Room Temperature Vulcanizing RTV Silicones

CREATING TOMORROW’S SOLUTIONS

ROOM TEMPERATURE VULCANIZING (RTV) SILICONES Material and Processing Guidelines 2 WELCOME TO THE WORLD OF RTV SILICONES

Contents

Section 1: Discover Diversity 5 Why WACKER silicones optimize the properties and process technologies of products in all major industries worldwide.

Section 2: Silicone Rubber – Basic Principles 13 Benefit from the chemical structure, components, classes and property profile of our silicone rubber in your application.

Section 3: Understanding RTV Silicones 21 Short cycle times for mass production or ease of processing with minimal investment – RTV silicones score with advantageous properties.

Section 4: Preparing for Production 31 Well begun is half done: From safety, systematic selection and working with RTV silicones to physical and chemical surface preparation methods.

Section 5: Processing RTV Silicones 41 How to process, modify and store silicones to achieve best results for industrial scale production.

Section 6: Spectrum of Technical Applications 57 Sealant adhesives, silicone gaskets, potting, encapsulation, coating and casting.

Section 7: Service 71 Excellent technologies need best-in-class services. WACKER ACADEMY, technical centers and e-business offer excellent expertise and support.

Section 8: Silicones A – Z 77 Facts and figures on RTV silicone rubber.

ELASTOSIL®, LUMISIL®, SEMICOSIL®, WACKER SilGel® and SILPURAN® are registered trademarks of Wacker Chemie AG.

3 4 Discover Diversity Discover

SECTION 1: DISCOVER DIVERSITY

Contents Why WACKER silicones optimize the properties and process technologies of products in all major industries worldwide.

1.1 Diversity in Silicones 6

1.2 Relevant Industries 8

1.3 General Properties of RTV Silicone Elastomers 10

5 1.1 DIVERSITY OF SILICONES

Technical innovations and rapid Room-temperature-vulcanizing (RTV) With more than 60 years' experience production development cycles are silicone rubber compounds are a train silicone technology and an routine in specialized industries. ditional core competence of WACKER. above-average commitment to R&D, However, to achieve market leader- The range of ready-to-use products WACKER has long become indispens- ship in the long-term, it is necessary focuses on numerous applications in able to its customers and participates to set standards. Modern silicone- the fields of bonding, sealing, potting, in their technical progress. This would based materials increasingly play encapsulation, coating and casting. not be possible without ongoing, a key role in achieving such goals. Equally broad is WACKER’s experi- confidential dialog and the exchange ence in processing techniques and of knowledge, experience and ideas, material requirements specific to these which powers a shared undertaking. applications, from DIY-scale right up to industrial production lines.

6 7

Discover Diversity 1.2 RELEVANT INDUSTRIES

E-Mobility

– Battery – Fuel cell – Electric motor – Cables and connectors Appliances

Automotive Electrical – Steam irons Industry Industry – Dishwashers – Drive train – Ovens – Seals and gaskets – Kitchen hoods – Dampers – Hobs

Mining and Exploitation Health Care

– Automotive electronics – Consumer electronics – Power modules

Electronics Aerospace

8 Applications Medical Medical Lighting – – – – – – Dental care care Wound and prosthetics Orthopedics Luminaires optics Secondary LED

Food Industry Food Industry Mold Making Molding and – – – – – Reproduction moldingReproduction Composite industry molding Prototype printing Industrial Construction molding

Transportation Energy Sector – – – – – – – Railway systems Railway industry Marine Utility vehicles Oil &gas Oil Hydro power Hydro power Wind Solar industry Rubber Industry

Applications

Fire Safety Safety Fire

– – – – Seat cushions seals duct pipe and Cable O-rings, profiles O-rings, Gluing and fixing ofsilicones

Discover Diversity 1.3 GENERAL PROPERTIES OF RTV SILICONE ELASTOMERS

Constant properties over a wide range of temperatures and frequencies

Excellent thermal resistance

Outstanding long- term thermal Outstanding stability from dielectric -50 °C to +180 °C properties WACKER RTV SILICONE ELASTOMERS

Very good High chemical adhesion to a purity and variety of biocompatibility substrates

Superior weathering, Excellent release UV and radiation properties resistance

10 Low Young’s resistance Very good chemical modulus

Long-lasting flexibility Chemical inertness

compatibility and compatibility environmental Selective gas permeability no harmful Excellent effects

moisture uptake surface and lowsurface Water-repellent physiological tolerance Excellent

Flame resistance 11

Discover Diversity 12

SECTION 2: SILICONE RUBBER – – Rubber Silicone PrinciplesBasic BASIC PRINCIPLES

Contents Benefit from the chemical structure, components, classes and property profile of our silicone rubber in your application.

2.1 Chemical Structure 14

2.2 Components of Silicone Rubber 15

2.3 Classes of Silicone Rubber 16

2.4 Properties of Silicone Rubber 18

2.5 Properties of RTV Silicone Elastomers 19

13 2.1 CHEMICAL STRUCTURE

Section of a Polydimethylsiloxane Chain

CH3

CH3 CH3 O Si

CH3 O

O Si CH3 CH3 Si O

O Si CH3 Si CH3 O CH3

CH3

From Quartz to Silicone The properties of silicone rubber PVMQ: PVMQ stands for a VMQ Silicones are made from quartz. While vary greatly depending on the organic in which a number of methyl this raw material is available in practi- groups and the chemical structure. groups have been replaced by cally unlimited quantities, the quality The organic groups may be methyl, phenyl groups. is crucial. WACKER converts quartz vinyl, phenyl or other groups. Accord- into silicon metal (Si) via a metallurgical ing to DIN EN ISO 1043-1, silicones FVMQ: FVMQ stands for a VMQ in process. Then silicon metal is trans- are classified as follows: which a number of methyl groups have formed into silanes by an integrated been replaced by fluorinated organic production system based on the MQ: MQ, or polydimethylsiloxane substituents. Müller-Rochow process. These silanes (PDMS), denotes a polymer in which are the precursors of polysiloxanes. two methyl groups are bound to the Polysiloxanes are macromolecules siloxane backbone. (polymers) comprised of a silicon- oxygen backbone with an organic VMQ: VMQ stands for a polydimethyl- moiety bound to the silicon atom. siloxane in which a number of methyl They are the basis for around 3,000 groups have been replaced by vinyl different silicone products. groups.

14 vulcanization. crosslinking, alsocalledcuringor polysiloxanes are required for peroxides, silanesorSiH-containing on theclassofsiliconerubber, stable cured product. Depending the uncured rubberinto amechanically A crosslinker isrequired to convert Crosslinkers and colorants. as crosslinkers, fillers,additives few additionalsubstances,such rubber generally containsonlya chain lengths,uncured silicone Besides polysiloxanes ofdifferent COMPONENTS OFSILICONERUBBER 2.2 Uncured, FilledPolymer Compared withCured Rubber Uncured polymerwithfiller.

Curing rubber's resistance to variousmedia. forexample,earths, increase thecured carbonate, talcumordiatomaceous finelypowderedQuartz, calcium These functionmerely asafill-up. Non-reinforcing fillers used. resins orcarbonblackcanalsobe although precipitated silica,silicone proven to beespeciallyeffective, ties oftheuncured andcured rubber. have acrucialinfluenceontheproper composition andquantityofthefillers elastic siliconenetwork.Thenature, Fillers are neededto reinforce the Fillers 100 m²/g).WACKER HDK areasBET surface (higher than filler ispyrogenic high silicawithvery The mostfrequently usedreinforcing Reinforcing fillers

elastic network. crosslinks (red) formsafilled, Polymer withchemical

® has

- silicone rubbercompounds. can easilybeblendedwithRTV broad range ofpigmentpastes that For thispurpose,WACKER offers a according to customers’ requirements. to opaquebutcanbe colored Silicone rubberisgenerally transparent Colorants color ofthecompound. this mayhaveanimpactonthefinal into accountbythecustomer as are naturally colored shouldbetaken The factthatsomeoftheseadditives ers andcolorants, forinstance. adhesion promoters, rheologymodifi- can becatalysts,heatstabilizers, processing atthecustomer. Additives the material properties andthe The choiceofadditivesdetermines linker and filler. may compriseonlypolymer, cross- Thus, asiliconerubbercompound determined bythepolysiloxane itself. because theessentialproperties are silicone rubberrequires fewadditives Compared withother elastomers, Additives

Silicone Rubber – Basic Principles 2.3 CLASSES OF SILICONE RUBBER

Uncured silicone rubber is converted into elastomer by vulcanization. Depending on the curing method, the viscosity of the base polymer and the curing temperature, silicones are classified as follows: • 1-part room-temperature vulcanizing silicone rubber (RTV-1) • 2-part room-temperature vulcanizing silicone rubber (RTV-2) • Liquid silicone rubber (LSR) • High-temperature vulcanizing silicone rubber (HTV).

1-Part Room-Temperature Vulcanizing Silicone Rubber (RTV-1) RTV-1 silicone rubber formulations are one-part, ready-to-use systems. They consist of polysiloxane, curing agent, fillers and additives. Right after application, the material starts crosslinking on contact with moisture in the air. Byproducts are released during curing. Crosslinking starts with the formation of a skin on the rubber surface and gradually progresses into the compound. Depending on the nature of the crosslinker, a small amount of acetic acid, amine or neutral byproducts, such as alcohol, is released during vulcanization. RTV-1 silicones are ideal for almost all sealing, bonding and coating applications. They are used in the automotive, construction, electrical engineering, electronics, health care, medical and textile sectors, among others, and also for household appliances.

16 health-care applicationsaswell making, householdappliances and applications. Theyare usedformold all sealing,bondingandcoating formulations are idealforalmost Like RTV-1 silicones,RTV-2 specialized properties. with extremely versatileandhighly production ofsiliconeelastomers silicone rubberproducts enablesthe The extensive ofRTV-2 portfolio remain flexible evendown to -110°C. down to -50°C.Somespecialgrades temperature, theyretain theirflexibility heat exposure upto 300°C.At low Some products evenwithstandshort 180 °C,evenafter long-term exposure. retain theirfullelasticityatupto silicone rubberinacured stage– Most RTV-2 siliconeelastomers – is classifiedas RTV-2. component heat-curingsiliconesand 25 °C).Thisgroup isknownasone- stored atroom temperature (20°Cto shelf life(upto 12months) when systems are characterized byalong at elevated temperatures. These slow-acting catalystandonlyvulcanize component systems thatcontaina be formulated aspremixed one- curing RTV-2 siliconerubbercan For process reasons, addition- and exposure time. controlled byadjusting theUVintensity light. Thevulcanizationtimecanbe can beflashvulcanized usingUV Special RTV-2 siliconerubbergrades not generate anybyproduct. requires aplatinumcatalystanddoes releases byproducts. Additioncuring an organotin catalyst andalways addition. Condensationcuringrequires reactions, either by condensationor are twodifferent typesofcrosslinking form ahighlyelasticmaterial. There room-temperature vulcanizing)and cure atroom temperature (RTV = vulcanize after mixing.Theyusually or kneadablecompositionsthat are pourable, two-part spreadable RTV-2 siliconerubberformulations Vulcanizing SiliconeRubber(RTV-2) 2-Part Room-Temperature

medical industries. engineering, food,health-care and construction, mechanicaland process ering, transmission anddistribution, in theautomotive, electricalengine- used inalarge varietyofapplications properties, HTV silicone elastomers are Thanks to theiroutstandingmechanical an elevated temperature. peroxides oraplatinumcatalystat rubber cures bymeansoforganic silicone Rubber(HCR).HTV silicone rubberorHighConsistency HTV siliconerubberisalsocalledsolid a solidconsistency. For thisreason, weight, whichprovides therubberwith polymer chainswithahighmolecular HTV siliconerubbercontainslong Silicone Rubber(HTV) High-Temperature Vulcanizing insulation andfire safety. weight construction,damping, used inapplicationssuchaslight- Silicone elastomer foamsare typically blowing agentascuringprogresses. release hydrogen, whichactsasa crosslink theliquidformulationand polysiloxane. Itsbasicfunctionisto content, namely, anSiH-rich characterized byahighcrosslinker Silicone foamformulationsare to temperature fluctuations. encapsulated componentsexposed They exert onlyminimalstress on especially fortheautomotive industry. fluorinated materials were developed as low-temperature flexible gelsand or woundcare. Specific gelssuch distribution, aswellhealthcare as: automotive, transmission and various applicationsinindustriessuch hardness range. Theyare suitablefor softvulcanisatesvery belowtheShore low crosslinking density andproduce are characterized byaparticularly curing RTV-2 silicones.Siliconegels foams are special typesofaddition- WACKER siliconegelsand and solar/photovoltaics. nology electronics, optoelectronics process engineering, lightingtech- mechanical engineering,industrial in anumberofindustriessuchas

Solid siliconerubberbar(standard supplyform).. engine andgearoils. contact withmediasuchasgasoline, ed LSR,whichishighlystableon automotive applications, like fluorinat- sector. WACKER offersspecific health care, babycare andthemedical and distribution,construction,food, electrical engineering,transmission mechanical andprocess engineering, a widerange ofindustries:automotive, Like allsilicones,LSRisalsousedin LSR curingprocess. byproducts are released duringthe is anSiH-functionalpolysiloxane. No and incomponentB,thecuringagent component Aisaplatinumcompound silicone, where thecuring catalystin system. LSRisanaddition-curing a two-componentandready-to-use is thuspumpableanddelivered as than solidsiliconerubber(HTV).It silicone rubberhasalowerviscosity processing advantages. Liquid mechanism provide themwithunique Their consistency andaddition-curing temperature-vulcanizing silicones. Liquid siliconerubbersare high- Liquid SiliconeRubber(LSR)

Silicone Rubber – Basic Principles 2.4 PROPERTIES OF SILICONE RUBBER

Inherent Properties Low-Temperature Flexibility versus High-Temperature Resistance Silicone elastomers are generally expected to be heat resistant 0 and flexible at both high and low temperatures. In contrast to organic -20 ACM FKM rubbers, this doesn't come at the expense of the other properties. SBR CR NBR CM/CSM EVM/AEM CO/ECO HNBR Silicone elastomers keep their -40 EPDM excellent mechanical properties Low-temperature flexibility [°C] flexibility Low-temperature over a very wide temperature range. NR These characteristics, intrinsic to -60 IIR BR silicone elastomers, are attributable Silicones Using heat stabilizers to the polymer and filler structure, not additives or surface treatment. -80 60 80 100 120 140 160 180 200 220 240 260

Temperature resistance* [°C] Material Benefits Resulting from the Polymer Structure * Temperature at which – after 1000 h – half of the initial elongation at break remains Silicones are characterized by a fully saturated backbone of alternating silicon and oxygen atoms. The Si-O links in the chain have an exceptionally Material Benefits Resulting from High Purity high bond energy of 451 kJ/mol. the Filler Structure Compared to many organic By comparison, C-C links have a bond Silicone rubber usually contains elastomers, silicones are considered energy of 352 kJ/mol. At the same pyrogenic silica as a filler, e.g., HDK® exceptionally pure. Thanks to their time, the Si-O chain mobility is very from WACKER. Since pyrogenic biocompatibility and physiological high. The organic side groups shield silica and polysiloxanes are very inertness, silicone elastomers are the backbone, so that the surface similar in structure, high compatibility highly suitable for applications in energy is low. is a given, resulting in the following the food, medical and electronic characteristics: sectors. For this purpose, WACKER This results in the following properties: • High transparency has developed the SILPURAN® • Excellent high-temperature • Good mechanical properties thanks brand and specific products within resistance combined with to effective polymer-filler interaction the ELASTOSIL® and SEMICOSIL® low-temperature flexibility • Flame resistance and non-toxic com- ranges. Some of these products • High resistance to chemicals bustion products in the case of fire. feature an exceptionally low ionic or and environmental influences volatile compound content. • Excellent weathering, UV and radiation resistance • Water-repellent surface.

18 • • • • RTV SiliconeRubber General Properties of RTV SILICONEELASTOMERS PROPERTIES OF 2.5 • • • • • • • • • • • • 150∙10 expansion approx. Coefficient oflinearthermal Low elasticitymodulus +180 °C properties between-50°Cand Only slightchangesinphysical load maybeevenlowerorhigher) or upto 270°C(peak temperature Specialty grades: downto -110°C resistance from -50°Cto +180°C; Outstanding long-term thermal High gaspermeability biocompatibility andChemical inertness High chemicalpurity grades are BfRandFDA compliant) Odorless andtasteless (many with lowmoisture uptake Water-repellent paired surface Easy to process Very goodchemicalresistance Fire retardant UV andradiation resistance High weathering, Electrically insulating temperature andfrequency range Constant properties overawide Outstanding dielectricproperties -6 –300∙10

-6

m/(m∙K)

• • • • • • Properties Typical Range ofMechanical (22 h/175°C)≥5% Compression set 5 -30N/mm Tear strength (ASTM D624): Elongation atbreak: 100-900% Tensile strength: 2-10N/mm² A, orjellylike Hardness: 20Shore 00-80Shore 3 g/cm³ Density: from 0.97upto over

• • • • • Main Property Options Pigmentable Wide range ofviscosityandhardness conductive Electrically insulatingorelectrically conductive Thermally insulatingorthermally (Self-)Bonding ornon-adhesive 19

Silicone Rubber – Basic Principles 20 SECTION 3: UNDERSTANDING RTV SILICONES

Contents Short cycle times for mass production or ease of processing with minimal investment – RTV silicones score Understanding RTV Silicones with advantageous properties.

3.1 RTV-1 Silicone Rubber 22

3.2 RTV-2 Silicone Rubber 24 Condensation-curing RTV-2 silicones 24 Addition-curing RTV-2 silicones 26 – Two-component silicones – One-component heat-curing silicones – UV-curing silicones

21 3.1 RTV-1 SILICONE RUBBER

Condensation Curing (RTV-1)

Step 1 R R X Si X X OH X OH X Si X X HO X Si R O Si R X HO OH X O Catalyst R Si X HO X OH X O X X X Si X Si X – volatile by-product (HX) O HO Si R R X X X Si R X R X OH X X O Si R X X Si R HO R OH OH O Si O X X X HO X Si X O R X Si R X Step 2 R R X Si X X R Catalyst, moisture R O O Si X R O – volatile by-product (HX) X X Si O Si R R X X R X X O Si R R O Si O X R X R X Si X O R X Si R X

ELASTOSIL® A: ELASTOSIL® E: ELASTOSIL® N: R1 O R1 X = N X = CH3 X = OR1 or N O R2 O R2

WACKER's RTV-1 silicone rubber Benefits at a Glance Curing Chemistry compounds are one-component ELASTOSIL® RTV-1 silicone rubber • Very easy handling and processing sytems that cure at room temperature. compounds consist of polysiloxanes, • Low capital investment for processing Thanks to their ease of processing, curing agents, fillers and, in some equipment ELASTOSIL® RTV-1 silicones are cases, solvents and/or additives. RTV-1 • Very good adhesion to a large variety preferred for applications involving silicones require air moisture to cure. of substrates thin layers and tolerable curing times. Since a small amount of by-products • Insensitive to inhibition by other However, these grades require long is released during crosslinking, substances curing times if applied in thick layers. RTV-1 silicones are classified as • Available as flowable, self-levelling This is not compatible with the short condensation-curing materials. or non-sag grades cycle times required in mass produc- The various RTV-1 systems available tion. In such cases, fast-curing RTV-2 at WACKER use different types of systems, one-component heat- curing agents. Small amounts of curing silicones, or UV-curing grades byproduct specific to the curing are more advantageous. In all other agent used are released during curing: cases, RTV-1 is appropriate. ELASTOSIL® E: acetic acid ELASTOSIL® A: amine ELASTOSIL® RTV-1 silicones owe ELASTOSIL® N: oxime or alcohol. their popularity to their advantageous properties in combination with minimal investment.

22 recommended. RTV-2 siliconerubbergrades are at all.Insuchcases,addition-curing out airaccess,curingisnotpossible 10 mm.Inclosedconfigurations with- applied siliconeshouldnotexceed from oneside,thethicknessof If airaccessislimited oronlypossible faster thecuringrate. The highertherelative humidity, the relative humidity. Theruleofthumbis: 1 −2mmperdayat23°Cand50% moisture, whichtypically averages is limited bythediffusionspeedof pound. Thecuringrate ofthesesilicones it gradually worksitswayinto thecom- ofthesiliconerubber,on thesurface Beginning withtheformationofaskin oncontactwithairmoisture.ber starts The crosslinking of RTV-1 siliconerub- Skin Forming andCuring

relative humidityatroom temperature. ELASTOSIL Exemplary vulcanizationrate of in diameter and18mmindepth. 23 °Cinaluminiumpansmeasuring24mm rubbers at50%relative humidityand Vulcanization rate ofvariousRTV-1 silicone Vulcanized FilmThickness Film Thickness [ mm ] [ mm ] 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11

® Relative humidity 85 Relative humidity 75 Relative humidity 45 Relative humidity 5 RTV-1 grades asafunctionof 1 2 3 4 5 6 7 8 9 10 11 12 5 4 3 2 1 1 2345

% % %

Time [d] Time Time [d] Time

using 0.3to 0.5vol. % ofCO In fact,optimalcuringisachieved curing tunnelmustnotexceed 60%. humidity inthecuringchamberor dioxide. Duringexposure, therelative enriched withupto 1 vol.%ofcarbon sure to ahumidatmosphere slightly grades canbeaccelerated byexpo- The curingrate ofELASTOSIL -15 °C. Curing isstillpossibledownto approx. thicker, blistering islikely to than 0.5mmthick).Ifthefilmsare any silicone material filmsare thin(less as high200°Cprovided thatthe The final temperature maybe byproducts and solvents to evaporate. be raised slowlyinorder to allowthe curing time.Thetemperature should temperature mayhelpto reduce some specialcases,increasing the by increasing therelative humidity. In can begreatly reduced time Curing speed ofRTV-1 siliconerubber. on theskinformingtimeandcuring Temperature hasaminoreffectboth Increasing Curing Speed layer within5minutes. full curingofa500micron silicone suitable forcoatingprocesses, enables This method,whichisparticularly 50 °C,e.g.,byusinginfrared lamps). with moderate temperature (40°Cto to 35%relative humiditycombined

occur. 2 at30%

® A

Understanding RTV Silicones 3.2 RTV-2 SILICONE RUBBER CONDENSATION-CURING RTV-2 SILICONES

Depending on the application, a catalyst. When components A and B Curing Chemistry WACKER offers different RTV-2 are mixed, the mixture immediately From the chemical point of view, the silicone rubber grades under starts curing to form the elastomer. crosslinking of condensation-curing the brand names ELASTOSIL®, The mixing ratio A:B varies between RTV-2 silicones is similar to the vul- SEMICOSIL®, LUMISIL®, SILPURAN®, 1:1 and 100:1, depending on the se- canization of RTV-1 silicone rubber. POWERSIL®, WACKER SilGel® and lected grade. For non-adhesive potting However, and in contrast to the latter, CENUSIL®. RTV-2 silicone rubber or mold making grades, the proportion the moisture required to properly cure formulations are two-component of component B typically ranges from RTV-2 silicones is already included in systems that cure when component 3 to 5 wt.% based on component A. the base compound (component A). A (also called rubber base or base In contrast, the two components of Condensation-curing ELASTOSIL ® compound) is mixed with compo- self-adhesive, condensation-curing RTV-2 silicone rubber therefore does nent B (also called curing agent). ELASTOSIL ® RTV-2 silicones typically not require air moisture to vulcanize, RTV-2 silicones can be further have an A:B mixing ratio of 8:1 making it suitable for substrate con- classified by curing systems. to 12:1. figurations where air access is limited. As the system crosslinks, alcohol is Condensation-curing ELASTOSIL® Benefits at a Glance released as a byproduct. This causes RTV-2 silicones consist of two compo- • Rapid curing, compared to RTV-1 a reduction in weight and three-dimen- nents. Component A contains polymer silicones sional shrinkage of the vulcanizate to and – if required – fillers and additives. • Crosslinking can be slightly accelerated the order of < 3 % by volume. Component B contains crosslinker and by raising the temperature • Curing of thick layers possible Important • Flowable, self-leveling or non-sag grades In condensation-curing RTV-2 silicone , • Self-adhesive grades with very good the rubber base (component A) and the adhesion to a large range of substrates curing agent (component B) always have • Almost insensitive to inhibition by the different lot numbers. presence of other substances

Condensation Curing (RTV-2)

RO RO Si OR OR OHOR OH H2O HO RO Si OR HO OH OR Catalyst HO OH H O – low volatile alcohol (ROH) OR 2 H2O HO RO Si OR OR OH OR RO Si OR HO OH OH OR HO

24 data sheetsofeachrubbergrade. ratios are specifiedin the technical ponent B).Catalysts andmixing (component A)to curingagent(com- justing theratio ofbasecompound fast orslowcuringagentandbyad- modified withinlimitsbychoosing a Potlife andvulcanizingtimecanbe have completely evaporated. be useduntilallbyproducts formed days. Thecured rubbershouldnot reached after somehoursoreven properties, however, are usually gels, whichremain tacky).Theultimate without feelingsticky(except silicone tack-free, i.e.,whenitcanbetouched time fortherubberto cure untilitis in thetechnical data sheetspecifythe figures forthevulcanizingtimequoted before thepotlifehaselapsed.The Therefore, thematerial shouldbeused ability andadecrease inplasticity. in viscositythatcausesreduced flow- Curing ischaracterized byanincrease ed asthepotlife. viscosity valueto double isoften quot- gaps), thetimerequired fortheinitial tronic small componentswithvery (e.g., encapsulatingelectricalorelec- requirementability isanimportant For applicationsinwhichgoodflow- pourable, spreadable orkneadable. the mixofcomponentAandBisstill maximum periodoftimeduringwhich The potlifeusuallyindicates the “vulcanizing time”(or“curing time”). by theparameters “potlife”and RTV-2 siliconerubberisdescribed The reactivity ofcondensation-curing Potlife andCuringTime

• in thefollowingeffects: excess ofcrosslinking agentresulting the resulting elastomer containsan curing agentishigherthanprescribed, significantly reduced. Iftheamountof casting resin componentsisalso resistance to swellingbysolventsor mechanical strength. Theelastomer’s softoreventackyrubberwithlow incomplete curingwillresult yielding ponent B)islowerthanprescribed, If theamountofcuringagent(com- used, theshorter thecuringtime. than 2minutes. The more curingagent however, thepotlifemustnotbeless limits. To ensure reliable processing, themixingratiovarying withincertain “slow” ora“fast”curingagentandby can beadjusted by selecting eithera to cure. Bothpotlifeandcuringtime 45 minutes, andtake 15to 90minutes have apotliferange between5and RTV-2 siliconeelastomers typically Condensation-curing ELASTOSIL Modifying CuringSpeed Typical Potlife Values asaFunction ofMixingRatiowithWACKER of therubber Decreased release properties [ min ] 0 5 10 15 20 25 30

ELASTOSIL 8 1012 ® RT 771 771 RT

ELASTOSIL

® RT 772 772 RT condensation-curing ELASTOSIL Depending onthetypeofcuringagent, Modifying AdhesiveProperties consistency reverts to asoftstate. the system eitherremains tackyorthe crosslinking reaction isreversed and At temperatures above80°C,the the siliconerubbercouldbedestroyed. fore curingiscompleted, otherwise however, mustnotexceed 80°Cbe- ed byraising thetemperature. Heating, Curing speedcanbeslightlyaccelerat- • • • T7x orWACKER agent from theWACKER hesive material bychoosingacuring ELASTOSIL it ispossibleto transform non-adhesive hesive ornon-adhesive.For example, RTV-2 siliconeelastomers are self-ad- Parts ELASTOSIL Parts on curing). is present, theelastomer willcarry Embrittlement (where airmoisture Reduced elasticity Increased hardness ELASTOSIL ®

Mgrades into self-ad- ® RT 77x to one part curing agent curing part one to 77x RT ® Catalyst T8xseries. ® RT 778 RT ® Catalyst T77 ® Catalyst

Understanding RTV Silicones 3.2 RTV-2 SILICONE RUBBER ADDITION-CURING RTV-2 SILICONES

Two-Component Silicones Benefits at a Glance Curing Chemistry Addition-curing RTV-2 silicone rubber • Rapid curing at room temperature, even Addition-curing RTV-2 silicones cure compounds consist of two compo- of thick layers via a completely different mechanism nents (A and B), one of which contains • Crosslinking is significantly accelerated to that of condensation-curing sys- polymer and crosslinker, the other, tems: when the two components are by raising the temperature polymer and a platinum catalyst. When mixed, the polymer, a platinum catalyst • No byproducts, no weight loss and the two components are mixed, they and the curing agent are brought into practically no shrinkage (< 0.1 %) on cure to form the elastomer product. contact with each other. During this curing reaction, the polymer chains cross- • Self-adhesive grades show very good The mixing ratio of addition-curing link through hydrosilylation of the vinyl adhesion to a large variety of substrates RTV-2 silicone rubber components is groups by means of the hydrogen- • Low compression set typically 1:1, 9:1 or 10:1 by weight, containing crosslinker. Since no • Excellent media resistance depending on the chosen product. volatile byproducts are formed during • Outstanding heat resistance A different ratio of A:B generally can crosslinking, there is neither a risk of • Available as flowable, self-levelling and lead to incomplete curing or to signifi- reversion of the crosslinking reaction non-sag grades cant changes in the product proper- at elevated temperature, nor chemical ties. Unless otherwise specified, the shrinkage of the vulcanizate due to two components must always have weight loss. the same batch number.

Addition Curing

Addition of H-siloxanes to C=C double bonds

Pt-catalyzed hydrosilylation

Uncured state Elastic state

26 120 °C),alsoknownaspost-curing. tively moderate temperatures (100°C- cone rubberforseveral hoursatrela- fastest byageingthecured RTV-2 sili- ties ofthevulcanizate canbereached ageing. However, theultimate proper ing thesubsequentroom-temperature to crosslink to extent acertain dur ately after curing,sometimescontinue fore usuallypresumed usableimmedi- relatively hightemperature andthere- days. Even vulcanizates produced ata their ultimate properties after some tion-curing siliconeelastomers reach Room-temperature-vulcanized addi- can beafewminutes. and 6hours.For specificgrades it typically variesbetween30minutes average potlifeofRTV-2 silicones the timeto cure untiltack-free. The quoted forthevulcanizing timespecify ity hasdoubledinvalue).Thefigures sible (orduringwhichtheinitialviscos- catalyzed mixofAandBis proces- period oftimeduringwhichthe potlife usuallyindicates themaximum “potlife” and“vulcanizingtime”. The tions isdescribedbytheparameters curing RTV-2 siliconerubberformula- silicones, thereactivity ofaddition- As withcondensation-curingRTV-2 Potlife andCuringTime

- PT 88(longerpotlife),orWACKER thumb, atemperature changeof potlife andcuringtime.Asaruleof ture shortens orprolongs boththe increasing ordecreasing thetempera- changing themixingratio. Therefore, altering thetemperature, butnotby can becontrolled additionallyby of addition-curingRTV-2 silicones silicone elastomers, thecuringrate Unlike condensation-curingRTV-2 Modifying CuringSpeed limits byaddingWACKER ing timecanbemodifiedwithinwide As analternative, the potlifeandcur potlife andcuringspeed. approx. 10°Chalvesordoubles tive flyer. information, pleaserefer to therespec- Catalyst EP(shorter potlife).For further

Inhibitor

- 27

Understanding RTV Silicones 3.2 RTV-2 SILICONE RUBBER ADDITION-CURING RTV-2 SILICONES

One-Component Heat-Curing Curing ELASTOSIL® RT 70x Grades Silicones 30 One-component, heat-curing silicones

[min ] 25 contain the same components as the 20 two-component addition-curing sili- 15 cones, but they are supplied as one- 10 part products with an appropriately 5 long shelf life at ambient temperature. 0 Consequently, they cure by the same 140 150 160 170 180 190 200 chemical reaction, but they need to be Temperature [°C] heated to the kick-off temperature in order to start the curing process.

The obvious advantage of one-component, heat-curing silicone rubbers is that they can be processed without Please Note mixing equipment, making them These products are ready to use and do suitable for both short and long pro- not accommodate fine adjustments of duction runs. They should be favored curing speed by adding inhibitor or plati- over two-component addition-curing num catalyst. Detailed information about silicones if mixing equipment for kick-off temperature and curing speed at two-component products cannot be various temperature levels are shown in purchased for technical or financial the corresponding technical data sheet. reasons.

The curing speed of one-component Benefits at a Glance heat-curing silicones depends only on • Low capital investment temperature. They are typically cured • Suitable for short production runs between 130 °C – 200 °C. Below this • Long potlife at room temperature range, crosslinking takes much longer • Short curing time at elevated or doesn’t even start. This may result temperature in poor adhesion, depending on the • Very good adhesion to many nature of the substrates. Conversely, substrates excessive temperature disturbs the • Available as flowable, self-levelling vulcanization process and impairs the and non-sag grades properties of the vulcanized material.

28 switched off. ing willcontinueeveniftheUVlightis molecules havebeengenerated, cur sible. However, onceactivecatalyst exposed to UVlight,itremains proces- speed. Aslongasthematerial isnot and thefaster thesilicone's curing number ofactivecatalystmolecules irradiation intensity, thegreater the – atroom temperature. Thehigherthe within afewsecondsto afewminutes then cure completely andrapidly – be irradiated forafewseconds.They WACKER’s UVgrades onlyneedto as foraddition-curingRTV-2 silicones. is basicallythesamechemicalreaction triggers thecrosslinking reaction. This required to activate thecatalystthat that isinactiveinthedark.UVlight silicones containauniquecatalyst curing silicones.Theseaddition-curing cesses, WACKER hasdevelopedUV- for large-scale series incustomer pro- In order to highproductivity support UV-Curing Silicones Please Note daylight. The UVcatalystisalsosensitiveto

- 29

Understanding RTV Silicones 30 SECTION 4: PREPARING FOR PRODUCTION

Contents Well begun is half done: From safety, systematic selection and working with RTV silicones to physical and chemical surface-preparation methods.

4.1 Safety First 32

4.2 Systematic Selection 33

4.3 Working with RTV Silicones 34

for Production for 4.4 Physical Surface Preparation Methods 36 Preparing

4.5 Chemical Surface Preparation Methods 38

31 4.1 SAFETY FIRST

Safety Precautions Some RTV silicone rubber grades may Cleaning Before processing WACKER products, also contain volatile solvents. Vapor In the case of spillage, remove the please carefully read the correspond- formed during vulcanization should not bulk of unvulcanized RTV silicone ing material safety datasheet available be inhaled. Additionally, the flamma- with a spatula, paper or a rag. from WACKER subsidiaries on request bility of all volatile compounds must Residues can then be washed off or visit WACKER’s website be taken into account. The work place with a grease-dissolving solvent, such (www.wacker.com) where detailed should be well ventilated in accor- as acetone, methyl ethyl ketone (MEK), information on all safety matters can dance with the threshold limit values isopropanol, white spirit or a similar be found. (TLV) of the respective country. isoaliphatic solvent. All tools should likewise be cleaned immediately For most WACKER silicone rubber If, despite all protective measures, after use before the silicone rubber products, standard industrial hygiene skin contact with uncured RTV silicone has vulcanized. When machines or precautions are adequate for handling rubber occurs, clean the affected dispensing equipment are cleaned, and processing. However, a few area immediately with soap and water. white spirit or similar non-polar products are classified as hazardous If uncured silicone rubber comes solvents are recommended. Ideally, and therefore require special safety into contact with the eyes, irrigate cleaning should take place before measures. them immediately with copious the rubber is fully vulcanized. amounts of water for several minutes. For example, curing agents for If the irritation continues, immediately Fully cured silicone rubber is removed condensation-curing RTV rubber seek medical advice. mechanically, if necessary, after using formulations may cause skin or eye a non-polar solvent to swell it. It can irritation after direct contact. Therefore, also be removed with any commercial- appropriate protective measures have ly available silicone remover or by to be taken. Additionally, condensa- pyrolysis. It is best to allow surplus tion-curing RTV silicones release small catalyzed mix to cure in the containers, amounts of amine, acetic acid, oxime after which it can be readily removed. or alcohol during vulcanization. Instructions for proper disposal of the uncured components and vulcanizates are also included in the respective safety data sheet.

32 SILPURAN SYSTEMATIC SELECTION 4.2 ELASTOSIL marketed underthebrand names WACKER offersdifferent RTVsilicones SilGel duction requirements best. system thatsuitsthe customer’s pro- It isessentialto select thesilicone ing properties maydiffersubstantially. Silicone Systems andProduction Requirements

Fast curing ® andCENUSIL • • • RTV-2 Silicones ® a suitablecuringagent by workingatelevated temperatures orselecting Rapid curingtimeofafewminutes isachieved to process them Dual-component metering equipmentisneeded systems thatvulcanize atroom temperature Addition-curing andcondensation-curing2-part ®

, POWERSIL , SEMICOSIL ® . Theprocess- ® ® , WACKER , LUMISIL

® ,

Comparative Curingofa10-mmSiliconeCoating [% ] 0 10 20 30 40 50 60 70 80 90 100 RTV-2

1 2345678910 • • • RTV-1 Silicones • • • One-Component Systems Air moisture isneededforcuring these rubbergrades canevenbeappliedmanually Simple metering equipmentsuffices to process them; One-component systems thatcure atroom temperature Curing isfast,sometimesonlyminutes Simple metering equipmentsuffices to process them One-component systems thatcure exclusively athightemperature RTV-1 Easy processing

Time [d] Time 33

Preparing for Production 4.3 WORKING WITH RTV SILICONES

The essential features of room- Rheological Behavior of Silicones temperature curing silicone rubber are:

• Consistency 100 • Viscosity 90 80

• Reactivity viscosity [%] 70

• Mechanical properties Relative dynamic • Dielectric properties 60 • Heat resistance 50 40 Consistency 30 According to the type, WACKER RTV 20 silicone rubber compounds can be 10 pourable, spreadable, non-sag or 0 0 2 4 6 8 10 kneadable. Depending on their con- Shear rate [s-1] sistency, they are suitable for a large Unfilled silicone (Newtonian) Filled silicone (pseudoplastic) number of processing techniques, including spraying, dipping, potting, encapsulating, silk-screen printing Relaxation Behavior of Various Filled Silicone Blends after Applying Shear Force 0.5 s-1 10 s-1 0.5 s-1 and automated application of sealing 100 beads. Non-sag (also called non-slump) 90 grades differ from spreadable grades 80 in their reduced flowability: up to a viscosity [%] 70 specific maximum thickness (usually Relative dynamic 60 10 mm), they neither sag nor run off 50 from a vertical or inclined surface. 40 The consistency of kneadable com- 30 pounds is usually characterized by 20 quoting the penetration. It is deter- 10 mined by using a standard cone under 0 a specific load and given in mm/10. 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 The higher the penetration value, the Time [s] softer the compound. Thixotropic Non-thixotropic

Viscosity The suitability of a compound for a compound. The viscosity of RTV Newtonian fluids have a constant particular processing method is dicta- silicone rubber compounds is usually viscosity independent from the ted by its rheological properties, for between 500 and 2,000,000 mPa⋅s. shearing. In non-Newtonian fluids, example, its viscosity. The viscosity The viscosity further depends on the viscosity depends on the of a material describes its flow charac- the temperature. Precise temperature shearing and therefore the viscosity teristics. The higher the viscosity, control during measurement is needs to be quoted for specific the less pourable or the stiffer the therefore essential. shear rates.

34 relative humidityupto 80%. can beaccelerated byincreasing whereas thecuringofRTV-1 grades alyst, mixingratio andtemperature, can bemodifiedbythechoiceofcat- RTV-2 siliconerubberformulations ing grades). Thereactivity of temperature (one-component heatcur potlife /curingtime(RTV-2) orkick-off either skin-formingtime(RTV-1) or of RTV siliconesischaracterized by As describedabove,thereactivity Reactivity e.g., pumping,stirring,ormixing. depend onthepreliminary treatment, silicone rubberformulationstherefore The rheologicalproperties ofthixotropic time, thisbehavioriscalledthixotropic. after shearing,butis retarded over If viscositydoesn’trecover immediately has beenmeasured. gether withtheshearrate atwhichit tonecessary quote theviscosity to- behavior. Insuchcases,itisalways non-Newtonian and shear thinning RTV siliconerubberformulationsshow compound after application. Many shearing, forexample theflowof underloworzerothe performance given forlowshearrates describes stirring, knife-coating,etc.Theviscosity for example during metering, extrusion, the compoundunderintense shearing, characterizes theflowproperties of The viscositygivenforhighshear-rates

so-called high-strength silicones. and atensile strength of>5MPa are with atear strength of>10N/mm standardized tensile tests. Materials stress-strain graphs determined by elongation atbreak are derivedfrom Tensile strength, tear resistance and softer thevulcanizate. penetration: thehighervalue, A hardness, thereverse istruefor hardness forbothShore 00andShore Whereas highervaluesmean greater tion isquoted forevensofter materials. softmaterialsfor very andthepenetra The Shore 00indentationscaleisused surement oftheShore Ahardness. silicone gelsistoo lowto allowmea the hardness ofprintingpadsor the harder thecured rubber. However, A scale:thehigherShore Avalue, tion andisusuallyquoted ontheShore The hardness ismeasured byindenta set. elongation atbreak andcompression ness, tensile strength, tear resistance, ties ofcured RTV siliconesare hard The mostrelevant mechanicalproper counterparts. able thantheircondensation-curing addition-curing grades are more suit tions causinghighmechanicalstress, the typeofcuringsystem. For applica are determined to someextent by The properties ofvulcanized silicones Mechanical Properties

------into consideration. mechanical strength mustbetaken degradation, discoloration orlossin even highertemperatures butthen These grades canbeexposed to tures ofupto 270°C. stability inthelong-term attempera- silicone grades showremarkable pose. Heat-stableWACKER RTV are suitableforthispur particularly um) andsomecarbon blackgrades Metal oxides (suchasofiron ortitani- silicones needto be heat-stabilized. even forprolonged periods,RTV to atemperature higherthan200°C, applications, where are parts exposed joints. For demanding particularly on thebondingstrength ofRTV silicone stress hasnoconsiderable influence ties donotalter significantly, andheat to 180 °C:proper mechanical the hightemperaturescontinuous ofup silicone rubbereasilywithstands elastomers. Properly cured RTV far superiorto thatof mostorganic The heatresistance ofsiliconesis Heat Resistance 100 kV/mm(IEC60243-1). thickness) ranges from 20kV/mmto of acured siliconespecimen(1mm system. Thebreakdown voltage mechanical properties andcuring independent ofconsistency, reactivity, of siliconeelastomers are largely conductive. Thedielectricproperties Silicones are basically not electrically Dielectric Properties curing grades showvaluesbelow20%. compression set, whereas addition- curing siliconesusuallyexhibit ahigh silicone elastomer. Condensation- value, thehigherresilience ofthe specimen thickness.Thelowerthe given asthepercentage oforiginal when aforce isremoved anditis the permanentdeformationremaining The compression setisdefinedas

Preparing for Production 4.4 PHYSICAL SURFACE- PREPARATION METHODS

Surface Cleaning Addition-curing RTV silicones, how- Regardless of the type of silicone to The crosslinking agents used in ever, are much more sensitive. Small be used, the surfaces to be bonded condensation-curing silicones often amounts of surface contaminants must be clean, dry and free from act as adhesion promoters. Therefore may cause adhesion problems or grease, waxes or other contaminants. RTV-1 silicones and condensation- even inhibition. Examples of inhibiting Suitable cleaners include low-boiling curing RTV-2 silicones are robust pollutants are materials containing solvents (caution: flammable) that adhesives or sealants: they adhere sulfur or amino groups, plasticizers, evaporate without leaving any residue, very well to many substrates and urethanes and organometallic com- e.g., acetone, isopropanol or aliphatic are relatively tolerant to surface pounds – especially organotin com- solvents. Modern cleaning techniques, contamination. pounds. If a substrate’s ability to in- such as dry-ice blasting or laser hibit the silicone’s cure is unknown, a cleaning, are also applicable. small-scale test should be run to as- sess compatibility.

36 are notself-adhesive. addition-curing RTV-2 silicones,which when joiningsubstrates bymeansof bonding. Thisisalsomandatory Pyrosil pressure plasma,flametreatment or pretreatment (corona discharge, low PMMA or PPS compounds,require polymers, polycarbonate, ABS, substrates, suchaspolyaliphatic silicone. However, more demanding to bebondedwithaself-adhesiveRTV (PA, PBT, polyester grades, etc.)are thermoplastics withpolarsurfaces aluminum, stainlesssteel orselected when glass,ceramic materials, Usually pretreatment isnotneeded PretreatmentSurface ® treatment) to obtainreliable

spirit orasimilaraliphaticsolvent. cleaned withe.g.,isopropanol, white abrasive shouldbe dust,thesurface metal, sandblasting.After removing the with sandpaperor, inthecaseof mayrequiresurfaces slightroughening Very smoothplasticandmetal Please Note migrate. bitumen oroilswithatendency to that containplasticizers, anti-oxidants, permanent bondwithsomesubstrates might bechallengingto achievea Despite physicalpretreatment, itstill

Preparing for Production 4.5 CHEMICAL SURFACE- PREPARATION METHODS

Perfect Adhesion Special Characteristics Primer Application Step by Step Some ELASTOSIL® RTV silicone • Excellent adhesion promotion to 1. The substrate must be clean rubber formulations are inherently various substrates (free of dust, grease, oils or other self-adhesive, such as all RTV-1 • Solvent based, thus suitable for contaminants) and dry. Very silicone rubber grades. Others contain various coating techniques like smooth surfaces should be rough- adhesion promoters to facilitate dipping, brushing or spraying ened, cleaned and degreased as adhesion to a wide range of substrates. • Miscible with organic solvents described above. Sometimes, though, priming is for further dilution 2. The (diluted) primer is applied advisable and even essential for by spraying, dipping or brushing perfect results. There is no “universal primer” suitable (thin coat with no bubbles). For for every kind of application. To make absorbent surfaces, priming must Primer a proper choice, both the kind of be repeated several times. The adhesion of RTV silicones can be substrate and the RTV silicone rubber 3. The primed parts must be air dried enhanced by preparing the surfaces grade must be considered for at least 15 minutes. beforehand with a primer. Primers are 4. The pretreated surfaces are stored low viscous formulations of reactive Please Note in a clean and dust-free place for silanes and/or siloxanes. While drying, A too-thick primer layer can reduce minimum 1 hour and maximum they form a resinous silicone film, to adhesion. In order to reduce the layer 12 hours in order to allow the cross- which the RTV silicone rubber bonds thickness, it is recommend to dilute the linking of the primer. Alternatively, during curing. Primers thus promote primer directly before use with a nonpolar the primer can be baked for 15 to adhesion between the RTV silicone solvent (white spirit or a similar aliphatic 40 minutes at 100 to 150 °C. and the substrate. solvent) in a 1:1 or 1:2 ratio (primer : solvent). Please Note Primers are sensitive to moisture. Opened containers should always be stored in a cool, dry place with regular checks for cloudiness or white sediment. If there is a white precipitate, the primer should not be used.

Primer Selection Kinematic Viscosity Color Solvent Suitable for in mm²/s WACKER® Primer G 790 1 Yellowish Isoalkanes/ General purpose Toluene WACKER® Primer G 790 1 Yellowish Isoalkanes General purpose TOLUENE FREE WACKER® Primer G 791 5,200 / 120 Opaque Isoalkanes Silicone-to-silicone bonding WACKER® Primer G 795 2 Yellowish Isoalkanes General purpose (preferably for addition-curing RTV-2 silicones) WACKER® Primer G 718 1 Orange Acetone/ Bonding RTV-1 silicones to Toluene thermoplastics and metals WACKER® Primer FD 2 Yellowish Acetone/ Porous, absorbent surfaces Toluene WACKER® Primer FMP HC 0.8 Yellowish Isoalkanes Substrates with Zn-based coatings WACKER® Primer AV A/B 5 / 100 Yellowish Isopropanol Wood and aluminum (preferably for addition-curing RTV-2 silicones)

38 to airmoisture. pails, andtheycure onexposure to-process or intubes,cartridges These materials are suppliedready- prerequisite foradurable, firmbond. pre-coat thuscreating surfaces, the rubber compoundscanbeusedto Similar to primers,RTV-1 silicone Multicomponent Techniques * for medical applications medical * for ELASTOSIL SILPURAN ELASTOSIL ELASTOSIL ELASTOSIL RTV-1 SiliconesSuitableforMulticomponentTechniques ® ® ® ® ® 4200* N10 N2010 E43N E41 Consistency Self-levelling Flowable Flowable Self-levelling Flowable

Type Acetoxy Oxime Alkoxy Acetoxy Acetoxy 5. 4. 3. 2. 1. Step byStep Application prior to processing. further The material mustbe fullycured 80 °Candathighhumidity. much faster between 50°Cand 12 to 15hours.The process is temperature isachievedwithin optimum bondstrength atroom Depending ontheairhumidity, the in acleananddust-free place. The pretreated are surfaces stored at least15minutes. coated must beairdriedfor parts If asolventhasbeenused,the grade) inorder to easeprocessing. (white spiritorasimilaraliphatic non-polar, water-free solvent rubber canbediluted witha If required, theRTV-1 silicone screen printingorspraying. with acoatingknife,bybrushing, thickness of0.5mm,forexample should beappliedto amaximum The (diluted) RTV-1 siliconerubber necessary. cleaned anddegreased if Substrate mustbecarefully Color Translucent Translucent Translucent Translucent Transparent

Solvent None None None None Toluene

Please Note with atendency to migrate. cizers, antioxidants, bitumenandoils that containsubstancessuchasplasti- permanent bondwithsomesubstrates still mightbechallengingto achievea as chemicaletching.Furthermore, it special pre-treatment methods,such Fluorinated thermoplasticsrequire recommended for Not Surfaces proneSurfaces to corrosion Addition-curing RTV-2 silicones Addition-curing RTV-2 silicones proneSurfaces to corrosion proneSurfaces to corrosion Addition-curing RTV-2 silicones

Preparing for Production 40 SECTION 5: PROCESSING RTV SILICONES

Contents How to process, modify and store silicones to achieve best results for industrial scale production.

5.1 Basic Guidelines 42

5.2 Manual Mixing 44

5.3 Air Removal 45

5.4 Fully Automated Material Processing 46

5.5 Post-Treatment 47

5.6 Modifying Silicone Rubber 48

5.7 Storage 52

5.8 Trouble Shooting 53 Processing Processing RTV Silicones

41 5.1 BASIC GUIDELINES

WACKER RTV silicones can be processed in many different ways. Since the choice of material, application method and processing equipment always depends on a number of factors, the following questions should be clarified first: • What is the application? • What are the substrates involved? • What are the material requirements in terms of the chemical and physical properties of the cured rubber? • Is a liquid, self-levelling or non-sag RTV silicone formulation the right choice? • Can a two-component grade be processed, or is a one-component material mandatory? • Which curing temperature is preferred? Do the substrates involved allow curing at temperature levels higher than room temperature? • Is adhesion required? If so, will a surface pre-treatment be necessary? • What equipment is available and how much investment is required, if any? • What experience/expertise is available for the particular process? • What type of geometry does the part have? Complex or simple? • How large is the required production series?

42 • • • • • • • • following basicequipment: quantities, werecommend the For manualprocessing ofsmaller Manual Equipment isopropanol). spirit, acetone, methyl-ethyl-ketone, Grease-dissolving solvent(e.g.,white desiccator) and vacuumbox (e.g.,glassorplastic Vacuum pump(oilorwater-jet pump) compounds: roll millorkneader) with paddlestirrer (forkneadable Mechanical stirrer, e.g.,electricdrill formulations Brush to applylowviscous Metal orplasticspatula Pipette ordisposable syringe plastic (preferably polyethylene) Clean beaker madeofmetalor Balance

request. A comprehensive listisavailableon equipment forWACKER RTV silicones. offer automatic mixing andmetering A large numberofmanufacturers bonding. as jetting,vacuumpottingor modern applicationtechniques, such and spraying islikewise possiblewith casting, dispensing,screen printing low pressure. Automated dipcoating, ing automatic metering systems at compounds canbeprocessed us- properties, RTV siliconerubber Depending ontheirspecificrheological Automatic Metering Equipment

their optimumflowproperties. use isbeneficialandcanoften restore during longstorage. Stirring priorto Some grades maythicken slightly • • • thoroughly stirred: pigments, thecompoundsmustbe uniform distributionofthefillersor to colorliquidgrades. To ensure pigments whichhavebeenused storage. Thesameappliesto fillers mayslowlysedimentduring Depending ontheformulation,such or improved oilresistance, etc. conductivity, elevated hardness in order to obtainhighthermal contain large quantities offillers Some pourable RTV siliconegrades for Processing Preparing theComponents vessels ofthemetering equipment. During thetimespentinsupply equipment original packaginginto themetering Prior to transfer from the preferably usingamechanicalstirrer from theoriginalpackaging, Prior to processing onceremoved

Processing RTV Silicones 5.2 MANUAL MIXING

Flowable RTV-2 Silicone Grades Manual mixing of two-component RTV silicones is only recommended for flowable compounds. For econo- mical, large-scale processing, the use of automatic metering equipment, which includes static or dynamic mixers, is recommended.

To mix small quantities, a spatula is adequate. If the amount is relatively large, a mechanical stirrer has to be employed. Suitable stirring tools are paddle stirrers with perforated, inclined blades. High-speed stirrers using toothed discs (dissolvers) are also suitable.

The equipment employed must always be scrupulously cleaned before processing addition-curing RTV-2 Important Non-Slump RTV-2 Silicone Grades silicones. It is mandatory to use If the viscosity of the two components Small quantities of non-sag grades different equipment for component differs greatly, the less viscous compo- are best processed from side-by- A and B, as even traces of catalyst nent tends to accumulate on the wall side cartridges using a pneumatic will cause the component containing of the beaker during mixing. This might gun and a static mixer. Small-scale the crosslinker to cure. result in an unevenly cured product. trial mixtures can be prepared in the Therefore, it is necessary to scrape same way as described above for It is also mandatory that the two the beaker wall with a spatula at short flowable grades. However, the risk components are thoroughly mixed intervals. This also applies when a of entrapping air and thus creating in the prescribed ratio to form a mechanical stirrer is used for mixing. blistered vulcanizates has to be taken homogeneous compound. If the into account. For processing large components have different colors, quantities of shear thinning/thixotropic they should be mixed until the grades, we recommend using auto- compound is totally streak free. matic dosing equipment, which can be run with either static mixers or dynamic mixing heads, depending on the RTV silicone grade.

44 AIR REMOVAL 5.3 slightly byasmallshotofair. overflow, thevacuumcanbebroken the rim.However, ifitappearslikely to mix usuallycollapsesbefore itreaches the containerisadequate, therising vacuum isapplied.Ifthevolumeof rubber willfoamextensively whenthe volume oftheproduct, asthesilicone deaeration shouldbefourtimesthe The capacityofthecontainerfor suffuce. available, awater-jet pumpmightalso low temperature (lessthan10°C)is such lowpressure. Iftapwater atvery An oilpumpshouldbeusedto obtain at reduced pressure (10 in avacuumbox oravacuumcabinet to 200,000mPa∙s) canbedeaerated (i.e., products withaviscosityofup RTV siliconerubbercompounds compound priorto curing. Pourable air mustberemoved from therubber crosslinking, absorbedandentrapped If voidsorbubblesappearduring within therespective potlife. ating, allowingentrapped airto escape low enoughviscosityto beself-deaer pounds onlyoccasionallypresent a compound. RTV siliconerubbercom- unavoidably introduced into therubber system, amount ofairis acertain done undervacuumorinaclosed vulcanizates. Further, ifmixingisnot often istheroot causeforblistered Air isreadily soluble insilicones,which

- 20 mbar).

during mixing. static mixers prevents airentrapment equippedwithside-by-side cartridges Using automatic dispensinglinesor cannot bede-aerated byevacuation. high viscousornon-sagcompounds In contrast to pourable compounds, recommended. dispensing inavacuumcabinetis the complete absence ofanyvoids, demanding applicationsrequiring automatic deaeration devices.For silicones are often equippedwith cessing flowabletwo-component Automatic dosingsystems forpro- rubber. to remove alltheairtrapped inthe the vacuumwasnotstrong enough either thecontainerwastoo smallor has notcollapsedcompletely bythen, for curingmightescape.Ifthemix some volatilecompoundsessential take more than10minutes, otherwise The deaeration process shouldnot full vacuum. the mixcollapsescompletely under This step shouldberepeated until

Processing RTV Silicones 5.4 FULLY AUTOMATED MATERIAL PROCESSING

Processing large quantities on an gear pumps, helical pumps or volu- Dosing industrial scale requires automatic metric piston systems, to the mixing The (mixed) material is applied to a metering equipment fitted with follower unit, which can be either a static or substrate via a robot-mounted dis- plates allowing the dispensing directly a dynamic mixer. pensing nozzle. Dispensing systems from the original container. Despite with fixed nozzles, where a robot their widely differing viscosity, flowable Static mixers do not have moving moves the construction parts, are as well as non-slump RTV silicones parts, and the material is homogenized also commercially available, as are can be metered and mixed, if via fixed mixing elements on the inte- multi-nozzle or jetting systems. Modern applicable, in the same way. rior. Dynamic mixers support homog- dosing machines offer accurate control enization with moving parts. The length of both the metering and dispensing Important and diameter of the static mixer as process. Metering equipment using pressurized well as the number and shape of the air is disadvantageous. There is a signifi- mixing elements influence the mixing Vulcanization cant risk of generating bubbles in the quality. The most suitable mixer should The applicable temperature and vulcanizate due to the high solubility of be chosen, depending on the rheologi- resulting curing time strongly depend air in silicone. For silicone foams, however, cal properties and the flow rate of the on the type of RTV silicone, the volume the admixing of air to the components RTV silicone grade. of material applied and the assembly can improve the silicone foam structure. The homogeneous color of the com- configuration. RTV-1 silicone rubber pound helps identify problems arising is usually cured at room temperature when feeding one of the two compo- (20 °C to 25 °C) and 40 % to 60 % Mixing nents or with the mixing element. In relative air humidity. Due to the low RTV-2 silicones require mixing systems. case of prolonged production breaks, vulcanization speed and the small The metering units pump component flushing the mixing unit with the base amount of by-products released, A and component B in the specified component, which does not contain ventilated curing cabinets with air ratio directly from the pails or drums the crosslinker is recommended. moisture control are recommended. and feed them, supported by additional Process cycle time may vary between a couple of minutes and days. Mixing and Metering Equipment for RTV Silicone Rubber Condensation-curing RTV-2 silicones usually don’t require air moisture control. They are preferably cured at   room temperature. Optionally, curing speed can be slightly accelerated by heating up to a maximum of 70 °C. Ventilation of the curing site is  Material supply units for recommended to ensure the safe component A and component B removal of the evaporated by-pro- (including piston pumps and ducts. The process cycle time follower plates, if necessary) typically ranges from minutes to

   hours. Addition-curing RTV silicones Metering pumps can have a different curing time and (e.g., gear pump or helical curing temperature. Some grades can pump) be cured at room-temperature within hours, while others are preferably  vulcanized at a higher temperature Dosing unit with mixing device (e.g., dynamic mixing head or (80 °C to 200 °C) in order to substan-  static mixer) tially shorten the curing time down to minutes. Exactly how much time is   required depends on the grade, on the Metering nozzle heat capacity of the substrate(s) and on the heat transfer rate. Suitable heat sources include heated metal molds, circulating air ovens and IR tunnels.

46 POST-TREATMENT 5.5 • • • • • following typicaleffects: in thevulcanizate, causing byproducts mayremain entrapped During crosslinking, somevolatile Silicone Rubber Condensation-Curing recommendations mustbefollowed. BfR orE.P. 3.1.9 ple. Insuchcases,therelevant FDA, tact ormedicalapplications,forexam - meet legalrequirements forfood-con- nents), whichisessentialinorder to ing, orlow-molecularpolymercompo- ucts resulting from condensation-cur also to remove volatiles(e.g.,byprod- improved mechanical properties but notonlytois performed achieve for adefinedtime(post-curing).This days, orexposure to hightemperature ageing atroom temperature forseveral Post-treatment usuallymeanseither temperature. permanent shrinkage,evenatroom Long-term weightlossand sion (dueto aminesoracetic acid) The riskofplasticsandmetalcorro- resistance Significantly reduced media a compression setofupto 100% A lowlevelofresilience, paired with (> 90°C) is exposed to elevated temperature Reversion whenthesiliconerubber

or exceed 200°C. but itshouldnotfallbelow100°C perature ofuseisrecommended, temperature similarto thefuture tem- exposing thecured siliconeto a rubber hasset.Duringpost-curing, a numberofhoursafter thesilicone out additionalheattreatment for In suchcases,itisadvisableto carry minimal compression set,isrequired. mechanical properties, especiallya improvement oftheelastomer’s recommendedis nevertheless ifan ately after heat-curing.Post-curing byproducts, theycanbeusedimmedi- curing rubberdonotcontainvolatile Since thevulcanizates ofaddition- Addition-Curing SiliconeRubber as possible. exposedwith asmuchofthesurface the vulcanizate shouldbestored open Duringthisageingperiod,surface). thickness to thenearest exposed (rule ofthumb:approx. 6hourspercm several hoursatamaximumof70°C to thenearest exposed orfor surface) approx. 24hourspercmthickness at room temperature (ruleofthumb: zates byageingthemforseveral days removed from freshly cured vulcani- Volatile byproducts are completely

3. Post-curing time deformed bytheirinherent weight. other andsuchthattheyare not if possiblewithoutcontactto each on aperforated plate orwire mesh, Large siliconeitems shouldbeput the siliconesidefacinghotairflow. shouldbepositionedwithThe parts intheoven 2. Placingtheparts must beensured duringthistime. post-curing period.Goodventilation components escapewithintheinitial be considered). Mostofthevolatile deflagration (the explosion limitsmust kg ofsiliconeto prevent ariskof rate of100-120lperminute and tion, fresh airmust besuppliedata post-curing. To ensure reliable opera- to beremoved from theovenduring acid, oximes etc.), whichalsohave volatiles (e.g.,alcohol,amines,acetic cular siloxanes or otherflammable consist predominantly oflowmole- supply. Thevolatilecomponents circulating-air oven withfresh air Post-curing mustbedoneina 1. Fresh-air supply The RightWay to Post-Cure aging and/orembrittlementcanoccur. undesirablehours, otherwise thermal be conducted fornotmore than8 heating-up phase,post-curingshould However,silicone part. followingthe increases withthethicknessof loss. Therequired post-curingtime be checked bymeasuringtheweight Thevolatilescontentparts. should the optimumconditionsfor Tests to shouldbeperformed define

Processing RTV Silicones 5.6 MODIFYING SILICONE RUBBER

WACKER offers various additives For addition-curing RTV silicones, Properties of Silicone Elastomers in order to modify properties such WACKER has developed WACKER® Usually WACKER® AK silicone fluids as viscosity or reactivity or to adjust VISCOREGLER 64 DILUTING AGENT are intentionally added to reduce the the elastomer’s properties. in order to minimize the impact of the original hardness of a cured rubber diluent on the mechanical properties. for a specific purpose, for example Viscosity This solvent-free, rheologically to obtain a very soft vulcanizate for The rheological properties of RTV effective additive contains reactive printing pads. By increasing the quan- silicones can be altered over a wide groups and is incorporated into the tity of silicone fluid, hardness, tensile range using various additives. For silicone network during addition- strength and tear strength decrease, example, viscosity can be lowered by curing. It facilitates significant lowering while elongation at break increases. adding a low-viscous WACKER® AK of the addition-curing RTV silicone silicone fluid. The viscosity decreases rubber formulations' viscosity, while Depending on their viscosity, the in proportion to the amount of fluid the mechanical properties of their silicone fluids have a tendency to added. vulcanizates remain more or less separate, since they cannot chemically constant. link to the vulcanized silicone rubber Important network. As a rule of thumb, the In order to increase the viscosity of highest migration rate is observed for WACKER® AK silicone fluids do not flowable RTV silicone formulations, silicone fluids with a viscosity between crosslink and therefore behave like a a few percent by weight of pyrogenic 10,000 mm2/s and 50,000 mm2/s. plasticizer, changing the cured silicone silica (such as WACKER HDK® N 20) In contrast, silicone fluids with a rubber’s mechanical properties to a can be added. A more convenient viscosity below 200 mm²/s show a certain extent. Adding silicone fluids in method is to use thickening additives, very low tendency to bleed. Hence, large quantities (over 20 %) may reduce thereby transforming certain readily it is possible to tune the vulcanizate’s the vulcanizates’ resistance to swelling flowable formulations into nonsag properties not only in terms of hard- agents (solvents, oil, lubricants), while ones. While adding 0.3 - 0.5 % ness, but also in regard to its oil potlife and curing time can increase as WACKER® STABILIZER 43 confers bleeding capability, just by choosing a result of the crosslinker dilution. excellent non-sag properties to a silicone fluid with the “right” However, if not more than 5 % by weight addition-curing RTV silicones, 1 - 2 % viscosity. is added, the influence of the silicone of WACKER® THIXOTROPIC ADDITIVE fluids is generally modest. C is required for condensation-curing RTV silicone grades. The corresponding TDS display all relevant details.

Additives that Modify the Viscosity and Consistency of RTV Silicone Rubber Product Increasing Lowering Softening Oil Bleeding Viscosity Viscosity Effect Effect WACKER® AK 35   WACKER® AK 1000   WACKER® AK 20000   WACKER® VISCOREGLER 641  WACKER HDK® N 20  WACKER® STABILIZER 431  WACKER® THIXOTROPIC ADDITIVE C2 

1) For addition-curing RTV silicone rubber formulations only 2) For RTV silicone rubber formulations only

48 hibitor PT88oradditional WACKER graphs. display allrelevant detailsincluding Catalyst EP. Thecorresponding TDS broad limitsbyaddingWACKER formulations canbevariedwithin addition-curing RTV siliconerubber The potlifeandvulcanizationtimeof 2) needto bechanged. curing catalyst(componentBofRTV- the mixingratio (RTV-2) ortheT-series tive airhumidity;RTV-2: temperature), curing conditions(RTV-1: levelofrela- or slowdownthecuringprocess, the by additives.Inorder to speedup rubber grades cannotbemodified condensation-curing RTV silicone The vulcanizationcharacteristics of Curing Properties

® In-

% ofWACKER In manycases,addingupto 0.25wt. inhibition isreduced atthesametime. As apositiveside-effect,theriskof i. e.,potlifeandcuringtimedecrease. lations increases theircuringspeed, addition-curing siliconerubberformu- tion’s robustness towards inhibition. crease curingspeedandtheformula- mixture) issufficient tosignificantly in- the total weightofthe siliconerubber Adding WACKER WACKER Please Note alyst EP, dependingonthequantityused. ly brownish uponaddingWACKER compounds maydiscoloryelloworslight- ponent AandcomponentB.Transparent the catalysedmixture madefrom com- platinum catalyst,or–alternatively –to either to thecomponentcontaining WACKER ® ® Catalyst EPshouldbeadded Catalyst EP ® Catalyst EP(basedon ® Catalyst EPto

® Cat

- WACKER WACKER adding upto 0.5wt.%of WACKER curing timeincrease. Inmostcases, formulations. Consequently, potlifeand of addition-curingsiliconerubber extender thatdiminishesthereactivity ensure complete vulcanization. elevated temperature to isnecessary strongly retarded curingoccurs,an at room-temperature fordays.Where modified RTV-2 siliconecompound lives andmightdelaythecuringof Inhibitor PT88result longpot invery because large quantitiesofWACKER exceeding theupperlimitof1wt.%, ing speed.We strongly discourage is sufficient tosignificantly reducecur weight ofthesiliconerubbermixture) Inhibitor PT88(basedonthe total Please Note ponent AandcomponentB.WACKER the catalysedmixture madefrom com- ing thecrosslinker, or–alternatively –to added eitherto thecomponentcontain- will turnbrownish. thecompoundlyst, becauseotherwise component containingtheplatinumcata- Inhibitor PT88mustnotbeadded to the WACKER ® ® ® Inhibitor PT88shouldbe Inhibitor PT88isapotlife Inhibitor PT88

® -

Processing RTV Silicones Examples of Use The graphs shown below illustrate the usage of WACKER® Catalyst EP or WACKER ® Inhibitor PT 88 on the basis of selected addition-curing RTV-2 silicones. The data given is only intended as a guide and should not be used for preparing specifications.

% WACKER® Catalyst EP % WACKER® Catalyst EP % WACKER® Catalyst EP in WACKER SilGel® 612 in ELASTOSIL® RT 607 in ELASTOSIL® RT 622

200 10 100 10 100 10 Potlife [min] Potlife Potlife [min] Potlife Potlife [min] Potlife 180 Curing time [h] Curing time [h] 160 8 80 8 Curing time [h] 80 8 140

120 6 60 6 60 6 100

80 4 40 4 40 4 60

40 2 20 2 20 2 20

0 0 0 0 0 0 0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25

 Curing time  Potlife  Curing time  Potlife  Curing time  Potlife

% WACKER® Inhibitor PT 88 % WACKER® Inhibitor PT 88 % WACKER® Inhibitor PT 88 in WACKER SilGel® 612 in ELASTOSIL® RT 607 in ELASTOSIL® RT 622

50 150 50 150 100 100 Potlife [h] Potlife Potlife [h] Potlife [h] Potlife Curing time [h] 40 120 Curing time [h] 40 120 Curing time [h] 80 80

30 90 30 90 60 60

20 60 20 60 40 40

10 30 10 30 20 20

0 0 0 0 0 0 0 1.0 0.2 0.3 0.4 0.5 0 1.0 0.2 0.3 0.4 0.5 0 0.2 0.4 0.6 0.8 1

 Curing time  Potlife  Curing time  Potlife  Curing time  Potlife

50 or ELASTOSIL Paste FLRedIron Oxide RAL3013, Ivory RAL1014,ELASTOSILIvory ELASTOSIL tained. almost anydesired colorcanbeob- can bemixed together inanyratio, UV andhotair. Andasthecolorpastes provide huesthatare resistant to light, the 200°Climit. the RTV siliconessignificantly exceeds Black RAL9005,theheatstabilityof such asELASTOSIL intensive color, withspecificgrades, der adverseconditions.Besidestheir tain itscolorforalongtime,evenun- cured RTV siliconeelastomer to re- are easyto process andallowthe ELASTOSIL used inRTV siliconerubbers. from similarsiliconepolymersto those patibility, thepigmentsare prepared a siliconepolymer. For maximumcom- very finely powdered pigmentsand ready-to-mix preparations comprising colors, ELASTOSIL mance, too. Available inmanydifferent good. Theyofferoutstandingperfor Our pigmentpastes don’tjustlook Coloring andHeatStability

® ® ColorPaste FLgrades ColorPastes FLare ® ColorPaste FLDeep ® ® ColorPastes FL ColorPaste FL ®

Color

• • • • • Advantages ataglance weight ofoneorseveral ELASTOSIL modified byaddingup to 2%by The colorofRTV siliconescanbe Processing mixers, isappropriate. which includesstaticordynamic of automatic metering equipment, cal, large-scale processing, theuse non-sag siliconegrades. For economi- air hasto betaken into accountfor quantities. Also,theriskofentrapping silicone grades orsmallmaterial recommended forflowable RTV rubber. However, manualmixingis for homogenizationwiththesilicone Standard mixingdevicescanbeused or white basecompounds. effective fortransparent, translucent Color Paste FLgrades. Theyare most food contact. BfR and/orFDA regulations regarding Most ofourcolorpastes complywith exposed to heat,lightandweathering High colorretention, evenwhen rubber processing No adverseeffectsonthesilicone with WACKER’s RTV siliconerubber Highly compatibleandeasyto mix space justbymixing. access to some80%ofthecolor of 24basiccolors,whichprovides A modularcolorschemecomposed

mix ELASTOSIL mixture, itismandatory to thoroughly In order to obtainahomogeneous before use. FL shouldbehomogenized bystirring compound. mixing, resulting inanunevenlymixed late onthewallofbeaker during viscous componenttends to accumu- thelessused formixing.Otherwise, applies whenamechanicalstirrer is intervals.a spatulaatshort Thisalso the beaker wallmustbescraped with respective componentsdiffersgreatly, uniform incolor. Iftheviscosityof pound mixistotally streak free and the RTV siliconerubberuntilthecom- Furthermore, ELASTOSIL Please Note base (componentA). icone rubber, butalwayswiththerubber nent B)ofcondensation-curingRTV-2 sil- be mixed withthecuringagent(compo- ELASTOSIL skilled personnel.For thesamereason, requires specialmixingequipmentand under strictexclusion ofhumidity, which moisture. Allmodificationmustbedone RTV-1 siliconerubberissensitiveto ®

ColorPastes FLshould not ® ColorPaste FLwith ® ColorPaste

Processing RTV Silicones 5.7 STORAGE

If stored in the original closed contain- Special Requirements for This type of contamination may be ers at 5 °C to 30 °C, ELASTOSIL®, Condensation-Curing Grades caused just by storing open drums SEMICOSIL®, LUMISIL®, SILPURAN®, (RTV-1, RTV-2 Silicones) of A and B component next to each POWERSIL®, WACKER SilGel® and As mentioned above, RTV-1 silicone other. As a result, the uncured material CENUSIL® silicone rubber formulations rubber formulations start curing in may form cured particles, or hydrogen have a shelf life of 3 to 24 months, the presence of moisture. In a similar might be released. Consequently, the from the delivery date, depending on manner, WACKER® T-series cata- drums must be tightly sealed after use. the grade. lysts of condensation-curing RTV-2 silicones react with air humidity and Storage-Induced Increase form siliceous compounds. Conden- General Information on Storing in Viscosity sation-curing RTV-2 silicone rubber ELASTOSIL® RTV Silicone Rubber For some RTV silicone rubber, storage formulations require small amounts of may cause an increase in viscosity. moisture (present in the rubber base), • Store in closed containers in a dry This is due to a particular polymer/filler which may escape from the packag- place at 5 – 30 °C orientation that can be reversed at any ing when stored open or with a loose • Higher average temperatures may time by shearing. Hence, the viscosity lid for a long time. It is important that shorten the shelf life is automatically reduced when the only the original, sealed containers are • Do not expose to direct sunlight rubber is processed with automatic used to store condensation-curing sili- • When opening the container, make dispensing machines, for instance. cone rubber formulations and that the sure that no dirt falls onto the surface Mixing or stirring the respective com- packaging is tightly closed for storage of the rubber pound prior to use also helps to re- once opened. store the original viscosity level. Safety Information: Therefore, such RTV silicone rubber Special Requirements for Please consult our safety data sheets if formulations can be processed in the Addition-Curing Grades you require additional safety information. normal way within the given shelf life. Even tiny amounts of the platinum catalyst are sufficient to start a reaction on contact with the component containing the crosslinking agent.

52 TROUBLE SHOOTING 5.8 The compoundcanthenbeused. sufficient moisture for proper curing. the rubberbecomessaturated with this time,thewater evaporates and 24 hoursatroom temperature. During in atightlycloseddrumforatleast up thoroughly. Themixture isstored A)andstirringbase compound(part kilogram ofbasecompound)to the quantity ofwater (1-2grams per be restored easilybyaddingasmall the originalcuringproperties can or withalooselid.Insuchcases, e.g., after storing thepackagingopen A), hasdropped belowacriticallevel, ofthebasecompound(partis part a proper curingandwhichtherefore of water vapor, for whichisnecessary rubber mayalsooccurwhenthelevel condensation-curing RTV-2 silicone Retarded vulcanizationof and result inimproper curing. condensation reaction’s byproducts of airmoisture ortherelease ofthe configurations canimpedetheaccess for curing.Unfavorable assembly (RTV-2) orusingexcessive heat (RTV-1), mismatchesinmixingratio such aslowlevelsofrelative humidity from inappropriate curingconditions Most oftheircuringproblems originate silicones are not sensitive to inhibition. In general, condensation-curing Condensation-Curing Silicones Vulcanization Problems of

• • • Typical inhibitors are: significantly delayedcuring. the interface to thesubstrate, or the presence ofliquidrubberat tackiness,by apermanentsurface curing inhibitionisusuallyindicated of substancesormaterials. Such substantially impaired byanumber curing siliconerubbermaybe silicones, thevulcanizationofaddition- In contrast to condensation-curing Curing Silicones(Inhibition) Vulcanization Problems ofAddition- Important forRTV-1Important SiliconeRubber silicone rubberisunsuitable. using ahygrometer. Addingwater to the curing. Humiditycanbeeasilymonitored a climate chambermustbeusedfor by meansofevaporators, atomizers, or completely. Thehumiditymustberaised 5 %orbelow, curingmayevenstop remain tacky. At arelative humidityof 30 %,thevulcanizate’s may surface If thelevelofrelative humidityfallsbelow rubber formulations. condensation-curing RTV-2 silicone vulcanizates andcatalystsof stances thatcontainthem,e.g., Organo-tin compoundsandsub- or amine-cured epoxy resins. substances suchaspolyurethanes Amines andaminecontaining synthetic rubbers(e.g.,EPDM). stances suchasnatural orcertain sulfones andsulfur-containing sub- Sulfur compoundssuchassulfides,

the substrates (seeabove). described forcleaningandpreparing aresurfaces identicalto those removing inhibitingcompoundsfrom pounds are present. Methodsfor determine whetherinhibiting com- out preliminary trialsinorder to It isstrongly recommended to carry organic rubber, orcastingresins. cabinetsusedforcuringdrying pounds canbepost-curingovens, Further sources ofinhibitingcom- in themixinganddosingequipment. present eitheronthesubstrate, or The inhibitingcompoundsmaybe • types ofplasticine. release agentsandalmostall such materials, forexample, many well assubstancescontaining greases, waxes andresins, as Various natural andsyntheticoils,

Processing RTV Silicones Problems Linked to Mixing Ratio Problems Linked to Temperature applies both to condensation- and It is absolutely essential to accurately When accelerating the vulcanization addition-curing RTV. Furthermore, meter two-component RTV silicones of condensation-curing silicones, the it is important to keep in mind that in the recommended mixing ratio. Only temperature should not exceed 70 °C. condensation-curing RTVs are a firm ratio of A:B guarantees a stable Otherwise, the result will be a limp, generally prone to chemical shrinkage, dispensing process and reproducible putty and sticky vulcanizate. Further irrespective of the curing temperature. results. Metering is possible either by defects such as bubble formation, Therefore, if dimensional accuracy weight or by volume. blistering or uneven surfaces (orange is required, either curing has to be peel, pinholes) may arise. Addition- carried out at the temperature at Important curing silicones can be heat cured which the rubber will subsequently be In general, the TDS state the mixing ratio (up to 250 °C). It is important to keep employed or the dimensional change in parts by weight. If mixing by volume in mind that increasing temperature has to be calculated, or determined is requested, the mixing ratio by volume will cause a corresponding decrease experimentally, and taken into account must be calculated using the density of in the potlife. To prevent premature accordingly. the respective component. vulcanization during processing, it is advisable to control the temperature It is also important to calculate space Depending on the type of RTV-2 both of the production place and the for thermal expansion of the silicone silicone, improper mixing ratio may metering and mixing device. during heat cure, especially when cause one or several of the following vulcanizing takes place in a closed effects: If curing is accelerated by heat, the system. Since silicone elastomers Situation 1 volume of curing rubber increases can only be compressed by applying Excess amount of the component due to thermal expansion. During extremely high pressure, thermal containing the crosslinker cool-down of the cured rubber to expansion of the rubber without an • Reduced potlife room temperature, shrinkage will “escape” provision can also cause very • Increased hardness and tensile occur. This can result in a distortion high pressure with a highly destructive strength of the vulcanizate’s geometry and effect. • Reduced maximum elongation and tear resistance • Post-curing effects at room Change in Volume During Curing temperature (embrittlement) Room temperature e.g., +150 °C Room temperature Situation 2 Insufficient amount of the component containing the crosslinker • Delayed or incomplete crosslinking • Soft, limp vulcanizates • Low mechanical strength of the vulcanizates • Increased susceptibility to swelling • Poor adhesion.

Uncured While curing Cured

54 UV-Curing Silicones Heat-Curing Silicones One-Component Addition Curing RTV-2 Silicones, Condensation Curing RTV-2 Silicones, RTV-1 Silicones All RTV Silicones Trouble Shooting

• Inhomogeneousvulcanizate • Bubbles,blisters andvoids • Uncured material onsubstrate interface • Limpandstickyvulcanizate • Delayedcuring • Bubbles,blisters andvoids • Uncured material onsubstrate interface • Sticky vulcanizate • Delayedcuring • Inhomogeneousvulcanizate • Bubbles,blisters andvoids • Uncured material onsubstrate interface • Sticky vulcanizate • Premature curing • Improper vulcanizate properties • Delayedcuring • Inhomogeneousvulcanizate • Bubbles,blisters andvoids • Limpandstickyvulcanizate • Delayedcuring • Premature curing • White spotsonthesurface • Bubbles,blisters andvoids • Tacky surface • Delayedcuring • Bubbles,blisters andvoids • Delayedcuring Issue

• Improper mixing • Contaminationwithwater • Humidsubstrate inhibition • Surface • Inhibition • Insufficientirradiation level • Inhibition • Insufficientirradiation level • Contaminationwithwater • Humidsubstrate • Excessive heatwhilecuring inhibition • Surface • Inhibition • Curingtimetoo short • Curingtemperature too low • Inhibition • Curingtemperature too low • Improper mixing • Contaminationwithwater • Humidsubstrate inhibition • Surface • Inhibition • Incorrect mixingratio • Inhibition • Incorrect mixingratio • Inhibition • Incorrect mixingratio • Improper mixing • Excessive heatwhilecuring • Lackofmoisture incomponentA • Excessive heatwhilecuring • Incorrect mixingratio byproducts to escape • Limited/no possibilityfor • Lackofmoisture incomponentA • Incorrect mixingratio • Incorrect mixingratio • Contactto water whilecuring • Useofheatwhilecuring • Useofheatwhilecuring • Low levelofairhumidity • Inappropriate assemblyconfiguration • Low levelofairhumidity • Insufficientlevelofde-aeration • Processing temperature too low Possible RootCause

Processing RTV Silicones 56 SECTION 6: SPECTRUM OF TECHNICAL APPLICATIONS

Contents Sealant adhesives, silicone gaskets, potting, encapsulation, coating and casting.

6.1 Sealant Adhesives 58

6.2 Silicone Gaskets 60 – Preformed gaskets – Cured-in-place gaskets (CIPG) – Foam gaskets – Formed-in-place gaskets (FIPG) – Applying RTV silicones for FIPG and CIPG

6.3 Potting and Encapsulation 65

6.4 Coating and Casting 66 Coating applications 66 Casting applications 68 WACKER brands for coating and casting 69

Spectrum of Spectrum of Technical Applications Technical

57 6.1 SEALANT ADHESIVES

Traditional mechanical joining Handling technologies, such as screwing, WACKER silicone sealant adhesives soldering, seaming, welding, or can be applied easily and economically riveting, are progressively being either manually or with automated superseded by modern adhesive dispensing equipment. Compared to bonding methods, such as sealant mechanical joining methods, sealant adhesives. The reasons are obvious: adhesives significantly reduce not elastic bonding with silicone sealant only the quantity of parts (e.g., screws, adhesives has decisive advantages rivets, etc.), but also the number of in terms of handling, functionality, process steps. Hence, silicone seal- durability and cost efficiency. ant adhesives help to reduce process cycle time.

58 Functionality Cost Effectiveness • Bonding efficiency Using silicone sealant adhesives A sealant adhesive acts as glue saves costs at different levels of and sealant at the same time. the manufacturing process, for The need for additional mechanical instance by: safeguarding measures often • A low level of warehousing due becomes obsolete. to the small number of parts • High joint reliability (e.g., screws, rivets, etc.) to be Thanks to the good electrical handled for the joint insulating properties of silicones, • Reduced costs for labor due to fully different metals can be bonded automated adhesive application without the risk of galvanic • Wide machining tolerances for the corrosion. parts to be bonded. • Uniform stress distribution Sealant adhesives distribute mechanical strain over the entire bonding area and thus minimize the risk of localized excessive stress. • Perfect stress relaxation Thanks to their low Young’s modulus, silicone sealant adhesives effectively compensate thermo- mechanical loads resulting from substrates with a different coefficient of thermal expansion. • Versatile applicability Silicone sealant adhesives have Spectrum of Spectrum of a high ability to bond dissimilar Applications Technical materials.

59 6.2 SILICONE GASKETS

Since gaskets operate at the inter- The respective silicone seals are Preformed Gaskets face between interior and exterior, either manufactured in a separate Preformed gaskets (O-rings, surface hot and cold, or wet and dry, they injection-molding process, or seals, and profile gaskets) are typically are frequently exposed to extreme subsequently inserted into the manufactured from liquid silicone rub- conditions. These severe physical multi-component assembly, or ber (LSR) or high consistency rubber challenges are met perfectly by they are “cured in place”. Curing (HCR) in a separate process. There WACKER silicone gaskets, which can also take place before the is no adhesion between the inserted perform with absolute reliability. components have been assembled. gasket and the joint parts. Sealing is achieved solely by compression, making disassembly possible at any time.

Sealing Technology Preformed Gasket Cured-In-Place Gasket Formed-In-Place Gasket (CIPG) (FIPG)

Silicone type LSR, HTV RTV-1, RTV-2 RTV-1, RTV-2 Application method Insert Dispensing Dispensing Time of assembly After curing After curing Before curing Adhesion to substrates None Only to one part To both parts Disassembly Possible Possible Impossible Mode of sealing Compression Compression Adhesive bonding Products ELASTOSIL® LR ELASTOSIL® E ELASTOSIL® E ELASTOSIL® R ELASTOSIL® A ELASTOSIL® A ELASTOSIL® N ELASTOSIL® N ELASTOSIL® LR ELASTOSIL® LR ELASTOSIL® RT ELASTOSIL® RT ELASTOSIL® SC ELASTOSIL® Solar ELASTOSIL® Solar SEMICOSIL® SEMICOSIL®

60 by compression, whichcallsfor the secondjointmemberisachieved has cured. Thesealing effect towards sembled after theRTV siliconerubber way. to Theparts besealedare as- in placewithoutbeingsecured inany one ofthesubstrates andthusstays gasket isappliedandadheres onlyto non-slump RTV silicones.Thesilicone bly”) isatypicalsealingtechnology for CIPG (alsoknownas“dry assem- Cured-In-Place Gaskets (CIPG) Calculation ofMinimumWidththeGroove Cross-Section andHeight-to-Width RatioofaSiliconeBead Maximum Compression ofaCIPGasket H u W H H Compression 25–35% H C fectly round-shaped, astheratio of section ofasiliconebeadisnotper recommended. In principle,thecross spacers orbyproper groove designis measures, forexample, byapplying compression by suitable constructive 25 %to amaximumof35%.Limiting gasket isassured oncompression of time. Ingeneral, tightnessofaCIP CIPG canbedisassembledatany set properties. sealedvia Theparts silicones withexcellent compression c ~ 1,3xW W/H =1:0.6–1:0.8 W Compression 25–35% ~ 0,75xH H - distribution ofthecompression force. each otherinorder to allowforeven placed asuitabledistancefrom Fixing boltsorscrews mustbe must becalculated accordingly. dimensioned andthecontactforce havetothe parts beproperly the assemblytight.For thisreason, must beavoidedinorder to keep distortion oftheassemblyparts compression force. Furthermore, toimportant evenlydistribute the itisWhen assemblingparts, with silicone. mended notto filltheentire groove height. Itisstrongly recombead’s - about the1.3to 1.4-foldthe silicone the groove shouldtherefore be taken into account.Thewidthof increase byswellingneedsto be and fluids,anadditionalvolume When incontactwithchemicals to deformundercompression. additional spaceforthesilicone the groove mustprovide sufficient As siliconesare notcompressible, for successfulsealing. clean andoil-free isnecessary surface the groove isnot required, howevera with agroove. Preparatory tooling of two substrates shouldbeequipped bead’s position,atleastoneofthe under loadandto stabilize thesilicone prevent aCIPgasket from rolling off from 1:0.6to 1:0.8.Inorder to width (W)to height(H)typicallyranges H H C u c Compressed Uncompressed height ofbead Compression height ofbead

Spectrum of Technical Applications Foam Gaskets The following conditions should RTV-2 silicone foam gaskets are be observed: similar to CIP gaskets but they permit • Silicone foam gaskets require higher component tolerances and a compression level of about require less compression force. They 30 % to 50 %. are particularly suitable for applications • The compression of the bead must where either pressure can’t be applied be controlled by suitable measures, evenly (e.g., due to constructional such as spacers or ridges, in order constraints) or the assembly parts to maintain a constant compression can’t withstand high compression level in the long term. force. • Preferably one of the substrates should be equipped with a groove. • In order to avoid permanent deformation, silicone foam beads must completely cure before they are compressed. • Post-curing can help to improve the silicone foam gasket’s resilience.

Foam Gasket Designs

During the curing process, RTV-2 Calculation of Foam Gaskets silicone foam rubber expands to 2 to 4-fold of its initial volume. When the space for this expansion process is W limited, e.g., in deep slots or cavities, Hr significant pressure is created on the cavity’s walls. As a result, deformation of the assembly parts can occur, and H H the foam density is higher than f it would be in open conditions (no cavity). Therefore, when foaming RTV-2 silicone rubber in cavities, the ratio of width (W) to height (H) should range from 1:1 to 1:2. For all other W : H = 1:1 to 1:2 Hr Height of rise configurations, the recommendations Hf Height of fill described for CIPG apply.

62 Formed-In-Place Gaskets (FIPG) Compared to inserted gaskets, However, the sealing effect is improved In FIPG (also known as “wet assem- FIPG do not require the joint parts to when the assembly parts are kept at a bly”), the parts to be sealed are as- have such high dimensional accuracy. distance H of 0.1 to 1.5 mm in order to sembled before the non-slump RTV In addition, the cured gasket mate- compensate relative movements (e.g., silicone rubber cures. Therefore, the rial stays firmly in place without fixing. vibration, different thermal expansion gasket material adheres to both sides Both permit simpler parts design and coefficient, shear load, etc.). This can after curing, which enhances the re- reduce development costs. be achieved by either spacers, external liability of the seal, but excludes the fixtures, or by adding glass beads of possibility of posterior disassembly. Parts sealed by FIPG are often specific size to the silicone. Embossing compressed up to a direct metal-to- a groove is also a suitable method. metal contact (also called zero gap). Depending on the substrate design and the joining distance, silicone

beads of 1.5 - 3.0 mm usually result FIP Gasket Designs in sufficiently wide FIP gaskets. For an optimum sealing result, the silicone should have a width (W) of 15 - 20 mm Spectrum of Spectrum of after assembling the parts, and must Applications Technical not fall below 6 - 8 mm to ensure tightness.

Since adhesion is crucial for FIPG, the surfaces must be clean and free H of grease. Before applying the silicone, contaminations have to be removed. In many cases, unprocessed surfaces provide better conditions for FIPG. W Rough surfaces and gaps of up to 3 mm (depending on the silicone grade used) can be sealed.

63 Using RTV Silicones as FIPG Unfavorable Groove Designs and CIPG Proper component design, in particular of the grooves and/or fixation points, is decisive for the tightness of FIP and CIP gaskets. For instance, in order to reduce the risk of air entrapment, the groove should not have any undercuts, and the corners should be rounded. The presence of ridges or sharp edges, which may corrupt the silicone bead, must also be avoided. Risk of air entrapment To ensure a proper application process, the nozzle design, the distance between nozzle and substrate, the Application Path at Edges extrusion speed, and the moving speed of the nozzle must be optimized in pre-trials. Generally, the dimension of the groove determines the type of the dispensing unit and the size of the dispensing nozzle.

Optimal application requires position- ing the nozzle close to the substrate, i.e., at a distance of just a few mm from the bottom of the groove. The silicone bead should be applied in the middle of the groove, which must not run at sharp angles but in curves. Nozzle path Formation of undesired bubbles possible When substrates are additionally fixed with bolts or screws, it is important to keep a specific distance between Applicaton Path for Substrates Fixed with Bolts or Screws silicone bead and the bolt holes. The distance is determined by the flexibility of the substrate, the hardness and compressibility of the silicone, and the compression force applied.

64 POTTING ANDENCAPSULATION 6.3 this market. WACKER isexcellently positioned for raw material polydimethylsiloxane, manufacturing process forthesilicone silicone encapsulants.Withitsunique microchips isaccomplishedbyusing boards, semiconductor devicesor control units,sensors,printed circuit Potting andencapsulationofelectronic protection from theenvironment. application fieldsdependonefficient of electronic devicesindifferent Reliable operation andthelifetime

grated Circuit). devices suchasbondedICs(Inte- are availableforsensitiveelectronic increasingly Extra-soft important. gels volatility andlowbleedare becoming gels characterized low by particularly vibrations. For sensorapplications, temperature fluctuations orstrong erly evenwhenexposed to extreme ensure thatthedevicewillworkprop- thermal stress and onsensitiveparts tions. Siliconegelsofferminimum for pottingandencapsulationapplica- one- andtwo-componentproducts WACKER offersawide range of

• • • • • • • Material Property Options • • • • • • • • Fuel resistance andNO High thermalconductivity High flame resistance Transparent to opaque Soft to hard Variable processing andcuringtimes Low viscosityorsheardiluting Specified lowioncontent Pronounced damping property Low uncured-silicone bleed Low outgassing Good adhesionto polymerhousings Low shrinkage High thermalshockresistance flexibility (down to -100°C) Remarkable low-temperature e.g., fluoro silicones x resistance

Spectrum of Technical Applications 6.4 COATING AND CASTING COATING APPLICATIONS

Low viscous RTV silicones can be The above-mentioned methods Since silicones can absorb air, airless applied with all common coating require specific RTV silicone properties spraying systems – as used for high- methods, such as spray coating, in terms of rheology, potlife and curing quality paintwork – are mandatory knife coating, dip coating, brush characteristics to achieve uniform for spray coating. This avoids unsatis- coating or transfer roller coating. coating of the protective lacquer. For factory results such as blistering and The following section gives an this purpose, WACKER offers custom- orange peel. The surfaces to be overview of the most relevant ized silicones, either solvent based or coated should be thoroughly cleaned industrial coating techniques. solvent-free. Dedicated SEMICOSIL® beforehand to ensure good adhesion and ELASTOSIL® silicone rubber to the substrate. Conformal Coating grades meet challenging requirements Thin coatings or protective lacquers in terms of productivity, quality, reliabil- Spray coating can be used for: for PCBs (Printed Circuit Board) ity and cost-efficiency. • Low viscous, flowable RTV silicones or hybrid devices are known as or “conformal coatings”. They provide Spray Coating • Solvent-based RTV silicone protection against external influences Spray coating is particularly suitable emulsions or such as dust, light, aggressive for parts with complex geometry or • Shear thinning, self-levelling media, temperature fluctuations for large surfaces. In sectors such as RTV silicones and mechanical stress. They also the electrical industry or the food in- enhance the dielectric strength of dustry, spraying silicones is a common Coatings based on RTV-1 start highly complex electronic modules. process to equip insulators, electrical vulcanizing during spraying due to In mass production, conformal coils, baking trays, baking molds, or contact with air moisture. RTV-2 coatings are typically applied by other devices with a protective silicone silicone coatings are usually cured by spraying or dispensing. Selective layer. Typical objectives are improving heating, e.g., in an oven or a heating parts of a PCB can even be coated hydrophobicity, protection against tunnel, after the spraying process. separately (“partial cover by selective moisture and atmospheric pollutants coating”). and better release.

66 • • • • applications are: Examples ofknifeorroller coating apply thesiliconeinstead ofaknife. ence isthatatransfer roller isusedto coating interms ofprocess. Thediffer Roller coatingiscomparable to knife with knifecoating. is key to obtainingexcellent results substrate. TheRTV silicone’s rheology the bladeispressed directly onto the thincoating(approx.a very the higherthickness.To achieve thickness –thegreater thedistance, substrate determines thecoating distance betweenthebladeand into thefabric,ifapplicable. The ensured, whichfacilitates permeation spreadability onthesubstrate is silicone isevenlydistributed andits silicone's viscosity. Asaresult, the applied bythebladelowers or adoctor blade.The shearforce applied infront ofacoatingknife With knifecoating,thesiliconeis viscosity are required. grades orthosewithmediumto high coating methods,eithershearthinning or non-wovenfabrics.For these RTV siliconeontextile, plasticfilm, processes are idealforapplyingan involving flexible substrates. Both preferred forroll-to-roll processes Knife coatingandroller coatingare Knife CoatingorRoller Silicone-based skinadhesives Silicone laminated plasticfilms Release lineronplasticfilmsorpaper dressings, airbags,orbakingmats Fabrics coatingse.g.,forwound

10 μm)

SILPURAN • • • • • grades are typicallyusedin product quality. standards ensure consistently high dance withWACKER CleanOperations dispensing andpackaginginaccor users andprocessors. Cleanroom and thehighestsafetylevelsforboth ensurecertification biocompatibility to ISO10993andUSPClassVI certificates. Selected tests according be sterilized anumberof andcarry are free oforganic plasticizers, can rigorous medicaldemands:They ing applications,SILPURAN SILPURAN health- andwound-care market is WACKER's dedicated brand forthe Knife CoatingandRoller Medical tapes Ostomy care Scar treatment Advanced woundcare Traditional woundcare Coating knife ® ® products fulfillthemost . For knifeandroller coat- Substrate ® RTV RTV coating Silicone

- transformers. machines, orelectricalcoilsof chokes, thecoilheadofelectrical coating isused,forexample, to coat potlife.Dipsilicones withashort production usuallymeansfastcuring with alongpotlife,whereas mass as thedipprocess requires asilicone ing. Itisrarely usedformassproduction adapted forsmallseriesorprototyp- Dip coatingisacost-efficientmethod viscous orsolvent-based. used fordipcoatingare eitherlow heat curinggrades). Typically, silicones sure to heat(RTV-2 orone-component by exposure to air(RTV-1) orbyexpo- type, thecoated material isvulcanized ing sags.Dependingonthesilicone the curingprocess to prevent coat- achieved byrotating during thepart Bettercan start. coating results are off. Thenthevulcanizationprocess ing bath,excess siliconemustdrip After removing from thepart thecoat- is dippedinto uncured RTV silicone. In thisprocess, to thepart becoated Dip Coating Silicone reservoir Silicone Substrate

coating Silicone

Spectrum of Technical Applications 6.4 COATING AND CASTING CASTING APPLICATIONS

Casting is a process in which uncured In this case, the silicone rubber is WACKER silicones for casting material is poured into a silicone mold infused into a mold as a casting com- applications offer valuable and where it crosslinks. Flowable RTV-2 pound in order to obtain a shaped unique advantages with optimal silicones are often processed by cast- elastomer part. Casting is usually results: ing, typically for manufacturing used for complex shapes, small-scale • Excellent processability and • Printing pads production or where investment is degassing properties • Embossing rollers limited. • Low viscosity to allow for a high level • Printer rollers of precision in detail reproduction • Prosthetic and orthopedic items • High flowability that permits fast • Ostomy care items. mold filling, no matter how intricate the mold is • Fast curing to enable short Reusable Silicone Elastomer Molds Produced by Casting demolding times • High level of tear resistance and release for easy and safe demolding • Long-term consistency and fatigue resistance for mechanically stressed silicone items • Excellent resistance to chemicals, such as printing inks, wax, plaster, casting resins or concrete.

Pattern production Mold production Casting Checkout

RTV silicone rubber is used to manufacture reusable molds, e.g., for molding applications, replica production or rapid prototyping.

Silicone Printer Roller Produced by a Casting Process

The open mold (1) has to be closed (2). Silicone (yellow) is introduced from the bottom so that air (white) can escape from the mold (3) and is not entrapped. After the mold is filled completely (4), the curing process can start. As soon as the material is cured, the mold can be (5) removed.

68 6.4 COATING AND CASTING WACKER BRANDS

WACKER brands for reproduction WACKER brands for medical, pro- and printing applications sthetic and orthopedic applications

ELASTOSIL® M SILPURAN® Molds for rapid prototyping, industrial WACKER's dedicated products not mass production, concrete moldings, only cover knife-coating and roller- restoration and reproduction, decora- coating applications, but also casting tive arts, or the composites industry applications for the medical industry: require the highest level of precision, SILPURAN® RTV grades are used, for accuracy and reusability. ELASTOSIL® instance, for ostomy care. Here too, M-series casting silicones have long SILPURAN ® products fulfill the most been recognized as the ideal solution rigorous medical demands. for making all types of silicone rubber molds. Their high elasticity, excellent ELASTOSIL® P release properties and optimal dura- WACKER silicones are used in many bility make ELASTOSIL® M casting prosthetic applications such as the grades indispensable for both manufacture of: industrial and artisan mold makers. • Functional prostheses for fingers, hands and partial-foot prostheses ELASTOSIL® RT • Orthoses In order to print on different surfaces • Epitheses such as paper, porcelain, plastics, or • External breast prostheses other uneven surfaces, the printing • Liners device (printing pad or printer roller) • Face masks tailored to must have constant mechanical pro- fit the wearer perfectly. perties and outstanding ink-transfer. ELASTOSIL® P-series silicones are ELASTOSIL ® RT-series casting sili- ready-to-use and offer customized cones provide precisely these qualities, solutions for the prosthetic industry. making them essential for any printing application. They produce superior print results, even for large print runs.

ELASTOSIL® C In the composite industry, reusable vacuum bags are manufactured with chemically resistant ELASTOSIL® C silicones. Their fast-curing property Spectrum of Spectrum of Technical Applications Technical permits short production cycles, thus ensuring cost-effective and efficient production of fiber-composite items.

69 70 SECTION 7: SERVICE

Contents Excellent technologies need best-in-class services. Our WACKER ACADEMY, technical centers and e-business offer you extraordinary expertise and support.

7.1 Technical Service and Expertise 72

7.2 WACKER Infoline & E-Business 73

7.3 Regulatory Support 74

7.4 WACKER ACADEMY 75 Service

71 7.1 TECHNICAL SERVICE AND EXPERTISE

Our application chemists and engineers work closely with our customers, dealing with specific questions from the field. We will support you by finding the optimum product for your specific requirements and by assisting your product development, from material selection to industrial production – worldwide. Our laboratories deal with key issues from specific industrial sectors and have extensive expertise in various application fields.

WACKER SILICONES stands for 360°-silicone expertise and over 50 years of market experience: • Deep understanding of silicones and silicone processing • Local technical centers world- Thanks to our RTV Clean Operations Some of our Laboratory Services wide with experienced laboratory plant, WACKER is able to produce • Product adaptation/development technicians according to selected GMP criteria and • Range of lab tests: • Technical consultancy for product provide clean-room packing classified – Mechanical properties selection according to EN ISO 14644-1 Class 8 – Adhesion • Adjusting standard formulations and for high-end health care and electron- – Chemical resistance customizing to specific requirements ics applications. Furthermore, UV-cur- – Thermal, UV and climate ageing • State-of-the-art analytical equipment ing silicone rubber can be processed – Electrical properties. to perform tests according to under controlled lighting conditions. • In-house application of our RTV international and local standards silicone rubber formulations on and regulations original assembly parts by fully • Active network of specialists and automated metering & dispensing cross-functional cooperation with equipment, e.g., for testing or other labs and departments approval series • Consistent product quality worldwide

72 WACKER INFOLINE&E-BUSINESS 7.2 hearing from you. e-mail orphone.We lookforward to data orfactsquicklyandexpertly via information,you withthenecessary products We’ll orservices. provide questions youmayhaveaboutour provide prompt answersto any Our WACKER Infolineisthere to Infoline

• • • Asia, LatinAmerica Europe, MiddleEast&Africa, • • • NAFTA (USA,Canada andMexico) General Telephone Number: 00 800-6279-0800 Toll-free NumberInternational: 0800-6279-800 Toll-free NumberGermany: E-Mail [email protected] (+1 888-WACKER 4U) E-Mail [email protected] +49 896279-1741 +1 888-922-5374 Toll-free Number:

• • • • • • • • greater efficiencythrough: You cangainconsiderably wishes. company, yourprofile andspecific for you,adapted to thesize ofyour compile atailored package service and vendor-managed inventory. We to fastorder processing solutions in ourLogin4More customer portal global searches andreporting options and offermanypossibilities:from between ourcustomers andWACKER, WACKER e-solutionssimplifybusiness E-Business Automatic inventory monitoring. Paperless invoicing Full transparency Maximum planningreliability Fast processing withfarfewererrors Easy order changes Automatic order processing 24/7 availability

Service 7.3 REGULATORY SUPPORT

To ensure product safety, we This includes the following topics: • Specific customer requirements offer you regulatory support. • Food contact applications (e.g., banned-substance and Our experts handle your enquiries (e.g., BfR, FDA) substance-avoidance lists) on environmental, health and • Drinking water approval • Toxicology and ecotoxicology regulatory matters. (e.g., KTW, WRAS, ACS) • Risk assessment • Pharmaceutical and medical • Organizational assistance. applications (e.g., European Pharmacopeia and U.S. Pharmacopeia USP) • National and international regulations and provisions (e. g., EU directive 2002/95/ EC – RoHS, REACH) • Specific industry requirements (e.g., GADSL, IMDS, automotive industry)

74 THE WACKER ACADEMY 7.4 industry-specific seminarprogram.industry-specific can take advantageofaversatile, number ofsites worldwide,you WACKER ACADEMY. Here, ata founded auniqueinstitution,the market experience, WACKER has To transfer itsownexpertise and

needs andyourspecificmarkets. you aseminarprogram tailored to your doorstep. Asaresult, wecanoffer expertise availablerightonyour ing ourpolicyofmakingglobal located indifferent regions, exemplify- WACKER ACADEMY centers are www.wacker.com/wacker-academy. You canfindthecurrent program at: • • • • This includes: events, specific to yourneeds. Customized training programs and rubber fornewcomersto thefield Introductory seminaronsilicone application fields Training programs onparticular Introductory seminars chemistry

universities andresearch institutes. up to date, weworkcloselywith more attractive andensure itremains experts. To make ourprogram even enced specialists–chieflyin-house All ourseminarsare heldbyexperi-

Service 76 SECTION 8: SILICONES A–Z

Contents A list of frequently used technical terms is given below.

Adhesion 78 Coefficient of linear thermal expansion 78 Compression set 78 Density 78 Dielectric constant 78 Dielectric strength 78 Dissipation factor 78 Environmental compatibility 78 Fire behavior 78 Flame resistance 79 Gas permeability 79 Hardness 79 High-energy radiation 79 Heat resistance 79 Ozone resistance 79 Optical properties 79 Penetration 80 Rebound resilience 80 Release properties 80 Reversion 80 Solvent and chemical resistance 80 Shrinkage 80 Surface resistance 80 Tear propagation and notch resistance 80 Tensile strength and elongation at break 80 Temperature behavior 81 Thermal conductivity and specific heat capacity 81 Tracking resistance 81 Viscosity 81 Volume resistivity 81 Water and steam resistance 81 Weathering and UV resistance 81

77 Silicones A-Z Silicones A-Z 8.0 SILICONES A – Z

Adhesion Density Dissipation Factor Tan δ • Self-adhesive RTV silicone rubber • Determined as per ISO 1183-1 A • Dielectric dissipation factor tan δ is suitable for many substrates (buoyancy method). – Dissipation factor determined • The quality of adhesion depends • Typical range for specific density as per VDE 0303. on the nature of the materials to 0.95 – 1.50 g/cm³. – Typical values for loss angle be bonded, the mechanical stress, • When using additional inactive tan δ ~10 –3. and possibly a surface treatment fillers (e.g., quartz), values of over – tan δ is raised by increasing the (primer, plasma, corona). 3 g/cm³ can be achieved, for exam- filler content/density. • Most superior bonds are obtained ple, to improve swelling resistance or • Mechanical dissipation factor tan δ on oxidic and siliceous surfaces. thermal conductivity. – Determined via measurement of the silicone’s storage modulus and

Coefficient of Linear Thermal Dielectric Constant εr loss modulus.

Expansion • Dielectric constant εr determined – Typical values for gels: tan δ < 0.1; • Coefficient of linear thermal as per DIN 53 482 or VDE 0303. typical values for silicone elastomers expansion approx. • Typical values for silicone rubber: tan δ >1. -6 -6 150∙10 – 300∙10 m/(m∙K) εr = 2.7 - 3.3 (at 25 °C and 50 Hz). – tan δ is raised by increasing the • RTV silicone rubber expands during • This property can be increased up crosslinking density or by filler heat curing, resulting into an to 150 by using suitable fillers. content. “apparent” shrinkage on cooling • The coefficient of linear thermal Dielectric Strength Environmental Compatibility expansion depends on the filler • Dielectric strength determined as • Since silicones have the same basic content. per IEC 60243-1. chemical structure as quartz, cured • Typical value for RTV silicone RTV silicone rubber poses no known Compression Set rubber > 20 kV/mm ecological or physiological risks. • Compression set determined as (1 mm sheet, IEC 60243-1). per ISO 815-B (ASTM D395 B-2) Fire Behavior for storage lasting 22h/175 °C, or • The auto-ignition temperature of 22h/125 °C in cured products is about 430 °C. the case of self-adhesive grades. • Silicone rubber burns to form a white • Compression set describes the non-toxic ash of silicon dioxide elastic recovery of a cured rubber, • The resultant combustion gases are an important characteristic for usually non-corrosive. gasket applications. • Specialty grades form a ceramic • Typical values for RTV silicone layer in the case of fire. rubber: down to 5 %.

78 Flame Resistance Relative Permeability of Gases at Heat Resistance • Flame resistance determined acc. 25 °C (%) • The mechanical properties of to ASTM D 2863 test standard by Air 100 WACKER silicone rubber are retained determining the limiting oxygen Hydrogen 190 even at high temperature stress. index (LOI) or acc. to Underwriters Oxygen 170 • The heat resistance is thereby clearly Laboratory fire standard (UL 94). Nitrogen 80 superior to that of most organic • Typical LOI values of flame retardant Carbon dioxide 1.000 elastomers (cf. ASTM Charta D2000) grades 27 % to 35 % Ethylene 390 • Standard grades normally achieve Ozone Resistance UL 94 HB (0.5 – 1.0 mm thickness) Hardness • Outstanding resistance of silicone • Specialty grades with additives reach • Hardness of silicone rubber rubber to ozone UL 94 V0 (1.0 – 4.0 mm thickness). determined in Shore 00 • Ozone resistance determined as (ASTM D 2240 / Type 00), per DIN 53509 Gas Permeability Shore A (ISO 7619-1) or in • Determined as per DIN 53 536 IRHD units (DIN 53 519). Optical Properties • Very high gas permeability compared • Typical range: • The light permeability of unfilled RTV to other elastomers, e.g., for air 30 20 Shore 00 – 80 Shore A. silicone rubber materials is almost times higher than for natural rubber • See penetration for silicone gels 100 % in the visible range from 400 (NR) or 400 times higher than butyl to 760 nm (1 mm layer thickness). rubber (IIR) (measured at 25 °C) High-Energy Radiation • The cut-off region of highly trans- • The absolute value of a 50 Shore A • Outstanding resistance of silicone parent RTV silicones ranges from grade for air at 20 °C and 80 °C is rubber (VMQ, PVMQ) to high-energy 220 – 230 nm. 570 and 1.330 cm³ ∙ mm ∙ m –2 ∙ h –1 radiation in combination with hot-air • The appearance of RTV silicone ∙ bar –1 (volume of air measured in resistance in comparison to other rubber is determined by fillers. cm³, that penetrates a membrane of elastomers. Fumed silica as filler makes the 1 m² area per hour at a pressure • With VMQ silicone rubber grades, respective grades become difference of 1 bar and 1 mm only high radiation doses of translucent due to light scattering. thickness) 400 – 800 kGy lead to a reduction • The refractive index nD25 is between • Technical advantage, e.g., for of 50 % in the elongation at break. 1.404 and 1.410 for standard RTV contact lenses, textile coatings and • Phenyl-containing PVMQ silicone silicone rubber. High refractive index some medical applications rubber, such as ELASTOSIL® RTV-S grades achieve values of up to 1.5 • At high temperatures, silicone has 691, has higher resistance. and higher. similar values to organic elastomers • Properties not severely affected by gamma and beta radiation (25 – 75 kGy), as widely used for sterilizing medical equipment. • Very good resistance to micro- waves, since silicone parts are not microwave-active and therefore not heated.

* dep. on grade

79 Silicones A-Z Silicones A-Z Penetration Reversion • Silicone rubber has good resistance • The consistency of silicone gels • Degradation of the crosslinking to aqueous solutions of weak acids, is usually characterized by quoting network in the cured rubber as a alkalis or salts, which are commonly the penetration. It is determined by result of chemical or thermal effects. used as cleaning solutions for use of a standard cone under a spe- This leads to a permanent decrease lines / tubing at 70 – 80 °C in the cific load and given in mm/10. of hardness (softening) food industry. • The higher the penetration • In silicone rubber, at high tempera- value, the softer the compound. tures (> 200 °C) traces of moisture Shrinkage • Typical values for soft gels: or free hydroxyl groups in fillers • Condensation-curing RTV silicones 300-100 mm/10 cause cleavage of the Si-O bond show a volume shrinkage of up to • Typical values for tough gels: in the polymer chain and ultimately 3 % due to the liberation of volatile 30-10 mm/10. the above-mentioned decrease in by-products. hardness due to depolymerization • Addition-curing RTV silicones cure Rebound Resilience • This process is inhibited by the almost shrink-free (approx. 0.1%). • Rebound resilience determined as presence of air per DIN 53 512 • High heat resistance therefore Surface Resistivity • Also commonly known as “snap” requires unrestricted access of • Surface resistivity determined as • Measured on 6 mm samples as a atmospheric oxygen, and must per VDE 0303 ratio of rebound height to the drop be taken into account in the design • Typical values for insulating silicone height of a pendulum of gasket parts compounds: approx. 1012 – 1013 Ω. • Typical values 30 – 70%. • Solvent and Chemical Resistance Tear Propagation and Notch Release Properties • The chemical resistance of WACKER Resistance • RTV silicone rubber shows a silicone rubber generally depends on • Tear strength depends on which pronounced release effect versus the crosslinking density, filler used, particular standard is used. inorganic and organic materials such and filler content. • Typical values when determined as gypsum, concrete, polyester, • With higher filler levels in the silicone as per ASTM D 624 B (crescent): epoxide, polyurethane, polyamide, rubber, the swelling tendency de- 5 – 30 N/mm. polystyrene, PVC, wax and metal creases and resistance is improved. alloys. • High swelling tendency to non- Tensile Strength and Elongation • This effect is exploited where RTV polar liquids such as hydrocarbons, at Break silicone rubber is used in mold- mineral oils and greases. • Tensile strength and elongation making compounds to make molded • Low swelling tendency to polar at break determined as per ISO 37 parts or reproductions. liquids, such as alcohols, low- • Standard test on S1 bar. In some molecular ketones, and therefore cases, also measurements on small no negative effect on seal quality. S2 and S3 test specimens, though • Strongly attacked by concentrated the values deviate correspondingly acids and alkalis, particularly by • Typical RTV silicone values: tensile oxidizing acids such as sulfuric or strength — approx. 2 – 8 N/mm2 nitric acid. (or MPa); elongation at break — approx. 100 % – 900 %

80 Temperature Behavior Thermal Conductivity and Water and Steam Resistance • Mechanical properties of silicone Specific Heat Capacity • Excellent resistance to boiling elastomers determined at 23 °C • Determined as per DIN 52 612 water. (room temperature) as per DIN • The thermal conductivity depends • Volume decrease in boiling water 53503 or DIN 53505 respectively. on the type and amount of fillers below 1 %, even after prolonged • The change in the mechanical used. action. properties is small compared • Typical value for standard grades at • Steam sterilization (as per ISO to organic elastomers. 50 °C: approx. 0.2 – 0.3 W/(m∙K). 17665, DIN EN 868-8 at 500 • Typical service temperature range: • Special thermally conductive cycles at 134 °C, 5 min.) may –50 to +180 °C. Specialty grades: compounds achieve values of slightly change mechanical down to -110 °C or up to 270 °C up to 3 W/(m∙K). properties. (peak temperature load may be • Typical values for specific heat • Water (gaseous) absorption of even lower or higher). capacity: approx. 1.25 kJ/( kg∙K). < 0.5 % with virtually no effect • Standard grades harden at very low on mechanical or electrical temperatures (below -45 °C) due Tracking Resistance properties. to reversible crystallization. • Silicone rubber generally features • There is a slow increase in hardness high tracking resistance Weathering and UV Resistance at very high temperatures (> 200 °C) (e.g., CTI 600 as per IEC 60112). • Silicone rubber items are generally as a result of heat aging. insensitive to UV radiation. • At high temperatures (> 180 °C), Viscosity • Properties only change slightly the organic side groups attached to • Determined as per DIN EN ISO 3219. even in long-term tests (several the silicon atom undergo free-radical • The viscosity of RTV silicone rubber years of weathering). cleavage. The resulting free radicals compounds is usually between • Unlike with organic elastomers, can cause post-curing of the polymer 500 and 2,000,000 mPa∙s. weathering resistance can be chains, thereby increasing hardness • Viscosity depends on temperature achieved without additives and decreasing tensile strength and and can depend on shear rate. (e.g. organic antioxidants, elongation at break (embrittlement). UV stabilizers, etc.). • The simultaneous weight decrease Volume Resistivity of the vulcanizate leads to shrinkage. • Determined as per IEC 60093. • The lifetime of the RTV silicone • Typical values for insulating silicone vulcanizate can be increased by the rubber grades approx. 1015 Ω∙cm. use of heat stabilizers • Typical values for conductive RTV • The increased crosslinking density grades approx. 50 Ω∙cm. as a result of prolonged thermal loading has a positive effect on the rebound resilience. • Excellent stable, long-term behavior for electrical insulation at high temperatures is obtained, as oxida- tive degradation produces quartz- like properties.

81 Silicones A-Z Silicones A-Z EXPERTISE AND SERVICE NETWORK ON FIVE CONTINENTS

• Sales offices and production sites, plus WACKER is one of the world’s leading and energy efficiency and protection of the and in collaboration with, our customers. reliable service to enable projects and 18 technical centers, ensure you a local presence worldwide. most research-intensive chemical compa- climate and environment. We also help them boost their own suc- orders to be handled fast, reliably and nies, with total sales of €4.6 billion. Spanning the globe with 4 business cess. Our technical centers employ local highly efficiently. Products range from silicones, binders divisions, we offer our customers highly- specialists who assist customers world- Visit us anywhere, anytime around the and polymer additives for diverse industrial specialized products and comprehensive wide in the development of products world at: www.wacker.com sectors to bioengineered pharmaceutical service via 23 production sites, 18 technical tailored to regional demands, supporting actives and hyperpure silicon for semi- competence centers, 13 WACKER them during every stage of their complex conductor and solar applications. As a ACADEMY training centers and 48 sales production processes, if required. technology leader focusing on sustainability, offices in Europe, North and South America, WACKER e-solutions are online services WACKER promotes products and ideas and Asia – including a presence in China. provided via our customer portal and as that offer a high value-added potential to With a workforce of some 13,450, we see integrated process solutions. Our custom- ensure that current and future generations ourselves as a reliable innovation partner ers and business partners thus benefit enjoy a better quality of life based on that develops trailblazing solutions for, from comprehensive information and All figures are based on fiscal 2016.

O-17-03128_NEU_group page_double_A4_Europe_2016.indd Alle Seiten 08.05.17 13:45 O-17-03128_NEU_group page_double_A4_Europe_2016.indd AlleSeiten • ON FIVECONTINENTS EXPERTISE ANDSERVICENETWORK

worldwide. 18 technical centers, ensure youalocalpresence Sales officesandproduction sites, plus

enjoy abetter qualityoflifebasedon ensure thatcurrent andfuture generations that offerahighvalue-added potential to WACKER promotes products andideas technology leaderfocusingonsustainability, conductor andsolarapplications.Asa actives andhyperpure siliconforsemi- sectors to bioengineered pharmaceutical and polymeradditivesfordiverseindustrial Products range from silicones,binders nies, withtotal salesof€4.6billion. most research-intensive chemicalcompa- WACKER isoneoftheworld’s leadingand

that developstrailblazing solutionsfor, ourselves asareliable innovationpartner With aworkforce ofsome13,450,wesee and Asia–includingapresence inChina. offices inEurope, andSouthAmerica, North ACADEMY training centers and48sales competence centers, 13WACKER via23productionservice sites, 18technical specialized products andcomprehensive divisions, weofferourcustomers highly- Spanning theglobewith4business climate andenvironment. energy efficiencyand protection ofthe

from comprehensive informationand ers thusbenefit andbusinesspartners integrated process solutions.Ourcustom- provided viaourcustomer andas portal WACKER e-solutionsare onlineservices production processes, ifrequired. stageoftheircomplexthem duringevery tailored to regional demands,supporting wide inthedevelopmentofproducts specialists whoassistcustomers world cess. Ourtechnical centers employlocal We alsohelpthemboosttheirownsuc- and incollaboration with,ourcustomers.

- world at:www.wacker.com Visit usanywhere, anytimearound the highly efficiently. orders to behandledfast,reliably and reliable to service enableprojects and

All figures are basedonfiscal2016. 08.05.17 13:45

Rubber Solutions A-Z Service Technical Application Handling Getting Started Understanding Silicone Rubber – Discover Diversity Spectrum for RTV Silicones RTV Silicones for Production RTV Silicones Basic Principles CREATING TOMORROW’S SOLUTIONS

Wacker Chemie AG PRODUCT OVERVIEW Hanns-Seidel-Platz 4 81737 München, Germany Tel. +49 89 6279-1741 [email protected] 7461B e/08.17 www.wacker.com INDUSTRIAL SEALING & www.wacker.com/socialmedia BONDING APPLICATIONS

Non-slump RTV silicone grades (self-adhesive)

The data presented in this medium are in accordance with the present state of our knowledge but do not absolve the user from carefully checking all supplies immediately on receipt. We reserve the right to alter product constants within the scope of technical progress or new developments. The recommendations made in this medium should be checked by preliminary trials because of conditions during processing over which we have no control, especially where other companies’ raw materials are also being used. The information provided by us does not absolve the user from the obligation of investigating the possibility of infringement of third parties’ rights and, if necessary, clarifying the position. Recommendations for use do not constitute a warranty, either express or implied, of the fitness or suitability of the product for a particular purpose. Main characteristics Brand Product Product type / curing system Shrink-free By-product of Additional features Food Viscosity Potlife or Hardness Tensile strength Elongation Tear strength Density, cured Recommended CIPG FIPG Aspect / color curing curing compliance [mPa·s] skin forming time [Shore A] [MPa] at break [%] [N/mm] [g/cm³] max. service temperature [°C] Self-adhesive after curing at room temperature General purpose ELASTOSIL® E 4 RTV-1 / condensation cure Acetic acid Non-slump 20 min 15 2.0 750 7.3 1.02 180 X X Translucent ELASTOSIL® E 43 N RTV-1 / condensation cure Acetic acid Tin free X 300,000 5 min 30 8.0 500 13.5 1.10 180 X Translucent / white / black ELASTOSIL® E 900 RTV-1 / condensation cure Acetic acid Non-slump 10 min 20 0.6 300 4.2 1.02 230 X Anthracite ELASTOSIL® N 197 Gray RTV-1 / condensation cure Oxime Low MEKO grade Non-slump 20 min 30 1.2 400 1.40 180 X Gray ELASTOSIL® N 198 RTV-1 / condensation cure Oxime Non-slump 30 min 40 3.0 300 4.5 1.24 190 X Gray / black ELASTOSIL® N 2197 RTV-1 / condensation cure Alcohol Flame retardant Non-slump 20 min 35 2.5 350 6.0 1.27 180 X Gray ELASTOSIL® N 2199 RTV-1 / condensation cure Alcohol Non-slump 15 min 30 2.5 350 4.0 1.06 180 X Translucent ELASTOSIL® N 9111 RTV-1 / condensation cure Alcohol Tin free Non-slump 25 min 30 2.2 500 10.0 1.33 180 X White / gray / black ELASTOSIL® RT 771 RTV-2 / condensation cure (Base + Catalyst 10:1)* Alcohol 150,000 5 min / 10 min * 45 1.0 180 1.55 180 Black ELASTOSIL® RT 774 RTV-2 / condensation cure (Base + Catalyst 10:1)* Alcohol Non-slump 5 min / 15 min * 38 2.1 300 6.2 1.37 180 X Anthracite Improved mechanical properties ELASTOSIL® E 47 RTV-1 / condensation cure Acetic acid Non-slump 5 min 35 4.5 450 10.0 1.07 180 X Translucent ELASTOSIL® N 199 RTV-1 / condensation cure Oxime Non-slump 30 min 35 4.9 500 12.0 1.09 180 X Translucent Heat resistance ELASTOSIL® A 33 RTV-1 / condensation cure Amine Non-slump 10 min 28 2.5 300 7.8 1.17 200 X Ivory ELASTOSIL® E 14 RTV-1 / condensation cure Acetic acid Non-slump 15 min 38 3.0 450 7.0 1.18 250 X Red ELASTOSIL® E 43 BLACK RTV-1 / condensation cure Acetic acid 300,000 15 min 30 6.2 600 11.5 1.10 250 X Black ELASTOSIL® RT 778 RTV-2 / condensation cure (Base + Catalyst 10:1)* Alcohol Fast cure Non-slump 5 min / 10 min * 42 3.5 180 7.0 1.32 250 X Black Media resistance ELASTOSIL® N 189 RTV-1 / condensation cure Oxime Coolant resistant, oil resistant Non-slump 10 min 32 2.0 300 7.0 1.09 250 X Black ELASTOSIL® N 2189 RTV-1 / condensation cure Alcohol Coolant resistant, oil resistant Non-slump 15 min 45 2.5 250 4.0 1.23 180 X Black ELASTOSIL® RT 779 RTV-2 / condensation cure (Base + Catalyst 10:1)** Alcohol Coolant resistant, oil resistant Non-slump 5 min 50 2.8 250 9.5 1.32 180 X Anthracite Compressible ELASTOSIL® RT 773 RTV-2 / condensation cure (Base + Catalyst 10:1)* Alcohol Low density Non-slump 5 min / 15 min * 35 1.2 110 0.70 140 X Black ELASTOSIL® SC 833 RTV-2 / platinum cure (A/B 1:1) Hydrogen gas Silicone foam, flame retardant 17,000 4 min 27 1.2 80 0.50 200 X Black ELASTOSIL® SC 835 RTV-2 / platinum cure (A/B 1:1) Hydrogen gas Silicone foam 15,000 240 s 20 0.45 80 0.45 200 X Reddish brown ELASTOSIL® SC 870 RTV-2 / platinum cure (A/B 1:1) Hydrogen gas Silicone foam, thixotropic 40,000 150 s 10 0.35 100 0.40 200 X Gray Self-adhesive after curing at elevated temperature General purpose ELASTOSIL® RT 703 1-component heat-curing / platinum cure X Screen printable Non-slump 6 months 33 2.0 360 1.03 200 X X Translucent ELASTOSIL® RT 724 RTV-2 / platinum cure (Base + Catalyst 10:1)*** X 100,000 12 h 45 4.0 180 10.0 1.25 180 X Blue SEMICOSIL® 986/1K 1-component heat-curing / platinum cure X UV fluorescent Non-slump 6 months 51 5.0 200 8.0 1.07 180 X Translucent SEMICOSIL® 987 GR 1-component heat-curing / platinum cure X Sealing adhesive Non-slump 6 months 50 5.0 200 1.10 180 X Gray SEMICOSIL® 988/1K gray 1-component heat-curing / platinum cure X Sealing adhesive Non-slump 6 months 35 4.5 350 24.0 1.10 180 X X Gray SEMICOSIL® 989/1K 1-component heat-curing / platinum cure X Sealing adhesive Non-slump 6 months 55 5.0 200 10.0 1.10 180 X Translucent SEMICOSIL® 970 TC RTV-2 / platinum cure (A/B 1:1) X Thermally conductive 94,000 16 h 65 4.0 90 2.26 160 X White-gray SEMICOSIL® 975 TC 1-component heat-curing / platinum cure X Thermally conductive Non-slump 3 months 90 3.0 30 6.0 3.30 160 X Reddish gray High tear resistance ELASTOSIL® RT 722 RTV-2 / platinum cure (A/B 1:1) X High tensile strength Non-slump 6 h 45 6.0 300 1.10 180 X Gray Heat resistance ELASTOSIL® RT 702 1-component heat-curing / platinum cure X Non-slump 6 months 40 6.1 500 10.1 1.21 250 X Black Media resistance ELASTOSIL® RT 727 RTV-2 / platinum cure (A/B 1:1) X Coolant resistant Non-slump 24 h 60 5.5 350 10.0 1.14 180 X X Gray ELASTOSIL® RT 728 RTV-2 / platinum cure (A/B 1:1) X Coolant resistant Non-slump 24 h 60 4.0 200 10.0 1.13 180 X Opaque Compressible ELASTOSIL® RT 713 1-component heat-curing / platinum cure X Low density Non-slump 6 months 23 1.5 350 7.0 0.75 140 X Gray

* base component to be combined with WACKER® Catalyst T 77 or WACKER® Catalyst T 77 PLUS (please see the corresponding technical data sheet for details) ** base component to be combined with WACKER® Catalyst T 79 (please see the corresponding technical data sheet for details) *** base component to be combined with ELASTOSIL® CAT PT, ELASTOSIL® CAT PT-F or ELASTOSIL® CAT UV to allow curing at room temperature, under heat or by UV light (please see the corresponding technical data sheet for details)

ELASTOSIL® and SEMICOSIL® are registered trademarks of Wacker Chemie AG. CREATING TOMORROW’S SOLUTIONS

Wacker Chemie AG PRODUCT OVERVIEW Hanns-Seidel-Platz 4 81737 München, Germany Tel. +49 89 6279-1741 [email protected] 7461C e/08.17 www.wacker.com INDUSTRIAL COATING OR www.wacker.com/socialmedia SEALING APPLICATIONS

Flowable RTV silicone grades (self-adhesive)

Self-adhesive after curing at room temperature General purpose ELASTOSIL® A 07 RTV-1 / condensation cure Amine Solvent based 8,000 3 min 20 1.5 300 4.0 1.02 200 Translucent ELASTOSIL® E 41 RTV-1 / condensation cure Acetic acid Solvent based 65,000 15 min 40 6.0 350 11.5 1.12 180 Translucent ELASTOSIL® E 50 N RTV-1 / condensation cure Acetic acid Tin free X 50,000 10 min 35 1.5 150 5.0 1.07 180 Transparent ELASTOSIL® E 303 RTV-1 / condensation cure Acetic acid Solvent based 500 5 min 30 5.0 400 0.90 180 Translucent ELASTOSIL® N 10 RTV-1 / condensation cure Oxime 8,000 25 min 25 1.5 200 2.0 1.03 180 Transparent ELASTOSIL® N 2010 RTV-1 / condensation cure Alcohol 15,000 20 min 25 1.0 200 1.01 180 Translucent ELASTOSIL® N 2034 RTV-1 / condensation cure Alcohol Flame retardant 25,000 20 min 35 2.0 200 1.16 180 Black ELASTOSIL® RT 745 RTV-2 / platinum cure (A/B 1:1) X 1,000 4 h 15 1.0 150 0.97 160 Brownish Heat resistance ELASTOSIL® A 234 RTV-1 / condensation cure Amine 35,000 15 min 36 2.5 200 3.7 1.19 230 White ELASTOSIL® A 316 RTV-1 / condensation cure Amine Solvent based 500 5 min 15 0.8 200 1.02 180 Translucent ELASTOSIL® A 59 RTV-1 / condensation cure Amine Oil resistant 60,000 45 min 20 1.2 300 3.0 1.43 210 Gray ELASTOSIL® E 10 RTV-1 / condensation cure Acetic acid 8,000 10 min 25 2.5 300 7.3 1.10 250 Red ELASTOSIL® E 60 N RTV-1 / condensation cure Acetic acid Tin free X 80,000 5 min 35 2.5 250 1.07 230 Black / gray / red ELASTOSIL® E 70 RTV-1 / condensation cure Acetic acid 60,000 15 min 40 3.5 300 5.1 1.24 230 Red ELASTOSIL® N 288 RTV-1 / condensation cure Oxime 65,000 50 min 35 3.5 300 5.1 1.09 230 Red ELASTOSIL® N 291 RTV-1 / condensation cure Oxime Screen printable 45,000 6 h 40 2.5 200 5.5 1.21 200 Cream white ELASTOSIL® N 294 RTV-1 / condensation cure Oxime Screen printable 25,000 6 h 33 2.2 200 4.5 1.21 200 Blue / red ELASTOSIL® RT 772 RTV-2 / condensation cure (Base + Catalyst 10:1)* Alcohol 35,000 5 min / 10 min * 35 2.2 200 1.26 230 Black Self-adhesive after curing at elevated temperature Heat resistance ELASTOSIL® RT 705 1-component heat-curing / platinum cure X 72,500 6 months 42 3.5 200 3.5 1.24 230 Black ELASTOSIL® RT 706 1-component heat-curing / platinum cure X 15,000 6 months 30 2.5 200 1.23 210 Red ELASTOSIL® RT 707 W 1-component heat-curing / platinum cure X 60,000 6 months 42 3.3 270 1.18 230 White ELASTOSIL® RT 708 1-component heat-curing / platinum cure X UV fluorescent 75,000 6 months 42 3.5 300 1.36 230 Dark gray High tear resistance ELASTOSIL® RT 720 RTV-2 / platinum cure (A/B 1:1) X 35,000 6 h 40 6.0 300 1.10 180 Gray

* base component to be combined with WACKER® Catalyst T 77 or WACKER® Catalyst T 77 PLUS (please see the corresponding technical data sheet for details)

ELASTOSIL® is a registered trademark of Wacker Chemie AG. CREATING TOMORROW’S SOLUTIONS

Wacker Chemie AG PRODUCT OVERVIEW Hanns-Seidel-Platz 4 81737 München, Germany Tel. +49 89 6279-1741 [email protected] 7461D e/08.17 www.wacker.com INDUSTRIAL POTTING, ENCAPSULATION www.wacker.com/socialmedia OR CASTING APPLICATIONS

Flowable RTV silicone grades

The data presented in this medium are in accordance with the present state of our knowledge but do not absolve the user from carefully checking all supplies immediately on receipt. We reserve the right to alter product constants within the scope of technical progress or new developments. The recommendations made in this medium should be checked by preliminary trials because of conditions during processing over which we have no control, especially where other companies’ raw materials are also being used. The information provided by us does not absolve the user from the obligation of investigating the possibility of infringement of third parties’ rights and, if necessary, clarifying the position. Recommendations for use do not constitute a warranty, either express or implied, of the fitness or suitability of the product for a particular purpose. Main characteristics Brand Product Product type / Shrink- By- Additional features Self- Food Viscosity Potlife Hardness Tensile Elonga- Tear Density, Recom- Aspect / curing system free product adhesive compli- [mPa·s] [Shore A] strength tion strength cured mended color curing of curing after ance [MPa] at break [N/mm] [g/cm³] max. curing at [%] service room tem- tempera- perature ture [°C] General purpose ELASTOSIL® RT 402 RTV-2 / condensation cure Alcohol Antistatic 13,000 75 min 11 2.0 350 3 1.28 160 Light gray (Base + Catalyst 100:3)* ELASTOSIL® RT 563 RTV-2 / condensation cure Alcohol Excellent flowability 5,000 35 min 55 4.5 120 3 1.27 180 Beige (Base + Catalyst 100:4)* ELASTOSIL® RT K RTV-2 / condensation cure Alcohol Excellent flowability 7,000 30 min 45 2.0 130 3 1.22 180 Light gray (Base + Catalyst 100:4)* ELASTOSIL® RT 601 RTV-2 / platinum cure (A/B 9:1) X Crystal clear X 3,500 90 min 45 6.0 100 1.02 150 Transparent ELASTOSIL® RT 604 RTV-2 / platinum cure (A/B 9:1) X Crystal clear X 800 90 min 25 1.0 100 3 0.97 150 Transparent ELASTOSIL® RT 628 RTV-2 / platinum cure (A/B 9:1) X High tear strength 50,000 60 min 50 3.5 230 11 1.23 180 Gray ELASTOSIL® RT 743 LV-K RTV-2 / platinum cure (A/B 1:1) X Thermally conductive 1,100 2 h 20 3.0 150 1.45 180 Gray ELASTOSIL® RT 745 RTV-2 / platinum cure (A/B 1:1) X X 1,000 4 h 15 1.0 150 0.97 160 Brownish translucent ELASTOSIL® RT 745 "S" RTV-2 / platinum cure (A/B 1:1) X Soft elastomer O 1,000 4 h 5 1.0 150 0.97 160 Brownish translucent SEMICOSIL® 911 RTV-2 / platinum cure (A/B 1:1) X Soft gel, thixotropic X 8,000 1 h - - - - 0.99 160 Translucent SEMICOSIL® 912 RTV-2 / platinum cure X Soft gel X 1,000 Depending on catalyst used - - - - 0.97 160 Transparent (Base + Catalyst 10:1)** WACKER SilGel® 612 RTV-2 / platinum cure (A/B 1:1) X Soft gel, crystal clear X 1,000 150 min - - - - 0.97 160 Transparent WACKER SilGel® 613 RTV-2 / platinum cure X Soft gel, crystal clear X 200 Depending on catalyst used - - - - 0.97 160 Transparent (Base + Catalyst 10:1)** High tear resistance ELASTOSIL® RT 620 RTV-2 / platinum cure (A/B 10:1) X Excellent mechanical properties X 6,000 35 min 17 5.0 900 12 1.05 200 Translucent ELASTOSIL® RT 622 RTV-2 / platinum cure (A/B 9:1) X Excellent mechanical properties X 12,000 60 min 27 6.5 550 30 1.13 200 Reddish brown / gray ELASTOSIL® RT 623 RTV-2 / platinum cure (A/B 9:1) X Excellent mechanical properties X 10,000 30 min 31 7.5 700 30 1.12 200 Reddish brown ELASTOSIL® RT 625 RTV-2 / platinum cure (A/B 9:1) X Excellent mechanical properties X 12,000 60 min 25 6.5 600 30 1.10 180 Translucent ELASTOSIL® RT 629 RTV-2 / platinum cure (A/B 10:1) X Antistatic 8,000 40 min 31 6.0 500 25 1.13 180 Turquoise ELASTOSIL® RT 646 RTV-2 / platinum cure (A/B 10:1) X Good chemical resistance X 70,000 80 min 53 5.0 280 12 1.28 180 Beige ELASTOSIL® RT 720 RTV-2 / platinum cure (A/B 1:1) X O 35,000 6 h 40 6.0 300 1.10 180 Gray Heat resistance ELASTOSIL® RT 426 RTV-2 / condensation cure Alcohol Thermally conductive 10,000 90 min 60 4.5 120 4 1.44 200 Reddish brown (Base + Catalyst 100:3)* ELASTOSIL® RT 428 RTV-2 / condensation cure Alcohol Thermally conductive 12,000 100 min 65 6.0 90 5 1.53 200 Reddish brown (Base + Catalyst 100:3)* ELASTOSIL® RT 602 RTV-2 / platinum cure (A/B 9:1) X X 3,500 80 min 30 1.5 130 1.17 200 Light gray ELASTOSIL® RT 607 RTV-2 / platinum cure (A/B 9:1) X X 12,000 80 min 55 3.0 100 1.43 210 Reddish brown ELASTOSIL® RT 619 RTV-2 / platinum cure (A/B 9:1) X Flame retardant 9,500 60 min 50 3.9 120 1.42 230 Reddish brown ELASTOSIL® RT 675 RTV-2 / platinum cure (A/B 1:1) X Thermally conductive X 50,000 150 min 80 2.0 20 2.30 180 Reddish brown ELASTOSIL® RT 685 RTV-2 / platinum cure (A/B 9:1) X X 40,000 48 h 40 4.0 250 5 1.10 200 Cream white ELASTOSIL® RT 772 RTV-2 / condensation cure Alcohol X 37,000 5 min / 10 min *** 35 2.2 200 1.26 230 Black (Base + Catalyst 10:1)*** ELASTOSIL® RT 706 1-component heat-curing / X O 12,000 6 months 30 2.5 200 1.23 210 Red platinum cure ELASTOSIL® RT 707 W 1-component heat-curing / X O 60,000 6 months 42 3.3 270 1.18 230 White platinum cure Low-temperature flexibility ELASTOSIL® RTV-S 691 RTV-2 / platinum cure (A/B 9:1) X Flexible at very low temperature 20,000 100 min 55 4.5 130 5 1.42 200 Red ELASTOSIL® S 692 RTV-2 / platinum cure (A/B 9:1) X Flexible at very low temperature 40,000 4 h 35 1.5 200 3 1.05 200 Black SEMICOSIL® 900 LT RTV-2 / platinum cure (A/B 1:1) X Soft gel X 13,000 2 h - - - - 1.00 160 Translucent

* grade can be transformed into a self-adhesive silicone elastomer when cured with WACKER® Catalyst T 77 or WACKER® Catalyst T 77 PLUS in a mixing ratio of 10:1 (for details, please see the technical data sheets for WACKER Catalyst T 77 and T 77 PLUS) ** base component to be combined with ELASTOSIL® CAT PT, ELASTOSIL® CAT PT-F or ELASTOSIL® CAT UV to allow curing at room temperature, under heat or by UV light (please see the corresponding technical data sheet for details) *** base component to be combined with WACKER® Catalyst T 77 or WACKER® Catalyst T 77 PLUS (please see the corresponding technical data sheet for details) O self-adhesive when cured at elevated temperature

ELASTOSIL®, SEMICOSIL® and WACKER SilGel® are registered trademarks of Wacker Chemie AG. CREATING TOMORROW’S SOLUTIONS

Wacker Chemie AG PRODUCT OVERVIEW Hanns-Seidel-Platz 4 81737 München, Germany Tel. +49 89 6279-1741 [email protected] 4761G e/08.17 www.wacker.com SILICONES FOR www.wacker.com/socialmedia MEDICAL APPLICATIONS

SILPURAN® Silicones for Scar Treatment ELASTOSIL® RTV-2 Silicone Rubber Grades for Orthopedics and Prosthetics SILPURAN® RTV-2 Silicone Rubber Grades for Orthopedics and Prosthetics (WACKER Clean Room Quality)

Brand Product Mixing Viscosity Viscosity Hardness Hardness Tensile Elongation Tear Color Brand Product Blending Viscosity Viscosity Final Final Tensile Elongation Tear Brand Product Blending Color Viscosity Viscosity Final Final Tensile Elongation Tear ratio A* B* Shore A* Shore 00* strength* at break* resistance* ratio Component Component hardness hardness strength at break resistance ratio Component Component hardness hardness strength at break strength A:B [mPa·s] [mPa·s] [N/mm2] [%] [N/mm] A:B A B Shore A Shore 00 ISO 37 ISO 37 ASTM D A:B A B Shore A Shore 00 ISO 37 ISO 37 ASTM D [mPa·s] [mPa·s] ISO 868 ASTM 2240 [N/mm²] [%] 624 B D = 10 s-1 D = 10 s-1 ISO 868 ASTM [N/mm²] [%] 624 B SILPURAN® 2400 1:1 1,800 1,800 7 55 2.0 600 3 Translucent [N/mm] [mPa·s] [mPa·s] 2240 [N/mm] SILPURAN® 2400/25 1:1 3,300 2,000 < 0 25 1.3 700 3 Translucent ELASTOSIL® P 7600 1:1 4,000 2,000 < 0 28 1.2 650 3 SILPURAN® 2400 1:1 Translucent 1,800 1,800 7 55 2.0 600 3 SILPURAN® 2420 1:1 2,500 3,500 12 62 4.0 650 14 Translucent ELASTOSIL® P 7670 1:1 1,200 1,400 7 55 1.9 580 3 SILPURAN® 2400/25 1:1 Translucent 3,300 2,000 < 0 25 1.3 700 3 ELASTOSIL® P 7671 1:1 1,500 1,800 < 0 21 0.5 400 2 SILPURAN® 2420 1:1 Translucent 2,500 3,500 12 62 4.0 650 14 ELASTOSIL® P 7676 1:1 1,300 900 < 0 15 0.8 700 2 SILPURAN® 2430 1:1 Translucent 8,000 10,000 20 - 6.0 540 23 Brand Product Mixing ratio A:B Viscosity A* Viscosity B* Penetration Adhesive strength** Potlife at 23 °C ELASTOSIL® P 7683 / 25 1:1 1,200 3,500 < 0 25 1.5 650 5 SILPURAN® 2440 1:1 Translucent 15,000 10,000 35 - 7.0 400 25 [mPa·s] [mPa·s] [1/10 mm] [N/2.5 cm] [min] ELASTOSIL® P 7683 / 47 1:1 1,700 1,500 7 47 2.6 450 8 SILPURAN® 2445 1:1 Translucent 10,000 10,000 40 - 7.0 400 18 SILPURAN® 2130 1:1 1,100 1,000 220 1.8 74 ELASTOSIL® P 7684 / 40 1:1 1,500 2,300 < 0 40 2.2 670 8 SILPURAN® 2450 1:1 White 35,000 20,000 54 - 7.0 230 14

ELASTOSIL® P 7684 / 60 1:1 1,400 2,600 12 60 3.8 650 13 SILPURAN® 2438 ADH 1:1 Translucent 6,700 (D=100) 6,000 (D=100) 35 - 6.8 450 15 ELASTOSIL® PK 16 1:1 1,700 2,700 < 0 20 1.2 850 4 SILPURAN® Silicones for Advanced Wound Care

Brand Product Viscosity A* Viscosity B* Penetration Adhesive strength** Potlife at 23 °C SILPURAN® RTV-1 Silicone Rubber Grade for Orthopedic Technology and Prosthetics [mPa·s] [mPa·s] [1/10 mm] [N/2.5 cm] [min] ELASTOSIL® RTV-2 Silicone Gels for External Mammary Prostheses SILPURAN® 2100 34,000 35,500 205 2.7 73 Brand Product Color Viscosity Endhardness Tensile strength Elongation at Tear resistance D = 10 s-1 Shore A ISO 37 break ISO 37 ASTM 624 B SILPURAN® 2112 11,600 11,500 225 2.6 76 Brand Product Blending ratio Viscosity Viscosity Potlife at Gel time at Penetration, hollow cone [mPa·s] ISO 868 [N/mm2] [%] [N/mm] A:B Component A Component B 23 °C 70 °C 62.5 g for 5 sec. SILPURAN® 2114 12,000 10,000 200 3.5 70 [mPa·s] [mPa·s] [h] [min] [1/10 mm] SILPURAN® 4200 Translucent 200,000 35 5.5 300 10 SILPURAN® 2130 1,100 1,000 220 1.8 74 ELASTOSIL® P 7616-160 1:1 350 1,200 > 6 22 160 ELASTOSIL® P 7616-195 1:1 350 1,200 > 4 13 195 ELASTOSIL® P 7618 1:1 50 300 > 6 15 220 ELASTOSIL® P 7619 2:1 100 1,100 > 6 21 200 SILPURAN® Silicones for Stoma Care ELASTOSIL® P 7630 1:1 9,000 9,000 0.5 3 220 (density 0.62 g/cm3) Brand Product Viscosity A* Viscosity B* Penetration Adhesive strength** Potlife at 23 °C ELASTOSIL® P 7636 1:1 8,500 8,500 4 9 256 (density 0.76 g/cm3) [mPa·s] [mPa·s] [1/10 mm] [N/2.5 cm] [min] SILPURAN® 2142 80,000 40,000 140 7.5 90

ELASTOSIL® RTV-2 Silicone Gels for Antidecubitus Applications

SILPURAN® Silicones for Traditional Wound Care and Medical Tape Brand Product Blending ratio Viscosity Viscosity Potlife at 23 °C Penetration, hollow A:B Component A Component B [min] cone 62.5 g for Brand Product Viscosity A* Viscosity B* Penetration Adhesive strength** Potlife at 23 °C [mPa·s] [mPa·s] 5 sec. [1/10 mm] [mPa·s] [mPa·s] [1/10 mm] [N/2.5 cm] [min] ELASTOSIL® P 26028 VP 1:1 35 1,100 10 150 SILPURAN® 2117 33,000 13,000 210 3.0 40 SILPURAN® 2122 3,200 2,700 180 5.5 60 All figures are intended as a guide and should not be used in preparing specifications.

* For standard specifications and technical parameters, refer to the technical data sheet ** On stainless steel Measurement conditions for penetration: hollow cone 62.5 g, 60 sec.

All figures are intended as a guide and should not be used in preparing specifications.

ELASTOSIL® and SILPURAN® are registered trademarks of Wacker Chemie AG. CREATING TOMORROW’S SOLUTIONS

Wacker Chemie AG PRODUCT OVERVIEW Hanns-Seidel-Platz 4 81737 München, Germany Tel. +49 89 6279-1741 [email protected] 4761F e/08.17 www.wacker.com MOLD MAKING: FORM HAS NO LIMITS www.wacker.com/socialmedia ELASTOSIL® M, C and RT High-Quality Silicone Rubber

Brand Product Catalyst Mixing ratio Viscosity A Viscosity B Mixing Hardness Elongation at Tensile Tear Specific Color (cured) Potlife Vulcanization Typical mold making applications Brand Product FDA Low Easy Heat Anti- Fast Long Shrink- Resin stability Oil Ink Non- [mPa·s] [mPa·s] viscosity [Shore A] break [%] strength resistance gravity (cured) [min] time [h] viscos- mixing resist- static vulcani- potlife age bleed- resist- sag [mPa·s] [N/mm²] [N/mm] [g/cm³] ity (1:1) ant zation <0.1% ing ant

Condensation Curing Epoxy Poly- Poly- ELASTOSIL® RT 402 T 12 3% 15,000 13,000 11 350 2 > 3 1.28 Gray 75 5 Industrial printing, antistatic ester urethane ELASTOSIL® M 1470 Paste T 40 2% Kneadable Kneadable 45 230 4.5 > 10 1.28 Pink 70 4 - 5 Reproduction Condensation Curing ELASTOSIL® M 4400 T 37 / T 40 3% / 2% 30,000 25,000 23 250 2 > 3 1.30 Yellow 90 / 40 9 - 12 / 5 - 7 Reproduction ELASTOSIL® RT 402   ELASTOSIL® M 4440 T 37 / T 40 3% / 2% 25,000 20,000 37 220 2.5 > 4.5 1.23 White 80 / 50 8 - 10 / 6 - 7 Reproduction ELASTOSIL® M 1470   ELASTOSIL® M 4470 T 37 / T 40 3% / 2% 15,000 10,000 60 120 4.5 > 4 1.44 Reddish brown 90 / 40 20 - 24 / 3 - 4 Low melting metals ELASTOSIL® M 4400  ELASTOSIL® RT 480 T 37 / T 40 3% / 2% Spreadable Spreadable 55 170 4.5 > 7 1.20 Gray 120 / 20 9 / 3 Reproduction ELASTOSIL® M 4440  ELASTOSIL® M 3502 T 21 / T 51 5% / 5% Non-sag Non-sag 26 450 4.5 > 23 1.24 White 60 - 90 8 - 10 Skin mold, reproduction ELASTOSIL® M 4470    ELASTOSIL® M 4511 T 21 / T 51 5% / 5% 25,000 20,000 12 600 3.5 > 18 1.22 White 60 - 90 8 - 10 Reproduction ELASTOSIL® M 3502   ELASTOSIL® M 4512 T 21 / T 51 5% / 5% 30,000 25,000 20 500 3.5 > 24 1.19 White 60 - 90 8 - 10 Reproduction, automotive ELASTOSIL® M 4511    ELASTOSIL® M 4514 T 21 / T 51 5% / 5% 35,000 25,000 25 450 4.5 > 25 1.25 White 60 - 90 8 - 10 Reproduction ELASTOSIL® M 4512    ELASTOSIL® M 4541 T 21 / T 51 5% / 5% 40,000 35,000 32 400 5 > 30 1.16 White 60 - 90 8 - 10 Reproduction ELASTOSIL® M 4514    ELASTOSIL® M 4503 T 35 5% 45,000 40,000 25 350 5 > 20 1.16 White 90 15 - 20 Reproduction ELASTOSIL® M 4541    ELASTOSIL® M 4503  Brand Product Catalyst A : B Viscosity A Viscosity B Mixing Hardness Elongation at Tensile Tear Specific Color (cured) Potlife Vulcanization Typical mold making applications Addition Curing Components [mPa·s] [mPa·s] viscosity [Shore A] break [%] strength resistance gravity (cured) [min] time [h] ELASTOSIL® M 4370     [mPa·s] [N/mm²] [N/mm] (g/cm3) ELASTOSIL® M 4600    Addition Curing ELASTOSIL® M 4601    ELASTOSIL® M 4370 A 9:1 10,000 350 8,000 55 130 3 > 4 1.43 Reddish brown 80 6 Low melting metals ELASTOSIL® M 4615    ELASTOSIL® M 4600 B 10:1 20,000 12,000 15,000 20 800 7 > 20 1.10 Translucent 80 12 Reproduction ELASTOSIL® M 4630     ELASTOSIL® M 4601 B 9:1 15,000 800 10,000 28 700 6.5 > 30 1.13 Reddish brown 90 12 Reproduction, automotive, composite ELASTOSIL® M 4635    ELASTOSIL® M 4615 B 100:15 7,000 500 5,000 13 > 700 3 > 10 1.03 Blue 40 5 Reproduction, glove molding ELASTOSIL® M 4641     ELASTOSIL® M 4630 B 10:1 15,000 800 10,000 28 700 6.5 > 30 1.13 White 90 12 Construction ELASTOSIL® M 4642     ELASTOSIL® M 4635 B 10:1 20,000 700 15,000 37 480 7 > 30 1.14 White 90 12 Construction ELASTOSIL® M 4643     ELASTOSIL® M 4641 A 10:1 50,000 400 30,000 43 > 300 > 4.5 > 25 1.07 Translucent 90 12 Prototype ELASTOSIL® M 4644     ELASTOSIL® M 4642 B 10:1 20,000 700 15,000 37 480 7 > 30 1.14 Dark red 90 12 Reproduction, composite ELASTOSIL® M 4645     ELASTOSIL® M 4643 B 9:1 40,000 800 25,000 48 300 5 > 10 1.31 Gray 90 12 Reproduction, automotive ELASTOSIL® M 4670     ELASTOSIL® M 4644 A 10:1 70,000 500 50,000 40 400 5.5 > 25 1.07 Translucent 80 12 Prototype (slight oil bleeding) ELASTOSIL® RT 620     ELASTOSIL® M 4645 A 10:1 50,000 3,500 35,000 40 330 5 > 28 1.06 Translucent 80 12 Prototype (strong oil bleeding) ELASTOSIL® RT 623     ELASTOSIL® M 4670 A 10:1 120,000 7,000 80,000 55 250 5.5 > 12 1.28 Beige 90 12 Reproduction, prototype, composite ELASTOSIL® RT 629      ELASTOSIL® RT 620 B 10:1 7,000 1,200 6,000 17 900 5 > 12 1.05 Translucent 35 4 Industrial printing ELASTOSIL® C 1200      ELASTOSIL® RT 623 B 9:1 15,000 800 10,000 31 700 7.5 > 30 1.12 Reddish brown 30 5 Industrial printing ELASTOSIL® M 4115    ELASTOSIL® RT 629 B 10:1 14,000 900 8,000 31 500 6 25 1.13 Turquoise 40 3 Industrial printing, antistatic ELASTOSIL® M 4125     ELASTOSIL® C 1200 A 1:1 20,000 20,000 20,000 25 500 5 25 1.05 Blue 20 1 Composite ELASTOSIL® M 4125 F      ELASTOSIL® M 4115 A 1:1 2,500 2,500 2,500 17 400 3 5 1.05 Translucent 12 1 Cosmetic ELASTOSIL® VARIO 15     ELASTOSIL® M 4125 A 1:1 6,000 6,000 6,000 25 500 5 25 1.05 Translucent 60 12 Industrial printing (printing roller) ELASTOSIL® VARIO 40    ELASTOSIL® M 4125 F A 1:1 6,000 6,000 6,000 28 500 5 25 1.05 White 15 2 Industrial printing (printing roller), reproduction ELASTOSIL® VARIO 15 CAT Vario / Cat Vario F 10:1 5,000 3,000 15 ... * 900 6.5 15 1.06 Translucent 150 / 2 6 / 0.25 All  For prepreg use  Strong oil bleeding ELASTOSIL® VARIO 40 CAT Vario / Cat Vario F 10:1 15,000 10,000 ... 40 ** 450 8 15 1.15 Translucent 150 / 2 6 / 0.25 All

The data are only intended as a guide and should not be used in preparing specifications. * Can be blended by adding ELASTOSIL® VARIO 40 ** Can be blended by adding ELASTOSIL® VARIO 15

ELASTOSIL® is a registered trademark of Wacker Chemie AG. CREATING TOMORROW’S SOLUTIONS

PRODUCT OVERVIEW

ELASTOSIL® COLOR PASTE FL

ELASTOSIL® Color Paste FL Similar to RAL* BfR FDA Conditions of use Standard colors Yellow RAL 1016   2) Use B-H** Red iron oxide RAL 3013   Blue RAL 5022   White RAL 9010   Deep black RAL 9011   3) Other colors Yellow RAL 1006   Ivory RAL 1014  Yellow RAL 1021   3) Use B-H** Yellow RAL 1026  Yellow RAL 1026 F   3) Use C-H** Yellow RAL 1033   Use B-H** Red-brown RAL 2001   Orange RAL 2004  Orange RAL 2004 F   4) Use B-H** Dark red RAL 3000 Red RAL 3020   4) Use B-H** Red violet RAL 4002   1) Blue RAL 5002   Dark blue RAL 5010   5) Light blue RAL 5015  Light blue RAL 5015 F   Heliogreen RAL 6004   Green RAL 6010   5) Gray RAL 7000  Deep black RAL 9005  Black RAL 9005 F   UV fluorescent n.a.

 Complies with the requirements of BfR Recommendation IX 1) maximum quantity: 1 weight-% The ELASTOSIL® COLOR PASTE FL products show temperature resistance of “Pigments for coloring plastics“ and of FDA regulation 2) maximum quantity: 3 weight-% at least 42 d / 175 °C or 21 d / 200 °C and UV-resistance for at least 21 d CFR 21 § 177.2600 ”Rubber Articles Intended for Repeated 3) maximum quantity: 4 weight-% (continuous exposure in UV weathering chamber). Use“ when the maximum quantity limits are respected. 4) maximum quantity: 5 weight-% * The RAL values shown in the table are only intended as 5) maximum quantity: 10 weight-% ELASTOSIL® is a registered trademark of Wacker Chemie AG. a guide and should not be used in preparing specifications. ** Refer to 21 CFR §176.170 (c) (4–1–05 Edition), www.fda.gov

Wacker Chemie AG Hanns-Seidel-Platz 4, D-81737 München [email protected], www.wacker.com, www.wacker.com/socialmedia

Recommendations for use do not constitute a warranty, either express or implied, of the fitness or suitability of the product for a particular purpose. 7461E e/08.17 Wacker Chemie AG 08.17

Hanns-Seidel-Platz 4 / 81737 München, Germany

Tel. +49 89 6279-1741 7461e [email protected] www.wacker.com www.wacker.com/socialmedia