Carbon Additives for Polymer Compounds

Polymers

Graphite & Coke

www.timcal.com

1 Who are we?

TIMCAL Graphite & Carbon has a strong tra- agement and continuous process improve- dition and history in carbon manufacturing. Its ment, all TIMCAL manufacturing plants comply first manufacturing operation was founded in with ISO 9001-2008. 1908. TIMCAL Graphite & Carbon is committed to Today, TIMCAL facilities produce and market a produce highly specialized graphite and car- large variety of synthetic and natural graphite bon materials for today’s and tomorrow’s cus- powders, conductive carbon blacks and water- tomers needs. based dispersions of consistent high quality. TIMCAL Graphite & Carbon is a member of IMERYS, Adhering to a philosophy of Total Quality Man- a world leader in adding value to minerals.

Where are we located?

With headquarters located in Switzerland, TIMCAL The Group’s industrial and commercial activities Graphite & Carbon has an international pres- are managed by an experienced multinational ence with production facilities and commercial team of more than 430 employees from many offices located in key markets around the globe. countries on three continents.

HQ Bodio, Switzerland Willebroek, Belgium Lac-des-Îles, Canada Terrebonne, Canada Graphitization & pro- Manufacturing & pro- Mining, purification and Exfoliation of natural cessing of synthetic cessing of conductive sieving of natural graphite, processing of graphite, manufacturing carbon black graphite flakes natural and synthetic of water-based dispersions, graphite processing of natural graphite & coke and manufacturing & processing of silicon carbide

Baotou, China Changzhou, China Fuji, Japan For the updated list of Purification, intercalation, Manufacturing of Manufacturing of commercial offices and exfoliation, size reduc- descaling agents and water-based dispersions distributors please visit tion, shape modification processing of natural www.timcal.com and sieving & classifying graphite of natural graphite

What is our vision?

To be the worldwide leader and to be recog- nized as the reference for innovative capability in the field of carbon powder-based solutions.

2 Contents

ENSACO® Conductive Carbon Black TIMREX® Graphite and Coke Carbon additives for polymer compounds

The products

• Introduction to ENSACO® Conductive Carbon Black p. 4

• Introduction to TIMREX® Graphite and Coke p. 5

• ENSACO® Conductive Carbon Black for polymer compounds p. 6

• TIMREX® Graphite and Coke for polymer compounds p. 8

Typical applications for ENSACO® Conductive Carbon Black

• Electrically conductive plastics p. 10

• Rubber p. 14

• Power cables and accessories p. 17

Typical applications for TIMREX® Graphite and Coke

• Self lubricating polymers p. 18

• Filled PTFE p. 20

• Thermally conductive polymers p. 22

3 Introduction to ENSACO® Conductive Carbon Black

Conductive carbon blacks are carbon blacks TEM picture of ENSACO® 250 G Carbon Black showing the high with high to very high stucture (or void volume) level of aggregation. allowing the retention of a carbon network at By courtesy of University of low to very low filler content. The void volume Louvain (Louvain-La-Neuve) can originate from the interstices between the carbon black particles, due to their complex ar- rangement, and from the porosity.

100 nm

How ENSACO® Conductive Carbon STM picture of the surface of ENSACO® 250 G Carbon Black Blacks are produced 5x5 nm. The Timcal carbon black process has been de- By courtesy Prof. Donnet - Mulhouse veloped around 1980 and is commercially ex- ploited since 1982. The plant uses most modern technology. The process is based on partial oil oxidation of carbochemical and petrochemical origin. The major difference with other partial combustion carbon black technologies lies in the aerodynamic and thermodynamic condi-

the product tions: • low velocity; • no quench; • no additives. SEM picture of ENSACO® 250 G Carbon Black illustrating the high void volume. This leads to a material with no or nearly no By courtesy of University of sieve residue on the 325 mesh sieve and allows Louvain (Louvain-La-Neuve) the highest possible purity. The granulation process has been developed to achieve an homogeneously consistent product maintaining an outstanding dispersibility. It is in fact a free-flowing soft flake characterised by a

homogeneous and very low crushing strength 100 nm that guarantees the absence of bigger and harder agglomerates. The process enables the production of easily dispersible low surface area conductive carbon blacks as well as very high surface area conductive carbon blacks. The unique combination of high structure and low surface area also contributes to give outstanding dispersibility and smooth surface finish. The low surface area materials show a chain-like structure comparable to acetylene black. The very high surface area materials belong to the Extra Conductive (EC) family. Although ENSACO® Carbon Blacks are slightly more graphitic than furnace blacks, they are quite close to the latter ones as far as reinforcement is concerned. ENSACO® Carbon Blacks combine to a certain extent both the properties of furnace and acetylene black, reaching the optimal compromise.

4 Introduction to TIMREX® Graphite and Coke

Graphite finds wide application thanks to its carbon atom and participate in covalent bond- favourable combination of properties such as: ing with three surrounding carbon atoms in the graphite planes. The fourth electron is located • low friction, chemical inertness and in the remaining 2p orbital, which projects absence of inherent abrasiveness; above and below the graphite plane, to form • high thermal conductivity, thermal part of a polyaromatic π-system. stability and electrical conductivity; • film forming ability on metal surfaces; Delocalisation of electrons in π-electron sys- • relatively inoffensive nature of both tem is the reason of graphite’s high stability powders and products of combustion. and electrical conductivity. Interlamellar bonding was once thought to be weak and mainly These properties are a consequence of the la- the result of Van der Waals forces, however, it mellar graphite structure and the anisotropic now appears that interlamellar bonding is re- nature of chemical bonding between carbon inforced by π-electron interactions. Graphite is atoms. In graphite, three sp2 hybrid orbitals therefore not intrinsically a solid lubricant and (each containing one electron) are formed requires the presence of adsorbed vapours to from the 2s and two of the 2p orbitals of each maintain low friction and wear. the product

How TIMREX® Graphite and Coke powders are produced

TIMREX® Primary Synthetic Graphite TIMREX® Primary Synthetic Graphite is produced in a unique highly controlled graphitization process which assures narrow specifications and unequalled consistent quality thanks to: monitoring of all production and processing stages, strict final inspection, and clearly defined development processes. TIMREX® Primary Synthetic Graphite shows unique properties thanks to the combination of a consistent purity, perfect crystalline structure and well defined texture.

SEM picture of TIMREX® Graphite showing the perfect crystalline structure. TIMREX® Natural Flake Graphite TIMREX® Natural Flake Graphite is produced in a wide range of products distinguished by particle size distribution, chemistry and carbon content. Timcal mines the graphite from its own source in Lac-des-Îles, Quebec, Canada. Further processing can be done either in Lac-des-Îles or in our processing plant in Terrebonne, Quebec, Canada. All TIMREX® “Naturals” are thoroughly controlled in our laboratories to ensure quality, consistency and total customer satisfaction.

Lc c TIMREX® Coke TIMREX® Petroleum Coke is calcined at appropriate temperature with low ash and sulphur content, well defined texture and consistent c/2 particle size distribution.

c/2 = Interlayer distance Lc = Crystallite height

5 ENSACO® Conductive Carbon Black for polymer compounds

Typical values

Property Test Method UNIT ENSACO® 150 G ENSACO® 210 G ENSACO® 250 G ENSACO® 260 G ENSACO® 350 G

Form Granules (*) Granules Granules (*) Granules Granules

BET Nitrogen Surface Area m2/g 50 55 65 70 770 ASTM D3037

OAN Absorption ml/100 g 165 155 190 190 320 ASTM D2414 (1)

COAN Crushed OAN ml/100 g 95 95 104 104 270 ASTM D2414 (1)

Pour Density kg/m3 190 210 170 170 135 ASTM D1513

Moisture (as packed) % 0.1 0.1 0.1 0.1 1 max ASTM D1509

Sieve residue 325 mesh (45 μm) ppm 2 2 2 2 10 ASTM D1514 the product Ash Content % 0.1 0.1 0.01 0.01 0.03 ASTM D1506

Volatile Content % 0.2 max 0.2 max 0.2 max 0.2 max 0.3 max TIMCAL Method 02 (2)

Sulphur Content % 0.5 max 0.5 max 0.02 0.02 0.02 ASTM D1619

Toluene Extract % 0.1 max 0.1 max 0.1 max 0.1 max 0.1 max ASTM D4527

pH 8–11 8–11 8–11 8–11 8–11 ASTM D1512

Volume Resistivity Ohm.cm 2000 max (3) 500 max (3) 10 max (3) 5 max (3) 20 max (4) TIMCAL Method 11 (3) (4)

(1) Spring: 0.9 lbs/inch; 10 g of carbon black (2) Weight loss during heating between 105 and 950°C (3) 25% carbon black in HDPE Finathene 47100 (4) 15% carbon black in HDPE Finathene 47100

(*) ENSACO® 150 and ENSACO® 250 are also available in powder form.

6 ENSACO® Conductive Carbon Black for polymer compounds

Typical effects on polymer compounds

Property ENSACO® 150 G ENSACO® 210 G ENSACO® 250 G ENSACO® 260 G ENSACO® 350 G

Form Granules (*) Granules Granules (*) Granules Granules

BET Nitrogen Surface Area (m2/g) 50 55 65 70 770

OAN Oil Absorption (ml/100 g) 165 155 190 190 320

Conductivity     

Dispersibility     

Purity     

Water absorption very low very low very low very low high the product Surface smoothness     

Electrical/Mechanical      properties balance

Resistance to shear     

MRG Comments to Easy strippable (Mechanical All polymers application domains insulation shields Rubber Goods)

excellent  very good  good  quite good  difficult 

(*) ENSACO® 150 and ENSACO® 250 are also available in powder form.

7 TIMREX® Graphite and Coke for polymer compounds

Typical values

Particle size range Grade Ash Scott density Surface area d90 (µm) (%) (g/cm3) Bet (m2/g) Synthetic Graphite KS Graphite KS 6 0.06 0.07 26.0 KS 15 0.05 0.07 20.0 KS 5-25 0.03 0.23 8.6 KS 44 0.06 0.19 9.0 KS 5-44 0.02 0.31 5.9 KS 150 0.06 0.42 3.0

0 25 50 75 150

SFG Graphite SFG 6 0.07 0.07 17.0 SFG 44 0.07 0.19 5.0 SFG 150 0.03 0.29* 2.5

0 25 50 75 150

T Graphite T 15 0.08 0.10 13.0 T 44 0.07 0.18 10.0 T 75 0.07 0.21 9.8 the product 0 25 50 75 150

Natural Graphite

PP Flake PP 10 <5 0.05 10.0 Graphite PP 44 <5 0.11 4.8

0 25 50 75 150

LSG Flake LSG 10 <1 0.08 9.3 Graphite LSG 44 <1 0.20 5.4

0 25 50 75 150

cumulative size Large flake min. 80% <150 mesh (105 µm) M150 <6 0.4* 1.9 graphite min. 80% >150 mesh (105 µm) 80X150 <6 0.6* 0.9

Coke

oversize control PC Coke min. 98% <45 µm (air jet sieving) PC 40-OC 0.15 0.47* 10.0 max. 0,1% >106 µm (air jet sieving)

Grade Ash Density Particle size Solid content (%) (g/cm3) distribution (%) 20°C d90 (µm) Water-based dispersion

LB Dispersion LB 1300 0.10 1.17 6.5 27.5

Grade Ash Scott density Form d90 (%) (g/cm3) (µm)

Special Grade

C-THERM™ C-THERM™001 <0.3 0.15* soft granules

C-THERM™011 <2.5 0.15* soft granules

C-THERM™002 <0.3 0.04* powder 81

C-THERM™012 <2.5 0.04* powder 81

* bulk density

8 EnSACo® Conductive Carbon Black TIMREX® Graphite for polymer compounds

Conductivity Targets

9 Electrically conductive plastics

The selection of a Some typical final conductive carbon black plastics applications ENSACO® Conductive Carbon Blacks find their • handling of electronic components: carrier applications in an unlimited number of plastics. boxes, carrier trays, carrier tapes, etc.; The combination of the polymer type and grade • films: antistatic and conductive films, and the carbon black grade are determining the packaging films, garbage bags, etc.; overall electrical and mechanical performance. • automotive industry: fuel injection systems, The main parameter influencing the final con- anticorrosion systems, fuel tank inlet, ductivity of a finished part in a given polymer is electrostatically paintable parts, etc.; the type and level of carbon black used. • transport: mobile phone parts, wheels, k cti v e C arb on B lac O ® Condu The higher the structure of the carbon black, containers, bins, pallets, etc.; the lower the level of carbon black needed to • computer: antistatic articles for computer & achieve the required conductivity. Nevertheless, accessories, CD player, etc.; in a minor way, other parameters like the ad- • health: medical applications, cleanroom ditives in presence, the compounding or pro- equipments, articles for antistatic cessing conditions may also influence the final workplaces, etc.; conductivity of parts. • antistatic flooring; Low surface area conductive carbon blacks • heating element; show a particular advantage on dispersion and • sensors; processing. • PTC switches; Percolation curves – correlating the volume re- • UV protection and pigmentation. sistivity and the carbon black percentage – are a useful comparative tool to predict the con- In the following pages there are some of the re- ductivity in place and to select the more appro- sults of experimental work carried out on EN-

on s f o r E N SAC T y p ical a pp licati priate system. These curves are valid for a given SACO® Conductive Carbon Blacks in different formulation and sample preparation technique. polymer compounds. The selection of the conductive carbon black will also influence: The data shown here are given as orientation • the compounding behaviour and are valid for the particular formulations and (dispersibility, resistance to shear, mixing sample preparation technique mentioned. cycle, melt flow index, extrusion throughput); Results in other polymers, full studies and pub- • the surface appearance of the finished mate- lications are available upon request. rial (number of surface defects); • the mechanical properties (polymer property retention, reinforcement); • the overall price – performance ratio.

The preparation of a conductive compound Suitable mixing equipments for the preparation of black conductive compounds include internal mixers, twin screw extruders, single screw kneader machines and LCM. The feeding of low bulk density, soft flake-type carbon blacks into extruders requires the use of twin screw feeders and separate introduction on an already molten polymer (split feeding technology).

10 EnSACo® ConduCTIvE CARBon BLACkS In HdpE

Infl uence of the carbon black type on the various carbon blacks in HdpE resistivity 109 ENSACO® 250 G Compounding: laboratory Brabender internal mixer. Processing: compression moulding. ENSACO® 260 G 107 ENSACO® 350 G The higher the structure of the carbon black, the lower the percolation threshold. 105

103

10 Volume Resistivity [ Ohm.cm ]

0.1 0 10 20 30 40 50

Carbon Black %

At a concentration very near to the percolation Resistivity vs mixing time - 18% carbon black level, when overmixed, ENSACO® 260 G off ers a 800 higher consistency in resistivity resulting from CARBon BLACk ConduCTIvE FoR EnSACo® TYpICAL AppLICATIonS ENSACO® 250 G its higher shear stability in extreme working 700 ENSACO® 260 G conditions. 600

500

400

300

200

100 Volume Resistivity [ Ohm.cm ]

0 4 5 6 7 8 9 10

Brabender Mixing Time [min]

At a concentration far above the percolation Resistivity vs mixing time - 25% carbon black level, both blacks are very stable in resistivity when overmixed. ENSACO® 260 G shows a con- 7.0 ENSACO® 250 G sistent lower resistivity. 6.5 ENSACO® 260 G 6.0

5.5

5.0

4.5

4.0

3.5 Volume Resistivity [ Ohm.cm ]

3.0 4 5 6 7 8 9 10

Brabender Mixing Time [min]

11 EnSACo® ConduCTIvE CARBon BLACkS In LdpE

Infl uence of the carbon black type and of the various carbon black in LdpE MFI 0.3 and 36 (g/10 min) MFI of the starting polymer on the resistivity 108 Compounding: laboratory Brabender internal mixer. E250 G LD 0.3 Processing: compression moulding. E250 G LD 36 106 N472 LD 0.3 N472 LD 36 The higher the structure of the carbon black, 4 P-type LD 0.3 the lower the percolation threshold. 10 P-type LD 36 At equal structure, the carbon black of lower surface area gets an advantage on resistivity 102 that may be coming from the easier dispersion Volume Resistivity [ Ohm.cm ] resulting in smoother compounding. The higher 100 the meltfl ow index of the starting polymer, the 0 5 10 15 20 25 30 35 lower the percolation threshold. Carbon Black Concentration [%] TYpICAL AppLICATIonS FoR EnSACo® ConduCTIvE CARBon BLACk ConduCTIvE FoR EnSACo® TYpICAL AppLICATIonS

EnSACo® ConduCTIvE CARBon BLACkS In pp

Infl uence of the carbon black type on the ppH MI54 (230 °C/5 kg) with various conductive carbon blacks resistivity. Relation between resistivity and melt fl ow index 104 E250 G high structure Compounding and processing: twin screw extruder Haake PTW16 low surface area 3 and realization of tapes. 10 N472 high structure high surface area

2 At same structure level, the carbon black with 10 the lowest surface area has the smallest impact on fl uidity reduction. 101 Volume Resistivity [ Ohm.cm ]

100 0 10 100

MFI [230 °C/5 kg] [g/10 min]

Infl uence of carbon black loading and 106 processing on the resistivity 13.50% E250 G 4.6E + 10 105 15% E250 G Compounding: ZSK25 twin screw extruder. Processing: injection moulding. 104

103 Injection moulding generates more shear than 171 compression moulding. The closest to the per- 102 54 24 colation, the more visible is that eff ect. A con- 10 101 6

centration safety margin can overcome this Volume Resistivity [ Ohm.cm ] phenomenon. 100

strands pellets + pressed pellets + plaques injection moulding

12 EnSACo® ConduCTIvE CARBon BLACkS In pC

Infl uence of the carbon black type volume Resistivity (vR) in function of carbon black loading on the resistivity 12 ENSACO® 250 G Compounding: ZSK57 twin screw extruder. 11 Processing: injection moulding. ENSACO® 350 G 10 9 8 7 6 5 4 3 2

Volume Resistivity [log (Ohm.cm)] 1 5 10 15 20 25

Carbon Black concentration [%]

Infl uence of the carbon black type on Izod impact strength, notched, in function of vR mechanical and rheological performances 12 ENSACO® 250 G Compounding: ZSK57 twin screw extruder.

Processing: injection moulding. 11 ENSACO® 350 G CARBon BLACk ConduCTIvE FoR EnSACo® TYpICAL AppLICATIonS 10 ]

2 9 Although the concentration for percolation is double the level with ENSACO® 250 G, most 8 mechanical properties are still better. 7 Izod [ kJ/m 6

4 1 2 3 4 5 6 7 8 9 10 11 12

Volume Resistivity [log (Ohm.cm)]

Tensile Strength for both carbon blacks is almost Tensile strength in function of vR at the same level. 68 ENSACO® 250 G 67 ENSACO® 350 G 66

62 Tensile Strength [ MPa ] 61

60 1 2 3 4 5 6 7 8 9 10 11 12

Volume Resistivity [log (Ohm.cm)]

13 Rubber

Carbon black is one of the main ingredients A few conductive applications: of any rubber compound. Conductive carbon • belt cover compounds; blacks are before all carbon blacks, to be mixed • flooring; and handled as any other reinforcing or semire- • conveyer belts; inforcing carbon black. They are high structure • hoses for fuel, for conveying of powders, etc.; materials bulky by nature. Although the com- • cylinder coating; mon carbon blacks are conductive by nature • shoe soles; and impart also conductivity to the compounds • seals. onduc t iv e C arbon B lack when used in sufficiently high loading, conductive carbon blacks have the advantage to reach ENSACO® 150 and 250 are also used in non con- conductivities at lower loading and are often ducting applications where the compounder used to give the final boost to a compound al- can take profit of the low surface area and high ready filled with other carbon blacks. As carbon structure of those blacks: black structure is the parameter determining • low hysteresis with relatively high hardness; the conductivity, structure being an additive • good thermal aging; property, the combinations of conductive and • very good tear strength; normal black can be predicted. • very good dispersion, very good mechani-

® C t ions for E NSACO Specifications of rubber compounds being usu- cal performance at thin layer. ally quite complex and conductivity being only one of the numerous physical requirements, the use of carbon black blends is very often the A few non-conductive applications: only solution. In some specific cases, especially • antivibration systems; in special polymers, it occurs that the conduc- • textile coating; tive carbon black is used by its own in order to • membranes;

Typical applica maintain mechanical properties and processing • articles exposed to chipping and chunking. at a good level. ENSACO® carbon blacks are, quite close to fur- In the following pages there are some of the re- nace blacks as far as the reinforcing activity is sults of experimental work carried out on EN- concerned. Especially the low surface area car- SACO® Conductive Carbon Blacks in different bon blacks, grades 150, 250 and 260, are, due to rubber compounds. their very easy dispersion, quite performing in The data shown here are given as orientation most rubber compounds. ENSACO® 350 is also and are valid for the particular formulations and used in some compounds where small additions sample preparation technique mentioned. Re- are required. sults in other polymers, full studies and publica- tions are available upon request.

14 NBR conductive hose compound

A B A B

Compound Compound Compound Compound ENSACO® 250 N-472 ENSACO® 250 N-472

NBR NT 3945 100 100 t90% (min) 11.46 11.37 onduc t iv e C arbon B lack ENSACO® 250 25 Mooney ML (1+4) at 100° C 45.7 47.2

N-472 25 Vulcanizate data unaged at RT

N-550 40 40 Shore A Hardness 70.9 72.2

ZnO 4 4 Stress-strain Stearic acid 0.5 0.5 Elongation at break (%) 339 311

DOP 30 30 Tensile Strength (MPa) 13.8 14.8

Sulphur 0.4 0.4 Modulus 100% (MPa) 3.9 4.6 ® C t ions for E NSACO Methyl Thuads 2 2 Modulus 300% (MPa) 8.6 10.3

Amax 2 2 Modulus 500% (MPa) 12.6 14.4

By courtesy of Bayer Resistivity (Ohm.cm) 79 360

Tear Strength (N/mm) 32.4 31.8 Typical applica

Conductive CR conveyor belt cover compound

A B A B

Compound Compound Compound Compound ENSACO® 250 N-472 ENSACO® 250 N-472

Bayprene 610 (CR) 100 100 Dispersion Rating DIK 86.8 85.8

Buna CB 10 2 2 t90% (min) 20.7 21.8

MgO Powder 4 4 Mooney ML(1+4) at 100°C 62 64

N-472 30 Vulcanizate data unaged at RT

ENSACO® 250 30 Shore A hardness 62 64

Vulkanox DDA 1.5 1.5 Stress-strain Vulkanox 4020 0.5 0.5 Elongation at break (%) 676 540

Ingralen 450 15 15 Tensile Strength (MPa) 23.4 22.4

ZnO Powder 5 5 Modulus 50% (MPa) 1.2 1.4

Rhenogran ETU-80 0.2 0.2 Modulus 100% (MPa) 2.4 2.7

Stearic acid 0.5 0.5 Modulus 300% (MPa) 9.2 11.5

By courtesy of Bayer Modulus 500% (MPa) 16.1 20.6

Compression Set 24h at 18 19 70°C (%)

Resistivity (Ohm.cm) 100 800

15 FkM ConduCTIvE CoMpoundS

1 2 3 4 5 6 7 8 9

vITon A-32J - Fluoroelastomer 100 100 100 100 100 100 100 100 100

Mgo 3 3 3 3 3 3 3 3 3

Ca(oH)2 3 3 3 3 3 3 3 3 3 MT black (n990) 20 ------20 20

EnSACo® 250G - 10 20 30 - - - 10 20

n-472 SCF - - - - 10 20 30 - -

vpA-2 1 1 1 1 1 1 1 1 1 Total phr 127.0 117.0 127.0 137.0 117.0 127.0 137.0 137.0 147.0

MT black % 15.7 0.0 0.0 0.0 0.0 0.0 0.0 14.6 13.6

E250G % 0.0 8.5 15.7 21.9 0.0 0.0 0.0 7.3 13.6

SCF N-472 % 0.0 0.0 0.0 0.0 8.5 15.7 21.9 0.0 0.0

Experimental data provided by DuPont Dow Elastomers, Japan

Mooney viscosity ML (1+10’), 100°C t 90% (min)

180 20 (*) * 160 18 TYpICAL AppLICATIonS FoR EnSACo® ConduCTIvE CARBon BLACk ConduCTIvE FoR EnSACo® TYpICAL AppLICATIonS 140 16 14 120 12 100 10 80 8 60 6 40 4 20 2 0 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 8 9

(*) Rejected because uncurable. Vulcanizate properties at 177°C for 10 min.

Log Resistivity (ohm.cm) Compression set (%)

14 70

12 60

10 50

8 40

6 30

4 20

2 10

0 0 1 2 3 4 5 6 8 9 1 2 3 4 5 6 8 9

Shore A

100 90 80 70 60 50 40 30 20 10 0 1 2 3 4 5 6 8 9

16 Power cables and accessories

Conductive carbon black is used in semicon Typical EVA/NBR strippable compounds compounds for conductor and insulator shields. The requirements for those compounds are be- Compound Compound Compound sides processing, a sufficient electrical conduc- N-472 ENSACO® 210 ENSACO® 250 tivity, a smooth or even supersmooth surface Levaprene 450 90 90 90 finish, and high purity. For strippable or easy strippable compounds Perbunan NT 8625 10 10 10 these requirements are added to a specific ad- Rhenogran P60 3 3 3 hesion strength between the insulating layer N-472 40 and the insulator shield. These strippable or k cti v e C arb on B lac O ® Condu easy strippable layers have to peeled of by hand E 210 40 or using a specific peeling device. E 250 40 Typical polymer compositions are polyolefins or N-550 40 40 40 copolymers; for strippable compounds quite often blends of EVA and NBR are used. Antilux 654 10 10 10 Zn Stearate 1 1 1

Rhenovin DDA-70 1.4 1.4 1.4

Rhenofit TAC/CS 4.3 4.3 4.3

Percadox BC-408 5 5 5

Viscosity ML (4+1) 56 44 48

Rheometer@180 t90% 3.6 3.6 3.8

Mechanical properties

Non aged (diff. aged) on s f o r E N SAC T y p ical a pp licati

Tensile strength MPa 16.5 (-19) 16.9 (-15) 16.9 (-15)

Elongation at break % 215 (-58) 180 (-50) 170 (-53)

Modulus 100% MPa 11 12.2 12.7

Shore A 87 (+7) 90 (+4) 89 (+7)

Peel strength hot air 100°C N 7 3 4 - after 3 days N 5 4 3 - after 21 days N 5 3 4

Volume resistivity (Ohm.cm) 210 6600 410

Typical EEA/EBA semicon compounds

Compound Compound EEA EBA

EEA 100

EBA 100

E 250 30 30

Peroxide

Mixing cond. L/D15; Feed BC; Truput 30 Resistivity @ RT 7.2 5.6

Resistivity @ 90°C 37 22

Carbon black dispersion: <3µm 97.9 99.4

Die pressure (bar) 229 239

MFI (g/10 min) 23.12 21.39

Specific net mixing energy (KWh/kg) 0.313 0.326

Protrusion N°/m2 0 0

17 Self lubricating polymers

The choice of a polymer-based self lubricating Graphite powder is widely used in polymer solid for a particular application depends mainly composites, either alone or in combination with upon the operating conditions of: temperature, reinforcing fibres, PTFE or various inorganic chemical environment and the maximum values fillers, e.g. mica, talc (bottom, right table). Ap- of pressure (p) and sliding speed (v). For each plications include gears, dry sliding bearings, polymer or composite material, a pv limit is quot- seals, automotive and micro-mechanical parts. ed, which corresponds to the pressure times the sliding speed at which the material fails, either The properties of graphite which favour its use due to unacceptable deformation, or to the high in polymer composites are: frictional energy dissipated causes surface melt- • low friction lamellar solid ing, softening and excessive wear. (reduces friction); The pv limit of a polymeric material may be in- • tendency to form a transfer film on the creased by increasing its mechanical strength countersurface (resistance to deformation), thermal con- (assists in wear reduction, particularly when ductivity (reduction in surface temperatures) graphite is applied as water based dispersion and by decreasing friction (reduces frictional i.e. LB 1300); heating). In practice, thermoplastics (with the • high thermal conductivity exception of PTFE) are mainly used as pure (decreases temperature rise due to frictional solids, since their wear resistance and frictional heating); coefficient, are satisfactory for most applica- • electrical conductivity tions. Solid lubricant fillers or fibre reinforce- (prevent build-up of static charge which may ment (glass fibres, carbon fibres, textiles) are be a problem in some cases); only employed under the more extreme condi- • chemically inert tions of load and speed. (used in conjunction with PTFE in corrosive

e on s f o r TIMREX® G ra p hite a nd Cok T y p ical a pp licati The major polymers employed as self lubricat- environments); ing solids/composites, are illustrated below. • high thermal stability (favours use in high temperature applications, e.g. polyimide graphite composites may be used up to 350°C).

18 Incorporation of graphite powder into a ther- Ball/disc Friction & Wear data: polystyrene/graphite fi ller moplastic polymer will generally result in a reduction in the friction coeffi cient (with the ex- 12 0.4 wear ception of PTFE) but rarely improves the wear friction 10 resistance. This behaviour is illustrated in the -12 0.3 two graphs, which show the mean friction co- 8

effi cient and specifi c wear rate for a stainless /Nm)x10 3 steel ball (ø = 5 mm) rubbing on discs of graph- 6 0.2 ite fi lled polystyrene and polyamide at constant 4 load (32.5 N) and speed (0.03 m/s). The specifi c

0.1 friction coecient wear rates of the graphite-polymer composites 2 were calculated from the diameters of the wear speciﬁc wear (m 0 0 tracks and the contact geometry. pure 30% 50% polystyrene T 75 T 75 In the case of polystyrene, addition of 30–50% of a high purity macrocrystalline synthetic Infl uence of graphite addition on the specifi c wear rate and friction of polystyrene graphite (T 75), reduced both friction and wear rate. With polyamide however, addition of a graphite similar to T 75 reduced the friction Ball/disc Friction & Wear data: polyamide 6/graphite fi ller coeffi cient, but caused a slight increase in the wear rate, with the fi ner particle size powder 20 0.4 wear (KS 6) giving the better result. In the case of friction low density polyethylene and polypropylene, -12 15 0.3 graphite incorporation causes both an increase

in friction and wear. FoR TIMREX® GRApHITE And CokE TYpICAL AppLICATIonS /Nm)x10 3 10 0.2 The results described above are thought to be related to the strength of adhesion at the pol-

5 0.1 friction coecient ymer-graphite interface, which depends upon the wettability of the powder by the molten pol- speciﬁc wear (m 0 0 ymer, powder surface area to volume ratio, sur- pure 30% 30% face chemistry, etc. In simple terms, polystyrene polyamide KS 6 KS 44 shows a strong affi nity for the graphite surface, while polyolefi ns show a weak affi nity. Interfa- Infl uence of graphite addition on the specifi c wear rate and friction of polyamide 6 cial adhesion increases with increasing powder surface area to volume ratio, or decreasing particle size.

For this reason relatively fi ne graphite powders (95%<15 microns) are recommended for thermoplastics. The strength of thermosetting polymers is much less sensitive to fi ller-polymer interactions, therefore coarser graphite powders may be used (typically 95%<75 microns). For thermoplastics, the viscosity of the polymer-graphite melt during extrusion/ moulding will also depend on the graphite particle size, which should be appropriate. Excessive graphite surface area may also lead to void formation in the fi nished composite, due to desorption of The above mentioned results are the confi r- physisorbed vapours in the hot melt. mation that TIMREX® graphite powder is an excellent additive to produce self-lubricated High graphite purity is generally desirable in or- polymers. The addition of TIMREX® graphite der to minimize wear, although this parameter powder to the unfi lled polymers allow for a re- is unlikely to be important in the presence of duction of the friction coeﬃ cient and in most abrasive fi llers (glass fi bre, carbon fi bre). of the cases to a reduction of the wear rate. These results are achieved by a synergic combinations of all the good properties of TIMREX® graphite powder that among the others are: the high degree of crystallinity, the extremely high purity, the optimal texture and the perfect particle size distribution. All of them linked by a common factor: the consistency!

19 Filled PTFE

Polytetrafluoroethylene (PTFE) exhibits a very TIMREX® Graphite low coefficient of friction and retains useful me- and Coke fillers in filled-PTFE chanical properties at temperatures from -260 to +260 °C for continuous use. TIMREX® PC 40-OC Coke The crystalline melting point is 327 °C, much TIMREX PC 40-OC Coke is calcined at high tem- higher than that of most other semi-crystalline peratures offering low sulphur concentration, polymers. Furthermore, PTFE is nearly inert low content of oversize particles, high apparent chemically and does not adsorb water, leading density and high chemical stability against most to excellent dimensional stability. On the one chemical substances. TIMREX® PC 40-OC Coke hand, these characteristics of PTFE are very is added to the virgin PTFE in a percentage by useful in the matrix polymer of polymer-based weight between 10 and 35% along with small composites which are used in sliding applica- percentage of graphite. tions. On the other hand, PTFE is subjected to Compounds made of PTFE and TIMREX® PC marked cold flow under stress (deformation 40-OC Coke have excellent wear resistance and creep) and reveals the highest wear among and deformation strength and compared to the the semicrystalline polymers. virgin PTFE, they have practically unchanged However, these disadvantages are very much chemical resistance and friction behaviour. improved by incorporating suitable fillers, al- Typical final materials that can be produced lowing the use of PTFE in fields otherwise pre- with coke filled PTFE are: cluded to this polymer. engineering design components, slide bearings, The treated PTFE is generally known as filled- valve housing and valve seats for chemical ap- PTFE. There are many kinds of filled- PTFE plications, piston sealing and guiding elements composite because various fillers are incorpo- for dry-running compressors. rated into PTFE and one or more materials can

e on s f o r TIMREX® G ra p hite a nd Cok T y p ical a pp licati be used simultaneously. Usually, these fillers are TIMREX® KS44 Synthetic Graphite in form of powders or fibers intimately mixed NTIMREX® KS 44 is a Primary Synthetic Graph- with the PTFE. ite obtained by the full graphitisation of amor- The addition of fillers to the PTFE improves or phous carbon materials through the well known modifies its properties depending upon the na- Acheson process. The process parameters in the ture and quantity of filler: Acheson furnace such as temperatures and resi- • remarkable increase in wear resistance; dential times are all optimised in order to achieve • decrease of deformation under load and of the perfect degree of crystallinity and the lowest creep; level of impurities whereas others minor adjust- • reduction of thermal expansion; ments are made during the material sizing and • some types of filler increase the thermal and conditioning. electric conductivity. The percentage of TIMREX® KS 44 used in the filled PTFE vary between 5 and 15%. Filled PTFE is often not as strong and TIMREX® KS 44 can be used alone or in combina- resilient as virgin PTFE. Sometimes, the filler tion with glass or coke. limits the resistance to chemical agents and TIMREX® KS 44 lowers the coefficient of friction modify the electrical properties. and is, therefore, often added to other types of filled PTFE for improving this property (and also to improve the lifetime of the cutting tools during for instance the production of gaskets and seals). It improves the deformation under load, strength and, to a minor degree the wear. Like coke, it serves well in corrosive environments. PTFE filled with TIMREX® KS 44 are often used in steering and shock-absorber gasket, bearings as well as in slide films for anti-static applications.

20 Influence of TIMREX®Graphite and Coke fillers in filled-PTFE

Wear resistance virgin PTFE shows much high wear as a result of the destruction of the banded structure due to easy slippage between the crystalline lamellae in the bands. The presence of well distributed carbon particles in the filled PTFE partially avoid the slippage between the crystalline lamellae in the bands and therefore the wear resistance is improved.

Deformation strength virgin PTFE deformation behaviour is somehow similar to the mechanism previously described. In someway the deformation phenomena could be explained by the tendency of slippage that occurs between the crystalline lamellae. How- ever, in this case the presence of well distributed carbon particles in the filled PTFE offers only a partial explanation to the phenomena because also hardness of these particles is important in

determine an improvement of the deformation e on s f o r TIMREX® G ra p hite a nd Cok T y p ical a pp licati behaviour.

Friction Coefficient the coefficient of friction for various filled PTFE composites is weakly dependent upon the in- corporated filler, because a thin PTFE film generally exists at the interface between the body and counter-body. Consequently the coefficient of friction is both similar in the filled PTFE and virgin PTFE. This evidence is true as long as no oversize particles are present in the filler. In fact the presence of oversize particles could lead to a radically modification of the coefficient of friction. Because of that in carbons as well as in other fillers is very important the control of oversize particles.

21 Thermally conductive polymers

What is thermal conductivity? Thermal conductivity The ability of a material to conduct heat is known of graphite as its thermal conductivity. Thermal conductiv- Graphite is an excellent solution for making ity itself is nothing else than the transportation polymers thermally conductive when electri- of thermal energy from high to low tempera- cal conductivity is also tolerated. Graphite ture regions. Thermal energy within a crystalline operates by a phonon collision mechanism, solid is conducted by electrons and/or discrete very different from the percolation mechanism vibrational energy packets (phonons*). Each ef- occurring with metallic powders. This mecha- fect, phonons and movement of free electrons, nism, together with the particular morphology contributes to the rate at which thermal energy of graphite particles, helps to meet the re- moves. Generally, either free electrons or phon- quired thermal conductivity at lower additive ons predominate in the system. levels without any abrasion issues. In addition, due to its particular structure, thermal con- *Phonons ductivity is different in the different directions In the crystalline structures of a solid mate- of the crystal. It is highly conducting along rial, atoms excited into higher vibrational fre- its layers (ab direction or in-plane) and less quency impart vibrations into adjacent atoms conducting perpendicular to the layers (c dir- via atomic bonds. This coupling creates waves ection or through-plane) because there is no which travel through the lattice structure of a bonding between the layers. material. In solid materials these lattice waves, In particular, expanded graphite, is well known or phonons, travel at the velocity of sound. as an excellent thermally and electrically con- During thermal conduction it is these waves ductive additive for polymers. On the way to which aid in the transport of energy. graphene, high aspect ratio expanded graphite is thermally more conductive when com-

e on s f o r TIMREX® G ra p hite a nd Cok T y p ical a pp licati pared to conventional carbon materials such as standard graphite and carbon fibres. However, the very low bulk density of expanded graphite makes it very difficult to feed into a polymer melt using common feeding/mixing technologies. In order to overcome the feed issues en- countered by compounders with expanded graphite, TIMCAL has developed a range of products belonging to the TIMREX® C-THERM™ carbon-based product family.

Grade Features Form Ash Effect on content (%) thermal conductivity

TIMREX®KS family Standard powder < 0.1 medium (spheroids) (through-plane +)

TIMREX®SFG family Standard powder < 0.1 medium (flakes) (in-plane +)

TIMREX®C-THERM™011 High aspect ratio soft granules < 2.5 high (pure)

TIMREX®C-THERM™001 High aspect ratio soft granules < 0.3 high (pure +)

22 THERMALLY ConduCTIvE poLYMERS ing the measurement, but also on the type of Thermally conductive polymers are able to polymer, the sample history (type and condi- evenly distribute heat generated internally tions of compounding and processing) and the from a device and eliminate “hot spots.” Pos- measurement method. sible applications for thermally conductive A full set of measurements to determine me- plastics include heat sinks, geothermal pipes, chanical properties in PP were performed and LED light sockets, heat exchangers, appliance are available to customers. When tested at the temperature sensors and many other industrial same loadings, C-THERM™ 001/011 imparts applications. Also thermally conductive elas- similar mechanical properties as conventional tomers can be found in a wide variety of in- carbon materials. dustrial applications such as gaskets, vibration dampening, interface materials, and heat sinks. As highlighted in the fi gure, the low thermal conductivity of virgin PPH (~0.38 W/m.K) could be increased by one order of magni- 4.0 In-plane tude already at relatively low addition level In-plane 3.5 inj > Through-plane (~3.5 W/m.K at 20% C-THERM™). The “through- Through-plane 3.0 plane” thermal conductivity is about the half of 2.5 the longitudinal “in-plane” thermal conductivity. These results indicate that the anisotropy 2.0 of the graphite particles is conferred to the 1.5 fi nal compound, due to their alignment dur- 1.0 ing the injection molding process. This is an 0.5 Thermal Conductivity [ W/m.K ] important property that has to be taken into 0 account by design engineers. Of course the Virgin PPH 20% 20% 20% FoR TIMREX® GRApHITE And CokE TYpICAL AppLICATIonS thermal conductivity strongly depends not ENSACO® TIMREX® TIMREX® 250G KS25 C-THERM™ only on the sample orientation (direction) dur-

Timcal locations

production plants

Commercial offi ces

Distributors present in many countries. For the updated list please visit www.timcal.com

23 EUROPE Asia-Pacific Americas

TIMCAL Ltd. TIMCAL Japan K.K. TIMCAL America Inc. Group Head Office Tokyo Club Building 13F 29299 Clemens Road 1-L 6743 Bodio 3-2-6 Kasumigaseki, Westlake (OH) 44145 Switzerland Chiyoda-ku USA Tel: +41 91 873 20 10 Tokyo 100-0013 Tel: +1 440 871 75 04 Fax: +41 91 873 20 19 Japan Fax: +1 440 871 60 26 [email protected] Tel: +81 3 551 032 50 [email protected] Fax: +81 3 551 032 51 TIMCAL Belgium NV/SA [email protected] TIMCAL Canada Inc. Appeldonkstraat 173 990 rue Fernand-Poitras 2830 Willebroek Changzhou TIMCAL Terrebonne (QC) J6Y 1V1 Belgium Graphite Corp. Ltd. Canada Tel: +32 3 886 71 81 188# Taishan Road Tel: +1 450 622 91 91 Fax: +32 3 886 47 73 Hi-Tech Zone Fax: +1 450 622 86 92 [email protected] Changzhou 213022 [email protected] China TIMCAL Deutschland GmbH Tel: +86 519 851 008 01 Berliner Allee 47 Fax: +86 519 851 013 22 40212 Düsseldorf [email protected] Germany Tel: +49 211 130 66 70 Changzhou TIMCAL Fax: +49 211 130 667 13 Graphite Corp. Ltd. [email protected] Shanghai Branch Office c/o IMERYS (Shanghai) France Representative Office 288, Jiu Jiang Road c/o IMERYS Hong Yi Plaza 154-156 rue de l’Université Unit 1102-1105 75007 Paris, Shanghai 200001 France China Tel: +33 1 495 565 90/91 Tel: +86 21 613 782 88 Fax: +33 1 495 565 95 Fax: +86 21 613 780 02 [email protected] [email protected]

UK Representative Office Singapore Representative Office Tel: +44 1 270 212 263 c/o IMERYS Asia Pacific (Singapore) Fax: +44 1 270 212 263 80 Robinson Road #19-02 [email protected] 068898 Singapore Tel: +65 67 996 060 Fax: +65 67 996 061 [email protected]