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Composites I ADDITIVES

VINNAPAS® SOLID RESINS Low-Profile Additives for Composites Vinnapas® Polyvinyl acetate as a low-profile additive Applications in -reinforced (FRP)

1. General Information In addition to VINNAPAS® B and UW 2. Low Profile Technology homopolymer grades, WACKER also VINNAPAS® is a solid, homogeneous, manufactures carboxylated VINNAPAS® Unsaturated composites odorless and nontoxic copolymer C grades based on vinyl for fiber-reinforced plastics comprise synthetic polyvinyl acetate resin. acetate and crotonic . unsaturated polyester resins compound- ed with styrene, various fillers, peroxide WACKER produces VINNAPAS® homo- VINNAPAS® (polyvinyl acetate) resins catalysts, thickening agents, mold polymer B and UW grades with varying are used as low-profile additives in FRP release agents, low-profile additives degrees of , varying mo- composites. The great versatility of and reinforcing glass . Low-profile lecular weights and varying viscosities VINNAPAS® low-profile additive resins technology includes various compound- in solution. has led to many FRP applications, ing techniques and various molding successfully combining zero shrink, techniques depending on the desired Class A surface quality, full viscosity quality and shape of the molded parts. control and design flexibility.

On the following pages, we introduce our VINNAPAS® (polyvinyl acetate) resins for use as low-profile additives in FRP composites.

VINNAPAS® is a registered trademark of Wacker Chemie AG. Good compatibility with all major compounding techniques

2.1 Description of the Compounding Other compounding techniques used to RTM: Resin Techniques harden and transform unsaturated poly- In the RTM process, a combination of resin composites into functional continuous mat is laid in the mold cavity. SMC: Sheet Molding Compound parts include: A matching mold half is fixed to the first SMC is prepared by applying a paste half tightly. Afterwards, a pressurized containing unsaturated , BMC: Bulk Molding Compound resin system mixed with a free-radical styrene, , peroxide catalyst and a low- BMC is manufactured in a sigma- initiator is pumped into the closed mold profile additive (LPA) solution in styrene blade mixer and the resulting compound containing the reinforcement. The resin onto a film. Chopped glass is either injection-molded or compres- and fiber remain in the mold until cross- strand (glass-fiber) is dropped onto the sion-molded under high pressure and linking takes place. Then the composite UP resin paste sheet, and a second layer at elevated temperature. can be removed. The material may be of the SMC paste is applied to sand- : In the pultrusion process cured at room temperature or in a heated wich the glass-fiber layer. This multilayer for thermoset resins, fiber reinforcement mold by proper choice of initiator. The sheet runs through compaction rolls and is pulled through a resin impregnation RTM process is affected by such param- is rolled up for maturation. After matu- area to coat the reinforcement. Then it eters as: resin characteristics, resin ration, the compound has a very high is processed through preform plates to injection pressure, mold temperature or viscosity, which allows good glass-fiber begin to shape the fiber/resin bundle. vacuum conditions of the system. distribution during mold flow and easy Afterwards, it is pulled through a heated VINNAPAS® homopolymer grades handling of the material. Once matura- to cure the resin. This process pro- provide superior stability and excellent tion is complete and the required viscos- duces little waste material. The cured shrinkage-control properties. ity has been reached, SMC can be cut part pultruded from the die requires into shapes and compression-molded at no further processing. The quality of high pressure and elevated temperature. pultruded composites is affected by process variables such as pull speed, die temperature or quality of fibers/ resins. VINNAPAS® homopolymer grades provide superior stability and excellent shrinkage-control properties. SMC paste Cutter

Polyamide film

Compacting rolls SMC paste

Polyamide film

Finished SMC

2.2 Polyester Resin Applications: SMC Production Molding techniques

Unsaturated polyester resin molding These problems were the consequence Benefits of VINNAPAS® Solid Resins: compounds are transformed into of the high polymerization shrinkage functional articles by a wide variety of unsaturated polyester resin with the • Zero shrinkage/expansion in of molding techniques. crosslinking styrene . They FRP composites They include: are remedied by adding certain thermo- • Excellent gloss and surface • Hand lay-up and spray-up plastics to the molding compound. The smoothness • and most effective shrinkage-control additive • Effective thickening of SMC continuous was found to be polyvinyl acetate. With • Easy to process and to formulate • Pultrusion polyvinyl acetate compounds with zero • Consistent high quality • Injection molding shrinkage and zero expansion can be • Good mechanical properties • formulated. This results in moldings • Fast and complete solubility in styrene with excellent surface smoothness and The UP composite is typically dimensional stability without warpage. ® modified with LPA for the following VINNAPAS C Grades molding techniques: 3.1 VINNAPAS® as Low-Profile Additive Very effective thickening in combination with MgO or CaO • Compression molding of SMC or VINNAPAS® is a most effective thermo- VINNAPAS® UW Grades BMC at high pressure and elevated anti-shrink (low-profile) additive Moderate thickening effect without temperature in UP resin composites processed at MgO or CaO • Injection molding of BMC at high high molding temperatures. VINNAPAS® B Grades pressure and elevated temperature No thickening effect • Pultrusion: for special applications In addition to the zero shrink effect, • Resin transfer molding (RTM): for certain high-temperature unsaturated Typical SMC Formulation special applications, the UP resin polyester applications, such as SMC and Components Parts by wt batch is modified with LPA BMC, require effective thickening for easy Unsaturated Polyester Resin handling of the composite and for good Orthophthalic polyester resin 65.0 3. Low-Profile Additives glass-fiber distribution during mold flow: (65% in styrene) ® Carboxylated VINNAPAS C grades, in Additives Both SMC and BMC technology used to combination with magnesium oxide or VINNAPAS® PVAC 35.0 be subject to severe limitations because calcium oxide, are the perfect thickening (40% in styrene) of the following problems: systems for unsaturated resin composites. t-Butylperbenzonate 1.0 ® • Warpage of molded parts prevented Carboxylated VINNAPAS C grades, in Peroxy ester 0.2 the molding of close tolerances combination with a thickening paste, result Pigment dispersion 10.0 • Depressions (“sink marks”) on the in a high and constant viscosity level. Zinc stearate 2.0 surface After maturation, this combination is ideal Filler • Rough, wavy surfaces resulted in a to prevent exudation of the thermoplastic poor appearance resins. Carboxyl-free homopolymer Calcium carbonate 3 micron 180.0 VINNAPAS® B and UW grades are used Glass-fiber when only moderate or no thickening of 50 mm chopped glass-fiber, wt % 27– 29 the UP resin composite is required. 5 VINNAPAS® Low-profile additives: overview

VINNAPAS® LP Additives Grade Type Solids Appearance Acid1 Viscosity2 Molecular Viscosity in styrene4 content mg KOH/g mPas weight3 Mw 40% in mPas VINNAPAS® LL 8251 carboxylated PVAc 100% Flakes 6–9 2.0–2.3 ~ 30 000 ~ 300 VINNAPAS® C 341 carboxylated PVAc 100% Flakes 6–8 3.5–3.8 ~ 60 000 ~ 1 000 VINNAPAS® C 501 carboxylated PVAc 100% Flakes 6–9 7.5–9.5 ~ 130 000 ~ 6 500 VINNAPAS® B 60 sp PVAc 100% Pellets < 0.5 3.5–5.0 ~ 65 000 ~ 1 000 VINNAPAS® B 100 sp PVAc 100% Pellets < 0.5 5.0–6.5 ~ 90 000 ~ 2 000 VINNAPAS® UW 1 FS PVAc 100% Beads < 0.5 8.0–11.0 ~ 130 000 ~ 5 000 VINNAPAS® UW 4 FS PVAc 100% Beads < 0.5 23–30 ~ 280 000 ~ 66 000 VINNAPAS® UW 10 FS PVAc 100% Beads < 0.5 35–55 ~ 360 000 ~ 160 000

1 Acid number: number of milligrams of potassium hydroxide required to neutralize the alkalireactive groups in 1 gram of VINNAPAS® LP Additive 2 Viscosity-conditions: 10% solution of VINNAPAS® LP Additive in ethylacetate, ASTMD 445–06; 20 °C 3 SEC conditions: PS standard; THF; 60 °C; weight average 4 Brookfield PHL 002 /23 °C

® Application Preparing a VINNAPAS Solution in Styrene: SMC BMC Pultrusion RTM Add the VINNAPAS® resin to the styrene VINNAPAS® LL 8251     while stirring well to prevent the formation ® VINNAPAS C 341     of lumps during dissolution. This should VINNAPAS® C 501     usually be done at room temperature; VINNAPAS® B 60 sp     some temperature increase during the VINNAPAS® B 100 sp     dissolving process is normal due to shear VINNAPAS® UW 1 FS     friction. Protect the resulting solution from VINNAPAS® UW 4 FS     direct light during storage. Additional temperature will increase the dissolving VINNAPAS® UW 10 FS     speed. However, a control of solution  = Recommended  = Suitable stability is necessary due to the mono- meric styrene’s tendency to polymerize. The table at the top lists VINNAPAS® 3.2 VINNAPAS® Solution in Styrene VINNAPAS® LPA solution typically contains grades used as low-profile additives in 40% solids, but this may vary depending UP resin composites and also demon- VINNAPAS® low-profile additives (LPA) on the molecular weight of the VINNAPAS® strates the broad range of molecular are almost exclusively used as solutions grade and the compound formulation. weights/viscosities covered by both the in styrene. The solid VINNAPAS® poly- Average figures for VINNAPAS® LPA homopolymer and the carboxylated vinyl acetate resins are readily soluble in solutions in styrene are: VINNAPAS® grades. styrene and thus enable you to prepare ® VINNAPAS® solutions in styrene accord- VINNAPAS C grades 40% ing to your needs. VINNAPAS® B grades 40– 45% VINNAPAS® UW grade 30– 40%

6 General Information

VINNAPAS® beads VINNAPAS® pellets VINNAPAS® flakes

Dangerous Chemical Regulations Storage of VINNAPAS® Polyvinyl Packaging Acetate All VINNAPAS® resins (B, UW and C Standard packaging for VINNAPAS® B, grades) are not classified as dangerous VINNAPAS® resins exhibit excellent UW and C grades: chemicals under the German hazardous stability when stored under cool and Paper bags, 25 kg net weight. substances legislation – Gefahrstoffver- dry conditions. However, because Other types of packaging are available ordnung (GefStoffV, 11th issue 1997) – they are thermoplastic materials, it is upon request. and therefore do not have to be labeled strongly suggested that the lower- as such. A certificate of origin, details molecular-weight VINNAPAS® B grades Shelf Life on labeling and safety data sheets are in particular be stored below 20 °C to available upon request. prevent caking. All VINNAPAS® resins Please refer to the technical data sheet. will retain their free-flowing charac- teristics when stored in a cool (less Further information regarding individual than 20 °C) and dry place. Even if products (technical data sheets, material the material is blocked, the chemical safety data sheets) is available at: nature of the polymer remains un- changed. Infoline +49 8677 83-7979 [email protected] www.wacker.com/vinnapas

7 wacker Chemie ag .05 hanns-seidel-platz 4 7 81737 münchen, germany www.wacker.com/contact www.wacker.com/vinnapas 1 supersedes 5919e/0 1 . 11 5919e/

The data presented in this brochure are in accordance with the present state of our knowledge, but do not absolve the user from carefully checking all supplies immediately upon receipt. We reserve the right to alter product constants with the scope of technical progress or new developments. The information given in this brochure 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.