Some high-performance elastomers, such as fluoroelastomers, fluorosilicones, and silicone rubbers, have reduced mechanical properties at high temperatures. This is especially true of tear strength; some elastomers tear easily when being removed from molds at 177 to 191°C (350 to 375°F). Zonyl® fluoroadditives greatly reduce damage from sticking or tearing during mold release, and increased abrasion resistance is a benefit to the molded end product.
Lower-temperature elastomers, such as Nordel® EPDM, Neoprene®, and Hypalon® CP can also benefit from property enhancement with fluoroadditives.
Processing
Standard elastomer processing methods for incorporation of carbon black or other additives can be used to blend Zonyl® fluoroadditives. BR Banbury internal mixers or two-roll mixers are suitable.
Most elastomers are themselves mixtures of dissimilar ingredients, mechanically compounded with a high proportion of the host generic elastomer. Lengthy curing and molding at elevated temperature is often required. The addition of another ingredient, such as a Zonyl® fluoroadditive powder, is readily adapted to existing practice.
Zonyl® fluoroadditives can be added up to 30 weight percent of the base elastomer in a formulation. The mechanical action during roll milling of most elastomers ensures good distribution.
Low viscosity elastomers, such as fluorosilicones or silicones, may require the use of a concentrate (master batch) of up to 50 weight percent additive, which can be brought to a reduced concentration with added elastomer. The additional shearing action in the second step may be necessary for some additives, such as MP 1500, to develop optimum reinforcing for improved tear strength.
Recommended Grades
Zonyl® PTFE grades MP 1000, MP 1400, MP 1500, and MP 1600 are easily dispersed into elastomers at high concentrations. All four products are equally effective in improving abrasion resistance and lowering the coefficients of friction. MP 1000, MP 1400 and MP 1600 can be used in EEC countries for food contact applications. MP 1400 and MP 1600 should be used if FDA compliance for food use is necessary.
MP 1500 is preferred for enhancement of tear strength and toughness for a variety of elastomers, especially when high temperature curing or service is involved. It is designed to provide a reinforcing action aided by the development of short fibers, ribbons, or platelets. This structure, formed during compounding, allows high levels of incorporation of the powder with uniform dispersion. Use of 10 weight percent has been found to be effective, but up to 30 percent has been added without compromising elastic behavior.
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