Polymer blend having low compression set

Abstract

There is a need for halogen-free polymeric compositions for utilization in gaskets and seals that offers high tensile strength and high tear strength as well as good resistance to compression set. Seals for automotive body applications, such as, windows, hoods, trunks, and doors, and building applications, such as window glazing gaskets and weather strips, should be dimensionally stable, provide low compression set, and offer outstanding sealing characteristics over a broad temperature range. They must be capable of sealing out noise, wind and water, while providing long-term ultraviolet light resistance. This invention discloses a polymeric composition comprising (1) a compatibilizing polymer selected from the group consisting of ethylene vinyl acetate and ethylene alkyl acrylate co(polymer), (2) a polyolefin, (3) a curative system, such as a free radical generator, (4) a rubbery polyolefin, such as an ethylene-propylene-diene monomer polymer and (5) a rubbery polymer which is comprised of repeat units which are derived from (a) butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl acrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c) acrylonitrile, (d) styrene and (e) a crosslinking agent. The polymeric compositions of this invention can also optionally contain a plasticizer.