Abstract: Ozone resistance of vulcanized chloroprene homopolymers and copolymers, chlorinated isobutylene/isoprene copolymers, and blends of any of the above with up to equal weight of styrene/butadiene copolymer or natural rubber is improved by incorporating into the polymer or polymer blend prior to vulcanization about 0.5-5 parts per 100 parts by weight of polymer or polymer blend of one or more of bis(5-norbornene-2-methyl) phosphite, tris(5-norbornene-2-methyl) phosphite, and tris(5-norbornene-2-methyl) phosphate. These esters also improve the flex resistance of chloroprene copolymers with sulfur and their blends with styrene-butadiene copolymers or natural rubber. In addition to improving ozone and flex resistance of the above polymers and polymer blends, these esters do not cause staining or discoloration of the vulcanized polymers.

Abstract: Bis(5-norbornene-2-methyl) phosphite, tris(5-norbornene-2-methyl) phosphite, and tris(5-norbornene-2-methyl) phosphate, as well as a mixture of the above esters are novel compositions of matter, useful as antiozonants in chloroprene polymers and in blends of chloroprene polymers with diene rubbers.

Abstract: Addition to unvulcanized chloroprene polymer of 0.5-5 parts by weight of certain triarylphosphines per 100 parts of polymer improves the processing safety of unvulcanized stocks of polymer prepared in the absence of elemental sulfur and reduces the compression set of vulcanizates. In chloroprene-sulfur copolymers, the addition of triarylphosphines results in improved flex resistance.