Process for crosslinking and, if desired, foaming natural or synthetic homo- and/or copolymers

Claim 1

A process of crosslinking a polymer select from the group consisting of high pressure polyethylene of low density, low pressure polyethylene of high and low density, chlorinated polyethylene, chlorosulfonated polyethylene, polypropylene, polybutyl-(1), poly-[4-methylpentene-(1)], polyvinyl chloride, polyvinyl acetate, polyacrylic acid esters, ethylene-vinyl acetate copolymers, ethylene-propylene butylene copolymers, ethylene-propylene-diene terpolymers, ethylene-butylene copolymers, ethylene-propylene butylene copolymers, ethylene-vinyl chloride copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, ethylene-carbon monoxide copolymers, natural rubber (polyisoprene), polybutadiene, polychloroprene (neoprene), synthetic polyisoprene, ethylene-propylene-ethylidene norbornene (or cyclopentadiene or hexadiene or butadiene) copolymer, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-styrene-acrylonitrile copolymer, styrene-isoprene block polymer, butyl rubber (isobutylene-isoprene copolymer), silicone rubber, saturated polyesters, polyamides, polyurethanes, polyethers, and polyacetals comprising: mixing with a 100 parts by weight of said polymer (i) from about 0.02 to about 3.0% by weight of at least one member selected from the group consisting of an azo ester, an azo ether, and a mixture thereof wherein the azo ester and azo ether have the following formulas ##STR4## wherein: R is selected from the group consisting of linear or branched alkyl of 1 to 11 carbons, substituted or unsubstituted cycloalkyl of 5 to 6 carbons, substituted or unsubstituted phenyl, substituted or unsubstituted aralkyl of 7 to 15 carbons, and R 3 --CO--, wherein the substituent is alkyl of 1 to 10 carbons, R 3 is selected from the group consisting of H, linear or branched alkyl of 1 to 10 carbons, substituted or unsubstituted cycloalkyl of 5 to 6 carbons, substituted or unsubstituted phenyl, and substituted or unsubstituted aralkyl of 7 to 15 carbons, wherein the substituent is alkyl of 1 to 10 carbons, R 1 and R 2 are independently selected from the group consisting of linear or branched alkyl of 1 to 10 carbons, substituted or unsubstituted cycloalkyl of 5 to 6 carbons, substituted or unsubstituted phenyl, and substituted or unsubstituted aralkyl of 7 to 15 carbons, wherein the substituent is alkyl of 1 to 10 carbons, R 1 R 2 C-- can join together to form a group selected from substituted or unsubstituted cycloalkyl of 5 to 6 carbons wherein the substituent is alkyl of 1 to 10 carbons, --OR and --R 1 can join together to form a member selected from the group consisting of --OCO--CH 2 --CH 2 -- and --OCO--CH 2 --CH 2 --CH 2 --, R 4 , R 5 and R 6 are independently selected from the group consisting of linear or branched alkyl of 1 to 10 carbons, substituted or unsubstituted cycloalkyl of 5 to 6 carbons, substituted or unsubstituted phenyl, and substituted or unsubstituted aralkyl of 1 to 10 carbons, wherein the substituent is alkyl of 1 to 10 carbons, and R 5 R 6 C-- can join together to form a member selected from the group consisting of substituted or unsubstituted cycloalkyl of 5 to 6 carbons wherein the substituent is alkyl of 1 to 10 carbons and (ii) from about 0.05 to about 10% by weight of at least one crosslinking intensifier having at least two relative carbon-carbon double or triple bonds, and heating the polymer mixture at a temperature above about 150° C. but not to the point where the polymer will substantially degrade and at a pressure of from about atmospheric to about 300 psia until crosslinking is effected.