GB1343730A - Cross-linking of olefin polymers - Google Patents

Abstract

1343730 Crosslinking olefin polymers SIEMENS AG 19 April 1971 [17 April 1970] 27147/71 Addition to 1294154 Heading C3P Olefin polymers are crosslinked by heating in the presence of a ditertiary peroxide and 0À1 to 20 weight per cent, based on the polymer, of a radical transfer agent which is a polymethine of one of formulae wherein R 1 is aryl, R 2 , R 3 and R 4 are aryl or hydrogen, n is 0 or 1, R<SP>1</SP> 1 , R<SP>1</SP> 2 , R<SP>1</SP> 3 and R<SP>1</SP> 4 are aryl or hydrogen or R<SP>1</SP> 1 and R<SP>1</SP> 2 and/or R<SP>1</SP> 3 and R<SP>1</SP> 4 can together form the remaining atoms of an aryl ring, and R 5 and R 6 are hydrogen or aryl or when R 5 is hydrogen R 6 may be a heterocyclic group which does not contain reactive hydrogen bonded to a hetero atom. The polymer may be a polyethylene or ethylene/propylene copolymer rubber. An acenaphthylene compound may also be present as transfer agent/stabilizer. Specified peroxides are dicumyl peroxide, di-t.butyl peroxide, 2,5-bis-t.butylperoxy-2,5-dimethylhexane, 1,3-bis(t.butylperoxy)isopropylbenzene, n-butyl-4,4-bis(t.butylperoxy)valerate and 2,2- bis(t.butylperoxy)butane. Specified transfer agents are 1-phenylbutadiene-1,3, 1,4-diphenylbutadiene-1,3, phenyl fulvene, diphenyl fulvene, #-phenyl- and #,#<SP>1</SP>-diphenyl benzofulvene, 9- phenyl- or 9-diphenyl-methylene fluorenes, furfurylindene-cyclopentadiene, cinnamylidene fluorene, cinnamylidene fulvene and cinnamylidene indene. The transfer agents and other additives may be added to the polymer as a suspension or solution in an inert liquid medium, e.g. chlorinated biphenyl. The crosslinked products may be used for insulating electrical components, e.g. by curing thereon in a high boiling liquid such as a molten salt. Examples describe the crosslinking of (1,2 and 4) polyethylene and (3) ethylene/propylene rubber.