Verfahren zum Vulkanisieren von Mischpolymerisaten

摘要

The Specification describes rubbery copolymers of ethylene, at least one alpha-olefin of the formula R-CH=CH2 in which R is a C1-C18 alkyl group and a substituted or unsubstituted 5-alkenyl-2-norbornene of the formula: in which each R is hydrogen or a C1-C6 alkyl radical and Z is an alkenyl radical in which the double bond is internal, the copolymer having an iodine number between 5 and 60, an ethylene units content of at least 20% and an alpha-olefin units content of at least 25% by weight. Specific copolymers referred to contain as the alpha-olefin propylene, 1-butene, 4,4-dimethyl-1-hexene, 5,5-dimethyl-1-octene, 6-methyl-1-heptene, 1-decene or 5,6,6-trimethyl-1-heptene and as the third component a 5-alkenyl-2-norbornene in which the alkenyl group is 21-butenyl, 21-ethyl-21-butenyl, 21-ethyl-11-butenyl, 11-propenyl, 21-heptyl-11-undecenyl, 21-propyl-21-pentenyl, 21-nonyl-21-heptenyl, 21-methyl-21-decenyl 21-hexyl-21-butenyl, or 21-octyl-21-butenyl. The copolymerization may be effected by saturating a solvent with the olefins, adding the alkenyl-norbornene and polymerizing at 20-60 DEG C. in the presence of (a) vanadium tetrachloride or vanadyl chloride and (b) R3Al or R2AlX in which R is C1-C12 alkyl and X is chlorine or bromine; the molar ratio of Al:V may be 1-10:1 and the vanadium concentration in the reaction zone may be 5x10-4 to 5x10-3 moles/litre. Suitable solvents are hydrocarbons and halogeno-hydrocarbons. The copolymerization is stopped before the concentration of polymer exceeds 5% by weight by deactivating the catalyst with an alcohol, extracting with dilute hydrochloric acid and washing then flashing off the solvent. Suitable antioxidants which may be added to the copolymer are 2,21-methylene-bis (6-tert.butyl-4-methylphenol) or 4,41-thiobis(2-tert.butyl-5-methyl phenol). The elastomer may be cured by one of the following methods; (a) heating with sulphur by conventional methods, (b) heating with organic peroxides or (c) heating with an organic peroxide and an N-alkyl or N-aryl maleimide, an N,N1-alkylene or arylene bismaleimide, an N,N1-alkylene or arylene bisacrylamide or a cyclic triacryloylhexahydrotriazine. In the Examples the copolymers are sulphur-cured and strengthened by addition of 4 g. of carbon black per 10g. of copolymer.ALSO:5-Alkenyl-2-norbornenes of the formula wherein Z is an alkenyl radical with an internal double bond and each R is hydrogen or an alkyl group may be prepared by (a) dehydration of the alcohol obtained by reacting a ketone Y-CH2-CO-CH2-Y1 with the Grignard reagent of 5-haloalkyl-2-norbornene in ether to obtain or in which Y is hydrogen or alkyl and Y1 is alkyl or (b) by Diels-Alder condensation of a diolefin Z-CH=CH2 with a cyclopentadiene of the formula The dehydration of (a) above is effected by refluxing with anhydrous copper sulphate in toluene; the Diels-Alder condensation is effected by heating to 150-250 DEG C. By replacing the diolefine by another of the formula R11-CH=CH-CH=CH-R111 two compounds are formed of the formulae and In examples, cyclopentadiene is supplied to the Diels-Alder condensation as its dimer.