GB1120572A - Polybutadiene rubber composition - Google Patents

Abstract

A polybutadiene composition comprises from 80 to 99% by weight of polybutadiene rubber having cis-1,4-structure of from 20 to 50% and 1,2-structure of less than 40% and from 1 to 20% by weight of a polymer having a mean molecular weight of from 200 to 5000, selected from homopolymers of alpha-olefins, the general formula CH2=CRR1 (where R and R1 are selected from alkyl radicals of less than 6 carbon atoms and aryl radicals of less than 7 carbon atoms and one of R and R1 can be a hydrogen atom), copolymers of said alpha-olefins and mixtures thereof. Examples of suitable polymers of alpha-olefins are polymers of propylene, n-butene-1, isobutene, 2-methyl butene-1, 2-ethyl butene-1, 3-methyl butene-1, 2-methyl pentene-1, 2 - ethyl pentene - 1, 2 - propyl pentene-1 and styrene and copolymers of propylene and n-butene-1, n-butene-1 and isobutene, and propylene and styrene. The compositions may be produced by adding to a solution of the polybutadiene rubber in a suitable inert solvent (which may be obtained by polymerizing butadiene with a lithium based catalyst in an inert solvent) a polymer of an alpha-olefin in an amount of 1 to 2% by weight relative to the total composition, mixing them uniformly, removing the solvent from the solution and drying the product. The compositions may be shaped and cured to produce shaped articles, e.g. tyre treads, carcasses, belts and hoses. Natural rubber or other synthetic rubbers may be included in the compositions used to make articles. In examples are use: polybutene-1, sulphur, N-cyclohexyl-2-benzothiazyl sulphenamide, stearic acid, zinc oxide, phenyl - b - naphthylamine, carbon black, aromatic process oil, poly-2-methyl pentene-1, copolymer of n-butene-1 and isobutene, styrene polymers, polypropylene, styrene-butadiene copolymer, dibenzothiazyl disulphide, diphenyl guanidine, 2,6-ditert-butyl hydroxytoluene and silica.