| 摘要 |
Plastic rubber compositions are prepared by mixing a synthetic polymer, which is compatible with hydrocarbon mineral oils, of a conjugated diolefin having not in excess of eight carbon atoms with at least 20 per cent, based on the weight of the polymer, of a compatible plasticizer, the polymer containing at least 50 per cent diolefin and having a raw "computed Mooney" plasticity of at least 85. Specified polymers are those of butadiene, isoprene and dimethylbutadiene and their copolymers with alpha- or p-acetyl-alpha-methylstyrene, styrene, 3 : 4-dimethyl styrene, methylisopropenyl ketone, methyl vinyl ketone, methyl methacrylate, methyl acrylate and the amides of acrylic and methacrylic acids. Specified plasticizers are mineral oils, tar oils, substituted phenols such as those of cashew-nut shell oil and, less preferably, dibutyl or dioctyl phthalate, and tricresyl phosphate. The plasticizer may be added as a disperse phase to a latex of the polymerization product, or may be incorporated therein, after coagulating, on a Banbury or similar mixer, or may be added as the polymerization product is formed from its monomers in the presence of a catalyst, e.g. an Alfin catalyst. Carbon black may also be present, preferably in amounts of 30-35 parts per 100 of plasticizer and polymer, while an aqueous dispersion of polymer may be mixed with a liquid plasticizer and an aqueous carbon black slurry, coagulated and free liquid removed. The polymerization may take place at below room temperature, e.g. below 50 DEG F. The usual vulcanization ingredients as well as natural rubber may be present in the composition which may be vulcanized. The preferred Mooney value is 90, and even more preferred, at least 120. U.S.A. Specification 2,457,097 is referred to.
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