PROCESS FOR PRODUCING POLYMER BLENDS

1,182,866. Polymer blends. ASAHI KASEI KOGYO K.K. 14 Aug., 1968 [26 Aug., 1967], No. 38871/68. Headings C3C, C3P and C3Q. A polymer blend is produced by copolymerizing a conjugated diolefin and a monovinyl substituted aromatic compound in the presence of a lithium based catalyst in the presence of a conjugated diolefin homopolymer or a random copolymer of a conjugated diolefin and a monovinyl substituted aromatic compound containing not more than 40% by weight of the monovinyl substituted aromatic compound in an inert medium and under an inert atmosphere to produce a polymer blend comprising 25-95 parts by weight of a conjugated diolefin homopolymer or a random copolymer of a conjugated diolefin and a monovinyl substituted aromatic compound containing not more than 40% by weight of the aromatic hydrocarbon, and 75-5 parts by weight of a random copolymer of a conjugated diolefin and a monovinyl substituted aromatic compound having a content of the monovinyl substituted aromatic compound of 50-95% by weight. The inert medium may be an aliphatic hydrocarbon and the inert atmosphere may be argon or nitrogen. The copolymerization may be carried out at 0‹ C. to 150‹ C. for 5 minutes to 24 hours. A preferred composition comprises 100 parts of the polymer blend, 10-400 parts of filler and 2-100 parts of a process oil. In the examples (1) 1,3-butadiene is polymerized and to this homopolymer is added a mixture of 1, 3 butadiene, styrene and n- or sec-butyl lithium and potassium oleate (as a random copolymerization agent); (2) as (1) except initially isoprene is homopolymerized; (3) styrene and 1,3 butadiene are copolymerized and to this copolymer is added a mixture of 1,3 butadiene, styrene, nbutyl lithium and tetrahydrofuran (as a random copolymerization agent). An antioxidant was added to the resultant polymer blend, from which the solvent was then removed. The blends may be mixed with process oils, natural rubber, and fillers such as calcium carbonate, carbon black, clay, and silicic acid, and the resultant mixtures vulcanized. In (1) above, a blowing agent is also mixed with the blend prior to vulcanization, to form a sponge foam.