Abstract: By block-copolymerizing a mixture of an aromatic vinyl compound and a conjugated diene in two stages in an aliphatic hydrocarbon solvent, using an organomonolithium compound or an organodilithium compound as a polymerization initiator, a block copolymer is formed as a suspension polymer in a slurry state.The resulting block copolymer is very clear and excellent in mechanical properties, especially, strength, elongation and impact strength. It has a wide application in the field of general resins.

Abstract: By block-copolymerizing a vinyl aromatic compound and a conjugated diene in a hydrocarbon solvent with an organolithium compound as initiator, there is obtained a block copolymer which comprises in the molecule three blocks of homopolymerized vinyl aromatic compound, randomly copolymerized vinyl aromatic compound and conjugated diene, and homopolymerized diene, respectively. The resulting block copolymer is transparent and excellent in mechanical properties, and is suitable for use in the manufacture of sheeting, film, and various molded articles.

Abstract: In block-copolymerizing a vinyl aromatic compound and a conjugated diene in a hydrocarbon solvent using an organolithium compound as initiator, a transparent block copolymer resin characterized by having elastomeric random copolymer blocks may be produced by continuously adding a mixture of the vinyl aromatic compound and the conjugated diene. The block copolymer resin thus obtained is transparent, excellent in mechanical characteristics and may be used in the fields of sheetings, films, and various molded articles.

Abstract: A block copolymer resin having at one or both ends a copolymer block of a vinyl aromatic compound and a conjugated diene is obtained by subjecting a vinyl aromatic compound and a conjugated diene to 2- or 3-stage block copolymerization in a hydrocarbon solvent in the presence of a definite amount of a Lewis base compound using an organolithium compound as an initiator. The block copolymer resin is high in transparency and excellent in mechanical properties, and is successfully usable in the fields of sheets, films and various molded articles.

Abstract: A binary or ternary graft-copolymer excellent in both tensile strength and impact resistance is obtained by the process for producing a binary or ternary graft-copolymer consisting essentially of an ethylene-propylene rubber and an aromatic vinyl compound or of an ethylene-propylene rubber, an aromatic vinyl compound, and a vinyl cyanide compound, characterized by subjecting these materials to solution polymerization in a mixed solvent comprising an aliphatic hydrocarbon solvent capable of dissolving the ethylene-propylene rubber and a polar solvent capable of dissolving a poly-(aromatic vinyl compound) or a copolymer of the aromatic vinyl compound and the vinyl cyanide compound.