Process for producing transparent block copolymer resins
AssigneeSumitomo Chemical Company, Limited
InventorsTamotsu Miki, Shizuo Narisawa, Ichiro Ichikawa, Hideki Horiike
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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.
Claims25
A process for producing a transparent block copolymer resin which comprises subjecting 90 to 65 parts by weight of a vinyl aromatic compound monomer and 10 to 35 parts by weight of a conjugated diene monomer to 3-stage block copolymerization in an inert hydrocarbon solvent using an organo-monolithium compound as an initiator, characterized in that at the first stage of polymerization, a mixture of S.sub.1 parts by weight of the vinyl aromatic compound monomer and B.sub.1 parts by weight of the conjugated diene monomer is added and substantially all of the monomer mixture is polymerized;
- at the second stage of polymerization, S.sub.2 parts by weight of the vinyl aromatic compound monomer is added and the polymerization is continued to polymerize substantially all of the monomers;
- and at the third stage of polymerization, a mixture of S.sub.3 parts by weight of the vinyl aromatic compound monomer and B.sub.3 parts by weight of the conjugted diene monomer is added and the polymerization is continued to polymerize substantially all of the monomers, wherein the feed weight ratios of the individual monomers are controlled to values within the ranges of:
- S.sub.1 + S.sub.2 + S.sub.3 = 90 to 65 (parts by weight)
- B.sub.1 + B.sub.3 = 10 to 35 (parts by weight)
- S.sub.1 /B.sub.1 = 0.2 to 3.0
- S.sub.3 /B.sub.3 = 0.2 to 3.0
- S.sub.2 /(S.sub.1 + S.sub.2 + S.sub.3) = 0.35 to 0.90
- and the polymerization is effected in the presence of 0.01 to 5 mole % of a Lewis base compound based on the total monomer, to produce a block copolymer resin having an average molecular weight in the range from 0.5 to 1.8 dl/g in terms of intrinsic viscosity as measured in toluene at 30.degree. C.
A process for producing a transparent block copolymer resin which comprises subjecting 90 to 65 parts by weight of a vinyl aromatic compound monomer and 10 to 35 parts by weight of a conjugated diene monomer to 2-stage block copolymerization in an inert hydrocarbon solvent using an organo-dilithium compound as an initiator, characterized in that at the first stage of polymerization, S.sub.1 parts by weight of the vinyl aromatic compound monomer is added and substantially all of the monomer is polymerized, and then, at the second stage of polymerization, a mixture of S.sub.2 parts by weight of the vinyl aromatic compound monomer and B parts by weight of the conjugated diene monomer is added and the polymerization is continued to polymerize substantially all of the monomers, wherein the feed weight ratios of the individual monomers are controlled to values within the ranges of:
- S.sub.1 + S.sub.2 = 90 to 65 (parts by weight)
- B = 10 to 35 (parts by weight)
- S.sub.1 /(S.sub.1 + S.sub.2) = 0.35 to 0.90
- S.sub.2 /B = 0.2 to 3.0
- and the polymerization is effected in the presence of 0.01 to 5 mole % of a Lewis base compound based on the total monomer, to produce a block copolymer having an average molecular weight in the range from 0.5 to 1.8 dl/g in terms of intrinsic viscosity as measured in toluene at 30.degree. C.
Dependencies are inferred from the claim text.