Denki Kagaku Kogyo Kabushiki Kaisha

Kenki Kagaku Kogyo Kasushiki Kaisha

Shin-Ichiro Asai

Shigeki Horiie

Yoshihisa Moriya

Minoru Handa

Kazuhiro Shirakawa

Takashi Torikoshi

A stable and non-polar solvent soluble alpha-methylstyrene-conjugated diene oligomer dilithium as a polymerization initiator is obtained by preparing a dilithium initiator solution by reacting lithium metal with alpha-methylstyrene in a polar solvent at low temperature, thereafter adding gradually a small amount of a conjugated diene to the dilithium initiator solution to consume completely the alpha-methylstyrene, and then adding additional conjugated diene in a certain amount so as to prepare the stable and non-polar solvent soluble alpha-methylstyrene-conjugated diene oligomer dilithium.

Organolithium polymerization initiators and their preparations

First polymerization of a mixture of styrene-type monomers and conjugated diene monomers containing 30 to 70% by weight of styrene-type monomers is carried out, and when 40 or more of the diene monomers have been converted to a copolymer, there are then added styrene-type monomers in such an amount that the content of styrene units accounts for a proportion of 70 to 85% by weight of the finally obtained block copolymers, followed by completion of the polymerization. Alternatively, when all the diene monomers added have been converted to the copolymer, the second polymerization of styrene type monomers is carried out in the presence of a small amount of conjugated dienes as a polymerization retardant. Block copolymers obtained thus are useful for sheet or film molding having good low-temperature impact strength.

Block copolymers for a sheet or film

Growing community of inventors

Tokyo, Japan

Shin-Ichiro Asai