Denki Kagaku Kogyo Kabushiki Kaisha

Takashi Kadowaki

Shoji Kimura

Kanehisa Hanabusa

Michio Dohi

Ichiro Fukuoka

Yasuaki Denda

Chojiro Kitagawa

Koichi Abe

Takehiko Nishimura

Seiichi Watanabe

Hideki Matsumura

Takao Iwasaki

Michio Nishimura

A process is disclosed for preparing a polycloroprene elastomer consisting of a blend of from 20 to 80 parts by weight of (a) a toluene-insoluble gel polymer and from 80 to 20 parts by weight of (b) a toluene-soluble sol polymer, the process comprising preparing the toluene-insoluble gel polymer by polymerizing chloroprene or a mixture of chloroprene with a small amount of at least one copolymerizable monomer in the presence of a suitable cross-linking agent, preparing the toluene-soluble sol polymer by polymerizing chloroprene or a mixture of chloroprene with a small amount of at least one copolymerizable monomer and blending the gel and sol polymers wherein an improved elastomer is obtained by polymerizing the toluene-insoluble gel polymer to a cross-linking density of at least 2.4 .times. 10.sup.-6 to a monomer conversation of at least 80%.

Polychloroprene elastomer

Chloroprene having a little content of acetaldehyde is produced by dehydrochlorination of 3,4-dichlorobutene-1 in the presence of an aqueous solution of an alkali metal hydroxide by treating with an ammonium ion donor during or after the dehydrochlorination or in both the steps.

Process for producing chloroprene monomer having a little content of

Chloroprene or a mixture of chloroprene and a comonomer is polymerized by emulsion polymerization in the presence of an alkali metal or ammonium salt of an aliphatic substituted benzoic acid or a non-ionic polyoxyethylene ether or ester surfactant. The resulting chloroprene polymer is admixed with a solvent, a metal oxide and a thermosettable resin, e.g., an alkylphenol-formaldehyde resin to yield a non-phasing adhesive composition.

Non-phasing chloroprene polymer adhesive composition and preparation

In production of chloroprene by dehydrochlorinating 3,4-dichlorobutene-1 in the presence of an aqueous solution of alkali, the mixture of 3,4-dichlorobutene-1 and the aqueous solution of alkali is heated at 85.degree. to 100.degree. C to evaporate a mixture consisting mainly of the resulting chloroprene, unreacted 3,4-dichlorobutene-1 and water rapidly, the evaporated mixture is taken out from the reaction system without subjecting to a distillation and totally condensed, the condensed reaction mixture is separated into an aqueous phase and an organic phase and then the organic phase is fractionally distilled to separate chloroprene from 3,4-dichlorobutene-1. Prior to subjecting the organic phase to the fractional distillation, if the organic phase is previously subjected to a drying means and the water content in the organic phase is reduced to a proper degree, it is possible to avoid formation of polymer of the resulting chloroprene and corrosion of the distillation column.

Method of producing chloroprene

A toluene-insoluble gel polymer having a crosslinking density of at least 2.4 .times. 10.sup.-.sup.6 obtained by polymerizing chloroprene or a mixture of chloroprene with a small amount of at least one copolymerizable monomer to a monomer conversion of at least 80 percent in the presence of a crosslinking agent selected from the group consisting of a compound represented by the following formula: ##EQU1## wherein n is integer of from 1 to 8, ##EQU2## wherein n is integer of from 2 to 4, divinylbenzene and diallyl phthalate and a process for the preparation thereof.

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Niigata, Japan

Takashi Kadowaki