Kuraray Co., Ltd.

Yoshihiro Tokuda

Shigeaki Suzuki

Naoki Fujiwara

Takeshi Kusudou

Jin Tokuyasu

Hisamichi Yanai

Katsushi Nagareda

Kimiko Miyata

The present invention provides polyvinyl alcohol based (PVA) whose solubility in water varies with a small temperature change to a sufficiently great degree. In manufacturing a polyvinyl alcohol based polymer by: progressing a transesterification reaction of a polyvinyl ester based polymer with alcohol in a liquid reaction mixture including the polyvinyl ester based polymer, the alcohol, and a basic compound; precipitating the polyvinyl ester based polymer, at least a part of which has been transesterified with the alcohol, out of the liquid reaction mixture; and further progressing the transesterification reaction in the liquid reaction mixture including the polyvinyl ester based polymer that has precipitated, the liquid reaction mixture has a temperature of 75&#xb0; C. to 150&#xb0; C. when the polyvinyl ester based polymer, at least a part of which has been transesterified, starts precipitating.

Polyvinyl alcohol based polymer and method of manufacturing the same

A process for producing diamines which comprises the steps of: (1) reacting a dialdehyde with ammonia and hydrogen in the presence of an alcohol and a hydrogenation catalyst to synthesize the corresponding diamine; (2) separating and recovering the alcohol by distilling the reaction mixture obtained by the step (1); (3) separating the diamine by purifying the distillation residue obtained by the step (2); and (4) feeding at least part of the alcohol recovered in the step (2) to step (1); said step (1) comprising maintaining the amount of ammonia at a level of at least 200 moles per mole of the primary amine that has formed in the step (1) and accumulated in the reaction vessel for step (1). The process can produce diamines commercially advantageously and in high yields, the diamines having little impurities.

Process for producing diamines

A process for producing diamines by reacting a dialdehyde with ammonia and hydrogen in the presence of a hydrogenation catalyst to produce the corresponding diamine, where a solvent comprising an alcohol is used in the reaction and the concentration of water in the reaction mixture is 5 to 15% by weight.

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Kurashiki, Japan

Yoshihiro Tokuda