Kuraray Co., Ltd.

Junji Funakoshi

Kazunori Watanabe

Junpei Horiguchi

Tsuyoshi Kowaka

Kazuyuki Tanaka

Hiroyuki Miyawaki

The present invention is characterized by being a polyvinyl alcohol powder having an average particle diameter of 100 to 2000 &#x3bc;m as measured by optical microscopic observation at a humidity of 65% RH and a temperature of 25&#xb0; C., having a bulk specific gravity (g/ml) of a portion ranging from 500 to 1000 &#x3bc;m in particle diameter of more than 0.60 and less than 0.80, and having a content of the portion ranging from 500 to 1000 &#x3bc;m in particle diameter of 35 to 70% by mass. Accordingly, a polyvinyl alcohol powder is provided, that is good in anti-scattering property, superior in solubility in preparing an aqueous solution from the powder, and capable of reducing transport costs due to its large specific gravity.

Polyvinyl alcohol powder and method for producing same

A method of producing polyvinyl alcohol polymer, with which a high-strength polyvinyl alcohol polymer with a high degree of saponification can be obtained, the polyvinyl ester saponification process can be linked directly with the spinning process, in which the polyvinyl alcohol polymer is made into fiber, the mole ratio of alcohol with respect to the polyvinyl alcohol can be freely selected, and the concentration of the polyvinyl alcohol obtained by the saponification reaction is high. The polyvinyl alcohol polymer that is obtained by this method exhibits a high block character value and is excellent in randomness is provided, wherein a polyvinyl ester is subject to a saponification reaction in an alcohol-containing organic solvent under the presence of a saponification catalyst and the saponification is carried out while distilling off the carboxylic acid ester that is produced by the saponification reaction.

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Tainai, Japan

Junji Funakoshi