Nippon Shokubai Co., Ltd.

Dai-ichi Kogyo Seiyaku Co., Ltd.

Keiji Watanabe

Kazuhiro Okamura

Norihiro Wakao

Keiichi Fujise

The present invention is a powder of a vinylpyrrolidone polymer having a K value of smaller than 50, characterized in that a content of particles having a particle diameter of 106 &#x3bc;m or smaller is 10% by mass or less and a content of particles having a particle diameter of greater than 1,000 &#x3bc;m is 5% by mass or lower. A process for production of a powder of a vinylpyrrolidone polymer according to the present invention is characterized in that a vinylpyrrolidone polymer having a K value of smaller than 50 is formed into a solution having a concentration from 30% to 70% by mass, and the solution is dried by using a hot surface adhesion-type dryer, followed by pulverization so that a content of particles having a particle diameter of 106 &#x3bc;m or smaller is 10% by mass or lower and a content of particles having a particle diameter of greater than 1,000 &#x3bc;m is 5% by mass or lower. Thus, there is provided a powder of a vinylpyrrolidone polymer, which has excellent solubility in spite of having a low K value determined by a Fikentscher method and can be made into solution with favorable handleability without dust rising, and a process for production of the same.

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Jyoetsu, Japan

Keiji Watanabe