Abstract: 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 ?m or smaller is 10% by mass or less and a content of particles having a particle diameter of greater than 1,000 ?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 ?m or smaller is 10% by mass or lower and a content of particles having a particle diameter of greater than 1,000 ?m is 5% by mass or lower.

Abstract: Disclosed is a vinylpyrrolidone-based polymer composition which has improved storage stability and of which the reduction in the molecular weight (K value) under shear stress is small. The composition comprises a vinylpyrrolidone-based polymer and contains from 1 to 10000 ppm of at least one compound selected from a group consisting of biguanides and further contains from 1000 to 30000 ppm of 2-pyrrolidone and from 1 to 5000 ppm of ammonia.

Abstract: 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 ?m or smaller is 10% by mass or less and a content of particles having a particle diameter of greater than 1,000 ?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 ?m or smaller is 10% by mass or lower and a content of particles having a particle diameter of greater than 1,000 ?m is 5% by mass or lower.

Abstract: Disclosed is a vinylpyrrolidone-based polymer composition which has improved storage stability and of which the reduction in the molecular weight (K value) under shear stress is small. The composition comprises a vinylpyrrolidone-based polymer and contains from 1 to 10000 ppm of at least one compound selected from a group consisting of biguanides and further contains from 1000 to 30000 ppm of 2-pyrrolidone and from 1 to 5000 ppm of ammonia.

Abstract: The present invention provides a process for preparing vinylpyrrolidone polymer powder, which has high bulk density and favorable powder flowability and can be handled with ease. Specifically, the present invention relates to a process for preparing vinylpyrrolidone polymer powder, which comprises spraying an aqueous solution of a vinylpyrrolidone polymer into a drying tower using a disc atomizer and then drying.

Abstract: The present invention provides a process for preparing vinylpyrrolidone polymer powder, which has high bulk density and favorable powder flowability and can be handled with ease. Specifically, the present invention relates to a process for preparing vinylpyrrolidone polymer powder, which comprises spraying an aqueous solution of a vinylpyrrolidone polymer into a drying tower using a disc atomizer and then drying.

Abstract: A process for preparing a high purity vinylpyrrolidone polymer which dissolves clearly in an organic solvent can be provided. The process for preparing a high purity vinylpyrrolidone polymer, wherein vinylpyrrolidone is polymerized by using a redox initiator comprising an organic peroxide and a sulfite, and thereafter the product is contacted with an anion exchange resin to be purified.

Abstract: A vinylpyrrolidone polymer which is little colored, gives off a bad smell little, and contains extremely little impurities is provided. The polymerization is performed by adding a water-soluble organic peroxide and a sulfite to a vinylpyrrolidone aqueous solution.

Abstract: A vinylpyrrolidone polymer which is little colored, gives off a bad smell little, and contains extremely little impurities is provided. The polymerization is performed by adding a water-soluble organic peroxide and a sulfite to a vinylpyrrolidone aqueous solution.