| 摘要 |
PROBLEM TO BE SOLVED: To provide a vinylpyrrolidone-based polymer having a reduced change of K value in an alkaline solution and a method for producing the same. SOLUTION: In a method for producing the vinylpyrrolidone-based polymer by polymerizing a vinylpyrrolidone monomer in a solution using a radical polymerization initiator, a solution containing the vinylpyrrolidone monomer and a sulfite is prepared and the polymerization is performed by continuously or intermittently adding an azo-based initiator having≤60°C 10-hour half-time temperature to the solution. By the method, a vinylpyrrolidone-based polymer expressing≤3% rate of change in K value after 3 months preservation at 50°C is produced. COPYRIGHT: (C)2008,JPO&INPIT
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