Anti-fouling agent and method for producing the same

摘要

Disclosed is an anti-fouling agent which is superior in viscosity stability, water resistance of its film and ability of preventing a scale from depositing on the inner wall of a polymerization reactor and which can prevent the contamination of foreign substances into a polymeric product caused by exfoliation of a scale depositing on the inner wall of a polymerization reactor and exfoliation of the anti-fouling agent itself, the anti-fouling agent comprising an aqueous solution containing a polyvinyl alcohol that is obtained through saponification of a polyvinyl ester that contains monomer units having a specific silyl group and that satisfies the following formulae (I) and (II): 370 < P x S < 9000 wherein P indicates the viscosity-average degree of polymerization of the polyvinyl alcohol, and S indicates the content (mole%) of the monomer units having a silyl group of formula (1) in the polyvinyl alcohol; 0.2/100≤(A-B)/(B)≤75/100 wherein A indicates the content (ppm) of silicon atoms in the polyvinyl alcohol, and B indicates the content (ppm) of silicon atoms in the polyvinyl alcohol that was washed with sodium hydroxide-containing methanol and then washed with methanol by Soxhlet extraction.