PURPOSE: To obtain an additive for papermaking excellent in drainage effect and paper strength effect by subjecting a (meth)acrylic amide-based aqueous high polymer compound to Hofmann degradation reaction with sodium hypochlorite under alkaline conditions and partially lactamizing the resultant primary amino group.
CONSTITUTION: An aqueous high polymer compound prepared by copolymerizing acrylic amide and/or methacrylic amide with N-vinyl-2-pyrrolidone, etc., is subjected to Hofmann degradation reaction with sodium hypochlorite of 5-50mol% based on this high polymer compound under alkaline conditions at pH ≥11 and after the Hofmann degradation reaction is finished, the reaction is further continued and 3-40mol% of the resultant primary amino group is modified with a lactam structural unit to provide the objective additive for papermaking consisting essentially of 3-50mol% structural unit expressed by formula II and/or formula III (X is inorganic or organic anion) and 1-40mol% structural unit expressed by formula IV and/or formula I and having high drainage effect and paper strength effect.
MINODA SHIGEJI
MATSUBARA TSUGIO
TOKI HIROTOSHI
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