To obtain a polymer with any regulated molecular weight by polymerizing N-vinylcarboxylic acid amide(s), and to obtain the corresponding polyvinylamine(s) with regulated molecular weight by hydrolyzing the above polymer.
In polymerizing one or more kinds of N-vinylcarboxylic acid amides or copolymerizing one or more kinds of N-vinylcarboxylic acid amides with one or more kinds of other monomers by using ≥30 wt.% of the monomers being N-vinylcarboxylic acid amide(s) the per all the monomers, polymerization is carried out in the presence of a hypophosphite salt. This polymer obtained by the above polymerization method has a reduced viscosity of ≤0.5 dl/g at a concentration of 0.1 g/dl in 2N saline solution at 25°C. The other objective polyvinylamine-base polymer is obtained by hydrolyzing the above polymer.
IZUMIKAWA HIROSHI
TAKASAKI NITSUSHIN
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