Method for producing vinyl amine unit-containing polymer solution
Provided is a method for efficiently producing on an industrial scale a high-performance polyvinylamine solution having good handling properties. After producing a polymer containing N-vinylcarboxamide monomer units having a value of the weight average molecular weight (Mw)/number average molecular weight (Mn) of 5 or higher by aqueous solution standing adiabatic polymerization, the polymer is hydrolyzed in an aqueous solvent in the presence of an alkali and an antigelling agent. In a preferred embodiment of the present invention, a polymer powder having a volatile content of 0.1-12% by mass is obtained by drying and pulverizing after producing a (co)polymer, and the powder obtained is stored or transported to the site of use of the polymer solution and hydrolyzed in an aqueous solvent in the presence of an alkali and an antigelling agent when the polymer solution is needed or at the site of use of the polymer solution.
1. A method for producing a vinyl amine unit-comprising polymer solution comprising: producing a polymer comprising N-vinylcarboxamide monomer units and having a value of weight average molecular weight Mw/number average molecular weight Mn of at least 5 by an aqueous solution standing adiabatic polymerization method, and then performing hydrolysis on the polymer in an aqueous solvent under the presence of alkali and an antigelling agent.
2. The method according to claim 1 , wherein the N-vinylcarboxamide monomer units in the polymer are at least 50 mol % of all monomer units in the polymer.
3. The method according to claim 1 , wherein the N-vinylcarboxamide monomer units are N-vinylformamide monomer units.
4. The method according to claim 1 , wherein the antigelling agent is at least one selected from the group consisting of dithionite, sulfite, hydrogensulfite, disulfite, sulfoxylate formaldehyde adduct, thioureadioxide and sodium borohydride.
5. The method according to claim 1 , wherein reduced viscosity of 0.1 g/dl of the polymer in a 1N brine is 2 to 9.
6. The method according to claim 1 , wherein polymer concentration in the aqueous solvent upon performing hydrolysis is at least 3% by mass.
7. The method according to claim 1 , wherein polymer concentration in the aqueous solvent is at least 3% by mass.
8. A method for producing the polymer solution according to claim 1 , wherein the polymer comprising N-vinylcarboxamide monomer units after being produced by aqueous solution standing adiabatic polymerization, is then dried and powderized to obtain polymer powder having 0.1 to 12% by mass of volatile components, followed by performing hydrolysis on the powder obtained in said aqueous solvent under the presence of said alkali and said antigelling agent.
9. The method for producing a polymer solution according to claim 8 , comprising transporting the polymer powder obtained to a location of use of the polymer solution, and performing hydrolysis on the polymer powder in an aqueous solvent under the presence of alkali and an antigelling agent at the location of use.
10. The method according to claim 1 , wherein the polymer comprising N-vinylcarboxamide monomer units is a mixture of at least two N-vinylcarboxamide polymers having different reduced viscosities.
11. A retention and drainage aid for papermaking comprising the vinylamine unit-containing polymer solution according to claim 1 .