Modification of water-soluble acrylic polymer

Claim 2

A process for the modification of a water-soluble high polymer, which comprises: dispersing at least one water-soluble high polymer selected from the group consisting of polyacrylamide, polymethacrylamide, copolymers composed mainly of acrylamide, and copolymers composed mainly of methacrylamide in an aqueous solution of a water-soluble salt, said salt selected from the group consisting of alkali metal and magnesium salts of dibasic and more basic inorganic acids, wherein the concentration of said salt in said aqueous solution is sufficient to prevent the elution of said polymer from said solution and is not less than 15 wt. % based on the amount of salt in water; and contacting said water-soluble high polymer dispersed in the aqueous solution with a modifier to modify said high polymer.

Claim 3

The process of claim 1 wherein said alkali metal or magnesium salt of the dibasic or more basic inorganic acid is selected from the group consisting of sodium carbonate, potassium carbonate, sodium phosphate, potassium phosphate, sodium hydrogenphosphate, potassium hydrogenphosphate, sodium sulfate, potassium sulfate and magnesium sulfate.

Claim 4

The process of claim 1, wherein said water-soluble high polymer is modified by hydrolysis, methylolation, sulfomethylation, the Hofmann degradation reaction, or the Mannich reaction of carbamoyl groups and conversion of tertiary to quaternary amino groups.

Claim 5

The process of claim 1, wherein said water-soluble high polymer is contacted with an alkaline reagent in an aqueous solution of said salt selected from the group consisting of carbonates, phosphates, and hydrogenphosphates of sodium and potassium to hydrolyze the carbamoyl groups of said high polymer.

Claim 6

The process of claim 1, wherein said water-soluble high polymer is contacted with a dialkyl sulfate in an aqueous solution of said salt selected from the group consisting of sulfates of sodium, potassium and magnesium to alkylate the tertiary amino groups of said high polymer.

Claim 7

The process of claim 1, wherein said water-soluble high polymer is a copolymer composed mainly of acrylamide or methacrylamide having a molecular weight of more than 200,000, in which the content of acrylamide or methacrylamide units is more than 15 mole percent and that of the units possessing ionic groups is less than 15 mole percent in the copolymer.

Claim 8

A process for the modification of a watersoluble high polymer, which comprises: dispersing at least one water-soluble high polymer selected from the group consisting of polyacrylamide, polymethacrylamide, copolymers composed mainly of acrylamide, and copolymers composed mainly of methacrylamide in an aqueous solution of a water-soluble salt, said salt selected from the group consisting of alkali metal and magnesium sulfates, wherein the concentration of said salt in said aqueous solution is sufficient to prevent the elution of said polymer from said solution and is not less than 15 wt. % based on the amount of salt in water; and contacting said water-soluble high polymer dispersed in the aqueous solution with formaldehyde and a primary or secondary amine to aminoalkylate the carbamoyl groups of said high polymer.

Claim 9

A process for the modification of a watersoluble high polymer, which comprises: dispersing at least one water-soluble high polymer selected from the group consisting of polyacrylamide, polymethacrylamide, copolymers composed mainly of acrylamide, and copolymers composed mainly of methacrylamide in an aqueous solution of a water-soluble salt, said salt selected from the group consisting of alkali metal and magnesium sulfates, wherein the concentration of said salt in said aqueous solution is sufficient to prevent the elution of said polymer from said solution and is not less than 15 wt. % based on the amount of salt in water; and contacting said water-soluble high polymer dispersed in the aqueous solution with formaldehyde and a primary or secondary amine to aminoalkylate the carbamoyl groups of said high polymer.

Claim 10

The process of claim 7 wherein said water-soluble high polymer is a copolymer composed mainly of acrylamide or methacrylamide having a molecular weight of more than 200,000, in which the content of acrylamide or methacrylamide units is more than 50 mole % and that of the units possessing ionic groups is less than 15 mole % in the copolymer.

Claim 11

The process of claim 7 wherein said sulfate is sodium, potassium or magnesium sulfate.

Claim 12

The process of claim 7 wherein said polymer is polyacrylamide.

Claim 13

The process of claim 7 wherein said salt is sodium sulfate.

Claim 14

The process of claim 7 wherein said salt is magnesium sulfate.