A method for producing an aqueous copolymer solution, which comprises dissolving a copolymer of (meth)acrylamide and at least 1 mol-% cationic monomers, calculated from total amount of monomers in the dissolving water having calcium hardness of at least mg/l, expressed as Ca.sup.2+, and adding acid comprising monoprotic organic acid and/or mineral acid to the dissolving water and/or the aqueous solution of the copolymer in an amount sufficient to provide the aqueous solution of the copolymer with a pH of equal to or less than 4.5. The invention also relates to uses of the obtained polymer solutions in manufacturing of paper, board or the like or in treatment of sludge or water.

A method for producing an aqueous copolymer solution, which comprises dissolving a copolymer of (meth)acrylamide and at least 1 mol-% cationic monomers, calculated from total amount of monomers in the dissolving water having calcium hardness of at least mg/l, expressed as Ca.sup.2+, and adding acid comprising monoprotic organic acid and/or mineral acid to the dissolving water and/or the aqueous solution of the copolymer in an amount sufficient to provide the aqueous solution of the copolymer with a pH of equal to or less than 4.5. The invention also relates to uses of the obtained polymer solutions in manufacturing of paper, board or the like or in treatment of sludge or water.

Provided are: a sludge dehydrating agent which can exert a steady dehydrating effect on various types of sludge and has excellent dehydration performance; and a sludge dehydration method using the sludge dehydrating agent. The sludge dehydrating agent of the present invention with a polymer which has a constituent unit derived from a cationic monomer, wherein a value k determined from an intrinsic viscosity [η] 1 [dL/g] of a 1-mol/L aqueous sodium nitrate solution of the polymer at 30° C. and an intrinsic viscosity [η] 0.01 [dL/g] of a 0.01-mol/L aqueous sodium nitrate solution of the polymer at 30° C. in accordance with formula (I) is 0.8 to 2.2 exclusive.

k=([η]0.01−[η]1)/9   (I)

Provided are: a sludge dehydrating agent which can exert a steady dehydrating effect on various types of sludge and has excellent dehydration performance; and a sludge dehydration method using the sludge dehydrating agent. The sludge dehydrating agent of the present invention with a polymer which has a constituent unit derived from a cationic monomer, wherein a value k determined from an intrinsic viscosity [η] 1 [dL/g] of a 1-mol/L aqueous sodium nitrate solution of the polymer at 30° C. and an intrinsic viscosity [η] 0.01 [dL/g] of a 0.01-mol/L aqueous sodium nitrate solution of the polymer at 30° C. in accordance with formula (I) is 0.8 to 2.2 exclusive.

k=([η]0.01−[η]1)/9   (I)

A method is provided for generating aldehyde-functionalized polymers such as GPAM, wherein progress of the aldehyde-functionalized polymer formation is monitored by measuring viscosity using an online viscometer. A method is also provided for enhancing paper strength, said method comprising generating an aldehyde-functionalized polymer, such as GPAM, according to the present disclosure, and combining said aldehyde-functionalized polymer with a fiber slurry or applying it to a paper sheet.

A method is provided for generating aldehyde-functionalized polymers such as GPAM, wherein progress of the aldehyde-functionalized polymer formation is monitored by measuring viscosity using an online viscometer. A method is also provided for enhancing paper strength, said method comprising generating an aldehyde-functionalized polymer, such as GPAM, according to the present disclosure, and combining said aldehyde-functionalized polymer with a fiber slurry or applying it to a paper sheet.

This invention relates to an additive based on (co)polymers resulting from the reaction between at least one dialdehyde compound and at least one complex (co)polymer obtained by polymerization of water-soluble monomers in the presence of at least one host (co)polymer comprising vinylamine functions.

This invention relates to an additive based on (co)polymers resulting from the reaction between at least one dialdehyde compound and at least one complex (co)polymer obtained by polymerization of water-soluble monomers in the presence of at least one host (co)polymer comprising vinylamine functions.

What are described are copolymers containing cationic structural units and macromonomeric structural units. The copolymers are, for example, advantageously suitable for use in detergent compositions and lead to advantageous shine results, for example, after application on hard surfaces.

A polyacrylamide resin has at least one kind of a first unit represented by the following formulas (1) to (4) and a second unit represented by the following formula (5).

##STR00001##

(In the above-described formulas (1) to (4), R1 represents a hydrogen atom, a methyl group, an ethyl group, or a benzyl group; R2 and R3 are independent and represent a hydrogen atom, a methyl group, an ethyl group, or a benzyl group; and X represents an anion.)

##STR00002##

(In the above-described formula (5), R4 represents a hydrogen atom or a methyl group and R5 represents a hydrogen atom, an alkali metal ion, or an ammonium ion.)