Granted Patent B2

US 8,822,586 · App. 11/813,136 · Granted Sep 2, 2014

Abstract

Claims (15)

1. A method of producing a cationic water-in-water polymer dispersion comprising the step of free-radically polymerizing one or more monomers in an aqueous dispersion of a polymeric cationic dispersant B to form a cationic polymer A wherein the monomers comprise

(a) from 1 to 60 wt. % based on the weight of the cationic polymer A of cationized N-alkyl- or N,N-dialkylaminoalkyl (meth)acrylates and/or cationized N-alkyl- or N,N-dialkylaminoalkyl(meth)acrylamides, and

(b) from 40 to 99 wt. % by based on the weight of the cationic polymer A of nonionic monomers,

and

the cationic polymeric dispersant B has an average molecular weight M w of from 75,000 to 350,000 g/mol and is prepared from

(c) from 30 to 100 wt. % based on the weight of the cationic polymeric dispersant B of cationized N-alkyl- or N,N-dialkylaminoalkyl(meth)acrylamides and/or cationized N-alkyl- or N,N-dialkyl(meth)acrylamides, and

(d) from 0 to 70 wt. % by based on the weight of the cationic polymeric dispersant B of nonionic monomers, and

wherein the free radical polymerization occurs in the presence of redox free radical initiators consisting of sodium peroxydisulfate, sodium disulfite and tert.-butylhydroperoxide.

2. The method according to claim 1 , characterized in that the polymeric dispersant B is used in the form of an aqueous solution comprising 20 to 80 wt. % polymeric dispersant B based on the weight of the aqueous solution.

3. The method according to claim 2 , characterized in that the monomers to be polymerized by free radical polymerization to form the cationic polymer A are present in an amount of 5 to 60 wt. % based on the total weight of the monomers and the aqueous solution.

4. The method according to claim 3 , characterized in that only a proportion of the monomers to be polymerized is initially introduced, the reminder being added as metered portions or as a continuous feed during the course of the free-radical polymerization.

5. The method according to claim 3 , characterized in that only a proportion of the monomers to be polymerized and of the aqueous solution are initially introduced, the remainder being added as metered portions or as a continuous feed during the course of the free-radical polymerization.

6. The method according to claim 3 , characterized in that the free-radical polymerization is performed at temperatures of between 30° and 90° C.

7. The method according to claim 6 , characterized in that the initiators for free-radical polymerization are added continuously during the entire course of the polymerization.

8. The method according to claim 7 , characterized in that acid is added before, during or after the free-radical polymerization.

Assignments (26)