Polymer dispersion and process for preparing a polymer dispersion

A polymer dispersion comprising:

• a) a dispersed polymer consisting of monomer units originating from one or more monomers (m), and,
• b) a polymeric stabilizer (C) which is a graft copolymer resulting from reaction of:
• i) a polymer (B) of a monomer mixture comprising monomers selected from the group consisting of one monomer (x) having a primary, secondary or tertiary amine or amide group and at least one olefinic unsaturation, and, a cationic monomer (y) being a diallyldimethylammoniumchloride (DADMAC), and,
• ii) said one or more monomers (m), polymer (B) constituting the backbone of the polymeric stabiliser (C) and monomers (m) the grafted branches;
• and,
• c) a polymeric cationic co-stabiliser (A) being a poly-DADMAC homopolymer, wherein the monomers, (m), consist of a non-ionic monomer, (m1), and a cationic monomer, (m2), wherein the non-ionic monomer, (m1), is N-t-butylacrylamide, N-t-butylmethacrylamide or a monomer of the general formula (I):
• wherein R1 is hydrogen or methyl, and R2 and R3 are, independently from each other, any of hydrogen, C1-C2 alkyl, isopropyl, methylol, hydroxyethyl, or hydroxypropyl;
• wherein the cationic monomer, (m2), is a monomer of the general formula (II):
• wherein R4 is hydrogen or methyl, R5, R6 and R7 are, independently from each other, any of hydrogen, C1-C8 alkyl or benzyl, D is oxygen or NH, E is C2-C4 alkyl or C2-C4 hydroxyalkyl, X− is an anionic counterion;
• wherein the amine or amide monomer (x) is selected from the group consisting of diallylamine, diallylpropanolamine, N-vinylformamide, N-methyl-N-vinylformamide, and N-methyl-N-vinylacetamide.

A Process for preparing a polymer dispersion comprising reacting, in the presence of a polymeric cationic co-stabiliser (A), one or more-monomers (m), and a polymer (B) of a monomer mixture comprising monomers selected from the group consisting of one monomer (x) having a primary, secondary or tertiary amine or amide group and at least one olefinic unsaturation, and, one cationic monomer (y) having at least one olefinic unsaturation, if a monomer having an amide group is used, the polymer has been hydrolysed to convert the amide functionality into an amine functionality;

• wherein the reacting step occurs under conditions that result in the formation of a polymeric stabilizer (C), which is a graft copolymer;
• wherein polymer (B) constitutes the backbone of the polymeric stabiliser (C) and monomers (m) the grafted branches,
• wherein the polymeric cationic co-stabiliser (A) is a homo- or co-polymer consisting of monomers m2 of general formula (II),
• wherein the monomers, (m), consist of a non-ionic monomer, (m1), and a cationic monomer, (m2),
• wherein the non-ionic monomer, (m1), is N-t-butylacrylamide N-t-butylmethacrylamide or a monomer of the general formula (I):
• wherein R1 is hydrogen or methyl, and R2 and R3 are, independently from each other, any of hydrogen, C1-C2 alkyl, isopropyl, methylol, hydroxyethyl, or hydroxypropyl;
• wherein the cationic monomer, (m2), is a monomer of the general formula (II):
• wherein R4 is hydrogen or methyl, R5, R6 and R7 are, independently from each other, any of hydrogen, C1-C8 alkyl or benzyl, D is oxygen or NH, E is C2-C4 alkyl or C2-C4 hydroxyalkyl, X− is an anionic counterion;
• and
• wherein the amine or amide monomer (x) selected from the group consisting of diallylamine, methdiallylamine, diallylpropanolamine, N-vinylformamide, N-methyl-N-vinylformamide, and N-methyl-N-vinylacetamide.