Low-solvent polyacrylate copolymer dispersions
The present invention relates to an aqueous secondary copolymer dispersion comprising a copolymer (P) synthesized from a mixture of free-radically polymerizable monomers (M) comprising (M1) cycloaliphatic esters of acrylic and/or methylacrylic acid; (M2) vinyl esters of aliphatic carboxylic acids; (M3) hydroxy-functional, free-radically polymerizable monomers; (M4) carboxyl-functional, free-radically polymerizable monomers and (M5) hydroxyl- and carboxyl-free (meth)acrylic esters having C1 to C12 hydrocarbon radicals in the alcohol moiety and/or vinylaromatics. The mixture further comprises glycidyl esters of aliphatic carboxylic acids. The invention also relates to a method for the production of such a dispersion, to the use of the dispersion as a coating and as a binder in 2K polyurethane coatings.
1. An aqueous secondary copolymer dispersion comprising a copolymer (P) synthesized from a mixture of free-radically polymerizable monomers (M) comprising:
(M1) ≧0.1 weight-% to ≦3 weight-% of a cycloaliphatic ester of acrylic and/or methylacrylic acid,
(M2) ≧0.1 weight-% to ≦3 weight-% of a vinyl ester of aliphatic carboxylic acid,
(M3) ≧10 weight-% to ≦30 weight-%, of a hydroxy-functional, free-radically polymerizable monomer,
(M4) ≧1 weight-% to ≦10 weight-% of a carboxyl-functional, free-radically polymerizable monomer, and
(M5) ≧40 weight-% to ≦80 weight-% of a hydroxyl- and carboxyl-free (meth)acrylic ester having C1 to C12 hydrocarbon radicals in the alcohol moiety and/or vinyl aromatic monomer,
wherein the mixture further comprises a glycidyl ester of an aliphatic carboxylic acid in an amount of ≧5 weight-% to ≦20 weight-%,
based on the total weight of the solids in the dispersion, the amounts given adding up to ≦100 weight-%.
2. The dispersion according to claim 1 , wherein the content of solids in the dispersion is in a range of ≧10 weight-% to ≦90 weight-%, based on the total weight of the dispersion and wherein organic solvents are present in an amount of ≦5 weight-%, based on the total weight of the dispersion.
3. The dispersion according to claim 1 , wherein in the glycidyl ester of aliphatic carboxylic acid the carboxylic acid comprises 8, 9 and/or 10 carbon atoms.
4. The dispersion according to claim 1 , wherein:
(M1) is isobornyl (meth)acrylate,
(M2) is represented by the formula H 2 C═CH—O—C(═O)—C(R1)(R2)(CH 3 ) in which R1 and R2 represent saturated alkyl groups with a total of 6, 7 or 8 carbon atoms,
(M3) is hydroxyethyl (meth)acrylate and/or hydroxypropyl (meth)acrylate,
(M4) is (meth)acrylic acid, and
(M5) is styrene, methyl (meth)acrylate and/or n-butyl (meth)acrylate.
5. A method for producing a dispersion according to claim 1 , comprising the step of free-radically polymerizing a mixture of monomers (M) comprising:
(M1) ≧0.1 weight-% to ≦3 weight-% of a cycloaliphatic ester of acrylic and/or methylacrylic acid,
(M2) ≧0.1 weight-% to ≦3 weight-% of a vinyl esters of aliphatic carboxylic acid,
(M3) ≧10 weight-% to ≦30 weight-%, of a hydroxy-functional, free-radically polymerizable monomer,
(M4) ≧1 weight-% to ≦10 weight-% of a carboxyl-functional, free-radically polymerizable monomer,
(M5) ≧40 weight-% to ≦80 weight-% of a hydroxyl- and carboxyl-free (meth)acrylic ester having C1 to C12 hydrocarbon radicals in the alcohol moiety and/or vinyl aromatic monomer,
wherein the mixture further comprises a glycidyl esters of an aliphatic carboxylic acid in an amount of ≧5 weight-% to ≦20 weight-%,
thereby obtaining a copolymer (P),
said amounts based on the total weight of the solids in the dispersion, the amounts given adding up to ≦100 weight-%.
6. A method comprising utilizing the dispersion according to claim 1 as a coating material.