BLOCK COPOLYMER PIGMENT DISPERSANTS
The present invention is directed to a linear block copolymer, useful as a dispersant for pigment, wherein the block copolymer comprises acetoacetyl amine functional groups which serve as pigment anchoring groups. The linear block copolymer of this invention can be an AB, ABC, or ABA block copolymer. The present invention can be useful in dispersing and stabilizing a wide range of pigments in solvent based systems, and are particularly useful in providing pigment dispersions that are used in coating compositions for automobiles and trucks, where they provide improved efficiency of pigment use, lower paint viscosity, and reduced emission of volatile organic solvent.
1 . A pigment dispersant comprising a linear block copolymer, said linear block copolymer comprising:
(a) a linear A-block formed by polymerizing ethylenically unsaturated A-block monomers; and
(b) a linear B-block comprising one or more acetoacetyl amine functional groups as pigment anchoring groups, said linear B-block is formed by polymerizing ethylenically unsaturated B-block monomers;
wherein said linear A-block is essentially free from said acetoacetyl amine functional groups.
2 . The pigment dispersant of claim 1 , wherein said linear block copolymer further comprises:
(c) a linear C-block formed by polymerizing ethylenically unsaturated C-block monomers;
wherein said linear A-block and said C-block are essentially free from said acetoacetyl amine functional groups, and wherein said A-block monomers and said C-block monomers are the same or different.
3 . The pigment dispersant of claim 1 , wherein said B-block monomers comprise an acetoacetate monomer having one or more acetoacetate functional groups, and wherein said acetoacetyl amine functional groups are formed by reacting said acetoacetate functional groups with a primary amine.
4 . The pigment dispersant of claim 3 , wherein said acetoacetate monomers are selected from acetoacetoxyethyl methacrylate, acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, acetoacetoxypropyl acrylate, allyl acetoacetate, acetoacetoxybutyl methacrylate, acetoacetoxybutyl acrylate, or a combination thereof.
5 . The pigment dispersant of claim 3 , wherein said primary amine is selected from aliphatic, aromatic, heterocyclic compounds containing primary amine groups, or a combination thereof.
6 . The pigment dispersant of claim 3 , wherein said primary amine is selected from N-benzylamine, phenethylamine, 4-phenylbutylamine, 2,2-diphenylethylamine, propylamine, butylamine, aminoethanol, 2-amino-1-butanol, N,N-dimethylaminopropylamine, 4-(aminoethyl)morpholine, 2-(2-aminoethyl)-1-methyl pyrrolidine, 1-(2-aminoethyl)pyrrolidine, 2-(2-aminoethyl pyridine, 1-(2-aminoethyl)piperazine, 1-(2-aminoethyl)piperidine, 1-(3-aminopropyl)imidazole, 4-(3-aminopropyl)morpholine, 1-(3-aminopropyl)-2-pipecoline, 1-(3-aminopropyl)-2-pyrrolidinone, or a combination thereof.
7 . The pigment dispersant of claim 1 , wherein said B-block monomers comprise a hydroxyl monomer having one or more hydroxyl functional groups, wherein said acetoacetyl amine functional groups are formed by first reacting said hydroxyl functional groups with an acetoacetate agent to convert said hydroxyl functional groups to acetoacetate functional groups and then reacting said acetoacetate functional groups with a primary amine.
8 . The pigment dispersant of claim 7 , wherein said hydroxyl monomer is selected from hydroxyl acrylate, hydroxyl methacrylate, or a combination thereof.
9 . The pigment dispersant of claim 7 , wherein said acetoacetate agent comprises t-butyl acetoacetate.
10 . The pigment dispersant of claim 7 , wherein said primary amine is selected from aliphatic, aromatic, heterocyclic compounds containing primary amine groups, or a combination thereof.
11 . The pigment dispersant of claim 7 , wherein said primary amine is selected from N-benzylamine, phenethylamine, 4-phenylbutylamine, 2,2-diphenylethylamine, propylamine, butylamine, aminoethanol, 2-amino-1-butanol, N,N-dimethylaminopropylamine, 4-(aminoethyl)morpholine, 2-(2-aminoethyl)-1-methyl pyrrolidine, 1-(2-aminoethyl)pyrrolidine, 2-(2-aminoethyl)pyridine, 1-(2-aminoethyl)piperazine, 1-(2-aminoethyl)piperidine, 1-(3-aminopropyl)imidazole, 4-(3-aminopropyl)morpholine, 1-(3-aminopropyl)-2-pipecoline, 1-(3-aminopropyl)-2-pyrrolidinone, or a combination thereof.
12 . The pigment dispersant of claim 1 , wherein said linear B-block further comprises, as pigment anchoring groups, one or more acyclic amide groups, one or more cyclic amide groups, one or more quaternary ammonium groups, or a combination thereof.
13 . The pigment dispersant of claim 1 , wherein said B-block monomers comprise hydroxyl functional monomers.
14 . The pigment dispersant of claim 1 , wherein the linear block copolymer has a weight average molecular weight of about 2,000-100,000.
15 . A pigment dispersion comprising a pigment and the pigment dispersant of claim 1 .
16 . A coating composition comprising the pigment dispersion of claim 15 .
17 . A pigment dispersion comprising a pigment and the pigment dispersant of claim 2 .
18 . A coating composition comprising the pigment dispersion of claim 17 .