Pigment dispersant
A pigment dispersant is disclosed comprising a tri-block copolymer having a first block comprising a glycidyl(meth)acrylate reacted with a napthoic acid, a second block comprising (meth)acrylic acid alkyl esters, and a third block comprising (meth)acrylic acid alkyl esters, wherein said third block is different from said second block. The dispersant is suited for use in a nanoparticulate dispersion comprising pigment particles having an average primary particle size of less than 100 nm.
1. A nanoparticulate dispersion comprising:
a) pigment particles having an average primary particle size of less than one micron; and
b) a dispersant comprising a tri-block copolymer prepared by controlled radical polymerization and represented by the following formula,
φ-(G) p -(W) q -(Y) s -T
wherein φ is a hydrophobic residue of or derived from a monomeric initiator, and is free of a radically transferable group,
G is a hydrophobic residue of an oxirane functional monomer reacted with a carboxylic acid,
W is a residue of (meth)acrylic acid alkyl esters, and -(W) q - defines a W-block,
Y is a residue of (meth)acrylic acid alkyl esters, and -(Y) s - defines a Y-block, wherein said W-block is different from said Y-block,
T is or is derived from the radically transferable group of said monomeric initiator, and
p, q, and s are each independently at least 1.
2. The dispersion of claim 1 wherein said pigment particles comprise organic pigments.
3. The dispersion of claim 1 wherein said carboxylic acid comprises an aromatic carboxylic acid or a polycyclic aromatic carboxylic acid.
4. The dispersion of claim 1 wherein said carboxylic acid comprises a napthoic acid.
5. The dispersion of claim 1 wherein said dispersion has a maximum haze of 1%.
6. The dispersion of claim 1 wherein said oxirane functional monomer comprises glycidyl(meth)acrylate.
7. The dispersion of claim 1 wherein said W-block comprises residues of hydroxy functional (meth)acrylic acid alkyl esters.
8. The dispersion of claim 1 wherein said pigment particles have an average primary particle size of up to 100 nm.
9. A pigment dispersant comprising a tri-block copolymer prepared by controlled radical polymerization and represented by the following formula,
φ-(G) p -(W) q -(Y) s -T
wherein φ is a hydrophobic residue of or derived from a monomeric initiator, and is free of a radically transferable group,
G is a hydrophobic residue of a glycidyl(meth)acrylate reacted with a napthoic acid,
W is a residue of (meth)acrylic acid alkyl esters, and -(W) q - defines a W-block,
Y is a residue of (meth)acrylic acid alkyl esters, and -(Y) s - defines a Y-block, wherein said W-block is different from said Y-block,
T is or is derived from the radically transferable group of said momomeric initiator, and
p, q, and s are each independently at least 1.
10. The dispersant of claim 9 wherein said napthoic acid comprises hydroxy napthoic acid.
11. The dispersant of claim 9 wherein said W-block comprises residues of hydroxy functional (meth)acrylic acid alkyl esters.
12. A pigment dispersion comprising (a) pigment particles having an average primary particle size of less than one micron and (b) the dispersant of claim 9 .
13. The dispersion of claim 12 wherein said pigment particles comprise organic pigments.
14. The dispersion of claim 12 wherein said dispersion has a maximum haze of 1%.
15. The dispersion of claim 12 wherein said W-block comprises residues of hydroxy functional (meth)acrylic acid alkyl esters.
16. The dispersion of claim 12 wherein said pigment particles have an average primary particle size of up to 100 nm.
17. A coating composition comprising (a) a resinous binder and (b) the pigment dispersion of claim 1 .
18. The coating composition of claim 17 wherein said pigment particles comprise organic pigments.
19. The coating composition of claim 17 wherein said pigment dispersion has a maximum haze of 1%.
20. A coated article comprising an article coated with the coating composition of claim 17 .
21. The nanoparticulate dispersion of claim 7 , wherein said Y-block consists essentially of residues of C 1 -C 20 -alkyl(meth)acrylates.
22. The pigment dispersant of claim 11 , wherein said Y-block consists essentially of residues of C 1 -C 20 -alkyl(meth)acrylates.