Branched polyester polymers and soft touch coatings comprising the same
A crosslinkable, branched polyester prepared by free radical polymerization of unsaturated polyester prepolymers, wherein the polymerization occurs primarily by reaction of the unsaturation is disclosed. Coatings comprising the same are also disclosed, as are substrates coated at least in part with such coatings.
1. A crosslinkable branched polyester polymer prepared by free radical polymerization of a double bond of a first unsaturated polyester prepolymer and a double bond of a second unsaturated polyester prepolymer, wherein each prepolymer independently comprises:
a) a polyol segment; and
b) an unsaturated polycarboxylic acid and/or an anhydride and/or ester thereof;
wherein the branched polyester polymer has a Tg of 25° C. or less.
2. The polyester of claim 1 , wherein the prepolymer further comprises a soft segment.
3. The polyester of claim 2 , wherein the soft segment comprises adipic acid.
4. The polyester of claim 1 , wherein the prepolymer further comprises isophthalic acid.
5. The polyester of claim 1 , wherein the polyol segment comprises 2-methyl-1,3-propanediol.
6. The polyester of claim 1 , wherein the unsaturated polycarboxylic acid/anhydride/ester comprises maleic acid/anhydride/ester and/or itaconic acid/anhydride/ester.
7. The polyester of claim 2 , wherein at least one prepolymer comprises adipic acid, 2-methyl-1,3-propanediol, and maleic acid/anhydride/ester.
8. The polyester of claim 1 , wherein the M W of the prepolymer is 5,000 to 10,000.
9. The polyester of claim 1 , wherein the M W of the polyester is 4,000 to 10,000.
10. The polyester of claim 1 , wherein the Mark Howink parameter of the polyester is 0.48 or less.
11. A coating comprising the polyester of claim 1 and a crosslinker therefor.
12. The coating of claim 11 , having a hardness as measured by the Fischer Micro-hardness test of 2 to 10 N/mm 2 , a coefficient of friction as measured by ASTM Method D1894 of 0.05 to 0.2, an abrasion resistance as measured by ASTM Method F2357 of 250 to 500 cycles and/or a surface roughness as measured by a Taylor Hobson Precision Surtronic Duo Profilometer of 20 μm to 50 μm.
13. The coating of claim 11 , wherein at least one of the prepolymers comprises adipic acid, 2-methyl-1,3-propanediol, and maleic acid/anhydride/ester.
14. The coating of claim 11 , wherein the coating further comprises a colorant.
15. The coating of claim 11 , wherein the crosslinker comprises isocyanate.
16. A substrate coated at least in part with the coating of claim 11 .
17. The substrate of claim 16 , wherein the substrate comprises a consumer electronic part.
18. The substrate of claim 16 , wherein the substrate comprises PC/ABS.
19. The substrate of claim 16 , wherein the substrate comprises a metal can.
20. The polyester of claim 1 , wherein the polyester does not comprise (meth)acrylate or residues thereof.
21. The polyester of claim 1 , wherein the only unsaturation in the prepolymers is from component b).