High-reflectivity polyester coating
View Patent ↗A high reflectivity coated substrate and coating composition employing a binder containing a polyester resin that includes a cycloaliphatic group and has a number average molecular weight from about 1,000 to 40,000. The binder contains less than 40 weight percent aromatic group containing compound and the weight ratio of pigment to binder is greater than 0.9:1. When the binder is blended with rutile TiO 2 at a solids loading of 50 weight percent and coated to a dried film thickness of 0.00254 cm, the coating exhibits a Y-value of at least 85.5.
1. A coated substrate article comprising
a substrate coated with a coating composition, wherein the coating composition comprises:
(i) a binder comprising a polyester resin that includes a cycloaliphatic group and has a number average molecular weight from about 1,000 to 40,000, the binder comprising less than 40 weight percent aromatic group containing compound, and
(ii) a pigment,
wherein the weight ratio of pigment to binder is greater than 0.9:1, and wherein the binder, when blended with rutile TiO 2 at a solids loading of 50 weight percent and coated to a dried film thickness of 0.00254 cm, exhibits a Y-value of at least 85.5.
2. The coated substrate of claim 1 wherein the polyester resin has a number average molecular weight between about 1,500 and 10,000.
3. The coated substrate of claim 1 wherein the polyester resin has a pencil hardness of at least HB.
4. The coated substrate of claim 1 wherein the polyester resin has a flexibility of at least 2T and no cracks are visible when a 2T specimen is viewed at a 10× magnification.
5. The coated substrate of claim 1 wherein the polyester resin has a hydroxyl number from about 20 to 90.
6. The coated substrate of claim 1 wherein the polyester resin has an acid number from about 2 to 20.
7. The coated substrate of claim 1 wherein the polyester resin has an acid number between about 5 and 10.
8. The coated substrate of claim 1 , wherein the substrate comprises a lighting fixture reflector.
9. The coated substrate of claim 1 , wherein the substrate comprises an architectural metal skin.
10. The coated substrate of claim 8 , wherein the architectural metal skin comprises gutter stock, window blinds, siding or a window frame.
11. A coating composition comprising:
(i) a binder comprising a polyester resin that includes a cycloaliphatic group and has a number average molecular weight from about 1,000 to 40,000, the binder comprising less than 40 weight percent aromatic group containing compound, and
(ii) a pigment,
wherein the weight ratio of pigment to binder is greater than 0.9:1, and wherein the binder, when blended with rutile TiO 2 at a solids loading of 50 weight percent and coated to a dried film thickness of 0.00254 cm, exhibits a Y-value of at least 85.5.
12. The coating composition of claim 11 , wherein the polyester resin has a number average molecular weight between about 1,500 and 10,000.
13. The coating composition of claim 11 , wherein the polyester resin has a pencil hardness of at least HB.
14. The coating composition of claim 11 , wherein the polyester resin has a flexibility of at least 2T and no cracks are visible when a 2T specimen is viewed at a 10× magnification.
15. The coating composition of claim 11 , wherein the polyester resin has a hydroxyl number from about 20 to 90.
16. The coating composition of claim 11 , wherein the polyester resin has an acid number from about 2 to 20.
17. The coating composition of claim 11 , wherein the polyester resin has an acid number between about 5 and 10.
18. The coating composition of claim 11 , wherein the polyester resin is formed from the reaction of one or more polyols and a cycloaliphatic polycarboxylic acid, ester or anhydride.
19. The coating composition of claim 11 , wherein the polyester resin is formed from the reaction of one or more polyols and a compound comprising a 1,2-, 1,3- or 1,4-cyclohexanedicarboxylic acid or its methyl ester; a 1,2-isomer anhydride; or derivative of such compound.
20. The coating composition of claim 11 , wherein the binder comprises less than 20 weight percent aromatic group containing compound.
21. The coating composition of claim 11 , wherein the binder comprises less than 10 weight percent aromatic group containing compound.
22. The coating composition of claim 11 , wherein the pigment:binder weight ratio is at least 1:1 and less than 1.4:1.
23. The coating composition of claim 11 , wherein the binder, when blended with rutile TiO 2 at a solids loading of 50 weight percent and coated to a dried film thickness of 0.00254 cm, exhibits a Y-value of at least 87.5.
24. The coating composition of claim 11 , wherein a cured or hardened coating formed from the coating composition exhibits a Y-value of at least 85.5.
25. The coating composition of claim 11 , wherein a cured or hardened coating formed from the coating composition exhibits a Y-value of at least 86.5.
26. The coating composition of claim 11 , wherein a cured or hardened coating formed from the coating composition exhibits a Y-value of at least 87.5.
27. The coating composition of claim 11 , wherein the pigment is white.
28. The coating composition of claim 11 , wherein the polyester resin is formed from a polyol consisting essentially of 1,6-hexanediol, pentaerythritol, trimethylolpropane, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, trimethylol ethane, 3-hydroxy-2,2-dimethylpropyl 3-hydroxy-2,2-dimethylpropionate, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol or hydrogenated bisphenol A.