Hardenable compositions comprising polyacid(s) and polyol(s)
View Patent ↗The present invention provides hardenable coating compositions, comprising: a first compound selected from the group consisting of polyacids, polyanhydrides, salts thereof and mixtures thereof, and a second compound having two or more active hydrogen groups. When used as a roll coating composition, the first compound preferably has a low average molecular weight and an acid number greater than about 100. The hardenable coating composition preferably has an extended open time and can be rapidly cured to a substantially tack-free state in less than about one minute at 200° C. Coated articles and methods of coating are also provided.
1. A hardenable packaging coating composition, comprising:
a polyacid compound comprising a homopolymer or a copolymer derived from a compound selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, crotonic acid, salts thereof and mixtures thereof, wherein the polyacid compound has a weight average molecular weight between about 750 and 10,000 Daltons and an acid number from 250 to 600;
a polyhydroxyl compound, separate from the first compound, comprising a quaternized epoxy resin, wherein the polyhydroxyl compound has a weight average molecular weight between about 300 and 5,000 Daltons; and
a liquid carrier,
wherein the hardenable packaging coating composition is substantially formaldehyde free.
2. A coating composition according to claim 1 , wherein the polyacid compound is derived from methacrylic acid.
3. A coating composition according to claim 1 , wherein the polyacid compound has a weight average molecular weight of from about 1,000 to about 5,000 Daltons.
4. A coating composition according to claim 1 , further comprising a third compound having active hydrogen groups.
5. A coating composition according to claim 4 , wherein the third compound contains active hydrogen groups selected from the group consisting of hydroxyl groups, primary amino groups, secondary amino groups, thiol groups, and combinations thereof.
6. A coating composition according to claim 4 , wherein the third compound is selected from the group consisting of glycerol, ethylene glycol, propylene glycol, trimethylol propane, triethylolethane, ethylene diamine, ethanolamine, propanolamine, butanolanmine, pentanol amine, diethanolamine, triethanolamine, pentaerythritol, sorbitol, sucrose, bisphenol A, a quaternized epoxy resin, polyvinyl alcohol, trihydroxyethyl isocyanurate resorcinol, catechol, gallol, polymeric polyols, and mixtures thereof.
7. A coating composition according to claim 1 , wherein the composition has a solids content of from about 20% to about 80% by weight.
8. A coating composition according to claim 1 , which has a #4 Ford cup viscosity of about 40 to about 90 seconds at 25° C.
9. A coating composition according to claim 1 , which has no more than slight misting as determined with the misting/slinging test method.
10. A coating composition according to claim 1 , wherein the carrier comprises water.
11. A coating composition according to claim 1 , wherein the composition has a volatile organic compound level of less than 0.25 kg/l of coating composition and solvent.
12. A coating composition according to claim 1 , wherein the composition is in the form of an exterior varnish.
13. A coating composition according to claim 1 , wherein the composition remains tacky for at least 15 minutes at room temperature when applied to yield a dry film thickness of 2.2+/−0.63 g/m 2 .
14. The coating composition according to claim 1 , wherein the quaternized epoxy resin is derived from an epoxy resin that comprises at least two epoxide groups.
15. The coating composition according to claim 14 , wherein the epoxide groups are terminal epoxide groups.
16. A hardenable packaging coating composition, comprising: (a) a polyacid compound comprising a homopolymer or a copolymer derived from a compound selected from the group consisting of acrylic acid and methacrylic acid, salts thereof and mixtures thereof, wherein the polyacid compound has an acid number from 250 to 600 and a weight average molecular weight between about 750 and 10,000 Daltons; and (b) quaternized epoxy resin having a weight average molecular weight between about 300 and 5000 Daltons; and
a liquid carrier comprising water,
wherein the hardenable packaging coating composition has no more than slight misting as determined with the misting/slinging test method and can be rapidly cured to a substantially tack-free state in less than about one minute at 200° C., and wherein the coating composition is essentially formaldehyde free.
17. A coating composition according to claim 16 , wherein the first compound has a weight average molecular weight between about 1000 5000 Daltons.