Coatings having low volatile organic compound content
View Patent ↗The present invention provides a method of making an aqueous coating composition comprising an aqueous dispersion of an epoxy acrylate resin and a polymerized reactive diluent. The aqueous coating composition preferably has a volatile organic compound content of no greater than 0.4 kilogram per liter of solids.
1. A method of making a coating composition, comprising the steps of:
blending an epoxy material, a reactive diluent, and an acrylic resin;
reacting the epoxy material and the acrylic resin to form an epoxy acrylate resin;
dispersing the reactive diluent and the epoxy acrylate resin into water; and
polymerizing the reactive diluent, wherein the aqueous coating composition formed has a volatile organic compound content of no greater than 0.4 kilogram per liter of solids.
2. The method of claim 1 , wherein the epoxy material comprises diglycidyl ether of bisphenol-A.
3. The method of claim 1 , wherein the molecular weight of the epoxy material is 350 to 6,000.
4. The method of claim 1 , wherein the molecular weight of the epoxy material is 1,500 to 4,000.
5. The method of claim 1 , wherein the acrylic resin comprises a polymeric backbone having at least one pendant or terminal carboxylic acid moiety.
6. The method of claim 5 , wherein the acrylic resin is formed using a monomer selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, crotonic acid, maleic acid, and itaconic acid.
7. The method of claim 5 , wherein the acrylic resin is formed using a monomer selected from the group consisting of ethyl acrylate, methyl acrylate, butyl acrylate, ethyl methacrylate, methyl methacrylate, butyl methacrylate, styrene, substituted styrene, vinyl acetate, vinyl chloride, vinylidene chloride, 2-ethylbexyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-hydroxyethyl acrylate, poly(ethylene glycol) acrylate, isobornyl acrylate, acrylamide, and acrylonitrile.
8. The method of claim 5 , wherein the acrylic resin is formed using acrylic acid, styrene, and ethyl acrylate.
9. The method of claim 1 , wherein the composition further comprises an initiator.
10. The method of claim 1 , wherein the volatile organic compound content of the coating composition is no greater than 0.3 kilogram per liter of solids.
11. The method of claim 1 , wherein the volatile organic compound content of the coating composition is no greater than 0.2 kilogram per liter of solids.
12. The method of claim 1 , wherein the volatile organic compound content of the coating composition is no greater than 0.1 kilogram per liter of solids.
13. The method of claim 1 , wherein the coating composition is substantially free of formaldehyde.
14. A method of coating a substrate comprising the steps of:
applying a coating prepared according to the method of claim 1 on a substrate; and
hardening the coating.
15. The method of claim 14 , wherein the substrate is metal.
16. The method of claim 14 , wherein the substrate is a portion of a container.
17. A coating composition prepared by the method of claim 1 .
18. A substrate coated with a coating composition prepared according to the method of claim 1 .
19. A method of making a coating composition, comprising the steps of:
blending an epoxy material, a reactive diluent, and an acrylic resin;
reacting the epoxy material and the acrylic resin to form an epoxy acrylate resin;
dispersing the reactive diluent and the epoxy acrylate resin into water; and
polymerizing the reactive diluent, wherein the aqueous coating composition formed has a volatile organic compound content of no greater than 0.4 kilogram per liter of solids, and
wherein the reactive diluent is selected from the group consisting of ethyl acrylate, 2-ethylhexyl acrylate, methyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-hydroxyethyl acrylate, poly(ethylene glycol) acrylate, isobornyl acrylate, butyl methacrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, 2-hydroxyethyl methacrylate, poly(ethylene glycol) methacrylate, poly(propylene glycol) methacrylate, styrene, substituted styrene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylamide, and acrylonitrile.
20. The method of claim 19 , wherein the reactive diluent comprises butyl acrylate and styrene.
21. The method of claim 19 , wherein the reactive diluent comprises butyl acrylate.
22. A method of making a coating composition, comprising the steps of:
blending an epoxy material, a reactive diluent, and an acrylic resin;
reacting the epoxy material and the acrylic resin to form an epoxy acrylate resin;
dispersing the reactive diluent and the epoxy acrylate resin into water; and
polymerizing the reactive diluent, wherein the aqueous coating composition formed has a volatile organic compound content of no greater than 0.4 kilogram per liter of solids, and
wherein the composition further comprises an initiator selected from the group consisting of peroxides, persulfates, sulfites, bisulfites, azoalkanes, UV light initiators, and visible light initiators.
23. A method of making a coating composition, comprising the steps of:
blending an epoxy material, a reactive diluent, and an acrylic resin;
reacting the epoxy material and the acrylic resin to form an epoxy acrylate resin;
dispersing the reactive diluent and the epoxy acrylate resin into water; and
polymerizing the reactive diluent, wherein the aqueous coating composition formed has a volatile organic compound content of no greater than 0.4 kilogram per liter of solids, and
wherein the composition further comprises an initiator selected from the group consisting of benzoyl peroxide, t-butyl hydroperoxide, ammonium persulfate, hydrazine, ammonium sulfites, alkali metal sulfites, bisulfites, metabisulfites, hydrosulfites, and combinations thereof.
24. A method of making a coating composition, comprising the steps of:
blending an epoxy material, a reactive diluent, and an acrylic resin;
reacting the epoxy material and the acrylic resin to form an epoxy acrylate resin;
dispersing the reactive diluent and the epoxy acrylate resin into water; and
polymerizing the reactive diluent, wherein the aqueous coating composition formed has a volatile organic compound content of no greater than 0.4 kilogram per liter of solids, and
wherein the composition further comprises an initiator comprising benzoin and hydrogen peroxide.