Crosslinked coating compositions for packaging articles such as food and beverage containers
A method of forming a coating on a food or beverage container, which includes spraying a coating composition onto an interior surface of the food or beverage container, where the coating composition includes a latex copolymer and a metal drier or crosslinking agent. The latex copolymer is a reaction product of monomers that include (a) one or more styrene-mimicking monomers containing one or more cyclic groups and one or more ethylenically-unsaturated groups, at least a portion of such styrene-mimicking monomers being polycyclic monomers containing ring unsaturation, and (b) one or more other ethylenically-unsaturated monomers. Preferably, the coating composition is substantially free of each of BPA, PVC, other halogenated monomers, and optionally styrene. The method may also include curing the sprayed coating composition, thereby providing the coating on the interior surface of the food or beverage container.
1. An inside spray coating composition for a food or beverage container, the composition comprising:
a liquid carrier; and
an acrylic copolymer comprising a reaction product of monomers comprising:
one or more monomers containing one or more cyclic groups and one or more ethylenically-unsaturated groups, at least a portion of such monomers being polycyclic monomers containing ring unsaturation, wherein the polycyclic monomers containing ring unsaturation comprise norbornene (meth)acrylate, tricyclodecenyl (meth)acrylate, octahydronaphthalene (meth)acrylate, norbornene (meth)acrylamide, tricyclodecenyl (meth)acrylamide, octahydronaphthalene (meth)acrylamide, tricyclodecenyl vinyl acetate, norbornene vinyl acetate, octahydronaphthalene vinyl acetate, or a combination thereof; and
one or more other ethylenically-unsaturated monomers;
wherein the coating composition has an average viscosity ranging from about 5 seconds to about 40 seconds as measured using a Ford Viscosity Cup #4 at 25° C.
2. The composition of claim 1 , wherein the polycyclic monomers containing ring unsaturation comprise norbornene (meth)acrylate, tricyclodecenyl (meth)acrylate, or a combination thereof.
3. The composition of claim 1 , wherein the acrylic copolymer is solution polymerized.
4. The composition of claim 1 , wherein the acrylic copolymer is emulsion polymerized.
5. The composition of claim 1 , wherein the monomers used to produce the acrylic copolymer are substantially free of each of BPA, PVC, other halogenated monomers, and optionally styrene.
6. The composition of claim 1 , wherein the polycyclic monomers containing ring unsaturation constitute less than 50% of the monomers used to produce the acrylic copolymer.
7. The composition of claim 1 , wherein the one or more ethylenically-unsaturated monomers constitute at least 3% by weight of the acrylic copolymer, based on the total weight of the monomers used to produce the acrylic copolymer.
8. The composition of claim 1 , wherein the one or more other ethylenically-unsaturated monomers comprise one or more oxirane-functional monomers selected from glycidyl acrylate, glycidyl methacrylate, and combinations thereof.
9. The composition of claim 1 , wherein the coating exhibits a glass transition temperature ranging from about 50° C. to about 120° C.
10. The composition of claim 1 , wherein the liquid carrier comprises water and an organic solvent, and wherein the liquid carrier comprises greater than about 5% of organic solvent.
11. The composition of claim 1 , wherein the acrylic copolymer makes up 50% or more by weight of the composition, based on the entire weight of the total resin solids in the coating composition.
12. The composition of claim 1 , wherein the composition comprises a resole phenolic crosslinker.
13. An interior coating disposed on a food or beverage container, the interior coating comprising a cured coating composition comprising a reaction product of ethylenically-unsaturated polycyclic monomers containing ring unsaturation and one or more other ethylenically-unsaturated monomers, wherein the polycyclic monomers containing ring unsaturation comprise norbornene (meth)acrylate, tricyclodecenyl (meth)acrylate, octahydronaphthalene (meth)acrylate, norbornene (meth)acrylamide, tricyclodecenyl (meth)acrylamide, octahydronaphthalene (meth)acrylamide, tricyclodecenyl vinyl acetate, norbornene vinyl acetate, octahydronaphthalene vinyl acetate, or a combination thereof.
14. The interior coating of claim 13 , wherein the polycyclic monomers containing ring unsaturation comprise norbornene (meth)acrylate, tricyclodecenyl (meth)acrylate, or a combination thereof.
15. An interior coating disposed on a food or beverage container, the interior coating comprising a cured coating composition prepared by:
forming a coating composition comprising an acrylic copolymer that comprises a reaction product of an ethylenically-unsaturated polycyclic monomer containing ring unsaturation and one or more other ethylenically-unsaturated monomers, wherein the polycyclic monomer containing ring unsaturation comprise norbornene (meth)acrylate, tricyclodecenyl (meth)acrylate, octahydronaphthalene (meth)acrylate, norbornene (meth)acrylamide, tricyclodecenyl (meth)acrylamide, octahydronaphthalene (meth)acrylamide, tricyclodecenyl vinyl acetate, norbornene vinyl acetate, octahydronaphthalene vinyl acetate, or a combination thereof;
spraying the coating composition onto a surface; and
curing the coating composition to cause cross-linking of at least some of the ethylenically-unsaturated polycyclic monomer containing ring unsaturation.
16. The interior coating of claim 15 , wherein the coating composition further comprises a resole phenolic crosslinker.
17. The interior coating of claim 15 , wherein forming the acrylic copolymer comprises an organic solution polymerized copolymer.
18. The interior coating of claim 15 , wherein forming the acrylic copolymer comprises an emulsion polymerized latex copolymer.
19. The interior coating of claim 15 , wherein the coating exhibits a glass transition temperature ranging from about 50° C. to about 120° C.