Polymer compositions and coatings for food and beverage packaging
The present disclosure relates to coatings and coating compositions that are substantially free of bisphenol A (BPA) and similar compounds, which help reduce or minimize flavor loss associated with foods or beverages stored in contact with the coating compositions. In one aspect, the composition can include the reaction products of an intimate mixture of cyclic ether resins and acrylate resins, which provides a unique cross-linked and interpenetrating network of polymers.
1. A coating composition for use in food and beverage packaging, comprising a polymeric reaction product formed from a mixture of:
a) at least one cyclic ether monomer selected from the group consisting of isosorbide diglycidyl ether, ethylene oxide and vinyl oxirane in a 5:1 ratio by weight, propylene oxide and vinyl oxirane in a 10:1 ratio by weight, and 1,4-cyclohexanedimethanol diglycidyl ether,
b) at least one polyacrylate monomer selected from the group consisting of dipentaerythritol pentaacrylate, diacryloyl methane, tripropylene glycol diacrylate, propoxylated neopentyl glycol diacrylate, and trimethylolpropane triacrylate,
c) a free radical initiator,
d) at least one surfactant, and
e) a carrier liquid, wherein:
from 5% to 25% of skeletal bonds in the polymeric reaction product are network-forming bonds; and
the coating composition is substantially free of BPA, BPF, BADGE and BFDGE.
2. The coating composition according to claim 1 , wherein the polymeric reaction product constitutes at least 20% of the coating composition as measured by dry weight.
3. The coating composition according to claim 1 , wherein the mixture further comprises a cross-linker in an amount from about 0.1% to about 10% by weight.
4. The coating composition according to claim 1 , wherein the mixture further comprises a condensation-type cross-linking resin selected from methylated and butylated melamines, alkylated and imino mixed ether melamines, alkylated ureas, formaldehyde-free modified ureas, benzoguanamine, glycoluril, and combinations thereof.
5. The coating composition according to claim 1 , wherein the mixture further comprises a catalyst selected from a tetraalkyl ammonium halide, a tetraalkyl phosphonium iodide or acetate, a tetraaryl phosphonium iodide or acetate, tin octoate, zinc octoate, triphenylphosphine, or any combination thereof.
6. The coating composition according to claim 1 , wherein:
a) the at least one cyclic ether monomer is 1,4-cyclohexanedimethanol diglycidyl ether; and
b) the at least one polyacrylate monomer is tripropylene glycol diacrylate, trimethylolpropane triacrylate, propoxylated neopentyl glycol diacrylate, or any combination thereof.
7. The coating composition according to claim 1 , wherein the at least one acrylate monomer is from about 4.7 wt % to about 9.4 wt % of the mixture.
8. The coating composition according to claim 1 , wherein the at least one cyclic ether monomer is about 9.5 wt % of the mixture.
9. The coating composition according to claim 1 , wherein the free-radical initiator comprises t-butylperoxybenzoate.
10. The coating composition according to claim 1 , wherein the at least one surfactant comprises 2,4,6-tris(dimethylamino)phenol and/or sodium bis(2-ethylhexyl) sulfosuccinate.
11. A food and beverage container comprising:
a) a metal selected from aluminum, aluminum alloys, steel, steel alloys, tin, tin alloys, zinc, zinc alloys, chrome or chrome alloys; and
b) a coating formed from the coating composition according to claim 1 at least partially coating a surface of the metal.
12. The food and beverage container according to claim 11 , wherein the coating is from 0.1 to 20 microns thick and has a contact angle with water of at least 70 degrees.
13. The food and beverage container according to claim 11 , wherein the coating remains intact after the coating has been in contact with an aqueous solution having a pH between 2.4 and 2.5 for a period of 12 months at a temperature between 20° C. and 25° C.
14. The food and beverage container according to claim 11 , wherein the coating remains intact after the side of the metal opposite the coating receives an impact by an object uniformly over a 10 cm 2 surface area having a momentum of 25 μN/s, and wherein the coating is exposed to a carbonated or uncarbonated aqueous solution during a period from at least 24 hours prior to the impact to at least 24 hours following the impact.
15. The food and beverage container according to claim 11 , wherein:
a) the at least one cyclic ether monomer is 1,4-cyclohexanedimethanol diglycidyl ether; and
b) the at least one acrylate monomer is tripropylene glycol diacrylate, trimethylolpropane triacrylate, propoxylated neopentyl glycol diacrylate, or any combination thereof.