Coating compositions, coated substrates and hermetic seals made therefrom having improved low temperature sealing and hot tack properties
View Patent ↗Novel coated substrates are disclosed wherein a substrate is coated with a coating composition that forms good hermetic seals at very low temperatures and exhibits good blocking and slip characteristics. Such coating composition is comprised of an aqueous dispersion of a substantially non-polar copolymer of ethylene and an alpha-olefin having less than 20 carbon atoms, and an additive selected from the group consisting of an anti-blocking and slip agent, a coalescent and wetting agent, and mixtures thereof.
1. A coating composition, comprising:
a) a first liquid,
b) a first ethylene copolymer and second ethylene copolymer dispersed in the first liquid, the mean particle size of the dispersion in the range from 400 to 1200 nanometers; and
c) a second liquid with a second polymer dispersed in the second liquid, said second polymer having a mean particle size of less than 50 nanometers, said second polymer comprises at least 5 wt % of the total combined weight of the first polymer and the second polymer.
2. The coating composition of claim 1 , further comprising a dispersing agent, wherein the liquid comprises water, and wherein the second polymer is selected from the group consisting of an ethylene-acrylic acid copolymer, an ionized salt of the ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ionized salt of the ethylene-methacrylic acid copolymer, and mixtures thereof.
3. The coating composition of claim 2 , wherein the first and second ethylene copolymers are dispersed in a first aqueous dispersion and the second copolymer is dispersed in a second aqueous dispersion.
4. The coating composition of claim 1 , further comprising a slip agent.
5. The coating composition of claim 4 , wherein the slip agent has a mean particle size of less than 130 nanometers.
6. The coating composition of claim 4 , wherein the slip agent comprises a polyethylene wax, a paraffin wax, a microcrystalline wax, a beeswax, a carnauba wax, a montan wax, a candelilla wax, or mixtures thereof.
7. The coating composition of claim 1 , wherein the mean particle size of the first ethylene copolymer is less than 1000 nanometers.
8. The coating composition of claim 2 , wherein the first ethylene copolymer comprises ethylene and an alpha-olefin having less than 20 carbon atoms.
9. The coating composition of claim 8 , wherein the alpha-olefin is 1-octene.
10. The coating composition of claim 9 , wherein the first ethylene copolymer comprises ethylene and 1-octene and has a melt index of less than 35 g/10 min measured in accordance with ASTM D1238.
11. The coating composition of claim 2 , wherein the first ethylene copolymer comprises ethylene and a first alpha olefin, and
wherein the second ethylene copolymer has a second mean particle size and comprises ethylene and a second alpha-olefin, and
wherein the second alpha-olefin has less than 20 carbon atoms.
12. The coating composition of claim 11 , wherein the second alpha-olefin is 1-octene.
13. The coating composition of claim 12 ,
wherein the first ethylene copolymer and the second ethylene copolymer have a melt index of less than 10 g/10 min measured in accordance with ASTM D1238.
14. The coating composition of claim 12 , wherein the first ethylene copolymer comprises ethylene and 1-octene, has a mean particle size of less than 1100 nanometers and a melt index of less than 10 g/10 min measured in accordance with ASTM D1238,
wherein the second ethylene copolymer comprises ethylene and 1-octene, has a mean particle size of less than 850 nanometers and a melt index of less than 35 g/10 min measured in accordance with ASTM D1238.
15. The coating composition of claim 11 , wherein the first alpha-olefin and the second alpha-olefin are different.
16. The coating composition of claim 2 , wherein the dispersing agent comprises a copolymer selected from the group consisting of an ethylene-acrylic acid copolymer, an ionized salt of the ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ionized salt of the ethylene-methacrylic acid copolymer, a fatty acid, a ionized salt of a fatty acid, and mixtures thereof.
17. The coating composition of claim 16 , wherein the dispersing agent is ethylene-acrylic acid copolymer ionized with potassium hydroxide or montanic acid ionized with potassium hydroxide.
18. The coating composition of claim 3 , wherein the mean particle size of the second aqueous dispersion is less than 40 nanometers.
19. The coating composition of claim 2 , wherein the second polymer comprises at least 10 wt % of the total combined weight of the first ethylene copolymer, second ethylene copolymer and the second polymer.
20. The coating composition of claim 2 , wherein the second polymer comprises at least 15 wt % of the total combined weight of the first ethylene copolymer, second ethylene copolymer and the second polymer.
21. The coating composition of claim 1 , further comprising an anti-block agent.
22. The coating composition of claim 21 , wherein the anti-block agent is selected from the group consisting of a polymethylmethacrylate particles, silicone particles, colloidal silica, fumed silica particles, silicone gum, talc, finely-divided clay, and mixtures thereof.
23. The coating composition of claim 22 , wherein the mean particle size of the anti-block agent is from 0.5 to 10 microns.
24. The coating composition of claim 1 , further comprising a coalescent and wetting agent.
25. The coating composition of claim 24 , wherein the coalescent and wetting agent is selected from the group consisting of a hexyl or benzyl ether of ethylene glycol, a hexyl ether of diethylene glycol, a butyl alcohol, a hexyl alcohol, an octyl alcohol, diacetone alcohol, a non-ionic surfactant, an anionic surfactant, and mixtures thereof.
26. The coating composition of claim 1 , further comprising a primer.
27. The coating composition of claim 26 , wherein the primer is selected from the group consisting of polyethylene imine (PEI) resin, a crosslinked epoxy resin, and a polyurethane resin.
28. A coating composition, comprising:
(a) a first aqueous dispersion having a mean particle size in the range from 400 to 1200 nanometers, wherein the first aqueous dispersion comprises a first copolymer and a dispersing agent,
wherein the first copolymer comprises a copolymer of ethylene and an alpha-olefin having less than 20 carbon atoms,
wherein the dispersing agent comprises a copolymer selected from the group consisting of an ethylene-acrylic acid copolymer, an ionized salt of the ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ionized salt of the ethylene-methacrylic acid copolymer, a fatty acid, a ionized salt of a fatty acid and mixtures thereof;
(b) a second aqueous dispersion having a mean particle size of less than 50 nanometers,
wherein the second aqueous dispersion is comprised of a second copolymer selected from the group consisting of an ethylene-acrylic acid copolymer, an ionized salt of the ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ionized salt of the ethylene-methacrylic acid copolymer, and mixtures thereof; and
wherein the second copolymer comprises at least 5 wt % of the combined total weight of the first copolymer and the second copolymer.