Water based printable coatings
View Patent ↗Various aqueous top coat compositions are described. The compositions include one or more polyurethane dispersions, silica, crosslinker(s), acrylic polymers, and an optional water soluble polyester. The compositions can be used to form top coats which exhibit good resistance to scratches and solvents, and improved ink retention.
1. An aqueous top coat composition comprising:
10 to 85 parts by weight of one or more polyurethanes;
10 to 60 parts by weight of one or more water soluble polyesters;
0 to 80 parts by weight of one or more acrylic polymers;
0.01 to 3 parts by weight of silica;
0.05 to 3 parts by weight crosslinker;
wherein the aqueous top coat composition comprises from 20 to 99.04% solids.
2. The top coat composition of claim 1 , wherein the polyurethanes include a hard polyurethane and a soft polyurethane.
3. The top coat composition of claim 1 , wherein the water soluble polyester is a linear polyester prepared from the polycondensation of glycols and dicarboxylic acids and has a molecular weight from 5,000 to 20,000.
4. The top coat composition of claim 3 , wherein the polyester has a glass transition temperature Tg from 36° C. to 52° C.
5. The top coat composition of claim 1 , wherein the crosslinker includes an aziridine crosslinker.
6. The top coat composition of claim 1 , wherein the composition comprises from 10 to 70 parts by weight of one or more acrylic polymers.
7. The top coat composition of claim 1 , further comprising at least one additional component selected from the group consisting of an antiblock agent, an acrylic polymer, and combinations thereof.
8. The top coat composition of claim 1 , further comprising water in addition to water found with any of the other components of the top coat composition.
9. A top coated substrate comprising:
a polymeric substrate;
a top coat disposed on the substrate, the top coat including 10 to 85 parts by weight of one or more polyurethanes, 0 to 80 parts by weight of one or more acrylic polymers, 10 to 60 parts by weight of one or more water soluble polyesters, 0.01 to 3 parts by weight of silica, and 0.05 to 3 parts by weight crosslinkers;
wherein the top coat is print receptive.
10. The top coated substrate of claim 9 , wherein the substrate is bi-axially oriented polypropylene (BOPP).
11. The top coated substrate of claim 9 , wherein the substrate is machine direction orientation (MDO) film.
12. The top coated substrate of claim 9 , wherein the substrate is polyester film.
13. The top coated substrate of claim 9 , wherein the polyurethanes include a hard polyurethane and a soft polyurethane.
14. The top coated substrate of claim 9 , wherein the water soluble polyester is a linear polyester prepared from the polycondensation of glycols and dicarboxylic acids and has a molecular weight from 5,000 to 20,000.
15. The top coated substrate of claim 9 , wherein the polyester has a glass transition temperature Tg from 36° C. to 52° C.
16. The top coated substrate of claim 9 , wherein the crosslinker includes an aziridine crosslinker.
17. The top coated substrate of claim 9 , wherein the composition comprises from 12 to 27 parts by weight of polyurethanes.
18. The top coated substrate of claim 9 , wherein the composition comprises from 15 to 25 parts by weight of water soluble polyesters.
19. The top coated substrate of claim 9 , wherein the composition comprises from 0.01 to 2 parts by weight silica.
20. The top coated substrate of claim 9 , wherein the composition comprises from 0.05 to 1 parts by weight crosslinker.