Urethane based coating applied in-line for improved ink adhesion
View Patent ↗A printable, coated, biaxially oriented film is provided that includes a polypropylene base film having a first and a second side, and a urethane coating on the first side. The coating has been applied to the base film between a machine direction orientation and a transverse direction orientation of a two step tentering operation. A method for manufacturing the film is also provided which includes the steps of forming a base film of a substantially uniform film layer of polypropylene, uniaxially orienting the base film by machine direction stretching, applying a coating of urethane to a first side of the uniaxially oriented base film, and biaxially orienting the coated film by stretching the film transversely to the machine direction.
1. A printable, coated, biaxially oriented film, comprising:
(a) a polymeric base film having a predominant polymer, and a first and a second side, said predominant polymer being polypropylene; and
(b) a urethane coating on said first side, said coating having been applied to said base film between a machine direction orientation and a transverse direction orientation of a two step tentering operation.
2. The film of claim 1 , wherein the base film additionally comprises a base film antiblock agent.
3. The film of claim 2 , wherein the base film antiblock agent is present at up to 1% by weight of the film.
4. The film of claim 2 , wherein the base film antiblock agent is present at up to 0.5% by weight of the film.
5. The film of claim 2 , wherein the base film antiblock agent is an antiblock agent selected from the group consisting of silica-based, silicone-based, and a blend of silica-based and silicone-based antiblock agents.
6. The film of claim 1 , wherein the urethane coating comprises a waterborne urethane dispersion.
7. The film of claim 1 , wherein the urethane coating comprises a waterborne urethane dispersion blended with waterborne acrylic dispersions.
8. The film of claim 1 , wherein the urethane coating comprises a crosslinking agent.
9. The film of claim 8 , wherein the crosslinking agent is present in the coating at up to 1% by dry weight.
10. The film of claim 8 , wherein the crosslinking agent is polyfunctional aziridine crosslinking agent at up to 1% by dry weight of the coating.
11. The film of claim 1 , wherein the urethane coating comprises a coating antiblock agent.
12. The film of claim 11 , wherein the urethane coating comprises up to 1% coating antiblock agent based on dry component weight of the coating.
13. The film of claim 11 , including a base film antiblock agent selected from the group consisting of silica-based, silicone-based, and a blend of silica-based and silicone-based antiblock agents.
14. The film of claim 1 , including a surface treatment on the first side beneath the urethane coating.
15. The film of claim 14 , wherein the surface treatment on the first side comprises an oxidative treatment.
16. The film of claim 1 , including a surface treatment on the second side.
17. The film of claim 16 , wherein the surface treatment on the second side comprises an oxidative treatment.
18. The film of claim 1 , wherein the polypropylene is a polypropylene homopolymer.
19. The film of claim 1 , wherein the polypropylene is a copolymer of propylene.
20. The film of claim 1 , wherein the polypropylene is a blend of homopolymers and copolymers.
21. The film of claim 1 , wherein the base film is a coextruded structure.
22. The film of claim 21 , wherein the coextruded structure has at least three layers.
23. The film of claim 21 , wherein the coextruded structure includes a core and at least one skin layer.