Biaxially oriented polylactic acid film with improved heat seal properties
Multi-layer biaxially oriented polylactic acid (BOPLA) film with a novel formulation improves the heat seal initiation temperature and heat seal performance of BOPLA films while maintaining good optical clarity. The film may include a core layer including polylactic acid base polymer resin, and a heat sealable layer including amorphous polylactic acid base polymer and a modifier comprising polycaprolactone or poly(butylene-adipate-co-butylene terephthalate).
1. A biaxially oriented film comprising:
a core layer consisting essentially of polylactic acid base polymer resin; and
a heat sealable layer comprising amorphous polylactic acid base polymer and a modifier comprising polycaprolactone or poly(butylene-adipate-co-butylene terephthalate),
wherein the amorphous polylactic acid base polymer has a peak melting point and the film has a heat seal strength of 200-365 g/25 mm at 250° F.
2. The biaxially oriented film of claim 1 , wherein the heat sealable layer comprises at least 50 wt % amorphous polylactic acid base polymer.
3. The biaxially oriented film of claim 1 , wherein the modifier comprises polycaprolactone and poly(butylene-adipate-co-butylene terephthalate).
4. The biaxially oriented film of claim 1 , wherein the core layer comprises crystalline polylactic acid base polymer resin.
5. The biaxially oriented film of claim 1 , wherein the core layer comprises 2-10 wt % ethylene-acrylate copolymer.
6. The biaxially oriented film of claim 1 , further comprising a skin layer comprising a polylactic acid base polymer resin on a side of the core layer opposite the heat sealable layer.
7. The biaxially oriented film of claim 6 , wherein the skin layer is a printing ink receiving layer, a metal receiving layer or a coating receiving layer.
8. The biaxially oriented film of claim 6 , wherein the skin layer has the same composition as the heat sealable layer.
9. The biaxially oriented film of claim 1 , wherein the film is oriented in the transverse direction at least 8.0x.
10. The biaxially oriented film of claim 1 , wherein the heat sealable layer comprises less than 50 wt % modifier.
11. The biaxially oriented film of claim 10 , wherein the heat sealable layer comprises 10-20 wt % modifier.
12. A biaxially oriented film comprising:
a core layer consisting essentially of polylactic acid base polymer resin; and
a heat sealable layer comprising amorphous polylactic acid base polymer and a modifier, wherein the modifier reduces the seal initiation temperature by at least 5° F. (2.8° F.) compared to the heat sealable layer without the modifier, and wherein the heat sealable layer maintains compostability per ASTM D6400-99 in less than 180 days,
wherein the amorphous polylactic acid base polymer has a peak melting point and the film has a heat seal strength of 200-365 g/25 mm at 250° F.
13. The biaxially oriented film of claim 12 , wherein the heat sealable layer comprises polycaprolactone or poly(butylene-adipate-co-butylene terephthalate).
14. The biaxially oriented film of claim 12 , wherein the heat sealable layer comprises at least 50 wt % amorphous polylactic acid base polymer.
15. The biaxially oriented film of claim 12 , wherein the core layer comprises crystalline polylactic acid base polymer resin.
16. The biaxially oriented film of claim 12 , wherein the film is oriented in the transverse direction at least 8.0x.
17. The biaxially oriented film of claim 12 , wherein the heat sealable layer comprises less than 50 wt % modifier.
18. The biaxially oriented film of claim 17 , wherein the heat sealable layer comprises 10-20 wt % modifier.
19. A method of making a multilayer film comprising:
co-extruding a film comprising a core layer consisting essentially of polylactic acid base polymer, and a heat sealable layer comprising amorphous polylactic acid base polymer and a modifier comprising polycaprolactone or poly(butylene-adipate-co-butylene terephthalate); and
biaxially orienting the film,
wherein the amorphous polylactic acid base polymer has a peak melting point and the film has a heat seal strength of 200-365 g/25 mm at 250° F.
20. The method of claim 19 , wherein the heat sealable layer comprises at least 50 wt % amorphous polylactic acid base polymer.
21. The method of claim 19 , wherein the modifier comprises polycaprolactone and poly(butylene-adipate-co-butylene terephthalate).
22. The method of claim 19 , wherein the core layer comprises crystalline polylactic acid base polymer resin.
23. The method of claim 19 , wherein the core layer comprises 2-10 wt % ethylene-acrylate copolymer.
24. The method of claim 19 , further comprising a skin layer comprising a polylactic acid base polymer resin on a side of the core layer opposite the heat sealable layer.
25. The method of claim 24 , wherein the skin layer is a printing ink receiving layer, a metal receiving layer or a coating receiving layer.
26. The method of claim 24 , wherein the skin layer has the same composition as the heat sealable layer.
27. The method of claim 19 , wherein the film is oriented in the transverse direction at least 8.0x.
28. The method of claim 19 , wherein the heat sealable layer comprises less than 50 wt % modifier.
29. The method of claim 28 , wherein the heat sealable layer comprises 10-20 wt % modifier.