Anti-blush and chemical resistant polyester film
Embodiments herein relate to a polymer film comprising an anti-blushing composition in a blend comprising polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); wherein the blend contains at least 50 wt. % of PBT; wherein the anti-blushing composition comprises a phosphorus containing compound but excludes certain phosphorus compounds; and wherein the anti-blushing composition is configured to prevent blushing in the polymer film laminated directly to a metal substrate sheet and exposed to steam at a temperature of 260° F. for 90 minutes.
1. A method of reducing blushing on a film laminated to a metal, comprising:
a. exposing the film to a retort process, and
b. obtaining a blush-free film after the retort process;
c. wherein the film comprises a polyethylene terephthalate (PET), a polybutylene terephthalate (PBT) and a derivative of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and
d. wherein the derivative comprises a phosphate and has a higher molecular weight than that of the bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite.
2. The method of claim 1 , wherein the derivative has a molecular weight greater than 604.
3. The method of claim 1 , wherein the derivative has a molecular weight in the range of about 605 to 700.
4. The method of claim 1 , wherein the derivative has a molecular weight in the range of about 610 to 660.
5. The method of claim 1 , wherein the derivative has a molecular weight in the range of about 620 to 640.
6. The method of claim 1 , wherein the derivative comprises a monophosphate and a diphosphate.
7. The method of claim 6 , wherein the monophosphate comprises bis(2,4-di-tert-butylphenyl) pentaerythritol monophosphate.
8. The method of claim 6 , wherein the diphosphate comprises bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphate.
9. The method of claim 1 , wherein derivative comprises an orthophosphate.
10. The method of claim 1 , wherein the PBT is at least about 40% by weight in the film.
11. The method of claim 10 , wherein the PBT is about 40% to about 80% by weight in the film.
12. The method of claim 11 , wherein the PBT is about 50% weight to about 70% in the film.
13. The method of claim 1 , wherein the film is laminated on an exterior surface of a container.
14. The method of claim 1 , wherein an average melting point of the PET in the film as measured by a differential scanning colorimeter (DSC) ranged from about 244.0° C. to about 250.0° C.
15. The method of claim 14 , wherein the average melting point of the PET in the film ranged from 244.0° C. to 248.5° C.
16. The method of claim 1 , wherein the film is laminated on an interior surface of a container.
17. The method of claim 1 , wherein the film comprises a single layer.
18. The method of claim 1 , wherein the film comprises at least a two layer.
19. The method of claim 1 , wherein a thickness of the film is in a range of about 1 μm to about 80 μm.