Anti-blush and chemical resistant polyester film

A polymer film comprising an anti-blushing composition in a blend comprising polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), wherein PBT is polymerized in presence of tetra-n-butyl titanate, tetraisopropyl titanate or combinations thereof;

• wherein the blend has an intrinsic viscosity greater than 0.765 and contains at least 50 wt. % of PBT;
• wherein a melting point of the PET is greater than 244.5° C. and lower than 254.4° C.;
• wherein a degree of transesterification between the PET and the PBT is greater than 0.3 mol % and less than 6.47 mol %;
• wherein the anti-blushing composition excludes:
• triphenyl phosphite,
• bis(acetodeca)pentaerythritol diphosphite,
• bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol dibenzophosphite,
• bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite,
• bis(2,4-dicumylphenyl)pentaerythritol diphosphite,
• 2-[[2,4,8,10-tetrakis(1,1-dimethylether)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]-N,N-bis[2-[2,4,8,10-tetrakis(1,1-dimethylether)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]ethyl]ethanolamine,
• diphenyl isodecylphosphite,
• benzyl ethylphosphonate,
• trimethyl phosphate,
• triethyl phosphate,
• tributyl phosphate,
• ethyl diethylphosphonoacetate,
• tri-2-ethylhexyl phosphate,
• tris(2-chloroethyl)phosphate, and
• bis(acetodeca)pentaerythritol diphosphite;
• and
• wherein the anti-blushing composition comprises dialkyl pentaerythritol di phosphonate, pentaerythritol phosphonate or combinations thereof;
• wherein the anti-blushing composition is configured to prevent blushing in the polymer film laminated directly to a metal sheet and exposed to steam at a temperature of 251° F. for 90 minutes, wherein the anti-blushing composition is about 0.01 wt. % to about 1 wt. % in the blend.