| abstract |
In one embodiment, the invention provides a polyethylene terephthalate film comprising a biaxially oriented and birefringent film polyethylene terephthalate film having at least one layer having a thickness of from 10 mils (0.25 mm) to 25 mils (0.64 mm), wherein the film is formed from a polyethylene terephthalate resin comprising the reaction product of dimethyl terephthalate, terephthalic acid, or a combination thereof ethylene glycol, a diol or triol monomer other than ethylene glycol and from 0.9 to 3 mol percent of a sulfonate monomer having an inorganic counterion based on 100 mol percent dimethyl terephthalate, terephthalic acid, or a combination thereof. |