Patent ID: 8277710

Claim:
A biaxially oriented polyester film comprising 0.1-5.0% by weight based on the weight of the film, of a hydrolysis stabilizer based on epoxidized fatty acid esters and 0.2-10% by weight, based on the weight of the film, of epoxidized fatty acid glycerides, said epoxidized fatty acid esters having a mean molecular weight of at least 425 g/mol, wherein more than 90% by weight of the epoxidized fatty acid esters are esters of the formula 2: R 4 OR 5 formula 2: where R 4 is defined as follows: where R E =CH 3 or H and p =1-40 q =0-10 r 0-4 and the individual methylene (CH 2 )— (1), epoxy (CHOCH)— (2) and (CHCH 3 )— (3) groups may be present in any sequence and where the R 5 radical is described by the following formula 3: —(CH 2 ) S —R 6 formula 3: where s =0-50 R 6 =O—((CH 2 ) u —O) v —Y where u =2-5, v =2-5000 and Y =H or CH 3 or O—R 4 , where R 4 corresponds to the R 4 radical from formula 2.