Lidding structure based on aromatic polyester film, extrusion-coated with a sealable/peelable copolyester layer

A heat-sealable, peelable multilayer polyester film, comprising a heat-sealable layer and a polyester substrate layer, wherein:

• i. the heat-sealable layer comprises a polyester of at least one aromatic dicarboxylic acid, at least one aliphatic dicarboxylic acid and at least one aliphatic diol;
• ii. a sample of the heat-sealable layer has a heat of fusion of in a range of about 0.32 J/g to about 0.96 J/g measured on a differential scanning calorimeter upon second heating of the sample at a controlled heating rate of 10° C./min after the sample has undergone a first heating at 10° C./min going from 23° C. to 200° C. in order to completely melt the sample and then cooling back to 23° C. by exposing the sample to ambient conditions, and the heat-sealable layer has a glass transition temperature lower than 80° F. and a melting point 250-320° F.;
• iii. the heat-sealable layer attains a seal strength of 2.5 lb/in or higher at a sealing temperature range between 250-420° F.;
• and
• iv. the heat-sealable layer has an amorphous character that enables the heat-sealable layer to flow and seal onto the polyester substrate layer even below the melting of the heat-sealable layer.