The film of claim 15 wherein R13 is from 45 to 85 mol % of the acid component of the copolyester, R14 is from 55 to 15 mol % of the acid component of the copolyester, R11 and R12 are derivatives of 1,4-butanediol, R13 is a derivative of adipic acid or an ester forming derivative thereof, and R14 is a derivative of 1,4-terephthalic acid or an ester forming derivative thereof, having a tangent modul