Patent ID: 7753164

Claim:
A thermoformed diaphragm made of cast of polyarylate film, at least comprising one polyarylate having a structural unit of the formula: wherein each of R 1 , R 2 , R 3 , and R 4 , independently of the others, is hydrogen, C 1-4 -alkyl, C 1-4 -alkoxy, or halogen, and each of R 5 and R 6 , independently of the other, is hydrogen, C 1-4 -alkyl, C 1-4 -alkoxy, phenyl, or halogen, where the cast polyarylate films are produced from polyarylate cast solutions which contain: (i) a nonionic polyol surfactant selected from the group consisting of poly(ethylene glycol), poly(propylene glycol) and poly(tetramethylene oxide), utilized as homopolymer, copolymer, block polymer, or a mixture thereof, dissolved as a mixture with a dye, or (ii) said nonionic polyol surfactant, each of (i) and (ii) can comprise other additives.