Diaphragms made of cast polyarylate films

Abstract

Thermoformed diaphragms made of cast polyarylate films, having at least one polyarylate (PAR) having a structural unit of the formula (I): where 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. The thermoformed diaphragms made of cast PAR films can be used as acoustic transducers, preferably as microphone diaphragms or loudspeaker diaphragms. The cast PAR films can be used for producing these diaphragms, and the PAR casting solutions can be used for producing the cast PAR films. There are processes for producing thermoformed diaphragms made of cast PAR films.

1 - 13 . (canceled) 
     
     
         14 . A process for producing cast polyarylate films composed of polyarylate of the formula: 
       
         
           
           
               
               
           
         
       
       where each of R 1 , R 2 , R 3 , and R 4 , independently of the others, is hydrogen, C 1-4 -alkl, 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, comprising applying a polyarylate casting solution to a substrate to form a film, peeling the polyarylate film away from this substrate after a predrying period and then fully drying the polyarylate film. 
     
     
         15 . The process as claimed in  claim 14 , wherein the polyarylate casting solution is applied to a continuous substrate. 
     
     
         16 . The process as claimed in  claim 14 , wherein the polyarylate casting solution is applied to an intermediate film conducted on the substrate and, after a predrying period, is peeled away together with the intermediate film from this substrate, and is then fully dried. 
     
     
         17 . The process as claimed in  claim 16 , wherein the intermediate film used comprises a polyethylene terephthalate film. 
     
     
         18 . The process as claimed in  claim 17 , wherein the average thickness of the cast polyarylate films after final drying produced in this manner, is from 5 to 200 μm. 
     
     
         19 . The process as claimed in  claim 14  wherein a solution-application or lamination process is utilized to coat the cast polyarylate film. 
     
     
         20 . The process as claimed in  claim 15 , wherein the polyarylate casting solutions are applied to a continuous substrate that is a steel belt that is matt or polished on one side, or that is a polished or matt stainless steel roll of circumference from 5 to 25 m. 
     
     
         21 . The process as claimed in  claim 17 , wherein the average thickness of the cast polyarylate films after final drying, produced in this manner, is from 5 to 200 μm. 
     
     
         22 . A process for producing cast polyarylate films comprising at least one polyarylate having a structural unit of the formula: 
       
         
           
           
               
               
           
         
       
       where 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, comprising applying a polyarylate casting solution to a substrate to form a film, peeling the polyarylate film away from this substrate after a predrying period, and then fully drying the polyarylate film.