Film and method for producing film

Abstract

A method for producing a film comprising feeding a composition comprising a crystalline thermoplastic resin having a temperature of higher than the crystallization temperature Tc of the resin to between a first nip-pressing surface and a second nip-pressing surface of a nip-pressing unit, and leading the composition to pass through the nip-pressing surfaces while the nip-pressing unit gives a pressure of from 5 to 1000 MPa to the composition, to thereby form the composition into a film continuously.

1 . A film in which orientation degree changes continuously in the thickness direction of the film and a part having a maximum orientation degree is inside the film. 
     
     
         2 . The film according to  claim 1 , comprising a crystalline thermoplastic resin in an amount of at least 60% by mass wherein composition is uniform in the plane and in the thickness direction of the film, both sides of the film have a mirror surface, and the film has an elongation at break at 25° C. of at least 150% and a yield stress of at least 40 MPa. 
     
     
         3 . The film according to  claim 1 , having a thickness fluctuation of at most 3%. 
     
     
         4 . The film according to  claim 2 , wherein the crystalline thermoplastic resin is a polyester. 
     
     
         5 . The film according to  claim 4 , wherein the polyester is polyethylene terephthalate or polyethylene naphthalate. 
     
     
         6 . The film according to  claim 1 , which has a polarization property.