| 摘要 |
<p>PURPOSE:To provide a polyester film made of terephthalate- or 2,6-naphtalate- polyester which has a specified birefringence index and haze and is improved in the coloring due to interference fringes. CONSTITUTION:The polyester film of this invention is made of terephthalate- or 2,6-naphtalate-polyester and has a birefringence index of 30X10<-3>-110X10<-3>, a thickness of 100mum, and a haze of <=5%. It is desirable to use a polyester whose transparency is not lowered and dimensions are not changed when heated, since the film is put in a heated condition at the time of manufacturing liquid crystal panels. It is desirable from the point of practical use that the coefficient of contraction is <=5% when held in a 150 deg.C atmosphere for 30min and the haze is <=5% at a thickness of 100mum. These conditions are achieved when a film of >=30X10<-3> in the degree of surface orientation is heat treated so that its mean refractive index becomes >=1.595 in the manufacturing process of the film.</p> |
