Teijin Limited

Tadashi Ono

Takeo Asai

Kinji Hasegawa

Yoji Murakami

A biaxially oriented polyester film comprising a copolyester which contains a lubricant having an average particle diameter of no greater than 2.5 .mu.m and has a melting point of from 210.degree. to 245.degree. C., the film having a plane orientation coefficient of from 0.10 to 0.16, a thermal shrinkage at 150.degree. C. of no higher than 10%, and a density of lower than 1.385 g/cm.sup.3, and optionally a refractive index in a direction of thickness of from 1.495 to 1.530 as well as a film plane refractive index of from 1.61 to 1.66 in all directions.

Polyester film for fabrication

A polyester film for metal sheet lamination processing which comprises a co-polyester containing a lubricant having an average particle diameter of 2.5 .mu.m or less and the co-polyester having a melting point of 210.degree. to 245.degree. C.; and wherein the refractive index in the direction of film thickness is 1.505 to 1.550, the refractive index in the direction of the film plane is 1.61 to 1.66 about all directions, subpeak by DSC is 150.degree. to 205.degree. C., and optionally, protrusions on the film surface satisfy the formula

Polyester film for laminated metal sheet drawing and processing

A biaxially oriented polyester film composed of an intimate mixture of an aromatic polyester, barium sulfate particles having an average particle diameter of 0.1 to 10 micrometers, and an alkali metal or alkaline earth metal salt of a higher fatty acid having 8 to 34 carbon atoms. The fatty acid metal salt has a melting point in the range of 120.degree. to 320.degree. C. The biaxially oriented polyester film has substantially no difference in surface properties such as roughness and the degree of gloss between its surface and back, and can be produced industrially advantageously with high producibility and excellent operability.

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Yokohama, Japan

Tadashi Ono