Unitika Ltd.

Yoshiaki Kozuka

Eiji Y Yamamoto

Minoru Kishida

Kenji Yasue

Tsuneo Tamura

Katsuyuki Touma

Akira Menjyu

Shouji Nishimoto

Katsuyuki Toma

Hiroyuki Matsuda

Hayami Ohnishi

A surface-roughened film and methods for fabricating same. The film has good transparency/exceptional clarity and high lubricity so that it is useful for a photoengraving material, label, packaging film, magnetic recording film, or clear film. The film has a composition including thermoplastic polyester resin (a) and a thermoplastic resin (b), such as an amorphous nylon, having glass transition temperature preferably 10.degree. C. higher than that of the thermoplastic polyester resin (a) and a critical surface tension more than 0.1 dyne/cm different from that of the thermoplastic polyester resin (a). Resin (b) further has a melt viscosity, at a temperature of 280.degree. C. and shear rate of 10.sup.2 sec.sup.-1, in the range of 500 to 50,000 poise. One or more particulate inert inorganic compound may be added and the film may be laminated to layers of other polymers with the film of the foregoing composition on at least one surface thereof. On the film surface, microprotuberances cored with the thermoplastic resin (b) are formed. In addition, there are also provided methods for fabricating the surface-roughened film including drawing the film in at least one direction by a factor of at least one and one-half at a temperature between Tg of (a) and Tg of (b).

Surface-roughened polyester film

A light-weight polyester film which comprises (A) from 50 to 95% by weight of a crystalline polyester resin and (B) from 5 to 50% by weight of a maleimide copolymer, said maleimide copolymer being dispersed in the film in the form of particles having diameters of from 0.1 to 20 .mu.m and fine voids being present in the film, and which has an apparent specific gravity of from 0.3 to 1.1, wherein said maleimide copolymer comprises from 30 to 50 mol % of a maleimide monomer group, from 30 to 70 mol % of an aromatic vinyl monomer group, from 0 to 40 mol % of an unsaturated dicarboxylic anhydride monomer group and from 0 to 40 mol % of other copolymerizable monomer group, and said maleimide copolymer has a glass transition temperature higher by at least 10.degree. C. than the crystalline polyester resin.

Light-weight polyester film and process for its production

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Uji, Japan

Yoshiaki Kozuka