Toyo Boseki Kabushiki Kaisha

Toyo Boseki Kabushiki Kaisha T/a Toyobo Co., Ltd.

Nippon Magphane Kabushiki Kaisha

Tsuyoshi Hongo

Katsuaki Kuze

Osamu Makimura

Yujiro Matsuyama

Masahiro Kobayashi

Kozo Maeda

Tadashi Okudaira

Keiichi Uno

Koichi Matsunami

Yasuhiro Nishino

Hikoichi Nagano

Takahito Miyagawa

Takeshi Ota

An oriented polyester film comprising ethylene terephthalate as the major repeating units, which comprises 0.01 to 1.0% by weight of silica particles and/or titanium dioxide particles having each an average particle size of 0.01 to 0.5.mu. and 0.005 to 1.0% by weight of calcium carbonate having an average particle size of 0.01 to 0.5.mu., which provides an oriented polyester film for the base film of video tape which has a flatness on the surface and has excellent slipperiness, abrasion resistance and running characteristics as well as excellent magnetic transducer characteristics.

Oriented polyester film

An oriented polyester film comprising ethylene terephthalate as the major repeating unit, which comprises particles of kaolinite and calcium carbonate uniformly dispersed therein, said kaolinite and said calcium carbonate having each an average particle size of 0.05 to 0.8 micron and being contained in such amounts as satisfying the following equations:

Oriented polyester film containing calcium carbonate and kaolinite

A shaped article having a refractive index of not less than 1.625 at least in one direction and possessing excellent physical properties and various uses, which can be prepared by stretching a molded product, which is made of a polymeric material comprising at least 80 mol% of the repeating units of the formula: ##STR1## and having an intrinsic viscosity of not less than 0.25 dl/g when measured in a mixture of phenol and sym.-tetrachloroethane in a weight ratio of 6 : 4 at 30.degree. C. and has a refractive index of not more than 1.610 at least in one direction, at a temperature of 120.degree. to 230.degree. C. with a stretch ratio of 2 to 20 in the same direction as the refractive index is measured, or by melt extruding the polymeric material at a temperature higher than 230.degree. C. and not higher than 360.degree. C. while or immediately followed by stretching with a deformation speed of not less than 20 times the speed of the melt extrusion.

Shaped article of polymers prepared from

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Otsu, Japan

Tsuyoshi Hongo