Diafoil Company, Ltd.

Diafoil Hoechst Company, Limited

Mitsubishi Chemical Industries Limited

Diafoil Hoescht Company, Limited

Daifoil Company, Limited

Shigeo Utsumi

Yujiro Fukuda

Kichinojo Tomitaka

Kichinojyo Tomitaka

Masashi Inagaki

Tateo Kanesaki

Tomoyuki Kotani

Yuko Watanuki

Toshifumi Takisawa

Masumi Koizumi

Shigeyuki Watanabe

Kazuo Endo

Seiichi Nozawa

Narihiro Masuda

Chikakazu Kawaguchi

Yoshinori Sato

Satoshi Otonari

Yoshio Meguro

Masahiko Fujimoto

Kenji Kato

Shinobu Suzuki

Nobuyasu Shudo

Kazuyuki Akatsu

Michio Nakata

Takashi Kagiyama

Takatoshi Miki

Koichiro Ikushima

Norio Okumura

Disclosed herein is a polyethylene naphthalate multilayered film for a high density magnetic recording medium comprising:

Polyethylene naphthalate multilayered film for high density magnetic

A laminated polyester film for a magnetic tape, which film comprises a layer of a crystalline polyester (A) and a layer of a polyester (B) which is laminated on at least one surface of the layer of the polyester (A) and has a melting point lower than that of the polyester (A), and which film has a Young's modulus of at least 600 kg/mm.sup.2 in both longitudinal and transverse directions, which film is suitable as a base film of a video tape.

Laminated polyester film for magnetic tape

A polyester film prepared through a lamination of at least two layers by coextrusion, wherein one of exposed surfaces (surface A) has a center line average roughness of from 0.002 to 0.015 .mu.m, a polyester layer forming the other of the exposed surfaces (surface B) has a lower melting point than a polyester forming the surface A, and the surface B has a degree of planar orientation of not larger than 0.100, which can be used as a base film for magnetic recording tape having no back coating.

Laminated polyester film for magnetic tape having specific surface

A multilayered polyester film for high-density magnetic discs, comprising a layer of polyester (A) and a layer of polyester (B) having a thickness of not more than 3 .mu.m, being laminated on at least one side of the layer of polyester (A) and having specific surface characteristics.

Polyester multilayered film for high-density magnetic disc

The present invention relates to a process for producing a biaxially oriented polyester film. The process is carried out using the following steps: (a) stretching an amorphous film substantially comprising polyethylene terephthalate 1.2 to 4.0 times in the machine direction by single-stage or multi-stage process to obtain a film having an index of birefringence of 1.times.10.sup.-3 to 2.5.times.10.sup.-2 ; (b) stretching the thus obtained film 1.1 to 3.5 times in the machine direction by single-stage or multi-stage process of 3.0.times.10.sup.-2 to 8.0.times.10.sup.-2 without cooling the film to the glass transition temperature thereof or below; (c) cooling the thus obtained film to the glass transition temperature thereof or below; (d) heating the thus obtained film to the glass transition temperature or higher and stretching the film in the machine direction by a single-stage or multi-stage process at a stretching ratio which brings the overall stretching ratio of 4.0 to 9.0 times; and (e) stretching the thus obtained film at least 3.2 times in the transverse direction. According to the method of the present invention, a biaxially oriented polyester film which is excellent in thickness uniformity and flat and slippery properties can be easily produced and high-speed production thereof is possible, therefore, the present invention has a great industrial value.

Process for producing biaxially oriented polyester film

A biaxially oriented polyester film simultaneously satisfying the following formulas (I) to (III):

Low-shrinkage polyester film and preparation thereof

A shrinkable copolyester film having shrinkage of not less than 30% in the direction (main shrink direction) of either the machine direction or the transverse direction after 5 min treatment in an air oven at 100.degree. C., a shrinkage of not more than 20% in the other direction perpendicular to the main shrink direction after 5 min treatment in an air oven at 100.degree. C., an initial shrinkage stress (F.sub.0) of not more than 2000 g/mm.sup.2 in the main shrink direction during the course of 5 sec after dipped in a silicone oil of 75.degree. C., a shrinkage stress (F.sub.20) of not less than (F.sub.0 -100) g/mm.sup.2, after 20 sec dipping in a silicone oil at 75.degree. C., and a glass transition temperature of 35.degree. to 65.degree. C., is disclosed. The shrinkable copolyester film of the present invention is excellent in shrinkage properties, i.e., substantially free from wrinkles, distortion of film and uneven shrinkage, and is suitable for a shrinkable label for a PET bottle, etc.

Shrinkable copolyester film

A polyester film suitable for a base of high density magnetic recording medium containing barium ferrite as a magnetic material characterized in that the centerline average roughness (Ra) is not more than 0.025 .mu.m and the F.sub.5 value in the longitudinal direction is not less than 14 kg/mm.sup.2 is disclosed wherein the polyester film exhibit excellent better durability when used with barium ferrite as a magnetic material.

Polyester film for high density magnetic recording medium

Disclosed herein is a polyester film containing specific fine spherical silica particles. The film of the present invention is especially suitable as a base film for a magnetic recording medium or dielectric for a capacitor. The films of the present invention have the markedly improved properties such as surface properties, electromagnetic properties, electrical properties, etc. due to the excellent dispersibliity of the particles in the film.

Polyester films, magnetic recording media and film capacitors produced

A biaxially stretched polyester film which satisfies the following equations (1) to (4):

Process of making a biaxially stretched polyester film and biaxially

A shrinkable polyester film having a sufficient shrinkage, a sufficient resistance to solvent for printing ink, a shrinking property not to cause wrinkles, a warm water resistance sufficient for preventing wrinkles, slack and whitening is disclosed herein. The shrinkable polyester film of the present invention may be used as labels for various vessels such as glass bottle, heat-resistant PET bottle and non heat-resistant PET bottle.

Shrinkable polyester film

A heat-resistant film or sheet produced by melt extruding polyether ketone having an intrinsic viscosity of at least 0.4 dl/g, which is obtained by heat treating an unstretched film or sheet which comprises (i) heat-treating to crystallization being not more than 60%, or (ii) uni- or biaxially stretching under specific conditions to an extent in which a stress at 5% elongation in the stretched direction is at least 13 kg/mm.sup.2 ; an initial elastic modulus in the stretched direction is at least 600 kg/mm.sup.2 ; and thermal shrinkages in a lengthwise direction and its vertical direction are not more than 4%. The film or sheet of the present invention is excellent in such properties as heat resistance, mechanical strength and the like, and is suitable for use as a substrate for magnetic recording or electric insulation.

Heat-resistant film or sheet

Disclosed herein is a transfer material for use with a printer, which comprises a biaxially oriented polyester film which simultaneously satisfies the following expressions (I) to (III):

Transfer material for use with printer

A biaxially oriented polyester film for floppy disks which has an in-plane thermal expansion coefficient (.alpha..sub..gamma.) of (1.7.+-.0.8).times.10.sup.-5 /.degree.C. and a shrinkage of not more than 0.03% after 72-hour treatment under the conditions of 60.degree. C. and 80% RH, and which simultaneously satisfies the following relationships (1) to (6):

Biaxially oriented polyester film for floppy disk

Disclosed herein is a polyethylene naphthalate film for high-density magnetic recording media of floppy disk which has little anisotropy, high mechanical strength and good dimensional stability, and which scarcely causes a drop out and has good productivity.

Growing community of inventors

Yokohama, Japan

Shigeo Utsumi