Teijin Limited

Masami Etchu

Masahiro Hosoi

Yasuhiro Saeki

Hisashi Hamano

Hirofumi Murooka

Shigeyoshi Masuda

Ieyasu Kobayashi

Masanori Nishiyama

Sumio Kato

Makoto Handa

Tatsuya Ogawa

Kei Mizutani

Norio Takagi

Yasuhiko Saito

Takao Chuujou

Takao Yamaguchi

Yoshimichi Hase

A biaxially oriented polyethylene-2,6-naphthalate film suitable for producing magnetic recording media wherein the film has a Young's modulus of at least 550 kg/mm.sup.2 in the longitudinal direction and a Young's modulus of at least 800 kg/mm.sup.2 in the transverse direction with the Young's modulus in the transverse direction being greater than the Young's modulus in the longitudinal direction by more than 200 kg/mm.sup.2 ; a surface roughness Ra of 1-12 nm; and low heat shrinkage. The film also contains 0.005-2% by weight inorganic or organic fine particles.

Biaxially oriented, polyethylene-2, 6-naphthalate film and magnetic tape

A biaxially oriented polyester film which has excellent resistances to dry heat deterioration and wet heat deterioration, which can withstand the use in an atmosphere of relatively high moisture content, and which is useful, for example, as an electrical insulating film, a film for transparent electrode, a film for absorption of electromagnetic wave (e.g. a film used as an inspection window of microwave oven) and a reflection film. This polyester contains �ethylene-2,6-naphthalenedicarboxylate as the main recurring unit.! 99.5 to 95 mole % of ethylene-2,6-naphthalenedicarboxylate and 0.5 to 5 mole % of ethylene-2,7-naphthalenedicarboxylate and has a density of 1.355 to 1.370 g/cm.sup.3 and an intrinsic viscosity of 0.62 to 0.90. The polyester film has an amount of terminal carboxyl in the polyester of 40 eg/10.sup.6 g or less and an amount of oligomers of 2.0 mg/m.sup.2 film or less.

Biaxially oriented polyester film

A magnetic recording tape or disk formed from a biaxially oriented laminated polyester base film which comprises a layer (A) of a polyester consisting essentially of 2,6-naphthalenedicarboxylic acid and ethylene glycol components and a layer (B) of a copolyester consisting essentially of 2,6-naphthalenedicarboxylic acid, ethylene glycol, and diethylene glycol components, wherein the copolyester contains 1-5% by weight of the diethylene glycol component, based on the weight of the layer (B) copolyester, layer (B) being present on one or both surfaces of layer (A).

Laminated polyester film for magnetic recording medium

A biaxially oriented polyethylene-2,6-naphthalate film suitable for producing magnetic recording media wherein the film has a Young's modulus of at least 550 kg/mm.sup.2 in the longitudinal direction and a Young's modulus of at least 800 kg/mm.sup.2 in the transverse direction with the Young's modulus in the transverse direction being greater than the Young's modulus in the longitudinal direction by more than 230 kg/mm.sub.2, a surface roughness Ra of 1-12 nm; and low heat shrinkage. The film also contains 0.005-2% by weight inorganic or organic fine particles.

Biaxially oriented polyethylene-2,6-naphthalate film and magnetic tape

A biaxially oriented laminated polyester film comprises a polyester substrate layer (A) and a polyester surface layer (B) containing inert particles wherein the polyester surface layer (B) has a thickness of 0.2 to 3 .mu.m with the thickness of the polyester surface layer (B) varying along the film width direction so that the surface layer (B) is thicker at the edges of the film and thinner at the center of the film. The thickness of the surface layer (B) also satisfies specified relationships based on surface layer thickness, birefringence, and orientation angle values at two different points along the film width direction in order to obtain a film whose surface layer (B) has a uniform surface roughness in the film width direction wherein the polyester surface layer (B) has a surface roughness Ra of 3 to 40 nm and a surface roughness Ra fluctuation ratio of 5% or less when measured along a distance of 500 mm in the film width direction. The laminated film can be slit and easily wound into pancake rolls.

Biaxially oriented laminated polyester film

A biaxially oriented laminated polyester film comprising:

A biaxially oriented laminated polyester film comprising a first thin polyester layer containing large-diameter inert particles and small-diameter inert particles; a second polyester layer containing large-diameter inert particles; and a third thin polyester layer containing large-diameter inert particles and small-diameter inert particles, the biaxially oriented laminated polyester film satisfying the following expression (1), ##EQU1## wherein: W.sub.1 is the content (wt. %) of the large-diameter inert particles in the first thin polyester layer, W.sub.2 is the content (wt. %) of the large-diameter inert particles in the second polyester layer, D.sub.13 is a total of the thickness (.mu.m) of the first thin polyester layer and the thickness (.mu.m) of the third thin polyester layer, and D.sub.2 is the thickness (.mu.m) of the second polyester layer. This film is useful as a base film for a magnetic medium.

Biaxially oriented laminated polyester film and magnetic recording

Biaxially oriented film of polyethylene-2,6-naphtalenedicarboxylate for

A biaxially oriented laminated polyester film comprising a first polyester surface layer having (a1) a central line average roughness R.sub.aA of 1 to 7.9 nm, (b1) a 10-points average roughness R.sub.ZA of 15 to 400 nm and (c1) an R.sub.ZA /R.sub.aA ratio of 11-51, and a second polyester surface layer having (a2) a central line average roughness R.sub.aB which is greater than R.sub.aA and is 5 to 40 nm, (b2) a 10-points average roughness R.sub.ZB of 75 to 600 nm and (c2) an R.sub.ZB /R.sub.aB ratio of 20 or less, and satisfying the relationship between the first polyester surface layer and the second polyester surface layer, which is represented by the following expressions,

Biaxially oriented laminated polyester film having different size

A laminated polyester film for use in a magnetic recording medium, which comprises (A) a first layer of a first polyester which contains at least 95 mol %, based on the total content of its dicarboxylic acid components, of a 2,6-naphthalenedicarboxylic acid component and whose main recurring unit is composed of ethylene-2,6-naphthalenedicarboxylate, and (B) a second layer of a second polyester containing 93 to 99 mol %, based on the total content of its recurring units, of an ethylene-2,6-naphthalenedicarboxylate recurring unit. The second layer is laminated on at least one surface of two surfaces of the above first layer.

Laminated polyester film and magnetic recording medium using it as base

A magnetic recording tape, in particular a VTR tape, comprising;

Magnetic recording tape comprising a polyethylene-2,6-napthalate

A biaxially oriented, unidirectionally long polyethylene-2,6-naphthalate film, (A) which contains

Biaxially oriented, unidirectionally long polyethylene-2,6-naphthalate

A biaxially oriented polyester film for magnetic recording media, which comprises:

Biaxially oriented polyester film for magnetic recording media

A magnetic tape for audio cassettes wherein a magnetic layer is provided on base film characterized in that the a base film, is biaxially oriented polyethylene-2,6-naphthalate film having a Young's modulus in the longitudinal direction of 850 Kg/mm.sup.2 or more, a Young's modulus in the transverse direction of 550 Kg/mm.sup.2 or more a surface roughness Ra in the range of 0.015 to 0.040 .mu.m, and a thermal shrinkage rate in the longitudinal direction of 0.3% or less in a case where it was held at a temperature of 100.degree. C. for 1 hour. A magnetic tape for audio cassettes is provided which is capable of long-time recording and wherein deterioration of magnetic characteristics does not easily occur in use, storage and the like at a high temperature, for example in the open during summer or in cars, compared to conventional ones.

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Yokohama, Japan

Masami Etchu