Teijin Limited

Yasuhiro Saeki

Masahiro Hosoi

Hisashi Hamano

Masami Etchu

Masanori Nishiyama

Ieyasu Kobayashi

Tatsuya Ogawa

Takao Chujo

Kouhei Endou

Ieyasu Kobayshi

Yasuhiko Saito

Takao Chuujou

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

Provided is a biaxially oriented, unidirectionally long polyethylene-2,6-naphthalenedicarboxylate film having the following characteristic properties;

Biaxially oriented, unidirectionally long

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

Polyethylene-2,6-naphthalenedicarboxylate film

Biaxially oriented unidirectionally long polyethylene-2,

There is provided a biaxially oriented polyester base film for a magnetic tape for use in a cassette for a digital audio tape recorder. The film has (a) a stress when the biaxially oriented polyester base film is extended in the longitudinal direction by 5% of at least 12 kg/mm.sup.2, (b) a residual extension in the longitudinal direction of 0.2% or less and a residual extension in the transverse direction of 0.3% or less, (c) a heat shrinkage in the longitudinal direction of 1.5% or less, (d) at least one surface of which has a surface roughness, Ra, of 25 nm or less, and (e) a film thickness of in the range of from 3 to 12 .mu.m. A magnetic tape for use in a cassette for a digital audio tape recorder is also provided.

Magnetic tape for use in cassette for digital audio tape recorder and

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 unidirectionally long, biaxially oriented film of polyethylene-2,6-naphthalenedicarboxylate:

Unidirectionally long biaxially oriented film of

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, (A) which is formed from polyethylene-2,6-naphthalenedicarboxylate containing 0.01 to 1% by weight of inert solid fine particles having an average particle size of 0.05 to 3 .mu.m, (B) which has a refractive index, in a film thickness direction, of at least 1.498, and (C) which has a Young's modulus, at least in one direction, of at least 700 kg/mm.sup.2 ; and a process for the production thereof. This film is useful as a magnetic recording medium, particularly as a base film excellent in abrasion resistance and tear resistance.

Biaxially oriented polyethylene-2,6-naphthalene-dicarboxylate film and

There is provided a biaxially oriented polyester base film for a magnetic tape for use in a cassette for a digital audio tape recorder. The film has (a) a stress when the biaxially oriented polyester base film is extended in the longitudinal direction by 5% of at least 12 kg/mm.sup.2, (b) a residual extension in the longitudinal direction of 0.2 % or less and a residual extension in the transverse direction of 0.3% or less, (c) a heat shrinkage in the longitudinal direction of 1.5% or less, (d) at least one surface of which has a surface roughness, Ra, of 25 nm or less, and (e) a film thickness of in the range of from 3 to 12 .mu. m. A magnetic tape for use in a cassette for a digital audio tape recorder is also provided.

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Sagamihara, Japan

Yasuhiro Saeki