Teijin Limited

Hisashi Hamano

Yasuhiro Saeki

Masahiro Hosoi

Masanori Nishiyama

Masami Etchu

Takao Chujo

Hideo Katoh

Tatsuya Ogawa

Ieyasu Kobayashi

Kouhei Endou

Kinji Hasegawa

Ieyasu Kobayshi

Yoshihiro Noumi

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

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

A biaxially oriented film of a polyethylene-2,6-naphthalenedicarboxylate, which (A) has a Young's modulus of at least 800 kg/mm.sup.2 in the longitudinal direction and a Young's modulus of at least 500 kg/mm.sup.2 in the transverse direction, the Young's modulus in the longitudinal direction being greater than the Young's modulus in the transverse direction, (B) satisfies the following relationships between an elongation S.sub.M (%) in the longitudinal direction per a load of 1 kg/mm.sup.2 at 120.degree. C. and the Young's modulus Y.sub.M (kg/mm.sup.2) in the longitudinal direction,

Biaxially oriented film of polyethylene-2,6-naphthalenedicarboxylate

A biaxially oriented film of a polyethylene-2,6-naphthalenedicarboxylate, which (1) has a Young's modulus of at least 600 kg/mm.sup.2 in the transverse direction and a Young's modulus of at least 500 kg/mm.sup.2 in the longitudinal direction, the Young's modulus in the transverse direction being greater than the Young's modulus in the longitudinal direction, (2) satisfies the following relationships between an elongation S.sub.T (%) in the transverse direction per kg/mm.sup.2 of a load at 120.degree. C. and the Young's modulus Y.sub.T (kg/mm.sup.2) in the transverse direction,

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

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 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, (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.

An oriented polyester film (A) which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing a 4,4'-diphenyldicarboxylic acid component and having a heat of crystallization of 16 to 25.5 Joule/g, and (B) which is biaxially oriented; and an oriented polyester film (A') which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing of a glycol component derived from a compound represented by the following formula, ##STR1## wherein each of n and m is independently a positive number of 1 to 9 as an average, provided that m+n equals 2 to 9 as an average, and having a heat of crystallization of 6 to 20 Joule/g, and (B) which is biaxially oriented. These films are useful as a base film for a magnetic recording tape or as an electric insulation film.

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Sagamihara, Japan

Hisashi Hamano