Teijin Limited

Takao Chujo

Hisashi Hamano

Masanori Nishiyama

Yasuhiro Saeki

Tatsuya Ogawa

Kouhei Endou

Shigeru Shiozaki

Yukio Mitsuishi

Takeyuki Yokoyama

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,

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

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.

A biaxially oriented polyester film containing fine particles of insoluble inert substance, has a kinetic coefficient of friction of not more than 0.3, and has microscopic protrusions integrated thereto, said protrusion having an peak-to-valley height of not more than 1 micron mostly range of 0.2 to 0.5 micron. The film having improved slipperiness is useful as the base film of magnetic recording tape for a video tape recorder or a computer data storage.

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Sagamihara, Japan

Takao Chujo