Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Patent
1989-01-06
1991-09-10
Thibodeau, Paul J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
428480, 428694, 428900, G11B 2300
Patent
active
050472780
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Polyester Film and Magnetic Recording Medium
1. Technical Field
The present invention relates to a polyester film. More particularly, it relates to polyester film exhibiting a good slipperiness. This polyester film is suitable as a base film of a magnetic recording medium comprising a ferromagnetic thin film as the recording layer, such as a magnetic tape.
2. Background Art
As the magnetic recording medium, especially the base film for a ferromagnetic thin film, there are known the following films.
(1) A composite film comprising a laminate comprised of a smooth thermoplastic film and a fine particulate-containing thermoplastic film, and a covering layer mainly comprised of a lubricant, which is formed on the outer surface of the fine particle-containing film layer (see, for example, Japanese Unexamined Patent Publication No. 58-153639).
(2) A polyester film having one surface rendered easily slippery by forming a coating in which a lubricant is dispersed, while the other surface is smooth (see, for example, Japanese Unexamined Patent Publication No. 57-162123).
(3) A composite polyester film comprising a laminate of two polyethylene terephthalate films having different intrinsic viscosities, and a ferromagnetic metal thin film formed on the surface of the layer having a lower intrinsic viscosity (see, for example Japanese Unexamined Patent Publication No. 57-200932).
(4) A smooth, biaxially oriented polyester film having fine protrusions formed thereon, in which the surface roughness, the Young's modulus in the longitudinal direction and the thermal shrinkage in the lateral direction are specified and a lubricant-containing coating is formed on one surface (see, for example, Japanese Unexamined Patent Publication No. 62-32048).
(5) A smooth polyester film having granular protrusions formed on one surface (see, for example, Japanese Unexamined Patent Publication No. 54-94574).
(6) A smooth polyester film having worm-like modules formed on both surfaces thereof (see, for example, Japanese Unexamined Patent Publication No. 56-10455).
(7) A polyester film having a discontinuous thin film layer composed mainly of a water-soluble polymer and having a thickness smaller than 50 nm, which is formed on at least one surface (see, for example, Japanese Unexamined Patent Publication No. 58-62826).
(8) A polyester film having a discontinuous thin film layer composed manly of a water-soluble polymer and a silane coupling agent and having a thickness smaller than 50 nm, which is formed on at least one surface (see, for example, Japanese Unexamined Patent Publication No. 58-65658).
(9) A polyester film having a discontinuous thin film layer composed mainly of a polymer blend containing an easily-bonding resin and fine particles having a particle diameter of 5 to 50 nm, and having a thickness smaller than 50 nm, which is formed on at least one surface (see, for example, Japanese Unexamined Patent Publication No. 60-180839).
(10) A polyester film having protrusions having a height of 10 to 200 nm at a density of 10,000 to 1,000,000 protrusions per mm.sup.2 on the average (see, for example, Japanese Unexamined Patent Publication No. 58-100221).
(11) A polyester film having protrusions having a height of 5 to 60 nm at a density of 1.times.10.sup.5 to 1.times.10.sup.8 protrusions per mm.sup.2 on the average (see, for example Japanese Unexamined Patent Publication No. 60-93636).
(12) A fine particle-containing polyester film in which surface protrusions are formed by the fine particles, and a discontinuous thin film layer composed mainly of a polar polymer and having a height smaller than the height of the surface protrusions is formed on the surface (see, for example, Japanese Unexamined Patent Publication No. 62-130848).
(13) A composite film comprising a laminate of a smooth thermoplastic film and a fine particle-containing thermoplastic film, in which a discontinuous film layer is formed on the outer surface of the smooth film layer and a coating layer composed mainly of a lubricant is formed on the outer surfa
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Izasa Takao
Okabe Kazuo
Ono Masaaki
Miller Austin R.
Thibodeau Paul J.
Toray Industries Inc.
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