Toray Industries, Inc.

Masaaki Ono

Kazuo Okabe

Masahiko Motegi

Katsuya Okamoto

Yasuki Miura

Kazuyoshi Fukata

Masahiro Yagi

Toshihiro Tsuzuki

Tsutomu Morimoto

Toshiaki Ueda

Takao Izasa

Akihiko Nagahama

Tohru Morita

Tadashi Harada

A polyester film for recording medium, having one major surface thereof provided with a coating layer containing fine particles of 5 to 60 nm diameter and an organic compound, wherein the number of fine surface projections existing on the surface of the coating layer is in the range of 3 million to 100 million/mm, and the number of surface defects of 120 nm or greater height attributed to foreign matter contained in the film is 30/100 cmor less, and wherein the polyester contains a titanium compound substantially not having any particle diameter. Thus, there are provided a magnetic recording tape for digital data recording that can reduce dropouts and excels in durability, and further provided a polyester film that is suitable as a base film thereof.

Polyester film for recording medium and magnetic recording tape

A polyester film for magnetic recording media includes a coating layer containing fine particles and organic compounds formed on surface A at one side of the polyester film, and fine surface protrusions formed at a density of 3&#xd7;10to 1&#xd7;10protrusions/mmon surface A. The polyester film satisfies at least one of the following conditions: (a) the mean diameter of the fine surface protrusions is in the range of 5 to 60 nm, and, among the fine surface protrusions, the density of fine surface protrusions with a height of 20 nm or more is 3,000 protrusions/mm, and (b) the mean diameter of the fine surface protrusions is in the range of 5 to 100 nm, the mean height of the fine surface protrusions is in the range of 5 to 30 nm, and the degree of cohesion of the fine surface protrusion is less than 15%.

Polyester film for magnetic recording media, magnetic recording tape and digital recorder

A polyester film comprising a coating layer which comprises organic fine particles and organic compounds on one-side surface of the polyester film, the weight ratio of the organic fine particles to the organic compounds in the coating is 1:0.2 to 1:5.0, the diameters of surface protrusions on the coating surface are 20 to 60 nm, the number of surface protrusions on the surface of the coating layer is 3 million to 100 million per square millimeter, and the surface roughness Ra of the coating surface is 0.5 to 1.9 nm, is suitable as a base film of a recording medium having excellent image quality and excellent durability without shaving an MR head.

Polyester film and recording tape

Disclosed is a base film that has excellent electromagnetic conversion property over the entire length from a roll core portion to a surface portion of the film product and that is suitable for the production of digital videotapes with reduced dropouts. A polyester film for a magnetic recording medium includes at least a polyester layer A and a polyester layer B laminated. A center-line surface average roughness (SRa value) of a layer A-side surface of the film is 2 nm to 4 nm, and a ten-point average surface roughness (SRz value) of the layer A-side surface is 10 nm to 40 nm. The layer B contains a fine particle &agr; whose average particle size is at least 50 nm and less than 250 nm, and a fine particle &bgr; whose average particle size is at least 250 nm and less than 500 nm. The content of the fine particle &agr; in the layer B is 0.1 wt. % to 1.0 wt. %. The content of the fine particle &bgr; in the layer B is 0.01 wt. % to 0.10 wt. %. A magnetic recording tape is formed by providing a ferromagnetic metal thin film on a layer A-side surface of the polyester film.

Polyester film for magnetic recording medium, and magnetic recording tape

A method for storing a polyester film for a magnetic recording medium, characterized in that a polyester film for a magnetic recording medium with a surface roughness Ra of 6 nm or less on the surface A on one side is stored substantially in a storing atmosphere having a storing temperature kept in a range from 10.degree. C. to 35.degree. C. The polyester film stored according to this storing method is used as a base film for producing magnetic tapes.

Method for storing a polyester film for a magnetic recording medium, and

Composite polyester film

Polyester film and magnetic recording medium

A laminated film for a super-high density magnetic recording medium, which comprises (A) a layer composed of a thermoplastic resin and (B) a layer of a thermoplastic resin containing fine particles therein. In this laminated film, the outer surface of the layer (A) has a surface roughness of less than 0.005.mu. as expressed as the Ra value, and the outer surface of the layer (B) has a surface roughness of 0.005 to 0.040.mu. as expressed as the Ra value. The outer surface of the layer (B) has either (i) a plurality of depressions and a plurality of protrusions, which are formed thereon in a configuration such that at least one protrusion exists within each depression or at least one protrusion exists in the area where two or more depressions are contiguous to each other, or (ii) protrusions on a flat plane and a covering layer (C) composed of a lubricant, which is formed on the surface of the layer (B). This covering layer (C) may be formed on the surface having the above-mentioned depressions and protrusions. The covering layer (C) is a continuous film layer or a discontinuous film layer formed of worm-like nodules. When a ferromagnetic metal thin film is formed on the surface of the layer (A) by vacuum evaporation and a protective film layer is formed on this thin film, there is obtained a vacuum-deposited video tape excellent in running properties and electromagnetic transformation performance. In this vacuum-deposited video tape, the transfer of the surface configuration due to the coarseness of the running surface can be prevented.

Laminated film and magnetic recording medium made therewith

A thermoplastic resin base film for a magnetic recording medium including a thermoplastic resin film and a discontinuous film adhering closely to at least one surface of the thermoplastic resin film. The discontinuous film has a thickness of not larger than 500 angstroms and is composed of a polymer blend containing fine particles. The polymer blend comprises a water-soluble polyester copolymer and a water-soluble polymer having at least one hydroxyl group in the recurring unit thereof. Fine protrusions are formed on the discontinuous film due to the presence of the fine particles therein. A magnetic recording medium using the base film is suitable for high density magnetic recording and has extremely excellent durability to repeated use.

Thermoplastic resin base film for magnetic recording medium

A laminated film comprising (A) a layer composed of a thermoplastic resin and (B) a layer composed of a thermoplastic resin containing fine particles therein, wherein a discontinuous skin having a height of 50 to 1,000 .ANG. is formed on the outer surface of the layer (A) and the outer surface of the layer (B) has a surface Ra value of 0.005 to 0.040.mu.. The laminated film is very valuable as a base film of a magnetic recording tape having a ferromagnetic metal thin film formed on the surface of the layer (A), especially a video tape, because it has good running properties and is excellent in electromagnetic transformation performance.

Disclosed is a polyester film for a magnetic recording medium, which is comprised of a polyester film, a discontinuous film layer or layers adhering closely to one surface or both the surfaces of the polyester film, and fine particles present in the discontinuous film layer or layers and on the or each surface of the discontinuous film layer or layers, or on the exposed surface or surfaces of the polyester film in the portions where the discontinuous film layer or layers are not present. The discontinuous film layer or layers have a thickness of not larger than 500 angstroms and are composed mainly of a water-soluble polymer.

Polyester film for magnetic recording medium

A super high density magnetic recording medium is provided, which comprises a polyester film and a discontinuous film formed on at least one surface of the polyester film. The discontinuous film has a thickness of smaller than 500 angstroms and is composed mainly of a water-soluble polymer, a silane coupling agent, and if desired, a silicone resin. A high density magnetic recording medium is also provided, which comprises a ferromagnetic metal thin film formed on the discontinuous film layer of the polyester base film. The polyester base film is especially suitable for formation of a metallized video tape, and this tape is excellent in the slip characteristics and abrasion resistance and advantageous in that noises and drop-out are reduced.

Super high density magnetic recording medium

A slippery and smooth-surfaced polyester film, at least one surface of which is covered with worm-like nodules, useful as a base film for high recording density magnetic tape.

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Anpachi-gun, Japan

Masaaki Ono