Toray Industries, Inc.

Toyo Metallizing Co., Ltd.

Kazuo Okabe

Masahiko Motegi

Masaaki Ono

Yasuki Miura

Toshiya Yoshii

Takao Izasa

Satoru Hagiwara

Satoyuki Minami

Saburo Fujita

Katsumi Bokuta

Kazuyoshi Koide

Hiroyuki Morimoto

Ichiro Ishizuka

Ken-iti Sato

Tatuo Oikawa

Kimio Satoh

Polyester film for leader tapes, and a production process thereof

Polyester film and magnetic recording medium

Polyester films with a good slitting property and good slipping property contain, in first and second embodiments, at least 0.005% by weight of calcium carbonate particles. The particle size S.sub.c of the polyester crystals, crystal face orientation index X.sub.i and the difference .DELTA.n between the refractive indices in the machine direction and in the transverse direction of the polyester film have a specific relationship, or the internal haze H, face orientation coefficient f.sub.n or the difference .DELTA.n between the refractive indices in the machine direction and in the transverse direction have a specific relationship. By satisfying the specific relationship, a good slitting property and good slipping property are obtained. A third embodiment provides a polyester film containing at least 0.005% by weight of calcium carbonate particles, which has a specific center line average roughness Ra, face orientation coefficient f.sub.n, the difference .DELTA.n between the refractive indices in the machine direction and in the transverse direction, and F-5 value in the transverse direction. By these characteristics, a good slitting property, good slipping property and good shaving property are obtained.

Polyester film

Capacitor elements having an ultra thin dielectric layer are made by the method of cutting a metal-deposited polyethylene terephthalate laminated film into a predetermined width, and then separating a metal-deposited polyethylene terephthalate film from the cut laminated film and successively forming the separated metal-deposited polyethylene terephthalate film into a coil. The metal-deposited polyethylene terephthalate laminated film is composed of an oriented ultra thin polyethylene terephthalate film having a thickness of 0.2 to 2.0 .mu.m, on one surface of which a metal layer is formed by vacuum deposition and on the other surface of which a propylene copolymer support film is bonded with an adhesive force of 0.1 to 2.0 g/cm.

Method for making capacitor elements

A biaxially oriented polyester film is provided, which has a plurality of depressions and a plurality of protrusions on at least one surface thereof, in a configuration such that at least one protrusion exists within each depression or at least protrusion exists in the area where two or more depressions are contiguous to each other depressions having an area fraction of from 1.times.10.sup.-3 to 6.times.10.sup.-1. The polyester film is useful as a substrate for magnetic recording tapes such as audio and video tapes, and the resultant magnetic recording tapes are excellent in both electromagnetic transducing characteristics and runnability.

Biaxially oriented polyester film

Capacitor elements having an ultra thin dielectric layer are made by cutting a metal-deposited polyethylene terephthalate laminated film into a predetermined width, and then separating a metal-deposited polyethylene terephthalate film from the cut laminated film and successively forming the separated metal-deposited polyethylene terephthalate film into a coil. The metal-deposited polyethylene terephthalate laminated film is composed of an oriented ultra thin polyethylene terephthalate film having a thickness of 0.2 to 2.0 .mu.m, on one surface of which a metal layer is formed by vacuum deposition and on the other surface of which a support film is bonded with an adhesive force of 0.1 to 2.0 g/cm.

Metal-deposited laminated film and method for making capacitor elements

Easily-adhesive polyester film

The present invention relates to a method for holding a moving film comprising bringing each surface of a set of conductive rolls into contact with a front surface and a back surface of a moving film respectively, at least one of the surfaces of the set of rolls being constructed of an elastomer, and holding the moving film by the surfaces of the set of rolls while establishing a high electric potential difference between the set of rolls. The present invention provides a useful method for conveying or stretching the film at high speed without operational troubles, thereby providing a strong film free from scratches or foreign particles on the surface.

Method for holding a moving film

The present invention relates to a method for producing a thermoplastic polymeric sheet, wherein a molten thermoplastic polymer is extruded from an extrusion die in the form of a sheet onto a moving quenching member, with an electric potential difference being established between the surface of the moving quenching member and the extrusion die, whereby the polymer is caused to electrostatically solidify and adhered to the surface of the quenching member. The contact area of the polymeric sheet with the moving quenching member is held in an atmosphere of a gas which posesses better insulating properties than standard air. Thus the present invention provides a useful method that can produce, at higher speeds than conventional method, polymer sheets of high surface quality which avoid the operational problems encountered in the conventional methods.

Method for producing a thermoplastic polymeric sheet

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 base film for a magnetic recording tape is provided, which possesses an F-5 value of 9-15 Kg/mm.sup.2 as measured along both the longitudinal and transverse directions and in which the ratio of the average surface roughness to the particle size of included particles is 2.0.times.10.sup.-3 to 5.1.times.10.sup.-3. The average surface roughness is preferably 0.005-0.040 micron. The magnetic recording tape made therefrom exhibits an improved running property and an improved abrasion resistance as well as good surface characteristics.

Base film for magnetic recording tape with F-5 values of 9-15 Kg/mm.sup.2

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.

Growing community of inventors

Shiga, Japan

Kazuo Okabe