Toray Industries, Inc.

Masahiko Motegi

Kazuo Okabe

Masaaki Ono

Yasuki Miura

Saburo Fujita

Satoyuki Minami

Kazuhiro Tanaka

Atsuhiko Soda

Masakazu Inoue

Ikukazu Kimata

Satoru Okamoto

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

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.

Super high density magnetic recording medium

The present invention relates to a process for preparing a highly tensilized polyester film that has enhanced mechanical properties in both longitudinal and transverse directions. The process involves the simultaneous machine and transverse direction stretching and subsequent heat setting of a film that has already been highly stretched in the machine and transverse directions individually. During the simultaneous stretching process both the temperature and rate of linear movement of the film are controlled.

Method of manufacturing polyester films

The present invention relates to a process for preparing a polyester film which has not only uniaxially enhanced mechanical properties but also biaxially enhanced mechanical properties. The process involves heat-setting a biaxially oriented polyester film at a temperature above that used for the machine and transverse direction stretching and above that used for the machine direction re-stretching, but at least 10.degree. C. below the melting point of the polyester, then re-stretching the film in both the machine and transverse directions, and re-heat-setting the film.

Method for manufacturing polyester films

A polymeric-shaped article for use as film such as microfilm, overhead projector film, reprographic film, layout base, etc., and for insulating capacitors, which has excellent transparent, slippery and dielectric properties, and the process for realizing the same, the polymeric-shaped article having a polar surface such as polyester, polyamide, polyolefins, polyimide, polyvinyl alcohol, polyethylene terephthalate or polyethylene-2,6-naphthalate, to which is bonded a multiplicity of nodules of TiO.sub.2, each nodule having a diameter in the range of from about 0.01 to about 10 .mu.m, a height or thickness in the range of from about 0.01 to about 0.5 .mu.m, and an area ratio of TiO.sub.2 to total surface of from about 0.01 to about 50%; and the process being that of exposing at least one side of the surface of the article to water vapor and bringing a tetrafunctional titanium compound such as TiCl.sub.4, tetraethyltitanate, tetraisopropyltitanate, tetra-n-butyltitanate or mixture thereof, into contact with the surface, the processing temperature being at least greater than 30.degree. C.

Polymeric-shaped article

Polyester film for magnetic tape including discrete polyester particles containing lithium, calcium and phosphorus, said particles having an average size in the range from 0.1 to 3.0 .mu.m and inert pigments having an average size of 1.0 to 10.0 .mu.m. Magnetic tape from this film has improved abrasion resistance and reduced the occurrence of 'drop out'.

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Hikone, Japan

Masahiko Motegi