Fuji Photo Film Company, Limited

Tadashi Ishikuro

Masaaki Fujiyama

Ryuji Shirahata

Takahito Miyoshi

Shinobu Iida

Yasuo Nishikawa

Hideaki Kosha

Kunihiko Honda

Haruo Masuda

Masataka Ohta

Kouiti Mochizuki

A magnetic layer is overlaid on the front surface of a substrate, and a backing layer is overlaid on the back surface of the substrate. The backing layer is formed by the application of a coating composition, which contains inorganic grains and a binder, to the back surface of the substrate. The coating composition is prepared from the steps of kneading a mixture of the inorganic grains and the binder, in which the weight ratio of the inorganic grains to the binder falls within the range of 100:10 to 100:30, in a two-shaft continuous kneading and mixing machine. A dilution kneading process is then carried out on a mixture of the kneaded mixture, which results from the kneading process, and an organic solvent in a two-shaft continuous kneading and mixing machine. Thereafter a dispersion process is carried out on the diluted mixture, which results from the dilution kneading process.

Method for making magnetic recording media by kneading, dilution

A magnetic recording medium comprising a support having provided on one surface thereof a magnetic layer, and on the opposite surface thereof a backing layer comprising nonmagnetic particles dispersed in a binder, wherein the binder in the backing layer comprises a vinyl chloride-vinyl acetate copolymer of from 50 to 80 parts by weight, a polyester resin of from 1 to 40 parts by weight, and a polyisocyanate of from 10 to 49 parts by weight, per 100 parts by weight of the binder.

Magnetic recording medium and method for preparing the same

A process for preparing a magnetic recording medium by the steps of (a) forming a magnetic layer on one surface of a non-magnetic support and (b) homogeneously dispersing an .alpha.-Al.sub.2 O.sub.3 power having an average particle size of about 0.1 .mu.m or less in a solvent containing a small amount of binder to form a dispersion, mixing the thus-prepared dispersion with a binder to provide a coating composition, and applying the coating composition to the opposite surface of the nonmagnetic support to form a backing layer. The magnetic recording medium has improved wear resistance, a low friction coefficient and excellent electromagnetic properties.

Process for preparing a backing layer of a magnetic recording medium

A method for preparing a magnetic recording medium comprising a non-magnetic support having thereon a magnetic layer comprised of ferromagnetic particles of hexagonal crystalline ferrite which comprises smoothing the surface of the magnetic layer and thereafter abrading the surface thereof by an abrasive tape.

Method for preparing a magnetic recording medium

A magnetic recording medium having a magnetic layer is disclosed, comprising co-absorbed .gamma.-iron oxide particles as ferromagnetic particles and binders, wherein coercive force of Hc of the magnetic recording medium is 850 Oe or more and the ratio of the coercive force Hc and saturated magnetic flux density Bm thereof is 0.5/l or less.

Magnetic recording system

A process for producing a magnetic recording medium is disclosed, which comprises uniformly dispersing an .alpha.-Al.sub.2 O.sub.3 powder having a particle size of not greater than 0.1 .mu.m in a dispersion medium to obtain a dispersion, adding the dispersion to a coating composition for a magnetic layer essentially comprising a binder and a ferromagnetic powder having a specific surface area of not less than about 40 m.sup.2 /g, further dispersing the mixture to prepare a coating composition for a magnetic layer, and coating the resulting coating composition on a nonmagnetic support to obtain a magnetic layer having a dry thickness of about 2 .mu.m or less. The resulting magnetic recording medium exhibits excellent electromagnetic characteristics and improved abrasion resistance.

Process for producing a magnetic recording medium

Disclosed is a magnetic recording medium comprising a non-magnetic support having provided thereon a ferromagnetic metal thin film provided with a layer containing a compound having a mercapto group. This layer may also contain an ester bond. The magnetic recording medium shows improved running properties and wear resistance over wide ranges of temperature and humidity.

Magnetic recording medium

A method is described for preparing a magnetic recording medium by vapor-depositing a magnetic metal thin film on a polyester film, which comprises winding up a polyester film while subjecting the polyester film to a tension of from 0.1 to 2.0 kg/mm.sup.2, heating the resulting polyester film roll at 60.degree. C. to 80.degree. C. for from 10 to 100 hours, and vapor-depositing a magnetic thin film onto the polyester film while subjecting the polyester film to a tension of 0.5 kg/mm.sup.2 or more.

A magnetic recording medium is disclosed, which comprises a non-magnetic support having, on opposite surfaces thereof, a magnetic recording layer containing magnetic particles and a backing layer containing carbon black and other inorganic particles and a binder having a thickness of not more than 2.mu., the backing layer containing (a) carbon black having an average particle size of 60 to 120 m.mu. and (b) other inorganic particles having an average particle size of 20 to 100 m.mu..

A magnetic recording medium is disclosed which comprises a non-magnetic support having provided on opposite surface thereof a magnetic recording layer, and a backing layer containing carbon black and a binder, said carbon having an average particle size of not less than 150 m.mu. and the weight ratio of carbon black and the binder being 1:3.0 to 1:10.

Growing community of inventors

Kanagawa, Japan

Tadashi Ishikuro