Fuji Photo Film Company, Limited

Photopoly Ohka Co., Ltd.

Oiles Corporation

Kazuo Kato

Kenichi Masuyama

Hiroaki Araki

Noburo Hibino

Takeshi Kakuta

Hiroaki Takano

Shinji Saito

Hiroshi Hashimoto

Kazuko Hanai

Tadashi Ishiguro

Yasuyuki Tanaka

Masaaki Fujiyama

Masashi Aonuma

Hitoshi Noguchi

Nobutaka Yamaguchi

Hisashi Nakane

Hiroaki Doushita

Toshihiko Miura

Yasutoshi Okuzawa

Kazutoshi Katayama

Toshimi Aoyama

Hiroyuki Tohda

Toshichika Aoki

Tsuneo Yoshida

Mikio Ono

Akira Kashiwagi

A magnetic recording medium having on a nonmagnetic support at least one magnetic layer that contains a ferromagnetic metal powder and a binder and has surface roughness of 3 nm or below, with that the ferromagnetic metal powder has an average major-axis length of 30 to 100 nm and saturation magnetization &#x3c3;s of 70 to 100 A&#xb7;m/kg and the magnetic layer further contains SiOgrains having an average size of 5 to 30 nm, which shows excellent electromagnetic conversion characteristics, ensures reduction in MR head abrasion and has enhanced scratch resistance.

Magnetic recording medium

A magnetic recording medium comprising a backcoating layer, a support, and a magnetic layer containing ferromagnetic powder, the backcoating layer having 800 to 1500 projections of 50 nm or more and less than 75 nm in height per 6400 &#x3bc;mand 600 or less projections of 75 nm or more in height per 6400 &#x3bc;m.

Magnetic recording layer

A magnetic recording medium comprises: a support; and at least one magnetic layer comprising a binder and a ferromagnetic alloy powder including Fe, wherein the magnetic recording medium has a surface scratch depth of 370 nm to 460 nm, and has a surface lubricant index of 4 to 11.

The present invention discloses a magnetic recording particulate mediumhaving amagnetic layer on anonmagnetic support, the magnetic layer containing a ferromagnetic metal powder and a binder and having a coercive force of 1,400 to 1,700 Oe, wherein the ferromagnetic metal powder is spindle-shaped particles consisting essentially of Fe and having a Co/Fe ratio of from 1 to 5 atomic %, an Al/Fe ratio of from 5 to 15 atomic %, an average major axis length of 0.1 to 0.2 .mu.m and a specific surface area of 40 to 50 m.sup.2 /g, and the binder contains a polyurethane consisting essentially of a diol component comprising a polyether polyol and a polyester polyol and a polyisocyanate component. This magnetic recording particulate medium is characterized by minimal head wear, freedom from head clogging, and satisfactory electromagnetic characteristics.

Magnetic recording particulate medium

A magnetic recording medium comprising a nonmagnetic support and a magnetic layer, wherein the magnetic layer is provided on one surface of the nonmagnetic support, comprises a ferromagnetic particle, and has a surface roughness of from 2 to 10 nm; the nonmagnetic support has plural layers; at least one layer of the plural layers comprises an antistatic agent; and the nonmagnetic support has a surface roughness of from 5 to 30 nm on the opposite surface to the surface on which the magnetic layer is provided.

A magnetic recording medium having improved electromagnetic characteristics and running properties is disclosed. The magnetic recording medium comprises a non-magnetic support having thereon a plurality of magnetic layers consisting of two or more layers composed of a first lower magnetic layer and a second upper magnetic layer, provided on said support by either co-coating the lower magnetic layer and the upper magnetic layer in the wet state, or coating the lower magnetic layer and then the upper magnetic layer while the lower magnetic layer is still in the wet state; wherein the cobalt-modified iron oxide is employed as the ferromagnetic powder contained in the lower magnetic layer, ferromagnetic metal is employed as the ferromagnetic powder contained in the upper magnetic layer, both the ferromagnetic powder contained in the lower magnetic layer and the ferromagnetic powder contained in the upper magnetic layer having an average major axis length of 0.25 .mu.m or less and an average acicular ratio of 10 or less, a difference in the average major axis length between the ferromagnetic powder contained in the lower magnetic layer and that contained in the upper magnetic layer of 0.08 .mu.m or less, and a difference in the average acicular ratio between the ferromagnetic powder contained in the lower layer and that contained in the upper layer of 4 or less.

A magnetic recording medium having two or more magnetic layers is disclosed, comprising a first magnetic layer and a second magnetic layer which-have been provided in this order on a surface of a nonmagnetic support, and which contain ferromagnetic particles and a binder, wherein said second magnetic layer (outermost layer) contains nonmagnetic particles having a pH of less than 7, and a Mohs' hardness of 6 or more, in an amount of from 1 to 20 parts by weight, per 100 parts by weight of the ferromagnetic particles in the second magnetic layer, and said first magnetic layer contains nonmagnetic particles having a pH of 7 or more, and a Mohs' hardness of 6 or more, in an amount of from 5 to 50 parts by weight, per 100 parts by weight of the ferromagnetic particles in the first magnetic layer.

A magnetic tape cassette whose reliability is considerably improved by preventing triboelectrification by tape-and-guide friction. A metal tape guide for guiding the magnetic tape while in contact with the back surface of the tape. The substrate of the magnetic tape is made of polyethylene terephthalate or polyethylene naphthalate, and has a surface specific resistance R.sub.s of 10.sub.8 .OMEGA./cm.sup.2 or more. The tape guide is made of stainless steel or aluminum, and the surface roughness of the tape guide is such that the root mean square roughness value R.sub.rms, as determined by height from a reference surface, is 60 nm or lower. Also, the back surface of the tape may be provided with 30 to 400 protrusions of a height of 300 nm per 0.1 mm.sup.2.

Magnetic tape cassette having improved magnetic tape substrate and tape

A magnetic recording medium and a magnetic tape cassette are disclosed, comprising a non-magnetic support having formed on one surface only thereof at least two layers including a lower layer and an upper magnetic layer formed thereon, wherein the surface electric resistance (Rs) of the surface of the magnetic layer of said magnetic recording medium is 10.sup.9 .OMEGA./sq or less, the non-magnetic support contains at least three different kinds of particles which vary from each other in at least one property of mean particle diameter and Mohs' hardness, and the opposite surface of the magnetic recording medium comprises the rear surface of the nonmagnetic support having at least 1,000 projections having a height of from 200 nm to 400 nm per 0.1 mm.sup.2, but with the provisos that not more than 1,000 projections are present having a height of from 400 nm to 700 nm per 0.1 mm.sup.2 and not more than 50 projections are present having a height of 700 nm or more per 0.1 mm.sup.2.

Magnetic recording medium and magnetic tape cassette mounted with the

A magnetic recording medium is disclosed, which is formed by providing on a non-magnetic support, a lower layer comprising at least one of a ferromagnetic powder and a non-magnetic powder dispersed in a binder, and providing on the lower layer while the lower layer is in a wet condition, an upper magnetic layer comprising a ferromagnetic powder dispersed in a binder, wherein the upper magnetic layer has a dry thickness of 1.0 .mu.m or less, and the non-magnetic support is a multi-layer structural support comprising at least an uppermost support layer and a lowermost support layer, wherein the uppermost support layer is coated with the lower non-magnetic or magnetic layer, each of the uppermost layer and the lowermost layer comprises a biaxially oriented film comprising a thermoplastic resin containing filler particles, and the uppermost support layer has a center line average surface roughness Ra in the range defined by the following formula:

Magnetic recording medium containing a biaxially oriented multilayer

Disclosed is a magnetic recording medium which is improved in electromagnetic conversion and running durability which includes a magnetic layer containing a ferromagnetic powder dispersed in a binder on a non-magnetic support, wherein the sum of the elastic modulus in a longer direction of the non-magnetic support and the elastic modulus in a width direction of the non-magnetic support is 1,250 kg/mm.sup.2 or more; an elastic modulus in a longer direction of the magnetic layer is 0.6 to 3.0 times as much as the elastic modulus in the longer direction of the non-magnetic support; and an elastic modulus in a width direction of the magnetic layer is 0.4 to 2.0 times as much as the elastic modulus in the width direction of the non-magnetic support.

Magnetic recording medium comprising a magnetic layer and a non-magnetic

A magnetic recording medium is disclosed, comprising a non-magnetic support with an undercoating layer having formed thereon one or more magnetic layers. The undercoating layer contains a polyester resin or polyurethane resin having at least one polar group selected from the group consisting of --SO.sub.3 M, --OSO.sub.3 M, --COOM, and --OPO.sub.3 M.sub.2 (wherein M represents a hydrogen atom, an alkali metal, or an ammonium base, and M in different polar group or plural M's within the same polar group may be the same or different), and a glass transition temperature (Tg) of from 40.degree. C. to 80.degree. C. The magnetic layer contains a binder resin having at least one polar group selected from the same group as defined above. The recording medium has excellent adhesion between the non-magnetic support and the magnetic layer, high running durability and excellent electromagnetic characteristics.

A magnetic recording medium is disclosed. The medium is comprised of a non-magnetic support base having a surface with a center line average loughness (Ra) of not more then 0.035 .mu.m, having coated thereon a magnetic layer. The magnetic layer is comprised of a ferromagnetic powder, a fatty acid ester and two types of carbon black dispersed in a binder. The first type of carbon black has an average primary particles sizes of 10 to 30 m.mu.. The second type of carbon black has an average primary particle size of 60 to 120 m.mu.. The first type of carbon black and second type of carbon black are present in a mixing weight ratio in the range of 60/40 to 95/5. The magnetic recording medium has excellent electromagnetic properties and provides a tape having good running property and durability.

Magnetic recording medium including magnetic layer with carbon black

The invention provides an improved method for the so-called dry-film process for forming a pattern-wise photoresist layer on the substrate surface in which a substrate is overlaid and laminated with a preformed film of a photosensitive composition called a dry film and photolithographically processed. In the inventive method, different from conventional dry-film processes, the substrate plate is first provided with a protecting layer of a photosensitive composition containing a halation inhibitor and the lamination with a dry film is performed without removing the protecting layer. After pattern-wise exposure to light, development of the photosensitive layer is undertaken by use of a developer solvent capable of dissolving both of the protecting layer and the pattern-forming layer. Despite the intervention of the protecting layer, the resolving power and image reproducibility are excellent.

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Kanagawa, Japan

Kazuo Kato