JP2000089397A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having a transparent magnetic layer which is extremely less in the degradation in the output of a magnetic head at the time of input and output of a magnetic signal and has less electrification fog as a photographic sensitive material and the magnetic recording medium which has the decreased gaps by the higher density of a coating film and substantially prevents the penetration of a developer. SOLUTION: This magnetic recording medium is constituted by forming a transparent conductive layer on one side on a nonmagnetic base and forming the transparent magnetic layer on this transparent conductive layer. The recording medium has a conductive material in the transparent conductive layer and the turbidity of the nonmagnetic base and the coating layer is <=12 ppm. The total thickness of the nonmagnetic base and the coating layer is 75 to 90 microns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having a transparent magnetic layer, and more particularly, it has optical transparency,
The present invention relates to a magnetic recording medium which has excellent antistatic performance and can be provided with an image forming means on the opposite surface.

[0002]

2. Description of the Related Art The coating technology of a magnetic recording medium has been progressing with the progress of higher density of magnetic recording and accompanying multi-layering and thinning. However, an optical recording layer is formed on a magnetic recording medium. Technology is also evolving. The one described in the publishing of a photographic film with a magnetic recording layer is also an example.

For example, a silver halide photographic light-sensitive material (hereinafter, also simply referred to as a "light-sensitive material") includes, for example, the type, serial number, manufacturer name, emulsion No. Various information on shooting, such as shooting date and time, aperture, exposure time, lighting conditions, filters used, weather, shooting size, shooting model, use of anamorphic lens, etc. when shooting the camera, furthermore, the number of prints, filter selection , Customer's color preference, size of trimming frame, etc., necessary information for print production, number of prints, selection of filters,
Entering various information obtained at the time of printing, such as the customer's color preference, the size of the trimming frame, etc., and other customer information, etc., from the viewpoint of management, improvement of print quality,
This is also necessary from the viewpoint of improving the efficiency of the printing operation.

In a conventional photosensitive material, it is impossible to input all of such information, and only information such as a photographing date and time, an aperture and an exposure time is optically inputted at the time of photographing. In addition, it is impossible to input the above information into the photosensitive material at the time of printing without any means.

Since the magnetic recording system is easy to record / reproduce, studies have been made on the use of the magnetic recording system for inputting the above-mentioned various information to a photosensitive material, and various techniques have been proposed.

[0006] For example, it is a special feature to provide a stripe-shaped magnetic recording layer in which ferromagnetic fine particles are dispersed on the emulsion surface or the back surface beside the image area to record information such as sound and photographing conditions. No. 50-62627, No. 49-4503
Nos., U.S. Pat. Nos. 3,243,376 and 3,220,8
No. 43,782,9, and the provision of a transparent magnetic recording layer on a back surface of a light-sensitive material in which the necessary transparency is obtained by selecting the amount and size of magnetic particles is disclosed.
No. 47, 4,279,945, 4,302,52
No. 3 and the like. No. 4,947,1.
No. 96 and WO 90/04254 describe a camera for photographing having a magnetic head together with a roll-shaped film having a magnetic recording layer containing a magnetic substance capable of magnetic recording on the back surface of a photographic film.

The provision of these magnetic recording layers makes it possible to record the above-mentioned various information in the photosensitive material, which has been difficult in the past, and has the potential to record audio and image signals. ing.

The coating technique required for the magnetic recording layer of the photosensitive material and the physical properties of the binder include water resistance, abrasion resistance,
Very high and difficult-to-achieve levels are required, such as the dispersibility of magnetic powder, transparency, suitability for thin film coating, and dusting during cutting and perforation. Among them, the formation of the magnetic recording layer and the conductive layer, particularly before the coating of the photosensitive material, is a technique similar to that of the magnetic recording medium. However, unlike conventional audio and video tapes, the support itself is not used. The rigidity and paint composition are completely different, and the premise of wet chemical treatment,
There are a wide variety of required quality items such as rubbing the surface in a magnetic head or a running system after these processes, charging on the film before development, and prevention of fogging due to electric discharge. Is difficult.

In Japanese Patent Application Laid-Open No. 9-160173, the magnetic powder is dispersed by coating with a polymer having a dispersing function, and a vinylidene chloride-based polymer is employed as a binder for the conductive layer, thereby improving transparency, dispersibility, and interlayer property. It is disclosed that the adhesion is dramatically improved.

However, even with these techniques, the strength of the coating film and the stability of magnetic input / output after development have not been completely obtained.

JP-A-4-62543 has a transparent magnetic layer and has an electric resistance of 10% RH before and after the development process.
It is disclosed that a metal oxide or an ionic polymer having a resistivity of 10 ¹² Ω or less under the above conditions is used as a conductive agent.

However, the adhesion of dirt on the surface layer of the coating film is not improved simply by lowering the charge amount in the charging characteristics. Also, in order to lower the charge with the conductive agent, that is, to reduce the electric resistance, it is necessary to make a large amount of the conductive agent densely present in the coating film, and conversely, the coating film becomes brittle and the durability is deteriorated. .

In order to improve the magnetic input / output and the wear resistance of the coating film, the design of the surface roughness is important. It has become clear that the layer also contributes significantly in terms of surface properties, but no improvement has been made in this respect.

[0014] In addition, although conductive resins have been studied in recent years, they are easily deteriorated due to film physical properties, and have low strength compared to metal oxide particles, and their electric resistance is affected by humidity and contamination by electrolytes. Is not preferred.

The magnetic recording layer and the conductive layer used in the photographic film in the APS (Advanced Photo System) are used by being rubbed with a plastic cartridge.
A back layer having better durability, less chargeability, less charge deterioration, and a protective layer for an emulsion layer have been studied.

However, if the upper magnetic recording layer is made thicker and the wear resistance is improved, the effect of the lower conductive layer is reduced, and the required conductivity cannot be obtained unless the conductive layer is too thick. When the upper magnetic recording layer is made thinner, the adhesiveness between the layers is improved, but the difference in the refractive index from the conductive layer causes interference fringes and the coating properties are deteriorated, which is practically difficult.

Also, since the conductive layer originally requires a coating layer thereon, it is desirable that the adhesion to other coating layers be good, but on the other hand, when the emulsion layer is provided, blocking is required. It is required not to cause such problems. In addition, it is preferable from the viewpoint of productivity that physical and chemical changes are small after forming the conductive layer and before forming a functional layer such as a magnetic recording layer.

In particular, when it is desired that the outermost layer at the time of coating has a rough and uniform projection distribution on the surface of the magnetic recording layer in order to ensure the stability of magnetic input / output, simply add the matting agent particles of the magnetic layer coating solution. It cannot be achieved only by itself. In any case, the composition and manufacturing method of the intermediate layer having a good function of the conductive layer and the function of the adhesive layer have not been achieved.

Particularly in the case of multi-layer coating, the properties of the material of the lower layer,
That is, it may be difficult to sequentially form layers due to adhesiveness, solvent resistance, and the like. In addition, if you want to apply the upper layer thinly and evenly, the quality of the applied layer will change significantly due to slight process fluctuations because of the low viscosity and low solids concentration of the upper layer coating solution using conventional materials.
Long and stable application on a production scale is virtually impossible. In addition, when the conductive layer is formed and then wound up and used for other purposes, the conductive layer is not merely an intermediate layer, but must prevent failure due to contact with the opposite surface.

In addition, in recent years, instead of continuously coating the magnetic layer and the emulsion layer, the support which has been subjected to the antistatic treatment is not continuously coated with the magnetic layer and the emulsion layer, but is stored in an intermediate state according to various production plans, market trends and the like. There is a demand for commercialization and application development. It is difficult to meet such demands with conventional materials, prescriptions, and process technologies premised on integrated production.

Under these circumstances, the binders, conductive agents, lubricants, and solvents that can be used in the present invention are limited, and very advanced manufacturing techniques and prescription techniques are required for practical use. .

[0022]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a magnetic recording medium having a transparent conductive layer and a magnetic recording layer having excellent optical characteristics.

A second object of the present invention is to provide a magnetic recording system having a transparent magnetic layer and a conductive layer having excellent abrasion resistance and blocking resistance by appropriately selecting the composition of a binder and an additive for the transparent magnetic layer and the conductive layer. To provide a medium.

A third object is to use a material having good coating strength and low electric resistance to provide a transparent magnetic layer which has a very small decrease in the output of a magnetic head when inputting / outputting a magnetic signal and has little charged fog as a photographic photosensitive material. To provide a magnetic recording medium having the same.

A fourth object of the present invention is to provide a magnetic recording medium having few voids due to a high density of a coating film and hardly permeating a developer.

[0026]

The above object of the present invention is achieved by the following constitution.

1. A transparent conductive layer is formed on one side of the non-magnetic support, a transparent magnetic layer is formed on the transparent conductive layer, a conductive material is provided in the transparent conductive layer, and the non-magnetic support and the coating layer Has a turbidity of 12 ppm or less, and the total thickness of the nonmagnetic support and the coating layer is 75 to 90 microns.

2. The thickness of the transparent magnetic layer is 0.5 μm
1.8 μm and the amount of conductive material particles in the transparent conductive layer is 4
The magnetic recording medium according to the 1, which is a ^{0mg / m 2 ~120mg / m 2} .

3. 3. The method according to 1 or 2, wherein the conductive material particles have an oxide mainly composed of tin oxide, and an oxide having an average particle size of 10 nm to 90 nm and an oxide having a thickness of 120 nm to 500 nm. Magnetic recording medium.

4. The transparent conductive layer has an oxide mainly composed of tin oxide and a binder, and the weight ratio of the oxide and the binder is 40/60 to 70/60. The magnetic recording medium according to the above.

5. Before the transparent conductive layer is applied to the magnetic layer and / or
5. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is processed by a calender after coating the magnetic layer.

6. 6. The magnetic recording medium according to the above 1, 2, 3, 4 or 5, wherein the binder of the transparent conductive layer is a hydrophilic binder having an amide bond.

[7] The transparent conductive layer is provided on a polyester-based support after film formation, and a coating layer mainly composed of gelatin is formed on the surface opposite to the transparent conductive layer as the outermost layer before or after the formation of the transparent conductive layer. 7. The magnetic recording medium according to 1, 2, 3, 4, 5, or 6, wherein the polyester support is subjected to an antistatic treatment.

8. In a magnetic recording medium in which a transparent magnetic layer is formed on a transparent magnetic layer, the conductive material particles mainly composed of tin oxide have a mean particle diameter of 10 to 90 nm, and a needle-like mean long axis length of 120 to 800 nm. A magnetic recording medium characterized by using the following conductive material particles in combination.

Hereinafter, the present invention will be described in more detail.

"Transparent" of the transparent magnetic layer (hereinafter also referred to as "magnetic recording layer") in the present invention means that the optical density is 1.5 or less. The optical density was measured using a Sakura densitometer PDA-65 manufactured by Konica Corporation, and light having a wavelength of 436 nm was vertically incident on the coating film through a filter that transmits blue light. It means that the optical density by the method of calculating the absorption is 0.2 or less, particularly preferably 0.1 or less.

The term "magnetization amount per unit area" in the present invention refers to the magnetization intensity per 1 m ^{2 of} the photographic photosensitive material, that is, the magnetization intensity per 1 m ^{2 of} the transparent magnetic layer. The intensity of magnetization is also called magnetization, and a detailed description and a measurement method are described in “Basics of Magnetic Engineering I” (by Keizo Ota, Kyoritsu Zensho). In the present invention, the sample is saturated once with an external magnetic field of 1000 Oe (Oe) in the direction of application of a fixed volume coating film using a sample vibration type magnetometer (VSM-3) manufactured by Toei Kogyo, and then the external magnetic field is reduced. The magnetic flux density (residual magnetic flux density) when measured to 0 was measured and converted to the volume of the transparent magnetic layer contained per 1 m ² of the photosensitive material.

In the present invention, the amount of magnetization per unit area of the transparent conductive layer is preferably 3 × 10 ^-2 emu or more.

The amount of magnetization per unit area of the transparent magnetic layer is 3
If it is less than × 10 ^-2 emu, the input / output of magnetic recording will be hindered.

The thickness of the transparent magnetic layer is preferably from 0.5 to 3.0 μm, more preferably from 0.6 to 2.5 μm, and still more preferably from 0.6 to 2.0 μm.

The coating solution for forming the magnetic recording layer may be provided with a lubricant or an antistatic agent in order to provide the magnetic recording layer with functions such as imparting lubricity, preventing charge, preventing adhesion, and improving friction and wear resistance. Various additives can be added. In addition, a plasticizer is added to impart flexibility to the magnetic recording layer, a dispersant is added to help disperse the magnetic substance in the coating solution, and an abrasive is added to prevent clogging of the magnetic head. be able to.

The above-mentioned provision of lubricity, antistatic, antiadhesive,
Functions such as improvement of friction / wear resistance and prevention of clogging of the magnetic head may be provided by providing these functional layers separately from the magnetic recording layer. For example, when the magnetic recording layer of the present invention is provided on the antistatic layer, its good film-forming properties and the number of coatings can be reduced to form a more uniform thin film, so that a conventional transparent magnetic layer is formed on the antistatic layer. Better antistatic properties can be obtained than in the case where When the magnetic recording layer is provided in the form of a stripe, a transparent polymer layer containing no magnetic material may be provided thereon to eliminate a step due to the magnetic recording layer. In this case, the transparent polymer layer may have the various functions described above.

The production method used in the present invention can disperse using not only the magnetic powder but also the various additives described above in combination with the magnetic powder in order to suppress solvent penetration and swelling into the lower layer and to improve the coating strength after drying. The number of constituent layers of the photosensitive material can be reduced, which is advantageous in manufacturing.

In the present invention, the term "calendering" means not only improving the smoothness and improving the S / N ratio of the magnetic output, but in this case, after applying the calendering, the silver halide photosensitive layer is coated. Is preferred.

The ferromagnetic fine powder used for the transparent magnetic material layer includes ferromagnetic iron oxide fine powder, Co-doped ferromagnetic iron oxide fine powder, ferromagnetic chromium dioxide fine powder, ferromagnetic metal powder, and ferromagnetic alloy powder. And barium ferrite.

The ferromagnetic powder can be produced according to a known method. The shape may be any of a needle shape, a rice grain shape, a spherical shape, a cubic shape, a plate shape and the like, but a needle shape and a plate shape are preferable in terms of electromagnetic conversion characteristics. The crystallite size and non-surface area are also not particularly limited, but the crystallite size is 400 ° or less, and the BET
Preferably at least 20 m ² / g with a value, and particularly preferably equal to or greater than 30 m ² / g.

The pH and surface treatment of the ferromagnetic powder can be used without any particular limitation, and the preferred pH range is 5-10. In the case of the ferromagnetic iron oxide fine powder, the ratio of divalent iron / trivalent iron can be used without any particular limitation. These magnetic recording layers are described in JP-A-47-32812.
No. 53-109604.

The preferred amount of the magnetic powder is 1 m
4 × 10 ⁻⁴ g or more per ²

If the amount is less than 4 × 10 ⁻⁴ g, the input / output of magnetic recording is hindered. The upper limit may be any value as long as the optical density of light having a wavelength of 436 nm is 1.5 or less. However, the upper limit is 4 g per 1 m ² , and if it exceeds this, practical problems occur as a photosensitive material.

In order to form an optically transparent magnetic recording layer, the binder is used in an amount of 1 to 2 parts by weight based on 1 part by weight of the magnetic powder.
It is preferable to use 00 parts by weight. More preferably, the amount is 2 to 50 parts by weight based on 1 part by weight of the magnetic substance powder. The solvent is used in such an amount that the coating can be easily performed.

The method for providing a magnetic recording layer on a support includes extrusion coating, air doctor coating, blade coating, air knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, and the like. Cast coat, spray coat, etc. can be used. In order to perform multiple stripe coating, these coating heads may be formed in multiples. Specific methods for stripe coating include, for example, JP-A-48-25503 and JP-A-48-25504,
No. 48-98803, No. 50-138037, No. 5
2-15533, 51-3208, 51-62
No. 39, No. 51-65606, No. 51-140703
No., JP-B-29-4221, U.S. Pat. No. 3,062,1
Nos. 81 and 3,227,165 can be referred to.

However, the most effective coating method in the present invention is a two-slit type multi-layer coating head shown in FIG. 3 of JP-A-5-192627. By adjusting the contact gap between the slit gap of the head and each of the front, center and back edges, it is possible to cope with magnetic recording media having different thicknesses and rigidities of the support.

In order to firmly adhere the magnetic recording layer to the support, an undercoat layer may be provided on the support. The support may be treated with a chemical, a mechanical treatment, a corona discharge treatment, a flame treatment, an ultraviolet ray, or the like. Surface activation treatment such as treatment, high-frequency treatment, glow discharge treatment, active plasma treatment, laser treatment, concentrated acid treatment, and ozone oxidation treatment may be performed. Further, an undercoat layer may be provided after the surface activation treatment. The undercoat layer is preferably of an aqueous latex type.

As the binder that can be used for the magnetic recording layer or the binder that is used for the undercoat layer, there are thermoplastic resins, radiation-curable resins, thermosetting resins, and other reactive resins, which are dissolved or dispersed in an organic solvent or water. Can be used alone or in combination.

Examples of the thermoplastic resin include vinyl chloride / vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, vinyl acetate / vinyl alcohol copolymer, partially hydrolyzed vinyl chloride / vinyl acetate copolymer, vinyl chloride -Vinyl polymers such as vinylidene chloride copolymer, vinyl chloride / acrylonitrile copolymer, ethylene / vinyl alcohol copolymer, chlorinated polyvinyl chloride, ethylene / vinyl chloride copolymer, ethylene / vinyl acetate copolymer Or a copolymer, nitrocellulose, cellulose diacetate, cellulose derivative such as cellulose acetate propionate, cellulose acetate butyrate resin, a copolymer of maleic acid and / or acrylic acid, an acrylate ester copolymer, acrylonitrile styrene Copolymer, chlorinated polyethylene, Acrylonitrile-chlorinated polyethylene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, acrylic resin, polyvinyl acetal resins, polyvinyl butyral resins, polyester polyurethane resins, polyether polyurethane resins,
Polycarbonate polyurethane resin, polyester resin, polyether resin, polyamide resin, amino resin,
Rubber-based resins such as styrene-butadiene resin and butadiene-acrylonitrile resin, silicone-based resins, and fluorine-based resins can be used. Particularly, cellulose derivatives, especially cellulose diacetate, are preferred.

The above thermoplastic resin has a Tg of usually -40 to 40.
180 ° C., preferably −30 ° C. to 150 ° C., and the weight average molecular weight is preferably 5,000 to 300,000, and more preferably the weight average molecular weight is 10,000.
0 to 200,000.

It is desirable that the above-mentioned binder is crosslinked by using a crosslinking agent in combination. Examples of the crosslinking agent that can be used include epoxy compounds, aziridine compounds, N-methylol compounds, aldehyde compounds, ketone compounds, polyfunctional isocyanate compounds, and inorganic crosslinking agents. In particular, polyfunctional isocyanate compounds are preferred.

The transparent magnetic layer of the present invention has a Tg of 50.
It is preferable to use a combination of not less than 30 ° C. and not more than 30 ° C. Tg is described in detail in New Experimental Chemistry Course 19 (Polymer Chemistry II), Maruzen.

These can be used as an aqueous emulsion or an aqueous colloid solution. These synthetic resin emulsions having a particle size of 5 nm to 2 μm can be used.

The radiation-curable resin is a resin which is cured by radiation such as an electron beam or an ultraviolet ray, and includes a maleic anhydride type, a urethane acrylic type, an ether acrylic type, and an epoxy acrylic type. In each case, the unsaturated bond is polymerized, ring-opened and cross-linked by light, radiation, electron beam or the like to increase the molecular weight.

More specifically, the vinyl ester resin “Lipoxy” series (Showa Kogaku Co., Ltd.), Seika Beam PH
C ・ MPL series, Seika beam DP series, Seika beam P-1000 series, Seika beam W500
0 series, Seika Beam K series (Dainichi Seika Kogyo Co., Ltd.), Koei Hard A series, C series, M series, T series, D series, NS series, F series, HS series, J series (Kaoei Chemical Industry Co., Ltd.) UV curable hard coating agent DH
Series (Dahachi Chemical Industry Co., Ltd.) and Aurex Series (China Paint Co., Ltd.).

Examples of the thermosetting resin and other reactive resins include phenol resin, epoxy resin, polyurethane-based curing resin, urea resin, alkyd resin, and silicone-based curing resin.

The binders listed above may have a polar group in the molecule. As the polar group, an epoxy group, -C
OOM, -OH, -N (R) 2, -N + (R 2) X, -S
O ₃ M, —OSO ₃ M, —PO ₃ M ₂ , and —OPO ₃ M (M is a hydrogen atom, an alkali metal or ammonium,
Represents an acid that forms an amine salt, and R represents a hydrogen atom or an alkyl group, respectively.

Other hydrophilic binders usable in the present invention include, for example, Research Disclosure (R)
DNo. No. 17643, page 26 and the same No. 18716,
Examples thereof include water-soluble polymers, cellulose ethers, latex polymers, and water-soluble polyesters described on page 651.

Examples of the water-soluble polymer include gelatin, gelatin derivatives, casein, agar, sodium alginate, starch, polyvinyl alcohol, acrylic copolymers, and maleic anhydride copolymers in addition to those described above. As ethers, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose,
Hydroxypropyl cellulose and the like.

When a water-soluble polymer is used, a hardener is preferably used. Hardening agents that can be used include aldehyde compounds, ketone compounds, compounds having a reactive halogen, compounds having a reactive olefin,
Examples include N-methylol compounds, isocyanates, aziridine compounds, acid derivatives, epoxy compounds, mucohalic acids, chromium alum, zirconium sulfate, and carboxyl group active hardeners. Hardeners are usually
It is used in an amount of 0.01 to 60% by weight, preferably 0.05 to 50% by weight, based on the resin solid content.

Examples of the lubricant that can be used for the transparent magnetic layer include:
Silicon oil such as polysiloxane, plastic fine powder such as polyethylene and polytetrafluoroethylene, higher fatty acids, higher fatty acid esters, paraffin wax,
Fluorocarbons. These can be used alone or as a mixture. These addition amounts can be used in the range of 0.5 to 20 parts by weight based on 100 parts by weight of the dried coating film. Those that can be dissolved or diffused in water are preferred.

Examples of the abrasive that can be used for the transparent magnetic layer include:
Non-magnetic inorganic powders having a Mohs hardness of usually 5 or more, preferably 6 or more, specifically, aluminum oxide (α-alumina, γ-alumina, corundum, etc.), chromium oxide (Cr ₂ O ₃ ), Examples thereof include oxides such as iron oxide (α-Fe ₂ O ₃ ), silicon dioxide and titanium dioxide, carbides such as silicon carbide and titanium carbide, and fine powders such as diamond. The average particle size is preferably 0.01 to 2.0 μm, and 0.5 to 300 μm with respect to 100 parts by weight of the magnetic powder.
It can be added in the range of parts by weight.

As the antistatic agent contained in the transparent magnetic layer, metal oxide fine particles are preferable. A specific example is Nb
Oxygen-excess oxide such as ^{_{2 O 5 + x, RhO 2}} - x, Ir 2
O ₃ ^- oxygen deficiency oxides such as x, or nonstoichiometric hydrides such as _{Ni (OH) x, HfO 2} , ThO 2, ZrO 2, C
eO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In
₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₂ , V ₂ O _5, etc.
Alternatively, these composite oxides are preferable, and in particular, ZnO, T
iO ₂ and SnO ₂ are preferred. Examples of including heteroatoms include, for example, addition of Al, In, etc. to ZnO,
For ₂ Nb, the addition of Ta or the like, also, Sb, Nb, addition of such a halogen element is effective for SnO _2.
The addition amount of these different atoms is preferably in the range of 0.01 to 25 mol%, and particularly preferably in the range of 0.1 to 15 mol%.

The volume resistivity of the conductive metal oxide powder is preferably 107 Ωcm, particularly preferably 105 Ωcm or less. Further, a sol in which fine particles of the metal oxide are mixed in an aqueous solution may be used.

In addition, conductive fine powders such as carbon black and carbon black graft polymer, nonionic surfactants such as alkylene oxide, glycerin and glycidol; higher alkylamines, quaternary ammonium salts, pyridine Other heterocyclic compound salts, cationic surfactants such as phosphonium or sulfonium; carboxyl group, phosphate group, sulfate group,
Anionic surfactants containing an acidic group such as a phosphate group; amphoteric surfactants such as amino acids, aminosulfonic acids, sulfuric acid or phosphates of amino alcohols, and the like;

Since the binder system of the present invention is also excellent in dispersibility of these antistatic agents, good conductivity can be imparted to the transparent magnetic layer.

The surfactant may be contained as a substituent of the polymer.

Solvents used in the dispersion, kneading and coating of the present invention include acetone, methyl ethyl ketone, methyl i-butyl ketone, cyclohexanone,
Ketones such as isophorone and tetrahydrofuran; alcohols such as methanol, ethanol, propanol, butanol, i-butyl alcohol, i-propyl alcohol and methylcyclohexanol; methyl acetate, ethyl acetate, butyl acetate, i-butyl acetate and acetic acid Esters such as i-propyl, ethyl lactate, glycol acetate, and monoethyl ether; glycol ethers such as ether, glycol dimethyl ether, glycol monoethyl ether, and dioxane; benzene, toluene, xylene, cresol, chlorobenzene, styrene, and the like. Tar-based (aromatic hydrocarbons); chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene;
N, N-dimethylformaldehyde, hexane, water and the like can be used.

In the present invention, various supports can be used. Specifically, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cellulose triacetate (TAC) film, cellulose diacetate (DA)
C) Films, polycarbonate films, polystyrene films, polyolefin films and the like can be mentioned.

The polyester support is not particularly restricted but includes aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid and naphthalenedicarboxylic acid and ethylene glycol, 1,3-propanediol and 1,4-butanediol. Condensation polymers with alkylene glycols, for example, polyethylene terephthalate, polyethylene-2,6-dinaphthalate, polypropylene terephthalate, polybutylene terephthalate, and the like, and copolymers thereof are exemplified. In particular, Japanese Patent Application Laid-Open Nos. 1-244446 and 1-291248 disclose curl recovery properties after development processing.
No. 1-298350 No. 2-89045 No. 2
-93641, 2-181749, 2-214
It is preferable to use a polyester having a high water content as described in JP-A No. 852 and JP-A-2-291135. These polyesters may have a polar group and other substituents.

The support of the present invention may be PET or PEN.
Is preferred. These polyesters are preferably stretched in an area ratio of 4 to 16 times in order to satisfy the mechanical strength, dimensional stability and the like of the film support.

The support includes a matting agent, an antistatic agent, a lubricant, a surfactant, a stabilizer, a dispersant, a plasticizer, an ultraviolet absorber, a conductive substance, a tackifier, a softener, and a fluidity-imparting agent. , A thickener, an antioxidant, and the like.

The support is neutralized in color at the minimum density portion, and light piping phenomenon (edge fogging) that occurs when light is incident from the edge on a film coated with a photographic emulsion layer.
Dyes can be contained for the purpose of preventing bleeding and preventing halation.

The type of the dye is not particularly limited, but when a polyester film is used as a support, it is preferable that the dye has excellent heat resistance in the film forming step, and examples thereof include an anthraquinone-based chemical dye. Also, as the color tone,
For the purpose of preventing light piping, gray dyeing is preferable as seen in general photographic materials. The dyes may be used alone or in combination of two or more. Commercial products: Diaresin, Baye, manufactured by Mitsubishi Chemical Corporation
The target can be achieved by using a dye such as MACROLEX, manufactured by r company, alone or in an appropriate mixture.

The photosensitive material having a magnetic recording layer according to the present invention comprises
Any photosensitive material such as black-and-white photosensitive material, color negative photosensitive material, color paper photosensitive material, color reversal photosensitive material, movie photosensitive material, X-ray photosensitive material, printing photosensitive material, microphotographic photosensitive material, etc. There may be.

[0082]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the embodiments of the present invention are not limited thereto.

Example 1 (Preparation of Undercoating Base) 20 W / m ^{2 on} both sides of polyethylene-2,6-naphthalate base (85 μm thick)
Min corona discharge treatment to prepare undercoating liquids U-1 and S-1 having the following composition on one side, and U-1 from the base side
Is applied so as to have a dry film thickness of 0.1 μm, and S-1 is applied thereon so that the conductive material has a coating weight of 80 mg.
A subbing coating solution U-2 having the following composition was prepared on the other surface.
The resultant was applied so as to have a dry film thickness of 1 μm to prepare a support having an undercoat layer having an antistatic function. In the following examples, “parts” of each material indicates “parts by weight” unless otherwise specified.

Undercoating solution (U-1) Gelatin 1 part Water 1 part Acetic acid 1 part Methanol 80 parts Isopropyl alcohol 20 parts p-chlorophenol 1 part Conductive layer coating solution (S-1) Conductive material (tin oxide fine powder) , Average primary particle size 80 nm) 40 parts Gelatin 10 parts Surfactant (A-1) 0.1 parts Methanol 800 parts Resorcin 4 parts Undercoating coating solution (U-2) Gelatin 10 parts Water 10 parts Methanol 900 parts Surface activity Agent (A-1) 0.1 part Hardener (H-1) 0.3 part Matting agent (silica particles having an average particle diameter of 1 μm) 0.5 part The structural formula of the compound used is shown below.

[0085]

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(Coating of Magnetic Recording Layer and Lubricating Layer) On the surface of the undercoating-treated base on which the undercoating layer S-1 (corresponding to the conductive layer) was applied, the magnetic layer coating solution (M- 1) and a coating liquid (W-1) for a lubricating layer were prepared, and the coating was oriented in a coating direction in an orientation magnetic field while the coating was not dried to increase the output of magnetic recording. Subsequently, W-1 is applied in an atmosphere under normal temperature,
The raw material after application was introduced into a drying zone, and was dried sufficiently by passing through a controlled drying air and a conveying roll, with the upper limit being 75 ° C. which is lower than the melting point of carnauba wax.

Subsequently, it is completely dried in a drying zone,
After cooling, it was wound up. The original roll after application was left in an oven at 50 ° C. for 3 days to allow sufficient reaction of the crosslinking agent to obtain a magnetic recording medium for a subbed photographic photosensitive material. Each sample has a resin outer diameter of 1
Only the same sample having a width of 18 cm and a coating length of 500 m was continuously wound around a 5 cm core, and was applied, transported, stored, and heat-treated under the same winding conditions.

Magnetic Layer Coating Solution (M-1) The following composition P-1 was stirred and mixed, and then dispersed by a sand mill.

<P-1> Cobalt-containing γ-iron oxide (average major axis length 0.12 μm, 7 parts minor axis length 0.015 μm, Fe ²⁺ / Fe ³⁺ = 0.2, specific surface area 40 m ² / g , Hc = 750 Oe) α-alumina (average particle size 0.2 μm) 5 parts Polymethyl methacrylate (mat material, average particle size 1.0 μm) 0.3 parts Polyurethane (molecular weight 30,000, sulfonic acid group 2 per molecule 2) 1 part Methyl ethyl ketone 10 parts Cyclohexanone 3 parts The above P-1 is diluted with the following resin solution for dilution LD-1 and stirred and mixed.

<LD-1> Cellulose diacetate 89 parts Cyclohexanone 600 parts Acetone 600 parts After this coating solution was further dispersed by a sand mill, 20 parts of coronate 3041 (50% solids) was added, stirred, and filtered with a filter. Thus, a magnetic layer coating liquid M-1 was obtained.

Lubricating layer coating liquid (W-1) Carnauba wax 1 part Cellulose acetate propionate 0.3 part Cyclohexanone 3 parts Propylene glycol monomethyl ether 3 parts After stirring and mixing, the mixture was dispersed by a sand mill to form a stock solution.
This was diluted with 1000 parts by weight of a solvent having a weight ratio of cyclohexanone / acetone of 1/1, filtered, and then filtered.
It was set to 1.

(Evaluation of Magnetic Recording Medium) The coating properties and devitrification, surface specific resistance, adhesiveness to a support, and blocking properties of the sample 1 thus obtained were evaluated.

<< Applicability >> The state immediately before the application of the base before entering the drying zone was visually observed and classified as follows.

：: Good coating state △: Coating failure such as mottle unevenness and uneven streaks of upper and lower layers occurred and coating range was extremely narrow ×: Impossible level << turbidity (haze value) >> Mitsubishi Chemical Industrial company turbidity meter SEP
-Measured using a model PT-501D.

<< Adhesiveness >> A cellophane tape was adhered to a sample in a fixed area and a constant load was written with a rubber roller, and then peeled off, and the peeled area of the back surface (magnetic recording layer) was examined. It was calculated from the area ratio to the portion where the tape was first applied.

0% was not peeled off at all, and 100% was the magnetic recording layer completely transferred to the cellophane tape side.

(Preparation of Photosensitive Material) The surface opposite to the surface of the sample 1 having the magnetic recording layer, that is, 25
After applying a corona discharge of W / m ² · min,
A multilayer color light-sensitive material having an emulsion layer constitution corresponding to sample 101 of Example 1 described in JP-A-334858 was prepared.

In the emulsion layer of the sample, the silver coating amount was 6.
25 mg / m ² and the dry film thickness was 18 μm. The sample was cut and pierced according to the APS format,
A photographic film containing a cartridge for S was used.

<Development> The prepared photosensitive material was developed according to the following processing steps.

Processing step Processing time Color development 3 minutes 15 seconds Bleaching 6 minutes 30 seconds Rinse 2 minutes 10 seconds Fix 4 minutes 20 seconds Rinse 3 minutes 15 seconds Stabilization 1 minute 05 seconds Processing solution used in each step The composition was as follows.

Color developer Diethylenetriaminepentaacetic acid 1.0 g 1-hydroxyethylidene-1,1-diphosphonic acid 2.0 g Sodium sulfite 4.0 g Potassium carbonate 30.0 g Potassium bromide 1.4 g Potassium iodide 1.3 mg Hydroxylamine Sulfate 2.4 g 4- (N-ethyl-N-β-hydroxyethyl) amino-2-methylaniline sulfate 4.5 g Water is added to 1 liter, and the pH is adjusted to 10.0.

Bleaching solution Ferric ammonium salt of ethylenediaminetetraacetic acid 100.0 g Disodium salt of ethylenediaminetetraacetic acid 10.0 g Ammonium bromide 150.0 g Ammonium nitrate 10.0 g Water is added to 1 liter to adjust the pH to 6.0.

Fixer Disodium ethylenediaminetetraacetate 1.0 g Sodium sulfite 4.0 g Ammonium thiosulfate (70%) 175.0 g Sodium bisulfite 4.6 g Water is added to 1 liter to adjust the pH to 6.6.

Stabilizer Formalin (40%) 2.0 mg Polyoxyethylene-p-monononylphenyl ether (average degree of polymerization 10) 0.3 g Water was added to make up to 1 liter.

(Evaluation of photosensitive material) Each sample of the photosensitive material prepared as described above was evaluated as follows.

<< Durability Test >> A test piece was fixed on a carrier that reciprocates horizontally for a distance of 15 cm with the measurement surface of the specimen facing upward, and a load of 150 g was applied from above with a stainless steel ball (5 mmφ). The carrier was slid at a speed of 10 cm / sec, and reciprocated 1,000 times. The degree of damage after the end of the test was measured according to the rank shown below. The measurement surface is a surface having no emulsion layer after development, and the measurement environment is room temperature (25 ° C.).
55% RH).

A: No damage B: There is a sliding mark, but there is no decrease in the output of the magnetic recording / reproducing device. C: There is flaw, and the output of the magnetic recording / reproducing device is 50.
% Decrease D: film peeling occurs.

<< Solvent Resistance Test >> On a flat plate reciprocating horizontally for a distance of 5 cm, each sample was fixed with the measurement surface up, and a felt (5 m) impregnated with ethanol from above.
m square) with a load of 10 g. The plate on which the sample was placed was run at a speed of 10 cm / sec, and reciprocation was repeated 30 times. The degree of solvent resistance was measured according to the following rank.

A: No change at all B: A magnetic layer is slightly removed C: A magnetic layer is removed by being removed after 10 or more times D: A magnetic layer is removed by several times Elutes.

<< Stain Adhesion Test >> Samples after mixing the above-mentioned fixing solution and stabilizing solution with a 30-fold concentration (reducing the dilution of water to 1/30) and subjecting them to normal development processing. After 10 minutes infiltration, pull up, 23 ° C,
The coated surface was allowed to dry in a vertical direction in a 50% environment. The stain on this sample was evaluated according to the following criteria.

・ ・ ・: No change in appearance and usable as a photographic film △: scale-like stains are visible in the periphery but acceptable for practical use ×: solidification of adhered solids , The transparency of which clearly deteriorates.

Comparative Examples 1 to 7 The same procedure as in Example 1 was carried out except that the dry thickness of the magnetic layer and the amount of the conductive material were changed as shown in Table 1.
2 to 8 were produced and evaluated as magnetic recording media.

Examples 2 to 4 Except that the composition of S-1 of Example 1 was changed to S-2 or S-3, and the thickness of the dried magnetic layer was changed as shown in Table 2. In the same manner as in Example 1, the sample No. 9 to 11 were prepared and evaluated as magnetic recording media and photosensitive materials.

Conductive layer coating liquid (S-2) Conductive material (tin oxide powder, average major axis length 350 nm) 10 parts Conductive material (tin oxide fine powder, average primary particle size 80 nm) 40 parts Gelatin 10 parts Surface activity Agent (A-1) 0.1 part Methanol 800 parts Resorcin 4 parts Conductive layer coating solution (S-3) Conductive material (tin oxide needle powder, average major axis length 350 nm) 40 parts Gelatin 10 parts Surfactant (A -1) 0.1 part Methanol 800 parts Resorcin 4 parts Examples 5 to 11 The composition of S-3 and the amount of the conductive material in Example 4 were changed as shown in Table 3, and a conductive layer was applied and dried. Later, 300kg,
Sample No. 1 was prepared in exactly the same manner as in Example 4 except that it passed through a 4 nip calender roll (combination of a mirror chrome plating roll and a hard nylon roll) at 80 ° C. 12-1
8 was prepared and evaluated as a magnetic recording medium and a photosensitive material.

Examples 12 to 16 and Comparative Examples 8 to 13 By substituting the base thickness of Example 2, the composition of S-1 and the composition of U-2 as shown in the following U-3 and Table 4, , Sample No. 19 to 29 were prepared and evaluated as a magnetic recording medium and a photosensitive material.

Undercoat layer coating solution (U-3) Butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl methacrylate copolymer 100 parts Methyl ethyl ketone 900 parts Surfactant (A-1) 0.1 part Hard film Agent (H-2) 0.1 part Matting agent (silica particles having an average particle diameter of 1 μm) 0.5 part Evaluation results are shown below.

[0117]

[Table 1]

[0118]

[Table 2]

[0119]

[Table 3]

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[Table 4]

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[Table 5]

[0122]

[Table 6]

[0123]

[Table 7]

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[Table 8]

[0125]

[Table 9]

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[Table 10]

As is clear from the above results, the sample of the present invention is superior to the comparative sample.

[0128]

As demonstrated in the examples, the magnetic recording medium according to the present invention has a transparent conductive layer and a magnetic recording layer which are excellent in optical characteristics, and the composition of the binder and additives of the transparent magnetic layer and the conductive layer is appropriately adjusted. By using a material with good coating strength and low electrical resistance, which has a transparent magnetic layer with excellent wear resistance and blocking resistance and a conductive layer, the output of the magnetic head during input / output of magnetic signals can be reduced. It has a very small number of transparent magnetic layers with little charged fog as photosensitive material,
It has an excellent effect that the developer is hardly permeated with few voids due to the high density of the coating film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/84 G11B 5/84 Z

Claims (8)

[Claims] 1. A transparent conductive layer is formed on one side of a nonmagnetic support, and a transparent magnetic layer is formed on the transparent conductive layer.
A conductive material is provided in the transparent conductive layer, the turbidity of the nonmagnetic support and the coating layer is 12 ppm or less, and the total thickness of the nonmagnetic support and the coating layer is 75 μm to 90 μm. Characteristic magnetic recording medium. 2. The transparent magnetic layer having a thickness of 0.5 μm to 1.
8 μm and the amount of conductive particles in the transparent conductive layer is 40 m
The magnetic recording medium according to claim 1, characterized in that the ^{g / m 2 ~120mg / m 2} . 3. The conductive material particle has an oxide mainly composed of tin oxide, and an oxide having an average particle size of 10 nm to 90 nm and an oxide having an average particle size of 120 nm to 500 nm are used in combination. 3. The magnetic recording medium according to 1 or 2. 4. The transparent conductive layer has an oxide mainly composed of tin oxide and a binder, and the weight ratio of the oxide and the binder is 40/60 to 70/60. 4. The magnetic recording medium according to 1, 2, or 3. 5. The magnetic recording medium according to claim 1, wherein the transparent conductive layer is treated by a calender before and / or after the application of the magnetic layer. 6. The magnetic recording medium according to claim 1, wherein the binder of the transparent conductive layer is a hydrophilic binder having an amide bond. 7. The transparent conductive layer is provided on a polyester-based support after film formation, and before or after the formation of the transparent conductive layer, a coating layer mainly composed of gelatin is used as the outermost layer as the transparent conductive layer. 7. The magnetic recording medium according to claim 1, wherein the polyester support is provided with an antistatic treatment on the surface on the opposite side of the magnetic recording medium. 8. A magnetic recording medium in which a transparent magnetic layer is formed on a transparent magnetic layer, wherein the conductive material particles mainly composed of tin oxide and the conductive material particles having an average particle size of 10 to 90 nm and an acicular average length. A magnetic recording medium comprising a combination of conductive material particles having an axis length of 120 nm to 800 nm.