JPH10289438A - Magnetic recording medium having abrasive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly and surely perform the input and output of magnetic information by having an abrasive layer containing >=60 wt.% of total abrasive and a magnetic recording layer containing >=60 wt.% of total magnetic material on one side of a supporting body and making the average particle diameter of the abrasive larger than the dry film thickness of the abrasive layer to improve the durability of the magnetic recording layer and the cleaning property of a magnetic head. SOLUTION: The abrasive to be used is a non-magnetic inorganic powder having a Moh's hardness of >=5, preferably >=6 and aluminum oxide, chromium oxide, silicon dioxide, titanium dioxide and the like are embodied. The average particle diameter is preferably 0.2-5.0 μm. The abrasive is dispersed in a well- known binder and applied with 10-55 mg/m<2> coating night. The ferromagnetic powder is well-known one, preferably has 400 Å size of crystallite, >= 20 m<2> /g BET value and is dispersed in the same solvent to be preferably used in an amount of 4×10<-4> g per 1 m<2> . The abrasive layer and the magnetic layer are applied by multiply simultaneous coating system on a supporting body in this order.

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, and more particularly, to a magnetic recording medium with improved cleaning and durability of a magnetic head.

[0002]

2. Description of the Related Art Generally, a magnetic recording medium reads and writes information with a magnetic head. In order to quickly and accurately input and output information, the magnetic recording medium and the magnetic head must always be in an optimal environment. . However, due to the contact between the surface of the magnetic recording medium, in which the magnetic particles mainly composed of iron oxide are dispersed in the synthetic polymer binder, and the magnetic head, which is a metal, dust, dust, In some cases, dust or components of the magnetic recording medium adhere and cause clogging, which may hinder information input / output.

[0003] These problems are almost completely eliminated by cleaning the magnetic head.
Even if it is effective against dust, dust, and dust, it is not perfect against the adhesion of components of the magnetic recording medium. Further, the preparation of the cleaning member and the trouble of the cleaning still exist.

In recent years, silver halide color photographic materials (hereinafter simply referred to as photographic materials) have been used for photographing (image exposure).
There has been a proposal to record information such as photographing conditions on a silver halide color photosensitive material for effective use in order to more efficiently perform later development processing and printing on photographic paper with high accuracy.

US Pat. No. 4,947,196 and WO 90/04254 disclose a roll-shaped film and a magnetic head having a magnetic layer containing magnetic particles capable of magnetic recording on the back surface of a photographic film. An imaging camera having the same is disclosed. According to the above-described improved technology, the identification information of the type and maker of the photosensitive material, information on the conditions at the time of photographing, information on the customer, information on the printing conditions, information on the conditions for additional printing, etc. are recorded on the magnetic layer on the film. By magnetically inputting / outputting the data, it is possible to improve the print quality, increase the efficiency of the printing operation, increase the efficiency of the lab work, and the like.

That is, it can be said that the magnetic recording medium is provided on one side of the support and the photographic constituent layer is provided on the other side, and is an epoch-making recording medium having both magnetic information and optical image information.

However, there is a problem of the clogging of the magnetic head, and a new clogging factor relating to the photographic constituent layer and its developing process is added.

The cleaning of the magnetic head performed from the side of the magnetic recording medium is performed by incorporating an abrasive such as aluminum oxide into the magnetic recording medium itself and polishing the surface of the magnetic head with the abrasive when the magnetic head is running. Is going.

Conventionally, only the outermost magnetic recording layer contains an abrasive. When an abrasive having a small particle size is used, a large amount of abrasive is required to obtain a sufficient polishing force, and an abrasive having a large particle size must be selected when the amount of the abrasive is small. In each case, the content of the particle component in the magnetic recording layer is increased, and the magnetic recording layer is likely to be brittle. When the magnetic head is running, these abrasives easily fall off, and the durability is remarkably deteriorated.

Further, in JP-A-8-17047 and JP-A-8-50340, an abrasive having a center particle diameter of 0.2 to 0.4 μm is contained in a binder having a thickness of 0.2 to 0.4 μm. Although a method is disclosed in which an abrasive layer is provided outside the magnetic recording layer, the abrasive center particle size is small with respect to the thickness of the binder, and a sufficient polishing effect cannot be obtained.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the durability of a magnetic recording layer and improve the cleaning performance of a magnetic head, so that magnetic information can be input and output quickly and reliably. To provide a medium.

[0012]

The above object of the present invention has been attained by the following constitutions.

(1) On one side of the support, an abrasive layer containing 60% by weight or more of the total abrasive, and 6% of the total magnetic material
A magnetic recording medium comprising: a magnetic recording layer containing 0% by weight or more, and wherein the average particle size of the abrasive in the abrasive layer is larger than the dry film thickness of the abrasive layer.

(2) An abrasive coating solution containing at least 60% by weight of the total abrasive and a magnetic material coating solution containing at least 60% by weight of the total magnetic material are coated on one side of the support with a multilayer. A magnetic recording medium characterized by being simultaneously layered.

(3) The average particle size of the abrasive in the abrasive layer is larger than the sum of the dry thickness of the abrasive layer and the dry thickness of the magnetic recording layer (1) or (2) The magnetic recording medium according to (2).

(4) The method according to any one of (1) to (3), wherein a magnetic recording layer is provided on a farther side and a polishing agent layer is provided on a closer side to the support. Magnetic recording medium.

That is, the present inventors have conducted various studies in order to solve the above-mentioned object of the present invention. As a result, the present inventors have found that an abrasive layer containing 60% by weight or more of the total abrasive, The abrasive had a magnetic recording layer containing at least 60% by weight of the body, and the average particle size of the abrasive in the abrasive layer was larger than the dry film thickness of the abrasive layer. Furthermore, by providing both the abrasive layer coating solution and the magnetic recording layer coating solution simultaneously or sequentially by so-called wet-on-wet multi-layer simultaneous coating, a magnetic recording medium having high durability and excellent magnetic head cleaning properties can be obtained. The present invention will be described in detail below, which can be obtained and can achieve the object of the present invention.

Examples of the abrasive used in the present invention include non-magnetic inorganic powders having a Mohs hardness of 5 or more, preferably 6 or more. Specifically, aluminum oxide (α-alumina, γ-alumina, corundum, etc.) ), Chromium oxide (Cr
₂ O ₃ ), oxides such as iron oxide (α-Fe ₂ O ₃ ) silicon dioxide and titanium dioxide, and fine powders such as diamond. The average particle size is preferably 0.02 to 5.0 μm, and more preferably 0.2 to 5.0 μm. It can be added in the range of 0.5 to 300% by weight based on the magnetic substance powder. 5-10 abrasives on one side on the support
0 mg / m ² , and 10-55
It is preferable to apply in the range of mg / m ² .

The ferromagnetic fine powder used in the present invention includes ferromagnetic iron oxide fine powder, Co-doped ferromagnetic iron oxide fine powder,
Ferromagnetic iron dioxide fine powder, ferromagnetic chromium dioxide fine powder, ferromagnetic metal powder, barium ferrite and the like can be used.

The ferromagnetic powder used in the present invention 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 surface area are not particularly limited, but the crystallite size is 400 mm or more, and the BET value is 20 m.
^It is preferably at least ² / g, particularly preferably at least 30 m ² / g. The pH, surface treatment, and the like of the ferromagnetic powder can be used without any particular limitation. The preferred pH range is 5-10. In the case of ferromagnetic iron oxide fine powder, the ratio of divalent iron / trivalent iron can be used without any particular limitation.

In the present invention, the preferred amount of the magnetic powder is 4 × 10 ⁻⁴ g or more per 1 m ^{2 of} the magnetic recording medium. Further, the upper limit is that the optical density of the 436 nm wavelength light is 1.5.
Any amount may be used as long as it is below, but the limit is about 4 g per m ² . If it is more than this, when it is applied to a photographic light-sensitive material, it has an optical effect on the photographic constituent layers.

The binder constituting the abrasive layer and the magnetic recording layer in the present invention is a thermoplastic resin, a radiation-curable resin, a thermosetting resin, and other reactive resins.
These can be used alone or in combination.

Examples of the thermoplastic resin include cellulose resins (cellulose derivatives such as cellulose acetate and nitrocellulose), vinyl chloride-vinyl acetate resin, vinyl chloride resin, vinyl acetate resin, vinyl acetate-vinyl alcohol copolymer, and chloride resin. Vinyl-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, ethylene-vinyl alcohol copolymer, chlorinated polyvinyl chloride,
Ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, maleic acid-acrylic acid copolymer, acrylate copolymer, polyvinyl butyral resin, saturated polyester resin, polyurethane resin, polyamide resin, amino resin, styrene Examples thereof include butadiene resin, silicone resin, and fluorine-based resin.

These can be used as an aqueous emulsion or an aqueous colloid solution.

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 the like.

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

The binders listed above may have a polar group in the molecule. Epoxy group as the polar group,-
COOM, -OH, -N (R) 2, -N (R) 3 X, -S
_{O 3 M, -OSO 3 M,} -PO 3 M 2, -OPO 3 M (M,
M ₂ represents a hydrogen atom, an alkali metal atom and ammonium, X represents an acid forming an amine salt, (R) ₂ ,
(R) ₃ represents a hydrogen atom or an alkyl group, respectively. ).

Other hydrophilic binders usable in the present invention include, for example, Research Disclosure No. 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, maleic anhydride copolymers, etc. Examples of the ether include 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 reactive halogens, compounds having reactive olefins, N-methylol compounds, aziridine compounds, acid derivatives, and epoxy compounds. , Halogen carboxaldehydes, chromium ban, zirconium sulfate, carboxyl group activated hardener and the like. The hardener is
Usually, it is used in an amount of 0.01 to 60% by weight, preferably 0.05 to 50% by weight, based on the solid content of the resin.

In the present invention, if necessary, one or both of the abrasive layer and the magnetic recording layer may be crosslinked. Examples of the crosslinking agent that can be used include aldehyde compounds, ketone compounds, compounds having a reactive halogen, compounds having a reactive olefin, N-hydroxymethylphthalimide, N-methylol compounds, isocyanates, and aziridine compounds. , Acid derivatives, epoxy compounds, halogen carboxaldehydes and inorganic crosslinking agents.

The crosslinking agent is usually used in an amount of 0.0
It is used in an amount of 1 to 30% by weight, preferably 0.05 to 20% by weight.

When preparing the coating solution for the abrasive layer and the magnetic recording layer of the present invention, when the above components are dissolved or uniformly dispersed in an organic solvent and coated on a support, any part has a uniform composition. To be.

Examples of the organic solvent include alcohols such as methanol, ethanol, isopropyl alcohol and butanol; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers and glycol dimethyl ether. , Glycol monomethyl ether, ether solvents such as dioxane, aromatic hydrocarbon solvents such as benzene, toluene, xylene, chlorinated hydrocarbons such as methylene chloride, ethylene chloride carbon tetrachloride, chloroform, ethylene chlorohydrin, N,
There is a mixed solvent in which N-dimethylformamide, hexane, water and the like are used alone or mixed at an appropriate ratio.

In the present invention, the dry film thickness of the abrasive layer and the magnetic recording layer is preferably 0.01 to 10 μm, respectively.
0.1-5.0 micrometers is more preferable. Further, the total dry film thickness of the abrasive layer and the magnetic recording layer is preferably 0.1 to 5.0 μm.

The relation between the thickness of the binder in the abrasive layer and the center particle size of the abrasive is preferably such that the ratio of the center particle size of the abrasive / the thickness of the binder is 1.0 to 2.5, more preferably 1.25 to 1.7. Is more preferred.

A magnetic material can be contained in the abrasive layer, and an abrasive can be contained in the magnetic recording layer. The amount of the magnetic substance and the abrasive that can be contained in each layer is such that the abrasive particles in the abrasive layer are 60% by weight or more of the total abrasive amount, and the magnetic recording layer is 60% by weight or more of the total magnetic substance amount. Is preferred. If the amount of the abrasive in the abrasive layer is less than 60% by weight, a sufficient magnetic head cleaning effect cannot be obtained. Further, even when the amount of the abrasive in the abrasive layer is 60% by weight or more, if the abrasive layer contains more than 40% by weight of the magnetic material,
Although the magnetic head cleaning effect is obtained, the content of the abrasive layer increases, so that abrasive particles and the like fall off,
It degrades durability. Therefore, it is necessary to contain the magnetic material in the magnetic recording layer at 60% by weight or more.

In order to impart functions such as imparting lubricity, preventing static electricity, preventing adhesion, and improving friction and abrasion characteristics to the coating liquid for forming the abrasive layer and the magnetic recording layer, various kinds of lubricants and antistatic agents are used. Additives can be added. For example, a plasticizer may be added to the coating solution to give flexibility to the abrasive layer and the magnetic recording layer, and a dispersant may be added to aid dispersion of the abrasive and the magnetic substance in the coating solution. The above-mentioned functions of imparting lubricity, preventing static electricity, improving friction and wear characteristics include an abrasive layer,
These functional layers may be provided separately from the magnetic recording layer.

As a method for imparting lubricity, a lubricant can be added to the adjacent layer and / or a lubricant can be added to the outermost layer. Further, a lubricant may be applied outside the outermost layer as an overcoat layer without a binder.
The method of applying the lubricant without a binder is not particularly limited, and examples thereof include a method in which the lubricant is applied by dissolving with a solvent, and a method in which the lubricant is emulsified and the dispersion liquid is applied. Can be

Examples of the lubricant that can be used in the magnetic recording layer of the present invention include silicone oils such as polysiloxane, plastic fine powders such as polyethylene and polytetrafluoroethylene, higher fatty acids, higher fatty acid esters, paraffin wax, and fluorocarbons. Can be Specifically, these can be used alone or as a mixture.
The amount of these additives is 0.5 to 100 parts by weight of the dried coating film.
It can be used in the range of up to 20 parts by weight. Those that can be dissolved or diffused in water are preferred.

The antistatic agent that can be used in the present invention includes:
Antistatic agents generally useful for silver halide photographic materials,
Most of the antistatic compositions can be used.

In the antistatic layer before the outermost layer of the present invention is applied, almost all antistatic compositions useful for silver halide photographic materials can be used. For example, JP-B-47-28937 or JP-B-49-23
Styrene-sodium maleate copolymer described in JP-A-828, sodium vinylbenzyl sulfonate copolymer described in JP-A-53-82876, JP-B-48-23451.
Anionic antistatic agents such as polymers or copolymers of sodium styrene sulfonate described in JP-A-51-42
No. 535, JP-A-54-159222 and JP-A-55-159222.
No. 7763 Ionene polymer (for example, a polymer of triethylenediamine and xylidene dichloride),
For example, polymethacryloylethyldiethylmethylammonium methylsulfonate described in U.S. Pat. No. 2,882,157, JP-B-60-51693, JP-A-6
No. 1,223,736 and Japanese Unexamined Patent Publication No. 62-9346, crosslinked copolymer particles having a quaternary ammonium group in the side chain (for example, copolymer [N, N, N-trimethyl-N-
Vinylbenzylammonium chloride-co-divinylbenzene]), cationic antistatic agents such as ionomer polymer cross-linked or copolymer particles having an ionene polymer in the side chain described in Japanese Patent Application No. 5-174572 (for example, polyvinyl benzyl). Cross-linking reaction product of chloride and terminal N- (polymer of triethylenediamine and xylidenedichloride), those having an alumina sol described in JP-B-57-12979 as a main component and described in JP-A-57-104931. ZnO, SnO ₂ , TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ ,
_{SiO 2, MgO, BaO, MoO} 3, ZiO particulate metal oxides such as _2, metal oxide antistatic agents such as V ₂ O ₅ described in JP-B-55-5982, higher fatty described in JP-B-52-32572 Alcohol phosphate ester antistatic agent, poly (isothianaphthene) based on JP-A-2-252726, JP-A-2-255770 or JP-A-2-3
And a conjugated double bond conductive polymer such as poly (thiophene) described in JP 08246. In particular, among the above antistatic agents, alkali metal sulfonic acid types such as a copolymer of sodium styrene sulfonate described in JP-B-48-23451 and a copolymer of sodium vinylbenzyl sulfonate described in JP-A-53-82876. Anion polymer antistatic agent; ionene polymer represented by a polymer comprising dihalide such as triethylenediamine and xylidene dichloride described in JP-A-54-159222;
174572, a condensate of a diamine such as triethylenediamine and a dihalide such as xylidene dichloride, or an ionene crosslinked copolymer particle in which an ionene polymer serves as a crosslinker for a vinyl copolymer; Quaternary triethylenediamines such as ionicene side chain pendant crosslinked copolymer particles in which a condensate or polymer comprising a diamine such as ethylenediamine and a dihalide such as xylidene dichloride is bonded to the side chain of a crosslinked vinyl copolymer Cationic ionizer polymer antistatic agent comprising as a constituent quaternary benzylamine cationic polymer such as crosslinked copolymer particles having a benzyltrialkylammonium chloride group in the side chain described in JP-B-60-51693. antistatic agents, SnO _2, T described in JP 57-10431 _{O 2, ZnO, In 2 O} 3, SiO 2,
MoO ₃ , WO ₃ metal oxides and / or crystalline metal oxide fine powder antistatic agents mainly composed of these metal composite oxides, alumina sol composition described in JP-B-57-12979, JP-A-2-252726 No., JP-A-2-25577
No. 0, JP-A-2-308246 and the like.
-Dodecylbenzothiophene), poly- (3-dodecylthiophene), methacryloylethyloxymethyl-3
-A polythiophene-based conductive polymer antistatic agent having a conjugated double bond represented by polythiophene and the like is preferable, and polyfuran and polypyrrole are also useful.

The plasticizer is not particularly restricted but preferably includes, for example, dioctyl phthalic acid (DOP), dibutyl phthalic acid (DBP), triphenyl phosphate (TPP) and tricresyl phosphate (TCP). These can be used alone or as a mixture.

The method for providing the abrasive layer and the magnetic recording layer of the present invention on a support includes an extrusion coater,
Air doctor coat, blade coat, air knife coat, squeeze coat, impregnation coat, reverse roll coat, transfer roll coat, gravure coat, kiss coat, cast coat, spray coat and the like can be used. In order to perform multiple stripe coating, these coating heads may be formed in multiples. As a specific method of stripe coating, for example, JP-A-48-25503
Nos. 48-25504, 48-98803, 50-138037, 52-15533, 51
No.-3208, No.51-6239, No.51-6560
No. 6, No. 51-140703, Japanese Patent Publication No. 29-4221
No. 3,062,181, U.S. Pat.
No. 165 can be referred to.

The abrasive layer and the magnetic recording layer of the present invention may be sequentially coated by a so-called wet-on-dry method, but may be coated on a support by a multi-layer simultaneous coating method, a so-called wet-on-wet coating method. More preferably, it is provided.

In the present invention, the wet-on-wet coating method in which the abrasive layer and the magnetic recording layer are provided is a method in which one layer is first coated and then the next layer is coated thereon as soon as possible in a wet state. It refers to a method of applying by a sequential coating method, a multi-layer simultaneous extrusion coating method, and the like.

As a wet-on-wet coating method, a magnetic recording medium coating method disclosed in JP-A-61-139929 can be used. An apparatus used in a wet-on-wet coating method is disclosed in JP-A-2-25126.
5, JP-A-3-153, JP-A-3-161, JP-A-3-162 and JP-A-3-163 can be referred to.

FIGS. 1 (a) to 1 (e) illustrate various examples of a coating method used for providing an abrasive layer and a magnetic recording layer in the present invention. FIG. 1 (a) shows a wet-on
1 shows an extrusion coating coater used in a dry coating method. In this figure, the coating liquid injector 22 is located between the rolls supporting the support 1, but as shown in FIG. 1B, the coating liquid injector 22 is located on the opposite side of the roll supporting the support. 23 may be provided to apply the coating liquid 8. FIG. 1 (c) and subsequent figures show an apparatus used in a wet-on-wet coating method, and FIG. 1 (c) shows an apparatus using a simultaneous multi-layer coating liquid injector 24 on a support 1 such as polyethylene terephthalate which runs continuously. This shows a state in which the lower layer coating liquid 11 and the upper layer coating liquid 10 are simultaneously coated. FIG.
In (c), the coating liquid injector is located between the rolls supporting the support similarly to FIG. 1 (a), but the simultaneous multilayer coating liquid injector as shown in FIG. 1 (d). A simultaneous multilayer coating liquid injector 25 may be provided on the opposite side of the roll supporting the support. FIG. 1 (e) shows that the lower layer coating solution 11 is applied to the support 1 using the single layer coating liquid injector, and then another lower layer coating solution 11 is wet. Is applied by the coating liquid injection device 27 of FIG.

An undercoat layer may be provided on the support in order to firmly adhere the abrasive layer and the magnetic recording layer on the support.
The surface of the support is subjected to surface treatment such as chemical treatment, mechanical treatment, corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, laser treatment, agricultural production treatment, ozone oxidation treatment, etc. May be. Further, an undercoat layer may be provided after the surface treatment.

There is no particular limitation on the undercoat layer, but examples thereof include JP-A-59-19941 and JP-A-59-77439.
Copolymer disclosed in JP-A-57-12
No. 8332, a copolymer of a diolefin monomer and a vinyl monomer. JP-B-43-3976, JP-A-6-39
Examples thereof include a layer containing a vinylidene chloride copolymer described in JP-A-4-538 and JP-A-3-137637.

In these undercoat layers, a conductive substance, an antihalation agent, a crossover cut agent,
Coloring dyes, pigments, coating aids, antifoggants, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, etching agents,
One or more of various additives such as a matting agent may be contained.

After the magnetic recording layer is provided, the layer is subjected to a calendering process to improve the smoothness and to improve the S / N of the magnetic output.
It is also possible to improve the ratio.

In the present invention, as the support, polyester films such as polyethylene terephthalate and polyethylene naphthalate; cellulose ester films such as cellulose triacetate and cellulose diacetate;
Examples include a polycarbonate film, a polystyrene film, and a polyolefin film.

In particular, when these are used in a silver halide photographic light-sensitive material, it is difficult to recover the curl after development processing.
Nos. 244446, 1-291248, 1-298
No. 350, No. 2-89045, No. 2-93641,
It is preferable to use a polyester film having a high water content, as described in JP-A-2-181748, JP-A-2-214852 and JP-A-2-291135.

Further, 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-providing agent are provided on the support. , A thickener, an antioxidant, and the like.

The support is used for the purpose of neutralizing the color of the minimum density portion, preventing the light piping phenomenon (edge fogging) that occurs when light enters the film coated with the photographic constituent layer from the edge, and preventing halation. Dyes can be included.

The type of the dye is not particularly limited, but when a polyester film is used as the support, those having excellent heat resistance in the film forming step are preferable, and examples thereof include an anthraquinone-based chemical dye. As for the color tone, when the purpose is to prevent light piping, gray dyeing is preferable as seen in general photosensitive materials. The dyes may be used alone or in combination of two or more. Diaresin, Bayer manufactured by Mitsubishi Chemical Corporation
The target can be achieved by using a dye such as MACROLEX manufactured by the company alone or in an appropriate mixture.

A photographic component layer can be provided on the side opposite to the magnetic recording layer of the magnetic recording medium of the present invention. As the photographic constituent layer, a known technique in the art can be used.

In the present invention, the silver halide emulsion may be selected from Research Disclosure No. 308119 (hereinafter R
D308119).

The following shows the places to be described.

[Items] [Page RD 308119] Iodine composition 993 IA section Production method 993 IA and 994 E crystal wall normal crystal 999 IA twin twin 1993 IA section Epitaxial 933 I -A halogen composition uniform 993 IB non-uniform 993 IB halogen conversion 994 IC halogen substitution 994 IC metal-containing 994 ID monodispersion 975 IF solvent added Item 995 I-F Latent image forming position Surface 995 I-G Inside 995 I-G Applicable photosensitive material negative 995 I-H Positive (including internal fog particles) 995 I-H Item Emulsion mixed 995 I Section J Desalting 995 II-A In the present invention, a silver halide emulsion which has been subjected to physical ripening, scientific ripening and spectral sensitization is used. Additives used in such a process are described in Research Disclosure No. 17643, no. 18716 and no. 308
119 (hereinafter RD17643 and RD1871 respectively)
6 and RD308119).

The following shows the places to be described.

[0064]

[Table 1]

Known photographic additives which can be used in the present invention are also described in the above-mentioned Research Disclosure.

The following is a description of relevant places.

[0067]

[Table 2]

Various couplers can be used in the present invention, and specific examples thereof are described in the above-mentioned Research Disclosure.

The following describes relevant portions.

[0070]

[Table 3]

The additive used in the present invention is RD3081
It can be added by the dispersion method described in 19XIV.

In the present invention, the aforementioned RD17643
Page 28, RD18716 pages 647 to 648, and RD3
The support described in XIX of 08119 can be used.

The photographic constituent layer used in the present invention may be provided with an auxiliary layer such as a filter layer or an intermediate layer described in RD308119VII-K.

The photographic constituent layer used in the present invention is the same as that of the aforementioned R
Various layer configurations such as a normal layer, a reverse layer, and a unit configuration described in D308119VII-K can be employed.

To develop the photographic component layer used in the present invention, for example, H. James, Theory of the Photographic Process 4th Edition (The
Theory of The Photographic
Process Forth Edition) 2
Pages 91-334 and Journal of the American Chemical Society (Journal of the American Chemical Society)
the American Chemical Soc
iey) Developers known per se described in Vol. 73, page 3, 100 (1951) can be used. Further, the color photographic constituent layer is the same as that of the aforementioned RD1764.
3 pages 28-29, RD18716 page 615 and RD
Development processing can be carried out by the usual method described in 308119 XIX.

[0076]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto.

Example 1 Preparation of Magnetic Recording Medium << Preparation of Support >> 0.1 part by weight of calcium acetate hydrate as a transesterification catalyst was added to 100 parts by weight of dimethyl 2,6-naphthalenedicarboxylate and 60 parts by weight of ethylene glycol. After the addition, a transesterification reaction was carried out according to a conventional method.
To the obtained product, 0.05 parts by weight of antimony trioxide,
0.03 parts by weight of trimethyl phosphate was added.
Then, gradually raise the temperature and reduce the pressure, 290 ° C, 0.05 mm
Polymerization was performed under the conditions of Hg to obtain polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.60.

This was vacuum-dried at 150 ° C. for 8 hours, melt-extruded in a layer form from a T-die at 300 ° C., brought into close contact with a 50 ° C. cooling drum while applying static electricity, cooled and solidified, and an unstretched sheet was obtained. Obtained. This unstretched sheet was stretched 3.3 times in the machine direction at 135 ° C. using a roll-type longitudinal stretching machine.

The obtained uniaxially stretched film was stretched in a first stretching zone at 145 ° C. by 50% of the total transverse stretching ratio using a tenter type transverse stretching machine, and further at a second stretching zone at 155 ° C. at a total transverse stretching ratio of 3. The film was stretched three times. Then 10
Heat treated at 0 ° C for 2 seconds, and further heat-fixed zone 200 ° C
For 5 seconds and a second heat setting zone at 240 ° C. for 15 seconds. Next, the film was gradually cooled to room temperature over 30 seconds while performing a 5% relaxation treatment in the lateral direction to obtain a polyethylene naphthalate film having a thickness of 85 μm.

This is wound around a stainless steel core, and
A heat treatment (annealing treatment) was performed at 10 ° C. for 48 hours to form a support.

On both sides of this support, 12 W / m ² / min
On one side, the following undercoating coating solution B
-1 is applied so as to have a dry film thickness of 0.4 μm, and a corona discharge treatment of 12 W / m ² / min is applied thereon, so that the undercoating coating solution B-2 described below has a dry film thickness of 0.06 μm. Was applied.

On the other surface subjected to the corona discharge treatment of 12 W / m ² / min, the following undercoating coating solution B-3 was applied to a dry film thickness of 0.2 μm, and 12 W / m ² / min. ^Two
/ Min, and a coating liquid B-4 shown below was applied to a dry film thickness of 0.2 μm.

Each of the layers was dried at 90 ° C. for 10 seconds after the application, and after the four layers were applied, heat-treated at 110 ° C. for 2 minutes, and then cooled at 50 ° C. for 30 seconds.

<Undercoat Coating Solution B-1> A copolymer latex liquid of 30% by weight of butyl acrylate, 20% by weight of t-butyl acrylate, 25% by weight of styrene and 25% by weight of 2-hydroxyethyl acrylate (solid content: 30% 125 g Compound (UL-1) 0.4 g Hexamethylene-1,6-bis (ethylene urea) 0.05 g Finish with water 1000 ml <Subbing coating solution B-2> Hydroxidation of styrene-maleic anhydride copolymer Sodium aqueous solution (solid content 6%) 50 g Compound (UL-1) 0.6 g Compound (UL-2) 0.09 g Silica particles (average particle size 3 μ) 0.2 g Finish with water 1000 ml <Coating solution B-3> Butyl 30% by weight of acrylate, 20% by weight of t-butyl acrylate, 25% by weight of styrene and 25 of 2-hydroxyacrylate % By weight of copolymer latex liquid (solid content 30%) 50 g Compound (UL-1) 0.3 g Hexamethylene-1,6-bis (ethylene urea) 1.1 g Finish with water 1000 ml

[0085]

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<Coating solution B-4> 60 mol% of dimethyl terephthalate, 30 mol% of dimethyl isophthalate, 10 mol% of a sodium salt of dimethyl 5-sulfoisophthalate, 50 mol% of ethylene glycol as a glycol component, 50 mol% of diethylene glycol was copolymerized by a conventional method. The copolymer was stirred in hot water at 95 ° C. for 3 hours to obtain a 15% by weight aqueous dispersion A.

Aqueous dispersion of tin oxide-antimony oxide composite fine particles (average particle size: 0.2 μm) (solid content: 40% by weight) 109 g Aqueous dispersion A 67 g Water Adjusted so that the finish becomes 1000 ml << Coating of magnetic recording layer A coating liquid for an abrasive layer and a coating liquid for a magnetic recording layer having the following composition were prepared on the surface coated with the coating liquid for the undercoat layer B-4 of the undercoated treatment support as follows.
Apply.

A. Preparation and application of abrasive layer coating solution and magnetic recording layer coating solution Preparation of Abrasive Dispersion 1 The abrasives, binders, and solvents shown in Table 4 were charged into a sand grinder and dispersed for 4 hours to prepare an abrasive dispersion 1.

[0089]

[Table 4]

2. Preparation of Magnetic Material Dispersion 1 A magnetic material, a binder and a solvent described in Table 5 were charged into a sand grinder and dispersed for 4 hours to prepare a magnetic material dispersion 1.

[0091]

[Table 5]

3. Preparation of Abrasive Layer Coating Solution A-1 A binder dissolving solution is prepared by gradually adding a binder and dissolving the binder while stirring the solvent, as shown in the type and amount shown in Table 6. The dispersion 1 of the magnetic substance and the dispersion 1 of the abrasive were added thereto as shown in Table 6, dispersed by a sand grinder for 1 hour, and a hardener was added, followed by sufficient stirring and mixing to obtain an abrasive layer coating liquid A-1. Was.

[0093]

[Table 6]

4. Preparation of Coating Solutions A-2 and A-3 for Abrasive Layer Except that the abrasive type (HIT-30) of Abrasive Dispersion 1 (Table 4) was changed as shown in Table 7 (however, except that the parts by weight were equal). Is the same as the abrasive dispersion (the abrasive concentration is the same as the abrasive dispersion 1).
B / A = 22% by weight and solid content concentration = 40% by weight) were prepared, and then used in the same manner as in the case of the coating solution A-1 for the polishing agent layer, as shown in Table 7. Layer coating solutions A-2 and A-3 were prepared.

[0095]

[Table 7]

[0096] 5. Preparation of Coating Solution M-1 for Magnetic Recording Layer As shown in Table 8, the binder is gradually added while the solvent is being stirred and the binder is dissolved to prepare a binder solution. As shown in Table 8, magnetic material dispersion 1 and abrasive dispersion 1 were added thereto, dispersed by a sand grinder for 1 hour, and a hardener was added, followed by sufficient stirring and mixing to obtain a magnetic recording layer coating solution M-1. Was.

[0097]

[Table 8]

6. Preparation of Coating Solutions M-2 and M-3 for Magnetic Recording Layer Except that the abrasive type (HIT-30) of Abrasive Dispersion 1 (Table 4) was changed as shown in Table 9 (however, except for equal parts by weight). Is the same as the abrasive dispersion (the abrasive concentration is the same as the abrasive dispersion 1).
B / A = 22% by weight and solid content concentration = 40% by weight), and then used in the same manner as in the case of the abrasive layer coating solution M-1 to obtain an abrasive as shown in Table 9. Layer coating solutions M-2 and M-3 were prepared.

[0099]

[Table 9]

7. Preparation of Magnetic Recording Layer Coating Solution M-4 As shown in Table 10, the binder is gradually added while the solvent is being stirred and the binder is dissolved to prepare a binder solution. As shown in Table 10, magnetic material dispersion 1 and abrasive dispersion 4 were added thereto, dispersed by a sand grinder for 1 hour, and a hardener was added thereto, followed by sufficient stirring and mixing to obtain a magnetic recording layer coating liquid M-4. Was.

[0101]

[Table 10]

8. Preparation of Coating Solutions M-5 and M-6 for Magnetic Recording Layer As shown in Table 11, Magnetic dispersion 1 was added. Further, the abrasive dispersion was prepared by changing the kind of the abrasive as shown in Table 11, and the abrasive concentration was the same as that of the abrasive dispersion 1, ie, B / A = 22% by weight and solid content concentration = 40% by weight. . This abrasive dispersion was added, and the magnetic recording layer coating solutions M-5 and M-6 were added.
Was prepared.

[0103]

[Table 11]

9. Preparation of Abrasive Dispersion 4 An abrasive, a binder and a solvent shown in Table 12 were charged into a sand grinder and dispersed for 4 hours to prepare an abrasive dispersion 4.

[0105]

[Table 12]

10. Preparation of Abrasive Layer Coating Solution 4 As shown in Table 13, a binder is gradually added to a solvent under stirring and the binder is dissolved to prepare a binder solution. Abrasive dispersion 4 was added thereto as shown in Table 13 and dispersed by a sand grinder for 1 hour. After adding a curing agent, the mixture was sufficiently stirred and mixed to obtain an abrasive layer coating liquid A-4.

[0107]

[Table 13]

11. Preparation of Magnetic Recording Layer Coating Solution M-7 As shown in Table 14, a binder is gradually added to a stirring solvent and the binder is dissolved to prepare a binder solution. The magnetic material dispersion 1 (described in Table 5) and the abrasive dispersion 4 were added thereto, and dispersed by a sand grinder for 1 hour.
After adding the curing agent, the mixture was sufficiently stirred and mixed, and the magnetic recording layer coating solution M-
7 was obtained.

[0109]

[Table 14]

12. Coating of Abrasive Layer and Magnetic Recording Layer Coating was performed so as to conform to the level shown in Table 17 (Sample Nos. 101 to 113). The coating was carried out by the method shown in FIG. 1A for the wet-on-dry coating method and the simultaneous multilayer coating by the method shown in FIG. 1C for the wet-on-wet coating method. Sample No. 10
The dried film thicknesses of 1 to 108 and 112 and 113 were 0.4 μm for both the upper and lower layers, and 0.8 μm for the upper and lower layers. Sample No. consisting of only the magnetic recording layer Nos. 109 to 111 were applied so that the dry film had a thickness of 0.8 μm. At the same time as the drying, the magnetic material was oriented in the application direction in an orientation magnetic field while the coating film was not dried, thereby increasing the output during magnetic recording and reproduction.

B. Preparation and application of coating liquid for lubricant layer Preparation of Lubricant Layer Coating Solution As shown in Table 15, the solvent (carnauba wax) was dissolved while heating the solvent to 70 ° C. and stirring.
The temperature was lowered to 0 ° C. to obtain a lubricant layer coating solution.

[0112]

[Table 15]

[0113] 2. Application of Lubricant Layer After the abrasive layer and the magnetic recording layer were applied and dried, they were applied using a precision extrusion coater. The dry film thickness of the lubricant layer was set to 10 nm at any level.

C. Heat treatment After the application of the lubricating layer, heat treatment was performed for 3 days in an oven heated to 60 ° C.

<< Coating of Photo Constituent Layer >> On the side of the magnetic recording medium opposite to the magnetic recording side, the above-mentioned undercoating coating solutions B-1 and B
-2 was provided under the same conditions as above, and a photographic component layer having the following composition was provided on the undercoat layer.
3 was obtained. The addition amount is expressed in grams per 1 m ^2. However, silver halide and colloidal silver were converted to the amount of silver, and sensitizing dyes (indicated by SD) were shown in moles per mole of silver.

Black Colloidal Silver 0.16 UV-1 0.3 CM-1 0.044 OIL-1 0.044 Gelatin 1.33 Second Layer (Intermediate Layer) AS-1 0.16 OIL-1 0.20 Gelatin 1.40 Third layer (low-sensitivity red-sensitive layer) Silver iodobromide a 0.12 Silver iodobromide b 0.50 SD-1 3.0 × 10 ^-5 SD-4 1.5 × 10 ^-4 SD-3 3.0 × 10 ^-4 SD-6 3.0 × 10 ^-6 C-1 0.51 CC-1 0.047 OIL-2 0.45 AS-2 0.005 Gelatin 1.40 Fourth layer (medium-speed red-sensitive layer) Silver iodobromide c 0.64 SD-1 3.0 × 10 ^-5 SD-2 1.5 × 10 ^-4 SD-3 3.0 × 10 ^-4 C-2.22 CC-1 0.028 DI-1 0.002 OIL-2 0.21 AS-3 0.006 Gelatin 0.87 Fifth layer (high sensitivity red Color-sensitive layer) Silver iodobromide c 0.13 Silver iodobromide d 1.14 SD-1 3.0 × 10 ^-5 SD-2 1.5 × 10 ^-4 SD-3 3.0 × 10 ^{− 4} C-2 0.085 C-3 0.084 CC-1 0.029 DI-1 0.027 OIL-2 0.23 AS-3 0.013 Gelatin 1.23 6th layer (intermediate layer) OIL- 1 0.29 AS-1 0.23 7th layer (low-sensitivity green color-sensitive layer) Silver iodobromide a 0.245 Silver iodobromide b 0.105 SD-6 5.0 × 10 ^-4 SD- 5 5.0 × 10 ^-4 M-1 0.21 CM-2 0.039 OIL-1 0.25 AS-2 0.003 AS-4 0.063 Gelatin 0.98 8th layer (intermediate layer) M -1 0.03 CM-2 0.005 OIL-1 0.16 AS-1 0.11 Gelatin 0.80 Ninth layer (medium-speed green-sensitive layer) Silver iodobromide e 0.87 SD-7 3.0 × 10 ^-4 SD-8 6.0 × 10 ^-5 SD-9 4.0 × 10 ^-5 M-1 0.17 CM-2 0.048 CM-3 0.0. 059 DI-2 0.012 OIL-1 0.29 AS-4 0.05 AS-2 0.005 Gelatin 1.43 10th layer (highly sensitive green color-sensitive layer) Silver iodobromide f 1.19 SD −7 4.0 × 10 ⁻⁴ SD-8 8.0 × 10 ⁻⁵ SD-9 5.0 × 10 ⁻⁵ M-1 0.09 CM-3 0.020 DI-3 0.005 OIL-1 0.11 AS-4 0.026 AS-5 0.014 AS-6 0.006 Gelatin 0.78 Eleventh layer (yellow filter layer) Yellow colloidal silver 0.05 OIL-1 0.18 AS-7 0.0. 16 Gelatin 1.00 12th layer (low-sensitivity blue-sensitive layer) Silver iodobromide g 0.29 Silver iodobromide h 0.19 ^{D-10 8.0 × 10 -4 SD} -11 3.1 × 10 -4 Y-1 0.91 DI-4 0.022 OIL-1 0.37 AS-2 0.002 Gelatin 1.29 Thirteenth Layer (highly sensitive blue-sensitive layer) Silver iodobromide h 0.13 Silver iodobromide i 1.00 SD-10 4.4 × 10 ^-4 SD-11 1.5 × 10 ^-4 Y-10 .48 DI-4 0.019 OIL-1 0.21 AS-2 0.004 Gelatin 1.55 Fourteenth layer (first protective layer) Silver iodobromide j 0.30 UV-1 0.055 UV-2 0.110 OIL-2 0.63 gelatin 1.32 15th layer (second protective layer) PM-1 0.15 PM-2 0.04 WAX-1 0.02 D-1 0.001 gelatin 0.55 In addition, in addition to the above composition, coating aids SU-1 and SU-
2, SU-3, dispersing aid SU-4, viscosity modifier V-1,
Stabilizers ST-1, ST-2, antifoggant AF-1, weight average molecular weight: 10,000 and weight average molecular weight: 1,
100,000 two types of polyvinylpyrrolidone (AF-
2), inhibitors AF-3, AF-4, AF-5, hardener H
-1, H-2 and the preservative Ase-1 were added.

The structure of the compound used in the above sample is shown below.

Table 16 shows the characteristics of the silver iodobromide.

[0119]

[Table 16]

[0120]

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[0121]

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[0122]

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[0123]

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[0124]

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[0125]

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[0126]

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[0127]

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[0128]

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Incidentally, as a preferred example of forming silver halide grains of the present invention, a production example of silver iodobromide d and f will be shown below.

Preparation of Seed Emulsion-1 A seed crystal emulsion was prepared as follows.

JP-B-58-58288, 58-58
No. 289, a silver nitrate aqueous solution (1.161 mol) was added to the following solution A1 adjusted to 35 ° C.
And a mixed aqueous solution of potassium bromide and potassium iodide (potassium iodide 2 mol%) while maintaining the silver potential (measured with a silver ion selective electrode using a saturated silver-silver chloride electrode as a reference electrode) at 0 mV. For 2 minutes to form nuclei. Subsequently, the temperature of the solution was raised to 60 ° C. over a period of 60 minutes, the pH was adjusted to 5.0 with an aqueous solution of sodium carbonate, and then an aqueous solution of silver nitrate (5.902 mol), potassium bromide and iodide were added. A mixed aqueous solution of potassium (2 mol% of potassium iodide) was added over 42 minutes by a double jet method while keeping the silver potential at 9 mV. After the addition was completed, the temperature was lowered to 40 ° C., and desalting and washing were immediately performed using a normal flocculation method.

The resulting seed crystal emulsion had an average sphere-equivalent diameter of 0.24 μm, an average aspect ratio of 4.8, and 90% or more of the total projected area of the silver halide grains had a maximum side ratio of 1.0.
~ 2.0 hexagonal tabular grains.
This emulsion is referred to as seed emulsion-1.

[Solution A1] Ossein gelatin 24.2 g Potassium bromide 10.8 g HO (CH ₂ CH ₂ O) _m (CH (CH ₃ ) CH ₂ O) _19.8 (CH ₂ CH ₂ O) _n H (m + n = 9.77) (10% ethanol solution) 6.78 ml 10% nitric acid 114 ml H ₂ O 9657 ml Preparation of silver iodide fine grain emulsion SMC-1 6.0% by weight gelatin aqueous solution containing 0.06 mol of potassium iodide While stirring 5 liters vigorously, 7.06
2 liters of an aqueous silver nitrate solution and 2 liters of a 7.06 mol aqueous potassium iodide solution were added over 10 minutes. During this time, the pH was controlled at 2.0 using nitric acid, and the temperature was controlled at 40 ° C. After the particles are prepared, the pH is adjusted using an aqueous sodium carbonate solution.
Was adjusted to 5.0. The average particle size of the obtained silver iodide fine particles was 0.05 μm. This emulsion is designated as SMC-1.

Preparation of silver iodobromide d 0.178 mol of seed crystal emulsion-1 and HO (CH ₂ CH ₂
O) _m (CH (CH ₃ ) CH ₂ O) _19.8 (CH ₂ CH ₂ O) _n
H (m + n = 9.77) in 10% ethanol solution 0.5
4.5% by weight of an aqueous inert gelatin solution 70
0 ml at 75 ° C., pAg 8.4, pH 5.0.
Then, particles were formed by the simultaneous mixing method with vigorous stirring by the following procedure.

1) A 2.1 mol silver nitrate aqueous solution and 0.19
5 mol of SMC-1 and an aqueous solution of potassium bromide were added to pA
g while maintaining the pH at 8.4 and the pH at 5.0.

2) Subsequently, the solution was cooled to 60 ° C.
Was adjusted to 9.8. Then, 0.071 mol of SMC
-1 was added and aging was performed for 2 minutes (introduction of dislocation lines).

3) 0.959 mol silver nitrate aqueous solution and 0.1 mol
03 mol of SMC-1 and an aqueous solution of potassium bromide were added to p
Ag was added at 9.8 and the pH was maintained at 5.0.

Each solution was added at an optimum rate throughout the particle formation so as to prevent formation of new nuclei and Ostwald ripening between particles. After completion of the addition, the resultant was subjected to a water washing treatment at 40 ° C. using a normal flocculation method, and then gelatin was added and redispersed to adjust the pAg to 8.1 and the pH to 5.8.

The obtained emulsion had a particle size (cubic 1 of the same volume).
The emulsion was composed of tabular grains having a halogen composition of 0.75 μm in side length, an average aspect ratio of 5.0, and a halogen composition of 2 / 8.5 / X / 3 mol% (X is a dislocation line introduction position) from the inside of the grains. . When this emulsion was observed with an electron microscope, five or more dislocation lines were observed both in the fringe portion and in the inside of the grain in 60% or more of the total projected area of the grain in the emulsion. The surface silver iodide content was 6.7 mol%.

Preparation of silver iodobromide f In the preparation of silver iodobromide d, pAg was adjusted to 8.8 in step 1).
The silver iodobromide f was prepared in exactly the same manner as the silver iodobromide d except that the amount of silver nitrate added in step 3) was 0.92 mol and the amount of SMC-1 was 0.069 mol. .

The obtained emulsion had a particle size (cubic 1 of the same volume).
An emulsion comprising tabular grains having a halogen composition of 0.65 μm, an average aspect ratio of 6.5, and a halogen composition of 2 / 8.5 / X / 7 mol% (X is a dislocation line introduction position) from the inside of the grains. . When this emulsion was observed with an electron microscope, five or more dislocation lines were observed both in the fringe portion and in the inside of the grain in 60% or more of the total projected area of the grain in the emulsion. The surface silver iodide content was 11.9 mol%.

After the above-mentioned sensitizing dyes were added to each of the above emulsions and ripened, triphosphine selenide, sodium thiosulfate, chloroauric acid and potassium thiocyanate were added, and the fogging and sensitivity were optimized according to a conventional method. Chemical sensitization was applied to obtain.

Silver bromoiodides a, b, c, e, g, h, and i were also subjected to spectral sensitization and chemical sensitization in accordance with d and f described above.

The samples 101 to 113 were subjected to the following magnetic head clogging evaluation test (undeveloped).
Further, the same exposure test was performed on the photographic component layer, which was subjected to image exposure and developed as described below.

(Processing step) Processing step Processing time Processing temperature Replenishment amount * Color development 3 minutes 15 seconds 38 ± 0.3 ° C. 780 ml Bleaching 45 seconds 38 ± 2.0 ° C. 150 ml Fixing 1 minute 30 seconds 38 ± 2. 0 ° C. 830 ml Stability 60 seconds 38 ± 5.0 ° C. 830 ml Drying 1 minute 55 ± 5.0 ° C.-* The replenishing amount is a value per 1 m ² of the photosensitive material.

The following color developing solutions, bleaching solutions, fixing solutions, stabilizing solutions and replenishers were used.

Color developing solution and color developing replenishing solution Developer replenishing solution Water 800 ml 800 ml Potassium carbonate 30 g 35 g Sodium hydrogen carbonate 2.5 g 3.0 g Potassium sulfite 3.0 g 5.0 g Sodium bromide 1.3 g 0.4 g iodide Potassium 1.2 mg-Hydroxylamine sulfate 2.5 g 3.1 g Sodium chloride 0.6 g-4-Amino-3-methyl-N-ethyl-N-([beta] -hydroxylethyl) aniline sulfate 4.5 g 6.3 g Diethylenetriaminepentaacetic acid 3.0 g 3.0 g Potassium hydroxide 1.2 g 2.0 g Add water to make 1 liter, and add potassium hydroxide or 20%
The color developing solution is adjusted to pH 10.06 and the replenisher is adjusted to pH 10.18 using sulfuric acid.

Bleach and Bleach Replenisher Bleach Replenisher Water 700 ml 700 ml Ammonium 1,3-diaminopropanetetraacetate 125 g 175 g Ethylenediaminetetraacetic acid 2 g 2 g Sodium nitrate 40 g 50 g Ammonium bromide 150 g 200 g Glacial acetic acid 40 g 56 g Water To 1 liter, and adjust the pH of the bleaching solution to 4.4 and the pH of the replenishing solution to 4.0 using ammonia water or glacial acetic acid.

Fixing Solution and Fixing Replenisher Fixing Solution Replenisher Water 800 ml 800 ml Ammonium thiocyanate 120 g 150 g Ammonium thiosulfate 150 g 180 g Sodium sulfite 15 g 20 g Ethylenediaminetetraacetic acid 2 g 2 g Aqueous solution using ammonia water or glacial acetic acid, pH 6.2
Then, the pH of the replenisher is adjusted to 6.5, and then water is added to make 1 liter.

Stabilizing solution and stabilizing replenisher water 900 ml p-octylphenol ethylene oxide 10 mol adduct 2.0 g dimethylolurea 0.5 g hexamethylenetetramine 0.2 g 1,2-benzoisothiazolin-3-one 0.1 g siloxane (UCC L-77) 0.1 g ammonia water 0.5 ml water was added to make up to 1 liter.
Adjust to pH 8.5 with% sulfuric acid.

The samples obtained had the following levels.

[0152]

[Table 17]

The outline of the layer structure of the abrasive particles, the abrasive layer and the magnetic recording layer will be described with reference to the drawings.

FIGS. 2A to 2H show the abrasive particles 103, the abrasive layer 101 and the magnetic recording layer 10 of the embodiment, respectively.
FIG. 3 (s) to 3 (w) schematically show the layer configuration of a magnetic recording layer of a comparative example. In each drawing, the lower side of the drawing indicates the support.

<< Evaluation Method >> Interlayer Adhesion A sample of the magnetic recording medium on which each of the above-described layers was applied in a multilayer manner was allowed to adapt for 24 hours or more in an atmosphere of 23 ° C. and 55% RH. In the direction perpendicular to the application surface of the sample, cut in a grid pattern with a razor blade at 5 mm intervals both vertically and horizontally, and put Nichiban Cellotape from above on it.
It was pasted with a pressure of kg / cm ² . 5
The magnetic recording layer was peeled off from the sample at a speed of m / sec, and the remaining area of the magnetic recording layer which was not peeled off from the sample was observed.

[0156] 2. Measurement of Durability of Magnetic Recording Medium Surface (No Photo Constituent Layer) A sample of the magnetic recording medium coated with the above-described layers in multiple layers was cut into a width of 1 inch and a length of 50 m and wound around a core to form a roll.

A device for measuring the durability of the surface of the magnetic recording medium shown in FIG. 4 was prepared, and while this rolled film was conveyed from the film unwinding side 111 to the film winding side 112, the nonwoven fabric 114 (KZ 5011 Mitsubishi The cleaning roll 113 was wound around a non-rotating cleaning roll 113 and a nip roll composed of a freely rotating load applying roll 115 (the load applying roll 115 is loaded by a load 116). Nip roll so that one side of the nonwoven fabric is in contact with the magnetic recording layer side,
The sample was clamped at a pressure of 1 kg.

The magnetic recording side surface of the sample was cleaned at a film transport speed of 1 m / sec. The amounts of the magnetic substance and the abrasive in the stains on the nonwoven fabric were determined by quantification of Fe element and Al element. The durability of the magnetic recording layer and the abrasive layer was evaluated by measuring the magnitude of the detachment of the material from the side of the magnetic recording. The larger the numerical value of the X-ray intensity of each element, the more the material falls off from the medium and the lower the durability. Quantification of each element was performed using a fluorescent X-ray analyzer (Model 3080, manufactured by Rigaku Denki Kogyo KK). The measurement conditions are as shown in Table 18.

[0159]

[Table 18]

[0160] 3. Measurement of Cleaning Effect of Magnetic Head by Magnetic Recording Medium (No Photo Constituent Layer) A sample of the magnetic recording medium coated with the above-described layers in a multilayer was cut into a width of 1 inch and a length of 50 m. Track width 1.5 mm, head gap 7 μm, number of turns 1000
The magnetic head capable of inputting / outputting a magnetic signal was painted over with a PILOT name pen (oily / fine black). After running the sample 50 m at a conveyance speed of 100 mm / sec, the state of the surface of the magnetic head was observed.

State of magnetic head surface ○: Magic ink on head completely dropped △: Ink dropped about half 半 分: Ink dropped only near head gap (more than half of ink left) △ C: Ink remains in head gap. X: Almost ink remains. Clogging test of magnetic head (after application of photographic constituent layers) A sample of a magnetic recording medium coated with the above-described layers in a multilayer manner was cut into a width of 1 inch and a length of 50 m, a track width of 1.5 mm and a head gap of 7 μm. , 1000 turns
A 6 KHz square wave signal was recorded at a transport speed of 100 mm / sec by using a magnetic head capable of inputting and outputting a magnetic signal.

Next, the above-mentioned sample was subjected to the above-mentioned development processing. The composition of the processing solution used in each step is as described above.

Next, a square wave signal is read by the magnetic read head at the same speed as that at the time of recording.
The number of reproduction errors when the value was 5% or less was evaluated. Here, the reproduction error is a phenomenon in which the pulse output becomes 35% or less of the initial value, and the same phenomenon of 100 pulses or less is counted as one reproduction error.

Further, the state of the magnetic head surface after reading was observed.

Condition of magnetic head surface: No dirt on head ○ △: Slight dirt generated △: Dirt generated around head gap △ ×: Dirt also generated on head gap ×: Dirt generated on entire surface of head The results are shown in Table 19.

[0166]

[Table 19]

As is clear from Table 19, the present invention (Sample Nos. 101 to 108) in which the abrasive layer and the magnetic recording layer were provided has a comparative example (Sample N) in which the magnetic recording layer contains abrasive particles.
o. 109-111), the durability against abrasion,
Excellent in cleaning effect of the magnetic head and clogging of the magnetic head.

The comparative examples (samples Nos. 112 and 113) in which the abrasive was smaller than the thickness of the abrasive layer had excellent durability against abrasion, but had a cleaning effect of the magnetic head.
The magnetic head is inferior to the sample of the present invention in terms of clogging.

[0169]

According to the present invention, it is possible to provide a magnetic recording medium capable of quickly and reliably inputting and outputting magnetic information by improving the durability of the magnetic recording layer and improving the cleaning performance of the magnetic head. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing various examples of a coating method used for providing an abrasive layer and a magnetic recording layer in the present invention.

FIG. 2 is a cross-sectional view schematically showing the layer structure of the abrasive particles, the abrasive layer and the magnetic recording layer of the present invention.

FIG. 3 is a cross-sectional view schematically illustrating a layer configuration of a magnetic recording layer of a comparative example.

FIG. 4 is a sectional view schematically showing an apparatus for measuring the durability of the surface of a magnetic recording medium used in the present invention.

DESCRIPTION OF SYMBOLS 101 Abrasive layer 102 Magnetic recording layer 103 Abrasive particle support 111 Film take-out side 112 Film take-up side 113 Cleaning roll 114 Non-woven fabric 115 Freely rotating load load roll 116 Load

Claims (4)

[Claims] 1. On one side of the support, 60 of total abrasive
A polishing layer containing at least 60% by weight of the total magnetic material and a magnetic recording layer containing at least 60% by weight of the total magnetic material, and wherein the average particle size of the abrasive in the abrasive layer is a dry film of the abrasive layer. A magnetic recording medium characterized by being larger than the thickness. 2. A multi-layer simultaneous application of an abrasive coating solution containing at least 60% by weight of the total abrasive and a magnetic material coating solution containing at least 60% by weight of the total magnetic material on one side of the support. A magnetic recording medium having a multilayer structure. 3. The abrasive in the abrasive layer has an average particle size of:
3. The magnetic recording medium according to claim 1, wherein the thickness is larger than the sum of the dry thickness of the abrasive layer and the dry thickness of the magnetic recording layer. 4. The magnetic recording medium according to claim 1, wherein a magnetic recording layer is provided on a farther side of the support, and an abrasive layer is provided on a closer side of the support. .