JPH09282643A - Magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic recording tape maintaining the corrosion preventing effect of the magnetic layer even in storage and use in an environment at high temp. and humidity and having high durability and reliability. SOLUTION: When a magnetic layer 3 is formed on a base film 2 to obtain a magnetic recording tape 1, a corrosion inhibitor 9 is housed in microcapsules and applied to the base film 2 and then the magnetic layer 3 is formed on the microcapsules by vapor deposition. The microcapsules are broken at the time of forming the magnetic layer 3 and the corrosion inhibitor 9 in the microcapsules flows out and distributes insularly on the base film 2.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a magnetic recording medium such as a magnetic tape and a method for manufacturing the same.

[0002]

As a conventional magnetic recording medium, containing γ-Fe ₂ O _3, Co on a nonmagnetic support gamma-Fe ₂ O
_{3, Fe 3 O 4, Fe} 3 O 4 containing Co, γ-Fe ₂ O
Betride compound of ₃ and Fe ₃ O ₄ , Betride compound containing Co, oxide ferromagnetic powder such as CrO ₂ ,
Alternatively, a powder magnetic material such as an alloy magnetic powder containing Fe, Co, or Ni as a main component is dispersed in an organic binder (binder) such as a vinyl chloride-vinyl acetate copolymer, a polyester resin, or a polyurethane resin. A coating type magnetic recording medium prepared by coating and drying a magnetic coating material to which a dispersant such as a fatty acid or its ester type and a lubricant is applied is widely used.

On the other hand, in the field of video tape recorders (VTRs), for example, in order to achieve high image quality, there is an increasing demand for high density magnetic recording, large capacity, and further miniaturization. There is a further demand for smoothness and thinning of the medium. Then, a ferromagnetic metal material such as Fe-based or Co-Ni alloy is deposited on a non-magnetic support such as a polyester film or a polyimide film by plating or vacuum thin film forming technology (vacuum deposition method, sputtering method, ion plating method, etc.). A so-called ferromagnetic metal thin film type magnetic recording medium, which is directly deposited on the substrate and does not use a binder, has been proposed and is attracting attention.

This ferromagnetic metal thin film type magnetic recording medium is
Not only has excellent coercive force and squareness ratio, excellent electromagnetic conversion characteristics at short wavelengths, but also because the magnetic layer can be made extremely thin, recording demagnetization and thickness loss during reproduction are extremely small. That is, since it is not necessary to mix a non-magnetic material such as an organic binder or an additive which is a non-magnetic material in the magnetic layer, the packing density of the magnetic material can be increased, and a large residual magnetic flux density can be obtained. It has a number of advantages.

However, in such a ferromagnetic metal thin film type magnetic recording medium, a lubricant and a rust preventive agent cannot be mixed in the magnetic layer, so that the durability and the rust preventive property are still insufficient. It is said that there is. As a solution to this problem,
For example, a method of applying a lubricant, a rust preventive, or the like to the surface of the magnetic recording medium (that is, on the magnetic layer) is known.

However, in such a method, durability and rust preventive property which are sufficiently satisfactory for use under a special environment such as high temperature and high humidity and for severe use such as repeated use for business use are obtained. I was not able to do so, and lacked reliability of quality.

Therefore, for the purpose of improving the durability and anticorrosiveness of the above magnetic recording medium, a thin hard carbon protective film is provided on the ferromagnetic metal thin film (magnetic layer), and the carbon protective film is further protected. A method of applying a rust agent or a lubricant is adopted.

FIG. 16 is a sectional perspective view showing an example of a conventional magnetic recording medium manufactured under such consideration. As shown, the non-magnetic fine particles 49 are arranged on one surface of the base film 43, and the underlayer 44, the magnetic metal thin film 45, the protective film 46,
The magnetic tape 50 has a structure in which the rust preventive agent layer 47 is sequentially laminated, and the back coat layer 48 is laminated on the other surface of the base film 43.

However, even in the magnetic tape having such a structure, the base film 43 and the magnetic metal thin film 45 are also included.
Rust easily progresses in spots from the interface with.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and retains and maintains an anticorrosive effect under any conditions of use to improve running performance and durability. It is an object of the present invention to provide an excellent magnetic recording medium and a manufacturing method thereof.

[0011]

The present inventor has conducted extensive studies in order to achieve the above-mentioned object, and as a result, an effective rust-preventive structure for rust-proofing the side surface of a medium such as a magnetic tape after cutting. The present invention has been completed and the present invention has been completed.

That is, according to the present invention, in a magnetic recording medium in which a magnetic layer is provided on a substrate, a rust preventive agent is distributed in an island shape between the substrate and the magnetic layer. The present invention relates to a magnetic recording medium.

The present invention also relates to a method of manufacturing a magnetic recording medium, which comprises a step of distributing a rust preventive agent covered with a film on a substrate and a step of forming a magnetic layer on the substrate thereafter. It is a thing.

By thus distributing the rust preventive agent in an island shape between the substrate and the magnetic layer, the rust preventive agent is held or supplied to the magnetic layer for a long period of time, so that not only the rust preventive action can be maintained. In particular, a rust preventive agent oozes out to the magnetic layer side of a medium such as a magnetic tape (this causes remarkable bleeding or adhesion to the side surface (cut surface) after cutting.)
In addition, since it is possible to prevent an oxidizing substance (oxygen or the like) from penetrating into the magnetic layer from a portion other than the side surface (under the magnetic layer), the rust preventive effect can be more effectively exhibited. Furthermore, since the rust-preventive agent is distributed in an island shape, the magnetic layer and the substrate are likely to come into direct contact with each other in the non-distributed region, the adhesive force is maintained, and there is no peeling between the two, resulting in mechanical strength. Can also be held.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the magnetic recording medium according to the present invention, in order to sufficiently obtain the above effects, a rust preventive agent is preferably 10 to 10 million pieces / m ² , more preferably between the substrate and the magnetic layer. Is preferably distributed at a distribution density of 55 to 50 million pieces / m ² .

The magnetic recording medium preferably has a structure in which a magnetic layer made of a magnetic metal thin film is formed on a non-magnetic support, and a hard protective layer is provided on the magnetic layer.

Further, nonmagnetic particles are arranged in a region containing no rust preventive between the substrate and the magnetic layer, and the nonmagnetic particles are 1 to 10 million particles / m ² , and more preferably 5 to 5. 500
It is desirable to have a distribution density of 10,000 pieces / m ² . As a result, the surface roughness of the magnetic recording medium can be controlled to reduce friction during running.

Further, the production method of the present invention has a step of covering the rust preventive agent with a film by an interfacial polycondensation reaction in a state in which the rust preventive agent is included. In this step, a water-in-oil emulsion is used. It is desirable to cover the rust preventive agent with a polymer film by an interfacial polycondensation reaction between the fine emulsion particles and the medium liquid therein. Thereby, the rust preventive agent can be coated with the microcapsules.

In order to obtain the above effects sufficiently,
The rust preventive agent covered with the above film is arranged at a distribution density of 1 to 10 million pieces / m ² , more preferably 5 to 5 million pieces / m ² , and the particle diameter of the rust preventive agent covered with the film is Is preferably 10 to 1,000 nm, more preferably 20 to 500 nm.

In this way, the anticorrosive agent covered with the film is adhered onto the substrate, the magnetic layer comprising the metal magnetic thin film is vapor-deposited thereon, and a hard protective layer is formed on this magnetic layer. As a result, a durable and highly reliable magnetic recording medium having an excellent anticorrosive effect is provided.

In this case, it is preferable that the rust preventive agent is used as a solution, and the solution is covered with a film to be applied on the substrate to adhere the rust preventive agent. The concentration of this rust inhibitor solution is 0.2% to 50% by weight.
Is desirable.

Thus, on the substrate, between the magnetic layer,
By applying an internally added rust preventive agent to the coating such as microcapsules, the rust preventive agent oozes out from the microcapsules at the time of vapor deposition, and the rust preventive effect of the medium from the interface between the base and magnetic surface of the cut surface is effective. Can be raised. In particular, when the medium is stored in a reel state, it exhibits a good rust preventive effect against the problem of spot-like rust from the cut end surface.

In the magnetic recording medium of the present invention, the method for forming the magnetic layer made of a magnetic metal thin film may be a vacuum thin film forming technique, for example, a vacuum vapor deposition method, a sputtering method,
Any conventionally known technique such as an ion plating method and a CVD method (chemical vapor deposition method) can be used.

In the above vacuum deposition method, a ferromagnetic metal material is evaporated by resistance heating, high frequency heating, electron beam heating or the like under a vacuum of 10 ^-4 to 10 ^-1 Torr to evaporate metal (strong metal) on a non-magnetic support. The magnetic metal material is deposited, and in order to obtain a high coercive force, an oblique evaporation method in which the ferromagnetic metal material is obliquely evaporated on the non-magnetic support can be adopted.
Alternatively, the above vapor deposition is also included in order to obtain a higher coercive force.

When forming a metal magnetic thin film by such a vacuum thin film forming technique, as a ferromagnetic metal material used, in addition to metals such as Fe, Co, Ni and Cr, Co-
Ni alloy, Co-Pt alloy, Co-Fe-Ni alloy, C
o-Ni-Pt alloy, Co-Ni-Cr alloy, Fe-C
o alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe
-Co-B alloy, Co-Ni-Fe-B alloy, Co-C
Examples thereof include r alloys and the like, or those containing metals such as Cr and Al. In particular, when a Co—Cr alloy is used, a perpendicular magnetization film is formed.

Regarding the thickness of each layer, the thickness of the metal magnetic thin film is usually 0.02 to 1 μm. The hard protective film such as the carbon protective film has a thickness of 5 to 20 nm, the top coat layer has a thickness of 5 to 10 mg / m ² , and the back coat layer has a thickness of 0.1.
It is preferable that the thickness is 1.0 μm.

As the method for forming the carbon protective film, as in the case of the magnetic layer, for example, a vacuum vapor deposition method,
Any conventionally known technique such as a sputtering method, an ion plating method, or a CVD method can be used.

As the non-magnetic support, any conventionally known material can be used. Examples thereof include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polyethylene and polypropylene, and cellulose triacetate. , Cellulose diacetate, cellulose derivatives such as cellulose triacetate butyrate, polyvinyl chloride, vinyl resins such as polyvinylidene chloride, polycarbonates, polymeric materials typified by polyamideimides, aluminum alloys, titanium alloys, Examples thereof include a metal plate made of a light metal such as a titanium alloy, a support made of alumina glass, ceramics and the like.

The form of the non-magnetic support is not particularly limited, and may be any form such as tape, sheet, disc, drum and the like. Further, in order to control the surface property of this non-magnetic support, a surface treatment for forming fine irregularities (for example, minute projections) is performed, and if necessary, the surface treatment is performed on the non-magnetic support. An undercoat layer (intermediate layer) may be applied.

The rust preventive used in the present invention may be any rust preventive commonly used as a rust preventive for magnetic recording media of this type, for example, phenols, naphthols, quinones, diaryl ketones. , A heterocyclic compound containing a nitrogen atom, a heterocyclic compound containing an oxygen atom, a heterocyclic compound containing a sulfur atom, a compound having a mercapto group, a thiocarboxylic acid or a salt thereof, a thiazole compound, and the like. A specific example is as follows.

First, examples of the above-mentioned phenols include dihydric phenol, alkylphenol and nitrosophenol.

Examples of the dihydric phenol include pure phenols such as hydroquinone, resorcin, and catechol, and alkylamino, nitro, and halogen-substituted products thereof.
For example, 2-methylhydroquinone, 4-methylresorcinol, 5-methylresorcinol, 4-methylpyrocatechol, 2,5-dimethylhydroquinone, 4,6
-Dimethylresorcinol, 2,5-dimethylresorcinol, 2-isopropyl-5-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-te
rt-butylhydroquinone, 4-tert-butylcatechol, 2-aminoresorcinol, 2-resorcinol,
2,5-dichlorohydroquinone and the like can be mentioned.

The above-mentioned alkylphenol refers to a monovalent phenol alkyl-substituted product, and examples thereof include o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, 2,3. -Dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,
4,6-trimethylphenol, 2,4,5-trimethylphenol, 5-isopropyl-2-methylphenol, p-tert-butylphenol, 2,6-di-tert-
Butyl-p-cresol, 4,4'-methylene-bis-2,6-di-tert-butylphenol, 2,6-dimethyl-4-tert-butylphenol, 2,4,6-tri-
Examples include tert-butylphenol.

Examples of the nitrosophenol include 4-nitroso-2-methoxy-1-phenol and 4
-Nitroso-2-ethoxy-1-phenol, 6-nitroso-o-cresol, 4-nitroso-m-cresol, o-nitrosophenol, 2-nitrosophenol, 2-nitrosoresorcin, 4-nitrosoresorcin, p-nitroso Examples include phenol.

The above naphthols include α-naphthol, β-naphthol, 1,2-naphthalenediol,
1,3-naphthalene diol, 1,5-naphthalene diol, 1,7-naphthalene diol, 1,8-naphthalene diol, 2,3-naphthalene diol, 1,4,5
-Pure naphthols such as naphthalenetriol, 1,2,5,8-naphthalenetetraol, and nitro, nitroso, amino, halogeno-substituted naphthols such as 1-chloro-2-naphthol, 2,4-dichloro-1- Naphthol, 1-nitro-2-naphthol, 1,6-dinitro-2-naphthol 1-nitroso-2-naphthol, 2-
Nitroso-1-naphthol, 1-amino-2-naphthol and the like can be mentioned.

The above-mentioned quinones include p-benzoquinone, o-benzoquinone, 1,2-naphthoquinone, 1,4.
-Substituted quinones such as naphthoquinone, 2,6-naphthoquinone, anthraquinone, 9,10-phenanthrenequinone and diphenoquinone, methyl-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2-methyl-1, Methylquinones such as 4-naphthoquinone and 2-methylanthraquinone, 2,5-dihydroxy-p-benzoquinone, tetrahydroxy-p-benzoquinone, 5-hydroxy-1,4-naphthoquinone, 2,3-dihydroxy-1,4- Naphthoquinone, 5,8-dihydroxy-
1,4-naphthoquinone, 2-hydroxyanthraquinone, 1,2-dihydroxyanthraquinone, 1,2,3
-Hydroxyquinones such as trihydroxyanthraquinone, 1,2,4-trihydroxyanthraquinone, 1,2,6-trihydroxyanthraquinone, 2,5-trihydroxyanthraquinone and 1,2,7-trihydroxyanthraquinone, 2- Amino anthraquinone, 1,2
-Diaminoanthraquinones, 1-nitroanthraquinone, nitroquinones such as 1,5-dinitroanthraquinone, halogenoquinones such as 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone and tetrabromo-p-benzoquinone, or 2 Examples thereof include quinones having one or more substituents, such as 2,5-dichloro-3,6-dihydroxy-p-benzoquinone and 1-methyl-2-hydroxy-1,4-naphthoquinone.

Examples of the diarylketone include benzophenone and its derivatives. For example, benzophenone, 4-methylbenzophenone, 3-methylbenzophenone, 3,4-dimethylbenzophenone, 4,4'-methylbenzophenone, 3,4'-. Alkyl-substituted compounds such as methylbenzophenone and 4-ethylbenzophenone, 4
-Hydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,
2 ', 5,6'-tetrahydroxybenzophenone,
Hydroxybenzophenones such as 2,3 ′, 4,4 ′, 6-pentahydroxybenzophenone, aminobenzophenones such as 4-aminobenzophenone and 4,4′-diaminobenzophenone, or benzophenones having two or more substituents Examples include 4-methoxy-2-hydroxybenzophenone and 2,2′-dihydroxy-4-methoxybenzophenone.

Examples of the heterocyclic compound containing a nitrogen atom include acridine, 2,2 ', 2 "-terpyrdyl neocuproine, 2,2'-dipyridylbenzotriazole,
In addition to 5-methylbenzotriazole, pasophenanthroline, 1,10-phenanthroline, aldehyde collidine, benzylpyridine, phenylpyridine, quinazoline, 2-heptadecylimidazole and the like, compounds having a phenolic hydroxyl group, for example, 4- (2-pyridylazo). ) -Resorcin-1- (2-pyridylazo) -2-naphthol, 4-quinolinol, 4-methyl-2-quinolinol, 8-quinolinol, quinolinediol, etc., compounds having a carboxyl group, for example, kynurenic acid, actiridic acid, atphan , Quinnadic acid, cinchonic acid,
Compounds having an amino group or an imino group such as isonicotinic acid, 2,5-pyridinedicarboxylic acid and quinic acid, for example, 2-aminobenzimidazole, 5-amino-1H-tetrazole, 5-amino-1H-1,2, Compounds having a carbonyl group such as 4-triazole, adenine, guanine, luminol, 2-hydrazinoquinoline and thiamine, for example, riboflapine, theopromine, allantoin, alloxan, 2-thiobarpituric acid, violuric acid, isatin, hydantoin, thymine, barpituric acid. , Orotic acid, uracil, succinimide, creatinine, 2-pyrrolidone and the like.

Examples of the heterocyclic compound containing an oxygen atom include tocopherol, morin, quercetin, ascorbic acid, 1,8-naphthalic anhydride, resorufin, kojic acid, dehydroacetic acid, oxazole, 3-aminophthalimide, uridine, thymidine, Examples include guanosine and isatoic anhydride.

Examples of the above-mentioned heterocyclic compound containing a sulfur atom include sulfolane, 3-hydroxysulfolane, 3-methylsulfolane, sulfolene, 3-hydroxysulfolene, 3-methylsulfolene, rhodanine, 3-aminorhodanin, thiazoline- 4-carboxylic acid, 4H-1,4
-Thiazine, pithion, 3,6-thioxanthene diamine-10,10-dioxide and the like.

Examples of the compound having a mercapto group include 2-benzoxazolethiol, thiophenol, thiosalicylic acid, propanethiol, thiouracil, 2,3-quinoxalinedithiol, dithizone, thiooxine, 2-benzimidazolethiol, 6-thioguanine, 5-nitro-2-benzimidazole thiol, 5-amino-1,3,4-thiazole-2-thiol and the like can be mentioned.

The above thiocarboxylic acid or salt thereof includes
Examples thereof include sodium diethyldithiocarbamate, ethanethioic acid, rubeanic acid, thioacetamide, and ethanedithioic acid.

Examples of the thiazole compound include diazo sulfide, azosulfim, 1,3,4-thiadiazole, bismuthiol, viazthiol, benzothiazole, 2-methylbenzothiazole, 2- (p-aminophenyl) -6-methylbenzothiazole. , 2-mercaptobenzothiazole, benzothiazoline, 2-benzothiazoline, benzothiazolone and the like.

The above-mentioned rust preventive agent may be adhered by being applied to the surface of the non-magnetic support, but the rust preventive agent solution obtained by dissolving the above rust preventive agent in a solvent may be used. What is filled in microcapsules may be used.

In order to prepare the microcapsules, generally, a water-in-oil type emulsion is prepared, and a polymer thin film is formed by interfacial polycondensation of the fine emulsion particles and a medium liquid to cover the particles. Then, the microcapsules may be separated from the oil phase by centrifugation and purified by dialysis. This method itself is known, but its manufacturing method and materials are not particularly limited to the above.

Here, the concentration of the rust preventive solution is 0.2
% To 50% by weight is preferred, 0.5% to 10% by weight
More preferably, it is wt%. If this solution concentration is too low, the effect of improving rust prevention does not appear, and if it is too high, a sticking phenomenon occurs between the guide roll and the magnetic metal thin film at the time of transporting the medium in the production facility, and the medium Is likely to occur.

The material of the above-mentioned microcapsules is
It may be a polymer of various monomers and may be a homopolymer or a copolymer. Examples of usable monomers include ammonia, carboxylic acids, polyhydric alcohols, and the like.
Examples of the polymer obtained by these include polyamide, polyimide, polyester, polycarbonate, phenol resin, and melamine resin.

Further, in the present invention, if necessary,
An undercoat film of a magnetic layer may be provided on the non-magnetic support, a back coat layer may be provided on the back surface, a top coat layer may be provided on the magnetic layer, or a protective film may be appropriately formed on the magnetic layer. Good. In this case, the method for forming the undercoat film, the back coat layer, the top coat layer, the protective film and the like may be any method that is usually applied to this type of magnetic recording medium, and is not particularly limited.

[0049]

EXAMPLES Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to the following examples.

In the examples described below, fine particles are arranged on a non-magnetic support (hereinafter referred to as a base film) to form fine protrusions on the surface, and then a rust preventive agent is distributed in an island shape.
This is an example of a metal magnetic thin film type magnetic tape in which a metal magnetic thin film is vapor-deposited thereon and a surface layer composed of a carbon protective layer and a lubricant layer thereon is further formed.

FIG. 1 is an enlarged cross-sectional view of a main part showing a specific structure of a magnetic tape 1 according to an embodiment of the present invention in a cross section in the width direction, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. Is.

In the magnetic tape 1 of this embodiment, a SiO ₂ fine particle 8 having a particle diameter of about 20 nm and an island-shaped rust preventive agent 9 are provided on one surface of a base film 2 made of polyethylene terephthalate (PET) having a thickness of 10 μm. 0.2 μ thick on top of this
a magnetic layer 3 composed of a cobalt metal thin film of m (100% Co vapor-deposited layer), a protective layer 4 composed of diamond-like carbon and having a thickness of 15 nm, and a top coat layer 5 composed of a fluorine-based lubricant, which are formed in this order, It has a multi-layer structure in which the back coat layer 6 is provided on the opposite surface.

The most remarkable feature of this embodiment is
As shown in FIGS. 1 and 2, the rust preventive agent 9 is distributed in an island shape. This is because the solution of the rust preventive agent 9 is applied onto the base film 2 in a state of being encapsulated in the microcapsules 7 described later, and then the microcapsules are destroyed during the vapor deposition formation of the magnetic layer 3, and the magnetic layer 3 It is considered that the rust preventive agent 9 is distributed between the SiO ₂ particles 8 in an island shape at the interface between the base film 2 and the base film 2.

FIG. 5 shows that immediately after the rust preventive agent 9 is contained as the solution 9A in the microcapsules 7 and applied to the base film 2, the rust preventive agent 9 is applied as the solution 9A to the microcapsules 7 in the base. It shows a state of being scattered on the film 2. This is a cross-sectional view at one stage in the manufacturing process of the magnetic tape 1 corresponding to FIG.

As described above, the rust preventive agent solution 9A coated on the microcapsules 7 is a solution obtained by dissolving the rust preventive agent 9 in an alcoholic solvent.
It was filled in. In order to obtain this type of microcapsule, generally, a water-in-oil emulsion is prepared, and a polymer thin film is formed by interfacial polycondensation between the fine emulsion particles and a medium liquid, and the particles are covered. This is subjected to centrifugation to separate the microcapsules 7 from the oil phase, and this is further purified by dialysis. Although this method itself is known, this example was also manufactured by the same manufacturing method (details of the manufacturing method will be described later).

Then, in the state as shown in FIG.
The microcapsules 7 containing A are coated on the base film 2, and the magnetic layer 3 is vapor-deposited on the base film 2. At this vapor deposition stage, the microcapsules 7 are destroyed by the heat during vapor deposition, and the rust preventive agent is appropriately added. It is considered that the rust-preventive agent 9 is distributed in the form of islands at the interface between the base film 2 and the magnetic layer 3 in the state as shown in FIGS. 1 and 2 finally.

Therefore, this rust preventive agent 9 is used as the base film 2.
When the magnetic tape 1 is cut at a predetermined width while existing at the interface between the microcapsule 7 and the magnetic layer 3, the microcapsule 7 is broken at the cut surface as shown in FIGS. 3 and 4.
The rust preventive agent 9 adheres to the side surface (cut surface) 1a of the magnetic tape 1, and the rust preventive agent film 9B is formed on the side surface 1a.

The cause of spot-like rust formation at the interface between the base film 2 and the magnetic layer 3 is that an oxidizing substance (oxygen gas or the like) passes through the top coat layer 5 and the protective layer 4 which are extremely thin from the surface of the magnetic tape 1. It is conceivable that a magnetic substance may enter or an oxidative substance may be mixed in when forming a magnetic tape. The rust of the magnetic layer 3 due to this may be the above-mentioned rust preventive distributed between the magnetic layer 3 and the base film 2. Agent 9 can effectively prevent it.

As a factor of rust generation, the magnetic layer 3 may be exposed on the cut surface by cutting the magnetic tape 1. However, as described above, the rust preventive agent 9 oozes out to the side surface 1a. The cut surface of the magnetic layer 3 is covered with the film 9B of the rust preventive agent, the exposed portion of the magnetic layer 3 is reduced, and rust preventive measures against the factors causing rust can be effectively taken.
As described above, the present embodiment provides an effective means for rust prevention of the magnetic layer of the magnetic tape 1.

FIG. 6 is a sectional view schematically showing a process in which the microcapsules 7 are destroyed during the vapor deposition of the magnetic layer 3. That is, FIG. 6A shows the microcapsules 7 in a coated state in which the rust preventive agent 9 is contained, and FIG. 6B shows the destruction of the microcapsules 7 due to the heat thereof as the vapor deposition progresses to prevent rust. FIG. 6C shows a state in which the agent 9 has exuded.
Shows the state where the microcapsules 7 are completely destroyed and the rust preventive agent 9 flows out and diffuses.

FIG. 7 is an enlarged view of a part of FIG. 1, showing the above-mentioned microcapsules 7 in FIG.
FIG. 6 is a diagram showing the destruction process of (1) in the film formation process of the magnetic layer 3.

FIG. 8 is a flow chart showing the step of encapsulating the rust preventive agent 9 in microcapsules. First, the rust preventive agent (9) is dissolved so as to have a solution concentration of 2% by weight in the step (51) of dissolving in alcohol as a solvent to obtain a rust preventive agent solution (9).

Here, the solution concentration is 0.2% by weight to 50%.
It is preferably in the range of 0.5% by weight, and more preferably in the range of 0.5% by weight to 10% by weight. If this solution concentration is too low, the effect of improving rust prevention will not appear, and if it is too high, a sticking phenomenon will occur between the guide roll of the tape path of the manufacturing equipment and the metal magnetic thin film, and Cutting may occur.

On the other hand, examples of the monomer (10) used as the material of the microcapsule 7 include a mixture of sebacic acid dichloride and hexamethylenediamine, which is used together with the rust inhibitor solution (51) in oil (hexane in this case). ), And an interfacial condensation polymerization reaction was carried out in a known manner to prepare microcapsules 7 containing rust inhibitor solution 9A.

In this case, by stirring the rust preventive solution (9) and the monomer (10) in oil, the oil phase component and the water phase component are separated to form the water-in-oil emulsion (52). Had made. The oil medium to be used may be, for example, heptane, toluene, benzene or the like other than the above.

By this stirring, a polymer thin film is formed by interfacial condensation polymerization (53) at the interface between the fine emulsion particles of the rust inhibitor solution (9) and the medium liquid (monomer). Then, for example, fine particles of the rust preventive solution (9) having a solution concentration of 2% by weight were coated on the polymer thin film 7 to be microencapsulated (54). As the polymerization conditions, the temperature is from room temperature to
It is preferably 100 degrees, more preferably 20 to 50 degrees, and the reaction time is preferably 1 to 50 minutes, more preferably 5 minutes.

The microcapsules 7 containing the rust preventive solution thus obtained were separated (55) from the oil phase by centrifugation.

The separated microcapsules were further purified by dialysis (56) to prepare microcapsules 7 having a particle size of 50 to 100 nm containing the rust preventive agent 9 as described above.

The magnetic tape of this example using the rust preventive 9 contained in the microcapsules 7 prepared as described above was manufactured as follows. FIG. 9 is a flowchart showing the manufacturing process.

First, a base film 2 made of polyethylene terephthalate (PET) having a thickness of 10 μm was prepared.

On the surface of the base film 2, in the step (60) of adhering SiO ₂ particles, Si having a particle size of about 20 nm is used.
About 10 million O ₂ particles / m ² were arranged to form fine irregularities. This controls the surface property on the magnetic layer of the magnetic tape.

Further, on the base film 2, in the rust-preventive agent applying step (61), the particle size of the rust-preventive agent-containing solution having a solution concentration of 2% by weight produced by the above-mentioned microcapsule producing process (57) was 50. ~ 100nm microcapsules 7
Was applied at about 10 million pieces / m ² .

Next, in the step (62), cobalt (Co) is formed on the base film 2 on which the SiO ₂ particles 8 and the microcapsules 7 are arranged as described above by a continuous vacuum oblique vapor deposition method using a vacuum vapor deposition apparatus described later. A metal thin film (100% Co single-layer vapor deposition, film thickness 0.2 μm) of (1) was formed while introducing a slight amount of oxygen gas for improving magnetic characteristics, and the magnetic layer 3 was formed.

Next, in step (63), diamond-like carbon was laminated on the magnetic layer 3 by a sputtering method to form the protective layer 4.

Next, in step (64), methyl ethyl ketone was used as a solvent and carbon was fixed with a urethane-based binder to a thickness of 0.8 μm using a reverse roll coater (not shown) to form a back coat. Layer 6 was formed. For this coating, the coating device of FIG.
29 can also be used.

Next, in step (65), a solution obtained by diluting the fluorine-based lubricant layer with a solvent (toluene) is applied to the surface of the protective layer 3 formed as described above so that the coating amount is 10 mg / m ^2. Thus, the top coat layer 5 was formed.

A magnetic tape 1 was produced by cutting the raw material of the base film on which the predetermined layers were formed as described above into a width of 8 mm in the step (66).

A part of the above-described magnetic tape manufacturing process will be described more specifically.

The base film 2 is coated with the rust preventive agent 9 contained in the microcapsules 7 (step (61) in FIG. 9) by a coating device 29 shown in a schematic front view in FIG. 10, for example.

The base film 2A, which serves as a support for the original magnetic tape, is wound around the payout hub 20A and one end of the base film 2A passes through the guide rollers 21 and 22 and the backup roll 23.
And the gravure roll 24A. The gravure roll 24A is partially immersed in the paint (for example, ethanol) 7A containing the capsule 7 containing the rust preventive agent 9 filled in the paint tank 28A, and the gravure roll 24A is rotated to rotate the circle of the gravure roll 24A. The paint 7A attached to the peripheral surface is applied to one surface of the base film 2A.

The base film 2B coated with the paint 7A on one surface is further guided to the drying oven 30 via the guide rollers 26 and 27. Then, the base film 2C on which the paint 7A is dried is wound around the winding hub 20B.

This drive is performed by the drive source of the winding hub 20B (not shown). Incidentally, reference numeral 25 in the drawing is a doctor blade for scraping off the excess paint adhering to the gravure roll 24A.

As shown in FIG. 11, the base film 2C coated with the rust preventive agent as described above dissolves the magnetic metal substance (cobalt in this example) in the vacuum vapor deposition apparatus 41, and its vapor is spread on the surface. The magnetic layer 3 is formed by the uniform attachment (step (62) in FIG. 9).

That is, in the vacuum chamber 12, the cooling roll 16 is arranged above the evaporation source 15 and the cooling roll 16
While contacting the non-magnetic base film 2C with
At the same time as it is conveyed in the direction of the arrow, vapor of magnetic metal (cobalt) from the evaporation source 15 is deposited on the base film 2C. In FIG. 11, 31B is a feeding hub around which the base film 2C is wound, 31A is a take-up hub, 18 is a guide roll for guiding the base film, and 14 is a crucible for accommodating the evaporation source 15. The vapor deposition method shown in FIG. 11 is called oblique vapor deposition.

A window is provided in the vicinity of the cooling roll 16 to define the incident angle of vaporized metal and the vapor deposition region and to prevent the vaporized metal from flying to the region in the vacuum chamber where vapor deposition is not desired.
A deposition prevention plate 17 having 17a is arranged. In the figure, 19 is a vacuum pump.

As means for evaporating the magnetic metal,
An electron beam E emitted from an electron gun 13 provided outside the vacuum chamber 12 is used. Thus, by obliquely vapor-depositing the magnetic metal material, a high coercive force can be obtained.

On the base film 2A, the above-mentioned magnetic layer (further, carbon protective film, top coat layer, back coat layer:
A stack of these manufacturing steps is omitted here) is completed as a magnetic tape raw material 2D wound around a core 42 as shown in FIG. 12, and then a predetermined width (this example is used by a cutting device). 8mm width), and the magnetic tape 1
Becomes FIG. 13 is a front view of a main part of the cutting device.

The original magnetic tape 2D is attached to the feeding hub 43 together with the core 42, sent to the cutting machine 33 by the driving nip roll 40 composed of a pair of rolls 32A and 32B, and is cut into a predetermined width here to be magnetized. It becomes the tape 1, which is separated every other and divided into two magnetic tape groups.

The magnetic tape group divided into two is
The pair of rolls 3 are guided by the guide rollers 35A and 35B, respectively.
The nip rollers 41A and 41B for driving, which are composed of 7 and 38, respectively, convey them and wind them around the take-up hubs 39A and 39B to form pancakes 50A and 50B. A pancake is rolled up,
It is a term that refers to a long magnetic tape before being cut into a predetermined length.

The original magnetic tape 2D is designed so that a tension suitable for cutting is applied by the nip roll 40 and the nip rolls 41A and 41B at the time of cutting.

FIG. 14 is a front view of the main part of the cutting machine 33, and FIG. 15 is FIG.
It is a XV-XV line side view of.

The cutting machine 33 comprises a group of cutting blades in which a large number of disk-shaped cutting blades 34A are coaxially fixed to a rotary shaft 34C with a constant gap, and a large number of disk-shaped cutting blades similarly to this group. 34B is composed of a pair of cutting blades that are coaxially fixed to the rotating shaft 34D with a constant gap.

The width and gap between the cutting blades 34A and 34B are the cutting width (8 mm in this example). And the rotating shaft 34
C and 34D are arranged parallel to each other, and each cutting blade 34A is slightly inserted into each gap of the cutting blade 34B, and each cutting blade 34B is slightly inserted into each gap of the cutting blade 34A. Therefore, the cutting blades 34A and 34B adjacent to each other locally contact each other at the peripheral edge of the end face substantially without any gap.

The group of cutting blades 34A and the group of cutting blades 34B rotate in opposite directions as indicated by arrows. Original magnetic tape 2
F is conveyed to the central position between the rotary shafts 34C and 34D, and is cut into a large number by shearing at the circumferential roots of the cutting blades 34A and 34B to form a magnetic tape 1 having a width of 8 mm.

In the above manufacturing method, as the rust preventive agent 9 contained in the microcapsules 7, as shown in the following Table 1, 23 kinds are arbitrarily selected from the above-mentioned various rust preventive agents,
Corresponding sample tapes were produced using the microcapsules containing these, and these were taped.

[0096]

Each of the prepared sample tapes, together with the cassette shell, was exposed to the severe environment of being stored in the cassette for 6 days in a constant temperature and humidity chamber at a temperature of 60 ° C. and a relative humidity of 95%. The rust occurrence was measured. For storage, a cassette shell for Hi8ME manufactured by Sony Corp. was used with a sample tape mounted for 120 minutes. Then, the outermost 30 cm of the tape mounted in the cassette was sampled, both side surfaces (both cut end surfaces) of the tape were observed with an optical microscope, and the presence or absence of spot-like rust was examined and the number thereof was counted.

Further, in order to compare with the above specific example, a magnetic tape for comparison in which a rust preventive agent was applied as the uppermost layer was prepared without coating the microcapsules containing the rust preventive agent internally on the base film 2. The measurement was performed under the same conditions as in the above specific example.

The test results of each specific example and comparative example are shown in Table 2 below.
It is as follows. The numbers in this table indicate the number of rusts present on both sides of the sampled outermost 30 cm of the tape.

[0100]

As is clear from the above results, each of the specific examples according to the present invention exhibited a good rust preventive effect even under severe conditions of high temperature and high humidity. On the other hand, the sample tape not coated with the microcapsules (Comparative Example) was not excellent in rust-preventing effect and had a problem of rusting in spots from the cut end face.

That is, according to this example, the anticorrosive agent encapsulated in the microcapsules was ruptured and exuded when the microcapsules were destroyed when the magnetic layer was vapor-deposited after being applied on the base film, and the anticorrosion was applied on the base film. Since the agent is distributed in an island shape, it is possible to prevent rust of the magnetic particles at the interface between the base film and the magnetic layer.

When the raw tape of the magnetic tape in which the rust preventive agent is distributed in an island shape between the base film and the magnetic layer is cut into a tape having a width of 8 mm, the rust preventive agent 9 is applied to the side surface of the magnetic tape 1.
Oozes out. Therefore, the exposed surface of the magnetic layer 3 exposed on the side surface of the magnetic layer 3 can be covered with the rust preventive agent, and rust can be effectively prevented.

In particular, it is effective in preventing spot-like rust formation on the side surface of the tape during storage in the reel state. Moreover, since the rust preventive agent 9 is applied while being encapsulated in the microcapsules 7, the rust preventive agent can be easily distributed.

In addition, the magnetic layer is in direct contact with the base film (actually SiO ₂₎ except in this island-shaped distribution region.
Some are via particles 8. ) A region is formed and the adhesion between the magnetic layer and the base film is improved in the place where the rust preventive agent is not present. This is even better when there is an undercoat layer under the magnetic layer.

Although the embodiments of the present invention have been described above, various modifications can be added to the above embodiments based on the technical idea of the present invention.

For example, by changing the distribution of the above-mentioned microcapsules, it is possible to variously change the distribution density and distribution area of the rust preventive agent between the magnetic layer and the base film. Further, the distribution method of the microcapsules may be a method other than coating, for example, adhesion. This is shown in FIG.
It can be realized by adhering an anticorrosive agent to the cutting blade at the time of slitting shown in (1) or by contacting a felt impregnated with the anticorrosive agent with the side surface of the medium.

Further, in the above-mentioned embodiment, the microcapsules containing the rust preventive agent are applied on the upper surface of the base film to deposit the magnetic layer, but the microcapsules can be distributed in the base film. As a result, the rust preventive agent breaks the microcapsules at the time of cutting, exudes and adheres to the side surface of the base film from here, and in addition to the effect when distributed in islands on the base film as described above, The cut surface of the layer becomes more fully covered.

The rust preventive agent may be contained in the binder resin and applied instead of being encapsulated in the microcapsules. Further, if a rust preventive agent layer is provided as the top coat layer, the generation of rust on the surface of the magnetic layer can be suppressed.

In addition to the structure of the above-mentioned embodiment, it is also possible to coat the side surface of the magnetic tape or substantially the side surface of the magnetic layer with a rust preventive agent in another step, and by doing so, further corrosion can be achieved. The effect of suppressing the occurrence of is increased.

Further, in the above-mentioned embodiment, the magnetic layer is formed by the vacuum vapor deposition method, but other than this, for example, the magnetic layer may be formed by the sputtering method in which the substrate is heated at a predetermined temperature. . The present invention is very effective when the magnetic layer is a metal thin film type, but it may be a coating type magnetic layer.

In addition to the magnetic tape, the present invention can be similarly applied to a magnetic disk such as a floppy disk or a magnetic sheet manufactured by being cut into a predetermined shape from an original fabric. When the present invention is applied to a magnetic disk, the magnetic disk is manufactured by a step of punching into a circular shape after forming the magnetic recording medium constituting layer.

At this time, since the magnetic metal thin film exposed on the outer peripheral surface and the inner peripheral surface of the above-mentioned rust preventive agent layer has a rust preventive action, it is not so long (the surface area is smaller than that of the magnetic tape). The disk is effective for maintaining the magnetic characteristics. In addition, when the side surface of the punching die (for example, punch and die) is wetted with the rust preventive solution at the time of the above-mentioned punching, the rust preventive agent film can be formed on the inner and outer peripheral surfaces of the magnetic disk.

[0114]

The magnetic recording medium according to the present invention is a magnetic recording medium in which a magnetic layer is provided on a substrate,
Since the rust preventive agent is distributed in an island shape between the substrate and the magnetic layer, the presence of the rust preventive agent causes high temperature,
Even if stored or used in a high-humidity environment, rust can be effectively prevented from occurring on the magnetic particles of the magnetic layer even if an oxidizing substance enters from the side surface or other area thereof.

Since the rust preventive agent is distributed in an island shape,
In the non-distributed region, a region where the base body and the magnetic layer are in contact with each other is secured, the adhesiveness between the magnetic layer and the base body is enhanced, the mechanical strength of the magnetic recording medium is maintained, and its durability and reliability are high. Become.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a main part of a magnetic tape according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged cross-sectional perspective view of a main part of the magnetic tape.

FIG. 4 is an enlarged cross-sectional view showing a state of one side surface of the magnetic tape.

FIG. 5 is a cross-sectional view of a portion corresponding to FIG. 1, showing a state immediately after coating the microcapsules containing the rust preventive agent on the base film in the process of manufacturing the magnetic tape.

FIG. 6 shows a process of breaking the microcapsule,
3A is a cross-sectional view showing a state before destruction, FIG.

FIG. 7 shows the destruction process of the same microcapsule in the process of forming the magnetic layer of the magnetic tape, where (a) shows the state at the start of destruction, (b) shows the state of progress of destruction, and (c) shows the state after destruction. FIG. 3 is an enlarged cross-sectional view of a main part showing.

FIG. 8 is a flowchart of manufacturing the same microcapsules.

FIG. 9 is a flow chart of manufacturing the magnetic tape.

FIG. 10 is a schematic front view showing the coating apparatus.

FIG. 11 is a schematic cross-sectional view showing the same vacuum vapor deposition device.

FIG. 12 is a perspective view showing the magnetic tape original fabric.

FIG. 13 is a schematic front view showing a cutting device for the same magnetic tape original fabric.

FIG. 14 is a front view showing a main part of a cutting machine of the cutting device.

15 is a side view taken along line XV-XV in FIG.

FIG. 16 is an enlarged sectional perspective view of a conventional magnetic tape.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic tape, 2 ... Base film, 2A-2D ... Base film in the manufacturing process from a base film to a raw material, 3 ... Magnetic layer (metal magnetic thin film), 4 ... Protective layer, 5
... Top coat layer, 6 ... Back coat layer, 7 ... Microcapsule, 8 ... SiO ₂ fine particles, 9 ... Rust preventive agent, 9A ... Rust preventive agent solution, 9B ... Rust preventive agent film

Claims (14)

[Claims] 1. A magnetic recording medium having a magnetic layer provided on a substrate, wherein a rust preventive agent is distributed in an island shape between the substrate and the magnetic layer. Magnetic recording medium. ^2. The magnetic recording medium according to claim 1, wherein the rust preventive agent is arranged at a distribution density of 10 to 10 million pieces / m ² . 3. The magnetic recording medium according to claim 1, wherein a magnetic layer made of a magnetic metal thin film is formed on a non-magnetic support, and a hard protective layer is provided on the magnetic layer. 4. The magnetic recording medium according to claim 1, wherein nonmagnetic particles are arranged between the base and the magnetic layer. 5. The magnetic recording medium according to claim 4, wherein the non-magnetic particles are arranged at a distribution density of 10 to 10 million particles / m ² . 6. A method of manufacturing a magnetic recording medium, which comprises a step of distributing a rust preventive agent covered with a coating on a substrate, and a step of forming a magnetic layer on the substrate thereafter. 7. The method according to claim 6, comprising a step of covering the rust preventive agent with a film by an interfacial polycondensation reaction in a state where the rust preventive agent is included. 8. The method according to claim 6, wherein the rust preventive agent is covered with a polymer film by an interfacial polycondensation reaction between the fine emulsion particles in the water-in-oil emulsion and the medium liquid. 9. The method according to claim 6, wherein the coating-coated rust preventive agent is arranged at a distribution density of 10 to 10 million pieces / m ² . 10. The particle size of the rust preventive agent covered with a film is 10 to 1,00.
The method according to claim 6, wherein the thickness is 0 nm. 11. An anticorrosive agent covered with a coating is adhered onto a substrate, and a magnetic layer comprising a metal magnetic thin film is vapor-deposited thereon.
The method according to claim 6. 12. The method according to claim 11, wherein a solution of the coated rust inhibitor is applied onto the substrate. 13. The method according to claim 12, wherein the concentration of the rust inhibitor solution is 0.2% by weight to 50% by weight. 14. The method according to claim 6, wherein a hard protective layer is formed on the magnetic layer.