JPH10188264A - Magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the formation of the burned matter of a magnetic head by combining either of a pyridine deriv. and phenanthrene deriv. and a silane coupling agent and holding the combination in a magnetic layer. SOLUTION: The magnetic layer is formed by applying a magnetic coating material composed mainly of ferromagnetic powder and binder on a nonmagnetic base. At the time of preparing the magnetic coating material, the ferromagnetic powder is previously subjected to the surface treatment with the silane coupling agent and the powder and the binder are kneaded and dispersed together with either of the bipyridine deriv. or the phenanthrene deriv. Since the silane coupling agent is adsorbed on the ferromagnetic powder, the dispersibility of the ferromagnetic powder is improved. In addition, the coordination of the bipyridine deriv. and the phenanthrene deriv. to the ferromagnetic powder is hindered and the bipyridine deriv. and the phenanthrene deriv. alone disperse in the magnetic layer or adhere to the surface of the magnetic layer. The bipyridine deriv. and the phenanthrene deriv. are capable of preventing the accumulation of the burned matter as a complex to easily desorb the burned matter from the magnetic head surface by making complex forming reaction with the burned matter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magnetic recording medium for preventing sticking matter from adhering to a magnetic head and a method of manufacturing the same.

[0002]

2. Description of the Related Art In the field of magnetic recording, in particular, in a data cartridge for backing up a hard disk, a digital video recorder, and the like, there is a demand for long-time recording along with higher-capacity recording. Conventionally, this long-time recording has been dealt with by increasing the length of the tape by reducing the thickness of the tape, or by increasing the length of the tape by changing the cassette shell or the like.

In the above-mentioned data cartridge, recording and reproduction by a helical scan system is generally applied. However, in the helical scan method, since the magnetic layer surface and the magnetic head slide at high speed, the temperature of the magnetic head surface becomes high during running of the magnetic tape, so that seizure tends to be easily generated on the surface of the magnetic head. If the sliding time is increased or the scanning speed is increased in association with long-time recording, a burn-in product is more easily generated on the surface of the magnetic head.

Particularly, in an environment such as high temperature and low humidity, the polishing power of the magnetic tape is reduced. Therefore, when a metal oxide or the like generated tribologically causes seizure, the seized material is not polished and the magnetic head is not polished. Accumulate on the surface. And, by the accumulated seizures,
A gap (spacing) occurs between the magnetic tape and the magnetic head, causing a problem that a predetermined signal output cannot be obtained.

At present, in order to improve the electromagnetic conversion characteristics and reduce the spacing loss, the surface properties of the tape are improved by super calendar treatment or the like, and the friction between the magnetic tape and the magnetic head is further increased. Tend to be. However, this tendency promotes the generation of burn-in on the surface of the magnetic head described above.

Attempts have been made to add a reducing agent, such as an ascorbic acid derivative, to the magnetic tape as an antioxidant in order to prevent the occurrence of seizures on the magnetic head. Attempts have been made to increase the amount of lubricant used. On the other hand, a cleaning tape for physically polishing the head has been used in order to remove the seized product once formed, and a method of attaching a cleaning roll mechanism for sequentially polishing the magnetic head in the system has been studied. .

[0007] However, even if an antioxidant or a lubricant is held on the magnetic tape, it is not possible to remove the seized product once formed. Further, even with a method of physically polishing a magnetic head, there is a problem that if the polishing force is too high, the magnetic head is polished more than necessary and the characteristics are deteriorated.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional situation, and in order to achieve long-time recording, the sliding time is increased or the scanning speed is increased. Another object of the present invention is to provide a magnetic recording medium capable of preventing a magnetic head from causing burn-in, suppressing a decrease in output due to spacing loss, and preventing an increase in an error rate, and a method for manufacturing the same.

[0009]

Means for Solving the Problems The present inventors have made intensive studies on achieving the above object and as a result, as a result, combined with at least one of a pyridine derivative and a phenanthrin derivative and a silane coupling agent to form a magnetic layer. It has been found that by holding the magnetic head, generation of seizure on the magnetic head is suppressed, and the present invention has been completed.

That is, the magnetic recording medium according to the present invention comprises:
A magnetic coating mainly composed of ferromagnetic powder and a binder is applied on a non-magnetic support to form a magnetic layer. The magnetic layer contains a silane coupling agent, and contains a bipyridine derivative and a phenanthrin derivative. Characterized by containing at least one of the following.

[0011] The method of manufacturing a magnetic recording medium according to the present invention comprises:
In preparing a magnetic paint mainly composed of a ferromagnetic powder and a binder, a silane coupling agent is added to the magnetic paint, and then a bipyridine derivative and / or a phenanthrin derivative are added. I do.

Therefore, when preparing the magnetic paint, the ferromagnetic powder is previously subjected to a surface treatment with a silane coupling agent, and then the surface-treated ferromagnetic powder and a binder are combined with a bipyridine derivative, It may be kneaded and dispersed with at least one of the phenanthrin derivatives. Alternatively, the ferromagnetic powder, the binder, and the silane coupling agent may be kneaded and dispersed, and thereafter, at least one of a bipyridine derivative and a phenanthrin derivative may be added.

According to the present invention, a silane coupling agent, which is a dispersant for a magnetic powder, and a bipyridine derivative or a phenanthrin derivative capable of forming a complex with a metal are combined and held in the magnetic layer, so that the magnetic head is seized. Can be prevented from adhering.

That is, here, the silane coupling agent is sufficiently adsorbed to the ferromagnetic powder, thereby improving the dispersibility of the ferromagnetic powder and preventing the bipyridine derivative or the phenanthrin derivative from coordinating to the ferromagnetic powder. . As a result, the bipyridine derivative or the phenanthrin derivative is dispersed alone in the magnetic layer or adheres to the surface of the magnetic layer. The bipyridine derivative and the phenanthrin derivative form a complex that undergoes a complex-forming reaction with the burn-in product formed on the surface of the magnetic head, and the burn-in product is easily desorbed from the magnetic head surface, so that the burn-in product does not accumulate on the magnetic head surface.

As described above, the silane coupling agent not only disperses the magnetic powder but also suppresses the coordination of the bipyridine derivative and the phenanthrin derivative to the ferromagnetic powder.
The bipyridine derivative and the phenanthrin derivative can effectively contribute to the complex formation reaction with the seizure.

The silane coupling agent preferably has at least one or more functional groups selected from an amino group, an epoxy group, a vinyl group and an isocyanate group.

It is preferable to use a compound represented by the following chemical formula 5 as the bipyridine derivative, and to use a compound represented by the following chemical formula 6 as the phenanthrin derivative.

[0018]

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[0019]

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Further, the magnetic layer preferably contains a silane coupling agent in a ratio of 0.5 to 5 parts by weight based on 100 parts by weight of the ferromagnetic powder.

When the content of the silane coupling agent is less than the above lower limit, the bipyridine derivative and the phenanthrin derivative are coordinated with the ferromagnetic powder, and the anti-seizure effect is reduced and the dispersibility of the ferromagnetic powder is reduced. And good electromagnetic conversion characteristics cannot be ensured. When the content of the silane coupling agent is larger than the above upper limit, a large amount of the functional group which has not reacted with the binder remains in the magnetic layer, and these interact with each other to lower the dispersibility.

The magnetic layer may include a bipyridine derivative,
It is preferable that at least one of the phenanthrin derivatives is contained in a ratio of 0.3 to 10 parts by weight based on 100 parts by weight of the ferromagnetic powder.

When the content of the bipyridine derivative or the phenanthrin derivative is less than the above lower limit, the effect of preventing image sticking is not sufficient. When the content of the bipyridine derivative or the phenanthrin derivative is larger than the above upper limit, good electromagnetic conversion characteristics cannot be secured because the running property of the magnetic head is inhibited or the dispersibility of the magnetic powder is reduced.

Therefore, while adding the silane coupling agent to the magnetic layer, the bipyridine derivative,
In a magnetic recording medium to which at least one of the phenanthrin derivatives is added, a decrease in output of spacing loss due to accumulation of seizures on the magnetic head can be prevented, and an error rate can be suppressed.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the magnetic recording medium according to the present invention will be described below.

The magnetic recording medium according to the present invention comprises a non-magnetic support and a magnetic paint mainly composed of a ferromagnetic powder and a binder applied to form a magnetic layer. It is characterized by containing a ring agent and at least one of a bipyridine derivative and a phenanthrin derivative. Hereinafter, the bipyridine derivative or the phenanthrin derivative is referred to as a ligand.

According to the method of manufacturing a magnetic recording medium, when preparing a magnetic paint mainly composed of a ferromagnetic powder and a binder, a silane coupling agent is added to the magnetic paint, and then a ligand is added. It is characterized by being added.

In the present invention, the silane coupling agent needs to be added to the magnetic paint before the ligand. For this reason, when preparing a magnetic paint, the ferromagnetic powder is subjected to a surface treatment with a silane coupling agent in advance, and then the surface-treated ferromagnetic powder and a binder are kneaded and dispersed together with a ligand. Good to do. Alternatively, the ferromagnetic powder, the binder, and the silane coupling agent may be kneaded and dispersed, and then the ligand may be added.

In the present invention, a silane coupling agent, which is a dispersant for a magnetic powder, and a ligand (bipyridine derivative or phenanthrin derivative) capable of forming a complex with a metal are combined and contained in a magnetic layer. In addition, it is possible to prevent sticking matter from adhering to the magnetic head.

That is, here, the silane coupling agent is sufficiently adsorbed on the ferromagnetic powder, thereby improving the dispersibility of the ferromagnetic powder and preventing the ligand from coordinating to the ferromagnetic powder. As a result, the ligand alone becomes dispersed in the magnetic layer or adheres to the surface of the magnetic layer. Then, the ligand undergoes a complex formation reaction with a burn-in product formed on the surface of the magnetic head to form a complex that easily releases the burn-off product from the surface of the magnetic head, and does not accumulate the burn-in product on the surface of the magnetic head. If the silane coupling agent is not added, the ligand coordinates to the ferromagnetic powder to form a complex, so that the ligand does not form a complex with seizure (metal oxide) on the surface of the magnetic head. It is not possible to remove seizures on the surface.

As described above, the silane coupling agent not only disperses the ferromagnetic powder but also suppresses the ligand from coordinating to the ferromagnetic powder, and the ligand is effective for the complex formation reaction with the seizure. To contribute to

Therefore, the addition of the silane coupling agent to the magnetic layer and the addition of a ligand (at least one of a bipyridine derivative and a phenanthrin derivative)
In a magnetic recording medium to which is added, the output of spacing loss due to accumulation of burn-in on the magnetic head is prevented, and the error rate can be reduced.

The silane coupling agent used in combination with the above-mentioned ligand is not particularly limited as long as it is a coupling agent exhibiting strong adsorptivity to ferromagnetic powder. It preferably has at least one or more functional groups selected from an epoxy group, a vinyl group, and an isocyanate group.

The content of the silane coupling agent is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the ferromagnetic powder. When the content of the silane coupling agent is less than the above lower limit, the ligand coordinates to the ferromagnetic powder, the anti-seizure effect is reduced, the dispersibility of the ferromagnetic powder is reduced, and good electromagnetic conversion is performed. Characteristics cannot be secured. When the content of the silane coupling agent is larger than the above upper limit, a large amount of the functional group which has not reacted with the binder remains in the magnetic layer, and these interact with each other to lower the dispersibility. Therefore, the content of the silane coupling agent is set to 0.5 to 5 parts by weight based on 100 parts by weight of the ferromagnetic powder in order to improve the dispersibility of the ferromagnetic powder and suppress generation of seizure on the magnetic head. Parts by weight are preferred.

As the silane coupling agent, 2
More than one type of silane coupling agent may be used, or the silane coupling agent may be used in combination with other additives, as long as the content of the silane coupling agent is within the above range.

On the other hand, as the ligand used here,
A bipyridine derivative represented by the following chemical formula 7 and a phenanthrin derivative represented by the following chemical formula 8 are preferable.

[0037]

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[0038]

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The content of the ligand comprising at least one of the bipyridine derivative and the phenanthrin derivative is preferably from 0.3 to 10 parts by weight based on 100 parts by weight of the ferromagnetic powder. When the content of the ligand is smaller than the above lower limit, the effect of suppressing the generation of seizure on the magnetic head is not sufficient. On the other hand, when the content of the ligand is larger than the above upper limit, the running property of the magnetic head is impaired, or the dispersibility of the magnetic powder is reduced, so that good electromagnetic conversion characteristics cannot be secured. Therefore, the content of the ligand is set to 100 parts by weight of the ferromagnetic powder in order to improve the dispersibility of the ferromagnetic powder and sufficiently exhibit the effect of suppressing the generation of seizure on the magnetic head. 0.3 to 10 parts by weight is preferred.

As the ligand, a bipyridine derivative or a phenanthrin derivative may be used alone, or a plurality of these may be used in combination. What is necessary is just within the range mentioned above.

The ferromagnetic powder used to form the magnetic layer includes metals such as Fe, Co, and Ni;
Fe-Co, Fe-Ni, Fe-Al, Fe-Ni-A
1, Fe-Al-P, Fe-Ni-Si-Al, Fe-
Ni-Si-Al-Mn, Fe-Mn-Zn, Fe-N
i-Zn, Co-Ni, Co-P, Fe-Co-Ni,
Fe-Co-Ni-Cr, Fe-Co-Ni-P, Fe
-Co-B, Fe-Co-Cr-B, Mn-Bi, Mn
-Al, alloys such as Fe-Co-V, iron nitride, iron carbide and the like. Needless to say, even if an appropriate amount of a light metal element such as Al, Si, P, or B is added for the purpose of preventing sintering or maintaining the shape during reduction, the effects of the present invention are not hindered.

Further, as the ferromagnetic powder, γ-Fe ₂
O ₃ , Fe ₃ O ₄ , a beltride compound of γ-Fe ₂ O ₃ and Fe ₃ O ₄ , γ-Fe ₂ O ₃ containing Co, Fe ₃ O ₄ containing Co, γ containing Co -fe ₂ O ₃ and Fe ₃ O ₄
And oxides in which one or more metal elements, for example, Te, Sb, Fe, B, etc., are contained in CrO ₂ . Further, hexagonal plate-like ferrite can also be used, and examples thereof include M-type, W-type, Y-type, and Z-type barium ferrite, strontium ferrite, calcium ferrite, and lead ferrite. Further, for the purpose of controlling the coercive force, Co-Ti, Co-
Ti-Zn, Co-Ti-Nb, Co-Ti-Zn-N
Those added with b, Cu-Zr, Ni-Ti or the like can also be used.

These ferromagnetic powders can be used alone or in combination of two or more.

The specific surface area of the ferromagnetic powder used in the present invention is 30 to 80 m ² / g, preferably 40 to 70 m ² / g.
m ² / g is desirable. When the specific surface area is within the above range, high-density recording becomes possible as the shape of the ferromagnetic powder becomes finer, and a magnetic recording medium having excellent noise characteristics can be obtained.

Further, the ferromagnetic powder used in the present invention preferably has a major axis length of 0.05 to 0.50 μm and an axial ratio of 2 to 15. When the major axis length is less than 0.05 μm, dispersion in the magnetic coating material becomes difficult, and when the major axis length exceeds 0.50 μm, noise characteristics may deteriorate, which is not preferable. When the axial ratio is less than 5, the orientation of the ferromagnetic powder decreases and the output decreases. If the axial ratio exceeds 15, the short-wavelength signal output may decrease, which is not preferable. In the case of plate-like ferrite, the plate diameter is 0.01 to 0.5 μm and the plate thickness is 0.001 to 0.2 μm
The degree is preferred. As the major axis length, the axial ratio, the plate diameter, and the plate thickness, an average value of 100 or more samples randomly selected from a transmission electron micrograph is adopted.

As the binder contained in the magnetic layer, known thermoplastic resins, thermosetting resins, reactive resins and the like which have been conventionally used as binders for magnetic recording media can be used. Number average molecular weight is 5,000 to 100,000
Are preferred.

Examples of the thermoplastic resin include vinyl chloride,
Vinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate-acrylonitrile copolymer, acrylate-vinyl chloride-vinylidene chloride copolymer , Vinyl chloride-acrylonitrile copolymer, acrylate-acrylonitrile copolymer, acrylate-vinylidene chloride copolymer, methacrylate-vinylidene chloride copolymer, methacrylate-vinyl chloride copolymer, methacrylic acid Ester-ethylene copolymer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, cell Over scan diacetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene - butadiene copolymer, polyurethane resin, polyester resin, amino resin, synthetic rubber, and the like.

Examples of the thermosetting resin or the reactive resin include a phenol resin, an epoxy resin, a polyurethane curable resin, a urea resin, a melamine resin, an alkyd resin, a silicone resin, a polyamine resin, and a urea formaldehyde resin.

[0049] Also, all of the binding agent described above, in order to improve the dispersibility of the _{pigment, -SO 3 M, -OSO 3 M} , -
A polar functional group such as COOM and P = O (OM) ₂ may be introduced. Here, M is a hydrogen atom or lithium,
It is an alkali metal such as potassium and sodium. Further, the polar functional groups include -NR ¹ R ² , -NR ¹ R
A side chain type having a terminal group of ² R ^{3 +} X ⁻ ,> NR ¹ R ²⁺
Wherein X ^- include those of the main chain type. Where R ¹ , R
² and R ³ are a hydrogen atom or a hydrocarbon group, and X is a halogen element ion such as fluorine, chlorine, bromine or iodine or an inorganic / organic ion. Also, -OH, -SH,-
There are also polar functional groups such as CN and epoxy groups. The content of these polar functional groups is 10 ^-8 to 10 ^-1 mol / g, preferably 10 ^-6 to 10 ^-2 mol / g.

These binders can be used alone or in combination of two or more. The content of the binder in the magnetic layer is 1 to 200 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the ferromagnetic powder or the nonmagnetic powder. If the content of the binder is too large, the ratio of the ferromagnetic powder occupying the magnetic layer relatively decreases and the output decreases, and plastic flow tends to occur due to repeated sliding in a drive,
The running durability of the magnetic recording medium decreases. On the other hand, when the content of the binder is too small, the coating film becomes brittle, and the running durability of the magnetic recording medium decreases.

Further, a polyisocyanate for crosslinking and curing the above binder can be used in combination. Examples of the polyisocyanate include toluene diisocyanate and adducts thereof, alkylene diisocyanate and adducts thereof. The mixing amount of these polyisocyanates with the binder is 5 to 80 parts by weight, preferably 10 to 5 parts by weight, based on 100 parts by weight of the binder.
0 parts by weight.

The magnetic layer is formed by applying a magnetic coating material on a non-magnetic support and drying it. Examples of solvents used for forming the coating material include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Ketone solvents, methanol, ethanol, alcohol solvents such as propanol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate, ester solvents such as ethylene glycol acetate, diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, Ether solvents such as dioxane, benzene, toluene, aromatic hydrocarbon solvents such as xylene, methylene chloride, ethylene chloride, carbon tetrachloride,
Examples thereof include halogenated hydrocarbon solvents such as chloroform and chlorobenzene.

Further, a lubricant can be contained in the magnetic layer as required. As the above lubricant,
Examples include graphite, molybdenum disulfide, tungsten disulfide, silicone oil, fatty acids having 10 to 22 carbon atoms, fatty acid esters composed of these and alcohols having 2 to 26 carbon atoms, terpene compounds, and oligomers thereof.

The magnetic layer may contain abrasive particles, if necessary. As the abrasive particles, aluminum oxide (α, β, γ), chromium oxide,
Silicon carbide, diamond, garnet, emery, boron nitride, titanium carbide, silicon carbide, titanium carbide, titanium oxide (rutile, anatase) and the like. These abrasive particles are based on 100 parts by weight of the ferromagnetic powder.
20 parts by weight or less, preferably 10 parts by weight or less is desirable. Further, these abrasive particles have a Mohs hardness of 4 or more, preferably 5 or more, and a specific gravity of 2 to 6, preferably 3 to 5. Average particle size is 0.5 μm
Or less, preferably 0.3 μm or less. The average particle size of the abrasive particles is also measured from a transmission electron micrograph and processed statistically, as in the case of the ferromagnetic powder.

As described above, a magnetic paint is prepared from the above-mentioned silane coupling agent, ligand, magnetic powder, binder, if necessary, a lubricant, an abrasive, etc., and is applied to a non-magnetic support and dried. A magnetic layer is formed.

Examples of the nonmagnetic support include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, celluloses such as cellulose triacetate and cellulose diacetate, vinyl resins, polyimides, and the like.
Examples of the support include polymer materials represented by polycarbonates, and supports formed of metal, glass, ceramics, and the like.

The adjustment of the magnetic paint is performed in each of the kneading step, the mixing step, and the dispersion step. For dispersing and kneading, a roll mill, a ball mill, a sand mill, an agitator, a kneader, an extruder, a homogenizer, an ultrasonic disperser and the like are used. After the preparation of the magnetic paint, the magnetic paint may be applied and dried by any method such as spraying or roll application on the non-magnetic support.

The configuration of the magnetic recording medium according to the present invention is not particularly limited. For the purpose of improving the runnability of the magnetic recording medium, preventing charge and transfer, and the like,
A back coat layer may be provided on the surface of the non-magnetic support opposite to the surface on which the magnetic layer is formed. Further, if necessary, a top coat layer made of a lubricant, a rust inhibitor, or the like may be provided on the magnetic layer. The top coat layer and the back coat layer may be applied with a magnetic paint, dried, guided to a calender, wound on a take-up roll, and then applied and dried.

The basic configuration of the present invention has been described above. The magnetic recording medium may be provided with an additional configuration to further improve the characteristics.

For example, a non-magnetic layer (lower layer) in which non-magnetic powder is dispersed in a binder is provided between the magnetic layer and the non-magnetic support in order to obtain smoothness of the magnetic layer (upper layer). It is also possible. This is generally called a multilayer coating type magnetic recording medium. In the case of the multilayer coating type magnetic recording medium, examples of the nonmagnetic powder used for the nonmagnetic layer include nonmagnetic iron oxides such as α-Fe ₂ O ₃ , goethite, rutile type titanium oxide, anatase type titanium oxide, and oxides. Tin, tungsten oxide, silicon oxide, zinc oxide, chromium oxide, cerium oxide, titanium carbide, BN, α-alumina,
There are β-alumina, γ-alumina, calcium sulfate, barium sulfate, molybdenum disulfide, magnesium carbonate, calcium carbonate, barium carbonate, strontium carbonate, barium titanate and the like.

These non-magnetic powders can be used alone or in combination of two or more. These nonmagnetic powders can be doped with an appropriate amount of impurities according to the purpose.Also, for the purpose of improving dispersibility, improving conductivity, imparting conductivity, improving color tone, etc. , Si, Ti, Sn, Sb, Zr and the like. The non-magnetic powder has a non-surface area of 30 to 80 m ² / g, preferably 40 to 70 m ² / g.
It is.

The non-magnetic layer may contain, in addition to the above-described non-magnetic powder, carbon black such as rubber furnace, pyrolytic carbon, color black, and acetylene black, if necessary. The specific surface area of these carbon blacks is 100 to 400 m ² / g, DBP
(Dibutyl phthalate) Oil absorption is 2
It is preferably from 0 to 200 ml / 100 g.

The specific surface areas of the non-magnetic powder and carbon black are determined so that the non-magnetic layer (lower layer) is formed on a smooth surface, whereby the magnetic layer (upper layer) is formed on a smooth surface. In order to By smoothing the magnetic layer (upper layer), it is possible to obtain a magnetic recording medium that has excellent modulation noise characteristics and is less affected by spacing loss.

[0064]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described, but it goes without saying that the present invention is not limited to the embodiments.

EXPERIMENTAL EXAMPLE a Hereinafter, in Experimental Examples 1-a to 19-a, the addition amount and type of the silane coupling agent and the ligand (bipyridine derivative) shown in Chemical formula 9 were changed. The magnetic layer was held on the magnetic layer to produce a magnetic tape.

<Experimental Example 1-a> Preparation of Magnetic Paint and Preparation of Magnetic Recording Medium Composition of Magnetic Paint 100 parts by weight of Fe-based metal ferromagnetic powder (coercive force: 160 kA / m, saturation magnetization: 145 Am ² / kg ratio) Surface area: 51 m ² / g, major axis length: 0.08 μm, needle ratio: 3) Polyvinyl chloride resin (trade name: MR-110, manufactured by Zeon Corporation) 14 parts by weight Polyester polyurethane resin (manufactured by Toyobo Co., Ltd.) 3 5 parts by weight Additive (Al ₂ O ₃ ) 5 parts by weight ₃ parts by weight of a silane coupling agent represented by the following chemical formula 3 parts by weight 1 part by weight of stearic acid 1 part by weight of heptyl stearate 1 part by weight of methyl ethyl ketone 150 parts by weight of cyclohexanone 150 parts by weight After mixing the ferromagnetic powder represented by the composition, a binder, an additive, a solvent, and a silane coupling agent, and kneading with an extruder And dispersed in a sand mill for 6 hours.

Next, 3 parts by weight of a polyisocyanate was added thereto, and as shown in Table 1, the substituent R ¹ in Chemical formula 9 was added.
As shown in Table 2, 3 parts by weight of a ligand 1 (bipyridine derivative) in which R ⁸ is H was added to prepare a magnetic paint.
Then, the magnetic paint was coated on a 7 μm thick base film (polyethylene terephthalate) with a thickness of 6.5 μm.
It applied so that it might become. Thereafter, orientation treatment was performed by a solenoid coil, and drying, calendar treatment, and curing treatment were performed.

Back coating composition : 100 parts by weight of carbon black (trade name: Asahi # 50) 100 parts by weight of polyester polyurethane (trade name: Nipporan N-2304) 500 parts by weight of methyl ethyl ketone 500 parts by weight of toluene It was applied to the opposite side of the base film from the application surface. The film thus obtained was slit into a width of 8 mm and assembled into an 8 mm cassette to prepare a magnetic tape.

[0069]

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[0070]

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[0071]

[Table 1]

[0072]

[Table 2]

<Experimental Examples 2-a to 7-a> The amount of the ligand 1 (bipyridine derivative) shown in Table 1 was determined in accordance with Table 2.
The magnetic paint was prepared in the same manner as in Experimental Example 1-a, except that the addition amount was changed as shown in Table 2, and a magnetic tape was produced.

<Experimental Examples 8-a to 11-a>
The magnetic coating material was prepared in the same manner as in Experimental Example 1-a, except that the amount of the silane coupling agent shown in Table 2 was changed to the amount shown in Table 2, to prepare a magnetic tape.

<Experimental Examples 12-a to 14-a> Ligand 1 (bipyridine derivative) was obtained by substituting the substituents R ² , R ⁴ , R ⁵ and R ^{7 in} Chemical Formula 9 with H, ^1, R ^3,
As shown in Table 1, R ⁶ and R ⁸ were changed to various ligands 2 (bipyridine derivatives) to 4 (bipyridine derivatives). In Table 1, Ar represents an aryl group. Except for this, the magnetic paint was prepared in the same manner as in Experimental Example 1-a to produce a magnetic tape.

<Experimental Examples 15-a to 18-a>
The silane coupling agent represented by 0 is
A magnetic paint was prepared in the same manner as in Experimental Example 1-a, except that the silane coupling agent shown in Chemical formula 14 was used, to prepare a magnetic tape.

[0077]

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[0078]

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[0079]

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[0080]

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<Experimental Example 19-a> A surface treatment with a silane coupling agent was performed on a ferromagnetic powder without adding a silane coupling agent to a magnetic paint. Then, the ferromagnetic powder which has been subjected to surface treatment in advance is kneaded and dispersed together with a binder and ligand 1 (bipyridine derivative), and a magnetic paint is prepared in the same manner as in Experimental Example 1-a to produce a magnetic tape. did.

<Comparative Example 1-a> Ligand 1 shown in Table 1
A magnetic paint was prepared in the same manner as in Experimental Example 1-a, except that (bipyridine derivative) was not added to the magnetic paint. <Comparative Example 2-a> Experimental Example 1 except that the ligand 1 (bipyridine derivative) shown in Table 1 was not added to the magnetic paint.
The magnetic paint was prepared in the same manner as in 5-a to prepare a magnetic tape.

Comparative Example 3-a A magnetic tape was prepared in the same manner as in Experimental Example 1-a except that the silane coupling agent represented by Chemical formula 10 was not added to the magnetic paint. .

EXPERIMENTAL EXAMPLE b Next, in Experimental Examples 1-b to 19-b, the addition amount and type of the silane coupling agent and the ligand (phenanthrin derivative) The magnetic tape was produced by holding the magnetic layer in a different manner.

<Experimental Example 1-b> Ligand 1 shown in Table 1
As shown in Table 3, (bipyridine derivative) was replaced with ligand 5 (phenanthrin derivative) in which substituents R ^{9 to} R ^{16 in} Chemical Formula 15 were H, and 3 parts by weight were added as shown in Table 4. . Except for this, the magnetic paint was prepared in the same manner as in Experimental Example 1-a to produce a magnetic tape.

[0086]

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[0087]

[Table 3]

[0088]

[Table 4]

<Experimental Examples 2-b to 7-b> The amount of the ligand 5 (phenanthrin derivative) shown in Table 3 was
Experimental example 1-b except that the addition amount was changed as shown in Table 4.
The magnetic paint was prepared in the same manner as described above to produce a magnetic tape.

<Experimental Examples 8-b to 11-b>
The magnetic coating material was prepared in the same manner as in Experimental Example 1-b, except that the amount of the silane coupling agent shown in Table 4 was changed to the amount shown in Table 4, to prepare a magnetic tape.

<Experimental Examples 12-b to 14-b> Table 3
Is converted to ligand 5 (phenanthrin derivative)
5 is a substituent R ¹⁰ , R ¹² , R ¹³ , R ¹⁵ is H,
As shown in Table 3, the substituents R ⁹ , R ¹¹ , R ¹⁴ , and R ¹⁶ were changed to different ligands 6 (phenanthrin derivatives) to 8 (phenanthrin derivatives). In Table 3, Ar
Represents an aryl group. Except for this, the magnetic paint was prepared in the same manner as in Experimental Example 1-b to produce a magnetic tape.

<Experimental Examples 15-b to 18-b>
Except that the silane coupling agent represented by 0 was changed to the silane coupling agent represented by the above formulas 11 to 14,
A magnetic paint was prepared in the same manner as in Experimental Example 1-b to produce a magnetic tape.

<Experimental Example 19-b> A surface treatment with a silane coupling agent was performed on a ferromagnetic powder without adding a silane coupling agent to a magnetic paint. Then, the ferromagnetic powder having been subjected to the surface treatment in advance was kneaded and dispersed together with a binder and a ligand 5 (phenanthrin derivative).
A magnetic paint was prepared in the same manner as in b to prepare a magnetic tape.

<Comparative Example 1-b> Ligand 5 shown in Table 3
A magnetic paint was prepared in the same manner as in Experimental Example 1-b except that (phenanthrin derivative) was not added to the magnetic paint.
A magnetic tape was produced. <Comparative Example 2-b> A magnetic paint was prepared in the same manner as in Experimental Example 15-b except that the ligand 5 (phenanthrin derivative) shown in Table 3 was not added to the magnetic paint. did.

<Comparative Example 3-b> A magnetic tape was prepared in the same manner as in Experimental Example 1-b except that the silane coupling agent represented by Chemical formula 10 was not added to the magnetic paint. .

Evaluation of magnetic tape As described above, Experimental Examples 1-a to 19-a and Experimental Examples 1-b
-Experimental Example 19-b (hereinafter referred to as Experimental Examples 1 to 19)
Called. ), The magnetic tapes manufactured in Comparative Examples 1-a to 3-a and Comparative Examples 1-a to 3-a (hereinafter, referred to as Comparative Examples 1 to 3), The conversion characteristics were measured.

The measurement of the electromagnetic conversion characteristics was carried out using a fixed head type electronic measuring device. This measuring device is composed of a rotating drum and a head that comes into contact with the rotating drum, and a magnetic tape is wound around the drum. In actual measurement, first, a 10-MHz rectangular wave signal is recorded at an optimum recording current of each magnetic tape, and an output level of 10 MHz is detected by a spectrum analyzer. The relative speed between the magnetic tape and the head was 3.33 m / s. An 8 mm Hi8 tape manufactured by Sony Corporation was used as a reference (0 dB).

Then, recording and reproduction of this magnetic tape were evaluated on a video deck as follows. First, recording was performed for one minute on each magnetic tape, and the reproduction output thereof was measured. Thereafter, recording was performed for 20 minutes, the reproduction operation was repeated 10 times, and then the reproduction output was measured again to determine the output reduction (level reduction) based on the initial reproduction output. The results are shown in Tables 5 and 6.

[0099]

[Table 5]

[0100]

[Table 6]

From the results shown in Tables 5 and 6, the magnetic tapes of Experimental Examples 1 to 19 to which the ligand and the silane coupling agent were added showed that the magnetic tapes of Comparative Example 1 and Comparative Example 1 to which no ligand was added were used. It can be seen that the output decreases less than in Example 2. In addition, the magnetic tape of each of the experimental examples to which the ligand and the silane coupling agent were added had a higher initial output and a smaller decrease in output as compared with Comparative Example 3 in which the silane coupling agent was not added. Recognize. This indicates that the use of a combination of the silane coupling agent and the ligand suppresses generation of seizure on the magnetic head.

As can be seen from the results of Experimental Examples 1 and 19, the silane coupling agent only needs to be added to the magnetic layer before the ligand. It can be seen that the same effect can be obtained even if the silane coupling agent is added to the magnetic coating before the ligand, and the magnetic coating is adjusted by subjecting the ferromagnetic powder to a surface treatment in advance.

As shown in Tables 1 and 3, compounds having various functional groups were used as the ligands. However, there was no significant change in the characteristics. Did not.

Further, as a silane coupling agent,
Using those having various structures represented by Chemical formulas 14, slight differences were observed in the initial output and the output reduction value due to a slight difference in the adsorptivity to the ferromagnetic powder. No seizure was generated on the magnetic head by the combination.

However, in Experimental Example 2 in which the addition amount of the ligand was 0.1 part by weight, the effect of preventing image sticking was small. In Experimental Example 8 in which the addition amount of the silane coupling agent was 0.3 part by weight, the ligand was coordinated with the ferromagnetic powder.
It does not contribute much to the removal of burn-in of the magnetic head, and the output is reduced. Therefore, in order to improve the dispersibility of the ferromagnetic powder and suppress the generation of seizures, the addition amount of the ligand is 0.3 parts by weight or more, and the addition amount of the silane coupling agent is 0.5 parts by weight. It is understood that the number is preferably not less than parts.

In general, in each of the experimental examples, the larger the amount of the ligand added, the smaller the output decrease, and the larger the amount of the silane coupling agent, the larger the initial output. As can be seen from the results, if both are too large, the dispersibility of the ferromagnetic powder is reduced, and the initial output is reduced. From this, it can be seen that in order to maintain the dispersibility of the ferromagnetic powder, it is preferable that the addition amount of the ligand is 10 parts by weight or less and the addition amount of the silane coupling agent is 5 parts by weight or less.

From the above results, it can be seen that by using a combination of a ligand and a silane coupling agent, excellent electromagnetic conversion characteristics can be ensured and a decrease in output can be suppressed. Further, there is an appropriate range for the addition amount of the ligand and the silane coupling agent, and the addition amount of the ligand is 0.3 to 10 parts by weight based on 100 parts by weight of the ferromagnetic powder. It can be seen that the addition amount of the agent is more preferably 0.5 to 5 parts by weight based on 100 parts by weight of the ferromagnetic powder.

[0108]

As is apparent from the above description, according to the present invention, the magnetic layer contains a silane coupling agent and at least one of a bipyridine derivative and a phenanthrin derivative capable of forming a complex with a metal. By
The generation of burn-in on the magnetic head is suppressed.

Therefore, according to the present invention, even if the sliding time is increased or the scanning speed is increased in order to achieve long-term recording, a decrease in output due to spacing loss can be suppressed, and an increase in the error rate can be prevented. It is possible to provide a magnetic recording medium and a method of manufacturing the same that can prevent the occurrence of a magnetic recording medium.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Haruo Watanabe 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (14)

[Claims] 1. A magnetic recording medium comprising a non-magnetic support and a magnetic coating mainly composed of a ferromagnetic powder and a binder applied on a non-magnetic support to form a magnetic layer, wherein the magnetic layer comprises a silane coupling agent. A magnetic recording medium comprising at least one of a bipyridine derivative and a phenanthrin derivative. 2. The magnetic recording medium according to claim 1, wherein the silane coupling agent has at least one functional group selected from an amino group, an epoxy group, a vinyl group, and an isocyanate group. 3. The magnetic recording medium according to claim 1, wherein the bipyridine derivative is a compound represented by the following chemical formula 1. Embedded image 4. The magnetic recording medium according to claim 1, wherein the phenanthrin derivative is a compound represented by the following chemical formula 2. Embedded image 5. The magnetic recording medium according to claim 1, wherein the magnetic layer contains a silane coupling agent in a ratio of 0.5 to 5 parts by weight based on 100 parts by weight of the ferromagnetic powder. 6. The magnetic layer according to claim 1, wherein at least one of a bipyridine derivative and a phenanthrin derivative is made of a ferromagnetic powder.
2. The magnetic recording medium according to claim 1, wherein the content is 0.3 to 10 parts by weight based on parts by weight. 7. When preparing a magnetic paint mainly composed of a ferromagnetic powder and a binder, a silane coupling agent is added to the magnetic paint, and then at least one of a bipyridine derivative and a phenanthrin derivative is added. A method for manufacturing a magnetic recording medium. 8. The ferromagnetic powder is subjected to a surface treatment with a silane coupling agent in advance, and then the surface-treated ferromagnetic powder and a binder are kneaded together with at least one of a bipyridine derivative and a phenanthrin derivative. The method for manufacturing a magnetic recording medium according to claim 7, wherein the magnetic recording medium is dispersed. 9. The method according to claim 7, wherein the ferromagnetic powder, the binder, and the silane coupling agent are kneaded and dispersed, and thereafter, at least one of a bipyridine derivative and a phenanthrin derivative is added. A method for manufacturing a magnetic recording medium. 10. The magnetic recording medium according to claim 7, wherein a compound having at least one kind of functional group selected from an amino group, an epoxy group, a vinyl group, and an isocyanate group is used as the silane coupling agent. Manufacturing method. 11. A bipyridine derivative represented by the following formula 3:
8. A compound represented by the formula:
The manufacturing method of the magnetic recording medium according to the above. Embedded image 12. The method for producing a magnetic recording medium according to claim 7, wherein a compound represented by the following chemical formula 4 is used as the phenanthrin derivative. Embedded image 13. The magnetic recording medium according to claim 7, wherein the silane coupling agent is added to the magnetic layer at a ratio of 0.5 to 5 parts by weight based on 100 parts by weight of the ferromagnetic powder. Production method. 14. The magnetic layer according to claim 7, wherein at least one of a bipyridine derivative and a phenanthrin derivative is added to the magnetic layer in a ratio of 0.3 to 10 parts by weight based on 100 parts by weight of the ferromagnetic powder. A method for manufacturing a magnetic recording medium.