JPH08161729A - Magnetic recording medium - Google Patents

Abstract

PURPOSE: To obtain a magnetic recording medium which makes high density possible and achieves excellence in output characteristic and durability by setting the ratio between the content of an epoxy group of a magnetic paint and the content of sulfur at 1-2. CONSTITUTION: A non-magnetic layer 2 is provided on a support body 1 and a magnetic layer 3 thereon. A back coated layer 4 is provided on the rear of the support body 1 as required. The magnetic layer 3 is made up of a magnetic paint having a polymer containing an epoxy group and/or sulfur as binder. The ratio between the content of the epoxy group and the content of the sulfur (content of epoxy group/content of sulfur) is set at 1-20. Thus, a magnetic recording medium makes high density possible, especially achieving excellence in output characteristic and durability.

Description

Detailed Description of the Invention

[0001]

The present invention enables high density recording,
In particular, it relates to a magnetic recording medium having excellent output characteristics and durability.

[0002]

2. Description of the Related Art Conventionally, magnetic recording media have been widely used in the form of tapes, disks, drums or sheets. Such a magnetic recording medium is usually manufactured by coating a non-support such as a polyester film with a magnetic coating material containing magnetic powder and a binder as main components. In particular, in recent years, there has been a demand for miniaturization of magnetic recording media and high density recording,
In order to meet such demands, for example, attempts have been made to improve coercive force and saturation magnetization, and proposals have been made to reduce the thickness of the magnetic layer. In addition to the above requirements, there is a strong demand for a magnetic recording medium having particularly excellent output characteristics in order to meet the demand for a high-quality magnetic recording medium.

Further, conventionally, the magnetic layer in the magnetic recording medium has been formed of a magnetic paint containing polyisocyanate as a curing agent. The polyisocyanate is formed in the paint or by coating the magnetic paint. In the coating film, the reaction with the water present in the coating material or coating film atmosphere occurs preferentially, so that the function as the crosslinking agent was not sufficiently exhibited. Therefore, the conventional magnetic recording medium is
At present, the durability is not at a required level, and a magnetic recording medium having higher durability is desired.

Therefore, an object of the present invention is to provide a magnetic recording medium capable of high density recording, and particularly excellent in output characteristics and durability.

[0005]

As a result of various studies, the present inventors have found that a magnetic recording medium having a magnetic layer formed of a magnetic paint having a specific content ratio of epoxy groups and sulfur has the above-mentioned object. We have found that it can be achieved.

The present invention has been made based on the above findings, and comprises a support, at least a non-magnetic layer provided on the support, and a magnetic layer provided on the non-magnetic layer. The magnetic layer is formed by a magnetic paint having a polymer containing an epoxy group and / or sulfur as a binder, and the ratio of the epoxy group content to the sulfur content in the magnetic paint is The present invention provides a magnetic recording medium characterized in that [epoxy group content / sulfur content] is 1 to 20.

The magnetic recording medium of the present invention will be described in detail below. As shown in FIG. 1, the magnetic recording medium according to the present invention includes a support 1, a nonmagnetic layer 2 provided on the support 1, and a magnetic layer 3 provided on the nonmagnetic layer 2. The back coat layer 4 is provided on the back surface of the support 1 as necessary.

As the support 1, any known magnetic or non-magnetic support can be used without any particular limitation. Specifically, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyaramid, polycarbonate, polyamide can be used. Known resins and films such as polyimide, polyamide imide, polysulfone, aramid, and aromatic polyamide can be used. Further, the support may be previously subjected to corona discharge treatment, plasma treatment, easy adhesion treatment, heat treatment, dust removal treatment, and the like. The preferable thickness of the support is 1 to 300.
μm.

The non-magnetic layer provided on the support is a layer formed by applying a non-magnetic paint on the support. The non-magnetic coating material used when forming the non-magnetic layer is preferably a coating material composed of non-magnetic powder, a binder and a solvent, or a coating material composed of the binder and the solvent. The non-magnetic powder is not particularly limited as long as it is non-magnetic, but carbon black, graphite, titanium oxide, barium sulfate, zinc sulfide, magnesium carbonate, calcium carbonate, zinc oxide, calcium oxide, magnesium oxide, tungsten disulfide. , Molybdenum disulfide, boron nitride, tin dioxide, silicon dioxide, non-magnetic chromium oxide, alumina, silicon carbide, cerium oxide, corundum, artificial diamond, non-magnetic iron oxide, garnet, garnet, silica, silicon nitride, Molybdenum carbide,
Boron carbide, tungsten carbide, titanium carbide, diatomaceous earth, dolomite, resinous powder, and the like, among them,
Carbon black, titanium oxide, barium sulfate, calcium carbonate, alumina, non-magnetic iron oxide and the like are preferably used. The non-magnetic powder may be subjected to the surface treatment described above in order to improve the dispersibility of the non-magnetic powder.

When the non-magnetic layer contains non-magnetic powder, the particle size of the non-magnetic powder is preferably 0.001.
˜3 μm, more preferably 0.005 to 1 μm, and most preferably 0.005 to 0.5 μm. The non-magnetic powder is preferably contained in the non-magnetic layer formed by applying the non-magnetic coating material in an amount of 5 to 99% by weight, more preferably 30 to 95% by weight, and most preferably 50 to 95% by weight. It is desirable to incorporate it in the above non-magnetic paint so that it is contained by weight.

The binder may be a thermoplastic resin, a thermosetting resin, a reactive resin or the like, which may be used alone or as a mixture.
As the binder, specifically, vinyl chloride resin, polyester, polyurethane, nitrocellulose,
Epoxy resin and the like can be mentioned.
Resins and the like described in JP-A No. 162128, page 2, upper right column, line 19 to page 2, lower right column, line 19 and the like can be mentioned. Further, the binder may contain a polar group for improving dispersibility and the like. The amount of the binder used is preferably about 5 to 100 parts by weight, and particularly preferably 5 to 70 parts by weight, based on 100 parts by weight of the non-magnetic powder.

Examples of the solvent include ketone solvents, ester solvents, ether solvents, aromatic hydrocarbon solvents, chlorinated hydrocarbon solvents, and the like. The solvents described in JP-A-57-162128, page 3, lower right column, line 17 to page 4, lower left column, line 10 and the like can be used.

In addition, the non-magnetic coating material contains additives usually used in magnetic recording media such as a dispersant, a lubricant, an abrasive, an antistatic agent, a rust preventive, a mildew proofing agent, and a curing agent. , Can be added if necessary. As the above additives,
Specifically, it is described in JP-A-57-162128, page 2, upper left column, line 6 to page 2, upper right column, line 10 and page 3, upper left column, line 6 to third page upper right column, line 18 and the like. Various additives may be mentioned.

To prepare the above non-magnetic paint, for example,
The non-magnetic powder and the binder are charged together with a part of the solvent into a Nauter mixer or the like to be premixed to obtain a mixture, and the obtained mixture is kneaded by a continuous pressure kneader or the like, and then it is mixed with the solvent. Examples include a method of diluting a part of the mixture, carrying out a dispersion treatment using a sand mill or the like, mixing an additive such as a lubricant, filtering, and further mixing the remaining solvent and a curing agent.

The magnetic layer provided on the non-magnetic layer is a layer formed by applying a magnetic paint on the non-magnetic layer. The magnetic paint used for forming the magnetic layer is preferably a paint containing magnetic powder, a binder, and a solvent as main components.

Examples of the magnetic powder include ferromagnetic iron oxide, ferromagnetic chromium dioxide, and ferromagnetic metal powder.

The above-mentioned ferromagnetic iron oxide is FeOx (1.33).
A metal such as Cr, Mn, Co, or Ni added to ≦ x ≦ 1.5) can be used. Further, the ferromagnetic chromium dioxide is CrO ₂ or Na, K, F in the CrO _2.
Metals such as e and Mn, oxides of the metals, and nonmetal elements such as P may be used. Examples of the ferromagnetic metal powder include ferromagnetic metal powders having a metal content of 70% by weight or more, and 80% by weight or more of at least one type of ferromagnetic metal (eg, Fe, Co, Ni). . Specific examples of the ferromagnetic metal powder include, for example,
Fe-Co, Fe-Ni, Fe-Al, Fe-Ni-A
1, Co-Ni, Fe-Co-Ni, Fe-Ni-Al
-Zn, Fe-Al-Si, etc. are mentioned.

The magnetic powder may contain, if necessary,
A rare earth element or a transition metal element can be contained. In addition, as the magnetic powder, fine tabular barium ferrite and some of its Fe atoms are Ti, Co, Z.
Magnetic powders substituted with atoms such as n and V can also be used. The magnetic powder may be subjected to the above-mentioned surface treatment in order to improve the dispersibility of the magnetic powder.

The solvent used for the magnetic paint may be the same as the solvent used for the non-magnetic paint. The amount of the solvent used is preferably about 10 to 1200 parts by weight, more preferably 15 to 800 parts by weight, based on 100 parts by weight of the magnetic powder.

In the magnetic recording medium of the present invention, the magnetic coating material forming the magnetic layer has a polymer containing an epoxy group and / or sulfur as a binder. Examples of the polymer containing an epoxy group and / or sulfur include the following polymers.

That is, the epoxy group-containing polymer includes epoxy group-containing vinyl chloride copolymer, epoxy group-containing polyurethane, phenoxy resin, epoxy-modified polysiloxane and the like. As the polymer containing sulfur, a sulfonate metal group-containing polyurethane, a sulfate group-containing polyurethane, a sulfonate metal group-containing vinyl chloride copolymer,
Examples thereof include a vinyl chloride copolymer containing a sulfuric acid group and a polyester containing a metal sulfonate group. Examples of the polymer containing an epoxy group and sulfur include a vinyl chloride resin containing an epoxy group and a metal sulfonate group, and a polyurethane containing an epoxy group and a metal sulfonate group. The molecular weight of each of the above polymers is preferably 2000 to 300,000.

The amount of the above binder used is the same as that of the above magnetic powder 1.
It is preferably about 5 to 100 parts by weight, more preferably 5 to 70 parts by weight, based on 00 parts by weight.

Further, the ratio of the epoxy group content to the sulfur content in the above magnetic paint [epoxy group content / sulfur content,
That is, the content of the epoxy group contained in the magnetic layer / the content of sulfur contained in the magnetic layer] is 1 to 20, preferably 2 to 15. If the above content ratio is less than 1, there is a problem that dechlorination occurs during manufacture of the magnetic recording medium or during long-term storage of the magnetic recording medium, and durability is deteriorated. Properties deteriorate, and the durability of the magnetic recording medium deteriorates. Therefore, it is necessary to select one of the above polymers or to combine two or more of them so as to satisfy the above content ratio. If necessary, an epoxy group-containing compound such as phenoxy resin, "Epicoat 828", "Epicoat 834", "Epicoat 1007" (all are trade names, manufactured by Yuka Shell Co., Ltd.) is added to the magnetic coating material. Good. Further, in the coating film (magnetic layer) formed by the above magnetic paint, the epoxy group content is preferably 0.2 to 30 wt% and the sulfur content is preferably 0.05 to 5 wt%.

Further, the above-mentioned magnetic coating material may contain a generally known binder component other than the above-mentioned polymer, and the above-mentioned additives used in the above-mentioned non-magnetic coating material may be added thereto. Further, the above magnetic paint includes tertiary amines such as triethylenediamine and tetramethylhexamethylenediamine; "Kaolizer No. 30" and "Kaolizer N".
o. 1 ”[all are trade names, manufactured by Kao Corporation] and the like can be added as a curing agent. The amount of the curing agent added is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the binder.

To prepare the above magnetic paint, for example, the above magnetic powder and the above binder together with a part of the solvent are put into a Nauta mixer or the like and premixed to obtain a mixture, and the obtained mixture is continuously added. After kneading with a pressure kneader or the like, then diluting with a part of the solvent and dispersing treatment using a sand mill or the like, mixing additives such as a lubricant and filtering, and further curing agents such as polyisocyanate and the rest. And the like.

In the magnetic layer formed by applying the magnetic paint, the binder reacts to improve the durability of the magnetic layer.

In the magnetic recording medium according to the present invention, the dry thickness of the magnetic layer is preferably 0.05 to 1.5 μm.
m, more preferably 0.05 to 1.2 μm, most preferably 0.1 to 1 μm, and the dry thickness of the nonmagnetic layer is preferably 0.5 to 4 μm, more preferably 0.5.
.About.3.5 .mu.m, most preferably 0.5 to 3 .mu.m.

The magnetic recording medium according to the present invention is mainly used for data storage magnetic tapes, 8 mm video tapes and DAs.
It is suitable as a magnetic tape such as a T tape, but can also be used as another recording medium such as a floppy disk.

Next, an outline of the method for producing the magnetic recording medium of the present invention will be described. First, the non-magnetic coating and the magnetic coating are applied simultaneously on the support by a wet-on-wet method so that the dry thicknesses of the non-magnetic layer and the magnetic layer are the above-mentioned thickness, respectively, and the non-magnetic coating is applied. The coating film of the layer and the magnetic layer is formed. Next, the coating film is subjected to a magnetic field orientation treatment, followed by a drying treatment and winding. After this,
After performing a calendering treatment if necessary, a back coat layer is further formed if necessary. Then, if necessary, for example, when obtaining a magnetic tape, 40 to 70 ° C.
Aged for 6-72 hours underneath and slit to desired width.

The above-mentioned simultaneous multilayer coating method is disclosed in JP-A-5-73.
No. 42, line 31 to column 43, line 31, etc. of Japanese Patent No. 883, the above-mentioned magnetic coating material for forming the above-mentioned magnetic layer is applied before the above-mentioned non-magnetic coating material for forming the above-mentioned non-magnetic layer is dried. In this method, since the boundary surface between the non-magnetic layer and the magnetic layer is smooth and the surface property of the magnetic layer is good, dropout is small, high density recording is possible, and the coating film (magnetic layer Also, a magnetic recording medium having excellent durability of the (and non-magnetic layer) can be obtained.

The magnetic field orientation treatment is performed before the magnetic paint is dried. For example, when the magnetic recording medium of the present invention is a magnetic tape, the magnetic paint is applied in a direction parallel to the coated surface of the magnetic paint. About 500 Oe or more, preferably about 1000
It can be performed by a method of applying a magnetic field of 10,000 to 10,000 Oe, a method of passing a magnetic paint through a solenoid or the like of 1,000 to 10,000 Oe in a wet state.

The above drying treatment is carried out, for example, at 30 to 120 ° C.
The heating can be performed by supplying the gas heated to the above temperature. At this time, the drying degree of the coating film can be controlled by controlling the temperature of the gas and the supply amount thereof.

The calendering treatment can be carried out by a super calendering method in which two rolls such as a metal roll and a cotton roll or a synthetic resin roll, a metal roll and a metal roll are passed. Also,
The conditions for the calendar treatment are 60 to 140 ° C. and 100
It can be up to 500 kg / cm.

The backcoat layer, which is provided if necessary, is provided on the back surface of the support (the surface on which the nonmagnetic layer and the magnetic layer are not provided), and is usually the backcoat layer. It is obtained by applying the back coat paint used for the formation of the above onto the support. The back coat paint is obtained by appropriately selecting and mixing the non-magnetic powder, the binder, the dispersant, the lubricant, the curing agent, the solvent and the like described in detail in the non-magnetic paint. The back coat paint can be prepared by a generally known back coat paint manufacturing method.

When manufacturing the magnetic recording medium of the present invention, finishing steps such as polishing and cleaning of the surface of the magnetic layer may be carried out, if necessary. The non-magnetic coating material and the magnetic coating material can be applied by a generally known sequential multi-layer coating method.

[0036]

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<Example 1> [Preparation of magnetic paint, non-magnetic paint and back coat paint]
Of the formulations of the following paints, the components except polyisocyanate, fatty acid, and fatty acid ester are put into a Nauta mixer together with a part of the solvent and premixed to obtain a mixture, and the obtained mixture is continuously pressurized. Kneaded with a kneader. Then, after diluting each with a part of the solvent and dispersing with a sand mill, the fatty acid and the fatty acid ester are mixed and filtered, and the remaining solvent and polyisocyanate are further mixed to obtain a magnetic paint and a non-magnetic paint. And a back coat paint was obtained.

(Composition of magnetic paint) Ratio of content of epoxy group and sulfur = 5.7 Needle metal magnetic powder mainly composed of iron (coercive force 1860 Oe, saturation magnetization 137 emu / g, average major axis length) 0.1 μm) 100 parts by weight Alumina (average particle size 0.3 μm) 9 parts by weight Carbon black (average primary particle size 20 nm) 1 part by weight Vinyl chloride resin containing epoxy group and sulfonate metal base (metal sulfonate content) 0.9 wt%, epoxy group content 3 wt%) 9 parts by weight Metal sulfonate-containing polyurethane (metal sulfonate content 1 wt%) 7 parts by weight Stearic acid 1.5 parts by weight 2-ethylhexyl oleate 2 parts by weight Silane cup Ring agent [Toshiba Silicone Co., Ltd., trade name "TSL-8331"] 4 parts by weight Methyl ethyl ketone 100 parts by weight Toluene 5 0 parts by weight Cyclohexanone 100 parts by weight

(Composition of Non-Magnetic Paint) Needle-like α-iron oxide (average major axis length 0.07 μm) 90 parts by weight Carbon black (average primary particle size 0.023 μm) 7 parts by weight Alumina (average particle size 0.2 μm) ) 3 parts by weight Sulfonate metal base-containing vinyl chloride resin (metal sulfonate base content 0.6 wt%) 5 parts by weight Sulfonate metal base-containing polyurethane (GPC number average molecular weight 25000, sulfonate metal base content 1) .9 × 10 ⁻⁴ eq / g) 8 parts by weight Polyisocyanate [Nippon Polyurethane Industry Co., Ltd., trade name “Coronate HX”] 2 parts by weight Oleyl oleate 2 parts by weight Myristic acid 1 part by weight Methyl ethyl ketone 60 parts by weight Toluene 30 Parts by weight cyclohexanone 90 parts by weight

(Blending of back coat paint) Carbon black (average primary particle size 0.028 μm) 32 parts by weight Carbon black (average primary particle size 0.062 μm) 8 parts by weight “Nipporan 2301” [trade name, Nippon Polyurethane Industry ( Polyurethane manufactured by Co., Ltd.] 20 parts by weight nitrocellulose (viscosity display made by Hercules Powder Co. of 1/2 second) 20 parts by weight polyisocyanate (trade name “D-250N” manufactured by Takeda Pharmaceutical Co., Ltd.) 4 parts by weight Copper phthalocyanine 5 parts by weight Stearic acid 1 part by weight Methyl ethyl ketone 120 parts by weight Toluene 120 parts by weight Cyclohexanone 120 parts by weight

[Production of Magnetic Recording Medium] The dry thicknesses of the non-magnetic coating material and the magnetic coating material are 0.3 μm and 2.5 μm, respectively, on the surface of a polyethylene terephthalate support having a thickness of 9.8 μm. Like the wet
Simultaneous multi-layer coating was performed by an on-wet method to form coating films for the non-magnetic layer and the magnetic layer. Then, while the coating film was in a wet state, the coating film was passed through a solenoid of 5000 Oe for magnetic field orientation treatment, dried at 80 ° C., and then wound. Then, calendering was performed under the conditions of 85 ° C. and 350 kg / cm to form a non-magnetic layer and a magnetic layer, and then a back coat paint was applied on the back surface of the support so that the dry thickness was 0.5 μm. After drying at 90 ° C., it was wound up. Then, at 50 ℃, aging treatment for 16 hours, slit into 3.81mm width,
A magnetic tape having a width of 3.81 mm was obtained. For the obtained magnetic tape, output (4.7 MH) according to the following measuring method.
z) was measured. The results are shown in [Table 1]. Further, a continuous load scratch resistance test was performed according to the following test method to evaluate durability. The result is shown in FIG.

[Measurement Method] Output (4.7 MHz) The obtained 3.81 mm wide magnetic tape was loaded into a DAT cassette to obtain a DAT tape cassette for testing. The obtained DAT tape cassette for test is used as MediaLogic
Product name "Tape Evaluator Mode"
1 4500 "and put 4.7M on the above magnetic tape.
A Hz signal was recorded and the output (reproduction output) when the signal was reproduced was measured. The recording wavelength at 4.7 MHz is 0.6
It was 7 μm. The output value of the first embodiment is used as a reference (0d
B). [Test method] ◎ Continuous load scratch resistance test device shown in Fig. 2 [Continuous weight type surface texture measuring instrument, Type:
HELDON-22 (manufactured by HELDON)],
The test was conducted as follows. That is, after setting the sample on the sample table in the apparatus of FIG. 2 so that a load of 20 g is applied to the alumina ball, the scratch resistance when the sample table is moved at 150 mm / min in the direction of the arrow shown in FIG. Was detected.

Example 2 A magnetic tape obtained in the same manner as in Example 1 except that the magnetic layer and the non-magnetic layer were formed by using the magnetic coating material and the non-magnetic coating material having the following compositions, respectively, Evaluation was performed according to the method of 1. The results are shown in [Table 1] and FIG.

(Composition of magnetic paint) Ratio of content of epoxy group and sulfur = 7.7 Acicular metal magnetic powder mainly composed of iron (coercive force 1860 Oe, saturation magnetization 137 emu / g, average major axis length) 0.1 μm) 100 parts by weight Alumina (average particle size 0.3 μm) 9 parts by weight Carbon black (average primary particle size 20 nm) 1 part by weight Vinyl chloride resin containing epoxy group and sulfonate metal base (metal sulfonate content) 1.3%, epoxy group content 5.8 wt%) 11 parts by weight Epoxy group and sulfonic acid metal base containing polyurethane (sulfonic acid metal base content 2.9%, epoxy group content 2.4 wt%) 6 parts by weight Stearic acid 1.8 parts by weight 2-ethylhexyl oleate 2.1 parts by weight Methyltetrahydrophthalic anhydride, "QH200" [Nippon Zeon Co., Ltd., trade name 4 parts by weight of triethylenediamine, "Kaoraiza No.30" [manufactured by Kao Corporation, trade name] 4 parts by weight Methyl ethyl ketone 100 parts Toluene 50 parts by weight Cyclohexanone 100 parts by weight

(Blending of Non-Magnetic Paint) The needle-shaped α-iron oxide 90 parts by weight The carbon black 7 parts by weight The alumina 3 parts by weight The sulfonic acid group-containing vinyl chloride resin 8 parts by weight The sulfonic acid group-containing polyurethane 5 Parts by weight Polyisocyanate [Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"] 3 parts by weight oleyl oleate 1 part by weight myristic acid 1 part by weight methyl ethyl ketone 60 parts by weight toluene 30 parts by weight cyclohexanone 90 parts by weight

Comparative Example 1 The vinyl chloride resin containing sulfonic acid in the magnetic paint was replaced with a vinyl chloride-vinyl acetate copolymer (trade name "VAGH" manufactured by Union Carbide Co.) (epoxy group in magnetic paint). And sulfur content ratio =
A magnetic tape was manufactured in the same manner as in Example 1 except for 0), and this magnetic tape was evaluated according to the method of Example 1. The results are shown in [Table 1] and FIG.

<Comparative Example 2> A magnetic tape was produced in the same manner as in Example 1 except that the magnetic layer was formed of a magnetic coating material having the following composition, and this magnetic tape was evaluated according to the method of Example 1. . The results are shown in [Table 1] and FIG.

(Composition of magnetic paint): ratio of content of epoxy group to sulfur = 21 Needle-like metal magnetic powder mainly composed of iron (coercive force 1860 Oe, saturation magnetization 137 emu / g, average major axis length 0. 1 μm) 100 parts by weight Alumina (average particle size 0.3 μm) 9 parts by weight Carbon black (average primary particle size 20 nm) 1 part by weight Vinyl chloride resin containing epoxy groups and sulfonic acid groups (sulfonic acid group content 1.3% , Epoxy group content 6.5 wt%) 6 parts by weight Metal sulfonate-containing polyurethane (metal sulfonate content 1 wt%) 1.5 parts by weight Stearic acid 1.5 parts by weight 2-Ethylhexyl oleate 2 parts by weight Silane cup Ring agent [Toshiba Silicone Co., Ltd., trade name "TSL-8331"] 4 parts by weight Methyl ethyl ketone 100 parts by weight Toluene 50 parts by weight Cyclohexanone 100 parts by weight of the epoxy resin [Yuka Shell Co., Ltd., trade name "Epikote 1010", epoxy equivalent 3500] 20 parts by weight

[0049]

[Table 1]

[0050]

INDUSTRIAL APPLICABILITY The magnetic recording medium of the present invention is capable of high density and is particularly excellent in output characteristics and durability.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of a magnetic recording medium according to the present invention.

FIG. 2 is a schematic perspective view showing a measuring device for a continuous load scratch resistance test.

FIG. 3 is a graph showing the measurement results of a continuous load scratch resistance test.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a support, at least a non-magnetic layer provided on the support, and a magnetic layer provided on the non-magnetic layer, wherein the magnetic layer is Formed by a magnetic paint having a polymer containing an epoxy group and / or sulfur as a binder, and the ratio [epoxy group content / sulfur content] of the epoxy group content and the sulfur content in the magnetic paint is 1 to 20. A magnetic recording medium characterized by: