JPH08235576A - Magnetic recording medium - Google Patents

Abstract

PURPOSE: To provide a magnetic recording medium having a magnetic layer having good durability while keeping good electromagnetic conversion characteristics by adding a higher fatty acid ester of a specified component to a magnetic coating material to form the magnetic layer. CONSTITUTION: The magnetic coating material to form a magnetic layer 2 on a nonmagnetic supporting body 1 contains an ester compd. of higher fatty acid expressed by formula having aliphatic hydrocarbon groups R1 , R2 , R3 of the β position of alcohol. In formula, R1 , R2 , R3 are 1-5C aliphatic hydrocarbon groups and R4 is 14-22C aliphatic hydrocarbon group. By this method, the interaction between hydrogen atoms on the carbon at the β position and the oxygen atoms in carbonyl groups can be prevented, the electron density of oxygen atoms in carbonyl groups is increased, the interaction among molecule is increased, and thereby, the degree of freedom is decreased. This results in a strong oil film. Therefore, the magnetic layer can be sufficiently protected and the obtd. magnetic recording medium has excellent durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic tape, and more particularly, it has a magnetic layer formed by applying a magnetic coating material containing a ferromagnetic powder and a binder on a non-magnetic support. The present invention relates to a coating type magnetic recording medium.

[0002]

2. Description of the Related Art In magnetic recording media for audio and video use, a magnetic paint prepared by dispersing and kneading ferromagnetic powder, binder, dispersant, lubricant, etc. in an organic solvent is used as a non-magnetic material such as polyester film. A coating type magnetic recording medium in which a magnetic layer is formed by coating on a support is widely used.

In such a coating type magnetic recording medium, the ferromagnetic powder is being miniaturized in order to achieve high performance in response to high density recording, and a ferromagnetic powder having a large specific surface area is used. Is starting to appear. In addition, as the ferromagnetic powder, metals having excellent magnetic properties, such as Fe, Ni,
Ultra fine particles of Co or the like or alloys thereof have been used.

By the way, in a coating type high density recording medium, ferromagnetic powder having an extremely fine particle size is highly dispersed in a binder resin to improve the surface property of the magnetic layer to improve electromagnetic conversion characteristics. At the same time, it is required to improve the durability of the magnetic coating film.

That is, in the coating type magnetic recording medium, how well the ferromagnetic powder contained in the magnetic layer is dispersed and how well it is combined with the binder are extremely important problems. Moreover, it must have excellent durability while maintaining the obtained electromagnetic conversion characteristics.

Therefore, in order to meet such demands, addition of a dispersant such as lecithin into a magnetic coating material, introduction of a polar group into a binder, selection of a lubricant and the like have been conventionally performed.

However, when trying to disperse a fine ferromagnetic powder having a specific surface area of 45 m ² / g or more in a magnetic paint, the cohesive force of such a ferromagnetic powder is large, and therefore the addition of the above-mentioned dispersant or In reality, it is difficult to ensure sufficient dispersibility only by introducing a polar group into the binder.

When a dispersant such as lecithin is used, the reinforcing effect at the interface is insufficient due to the poor affinity between the dispersant and the binder, and the coating strength, that is, the durability tends to deteriorate. is there. Furthermore, in order to obtain sufficient durability using conventional fatty acids, fatty acid esters, etc., it is necessary to add a large amount of these, and as a result, there is a concern that the durability of the coating film may deteriorate due to plasticization.

[0009]

DISCLOSURE OF THE INVENTION The present invention makes it possible to improve the dispersibility of a coating type magnetic recording medium even if a fine ferromagnetic powder having a specific surface area of 45 m ² / g or more is used, thereby improving the electromagnetic properties of the magnetic coating film. Provided is a magnetic recording medium having excellent conversion characteristics and sufficient durability.

The higher fatty acid ester conventionally used as a lubricant has a hydrogen atom at the β-position carbon in the alcohol portion thereof. Since the hydrogen atom has an interaction with the oxygen atom of the carbonyl group on the carbon at the β-position, the electron density of the oxygen atom of the carbonyl group is small, and the interaction between molecules is small. As a result, it was found that the degree of freedom of the molecule is large, a strong oil film is hard to form, and sufficient durability cannot be obtained. In the present invention, the magnetic recording medium having sufficiently high durability is dealt with this. I came to find out.

[0011]

A magnetic recording medium according to the present invention has a β of an alcohol moiety represented by the following general formula (Formula 2).
It has a magnetic layer formed by applying a magnetic coating material in which an esterified product of a higher fatty acid having aliphatic hydrocarbon groups R ₁ , R ₂ , and R ₃ on the carbon at the position is added.

[Chemical 2]Where R₁, R₂ , R₃Is a C1-C5 fat
Is a group hydrocarbon group, R _FourIs an aliphatic having 14 to 22 carbon atoms
It is a hydrocarbon group.

[0012]

According to the above-mentioned constitution of the present invention, the higher fatty acid ester compound is added to the magnetic paint. As the higher fatty acid ester, a compound according to the above (Chemical formula 2) (hereinafter referred to as compound A), that is, its compound The structure in which a hydrogen atom was present at the β-position carbon of the alcohol portion was avoided, and an aliphatic hydrocarbon group was bonded to this part. For this reason, the interaction between the hydrogen atom on the carbon at the β-position and the oxygen atom of the carbonyl group is avoided, the electron density of the oxygen atom of the carbonyl group becomes large, and the interaction between molecules becomes large. The degree of freedom is reduced and a strong oil film is formed. Therefore, according to the present invention, a magnetic recording medium which can sufficiently protect the magnetic layer and has excellent durability is constructed.

[0013]

EXAMPLES The present invention is based on the fact that the specific surface area of the magnetic powder contained in the magnetic paint is 45 m ² / g or more, and the binder resin is 15 to 25 parts by weight when the specific surface area is 100 parts by weight, and 1 to 5 parts by weight of a compound having a plurality of carboxyl groups (hereinafter referred to as compound B) is added to 100 parts by weight of the powder, and an aliphatic hydrocarbon group R ₁ , R ₂ , on the carbon at the β-position of the alcohol portion. A magnetic coating material containing an esterified compound of a higher fatty acid (compound A) in which R ₃ is present is applied onto a non-magnetic support 1 to form a magnetic layer 2, as shown in the schematic sectional view of FIG. The configuration.

The compound A is based on the above (formula 2). Here, R ₁ , R ₂ and R ₃ are each a linear or side chain aliphatic hydrocarbon group having 1 to 5 carbon atoms and may be the same or different from each other. R ₄ is oxygen number 14 to 22
Is a linear or side chain aliphatic hydrocarbon group. These may be saturated or unsaturated hydrocarbon groups.

The compound A will be specifically described. Esterified products of neopentyl alcohol and saturated fatty acids such as palmitic acid and stearic acid, esterified products of neopentyl alcohol and unsaturated fatty acids such as oleic acid, or
Examples thereof include compounds such as esterified products of neopentyl alcohol and side chain fatty acids such as isostearic acid.

Further, by specifying the addition amount of the compound A to the magnetic paint to 1 to 5 parts by weight with respect to 100 parts by weight of the magnetic powder, it is possible to obtain sufficient durability and electromagnetic conversion characteristics of the magnetic coating film. it can. However, if the addition amount is less than 1 part by weight or does not exist, sufficient durability cannot be obtained.
If the amount added is more than 5 parts by weight, the coating film is plasticized and the durability is deteriorated.

In using the compound A, the magnetic layer formed by applying the magnetic coating must have a certain pore volume. It has a specific surface area of 45
When a magnetic powder of less than m ² / g is used, good durability is exhibited, but when a magnetic powder having a specific surface area of 45 m ² / g or more is used, the pore volume decreases and the surface of the magnetic layer is sufficiently reduced. There is no suitable lubricant. In such a case, the friction of the magnetic recording medium is increased, and powder is removed due to abrasion, so that sufficient durability cannot be obtained. Therefore, in this case, it may be difficult to obtain a magnetic recording medium having good electromagnetic conversion characteristics and sufficient durability.

Therefore, in the present invention, in order to sufficiently exert the excellent lubricating effect of the compound A and to satisfy the durability, the binder resin when the magnetic powder contained in the magnetic coating material is 100 parts by weight. Sufficient pore volume is obtained in the magnetic coating film by adding 15 to 25 parts by weight. On the other hand, if the addition amount is less than 15 parts by weight, sufficient mechanical strength cannot be obtained and durability deteriorates, and if it is more than 25 parts by weight, sufficient pore volume cannot be obtained.

To further improve the dispersibility, 1 to 5 parts by weight of the compound B having a plurality of carboxyl groups having a good affinity for the magnetic powder as a dispersant is added to 100 parts by weight of the magnetic powder in the magnetic coating material. However, if the amount added is more than 5 parts by weight, the electromagnetic conversion characteristics deteriorate and the durability also deteriorates. If the amount of the compound B is less than 1 part by weight or does not exist, the electromagnetic conversion characteristics deteriorate and sufficient durability cannot be obtained.

Examples of the compound B include dicarboxylic acid having two cargixyl groups in the molecule, tricarboxylic acid having three carboxyl groups in the molecule, and 4 in the molecule.
Tetracarboxylic acid having one carboxyl group can be used.

Specific examples of the compound B include, for example, dicarboxylic acids such as oxalic acid, malonic acid, succinic acid,
Saturated aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like, unsaturated aliphatic dicarboxylic acids such as maleic acid and fumaric acid,
Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. Examples of tricarboxylic acids include citric acid, nitrilotriacetic acid, and benzenetricarboxylic acid, and examples of tetracarboxylic acids include benzenetetracarboxylic acid.

The compound B has a weight average molecular weight of 1
It is preferably 000 or less. If the molecular weight exceeds 1,000, it is necessary to add a large amount in terms of quantity, which may adversely affect the physical properties of the magnetic coating film.

According to the above-mentioned constitution, since the compounds A and B are added in combination within a specific addition amount range, even if a fine magnetic powder having a specific surface area of 45 m ² / g or more is used, The dispersibility and the durability of the coating film can be realized. Therefore, it is possible to provide a magnetic recording medium having an electromagnetic conversion characteristic suitable for high density recording. On the other hand, when the magnetic powder having a specific surface area of less than 45 m ² / g was used, good durability was obtained, but the electromagnetic conversion characteristics were deteriorated regardless of the presence or absence of a plurality of carboxyl groups.

As the magnetic powder used in the present invention, any of conventionally known oxide magnetic powder and metal magnetic powder can be used.

The oxide magnetic powder is, for example, γ-Fe.
₂O₃, Co-containing γ-Fe₂O₃, Fe₃O_Four, Co included
With Fe₃O_Four, Co deposition γ-Fe₂O₃, Co deposited Fe
₃O _Four, CrO₂Etc.

Examples of the magnetic metal powder include Fe and C
o, Ni, Fe-Co, Fe-Ni, Fe-Co-N
i, Fe-Co-B, Fe-Co-V, Fe-Co-C
r-B, Mn-Al, Mn-Bi, Co-Ni, etc. are mentioned, and A for the purpose of improving various characteristics of these.
A metal component such as 1, Si, Ti, Cr, Mn, Cu or Zn may be added. Also, hexagonal ferrite such as barium ferrite, iron carbide such as Fe ₅ C ₂ and iron nitride can be used.

The magnetic layer is prepared by dispersing the above-mentioned magnetic powder in a binder. As a usable binder, any resin material usually used in this type of medium can be used. However, the type is not particularly limited. Typical binder resins are, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer. Polymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-
Vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, thermoplastic polyurethane resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile -Butadiene-methacrylic acid copolymer, polyvinyl butyral, polyvinyl acetal, cellulose derivative, styrene-butadiene copolymer, polyester resin, phenol resin, phenoxy resin, epoxy resin, thermosetting polyurethane resin, urea resin, melamine resin, alkyd Resin, urea-formaldehyde resin, and the like.

Such a binder has, at least in part, a sulfonic acid metal base (--SO ₃ M; M represents an alkali metal such as Na or K) or a sulfate metal base (--OSO).
₃ M; M represents an alkali metal such as Na or K or an alkyl group). The amount of these metal bases is preferably 0.2 to 0.8 μmol per 1 m ² of the surface area of the magnetic powder.

Further, in the magnetic recording medium of the present invention, if necessary, a dispersant such as lecithin, an antistatic agent such as carbon black, an abrasive such as alumina, a rust preventive and the like may be added. As the dispersant, the antistatic agent, the abrasive, and the rust preventive, any conventionally known material can be used, and the dispersant, the antistatic agent, and the rust preventive are not limited at all.

Further, the non-magnetic support 1 in the magnetic recording medium according to the present invention can be composed of polyesters such as polyethylene terephthalate, polyethylene-2,6-naphthalate film, aramid film and the like. An intermediate layer or an underlayer can be provided on the surface of the non-magnetic support in order to improve the adhesiveness of the magnetic layer.

In order to form a magnetic layer on these non-magnetic supports, the above-mentioned components of the magnetic layer are dispersed in a binder and ethers, esters,
A magnetic paint is prepared by dispersing it with an organic solvent selected from ketones, aromatic hydrocarbons, aliphatic hydrocarbons, organic chlorine compound-based solvents, etc., and this paint is applied to the surface of a non-magnetic support, dried, and calendered. To process.

As shown in FIG. 1, the non-magnetic support 1
A back coat layer 3 can be deposited on the surface opposite to the side on which the upper magnetic layer 2 is formed for the purpose of improving the running property of the magnetic recording medium, preventing charging and preventing transfer. The back coat layer 3 in this case can also have a conventionally known composition, and the binder used can basically be the binder used in the magnetic layer 2 described above, and a known binder such as carbon black can be used. The above non-magnetic material and various additive components for the back coat layer may be contained.

Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 A magnetic paint having the following composition was prepared. [Magnetic coating composition] Magnetic powder: Fe-based metal magnetic powder (specific surface area BET value: see Table 1 below) 100 parts by weight Binder: Polyester polyurethane resin (see Table 2 below) 10 parts by weight Vinyl chloride-based co-weight Combined (see Table 2 below) 10 parts by weight Abrasive: Alumina (Al ₂ O ₃ ) 8 parts by weight “AKP50” manufactured by Sumitomo Chemical Co., Ltd. Compound B: compound having a plurality of carboxyl groups (see Table 4 below) 3 parts by weight Parts Lubricants: stearic acid 2 parts by weight Solvents: methyl ethyl ketone / toluene / synchrohexane 100/100/50 parts by weight

To the magnetic coating material having the above composition, 3 parts by weight of Compound A (see Table 3 below) as a lubricant was added and dispersed by a sand mill, and then a curing agent "Coronate L" manufactured by Nippon Polyurethane Co., Ltd. was added to 20 parts. After adding a part by weight and stirring, this was applied onto a base film (nonmagnetic support) having a thickness of 7.5 μm. After that, a magnetic field orientation treatment was performed, dried and wound. Further, it was calendered and cured.
On the other hand, a back coat layer coating material having the following composition was prepared. [Coating composition for back coat layer] Carbon black: "Asahi Carbon 50" manufactured by Asahi Carbon Co., Ltd. 100 parts by weight Binder: Polyester polyurethane resin "Nipporan N2304" manufactured by Nippon Polyurethane Co., Ltd. 30 parts by weight Phenoxy resin U. C. C. "PKHH" 70 parts by weight Solvent: Methyl ethyl ketone 500 parts by weight Toluene 500 parts by weight To the coating material for the back coat layer having the above composition, 20 parts by weight of the curing agent "Coronate L" is added, and the magnetic layer of the base film is added. It was applied to the back surface opposite to the above, and a back coat layer having a thickness of 0.6 μm was formed on the back surface.

Total thickness thus obtained 10.5-1
8m wide slit 0.7mm wide tape
It was incorporated into the m cassette. A cassette tape formed of the magnetic recording medium according to the first embodiment will be referred to as sample 1.

Examples 2 to 7 The same procedure as in Example 1 was carried out except for the addition amount of the compound A, the addition amount of the compound B, and the addition amount of the binder used. Samples 2 to 7 are cassette tapes made of the magnetic recording media produced in Examples 2 to 7, respectively.

Examples 8 to 12 The same procedure as in Example 1 was carried out except for the type of compound A and the type of magnetic powder used. Samples 8 to 12 are cassette tapes made of the magnetic recording media produced in Examples 8 to 12, respectively.

Examples 13 and 14 Same as Example 1 except that the kinds of the compound A were A ₁ and A ₂ (see Table 3 below). Examples 13 and 1
Samples 13 and 14 are cassette tapes made of the magnetic recording media produced in Example 4 respectively.

Comparative Example 1 Example 1 was repeated except that the amount of the compound A added was 0.5 parts by weight with respect to Examples 1, 2 and 3. The cassette tape made of the magnetic recording medium manufactured in Comparative Example 1 is referred to as Sample 15.

Comparative Example 2 The procedure of Example 1 was repeated, except that the amount of the compound A added was 10 parts by weight with respect to Examples 1, 2 and 3. This comparative example 2
A sample 16 is a cassette tape made of the magnetic recording medium manufactured by.

Comparative Example 3 The procedure of Example 1 was repeated except that the amount of the binder added was 10 parts by weight with respect to Examples 1, 4, and 5. Sample 17 is a cassette tape made of the magnetic recording medium manufactured in Comparative Example 3.

Comparative Example 4 The procedure of Example 1 was repeated, except that the amount of the binder added was 30 parts by weight with respect to Examples 1, 4, and 5. A cassette tape made of the magnetic recording medium manufactured in Comparative Example 4 is referred to as Sample 18.

Comparative Examples 5 and 6 The same as Example 1 except that the addition amount of the compound B was 0 or 0.5 parts by weight with respect to Examples 1, 6 and 7. Samples 19 and 20 are cassette tapes made of the magnetic recording media produced in Comparative Examples 5 and 6.

Comparative Example 7 The procedure of Example 1 was repeated except that the amount of compound B added was 10 parts by weight with respect to Examples 1, 6 and 7. This Comparative Example 7
Sample 21 is a cassette tape made of the magnetic recording medium manufactured by.

Comparative Example 8 The same as Example 1 except that the specific surface area of the magnetic powder was smaller than those of Examples 1, 10, 11, and 12. The cassette tape made of the magnetic recording medium manufactured in Comparative Example 8 is referred to as Sample 22.

Comparative Example 9 Example 1 was repeated except that butyl stearate (BS) was added instead of the compound A to Examples 1, 13 and 14. The cassette tape made of the magnetic recording medium manufactured in Comparative Example 9 is referred to as Sample 23.

Samples 1 to 23 produced as described above
The still characteristics and electromagnetic conversion characteristics of were evaluated by the following methods.

Still characteristics: An 8 mm video deck modified to measure still for a long time was used, and the temperature was kept at 45 ° C. for 8 hours.
The time until the RF reproduction output was attenuated by 3 dB from the initial output was measured under the environment of 0% RH (relative humidity). Electromagnetic conversion characteristics: 25 ° C, 60% R using an 8mm VCR capable of recording / reproducing in Hiight (Hi8) mode
A signal of 7 MHz was input to the tape for 10 minutes under the environment of H, and the difference between the output at 7 MHz and the noise of -1 MHz was calculated as S / N. The value obtained for the sample 1 of Example 1 was set to 0 dB, and the values of the other samples were shown as relative values.

Tables 5 and 6 below show Examples 1 to 14 and
For each sample according to Comparative Examples 1 to 9, the specific surface areas of the magnetic powders used are shown by the symbols shown in Table 1, the compounds A and B are shown by the symbols shown in Tables 3 and 4, and the binder Along with the amount of addition, the measurement results of still time [minutes] and S / N [dB] based on the method described above are shown for each sample.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

[0055]

[Table 5]

[0056]

[Table 6]

The amounts added in Tables 5 and 6 are as follows.
The parts by weight when the magnetic powder is 100 parts by weight are shown.

As apparent from Tables 5 and 6, according to the present invention, magnetic powder having a specific surface area of 45 m ² / g or more was used.
25 parts by weight, 1 to 5 parts by weight of compound B having a plurality of carboxyl groups, and compound A
₁ to 5 parts by weight of (esterification product of higher fatty acid in which aliphatic hydrocarbon groups R ₁ , R ₂ and R ₃ are present on the β-position carbon of the alcohol moiety as shown in the general formula of (Chemical Formula 2)) The magnetic recording medium obtained by applying the magnetic coating composition described above onto the non-magnetic support 1 can maintain the electromagnetic conversion characteristics and obtain good still characteristics.

Further, from Samples 1, 4, and 5, it is suitable that the amount of the binder resin added is 15 to 25 parts by weight when the magnetic powder contained in the magnetic coating material is 100 parts by weight. On the other hand, in Sample 17, the addition amount is less than 15 parts by weight,
Insufficient mechanical strength was not obtained and durability was poor.
In addition, the addition amount was more than 25 parts by weight, a sufficient pore volume was not obtained, and the compound A was not sufficiently present on the medium surface, resulting in poor durability.

The amount of compound A added was 1 to 3 from Samples 1 to 3.
~ 15 parts by weight is suitable, less sample 15
Does not have sufficient durability, and more than 16
Has poor durability due to the plasticity of the coating film. Further, in the case of the sample 23 using a conventional higher fatty acid ester such as butyl stearate, sufficient durability cannot be obtained.

For the compound B having a plurality of carboxyl groups, 1 to 5 parts by weight from Samples 1, 6, and 7 are suitable, and Samples 8 and 9 are also suitable for other compounds having the same structure. The results were obtained. However, sample 2
When the addition amount of 1 is more than 10 parts by weight, electromagnetic conversion characteristics are deteriorated and durability is deteriorated. Samples 19 and 20
Does not exist or is small, the electromagnetic conversion characteristics deteriorate, and sufficient durability cannot be obtained.

As in Samples 1, 10, 11, and 12, it is important to use magnetic powder having a specific surface area of 45 m ² / g or more in order to obtain good electromagnetic conversion characteristics. However, sample 22
As described above, when the magnetic powder having a specific surface area of less than 45 m ² / g was used, good durability was obtained, but the electromagnetic conversion characteristics were deteriorated regardless of the presence or absence of the compound B having a plurality of arboxyl groups.

[0063]

As described above, the magnetic recording medium according to the present invention maintains good electromagnetic conversion characteristics while maintaining good electromagnetic conversion characteristics even when using fine magnetic powder having a specific surface area of 45 m ² / g or more. It is possible to provide a magnetic recording medium having a magnetic layer that also has durability.

In particular, the amount of the binder resin added is 15 to 25 parts by weight, and the compound having a plurality of silboxyl groups is 1
˜5 parts by weight, and ₁ to 5 parts by weight of an esterified product of a higher fatty acid having aliphatic hydrocarbon groups R ₁ , R ₂ and R ₃ on the β-position carbon of the alcohol moiety. By applying the coating material onto the non-magnetic substrate, it is possible to provide a magnetic recording medium having a magnetic layer that surely maintains good electromagnetic conversion characteristics and also has good durability.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of a magnetic recording medium according to the present invention.

[Explanation of symbols]

 1 non-magnetic support 2 magnetic layer 3 back coat layer

Claims (8)

[Claims] 1. An alcohol represented by the following general formula (formula 1):
Aliphatic hydrocarbon group R on the β-position carbon₁, R₂, R
₃With higher fatty acid ester compound
Characterized by having a magnetic layer formed by applying a conductive paint
Magnetic recording media. [Chemical 1]Where R₁, R₂ , R₃Is a C1-C5 fat
Is a group hydrocarbon group, R _FourIs an aliphatic having 14 to 22 carbon atoms
It is a hydrocarbon group. 2. The esterified product of the higher fatty acid is used in an amount of 1 per 100 parts by weight of the magnetic powder contained in the magnetic paint.
The magnetic recording medium according to claim 1, wherein the magnetic recording medium is added in an amount of 5 to 5 parts by weight. 3. The specific surface area of the magnetic powder in the magnetic paint is 45 m ² / g or more, and when 100 parts by weight of the magnetic powder is contained in the magnetic paint, the binder resin becomes 15 to 25 parts by weight. The magnetic recording medium according to claim 1. 4. The specific surface area of the magnetic powder in the magnetic paint is 45 m ² / g or more, and when 100 parts by weight of the magnetic powder is contained in the magnetic paint, the binder resin becomes 15 to 25 parts by weight. The magnetic recording medium according to claim 2. 5. The magnetic coating composition containing 1 to 5 compounds having a plurality of carboxyl groups per 100 parts by weight of magnetic powder.
The magnetic recording medium according to claim 1, which is added by weight. 6. A compound having a plurality of carboxyl groups in an amount of 1 to 5 with respect to 100 parts by weight of magnetic powder in the magnetic paint.
The magnetic recording medium according to claim 2, which is added by weight. 7. 1 to 5 compounds containing a plurality of carboxyl groups per 100 parts by weight of magnetic powder are added to the magnetic paint.
The magnetic recording medium according to claim 3, which is added by weight. 8. The magnetic coating composition containing 1 to 5 compounds having a plurality of carboxyl groups per 100 parts by weight of magnetic powder.
The magnetic recording medium according to claim 4, which is added by weight.