JPH06301965A - Magnetic recording medium - Google Patents

Abstract

(57) [Summary] [Structure] A magnetic powder is surface-treated with a polycarboxylic acid having two or more carboxyl groups, and cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4 is contained in the magnetic layer. A magnetic recording medium containing a compound such as cyclohexanedicarboxylic acid or a magnetic powder surface-treated with a polycarboxylic acid having two or more carboxyl groups, and cis-1,2 on the magnetic layer. A magnetic recording medium, characterized in that a compound such as cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid is applied. [Effect] The magnetic recording medium of the present invention is a magnetic powder in which the surface of the magnetic powder is acidic, and the presence of a compound such as cyclohexanedicarboxylic acid on the surface of the magnetic layer makes Corrosion is suppressed, and even if the magnetic head is run in an environment of high temperature and low humidity, burn-in of the magnetic head is suppressed, and the error rate does not increase.

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, for example, a backup data cartridge for computer (helical scan system) (DDS, data 8 mm, etc.).
The present invention relates to a magnetic recording medium suitable for use in a VTR video tape.

[0002]

2. Description of the Related Art Conventionally, in a so-called coating type magnetic recording medium, a magnetic paint prepared by dispersing and kneading a ferromagnetic powder, a binder, a dispersant, a lubricant and the like in an organic solvent is supported by a non-magnetic support such as a polyester film. The magnetic layer is formed by applying it on the body.

In the helical scan method, the surface of the magnetic layer and the magnetic head slide at high speed, so that the surface of the magnetic head becomes hot when the magnetic tape is running. If the material of the head is an alloy (Sendust, Permalloy, etc.), the Corrosion is likely to occur.

Particularly, in an environment such as high temperature and low humidity or low humidity, the polishing power of the magnetic tape is reduced, and the oxides produced by corrosion are markedly burned on the head surface, resulting in a gap between the tape and the head. (Spacing) will occur. In this case, a predetermined signal output cannot be obtained, which leads to an increase in error rate, especially in a data cartridge, which is a fatal phenomenon.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to suppress corrosion of the surface of a magnetic head during high-speed sliding and to prevent an increase in error rate even when the magnetic recording medium is run in an environment of high temperature and low humidity or low humidity. To provide.

[0006]

That is, the invention according to claim 1 is a magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support.
The magnetic powder is surface-treated with an acid, cyclohexanedicarboxylic acid, trans-cinnamic acid, 2,3-naphthalenediol, 1,2-naphthalenediol,
At least one compound (one or more compounds) selected from the group consisting of 1,8-naphthalenediol and 1,5-naphthalenediol (hereinafter referred to as "compound such as cyclohexanedicarboxylic acid", or simply " The compound may be referred to as "compound" in some cases.) Is contained in the magnetic layer.

According to a second aspect of the invention, in a magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support, the magnetic powder is surface-treated with an acid. , Cyclohexanedicarboxylic acid, trans-cinnamic acid, 2,3-naphthalenediol,
At least one (one or more) compound selected from the group consisting of 1,2-naphthalenediol, 1,8-naphthalenediol, and 1,5-naphthalenediol is coated on the magnetic layer. The present invention relates to a magnetic recording medium characterized by being attached.

According to a third aspect of the present invention, the acid is a polyvalent carboxylic acid having two or more carboxyl groups, and cyclohexanedicarboxylic acid among the compounds is cis-
1,2-cyclohexanedicarboxylic acid and / or cis-
1,4-cyclohexanedicarboxylic acid.
Alternatively, the present invention relates to the magnetic recording medium described in 2.

According to a fourth aspect of the invention, the content of the compound such as cyclohexanedicarboxylic acid in the magnetic layer of the first aspect is 0.15 to 5 parts by weight per 100 parts by weight of the magnetic powder (particularly 0.3 in the case of naphthalenediol). to 3 parts by weight, of which 0.15 to 3 parts by weight with 1,5-naphthalene diol), and claims the coating amount of the compound, such as 2 cyclohexane dicarboxylic acid to the magnetic layer is 5 to 100 mg / m ² ( Especially 1,
The magnetic recording medium according to any one of claims 1 to 3, wherein the content of 5-naphthalenediol is 5 to 100 mg / m ² and the content of other compounds is 10 to 100 mg / m ² .

The present inventor has conducted investigations to achieve the above-mentioned object, and as a result, has found that the surface of the magnetic layer is affected by cis
1,2-cyclohexanedicarboxylic acid and / or cis-
1,4-cyclohexanedicarboxylic acid, trans-cinnamic acid, 2,3-naphthalenediol, 1,2-naphthalenediol, 1,8-naphthalenediol or 1,5-
If naphthalenediol is present, head corrosion,
It was found that the burn-in was suppressed and the error rate did not rise. In particular, when 1,5-naphthalenediol is used, the above effect can be obtained even in a small amount as compared with the case of using other compounds, and therefore plastic flow of the magnetic layer due to plasticization is suppressed during many times of travel, and the friction coefficient is reduced. It can be lowered further.

Further, cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid, trans-cinnamic acid, 2,3-naphthalenediol, 1,2-naphthalenediol, 1,8 In order to allow naphthalene diol or 1,5-naphthalene diol to be continuously present on the surface of the magnetic layer during high-speed sliding, polyhydric carboxylic acid or the like is adsorbed on the magnetic powder to make the surface of the magnetic powder acidic.
It was found that the adsorption of the above compounds had to be suppressed.

That is, even if the magnetic tape is run a number of times in a high temperature and low humidity environment or a low humidity environment, the error rate does not increase if the following two items (1) and (2) are mainly satisfied. .

(1) The surface of the magnetic powder is made acidic by adsorbing a polycarboxylic acid or the like on the magnetic powder. For this purpose, the polyvalent carboxylic acid or the like may be added to and mixed with the magnetic coating material, or the magnetic powder may be previously subjected to an acid treatment by dipping the magnetic powder in a solution of the polyvalent carboxylic acid or the like.

(2) Then, cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid, trans-cinnamic acid, 2,
Add 3-naphthalene diol, 1,2-naphthalene diol, 1,8-naphthalene diol or 1,5-naphthalene diol. Alternatively, cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid, trans-cinnamic acid, 2,3-
Naphthalene diol, 1,2-naphthalene diol,
A solution of 1,8-naphthalenediol or 1,5-naphthalenediol is applied on (or on) the magnetic layer.

As the magnetic powder used in the present invention, any conventionally known magnetic powder can be used.
It may be an oxide magnetic powder or a metal magnetic powder.

As the oxide magnetic powder, for example, γ-Fe
₂ O ₃ , Co-containing γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co-containing Fe ₃ O ₄ , Co-deposited γ-Fe ₂ O ₃ , Co-deposited Fe ₃ O ₄ , CrO _{2 and the} like can be mentioned.

As the magnetic metal powder, for example, Fe, Co,
Ni, Fe-Co, Fe-Ni, Fe-Co-Ni, Co-Ni, Fe-Co-
B, Fe-Co-Cr-B, Mn-Bi, Mn-Al, Fe-Co-V, and the like, and further for the purpose of improving various characteristics of these.
A metal component such as Al, Si, Ti, Cr, Mn, Cu, or Zn may be added.

Further, hexagonal ferrite such as barium ferrite, iron carbide such as Fe ₅ C ₂ and iron nitride can also be used.

In the present invention, the above magnetic powder is preferably surface-treated with a polycarboxylic acid. By adsorbing the polyvalent carboxylic acid on the magnetic powder, the surface of the magnetic powder can be made acidic. Without such acidification, it is considered that the above-mentioned compounds such as cyclohexanedicarboxylic acid and the like are directly adsorbed on the surface of the magnetic powder to reduce the amount present on the surface of the magnetic layer, and the effect of preventing head surface corrosion is deteriorated. To be

Here, the polyvalent carboxylic acid used is a carboxylic acid having two or more carboxyl groups in the molecule, and such a polyvalent carboxylic acid having two carboxyl groups, for example, , Oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. When there are three carboxyl groups, for example,
Examples thereof include citric acid, tricarballylic acid, benzenetricarboxylic acid and the like. If there are 4 carboxyls,
For example, benzenetetracarboxylic acid and the like can be mentioned.

Of these, polyvalent carboxylic acids having 2 to 5 carbon atoms in the molecule are preferable, and 3 to 3 carbon atoms are particularly preferable.
4 is a polycarboxylic acid, for example, citric acid.

In the magnetic layer of the magnetic recording medium of the present invention, cyclohexanedicarboxylic acid (particularly cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid) is added together with the above-mentioned surface-treated magnetic powder. It is preferable that the above-mentioned compounds such as acid) are contained.

Cis-1,2-cyclohexanedicarboxylic acid and cis-1,4-cyclohexanedicarboxylic acid are
The magnetic layers may be contained individually or in combination.

Cyclohexanedicarboxylic acid such as cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid in the magnetic layer, trans-cinnamic acid, 2,3-naphthalenediol, 1,2. −
Naphthalene diol, 1,8-naphthalene diol,
The content of compounds such as 1,5-naphthalenediol is 0.15 to 5 parts by weight per 100 parts by weight of magnetic powder (particularly 0.3 to 3 parts by weight for naphthalenediol, and 0.15 to 3 parts by weight for 1,5-naphthalenediol). It is preferably within the range of (part). This content is less than 0.3 parts by weight (1,5
-0.15 parts by weight for naphthalenediol),
In some cases, the amount of the compound such as cyclohexanedicarboxylic acid present on the surface of the magnetic layer is insufficient, and the effect of suppressing the corrosion and burn-in on the magnetic head surface may not be obtained. Further, when the content of the compound such as cyclohexanedicarboxylic acid exceeds 5 parts by weight (3 parts by weight for 1,5-naphthalenediol), the ratio of the magnetic powder becomes relatively small, which may affect the magnetic properties. In some cases, the magnetic layer is plasticized and plastic flow occurs due to a large number of runnings to increase the friction coefficient, and even if the content is increased, the effect corresponding to this may not be obtained.

Further, in the present invention, instead of containing a compound such as cyclohexanedicarboxylic acid such as cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid in the magnetic layer. Or in combination therewith, a compound such as cyclohexanedicarboxylic acid such as cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid is deposited on the magnetic layer (or surface). May be.

The deposition of a compound such as cyclohexanedicarboxylic acid such as cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid onto the magnetic layer is carried out by coating the magnetic coating on a non-magnetic support. Can be achieved by applying a solution of a compound such as cyclohexanedicarboxylic acid such as cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid on the surface of the magnetic layer after coating and drying. .

The coating amount of the compound, such as cyclohexane dicarboxylic acid onto the magnetic layer is preferably in the range of (10~~100mg / m ^2, especially compounds other than 1,5-naphthalene diol) 5~100mg / m ^2. If the coating amount is less than 10 mg / m ² (less than 5 mg / m ² for 1,5-naphthalenediol), the amount of compounds such as cyclohexanedicarboxylic acid present on the magnetic layer will be insufficient, and the magnetic head surface will be corroded. In some cases, the effect of suppressing On the other hand, if the coating amount exceeds 100 mg / m ² , the running property may worsen and the spacing loss with the head may increase.

The magnetic layer is prepared by dispersing the above magnetic powder in a binder, and usable binders are vinyl copolymers such as modified or non-modified vinyl chloride resins,
Polyester polyurethane resin, polycarbonate polyurethane resin, or polyester resin can be used or mixed, and further, fibrous resin such as nitrocellulose, phenoxy resin, or thermoplastic resin having a specific usage system, thermosetting resin, reaction Type resin, electron beam irradiation curable resin, etc. may be used in combination. The group introduced for the above modification can improve the dispersibility of the magnetic powder --SO.
₃ M, -OSO ₃ M, -COOM, -PO (OM ') _{2 and the} like (M
Is an alkali metal atom such as Na, M'is the same alkali metal atom or an alkyl group).

As the usable fibrous resin, cellulose ether, cellulose inorganic acid ester, cellulose organic acid ester and the like can be used. Phenoxy resin has advantages such as high mechanical strength, excellent dimensional stability, good heat resistance, water resistance, chemical resistance, and good adhesiveness.

Further, it is preferable to add a curing agent to such a binder in order to further improve durability. As this curing agent, polyfunctional isocyanates can be used, especially tolylene diisocyanate (TD
The I) system is preferred. The addition amount of the curing agent is preferably 5 to 30% by weight based on the total amount of the binder.

In the magnetic recording medium of the present invention,
Furthermore, if necessary, a dispersant such as lecithin, a lubricant such as stearic acid ester, an antistatic agent such as carbon black, an abrasive such as alumina, and a rust preventive may be added. As the dispersant, the lubricant, the antistatic agent and the rust preventive, any conventionally known material can be used, and the dispersant is not limited at all.

Examples of the nonmagnetic support usable in the present invention include polyesters such as polyethylene terephthalate film and polyethylene-2,6-naphthalate film, and aramid film. An intermediate layer or an undercoat layer may be provided on the surface of the non-magnetic support in order to improve the adhesiveness of the magnetic layer.

To form the above-mentioned magnetic layer on a non-magnetic support, for example, the constituents of the magnetic layer and polyvalent carboxylic acid are dispersed in a binder, and ethers and esters are added depending on the kind of the binder. , A ketone, an aromatic hydrocarbon, an aliphatic hydrocarbon, an organic chlorine compound-based solvent and the like are dispersed together with an organic solvent to prepare a magnetic paint, and cis-1,
2-cyclohexanedicarboxylic acid and / or cis-1,
Add a compound such as 4-cyclohexanedicarboxylic acid,
This paint is applied to the surface of the non-magnetic support, dried and calendered.

Further, for example, the constituents of the magnetic layer and the polyvalent carboxylic acid are dispersed in a binder, and ethers, esters, ketones, aromatic hydrocarbons, aliphatic carbonizations, etc., depending on the kind of the binder. A magnetic coating material is prepared by dispersing it with an organic solvent selected from hydrogen, an organic chlorine compound-based solvent, etc. After coating the coating material on the surface of a non-magnetic support, drying and calendering, cis-1,2-cyclohexanedicarboxylic A solution of an acid and / or a compound such as cis-1,4-cyclohexanedicarboxylic acid is applied to the surface of the magnetic layer and dried.

A back coat layer is provided on the surface (rear surface) of the non-magnetic support, on which the magnetic layer is not provided, for the purpose of improving the running property of the magnetic recording medium, preventing charging and preventing transfer. You can The back coat layer can also contain a binder (basically the same kind of binder as that used in the magnetic layer), various conventionally known additive components for the back coat layer, and the like.

In the magnetic recording medium of the present invention, cyclohexanedicarboxylic acid (particularly cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-cyclohexanedicarboxylic acid) or the like is formed on the surface of the magnetic layer even at high speed sliding. The sufficient presence of the compound can suppress the corrosion of the head. Therefore, it is possible to suppress an increase in the error rate, which is suitable not only for the helical scan method, but also for magnetic tapes of all kinds as a measure for preventing head burn-in.

FIG. 1 shows an example of a magnetic recording medium of the present invention (a backup tape for a computer). That is, on the non-magnetic support 1, there is a magnetic layer 2 containing the magnetic powder whose surface has been acidified as described above, a binder, and the above-mentioned cyclohexanedicarboxylic acid or the like. Further, the other surface may have a back coat layer 3 mainly composed of a non-magnetic powder and a binder as indicated by a chain line.

[0038]

EXAMPLES The present invention will be described below with reference to specific examples, but it goes without saying that the present invention is not limited to these examples.

Example 1 Materials having the following compositions were mixed and dispersed in a sand mill for 4 hours to prepare a magnetic coating material.

<Magnetic coating composition I> Magnetic powder: Fe-based metal magnetic powder (specific surface area BET value = 50 m ² / g) 100 parts by weight Binder: Polyester polyurethane resin 8 parts by weight (Nipporan N2304 manufactured by Nippon Polyurethane Co., Ltd.) ") Vinyl chloride-vinyl acetate copolymer 8 parts by weight (" VAGH "manufactured by U.C.C. in the United States) Additive: carbon black 4 parts by weight (" Asahi Carbon 50 "manufactured by Asahi Carbon Co., Ltd.) Abrasive: alumina ( Al ₂ O ₃ ) (AKP50) 8 parts by weight Lubricant: butyl stearate 2 parts by weight Polycarboxylic acid: citric acid 3 parts by weight Solvent: methyl ethyl ketone 150 parts by weight Toluene 70 parts by weight

At the time of applying the above-mentioned magnetic paint I, 2 parts by weight of cis-1,2-cyclohexanedicarboxylic acid, 4 parts by weight of a curing agent (Coronate L) and 1 part by weight of myristic acid were added to give a thickness of A polyethylene terephthalate film having a thickness of 7 μm was applied so as to have a thickness of 3 μm. After calendering, it was left in an oven at 60 ° C. for 20 hours to prepare a wide base film with a magnetic layer.

Next, the materials having the following compositions were placed in a ball mill.
After mixing and dispersing for 24 hours, a coating material for back coat layer was prepared.

<Backcoat layer coating composition> 100 parts by weight of carbon black ("RAVEN-1255" manufactured by Colombian Carbon Co., Ltd.) Binder: 100 parts by weight of polyester polyurethane resin ("Nipporan N2304" manufactured by Nippon Polyurethane Co., Ltd.) Solvent : Methyl ethyl ketone 500 parts by weight Toluene 500 parts by weight

After adding 20 parts by weight of a curing agent (Coronate L), the above coating composition for back coat layer was applied to the other surface of the film with a magnetic layer prepared above so as to have a thickness of 0.7 μm. After that, a slit was made in a width of 8 mm to prepare a magnetic tape A. This was incorporated into a shell for data 8 mm.

Comparative Example 1 Magnetic paint II was prepared by mixing and dispersing materials having the same composition as in the magnetic paint composition of Example 1 in a sand mill for 4 hours except that citric acid was not added.

Then, the above magnetic coating material was applied in the same manner as described in Example 1, a back coat layer was applied, and slitting was performed to prepare a magnetic tape a. This was incorporated into a shell for data 8 mm.

Comparative Example 2 A magnetic paint was prepared using the magnetic paint composition I used in Example 1. Using the magnetic paint, a magnetic tape b was prepared in the same manner as in Comparative Example 1 and incorporated into a data 8 mm shell.

Comparative Example 3 The magnetic coating composition II used in Comparative Example 1 was cis-1,2-
A magnetic tape c was prepared in the same manner as in Comparative Example 1 except that 2 parts by weight of cyclohexanedicarboxylic acid was added to prepare a magnetic paint.
Was created and incorporated into a shell for data 8 mm.

Example 2 In the magnetic coating composition I used in Example 1, the
A magnetic coating material having the same composition except that 1,2-cyclohexanedicarboxylic acid was not added was prepared, and this magnetic coating material was applied and dried in the same manner as in Example 1.

Then, a 0.5% ethanol solution of cis-1,2-cyclohexanedicarboxylic acid was applied to the surface of the magnetic layer and dried. Next, a back coat layer was formed in the same manner as in Example 1, and after slitting to prepare a magnetic tape B, the magnetic tape B was incorporated into a shell for data of 8 mm.

Comparative Example 4 A magnetic paint was prepared using the magnetic paint composition II used in Comparative Example 1, coated and dried in the same manner as in Comparative Example 1, and cis-1,2-cyclohexane was applied to the surface of the magnetic layer. Dicarboxylic acid
A 0.5% ethanol solution was applied. Next, a back coat layer was formed in the same manner as in Example 1 and slitting was performed to prepare a magnetic tape d, which was incorporated into a shell for data of 8 mm.

Example 3 In Example 1, 2 parts of trans-cinnamic acid was added to the magnetic paint I.
A magnetic tape C was prepared in the same manner except that parts by weight were added and "Asahi Carbon 50" manufactured by Asahi Carbon Co., Ltd. was used as the carbon black of the coating material for the back coat layer. This was incorporated into a shell for data 8 mm.

Comparative Example 5 A magnetic tape e was prepared in the same manner as in Example 3 except that 2 parts by weight of trans-cinnamic acid was added to the magnetic coating composition II used in Comparative Example 1 to prepare a magnetic coating. , The data was incorporated in the shell for 8 mm.

Example 4 A magnetic coating composition having the same composition as in the magnetic coating composition I used in Example 3 except that trans-cinnamic acid was not added, and this magnetic coating composition was applied in the same manner as in Example 3. -Dry.

Then, a 0.5% ethanol solution of trans-cinnamic acid was applied to the surface of the magnetic layer and dried. Next, a back coat layer was formed in the same manner as in Example 3, and after slitting to prepare a magnetic tape D, it was incorporated into a shell for data of 8 mm.

Comparative Example 6 A magnetic paint was prepared using the magnetic paint composition II used in Comparative Example 1, coated and dried in the same manner as in Comparative Example 1, and 0.5% of trans-cinnamic acid was applied to the surface of the magnetic layer. % Ethanol solution was applied. Next, a back coat layer was formed in the same manner as in Example 3, slitting was performed to prepare a magnetic tape f, which was incorporated into a shell for data of 8 mm.

Example 5 In Example 1, except that 2 parts by weight of 2,3-naphthalenediol was added to the magnetic paint I, and "Asahi Carbon 50" manufactured by Asahi Carbon Co. was used as the carbon black for the back coat layer. In the same manner, a magnetic tape E was prepared. This was incorporated into a shell for data 8 mm.

Comparative Example 7 A magnetic tape g was prepared in the same manner as in Example 5 except that 2 parts by weight of 2,3-naphthalenediol was added to the magnetic coating composition II used in Comparative Example 1 to prepare a magnetic coating. Then, it was incorporated into a shell for data 8 mm.

Example 6 In the magnetic coating composition I used in Example 5, 2, 3
A magnetic coating material having the same composition except that naphthalene diol was not added was prepared, and this magnetic coating material was applied and dried in the same manner as in Example 5.

Then, a 0.5% toluene solution of 2,3-naphthalenediol was applied to the surface of the magnetic layer and dried. Next, a back coat layer was formed in the same manner as in Example 5, and a magnetic tape F was produced through slitting and then incorporated into a shell for data 8 mm.

Example 7 A magnetic coating composition prepared by adding 0.1 part by weight of 2,3-naphthalenediol to the magnetic coating composition I used in Example 1 was used.
A magnetic tape G was prepared in the same manner as above except that the magnetic layer was formed by coating and drying in the same manner as described above, and "Asahi Carbon 50" manufactured by Asahi Carbon Co., Ltd. was used as the carbon black for the back coat layer. This was incorporated into a shell for data 8 mm.

Comparative Example 8 A magnetic paint was prepared using the magnetic paint composition II used in Comparative Example 6, coated and dried in the same manner as in Comparative Example 6, and 2,3-naphthalenediol was added to the surface of the magnetic layer. A 0.5% toluene solution was applied. Next, a back coat layer was formed in the same manner as in Comparative Example 6, and a magnetic tape h was produced through slitting, and this was incorporated into a shell for data 8 mm.

Example 8 In Example 1, except that 2 parts by weight of 1,2-naphthalenediol was added to the magnetic paint I, and "Asahi Carbon 50" manufactured by Asahi Carbon Co., Ltd. was used as the carbon black for the back coat layer paint. In the same manner, a magnetic tape H was prepared. This was incorporated into a shell for data 8 mm.

Comparative Example 9 A magnetic tape i was prepared in the same manner as in Example 7 except that 2 parts by weight of 1,2-naphthalenediol was added to the magnetic coating composition II used in Comparative Example 1 to prepare a magnetic coating. Then, it was incorporated into a shell for data 8 mm.

Example 9 In the magnetic coating composition I used in Example 8, 1, 2
A magnetic coating material having the same composition except that naphthalenediol was not added was prepared, and this magnetic coating material was applied and dried in the same manner as in Example 8.

Then, a 0.5% toluene solution of 1,2-naphthalenediol was applied to the surface of the magnetic layer and dried. Next, a back coat layer was formed in the same manner as in Example 8, and after slitting to prepare a magnetic tape I, the magnetic tape I was incorporated into a shell for data of 8 mm.

Example 10 A magnetic coating composition prepared by adding 0.1 part by weight of 1,2-naphthalenediol to the magnetic coating composition I used in Example 1 was used.
A magnetic tape J was prepared in the same manner as above except that Asahi Carbon 50 manufactured by Asahi Carbon Co., Ltd. was used as the carbon black of the coating material for the backcoat layer by coating and drying in the same manner as above. This was incorporated into a shell for data 8 mm.

Comparative Example 10 A magnetic coating composition was prepared using the magnetic coating composition II used in Comparative Example 6, coated and dried in the same manner as in Comparative Example 6, and 1,2-naphthalenediol was added to the surface of the magnetic layer. A 0.5% toluene solution was applied. Next, a back coat layer was formed in the same manner as in Comparative Example 6, and a magnetic tape j was produced through slitting, and this was incorporated into a shell for data 8 mm.

Example 11 In Example 1, except that 2 parts by weight of 1,8-naphthalenediol was added to the magnetic paint I and "Asahi Carbon 50" manufactured by Asahi Carbon Co. was used as the carbon black for the back coat layer. In the same manner, a magnetic tape K was prepared. This was incorporated into a shell for data 8 mm.

Comparative Example 11 A magnetic tape k was prepared in the same manner as in Example 11 except that 2 parts by weight of 1,8-naphthalenediol was added to the magnetic coating composition II used in Comparative Example 1 to prepare a magnetic coating. Then, it was incorporated into a shell for data 8 mm.

Example 12 In the magnetic coating composition I used in Example 11, 1,8
A magnetic paint having the same composition was prepared except that naphthalenediol was not added, and this magnetic paint was applied and dried in the same manner as in Example 11.

Then, a 0.5% toluene solution of 1,8-naphthalenediol was applied to the surface of the magnetic layer and dried. Next, a back coat layer was formed in the same manner as in Example 11, and after slitting to prepare a magnetic tape L, it was incorporated into a shell for data of 8 mm.

Comparative Example 12 A magnetic coating composition was prepared using the magnetic coating composition II used in Comparative Example 6, coated and dried in the same manner as in Comparative Example 6, and 1,8-naphthalenediol was added to the surface of the magnetic layer. A 0.5% toluene solution was applied. Next, a back coat layer was formed in the same manner as in Comparative Example 8 and slitting was performed to prepare a magnetic tape 1, which was incorporated into a data 8 mm shell.

Example 13 In Example 1, except that 2 parts by weight of 1,5-naphthalenediol was added to the magnetic paint I, and "Asahi Carbon 50" manufactured by Asahi Carbon Co., Ltd. was used as the carbon black for the back coat layer. In the same manner, a magnetic tape M was prepared. This was incorporated into a shell for data 8 mm.

Comparative Example 13 A magnetic tape m was prepared in the same manner as in Example 13 except that 2 parts by weight of 1,5-naphthalenediol was added to the magnetic coating composition II used in Comparative Example 1, and the data was used for 8 mm data. Built into the shell.

Example 14 In the magnetic coating composition I used in Example 13, 1,5
A magnetic paint having the same composition was prepared except that naphthalenediol was not added, and this magnetic paint was applied and dried in the same manner as in Example 13.

Then, a 0.1% toluene solution of 1,5-naphthalenediol was applied to the surface of the magnetic layer and dried. Next, a back coat layer was formed in the same manner as in Example 13, a magnetic tape N was produced through slitting, and then the magnetic tape N was incorporated into a shell for data 8 mm.

Comparative Example 14 A magnetic paint was prepared using the magnetic paint composition II used in Comparative Example 6, coated and dried in the same manner as in Comparative Example 6, and 1,5-naphthalenediol was added to the surface of the magnetic layer. A 0.1% toluene solution was applied. Next, a back coat layer was formed in the same manner as in Comparative Example 6, and a magnetic tape n was prepared through slitting, and this was incorporated into a shell for data 8 mm.

Example 15 In Example 1, 0.2 parts by weight of 1,5-naphthalenediol was added to the magnetic paint I, and "Asahi Carbon 50" manufactured by Asahi Carbon Co., Ltd. was used as the carbon black for the back coat layer. In the same manner, a magnetic tape O was prepared. This was incorporated into a shell for data 8 mm.

The magnetic tape obtained in each of the above examples was subjected to a running durability test described below (running durability test conducted on 8 mm of medium data used for ordinary data storage), and the results are shown in the table below. 1 to Table 5 are shown.

Running durability test: Test environment: temperature 45 ° C., humidity 30%
Drive used by RH: "EXB-850" manufactured by Exabyte
It was measured at "0". Measurement method: Block error rate (BER) was measured by running 50 or 1000 passes. One pass is as follows. Write data over 32,000 blocks. Rewind and return to the original position. Read the written data of 32,000 blocks. Rewind and return to the original position. However, when the block error rate is indicated by E%, this indicates that out of 32,000 blocks, 320 × E blocks could not be normally written or read.

The friction coefficient of each magnetic tape was evaluated as follows. μ0: Coefficient of friction of initial magnetic layer μ1000: Coefficient of friction of magnetic layer after 1000 passes

[0083] However, CHDC ^{* 1} : cis-1,2-cyclohexanedicarboxylic acid BER ^{* 2} , ^{* 3} : Block error rat
e) Internal addition ^{* 4} : Addition in the magnetic layer Application ^{* 5} : Application on the magnetic layer

As is clear from Table 1, in the magnetic recording media of Examples 1 and 2 according to the present invention, 45 ° C., 30%
Even when running at a high temperature and low humidity of RH, the burn-in of the magnetic head is suppressed and the error rate does not rise.

Further, in Example 1 or 2, cis-1,4-cyclohexanedicarboxylic acid was used as the cyclohexanedicarboxylic acid, magnetic tapes were prepared in the same manner, and the running durability test conducted on them was also good. The results were obtained.

[0086] However, TCA ^{* 1} : trans-cinnamic acid BER ^{* 2} , ^{* 3} : block error rate
e) Internal addition ^{* 4} : Addition in the magnetic layer Application ^{* 5} : Application on the magnetic layer

As is clear from Table 2, in the magnetic recording media of Examples 3 and 4 according to the present invention, 45 ° C., 30%
Even when running at a high temperature and low humidity of RH, the burn-in of the magnetic head is suppressed and the error rate does not rise.

[0088] However, ND ^{* 1} : 2,3-naphthalenediol BER ^{* 2} , ^{* 3} : Block error rate (Block error rat
e) Internal addition ^{* 4} : Addition in the magnetic layer Application ^{* 5} : Application on the magnetic layer

In the sample of Comparative Example 8 in which ND was not applied, the BER at the 1000th pass was 5.3%, and μ0 was 0.32, μ.
1000 was 0.35, and in the sample of Example 6 in which ND was not applied, BER at the 1000th pass was 6.1%, μ0 was 0.30, μ
1000 was 0.35.

As is clear from Table 3, in the magnetic recording media of Examples 5 to 7 according to the present invention, 45 ° C., 30% RH
Even if the magnetic head is run under high temperature and low humidity, corrosion and burn-in of the magnetic head are suppressed, and the increase in error rate is reduced. In addition, the coefficient of friction can also be kept small.

[0091] However, ND treatment @: 1,2-naphthalene diol ND treatment #: 1,8-naphthalene diol BER ^{* 2} , ^{* 3} : Block error rate
e) Internal addition ^{* 4} : Addition in the magnetic layer Application ^{* 5} : Application on the magnetic layer

[0092] However, ND treatment @: 1,2-naphthalene diol ND treatment #: 1,8-naphthalene diol BER ^{* 2} , ^{* 3} : Block error rate
e) Internal addition ^{* 4} : Addition in the magnetic layer Application ^{* 5} : Application on the magnetic layer

In the sample of Comparative Example 10 in which ND was not applied, the BER at the 1000th pass was 5.3%, and μ0 was 0.35, μ.
1000 was 0.38, and in the sample of Example 9 in which ND was not applied, the BER at the 1000th pass was 6.1%, μ0 was 0.30, μ
1000 was 0.35.

As is clear from Table 4, in the magnetic recording media of Examples 8 to 12 according to the present invention, 45 ° C., 30% RH
Even if the magnetic head is run under high temperature and low humidity, corrosion and burn-in of the magnetic head are suppressed, and the increase in error rate is reduced. In addition, the coefficient of friction can also be kept small.

[0095] However, ND ^{* 1} : 1,5-naphthalenediol BER ^{* 2} , ^{* 3} : Block error rate
e) Internal addition ^{* 4} : Addition in the magnetic layer Application ^{* 5} : Application on the magnetic layer

As is clear from Table 5, the magnetic recording media of Examples 13 to 15 according to the present invention were 45 ° C. and 30%.
Corrosion and burn-in of the magnetic head are suppressed even when the vehicle is run under the high temperature and low humidity of RH, and the error rate does not increase. In addition, the coefficient of friction can also be kept small. And 1,
It is clear that 5-naphthalenediol exerts its effect even in a small amount unlike other compounds.

[0097]

In the magnetic recording medium of the present invention, the magnetic powder is surface-treated with an acid and a compound such as cyclohexanedicarboxylic acid is present on the surface of the magnetic layer to prevent corrosion of the magnetic head surface during high-speed sliding. Even if the magnetic head is driven in an environment of high temperature and low humidity, the magnetic head is prevented from being burned, and the error rate does not increase.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structural example of a magnetic recording medium to which the present invention is applied.

[Explanation of symbols]

 1 ... Non-magnetic support 2 ... Magnetic layer 3 ... Back coat layer

Claims (4)

[Claims] 1. A magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support, and the magnetic powder is surface-treated with an acid to prepare cyclohexanedicarboxylic acid and trans. -With cinnamic acid, 2,
At least one compound selected from the group consisting of 3-naphthalene diol, 1,2-naphthalene diol, 1,8-naphthalene diol, and 1,5-naphthalene diol is contained in the magnetic layer. A magnetic recording medium characterized by being present. 2. A magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support, wherein the magnetic powder is surface-treated with an acid to prepare cyclohexanedicarboxylic acid and trans. -With cinnamic acid, 2,
At least one compound selected from the group consisting of 3-naphthalene diol, 1,2-naphthalene diol, 1,8-naphthalene diol, and 1,5-naphthalene diol is deposited on the magnetic layer. A magnetic recording medium characterized by the following. 3. The acid is a polycarboxylic acid having two or more carboxyl groups, and cyclohexanedicarboxylic acid among the compounds is cis-1,2-cyclohexanedicarboxylic acid and / or cis-1,4-. The magnetic recording medium according to claim 1 or 2, which is cyclohexanedicarboxylic acid. 4. The content of the compound in the magnetic layer according to claim 1 is 0.15 to 5 parts by weight with respect to 100 parts by weight of the magnetic powder, and the coating amount of the compound onto the magnetic layer according to claim 2 is 5-100m
The magnetic recording medium according to claim 1, which is g / m ² .