JP2005120146A - Lubricant and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant which is excellent in lubricity and rust prevention effects under various service conditions, maintains lubrication effects and rust prevention effects for a long period, and provides excellent travelling performance, abrasion resistance, durability, corrosion resistance, and the like; and a recording medium using the lubricant. <P>SOLUTION: The lubricant is composed of a triazole compound represented by general formula (1) [e.g. a compound represented by chemical formula (1)] and having at least one triazole skeleton and at least one ester bond and is caused to be present on or in a recording layer of a recording medium. In the general formula (1), R<SP>1</SP>, R<SP>2</SP>, and R<SP>3</SP>are each a hydrogen atom, or a substituted or unsubstituted, saturated or unsaturated, fluorine-containing hydrocarbon or hydrocarbon group, provided that at least one of R<SP>1</SP>, R<SP>2</SP>, and R<SP>3</SP>contains at least one ester bond; all of R<SP>1</SP>, R<SP>2</SP>, and R<SP>3</SP>are not simultaneously a hydrogen atom; and R<SP>2</SP>and R<SP>3</SP>may form a ring together with each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lubricant used for a magnetic recording medium and the like, and a recording medium such as a magnetic recording medium using the lubricant.

  As a conventional recording medium, for example, a magnetic recording medium, a so-called metal thin film type magnetic recording medium in which a ferromagnetic metal material is deposited on a nonmagnetic support by a technique such as vapor deposition and this is used as a magnetic layer, There is known a so-called coating-type magnetic recording medium in which a magnetic coating material containing fine magnetic particles and a resin binder is coated on a nonmagnetic support and this is used as a magnetic layer.

  Since these conventional magnetic recording media have extremely good smoothness on the surface of the magnetic layer, a substantial contact area with a sliding member such as a magnetic head or a guide roller is large, and thus a friction coefficient is increased, and an adhesion phenomenon is caused. (So-called sticking) easily occurs, and there are many problems such as lack of running performance and durability.

  In addition, since a metal is used for the magnetic layer, the magnetic layer may corrode over time due to a high-temperature and high-humidity environment or the presence of corrosive gas, which may impair data storage reliability.

  Therefore, it has been studied to use various lubricants in order to improve problems such as adhesion phenomenon, running performance and durability. Conventionally, higher fatty acids and esters thereof have been used as magnetic layers of magnetic recording media. Attempts have been made to suppress the friction of the magnetic layer by suppressing the friction by adding it internally or by top coating.

However, a lubricant used for a magnetic recording medium or the like is required to have extremely strict characteristics. That is, the lubricant used in the magnetic recording medium includes
(1) Excellent low temperature characteristics to ensure a predetermined lubrication effect when used in cold regions;
(2) Since spacing with the magnetic head becomes a problem, it can be applied very thinly, and in that case, sufficient lubrication characteristics can be exhibited.
(3) Withstand long-term or long-term use and maintain a lubricating effect;
(4) It is required to prevent corrosion of the magnetic layer over a long period of time.

  In addition, various compounds are held in the recording medium in order to improve the corrosion resistance, prevent the corrosion of the magnetic layer, improve the storage characteristics of the magnetic recording medium, and increase the storage reliability of the data. .

  For example, in a coating type magnetic recording medium, a triazole derivative is contained as a nitrogen-containing aromatic compound in a magnetic layer in Patent Document 1 described later. In JP-A-6-36268 and JP-A-7-73451, a tetrazaindene derivative, which is a nitrogen-containing compound, is contained in the metal particle surface or the magnetic layer. Japanese Patent Application Laid-Open No. 2001-84729 proposes an example in which a nitrogen-containing heterocyclic compound or a derivative thereof is contained in a liner of a flexible disk as a rust inhibitor. In JP-A Nos. 2002-123924 and 2002-123925, a nitrogen-containing heterocyclic compound having a group or a site adsorbing to a polyphenol or an acidic group is contained in the magnetic layer, respectively. Yes. Furthermore, in Japanese Patent Application Laid-Open No. 2002-367151, an attempt is made to contain a nitrogen-containing heterocyclic compound as a rust inhibitor in the nonmagnetic layer.

  However, all of these are limited to coating type magnetic recording media, and application to so-called metal thin film type magnetic recording media is not considered. Furthermore, it is a device that is not related to the lubrication characteristics that are important for the recording medium, and the fundamental countermeasures such as suppression of the degradation of the lubrication characteristics that can contribute to media corrosion are insufficiently considered, Sufficient consideration has not been given to improving the lubrication characteristics.

  On the other hand, in a metal thin film type magnetic recording medium, for example, in Patent Document 2 described later, a phosphoric ester compound is contained in a protective layer, and if necessary, a perfluoropolyether having a terminal substituted with a triazole group is added. Attempts have been made. JP-A-6-76272 discloses an example in which a tetrazaindene ring compound is used as a protective layer in combination with a fluorine compound, and JP-A-7-210862 holds a cation. An example in which a lubricating layer made of perfluoroalkyl polyether is used and a rust inhibitor is added as necessary is shown.

  In addition to these contrivances in terms of materials, there are also examples in which contrivances are made in the structure of the medium. For example, Japanese Patent Application Laid-Open No. 6-36258 shows an example in which a rust preventive agent is filled in a gap in a magnetic recording layer. In JP-A-6-195696, a rust preventive layer made of a nitrogen-containing organic compound is provided between a ferromagnetic metal thin film layer and a lubricant layer, and a triple thin film configuration is adopted. Japanese Patent Laid-Open No. 9-35238 discloses an example in which a magnetic thin film has a two-layer structure and a rust preventive layer is provided between them. In Japanese Patent Laid-Open No. 9-35239, a base film and a magnetic layer are provided. The example which provides a rust preventive agent layer in between is shown. Furthermore, in Japanese Patent Laid-Open Nos. 9-282634 and 9-282644, a case is proposed in which a rust preventive agent is encapsulated in a microcapsule and applied to the base film or internally added to the base film. Has been.

  However, many of these are effective only for improving the antirust property, and the effect of improving the lubricating property cannot be expected. Although there are a few, some surface treatments on the outermost layer of the medium are aimed at improving the lubrication characteristics, but in each of these cases, a rust inhibitor is added to improve the rust prevention characteristics. Yes. As long as the rust inhibitor is added, the compatibility between the rust inhibitor and the lubricant is always a concern. That is, the presence of the rust preventive agent or the aggregation of the rust preventive agent may prevent the uniform top coating of the lubricant.

  Further, since the lubricant and the rust preventive agent are generally quite different in structure, the adsorption behavior on the surface of the protective layer is usually different. This means that the durability of the two materials is different, which can result in irregularities in the media's durability over time. In particular, recent recording media have a very smooth surface due to high recording density, and the influence is unexpectedly great. In the publicly known materials listed above, it is difficult to say that sufficient consideration has been given to these points.

Japanese Patent Application Laid-Open No. 5-54363 (Pages 2, 3 and 5) JP-A-5-12656 (3rd, 6th, 7th, 11th, 15th and 16th pages, FIGS. 1 and 2)

  As described above, in the field of magnetic recording media, due to the lack of capability of the lubricant used, for example, the reproduction output is lowered in the shuttle running test, or does not have sufficient storage characteristics, etc. I am dissatisfied with the practical characteristics.

  In particular, conventional lubricants focus on maintaining a small coefficient of friction and good still durability, and the rust prevention effect, so-called corrosion resistance, is often considered secondarily. Alternatively, the lubricant itself specializes in realizing improvement of the lubrication characteristics, and most of the corrosion resistance satisfies the necessary conditions by adding a rust inhibitor.

  In view of the above circumstances, the object of the present invention is to exhibit excellent lubricity and rust preventive effect under various use conditions, and this lubrication effect and rust preventive effect last for a long period of time. Another object of the present invention is to provide a lubricant that provides the performance, wear resistance, durability and corrosion resistance, and a recording medium using the same.

（式中、Ｒ¹ 、Ｒ² 及びＲ³ は、非置換若しくは置換の、また、飽和若しくは不飽和の含フッ素炭化水素基或いは炭化水素基、若しくは水素原子であり、これらの基のいずれかに、少なくとも１つのエステル結合が含まれる。但し、Ｒ¹ 、Ｒ² 及びＲ³ のすべてが水素原子であることはなく、Ｒ² 及びＲ³ は共同して環を形成していてもよい。） That is, the present invention relates to a lubricant comprising a triazole compound represented by the following general formula (1) and having at least one triazole skeleton and at least one ester bond, and is also provided on or in the recording layer. And the recording medium in which the lubricant is held.
General formula (1):

(In the formula, R ¹ , R ² and R ³ are unsubstituted or substituted, saturated or unsaturated fluorine-containing hydrocarbon group or hydrocarbon group, or a hydrogen atom. And at least one ester bond, provided that R ¹ , R ² and R ³ are not all hydrogen atoms, and R ² and R ³ may form a ring together.)

  Since the triazole compound constituting the lubricant of the present invention has one triazole skeleton and at least one ester group at one end of the triazole compound molecule, the recording layer or It can be strongly bonded to the protective film (for example, carbon film). On the other hand, a fluorine-containing hydrocarbon group or hydrocarbon group that reduces surface energy and exhibits good lubricating properties exists at the other end of the triazole compound molecule.

  As a result, when the lubricant composed of the triazole compound is held in the recording layer or its protective film, the triazole compound molecules are strong at the one end where azo groups and ester bond groups exist. The fluorine-containing hydrocarbon group or the hydrocarbon group at the other end is bonded to the recording layer or the recording material or the protective film thereof, and is effectively gathered between molecules to form a hydrophobic group. A hydrophobic base layer that exhibits a high lubricating action due to the cohesive force is formed on the surface side. For this reason, the lubricant is firmly held in the recording layer or recording material and its protective film, and is not removed from the sliding surface even under harsh environments such as low temperature and low humidity. At the same time, a sufficient lubricating effect can be maintained for a long time.

  As a result, when applied to, for example, a magnetic recording medium, good sliding characteristics based on high lubrication performance are ensured, and magnetic head dirt and dropout due to wear generated between the magnetic head and the magnetic recording medium are reduced. The durability and runnability of the magnetic recording medium are greatly improved. In particular, in the magnetic recording medium, when the lubricant comprising the triazole compound of the present invention is applied on the carbon film layer that is the protective film, the triazole skeleton and ester bond group that are polar groups are adsorbed on the surface, which is favorable. A lubricant layer can be formed.

  Also, in conventional lubricants, compounds with relatively large polarity such as carboxylic acids, amines or carboxylic acid amine salts tend to have a low coefficient of friction but poor still durability, and are relatively polar like ester compounds. A compound having a small size is excellent in still durability, but tends to have a large friction coefficient. The triazole compound of the present invention has at least one ester bond as well as three relatively small azo groups as terminal polar groups, so that both reduction in friction coefficient and excellent still durability are balanced. Can be made.

  In addition, since the azo group of the triazole skeleton has the property of being easily adsorbed to the metal particles, even if a situation occurs in which the magnetic layer is exposed microscopically and locally, the surface is covered and corrosion is not caused. There is an action to suppress the progress, and the lubricant itself effectively exhibits the rust prevention effect.

  Therefore, when the lubricant of the present invention is used as a lubricant for a recording medium, for example, a lubricant for a magnetic recording medium, it achieves both good lubrication characteristics and an antirust effect, and has excellent lubricity under various usage conditions. Since the lubricating effect and the antirust effect are maintained over a long period of time, a recording medium having excellent running properties, wear resistance, durability, corrosion resistance, and the like can be provided.

  In addition, the conventional fluorine-containing lubricant is soluble only in a fluorine-based solvent, and a fluorine-based solvent is essential for coating, whereas the triazole-based compound is dissolved in a hydrocarbon-based solvent such as toluene or acetone. It can be dissolved and applied using these solvents. Compared with the fluorine-based solvent, the hydrocarbon-based solvent is preferable because the waste liquid treatment of the solvent is easy.

（式中、Ｒf は、非置換若しくは置換の、また、飽和若しくは不飽和の、含フッ素炭化水素基或いは炭化水素基である。） In the present invention, the triazole compound may be a triazole compound represented by the following general formula (2).
General formula (2):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.)

（式中、Ｒf は、非置換若しくは置換の、また、飽和若しくは不飽和の、含フッ素炭化水素基或いは炭化水素基である。） Further, the triazole compound may be a triazole compound represented by the following general formula (3).
General formula (3):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.)

（式中、Ｒf は、非置換若しくは置換の、また、飽和若しくは不飽和の、含フッ素炭化水素基或いは炭化水素基である。） Further, the triazole compound may be a triazole compound represented by the following general formula (4).
General formula (4):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.)

（式中、Ｒf１とＲf２とは、非置換若しくは置換の、また、飽和若しくは不飽和の、含フッ素炭化水素基或いは炭化水素基である。） Further, the triazole compound may be a triazole compound represented by the following general formula (5).
General formula (5):

(In the formula, Rf1 and Rf2 are unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon groups or hydrocarbon groups.)

（式中、Ｒf は、非置換若しくは置換の、また、飽和若しくは不飽和の、含フッ素炭化水素基或いは炭化水素基である。） Further, the triazole compound may be a triazole compound represented by the following general formula (6).
General formula (6):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.)

  In the present invention, the lubricant may be a lubricant composed of a triazole compound represented by the general formulas (2) to (6), or a mixture thereof.

  In the present invention, the triazole compound represented by the general formula (1) may be synthesized by any method. For example, an esterification reaction between a compound having an Rf group and a compound having a triazole skeleton Etc. can be synthesized. The triazole compounds represented by the general formulas (2) to (6) can be synthesized, for example, as follows.

  That is, the compound represented by the general formula (2) is a mixture of carboxylic acid chloride containing Rf group and 1H-benzotriazole-1-methanol, heated to about 100 ° C. and reacted as shown in the following reaction formula. After the reaction, impurities and unwanted substances are washed by washing with an organic solvent or inorganic solvent, separation washing with a separatory funnel, recrystallization purification using 2-propanol (isopropyl alcohol; IPA) and n-hexane, etc. The desired triazole compound can be obtained with high purity.

  The compound represented by the general formula (3) is a mixture of carboxylic acid chloride containing Rf group and 1-hydroxy-1H-benzotriazole, heated to about 100 ° C. and reacted as shown in the following reaction formula. Then, purification is performed in the same manner as described above, and the target triazole compound can be obtained with high purity.

  The compound represented by the general formula (4) is a mixture of carboxylic acid chloride containing Rf group and 1-hydroxy-1H-7-azabenzotriazole, heated to about 100 ° C. and represented by the following reaction formula. After the reaction, purification is performed in the same manner as described above, and the target triazole compound can be obtained with high purity.

  Further, the compound represented by the general formula (5) is prepared by dissolving an alcohol compound containing Rf1 group and Rf2 group and 1,2,3-triazole-4,5-dicarboxylic acid in toluene and refluxing the following compound. After reacting as shown in the reaction formula, purification is performed in the same manner as described above, and the target triazole compound can be obtained with high purity.

  The compound represented by the general formula (6) is prepared by dissolving an alcohol compound containing an Rf group and 1,5-dimethyl-1H-1,2,3-triazole-4-carboxylic acid in toluene and refluxing. However, after reacting as shown in the following reaction formula, purification is performed in the same manner as described above, and the target triazole compound can be obtained with high purity.

  As described above, when the lubricant composed of the triazole compound represented by the general formula (1) is applied to the recording layer or its protective layer, the fluorine-containing hydrocarbon group or the hydrocarbon group which is a hydrophobic group Lubricating action is expressed by the cohesive force. The hydrophobic group, that is, the fluorine-containing hydrocarbon group or the hydrocarbon group may be saturated or unsaturated, linear, branched or cyclic, but is preferably saturated and linear. For example, a group represented by the following general formula (7) or (8) is desirable.

（但し、前記一般式（７）において、ｌは、８〜３０、より望ましくは１２〜２０の範囲から選ばれる整数である。） General formula (7):

(However, in the general formula (7), l is an integer selected from the range of 8 to 30, more preferably 12 to 20.)

（但し、前記一般式（８）において、ｍとｎは、それぞれ、次の範囲から選ばれる整数で、
ｍ＝２〜２０、ｎ＝４〜１８、より望ましくは
ｍ＝４〜１３、ｎ＝４〜１０である。） General formula (8):

(However, in the general formula (8), m and n are each an integer selected from the following ranges:
m = 2 to 20, n = 4 to 18, more preferably m = 4 to 13, and n = 4 to 10. )

The fluorinated hydrocarbon group may be concentrated at one place as described above, or may be dispersed as shown in the following general formula (9), such as —CF ₂ — as well as —CHF—. May be.

（但し、前記一般式（９）において、ｎ１＋ｎ２＝ｎ、ｍ１＋ｍ２＝ｍである。） General formula (9):

(However, in the general formula (9), n1 + n2 = n and m1 + m2 = m.)

  In general formulas (7), (8) and (9), the number of carbon atoms is limited as described above because the number of carbon atoms (l + 1 or m + n + 1) constituting the alkyl group or fluorine-containing alkyl group is equal to or greater than the above lower limit. This is because the length becomes an appropriate length, the cohesive force between the hydrophobic groups is effectively exhibited, a good lubricating action is exhibited, and the friction / wear durability is improved. Moreover, it is because the solubility with respect to the solvent of the lubricant which consists of said triazole type compound is kept favorable that the carbon number is below the said minimum.

  In particular, when the hydrophobic group contains a fluorine atom, it is effective in reducing the friction coefficient and improving running performance. However, a hydrocarbon group is provided between the fluorine-containing hydrocarbon group and the ester bond, and the fluorine-containing hydrocarbon group and the ester bond are separated to ensure the stability of the ester bond and prevent hydrolysis. Good.

  Further, the hydrophobic group may have a fluoroalkyl ether group or a perfluoropolyether group.

  The hydrophobic group contains elements such as nitrogen, oxygen, sulfur, phosphorus, and halogen as constituent elements, and in addition to the functional groups described above, a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, and an ester bond Etc. may further be included.

  The triazole compound thus configured is soluble in a non-fluorine solvent with a low environmental load, and uses a general-purpose solvent such as a hydrocarbon solvent, a ketone solvent, an alcohol solvent, an ester solvent, or the like. Thus, it has the advantage that operations such as coating, dipping, and spraying can be performed. Specific examples include solvents such as hexane, heptane, octane, decane, dodecane, benzene, toluene, xylene, cyclohexane, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropanol, diethyl ether, tetrahydrofuran, dioxane, cyclohexanone. it can.

  The lubricant may be a recording medium lubricant, and in particular, the recording medium is a magnetic recording medium having a magnetic layer, and the lubricant is on the magnetic layer and / or in the magnetic layer. It is good to be done.

  In particular, when the triazole compound is applied as a lubricant on a carbon film layer disposed as a protective layer on the magnetic layer, three azo groups, which are polar bases of the lubricant molecule, and at least one on the carbon film layer. The ester bond group is adsorbed, and a lubricant layer with good durability can be formed by the cohesive force between the hydrophobic groups.

  The recording medium of the present invention comprises a layer containing the lubricant in some form. For example, when the recording medium is a magnetic recording medium, a so-called metal thin film type magnetic recording medium in which a ferromagnetic metal material is deposited on a nonmagnetic support by vapor deposition or the like and is used as a magnetic layer, or There is a so-called coating-type magnetic recording medium in which a magnetic coating material containing fine magnetic particles and a resin binder is coated on a nonmagnetic support and used as a magnetic layer. In these, the layer containing the lubricant may be a layer that coats the surface of the magnetic recording medium, or may be internally added to the magnetic layer.

  In this case, the nonmagnetic support may be a flexible substrate such as a plastic film or a rigid substrate such as glass.

  As described above, the lubricant of the present invention is preferably used as the lubricant for the recording medium, particularly the magnetic recording medium. However, the lubricant can be applied not only to the magnetic recording medium but also to an optical recording medium, and the support is not limited to a tape, and can also be used for a recording medium such as a disk medium such as a magnetic disk or an optical disk. .

  Hereinafter, taking the case where the lubricant is used as a lubricant for a magnetic recording medium as an example, a preferred embodiment of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a schematic sectional view of a metal thin film type magnetic recording medium 5. In this magnetic recording medium 5, on the nonmagnetic support 2, at least a magnetic layer 3 made of a metal magnetic thin film formed by a technique such as vapor deposition, a carbon protective film layer 4, and a lubricant layer containing the triazole compound. 1 are sequentially formed. Moreover, you may form a base layer between a nonmagnetic support body and a magnetic layer as needed.

  The nonmagnetic support 2 is not particularly limited, and a known one can be adopted. For example, when a rigid substrate such as an aluminum alloy plate or a glass plate is used as the nonmagnetic support 2, an oxide film such as alumite treatment or a nickel-phosphorus film is formed on the substrate surface to harden the surface. You may make it do.

  The metal magnetic thin film constituting the magnetic layer 3 is not particularly limited, and a known one can be adopted. For example, it is formed as a continuous film by a technique such as plating, sputtering, or vacuum vapor deposition. For example, a metal such as Fe, Co, Ni, Co—Ni alloy, Co—Pt alloy, Co—Pt—Ni Alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-Ni-B alloy, Fe-Co-B alloy, Fe-Co-Ni-B alloy, etc. And an in-plane magnetization recording metal magnetic thin film and a Co—Cr alloy magnetic thin film.

  In particular, when an in-plane magnetization recording metal magnetic thin film is employed, an underlayer of a low melting point nonmagnetic material such as Bi, Sb, Pb, Sn, Ga, In, Ge, Si, or Tl is previously formed on a nonmagnetic support. In addition, the above metals are vapor-deposited or sputtered from the direction perpendicular to the underlayer, and these low melting point nonmagnetic materials are diffused in the metal magnetic thin film, thereby canceling the orientation and achieving in-plane isotropy. You may make it improve a magnetic resistance while ensuring.

  The magnetic layer 3 formed by depositing a ferromagnetic metal material on a nonmagnetic support by a technique such as vapor deposition is formed by depositing a magnetic material, and since no binder is used in the magnetic layer, It is vulnerable to the sliding operation, and a protective film layer 4 such as a carbon film is provided to compensate for this.

In addition to the carbon film, for example, a silicon oxide (SiO ₂ ) film or a zirconia (ZrO ₂ ) film may be used. The lubricant layer 1 is preferably applied on the carbon film layer 4, but may be applied directly or indirectly on the magnetic layer 3 made of a metal magnetic thin film.

  As a method for forming the carbon film layer 4, sputtering is generally used but is not particularly limited, and any known method such as a CVD (Chemical Vapor Deposition) method using a hydrocarbon gas can be employed. . The film thickness of the carbon film layer 4 is preferably 2 to 100 nm, more preferably 5 to 30 nm. The carbon film may be an amorphous carbon film in which a diamond structure or a graphite structure is mixed, which is called a hard carbon film or diamond-like carbon.

The lubricant layer 1 can be formed by top-coating a lubricant containing the triazole compound of the present invention on the carbon film layer 4 by a conventional method. The coating amount of the lubricant is preferably, for example 0.3~100mg / m ^2, more preferably 0.5-20 / m ^2. For the application, a lubricant dissolved in an organic solvent such as hexane can be used. If this coating amount is too small, the effect of lowering the friction coefficient and improving wear resistance and durability does not appear, while if too much, the sticking phenomenon occurs between the sliding member and the ferromagnetic metal thin film, On the contrary, the running performance becomes worse.

  The lubricant according to the present invention can be applied very thinly on such a protective film, and in this case as well, sufficient lubrication characteristics are exhibited, and a lubricating effect that can withstand long-term use Can last.

  In addition, various additives, for example, a rust preventive agent can also be mix | blended with the said lubricant as needed, for the further improvement of a rust prevention characteristic. In this case, the rust preventive agent may be those used in conventional magnetic recording media, such as phenols, naphthols, quinones, heterocyclic compounds containing nitrogen atoms, and heterocyclic rings containing oxygen atoms. It is also possible to add a compound specialized for the antirust function such as a compound or a heterocyclic compound containing a sulfur atom.

  When using a rust preventive agent, it may be used in combination with a lubricant, but after applying a rust preventive agent on the carbon film layer and then applying a lubricant to provide two or more layers, the rust preventive effect Is preferable.

  FIG. 2 is a schematic cross-sectional view of the coating type magnetic recording medium 15. In this magnetic recording medium 15, a magnetic coating material containing fine magnetic particles and a resin binder is applied on the nonmagnetic support 12, and this is used as the magnetic layer 11.

  In the case of a coating type, an internal addition type in which a predetermined amount of the lubricant is contained in the magnetic layer 11 composed of magnetic powder and a binder may be used. Also, the lubricant layer 13 coated with the lubricant on the surface of the magnetic layer 11 with or without a protective film, as in the thin film type (indicated by a dotted line which is a virtual line in FIG. 2). ) May be formed. When the magnetic layer 11 of the coating type magnetic recording medium 15 contains the lubricant, the content is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the magnetic powder.

The magnetic particles are preferably ferromagnetic powder, and are represented by, for example, γ-Fe ₂ O ₃ , Co-containing γ-Fe ₂ O ₃ , Co-coated γ-Fe ₂ O ₃ , CrO ₂ , and magnetite. Oxide magnetic powders such as ferrites, for example, Fe-Al series, Fe-Al-Ni series, Fe-Al-P series, Fe-Al-Co series, Fe-Al-Zn series, Fe-Ni series Fe, Co, Ni, etc. are mainly used like Fe-Ni-Si-Al-Mn, Fe-Ni-Si-Al-Zn, Fe-Mn-Zn, Ni-Co alloy powders. A metal magnetic powder as a component can be used.

The binder is typically a vinyl resin such as a polyester resin, a polyurethane resin, or a vinyl chloride copolymer. Further, for the purpose of improving the dispersibility of the magnetic powder to the binders resin, these _{resins, -SO 3 M, -OSO 3 M} , -COOM, -PO (OM ') 2 ( where, M is, Na , K, Li and the like, and M ′ is preferably a hydrogen atom, an alkali metal, or an alkyl group.) And at least one polar group selected from a sulfopeteine group as a repeating unit. .

  The magnetic layer 11 made of a binder and magnetic powder may contain known additives such as abrasives, lubricants, curing agents, and antistatic agents.

  The nonmagnetic support 12 used in the above-described metal magnetic thin film type magnetic recording medium and coating type magnetic recording medium can be made of a known material as appropriate, such as polyethylene terephthalate and polyethylene naphthalate. Examples include polyesters, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, aramid resins such as polyaramid, and plastics such as polycarbonate.

  These nonmagnetic supports may have a single layer structure or a multilayer structure. Further, corona discharge treatment or the like may be performed. Furthermore, it can be formed into an arbitrary shape such as a film shape, a sheet shape, a disk shape, or a card shape.

  Further, the backcoat layer 14 may be provided on the surface of the nonmagnetic support 12 on which the magnetic layer 11 is not provided. The back coat layer 14 can be formed according to a normal method.

  FIG. 3 shows a magnetic recording medium 25 in which a magnetic layer 23 made of a ferromagnetic metal thin film, a protective film 24 made of a carbon film, and a lubricant layer 21 are sequentially formed on both surfaces of a disk-shaped flexible nonmagnetic support 22. It is. Also in this case, the magnetic layer 23 can be formed by coating, and a lubricant can be internally added to the magnetic layer 23.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not limited to the following example at all.

  First, the compounds of Examples 1 to 12 shown in Table 1 were synthesized as follows.

Synthesis of Compound of Example 1 11- (perfluorooctyl) undecanoic acid chloride CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₁₀ COCl is used as the acid chloride compound containing Rf group in the general formula (2). Using 1H-benzotriazole-1-methanol as the compound having a triazole skeleton in 2), the triazole compound of Example 1 was synthesized by the following condensation reaction.

  In 500 mL of tetrahydrofuran (THF), 62.3 g (equivalent to 0.1 mol) of 11- (perfluorooctyl) undecanoic acid chloride and 14.9 g (equivalent to 0.1 mol) of 1H-benzotriazole-1-methanol were added. The mixture was heated at reflux for 3 hours to be reacted.

  After completion of the reaction, THF was removed by filtration, and the reaction product was purified by recrystallization. That is, the reaction solution was filtered to separate a solid reaction product from THF, and the reaction product was dissolved in 500 ml of 2-propanol (IPA) heated to 60 ° C., and then insoluble matters were removed by filtration. The filtrate was collected and concentrated. This concentrate was dissolved in 500 mL of n-hexane heated to 60 ° C., and then cooled on ice to precipitate the target product as crystals. The crystals were collected by filtration to obtain a purified target product. The yield was about 50%.

  When the product was analyzed by an infrared light absorption spectrum (IR) method and a liquid chromatography-mass spectrometry (LCMS) method, the results shown in FIGS. 4 and 5 were obtained, respectively. From these, it was found that the product was the target product represented by the following chemical formula.

Synthesis of Compound of Example 11 Triazole in general formula (6) using 11- (perfluorooctyl) undecanol CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₁₁ OH as the alcohol containing Rf group in general formula (6) Using 1,5-dimethyl-1H-1,2,3-triazole-4-carboxylic acid as the compound having a skeleton, the triazole compound of Example 11 was synthesized by the following condensation reaction.

  59.0 g (0.1 mol) of 11- (perfluorooctyl) undecanol and 14.1 g (0.1 mol) of 1,5-dimethyl-1H-1,2,3-triazole-4-carboxylic acid Were mixed in 500 mL of toluene and reacted by refluxing for 3 hours.

  After completion of the reaction, toluene was removed by filtration, and the reaction product was purified by recrystallization. That is, the reaction solution is filtered to separate a solid reaction product from toluene, and the reaction product is dissolved in 500 ml of 2-propanol (IPA) heated to 60 ° C., and then insoluble matter is removed by filtration. The filtrate was collected and concentrated. This concentrate was dissolved in 500 mL of n-hexane heated to 60 ° C., and then cooled on ice to precipitate the target product as crystals. The crystals were collected by filtration to obtain a purified target product. The yield was about 60%.

  The product was analyzed by infrared light absorption spectrum (IR) method and liquid chromatography-mass spectrometry (LCMS) method, and the results shown in FIGS. 6 and 7 were obtained, respectively. From these, it was found that the product was the target product represented by the following chemical formula.

  In the same manner as in the above two examples, the raw material compound having a predetermined group as the Rf group in general formulas (2) to (6) is reacted with the raw material compound having a triazole skeleton, and Examples 2 to 10 are reacted. And 12 triazole compounds could be synthesized. In summary, the reactants used in the synthesis of the compounds of Examples 1 to 12 and the reaction yield are shown in Table 2 below.

  Next, the performance as a lubricant was tested for the triazole compounds of Examples 1 to 12 as follows. Under the present circumstances, the same test was done also about the compound shown in following Table 3 as Comparative Examples 1-7.

Preparation of sample tape and performance test thereof Cobalt was vapor-deposited on a 6.3 μm thick polyethylene terephthalate film to form a magnetic layer made of a metal magnetic thin film having a thickness of 60 nm. Next, a carbon film layer having a thickness of about 10 nm was formed on the magnetic layer using a CVD apparatus.

  Next, a backcoat layer made of carbon and polyurethane resin having a thickness of 0.5 μm was formed on the surface of the polyethylene terephthalate film opposite to the surface on which the magnetic layer was formed.

Subsequently, the compound shown in Table 1 or Table 3 is dissolved in 2-propanol, applied to the surface of the carbon film layer so that the amount of the compound applied is 1 mg / m ^2, and further applied to the surface of the backcoat layer. It apply | coated so that an application quantity might be 3 mg / m < ² >. The obtained magnetic recording medium was cut into a width of 8 mm to obtain a sample tape.

<Evaluation of durability and running performance>
Using each sample tape thus prepared, the coefficient of friction under a temperature of 40 ° C. and a relative humidity of 80% and the shuttle durability under a temperature of −5 ° C. or a temperature of 40 ° C. and a relative humidity of 20% Were measured as follows. The evaluation results are shown in Table 4. In addition, these conditions of a present Example are considered to be the severest use conditions.

(1) Friction coefficient measurement method The friction coefficient is measured by controlling the atmosphere in the thermostatic chamber at a temperature of 40 ° C. and a relative humidity of 80%, and running the sample tape through the friction coefficient measuring instrument 1000 times in the thermostatic chamber. It was measured. In addition, the numerical value after 1000 times driving | running was described in Table 4 as a friction coefficient.
(2) Shuttle durability measurement method Shuttle durability is controlled by controlling the atmosphere in the thermostatic chamber to a temperature of -5 ° C or a temperature of 40 ° C and a relative humidity of 20%. The vehicle was run 100 times in the Play mode, and after 100 times of running, it was measured how much dB the reproduction output dropped from the initial output. For measurement of shuttle durability, a commercially available AIT2 deck (manufactured by Sony Corporation; trade name SDX-S500C) was used.

  Although the lubricating action of the 1,2,3-triazole compounds is unclear, the following characteristics can be pointed out from the results in Table 4.

<< Change due to difference in structure of raw material compound having triazole skeleton >>
Comparing Examples 1, 5 and 11 having one hydrophobic group which is almost equivalent, Example 1 is the best in both coefficient of friction and shuttle durability, and the performance decreases in the order of Examples 5 and 11. I understand. For example, the friction coefficients of Examples 1, 5, and 11 vary as 0.21, 0.23, and 0.25, but the difference in the friction coefficient is almost the same as the difference due to the difference in hydrophobic groups. It can be seen that the selection of the structure of the substrate molecule to which the functional group binds is as important as the selection of the hydrophobic group. However, as can be seen by comparing Example 7 and Example 8 with Example 5 and Example 6, respectively, the effect of substituting the benzene ring of the 1H-benzotriazole skeleton with a nitrogen atom was not recognized. .

  When the substrate molecule is a raw material compound having a 1H-1,2,3-triazole skeleton, unlike the raw material compound having a 1H-benzotriazole skeleton, two hydrophobic groups can be introduced as in Example 9. There are benefits. However, the coefficient of friction of Example 9 is 0.22, which is superior to that of Example 5, but does not reach that of Example 1. The same is true for shuttle durability.

From the above, the raw material compounds having a triazole skeleton are listed in order from the preferred ones as follows.

<< Effectiveness of triazole skeleton >>
In Comparative Example 7 using a compound having a pyrrole skeleton having only one nitrogen atom, although having a 5-membered ring structure similar to the triazole skeleton, the friction coefficient is higher than that of the compound having a triazole skeleton. Yes. A comparison of Example 11 (friction coefficient 0.25) and Comparative Example 7 (0.29) shows that the triazole skeleton provides high lubricating performance. The same is true for shuttle durability.

<< Change due to difference in structure of hydrophobic group >>
When Examples 11 and 12 (and Examples 9 and 10) having the same substrate molecule are compared, the friction coefficients are 0.25 and 0.27 (0.22 and 0.24), and the fluorine atoms are It can be seen that the inclusion contains higher lubricating performance than a simple hydrocarbon group. Further, when Examples 1 and 2 (or Examples 5 and 6 or Examples 7 and 8) are compared, the friction coefficients are 0.21 and 0.24 (or 0.23 and 0.26, or 0. 0). 23 and 0.26), this indicates that a longer carbon chain length of the hydrophobic group is more effective.

  However, comparing the difference in friction coefficient between Example 1 and Example 3 (and 4) with the difference in friction coefficient between Example 1 and Example 2, it is preferable to add fluorine atoms rather than simply adding a long hydrocarbon group. It can be seen that it is more effective to lengthen the carbon chain of the hydrophobic group containing.

<Evaluation of corrosion resistance>
About the lubricant used in Examples 1-12 and Comparative Examples 1-7, the storage reliability with respect to a hot and humid environment and corrosive gas was investigated as follows. The evaluation results are shown in Table 5. The evaluation criteria are ◎ when the magnetization deterioration rate is 1% or less, ◯ when the magnetization deterioration rate is 3% or less, and Δ when it is 5% or less, and × when it is more.

(1) High-temperature and high-humidity environment The sample was put into a tape piece, left in a high-temperature and high-humidity atmosphere environment of 60 ° C. and 80% RH for 1 week, and the magnetization deterioration rate before and after that was measured.
(2) Corrosive gas environment Put the sample in the form of a tape piece and leave it in an atmosphere of 35 ° C, 70% RH, ₂ ppm hydrogen sulfide (H ₂ S), 1 ppm hydrogen chloride (HCl) for 5 hours. We measured the magnetic degradation rate at.

  From the results of Table 5, Examples 1 to 12 based on the present invention all satisfy the conditions for corrosion resistance, but Examples 1 to 9 and 11 using a lubricant containing a fluorine atom exhibit excellent corrosion resistance. I understand. This seems to be related to the fact that the lubricant containing fluorine atoms has high water repellency.

  On the other hand, none of Comparative Examples 1 to 7 satisfies the corrosion resistance condition. As a result, Comparative Example 1 having one amino group in the molecule, Comparative Example 7 having a pyrrole ring having only one nitrogen atom in the molecule, and Comparison having one carboxyl group and one ester bond in the molecule. Example 4, while Comparative Examples 2, 3, 5 and 6 having an ester bond in the molecule cannot impart corrosion resistance to the magnetic recording medium, whereas at least one triazole skeleton and at least one ester bond according to the present invention It has been shown that a triazole-based compound having the above has an advantage capable of imparting sufficient corrosion resistance to a magnetic recording medium.

<Solubility Evaluation in Solvent>
About the lubricant used in Examples 1-12 and Comparative Example 3, the solubility with respect to each solvent of ethanol, acetone, and toluene was investigated. The evaluation was ○ when the material was easily soluble in each solvent and × when the lubricant was insoluble in the solvent. Table 6 shows the results of the solubility evaluation of each lubricant.

  Comparative example 3 selected as a comparative example is a lubricant that showed a relatively good coefficient of friction and shuttle durability among the comparative examples. However, as shown in Table 6, since this lubricant is difficult to dissolve in a hydrocarbon solvent, a fluorinated solvent is essential for application, and there is a problem that the load on the environment during use becomes large.

  From the above results, by using the triazole compound according to the present invention as a lubricant for magnetic recording media, the friction coefficient and shuttle durability are deteriorated even under various use conditions such as high temperature and high humidity, high temperature and low humidity or low temperature. It was found that extremely good results were obtained with respect to storage durability.

  Although the present invention has been described based on the embodiments and examples, it is needless to say that the present invention is not limited to these examples and can be appropriately changed without departing from the gist of the invention. .

  The triazole compound of the present invention is particularly useful as a lubricant for magnetic recording media. In addition, when the triazole compound of the present invention is used as a lubricant for recording media, excellent lubricity is maintained under various use conditions, and the lubrication effect is maintained over a long period of time, resulting in excellent running properties and wear resistance. Thus, a recording medium capable of providing durability, storage stability, and the like is obtained.

1 is a schematic cross-sectional view of a metal thin film type magnetic recording medium according to a preferred embodiment of the present invention. 1 is a schematic cross-sectional view of a coating-type magnetic recording medium according to a preferred embodiment of the present invention. 1 is a schematic cross-sectional view of a disk-shaped magnetic recording medium according to a preferred embodiment of the present invention. It is a graph which shows the infrared-light absorption spectrum of the triazole type compound of Example 1 of this invention. It is a graph which shows the mass spectrometry spectrum of the triazole type compound of Example 1 of this invention. It is a graph which shows the infrared-light absorption spectrum of the triazole type compound of Example 11 of this invention. It is a graph which shows the mass spectrometry spectrum of Example 11 triazole type compound of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lubricant layer, 2 ... Nonmagnetic support body, 3 ... Magnetic layer, 4 ... Carbon film layer,
5 ... Magnetic recording medium, 11 ... Lubricant layer, 12 ... Nonmagnetic support, 13 ... Magnetic layer,
14 ... Backcoat layer, 15 ... Magnetic recording medium, 21 ... Lubricant layer, 22 ... Nonmagnetic support,
23 ... Magnetic layer, 24 ... Protective film, 25 ... Magnetic recording medium

Claims (11)

A lubricant composed of a triazole compound represented by the following general formula (1) and having at least one triazole skeleton and at least one ester bond.
General formula (1):

(In the formula, R ¹ , R ² and R ³ are unsubstituted or substituted, saturated or unsaturated fluorine-containing hydrocarbon group or hydrocarbon group, or a hydrogen atom. And at least one ester bond, provided that R ¹ , R ² and R ³ are not all hydrogen atoms, and R ² and R ³ may form a ring together.) The lubricant according to claim 1, wherein the triazole-based compound is a compound represented by the following general formula (2).
General formula (2):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.) The lubricant according to claim 1, wherein the triazole-based compound is a compound represented by the following general formula (3).
General formula (3):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.) The lubricant according to claim 1, wherein the triazole-based compound is a compound represented by the following general formula (4).
General formula (4):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.) The lubricant according to claim 1, wherein the triazole-based compound is a compound represented by the following general formula (5).
General formula (5):

(In the formula, Rf1 and Rf2 are unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon groups or hydrocarbon groups.) The lubricant according to claim 1, wherein the triazole-based compound is a compound represented by the following general formula (6).
General formula (6):

(In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.)   A lubricant comprising a mixture of a plurality of lubricants selected from the group consisting of the lubricants according to claim 1.   The lubricant according to any one of claims 1 to 7, which is a lubricant for a recording medium.   The lubricant according to claim 8, wherein the recording medium is a magnetic recording medium having a magnetic layer, and is retained on and / or in the magnetic layer.   A recording medium in which the lubricant according to any one of claims 1 to 7 is retained on the recording layer and / or in the recording layer. The recording medium according to claim 10, which is configured as a magnetic recording medium in which the recording layer is a magnetic layer.

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