JP2003300937A - Partially-fluorinated alkyl compound, lubricant made of the compound, and recording medium using the lubricant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant for a recording medium, keeping excellent lubricity in various working conditions, retaining lubricating effects for a long period, and therefore capable of giving excellent traveling performance, abrasion resistance, durability, etc., to the recording medium. <P>SOLUTION: A compound of C<SB>18</SB>H<SB>37</SB>-CH(CH<SB>2</SB>COOC<SB>10</SB>H<SB>6</SB>OH)COORf (Rf is a saturated or unsaturated partially-fluorinated alkyl) is, for example, used as the lubricant for the magnetic recording medium. Thus, the magnetic recording medium having the excellent traveling performance, abrasion resistance, and durability is obtained. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a partially fluorinated alkyl compound, a recording medium lubricant comprising the compound, and a recording medium on which a lubricating layer containing the lubricant is formed.

[0002]

2. Description of the Related Art A conventional recording medium, for example, a magnetic recording medium, is a so-called metal thin film type magnetic recording in which a ferromagnetic metal material is deposited on a non-magnetic support by a method such as vapor deposition and the magnetic layer is used as a magnetic layer. There is known a medium or a so-called coating type magnetic recording medium in which a magnetic coating material containing very fine magnetic particles and a resin binder is coated on a non-magnetic support and used as a magnetic layer. Since these conventional magnetic recording media have extremely good smoothness of the magnetic layer surface, the substantial contact area with a sliding member such as a magnetic head or a guide roller is large,
Therefore, there are many problems such that the friction coefficient becomes large and the adhesion phenomenon (so-called sticking) is likely to occur and running performance and durability are poor. Therefore, it has been studied to use various lubricants in order to improve these problems. Conventionally, higher fatty acids and their esters are internally added to the magnetic layer of the magnetic recording medium, or a top coat is used. Attempts have been made to suppress the friction coefficient by doing so.

However, the lubricant used for the magnetic recording medium is required to have very strict characteristics due to its properties.
At present, it is difficult to satisfy the requirement with the lubricants used conventionally.

That is, the lubricant used in the magnetic recording medium is (1) excellent in low temperature characteristics so as to ensure a predetermined lubricating effect when used in cold regions, and (2) a lubricant with a magnetic head. As pacing becomes a problem, it is necessary to be able to apply it extremely thinly, to exhibit sufficient lubrication characteristics even in that case, and (3) to endure long-term use or long-term use and to maintain the lubrication effect. To be done.

Incidentally, Japanese Patent Laid-Open No. 6-41561 discloses that
As a lubricant for a metal thin film type magnetic recording medium, a fluorine-containing alkyl succinic acid diester represented by the following general formula (i) has been proposed.

[0006]

[Chemical 4]

In the formula, R1 is an aliphatic alkyl group or an aliphatic alkenyl group, one of R2 and R3 is a fluoroalkyl ether group, and the other is a fluoroalkyl group,
It is either a fluoroalkenyl group, a fluorophenyl group, an aliphatic alkyl group, or an aliphatic alkenyl group. But,
The above-mentioned fluorine-containing alkyl succinate diester has a problem that it has a large friction coefficient.

[0008]

As described above, in the field of recording media, due to the lack of the ability of the lubricant used, for example, the reproduction output is lowered in the shuttle running test, and the practical characteristics are not achieved. I am dissatisfied. Therefore, the present invention, while maintaining excellent lubricity under various use conditions, the lubricating effect is maintained for a long time,
An object of the present invention is to provide a compound capable of providing excellent running property, abrasion resistance, durability, etc., a lubricant comprising the compound, and a recording medium.

[0009]

That is, the present invention provides the following general formula (1):

[0010]

[Chemical 5]

(In the formula, R represents a saturated or unsaturated aliphatic hydrocarbon group having 6 to 30 carbon atoms, Rf represents a saturated or unsaturated fluoroalkyl group or a hydrocarbon group, and X represents an aromatic group. A ring or a heterocyclic group, or an aromatic ring or a heterocyclic group substituted with a hydroxyl group, an amino group, a carboxylic acid group, a halogen atom, a hydrocarbon group, an aromatic ring, or an aromatic ring or a heterocyclic group And a partially fluorinated alkyl-based compound represented by the formula (1). The present invention also has the following general formula (1):

[0012]

[Chemical 6]

(Wherein R represents a saturated or unsaturated aliphatic hydrocarbon group having 6 to 30 carbon atoms, Rf represents a saturated or unsaturated fluoroalkyl group or a hydrocarbon group, and X represents an aromatic group. A ring or a heterocyclic group, or an aromatic ring or a heterocyclic group substituted with a hydroxyl group, an amino group, a carboxylic acid group, a halogen atom, a hydrocarbon group, an aromatic ring, or an aromatic ring or a heterocyclic group The present invention provides a lubricant for recording media, which comprises a partially fluorinated alkyl-based compound represented by a hydrocarbon group. Furthermore, the present invention is a recording medium in which a recording layer and a lubricant layer made of a lubricant are formed at least in sequence on a support, and the lubricant has the following general formula (1):

[0014]

[Chemical 7]

(Wherein R represents a saturated or unsaturated aliphatic hydrocarbon group having 6 to 30 carbon atoms, Rf represents a saturated or unsaturated fluoroalkyl group or a hydrocarbon group, and X represents an aromatic group. A ring or a heterocyclic group, or an aromatic ring or a heterocyclic group substituted with a hydroxyl group, an amino group, a carboxylic acid group, a halogen atom, a hydrocarbon group, an aromatic ring, or an aromatic ring or a heterocyclic group The present invention provides a recording medium containing a partially fluorinated alkyl compound represented by a hydrocarbon group.

The partially fluorinated alkyl compound of the present invention is a novel substance, and when used as a lubricant for recording media, especially for magnetic recording media, excellent lubricity is maintained under various usage conditions. Thus, it is possible to provide a recording medium in which the lubrication effect is maintained for a long time and which has excellent running properties, abrasion resistance, durability and the like.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the case where the compound of the present invention is used as a lubricant for a magnetic recording medium will be described as an example.

In the partially fluorinated alkyl compound of the present invention, R has 6 to 30 carbon atoms, preferably 8 to 20 carbon atoms.
Is a saturated or unsaturated aliphatic hydrocarbon group. When the carbon number of R is less than 6 or more than 30, the solubility in an organic solvent decreases, and it becomes impossible to form a lubricating layer film on the carbon film layer using the organic solvent.

The partially fluorinated alkyl compound of the present invention is
For example, it can be obtained as follows. First, a succinic acid derivative containing an R group in the general formula (1) and an alcohol compound containing a fluoroalkyl group (Rf) in the general formula (1) are mixed, heated at 120 ° C., and reacted to produce an organic solvent. Alternatively, a partially fluorinated alkyl monoester monocarboxylic acid compound is obtained by removing impurities and unwanted substances by washing with an inorganic solvent, washing with a separating funnel, washing with a column chromatography, and the like. . Next, the obtained partially fluorinated alkyl monoester monocarboxylic acid compound and the hydroxyl compound containing the X group in the general formula (1) are combined with the carboxylic acid group of the partially fluorinated alkyl monoester monocarboxylic acid compound. It can be synthesized by subjecting one to an esterification reaction such that hydroxyl group 1 of the X-containing hydroxyl compound reacts to form an ester bond, and then purifying. In the esterification reaction, the carboxylic acid group of the partially fluorinated alkyl monoester monocarboxylic acid compound is previously treated with thionyl chloride or the like to form an acid chloride,
Then, a method of reacting with the hydroxyl group of the X group-containing hydroxyl compound can be used.

Further, as described above, the partially fluorinated alkyl compound of the present invention can be suitably used as a lubricant for recording media, especially magnetic recording media. If necessary, various additives such as a rust preventive may be added to the lubricant. The rust preventive agent may be one used in conventional magnetic recording media, for example, phenols, naphthols, quinones, heterocyclic compounds containing nitrogen atom, heterocyclic compounds containing oxygen atom, sulfur. Examples thereof include heterocyclic compounds containing atoms.

The recording medium of the present invention comprises a lubricant layer containing the above-mentioned lubricant. For example, in the case of a magnetic recording medium, specifically, it is formed on a non-magnetic support by a method such as vapor deposition. A magnetic recording medium of a so-called metal thin film type in which a magnetic layer formed of the formed metal magnetic thin film, a carbon film layer, and a lubricant layer containing the partially fluorinated alkyl compound of the present invention are formed at least sequentially . Also,
If necessary, an underlayer may be formed between the non-magnetic support and the magnetic layer.

The non-magnetic support is not particularly limited, and a known one can be used. For example,
When a rigid substrate such as an Al alloy plate or a glass plate is used as the non-magnetic support, an oxide film such as alumite treatment or Ni-P film is formed on the substrate surface to harden the surface. May be.

The metal magnetic thin film forming the magnetic layer is not particularly limited, and known ones can be adopted. For example, it is formed as a continuous film by a method such as plating, sputtering, or vacuum evaporation.
e, Co, Ni and other metals, Co-Ni alloys, Co-P
t-based alloy, Co-Pt-Ni-based alloy, Fe-Co-based alloy, Fe-Ni-based alloy, Fe-Co-Ni-based alloy, Fe
-Ni-B system alloy, Fe-Co-B system alloy, Fe-Co
Examples include in-plane magnetization recording metal magnetic thin films made of -Ni-B type alloys and Co-Cr type alloy magnetic thin films. In particular, when an in-plane magnetization recording metal magnetic thin film is adopted, Bi, Sb, Pb, Sn, Ga, In, and
An underlayer of a low-melting point nonmagnetic material such as Ge, Si, or Tl is formed, and the above-mentioned metals are vapor-deposited or sputtered on the underlayer in a direction perpendicular to the underlayer, and these low-melting point nonmagnetic materials are formed in the metal magnetic thin film. The material may be diffused to eliminate the orientation, thereby ensuring the in-plane isotropic property and improving the anti-magnetism.

As a method for forming the carbon film layer, sputtering is generally used, but the method is not particularly limited, and any known method can be adopted. The thickness of the carbon film is preferably 2 to 100 nm, more preferably 5 to 30 nm.

The lubricant layer can be formed by topcoating the carbon film layer with a lubricant containing the partially fluorinated alkyl compound of the present invention by a conventional method. The coating amount of the lubricant, for example, preferably 0.5 to 100 mg / m ^2, more preferably 1 to 20 mg / m ^2. For application, a lubricant dissolved in an organic solvent such as hexane can be used. When a rust preventive agent is used, it may be used in combination with a lubricant, but if a rust preventive agent is applied on the carbon film layer and then a lubricant is applied to provide two or more layers, the rust preventive agent can be used. This is preferable because it enhances the rust effect.

The partially fluorinated alkyl compound of the present invention is
As described above, it is preferably used as a lubricant for recording media, especially magnetic recording media. However, the lubricant of the present invention can be applied not only to magnetic recording media but also to optical recording media, and its support is not limited to tapes and can be used for recording media such as disk media such as magnetic disks and optical disks. .

[0027]

In the conventional lubricant, a compound having a relatively large polarity such as a carboxylic acid, an amine or a carboxylic acid amine salt has a small friction coefficient but tends to have a poor still durability. A compound having a small polarity is excellent in still durability, but has a large friction coefficient.
Since the partially fluorinated alkyl compound of the present invention has an aromatic ring or a heterocyclic group and two ester groups as the terminal polar group, it exhibits a small friction coefficient and excellent still durability. In particular, when the partially fluorinated alkyl compound of the present invention is applied as a lubricant onto a carbon film layer, an aromatic ring or a heterocyclic group of the general formula (1), which is a polar base portion of a lubricant molecule, and two The ester group is adsorbed, and the cohesive force between the hydrophobic groups makes it possible to form a lubricant layer having good durability. Further, while a fluorine-based solvent is essential for applying a conventional fluorine-containing lubricant,
Since the partially fluorinated alkyl compound of the present invention can be applied using a hydrocarbon solvent such as toluene or acetone, it is preferable because the load on the environment is small. As described above, the magnetic recording medium using the partially fluorinated alkyl compound of the present invention as a lubricant maintains excellent lubricity under various conditions of use, has a long-lasting lubricating effect, and is excellent in running performance. The wear resistance, wear resistance, durability, etc. can be provided.

[0028]

EXAMPLES The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Synthesis Example 1 (C ₁₈ H ₃₇ -CH (CH ₂ COOC ₁₀ H ₆ OH) COO
Synthesis of (CH ₂ ) ₂ (CF ₂ ) ₈ F) Using octadecyl succinic anhydride as the succinic acid derivative containing the R group in the general formula (1), the partial fluoroalkyl group (Rf) in the general formula (1) is used. Fluorinated alcohol F (CF ₂ ) ₈ CH ₂ CH ₂ OH is used as the alcohol compound to be contained, and 2, as the X group-containing hydroxyl compound in the general formula (1),
The partially fluorinated alkyl compound of the present invention was synthesized using 3-naphthalene diol C ₁₀ H ₆ (OH) ₂ . The synthetic procedure is shown below. Octadecyl succinic anhydride C ₁₈ H ₃₇
17.7 g of C ₄ H ₃ O ₃ and fluorinated alcohol F (CF ₂ ).
23.2 g of ₈ CH ₂ CH ₂ OH was mixed and the mixture was mixed for 3 hours and
Refluxed at 0 ° C. After completion of the reaction, the reaction product was dissolved in 200 ml of toluene, 300 ml of 10% NaOH aqueous solution was added, and the mixture was vigorously shaken. Formed white solid (Na
The salt) was suction filtered with a glass filter. 240m of water
The white solid was washed twice with 1 and once with 200 ml of toluene on a glass filter. By this operation, the starting material octadecyl succinic anhydride could be removed. Next, the white solid was put into a separating funnel, and 300 ml of toluene, 7.2
% HCl (300 ml) was added for liquid separation washing and desalting. Furthermore, 300 ml of 7.2% HCl was added twice, and an aqueous solution of sodium chloride was added twice to carry out liquid separation and washing, and the toluene phase was recovered and dried over magnesium sulfate. After 1 hour, it was filtered and the toluene phase was concentrated. Subsequently, the recovered product was purified by column chromatography. Column conditions are column packing:
Silica gel, column temperature: room temperature, eluent: ethyl acetate 3
It is a mixed solvent of 0% toluene and 70%. The target substance is eluted when a mixed solvent of ethyl acetate 30% and toluene 70% is used. IR analysis of the recovered material revealed that it had a general formula of C ₁₈ H _{37
-CH (CH 2 COOH) COO (} CH 2) 2 (CF 2) 8
It was found to have F.

Further, purified C ₁₈ H ₃₇ -CH (CH ₂
5.0 g of thionyl chloride was added to 33 g of (COOH) COO (CH ₂ ) ₂ (CF ₂ ) ₈ F, and the mixture was refluxed at 50 ° C. for 2 hours. After completion of the reaction, the reaction product was concentrated and the target product was recovered.
IR analysis of the recovered material revealed that it had a general formula of C ₁₈ H ₃₇ -CH.
It was found to have (CH ₂ COCl) COO (CH ₂ ) ₂ (CF ₂ ) ₈ F.

Next, purified C₁₈H₃₇-CH (CH₂C
OCl) COO (CH₂)₂(CF₂) ₈2,3-naphtha on F
Rendiol C_TenH₆(OH)₂6.5g was added at 2:00
The mixture was refluxed at 100 ° C for a while. After the reaction, toluene 200
Dissolve the reaction product in ml and add 10% Na in a separating funnel.
2 times with 300 ml of OH aqueous solution
Separation and washing were performed twice, and the toluene phase was recovered and washed with magnesium sulfate.
Dried with um. After 1 hour, filter and concentrate the toluene phase.
Contracted. Then, collect by column chromatography
The product was purified. Column condition is column packing: silica gel
Column temperature: room temperature, eluent: toluene. Purpose
The substance elutes when toluene is used. 34g collected
And the recovery rate was about 70%. IR analysis of the recovered material
When the general formula (C₁₈H₃₇-CH (CH₂COOC_Ten
H₆OH) COO (CH₂)₂(CF₂)₈F synthesis)
It turned out to be.

Synthesis Example 2 (C₁₈H₃₇-CH (CH₂COO
C_TenH₇) COO (CH₂)₂(CF₂)₈Synthesis of F) In the same manner as in Synthesis Example 1, the general formula C₁₈H₃₇-CH (C
H₂COCl) COO (CH₂)₂(CF₂)₈Have F
The acid chloride was synthesized. Next, purified C₁₈H₃₇-CH
(CH₂COCl) COO (CH₂)₂(CF₂) ₈1 to F
Naphthol C_TenH₇Add 5.9g of OH, 2 hours, 10
Refluxed at 0 ° C. After completion of the reaction, reconstitute with 200 ml of toluene.
Dissolve the reaction product, and use 10% NaOH water in a separating funnel.
300 ml of solution twice, sodium chloride aqueous solution twice,
After separation and washing, the toluene phase is recovered and washed with magnesium sulfate.
Dried. After 1 hour, filter and concentrate the toluene phase
It was Then, collect the collected product by column chromatography.
Purified. Column conditions are column packing: silica gel,
Column temperature: room temperature, eluent: toluene. The target is
Elute when using toluene. 34 g of recovered material
The recovery rate was about 70%. IR analysis of the recovered material
Roller, general formula C₁₈H₃₇-CH (CH₂COOC_TenH₇) C
OO (CH₂)₂(CF₂)₈It was found to have F.

If the same method as described above is adopted, the R group, the partial fluoroalkyl group (Rf) and the X group in the general formula (1) are arbitrarily set to synthesize the partially fluorinated alkyl compound of the present invention. can do. Specific examples thereof are shown in Table 1 below.

[0034]

[Table 1]

Examples 1 to 27 Partially fluorinated alkyl compounds of the present invention having the structures shown in Table 2 below were synthesized by the same procedure as in the above-mentioned synthesis example, and used as lubricants in the following tests.

[0036]

[Table 2]

Comparative Examples 1 to 5 The compounds having the structures shown in Table 3 below were used as lubricants in the following tests.

[0038]

[Table 3]

Preparation of Sample Tape Co was vapor-deposited on a polyethylene terephthalate film having a thickness of 7.0 μm to form a magnetic layer made of a metal magnetic thin film having a thickness of 180 nm. Next, a carbon film layer having a thickness of about 8 nm was formed on the magnetic layer using a magnetron sputtering device. Next, a 0.5 μm thick back coat layer made of carbon and polyurethane resin was formed on the surface of the polyethylene terephthalate film opposite to the surface on which the magnetic layer was formed. Subsequently, the compounds shown in Table 2 or Table 3 were dissolved in toluene and applied on the surface of the carbon film layer so that the application amount of the compound was 5 mg / m ² . The obtained magnetic recording medium is 6.35 mm
The sample tape was cut into widths.

Evaluation of Durability and Runnability Using each sample tape prepared as described above,
Friction coefficient under conditions of temperature 40 ° C and relative humidity 80%, still durability under conditions of temperature 5 ° C, temperature 40 ° C, relative humidity 2
The shuttle durability was measured under the condition of 0%. The results are shown in Table 4. It should be noted that these conditions in this example are considered to be the most severe usage conditions. A commercially available digital video camcorder (VX1000 manufactured by Sony Corporation) was used for measuring the still durability and the shuttle durability.

(1) Friction coefficient measuring method The friction coefficient was measured at a temperature of 40 ° C. and a relative humidity of 8 in a constant temperature bath.
Control the sample tape to 0% and set the sample tape to 1
The measurement was carried out by running 00 times. In addition, the numerical value after running 100 times is shown in the table as a friction coefficient. (2) Still durability measurement method Still durability was measured in a constant temperature bath at 5 ° C, and the reproduction output was 3
The time until it dropped by dB was measured. (3) Shuttle durability measurement method Shuttle durability is measured in a thermostatic chamber at a temperature of 40 ° C and a relative humidity of 20.
%, The 60-minute length of the sample tape was run 100 times in the Play mode, and how many dB the playback output dropped from the initial output after running 100 times was measured.

Evaluation of Solubility in Solvents The lubricants used in Examples 1 to 27 and Comparative Example 3 were examined for solubility in ethanol, acetone and toluene. The evaluation was evaluated as ◯ when it was easily soluble in each solvent, and as x when the lubricant was insoluble in the solvent. Table 5 shows the results of the solubility evaluation of each lubricant.

[0043]

[Table 4]

[0044]

[Table 5]

From the above results, by using the partially fluorinated alkyl compound of the present invention as a lubricant for magnetic recording media, the friction coefficient and the still durability under various use conditions such as high temperature and high humidity, high temperature and low humidity, and low temperature. It can be seen that there is very little deterioration in durability or shuttle durability, and very good results are obtained.

[0046]

INDUSTRIAL APPLICABILITY The partially fluorinated alkyl compound of the present invention is particularly useful as a lubricant for magnetic recording media.
Further, by using the partially fluorinated alkyl compound of the present invention as a lubricant for a recording medium, while maintaining excellent lubricity under various use conditions, the lubricating effect is maintained for a long time, and excellent running property, A recording medium capable of providing abrasion resistance, durability and the like can be obtained.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) // C10N 30:00 C10N 30:00 Z 30:06 30:06 40:18 40:18 (72) Inventor Kenichi Kurihara 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Soni Corporation (72) Inventor Hiroshi Iwamoto Tokyo, 6-35, Kita-Shinagawa, Shinagawa-ku, Sony Corporation (72) Inventor Toshinori Tsuboi Tokyo 6-7-35 Kita-Shinagawa, Shinagawa-ku F-term in Sony Corporation (reference) 4C055 AA01 BA01 CA01 DA43 DB02 DB11 4H006 AA01 AB60 BJ50 BM10 BM71 BN30 KA14 4H104 BD07A BE27A LA03 LA20 PA16 5D006 AA01

Claims (4)

[Claims] 1. The following general formula (1): (In the formula, R represents a saturated or unsaturated aliphatic hydrocarbon group having 6 to 30 carbon atoms, Rf represents a saturated or unsaturated fluoroalkyl group or a hydrocarbon group, and X represents an aromatic ring or a heterocyclic group. Ring group, or hydroxyl group, amino group,
It represents a carboxylic acid group, a halogen atom, a hydrocarbon group, an aromatic ring or a heterocyclic group substituted with an aromatic ring, or a hydrocarbon group substituted with an aromatic ring or a heterocyclic group. ) A partially fluorinated alkyl compound. 2. The following general formula (1): (In the formula, R represents a saturated or unsaturated aliphatic hydrocarbon group having 6 to 30 carbon atoms, Rf represents a saturated or unsaturated fluoroalkyl group or a hydrocarbon group, and X represents an aromatic ring or a heterocyclic group. Ring group, or hydroxyl group, amino group,
It represents a carboxylic acid group, a halogen atom, a hydrocarbon group, an aromatic ring or a heterocyclic group substituted with an aromatic ring, or a hydrocarbon group substituted with an aromatic ring or a heterocyclic group. And a partially fluorinated alkyl compound represented by the formula (1). 3. A recording medium in which a recording layer and a lubricant layer made of a lubricant are at least sequentially formed on a support, wherein the lubricant has the following general formula (1): (In the formula, R represents a saturated or unsaturated aliphatic hydrocarbon group having 6 to 30 carbon atoms, Rf represents a saturated or unsaturated fluoroalkyl group or a hydrocarbon group, and X represents an aromatic ring or a heterocyclic group. Ring group, or hydroxyl group, amino group,
It represents a carboxylic acid group, a halogen atom, a hydrocarbon group, an aromatic ring or a heterocyclic group substituted with an aromatic ring, or a hydrocarbon group substituted with an aromatic ring or a heterocyclic group. ) A recording medium comprising a partially fluorinated alkyl compound represented by 4. The recording medium according to claim 3, wherein the recording layer is a magnetic layer, and the recording medium is a magnetic recording medium.