WO2007105437A1

WO2007105437A1 - Lubricating agent for recording medium and magnetic disk

Info

Publication number: WO2007105437A1
Application number: PCT/JP2007/053188
Authority: WO
Inventors: Akinobu Wakabayashi; Yasuo Sakane
Original assignee: Matsumura Oil Research Corp.
Priority date: 2006-02-28
Filing date: 2007-02-21
Publication date: 2007-09-20

Abstract

Disclosed is a lubricating agent for recording media which is hardly decomposed, and firmly adheres to a recording medium by an UV treatment. Also disclosed is a magnetic disk which is capable of withstanding continuous sliding at high speed rotation. Specifically disclosed is a lubricating agent for recording media which contains a perfluoropolyether compound represented by the following formula (1). F(CF2CF2CF2O)m-CF2CF2CH2-R1 (1) [In the formula, R1 represents a group represented by: [Chemical formula 1] (wherein R represents a C1-4 fluoroalkyl group); and m represents a number of 2-60.] Also specifically disclosed is a magnetic disk provided with a lubricating layer which is composed of such a lubricating agent.

Description

Specification

Lubricant for recording medium and magnetic disk

Technical field

The present invention relates to a lubricant for a recording medium such as a magnetic disk and a magnetic tape, and a magnetic disk in which a lubricant layer is formed using the lubricant.

Background art

[0002] Perfluoropolyether compounds are generally used as lubricants for magnetic disks, and in particular, Fomblin compounds made of solbaine having low surface energy and low frictional force. Has become the mainstream. Fomblin compounds are perfluoropolyether compounds having a basic skeleton force S (CF CF 3 O) (CF 2 O) of the main chain.

2 2 m 2 n

[0003] However, it is known that fomblin compounds react with alumina (Al 2 O 3) contained in the head slider member to cause cleavage of the main chain (Macromolecules, 1

twenty three

992, 25 卷, p. 6791-6799). As this cutting force progresses, it has the disadvantage that the neoprenoic opening positive compound becomes low molecular and eventually volatilizes from the magnetic disk.

[0004] On the other hand, the drive system of the magnetic disk drive has a contact 'start' stop (CSS) system in which the head and the disk come into contact with each other when the device starts and stops. There is a ramp 'load' unload (LZUL) method, and the required characteristics for the lubricant differ depending on the method.

In recent years, there has been a demand for higher recording density and higher speed processing of disk devices. Correspondingly, the distance (flying height) between the head and the disk is reduced, and the rotation of the disk is increased at high speed. There is a need. Basically, even in the LZUL system where the head and disk do not contact, the contact frequency between the head and the disk increases with the low flying height and the high speed, and the lubricant moves the disk surface force to the head. Splashes out of the plane. As a result, the disc may be damaged. Therefore, it is desirable that the lubricant has a strong adhesion to the disc surface. Such lubricants widely used include fomblin perfluoropolyether compounds having a plurality of polar groups in the molecule (for example, “fomblin Z-Tetraol ”), but this lubricant has not solved the problem of decomposition by alumina.

[0006] On the other hand, the end of the fomblin perfluoropolyether skeleton is used as a compound that suppresses the decomposition reaction by alumina despite having a fomblin perfluoropolyether chain in the molecule. Compounds with modified phosphazene functional groups are known

(US Pat. No. 6608009, US Pat. No. 6,605,335). These compounds are inhibited from being decomposed by alumina due to the effect of the modified phosphazene functional group. In addition, it has excellent CSS resistance with high compatibility with other perfluoropolyether compounds. However, the adhesion to the disk surface is low, and it is insufficient as a lubricant for LZUL.

[0007] In order to achieve high-speed recording of information recording and Z playback, the rotational speed of the magnetic disk is expected to become more than 7, OOOrpm in the near future even in a small drive. As the rotational speed of the magnetic disk increases, the amount of lubricant scattered tends to increase. In addition, if the slider slides for a long time while rotating at a high speed, the lubricating layer becomes thinner due to decomposition, and eventually the magnetic disk is destroyed. In order to ensure the reliability of the magnetic disk drive, a lubricant that has strong adhesion to the magnetic disk and is difficult to disassemble is required.

[0008] Conventionally, heat treatment has been employed to firmly adhere the lubricant applied to the magnetic disk, but in recent years, UV (ultraviolet) treatment has begun to be studied. Since UV treatment has the advantage that there is no problem such as deterioration of the magnetic layer due to heat treatment that takes less time than heat treatment, future development is expected. However, conventional lubricants did not show excellent adhesion by UV treatment.

Disclosure of the invention

Problems to be solved by the invention

An object of the present invention is to provide a lubricant for a recording medium that adheres firmly to the recording medium by UV treatment and is not easily decomposed.

Means for solving the problem

[0010] The present invention provides a lubricant for a recording medium and a magnetic disk as described below. [0011] 1. Formula (1);

F (CF CF CF O) -CF CF CH

2 2 2 m 2 2:

[Where R ¹ is

[0012] [Chemical 1]

[0013] This represents the same fluoroalkyl group. ) And m is 2

1 -4 to 60 are shown. ] The lubricant for recording media containing the perfluoropolyether compound represented by this.

[0014] 2. A magnetic disk in which a recording layer and a protective layer are formed in this order on a support, and a lubricating layer made of the lubricant according to item 1 is formed on the surface of the protective layer.

[0015] Hereinafter, the present invention will be described in detail.

[0016] The perfluoropolyether compound contained in the recording medium lubricant of the present invention has the formula (1);

F (CF CF CF O) -CF CF CH-R ¹ (1)

2 2 2 m 2 2 2

[Where R ¹ is

[0017] [Chemical 2]

N N

—— O-fj- ~ H. (C ₆ H ₄ ) R] ₅

ヽ N

[0018] This represents the same fluoroalkyl group. ), M represents 2-60. ] And

14

It has a cyclotriphosphazene functional group at one end of one fluoropolyether chain. This perfluoropolyether compound has a property of strongly adhering to a substrate disk by UV treatment.

[0019] The fluoralkyl group is more preferably a trifluoromethyl group, preferably a perfluoroalkyl group. As m, 10-25 are preferable.

[0020] The recording medium lubricant of the present invention is produced, for example, as follows.

[0021] m-trifluoromethylphenol, cyclophosphazene, metallic sodium and general-purpose solution Mix the medium (eg, diisopropyl ether) and stir at 70 ° C. for 48 hours. After completion of the reaction, the mixture is extracted with a solvent, and the solvent of the extract is distilled off to obtain a viscous liquid (pentatrifluoromethylphenoxyphosphazene). Then F (CF CF CF O) -CF CF C

2 2 2 m 2 2

H 2 —OH [wherein m represents 2 to 60. ] Perfluoropolyether compound represented by

2

Mix the viscous liquid obtained above (pentatrifluoromethylphenoxyphosphazene), sodium metal and a fluorine-based solvent (for example, “Eftronic FT-2” manufactured by Eftron Co., Ltd.) at 80 ° Stir at C for 48 hours. After completion of the reaction, extraction is performed with a fluorocarbon solvent, and the solvent is removed by distillation to obtain a viscous liquid (recording medium lubricant).

[0022] Production raw material F (CF CF CF O)-CF CF CH -OH 〕so

2 2 2 m 2 2 2

As the perfluoropolyether compound represented, “Demnum SA” manufactured by Daikin Industries, Ltd. may be mentioned. The m of this perfluoropolyether compound is preferably 10-25. Number average molecular weight 【It is about 500-10000, and it is about 2000-4000.

[0023] The use of the recording medium lubricant of the present invention includes use as a lubricant for improving the sliding characteristics of a magnetic disk in a magnetic disk device. The purpose of this is to reduce the coefficient of friction between the magnetic disk and the head, and therefore, as a lubricant in other recording devices in which sliding occurs between the recording medium such as magnetic tape and the head in addition to the magnetic disk. Can also be used. Further, it can be used as a surface coating agent for a magnetic head. In addition to the recording device, it may be used as a lubricant for equipment having a sliding part. Furthermore, since the lubricant of the present invention exhibits excellent adhesion to the protective layer of the substrate disk by UV treatment, a carbon protective film used as the protective layer, Si N, SiC

3 4

The use of a material such as SiO as a lubricant is also conceivable.

2

[0024] It should be noted that the lubricant of the present invention also exhibits the effect of suppressing the decomposition of the fomblin perfluoropolyether compound, and therefore can be used in combination with the fomblin lubricant. It can also be used in combination with non-fomblin lubricants (for example, “Demnam SA” manufactured by Daikin Industries, Ltd., “Crite Tutus 157FS” manufactured by DuPont, etc.).

In the magnetic disk of the present invention, a recording layer and a protective layer are formed in this order on a support, and a lubricating layer made of the above-described recording medium lubricant is formed on the surface of the protective layer. FIG. 1 shows an outline of the configuration (cross section) of an example of the magnetic disk of the present invention.

In FIG. 1, the magnetic disk of the present invention has a recording layer 2 on a support 1, a protective layer 3 on the recording layer 2, and a lubricant for the above-described lubricant for the recording medium. Layer 4 is the outermost layer.

[0028] Examples of the material of the support 1 include aluminum alloy, glass, and polycarbonate. Examples of the material of the recording layer 2 include alloys in which chromium, platinum, tantalum and the like are included in an element capable of forming a ferromagnetic material such as iron, cobalt, and nickel, or oxides thereof. These are formed by a plating method, a sputtering method or the like. Examples of the material for the protective layer 3 include diamond-like carbon, SiN, SiC, and SiO. These include sputtering, CVD, etc.

3 4 2

Formed with.

The lubricating layer 4 is usually formed by a dipping method using the recording medium lubricant of the present invention dissolved in a solvent and using this solution. As the solvent, a solvent capable of dissolving the recording medium lubricant of the present invention is used. Specifically, fluorocarbon solvents (for example, “PF-5060”, “PF-5080”, “HFE-7100”, “HFE-7200” manufactured by Sumitomo 3EM, “Bertrel XF” manufactured by DuPont) Etc.

[0030] In order to firmly adhere the lubricating layer 4 to the protective layer 3, UV treatment is performed. This UV treatment is performed by irradiating ultraviolet light having a wavelength of around 185 nm.

The invention's effect

[0031] The recording medium lubricant of the present invention contains a perfluoropolyether compound in which a fluoralkylphenoxyphosphazene functional group is introduced at one end of a demnam perfluoropolyether chain. Since this phosphazene functional group functions as a Lewis base, it has excellent decomposition resistance. In addition, since the terminal fluoroalkylphenoxyphosphazene functional group of the perfluoropolyether compound adheres strongly to the recording medium by UV treatment, scattering is reduced. A magnetic disk having a lubricating layer formed using the recording medium lubricant of the present invention can withstand continuous sliding under high-speed rotation, and a magnetic disk drive equipped with the magnetic disk can perform at high speed. Recording Z playback becomes possible.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view showing an example of a magnetic disk of the present invention. FIG. 2 is a diagram showing the lubrication characteristics of a magnetic disk.

Explanation of symbols

[0033] 1 Support

2 Recording layer

3 Protective layer

4 Lubrication layer

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail with reference to examples.

[0035] Example 1

Under argon atmosphere, 61.5 g (379 mmol) of m-trifluoromethylphenol, 18.4 g (53 mmol) of cyclophosphazene, 7.9 g (344 mmol) of sodium metal and 339 ml of diisopropyl ether were mixed at 70 ° C for 48 hours. Stir. After completion of the reaction, diisopropyl ether was added to the reaction solution and extracted, and diisopropyl ether was distilled off from the extract to obtain a viscous liquid 54.lg (pentatrifluoromethylphenoxyphosphazene: 2 3mmol) _Q obtained

Next, under an argon atmosphere, “Demnum SA-2000” 50.0 g (23 mmol) manufactured by Daikin Industries, Ltd., 54. lg (pentatrifluoromethylphenoxyphore) of the viscous liquid obtained above. Sphazen: 23 mmol), 0.52 g (23 mmol) of sodium metal, and 180 ml of “Eftronic FT-2” manufactured by Eftron Co., Ltd. were mixed and stirred at 80 ° C. for 48 hours. After stopping the reaction with 3% nitric acid aqueous solution, DuPont “Bertrel XF” was added to the reaction solution for extraction. Unreacted pentatrifluoromethylphenoxyphosphazene is removed from the extract by washing with toluene, and “Bertrel?” Is distilled off by distillation to give a viscous liquid (lubricant for recording media) 35.4 g Got.

[0037] The resulting viscous liquid was subjected to ¹⁹ F-NMR analysis, and the number average molecular weight was calculated. The number average molecular weight was 3488.

[0038] The results of ¹⁹ F-NMR analysis are shown below.

¹⁹ F—NMR (Solvent: none. Reference material: —OCF CF CF O— in the product—129.7 ppm

2 2 2

It was. ): δ = -64. 0 to 1 62. Oppm

[2F, RHCF CF CH -Ο-Ρ Ν-(OC Η CF)]]

2 2 3 3 6 4 "3 5

δ = -83. O 82. Oppm

[3F, CF CF CF 0 (CF CF CF O) CF CF CH O-PN]

3 2 2 2 2

δ = 84. 0- 83.5 ppm

[4F, CF CF CF 0 (CF CF CF O) CF CF CH O-PN]

3 2 2 2 2 2]

δ = -85. 0 to 1 84.5 ppm

[2F, CF CF CF 0 (CF CF CF O) CF CF CH O-PN]

3 2 2 2 2 2]

δ = -86. 0 to 1 85.5 ppm

[2F, CF CF CF 0 (CF CF CF O) CF CF CH O-PN]

3 2 2 2 2 2]

δ =-125. 0 to 1 123. Oppm

[2F, CF CF CF 0 (CF CF CF O) CF CF CH O-PN]

3 2 2 2 2 2]

δ = -129.0 to 1130.5ppm

[2F, CF CF CF 0 (CF CF CF O) CF CF CH O-PN]

3 2 2 2 2 2]

δ =-130. 6 to 1 131. Oppm

[2F, CF CF CF 0 (CF CF CF O) CF CF CH O-PN] (

― 2 2 2

[0039] The viscous liquid (lubricant) obtained in Example 1 was subjected to a decomposition resistance test for alumina, an adhesion test by UV treatment, and an adhesion test by heat treatment. For comparison, the perfluoropolyether compound “A20H-2000” manufactured by Matsumura Oil Research Co., Ltd. and “Z-Tetraol-2000S” manufactured by Solvaine Soil was analyzed in the same manner. Decomposition resistance test for Mina, adhesion test by UV treatment and adhesion test by heat treatment were conducted.

[0040] [Decomposition resistance test for alumina]

In each of the viscous liquid (lubricant) obtained in Example 1 and “A2 OH-2000” manufactured by Matsumura Oil Research Co., Ltd. and “Z-Tetraol- 2000S” manufactured by Solvaine Soil, alumina powder was used. (Average particle size 100 m) was added to 20% by weight and mixed for 1 minute or more using a shaker. About the sample mixed uniformly, the decomposition resistance test by heating was implemented using the thermal analyzer (TG ZDTA). The test consists of a sample mixed with alumina and a sample not mixed The sample was weighed into an aluminum container and heated at a temperature of 250 ° C in a nitrogen atmosphere, and the weight loss rate of the sample was measured. The results are shown in Table 1.

[0041] [Table 1]

[0042] From Table 1, the viscous liquid (lubricant) obtained in Example 1 has a low weight reduction rate and there is almost no difference in the weight reduction rate due to the presence or absence of alumina. It was confirmed that it was excellent in decomposition resistance against alumina.

[0043] [Adhesion test by UV treatment]

The viscous liquid (lubricant) obtained in Example 1, and “A2 011—2000” manufactured by Matsumura Oil Research Co., Ltd. “2-—61 61 ^ & 01—20003” manufactured by Chobi Solvay Co., Ltd. each of, dissolved in DuPont "Vertrel XF" were prepared each lubricant solution (0.1 wt ^_0/0). A 3.5-inch diameter magnetic disk was immersed in a lubricant solution, pulled up at a speed of 4 mmZs and coated with a lubricant, and then irradiated with ultraviolet light having wavelengths of 185 nm and 254 nm for 1 minute. Next, this disc was immersed in “Bertrel XF” for 1 minute and pulled up at a speed of lOmmZs to wash away the non-adhering lubricant. The film thickness of the lubricant deposited on the disk was measured by FTIR-RAS (High Sensitivity Reflective Fourier Transform Infrared Spectroscopy). The results are shown in Table 2.

[0044] [Table 2] Table 2

[0045] [Adhesion test by heat treatment]

After the lubricant was applied to the disk in the same manner as the adhesion test by UV treatment, an adhesion test by a general heat treatment (150 ° C) was performed as a comparison. Table 3 shows the measurement results of the film thickness of the lubricant adhering to the disk.

[0046] [Table 3]

Table 3

[0047] From Table 2 and Table 3, it was confirmed that the viscous liquid (lubricant) obtained in Example 1 did not adhere to the magnetic disk at all by heat treatment, but exhibited extremely high adhesion by UV treatment. It was done. From this, the effect of reducing the scattering of the lubricant can be expected.

[0048] Example 2

The viscous liquid (lubricant) obtained in Example 1 was dissolved in “Bertrel XF” manufactured by DuPont to prepare a lubricant solution (0.1 wt%). After immersing a 3.5-inch diameter magnetic disk consisting of a support, recording layer and protective layer in a lubricant solution for 1 minute, pulling it up at a speed of 4 mmZs and applying the lubricant, ultraviolet light including wavelengths 185 nm and 254 nm is applied. Irradiated for 1 minute. The film thickness of the lubricant deposited on the disk was measured with FTIR-RAS. Lubricant film thickness Was 24.8A.

[0049] A contact sliding test was performed on the magnetic disk obtained in Example 2.

[0050] [Contact sliding test]

The magnetic disk obtained in Example 2 was assembled in a friction tester, rotated at 90 rpm while pressing a sapphire ball at a position of radial direction r = 3 Omm, and the frictional force at that time was measured. For comparison, the friction force was measured in the same manner using a magnetic disk (A) with a lubrication layer formed by applying heat treatment (150 ° C) after applying Z-Tetraol-2000S made of Solvayine. did. The results are shown in Fig. 2.

[0051] From Fig. 2, it was confirmed that the magnetic disk obtained in Example 2 exhibited excellent durability against contact sliding with little friction.

Claims

Claims Formula (1); F (CF CF CF O) -CF CF CH-R1 (1) 2 2 2 m 2 2 2 (where R1 is

[Chemical 1]

It represents the same fluoroalkyl group. ), M represents 2-60. Represented by

1-4

A lubricant for recording media containing a perfluoropolyether compound.

2. A magnetic disk in which a recording layer and a protective layer are formed in this order on a support, and the lubricating layer having the lubricant force according to claim 1 is formed on the surface of the protective layer.