JPH06293704A - Fluorine-conatining carboxylic acid and magnetic recording medium containing the same - Google Patents

Abstract

PURPOSE:To provide a novel fluorine-containing carboxylic acid which is useful as a lubricant, a surfactant, a releasing agent or an anticorrosive agent showing no deterioration in lubricity even after storage under high-temperature and high-humidity conditions, particularly useful for magnetic recording medium. CONSTITUTION:A fluorine-containing carboxylic acid of formula I (R1 is aliphatic alkyl, aliphatic alkenyl; R2 is fluoroalkyl, fluoroalkenyl; (m) is integer of 1 or more; (n) is 0 or 1), for example, a compound of formula II. A magnetic recording medium is obtained by forming a ferromagnetic layer on a nonmagnetic medium coating the medium directly or through a protecting layer with one or more of the fluorine-containing carboxylic acid to form a lubricant layer. The compound of formula II is obtained by reaction of octadecylsuccinic adhydride of formula III with a fluoroalkyl adduct to alcohol of formula IV. The compound of formula I is characterized by having a fluorine-containing hydrocarbon terminus formed by direct addition of an aliphatic omega-alkenyl to the tail of fluorocarbon group.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel fluorine-containing carboxylic acid useful as a lubricant, a surfactant, a release agent, an anticorrosive agent for precision machines and precision parts that require high-precision lubricity. A magnetic recording medium having the same.

[0002]

2. Description of the Related Art With the miniaturization and high precision of mechanical devices and parts, the lubrication mode of their sliding parts has been shifting from fluid lubrication to boundary lubrication. In particular, in electronic devices such as VTRs and magnetic disks, and electronic parts, by using a ferromagnetic metal thin film for the purpose of improving the recording density, high-precision lubrication is provided for sliding between the magnetic tape or the magnetic disk and the magnetic head. Has become necessary.

For example, in a vapor-deposited tape or a hard disk, a lubricant layer on the surface of the magnetic layer is used in order to minimize the spacing loss between the magnetic recording medium and the magnetic head while achieving high output while ensuring durability and reliability. Is formed to have a thickness of only a few tens of liters. Therefore, development of an organic compound having excellent lubricity as a material for forming the lubricant layer is an important issue.

As a lubricant for a metal thin film magnetic recording medium, for example, a fluoroalkyl group-containing aliphatic carboxylic acid represented by (Chemical Formula 2) or (Chemical Formula 3) has excellent compatibility with a metal thin film. A proposal has been made (Japanese Patent Laid-Open No. 61-1075).
29, JP-A-2-108218).

[0005]

[Chemical 2]

[0006]

[Chemical 3]

[0007]

However, the lubricant of fluoroalkyl group-containing aliphatic carboxylic acid represented by the above (Chemical formula 2) or (Chemical formula 3) is crystallized when stored in a high temperature and high humidity environment. However, there is a problem in that the lubricating property is deteriorated due to the precipitation of.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a substance which does not deteriorate in lubricity even after storage in an environment of high temperature and high humidity.

[0009]

The substance of the present invention for achieving the above object is a fluorine-containing carboxylic acid represented by the general formula (Formula 4).

[0010]

[Chemical 4]

R ₁ preferably has 6 to 30 carbon atoms, preferably 10 to 24 carbon atoms, and has less than 6 carbon atoms or 30 carbon atoms.
If it exceeds, lubricity will be reduced. R ₂ has 1 carbon atom
-30, preferably 4-18 are suitable and have 0 carbon atoms.
Alternatively, when it exceeds 30, the lubricity decreases. m is 1-2
0, preferably 2 to 10, is suitable, and when m exceeds 20, lubricity decreases.

In the magnetic recording medium of the present invention, a ferromagnetic film is provided on a non-magnetic support, and the fluorine-containing carboxylic acid represented by the general formula (Chem. 4) is directly formed on the ferromagnetic film or through a protective film. A lubricant layer containing one or more acids is provided.

In this lubricant layer, the fluorinated carboxylic acid represented by the general formula (Formula 4) is used alone or in the form of a thin layer by adding other lubricants, rust preventives and the like. Its abundance is 0.05 to 100 mg, preferably 0.1 to 50, per 1 m ² of surface.
The mg range is suitable. As the other lubricant and rust preventive, a fluorine-containing compound is preferable, and a liquid type fluorine-containing compound is more preferable. The amount added is 0-80
%, Preferably 0 to 70% is suitable, and when the content of the fluorinated carboxylic acid represented by the general formula (Formula 4) is less than 20%, the effect of the present invention is difficult to obtain.

As the protective film, a carbon thin film obtained by a method such as sputtering or plasma CVD in an amorphous form, a graphite form, a diamond form or a mixed state or a laminated state thereof can be applied, and the thickness thereof is 5
0 to 500Å is preferable.

[0015]

The fluorinated carboxylic acid of the present invention is conventionally known to have a fluorocarbon end group, that is, a fluorinated hydrocarbon end group having an aliphatic omega (ω) alkenyl bonded immediately after the fluoroalkyl end group or the fluoroalkenyl end group. Is different from the lubricant.

That is, the fluorine-containing hydrocarbon end group is bent in a cis or trans structure at the portion where the fluorocarbon end group and the aliphatic omega (ω) alkenyl are bonded. Therefore, the fluorocarbon end group is hard to come close to the fluorocarbon end groups of other adjacent molecules, and a proper intermolecular interaction does not work. For this reason, the molecules of the fluorine-containing carboxylic acid cannot be aligned with each other, and the crystallization phenomenon in which the molecules are aligned does not occur.

By the way, the carboxyl group strongly adheres to the surface of the metal thin film or the surface of the protective film and the surface of the magnetic head. Further, the fluorocarbon terminal group is exposed on the surface and contributes to lowering the energy of the surface, forming a non-adhesive surface.
In addition, aliphatic hydrocarbon end groups, ie, aliphatic alkyl or alkenyl end groups, are flexible carbon-
It has good lubricity because it is a carbon-bonded chain. And
Due to the synergistic effect of each of these terminal groups, excellent lubricity is exhibited in all environments from low humidity environments to high humidity environments.

[0018]

【Example】

(Embodiment 1) Hereinafter, the first embodiment of the present invention will be specifically described.

The substance of this embodiment is represented by (Chemical Formula 5).

[0020]

[Chemical 5]

The substance represented by (Chemical Formula 5) will be described in comparison with the general formula (Chemical Formula 4). As the aliphatic alkyl group R ₁ , C ₁₈
H ₃₇ (octadecyl), R ₂ has a fluoroalkyl group having 6 carbons bonded to fluorine, and m is 2
And n is 0.

Next, a method for producing the substance represented by (Chemical Formula 5) will be described. The starting materials were octadecyl succinic anhydride 35.3 g (0.10 mol) represented by (Chemical Formula 6) and (Chemical Formula 7).
Fluoroalkyl group-containing alcohol represented by 39.0 g
(0.10 mol).

[0023]

[Chemical 6]

[0024]

[Chemical 7]

The above raw materials, 170 ml of normal heptane and 130 ml of toluene were sampled in a 1 liter flask equipped with a stirring blade and reacted under reflux for 24 hours. After the reaction,
Normal heptane and toluene were distilled off from the reaction solution, the reaction product was made into a normal hexane solution, and then cooled to 0 ° C. to remove unreacted octadecyl succinic anhydride.

Further, the reaction product was used as a methanol solution and cooled to -10 ° C. to remove unreacted fluoroalkyl group-containing alcohol to obtain 53 g of a white solid having a melting point of 43 ° C. This white solid is a fluorine-containing compound represented by the formula (Chemical Formula 5) containing no starting material and by-products by infrared spectroscopic analysis (IR), gel permeation chromatography (GPC) and organic mass spectrometry (FD-MS). It was found to be a carboxylic acid.

IR: Absorption peak of acid anhydride at 1,775 cm ^-1 and extinction of alcohol at 3,330 cm ^-1 , absorption peak of ester at 1,735 cm ^-1 and absorption peak of carboxylic acid at 1705 cm ^-1 Appearance.

GPC: No starting material or by-products detected. FD-MS; main peak at m / e 743.

In this example, a mixed solvent of normal heptane and toluene was used as the reaction solvent, but the starting material was dissolved and the reaction temperature was 40 to 150 ° C., preferably 60.
Hydrophobic solvent that can be set to ~ 120 ℃, alcohols,
Any material other than ester-based materials may be used. This also applies to the other embodiments.

(Embodiment 2) Next, a second embodiment of the present invention will be specifically described.

The substance of this embodiment is represented by the chemical formula (8).

[0032]

[Chemical 8]

Explaining the substance of (Chemical formula 8) by comparing it with the general formula of (Chemical formula 4), C as an aliphatic alkenyl group R _{1
It has 15} H ₃₁ CH═CHCH ₂ (2-octadecenyl), has as R ₂ a fluoroalkenyl group having 6 carbons bonded to fluorine, and has m of 9 and n of 1.

Next, a method for producing the substance represented by Chemical formula 8 will be described. Starting materials are 35.1 g (0.10 mol) of 2-octadecenyl succinic anhydride represented by (Chemical Formula 9) and 45.0 g (0.10 mol) of a fluoroalkenyl group-containing alcohol represented by (Chemical Formula 10).

[0035]

[Chemical 9]

[0036]

[Chemical 10]

The above raw materials and 300 ml of benzene were sampled in a 1 liter flask equipped with a stirring blade and reacted under reflux for 24 hours. After the reaction is completed, the unreacted starting materials are removed by the same treatment as in (Example 1) to give a colorless transparent liquid 65.
got g. This colorless and transparent liquid contains IR, GPC and F
By D-MS, it was found to be a fluorine-containing carboxylic acid represented by the formula (Formula 8) containing no starting material and by-products.

IR: Absorption peak of acid anhydride at 1,775 cm ^-1 and extinction of absorption peak of alcohol at 3,330 cm ^-1 , absorption peak of ester at 1,735 cm ^-1 and absorption peak of carboxylic acid at 1705 cm ^-1 Appearance.

GPC: No starting material or by-products detected. FD-MS; main peak at m / e 801.

(Embodiment 3) Next, an embodiment of the magnetic recording medium of the present invention will be specifically described.

In the non-magnetic support of the magnetic recording medium of the present example, there were several granular projections (average height 70Å, diameter 1 μm) per 100 μm ^{2 on the} surface due to the silica fine particles added in the polyester film. Moreover, on the surface of the polyester film where the comparatively large projections due to the fine particles due to the polymerization catalyst residue are reduced as much as possible, the silica colloid particles with a diameter of 150Å are used as the core, and the steep mountain-like projections using the UV curable epoxy resin as the binder. Was used to form 1 × 10 ⁷ pieces per 1 mm ² .

On the non-magnetic support, a Co—Ni ferromagnetic film (Ni content 2
0%, film thickness 1000Å) was provided in the presence of a trace amount of oxygen. The oxygen content in the ferromagnetic film was 5% in atomic fraction.

Then, a fluorine-containing carboxylic acid represented by the formula (Chemical Formula 5) was applied on the above ferromagnetic film so that the amount thereof was 10 mg per 1 m ² to form a lubricant layer. A magnetic tape was produced by cutting the tape to a predetermined width. The magnetic tape was stored in an environment of 40 ° C. and 90% RH for 1 week, and then examined for the presence of crystals by an optical microscope. Also, 23 ℃,
Measure the output characteristics during repeated running by putting it on a commercially available VCR in the environment of 10% RH, 40 ° C, 80% RH,
The number of times of running until the RF output decreased by 3 dB from the initial value or the output fluctuation started to occur was obtained.

(Example 4) In the magnetic tape of (Example 3), a magnetic tape using (Chemical formula 8) in place of (Chemical formula 5) was prepared and the same test was conducted.

(Example 5) In the magnetic tape of (Example 3), instead of (Chemical formula 5), (Chemical formula 5) and a conventionally known rust preventive agent C ₈ F ₁₇ C ₂ H ₄ NHC ₁₈ H ₃₅ are weighed. A similar test was performed by making a magnetic tape using a mixture having a ratio of 2: 1.

(Example 6) In the magnetic tape of (Example 3), instead of (Chemical formula 5), (Chemical formula 5) and a conventionally known lubricant C ₁₇ H ₃₃ COOC ₂ H ₄ C ₆ F ₁₃ were used in a weight ratio. A magnetic tape using a 1: 1 mixture was prepared and subjected to the same test.

The test results of the above examples are shown in (Table 1). The lubricants of Conventional Examples 1, 2 and 3 in the table are those represented by (Chemical Formula 3), (Chemical Formula 11) and (Chemical Formula 12), respectively.

[0048]

[Chemical 11]

[0049]

[Chemical 12]

[0050]

[Table 1]

From Table 1, all the magnetic tapes provided with the lubricant layer containing at least one fluorine-containing carboxylic acid of the present invention have excellent lubricity even after storage in a high temperature and high humidity environment. It is clear. On the other hand, it is clear that the conventional magnetic tape provided with a lubricant layer consisting of only a lubricant has a low lubricity due to precipitation of crystals of the lubricant when stored in an environment of high temperature and high humidity.

(Embodiment 7) Next, another embodiment of the magnetic recording medium of the present invention will be specifically described.

The non-magnetic support of the magnetic recording medium of the present example was formed by applying a non-magnetic Ni-P alloy plating of 25 μm thickness on the surface of an Al alloy plate having a diameter of 95 mm and a thickness of 1.2 mm, and averaging by texturing. A protrusion having a roughness of 50Å and a maximum height of 300Å was used. 1300Å Cr with a thickness of 1300Å by sputtering on non-magnetic Ni-P alloy plating
Form a 600 Å thick Co-Ni ferromagnetic film on the base,
Further, a sample A is formed by forming a graphite protective film having a thickness of 200Å on the ferromagnetic film by a sputtering method.

Sample B is a diamond-like carbon protective film having a thickness of 50 Å formed by plasma CVD instead of the graphite protective film. Next, the fluorine-containing carboxylic acid represented by Chemical formula 5 was applied on the protective films of these samples so that the amount thereof was 10 mg per 1 m ² , and a lubricant layer was provided to prepare magnetic disks.

The magnetic disk was stored in an environment of 40 ° C. and 90% RH for 1 week, and then examined by an optical microscope for crystal precipitation. In addition, 23 ℃, 10% RH and 40 ℃, 8
A CSS (contact start stop) durability test was conducted in an environment of 0% RH, and the number of CSSs when the friction coefficient exceeded 1.0 or the CS when a head crash occurred.
The durability was judged by the number of times of S.

(Example 8) In the magnetic disk of (Example 7), a magnetic disk using (Chemical formula 8) instead of (Chemical formula 5) was prepared and the same test was conducted.

(Example 9) In the magnetic disk of (Example 7), a magnetic disk using the same lubricant as in (Example 5) in place of (Chemical formula 5) was prepared and the same test was conducted.

(Example 10) In the magnetic disk of (Example 7), a magnetic disk using the same lubricant as in (Example 6) in place of (Chemical formula 5) was prepared and the same test was conducted.

The test results of the above examples are shown in (Table 2). The lubricants of Conventional Examples 4, 5 and 6 in the table are those represented by (Chemical Formula 3), (Chemical Formula 11) and (Chemical Formula 12), respectively.

[0060]

[Table 2]

From Table 2, all the magnetic disks of the present invention provided with a lubricant layer containing one or more fluorine-containing carboxylic acids have excellent lubricity even after storage in a high temperature and high humidity environment. It is clear. On the other hand, it is clear that the conventional magnetic disk provided with a lubricant layer made of only a lubricant has a low lubricity due to precipitation of crystals of the lubricant when stored in an environment of high temperature and high humidity.

In the examples, the mixture of the substances of (Chemical formula 5), (Chemical formula 8) and (Chemical formula 5) with the conventionally known lubricant and rust preventive agent was explained. ), (Chemical Formula 15), (Chemical Formula 16) and (Chemical Formula 17), and mixtures of these substances with conventionally known lubricants and rust preventives can also provide similar effects.

[0063]

[Chemical 13]

[0064]

[Chemical 14]

[0065]

[Chemical 15]

[0066]

[Chemical 16]

[0067]

[Chemical 17]

[0068]

As is apparent from the above description, the fluorine-containing carboxylic acid of the present invention has a fluorocarbon end group, that is, a fluoroalkyl end group or a fluoroalkenyl end group, immediately after the aliphatic omega (ω) alkenyl in the same molecule. After storage in a high temperature and high humidity environment because it has a fluorine-containing hydrocarbon end group and an aliphatic hydrocarbon end group bonded to each other, that is, an aliphatic alkyl end group or an aliphatic alkenyl end group and a carboxyl group. Also shows an excellent effect that the lubricity does not decrease.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10N 40:18

Claims (2)

[Claims] 1. A fluorine-containing carboxylic acid represented by the general formula (Formula 1). [Chemical 1] 2. A ferromagnetic film is provided on a non-magnetic support, and one or more fluorine-containing carboxylic acids represented by the general formula (Chemical Formula 1) are directly provided on the ferromagnetic film or through a protective film. A magnetic recording medium provided with a lubricant layer containing.