JPH07225941A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium whose lubricity is not reduced even after storage in an environment at high temp. and humidity by disposing a lubricant layer contg. a specified F-contg. carboxylic acid and an amine having an F-contg. hydrocarbon group on a ferromagnetic film. CONSTITUTION:A ferromagnetic film is disposed on a nonmagnetic substrate and a lubricant layer contg. one or more kinds of F-contg. carboxylic acids each having an F-contg. hydrocarbon group, an aliphatic hydrocarbon group and a carboxyl group at the terminals of each molecule and one or more kinds of amines each having an F-contg. hydrocarbon group is disposed on the ferromagnetic film optionally with a protective film in-between. Since carboxyl and amine groups bond readily to each other when they coexist, the F-contg. carboxylic acids and the amines exist while forming salts. Aminocarboxyl groups stick tightly to the surface of the metallic thin film or the protective film and the surface of a magnetic head. The terminal F-contg. hydrocarbon groups form a nonsticky surface and the terminal aliphatic hydrocarbon groups exhibit satisfactory lubricity. By the synergistic effect of the terminal groups, superior lubricity is ensured in any environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a vapor deposition tape having a ferromagnetic metal thin film as a magnetic layer.

[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, high-precision lubrication is required for sliding between the magnetic recording medium and the magnetic head due to the adoption of the ferromagnetic metal thin film for the purpose of improving the recording density. Has become. For example, in the case of a vapor deposition tape, the lubricant layer on the surface of the magnetic layer is only a few tens of liters 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. It is formed to have a thickness. 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 type magnetic recording medium, a long chain carboxylic acid perfluoroalkylamine salt compound represented by (Chemical formula 3) or a fluoroalkyl ether group-containing aliphatic carboxylic acid represented by (Chemical formula 4) is used. Since the fluoroalkyl group-containing aliphatic carboxylic acid represented by the formula (Chemical Formula 5) has excellent compatibility with a metal thin film, a proposal has been made (JP-A-4-274018, JP-A-4-270243). , Japanese Patent Application No. 5-77818).

[0004]

[Chemical 3]

[0005]

[Chemical 4]

[0006]

[Chemical 5]

[0007]

However, when the magnetic tape is stored in a high temperature and high humidity environment, the lubricant represented by the above (Chemical formula 3), (Chemical formula 4) or (Chemical formula 5) causes a back coat of the lubricant. However, there was a problem that the amount of lubricant on the surface of the magnetic layer was reduced and the lubricity was lowered. This decrease in lubricity is more prominent as deterioration in still durability rather than durability in repeated running after storage.

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

[0009]

The magnetic recording medium of the present invention for achieving the above object is provided with a ferromagnetic film on a non-magnetic support, and the ferromagnetic film is directly or through a protective film on the ferromagnetic film. And a lubricant layer containing at least one fluorine-containing carboxylic acid having a fluorine-containing hydrocarbon group, an aliphatic hydrocarbon group, and a carboxyl group at the terminal of the molecule and at least one amine having a fluorine-containing hydrocarbon group.

Suitable fluorine-containing carboxylic acids are represented by the general formula (Formula 6), and fluorine-containing hydrocarbon group-containing amines are represented by the general formula (Formula 7).

[0011]

[Chemical 6]

Here, R ₁ is an aliphatic alkyl group or an aliphatic alkenyl group, R ₂ is a fluoroalkyl group, a fluoroalkenyl group, a fluorophenyl group or a fluoroalkyl ether group, and R ₃ is a saturated or unsaturated group. Represents a hydrocarbon chain of and n is 0 or 1.

[0013]

[Chemical 7]

Here, R ₄ represents a fluoroalkyl group or a fluoroalkenyl group, and R ₅ represents a saturated or unsaturated hydrocarbon chain.

R₁Has 6 to 30 carbon atoms, preferably
10 to 24 are suitable, and the number of carbon atoms is less than 6 or 30
If it exceeds, lubricity will be reduced. R₂Has 3 carbons
~ 30, preferably 6-18 fluoroalkyl groups, bonds
Having ether or phenylated ether as a group
It may have a carbon number of 3 to 30, preferably 6 to 18.
Alkenyl group, having 6 to 18 carbon atoms, preferably 6 to 1
2, a fluorophenyl group having 5 to 50 carbon atoms, preferably
5-30 fluoroalkyl ether groups are suitable, charcoal
If the prime number is outside these ranges, lubricity and storage reliability
Is reduced. R ₃, R_FiveHas 1 to 20 carbon atoms, preferably
Preferably 1 to 10 saturated or unsaturated hydrocarbon chains
If the carbon number exceeds 20, lubricity or storage reliability
Sex decreases. R_FourHas 3 to 30 carbon atoms, preferred
Or 6-18 fluoroalkyl group, and ether as a bonding group.
Number of carbon atoms that may have ethers with phenyl or phenyl
Is 3 to 30, preferably 6 to 18 fluoroalkenyl group
Is suitable, and if the carbon number is out of these ranges,
Reliability decreases.

This lubricant layer is prepared by mixing one or more kinds of fluorine-containing carboxylic acids represented by the general formula (Chemical formula 6) and amines having a fluorine-containing hydrocarbon group represented by the general formula (Chemical formula 7), or a mixture thereof. Add other lubricants, rust preventives, etc. to make them exist in a thin layer. The mixing ratio of the fluorine-containing hydrocarbon group-containing amine is 30 mol% or more, preferably 50 mol% or more, and the fluorine-containing hydrocarbon group-containing amine is less than 30 mol% according to the present invention. It is difficult to obtain the effect of. The abundance is 0.05 to 100 m per 1 m ² of surface
A range of g, preferably 0.1 to 50 mg 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 to 80%, preferably 0 to 70%
Is suitable, and if the mixture of the fluorinated carboxylic acid and the fluorinated hydrocarbon group-containing amine is less than 20%, it is difficult to obtain the effects of the present invention.

As the protective film, a carbon thin film obtained by a method such as sputtering or plasma CVD such as 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.

[0018]

In the magnetic recording medium of the present invention, a ferromagnetic film is provided on a non-magnetic support, and a fluorine-containing hydrocarbon group and an aliphatic hydrocarbon are attached to the ends of the molecule directly or through a protective film on the ferromagnetic film. A lubricant layer containing at least one fluorine-containing carboxylic acid having a group and a carboxyl group and at least one fluorine-containing hydrocarbon group-containing amine is provided. Since the carboxyl group and the amino group are easily combined when they coexist, it is considered that the fluorine-containing carboxylic acid and the fluorine-containing hydrocarbon group-containing amine in the lubricant layer exist in the form of a salt. This fluorine-containing carboxylic acid amine salt has two fluorine-containing hydrocarbon end groups in the same molecule, namely, a fluoroalkyl end group, a fluoroalkenyl end group, a fluorophenyl end group or a fluoroalkyl ether end group and one aliphatic carbon group. It is a structure having a hydrogen end group, that is, an aliphatic alkyl end group or an aliphatic alkenyl end group and an amino / carboxyl group. Here, since the fluorine-containing hydrocarbon terminal group is oleophobic, it has poor affinity with the backcoat layer composed of the hydrocarbon-based polymer. On the other hand, the lipophilic aliphatic hydrocarbon end group has a high affinity for the backcoat layer, but if there are more fluorine-containing hydrocarbon end groups than the aliphatic hydrocarbon end groups in the same molecule, Becomes more oleophobic,
The affinity with the back coat layer is weakened. Therefore, transfer of the fluorinated carboxylic acid amine salt to the back coat layer, that is, reduction from the surface of the magnetic layer is suppressed, and the magnetic tape does not deteriorate with time.

By the way, the amino / 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 fluorine-containing hydrocarbon terminal group is exposed on the surface and contributes to lowering the energy of the surface, forming a non-adhesive surface. Furthermore, the aliphatic hydrocarbon end groups exhibit good lubricity due to the flexible carbon-carbon bond chain. Then, due to the synergistic effect of each of these terminal groups, excellent lubricity is exhibited in all environments from a low humidity environment to a high humidity environment.

[0020]

EXAMPLES Examples of the magnetic recording medium of the present invention will be specifically described below.

(Example 1) In the non-magnetic support of the magnetic recording medium of this example, granular projections (average height 70Å, diameter 1 μm) having a gradual slope due to silica fine particles added to the polyester film had a surface of 100 μm. There are several per ² particles, and the silica film colloidal particles with a diameter of 150Å are used as the core, and the UV curable epoxy resin is used as the binder, on the surface of the polyester film where the relatively large protrusions due to the fine particles due to the polymerization catalyst residue are reduced as much as possible. The steep mountain-shaped projections were formed so as to be 1 × 10 ⁷ per 1 mm ² . Then, on the non-magnetic support, a Co—Ni ferromagnetic film (Ni content 20%,
A film thickness of 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, 1 m of an equimolar mixture of the fluorine-containing carboxylic acid represented by the formula (Chemical formula 8) and the amine with a fluorine-containing hydrocarbon group represented by the formula (Chemical formula 9) on the ferromagnetic film. ²
A magnetic tape A was produced by coating the coated layer so that the amount thereof was 10 mg per unit to form a lubricant layer, and then cutting it into a predetermined width.

[0023]

[Chemical 8]

[0024]

[Chemical 9]

A magnetic tape B was prepared in the same manner as the magnetic tape A after forming a protective film of diamond-like carbon with a thickness of 50Å on the ferromagnetic film by the plasma CVD method. The magnetic tape is 40 ℃, 90% RH
After being stored for 1 week in the above environment, the residual ratio of fluorine on the surface of the magnetic layer before and after storage was examined by X-ray photoelectron spectroscopy (ESCA). Also, 23 ℃, 10% RH and 40 ℃, 80% R
The output characteristics at the time of still reproduction were measured in a commercially available video deck under the environment of H, and the still durability time until the RF output decreased by 3 dB from the initial value or the output fluctuation started to be obtained.

(Embodiment 2) In the magnetic tape B of Embodiment 1, instead of (Chemical formula 8) and (Chemical formula 9), (Chemical formula 10) and (Chemical formula 1) are used.
A magnetic tape using 1) was prepared and the same test was conducted.

[0027]

[Chemical 10]

[0028]

[Chemical 11]

(Embodiment 3) In the magnetic tape A of Embodiment 1, (formula 8) and (formula 9) are used instead of (formula 8) and (formula 9).
Then, a similar test was conducted by preparing a magnetic tape using a mixture of a conventionally known rust preventive agent C ₈ F ₁₇ C ₂ H ₄ NHC ₁₈ H ₃₅ in a weight ratio of 2: 1.

(Embodiment 4) In the magnetic tape B of Embodiment 1, (formula 8) and (formula 9) are used instead of (formula 8) and (formula 9).
Then, a similar test was conducted by preparing a magnetic tape using a mixture of the conventionally known lubricant C ₁₇ H ₃₃ COOC ₂ H ₄ C ₆ F ₁₃ in a weight ratio of 1: 1.

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 4) and (Chemical Formula 5), respectively.

[0032]

[Table 1]

From Table 1, all magnetic tapes provided with a lubricant layer containing at least one fluorine-containing carboxylic acid and at least one fluorine-containing hydrocarbon group-containing amine according to the present invention were prepared under the environment of high temperature and high humidity. It is clear that the lubricity is excellent even after storage. On the other hand, it is clear that the conventional magnetic tape provided with a lubricant layer made of only a lubricant has a reduced lubricant content and a reduced lubricity when stored in an environment of high temperature and high humidity.

In the embodiment, (Chemical formula 8) and (Chemical formula 9),
Although a mixture of (Chemical Formula 10) and (Chemical Formula 11) and (Chemical Formula 8) and (Chemical Formula 9) and a conventionally known lubricant and rust preventive agent has been described, (Chemical Formula 12), (Chemical Formula 13) and (Chemical Formula 14) ) And (Chemical 1
5), (Chemical formula 16) and (Chemical formula 17) and (Chemical formula 18) and (Chemical formula 19), and mixtures of these substances with conventionally known lubricants and rust preventives, the same effect can be obtained.

[0035]

[Chemical 12]

[0036]

[Chemical 13]

[0037]

[Chemical 14]

[0038]

[Chemical 15]

[0039]

[Chemical 16]

[0040]

[Chemical 17]

[0041]

[Chemical 18]

[0042]

[Chemical 19]

[0043]

As is apparent from the above description, a magnetic recording medium provided with a lubricant layer containing at least one fluorine-containing carboxylic acid and one or more fluorine-containing hydrocarbon group-containing amine of the present invention is a lubricant layer. In, the carboxyl group and the amino group are easily combined to form a salt, and the transfer of the lubricant to the back coat layer, that is, the decrease from the surface of the magnetic layer is suppressed,
The magnetic tape exhibits an excellent effect that the lubricity does not decrease even after storage in a high temperature and high humidity environment.

Claims (2)

[Claims] 1. A ferromagnetic film is provided on a non-magnetic support, and a fluorine-containing hydrocarbon group, an aliphatic hydrocarbon group and a carboxyl group are provided on the ferromagnetic film directly or through a protective film at the molecular end. A magnetic recording medium provided with a lubricant layer containing at least one fluorine-containing carboxylic acid and one or more fluorine-containing hydrocarbon group-containing amine. 2. The magnetic recording medium according to claim 1, wherein the fluorinated carboxylic acid is represented by the general formula (Formula 1), and the fluorinated hydrocarbon group-containing amine is represented by the general formula (Formula 2). [Chemical 1] Here, R ₁ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₂ represents a fluoroalkyl group, a fluoroalkenyl group, a fluorophenyl group or a fluoroalkyl ether group, and R ₃ represents a saturated or unsaturated hydrocarbon. A chain is shown, and n is 0 or 1. [Chemical 2] Here, R ₄ represents a fluoroalkyl group or a fluoroalkenyl group, and R ₅ represents a saturated or unsaturated hydrocarbon chain.