JPH1091935A - Magnetic recording media - Google Patents

Abstract

(57) [Abstract] (with correction) [PROBLEMS] To provide a magnetic recording medium having a carbon-based protective film having a low coefficient of friction, good running properties, and high durability. SOLUTION: In a magnetic recording medium having a support, a magnetic film and a protective film, the Raman spectrum of the protective film is 800.
cm ^-1 has a peak in the region of ～2000Cm ^-1, when peak separated into two peaks so that the minimum error by a Gaussian function _{peak, 0.9 <S 1 / S 2} <1.65 where, S ₁ satisfies the area intensity of the low wave number side peak among the peak separated peaks, S ₂ satisfies the area intensity of the high wave number side peak among the peak separated peaks, and 0.4
<I _b / I _g <0.55, where I _b is the fluorescence background at the lower wave number peak position of the peak separated peaks, and I _g is the higher wave number peak of the peak separated peaks. Peak intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic recording medium.

[0002]

Due to the demand for high-density recording, a magnetic layer provided on a support is not a coating type using a binder resin, but is a metal tape that does not use a binder resin. Thin film types have been proposed. That is, a magnetic tape in which a magnetic layer is formed by wet plating means such as electroless plating or dry plating means such as vacuum evaporation, sputtering or ion plating has been proposed. This kind of magnetic tape has a high filling density of a magnetic material and is suitable for high-density recording.

In order to protect the metal magnetic film of the magnetic tape, it has been proposed to provide various protective films on the surface. For example, a diamond-like carbon film is one of these proposals. In addition, the diamond-like carbon film is formed, for example, by a hot filament CVD device, a photo CVD device,
CVD of RF plasma CVD equipment, microwave plasma CVD equipment, ECR microwave plasma CVD equipment, etc.
(Chemical vapor deposition) provided by a device.

However, it has been found that the conventional diamond-like carbon film is not sufficiently satisfactory. That is, the diamond-like carbon film is
Although it is high in hardness, it is inferior in tribological properties such as friction and requires a lubricant. However, even if a lubricant is provided on the inert diamond-like carbon film by coating, the lubricant is easily lost.

Accordingly, an object of the present invention is to provide a magnetic recording medium having a carbon-based protective film having a low coefficient of friction, good running properties and high durability.

[0006]

An object of the present invention is to provide a magnetic recording medium having a support, a magnetic film and a protective film, wherein the protective film is formed under the following conditions (1), (2) and (3). ,
The problem is solved by a magnetic recording medium characterized by satisfying (4).

Condition (1) The Raman spectrum of the protective film is 800 cm ^{-1 to} 2000 c.
It has a peak in the region of m ^-1 . Condition (2) When the peak is separated into two peaks by a Gaussian function so as to minimize the error, the following condition (3),
Satisfies (4).

Condition (3) 0.9 <S₁/ S_Two<1.65 where S₁Is the low wave number of the peaks separated
Area intensity of side peak S_TwoIs the higher wave number peak of the peaks separated.
Area strength Condition (4) 0.4 <I_b/ I_g<0.55 where I_bIs the low wave number of the peaks separated
Background I at the side peak position I_gIs the higher wave number peak of the peaks separated.
Peak intensity 0.90 ≦ S₁/ S_TwoPreferably ≤ 1.5
No. Also, 0.40 ≦ I _b/ I_g≤0.52
preferable.

[0009] The low wave number of the peaks
Half width W of side peak₁Is 100cm ^-1~ 400cm
^-1(Especially 150cm^-1~ 350cm^-1)
Half-width W of the peak on the higher wave number side of the peaks_Two
Is 40cm^-1~ 200cm^-1(Especially 60cm^-1~ 18
0cm^-1) Are preferred. That is,
Protective film that meets such conditions, especially carbon-based protective film
Has high toughness, relatively low electrical resistance and low coefficient of friction
It was excellent in running property and durability.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A magnetic recording medium according to the present invention is a magnetic recording medium having a support, a magnetic film and a protective film, wherein the protective film has the following conditions (1), (2), (3), (4)
It satisfies. Condition (1) The Raman spectrum of the protective film is 800 cm ^{-1 to} 2000 c.
It has a peak in the region of m ^-1 .

Condition (2) When the peak is separated into two peaks by a Gaussian function so as to minimize the error, the following condition (3)
Satisfies (4). Condition (3) 0.9 <S ₁ / S ₂ <1.65 where S ₁ is the area intensity of the lower wave number side peak among the peak separated peaks, and S ₂ is the high wave number of the peak separated peaks. Area intensity of side peak Condition (4) 0.4 < _Ib / _Ig <0.55 where _Ib is the fluorescence background at the lower wavenumber side peak position among the peaks separated, and _Ig is the peak Among the separated peaks, the peak intensity of the peak on the higher wave number side In particular, 0.90 ≦ S ₁ / S ₂ ≦ 1.5 and 0.40
≦ a I _b / I _g ≦ 0.52. Further, the half width W ₁ of the low-frequency side peak among the peaks peaks separated 100cm
^{-1 to} 400 cm ^-1 (especially 150 cm ^{-1 to} 350 c
m ^-1 ), and the half-width W _{2 of the} peak on the higher wave number side of the peaks separated is 40 cm ^{-1 to} 200 cm ^-1 (particularly, 60 cm ^{-1 to} 180 cm ^-1 ).

Hereinafter, further explanation will be given. FIG. 1 is a schematic diagram of a magnetic recording medium according to the present invention. In FIG. 1, reference numeral 1 denotes a support. The support 1 may be magnetic or non-magnetic. Representative examples are polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polycyclohexylene dimethylene terephthalate, and polyethylene bisphenoxycarboxylate; polyolefins such as polyethylene and polypropylene; cellulose acetate butyrate; Examples include cellulose derivatives such as cellulose acetate propionate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, and non-magnetic plastic materials such as polyamide and polycarbonate.
Of course, it is not limited to these. Also, various processes may be performed. For example, surface treatment by corona discharge or other appropriate means is performed. Further, polyester, polyurethane or oligomer for improving the adhesiveness may be applied.

A metal magnetic film 2 is provided on a support 1 by a dry plating method such as vapor deposition or sputtering to a thickness of 500 to 5000 mm. As a material of the magnetic particles forming the metal magnetic film, for example, in addition to metals such as Fe, Co, and Ni, Co
-Ni alloy, Co-Pt alloy, Co-Ni-Pt alloy,
Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-Co-B alloy, Co-Ni-Fe-B alloy,
A Co-Cr alloy or an alloy containing a different kind of metal is used. In addition, as the metal magnetic film, a nitride (for example, Fe-N, Fe-NO) or a carbide (for example, Fe-C, Fe-CO) of the above-mentioned material can be used.

The metal magnetic film 2 has a thickness of 10 to 500.degree.
A protective film 3 of about 0 to 200 ° is provided. This protective film 3 has the above characteristics. Such a protective film 3
Is, for example, a sputtering apparatus or an ECR microwave plasma C
A film can be formed using a VD apparatus. However, it is important that, for example, the following conditions are satisfied as the film forming conditions of the protective film 3.

When ECR microwave plasma CVD apparatus is used Vacuum evacuation degree; 1.0 × 10 ^{-6 to} 1.0 × 10 ^-4 Torr Raw materials; hydrocarbon-based gas such as methane, ethylene, acetylene, benzene, etc. , Unsaturated chain hydrocarbons having double or triple bonds such as ethylene and acetylene, cyclic unsaturated hydrocarbons (aromatic hydrocarbons) such as benzene, toluene, benzoic acid and benzaldehyde, or naphthalene and anthracene Hydrocarbon compounds having unsaturated bonds, such as those obtained by diluting benzene or toluene, etc. Raw material supply amount: Specified according to the degree of vacuum 1.2 × 10 ^{-1 to} 1.2 × 10 ^-5 Torr Can roll temperature -20 ° C to 40 ° C μ wave vibration frequency; 2.45 GHz μ wave output; 50 to 1000 W resonance point magnetic field; 875 Gauss sputtering device is used Target: Polygraphite Vacuum evacuation degree; <1.0 × 10 ⁻⁴ Torr Mixing ratio; Ar: H ₂ (CH ₄ ) = 2: 8 to 8: 2 Flow rate; defined by vacuum degree 1.2 × 10 ⁻¹ to 1.2 × 10 ⁻⁵ Torr Can roll temperature; −20 ° C. to 40 ° C. Sputtering voltage: 200 to 600 V Sputtering power: 0.5 to 6 kW The Raman spectrum of the protective film 3 thus obtained is as follows. Required.

As a measuring device, a triple spectrometer manufactured by Spex is used. The light source is an Ar laser with a 300 mW output and a wavelength of 488 nm. Then, the sample S is irradiated with an 488 nm Ar laser at an angle of 25 ° θ (the angle between the Ar laser and the sample S), and the scattered light from the sample S and the scattered light in the 90 ° direction are measured. Spectroscopy with a spectrometer (triple spectrometer). The measurement time (integrated time) is 10 minutes, at least three points are measured, and the average value is obtained. In order to determine the peak intensity, first, a blank level is checked. That is, without setting the sample S in the triple spectrometer,
Run the triple spectrometer for a minute and check the blank level of the triple spectrometer. Thereafter, the sample S is set in the triple spectrometer, and 10
A triple spectrometer is operated for one minute, a Raman spectrum is obtained, and the intensity of the peak point in each region (the height from the blank level to the peak value at the peak point) is determined based on the blank level. This is measured at three or more points, and the average value is determined.

Then, the peak of the obtained Raman spectrum is separated into two peaks by a Gaussian function (least square method). As a result, the protective film is made to meet the conditions (1)
It is checked whether (2), (3) and (4) are satisfied. In particular, when the protective film of the present invention is to be formed under film forming conditions other than the above conditions, a carbon film is formed once under specific conditions, and the carbon film is formed under the above conditions (1) and (2).
Check whether (2), (3) and (4) are satisfied,
If the condition is satisfied, the process is performed under that condition. If not, change some of the setting conditions, check whether the above conditions (1), (2), (3), and (4) are satisfied. If the test is repeated until the conditions are satisfied, Film formation conditions can be found.

Reference numeral 4 denotes a back coat film. 5 is 20 if necessary by dipping or ultrasonic spraying.
This is a lubricant film having a thickness of about 70 °. still,
When a Raman spectroscopy is performed on a protective film provided with a lubricant using a triple spectrometer, peaks due to CC, CH, CF bonds of the lubricant may be observed. In such a case, a peak in a state where a peak due to CC, CH, CF bonds of the lubricant is removed is obtained. Alternatively, the lubricant is removed in advance, and the Raman spectrum thereof is examined with a triple spectrometer. The lubricant can be removed by washing with a diluent such as perfluoropolyether,
Plasma etching using plasma (for example, reaction gas; Ar; reaction gas flow rate; from a vacuum of 9.0 × 10 ⁻⁶ Torr to 20 × 10 ⁻³ Torr; microwave output; 300)
W. ECR-CV under the condition of transport speed; 1 m / min
This is possible by performing D).

[0019]

EXAMPLE 1 A PET film (thickness: 6 μm) provided with a back coat film and a 2000 mm thick Co metal magnetic film was loaded into a sputtering apparatus, and a 120 mm thick carbon-based protective film was formed on the Co metal magnetic film. Thus, an 8 mm VTR magnetic tape was obtained. The conditions for forming the protective film are as follows.

Target: polygraphite Sputter gas: Ar + H ₂ (5: 5) Sputter gas supply: 3.0 × 10 ^-5 Torr vacuum evacuation supplied to 4.0 × 10 ^-4 Torr Voltage: 430v Sputter output: 2kW Can roll temperature: 5 ° C

[0021]

Example 2 Example 2 was carried out in the same manner as in Example 1, except that the conditions for forming the protective film were as follows. Target: polygraphite Sputter gas: Ar + H ₂ (6: 4) Sputter gas supply: 3.0 × 10 ^-5 Torr vacuum evacuation supplied to 6.0 × 10 ^-4 Torr Sputter voltage: 430 V Sputter output: 2kW Can roll temperature: 5 ° C

[0022]

Example 3 Example 1 was repeated except that the conditions for forming the protective film were as follows. The film forming apparatus is an ECR microwave plasma CVD apparatus. Protective film constituent material: C ₆ H ₆ (benzene) Supply amount of protective film constituent material: 1.0 × 10 ^-5 Torr vacuum supply degree is supplied so as to be 4.0 × 10 ^-4 Torr. Frequency: 2.45 GHz μ wave output: 600 W resonance point magnetic field (ECR-Point magnetic field); 875 Gau
ss Can roll temperature: 5 ° C

[0023]

Example 4 Example 3 was carried out in the same manner as in Example 3, except that the conditions for forming the protective film were as follows. Supply amount of constituent material of protective film; supply at 1.0 × 10 ^-5 Torr vacuum evacuation degree to 2.0 × 10 ^-4 Torr μ wave vibration frequency: 2.45 GHz μ wave output: 900 W resonance point Magnetic field (ECR-Point magnetic field); 875 Gau
ss Can roll temperature: 5 ° C

[0024]

Comparative Example 1 The procedure of Example 1 was repeated, except that the conditions for forming the protective film were changed as follows. Target: graphite Sputter gas: Ar + H ₂ (9: 1) Sputter gas supply: 3.0 × 10 ^-5 Torr vacuum evacuation supplied to 9.0 × 10 ^-4 Torr Sputter voltage: 430 v Sputter Output: 2kW Can roll temperature: 5 ℃

[0025]

Comparative Example 2 The procedure of Example 1 was repeated, except that the conditions for forming the protective film were as follows. Target: graphite Sputter gas: Ar + H ₂ (1: 9) Sputter gas supply: 3.0 × 10 ⁻⁵ Torr vacuum evacuation supplied to 1.2 × 10 ⁻⁴ Torr Sputter voltage: 430 v Sputter Output: 2kW Can roll temperature: 5 ℃

[0026]

Comparative Example 3 The procedure of Example 3 was repeated, except that the conditions for forming the protective film were as follows. Protective film constituent material: CH ₄ Protective film constituent material supply amount; 1.0 × 10 ^-4 Torr vacuum evacuation supplied to 2.0 × 10 ^-4 Torr Microwave vibration frequency: 2.45 GHz Microwave output: 600 W resonance point magnetic field (ECR-Point magnetic field); 875 Gau
ss Can roll temperature: 5 ° C

[0027]

[Characteristics] Raman spectra of the protective film of the magnetic tape for 8 mm VTR obtained in each of the above examples were obtained. 8, 9 and 10 (of Example 3), FIG.
1, 12, 13 (Example 4), FIGS. 14, 15, 1
6 (of Comparative Example 1), FIGS. 17, 18, and 19 (Comparative Example 2)
20), 21 and 22 (comparative example 3).

Then, S ₁ / S ₂ , I _b / I _g , W ₁ ,
Since it sought W _2, and the results are shown in Table 1. Further, the friction coefficient μ of the magnetic tape for 8 mm VTR obtained in each of the above examples was examined, and the result is shown in Table 1. In addition, jitter and still durability (time required for a still playback in an atmosphere of 20 ° C. and 50% RH to reduce the output by 3 dB) were also examined. The results are also shown in Table 1.

Table 1 S ₁ / S _{2 Ib} / I _g W ₁ W ₂ μ Jitter Still durability (cm ⁻¹ ) (cm ⁻¹ ) (nsec) (hr) Example 1 0.97 0.42 200 92 0.16 48 6.2 Example 2 1.33 0.47 220 90 0.14 44 6.4 Example 3 0.94 0.43 200 90 0.16 48 5.8 Example 4 1.41 0.45 300 92 0.15 42 6.0 Comparative Example 1 3.39 0.27 300 92 0.16 48 1.2 Comparative Example 2 0.67 0.62 180 94 0.22 62 5.2 Comparative Example 3 1.78 0.14 300 82 0.18 54 1.0 From these results, when the protective film provided on the metal magnetic film of the magnetic tape is the present invention, it is rich in lubricity, has a small friction coefficient, and has excellent durability. Things. Furthermore, it has little jitter and excellent recording / reproducing characteristics.

[0030]

The present invention has excellent running properties and durability, and has excellent recording and reproducing characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a magnetic recording medium.

FIG. 2 Raman spectrum before blank level correction

FIG. 3 Raman spectrum after blank level correction

FIG. 4 Raman spectrum with separated peaks

FIG. 5 Raman spectrum before blank level correction

FIG. 6 Raman spectrum after blank level correction

FIG. 7 Raman spectrum with separated peaks

FIG. 8 Raman spectrum before blank level correction

FIG. 9 Raman spectrum after blank level correction

FIG. 10: Raman spectrum with separated peaks

FIG. 11 Raman spectrum before blank level correction

FIG. 12 Raman spectrum after blank level correction

FIG. 13: Raman spectrum with separated peaks

FIG. 14: Raman spectrum before blank level correction

FIG. 15 Raman spectrum after blank level correction

FIG. 16: Raman spectrum with separated peaks

FIG. 17 Raman spectrum before blank level correction

FIG. 18 Raman spectrum after blank level correction

FIG. 19: Raman spectrum with separated peaks

FIG. 20: Raman spectrum before blank level correction

FIG. 21: Raman spectrum after blank level correction

FIG. 22: Raman spectrum with separated peaks

[Explanation of symbols]

 Reference Signs List 1 support 2 metal magnetic film 3 protective film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Osamu Yoshida 2606, Akabane, Kaigacho, Haga-gun, Tochigi Prefecture Kao Co., Ltd. In-house Information Science Laboratories (72) Inventor Takeshi Miyamura 2606 Akabane, Kaigamachi, Haga-gun, Tochigi Prefecture Kao Corporation In-house Information Science Laboratories

Claims (3)

[Claims] 1. A magnetic recording medium having a support, a magnetic film, and a protective film, wherein the protective film has the following conditions (1), (2), (3),
A magnetic recording medium satisfying (4). Condition (1) The Raman spectrum of the protective film is 800 cm ^{-1 to} 2000 c.
It has a peak in the region of m ^-1 . Condition (2) When the peak is separated into two peaks by a Gaussian function so as to minimize the error, the following condition (3),
Satisfies (4). Condition (3) 0.9 <S ₁ / S ₂ <1.65 where S ₁ is the area intensity of the lower wave number side peak among the peak separated peaks, and S ₂ is the high wave number of the peak separated peaks. Area intensity of side peak Condition (4) 0.4 < _Ib / _Ig <0.55 where _Ib is the fluorescence background at the lower wavenumber side peak position among the peaks separated, and _Ig is the peak Peak intensity of the higher wave number peak among the separated peaks 2. The half-width W ₁ of the low peak on the low wave number side of the peaks separated is 100 cm ^{−1 to} 400 cm ⁻¹ , and the half width W _{2 of the} peak on the high wave number side of the peaks separated is 40 cm. the magnetic recording medium of claim 1, which is a ^{-1 ~200cm -1.} 3. The magnetic recording medium according to claim 1, wherein the protective film is a carbon film.