JPH0319602B2 - - Google Patents
Info
- Publication number
- JPH0319602B2 JPH0319602B2 JP56127996A JP12799681A JPH0319602B2 JP H0319602 B2 JPH0319602 B2 JP H0319602B2 JP 56127996 A JP56127996 A JP 56127996A JP 12799681 A JP12799681 A JP 12799681A JP H0319602 B2 JPH0319602 B2 JP H0319602B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- thin film
- ferromagnetic thin
- magnetic recording
- recording medium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000005291 magnetic effect Effects 0.000 claims description 36
- 230000005294 ferromagnetic effect Effects 0.000 claims description 19
- 229910052751 metal Inorganic materials 0.000 claims description 17
- 239000002184 metal Substances 0.000 claims description 17
- 239000010409 thin film Substances 0.000 claims description 15
- 239000000314 lubricant Substances 0.000 claims description 11
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 3
- 150000002430 hydrocarbons Chemical class 0.000 claims description 2
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- -1 polyethylene Polymers 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 238000007733 ion plating Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- 229910020630 Co Ni Inorganic materials 0.000 description 2
- 229910002440 Co–Ni Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229920001747 Cellulose diacetate Polymers 0.000 description 1
- 229920002284 Cellulose triacetate Polymers 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- NNLVGZFZQQXQNW-ADJNRHBOSA-N [(2r,3r,4s,5r,6s)-4,5-diacetyloxy-3-[(2s,3r,4s,5r,6r)-3,4,5-triacetyloxy-6-(acetyloxymethyl)oxan-2-yl]oxy-6-[(2r,3r,4s,5r,6s)-4,5,6-triacetyloxy-2-(acetyloxymethyl)oxan-3-yl]oxyoxan-2-yl]methyl acetate Chemical class O([C@@H]1O[C@@H]([C@H]([C@H](OC(C)=O)[C@H]1OC(C)=O)O[C@H]1[C@@H]([C@@H](OC(C)=O)[C@H](OC(C)=O)[C@@H](COC(C)=O)O1)OC(C)=O)COC(=O)C)[C@@H]1[C@@H](COC(C)=O)O[C@@H](OC(C)=O)[C@H](OC(C)=O)[C@H]1OC(C)=O NNLVGZFZQQXQNW-ADJNRHBOSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229920002678 cellulose Chemical class 0.000 description 1
- 239000001913 cellulose Chemical class 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 229910052571 earthenware Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/72—Protective coatings, e.g. anti-static or antifriction
- G11B5/725—Protective coatings, e.g. anti-static or antifriction containing a lubricant, e.g. organic compounds
- G11B5/7253—Fluorocarbon lubricant
Landscapes
- Magnetic Record Carriers (AREA)
Description
本発明は、めつき、蒸着、スパツタリング、イ
オンプレーテイング等により非磁性支持体上に金
属強磁性薄膜を形成してなる磁気記録媒体に関す
るものである。
最近、残留磁束密度を大きくして高出力化を図
る等のために、Fe、Co、Co−Ni、Co−Cr、Fe
−Ni等の強磁性金属をめつき、真空蒸着、スパ
ツタリング、イオンプレーテイング等により非磁
性支持体上に直接付着させて金属強磁性薄膜を形
成するようにした磁気テープが実用化されてい
る。
このような磁気テープは、従来周知の如く、そ
の使用時において、磁気ヘツドやガイドドラムを
はじめ各種のテープガイド類に摺接する。このた
め、特に、磁気テープの磁性面、即ち金属強磁性
薄膜表面と上記摺動部材との間の摩擦はできるだ
け小さいのが望ましい。
本発明はこのような問題点に鑑みてなされたも
のであつて、金属強磁性薄膜表面に潤滑剤を塗布
して低摩擦係数のトツプコート層を形成すること
により、走行性の良い磁気記録媒体を提供しよう
とするものである。
このような潤滑剤としては、通常、カーボン鎖
を有する有機化合物が用いられるが、この場合、
その潤滑性を高めるために、表面張力のできるだ
け小さいものを用いるのが好ましい。この目的の
ために、本発明においては、金属強磁性薄膜表面
に塗布する潤滑剤として、カーボン鎖にフツ素の
結合したフツ化炭化水素化合物（以下、フルオロ
カーボン類という）を用いている。更に、例えば
低摺動速度においても充分な低摩擦係数を実現す
るために、本発明による潤滑剤は、そのカーボン
鎖の端部に、−SO3Me（MeはＫ又はNa）、−
SO2F、−COONH4、−COOH及び−SO3Hのうち
の少なくとも１種の活性基を有し、その塗布量
は、１〜100mg／m2である。
このような構成により、本発明による磁気記録
媒体は、金属強磁性薄膜とこの金属強磁性薄膜が
摺接する各種摺動部材との間の摩擦が小さくなつ
て、良好な走行特性を示す。
上記のような活性基を有するフルオロカーボン
類からなる潤滑剤は、従来の塗布型の磁気記録媒
体におけるトツプコート層としては不適当であつ
た。即ち、従来の塗布型の磁気記録媒体は、主と
して強磁性体粉末と有機バインダとからなる磁性
塗料が非磁性支持体上に塗布されて構成されてい
る。このような構成の磁性層表面に、トツプコー
ト層として、上記のような構成の活性基を有する
フルオロカーボン類からなる潤滑剤を塗布する
と、上記活性基が強磁性体粉末に吸着し、カーボ
ン鎖に結合したフツ素の有する大きな電気陰性度
のためにバインダがこの強磁性体粉末から殆ど完
全に遮断されてしまう。このため、磁気記録媒体
の摺動時における粉落ちが増加する。
これに対し、有機バインダを含有しない金属強
磁性薄膜で磁性層が構成されている本発明の磁気
記録媒体においては、上記のような活性基を有す
るフルオロカーボン類からなる潤滑剤を、粉落ち
の恐れなく、有効なトツプコート層として用いる
ことができる。
本発明において、上記フルオロカーボン類の塗
布量は、約１〜100mg／m2であり、特に、２〜20
mg／m2であるのが好ましい。この塗布量が１mg／
m2よりも少ないと、本発明による走行性改善の効
果が顕れない。一方、100mg／m2よりも多いと、
この潤滑剤層（トツプコート層）の表面張力によ
る摺動部材へのはりつきが起きるから、返つて走
行性の悪くなる恐れがあり、また、潤滑剤が金属
強磁性薄膜の表面に吸着しないで剥離してしまう
から、この剥離した部分が、磁気記録媒体（例え
ば、磁性テープ）と、ヘツドドラム、磁気ヘツ
ド、テープガイドなどの各種摺動部材との間に介
在してヘツドクロツク（磁気ヘツドのギヤツプが
絶縁状態となつてしまうこと）を引起こす原因と
なり、さらには、磁気ヘツドと磁気記録媒体との
間にスペーシングができるから、電磁変換特性の
劣化を招いてしまう。
本発明による磁気記録媒体のベースとなる非磁
性支持体は４〜25μ厚程度が好ましく、材料とし
ては、アセテート、ポリエチレン、ポリエチレン
テレフタレート、ポリエチレン−２，６−ナフタ
レート等のポリエステル類、ポリプロピレン等の
ポリオレフイン類、セルローストリアセテート、
セルロースダイアセテート等のセルロース誘導
体、ポリイミド、ポリアミド、ポリカーボネート
等のプラスチツク、Cu、Al、Zn、Al2O3等の非
磁性金属、ガラス、磁器、陶器等のセラミツクな
どが使用される。
この非磁性支持体上には、めつき、蒸着、スパ
ツタリング、イオンプレーテイング等により、
Fe、Co、Co−Ni、Co−Cr、Fe−Ni等からなる
約500〜2000Åの金属強磁性薄膜が形成される。
なお、本発明は磁気テープ以外の磁気記録媒
体、例えば磁気デイスク等にも適用可能である。
次に、本発明を実験例につき説明する。
実験例
14μ厚のポリエチレンテレフタレートフイルム
に、いわゆる斜め蒸着法によつてCoを付着させ、
1000Åの金属強磁性薄膜を形成した。なお、斜め
蒸着法とは、非磁性支持体表面に対し所定角度傾
斜した方向から蒸着ビームを入射させて蒸着する
方法であり、これによつて磁性層の磁気異方性を
所定方向に揃えることができ、その保磁力を大き
くすることができる。
次に、上記金属強磁性薄膜表面に、次表にＢ〜
Ｌで示す各化合物の１％フレオン溶液を６mg／m2
の割合で塗布し、磁気テープを作製した。なお、
実験例Ａにおいては、金属強磁性薄膜表面に何も
塗布しなかつた。
このようにして得られた各磁気テープを摩擦試
験に供し、夫々の摩擦係数を測定した。この摩擦
試験は次のようにして行つた。即ち、一端をテン
シヨンゲージに結合した各試料テープを、0.1Sの
ステンレス鋼からなるドラムに摺接させ、これら
各テープに50ｇの張力を付加した状態で往復動さ
せた。テープ巾は約12.7mm、走行速度は１mm／
secであつた。また、実験は、温度20℃、相対湿
度60％の条件化で行われた。結果を次表に示す
が、この摩擦係数は100回走行後でも殆ど変らな
かつた。
The present invention relates to a magnetic recording medium in which a metal ferromagnetic thin film is formed on a nonmagnetic support by plating, vapor deposition, sputtering, ion plating, or the like. Recently, in order to increase the residual magnetic flux density and increase output, Fe, Co, Co-Ni, Co-Cr, Fe
Magnetic tapes have been put into practical use in which a ferromagnetic metal such as -Ni is plated and directly deposited on a nonmagnetic support by vacuum evaporation, sputtering, ion plating, etc. to form a metal ferromagnetic thin film. As is well known in the art, such a magnetic tape comes into sliding contact with various tape guides including a magnetic head and a guide drum during use. For this reason, it is particularly desirable that the friction between the magnetic surface of the magnetic tape, that is, the surface of the metal ferromagnetic thin film, and the sliding member be as small as possible. The present invention was made in view of these problems, and it is possible to create a magnetic recording medium with good running performance by applying a lubricant to the surface of a metal ferromagnetic thin film to form a top coat layer with a low coefficient of friction. This is what we are trying to provide. As such a lubricant, an organic compound having a carbon chain is usually used, but in this case,
In order to improve its lubricity, it is preferable to use a material with as low a surface tension as possible. For this purpose, in the present invention, a fluorinated hydrocarbon compound (hereinafter referred to as fluorocarbons) in which fluorine is bonded to a carbon chain is used as a lubricant applied to the surface of a metal ferromagnetic thin film. Furthermore, in order to achieve a sufficiently low coefficient of friction even at low sliding speeds, the lubricant according to the invention contains -SO 3 Me (Me is K or Na), -
It has at least one active group selected from SO 2 F, -COONH 4 , -COOH and -SO 3 H, and the coating amount thereof is 1 to 100 mg/m 2 . With such a configuration, the magnetic recording medium according to the present invention exhibits good running characteristics because the friction between the metal ferromagnetic thin film and the various sliding members with which the metal ferromagnetic thin film slides is reduced. Lubricants made of fluorocarbons having active groups as described above are unsuitable for use as a top coat layer in conventional coating-type magnetic recording media. That is, conventional coated magnetic recording media are constructed by coating a magnetic coating material mainly consisting of ferromagnetic powder and an organic binder on a non-magnetic support. When a lubricant made of fluorocarbons having active groups as described above is applied as a top coat layer to the surface of the magnetic layer having such a structure, the active groups are adsorbed to the ferromagnetic powder and bonded to the carbon chains. Due to the high electronegativity of the fluorine, the binder is almost completely shielded from the ferromagnetic powder. This increases the amount of powder falling off when the magnetic recording medium slides. In contrast, in the magnetic recording medium of the present invention in which the magnetic layer is composed of a metal ferromagnetic thin film that does not contain an organic binder, a lubricant made of fluorocarbons having active groups as described above is used without the risk of powder falling off. It can be used as an effective top coat layer. In the present invention, the coating amount of the fluorocarbons is approximately 1 to 100 mg/ m2 , particularly 2 to 20 mg/m2.
Preferably it is mg/ m2 . This application amount is 1mg/
If it is less than m 2 , the effect of improving running performance according to the present invention will not be apparent. On the other hand, if it is more than 100mg/ m2 ,
The surface tension of this lubricant layer (top coat layer) causes it to stick to the sliding member, which may result in poor running performance.Also, the lubricant is not adsorbed to the surface of the metal ferromagnetic thin film and may peel off. Therefore, this peeled part is interposed between the magnetic recording medium (for example, magnetic tape) and various sliding members such as the head drum, magnetic head, tape guide, etc., and the gap of the head clock (magnetic head is insulated). Further, since a spacing is created between the magnetic head and the magnetic recording medium, the electromagnetic conversion characteristics deteriorate. The non-magnetic support, which is the base of the magnetic recording medium according to the present invention, preferably has a thickness of about 4 to 25 μm. Materials include polyesters such as acetate, polyethylene, polyethylene terephthalate, and polyethylene-2,6-naphthalate, and polyolefins such as polypropylene. class, cellulose triacetate,
Cellulose derivatives such as cellulose diacetate, plastics such as polyimide, polyamide, and polycarbonate, nonmagnetic metals such as Cu, Al, Zn, and Al2O3 , and ceramics such as glass, porcelain, and earthenware are used. On this non-magnetic support, plating, vapor deposition, sputtering, ion plating, etc.
A metal ferromagnetic thin film of about 500 to 2000 Å consisting of Fe, Co, Co-Ni, Co-Cr, Fe-Ni, etc. is formed. Note that the present invention is also applicable to magnetic recording media other than magnetic tapes, such as magnetic disks. Next, the present invention will be explained with reference to experimental examples. Experimental example Co was deposited on a 14μ thick polyethylene terephthalate film by the so-called oblique evaporation method.
A 1000 Å metal ferromagnetic thin film was formed. Note that the oblique evaporation method is a method in which a evaporation beam is incident on the surface of a nonmagnetic support from a direction inclined at a predetermined angle, thereby aligning the magnetic anisotropy of the magnetic layer in a predetermined direction. , and its coercive force can be increased. Next, on the surface of the metal ferromagnetic thin film, B ~
6 mg/m 2 of 1% Freon solution of each compound shown as L
A magnetic tape was prepared by coating the material at a ratio of . In addition,
In Experimental Example A, nothing was applied to the surface of the metal ferromagnetic thin film. Each of the magnetic tapes thus obtained was subjected to a friction test, and the respective friction coefficients were measured. This friction test was conducted as follows. That is, each sample tape, one end of which was connected to a tension gauge, was brought into sliding contact with a drum made of 0.1S stainless steel, and the tapes were reciprocated with a tension of 50 g applied thereto. Tape width is approximately 12.7mm, running speed is 1mm/
It was hot in sec. The experiment was conducted at a temperature of 20°C and a relative humidity of 60%. The results are shown in the table below, and the friction coefficient remained almost unchanged even after 100 runs.
【表】【table】
【表】
この結果から分るように、−SO3Me（MeはＫ又
はNa）、−SO2F、−COONH4、−COOH、又は−
SO3Hを活性基として有するフルオーカーボン類
からなる潤滑剤を用いた本発明の実施例において
は、比較例と比べて、磁気テープ表面の摩擦係数
を小さくすることができ、その走行性を改善する
ことができる。[Table] As can be seen from this result, -SO 3 Me (Me is K or Na), -SO 2 F, -COONH 4 , -COOH, or -
In the example of the present invention using a lubricant made of fluorocarbons having SO 3 H as an active group, the friction coefficient of the magnetic tape surface can be reduced compared to the comparative example, and its running performance can be improved. It can be improved.
Claims (1)
なる磁気記録媒体において、−SO3Me（MeはＫ又
はNa）、−SO2F、−COONH4、−COOH及び−
SO3Hからなる群より選ばれた少なくとも１種の
活性基を有するフツ化炭化水素化合物からなる潤
滑剤が前記金属強磁性薄膜の表面にトツプコート
層として１〜100mgの割合で塗布されていること
を特徴とする磁気記録媒体。1. In a magnetic recording medium formed by forming a metal ferromagnetic thin film on a nonmagnetic support, -SO 3 Me (Me is K or Na), -SO 2 F, -COONH 4 , -COOH and -
A lubricant made of a fluorinated hydrocarbon compound having at least one active group selected from the group consisting of SO 3 H is applied as a top coat layer to the surface of the metal ferromagnetic thin film at a ratio of 1 to 100 mg. A magnetic recording medium characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56127996A JPS5829147A (en) | 1981-08-15 | 1981-08-15 | Magnetic recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56127996A JPS5829147A (en) | 1981-08-15 | 1981-08-15 | Magnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5829147A JPS5829147A (en) | 1983-02-21 |
| JPH0319602B2 true JPH0319602B2 (en) | 1991-03-15 |
Family
ID=14973867
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56127996A Granted JPS5829147A (en) | 1981-08-15 | 1981-08-15 | Magnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5829147A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6066326A (en) * | 1983-09-21 | 1985-04-16 | Hitachi Condenser Co Ltd | Magnetic recording medium |
| JPH0619834B2 (en) * | 1984-06-25 | 1994-03-16 | 日本電信電話株式会社 | Method of manufacturing magnetic recording medium |
| JPS62200524A (en) * | 1986-02-26 | 1987-09-04 | Hoya Corp | Magnetic recording medium |
| JPH0734258B2 (en) * | 1986-04-03 | 1995-04-12 | ホ−ヤ株式会社 | Magnetic disk |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5589375A (en) * | 1978-12-27 | 1980-07-05 | Asahi Glass Co Ltd | Antistatic agent for reproducing and recording material |
| JPS5589376A (en) * | 1978-12-27 | 1980-07-05 | Asahi Glass Co Ltd | Antistaic agent composition for reproducing and recording material |
| JPS55144079A (en) * | 1979-04-27 | 1980-11-10 | Asahi Glass Co Ltd | Surface-treating agent for record-reproductive material |
| JPS56169224A (en) * | 1980-05-30 | 1981-12-25 | Hitachi Ltd | Manufacture of magnetic recording medium |
| JPS57200939A (en) * | 1981-06-01 | 1982-12-09 | Matsushita Electric Ind Co Ltd | Magnetic recording medium |
| JPS57200940A (en) * | 1981-06-01 | 1982-12-09 | Matsushita Electric Ind Co Ltd | Magnetic recording medium |
-
1981
- 1981-08-15 JP JP56127996A patent/JPS5829147A/en active Granted
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5589375A (en) * | 1978-12-27 | 1980-07-05 | Asahi Glass Co Ltd | Antistatic agent for reproducing and recording material |
| JPS5589376A (en) * | 1978-12-27 | 1980-07-05 | Asahi Glass Co Ltd | Antistaic agent composition for reproducing and recording material |
| JPS55144079A (en) * | 1979-04-27 | 1980-11-10 | Asahi Glass Co Ltd | Surface-treating agent for record-reproductive material |
| JPS56169224A (en) * | 1980-05-30 | 1981-12-25 | Hitachi Ltd | Manufacture of magnetic recording medium |
| JPS57200939A (en) * | 1981-06-01 | 1982-12-09 | Matsushita Electric Ind Co Ltd | Magnetic recording medium |
| JPS57200940A (en) * | 1981-06-01 | 1982-12-09 | Matsushita Electric Ind Co Ltd | Magnetic recording medium |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5829147A (en) | 1983-02-21 |
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