JP2547994B2 - Magnetic recording media - Google Patents
Magnetic recording mediaInfo
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- JP2547994B2 JP2547994B2 JP62006094A JP609487A JP2547994B2 JP 2547994 B2 JP2547994 B2 JP 2547994B2 JP 62006094 A JP62006094 A JP 62006094A JP 609487 A JP609487 A JP 609487A JP 2547994 B2 JP2547994 B2 JP 2547994B2
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- magnetic
- glass
- substrate
- thin film
- magnetic recording
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Description
【発明の詳細な説明】 技術分野 本発明は磁気記録媒体に関し、特に磁気デイスク装置
で使用されるガラス基板型磁気記録媒体に関する。TECHNICAL FIELD The present invention relates to a magnetic recording medium, and more particularly to a glass substrate type magnetic recording medium used in a magnetic disk device.
従来技術 磁気デイスク記録装置の大容量化に伴つて、磁気特
性、記録密度の点で塗布型磁気デイスクより有利なスパ
ツタ型磁気デイスクが注目されている。塗布型磁気デイ
スクでは磁性層厚が１〜２μｍ程度と比較的厚いため、
デイスク媒体の表面性は基板の表面性に著しく影響され
るということはない。これに対して、スパツタ型磁気デ
イスクでは磁性層厚が0.5μｍ以下と薄いため、基板の
表面性がデイスク媒体の表面性に著しく影響を及ぼす。
従つて、表面精度の優れた基板を用いることにより、薄
膜型磁気デイスク媒体の表面性を向上させることができ
る。その結果、磁気ヘツドの浮上量を減少させることが
でき、記録密度の向上が可能となる。2. Description of the Related Art With the increase in capacity of magnetic disk recording devices, attention has been paid to spatter type magnetic disks, which are more advantageous than coating type magnetic disks in terms of magnetic characteristics and recording density. The coating type magnetic disk has a relatively large magnetic layer thickness of about 1 to 2 μm.
The surface property of the disk medium is not significantly affected by the surface property of the substrate. On the other hand, in the sputter type magnetic disk, since the magnetic layer thickness is as thin as 0.5 μm or less, the surface property of the substrate remarkably affects the surface property of the disk medium.
Therefore, the surface property of the thin film magnetic disk medium can be improved by using the substrate having excellent surface accuracy. As a result, the flying height of the magnetic head can be reduced, and the recording density can be improved.
スパツタ型磁気デイスクにおいては、アルミ合金上に
50μｍ程度のNi−Ｐめつき層を形成し、この表面を研磨
したもの、あるいは、アルシ合金表面を陽極酸化して厚
さ２μｍ程度のアルマイト硬化層を形成し、さらにアル
マイト表面を研磨したものを基板としている。これらの
基板では表面粗さ（Rmax）が0.15μｍ程度の表面が得ら
れる。On a spatter type magnetic disc
A Ni-P plating layer having a thickness of about 50 μm is formed and the surface is polished, or an alumite surface is anodized to form a hardened alumite layer having a thickness of about 2 μm, and the alumite surface is further polished. It is used as a substrate. With these substrates, a surface having a surface roughness (Rmax) of about 0.15 μm can be obtained.
これらの基板上に磁性薄膜を形成する場合、例えばCo
−Niを主成分とする磁性薄膜を形成する場合には、基板
上にCrを2000Å程度スパツタ成膜し、この上にCo−Niを
主成分とする磁性薄膜を1000Å程度スパツタし、更にＣ
等の保護潤滑膜を200Å程度形成する。このようにして
得られた媒体の表面は、基板の表面性が反映されて、表
面粗さ（Rmax）が0.15μｍ程度である。酸化鉄を主成分
とする磁性薄膜を形成する場合には、Feを主成分とする
ターゲツトをAr＋O2雰囲気中でスパツタし、α−Fe2O3
を主成分とするスパツタ膜を基板上に2000Å程度成膜す
る。これを還元性雰囲気中で300℃程度に加熱し、α−F
e2O3を主成分とする膜をFe2O4を主成分とする膜とし、
更に酸化性雰囲気中で300℃程度に加熱して、γ−Fe2O3
を主成分とする膜とする。この上に更に保護潤滑膜を形
成し媒体としている。このようにして得られた媒体の表
面も、基板の表面性が反映されて、表面粗さ（Rmax）が
0.15μｍ程度である。When forming a magnetic thin film on these substrates, for example, Co
When forming a magnetic thin film containing -Ni as a main component, Cr is deposited on the substrate by about 2000 Å, and a magnetic thin film containing Co-Ni as a main component is deposited on this by about 1000 Å, and further C
Form a protective lubrication film such as 200 Å. The surface roughness (Rmax) of the surface of the medium thus obtained reflects the surface property of the substrate and is about 0.15 μm. When a magnetic thin film containing iron oxide as a main component is formed, a target containing Fe as a main component is sputtered in an Ar + O 2 atmosphere and α-Fe 2 O 3
A sputtered film containing as a main component is formed on the substrate to a thickness of about 2000Å. This is heated to about 300 ℃ in a reducing atmosphere, and α-F
A film containing e 2 O 3 as a main component is a film containing Fe 2 O 4 as a main component,
Further, heat to about 300 ° C in an oxidizing atmosphere to produce γ-Fe 2 O 3
Is a film containing as a main component. A protective lubricating film is further formed on this to serve as a medium. The surface roughness (Rmax) of the surface of the medium thus obtained also reflects the surface property of the substrate.
It is about 0.15 μm.
アルミ合金上にNi−Ｐめつき層を形成し、この表面を
研磨した基板においては、Ni−Ｐめつきを行なう前にア
ルミ合金表面を活性化処理する必要があり、基板形成の
工程が複雑となる。また、活性化処理以降の工程が基板
価格の50％以上を占め、基板が割高になる。更にNi−Ｐ
めつき層は150℃以上に加熱すると結晶化して磁性を持
つようになるため、磁性酸化鉄膜を形成する時のように
加熱工程が必要な場合はこの基板を使用することができ
ない。In a substrate in which a Ni-P plating layer is formed on an aluminum alloy and the surface is polished, it is necessary to activate the aluminum alloy surface before performing Ni-P plating, which complicates the substrate forming process. Becomes Moreover, the process after the activation process occupies 50% or more of the board price, and the board becomes expensive. Further Ni-P
Since the plating layer is crystallized and becomes magnetic when heated to 150 ° C. or higher, this substrate cannot be used when a heating step is required as in the case of forming a magnetic iron oxide film.
アルミ合金上にアルマイト皮膜を形成した基板は、熱
処理を行なつた場合、アルミ合金とアルマイト皮膜との
熱膨張係数の差により発生する応力のためにアルマイト
皮膜にクラツクが生じやすいという欠点がある。そのた
め磁性酸化鉄膜を形成する際の加熱温度は300℃程度以
下に限定されてしまう。更に、アルマイト皮膜には多数
の通電孔が存在し、多孔質構造となつている。そのため
この基体上に薄膜磁性層を形成した場合には通電孔の部
分に磁気的欠陥が生じやすく、また表面精度もRmaxが0.
15μｍ程度と充分なものではない。A substrate having an alumite coating formed on an aluminum alloy has a drawback that cracks are likely to occur in the alumite coating due to the stress generated due to the difference in thermal expansion coefficient between the aluminum alloy and the alumite coating when heat-treated. Therefore, the heating temperature for forming the magnetic iron oxide film is limited to about 300 ° C. or lower. Further, the alumite coating has a large number of current-carrying holes and has a porous structure. Therefore, when a thin-film magnetic layer is formed on this substrate, magnetic defects are likely to occur in the current-carrying holes, and the surface accuracy has a Rmax of 0.
It is not sufficient, about 15 μm.
上記欠点に鑑み、本発明者らは表面粗さ（Rmax）が10
0Å以下（望ましくは50Å以下）となるように超精密表
面加工されたガラス基板上に磁気記録用磁性薄膜を形成
した磁気記録媒体、及び、表面の少なくとも一部分を強
化し、又は表面粗さ（Rmax）が100Å以下（望ましくは5
0Å以下）となるように超精密表面加工されたガラス基
板上に磁気記録用磁性薄膜を形成した磁気記録媒体を開
発し、特許出願を行なつた。（特願昭60−183022） 従来技術の問題点 上記特許出願において提案されたガラス基板は、強度
が高く、寸法精度の高いアルミノ珪酸ガラス、石英ガラ
ス、チタン珪酸ガラスなどの高級ガラスを用いたもので
あり、しかも結晶質分の存在しないものを要した。これ
らのガラス基板は満足な機能特性や表面性を有するけれ
ども、高価であり、大量な需要があるデイスク型磁気記
録媒体においてはコストの面で不利となる。In view of the above drawbacks, the present inventors have a surface roughness (Rmax) of 10
A magnetic recording medium in which a magnetic thin film for magnetic recording is formed on a glass substrate that has been subjected to ultra-precision surface processing so as to be 0 Å or less (preferably 50 Å or less), and at least a part of the surface is strengthened or the surface roughness (Rmax ) Is less than 100Å (preferably 5
We have developed a magnetic recording medium in which a magnetic thin film for magnetic recording is formed on a glass substrate that has been subjected to ultra-precision surface processing so that it becomes 0 Å or less), and filed a patent application. (Japanese Patent Application No. 60-183022) Problems of Prior Art The glass substrate proposed in the above patent application uses high-grade glass such as aluminosilicate glass, quartz glass, and titanium silicate glass having high strength and high dimensional accuracy. In addition, a crystalline material that does not exist was required. Although these glass substrates have satisfactory functional characteristics and surface properties, they are expensive and are disadvantageous in cost in a disk type magnetic recording medium which is in large demand.
（発明の目的） 従つて、本発明の目的は、安価なガラスを磁気記録媒
体の非磁性基板として用い、しかも高級ガラスを用いた
ときと同様な機械強度及び表面精度を有する磁気記録媒
体を提供することにある。(Object of the Invention) Accordingly, an object of the present invention is to provide a magnetic recording medium which uses inexpensive glass as a non-magnetic substrate of a magnetic recording medium and has the same mechanical strength and surface accuracy as when high-grade glass is used. To do.
発明の概要 本発明は非磁性基板上に磁性薄膜を形成してなる磁気
記録媒体において、非磁性基板がソーダ石英ガラス、鉛
アルカリガラス、および硼珪酸ガラスより選んだガラス
板表面の少なくとも一部を強化処理して強化層を形成
し、その上に非磁性薄膜の下地層を形成して成ることを
特徴とする。この場合に、非磁性薄膜は、SiO2、Al
2O3、TiO2等の無機質材料より構成される。SUMMARY OF THE INVENTION The present invention is a magnetic recording medium in which a magnetic thin film is formed on a non-magnetic substrate, wherein the non-magnetic substrate has at least a part of a glass plate surface selected from soda quartz glass, lead alkali glass, and borosilicate glass. It is characterized in that a strengthening layer is formed by strengthening treatment, and an underlayer of a non-magnetic thin film is formed thereon. In this case, the non-magnetic thin film is SiO 2 , Al.
It is composed of inorganic materials such as 2 O 3 and TiO 2 .
発明の構成 本発明は非磁性基板としてソーダ石灰ガラス、鉛アル
カリガラス、硼珪酸ガラスを用いる。しかし、これらの
ガラスは安定性が悪く、その表面を研摩してその上に直
接磁性金属薄膜を形成すると、ガラス中のアルカリ、ア
ルカリ土類のイオンが表面に析出し、これが磁性薄膜に
移行混入し、磁気特性、特に角型比（Br/Bm）を劣化さ
せる問題が生じる。先に述べたように、酸化鉄薄膜を形
成するために熱処理工程を行う場合にはこの劣化傾向は
さらに大きくなる。Structure of the Invention The present invention uses soda-lime glass, lead-alkali glass, or borosilicate glass as the non-magnetic substrate. However, these glasses have poor stability, and when the surface of the glass is polished and a magnetic metal thin film is directly formed on it, alkali and alkaline earth ions in the glass are deposited on the surface, which migrates into the magnetic thin film. However, there arises a problem of deteriorating the magnetic characteristics, particularly the squareness ratio (Br / Bm). As described above, when the heat treatment process is performed to form the iron oxide thin film, this deterioration tendency becomes even greater.
そこで、本発明は上記の安価なガラス基板を硝酸カリ
ウム溶融塩等によりイオン置換するなどして強化処理し
た後、その表面に下地層としてSiO2、Al2O2、TiO2等の
非磁性薄膜を形成する。この下地層はスパツタ法により
形成することが望ましく、こうすることにより緻密な膜
が形成されるため、ガラス中のアルカリやアルカリ土類
のイオンが磁性薄膜中へ拡散して来ることはなくなる。Therefore, the present invention, after the strengthening treatment such as ion substitution of the inexpensive glass substrate with a molten salt of potassium nitrate or the like, a nonmagnetic thin film such as SiO 2 , Al 2 O 2 or TiO 2 on the surface thereof as an underlayer. Form. It is desirable to form this underlayer by a sputtering method, and since a dense film is formed by this method, alkali or alkaline earth ions in the glass will not diffuse into the magnetic thin film.
ガラス基板の表面粗さはその上に形成される下地層及
び磁性薄膜を介して磁性薄膜の表面粗さに反映されるか
ら、精密に仕上げるべきであり、例えばコロイダルシリ
カを含む研磨液の機械的及び化学的研磨作用を利用して
研磨することにより、表面粗さ（Rmax）が40〜100Åと
なるように研磨する。40Å未満ではヘツド浮上を阻害す
る吸着作用が生じるが磁性表面の熱処理によりこの問題
を防止できる（この点は本出願と同時出願の主題とし
た）。従つて、ガラス基板は表面粗さ100Å以下の高精
度に仕上げれば良い。Since the surface roughness of the glass substrate is reflected on the surface roughness of the magnetic thin film through the underlying layer and the magnetic thin film formed on it, it should be finished with precision, for example, the mechanical strength of the polishing liquid containing colloidal silica. Also, by polishing using a chemical polishing action, the surface roughness (Rmax) is 40 to 100 Å. If it is less than 40 Å, an adsorption effect that hinders head levitation occurs, but this problem can be prevented by heat treatment of the magnetic surface (this point was the subject of the present application and the simultaneous application). Therefore, the glass substrate should be finished with high accuracy with a surface roughness of 100Å or less.
また、ガラス基板の表面の少なくとも一部に強化処理
を施してあるので、デイスクとして高速回転を受ける場
合に生じる大きい遠心力に対して、或いはその他の外力
に対して大きい抵抗力を与えることができる。例えば表
面強化は一般的にガラス表面のイオンをガラス転移点以
下の温度でより大きなイオンに置換することにより行な
われる。イオン置換方法としては450℃程度に加熱した
硝酸カリウム溶液塩中にガラスを浸しておくことなどに
より行なわれる。この置換により、表面に急峻な分布を
持つ圧縮応力層が形成されガラス基板表面の強化がなさ
れる。この応力層の厚みはイオン置換時の温度、時間を
制御することにより10〜200μｍにする。Further, since at least a part of the surface of the glass substrate is subjected to a strengthening treatment, it is possible to give a large resistance force to a large centrifugal force generated when the disk is subjected to high-speed rotation or to other external force. . For example, surface strengthening is generally performed by replacing the ions on the glass surface with larger ions at temperatures below the glass transition temperature. The ion substitution method is carried out by immersing the glass in a salt of potassium nitrate solution heated to about 450 ° C. By this substitution, a compressive stress layer having a steep distribution is formed on the surface, and the glass substrate surface is strengthened. The thickness of this stress layer is set to 10 to 200 μm by controlling the temperature and time during ion substitution.
表面強化する部分としては、磁気ディスクで考える
と、内径縁部、内径縁部周辺、外径縁部、外径縁部周
辺、これらの適当な組合せ、全面などが考えられる。Considering a magnetic disk, the portion to be surface-reinforced may be an inner diameter edge portion, an inner diameter edge portion, an outer diameter edge portion, an outer diameter edge portion, an appropriate combination thereof, or the entire surface.
そして、ガラス基板を用いると400℃程度までは充分
に使用可能なため磁性酸化鉄膜を形成する場合のように
加熱工程が必要の場合は特に有効に使用することができ
る。When a glass substrate is used, it can be sufficiently used up to about 400 ° C., so that it can be particularly effectively used when a heating step is required as in the case of forming a magnetic iron oxide film.
一方、ガラス基板の表面に形成される下地層の厚さは
200〜5000Åが好適であり、スパツタ法によつて均一な
膜として形成する。200Å以下では十分なバリヤ効果が
なく、5000Å以上であると時間がかかりまた効果が飽和
する。On the other hand, the thickness of the underlayer formed on the surface of the glass substrate is
200 to 5000Å is suitable, and a uniform film is formed by the sputtering method. If it is less than 200Å, there is no sufficient barrier effect, and if it is more than 5000Å, it takes time and the effect is saturated.
次に、本発明の実施例を説明する。 Next, examples of the present invention will be described.
外形130mm、内径40mm、厚さ1.9mmの円板状の各種ガラ
ス基板に、SiO2、Al2O3、及びTiO2の下地層をスパツタ
法により1000Å形成した。この上に、鉄をターゲツトと
しAr＋O2雰囲気（混合比50％、真空度５×10-3Torr）で
スパツタすることによりα−Fe2O3膜を2000Å形成し
た。次に水素気流中で360℃、２時間、還元してFe3O4膜
とし、更に空気中310℃１時間酸化してγ−Fe2O3膜とし
て磁気デイスクを完成させた。このデイスクの角形比Br
/Bmを表１に示す。比較のため、下地層を形成しない場
合の角形比も表１に示してある。なおアルミノ珪酸ガラ
スの例は前に引用した先願の例であり、本発明がかなり
高品質であることを立証するものである。An underlayer of SiO 2 , Al 2 O 3 , and TiO 2 was formed on a disk-shaped glass substrate having an outer diameter of 130 mm, an inner diameter of 40 mm, and a thickness of 1.9 mm by 1000 Å by a sputtering method. Over this was iron and Tagetsuto Ar + O 2 atmosphere (mixing ratio 50%, the degree of vacuum 5 × 10 -3 Torr) and α-Fe 2 O 3 film by sputter in to 2000Å formed. Next, the magnetic disk was completed by reducing in a hydrogen stream at 360 ° C. for 2 hours to form a Fe 3 O 4 film, and further oxidizing in air at 310 ° C. for 1 hour to form a γ-Fe 2 O 3 film. Squareness of this disk Br
/ Bm is shown in Table 1. For comparison, Table 1 also shows the squareness ratio when the underlayer is not formed. The example of aluminosilicate glass is an example of the prior application cited above, and proves that the present invention has a considerably high quality.
参考例と同一形状のデイスク円板状ソーダ石灰ガラス
基板の表面強化を行なつた。強化は、硝酸カリウム溶融
塩を450℃にし、その中に10時間浸すことにより行なつ
た。強化層厚は60μｍであつた。この基板をコロイダル
シリカを含む研磨液を使用してメカノケミカルポリシン
グを30分間行なつたところ、基板の表面粗さ（Rmax）は
17Åとなつた。The surface of a disk-shaped soda-lime glass substrate having the same shape as that of the reference example was strengthened. The strengthening was performed by bringing the molten salt of potassium nitrate to 450 ° C. and immersing it in it for 10 hours. The thickness of the reinforcing layer was 60 μm. When this substrate was subjected to mechanochemical polishing for 30 minutes using a polishing liquid containing colloidal silica, the surface roughness (Rmax) of the substrate was
It was 17Å.
このようにして形成した基板は、20,000rpmで回転さ
せても破壊されることはなく、3600rpmで使用するデイ
スク基板としては充分な強度を持つていることがわか
る。It can be seen that the substrate thus formed is not destroyed even when rotated at 20,000 rpm, and has sufficient strength as a disk substrate used at 3600 rpm.
この基板の上に参考例と同様にSiO2下地層、γ−Fe2O
3磁性層を形成したところ、角形比0.76、表面粗さ（Rma
x）45Åとなり、磁気特性的にもヘツド浮上安定性も良
好な磁気デイスクが得られた。On top of this substrate, as in the reference example, an SiO 2 underlayer, γ-Fe 2 O
When three magnetic layers were formed, the squareness ratio was 0.76 and the surface roughness (Rma
x) 45Å, and a magnetic disk with good magnetic characteristics and head floating stability was obtained.
角形比を表１に示した。 The squareness ratio is shown in Table 1.
他のガラス材料と下地を使用して実施例と同様にして
実験を行った。ディスクの強度は実施例と同様であっ
た。また、角形比を表１に示した。Experiments were conducted in the same manner as in the examples using other glass materials and the base. The strength of the disc was similar to that of the example. The squareness ratio is shown in Table 1.
強化層及び下地層を形成することにより、角形比が格
段に向上する。アルミノ珪酸ガラスには及ばないが、実
用上問題ないSiO2、Al2O3、TiO2の中ではSiO2が比較的
良い 作用効果 以上のように、本発明によると通常のガラス基板の表
面に非磁性の無機酸化物膜をスパッタ形成し、表面の少
なくとも一部に強化処理を施すことにより、下地層のみ
を設けた場合と比べガラス中のイオンの磁性膜中への拡
散を一層抑制できることが分かる。以上より、特性の良
い磁性薄膜を形成することができる利点が得られ、更に
機械的にも補強され、安価で高性能な磁気記録媒体を提
供できる。 The squareness ratio is remarkably improved by forming the reinforcing layer and the underlayer. Although not as good as aluminosilicate glass, SiO 2 is relatively good among SiO 2 , Al 2 O 3 and TiO 2 which is not a problem for practical use. By forming a non-magnetic inorganic oxide film by sputtering and subjecting at least part of the surface to a strengthening treatment, it is possible to further suppress the diffusion of ions in the glass into the magnetic film as compared with the case where only the underlayer is provided. I understand. As described above, it is possible to provide an advantage that a magnetic thin film having excellent characteristics can be formed, mechanically reinforced, and an inexpensive and high-performance magnetic recording medium.
Claims (3)
気記録媒体において、非磁性基板がソーダ石灰ガラス、
鉛アルカリガラス、及び硼珪酸ガラスより選んだガラス
板表面の少なくとも一部に強化層を形成し、その上に非
磁性薄膜の下地層を形成して成ることを特徴とする、磁
気記録媒体。1. A magnetic recording medium comprising a magnetic thin film formed on a non-magnetic substrate, wherein the non-magnetic substrate is soda-lime glass.
A magnetic recording medium comprising a reinforcing layer formed on at least a part of the surface of a glass plate selected from lead-alkali glass and borosilicate glass, and an underlayer of a nonmagnetic thin film formed thereon.
ばれた膜より成る前記第１項記載の磁気記録媒体。2. The magnetic recording medium according to claim 1, wherein the non-magnetic thin film is a film selected from SiO 2 , Al 2 O 3 and TiO 2 .
融塩等によりイオン置換されるものである前記第１又は
第２項記載の磁気記録媒体。3. The magnetic recording medium according to claim 1, wherein the surface of the glass plate is strengthened by ion substitution with a molten salt of potassium nitrate or the like.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62006094A JP2547994B2 (en) | 1987-01-16 | 1987-01-16 | Magnetic recording media |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62006094A JP2547994B2 (en) | 1987-01-16 | 1987-01-16 | Magnetic recording media |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63175220A JPS63175220A (en) | 1988-07-19 |
| JP2547994B2 true JP2547994B2 (en) | 1996-10-30 |
Family
ID=11628927
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62006094A Expired - Lifetime JP2547994B2 (en) | 1987-01-16 | 1987-01-16 | Magnetic recording media |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2547994B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63316314A (en) * | 1987-06-18 | 1988-12-23 | Asahi Glass Co Ltd | Glass substrate for magnetic disk |
| US5774783A (en) * | 1995-03-17 | 1998-06-30 | Fujitsu Limited | Magnetic recording medium |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2456894C3 (en) * | 1974-12-02 | 1978-04-06 | Jenaer Glaswerk Schott & Gen., 6500 Mainz | Inorganic, vitreous material for use in an ion exchange for the purpose of generating a refractive index gradient while largely avoiding a change in the coefficient of thermal expansion |
| JPS5835639B2 (en) * | 1980-04-21 | 1983-08-03 | 株式会社 キヨウシン | Solid fuel manufacturing method |
| JPS6065746A (en) * | 1983-09-20 | 1985-04-15 | Nippon Sheet Glass Co Ltd | Manufacture of glass plate for transparent electrode |
| JPS61101433A (en) * | 1984-10-20 | 1986-05-20 | Nippon Sheet Glass Co Ltd | Glass composition for chemical reinforcing |
| JPS61205640A (en) * | 1985-03-08 | 1986-09-11 | Central Glass Co Ltd | Chemical reinforcement of float glass |
| JPS61222021A (en) * | 1985-03-28 | 1986-10-02 | Hoya Corp | Magnetic recording medium |
| JPS61223826A (en) * | 1985-03-29 | 1986-10-04 | Alps Electric Co Ltd | Liquid crystal display element |
| JPS6273426A (en) * | 1985-09-26 | 1987-04-04 | Hoya Corp | Production of magnetic recording medium |
| JPS62209719A (en) * | 1986-03-10 | 1987-09-14 | Toshiba Corp | Magnetic recording medium |
| JPH0823930B2 (en) * | 1986-10-28 | 1996-03-06 | 日本板硝子株式会社 | Magnetic recording media |
-
1987
- 1987-01-16 JP JP62006094A patent/JP2547994B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63175220A (en) | 1988-07-19 |
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