JPH0816978B2 - Magnetic disk - Google Patents
Magnetic diskInfo
- Publication number
- JPH0816978B2 JPH0816978B2 JP61000852A JP85286A JPH0816978B2 JP H0816978 B2 JPH0816978 B2 JP H0816978B2 JP 61000852 A JP61000852 A JP 61000852A JP 85286 A JP85286 A JP 85286A JP H0816978 B2 JPH0816978 B2 JP H0816978B2
- Authority
- JP
- Japan
- Prior art keywords
- powder
- magnetic
- undercoat layer
- layer
- magnetic disk
- 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
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は磁性層の厚さが５μｍ以下の高密度記録に
適した磁気ディスクに関し、さらに詳しくは耐久性に優
れた前記の磁気ディスクに関する。The present invention relates to a magnetic disk suitable for high-density recording having a magnetic layer having a thickness of 5 μm or less, and more particularly to the above magnetic disk having excellent durability.
磁気ディスクの磁性層は、通常、磁性粉末、結合剤成
分、有機溶剤およびその他の必要成分からなる磁性塗料
をポリエステルフィルムなどの基体上に塗布、乾燥して
つくられ、このようにしてつくられる磁性層の基体に対
する接着性を改善し、また表面電気抵抗を低減するた
め、ポリエステル樹脂を主体とした下塗り層を磁性層と
基体との間に形成したり、またカーボンブラックなどの
導電性粉末を均一に分散させた下塗り層を設けることが
行われている。（特開昭55-84040号） 〔発明が解決しようとする問題点〕 ところが、磁気記録の高密度記録化に対応して、磁性
層の厚さを可及的に薄くすると、減磁損失が少なくなっ
て記録密度が高密度化される反面、磁性層中に含有され
る充填剤などがしだいに少なくなり、磁性層の機械的強
度が低下して充分な耐久性が得られなくなる。特に10℃
以下の低温の場合は、磁性層にかかる磁気ヘッドの摺動
応力の影響が大きく、磁性層が短時間で破壊されること
があり、耐久性が大きく低下する。また、磁気ディスク
においては、高速回転するため内周側より外周側の線速
度が大きく、磁気ヘッドと磁気ディスクの磁性層表面に
おける摺接条件が外周側において厳しくなるなど、磁気
テープと異なって耐久性がシビアに要求され、さらに、
製造工程において、円盤状に打ち抜くときは、磁性層で
使用する結合剤樹脂や非磁性粉末の使用割合などによっ
て、粘着や粉落ちなどが生じる場合があり、不良品が生
じたり、ドロップアウト事故が生じたりする。The magnetic layer of a magnetic disk is usually prepared by applying a magnetic coating material comprising a magnetic powder, a binder component, an organic solvent and other necessary components on a substrate such as a polyester film and drying it. In order to improve the adhesion of the layer to the substrate and to reduce the surface electric resistance, an undercoat layer mainly composed of polyester resin is formed between the magnetic layer and the substrate, and a conductive powder such as carbon black is uniformly applied. It has been practiced to provide an undercoat layer dispersed in. (JP-A-55-84040) [Problems to be solved by the invention] However, when the thickness of the magnetic layer is made as thin as possible in response to high density recording of magnetic recording, demagnetization loss is reduced. Although the recording density is reduced and the recording density is increased, the filler and the like contained in the magnetic layer are gradually reduced, and the mechanical strength of the magnetic layer is reduced, so that sufficient durability cannot be obtained. Especially 10 ℃
When the temperature is lower than the following, the sliding stress of the magnetic head exerted on the magnetic layer has a great influence, the magnetic layer may be destroyed in a short time, and the durability is greatly reduced. In addition, since the magnetic disk rotates at a high speed, the linear velocity on the outer peripheral side is higher than that on the inner peripheral side, and the sliding conditions on the magnetic layer surface between the magnetic head and the magnetic disk become stricter on the outer peripheral side. Sex is severely demanded,
When punching into a disk shape in the manufacturing process, sticking or powder drop may occur depending on the ratio of binder resin or non-magnetic powder used in the magnetic layer, resulting in defective products or dropout accidents. It happens.
この発明は、かかる現状に鑑み種々検討を行った結果
なされたもので、基体と、この基体上に形成する厚さが
５μｍ以下の塗布型磁性層との間に、Al2O3粉末、α−F
e2O3粉末、CaCO3粉末、MgO粉末、Cr2O3粉末、BaSO4粉
末、BaCO3粉末、ZnO粉末、Cu2O粉末、CuO粉末、TiO2粉
末から選ばれる平均粒子径が0.1〜３μｍの非磁性粉末
を含む下塗り層を設け、さらに、この非磁性粉末の含有
量を下塗り層の全固形成分に対して20〜80重量％の範囲
内となるようにすることによって、磁気ヘッドの摺動に
より生じる内部応力を非磁性粉末で分散させ、塗布型の
磁性層の機械的強度を充分に補強し、磁性層の厚さが薄
い場合でも磁性層を補強して、磁性層の耐久性を充分に
向上させ、高密度記録が良好に行えるようにするととも
に、特にシビアな耐久性が要求される磁気ディスクの厚
さが極めて薄い磁性層の耐久層を充分に向上させ、かつ
製造工程で円盤状に打ち抜く際、粘着や粉落ちなどがな
く、不良品が生じたり、ドロップアウト事故が生じたり
することがないようにしたものである。The present invention has been made as a result of various investigations in view of the present situation. Al 2 O 3 powder, α, and α 2 O 3 powder, α are formed between a substrate and a coating type magnetic layer having a thickness of 5 μm or less formed on the substrate. -F
e 2 O 3 powder, CaCO 3 powder, MgO powder, Cr 2 O 3 powder, BaSO 4 powder, BaCO 3 powder, ZnO powder, Cu 2 O powder, CuO powder, the average particle size selected from TiO 2 powder 0.1 An undercoat layer containing 3 μm of non-magnetic powder is provided, and the content of this non-magnetic powder is set within the range of 20 to 80% by weight with respect to the total solid components of the undercoat layer. The internal stress caused by sliding is dispersed with non-magnetic powder, the mechanical strength of the coating type magnetic layer is sufficiently reinforced, and the magnetic layer is reinforced even when the thickness of the magnetic layer is thin, and the durability of the magnetic layer is improved. Of the magnetic disk, which is extremely thin, and which is required to have particularly high durability. When punching out into a disk shape, there is no sticking or powder falling, and defective products may Is obtained, to ensure they are not that out accident or cause.
この発明において、基体上に下塗り層を介して形成さ
れる磁性層は、高密度記録が良好に行えるようにするた
め５μｍ以下にするのが好ましく、これより厚くすると
減磁損失が大きくなって高密度記録が良好に行えない。In the present invention, the magnetic layer formed on the substrate via the undercoat layer preferably has a thickness of 5 μm or less so that high density recording can be performed well. Density recording cannot be performed well.
また、この発明において、基体と磁性層との間に設け
る下塗り層は、平均粒子径が0.1〜３μｍの非磁性粉末
を含有させ、層厚をこれらの非磁性粉末を充分に含有で
きる0.1〜３μｍの厚さにするのが好ましく、このよう
に平均粒子径が0.1〜３μｍの非磁性粉末を含有させた
層厚が0.1〜３μｍの下塗り層を、磁性層と基体との間
に設けると、下塗り層に含有させた非磁性粉末によって
磁気ヘッドの摺動により生じる内部応力を分散すること
ができて、磁性層の機械的強度を充分に補強することが
でき、磁性層の厚みが可及的に薄い場合でも磁性層を充
分に補強して、耐久性を充分に向上することができる。Further, in the present invention, the undercoat layer provided between the substrate and the magnetic layer contains a non-magnetic powder having an average particle diameter of 0.1 to 3 μm, and the layer thickness is 0.1 to 3 μm so that the non-magnetic powder can be sufficiently contained. When the undercoat layer containing the non-magnetic powder having an average particle diameter of 0.1 to 3 μm and having a layer thickness of 0.1 to 3 μm is provided between the magnetic layer and the substrate, The non-magnetic powder contained in the layer can disperse the internal stress generated by sliding of the magnetic head, and can sufficiently reinforce the mechanical strength of the magnetic layer. Even if it is thin, the magnetic layer can be sufficiently reinforced and the durability can be sufficiently improved.
このような下塗り層中に含有させる非磁性粉末として
は、Al2O3粉末、α−Fe2O3粉末、CaCO3粉末、MgO粉末、
Cr2O3粉末、BaSO4粉末、BaCO3粉末、ZnO粉末、Cu2O粉
末、CuO粉末、TiO2粉末から選ばれる平均粒子径が0.1〜
３μｍの非磁性粉末が好ましく使用され、平均粒子径が
0.3〜1.0μｍのものがより好ましく使用される。この種
の非磁性粉末は、磁気テープと違って、特にシビアな耐
久性が要求される磁気ディスクにおいて優れた耐久性向
上効果を発揮する。As the non-magnetic powder contained in such an undercoat layer, Al 2 O 3 powder, α-Fe 2 O 3 powder, CaCO 3 powder, MgO powder,
Cr 2 O 3 powder, BaSO 4 powder, BaCO 3 powder, ZnO powder, Cu 2 O powder, CuO powder, TiO 2 powder has an average particle size of 0.1 ~
A non-magnetic powder of 3 μm is preferably used and has an average particle size of
Those having a thickness of 0.3 to 1.0 μm are more preferably used. Unlike magnetic tapes, this kind of non-magnetic powder exhibits an excellent effect of improving durability especially in magnetic disks that require severe durability.
使用量は、下塗り層の全固形成分に対して20〜80重量
％の範囲内で使用するのが好ましく、これより少なくて
は所期の効果がえられず、また結合剤樹脂が多くなる
と、製造工程において、円盤状に打ち抜くとき、粘着が
起こって不良品となり、多すぎると下塗り層の表面粗さ
が大きくなり、磁性層のノイズ増加の原因となる他、製
造工程において、円盤状に打ち抜くとき、エッジから非
磁性粉末が粉落ちして磁性層に付着し、ドロップアウト
を生じたりする。このとき、磁気テープのように直線的
に切断する場合は、連続的に落ちた粉などを除去するこ
とも容易であっても、一枚づつ打ち抜かれて製造される
磁気ディスクにおいては困難であり、このため、前記の
非磁性粉末を使用量を下塗り層の全固形成分に対して20
〜80重量％の範囲内で使用するのが好ましい。The amount used is preferably within the range of 20 to 80% by weight with respect to the total solid components of the undercoat layer, and the desired effect cannot be obtained if the amount is less than this, and if the binder resin increases, When punching out in a disc shape in the manufacturing process, adhesion occurs and results in defective products, and if it is too much, the surface roughness of the undercoat layer increases, which causes increased noise in the magnetic layer. At this time, non-magnetic powder falls from the edges and adheres to the magnetic layer, resulting in dropout. At this time, when cutting linearly like a magnetic tape, even if it is easy to remove powder that has fallen continuously, it is difficult for magnetic disks manufactured by punching one by one. For this reason, the amount of the non-magnetic powder used is 20 relative to the total solid components of the undercoat layer.
It is preferably used within the range of 80% by weight.
このような非磁性粉末を含む下塗り層は、通常、これ
らの非磁性粉末を、結合剤樹脂および有機溶剤等ととも
に混合分散して下塗り層用塗料を調製し、これをポリエ
ステルフイルムなどの基体上に塗布し、乾燥して形成さ
れる。このようにして形成される下塗り層の層厚は、前
記の非磁性粉末を充分に含有することができるように、
0.1〜３μｍの範囲内にするのが好ましい。An undercoat layer containing such a non-magnetic powder is usually prepared by mixing and dispersing these non-magnetic powders with a binder resin, an organic solvent and the like to prepare a paint for the undercoat layer, which is then applied to a substrate such as a polyester film. It is formed by coating and drying. The thickness of the undercoat layer thus formed is such that the above-mentioned non-magnetic powder can be sufficiently contained,
It is preferably within the range of 0.1 to 3 μm.
ここで、下塗り層に使用される結合剤樹脂としては、
塩化ビニル−酢酸ビニル系共重合体、ポリビニルブチラ
ール樹脂、繊維素系樹脂、ポリウレタン系樹脂、ポリエ
ステル系樹脂、エポキシ系樹脂、ポリエーテル系樹脂、
イソシアネート化合物、放射線硬化型樹脂など従来から
汎用されている結合剤樹脂がいずれも好適に使用され
る。Here, as the binder resin used in the undercoat layer,
Vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, fibrin resin, polyurethane resin, polyester resin, epoxy resin, polyether resin,
Any conventionally used binder resin such as an isocyanate compound or a radiation curable resin is preferably used.
また、有機溶剤としては、アセトン、メチルイソブチ
ルケトン、メチルエチルケトン、シクロヘキサノン、ト
ルエン、酢酸エチル、テトラヒドロフラン、ジメチルホ
ルムアミドなど従来一般に使用される有機溶剤がいずれ
も単独で、或いは二種以上混合して使用される。Further, as the organic solvent, conventionally used organic solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, toluene, ethyl acetate, tetrahydrofuran, and dimethylformamide may be used alone or in combination of two or more. .
下塗り層上の磁性層の形成は、γ−Fe2O3粉末、Fe3O4
粉末、Co含有γ−Fe2O3粉末、Co含有Fe3O4粉末、Fe粉
末、Co粉末、Fe-Ni粉末およびバリウムフェライト、ス
トロンチウムフェライトなどの従来公知の各種磁性粉末
を、結合剤樹脂および有機溶剤等とともに混合分散して
磁性塗料を調製し、この磁性塗料を、基体上に形成した
下塗り層上に塗布、乾燥するなどして形成される。The magnetic layer on the undercoat layer is formed by γ-Fe 2 O 3 powder, Fe 3 O 4
Powder, Co-containing γ-Fe 2 O 3 powder, Co-containing Fe 3 O 4 powder, Fe powder, Co powder, Fe-Ni powder and barium ferrite, various conventionally known magnetic powders such as strontium ferrite, binder resin and It is formed by mixing and dispersing with an organic solvent or the like to prepare a magnetic coating material, applying the magnetic coating material on an undercoat layer formed on a substrate, and drying.
この際、使用する結合剤樹脂および有機溶剤は、前記
の下塗り層を形成する場合に使用したものと同じものが
いずれも好適に使用される。At this time, the same binder resin and organic solvent as those used when forming the undercoat layer are preferably used.
なお、磁性塗料中には、通常使用されている各種添加
剤、たとえば、潤滑剤、分散剤、研磨剤、帯電防止剤な
どを適宜に添加使用してもよい。In addition, various additives that are usually used, such as a lubricant, a dispersant, an abrasive, and an antistatic agent, may be appropriately added and used in the magnetic paint.
次に、この発明の実施例について説明する。 Next, an embodiment of the present invention will be described.
実施例１ ポリエステル樹脂（東洋紡社製；バイロン200）100重量
部 Al2O3粉末（粒子径0.7μｍ） 100 〃 シクロヘキサノン 400 〃 トルエン 400 〃 この組成物をボールミル中で24時間混合分散して下塗
り層用塗料を調整し、これらを75μｍのポリエステルフ
イルムの両面に、乾燥厚が３μｍとなるように、塗布、
乾燥し、カレンダ処理して下塗り層を形成した。Example 1 Polyester resin (manufactured by Toyobo Co., Ltd .; Byron 200) 100 parts by weight Al 2 O 3 powder (particle size 0.7 μm) 100 〃 cyclohexanone 400 〃 toluene 400 〃 This composition was mixed and dispersed in a ball mill for 24 hours to form an undercoat layer. Adjust the paints for coating and apply them to both sides of 75μm polyester film so that the dry thickness is 3μm.
It was dried and calendered to form an undercoat layer.
次いで、このポリエステルフイルム両面の下塗り層上
に、下記組成の磁性塗料を乾燥厚が0.7μｍとなるよう
に、塗布、乾燥し、50℃、10kg/cm2でカレンダ処理して
磁性層を形成した。しかる後、円盤状に打抜き加工処理
して、第１図に示すように、ポリエステルフイルム１の
両面に、下塗り層２および磁性層３を積層形成した磁気
ディスクＡをつくった。Next, a magnetic coating composition having the following composition was applied onto the undercoat layer on both sides of the polyester film, dried to a thickness of 0.7 μm, dried, and calendered at 50 ° C. and 10 kg / cm 2 to form a magnetic layer. . After that, a disk-shaped punching process was performed to prepare a magnetic disk A in which an undercoat layer 2 and a magnetic layer 3 were laminated on both surfaces of a polyester film 1 as shown in FIG.
磁性塗料 α−Fe磁性粉末 500重量部 塩化ビニル−酢酸ビニル−ビニルアルコール共重合体50
〃 （米国U.C.C.社製;VAGH） ポリウレタン樹脂 30 〃 （大日本インキ化学工業社製；パンデックスＴ−5250） イソシアネート化合物 20 〃 （日本ポリウレタン工業社製；コロネートＬ） オレイルオレート 15 〃 シクロヘキサノン 650 〃 トルエン 650 〃 実施例２ 実施例１における下塗り層用塗料の組成において、Al
2O3粉末に代えてCaCO3粉末（平均粒子径0.1μｍ）を同
量使用した以外は、実施例１と同様にして下塗り層を形
成し、磁気ディスクＡをつくった。Magnetic paint α-Fe magnetic powder 500 parts by weight Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 50
〃 (manufactured by UCC, USA; VAGH) Polyurethane resin 30 〃 (manufactured by Dainippon Ink and Chemicals; Pandex T-5250) Isocyanate compound 20 〃 (manufactured by Nippon Polyurethane Kogyo; Coronate L) oleyl oleate 15 〃 Cyclohexanone 650 〃 Toluene 650 〃 Example 2 In the composition of the coating material for undercoat layer in Example 1, Al
A magnetic disk A was prepared by forming an undercoat layer in the same manner as in Example 1 except that the same amount of CaCO 3 powder (average particle size 0.1 μm) was used instead of 2 O 3 powder.
実施例３ 実施例１における下塗り層用塗料の組成において、Al
2O3粉末に代えてα−Fe2O3粉末（平均粒子径0.3μｍ）
を同量使用した以外は、実施例１と同様にして下塗り層
を形成し、磁気ディスクＡをつくった。Example 3 In the composition of the coating material for undercoat layer in Example 1, Al
Instead of the 2 O 3 powder alpha-Fe 2 O 3 powder (average particle diameter 0.3 [mu] m)
A magnetic disk A was prepared by forming an undercoat layer in the same manner as in Example 1 except that the same amount was used.
比較例１ 実施例１における下塗り層用塗料の組成において、平
均粒子径が0.7μｍのAl2O3粉末に代えて平均粒子径が0.
07μｍのAl2O3粉末を同量使用した以外は、実施例１と
同様にして下塗り層を形成し、磁気ディスクをつくっ
た。Comparative Example 1 In the composition of the undercoat layer coating composition of Example 1, the average particle diameter was replaced by Al 2 O 3 powder having an average particle diameter of 0.7 μm, and the average particle diameter was 0.
A magnetic disk was prepared by forming an undercoat layer in the same manner as in Example 1 except that the same amount of Al 2 O 3 powder of 07 μm was used.
比較例２ 実施例１における下塗り層用塗料の組成において、平
均粒子径が0.7μｍのAl2O3粉末に代えて平均粒子径が4.
0μｍのAl2O3粉末を同量使用した以外は、実施例１と同
様にして下塗り層を形成し、磁気ディスクをつくった。Comparative Example 2 In the composition of the coating material for undercoat layer in Example 1, the average particle diameter was 4. 4 instead of Al 2 O 3 powder having an average particle diameter of 0.7 μm.
A magnetic disk was prepared by forming an undercoat layer in the same manner as in Example 1 except that the same amount of Al 2 O 3 powder of 0 μm was used.
比較例３ 実施例１における下塗り層用塗料の組成において、Al
2O3粉末に代えて平均粒子径が0.2μｍのカーボンブラッ
クを同量使用した以外は、実施例１と同様にして下塗り
層を形成し、磁気ディスクをつくった。Comparative Example 3 In the composition of the coating material for undercoat layer in Example 1, Al
A magnetic disk was prepared by forming an undercoat layer in the same manner as in Example 1 except that the same amount of carbon black having an average particle diameter of 0.2 μm was used instead of the 2 O 3 powder.
比較例４ 実施例１における下塗り層用塗料の組成において、Al
2O3粉末を省いた以外は、実施例１と同様にして下塗り
層を形成し、磁気ディスクをつくった。Comparative Example 4 In the composition of the coating material for undercoat layer in Example 1, Al
An undercoat layer was formed in the same manner as in Example 1 except that the 2 O 3 powder was omitted, to prepare a magnetic disk.
各実施例および比較例で得られた磁気ディスクについ
て、耐久性を調べた。耐久性は、磁気ディスクを磁気デ
ィスク駆動装置に装着し、相対速度3m/sec、ヘッド圧20
gで、磁気ディスクに傷が発生するまでの時間を測定し
て調べた。The durability of the magnetic disks obtained in each example and comparative example was examined. As for durability, the magnetic disk is mounted on the magnetic disk drive, the relative speed is 3 m / sec, and the head pressure is 20
In g, the time until scratches were generated on the magnetic disk was measured and examined.
下記第１表はその結果である。 The results are shown in Table 1 below.
〔発明の効果〕 上記第１表から明らかなように、この発明で得られた
磁気ディスク（実施例１ないし３）は、比較例１ないし
４で得られた磁気ディスクに比し、傷が発生するまでの
時間が長く、このことからこの発明によって得られる磁
気ディスクは、耐久性が充分に向上されていることがわ
かる。 [Effects of the Invention] As is clear from Table 1 above, the magnetic disks (Examples 1 to 3) obtained according to the present invention have more scratches than the magnetic disks obtained in Comparative Examples 1 to 4. It takes a long time to complete, and it can be seen from this that the durability of the magnetic disk obtained by the present invention is sufficiently improved.
第１図はこの発明で得られた磁気ディスクの部分拡大断
面図である。 １……ポリエステルフイルム（基体）、２……下塗り
層、３……磁性層、Ａ……磁気ディスクFIG. 1 is a partially enlarged sectional view of a magnetic disk obtained by the present invention. 1 ... Polyester film (base), 2 ... Undercoat layer, 3 ... Magnetic layer, A ... Magnetic disk
Claims (2)
CO3粉末、MgO粉末、Cr2O3粉末、BaSO4粉末、BaCO3粉
末、ZnO粉末、Cu2O粉末、CuO粉末、TiO2粉末から選ばれ
る平均粒子径が0.1〜３μｍの非磁性粉末を含む下塗り
層を設け、この下塗り層上に磁性粉末を含む厚さが５μ
ｍ以下の塗布型磁性層を設けたことを特徴とする磁気デ
ィスク1. Al 2 O 3 powder, α-Fe 2 O 3 powder, and Ca on a substrate.
CO 3 powder, MgO powder, Cr 2 O 3 powder, BaSO 4 powder, BaCO 3 powder, ZnO powder, Cu 2 O powder, CuO powder, TiO 2 powder, non-magnetic powder with an average particle diameter of 0.1 to 3 μm. An undercoat layer containing magnetic powder is provided on the undercoat layer containing 5 μm.
A magnetic disk having a coating type magnetic layer of m or less
CaCO3粉末、MgO粉末、Cr2O3粉末、BaSO4粉末、BaCO3粉
末、ZnO粉末、Cu2O粉末、CuO粉末、TiO2粉末から選ばれ
る平均粒子径が0.1〜３μｍの非磁性粉末を、下塗り層
の全固形成分に対して20〜80重量％含有させた下塗り層
である特許請求の範囲第１項記載の磁気ディスク2. The undercoat layer comprises Al 2 O 3 powder, α-Fe 2 O 3 powder,
A non-magnetic powder having an average particle diameter of 0.1 to 3 μm selected from CaCO 3 powder, MgO powder, Cr 2 O 3 powder, BaSO 4 powder, BaCO 3 powder, ZnO powder, Cu 2 O powder, CuO powder, and TiO 2 powder. The magnetic disk according to claim 1, which is an undercoat layer containing 20 to 80% by weight based on all solid components of the undercoat layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61000852A JPH0816978B2 (en) | 1986-01-06 | 1986-01-06 | Magnetic disk |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61000852A JPH0816978B2 (en) | 1986-01-06 | 1986-01-06 | Magnetic disk |
Related Child Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7051797A Division JPH09231549A (en) | 1997-03-06 | 1997-03-06 | Magnetic disk |
| JP7051697A Division JPH09231548A (en) | 1997-03-06 | 1997-03-06 | Magnetic disk |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62159338A JPS62159338A (en) | 1987-07-15 |
| JPH0816978B2 true JPH0816978B2 (en) | 1996-02-21 |
Family
ID=11485172
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61000852A Expired - Lifetime JPH0816978B2 (en) | 1986-01-06 | 1986-01-06 | Magnetic disk |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0816978B2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07107735B2 (en) * | 1986-03-25 | 1995-11-15 | 株式会社東芝 | Magnetic recording medium |
| JP2855440B2 (en) * | 1989-03-31 | 1999-02-10 | コニカ株式会社 | Magnetic recording media |
| US5645917A (en) * | 1991-04-25 | 1997-07-08 | Fuji Photo Film Co., Ltd. | Magnetic recording medium |
| US5827600A (en) * | 1991-01-21 | 1998-10-27 | Fuji Photo Film Co., Ltd. | Magnetic recording medium |
| JP2566088B2 (en) * | 1992-01-08 | 1996-12-25 | 富士写真フイルム株式会社 | Magnetic recording media |
| JP2566096B2 (en) * | 1992-04-14 | 1996-12-25 | 富士写真フイルム株式会社 | Magnetic recording media |
| JP2582051B2 (en) * | 1995-07-27 | 1997-02-19 | 富士写真フイルム株式会社 | Magnetic recording media |
| US5750250A (en) | 1995-10-20 | 1998-05-12 | Toda Kogyo Corporation | Hematite particles and magnetic recording medium having a non-magnetic under-coat layer containing hematite (Fe2 O3) particles. |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5613515A (en) * | 1979-07-16 | 1981-02-09 | Tdk Corp | Magnetic recording medium |
| JPS5928226A (en) * | 1982-08-09 | 1984-02-14 | Victor Co Of Japan Ltd | Magnetic recording medium |
| JPS59223935A (en) * | 1983-06-03 | 1984-12-15 | Tdk Corp | Magnetic recording medium |
-
1986
- 1986-01-06 JP JP61000852A patent/JPH0816978B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62159338A (en) | 1987-07-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |