JP3226564B2 - Magnetic recording media - Google Patents
Magnetic recording mediaInfo
- Publication number
- JP3226564B2 JP3226564B2 JP16936791A JP16936791A JP3226564B2 JP 3226564 B2 JP3226564 B2 JP 3226564B2 JP 16936791 A JP16936791 A JP 16936791A JP 16936791 A JP16936791 A JP 16936791A JP 3226564 B2 JP3226564 B2 JP 3226564B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- metal powder
- ferromagnetic metal
- powder
- weight
- 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 - Fee Related
Links
- 230000005291 magnetic effect Effects 0.000 title claims description 75
- 239000002184 metal Substances 0.000 claims description 73
- 229910052751 metal Inorganic materials 0.000 claims description 73
- 239000000843 powder Substances 0.000 claims description 64
- 230000005294 ferromagnetic effect Effects 0.000 claims description 61
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 24
- 239000011230 binding agent Substances 0.000 claims description 22
- 230000005484 gravity Effects 0.000 claims description 19
- 229910052742 iron Inorganic materials 0.000 claims description 11
- 239000006247 magnetic powder Substances 0.000 description 19
- 230000005415 magnetization Effects 0.000 description 13
- 239000003973 paint Substances 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 10
- 230000006866 deterioration Effects 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 239000000203 mixture Substances 0.000 description 9
- 239000010410 layer Substances 0.000 description 8
- 230000004907 flux Effects 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 7
- 238000007254 oxidation reaction Methods 0.000 description 7
- 229920005749 polyurethane resin Polymers 0.000 description 7
- 230000006872 improvement Effects 0.000 description 6
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 5
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 229920001577 copolymer Polymers 0.000 description 5
- 239000003960 organic solvent Substances 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000004381 surface treatment Methods 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000005275 alloying Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229920002433 Vinyl chloride-vinyl acetate copolymer Polymers 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 239000008199 coating composition Substances 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 238000013500 data storage Methods 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910020630 Co Ni Inorganic materials 0.000 description 1
- 229910002440 Co–Ni Inorganic materials 0.000 description 1
- 229910020674 Co—B Inorganic materials 0.000 description 1
- 229910020516 Co—V Inorganic materials 0.000 description 1
- 229910017061 Fe Co Inorganic materials 0.000 description 1
- 229910017086 Fe-M Inorganic materials 0.000 description 1
- 229910017112 Fe—C Inorganic materials 0.000 description 1
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- 229910018104 Ni-P Inorganic materials 0.000 description 1
- 229910018106 Ni—C Inorganic materials 0.000 description 1
- 229910018536 Ni—P Inorganic materials 0.000 description 1
- 229910018605 Ni—Zn Inorganic materials 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Landscapes
- Paints Or Removers (AREA)
- Powder Metallurgy (AREA)
- Magnetic Record Carriers (AREA)
- Hard Magnetic Materials (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、磁性粉末として強磁性
金属粉末を用いた塗布型の磁気記録媒体に関し、特に耐
候性に優れた磁気記録媒体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating type magnetic recording medium using a ferromagnetic metal powder as a magnetic powder, and more particularly to a magnetic recording medium excellent in weather resistance.
【０００２】[0002]
【従来の技術】塗布型の磁気テープや磁気ディスク等の
磁気記録媒体においては、高画質化等を図るために、よ
り一層の高記録密度化が要求されている。この高記録密
度化に伴い、鉄又は鉄を主体とする金属磁性粉末が広く
用いられるようになり、その微細化が活発に進められて
いる。このように微細化された金属磁性粉末を用いるこ
とで、高記録密度化や高周波帯域における優れた電磁変
換特性が達成される。2. Description of the Related Art In a magnetic recording medium such as a coating type magnetic tape or a magnetic disk, further higher recording density is required in order to achieve higher image quality and the like. With this increase in recording density, iron or metal magnetic powder mainly composed of iron has been widely used, and the miniaturization thereof has been actively promoted. By using such fine metal magnetic powder, high recording density and excellent electromagnetic conversion characteristics in a high frequency band can be achieved.
【０００３】ところが、鉄又は鉄を主体とする金属磁性
粉末は、本質的に錆易く、また酸化されやすい特性を有
しており、このような性質は磁性粉末の微細化が進めら
れるに従って、ますます強くなる傾向にある。このた
め、この金属磁性粉末を磁気記録媒体の磁性粉末として
用いる場合には、金属磁性粉末の保存中、或いは結合剤
や有機溶剤等との組合せによる塗料化の工程中、更には
ポリエステルフィルムなどの非磁性支持体上に塗布して
シート化した後、所定の雰囲気や温度、湿度等の条件下
での保管中に、主として酸素やある種のガス及び水分等
の影響による酸化が進行して、飽和磁化や保磁力等の磁
気特性が劣化するという問題が起こる。更に、このよう
な現象は、磁気記録媒体の残留磁束密度の低下をもたら
し、結果として出力特性が劣化してしまう。[0003] However, iron or iron-based metal magnetic powders are inherently easily rustable and easily oxidized, and such properties are more and more likely as the magnetic powders are miniaturized. It tends to be stronger. For this reason, when this metal magnetic powder is used as a magnetic powder for a magnetic recording medium, during storage of the metal magnetic powder, or during the process of coating with a binder or an organic solvent, etc. After being coated on a non-magnetic support and formed into a sheet, during storage under conditions such as a predetermined atmosphere, temperature, and humidity, oxidation mainly due to the influence of oxygen, some kind of gas, and moisture advances. There arises a problem that magnetic characteristics such as saturation magnetization and coercive force are deteriorated. Further, such a phenomenon causes a decrease in the residual magnetic flux density of the magnetic recording medium, and as a result, the output characteristics deteriorate.
【０００４】この問題に対して、鉄に比べて優れた耐酸
化性を示すＣｏ，Ｎｉ等の合金化やＡｌ及び／又はＳｉ
等の軽金属酸化物層を金属磁性粉末の表面に形成するこ
とにより、耐食性の向上を図る技術が検討されている。
或いは、最近では、低分子有機物を上記金属磁性粉末の
表面に吸着させる方法等についても研究が進められてい
る。[0004] In order to solve this problem, alloying of Co, Ni or the like, which exhibits superior oxidation resistance compared to iron, Al and / or Si
For example, a technique for improving corrosion resistance by forming a light metal oxide layer such as on the surface of a metal magnetic powder has been studied.
Alternatively, recently, studies have been made on a method of adsorbing a low molecular organic substance on the surface of the metal magnetic powder.
【０００５】[0005]
【発明が解決しようとする課題】上述のようにある種の
金属元素の合金化や軽金属酸化物層を形成する方法、或
いは金属磁性粉末の表面を低分子有機物で覆う方法で
は、金属磁性粉末の酸化を抑え磁気特性の経時劣化を防
ぐ上で必ずしも十分なものとは言い難い。また、処理の
方法によっては、表面処理すること自体が磁気特性の劣
化をもたらす場合や塗料化の際の分散性の低下をきたす
虞れがある。As described above, in the method of alloying a certain metal element or forming a light metal oxide layer, or the method of covering the surface of a metal magnetic powder with a low molecular organic substance, It is not always sufficient to suppress oxidation and prevent deterioration of magnetic properties over time. In addition, depending on the treatment method, there is a possibility that the surface treatment itself may cause deterioration of magnetic properties or that the dispersibility of the paint may be reduced.
【０００６】本発明は、上述のような実情に鑑みて提案
されたものであって、磁性粉末として用いられる強磁性
金属粉末の耐酸化性の向上を図り、耐候性に優れた磁気
記録媒体を提供することを目的とする。The present invention has been proposed in view of the above-mentioned circumstances, and aims to improve the oxidation resistance of a ferromagnetic metal powder used as a magnetic powder and provide a magnetic recording medium having excellent weather resistance. The purpose is to provide.
【０００７】[0007]
【課題を解決するための手段】本発明者等は、上述の目
的を達成せんものと鋭意研究の結果、鉄を主成分とする
強磁性金属粉末のＢＥＴ比表面積と比重の積の範囲を規
定することによって何ら表面処理を施さなくとも耐酸化
性に優れた強磁性金属粉末が実現され、この強磁性金属
粉末を磁性粉末として用いることにより、磁気記録媒体
の耐候性が向上することを見出し、本発明を完成するに
至ったものである。Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have defined the range of the product of the BET specific surface area and the specific gravity of a ferromagnetic metal powder containing iron as a main component. By doing so, a ferromagnetic metal powder excellent in oxidation resistance without any surface treatment is realized, and by using this ferromagnetic metal powder as a magnetic powder, it has been found that the weather resistance of a magnetic recording medium is improved, The present invention has been completed.
【０００８】即ち、本発明は、非磁性支持体上に鉄を主
成分とする強磁性金属粉末と結合剤とを主体とする磁性
層が形成されてなる磁気記録媒体において、強磁性金属
粉末のＢＥＴ比表面積（ｍ２／ｇ）と比重（ｇ／ｃｃ）
の積が１９０ｍ２／ｃｃ以上、２５０ｍ２／ｃｃ以下で
あり、且つ針状比が５以上、２０以下としたものであ
る。That is, the present invention mainly comprises iron on a non-magnetic support.
In a magnetic recording medium having a magnetic layer mainly composed of a ferromagnetic metal powder as a component and a binder, the BET specific surface area (m 2 / g) and the specific gravity (g / cc) of the ferromagnetic metal powder
Are not less than 190 m 2 / cc and not more than 250 m 2 / cc, and the acicular ratio is not less than 5 and not more than 20.
【０００９】磁気記録媒体の磁気特性の経時的劣化を防
止するとともに、耐候性を向上するためには、下記の
（１）式で示される基準値がＡが１９０ｍ２／ｃｃ以上
２５０ｍ２／ｃｃ以下であることが必要となる。In order to prevent the magnetic characteristics of the magnetic recording medium from deteriorating over time and to improve the weather resistance, the reference value represented by the following equation (1) is A: 190 m 2 / cc or more and 250 m 2 / cc. It is necessary that:
【００１０】 基準値Ａ＝（ＢＥＴ比表面積）×（比重ρ） ・・・（１） このように、基準値Ａを１９０ｍ２／ｃｃ以上２５０ｍ
２／ｃｃ以下とすることにより、磁気録媒体の経時的劣
化を防止できるのは、概念的に高密度の金属鉄核の形成
及びそれを取り巻く緻密で均一な酸化鉄層の形成による
ものと考えられる。したがって、これらの条件を満足す
る強磁性金属粉末を使用すれば、高耐候性を有する磁気
記録媒体を得ることができる。Reference value A = (BET specific surface area) × (specific gravity ρ) (1) Thus, the reference value A is set to 190 m 2 / cc or more and 250 m
The reason why the magnetic recording medium can be prevented from deteriorating over time by setting the ratio to 2 / cc or less is considered to be conceptually due to the formation of a high-density metal iron nucleus and the formation of a dense and uniform iron oxide layer surrounding it. Can be Therefore, if a ferromagnetic metal powder satisfying these conditions is used, a magnetic recording medium having high weather resistance can be obtained.
【００１１】即ち、上記（１）式中のＢＥＴ比表面積は
〔ｍ２／ｇ〕なる次元を有する値であり、一方比重は真
比重をもって表され〔ｇ／ｃｃ〕なる次元を有する値で
あるから、これらの積によって与えられる基準値Ａ〔ｍ
２／ｃｃ〕は、単位体積当たりの比表面積を表している
と言える。ここで、強磁性金属粉末の表面が平滑で一様
であれば、ＢＥＴ比表面積は小さく、比重は一般に大き
くなる。この場合、耐候性の向上に有効となる。逆に、
表面に凸凹や細孔を有し不均一な強磁性金属粉末では、
ＢＥＴ比表面積は大きく、比重は小さくなり、良好な効
果は期待できない。That is, the BET specific surface area in the above formula (1) is a value having a dimension of [m 2 / g], while the specific gravity is a value having a dimension of [g / cc] expressed as a true specific gravity. From the reference value A [m given by the product of
2 / cc] can be said to represent the specific surface area per unit volume. Here, if the surface of the ferromagnetic metal powder is smooth and uniform, the BET specific surface area is small and the specific gravity is generally large. This is effective for improving the weather resistance. vice versa,
In the case of non-uniform ferromagnetic metal powder having irregularities and pores on the surface,
The BET specific surface area is large, the specific gravity is small, and good effects cannot be expected.
【００１２】仮に、ＢＥＴ比表面積と比重が反比例する
ものであれば、上記基準値Ａは一定となるが、実際には
これらは反比例しておらず、ある限定された値をとる時
のみ、耐候性の向上が見られることが本発明者等の実験
結果から明らかにされた。If the BET specific surface area and the specific gravity are inversely proportional, the above-mentioned reference value A will be constant. However, they are not inversely proportional. It has been clarified from the experimental results of the present inventors that an improvement in the performance is observed.
【００１３】図１は、上記基準値Ａの異なる強磁性金属
粉末を用い、これら強磁性金属粉末を湿度９０％、温度
６０℃の環境下で１週間放置した後の初期値に対する飽
和磁化σＳの劣化率と上記基準値Ａの関係を示すもので
ある。[0013] Figure 1, using different ferromagnetic metal powder of the above reference value A, these ferromagnetic metal powders humidity of 90%, the saturation magnetization sigma S to the initial value after one week was left in an environment of temperature 60 ° C. 2 shows the relationship between the deterioration rate and the reference value A.
【００１４】図１より明らかなように、強磁性金属粉末
のＢＥＴ比表面積と比重の積が１９０〜２５０ｍ２／ｃ
ｃであるとき、飽和磁化σＳの劣化率は１０％以下と非
常に小さくなる。従って、上記基準値Ａの限定されるべ
き範囲は、１９０≦Ａ≦２５０（ｍ２／ｃｃ）とされ
る。基準値Ａが上記範囲から外れると、十分な耐候性が
得られなくなる。As is apparent from FIG. 1, the product of the BET specific surface area and the specific gravity of the ferromagnetic metal powder is 190 to 250 m 2 / c.
When it is c, the deterioration rate of the saturation magnetization σ S is very small, 10% or less. Therefore, the range of the reference value A to be limited is set to 190 ≦ A ≦ 250 (m 2 / cc). If the reference value A is out of the above range, sufficient weather resistance cannot be obtained.
【００１５】上述したように、上記基準値Ａは単位体積
当たりの比表面積であり、別の表現を用いれば、粒子の
（表面積）／（体積）値を示すものである。従って、こ
の基準値Ａは粒子の形状に強く依存し、例えばこの基準
値Ａの最小値は、粒子の形状が球状である時に実現され
る。但し、従来から知られているように、強磁性金属粉
末の保磁力は、粒子の形状異方性に起因する。従って、
高保磁力を実現するためには、適切な針状比Ｌ／Ｗを有
することが必須条件であり、本発明においては５≦Ｌ／
Ｗ≦２０の範囲であることが必要とされる。強磁性金属
粉末の針状比が上記範囲から外れると、良好な保磁力を
確保することができず、更に強磁性金属粉末の針状比が
２０より大きい場合には、塗料化する際に分散性が著し
く低下してしまい、実用上採用できない。As described above, the reference value A is a specific surface area per unit volume. In other words, the reference value A indicates a (surface area) / (volume) value of a particle. Therefore, the reference value A strongly depends on the shape of the particle. For example, the minimum value of the reference value A is realized when the shape of the particle is spherical. However, as is conventionally known, the coercive force of the ferromagnetic metal powder results from the shape anisotropy of the particles. Therefore,
In order to realize a high coercive force, it is essential to have an appropriate needle ratio L / W. In the present invention, 5 ≦ L /
It is required that the range of W ≦ 20 be satisfied. If the acicular ratio of the ferromagnetic metal powder is out of the above range, a good coercive force cannot be secured. The properties are remarkably reduced and cannot be used practically.
【００１６】以上のように、高耐候性を有し、且つ磁気
記録媒体としてふさわしい磁気特性を有する強磁性金属
粉末の条件として、磁気記録媒体基準値Ａを限定すると
同時に、針状比の限定も必要となる。このような条件を
満足する強磁性金属粉末を磁性粉末として用いることに
より、耐候性に優れた磁気記録媒体が得られる。上記強
磁性金属粉末としては、Ｆｅの如き強磁性金属材料や、
Ｆｅ−Ｃｏ、Ｆｅ−Ｎｉ、Ｆｅ−Ｃｏ−Ｎｉ、Ｆｅ−Ｍ
ｎ−Ｚｎ、Ｆｅ−Ｎｉ−Ｚｎ、Ｆｅ−Ｃｏ−Ｎｉ−Ｃ
ｒ、Ｆｅ−Ｃｏ−Ｎｉ−Ｐ、Ｆｅ−Ｃｏ−Ｂ、Ｆｅ−Ｃ
ｏ−Ｃｒ−Ｂ、Ｆｅ−Ｃｏ−Ｖ等のＦｅを主成分とする
各種強磁性合金材料からなる強磁性金属粉末が使用可能
とされ、更にこれらの種々の特性を改善する目的でＡ
ｌ、Ｓｉ、Ｔｉ、Ｃｒ、Ｍｎ、Ｃｕ、Ｚｎ、Ｍｇ、Ｐ等
の元素が添加されたものであっても良い。As described above, as a condition for the ferromagnetic metal powder having high weather resistance and magnetic properties suitable for a magnetic recording medium, the magnetic recording medium reference value A is limited, and the needle ratio is also limited. Required. By using a ferromagnetic metal powder satisfying such conditions as a magnetic powder, a magnetic recording medium having excellent weather resistance can be obtained. Examples of the ferromagnetic metal powder include a ferromagnetic metal material such as Fe,
Fe-Co, Fe-Ni, Fe-Co-Ni, Fe-M
n-Zn, Fe-Ni-Zn, Fe-Co-Ni-C
r, Fe-Co-Ni-P, Fe-Co-B, Fe-C
Ferromagnetic metal powders composed of various ferromagnetic alloy materials containing Fe as a main component, such as o-Cr-B and Fe-Co-V, can be used. In order to further improve these various characteristics, A
Elements to which elements such as 1, Si, Ti, Cr, Mn, Cu, Zn, Mg, and P are added may be used.
【００１７】本発明においては、上記強磁性金属粉末を
結合剤や有機溶剤、各種添加剤等とともに混練して磁性
塗料を調製し、この磁性塗料を非磁性支持体上に塗布、
乾燥することにより磁性層が形成される。このような磁
気記録媒体は、例えばハードディスクのバックアップ等
に用いられる磁気テープ等として用いて好適であり、メ
タルテープを用いたＲ−ＤＡＴカセットや８ミリビデオ
カセットを用いたＤＤＳやＤ−８等の所謂データストレ
ージ用メディアとしての使用が可能である。In the present invention, the above ferromagnetic metal powder is kneaded with a binder, an organic solvent, various additives and the like to prepare a magnetic paint, and the magnetic paint is applied on a non-magnetic support.
The magnetic layer is formed by drying. Such a magnetic recording medium is suitable for use as, for example, a magnetic tape or the like used for backup of a hard disk and the like, such as an R-DAT cassette using a metal tape and a DDS or D-8 using an 8 mm video cassette. It can be used as a so-called data storage medium.
【００１８】この種の磁気テープにおいては、ギガバイ
ト級の大容量化が要求されるとともに、特にデータスト
レージ用メディア等については、過酷な状況での使用を
要求されるために高い信頼性、長期保存安定性が強く要
求される。従って、耐錆性の改善や大容量化に伴う電磁
変換特性の向上は重要な課題である。This type of magnetic tape is required to have a large capacity of the order of gigabytes, and especially for data storage media and the like, which are required to be used under severe conditions, so that they have high reliability and long-term storage. High stability is required. Therefore, improvement of rust resistance and improvement of electromagnetic conversion characteristics accompanying increase in capacity are important issues.
【００１９】そこで、磁性塗料を調製する際に、強磁性
金属粉末と結合剤の重量比が５〜６．５となるように配
合されることが望ましい。強磁性金属粉末と結合剤の重
量比を上記範囲内に制御することにより、強磁性金属粉
末のまわりに存在する結合剤の量を良好に調節すること
ができ、耐候性、耐久性の向上が図られるとともに、良
好な走行性を確保することができる。Therefore, when preparing the magnetic paint, it is desirable to mix the ferromagnetic metal powder and the binder so that the weight ratio is 5 to 6.5. By controlling the weight ratio between the ferromagnetic metal powder and the binder within the above range, the amount of the binder present around the ferromagnetic metal powder can be adjusted well, and the weather resistance and durability can be improved. As well as good running performance can be ensured.
【００２０】なお、上記結合剤や有機溶剤、各種添加剤
としては、通常の磁気記録媒体に用いられるものがいず
れも使用可能である。As the above-mentioned binder, organic solvent, and various additives, any of those used for ordinary magnetic recording media can be used.
【００２１】また、本発明においては、耐候性の向上を
更に強化する目的で、上記強磁性金属粉末に対して、例
えば鉄に比べて優れた耐酸化性を示すＣｏ，Ｎｉ等の合
金化やＡｌ及び／又はＳｉ等の軽金属酸化物表面層の形
成、或いは低分子有機物による表面処理等、従来公知と
される技術を併用しても何ら不都合は生じない。この場
合、シランカップリング剤により上記強磁性金属粉末の
表面を被覆する方法が好適である。Further, in the present invention, for the purpose of further enhancing the improvement of weather resistance, alloying of the above ferromagnetic metal powder such as Co, Ni, etc., which exhibits oxidation resistance superior to that of iron, may be used. No inconvenience arises even if a conventionally known technique such as formation of a surface layer of a light metal oxide such as Al and / or Si or surface treatment with a low molecular organic substance is used in combination. In this case, a method of coating the surface of the ferromagnetic metal powder with a silane coupling agent is preferable.
【００２２】[0022]
【作用】ＢＥＴ比表面積と比重の積Ａが１９０ｍ２／ｃ
ｃ以上２５０ｍ２／ｃｃ以下にある強磁性金属粉末は、
高密度の金属鉄核を有し、更にそれを取り巻いて緻密で
均一な酸化鉄層が形成された状態にあり、何ら表面処理
を施さなくとも良好な耐酸化性を有する。[Function] The product A of the BET specific surface area and the specific gravity is 190 m 2 / c.
The ferromagnetic metal powder having a size of c to 250 m 2 / cc is:
It has a high-density metallic iron nucleus, and a dense and uniform iron oxide layer is formed around it, and has good oxidation resistance without any surface treatment.
【００２３】また、強磁性金属粉末の針状比Ｌ／Ｗを５
≦Ｌ／Ｗ≦２０の範囲とすることにより、良好な保磁力
が得られる。従って、強磁性金属粉末のＢＥＴ比表面積
と比重の積Ａを限定すると同時に、針状比を限定すれ
ば、高耐候性を有し、且つ磁気記録媒体としてふさわし
い磁気特性を有する強磁性金属粉末が得られる。The needle ratio L / W of the ferromagnetic metal powder is set to 5
By setting the range of ≦ L / W ≦ 20, a good coercive force can be obtained. Therefore, when the product A of the BET specific surface area and the specific gravity of the ferromagnetic metal powder is limited and the acicular ratio is limited, a ferromagnetic metal powder having high weather resistance and magnetic properties suitable for a magnetic recording medium is obtained. can get.
【実施例】以下、本発明を具体的な実施例を比較例とと
もに説明する、なお、本発明は、以下に示す実施例に限
定されるものでないことは言うまでもない。EXAMPLES Hereinafter, the present invention will be described with reference to specific examples and comparative examples. Needless to say, the present invention is not limited to the following examples.
【００２４】比較例１ 本発明に係る実施例に先立って本発明の比較例を示す
と、この比較例１は、ＢＥＴ比表面積と比重の積が２９
５ｍ２／ｃｃで、且つ針状比が１２である強磁性金属粉
末Ａを磁性粉末として用いた例である。なお、この強磁
性金属粉末Ａの諸特性は、下記の表１に示す通りであ
る。 Comparative Example 1 A comparative example of the present invention will be described prior to an example according to the present invention. In Comparative Example 1, the product of the BET specific surface area and the specific gravity is 29.
This is an example in which a ferromagnetic metal powder A having 5 m 2 / cc and a needle ratio of 12 is used as a magnetic powder. The properties of the ferromagnetic metal powder A are as shown in Table 1 below.
【００２５】[0025]
【表１】 先ず、強磁性金属粉末Ａを湿度９０％、温度６０℃の環
境下で１週間放置した後、飽和磁化σＳを測定し、その
劣化率を調べた。この結果、１週間放置後の飽和磁化σ
Ｓは９９ｅｍｕ／ｇであり、飽和磁化σＳの劣化率は僅
か１９％であった。[Table 1] First, the ferromagnetic metal powder A was allowed to stand for one week in an environment of a humidity of 90% and a temperature of 60 ° C., and then the saturation magnetization σ S was measured to check the deterioration rate. As a result, the saturation magnetization σ after one week
S was 99 emu / g, and the deterioration rate of the saturation magnetization σ S was only 19%.
【００２６】この強磁性金属粉末Ａを用いて、以下の組
成に従って磁性塗料を調製した。Using this ferromagnetic metal powder A, a magnetic paint was prepared according to the following composition.
【００２７】 磁性塗料の組成 強磁性金属粉末Ａ １００重量部 塩化ビニル−酢酸ビニル共重合体 １０重量部 ポリウレタン樹脂 １０重量部 カーボン ３重量部 Ａｌ２Ｏ３ ２重量部 メチルエチルケトン １００重量部 トルエン １００重量部 シクロヘキサノン ５０重量部 得られた磁性塗料を非磁性支持体上に塗布、乾燥して磁
性層とした、通常の手法により磁気テープを作製した。Composition of magnetic paint Ferromagnetic metal powder A 100 parts by weight Vinyl chloride-vinyl acetate copolymer 10 parts by weight Polyurethane resin 10 parts by weight Carbon 3 parts by weight Al 2 O 3 2 parts by weight Methyl ethyl ketone 100 parts by weight Toluene 100 parts by weight 50 parts by weight of cyclohexanone The obtained magnetic paint was applied on a nonmagnetic support, dried to form a magnetic layer, and a magnetic tape was produced by a usual method.
【００２８】実施例１ 表１に示すようにＢＥＴ比表面積と比重の積が２４４ｍ
２／ｃｃで、且つ針状比が１１である強磁性金属粉末Ｂ
を磁性粉末として用い、その他は上記比較例１と同様に
して磁気テープを作製した。 Example 1 As shown in Table 1, the product of the BET specific surface area and the specific gravity was 244 m
2 / cc and ferromagnetic metal powder B having an acicular ratio of 11
Was used as a magnetic powder, and the other conditions were the same as in Comparative Example 1 to produce a magnetic tape.
【００２９】なお、この強磁性金属粉末Ｂについても、
上述と同じ条件にて１週間放置後の飽和磁化σＳを調べ
たところ、１週間放置後の飽和磁化σＳは１１４ｅｍｕ
／ｇであり、飽和磁化σＳの劣化率は７．３％と非常に
小さく、極めて良好な耐候性を示すことが確認された。
また、この強磁性金属粉末Ｂの諸特性を上記表１に併せ
て記した。Incidentally, this ferromagnetic metal powder B also
Examination of the saturation magnetization σ S after being left for 1 week at the same conditions as described above, the saturation magnetization σ S after being left for one week 114emu
/ G, and the rate of deterioration of the saturation magnetization σ S is very small at 7.3%, confirming that extremely good weather resistance is exhibited.
Various properties of the ferromagnetic metal powder B are also shown in Table 1 above.
【００３０】比較例２ 表１に示すようにＢＥＴ比表面積と比重の積が本発明で
規定された範囲よりも大きい強磁性金属粉末Ｃを用い、
その他は上記比較例１と同様にして磁気テープを作製し
た。なお、この強磁性金属粉末Ｃについても、上述と同
じ条件にて１週間放置後の飽和磁化σＳを調べたとこ
ろ、１週間放置後の飽和磁化σＳは６９ｅｍｕ／ｇであ
り、飽和磁化σＳの劣化率は３７％と大きく、実用上好
ましくないことが明らかとなった。また、この強磁性金
属粉末Ｃの諸特性を上記表１に併せて記した。 Comparative Example 2 As shown in Table 1, a ferromagnetic metal powder C having a product of BET specific surface area and specific gravity larger than the range specified in the present invention was used.
Otherwise, a magnetic tape was produced in the same manner as in Comparative Example 1. Note that the ferromagnetic metal powder C also were examined saturation magnetization sigma S after standing for 1 week under the same conditions as described above, the saturation magnetization sigma S after standing for 1 week is 69emu / g, saturation magnetization sigma The deterioration rate of S was as large as 37%, which proved to be unfavorable for practical use. Various properties of the ferromagnetic metal powder C are also shown in Table 1 above.
【００３１】以上のようにして得られた各磁気テープに
ついて、耐候性を評価するために、乾燥直後の残留磁束
密度Ｂｒ、角形比Ｒｓ及び保磁力ＨＣを測定した後、湿
度９０％、温度６０℃に保持した恒温恒湿槽中で１週間
保存し、再度同じ測定を行い、経時的変化を調べた。こ
れらの結果を表２に示す。[0031] For each magnetic tape obtained as described above, in order to evaluate the weather resistance, the residual magnetic flux density Br immediately after drying, after measuring the squareness ratio Rs and the coercive force H C, 90% humidity, temperature The sample was stored in a thermo-hygrostat kept at 60 ° C. for one week, and the same measurement was performed again to examine a change with time. Table 2 shows the results.
【００３２】[0032]
【表２】 表２に示すように、比較例２では１週間保存後の残留磁
束密度が初期値に比べて１９％も低下し、実用上問題の
ある結果となった。これに対して、ＢＥＴ比表面積と比
重の積が２４４ｍ２／ｃｃである強磁性金属粉末を用い
た実施例１では、残留磁束密度の劣化率は僅か３％に止
まっており、優れた耐候性が得られることが判った。[Table 2] As shown in Table 2, in Comparative Example 2, the residual magnetic flux density after storage for one week was reduced by 19% as compared with the initial value, resulting in a practically problematic result. On the other hand, in Example 1 using the ferromagnetic metal powder having a product of the BET specific surface area and the specific gravity of 244 m 2 / cc, the deterioration rate of the residual magnetic flux density was only 3%, and excellent weather resistance was obtained. Was obtained.
【００３３】次に、上述のような高耐候性を示す強磁性
金属粉末と結合剤との重量比Ｐ／Ｂを検討した。なお、
この重量比Ｐ／Ｂは、Ｐ／Ｂ＝（強磁性金属粉末の重
量）／（結合剤の重量）とされる。実施例２ 本実施例は、磁性粉末としてＢＥＴ比表面積と比重の積
が２４４ｍ２／ｃｃであるＦｅ−Ｎｉ系金属粉末を用
い、このＦｅ−Ｎｉ系金属粉末と結合剤の重量比が５と
なるように配合した例である。Next, the weight ratio P / B of the ferromagnetic metal powder exhibiting high weather resistance as described above and the binder was examined. In addition,
The weight ratio P / B is P / B = (weight of ferromagnetic metal powder) / (weight of binder). Example 2 In this example, an Fe—Ni-based metal powder having a product of BET specific surface area and specific gravity of 244 m 2 / cc was used as the magnetic powder, and the weight ratio of the Fe—Ni-based metal powder to the binder was 5 and This is an example in which the components are blended as follows.
【００３４】先ず、以下の組成に従って磁性塗料を調製
した。なお、実施例２では、Ｆｅ−Ｎｉ経金属粉末、研
磨剤、潤滑剤、有機溶剤として、実施例１と同じものを
使用した。First, a magnetic paint was prepared according to the following composition. In addition, in Example 2, the same thing as Example 1 was used as the Fe-Ni transmetal powder, the abrasive, the lubricant, and the organic solvent.
【００３５】 磁性塗料の組成 Ｆｅ−Ｎｉ系金属粉末 １００重量部 塩化ビニル−酢酸ビニル共重合体 １０重量部 ポリウレタン樹脂 １０重量部 カーボンブラック ４重量部 研磨剤 ４重量部 潤滑剤 ２重量部 有機溶剤 ２４０重量部 得られた磁性塗料を非磁性支持体上に塗布、乾燥して磁
性層とした、通常の手法により磁気テープを作製した。Composition of Magnetic Paint Fe—Ni-based metal powder 100 parts by weight Vinyl chloride-vinyl acetate copolymer 10 parts by weight Polyurethane resin 10 parts by weight Carbon black 4 parts by weight Abrasive 4 parts by weight Lubricant 2 parts by weight Organic solvent 240 Parts by weight The obtained magnetic paint was applied on a non-magnetic support and dried to form a magnetic layer, and a magnetic tape was produced by a usual method.
【００３６】実施例３ 上記実施例２における磁性塗料の組成中、塩化ビニル−
酢酸ビニル共重合体とポリウレタン樹脂の添加量をそれ
ぞれ９重量部ずつに変えて、上記強磁性金属粉末と結合
剤の重量比が５．５となるようにし、その他は実施例２
と同様にして磁気テープを作製した。 Example 3 In the composition of the magnetic coating composition in Example 2 above, vinyl chloride
The addition amounts of the vinyl acetate copolymer and the polyurethane resin were each changed to 9 parts by weight so that the weight ratio between the ferromagnetic metal powder and the binder became 5.5, and the other examples were used in Example 2.
A magnetic tape was produced in the same manner as described above.
【００３７】実施例４ 上記実施例２における磁性塗料の組成中、塩化ビニル−
酢酸ビニル共重合体とポリウレタン樹脂の添加量をそれ
ぞれ８．３重量部ずつに変えて、上記強磁性金属粉末と
結合剤の重量比が６となるようにし、その他は実施例２
と同様にして磁気テープを作製した。 Example 4 In the composition of the magnetic paint in Example 2 above, vinyl chloride
The amounts of the vinyl acetate copolymer and the polyurethane resin were each changed to 8.3 parts by weight so that the weight ratio between the ferromagnetic metal powder and the binder became 6, and the other examples were used in Example 2.
A magnetic tape was produced in the same manner as described above.
【００３８】実施例５ 上記実施例２における磁性塗料の組成中、塩化ビニル−
酢酸ビニル共重合体とポリウレタン樹脂の添加量をそれ
ぞれ７．７重量部ずつに変えて、上記強磁性金属粉末と
結合剤の重量比が６．５となるようにし、その他は実施
例２と同様にして磁気テープを作製した。 Example 5 In the composition of the magnetic paint in Example 2, vinyl chloride
The amounts of the vinyl acetate copolymer and the polyurethane resin were respectively changed to 7.7 parts by weight so that the weight ratio between the ferromagnetic metal powder and the binder became 6.5, and the other conditions were the same as in Example 2. To produce a magnetic tape.
【００３９】比較例３ 上記実施例２における磁性塗料の組成中、塩化ビニル−
酢酸ビニル共重合体とポリウレタン樹脂の添加量をそれ
ぞれ１１．１重量部ずつに変えて、上記強磁性金属粉末
と結合剤の重量比が４．５となるようにし、その他は実
施例２と同様にして磁気テープを作製した。 Comparative Example 3 In the composition of the magnetic paint in Example 2, vinyl chloride
The amounts of the vinyl acetate copolymer and the polyurethane resin were each changed to 11.1 parts by weight so that the weight ratio between the ferromagnetic metal powder and the binder was 4.5, and the other conditions were the same as in Example 2. To produce a magnetic tape.
【００４０】比較例４ 上記実施例２における磁性塗料の組成中、塩化ビニル−
酢酸ビニル共重合体とポリウレタン樹脂の添加量をそれ
ぞれ７重量部ずつに変えて、上記強磁性金属粉末と結合
剤の重量比が７となるようにし、その他は実施例２と同
様にして磁気テープを作製した。 Comparative Example 4 In the composition of the magnetic coating composition in Example 2, vinyl chloride
The amount of the vinyl acetate copolymer and the amount of the polyurethane resin were each changed to 7 parts by weight so that the weight ratio between the ferromagnetic metal powder and the binder became 7, and the other conditions were the same as in Example 2 except for the magnetic tape. Was prepared.
【００４１】このようにして得られた各種磁気テープに
ついて、ガイドピンに対する摩擦、電磁変換特性、テー
プの傷付き及び湿度９０％，温度６５℃の環境下にて１
０日間保存した後の残留磁束Φ１の初期値Φ２に対する
減少率ΔΦを調べた。The various magnetic tapes thus obtained were subjected to friction with guide pins, electromagnetic conversion characteristics, scratches on the tape, and humidity of 90% at a temperature of 65.degree.
Was examined reduction rate ΔΦ of the residual magnetic flux [Phi 1 after storage 0 days with respect to the initial value [Phi 2.
【００４２】なお、ガイドピンに対する摩擦は、スティ
ックスリップの程度により表し、その程度に応じて大、
中、小で示した。電磁変換特性は、周波数４．７ＭＨｚ
での出力の値である。The friction with respect to the guide pin is represented by the degree of stick-slip.
Medium and small. Electromagnetic conversion characteristics, frequency 4.7MHz
Is the value of the output at.
【００４３】また、残留磁束の減少率ΔΦは、下記の
（２）式で与えられる。The rate of decrease ΔΦ of the residual magnetic flux is given by the following equation (2).
【００４４】[0044]
【数１】 この結果を表３に示す。(Equation 1) Table 3 shows the results.
【００４５】[0045]
【表３】 表３に示すように、実施例２〜５においては、残留磁束
の減少率ΔΦが抑えられると同時に、ガイドピンに対す
る摩擦やテープの傷付きが小さく、且つ良好な電磁変換
特性が得られていることが判った。このことから、強磁
性金属粉末と結合剤の重量比Ｐ／Ｂが５〜６．５となる
ように調節することにより、良好な耐候性を確保できる
とともに、走行性や耐久性を著しく向上させることがで
き、また優れた出力特性が得られる。これに対して、上
記強磁性金属粉末と結合剤の重量比Ｐ／Ｂが小さいと、
結合剤が過剰に存在するためにガイドピンに対する摩擦
が増大し、走行性が劣化してしまう。逆に、上記強磁性
金属粉末と結合剤の重量比Ｐ／Ｂが大きすぎる場合に
は、結合剤の量が不足し、十分な耐久性を確保すること
ができない。[Table 3] As shown in Table 3, in Examples 2 to 5, the reduction rate ΔΦ of the residual magnetic flux was suppressed, and at the same time, the friction with the guide pin and the damage of the tape were small, and good electromagnetic conversion characteristics were obtained. It turns out. From this, by adjusting the weight ratio P / B of the ferromagnetic metal powder and the binder to be 5 to 6.5, good weather resistance can be ensured, and the running property and durability are remarkably improved. And excellent output characteristics can be obtained. On the other hand, when the weight ratio P / B of the ferromagnetic metal powder and the binder is small,
Excessive presence of the binder increases friction with the guide pin, resulting in poor running performance. Conversely, if the weight ratio P / B of the ferromagnetic metal powder and the binder is too large, the amount of the binder is insufficient, and sufficient durability cannot be secured.
【００４６】[0046]
【発明の効果】上述のように、本発明では、鉄を主成分
とする強磁性金属粉末のＢＥＴ比表面積と比重の積を制
限することによって表面が均一である状態を実現すると
ともに、この強磁性金属粉末の針状比を規定しているの
で、良好な磁気特性を有しつつ、且つ耐候性に優れた強
磁性金属粉末が得られる。As described above, in the present invention, a state where the surface is uniform is realized by limiting the product of the BET specific surface area and the specific gravity of the ferromagnetic metal powder containing iron as a main component, Since the acicular ratio of the magnetic metal powder is specified, a ferromagnetic metal powder having excellent magnetic properties and excellent weather resistance can be obtained.
【００４７】磁性粉末の耐候性の向上は、この磁性粉末
を用いた磁気記録媒体の耐候性の向上に直接反映される
ので、上述のような強磁性金属粉末を用いれば、高耐候
性を有する有用な磁気記録媒体が得られる。また、この
ような磁気記録媒体において、強磁性金属粉末と結合剤
の重量比を調節しているので、テープの摩擦が抑えら
れ、良好な走行性を確保することができる。The improvement of the weather resistance of the magnetic powder is directly reflected in the improvement of the weather resistance of the magnetic recording medium using the magnetic powder. Therefore, the use of the ferromagnetic metal powder as described above has high weather resistance. A useful magnetic recording medium is obtained. Further, in such a magnetic recording medium, since the weight ratio between the ferromagnetic metal powder and the binder is adjusted, the friction of the tape is suppressed, and good running properties can be secured.
【００４８】従って、本発明によれば、寿命の長期化と
同時に、信頼性の向上が図られる。Therefore, according to the present invention, the service life is extended and the reliability is improved.
【図１】鉄を主成分とする強磁性金属粉末のＢＥＴ比表
面積と比重の積と、この強磁性金属粉末を所定の環境下
で１週間放置した後の飽和磁化σS の劣化率との関係を
示す特性図である。FIG. 1 shows a relationship between a product of a BET specific surface area and a specific gravity of a ferromagnetic metal powder containing iron as a main component and a deterioration rate of a saturation magnetization σ s after the ferromagnetic metal powder is left under a predetermined environment for one week. FIG.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 桃井 彦佳 東京都品川区北品川６丁目５番６号 ソ ニー・マグネ・プロダクツ株式会社内 (72)発明者 佐々木 太郎 東京都品川区北品川６丁目５番６号 ソ ニー・マグネ・プロダクツ株式会社内 (72)発明者 渡辺 勝子 東京都品川区北品川６丁目５番６号 ソ ニー・マグネ・プロダクツ株式会社内 (56)参考文献 特開 昭62−95729（ＪＰ，Ａ) 特開 平３−189925（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hirokazu Momoi 6-5-6 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Magne Products Co., Ltd. (72) Inventor Taro Sasaki 6 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Magne Products Co., Ltd. (72) Inventor Katsuko Watanabe 6-5-6 Kita Shinagawa, Shinagawa-ku, Tokyo Sonny Magne Products Co., Ltd. (56) References JP-A Sho 62-95729 (JP, A) JP-A-3-189925 (JP, A)
Claims (1)
性金属粉末と結合剤とを主体とする磁性層が形成されて
なる磁気記録媒体において、 上記強磁性金属粉末のＢＥＴ比表面積（ｍ２／ｇ）と比
重（ｇ／ｃｃ）の積が１９０ｍ２／ｃｃ以上、２５０ｍ
２／ｃｃ以下であり、且つ針状比が５以上、２０以下で
あることを特徴とする磁気記録媒体。1. A magnetic recording medium comprising a nonmagnetic support and a magnetic layer mainly composed of a ferromagnetic metal powder mainly composed of iron and a binder, wherein the BET specific surface area of the ferromagnetic metal powder is (M 2 / g) multiplied by specific gravity (g / cc) is 190 m 2 / cc or more, 250 m
2 / cc or less and a needle ratio of 5 or more and 20 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16936791A JP3226564B2 (en) | 1991-06-14 | 1991-06-14 | Magnetic recording media |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16936791A JP3226564B2 (en) | 1991-06-14 | 1991-06-14 | Magnetic recording media |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05143960A JPH05143960A (en) | 1993-06-11 |
| JP3226564B2 true JP3226564B2 (en) | 2001-11-05 |
Family
ID=15885275
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16936791A Expired - Fee Related JP3226564B2 (en) | 1991-06-14 | 1991-06-14 | Magnetic recording media |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3226564B2 (en) |
-
1991
- 1991-06-14 JP JP16936791A patent/JP3226564B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05143960A (en) | 1993-06-11 |
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