JPS60263328A - Magnetic recording medium - Google Patents
Magnetic recording mediumInfo
- Publication number
- JPS60263328A JPS60263328A JP59118781A JP11878184A JPS60263328A JP S60263328 A JPS60263328 A JP S60263328A JP 59118781 A JP59118781 A JP 59118781A JP 11878184 A JP11878184 A JP 11878184A JP S60263328 A JPS60263328 A JP S60263328A
- Authority
- JP
- Japan
- Prior art keywords
- cobalt
- magnetic
- powder
- coercive force
- magnetic powder
- 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.)
- Granted
Links
Landscapes
- Paints Or Removers (AREA)
- Magnetic Record Carriers (AREA)
Abstract
Description
【発明の詳細な説明】
〔技術分野および目的〕
この発明は、磁性粉末としてコバルトを主体とした板状
で板面に平行な磁化容易軸を有する磁性粉末を用いた磁
気記録媒体に関し、前記磁性粉末の充填性、分散性およ
び磁性層の表面平滑性が良好で、電磁変換特性に優れた
磁気記録媒体を提供することを目的とする。Detailed Description of the Invention [Technical Field and Objective] The present invention relates to a magnetic recording medium using a magnetic powder mainly composed of cobalt, which is plate-shaped and has an axis of easy magnetization parallel to the plate surface. The object of the present invention is to provide a magnetic recording medium that has good powder filling properties, good dispersibility, and magnetic layer surface smoothness, and has excellent electromagnetic conversion characteristics.
磁気記録媒体は、通常、磁性粉末を結合剤樹脂とともに
基体上に塗着して磁性層を形成することによりつくられ
、このとき使用される磁性粉末としては磁気特性に優れ
、磁気記録媒体に高感度、高Ｓ／Ｎ比など各種の優れた
電磁変換特性を付与できるものが望まれる。Magnetic recording media are usually made by coating magnetic powder on a substrate together with a binder resin to form a magnetic layer.The magnetic powder used at this time has excellent magnetic properties and is suitable for magnetic recording media. What is desired is something that can provide various excellent electromagnetic conversion characteristics such as sensitivity and high S/N ratio.
このため、飽和磁化量の大きな鉄を主体とした針状の金
属磁性粉末を記録素子として使用すること（特開昭５５
−８２４０８号）が行われているが、この種の鉄を主体
とする針状の金属磁性粉末は、粒子径が小さくなりすぎ
ると、保磁力が高くなりすぎて磁気記録媒体用として適
さなくなるため、針状粒子の粒子径を少なくとも０．２
μ以上の大きさにしなければならず、このように粒子径
の比較的大きな金属磁性粉末を使用すると、粉末粒子の
充填性、分散性および配向性が悪く、磁性層の表面平滑
性も劣化して、良好な電磁変換特性が得られないという
難点がある。そこで、近年、鉄を主体とした針状の磁性
粉末に代わるものとして、飽和磁化量の大きな粒状のコ
バルト金属磁性粉末を使用することが試みられているが
、この種の粒状のコバルト金属磁性粉末を使用したもの
は、鉄を主体とした金属磁性粉末を使用したものに比し
、耐酸化性が良好でほぼ同等の電磁変換特性が得られる
ものの、保磁力の熱安定性が悪く、また粒状であるため
磁性層の表面平滑性も充分に良好にならず、いまひとつ
電磁変換特性を充分に向上させることができない。For this reason, it is necessary to use acicular magnetic metal powder mainly composed of iron, which has a large amount of saturation magnetization, as a recording element (Japanese Patent Laid-Open No. 55
-82408), but if the particle size of this type of iron-based acicular metal magnetic powder becomes too small, the coercive force becomes too high, making it unsuitable for use in magnetic recording media. , the particle size of the acicular particles is at least 0.2
If a metal magnetic powder with such a relatively large particle size is used, the filling, dispersibility, and orientation of the powder particles will be poor, and the surface smoothness of the magnetic layer will also deteriorate. However, there is a drawback that good electromagnetic conversion characteristics cannot be obtained. Therefore, in recent years, attempts have been made to use granular cobalt metal magnetic powder with a large amount of saturation magnetization as an alternative to needle-shaped magnetic powder mainly composed of iron. Compared to those using iron-based metal magnetic powder, those using magnetic powders have better oxidation resistance and almost the same electromagnetic conversion characteristics, but they have poor thermal stability of coercive force, and also have granular Therefore, the surface smoothness of the magnetic layer is not sufficiently improved, and the electromagnetic conversion characteristics cannot be sufficiently improved.
この発明はかかる観点から種々検討を行った結果、板状
で、板面に平行な磁化容易軸を有するコバルトを主体と
した金属磁性粉末を使用すれば、この種の金属磁性粉末
は、耐酸化性および保磁力の熱安定性が良好な上、平均
粒子径が０．１μ以下の超微粒子であっても、保磁力を
容易に調整することができるため、耐酸化性および保磁
力の熱安定性が良好でしかも好適な保磁力を有する磁気
記録媒体が得られ、また、比表面積が小さくて高い残留
磁化量を有し、さらに平均粒子径がきわめて小さいため
、磁性粉末の充填性、分散性および磁性層の表面平滑性
が良好で電磁変換特性に優れた磁気記録媒体が得られる
ことを見いだしてなされたもので、板状で、板面に平行
な磁化容易軸を有するコバルトを主体とした金属磁性粉
末を磁性層中に含有させたことを特徴とするものである
。As a result of various studies conducted from this viewpoint, the present invention found that if a metal magnetic powder mainly composed of cobalt is used, which is plate-shaped and has an axis of easy magnetization parallel to the plate surface, this type of metal magnetic powder can be oxidation-resistant. In addition to having good thermal stability in terms of oxidation resistance and coercive force, the coercive force can be easily adjusted even for ultrafine particles with an average particle size of 0.1μ or less, resulting in good thermal stability in oxidation resistance and coercive force. A magnetic recording medium with good properties and suitable coercive force can be obtained, and also has a small specific surface area and a high amount of residual magnetization, and also has an extremely small average particle size, which improves the filling and dispersibility of the magnetic powder. It was developed based on the discovery that a magnetic recording medium with good surface smoothness of the magnetic layer and excellent electromagnetic conversion characteristics could be obtained.It is plate-shaped and mainly made of cobalt with an axis of easy magnetization parallel to the plate surface. It is characterized by containing metal magnetic powder in the magnetic layer.
この発明において使用されるコバルトを主体とする金属
磁性粉末は、面心立方晶を多く含む六方晶系の板状の磁
性粉末で、板面に平行な磁化容易軸を有し、コバルトの
みからなるものの他、コバルトに、鉄、ニッケル、マン
ガン、クロム、銅、亜鉛、マグネシウム、カルシウム等
の金属を含有させたものなどが好適なものとして使用さ
れる。The cobalt-based metal magnetic powder used in this invention is a hexagonal plate-shaped magnetic powder containing many face-centered cubic crystals, has an axis of easy magnetization parallel to the plate surface, and is composed only of cobalt. In addition to cobalt, cobalt containing metals such as iron, nickel, manganese, chromium, copper, zinc, magnesium, and calcium is preferably used.
このような面心立方晶を多く含む六方晶系の板面に平行
な磁化容易軸を有する板状のコバルトを主体とした金属
磁性粉末は、鉄を主体とする針状の金属磁性粉末に比し
、比表面積が小さく、耐酸化性もはるかに高くて安定性
が高い。また、この種の板状のコバルトを主体とする金
属磁性粉末は、平均粒子径が０．１μ以下の超微粒子で
あっても、保磁力が高くなりすぎることがなく、保磁力
を自在に調整することができて磁気記録媒体用として適
した保磁力のものを容易に得ることができ、さらに、そ
の高い飽和磁化量と安定性から高い残留磁化量を有する
。従って、ごの種の板状のコバルトを主体とした金属磁
性粉末を使用すれば、磁性粉末の充填性、分散性および
配向性が充分に向上され、磁性層の表面平滑性も充分に
改善されて、ビデオ画質およびクロマ出力が顕著に向上
し、一段と電磁変換特性に優れた磁気記録媒体が得られ
る。The plate-shaped cobalt-based metal magnetic powder, which has an axis of easy magnetization parallel to the hexagonal plate surface containing many face-centered cubic crystals, is compared to the acicular metal magnetic powder mainly made of iron. However, it has a small specific surface area, much higher oxidation resistance, and is highly stable. In addition, this kind of plate-shaped metal magnetic powder mainly composed of cobalt has a coercive force that does not become too high even if it is ultrafine particles with an average particle size of 0.1μ or less, and the coercive force can be adjusted freely. Therefore, it is possible to easily obtain a coercive force suitable for use in magnetic recording media, and furthermore, it has a high residual magnetization due to its high saturation magnetization and stability. Therefore, if a plate-shaped metal magnetic powder mainly composed of cobalt is used, the filling properties, dispersibility, and orientation of the magnetic powder can be sufficiently improved, and the surface smoothness of the magnetic layer can also be sufficiently improved. As a result, video image quality and chroma output are significantly improved, and a magnetic recording medium with even better electromagnetic conversion characteristics can be obtained.
このような板状のコバルトを主体とする金属磁性粉末は
、コバルト塩をアルカリ溶液中で反応させて合成した水
酸化コバルトの板状の結晶の表面を必要な場合は焼結防
止剤で被覆した後、これを空気中あるいは不活性ガス中
で熱分解し、さらに４００℃以上の温度で、水素気流中
等で還元してつくられ、このような４００℃以上の温度
での還元によって六方晶の他に面心立方晶を多く含むコ
バルト金属磁性粉末となり、板面に平行な磁化容易軸を
有するコバルト金属磁性粉末が得られる。Such plate-shaped magnetic metal powder mainly composed of cobalt is produced by coating the surface of plate-shaped crystals of cobalt hydroxide synthesized by reacting cobalt salts in an alkaline solution with an anti-sintering agent if necessary. After that, it is thermally decomposed in air or in an inert gas, and further reduced at a temperature of 400°C or higher in a hydrogen stream, etc., and this reduction at a temperature of 400°C or higher produces hexagonal crystals and other crystals. A cobalt metal magnetic powder containing a large amount of face-centered cubic crystals is obtained, and a cobalt metal magnetic powder having an axis of easy magnetization parallel to the plate surface is obtained.
このようなコバルト金属磁性粉末の平均粒子径は、前記
のようにしてコバルト金属磁性粉末を製造する際、水酸
化コバルトの板状結晶の形成時に結晶成長速度をコント
ロールすることによって調整され、また同様に保磁力は
コバルト金属磁性粉末を製造する際、粒子サイズに加え
て、還元前の熱処理及び表面処理等の前処理の条件を変
えることによって調整される。このようにして平均粒子
径が調整されるコバルトを主成分とした金属磁性粉末は
、平均粒子径が０．２μより大きいと、これを用いて得
られる磁性層の表面平滑性を充分に良好にして電磁変換
特性を充分に向上することができないため、平均粒子径
が０．２μ以下のものであることが好ましい。しかし、
粒子径が０．０３μより小さいものでは塗料中での分散
が困難になり、その結果、角型が低下するため、粒子径
が０．０３〜０．２μの範囲内のものを使用するのが好
ましい。The average particle diameter of such cobalt metal magnetic powder is adjusted by controlling the crystal growth rate during the formation of plate-shaped crystals of cobalt hydroxide when producing the cobalt metal magnetic powder as described above, and by controlling the crystal growth rate during the formation of plate-shaped crystals of cobalt hydroxide. When producing cobalt metal magnetic powder, the coercive force is adjusted by changing the particle size as well as pretreatment conditions such as heat treatment and surface treatment before reduction. If the average particle size of the cobalt-based metal magnetic powder whose average particle size is adjusted in this way is larger than 0.2μ, the surface smoothness of the magnetic layer obtained using the powder will be sufficiently good. Since the electromagnetic conversion characteristics cannot be sufficiently improved by using the particles, it is preferable that the average particle diameter is 0.2 μm or less. but,
If the particle size is smaller than 0.03μ, it will be difficult to disperse in the paint, resulting in a decrease in squareness, so it is recommended to use particles with a particle size in the range of 0.03 to 0.2μ. preferable.
また、この種の板状で板面に平行な磁化容易軸を有する
コバルトを主体とする金属磁性粉末は、形状磁気異方性
に基づく保磁力成分が増加するため、保磁力の温度依存
性がよく、結晶磁気異方性が主体である粒状のコバルト
金属磁性粉末のように、加温されたりした場合に保磁力
が減少してしまうということもない。In addition, in this type of plate-shaped metal magnetic powder mainly composed of cobalt, which has an axis of easy magnetization parallel to the plate surface, the coercive force component based on shape magnetic anisotropy increases, so the temperature dependence of the coercive force increases. Unlike granular cobalt metal magnetic powder, which is mainly characterized by magnetocrystalline anisotropy, the coercive force does not decrease when heated.
この発明の磁気記録媒体を製造するには常法に準じて行
えばよく、たとえば、前記の板状で板面に平行な磁化容
易軸を有するコバルトを主体とした金属磁性粉末を、結
合剤樹脂、有機溶剤等とともに混合分散して磁性塗料を
調製し、これをポリエステルフィルムなどの基体上にロ
ールコータ−など任意の塗布手段によって塗布し、次い
で、必要な場合は磁性層の長平方向に磁場配向処理を行
うなどした後、乾燥すればよい。The magnetic recording medium of the present invention may be manufactured according to a conventional method. For example, the metal magnetic powder mainly composed of cobalt, which is plate-shaped and has an axis of easy magnetization parallel to the plate surface, is mixed with a binder resin. A magnetic paint is prepared by mixing and dispersing with an organic solvent, etc., and this is applied onto a substrate such as a polyester film using any coating means such as a roll coater, and then, if necessary, the magnetic layer is oriented in a magnetic field in the longitudinal direction. After processing, it may be dried.
ここに用い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、イソ
シアネート化合物など従来汎用されている結合剤樹脂が
広く用いられる。As the binder resin used here, conventionally widely used binder resins such as vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, cellulose resin, polyurethane resin, polyester resin, and isocyanate compound are widely used. It will be done.
また、有機溶剤としては、トルエン、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、テト
ラヒドロフラン、酢酸エチルなど従来から汎用されてい
る有機溶剤が、単独または二種以上混合して使用される
。Further, as the organic solvent, conventionally widely used organic solvents such as toluene, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, and ethyl acetate are used alone or in a mixture of two or more.
ｆ 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、分散剤、温湯剤、研磨剤、帯電防止剤
などを任意に添加使用してもよい。f Note that various commonly used additives, such as dispersants, hot water agents, abrasives, antistatic agents, etc., may be optionally added to the magnetic paint.
次に、この発明の実施例について説明する。 Next, embodiments of the invention will be described.
実施例１
（ｉＭＭコハルＩ・０．８２モルを２ρの水に溶解し、
この溶液を、２モルの苛性カリを熔解した２７！の苛性
カリ水溶液に加えて６０°Ｃの温度で攪拌し、水酸化コ
バルトの板状粒子（平均粒子径０．１μ）を得た。次い
でこの水酸化コバルト板状粒子７６ｇを０．５Ｎの苛性
カリ水溶液３ρ中に懸濁させ、よくかきまぜて分散させ
た。これに１モルのオルトケイ酸ソーダ（Ｎａ４ Ｓ
ｉ ０４ ）水溶液１４０ｍ１を加え、よくかきまぜな
がら徐々に炭酸ガスを吹き込み、炭酸ガスによりアルカ
リを中和してＰＨ８以下になるまでかきまぜて分散させ
ながら炭酸ガスを吹き込んだ。その後デカンテーション
法によって充分に磁性粉末を水洗し、乾燥させて、コバ
ルトに対するケイ素の含有量が２重量％に相当するケイ
素化合物被膜を有する水酸化コバルト板状粒子を得た。Example 1 (Dissolve iMM Kohar I・0.82 mol in 2ρ water,
This solution was prepared by dissolving 2 moles of caustic potash into 27! The mixture was added to an aqueous solution of caustic potassium and stirred at a temperature of 60°C to obtain plate-like particles of cobalt hydroxide (average particle size: 0.1 μm). Next, 76 g of the cobalt hydroxide plate-like particles were suspended in 3 ρ of a 0.5N aqueous solution of potassium hydroxide and thoroughly stirred to disperse them. To this, 1 mol of sodium orthosilicate (Na4S
i 04 ) 140 ml of aqueous solution was added, and while stirring well, carbon dioxide gas was gradually blown into the mixture. Carbon dioxide gas was blown into the mixture while stirring and dispersing it until the alkali was neutralized with carbon dioxide gas and the pH became 8 or lower. Thereafter, the magnetic powder was thoroughly washed with water by a decantation method and dried to obtain cobalt hydroxide plate-like particles having a silicon compound coating having a silicon content of 2% by weight relative to cobalt.
このようにして得られたケイ素化合物被膜を有する水酸
化コバルト板状粒子を空気中にて、７００℃で２時間加
熱し、その後、５００°Ｃで４時間水素気流中で加熱還
元してコバルト金属磁性粉末を得た。得られたコバルト
金属磁性粉末は、板状で板面に平行な磁化容易軸を有し
、平均粒子径は０．１μ、保磁力は８００エルステツド
で、飽和磁化量は１２５ｅｍｕ ／ｇであった。The thus obtained cobalt hydroxide plate-shaped particles having a silicon compound coating were heated in air at 700°C for 2 hours, and then heated at 500°C for 4 hours in a hydrogen stream to reduce the cobalt metal. A magnetic powder was obtained. The obtained cobalt metal magnetic powder was plate-shaped and had an axis of easy magnetization parallel to the plate surface, an average particle diameter of 0.1 μ, a coercive force of 800 oersteds, and a saturation magnetization of 125 emu /g.
また、このコバルト金属磁性粉末には、コバルトに対す
るケイ素の含有量が２重量％に相当する５ｉ０２が含有
されていた。Further, this cobalt metal magnetic powder contained 5i02, which had a silicon content of 2% by weight relative to cobalt.
このようにして得られたコバルト金属磁性粉末を使用し
、
コバルト金属磁性粉末 １００重量部
エスレソクＡ−５（積木化学工業 １３．７ 〃社製、
塩化ビニル−酢酸ビニル
一ビニルアルコール共重合体）
タケラックＥ−５５１（式日薬品 ８．７〃工業社製、
ウレタンプレポリマ
ー）
０
コロネ−）Ｌ（日本ポリウレタン ２．５〃ノン業社製
、三官能性低分子量
イソシアネート化合物）
パルミチン酸 ０．８〃
メチルイソブチルケトン ６４〃
トルエン ６４〃
の組成からなる組成物をボールミル中で７２時間混合分
散して、磁性塗料を調整した。この磁性塗料を厚さ１０
μのポリエステルヘ−スフイルム上に塗布し、乾燥厚が
４μの磁性層を形成した。次いで、この磁性層の表面処
理を行ったのち、所定の巾に裁断して、磁気テープをつ
（った。Using the cobalt metal magnetic powder thus obtained, 100 parts by weight of cobalt metal magnetic powder Esresoku A-5 (manufactured by Block Chemical Industry Co., Ltd. 13.7,
Vinyl chloride-vinyl acetate-vinyl alcohol copolymer) Takelac E-551 (Shikinichi Yakuhin 8.7 manufactured by Kogyo Co., Ltd.,
Urethane prepolymer) 0 Coronae) L (Nippon Polyurethane 2.5〃Nongyo Co., Ltd., trifunctional low molecular weight isocyanate compound) Palmitic acid 0.8〃 Methyl isobutyl ketone 64〃 Toluene 64〃 A magnetic paint was prepared by mixing and dispersing in a ball mill for 72 hours. Apply this magnetic paint to a thickness of 10
A magnetic layer having a dry thickness of 4 .mu. Next, this magnetic layer was subjected to surface treatment, and then cut into a predetermined width to form a magnetic tape.
実施例２
実施例１におけるコバルト金属磁性粉末の合成において
、硝酸コバルトの水溶液中に新たに硝酸ニッケルを０．
０５モル添加して、５％の水酸化ニッケルを共沈させて
なる板状の水酸化コバルト粒子を得、これを実施例１と
同様にして加熱し、さらに加熱還元してニッケルを含有
したコバルト金属磁性粉末を製造した。得られたニッケ
ル含有コバｌｌ
ルト金属磁性粉末は、板状で、板面に平行な磁化容易軸
を有し、平均粒子径は０．１μ、保磁力は８２０エルス
テツド、飽和磁化量は１１５ｅｍｕ ７ｇで、コバルト
とニッケルの合計量に対してケイ素が２重量％に相当す
る５ｉ０２が含有されていた。また、ニッケルの含有量
はコバルトとニッケルの合計量に対して５重量％であっ
た。次いで、これを実施例１におけるコバルト金属磁性
粉末に代えて同量使用した以外は実施例１と同様にして
磁気テープをつくった。Example 2 In the synthesis of the cobalt metal magnetic powder in Example 1, 0.00% of nickel nitrate was newly added to an aqueous solution of cobalt nitrate.
Co-precipitated with 5% nickel hydroxide to obtain plate-shaped cobalt hydroxide particles, heated in the same manner as in Example 1, and further reduced by heating to produce cobalt containing nickel. A metal magnetic powder was produced. The obtained nickel-containing cobalt metal magnetic powder is plate-shaped, has an axis of easy magnetization parallel to the plate surface, has an average particle diameter of 0.1 μ, a coercive force of 820 oersted, and a saturation magnetization of 115 emu 7 g. , 5i02 contained silicon in an amount corresponding to 2% by weight based on the total amount of cobalt and nickel. Further, the content of nickel was 5% by weight based on the total amount of cobalt and nickel. Next, a magnetic tape was produced in the same manner as in Example 1 except that the same amount of this was used in place of the cobalt metal magnetic powder in Example 1.
実施例３
実施例１におけるコバルト金属磁性粉末の合成において
、水酸化コバルトの析出温度を６０℃から３０℃に変更
した以外は実施例１と同様にしてコバルト金属磁性粉末
を製造した。得られたコバルト金属磁性粉末は、板状で
、板面に平行な磁化容易軸を有し、平均粒子径は０．０
７μ、保磁力は６７０エルステツドで、飽和磁化量は、
１２０ｅｍｕ／ｇであった。次いで、これを実施例１に
おけるコバルト金属磁性粉末に代えて同量使用した以外
は実施例１と同様にして磁気テープをつくった。Example 3 A cobalt metal magnetic powder was produced in the same manner as in Example 1 except that the precipitation temperature of cobalt hydroxide was changed from 60°C to 30°C in the synthesis of the cobalt metal magnetic powder in Example 1. The obtained cobalt metal magnetic powder is plate-shaped, has an axis of easy magnetization parallel to the plate surface, and has an average particle diameter of 0.0.
7μ, coercive force is 670 oersted, and saturation magnetization is:
It was 120 emu/g. Next, a magnetic tape was produced in the same manner as in Example 1 except that the same amount of this was used in place of the cobalt metal magnetic powder in Example 1.
比較例１
実施例１におけるコバルト金属磁性粉末の合成において
、水素気流中での還元温度および時間を、５００℃、４
時間から３５０℃、８時間に変更した以外は実施例１と
同様にしてコバルト金属磁性粉末を得た。得られたコバ
ルト金属磁性粉末は、板状で板面に平行な磁化容易軸を
有し、平均粒子径は０．１μ、保磁力は５８０エルステ
ツド、飽和磁化量は８５ｅｍｕ／ｇであった。またコバ
ルトに対してケイ素が２重量％に相当する５ｉ０２が含
有されていた。次いで、これを実施例１におけるコバル
ト金属磁性粉末に代えて同量使用した以外は実施例１と
同様にして磁気テープをつくった。Comparative Example 1 In the synthesis of cobalt metal magnetic powder in Example 1, the reduction temperature and time in a hydrogen stream were changed to 500°C, 4
Cobalt metal magnetic powder was obtained in the same manner as in Example 1 except that the heating time was changed to 350° C. for 8 hours. The obtained cobalt metal magnetic powder was plate-shaped and had an axis of easy magnetization parallel to the plate surface, an average particle diameter of 0.1 μ, a coercive force of 580 oersted, and a saturation magnetization of 85 emu/g. Further, 5i02 containing silicon corresponding to 2% by weight with respect to cobalt was contained. Next, a magnetic tape was produced in the same manner as in Example 1 except that the same amount of this was used in place of the cobalt metal magnetic powder in Example 1.
比較例２
実施例１における磁性塗料の組成において、コバルト金
属磁性粉末に代えて、平均粒子径が０．５μ、保磁力が
８２０エルステツド、鉄に対してケイ素が２重量％に相
当する５ｉ０２が含有された針状の金属鉄磁性粉末を同
量使用した以外は実施３
例１と同様にして磁気テープをつくった。Comparative Example 2 In the composition of the magnetic paint in Example 1, instead of the cobalt metal magnetic powder, 5i02, which has an average particle diameter of 0.5 μm, a coercive force of 820 oersted, and a silicon content equivalent to 2% by weight with respect to iron, is contained. Example 3 A magnetic tape was produced in the same manner as in Example 1, except that the same amount of the acicular iron magnetic powder was used.
比較例３
実施例１における磁性塗料の組成において、コバルト金
属磁性粉末に代えて、平均粒子径が０．１μ、保磁力が
８１０エルステツド、コバルトに対してケイ素が２重量
％に相当する５ｉ０２が含有された粒状のコバルト金属
磁性粉末を同量使用した以外は実施例１と同様にして磁
気テープをつくった。Comparative Example 3 In the composition of the magnetic paint in Example 1, instead of the cobalt metal magnetic powder, 5i02, which has an average particle diameter of 0.1 μ, a coercive force of 810 oersted, and silicon equivalent to 2% by weight with respect to cobalt, is contained. A magnetic tape was produced in the same manner as in Example 1, except that the same amount of the granular cobalt metal magnetic powder was used.
各実施例および各比較例で得られた磁気テープについて
、保磁力、最大磁束密度、角型、ビデオ出力、Ｃ／Ｎ、
カラーＳ／Ｎ、表面粗度、粒度分布を測定し、耐食性を
試験した。ビデオ出力は、４ＭＩＩｚのキャリア信号を
記録再生したときの出力レベルをＹＨＰ社製スペクトロ
アナライザーによって測定し、またＣ／Ｎは、１〜７Ｍ
１ｌｚまでの全ノイズと４Ｍ１ｌｚのキャリアレベルと
の比をめて測定した。また、カラーＳ／Ｎは、得られた
磁気テープを日立製作所社製Ｖ Ｔ ’Ｈにかけて、テ
レビジョン信号発生器により規定のカラー信号（−色４
クロマ信号）を記録再生してビデオカラーノイズメータ
ーにより測定し、表面粗度は、東京精機社製、触針式表
面粗度計を用いてカットオフ０．０８ｎで中心線平均粗
度を測定した。さらに、粒度分布は、電子顕微鏡による
形状観察写真から粒子１０００個の粒度を測定し、その
分布曲線の極大ピークの半価幅から算定した。この粒度
分布は数値が小さいほど分布の広がりが狭く、粒子径が
均一になっていることを示す。また、耐食性試験は、得
られた磁気テープを６０℃、９０％ＲＨの条件下に７日
間放置し、放置後の最大磁束密度の劣化率を、放置前の
磁気テープの最大磁束密度を１００％として、これと比
較した値でその劣化率を調べて行った。下表はその結果
である。Regarding the magnetic tapes obtained in each example and each comparative example, coercive force, maximum magnetic flux density, square shape, video output, C/N,
Color S/N, surface roughness, and particle size distribution were measured, and corrosion resistance was tested. For the video output, the output level when recording and reproducing a 4MIIz carrier signal was measured using a YHP spectroanalyzer, and the C/N was 1 to 7M.
The ratio between the total noise up to 1lz and the carrier level of 4M1lz was measured. Color S/N can also be measured using a video color noise meter by applying the obtained magnetic tape to V T'H manufactured by Hitachi, Ltd., recording and reproducing a specified color signal (-color 4 chroma signal) using a television signal generator. The surface roughness was measured by measuring the center line average roughness using a stylus type surface roughness meter manufactured by Tokyo Seiki Co., Ltd. at a cutoff of 0.08n. Furthermore, the particle size distribution was calculated from the half width of the maximum peak of the distribution curve by measuring the particle size of 1000 particles from a shape observation photograph taken with an electron microscope. In this particle size distribution, the smaller the numerical value, the narrower the spread of the distribution, indicating that the particle size is more uniform. In addition, in the corrosion resistance test, the obtained magnetic tape was left under the conditions of 60°C and 90% RH for 7 days, and the deterioration rate of the maximum magnetic flux density after being left was measured, and the maximum magnetic flux density of the magnetic tape before being left was 100%. The deterioration rate was investigated using the values compared with this value. The table below shows the results.
また、実施例１および比較例３で得られた磁気テープを
、液体窒素で冷却した後、徐々に加熱し、各温度におけ
る保磁力を測定した。第１図はその結果をグラフで表し
たもので、グラフＡは実施例１で得られた磁気テープを
示し、グラフＢは比較例３で得られた磁気テープを示す
。Further, the magnetic tapes obtained in Example 1 and Comparative Example 3 were cooled with liquid nitrogen and then gradually heated, and the coercive force at each temperature was measured. FIG. 1 shows the results in graphs, where graph A shows the magnetic tape obtained in Example 1, and graph B shows the magnetic tape obtained in Comparative Example 3.
ｌ６
〔発明の効果〕
上表から明らかなように、この発明で得られた磁気テー
プ（実施例１ないし３）は、比較例１ないし３で得られ
た磁気テープに比し、角型、ビデオ出力、Ｃ／Ｎ、カラ
ーＳ／Ｎが高く、粒度分布が小さくて、表面粗度も小さ
く、このことがらこの発明によって得られる磁気記録媒
体は、磁性粉末の充填性、分散性に優れ、磁性層の表面
平滑性が良好で電磁変換特性に優れていることがわかる
。また、第１図に示すグラフから明らかなように、比較
例３で得られた磁気テープは温度が高くなるに従って保
磁力が急激に低下しているが、実施例１で得られた磁気
テープは比較例３の磁気テープはど急激な保磁力の低下
が見られず、このことからこの発明によって得られる磁
気記録媒体は、保磁力の熱安定性も良好であることがわ
かる。l6 [Effects of the Invention] As is clear from the table above, the magnetic tapes obtained by the present invention (Examples 1 to 3) have a rectangular shape and a video tape, compared to the magnetic tapes obtained in Comparative Examples 1 to 3. The magnetic recording medium obtained by this invention has high output, C/N, and color S/N, small particle size distribution, and small surface roughness. It can be seen that the layer has good surface smoothness and excellent electromagnetic conversion characteristics. Furthermore, as is clear from the graph shown in FIG. 1, the coercive force of the magnetic tape obtained in Comparative Example 3 decreases rapidly as the temperature increases, whereas the magnetic tape obtained in Example 1 The magnetic tape of Comparative Example 3 showed no sudden decrease in coercive force, which indicates that the magnetic recording medium obtained by the present invention also has good thermal stability of coercive force.
第１図は実施例１および比較例３で得られた磁気テープ
の保磁力と温度との関係図である。
１５９−FIG. 1 is a diagram showing the relationship between coercive force and temperature of the magnetic tapes obtained in Example 1 and Comparative Example 3. 159-
Claims (1)
主体とした磁性粉末を磁性層中に含有させたことを特徴
とする磁気記録媒体。1. A magnetic recording medium characterized in that a magnetic layer contains a magnetic powder mainly composed of cobalt, which is plate-shaped and has an axis of easy magnetization parallel to the plate surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59118781A JPS60263328A (en) | 1984-06-09 | 1984-06-09 | Magnetic recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59118781A JPS60263328A (en) | 1984-06-09 | 1984-06-09 | Magnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60263328A true JPS60263328A (en) | 1985-12-26 |
| JPH0467687B2 JPH0467687B2 (en) | 1992-10-29 |
Family
ID=14744921
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59118781A Granted JPS60263328A (en) | 1984-06-09 | 1984-06-09 | Magnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60263328A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5057299A (en) * | 1989-12-08 | 1991-10-15 | Minnesota Mining And Manufacturing Company | Method for making beta cobaltous hydroxide |
-
1984
- 1984-06-09 JP JP59118781A patent/JPS60263328A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5057299A (en) * | 1989-12-08 | 1991-10-15 | Minnesota Mining And Manufacturing Company | Method for making beta cobaltous hydroxide |
| US5338473A (en) * | 1989-12-08 | 1994-08-16 | Minnesota Mining And Manufacturing Company | Aqueous beta cobaltous hydroxide and method for making |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0467687B2 (en) | 1992-10-29 |
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