JPS6194229A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the color S/N and still characteristics by forming a magnetic layer contg. magnetic powder and magnetic powder of hexagonal ferrite having <=600Oe coercive force, <=5 aspect ratio and a regulated particle size in a specified mixing ratio. CONSTITUTION:A magnetic layer contg. 100pts.wt. magnetic powder having >=70emu/g saturation magnetization and <=5pts.wt. magnetic powder of hexagonal ferrite having an axis of easy magnetization in the direction of the c-axis, <=600Oe coercive force, <=5 aspect ratio and 0.2-0.5mum particle size is formed. The resulting magnetic recording medium can attain high reproduction output when a ringlike magnetic head of ferrite is used, and medium is suitable for high density recording. The reproduction output of a magnetic recording medium in a high frequency region is improved by using a small amount of magnetic powder of hexagonal ferrite mixed with a large amount of needlelike ferromagnetic powder, and the medium can be adapted to high density recording. The reproduction output in a low frequency region is improved by the horizontally magnetizable component of the needlelike ferromagnetic powder. The medium has improved color S/N, still characteristics, traveling performance and reproduction output.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、例えばオーディオテープ、ビデオテープ等の
磁気テープ、又は７ａツピーデイスク、ハードディスク
等の磁気ディスクといった磁気記録媒体に関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium such as a magnetic tape such as an audio tape or a video tape, or a magnetic disk such as a 7A disk or a hard disk.

〔従来技術とその問題点〕[Prior art and its problems]

従来、磁気記録媒体としては、針状γ−ＦｅｓＯｘ磁性
粉を含む磁性塗料を非磁性基体上に塗布し、そして機械
配向あるいは磁場配向といった配向処理によって磁化を
面内長手方向に配向させた、いわゆる水平磁気記録方式
のものが主である。Conventionally, magnetic recording media have been produced by coating a magnetic paint containing acicular γ-FesOx magnetic powder on a non-magnetic substrate, and then oriented the magnetization in the in-plane longitudinal direction by an orientation treatment such as mechanical orientation or magnetic field orientation. The main type is horizontal magnetic recording.

しかし、この種の水平磁気記録方式の磁気記録媒体は、
記録信号が短波長のものであると、自己減磁作用が大き
くなって再生出力が低下するので、高密度装置には適し
ていない。However, this type of horizontal magnetic recording type magnetic recording medium is
If the recording signal has a short wavelength, the self-demagnetizing effect increases and the reproduction output decreases, making it unsuitable for high-density devices.

そこで、このような欠点を解決するものとして、いわゆ
る垂直磁気記録方式の磁気記録媒体が提案されておシ、
例えば強磁性粉末と六方晶系フェライト磁性粉末、特に
平均粒径０．２μｍ以下の六方晶系フェライト粉末５〜
１００重量部と、飽和磁化７０ｅ　ｍ　ｕ／ｇ以上で平
均粒径が該六方晶系フェライト粉末の平均粒径より大き
い強磁性粉末とを、樹脂バインダー中に分散させてなる
磁気記録媒体が提案（特開昭５８−２０３６２５号）さ
れている。Therefore, as a solution to these drawbacks, a so-called perpendicular magnetic recording type magnetic recording medium has been proposed.
For example, ferromagnetic powder and hexagonal ferrite magnetic powder, especially hexagonal ferrite powder with an average particle size of 0.2 μm or less.
A magnetic recording medium is proposed in which 100 parts by weight of ferromagnetic powder with a saturation magnetization of 70 e m u/g or more and an average particle size larger than the average particle size of the hexagonal ferrite powder are dispersed in a resin binder ( JP-A No. 58-203625).

すなわち、この提案の技術思想は、単に強磁性粉末と六
方晶系フェライト磁性粉末を用いたのみでは、磁性塗料
の分散性が悪いことから磁気特性の低下をもたらしてい
るので、上記提案のように構成すれば磁性塗料の分散性
が向上し、よって磁気特性良好な磁気記録媒体が得られ
ると述べているのである。In other words, the technical idea of this proposal is that simply using ferromagnetic powder and hexagonal ferrite magnetic powder would result in a decrease in magnetic properties due to poor dispersibility of the magnetic paint. It is stated that if this configuration is adopted, the dispersibility of the magnetic coating material will be improved, and thus a magnetic recording medium with good magnetic properties can be obtained.

ところが、本発明者の研究によれば、この提案の磁気記
録媒体でも高密度記録用としては充分満足できるもので
もないことがわかってきた。However, according to research conducted by the present inventors, it has been found that even this proposed magnetic recording medium is not fully satisfactory for high-density recording.

〔発明の一示〕[Disclosure of the invention]

本発明者は、現在記録再生装置等に組み込まれているリ
ング型のフェライト磁気ヘッドによって大きな再生出力
を得ることができ、かつ高密度記録にも対応できる磁気
記録媒体の研究を進めているうちに、飽和磁化７０ｅｍ
ｕ／ｇ以上の磁性粉末と、イズが０．２〜０．５μｍの
六方晶系フェライト磁性粉末とを磁性層中に含み、前記
磁性粉末１００重量部に対し前記六方晶系フェライト磁
性粉末が５重量部以下の割合よシなる磁気記録媒体は、
リング型フェライト磁気ヘッドによって大きな再生出力
を得ることの出来るものであり、かつ高密度記録にも適
したものであることを見い出した。The present inventor has been conducting research on magnetic recording media that can obtain large playback output using ring-shaped ferrite magnetic heads that are currently incorporated in recording and playback devices, and can also handle high-density recording. , saturation magnetization 70em
The magnetic layer contains a magnetic powder of 0.2 to 0.5 μm and a hexagonal ferrite magnetic powder of 0.2 to 0.5 μm, and the hexagonal ferrite magnetic powder is A magnetic recording medium with a proportion of less than parts by weight is
It has been found that a ring-type ferrite magnetic head can provide a large reproduction output and is also suitable for high-density recording.

つ−！シ、少量の六方晶系フェライト磁性粉を多量の針
状強磁性粉に混入して用いることにより、六方晶系フェ
ライト磁性粉の垂直磁化成分が有効に利用できて高周波
領域での再生出力が向上し、高密度記録に対応できるも
のとなシ、又、針状強磁性粉の水平磁化成分が有効に利
用できて低周波領域での再生出力は向上する。Tsu-! By mixing a small amount of hexagonal ferrite magnetic powder with a large amount of acicular ferromagnetic powder, the perpendicular magnetization component of the hexagonal ferrite magnetic powder can be used effectively, improving reproduction output in the high frequency range. However, since it is compatible with high-density recording, and the horizontal magnetization component of the acicular ferromagnetic powder can be effectively used, the reproduction output in the low frequency region is improved.

そして、特に例えばバリウムフェライト磁性粉、ストロ
ンチウムフェライト磁性粉、カルシウムフェライト磁性
粉、鉛フェライト磁性粉ある゛いは置換型バリウムフェ
ライト磁性粉といった六方晶系フェライト磁性粉末の板
状比が約５以下、より一層好ましくは約１以上で５未満
であるものを用いることによって、磁性塗料の分散性が
向上し、カラーＳ／Ｎといった磁気特性も向上すること
より、六方晶系フェライト磁性粉の板状比は約５以下で
あることが望ましい。In particular, the plate ratio of hexagonal ferrite magnetic powder such as barium ferrite magnetic powder, strontium ferrite magnetic powder, calcium ferrite magnetic powder, lead ferrite magnetic powder, or substituted barium ferrite magnetic powder is about 5 or less, and more More preferably, by using powder having a value of about 1 or more and less than 5, the dispersibility of the magnetic coating material is improved and the magnetic properties such as color S/N are also improved. Desirably, it is about 5 or less.

又、研磨性に優れ、さらには滑剤の吸着量を少なくして
、磁気記録媒体の走行性及び耐久性の改善を図るには、
′板状比が５以下の六方晶系フェライト磁性粉末の平均
粒径が約０．２〜０．５°μｍのものであることが望ま
しい。In addition, in order to improve the running performance and durability of magnetic recording media by having excellent polishing properties and reducing the amount of lubricant adsorbed,
It is desirable that the average particle diameter of the hexagonal ferrite magnetic powder having a platelet ratio of 5 or less is about 0.2 to 0.5 μm.

特に、この場合の板状比が５以下で平均粒径が０．２〜
０．５μｍの六方晶系フェライト磁性粉末の含有量は、
針状の強磁性粉末１００重量部に対して約５重量部以下
、よシ一層好ましくは約０．１重量部以上で５重量部未
満のものであることが、分散性の向上といった面から望
ましい。In particular, in this case, the platelet ratio is 5 or less and the average particle size is 0.2 to
The content of 0.5 μm hexagonal ferrite magnetic powder is
From the viewpoint of improving dispersibility, it is desirable that the amount is about 5 parts by weight or less, more preferably about 0.1 parts by weight or more and less than 5 parts by weight, based on 100 parts by weight of the acicular ferromagnetic powder. .

又、上記のような六方晶系フェライト磁性粉末の保磁力
は約６００エルステッド以下のものを用いることによっ
て、良好な消去特性の得られるものとなる。Further, by using the above-mentioned hexagonal ferrite magnetic powder having a coercive force of about 600 Oe or less, good erasing characteristics can be obtained.

又、飽和磁化約７０ｅｍｕ／ｇ以上の磁性粉としては、
例えばｒ　−Ｆｅｔｕｓ　、　Ｃｏ被着ｒ−Ｆｅｔｏｓ
　、Ｆｅ５０４、Ｃｒｏｗ　、　Ｆｅ　Ｉ）るいは合金
粉末等の針状（針状比が好ましくは約５〜１５）強磁性
粉があり、このような磁性粉末の飽和磁化は約７０ｅｍ
ｕ／ｇ以上のものでなければ低周波領域での再生出力は
低下するものとなる。In addition, as magnetic powder with saturation magnetization of about 70 emu/g or more,
For example, r-Fetus, Co-coated r-Fetos
, Fe504, Crow, Fe I) or alloy powders, etc., are needle-shaped (acicularity ratio is preferably about 5 to 15) ferromagnetic powders, and the saturation magnetization of such magnetic powders is about 70 em
If the value is not higher than u/g, the reproduction output in the low frequency region will decrease.

〔実施例１〕 六方晶系バリウムフェライト磁性粉（飽和磁化Ｍｓ約５
４ｅｍｕ／ｇ、保磁力Ｈｃ約５８００ｅ、平均粒径的０
．２５μｍ、板状比的４．５　）　４重量部、ＣＯ含有
７−Ｆｅｘ０３磁性粉（Ｍｓ約７５ｅｍｕ／ｇ　、　Ｈ
’ｃ約６１５０ｅ、平均粒径的０．２μｍ、針状比的１
０）　１００重量部、塩化ビニル−ビニルアルコール共
重合体１５重量部、ポリウレタンエラストマー１５重量
部、レシチン１重量部、カーボンブラック６重量部、オ
レイン酸３重量部、トルエンとメチルエチルケトンの等
量混合溶痢３００重量部の混合物をサンドミルで所定時
間混合分散して磁性塗料を作る。[Example 1] Hexagonal barium ferrite magnetic powder (saturation magnetization Ms approximately 5
4 emu/g, coercive force Hc approximately 5800e, average particle size 0
．． 25 μm, plate-like ratio 4.5) 4 parts by weight, CO-containing 7-Fex03 magnetic powder (Ms approx. 75 emu/g, H
'c approx. 6150e, average particle size 0.2μm, needle-like ratio 1
0) 100 parts by weight, 15 parts by weight of vinyl chloride-vinyl alcohol copolymer, 15 parts by weight of polyurethane elastomer, 1 part by weight of lecithin, 6 parts by weight of carbon black, 3 parts by weight of oleic acid, and a mixture of equal amounts of toluene and methyl ethyl ketone. A magnetic paint is prepared by mixing and dispersing 300 parts by weight of the mixture in a sand mill for a predetermined period of time.

そして、この磁性塗料にポリイソシアネート（コロネー
トＬ、日本ポリウレタン製）１５重量部を添加し、これ
をポリエステルフィルムに塗布乾燥後、カレンダー処理
を施し、百インチ幅にスリットしてビデオ用磁気テープ
及び５．２５インチの径で打ち抜いてフロッピーディス
クを構成した。Then, 15 parts by weight of polyisocyanate (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added to this magnetic paint, and this was applied to a polyester film. After drying, it was calendered and slit into 100-inch widths to be used as video magnetic tapes. A floppy disk was constructed by punching out a piece with a diameter of .25 inches.

〔実施例２〕 六方晶系置換型バリウムフェライト磁性粉（Ｍｓ約５４
　ｅｍｕ／ｇ、　Ｈｅ約５４００ｅ、平均粒通約０．４
０ｐｍ、板状比約３．５）３重量部、Ｃｒ０＝磁性粉（
Ｍｓ約７０　ｅｍｕ／ｇ　、　Ｈｅ約６０００ｅ、平均
粒通約０．２μｍ、針状比的１０）　１００重量部、ニ
トロセルロース１３重量部、ポリウレタンエラストマー
１５重量部、レシチン１重量部、カーボンブラック４重
量部、オレイン酸３重量部、メチルエチルケトンとメチ
ルイソブチルケトンの等量混合溶剤３００重量部の混合
物をサンドミルで所定時間混合分散して磁性塗料を作り
、以下実施例１と同様にしてビデオ用磁気テープ及びフ
ロッピーディスクを構成した。[Example 2] Hexagonal substituted barium ferrite magnetic powder (Ms approx. 54
emu/g, He approx. 5400e, average grain size approx. 0.4
0pm, plate ratio approximately 3.5) 3 parts by weight, Cr0=magnetic powder (
Ms approx. 70 emu/g, He approx. 6000 e, average grain diameter approx. 0.2 μm, needle-like specificity 10) 100 parts by weight, nitrocellulose 13 parts by weight, polyurethane elastomer 15 parts by weight, lecithin 1 part by weight, carbon black 4 parts by weight 1 part by weight, 3 parts by weight of oleic acid, and 300 parts by weight of a mixed solvent of equal amounts of methyl ethyl ketone and methyl isobutyl ketone were mixed and dispersed in a sand mill for a predetermined period of time to prepare a magnetic paint. Configured a floppy disk.

〔実施例３〕 六方晶系置換型バリウムフェライト磁性粉（Ｍｓ約５４
　ｅｍｕ　７ｇ　、　Ｈｅ約５５００ｅ、平均粒径０．
４５μｍ、板状比約３　）　３．５重量部、Ｆ　ｅ　ｓ
　Ｏ４磁性粉（Ｍｓ約８２　ｅｍｕ　／　ｇ、　Ｈｅ約
６３００ｅ、平均粒通約０．２μｍ。[Example 3] Hexagonal substituted barium ferrite magnetic powder (Ms approx. 54
emu 7g, He about 5500e, average particle size 0.
45μm, plate ratio approximately 3) 3.5 parts by weight, Fes
O4 magnetic powder (Ms approx. 82 emu/g, He approx. 6300e, average particle diameter approx. 0.2 μm.

針状比的１０）　１００重量部、塩化ビニル−ビニルア
ルコール共重合体１５重量部、ポリウレタンエラストマ
ー１５重量部、レシチン１重量部、カーボンブラック４
重量部、オレイン酸３重量部、トルエンとメチルインブ
チルケトンの等量混合溶剤３００重量部の混合物をサン
ドミルで所定時間混合分散して磁性塗料を作り、以下実
施例１と同様にしてビデオ用磁気テープ及びフロッピー
ディスクを構成した。Acicular ratio 10) 100 parts by weight, vinyl chloride-vinyl alcohol copolymer 15 parts by weight, polyurethane elastomer 15 parts by weight, lecithin 1 part by weight, carbon black 4
A magnetic paint was prepared by mixing and dispersing a mixture of 1 part by weight, 3 parts by weight of oleic acid, and 300 parts by weight of a mixed solvent of equal amounts of toluene and methyl imbutyl ketone for a predetermined time using a sand mill. Constructed tape and floppy disk.

〔実施例４〕 六方晶系バリウムフェライト磁性粉（Ｍｓ約５４ｅｍｕ
／ｇ、　Ｈｅ約５６００ｅ、平均粒通約０．３μｍ、板
状比約４．５　）　４重量部、強磁性鉄粉末（Ｍｓ約１
２５ｅｍｕ／ｇ、Ｈｅ約１２０００ｅ、平均粒通約０．
２μｍ、針状比的１０）　１００重量部、塩化ビニル−
酢酸ビニル共重合体２０重量部、ポリウレタンニジスト
マー２０重量部、レシチン３重量部、カーボンブラック
３重量部、オレイン酸３重量部、トルエンとメチルエチ
ルケトンの等量混合溶剤３６０重量部の混合物をサンド
ミルで所定時間混合分散して磁性塗料を作シ、以下実施
例１と同様にしてビデオ用磁気テープ及びフロッピーデ
ィスクを構成した。[Example 4] Hexagonal barium ferrite magnetic powder (Ms approximately 54 emu
/g, He about 5600e, average grain size about 0.3 μm, plate ratio about 4.5) 4 parts by weight, ferromagnetic iron powder (Ms about
25emu/g, He about 12000e, average grain size about 0.
2 μm, acicular (specifically 10) 100 parts by weight, vinyl chloride
A mixture of 20 parts by weight of vinyl acetate copolymer, 20 parts by weight of polyurethane distomer, 3 parts by weight of lecithin, 3 parts by weight of carbon black, 3 parts by weight of oleic acid, and 360 parts by weight of a mixed solvent of equal amounts of toluene and methyl ethyl ketone was prepared using a sand mill. A magnetic coating material was prepared by time mixing and dispersion, and a video magnetic tape and a floppy disk were constructed in the same manner as in Example 1.

〔実施例５〕 実施例１において、Ｍｓ約５４　ｅｍｕ　／　ｇ、　、
Ｈｅ約５０００ｅ、平均粒通約０．２５μｍ、板状比約
４．５の六方晶系バリウムフェライト磁性粉を用いて同
様に行い、ビデオ用磁気テープ及びフロッピーディスク
を構成した。[Example 5] In Example 1, Ms about 54 emu/g, ,
A video magnetic tape and a floppy disk were constructed in the same manner using hexagonal barium ferrite magnetic powder having a He of about 5000e, an average grain size of about 0.25 μm, and a platelet ratio of about 4.5.

〔比較例１〕 実施例１において、六方晶系バリウムフェライト磁性粉
を１０重量部として同様に行い、ビデオ用磁気テープ及
びフロッピーディスクを構成した。[Comparative Example 1] The same procedure as in Example 1 was carried out except that 10 parts by weight of hexagonal barium ferrite magnetic powder was used to construct a video magnetic tape and a floppy disk.

〔比較例２〕 実施例２において、六方晶系置換型バリウムフェライト
磁性粉を３０重量部として同様に行い、ビデオ用磁気テ
ープ及びフロッピーディスクを構成した。[Comparative Example 2] A video magnetic tape and a floppy disk were prepared in the same manner as in Example 2 except that the hexagonal substituted barium ferrite magnetic powder was used in an amount of 30 parts by weight.

〔比較例３〕。[Comparative Example 3].

実施例１において、Ｍｓ約５４ｅｍｕ／ｇ、　Ｈｅ約５
８００ｅ１平均粒径約Ｑ、７ｐｍ、板状比約４．５の六
方晶系バリウムフェライト磁性粉を用いて同様に行い、
ビデオ用磁気テープ及びフロッピーディスクを構成した
。In Example 1, Ms about 54 emu/g, He about 5
The same procedure was carried out using hexagonal barium ferrite magnetic powder with an 800e1 average particle size of about Q, 7 pm, and a platelet ratio of about 4.5.
Constructed video magnetic tape and floppy disk.

〔比較例４〕 実施例１において、Ｍｓ約５４　ｅｍｕ／ｇ、　Ｈｅ約
５８００ｅ、平均粒通約０．２５μｍ、板状比６．５の
六方晶系バリウムフェライト磁性粉を用いて同様に行い
、ビデオ用磁気テープ及びフロッピーディスクを構成し
た。[Comparative Example 4] The same procedure as in Example 1 was carried out using hexagonal barium ferrite magnetic powder having an Ms of about 54 emu/g, a He of about 5800 e, an average grain diameter of about 0.25 μm, and a plate ratio of 6.5. Constructed video magnetic tape and floppy disk.

〔比較例５〕 実施例２において、Ｍｓ約５４　ｅｍｕ／ｇ、　Ｈｅ約
５４００ｅ、平均粒通約０．５５μｍ、板状比約９の六
方晶系置換型バリウムフェライト磁性粉３重量部を用い
て同様に行い、ビデオ用磁気テープ及びフロッピーディ
スクを構成した。[Comparative Example 5] In Example 2, 3 parts by weight of hexagonal substituted barium ferrite magnetic powder having an Ms of about 54 emu/g, a He of about 5400 e, an average grain size of about 0.55 μm, and a plate ratio of about 9 was used. A video magnetic tape and a floppy disk were constructed in the same manner.

〔比較例６〕 実施例１において、Ｍｓ約５４　ｅｍｕ／ｇ、　Ｈｅ約
５８００ｅ、平均粒通約０．１μｍ、板状比約４．５の
六方晶系バリウムフェライト磁性粉を用いて同様に行い
、ビデオ用磁気テープ及びフロッピーディスクを構成し
た。[Comparative Example 6] The same procedure as in Example 1 was carried out using hexagonal barium ferrite magnetic powder having an Ms of about 54 emu/g, a He of about 5800e, an average grain size of about 0.1 μm, and a plate ratio of about 4.5. , video magnetic tape and floppy disk.

〔比較例７〕 実施例３において、Ｍｓ約５４　ｅｍｕ／ｇ％Ｈｃ約５
５００ｅ、平均粒通約０．１５μｍ、板状比約３の六方
晶系置換型バリウムフェライト磁性粉３．５重量部を用
いて同様に行い、ビデオ用磁気テープ及びフロッピーデ
ィスクを構成した。[Comparative Example 7] In Example 3, Ms about 54 emu/g% Hc about 5
The same procedure was carried out using 3.5 parts by weight of hexagonal substituted barium ferrite magnetic powder having an average particle diameter of about 0.15 μm and a platelet ratio of about 3 to construct a video magnetic tape and a floppy disk.

〔比較例８〕 実施例４において、六方晶系バリウムフェライト磁性粉
を零にして同様に行い、ビデオ用磁気テープ及びフロッ
ピーディスクを構成した。[Comparative Example 8] The same procedure as in Example 4 was repeated except that the amount of hexagonal barium ferrite magnetic powder was reduced to zero, and a video magnetic tape and a floppy disk were constructed.

〔比較例９〕 実施例２において、Ｍｓ約５４　ｅｍｕ／ｇ　、　Ｈｃ
約６５００ｅ、平均粒径的０．４０μｍ、板状比約３．
５の六方晶系置換型バリウムフェライト磁性粉４．５重
量部を用いて同様に行い、ビデオ用磁気テープ及びフロ
ッピーディスクを構成した。[Comparative Example 9] In Example 2, Ms about 54 emu/g, Hc
Approximately 6500e, average grain size 0.40μm, plate ratio approximately 3.
The same procedure was carried out using 4.5 parts by weight of the hexagonal substituted barium ferrite magnetic powder No. 5 to prepare a video magnetic tape and a floppy disk.

〔比較例Ｎｏ　） 実施例１において、Ｍｓ約５４　ｅｍｕ／ｇｓ　Ｈｃ約
７５００ｅ、平均粒径的０．２５μｍ、板状比約４．５
の六方晶系バリウムフェライト磁性粉を用いて同様に行
い、ビデオ用磁気テープ及びフロッピーディスクを構成
した。[Comparative Example No.] In Example 1, Ms about 54 emu/gs Hc about 7500e, average particle size 0.25 μm, plate ratio about 4.5
A video magnetic tape and a floppy disk were constructed in the same manner using hexagonal barium ferrite magnetic powder.

〔特性〕〔Characteristic〕

上記実施例及び比較例で作成した磁性塗料の分散時間−
最大磁束密度の関係を示すと、第１図に示す通シである
。Dispersion time of magnetic paints prepared in the above examples and comparative examples -
The relationship between the maximum magnetic flux density is shown in FIG. 1.

これによれば、本発明の磁気記録媒体の磁性層構成に用
いた磁性塗料の分散性は良好であることがわかる。つま
り、六方晶系フェライト磁性粉の含有量が針状強磁性粉
１００重景重量′対して５重量部以下のものを選ぶこと
によって、分散性が向上し、磁気特性の向上が得られて
いる。According to this, it can be seen that the dispersibility of the magnetic paint used in the magnetic layer structure of the magnetic recording medium of the present invention is good. In other words, by selecting a hexagonal ferrite magnetic powder with a content of 5 parts by weight or less based on 100 square meters of acicular ferromagnetic powder, dispersibility is improved and magnetic properties are improved. .

伺、最大磁束密度Ｂｍは、それぞれの分散時間における
磁性塗料をブレードでポリエステルフィルムに塗布して
作成したサンプルを用いて、印加磁場２ＫＯｅで測定し
たものである。The maximum magnetic flux density Bm was measured at an applied magnetic field of 2 KOe using samples prepared by applying the magnetic paint to a polyester film with a blade at each dispersion time.

又、カラーＳ／Ｎを測定すると、実施例１のものではＺ
ＯｄＢ、実施例２のものでは２．５　ｄＢであるのに対
し、比較例３のものでは−０，５ｄＢ、比較例４のもの
では−Ｑ、ｌｄＢ、比較例５のものでは−２，，３ｄＢ
といったように、板状比及び平均粒径によってカラーＳ
／Ｎは大きく左右され、六方晶系・フェライト磁性粉の
板状比が５以下で平均粒径が０．５μｍ以下の場合の良
好なことがわかる。Also, when measuring the color S/N, in Example 1, Z
OdB, 2.5 dB in Example 2, -0.5 dB in Comparative Example 3, -Q, ldB in Comparative Example 4, -2, , in Comparative Example 5. 3dB
Color S is determined by plate ratio and average particle size.
It can be seen that /N is greatly affected and is favorable when the plate ratio of the hexagonal ferrite magnetic powder is 5 or less and the average particle size is 0.5 μm or less.

伺、カラーＳ／Ｎは、日本ビクター■製のＨＲ−３３０
０で測定したものである。The color S/N is HR-330 manufactured by Victor Japan.
It was measured at 0.

又、磁気テープのスチル特性（−５℃でポーズ再生した
際におけるスチルアウトまでの時間）と磁性面側の動摩
擦係数を測定すると、実施例１のものではスチル時間が
８０分、動摩擦係数が０．２１５、実施例３のものでは
スチル時間が９０分以上、動摩擦係数が０．２０３であ
るＯＫ対し、比較例６のものではスチル時間が１５分、
動摩擦係数が０．２９８であシ、又、比較例７のもので
はメチル時間が２５分、動摩擦係数がｏ、２７ｓである
といったように、六方晶系フェライト磁性粉の平均粒径
が０．２μｍ以上である場合に耐スチル性及び動摩擦係
数に向上がみられ、走行性及び耐久性に優れていること
がわかる。In addition, when measuring the still characteristics of the magnetic tape (the time until still out during pause playback at -5°C) and the dynamic friction coefficient on the magnetic surface side, in Example 1, the still time was 80 minutes and the dynamic friction coefficient was 0. .215, OK in Example 3 with a still time of 90 minutes or more and a dynamic friction coefficient of 0.203, whereas in Comparative Example 6, the still time was 15 minutes, and the dynamic friction coefficient was 0.203.
The average particle size of the hexagonal ferrite magnetic powder is 0.2 μm, as shown in the kinetic friction coefficient of 0.298 and the methylation time of 25 minutes and the dynamic friction coefficient of 27 seconds in Comparative Example 7. It can be seen that when the above conditions are met, the still resistance and the coefficient of dynamic friction are improved, and the running performance and durability are excellent.

又、フロッピーディスクの２Ｆ出力とモジュレーション
を測定すると、実施例１のものでは２Ｆ出力が３３０ｍ
Ｖ師、モジュレーションが３１実実施例２のものでは２
Ｆ出力が３５０ｍＶｐ−ｐ、モジュレーションが３％で
あるのに対し、比較例４のものでは２Ｆ出力が２ｓｓｍ
ｖｐ−ｐ、モジｚ４ｚ−ジョンが６優、比較例８のもの
では２Ｆ出力が３００ｍＶｐ−ｐ、モジュレーションが
５％であり、このような点からも板状比が約５以下の六
方晶系フェライト磁性粉を含むものは良好なことがわか
る。Also, when measuring the 2F output and modulation of the floppy disk, the 2F output of Example 1 was 330m.
Master V, the modulation is 31 and 2 in the example 2.
The F output is 350mVp-p and the modulation is 3%, whereas in Comparative Example 4, the 2F output is 2ssm.
The hexagonal ferrite with a plate ratio of about 5 or less has a 2F output of 300 mVp-p and a modulation of 5% in Comparative Example 8. It can be seen that those containing magnetic powder are good.

又、ビデオテープの４ＭＨｚ出力特性を測定すると、第
２図に示す通りである。Furthermore, when the 4 MHz output characteristics of the videotape were measured, the results were as shown in FIG.

これによれば、六方晶系フェライト磁性粉の保磁力が約
６０００ｅ以下の場合には出力特性が良く６０００ｅを
越えると急激に出力特性の低下することがわかる。According to this, it can be seen that when the coercive force of the hexagonal ferrite magnetic powder is about 6000e or less, the output characteristics are good, and when it exceeds 6000e, the output characteristics deteriorate rapidly.

〔効果〕〔effect〕

カラーＳ／Ｎ、スチル特性、走行性、再生出力等に優れ
ている。Excellent in color S/N, still characteristics, running performance, playback output, etc.

【図面の簡単な説明】[Brief explanation of drawings]

第１図及び第２図は、磁気記録媒体の特性説明図である
。1 and 2 are explanatory diagrams of characteristics of a magnetic recording medium.

Claims (1)

【特許請求の範囲】[Claims] 飽和磁化７０ｅｍｕ／ｇ以上の磁性粉末と、ｃ軸方向に
磁化容易軸をもち、かつ保磁力が６００エルステッド以
下で、板状比が５以下で、粒子サイズが０．２〜０．５
μｍの六方晶系フェライト磁性粉末とを磁性層中に含み
、前記磁性粉末１００重量部に対して前記六方晶系フェ
ライト磁性粉末が５重量部以下の割合であることを特徴
とする磁気記録媒体。Magnetic powder with a saturation magnetization of 70 emu/g or more, an axis of easy magnetization in the c-axis direction, a coercive force of 600 Oe or less, a plate ratio of 5 or less, and a particle size of 0.2 to 0.5.
1. A magnetic recording medium, characterized in that the magnetic layer contains a hexagonal ferrite magnetic powder of μm size, and the hexagonal ferrite magnetic powder is present in a ratio of 5 parts by weight or less to 100 parts by weight of the magnetic powder.