JPS61217927A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having good vertical orientability with good productivity by making combination use of hexagonal ferrite magnetic powder and acicular ferromagnetic powder. CONSTITUTION:The hexagonal ferrite magnetic powder having <=5 plate ratio and >=600 oersted coercive force is selected. The ferromagnetic powder having <=4 acicular ratio, 60-100emu/g saturation magnetization and >=700 oersted coercive force is selected. The ratio of the hexagonal ferrite magnetic powder and the ferromagnetic powder is made <=80pts.wt. the latter with respect to 20-100pts.wt. the former, then the magnetic recording medium of which the magnetic characteristics are less deteriorated with time (for example, the reproduced output is less decreased with time) and which has a good high-frequency characteristic, high density and high output is obtd. The ratio of the ferromagnetic powder is more preferably about 80-5wt% with respect to about 20-90wt% the hexagonal ferrite magnetic powder. The average grain sizes of both the hexagonal ferrite magnetic powder and ferromagnetic powder are about <=0.3mum.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、例えばオーディオ用、ビデオ用又はコンピュ
ータ用等の磁気テープ、フロッピーディスク又はハード
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, a floppy disk, or a hard disk for use in audio, video, or computers.

〔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ｒ　Ｆｅｚｅｓ磁性
粉を含む磁性塗料を非磁性基体上に塗布し、それを機械
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 Fezes magnetic powder on a non-magnetic substrate, and then applying an orientation treatment such as mechanical orientation or magnetic field orientation to orient the magnetization in the in-plane longitudinal direction. 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、高密度記録には適し
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, so it is not suitable for high-density recording.

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り、
例えば強磁性粉末と六方晶系フェライト磁性粉、特に平
均粒径０．２μｍ以下の六方晶系フェライト粉末５〜１
００重量部と、飽和磁化７０ｅｍｕ／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１００重量部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 5 to 1
A magnetic recording medium is proposed in which 100 parts by weight of a ferromagnetic powder with a saturation magnetization of 70 emu/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.

〔発明の開示〕[Disclosure of the invention]

本発明者は、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ような六方晶系フェライト磁性粉と
強磁性粉とを併用混入した磁気記録媒体の研究開発を進
めているうちに、六方晶系フェライト磁性粉としてはそ
の板状比が５以下であり、しかも保磁力が６００エルス
テツド以上のものを選び、又、強磁性粉としては針状比
が４以下であり、しかも飽和磁化が６０〜１０１００ｅ
／ｇであって保磁力が７００エルステツド以上のものを
選び、又、前記特性の六方晶系フェライト磁性粉と前記
特性の強磁性粉との割合を前者が２０〜１００重量部に
対して後者が８０重量部以下としておくならば、磁気特
性の経時変化が少なく（例えば再生出力の経時変化によ
る低下が少ない）、又高周波特性も良く、高密度で高出
力の磁気記録媒体が得られることを見い出した。The present inventor has discovered that a combination of hexagonal ferrite magnetic powder and ferromagnetic 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 mixed. While researching and developing magnetic recording media, we selected a hexagonal ferrite magnetic powder with a platelet ratio of 5 or less and a coercive force of 600 oersted or more. The acicular ratio is 4 or less, and the saturation magnetization is 60 to 10100e.
/g and has a coercive force of 700 oersted or more, and the ratio of the hexagonal ferrite magnetic powder having the above characteristics to the ferromagnetic powder having the above characteristics is 20 to 100 parts by weight for the former and 20 to 100 parts by weight for the latter. It has been found that if the amount is 80 parts by weight or less, there is little change in magnetic properties over time (for example, there is little decline in playback output due to change over time), and high frequency properties are also good, resulting in a high-density, high-output magnetic recording medium. Ta.

つまり、六方晶系フェライト磁性粉と針状強磁性粉とを
併用することによって、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９、又、針
状の強磁性粉の水平磁化成分が有効に利用できて低周波
領域での再生出力が向上するものの、強磁性粉の六方晶
系フェライト磁性粉に対する相対量が多くなりすぎると
、経時変化によって例えば再生出力が著しく低下してし
まうといったように磁気特性の劣下が酷く、又、高周波
領域での再生出力の低下が大きく、従って六方晶系フェ
ライト磁性粉が２０〜１００重量％に対して強磁性粉は
８０重量％以下の割合、より一層好ましくは六方晶系フ
ェライト磁性粉が約２０〜９５重量％に対して強磁性粉
が約８０〜５重量％の割合であることが望ましいのであ
る。In other words, by using hexagonal ferrite magnetic powder and acicular ferromagnetic powder together, the perpendicular magnetization component of hexagonal ferrite magnetic powder can be effectively used, improving reproduction output in the high frequency range and achieving high-density recording. 9.Also, although the horizontal magnetization component of the acicular ferromagnetic powder can be effectively used and the reproduction output in the low frequency range is improved, the relative strength of the ferromagnetic powder to the hexagonal ferrite magnetic powder If the amount is too large, the deterioration of the magnetic properties will be severe, for example, the reproduction output will drop significantly due to changes over time, and the reproduction output will also decrease significantly in the high frequency range, so the hexagonal ferrite magnetic powder is 20 to 100% by weight, and the ferromagnetic powder is 80% by weight or less, more preferably, the hexagonal ferrite magnetic powder is about 20 to 95% by weight, and the ferromagnetic powder is about 80 to 5% by weight. It is desirable that the ratio be as follows.

又、再生出力の特性の点より六方晶系フェライト磁性粉
と強磁性粉との割合は上記のようなものであることが望
ましいのであるが、高周波領域におけるＣ／Ｎの特性向
上には、六方晶系フェライト磁性粉と強磁性粉との割合
のみでなく、六方晶系フェライト磁性粉の保磁力が６０
０エルステツド以上、より一層好ましくは約７００〜１
５００エルステツドであることが、かつ強磁性粉の飽和
磁化が６０〜ＬＯＯｅｍｕ／　ｇであって保磁力が７０
０エルステツド以上、より一層好ましくは約７００〜１
５００エルステツドであることが望ましいのである。In addition, from the viewpoint of reproduction output characteristics, it is desirable that the ratio of hexagonal ferrite magnetic powder and ferromagnetic powder be as described above. Not only the ratio of crystalline ferrite magnetic powder and ferromagnetic powder, but also the coercive force of hexagonal ferrite magnetic powder is 60
0 oersted or more, even more preferably about 700 to 1
500 oersted, and the saturation magnetization of the ferromagnetic powder is 60 to LOOemu/g, and the coercive force is 70
0 oersted or more, even more preferably about 700 to 1
A value of 500 oersted is desirable.

又、六方晶系フェライト磁性粉の板状比が５以下好まし
くは約１〜５であり、かつ強磁性粉の針状比が４以下好
ましくは約１〜４のものを用いることによって、ランダ
ム配向が得られるものとなり、高周波領域においての高
出力化が図れるものとなる。Furthermore, by using a hexagonal ferrite magnetic powder whose platelet ratio is 5 or less, preferably about 1 to 5, and a ferromagnetic powder whose acicular ratio is 4 or less, preferably about 1 to 4, random orientation can be achieved. This makes it possible to achieve high output in the high frequency region.

又、上記で用いる六方晶系フェライト磁性粉及び強磁性
粉は、ともにその平均粒径が約０．３μｍ以下のもので
あることが望ましい。Further, it is desirable that both the hexagonal ferrite magnetic powder and the ferromagnetic powder used above have an average particle size of about 0.3 μm or less.

〔実施例１〕 Ｃ軸が磁化容易軸のバリウムフェライト磁性粉（板状比
３、保磁カフ５０エルステツド、飽和磁化５７　ｅｍｕ
　／　ｇ　１平均粒径０．１　ｔｔｍ　）　８５重量部
、Ｃｏ被着型γ−Ｆｅｔｕｓ磁性粉（針状比３、保磁力
８８０エルステツド、飽和磁化７４ｅｍｕ／ｇｓ平均粒
径０．２μｍ）１５重量部、結合剤２５重量部、分散剤
１重量部、研磨剤４重量部、カーボンブラック５重量部
、滑剤１重量部、溶剤３００重量部の混合物を充分に混
線分散して磁性塗料を作り、この磁性塗料に硬化剤を加
えてからポリエチレンテレフタレートといった非磁性基
体上に塗布し、乾燥後カレンダー処理し、ｉインチ巾に
スリットして磁気テープを得る。[Example 1] Barium ferrite magnetic powder whose C axis is the axis of easy magnetization (plate ratio 3, coercive cuff 50 oersted, saturation magnetization 57 emu)
/ g 1 average particle size 0.1 ttm) 85 parts by weight, Co-coated γ-Fetus magnetic powder (acicular ratio 3, coercive force 880 oersted, saturation magnetization 74 emu/gs average particle size 0.2 μm) 15 parts by weight , 25 parts by weight of binder, 1 part by weight of dispersant, 4 parts by weight of abrasive, 5 parts by weight of carbon black, 1 part by weight of lubricant, and 300 parts by weight of solvent were sufficiently cross-dispersed to prepare a magnetic paint. After adding a curing agent to the paint, it is applied onto a non-magnetic substrate such as polyethylene terephthalate, dried, calendered, and slit into i inch width to obtain a magnetic tape.

〔実施例２〜４〕 実施例１において、バリウムフェライト磁性粉を３０重
量部、かつＣｏ被着型γ−Ｆｅ＊Ｏｓ磁性粉を７０重量
部として（実施例２）、バリウムフェライト磁性粉を５
０重量部、かつＣｏ被着型γ−ＦｅｒＯ＊　磁性粉を５
０重量部として（実施例３）、バリウムフェライト磁性
粉を７０重量部、かつＣＯ被着型γ−Ｆｅ宜Ｏｓ磁性粉
を３０重量部として（実施例４）同様に行ない、磁気テ
ープを得る。[Examples 2 to 4] In Example 1, the barium ferrite magnetic powder was 30 parts by weight and the Co-coated γ-Fe*Os magnetic powder was 70 parts by weight (Example 2), and the barium ferrite magnetic powder was 5 parts by weight.
0 parts by weight, and 5 parts of Co-coated γ-FerO* magnetic powder.
A magnetic tape is obtained in the same manner as in Example 4, using 0 parts by weight (Example 3), 70 parts by weight of barium ferrite magnetic powder, and 30 parts by weight of CO-coated γ-Fe-Os magnetic powder.

〔実施例５〜８〕 実施例１〜４において、磁気テープとする代りに５．２
５インチの径で打ち抜いてフロッピーディスクを得る。[Examples 5 to 8] In Examples 1 to 4, instead of using magnetic tape, 5.2
Punch out a 5-inch diameter to obtain a floppy disk.

〔実施例９〕 実施例３において、ＣＯ被着型ｒ−ＦｅｔＯｚの代怜に
針状比３、保磁力８８０エルステツド、飽和磁化８５ｅ
ｍｕ／ｇ、平均粒径０．２μｍの金属磁性粉を用いて行
ない、フロッピーディスクを得る。[Example 9] In Example 3, the CO-coated r-FetOz had an acicular ratio of 3, a coercive force of 880 oersted, and a saturation magnetization of 85e.
A floppy disk is obtained by using metal magnetic powder of mu/g and average particle size of 0.2 μm.

〔比較例１〕 実施例１において、板状比３、保磁力５８０エルステツ
ド、飽和磁化５７ｅｍｕ／ｇ、平均粒径０．１μｍのバ
リウムフェライト磁性粉を用いて同様に行ない、磁気テ
ープを得る。[Comparative Example 1] A magnetic tape is obtained by carrying out the same procedure as in Example 1 using barium ferrite magnetic powder having a plate ratio of 3, a coercive force of 580 oersted, a saturation magnetization of 57 emu/g, and an average particle size of 0.1 μm.

〔比較例２〕 実施例１において、針状比３、保磁力６５０エルステツ
ド、飽和磁化７４　ｅｍｕ　／　ｇ　、平均粒径０．２
μｍのＣｏ被着型γ−Ｆｅ＊Ｏ＊磁性粉を用いて同様に
行ない、磁気テープを得る。[Comparative Example 2] In Example 1, the acicular ratio was 3, the coercive force was 650 oersted, the saturation magnetization was 74 emu/g, and the average grain size was 0.2.
A magnetic tape is obtained in the same manner using .mu.m Co-coated .gamma.-Fe*O* magnetic powder.

〔比較例３〕 実施例１において、バリウムフェライト磁性粉を用いず
、ＣＯ被着型γ−Ｆｅ１ｒｓ磁性粉を１００重量部とし
て同様に行ない、磁気テープを得る。[Comparative Example 3] A magnetic tape is obtained in the same manner as in Example 1 except that the barium ferrite magnetic powder is not used and the CO-coated γ-Fe1rs magnetic powder is used in an amount of 100 parts by weight.

〔比較例４〕 実施例１において、バリウムフェライト磁性粉１５重量
部、ＣＯ被着型γ−Ｆｅ鵞Ｏｎ磁性粉を８５重量部とし
て同様に行ない、磁気テープを得る。[Comparative Example 4] The same procedure as in Example 1 was repeated except that 15 parts by weight of the barium ferrite magnetic powder and 85 parts by weight of the CO-coated γ-Fe On magnetic powder were used to obtain a magnetic tape.

〔比較例５〕 比較例３において、磁気テープとする代りに５．２５イ
ンチの径で打ち抜いてフロッピーディスクを得る。[Comparative Example 5] In Comparative Example 3, instead of making a magnetic tape, a floppy disk was punched out with a diameter of 5.25 inches.

〔比較例６〕 比較例４において、磁気テープとする代りに５．２５イ
ンチの径で打ち抜いてフロッピーディスクを得る。[Comparative Example 6] In Comparative Example 4, instead of making a magnetic tape, a floppy disk was punched out with a diameter of 5.25 inches.

〔比較例７〕 実施例３において、板状比１０．保磁カフ５０エルステ
ツド、畿和磁化５７ｅｍｕ／ｇ、平均粒径０．１μｍの
バリウムフェライト磁性粉を用いてフロッピーディスク
を得る。[Comparative Example 7] In Example 3, the plate ratio was 10. A floppy disk was obtained using barium ferrite magnetic powder with a coercive cuff of 50 oersted, Kiwa magnetization of 57 emu/g, and average particle size of 0.1 μm.

〔比較例８〕 実施例３において、針状比１２、保磁力８８０エルステ
ツド、飽和磁化７４ｅｍｕ／ｇ、平均粒径０．２μｍの
Ｃｏ被着型γ−Ｆｅａｒｓ磁性粉を用いてフロッピーデ
ィスクを得る。[Comparative Example 8] In Example 3, a floppy disk is obtained using Co-coated γ-Fears magnetic powder having an acicular ratio of 12, a coercive force of 880 oersted, a saturation magnetization of 74 emu/g, and an average particle size of 0.2 μm.

〔特性〕〔Characteristic〕

上記実施例２，３．４及び比較例３，４の磁気テープに
ついて、この磁気テープを温度４０℃、湿度８０％ＲＨ
の雰囲気下に置き、そしてこの経時変化によって磁気テ
ープの再生出力がどのように変化するかを調べた結果を
第１図に示す。Regarding the magnetic tapes of Examples 2 and 3.4 and Comparative Examples 3 and 4, the magnetic tapes were heated at a temperature of 40°C and a humidity of 80% RH.
Figure 1 shows the results of examining how the reproduction output of a magnetic tape changes over time.

これによれば、本実施例のものは再生出力の低下が少な
いのに対し、比較例のものは再生出力が急激に低下して
おり、本発明の磁気記録媒体は磁気特性の低下が少なく
、耐久性に富むことがわかる。According to this, the reproduction output of the example has a small decrease, whereas the reproduction output of the comparative example has sharply decreased, and the magnetic recording medium of the present invention has a small decrease in magnetic properties. It can be seen that it is highly durable.

又、実施例７．９及び比較例７，８のフロッピーディス
クについて、ＦＭ信号を入力して再生出力の周波数特性
を調べた結果を第２図に示す。FIG. 2 shows the results of examining the frequency characteristics of the reproduction outputs of the floppy disks of Examples 7 and 9 and Comparative Examples 7 and 8 by inputting FM signals.

これによれば、本実施例のものは高周波領域においての
再生出力が高いのに対し、比較例のものは高周波領域に
おいての再生出力は低く、本発明の磁気記録媒体は高密
度記録に適したものであることがわかる。According to this, the magnetic recording medium of the present invention has a high reproduction output in the high frequency region, whereas the reproduction output of the comparative example has a low reproduction output in the high frequency region, and the magnetic recording medium of the present invention is suitable for high-density recording. I can see that it is something.

又、実施例１，２．４及び比較例１．２の磁気テープに
ついて、Ｃ／Ｎの周波数特性を調べた結果を第３図に示
す。FIG. 3 shows the results of examining the C/N frequency characteristics of the magnetic tapes of Examples 1 and 2.4 and Comparative Example 1.2.

これによれば、本実施例のものは高周波領域においての
Ｃ／Ｎが高いのに対し、比較例のものは高周波領域にお
いてのＣ／Ｎは低く、本発明の磁気記録媒体は高密度記
録に適したものであることがわかる。According to this, the C/N of the present example is high in the high frequency region, whereas the C/N of the comparative example is low in the high frequency region, and the magnetic recording medium of the present invention is suitable for high-density recording. It turns out that it is suitable.

又、実施例５〜８及び比較例５，６のフロッピーディス
クについてモジューレーションを調べると、実施例５の
ものでは１．３％、実施例６のものでは１．５％、実施
例７のものでは２．０９６、実施例８のものでは２，１
％とそのモジューレーションハ小すく高性能なフロッピ
ーディスクであることを示しているのに対し、比較例５
のものでは４．０　％　、比較例６のものでは１０．３
％とそのモジューレーショは大きく、その性能が劣って
いる。Further, when examining the modulation of the floppy disks of Examples 5 to 8 and Comparative Examples 5 and 6, it was found that the modulation of the floppy disks of Example 5 was 1.3%, that of Example 6 was 1.5%, and that of Example 7 was 1.3%. 2.096 in Example 8, 2.1 in Example 8
% and its modulation indicate that it is a small and high-performance floppy disk, whereas Comparative Example 5
4.0% in the case of Comparative Example 6, 10.3% in the case of Comparative Example 6.
% and its modulation is large and its performance is inferior.

〔効果〕〔effect〕

高周波領域においての特性の良いものであり、又、磁気
特性の劣下の少ない耐久性の良いものである。It has good characteristics in the high frequency range, and has good durability with little deterioration in magnetic properties.

又、磁場配向処理を特別に行なわなくても垂直配向性の
良い磁気記録媒体が得られ、生産性良く作れる。Further, a magnetic recording medium with good vertical alignment can be obtained without special magnetic field alignment treatment, and can be manufactured with high productivity.

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

第１図〜第３図は、磁気記録媒体の特性を示すグラフで
ある。 蒋締ｎζＨ） オ　１！２’１ ブ　２　局1 to 3 are graphs showing the characteristics of magnetic recording media. Jiang Shui nζH) O 1!2'1 Bu 2 station

Claims (1)

【特許請求の範囲】[Claims] 板状比が５以下、保磁力が６００エルステツド以上の六
方晶系フエライト磁性粉と、針状比が４以下、飽和磁化
が６０〜１００ｅｍｕ／ｇ、保磁力が７００エルステツ
ド以上の強磁性粉とを磁性層中に含み、前記六方晶系フ
エライト磁性粉２０〜１００重量部に対し前記強磁性粉
が８０重量部以下であることを特徴とする磁気記録媒体
。A hexagonal ferrite magnetic powder with a plate ratio of 5 or less and a coercive force of 600 Oe or more, and a ferromagnetic powder with an acicular ratio of 4 or less, a saturation magnetization of 60 to 100 emu/g, and a coercive force of 700 Oe or more. A magnetic recording medium, wherein the ferromagnetic powder is contained in a magnetic layer in an amount of 80 parts by weight or less relative to 20 to 100 parts by weight of the hexagonal ferrite magnetic powder.