JPS61217929A - 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, 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 <=30pts.wt. the latter with respect to 70-100pts. 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 erasing characteristic, good high-frequency characteristic, high density and high output is obtd. The ratio of the ferromagnetic powder is more preferably about 30-5wt% with respect to about 70-95wt% the hexagonal ferrite magnetic powder.

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γ−Ｆｅｔｕｓ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, as a magnetic recording medium, a magnetic paint containing acicular γ-Fetus magnetic powder is applied onto a non-magnetic substrate, and the magnetization is oriented in the in-plane longitudinal direction by an orientation treatment such as mechanical orientation or magnetic field orientation. The main type is the so-called horizontal magnetic recording method.

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 having 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. (Unexamined Japanese Patent Publication No. 58-203625
No.) has been done.

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 will lead to a decrease in magnetic properties due to poor dispersibility of the magnetic paint. It is stated that if the structure is configured as follows, the dispersibility of the magnetic coating material will be improved, and a magnetic recording medium with good magnetic properties can therefore 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以上であり、しかも保磁力が６００エル
ステツド以下のものを選び、又、強磁性粉としては針状
比が４以上であり、しかも飽和磁化が１０１００ｅ／　
ｇ以上であって保磁力が７００エルステツド以下のもの
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７０〜１００重量部
に対して後者が３０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ＦＭ出力の経時変化に
よる低下が少ない）、又、消去特性も良好であり、さら
には高周波特性も良く、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 conducting research and development of magnetic recording media, we selected hexagonal ferrite magnetic powder with a plate ratio of 5 or more and a coercive force of 600 oersted or less, and also selected ferromagnetic powder as ferromagnetic powder. has an acicular ratio of 4 or more and a saturation magnetization of 10100e/
g or more and has a coercive force of 700 oersted or less, and the ratio of the hexagonal ferrite magnetic powder having the above characteristics to the ferromagnetic powder having the above characteristics is 70 to 100 parts by weight for the former and 70 to 100 parts by weight for the latter. If the amount is 30 parts by weight or less, there will be little change in magnetic properties over time (for example, less decline in FM output due to changes over time), good erasing properties, and good high frequency properties, with high density and high output. It was discovered that a magnetic recording medium of

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
が高上し、高密度記録に対応できるものとなり、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ＦＭ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７０〜１００重量％に対して強磁性粉は
３０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７０〜９５ｉｌｉ量％に対して強磁
性粉が約３０〜５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, increasing the reproduction output in the high frequency range and increasing the density. Although the horizontal magnetization component of the acicular ferromagnetic powder can be used effectively and the reproduction output in the low frequency range is improved, the relative amount of ferromagnetic powder to the hexagonal ferrite magnetic powder is If the number of ferrite particles increases too much, the deterioration of the magnetic properties will be severe, for example, the FM output will drop significantly due to changes over time, and the reproduction output in the high frequency range will also be greatly reduced. 70-100% by weight of ferromagnetic powder, more preferably about 70-95% of hexagonal ferrite magnetic powder and about 30-5% by weight of ferromagnetic powder. It is desirable that it be a percentage.

又、前記磁気特性の点のみでなく、Ｃ／Ｎの周波数特性
の点よりも、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
。そしてこの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６００エル
ステツド以下、より一層好ましくは約４００〜６００エ
ルステツドであることが、かつ強磁性粉の飽和磁化が１
０１００ｅ／　ｇ以上であって保磁力が７００エルステ
ツド以下、より一層好ましくは約５００〜７００エルス
テツドであることが望ましいのである。Furthermore, it is desirable that the ratio of hexagonal ferrite magnetic powder and ferromagnetic powder be as described above, not only from the viewpoint of the magnetic properties but also from the viewpoint of C/N frequency characteristics. In order to improve the C/N characteristic in this high frequency region, it is important to not only adjust the ratio of the hexagonal ferrite magnetic powder to the ferromagnetic powder, but also to adjust the coercive force of the hexagonal ferrite magnetic powder to 600 oersted or less, more preferably about 400 to 600 oersted, and the saturation magnetization of the ferromagnetic powder is 1
It is desirable that the coercive force is 0.100 e/g or more and 700 Oe/g or less, more preferably about 500 to 700 Oe/g.

又、六方晶系フェライト磁性粉と強磁性粉の保磁力が上
記のようなものであることは、高周波領域におけるＣ／
Ｎの特性向上の観点からのみではなく、入出力特性、消
去特性上からも望ましいのである。Furthermore, the fact that the coercive forces of the hexagonal ferrite magnetic powder and the ferromagnetic powder are as described above means that C/
This is desirable not only from the viewpoint of improving N characteristics, but also from the viewpoint of input/output characteristics and erasing characteristics.

又、六方晶系フェライト磁性粉の板状比が５以上好まし
くは約７〜１５であり、かつ強磁性粉の針状比が４以上
好ましくは約６〜１５のものを用いることによって、機
械配向処理が容易で、周波数特性が向上する。Further, by using a hexagonal ferrite magnetic powder whose platelet ratio is 5 or more, preferably about 7 to 15, and a ferromagnetic powder whose acicular ratio is 4 or more, preferably about 6 to 15, mechanical orientation can be achieved. Easy processing and improved frequency characteristics.

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
１０．保磁力５８０エルステツド、飽和磁化５７ｅｍｕ
／ｇ１平均粒径０．１μｍ）８５重量部、金属鉄磁性粉
（針状比８、保磁力６７０エルステツド、飽和磁化１２
５ｅｍｕ／ｇ１平均粒径０．２　μｍ　）　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３０
０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、７インチ中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 10, coercive force 580 oersted, saturation magnetization 57 emu)
/g1 average particle size 0.1 μm) 85 parts by weight, metallic iron magnetic powder (acicular ratio 8, coercive force 670 oersted, saturation magnetization 12
5 emu/g1 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, 30 parts by weight of solvent.
0 parts by weight of the mixture is sufficiently cross-dispersed to make a magnetic paint, a curing agent is added to this magnetic paint, it is applied onto a non-magnetic substrate such as polyethylene terephthalate, and after drying, it is calendered and slit into 7-inch pieces. to obtain magnetic tape.

〔実施例２〕 実施例１におけるバリウムフェライト磁性粉を９５重量
部、金属鉄磁性粉を５重量部として同様に行ない、磁気
テープを得る。[Example 2] A magnetic tape was obtained in the same manner as in Example 1 except that 95 parts by weight of the barium ferrite magnetic powder and 5 parts by weight of the metal iron magnetic powder were used.

〔実施例３〕 実施例１において、ｉインチ巾にスリットして磁気テー
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。[Example 3] In Example 1, instead of making a magnetic tape by slitting it to a width of i inch, a floppy disk is obtained by punching it to a diameter of 5.25 inches.

〔比較例１〕 実施例１において、針状比３、保磁力６１０エルステツ
ド、飽和磁化１２５ｅｍｕ／ｇ、平均粒径０２μｍの金
属鉄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 metal iron magnetic powder having an acicular ratio of 3, a coercive force of 610 oersted, a saturation magnetization of 125 emu/g, and an average particle size of 02 μm.

〔比較例２〕 実施例１において、板状比４、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 2] 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 4, 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
、金属鉄磁性粉を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 by carrying out the same procedure as in Example 1 except for using 100 parts by weight of metal iron magnetic powder instead of using barium ferrite magnetic powder.

〔比較例４〕 実施例１において、バリウムフェライト磁性粉５０重量
部、金属鉄磁性粉を５０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 carried out except that 50 parts by weight of the barium ferrite magnetic powder and 50 parts by weight of the metal iron magnetic powder were used to obtain a magnetic tape.

〔比較例５〕 実施例１において、バリウムフェライト磁性粉を６０重
量部、金属鉄磁性粉を４０重量部として同様に行ない、
磁気テープを得る。[Comparative Example 5] The same procedure as in Example 1 was carried out except that the barium ferrite magnetic powder was 60 parts by weight and the metal iron magnetic powder was 40 parts by weight.
Get magnetic tape.

〔比較例６〕 実施例１　ｋ”Ｃおいて、針状比８、保磁力１５００エ
ルステツド、飽和磁化１２５　ｅｍｕ　／　ｇ　、平均
粒径０．２μｍの金属鉄磁性粉を用いて同様に行ない、
磁気テープを得る。[Comparative Example 6] Example 1 The same procedure was carried out using metallic iron magnetic powder having an acicular ratio of 8, a coercive force of 1500 oersted, a saturation magnetization of 125 emu/g, and an average particle size of 0.2 μm at k”C.
Get magnetic tape.

〔比較例７〕 実施例１において、板状比１０．保磁力９００エルステ
ツド、飽和磁化５７　ｅ　１７１　ｕ　／　ｇ　ｓ平均
粒径０．１μｍのバリウムフェライト磁性粉を用いて同
様に行すい、磁気テープを得る。[Comparative Example 7] In Example 1, the plate ratio was 10. A magnetic tape is obtained in the same manner using barium ferrite magnetic powder having a coercive force of 900 oersted, a saturation magnetization of 57 e 171 u/gs, and an average particle size of 0.1 μm.

〔比較例８〜１０　） 実施例３において、バリウムフェライト磁性粉と金属鉄
磁性粉との量が０重量部と１００重量部（比較例８）、
５０重量部と５０重量部（比較例９）、６５重量部と３
５重量部（比較例１０）として同様に行ない、フロッピ
ーディスクを得る。[Comparative Examples 8 to 10] In Example 3, the amounts of barium ferrite magnetic powder and metal iron magnetic powder were 0 parts by weight and 100 parts by weight (Comparative Example 8),
50 parts by weight and 50 parts by weight (Comparative Example 9), 65 parts by weight and 3
The same procedure was carried out using 5 parts by weight (Comparative Example 10) to obtain a floppy disk.

〔比較例１１〕 実施例３において、板状比３、保磁力５８０エルステツ
ド、飽和磁化５７ｅｍｕ／ｇｓ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、フロッ
ピーディスクを得る。[Comparative Example 11] A floppy disk was obtained by carrying out the same procedure as in Example 3 using barium ferrite magnetic powder having a plate ratio of 3, a coercive force of 580 oersted, a saturation magnetization of 57 emu/gs, and an average particle size of 0.1 μm.

〔比較例１２〕 実施例３において、針状比３、保磁力６７０エルステツ
ド、飽和磁化１２５ｅｍｕ／ｇ、平均粒径０．２μｍの
金属鉄磁性粉を用いて同様に行ない、フロッピ・−一′
ディスクを得る。[Comparative Example 12] The same procedure as in Example 3 was carried out using metal iron magnetic powder having an acicular ratio of 3, a coercive force of 670 oersted, a saturation magnetization of 125 emu/g, and an average particle size of 0.2 μm.
Get the disc.

〔特性〕〔Characteristic〕

上記実施例１及び比較例３，４．５の磁気テープについ
て、この磁気テープを温度４０℃、湿度８０９６ＲＨ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ＦＭ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 Example 1 and Comparative Examples 3 and 4.5 above, the magnetic tapes were placed in an atmosphere with a temperature of 40°C and a humidity of 8096RH, and how the FM output of the magnetic tapes changed over time. The results of the investigation are shown in Figure 1.

これによれば、本実施例のものはＦＭ出力の低下が少な
いのに対し、比較例のものは短時間のうちにＦＭ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 FM output of the example has a small decrease, whereas the FM output of the comparative example has sharply decreased in a short period of time, and the magnetic recording medium of the present invention has magnetic characteristics. It can be seen that there is little deterioration in , and the durability is high.

又、実施例３及び比較例８，９，１０，１１．１２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に結果を第２図に示す。Further, for the floppy disks of Example 3 and Comparative Examples 8, 9, 10, 11, and 12, an FM signal was input and the frequency characteristics of the reproduced output were investigated, and the results are shown in FIG.

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
おいての再生出力が低く、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 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及び比較例１，２．３の磁気テープシ
ζ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 tape sheets ζ of Examples 1 and 2 and Comparative Examples 1 and 2.3.

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は高いのに対し、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１，２及び比較例６，７の磁気テープに対し
て、５ＭＨｚのＦＭ信号を記録してその入出力特性を調
べた結果を第４図に示す。Further, FIG. 4 shows the results of recording 5 MHz FM signals on the magnetic tapes of Examples 1 and 2 and Comparative Examples 6 and 7 and examining their input/output characteristics.

これによれば、本実施例の磁気テープはその入出力特性
が良好なるものの、比較例の磁気テープは入出力特性が
悪いものであることがわかる。According to this, it can be seen that the magnetic tape of the present example has good input/output characteristics, but the magnetic tape of the comparative example has poor input/output characteristics.

〔効果〕〔effect〕

高周波領域においてのＣ／Ｎ、出力、入出力特性の良い
ものであり、又、磁気特性の劣下の少ない耐久性にζ富
むものである。It has good C/N, output, and input/output characteristics in the high frequency region, and is highly durable 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】 第１図〜第４図は、磁気記録媒体の特性を示すグラフで
ある。 １１絽　等存綺閤（＋）BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 are graphs showing the characteristics of magnetic recording media. 11 絽 To exist kikon (+)

Claims (1)

【特許請求の範囲】[Claims] 板状比が５以上、保磁力が６００エルステツド以下の六
方晶系フエライト磁性粉と、針状比が４以上、飽和磁化
が１００ｅｍｕ／ｇ以上、保磁力が７００エルステツド
以下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７０〜１００重量部に対し前記強磁性粉が
３０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 more and a coercive force of 600 Oe or less, and a ferromagnetic powder with an acicular ratio of 4 or more, a saturation magnetization of 100 emu/g or more, and a coercive force of 700 Oe or less are magnetic. A magnetic recording medium, wherein the ferromagnetic powder is contained in a layer in an amount of 30 parts by weight or less relative to 70 to 100 parts by weight of the hexagonal ferrite magnetic powder.