JPS60219629A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the dispersibility of magnetic powder in a magnetic paint without kneading for a long period and to improve the magnetic characteristic thereof by using a copolymer derived from methacrylate and maleic anhydride as at least part of a binder resin. CONSTITUTION:The copolymer derived from the methacrylate (CH2=C(CH3) COOR, R is an alkyl group of 1-8C) and maleic anhydride has about 1,000- 10,000mol.wt. and is used together with the binder resin of an arcylic resin base consisting essentially of an epoxy resin. The compsn. consisting of about 50- 120pts.wt. the entire binder by 100pts.wt. the magnetic powder is kneaded for 24hr by a ball mill to prepare the magnetic paint. Said magnetic paint is coated on an aluminum alloy substrate and is cured by baking and thereafter the surface thereof is subjected to a polishing treatment, by which a magnetic disk is obtd. The dispersibility is thus improved, the decrease in the coercive force and squareness ratio owing to the damage of the magnetic powder is prevented and the wear resistance is semipermanently improved.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、例えば研気テープ、フロッピーディスク、ハ
ードディスクといった磁気記録媒体、特にコンピュータ
等の磁気ディスク装置に用いられる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 magnetic recording media such as sharpening tapes, floppy disks, and hard disks, and particularly to magnetic recording media used in magnetic disk devices such as computers.

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

従来、例えば磁気ディスク装置等の情報記録装置に用い
られる磁気記録媒体は、磁性粉を、例えばエポキシ樹脂
、フェノール樹脂、メラミン樹脂、尿素樹脂、アクリル
樹脂、ブチラール樹脂等のバインダーを含む溶剤に分散
させた磁性塗料を、非磁性基板上に塗布し、そして焼付
硬化することによって構成されている。Conventionally, magnetic recording media used in information recording devices such as magnetic disk devices have been produced by dispersing magnetic powder in a solvent containing a binder such as epoxy resin, phenol resin, melamine resin, urea resin, acrylic resin, or butyral resin. It is constructed by applying a magnetic paint on a non-magnetic substrate and curing it by baking.

そして、情報記録装置の高性能化に伴ない、上記の磁気
記録媒体には高密度化が要求されてきており、このよう
な要求を満たす為に、磁気記録層をよシ薄くすること、
その表面性を向上させること、磁気記録層中の磁性粉末
を均一に分散させておくこと、高保磁力の磁性粉末、例
えばＣｏ改改良型−Ｆｅｔ　Ｏ３磁性粉末、Ｃｒ、０３
磁性粉末、金属磁性粉末等を用いること等が提案されて
いる。As the performance of information recording devices increases, the above-mentioned magnetic recording media are required to have higher density, and in order to meet such demands, the magnetic recording layer must be made thinner.
To improve the surface properties of the magnetic recording layer, to uniformly disperse the magnetic powder in the magnetic recording layer, to use magnetic powder with high coercive force, such as Co modified improved type-Fet O3 magnetic powder, Cr, 03
It has been proposed to use magnetic powder, metal magnetic powder, etc.

ところが、例えば磁気記録層を単に薄くするのンダー効
果が乏しくなり、耐久性が大きな問題となる。However, simply making the magnetic recording layer thinner, for example, reduces the undertone effect and poses a major problem in durability.

又、高保磁力の磁性粉末は、一般に粒子が小さく、しか
も針状比が大きいことより、比表面積が大きく、この為
従来のγ−Ｆｅ、０３磁性粉末に比べると分散しにくい
ものとなっている。そこで、磁性粉末の分散性を向上さ
せる為、磁性塗料を長時間混合分散する必要があるが、
このような長時間の混合分数が行なわれると、磁性粉末
が折損し、保磁力の低下といった磁気特性が低下する問
題がある。In addition, magnetic powder with high coercive force generally has small particles and a high acicular ratio, so it has a large specific surface area, which makes it difficult to disperse compared to conventional γ-Fe, 03 magnetic powder. . Therefore, in order to improve the dispersibility of magnetic powder, it is necessary to mix and disperse magnetic paint for a long time.
If such a long mixing period is carried out, there is a problem in that the magnetic powder is broken and the magnetic properties are deteriorated, such as a decrease in coercive force.

〔発明の開示〕[Disclosure of the invention]

本発明者は、磁性粉末をバインダー樹脂中に分数せしめ
て焼料硬化してなるタイプの磁気記録媒体において、バ
インダー樹脂の少なくとも一部としてメタクリル酸エス
テルと無水マレイン酸とより導かれる共重合体を用いて
いると、長時間の混練をせずとも磁性塗料中における磁
性粉末の分散性が良く、従って磁気特性を低下せしめる
こともなく、又、磁気記録層を薄くしても機械的強度に
優れていることを見い出した。　□ この分散性向上は、磁性粉末の折損による保磁力や角型
比の低下を防ぐといった効果をもた。らすのみではなく
、磁性塗料の混線時間の大巾な短縮が可能となり、例え
ば従来の磁気記録媒体の表面特性と同等の表面特性のも
のでよいとすれば混線時間は従来の半分以下ですみ、従
って製造時間の大巾な短縮化及び製造コストの大巾な低
廉化が行なえ、又、磁性粉末の折損が起きない程度まで
比較的長く磁性塗料の混線を行なえば保磁力等の低下も
なく表面特性は著しく向上することになる。The present inventor has proposed a type of magnetic recording medium in which magnetic powder is fractionally incorporated into a binder resin and hardened by firing, in which a copolymer derived from a methacrylic acid ester and maleic anhydride is used as at least a part of the binder resin. When using magnetic powder, the dispersibility of the magnetic powder in the magnetic paint is good even without long-time kneading, so the magnetic properties are not deteriorated, and the magnetic recording layer has excellent mechanical strength even if it is made thin. I found out that □ This improved dispersibility has the effect of preventing a decrease in coercive force and squareness ratio due to breakage of the magnetic powder. It is possible to significantly shorten the crosstalk time of not only magnetic paint but also magnetic paint. For example, if the surface characteristics are equivalent to those of conventional magnetic recording media, the crosstalk time can be reduced to less than half of the conventional magnetic recording medium. Therefore, the manufacturing time can be greatly shortened and the manufacturing cost can be greatly reduced, and if the magnetic paint is mixed for a relatively long time to the extent that the magnetic powder does not break, there is no decrease in coercive force etc. The surface properties will be significantly improved.

又、上記機械的強度の優秀性は、磁気記録層の密着性、
耐摩耗性及び耐溶剤性等に優れていることであり、耐摩
耗性は、例えば磁気ディスクの場合にはコンタクトスタ
ートアンドストップ（Ｃ８Ｓ）の回数で評価され、ＩＳ
ＯのＴＣ９７／５Ｃ１ＯＮ２２８で１００００回以上と
いった規格があるが、本発明による磁気ディスクはこの
規格値を大きく上まり、又、磁性粉末の粉落ちといった
ことも極めて少なく、さらには磁気ディスクの表面洗浄
に使用されるアルコール等の溶剤に対する抵抗性が強く
、磁気記録層が変性を受けに＜＜、極めて耐久性に富む
ことになる。Moreover, the above-mentioned superiority of mechanical strength is due to the adhesion of the magnetic recording layer,
It has excellent abrasion resistance and solvent resistance. For example, in the case of magnetic disks, abrasion resistance is evaluated by the number of contact start and stop (C8S), and IS
There is a standard for TC97/5C1ON228 of 0.0 to be used over 10,000 times, but the magnetic disk according to the present invention greatly exceeds this standard value, has very little magnetic powder falling off, and is even more effective in cleaning the surface of the magnetic disk. It has strong resistance to the solvents used, such as alcohol, and the magnetic recording layer is extremely durable against denaturation.

尚、上記メタクリル酸エステルと無水マレイン酸とより
導かれる共重合体は、その分子量が５００〜５ｏｏｏｏ
の範囲内、より望ましくは約１０００〜１ｏｏｏ。The copolymer derived from the above methacrylic acid ester and maleic anhydride has a molecular weight of 500 to 5oooo.
within the range of , more preferably about 1000 to 1ooo.

の範囲内のものであることが相溶性等の面から好ましい
。It is preferable from the viewpoint of compatibility etc. that it is within the range of .

又、上記共重合体における無水マレイン酸の割合は、モ
ル比率で約５〜８０％、よシ望ましくは約２０〜５０％
のものであることが磁性粉末に対する分散性等の面から
好ましい。Further, the proportion of maleic anhydride in the above copolymer is about 5 to 80% in molar ratio, preferably about 20 to 50%.
It is preferable from the viewpoint of dispersibility in the magnetic powder.

又、上記メタクリル酸エステルと無水マレイン酸とより
導かれる共重合体のみをバインダー樹脂として用いるよ
りも、この共重合体と、例えばエポキシ樹脂、フェノー
ル樹脂、メラミン樹脂、尿素樹脂、アクリル樹脂、ブチ
ラール樹脂、その他のバインダー効果を有する樹脂とを
併用して用いることが好ましく、すなわち磁性塗料を調
整する際添加する全バインダー樹脂のうちメタクリル酸
エステルと無水マレイン酸とより導かれる共重合体の割
合は約１〜５０重量−の範囲内のものとすることが表面
特性等の面から好ましい。Moreover, rather than using only the copolymer derived from the above-mentioned methacrylic acid ester and maleic anhydride as the binder resin, this copolymer and, for example, epoxy resin, phenol resin, melamine resin, urea resin, acrylic resin, butyral resin, etc. It is preferable to use the copolymer derived from methacrylic acid ester and maleic anhydride in the total binder resin added when preparing the magnetic paint. It is preferable to have a weight in the range of 1 to 50% by weight from the viewpoint of surface properties and the like.

特に、メタクリル酸エステルと無水マレイン、酸とより
導かれる共重合体を、エポキシ樹脂、よシ望ましくはエ
ポキシ樹脂とアクリル樹脂系、エポキシ樹脂とフェノー
ル樹脂系又はエポキシ樹脂とアクリル樹脂とフェノール
樹脂系（いずれもエポキシ樹脂が主体）のバインダー樹
脂と共に用いることが好ましい。In particular, a copolymer derived from a methacrylic acid ester, maleic anhydride, or acid may be used in an epoxy resin, preferably an epoxy resin and an acrylic resin system, an epoxy resin and a phenolic resin system, or an epoxy resin, an acrylic resin, and a phenolic resin system ( It is preferable to use them together with a binder resin (mainly epoxy resin).

又、メタクリル酸エステルと無水マレイン酸とより導か
れる共重合体等の全バインダーは、磁性粉末１００重量
部に対して約３０〜２００重量部、より望ましくは約５
０〜１２０重量部の範囲内であるとと　′が好ましい。Further, the total amount of the binder such as a copolymer derived from methacrylic acid ester and maleic anhydride is about 30 to 200 parts by weight, more preferably about 5 parts by weight, based on 100 parts by weight of the magnetic powder.
It is preferably in the range of 0 to 120 parts by weight.

又、無水マレイン酸との共重合に用いられるメタクリル
酸エステルＣＨ，，＝Ｃ（ＣＨ，）　Ｃ０ＯＲは、Ｒが
炭素数１〜１８、より望ましくは炭素数が１〜８のアル
キル基のものであることが好ましい。そして、無水マレ
イン酸との共重合に用いられるメタクリル酸エステルは
、一種類のものだけでなく、同時に二種類以上のメタク
リル酸エステルが用いられてもよい。In addition, in the methacrylic acid ester CH,,=C(CH,)COOR used for copolymerization with maleic anhydride, R is an alkyl group having 1 to 18 carbon atoms, more preferably 1 to 8 carbon atoms. It is preferable that there be. The methacrylic ester used in the copolymerization with maleic anhydride is not limited to one type, but two or more types of methacrylic ester may be used at the same time.

〔実施例１〕 ＣＯ被着型ｙ　−１ｉ’ｅ　２０ｇ磁性粉末１００重量
部、α−Ａｔ！　０３粉末１０重量部、エポキシ樹脂（
シェル化学社の一エピコート１００７）４５重量部、フ
ェノール樹脂（住友ベークライト社のスミラックＰＣ−
２５）２０重置部、メタクリル酸エステル−無水マレイ
ン酸共重合体（交互共重合体、メタクリル酸エステルは
メタクリル酸ブチル、メタクリル酸ブチル／無水マレイ
ン酸−５０１５０、牙ｗ＝５０００）１０重量部、混合
溶剤６２０重量部の組成物をボールミルに入れ、２４時
間混線を行なって磁性塗料を調整する。[Example 1] CO coated type y-1i'e 20g magnetic powder 100 parts by weight, α-At! 03 powder 10 parts by weight, epoxy resin (
45 parts by weight of Epikote 1007 (manufactured by Shell Chemical Co., Ltd.), phenolic resin (Sumilac PC-manufactured by Sumitomo Bakelite Co., Ltd.)
25) 20 overlapping parts, 10 parts by weight of methacrylic acid ester-maleic anhydride copolymer (alternating copolymer, methacrylic acid ester is butyl methacrylate, butyl methacrylate/maleic anhydride-50150, fang w = 5000), A composition containing 620 parts by weight of a mixed solvent was placed in a ball mill and mixed for 24 hours to prepare a magnetic coating material.

そして、上記磁性塗料をアルミニウム合金基板上に塗布
し、２００℃で１時間の焼付硬化を行ない、その後研磨
処理を施して磁気ディスクを製作する。Then, the magnetic paint is applied onto an aluminum alloy substrate, baked and hardened at 200° C. for 1 hour, and then polished to produce a magnetic disk.

〔実施例２〕 実施例１において、ボールミルでの混線時間を半分の１
２時間とし、その他は同様にして磁気ディスクを製作す
る。[Example 2] In Example 1, the crosstalk time in the ball mill was halved.
The magnetic disk was produced in the same manner except for 2 hours.

〔実施例３〕 Ｃｏ被着型γ−Ｆｅ２０３硼性粉末１００重量部、ａ　
−Ａ７２０３粉末１０重量部、エポキシ樹脂（シエノイ
ヒ学社のエピコート’　１００１）３５重量部、アクリ
ル樹脂（三菱レーヨン社のダイヤナール５Ｅ−５４３７
）２５重量部、メタクリル酸エステル−無水マレイン酸
共重合体（無水マレイン酸同士は結合していない形のラ
ンダム共重合体、メタクリル酸エステルはメタクリル酸
メチル、メタクリル酸メチル／無水マレイン酸＝６０／
４０、Ｍｗ：ｌ：：２０００）１５重量部、混合溶剤６
２０重量部の組成物を用いて、実施例１と同様にして磁
気ディスクを製作する。[Example 3] 100 parts by weight of Co-coated γ-Fe203 boron powder, a
- 10 parts by weight of A7203 powder, 35 parts by weight of epoxy resin (Epicoat' 1001 manufactured by Sienoich Gakusha), acrylic resin (Dianal 5E-5437 manufactured by Mitsubishi Rayon Co., Ltd.)
) 25 parts by weight, methacrylic acid ester-maleic anhydride copolymer (random copolymer in which maleic anhydride is not bonded to each other, methacrylic acid ester is methyl methacrylate, methyl methacrylate/maleic anhydride = 60/
40, Mw:l::2000) 15 parts by weight, mixed solvent 6
A magnetic disk is manufactured in the same manner as in Example 1 using 20 parts by weight of the composition.

〔比較例〕[Comparative example]

Ｃｏ被着型γ−１ｉ’ｅ２０３磁性粉末１００重量部、
α−Ａ、ｔ２０３粉末１０重量部、エピコート１００７
５０重量部、スミラックＰＣ−２５２５重量部、混合溶
剤６２０重量部を用いて、実施例１と同様にして磁気デ
ィスクを製作する。100 parts by weight of Co-coated γ-1i'e203 magnetic powder,
α-A, 10 parts by weight of t203 powder, Epicote 1007
A magnetic disk was manufactured in the same manner as in Example 1 using 50 parts by weight of SUMILAC PC-2525 and 620 parts by weight of the mixed solvent.

〔特性試験〕[Characteristics test]

上記実施例１〜３及び比較例で製作した磁気ディスクに
ついて、磁気特性（保磁力、角型比）、表面欠陥及び耐
摩耗性を調べると表１に示す通りである。　、　□ すなわち、本発明のものは、磁性塗料の混線時磁性粉末
の損傷が少なく、磁値特性の低下は少なく、つまシ保磁
力は比較例のものよりも犬きく、又、角型比は大きく、
分散性が良いことよシ磁気特性の良い記録媒体であるこ
とがわかる。The magnetic properties (coercive force, squareness ratio), surface defects, and wear resistance of the magnetic disks manufactured in Examples 1 to 3 and Comparative Example were examined as shown in Table 1. , □ That is, in the case of the present invention, there is less damage to the magnetic powder when the magnetic paint is crossed, there is less deterioration of the magnetic value characteristics, the magnetic coercive force is higher than that of the comparative example, and the squareness ratio is lower. big,
It can be seen that this recording medium has good dispersibility and good magnetic properties.

又、表面欠陥の数も犬ｌ］に少なくなっておシ、又、耐
摩耗性に関しては実用上半永久的といってもよい位優れ
ている。In addition, the number of surface defects has been reduced to an extremely low level, and the wear resistance is so excellent that it can be said to be semi-permanent in practical terms.

又、磁性塗料の混線時間を従来の半分にしても優れた記
録媒体が得られておシ、すなわち実施例２と比較例とを
比べると実施例２の方がはるかに優れておシ、このよう
なことより現在の規格程度のものを単に満足する程度の
ものでよいとするならば混練詩画は著しく短縮化でき、
製造コストも低置なものとなり、しかも磁性粉末等に対
する制約も緩和でき、選択範囲は極めて広いものとなる
。Moreover, even if the crosstalk time of the magnetic paint is reduced to half of the conventional one, an excellent recording medium can be obtained.In other words, when comparing Example 2 and the comparative example, Example 2 is far superior. If we were to simply satisfy the current standards, we could significantly shorten the time required for kneading poems.
The manufacturing cost is also low, and restrictions on magnetic powder etc. can be relaxed, and the range of selection is extremely wide.

特許出願人　日本ビクター株式会社Patent applicant: Victor Japan Co., Ltd.

Claims (1)

【特許請求の範囲】[Claims] 磁性層中にメタクリル酸エステルと無水マレイン酸とよ
り導かれる共重合体を含むことを特徴とする磁気記録媒
体。A magnetic recording medium characterized in that a magnetic layer contains a copolymer derived from methacrylic acid ester and maleic anhydride.