JPH04310624A - Magnetic recording medium and its production - Google Patents
Magnetic recording medium and its productionInfo
- Publication number
- JPH04310624A JPH04310624A JP10377291A JP10377291A JPH04310624A JP H04310624 A JPH04310624 A JP H04310624A JP 10377291 A JP10377291 A JP 10377291A JP 10377291 A JP10377291 A JP 10377291A JP H04310624 A JPH04310624 A JP H04310624A
- Authority
- JP
- Japan
- Prior art keywords
- carbon black
- magnetic
- less
- magnetic layer
- paint
- 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.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 239000006229 carbon black Substances 0.000 claims abstract description 36
- 239000002245 particle Substances 0.000 claims abstract description 35
- 239000011230 binding agent Substances 0.000 claims abstract description 11
- 229920005989 resin Polymers 0.000 claims abstract description 11
- 239000011347 resin Substances 0.000 claims abstract description 11
- 230000003746 surface roughness Effects 0.000 claims abstract description 11
- 238000003490 calendering Methods 0.000 claims abstract description 8
- 241000872198 Serjania polyphylla Species 0.000 claims abstract description 7
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 7
- 239000010935 stainless steel Substances 0.000 claims abstract description 7
- 239000000758 substrate Substances 0.000 claims abstract description 6
- 238000010008 shearing Methods 0.000 claims abstract description 4
- 239000003973 paint Substances 0.000 claims description 24
- 239000006247 magnetic powder Substances 0.000 claims description 11
- 239000003960 organic solvent Substances 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 abstract description 5
- 230000002776 aggregation Effects 0.000 abstract 2
- 238000004220 aggregation Methods 0.000 abstract 2
- 239000000696 magnetic material Substances 0.000 abstract 1
- 239000002904 solvent Substances 0.000 abstract 1
- 235000019241 carbon black Nutrition 0.000 description 25
- 239000000843 powder Substances 0.000 description 13
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 9
- 229920002554 vinyl polymer Polymers 0.000 description 7
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 6
- 239000000314 lubricant Substances 0.000 description 5
- 229910017344 Fe2 O3 Inorganic materials 0.000 description 4
- 229920001577 copolymer Polymers 0.000 description 4
- 235000014113 dietary fatty acids Nutrition 0.000 description 4
- 239000000194 fatty acid Substances 0.000 description 4
- 229930195729 fatty acid Natural products 0.000 description 4
- 229920002635 polyurethane Polymers 0.000 description 4
- 239000004814 polyurethane Substances 0.000 description 4
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 4
- 241000721047 Danaus plexippus Species 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- -1 fatty acid esters Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920005749 polyurethane resin Polymers 0.000 description 3
- TWJNQYPJQDRXPH-UHFFFAOYSA-N 2-cyanobenzohydrazide Chemical compound NNC(=O)C1=CC=CC=C1C#N TWJNQYPJQDRXPH-UHFFFAOYSA-N 0.000 description 2
- 229910017368 Fe3 O4 Inorganic materials 0.000 description 2
- 235000021360 Myristic acid Nutrition 0.000 description 2
- TUNFSRHWOTWDNC-UHFFFAOYSA-N Myristic acid Natural products CCCCCCCCCCCCCC(O)=O TUNFSRHWOTWDNC-UHFFFAOYSA-N 0.000 description 2
- 235000021355 Stearic acid Nutrition 0.000 description 2
- AYTAKQFHWFYBMA-UHFFFAOYSA-N chromium dioxide Chemical compound O=[Cr]=O AYTAKQFHWFYBMA-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 150000004665 fatty acids Chemical class 0.000 description 2
- 230000001050 lubricating effect Effects 0.000 description 2
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 2
- 229920006267 polyester film Polymers 0.000 description 2
- 229920001228 polyisocyanate Polymers 0.000 description 2
- 239000005056 polyisocyanate Substances 0.000 description 2
- 239000008117 stearic acid Substances 0.000 description 2
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229910018404 Al2 O3 Inorganic materials 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 241001422033 Thestylus Species 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- QHIWVLPBUQWDMQ-UHFFFAOYSA-N butyl prop-2-enoate;methyl 2-methylprop-2-enoate;prop-2-enoic acid Chemical compound OC(=O)C=C.COC(=O)C(C)=C.CCCCOC(=O)C=C QHIWVLPBUQWDMQ-UHFFFAOYSA-N 0.000 description 1
- 239000012461 cellulose resin Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000012948 isocyanate Substances 0.000 description 1
- AJCDFVKYMIUXCR-UHFFFAOYSA-N oxobarium;oxo(oxoferriooxy)iron Chemical compound [Ba]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O AJCDFVKYMIUXCR-UHFFFAOYSA-N 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
Landscapes
- Lubricants (AREA)
- Paints Or Removers (AREA)
- Magnetic Record Carriers (AREA)
- Manufacturing Of Magnetic Record Carriers (AREA)
Abstract
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】この発明は磁気記録媒体およびそ
の製造方法に関し、さらに詳しくは、磁性層の表面粗度
が小さく、かつ摩擦係数が小さくて、電磁変換特性およ
び走行安定性に優れた磁気記録媒体とその製造方法に関
する。
【０００２】
【従来の技術】近年、高密度記録の要請に応えるため、
磁性層の表面を平滑にして磁気ヘッドと磁性層とのコン
タクトを密にすることが行われている。しかしながら、
磁性層の表面が平滑になるほど、記録密度が向上される
反面、走行時の磁気ヘッドやガイドロ−ル等との摩擦係
数が大きくなり、走行が不安定になるとともにときとし
て磁気ヘッドを傷つけることがある。このため、磁性粉
末、結合剤樹脂、有機溶剤さらにカ−ボンブラック等の
必要成分を混合分散して調製された磁性塗料を、基体上
に塗布、乾燥してつくられる磁性層中に、脂肪酸、脂肪
酸エステル等の種々の潤滑剤を混入するなどして、磁性
層表面の摩擦係数を低減し、走行安定性を改善すること
が行われている。
【０００３】
【発明が解決しようとする課題】ところが、磁性層中に
混入したこられの潤滑剤は、使用中に散逸したりして長
期間にわたって摩擦係数を低減させることができず、多
量に混入させると磁性層表面に滲出したりして、磁気テ
−プとして巻回するときテ−プ間で貼りつきが生じるな
どの難点がある。
【０００４】
【課題を解決するための手段】この発明は、かかる現状
に鑑み種々検討を行なつた結果なされたもので、単一粒
子径８０ｍμ以下のカ−ボンブラックの凝集塊を、結合
剤樹脂、有機溶剤およびその他の必要成分とともに剪断
力を加えて混合分散し、カ−ボンブラックの凝集塊を単
一粒子に解した後、この単一粒子に解したカ−ボンブラ
ックを含む塗料を、磁性粉末、結合剤樹脂、有機溶剤お
よびその他の必要成分等を混合分散した塗料中に添加し
、さらに混合分散して磁性塗料を調製し、この磁性塗料
を基体上に塗布、乾燥した後、カレンダ−処理を施すこ
とによって、粒子径が８０ｍμ以下のカ−ボンブラック
を含み、表面粗度が中心線平均粗度（Ｒａ）にして ０
．００７μｍ以下で、ステンレス鋼に対する摩擦係数が
０．２０以下の磁性層を形成し、磁性層の表面を可及的
に平滑にし、かつ摩擦係数を充分に小さくして、電磁変
換特性および走行安定性を充分に向上させたものである
。
【０００５】この発明において、基体上に形成される磁
性層は、まず単一粒子径が８０ｍμ以下のカ−ボンブラ
ックの凝集塊を、結合剤樹脂、有機溶剤およびその他の
必要成分とともに剪断力を加えて混合分散し、カ−ボン
ブラックの凝集塊を単一粒子に解して、単一粒子径が８
０ｍμ以下のカ−ボンブラックを含む塗料を調製する。
そして、この塗料を、磁性粉末、結合剤樹脂、有機溶剤
およびその他の必要成分等を混合分散した塗料中に添加
し、さらに混合分散して磁性塗料を調製した後、この磁
性塗料を基体上に塗布、乾燥し、カレンダ−処理を施し
て形成される。
【０００６】しかして、このようにして形成される磁性
層は、カ−ボンブラックが８０ｍμ以下の単一粒子に解
された状態で均一に分散され、磁性層の表面でこの単一
粒子に解された球状で微粒子のカ−ボンブラックの潤滑
効果が充分に発揮される。従って、磁性層を形成した後
、カレンダ−処理を施して、磁性層の表面粗度を中心線
平均粗度（Ｒａ）にして ０．００７μｍ以下にしても
、ステンレス鋼に対する摩擦係数が充分に低減され、０
．２０〜０．１５程度という格段に低い摩擦係数が得ら
れて、走行安定性が向上される。
【０００７】これに対し、カ−ボンブラックを、磁性粉
末と同時に、結合剤樹脂、有機溶剤およびその他の必要
成分とともに混合分散させて磁性塗料を調製する場合は
、特に、磁性塗料中に分散させにくい磁性粉末が介在す
るため、カ−ボンブラックをその凝集塊の状態から解し
て単一の粒子に分離することが難しく、磁性塗料中に均
一に分散することができない。従って、この場合はカ−
ボンブラックの潤滑効果が発揮されず、走行安定性が改
善されない。
【０００８】このように単一粒子に解されて使用される
カ−ボンブラックは、単一粒子径が８０ｍμ以下のカ−
ボンブラックであることが好ましく、カ−ボンブラック
の単一粒子径が８０ｍμより大きいものでは、単一粒子
に解しても粒子径が大きすぎ、磁性層の表面平滑性が損
なわれるので好ましくない。使用量は、磁性粉末に対し
て ０．５〜８重量％の範囲内にするのが好ましく、少
なすぎると所期の効果が得られず、多すぎると相対的に
磁性粉末が減少し、電磁変換特性の劣化を招くおそれが
ある。
【０００９】このようなカ−ボンブラックとしては、た
とえば、キャボット社製；モナ−ク１２０（単一粒子径
７５ｍμ）、電気化学社製；ＨＳ−１００（単一粒子径
５３ｍμ）、旭日カ−ボン社製；ＨＳ−５００（単一粒
子径４３ｍμ）などが好適なものとして使用される。
【００１０】また、このような単一粒子径が８０ｍμ以
下のカ−ボンブラックを含む磁性層の表面粗度は、充分
な高密度記録が行えるようにするため、カレンダ−処理
を施すなどして中心線平均粗度（Ｒａ）にして ０．０
０７μｍ以下にするのが好ましく、中心線平均粗度（Ｒ
ａ）が ０．００７μｍより粗くなると充分な高密度記
録が行えない。
【００１１】さらに、単一粒子径が８０ｍμ以下のカ−
ボンブラックを含み、表面粗度を中心線平均粗度（Ｒａ
）にして ０．００７μｍ以下にした磁性層のステンレ
ス鋼に対する摩擦係数は、０．２０より大きいと走行安
定性が充分に向上されないため、０．２０以下にするこ
とが好ましい。
【００１２】このような磁性層の形成に際し、使用され
る磁性粉末としては、たとえば、γ−Ｆｅ２ Ｏ３ 粉
末、Ｆｅ３ Ｏ４粉末、Ｃｏ含有γ−Ｆｅ２ Ｏ３ 粉
末、Ｃｏ含有Ｆｅ３ Ｏ４ 粉末、ＣｒＯ２ 粉末の他
、Ｆｅ粉末、Ｃｏ粉末、Ｆｅ−Ｎｉ粉末、バリウムフェ
ライト粉末など従来公知の各種磁性粉末が広く使用され
る。
【００１３】また、結合剤樹脂としては、塩化ビニル−
酢酸ビニル系共重合体、繊維素系樹脂、ポリウレタン系
樹脂、ポリエステル系樹脂、アクリル系樹脂、ゴム系樹
脂、イソシアネ−ト化合物など、通常、磁性粉末の結合
剤成分として使用されるものが広く使用される。
【００１４】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、脂肪酸、脂肪酸エステル、シリ
コ−ン系潤滑剤、フッ素系潤滑剤等の潤滑剤および分散
剤や、帯電防止剤などを任意に添加使用してもよい。
【００１５】
【実施例】次に、この発明の実施例について説明する。
実施例１
カ−ボンブラック（キャボット社製；モナ−ク
１２０ 、単一 ８重量部
粒子径７５ｍμ）
塩化ビニル−酢酸ビニル−ビニルアルコ−ル共
重合体（積 ９ 〃 水化
学工業社製；エスレックＡ） シクロヘキサノン
９ 〃
トルエン
９ 〃この組成物をボ−ルミルで４
０時間混合分散して塗料を調製した。
【００１６】一方、
Ｃｏ含有γ−Ｆｅ２ Ｏ３ 粉末（保磁力 ５
２０エルステッド、 ２００重量部
ＢＥＴ比表面積３０ｍ２／ｇ） 塩化ビニル−酢
酸ビニル−ビニルアルコ−ル共重合体（積
２５ 〃 水化学工業社製；エスレックＡ
） ポリウレタン樹脂（日本ポリウレタン工業社
製；Ｎ−２３０９） ２５ 〃 ポリイ
ソシアネ−ト化合物（日本ポリウレタン工業社製；
１２ 〃 コロネ−トＬ）
α−Ａｌ２ Ｏ３ 粉末（平均粒子径０．２５
μｍ） ３
〃 ミリスチン酸
２ 〃 ステアリン酸ｎ
−ブチル
２ 〃
シクロヘキサノン
３４
０ 〃 トルエン
３４０ 〃の組成物をボ−ルミ
ルで４０時間混合分散して塗料を調製し、これに前記の
カ−ボンブラックを含む塗料を添加し、さらに１時間混
合分散して磁性塗料を調製した。次いで、この磁性塗料
を厚さ１４μｍのポリエステルフィルム上に乾燥後の厚
さが４μｍとなるように塗布、乾燥し、カレンダ−処理
を行って、磁性層を形成した。しかる後、所定の幅に裁
断して磁気テ−プをつくった。
【００１７】比較例１
Ｃｏ含有γ−Ｆｅ２ Ｏ３ 粉末（保磁力 ５
２０エルステッド、 ２００重量部
ＢＥＴ比表面積３０ｍ２／ｇ） 塩化ビニル−酢
酸ビニル−ビニルアルコ−ル共重合体（積
３４ 〃 水化学工業社製；エスレックＡ
） ポリウレタン樹脂（日本ポリウレタン工業社
製；Ｎ−２３０９） ２５ 〃 ポリイ
ソシアネ−ト化合物（日本ポリウレタン工業社製；
１２ 〃 コロネ−トＬ）
カ−ボンブラック（キャボット社製；モナ−ク
１２０ 、単一 ８ 〃
粒子径７５ｍμ）
α−Ａｌ２ Ｏ３ 粉末（平均粒子径０．２５
μｍ） ３
〃 ミリスチン酸
２ 〃 ステアリン酸ｎ
−ブチル
２ 〃
シクロヘキサノン
３４
９ 〃 トルエン
３４９ 〃この組成物をボ−ル
ミルで４０時間混合分散して磁性塗料を調製した。次い
で、この磁性塗料を厚さ１４μｍのポリエステルフィル
ム上に乾燥後の厚さが４μｍとなるように塗布、乾燥し
、カレンダ−処理を行って、磁性層を形成した。しかる
後、所定の幅に裁断して磁気テ−プをつくった。
【００１８】各実施例および比較例で得られた磁気テ−
プについて、下記の方法で磁性層の表面粗度、摩擦係数
およびＲＦ出力を測定し、走行安定性を調べた。
【００１９】＜磁性層の表面粗度＞触針式表面粗度計を
用いて、触針速度０．０６ｍｍ／秒、カットオフ０．０
８ｍｍの条件で、磁気テ−プの磁性層の中心線平均粗度
（Ｒａ）を測定した。
【００２０】＜摩擦係数＞直径２０ｍｍφのステンレス
ピン上に得られた磁気テ−プの長手方向がピンと垂直に
なるようにして磁性層を接しておき、磁気テ−プの一端
に３０ｇの荷重をかけ、もう一端を３ｍ／ｓｅｃ の送
り速度で引っ張った時の負荷荷重より摩擦係数を求めた
。
【００２１】＜ＲＦ出力＞ＶＨＳ方式のＶＴＲを用い、
得られた磁気テ−プに５０％ホワイトのビデオ信号を記
録再生し、そのＦＭ変調再生信号のレベルをオシロスコ
−プを用い測定して、基準テ−プとの相対値で示した。
【００２２】＜走行安定性＞ＶＨＳ方式のＶＴＲを用い
、得られた磁気テ−プを１０００回走行させ、その後、
磁気テ−プの変形を観察して、磁気テ−プ変形が全く認
められない場合を（○）、わずかに認められる場合を（
△）、磁気テ−プ変形が著しい場合を（×）として評価
した。下記表１はその結果である。
【００２３】
【００２４】
【発明の効果】上記表１から明らかなように、この発明
で得られた磁気テ−プ（実施例１）は、従来の磁気テ−
プ（比較例１）に比し、摩擦係数が小さく、また表面粗
度が小さく、ＲＦ出力が高くて、走行安定性がよく、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、
摩擦係数が小さく、磁性層の表面平滑性が良好で、走行
安定性および電磁変換特性に優れていることがわかる。[0001] The present invention relates to a magnetic recording medium and a method for manufacturing the same, and more particularly, the present invention relates to a magnetic recording medium and a method for manufacturing the same, and more particularly, the present invention relates to a magnetic recording medium and a method for manufacturing the same. This invention relates to a magnetic recording medium with excellent conversion characteristics and running stability, and a method for manufacturing the same. [0002] In recent years, in order to meet the demand for high-density recording,
The surface of the magnetic layer is smoothed to ensure close contact between the magnetic head and the magnetic layer. however,
The smoother the surface of the magnetic layer, the higher the recording density, but on the other hand, the coefficient of friction between the magnetic head and guide rolls during running increases, making running unstable and sometimes damaging the magnetic head. be. For this reason, a magnetic coating prepared by mixing and dispersing necessary components such as magnetic powder, binder resin, organic solvent, and carbon black is coated on a substrate and dried, and the resulting magnetic layer contains fatty acids, Various lubricants such as fatty acid esters are mixed in to reduce the coefficient of friction on the surface of the magnetic layer and improve running stability. [0003] However, these lubricants mixed in the magnetic layer cannot reduce the coefficient of friction over a long period of time because they dissipate during use, and are used in large amounts. If it is mixed in, it may ooze out onto the surface of the magnetic layer, causing problems such as sticking between the tapes when it is wound as a magnetic tape. [Means for Solving the Problems] The present invention was made as a result of various studies in view of the current situation, and consists of carbon black agglomerates with a single particle diameter of 80 mμ or less, which are combined with a binder. After mixing and dispersing the carbon black with resin, organic solvent, and other necessary ingredients by applying shearing force to break down the carbon black agglomerates into single particles, paint containing the carbon black broken down into single particles is mixed and dispersed. , magnetic powder, binder resin, organic solvent, and other necessary components are added to the mixed and dispersed paint, further mixed and dispersed to prepare a magnetic paint, and after coating this magnetic paint on a substrate and drying, By calendering, carbon black with a particle size of 80 mμ or less is contained, and the surface roughness is reduced to 0 in terms of center line average roughness (Ra).
．． 0.07 μm or less and a friction coefficient of 0.20 or less against stainless steel, the surface of the magnetic layer is made as smooth as possible, and the friction coefficient is made sufficiently small to improve electromagnetic conversion characteristics and running stability. It has been sufficiently improved. In the present invention, the magnetic layer formed on the substrate is first formed by applying shearing force to carbon black aggregates having a single particle size of 80 mμ or less together with a binder resin, an organic solvent, and other necessary components. In addition, the carbon black is mixed and dispersed to break up the carbon black agglomerates into single particles, and the single particle diameter is 8.
A paint containing carbon black of 0 mμ or less is prepared. Then, this paint is added to a paint that has been mixed and dispersed with magnetic powder, binder resin, organic solvent, and other necessary components, and further mixed and dispersed to prepare a magnetic paint, and then this magnetic paint is applied onto a substrate. It is formed by coating, drying, and calendering. [0006] In the magnetic layer formed in this way, the carbon black is uniformly dispersed into single particles of 80 mμ or less, and the carbon black is dissolved into single particles on the surface of the magnetic layer. The lubricating effect of the fine spherical carbon black particles is fully exhibited. Therefore, even if the surface roughness of the magnetic layer is reduced to 0.007 μm or less by calendering after forming the magnetic layer, the coefficient of friction against stainless steel is sufficiently reduced. and 0
．． A significantly low coefficient of friction of about 20 to 0.15 can be obtained, improving running stability. On the other hand, when preparing a magnetic paint by mixing and dispersing carbon black together with magnetic powder, binder resin, organic solvent, and other necessary components, it is particularly difficult to disperse carbon black in the magnetic paint. Because of the presence of hard magnetic powder, it is difficult to break the carbon black from its agglomerated state and separate it into single particles, making it impossible to uniformly disperse it in the magnetic paint. Therefore, in this case, the car
The lubricating effect of the bomb black is not exerted, and driving stability is not improved. [0008] Carbon black, which is used as a single particle in this way, has a single particle diameter of 80 mμ or less.
Carbon black is preferable, and carbon black with a single particle size larger than 80 mμ is not preferable because the particle size is too large even when broken down into a single particle and the surface smoothness of the magnetic layer is impaired. . The amount used is preferably within the range of 0.5 to 8% by weight based on the magnetic powder. If it is too small, the desired effect will not be obtained, and if it is too large, the magnetic powder will be relatively reduced, and the electromagnetic This may lead to deterioration of conversion characteristics. Examples of such carbon blacks include Monarch 120 (single particle diameter 75 mμ) manufactured by Cabot, HS-100 (single particle diameter 53 mμ) manufactured by Denki Kagaku Co., Ltd., and Asahi Carbon Black. HS-500 (single particle diameter 43 mμ) manufactured by Bonn Co., Ltd. is preferably used. [0010] In addition, the surface roughness of the magnetic layer containing carbon black with a single particle size of 80 mμ or less can be improved by calendering or other means in order to enable sufficient high-density recording. Center line average roughness (Ra) is 0.0
The center line average roughness (R
If a) becomes rougher than 0.007 μm, sufficient high-density recording cannot be performed. Furthermore, a carton with a single particle diameter of 80 mμ or less
Including bomb black, the surface roughness is defined as center line average roughness (Ra
) The friction coefficient of the magnetic layer with respect to stainless steel, which is 0.007 μm or less, is preferably 0.20 or less because running stability will not be sufficiently improved if it is larger than 0.20. [0012] Magnetic powders used in forming such a magnetic layer include, for example, γ-Fe2 O3 powder, Fe3 O4 powder, Co-containing γ-Fe2 O3 powder, Co-containing Fe3 O4 powder, CrO2 powder, and others. Various conventionally known magnetic powders such as , Fe powder, Co powder, Fe-Ni powder, and barium ferrite powder are widely used. [0013] As the binder resin, vinyl chloride-
Widely used are vinyl acetate copolymers, cellulose resins, polyurethane resins, polyester resins, acrylic resins, rubber resins, isocyanate compounds, etc. that are normally used as binder components for magnetic powders. be done. [0014] Various additives commonly used in magnetic paints include lubricants and dispersants such as fatty acids, fatty acid esters, silicone lubricants, and fluorine lubricants, and antistatic agents. may be optionally added. [Example] Next, an example of the present invention will be described. Example 1 Carbon black (manufactured by Cabot Corporation; Monarch 120, single 8 parts by weight)
Particle size: 75 mμ) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer (product size 9: manufactured by Suikagaku Kogyo Co., Ltd.; S-LEC A) Cyclohexanone
9 〃
toluene
9〃This composition was milled in a ball mill for 4
A paint was prepared by mixing and dispersing for 0 hours. On the other hand, Co-containing γ-Fe2 O3 powder (coercive force 5
20 oersted, 200 parts by weight
BET specific surface area 30m2/g) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer (
25〃 Manufactured by Suikagaku Kogyo Co., Ltd.; S-LEC A
) Polyurethane resin (manufactured by Nippon Polyurethane Kogyo Co., Ltd.; N-2309) 25 〃 Polyisocyanate compound (manufactured by Nippon Polyurethane Kogyo Co., Ltd.;
12 Coronate L) α-Al2 O3 powder (average particle size 0.25
μm) 3
〃Myristic acid
2 Stearic acid n
-butyl
2 〃
cyclohexanone
34
0 〃 Toluene
A paint was prepared by mixing and dispersing the composition of No. 340 in a ball mill for 40 hours, to which the paint containing the carbon black described above was added, and further mixing and dispersing for 1 hour to prepare a magnetic paint. Next, this magnetic paint was applied onto a polyester film having a thickness of 14 .mu.m to a dry thickness of 4 .mu.m, dried, and calendered to form a magnetic layer. Thereafter, it was cut to a predetermined width to make magnetic tape. Comparative Example 1 Co-containing γ-Fe2 O3 powder (coercive force 5
20 oersted, 200 parts by weight
BET specific surface area 30m2/g) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer (
34〃 Manufactured by Suikagaku Kogyo Co., Ltd.; S-LEC A
) Polyurethane resin (manufactured by Nippon Polyurethane Kogyo Co., Ltd.; N-2309) 25 〃 Polyisocyanate compound (manufactured by Nippon Polyurethane Kogyo Co., Ltd.;
12 〃 Coronate L) Carbon black (manufactured by Cabot; Monarch 120, single 8 〃
α-Al2O3 powder (average particle size 0.25)
μm) 3
〃Myristic acid
2 Stearic acid n
-butyl
2 〃
cyclohexanone
34
9 Toluene
349 This composition was mixed and dispersed in a ball mill for 40 hours to prepare a magnetic paint. Next, this magnetic paint was applied onto a polyester film having a thickness of 14 .mu.m to a dry thickness of 4 .mu.m, dried, and calendered to form a magnetic layer. Thereafter, it was cut to a predetermined width to make magnetic tape. [0018] The magnetic tape obtained in each example and comparative example
The surface roughness, friction coefficient, and RF output of the magnetic layer were measured using the methods described below to examine running stability. <Surface roughness of magnetic layer> Using a stylus type surface roughness meter, the stylus speed was 0.06 mm/sec, the cutoff was 0.0.
The center line average roughness (Ra) of the magnetic layer of the magnetic tape was measured under the condition of 8 mm. <Friction coefficient> The magnetic layer was placed on a stainless steel pin with a diameter of 20 mm in such a way that the longitudinal direction was perpendicular to the pin, and a load of 30 g was applied to one end of the magnetic tape. The friction coefficient was determined from the applied load when the other end was pulled at a feed rate of 3 m/sec. <RF output> Using a VHS type VTR,
A 50% white video signal was recorded and reproduced on the obtained magnetic tape, and the level of the FM modulated reproduction signal was measured using an oscilloscope and expressed as a relative value with respect to the reference tape. <Running Stability> Using a VHS type VTR, the obtained magnetic tape was run 1000 times, and then
Observe the deformation of the magnetic tape, and mark cases where no magnetic tape deformation is observed at all (○) and cases where it is slightly observed (
Δ), cases where the magnetic tape was significantly deformed were evaluated as (x). Table 1 below shows the results. Effects of the Invention As is clear from Table 1 above, the magnetic tape (Example 1) obtained by the present invention is superior to the conventional magnetic tape.
The magnetic recording medium obtained by the present invention has a lower coefficient of friction, lower surface roughness, higher RF output, and better running stability than the magnetic recording medium (Comparative Example 1).
It can be seen that the coefficient of friction is small, the surface smoothness of the magnetic layer is good, and the running stability and electromagnetic conversion characteristics are excellent.
Claims (1)
ブラックを含み、表面粗度が中心線平均粗度（Ｒａ）に
して ０．００７μｍ以下で、ステンレス鋼に対する摩
擦係数が０．２０以下の磁性層を有する磁気記録媒体【
請求項２】 単一粒子径８０ｍμ以下のカ−ボンブラ
ックの凝集塊を、結合剤樹脂、有機溶剤およびその他の
必要成分とともに剪断力を加えて混合分散し、カ−ボン
ブラックの凝集塊を単一粒子に解した後、この単一粒子
に解したカ−ボンブラックを含む塗料を、磁性粉末、結
合剤樹脂、有機溶剤およびその他の必要成分等を混合分
散した塗料中に添加し、さらに混合分散して磁性塗料を
調製し、この磁性塗料を基体上に塗布、乾燥した後、カ
レンダ−処理を施して、単一粒子径が８０ｍμ以下のカ
−ボンブラックを含み、表面粗度が中心線平均粗度（Ｒ
ａ）にして ０．００７μｍ以下で、ステンレス鋼に対
する摩擦係数が０．２０以下の磁性層を形成することを
特徴とする磁気記録媒体の製造方法Claim 1: Contains carbon black with a single particle diameter of 80 mμ or less, has a surface roughness of 0.007 μm or less in terms of center line average roughness (Ra), and has a friction coefficient of 0.20 or less against stainless steel. A magnetic recording medium having a magnetic layer of [
2. Carbon black agglomerates with a single particle diameter of 80 mμ or less are mixed and dispersed together with a binder resin, an organic solvent, and other necessary components by applying shearing force, and the carbon black agglomerates are separated into single particles. After disintegrating the carbon black into single particles, the paint containing the carbon black dissolved into single particles is added to a paint containing mixed and dispersed magnetic powder, binder resin, organic solvent, and other necessary components, and further mixed. After dispersing and preparing a magnetic paint, this magnetic paint is applied onto a substrate, dried, and then calendered to contain carbon black with a single particle diameter of 80 mμ or less, and the surface roughness is at the center line. Average roughness (R
a) A method for manufacturing a magnetic recording medium, comprising forming a magnetic layer having a thickness of 0.007 μm or less and a coefficient of friction against stainless steel of 0.20 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10377291A JPH04310624A (en) | 1991-04-08 | 1991-04-08 | Magnetic recording medium and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10377291A JPH04310624A (en) | 1991-04-08 | 1991-04-08 | Magnetic recording medium and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04310624A true JPH04310624A (en) | 1992-11-02 |
Family
ID=14362747
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10377291A Pending JPH04310624A (en) | 1991-04-08 | 1991-04-08 | Magnetic recording medium and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04310624A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6120870A (en) * | 1995-05-11 | 2000-09-19 | Seiko Epson Corporation | Optical disk and production method thereof |
| US6162519A (en) * | 1996-07-11 | 2000-12-19 | Seiko Epson Corporation | Optical disc and process for the production of the same, and process for the production of sheet material |
-
1991
- 1991-04-08 JP JP10377291A patent/JPH04310624A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6120870A (en) * | 1995-05-11 | 2000-09-19 | Seiko Epson Corporation | Optical disk and production method thereof |
| US6162519A (en) * | 1996-07-11 | 2000-12-19 | Seiko Epson Corporation | Optical disc and process for the production of the same, and process for the production of sheet material |
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