JPS59172208A - Magnetic powder and manufacture thereof - Google Patents
Magnetic powder and manufacture thereofInfo
- Publication number
- JPS59172208A JPS59172208A JP58046172A JP4617283A JPS59172208A JP S59172208 A JPS59172208 A JP S59172208A JP 58046172 A JP58046172 A JP 58046172A JP 4617283 A JP4617283 A JP 4617283A JP S59172208 A JPS59172208 A JP S59172208A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic powder
- powder
- magnetic
- nitrocellulose
- weight
- 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
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
- G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
Landscapes
- Hard Magnetic Materials (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Paints Or Removers (AREA)
- Magnetic Record Carriers (AREA)
Abstract
Description
【発明の詳細な説明】
この発明は磁石用あるいは磁気記録媒体用として好適な
磁性粉末およびその製造方法に関し、その目的とすると
ころは分散性に優れた磁性粉末を提供することにある。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic powder suitable for use in magnets or magnetic recording media, and a method for producing the same, and an object thereof is to provide a magnetic powder with excellent dispersibility.
磁性粉末は、通常、これを結合剤成分および有機溶剤等
と混練しかつ成型して得られる磁石、あるいは結合剤成
分、有機溶剤およびその他の必要成分とともに混練して
磁性塗料を調製し、これをポリエステルフィルムなどの
基体上に塗布、乾燥してつくられる磁気記録媒体等の記
録素子として使用され、分散性が良好で磁石および磁気
記録媒体等に優れた電気的特性を付与できるものである
ことが要求される。ところが、特に高密度記録に好適な
微粒子の磁性粉末は結合剤成分中に良好に分散させるこ
とは困難で、いまひとつ磁性粉末の分散性が充分に良好
でなく、特に粉末粒子表面が活性な金属磁性粉末は凝集
し易い傾向があって良好に分散し難い。Magnetic powder is usually kneaded with a binder component, an organic solvent, etc. and then molded into a magnet, or a magnetic paint is prepared by kneading it with a binder component, an organic solvent, and other necessary components, and then It is used as a recording element in magnetic recording media, etc., which is made by coating and drying on a substrate such as a polyester film, and it has good dispersibility and can impart excellent electrical properties to magnets and magnetic recording media. required. However, it is difficult to disperse fine-grained magnetic powder, which is particularly suitable for high-density recording, in a binder component, and the dispersibility of magnetic powder is not sufficiently good. Powders tend to aggregate and are difficult to disperse well.
そこで、磁性粉末の分散性を良好にするため、たとえば
、ニトロセルロースを磁性粉末の粉末粒子表面に被着さ
せたり、あるいは低粘度の分散剤で磁性粉末を表面処理
するなどの方法で、磁性粉末の分散性を改善することが
行われているが、従来から磁性粉末の分散性を改善する
ものとして使用されているニトロセルロースは重量平均
分子量が4万5千以上の比較的分子量の大きなものが使
用されているため、未だ磁性粉末の分散性を充分に改善
できず、また低粘度の分散剤で磁性粉末を処理するなど
の方法でも未だ磁性粉末の分散性の改善は充分でなく、
その上この種の分散剤を用いると逆に耐摩耗性が低下す
るなどの問題があった。Therefore, in order to improve the dispersibility of magnetic powder, methods such as coating nitrocellulose on the surface of magnetic powder particles or surface-treating magnetic powder with a low-viscosity dispersant are used to improve the dispersibility of magnetic powder. Nitrocellulose, which has traditionally been used to improve the dispersibility of magnetic powder, has a relatively large weight average molecular weight of 45,000 or more. However, the dispersibility of magnetic powder has not yet been sufficiently improved, and even methods such as treating magnetic powder with a low-viscosity dispersant have not yet sufficiently improved the dispersibility of magnetic powder.
Moreover, when this type of dispersant is used, there are problems such as a decrease in abrasion resistance.
この発明者らはかかる現状に鑑み種々検討を行った結果
、磁性粉末を、重量平均分子量が4万以下のニトロセル
ロースが含まれる有機溶剤で7EA潤処理し、しかる後
、乾燥して粉末粒子表面に重量平均分子量が4万以下の
ニトロセルロースからなる被膜を形成すると、磁性粉末
の分散性が充分に改善され、これを磁気記録媒体用とし
て使用すると磁性層の表面平滑性が一段と良好になって
、優れた磁気特性ないし電磁変換特性が得られ、またこ
れを使用した磁石の磁気特性も充分に改善されることを
見いだし、この発明をなすに至った。The inventors conducted various studies in view of the current situation, and found that magnetic powder was subjected to a 7EA wet treatment with an organic solvent containing nitrocellulose having a weight average molecular weight of 40,000 or less, and then dried to form a surface of the powder particles. When a coating made of nitrocellulose with a weight average molecular weight of 40,000 or less is formed on the magnetic powder, the dispersibility of the magnetic powder is sufficiently improved, and when this is used for magnetic recording media, the surface smoothness of the magnetic layer becomes even better. It was discovered that excellent magnetic properties or electromagnetic conversion properties can be obtained, and that the magnetic properties of a magnet using the same can be sufficiently improved, leading to the present invention.
この発明において使用されるニトロセルロースは、重量
平均分子量が4万以下の低分子量のニトロセルロースで
、重量平均分子量がこれより大きいと磁性粉末と混練し
て磁性塗料等を調製したとき磁性塗料が極めて高粘度に
なるかゲル化することがあるが、この種の低分子量のニ
トロセルロースはこのようなこともなく、磁性粉末との
親和性も良好で、磁性粉末の粒子表面に良好に被着して
被膜を形成し、磁性粉末の分散性を向上する。従って、
この種のニトロセルロースで被覆した磁性粉末を用いて
磁性層を形成すれば、磁性層の表面平滑性も良好なもの
となり、磁気特性ないし電磁変換特性が充分に向上され
る。このようなニトロセルロースとしては、重量平均分
子量が4万以下のものが好ましいが、重量平均分子量3
万以下のものがより好ましく使用され、具体例としては
、たとえば、旭化成社製ニトロセルロース・セルツバE
X−2などが挙げられる。The nitrocellulose used in this invention is low molecular weight nitrocellulose with a weight average molecular weight of 40,000 or less. This type of low-molecular-weight nitrocellulose can become highly viscous or gel, but this type of low-molecular-weight nitrocellulose has good affinity with magnetic powder and adheres well to the surface of magnetic powder particles. to form a film and improve the dispersibility of the magnetic powder. Therefore,
If a magnetic layer is formed using magnetic powder coated with this type of nitrocellulose, the surface smoothness of the magnetic layer will be good, and the magnetic properties or electromagnetic conversion properties will be sufficiently improved. As such nitrocellulose, those with a weight average molecular weight of 40,000 or less are preferable, but those with a weight average molecular weight of 3
10,000 or less is more preferably used, and specific examples include, for example, nitrocellulose Seltsva E manufactured by Asahi Kasei Corporation.
Examples include X-2.
このような重量平均分子量4万以下のニトロセルロース
による磁性粉末の表面処理は、この種のニトロセルロー
スをメチルイソブチルケトン、メチルエチルケトン、ベ
ンゼン、トルエンなどの有機溶剤に熔解させ、この溶液
中に磁性粉末をニーダ−などの適宜手段を用いて分散さ
せた後、乾燥するなどの方法によって行われる。使用量
は磁性粉末に対して0.1〜30重量%の範囲内とし、
望ましくは0.5〜4重量%の範囲内で使用するのが好
ましく、少なすぎると所期の効果が得られず、多すぎる
と得られた磁石、磁気記録媒体の機械的強度が劣化する
。The surface treatment of magnetic powder with nitrocellulose having a weight average molecular weight of 40,000 or less is carried out by dissolving this type of nitrocellulose in an organic solvent such as methyl isobutyl ketone, methyl ethyl ketone, benzene, or toluene, and then adding the magnetic powder to this solution. This is carried out by a method such as dispersing using an appropriate means such as a kneader and then drying. The amount used is within the range of 0.1 to 30% by weight based on the magnetic powder,
It is preferable to use it within the range of 0.5 to 4% by weight; if it is too small, the desired effect cannot be obtained, and if it is too large, the mechanical strength of the resulting magnet and magnetic recording medium will deteriorate.
磁性粉末としては、たとえば、γ−Fe203粉末、F
e3O4粉末、Co含有r−Fe203粉末、Co含有
Fe3O4粉末、CrO2粉末、Fe粉末、Co粉末、
Fe−Ni粉末など従来公知の各種磁性粉末が広く包含
される。Examples of magnetic powder include γ-Fe203 powder, F
e3O4 powder, Co-containing r-Fe203 powder, Co-containing Fe3O4 powder, CrO2 powder, Fe powder, Co powder,
Various conventionally known magnetic powders such as Fe-Ni powder are widely included.
次に、この発明の実施例について説明する。Next, embodiments of the invention will be described.
実施例1
α−Fe磁性粉末 100重量部ニトロセ
ルロース・セルノ 2 〃バEX−2 (旭化
成社製
ニトロセルロース)
メチルイソブチルケトン 50〃の組成でニー
ダ−中で混合分散して磁性粉末の表面処理を行った。こ
のように表面処理して得られたα−Fe磁性粉末に対す
るニトロセルロース・セルツバEX−2の被着量は15
■/gであった。Example 1 α-Fe magnetic powder 100 parts by weight Nitrocellulose Cerno 2 EX-2 (nitrocellulose manufactured by Asahi Kasei Corporation) Methyl isobutyl ketone A composition of 50% was mixed and dispersed in a kneader to perform surface treatment on the magnetic powder. went. The amount of nitrocellulose Seltsuba EX-2 deposited on the α-Fe magnetic powder obtained by surface treatment in this way was 15
■/g.
このようにして得られたα−Fe磁性粉末を使用し、
α−Fe磁性粉末 100重量部ニトロセ
ルロース・セルツバ 20〃EX−2(旭化成社製
ニト
ロセルロース)
メチルイソブチルケトン 146〃トルエン
73〃の組成からなる混合物をボー
ルミルで約72時間混合分散して磁性塗料を調製した。Using the α-Fe magnetic powder thus obtained, α-Fe magnetic powder 100 parts by weight Nitrocellulose Seltsuba 20〃EX-2 (nitrocellulose manufactured by Asahi Kasei Corporation) Methyl isobutyl ketone 146〃Toluene
A magnetic coating material was prepared by mixing and dispersing a mixture having a composition of 73 in a ball mill for about 72 hours.
この磁性塗料を厚さ10μのポリエステルフィルム上に
乾燥厚が約3.5μとなるように塗布、乾燥し、表面処
理を行った後、所定の巾に裁断して磁気テープをつくっ
た。This magnetic paint was applied onto a 10 μm thick polyester film to a dry thickness of about 3.5 μm, dried, surface treated, and then cut to a predetermined width to produce a magnetic tape.
比較例1
実施例1において、ニトロセルロース・セルツバEX−
2に代えて、ニトロセルロースH1/4を同量使用した
以外は実施例1と同様にしてα−Fe磁性粉末の表面処
理を行い、この磁性粉末を実施例1で使用したα−Fe
磁性粉末に代えて同量使用した以外は実施例1と同様に
して磁気テープをつくった。Comparative Example 1 In Example 1, nitrocellulose Seltsuba EX-
α-Fe magnetic powder was surface-treated in the same manner as in Example 1 except that the same amount of nitrocellulose H1/4 was used instead of 2, and this magnetic powder was used as the α-Fe magnetic powder used in Example 1.
A magnetic tape was produced in the same manner as in Example 1, except that the same amount was used in place of the magnetic powder.
比較例2
実施例1において、ニトロセルロース・セルツバEX−
2に代えて低粘度の分散剤を同量使用した以外は実施例
1と同様にしてα−Fe磁性粉末の表面処理を行い、こ
の磁性粉末を実施例1で使用したα−Fe磁性粉末に代
えて、同量使用した以外は実施例1と同様にして磁気テ
ープをつくった。Comparative Example 2 In Example 1, nitrocellulose Seltsuba EX-
α-Fe magnetic powder was surface-treated in the same manner as in Example 1 except that the same amount of low-viscosity dispersant was used in place of Example 2, and this magnetic powder was added to the α-Fe magnetic powder used in Example 1. Instead, a magnetic tape was made in the same manner as in Example 1 except that the same amount was used.
実施例1および比較例1で使用したニトロセルロースの
重量平均分子量を下記の条件で測定したところ、実施例
1で使用したニトロセルロース・セルツバEX−2は2
3900、ニトロセルロースH1,/ 4は53000
であった。When the weight average molecular weight of the nitrocellulose used in Example 1 and Comparative Example 1 was measured under the following conditions, the nitrocellulose Seltsuba EX-2 used in Example 1 was 2.
3900, nitrocellulose H1,/4 is 53000
Met.
〈重量平均分子量の測定条件〉
装置 ニゲル浸透クロマトグラフ、GPC−244
(WATER3)
データ処理: TRC製GPCデータ処理システム
カラム :TSK−GEL−GMHe (2)溶媒
:テトラヒドロフラン
流速 : 2m A /min
温度 :25℃
試料
濃度 :0.2%(wt/vol )
溶解性:完全熔解
濾過 :0.5μmFHLP FILTER(MI
LL T PORE)
注入量 :0.5mj2
検出器 :示差屈折率検出器、R−401(WATE
R)
分子量校正: POLYSTYRENE基準また、実施
例1および各比較例で調製した磁性塗料の粘度を測定し
、さらに実施例および各比較例で得られた磁気テープに
ついて、磁性層の表面平滑性および感度を測定した。な
お、表面平滑性および感度は下記の方法で測定した。<Measurement conditions for weight average molecular weight> Equipment Nigel permeation chromatograph, GPC-244
(WATER3) Data processing: TRC GPC data processing system Column: TSK-GEL-GMHe (2) Solvent: Tetrahydrofuran Flow rate: 2 mA/min Temperature: 25°C Sample concentration: 0.2% (wt/vol) Solubility: Complete melt filtration: 0.5 μm FHLP FILTER (MI
LL T PORE) Injection amount: 0.5mj2 Detector: Differential refractive index detector, R-401 (WATE
R) Molecular weight calibration: POLYSTYRENE standard In addition, the viscosity of the magnetic paint prepared in Example 1 and each comparative example was measured, and the surface smoothness and sensitivity of the magnetic layer were further measured for the magnetic tapes obtained in Example 1 and each comparative example. was measured. Note that surface smoothness and sensitivity were measured by the following methods.
0
〈表面平滑性〉
触針式粗さ計を使用し、触針速度0.06cm/秒、カ
ットオフ0.08mmの条件で磁性層の表面粗さくC。0 <Surface smoothness> Using a stylus type roughness meter, the surface roughness of the magnetic layer was measured at a stylus speed of 0.06 cm/sec and a cutoff of 0.08 mm.
L、^)を測定し、実施例1のものを基準として下記の
式に従って算出される相対値で表面平滑性の良否を判断
した。L, ^) was measured, and the quality of the surface smoothness was determined based on the relative value calculated according to the following formula with reference to that of Example 1.
〈感度〉
実施例1のものを基準(OdB)としたときの各試料の
5MHzの出力(dB)を求めた。<Sensitivity> The 5 MHz output (dB) of each sample was determined using the example 1 as a reference (OdB).
下表はその結果である。The table below shows the results.
上表から明らかなように、実施例1で得られる磁性塗料
は増粘、ゲル化がなく、また実施例1で得られた磁気テ
ープは比較例1および2で得られた磁気テープに比し、
表面平滑性が良好で感度も高く、このことからこの発明
によれば、磁性粉末の分散性が充分に向上され、その結
果磁性層の表面平滑性も良好となって電磁変換特性が向
上されていることがわかる。As is clear from the table above, the magnetic paint obtained in Example 1 did not thicken or gel, and the magnetic tape obtained in Example 1 was superior to the magnetic tapes obtained in Comparative Examples 1 and 2. ,
The surface smoothness is good and the sensitivity is high. Therefore, according to this invention, the dispersibility of the magnetic powder is sufficiently improved, and as a result, the surface smoothness of the magnetic layer is also good, and the electromagnetic conversion characteristics are improved. I know that there is.
Claims (1)
セルロースからなる被膜を設けてなる磁性粉末 2、磁性粉末を、重量平均分子量が4万以下のニトロセ
ルロースが含まれた有機溶剤で湿潤処理し、しかる後、
乾燥して粉末粒子表面に重量平均分子量が4万以下のニ
トロセルロースからなる被膜を形成することを特徴とす
る磁性粉末の製造方法[Claims] 1. Magnetic powder comprising a coating made of nitrocellulose having a weight average molecular weight of 40,000 or less on the surface of the powder particles 2. Magnetic powder containing nitrocellulose having a weight average molecular weight of 40,000 or less After wet treatment with an organic solvent,
A method for producing magnetic powder, which comprises drying to form a coating made of nitrocellulose having a weight average molecular weight of 40,000 or less on the surface of the powder particles.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP58046172A JPS59172208A (en) | 1983-03-20 | 1983-03-20 | Magnetic powder and manufacture thereof |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP58046172A JPS59172208A (en) | 1983-03-20 | 1983-03-20 | Magnetic powder and manufacture thereof |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS59172208A true JPS59172208A (en) | 1984-09-28 |
Family
ID=12739602
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP58046172A Pending JPS59172208A (en) | 1983-03-20 | 1983-03-20 | Magnetic powder and manufacture thereof |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS59172208A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0581652A (en) * | 1991-09-18 | 1993-04-02 | Fuji Photo Film Co Ltd | Magnetic recording material |
JP2008014311A (en) * | 2006-06-30 | 2008-01-24 | Alstom Technology Ltd | Fluid machine |
-
1983
- 1983-03-20 JP JP58046172A patent/JPS59172208A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0581652A (en) * | 1991-09-18 | 1993-04-02 | Fuji Photo Film Co Ltd | Magnetic recording material |
JP2008014311A (en) * | 2006-06-30 | 2008-01-24 | Alstom Technology Ltd | Fluid machine |
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