JPH039530B2 - - Google Patents
Info
- Publication number
- JPH039530B2 JPH039530B2 JP57137892A JP13789282A JPH039530B2 JP H039530 B2 JPH039530 B2 JP H039530B2 JP 57137892 A JP57137892 A JP 57137892A JP 13789282 A JP13789282 A JP 13789282A JP H039530 B2 JPH039530 B2 JP H039530B2
- Authority
- JP
- Japan
- Prior art keywords
- carbon black
- magnetic
- aluminum oxide
- adsorbed
- added
- 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.)
- Expired - Lifetime
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
- G11B5/708—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 addition of non-magnetic particles to the layer
Landscapes
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Paints Or Removers (AREA)
- Magnetic Record Carriers (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Description
本発明は磁気記録媒体に係り、磁性層中にカー
ボンブラツク吸着アルミナを含ませておくことに
より、磁性層の耐摩耗性、耐久性に富み、再生減
磁は小さく、又、帯電防止効果に優れ、ゴミやホ
コリ等が付着しにくく、走行性に優れたものとな
り、又遮光性にも優れ、さらには角型比も良好な
磁気記録媒体を提供することを目的とする。
従来、ビデオテープレコーダ用の磁気テープ、
あるいはフロツピーデイスク等の磁気記録媒体の
磁性層中には、磁性層の耐摩耗性向上の為に
Cr2O3又はAl2O3等の粉末が加えられており、又、
磁性層の帯電防止及び遮光性の向上の為にカーボ
ンブラツク等が加えられている。
しかし、これらの添加物によつて所望の効果を
得ようとするには、ある程度多く加えなければな
らないが、多く加えれば加える程磁性層中の磁性
粉の充填密度は小さくなり、しかも磁性層表面の
荒れてしまうものとなるので、磁気特性が低下
し、その為現実にはこれらの特性の調和を図つて
用いているにすぎないものである。
従つて、記録密度等の磁気特性の向上の観点か
らは、Al2O3、カーボンブラツク等の添加量は少
ない程望ましいものとなり、帯電防止、遮光性、
耐摩耗性等の特性が少量でも向上するものとなる
物質の開発が望まれている。
本発明は上記要望に沿つてなされたものであ
り、以下本発明に係る磁気記録媒体の実施例につ
いて説明する。
実施例
γ−Fe2O3420部、塩化ビニル−酢酸ビニル共
重合体65部、ポリウレタンエラストマー110部、
卵黄レシチン５部、メチルエチルケトン600部、
トルエン600部、平均粒径100mμ以下で比表面積
が30m2／ｇ以上のカーボンブラツクを酸化アルミ
ニウム粉末に対して0.5重量％以上吸着させたカ
ーボンブラツク吸着酸化アルミニウミ粉末３部以
上の混合物を、サンドミルで約20時間混合分散
し、これにイソシアネート系硬化剤を加えて磁性
塗料を作り、この磁性塗料を例えばポリエステル
フイルム等の支持体に塗布し、乾燥後カレンダー
処理し、その後加温して硬化反応を行なわしめ、
そして所定巾にスリツトして例えばビデオ用磁気
テープを得る。
尚、上記カーボンブラツク吸着酸化アルミニウ
ムは、次のようにすれば得られる。
酸化アルミニウムの粉末とカーボンブラツクの
粉末を所定量づつ秤量し、その中に分散剤と水を
入れて混練、分散する。
充分に分散された混合物から脱水して水分をな
くす。続いて高温、高圧容器に移し、真空状態と
する為に空気を抜く。この時の圧力は10-5Torr
以下とする。さらに、温度を300℃に保ち、圧力
を30気圧かけて10時間保つ。その後、温度を下
げ、圧力を１気圧に戻す。
このようにして生成されたカーボンブラツク吸
着物は酸化アルミニウムの表面に均一にカーボン
ブラツクが吸着されてり、物理化学的結合力によ
り通常のエネルギーでは剥れない構造のものとな
つている。
比較例
前記実施例におけるカーボンブラツク吸着酸化
アルミニウム粉末を0.6部として、又はカーボン
ブラツク吸着酸化アルミニウム粉末の代りにカー
ボンブラツク、酸化アルミニウムを用いて、同様
にして磁気テープを得る。
このようにして得られた磁気テープについて、
その再生減磁、表面電気抵抗、光透過率、角型比
及びカラーＳ／Ｎ等の特性を測定すると、表及び
第１図〜第４図に示す通りである。
The present invention relates to a magnetic recording medium, and by incorporating carbon black-adsorbed alumina into the magnetic layer, the magnetic layer has excellent wear resistance and durability, has low reproduction demagnetization, and has an excellent antistatic effect. It is an object of the present invention to provide a magnetic recording medium that is difficult to attract dirt, dust, etc., has excellent running properties, has excellent light-shielding properties, and also has a good squareness ratio. Conventionally, magnetic tape for video tape recorders,
Or, in the magnetic layer of magnetic recording media such as floppy disks, there is a
Powders such as Cr 2 O 3 or Al 2 O 3 are added, and
Carbon black or the like is added to the magnetic layer to prevent static electricity and improve light-shielding properties. However, in order to obtain the desired effect with these additives, it is necessary to add them in a certain amount, but the more they are added, the smaller the packing density of the magnetic powder in the magnetic layer becomes. As a result, the magnetic properties deteriorate, and in reality, these properties are used only in an attempt to harmonize them. Therefore, from the viewpoint of improving magnetic properties such as recording density, the smaller the amount of Al 2 O 3 , carbon black, etc. added, the better.
It is desired to develop a substance that can improve properties such as wear resistance even in small amounts. The present invention has been made in response to the above-mentioned demands, and examples of the magnetic recording medium according to the present invention will be described below. Example 420 parts of γ-Fe 2 O 3 , 65 parts of vinyl chloride-vinyl acetate copolymer, 110 parts of polyurethane elastomer,
5 parts of egg yolk lecithin, 600 parts of methyl ethyl ketone,
A mixture of 600 parts of toluene and 3 parts or more of carbon black-adsorbed aluminum oxide powder, in which 0.5% by weight or more of carbon black with an average particle size of 100 mμ or less and a specific surface area of 30 m 2 /g or more has been adsorbed to aluminum oxide powder, is prepared using a sand mill. After mixing and dispersing for about 20 hours, an isocyanate curing agent is added to make a magnetic paint, and this magnetic paint is applied to a support such as a polyester film, dried, calendered, and then heated to cause a curing reaction. Conduct,
The tape is then slit to a predetermined width to obtain, for example, a video magnetic tape. The carbon black adsorbed aluminum oxide can be obtained in the following manner. Predetermined amounts of aluminum oxide powder and carbon black powder are weighed out, a dispersant and water are added thereto, and the mixture is kneaded and dispersed. The well-dispersed mixture is dehydrated to eliminate water. Next, it is transferred to a high-temperature, high-pressure container, and the air is removed to create a vacuum state. The pressure at this time is 10 -5 Torr
The following shall apply. Furthermore, the temperature is maintained at 300℃ and the pressure is applied to 30 atmospheres for 10 hours. Thereafter, the temperature is lowered and the pressure is returned to 1 atmosphere. The carbon black adsorbate thus produced has carbon black uniformly adsorbed on the surface of aluminum oxide, and has a structure that cannot be peeled off by ordinary energy due to physicochemical bonding force. Comparative Example A magnetic tape was obtained in the same manner as in the above Example except that 0.6 part of the carbon black adsorbed aluminum oxide powder was used, or carbon black or aluminum oxide was used in place of the carbon black adsorbed aluminum oxide powder. Regarding the magnetic tape obtained in this way,
The characteristics such as regenerative demagnetization, surface electrical resistance, light transmittance, squareness ratio, and color S/N were measured as shown in the table and FIGS. 1 to 4.
【表】
上記の結果からわかるように、表面電気抵抗及
び遮光性に効果を及ぼすのは、カーボンブラツク
が磁性層中に0.6重量％以上含まれているもので
あり、又再生減磁に効果を及ぼすのは、酸化アル
ミニウムが磁性層中に0.8重量％以上含まれてい
るものであり、従つて表面電気抵抗、遮光性、再
生減磁のいずれの特性の向上をも図ろうとする
と、カーボンブラツク及び酸化アルミニウム等非
磁性粉の含有量は多くなり、磁性粉の充填密度は
小さくなり、電磁変換特性はそれだけ低下し、例
えば角型比等の磁気特性は悪いものとなつてい
る。
これに対して、本実施例の結果が示すように、
酸化アルミニウム、カーボンブラツクを磁性層中
に含ませるのではなく、カーボンブラツク吸着ア
ルミナ磁性層中に、特に磁性層中に0.5重量％以
上含ませることにより、表面電気抵抗、遮光性及
び再生減磁の特性向上は少量でも図れるものとな
り、従つて、磁性粉の充填密度をそれだけ大きな
ものとでき、電磁変換特性の低下は小さく、例え
ば角型比の特性も優れたものである。
すなわち、通常非磁性物である酸化アルミニウ
ムとカーボンブラツクとを各々単体で添加した場
合には、角型比、カラーＳ／Ｎは添加量と共に単
調に減少していく。
しかしながら、本発明のカーボンブラツク吸着
酸化アルミニウムは、第１図や第４図で示してい
る如く、添加と共に各々の特性が向上している。
つまり、カーボンブラツク吸着酸化アルミニウム
の添加が磁性塗料の分散性の向上や角型比の向上
をもたらしていること明白である。
又、第３図に示す如く、本発明のものは再生減
磁も少ない。
このように、カーボンブラツクが吸着していな
い酸化アルミニウムとカーボンブラツクとを共に
各々添加していても、このような場合には添加量
が少ないと光透過率、再生減磁には効果がなく、
逆に添加量が多くなると角型比、カラーＳ／Ｎが
低下し、双方の特性向上が得られないのに対し
て、カーボンブラツク吸着酸化アルミニウムが用
いられると、いずれの特性も向上し、カーボンブ
ラツクが吸着していない酸化アルミニウム及びカ
ーボンブラツクを各々用いた場合からは考えられ
ない特長がもたらされる。
尚、カーボンブラツクが平均粒径100mμ以下で
比表面積30m2／ｇ以上のものを用いた理由は、吸
着させるカーボンブラツクにより角型比やカラー
Ｓ／Ｎに多少の相違がで、例えばカーボンブラツ
クの粒径が大きすぎる場合には、テープ表面が粗
くなり、カラーＳ／Ｎが低下してくる傾向があ
り、逆に、カーボンブラツクの比表面積が小さす
ぎると、酸化アルミニウムへの吸着性が低くな
り、分散性、角型比が低下する傾向があり、カー
ボンブラツクは平均粒径100mμ以下で比表面積30
m2／ｇ以上のものであることが特に好ましかつた
からである。
上述の如く、本発明に係る磁気記録媒体は、磁
性層中に、平均粒径100mμ以下で比表面積30m2／
ｇ以上のカーボンブラツクを酸化アルミニウム粉
末に吸着させたものを磁性粉末に対して約0.5重
量％以上含むものであるので、磁性層の耐摩耗
性、耐久性に富み、再生減磁は小さく、又、帯電
防止効果に優れ、ゴミやホコリ等が付着しにく
く、走行性にも優れたものであり、又遮光性にも
優れ、光センサー等によるテープ端検出機構が誤
動作することなく、特にこれらの特性向上の為に
加える添加物は少量でも効果を発揮するものであ
り、従つて相対的に磁性粉末の充填密度を大きな
ものとでき、電磁変換特性は良好であり、角型比
等も大きなものである等の特長を有する。[Table] As can be seen from the above results, carbon black has an effect on the surface electrical resistance and light shielding properties when it is contained in the magnetic layer in an amount of 0.6% by weight or more, and it also has an effect on regenerative demagnetization. This is because aluminum oxide is contained in the magnetic layer in an amount of 0.8% by weight or more, and therefore, when trying to improve the surface electrical resistance, light shielding properties, and regenerative demagnetization properties, carbon black and The content of non-magnetic powder such as aluminum oxide increases, the packing density of magnetic powder decreases, and the electromagnetic conversion characteristics deteriorate accordingly. For example, magnetic characteristics such as squareness ratio become poor. On the other hand, as shown by the results of this example,
Rather than including aluminum oxide and carbon black in the magnetic layer, by including 0.5% by weight or more in the carbon black-adsorbed alumina magnetic layer, especially in the magnetic layer, surface electrical resistance, light shielding properties, and regenerative demagnetization can be improved. The characteristics can be improved even with a small amount, and therefore the packing density of the magnetic powder can be increased accordingly, the electromagnetic conversion characteristics are less deteriorated, and the squareness ratio characteristics, for example, are also excellent. That is, when aluminum oxide and carbon black, which are usually non-magnetic substances, are added alone, the squareness ratio and color S/N decrease monotonically with the amount added. However, as shown in FIGS. 1 and 4, the carbon black-adsorbed aluminum oxide of the present invention improves its properties as it is added.
In other words, it is clear that the addition of carbon black-adsorbed aluminum oxide improves the dispersibility and squareness ratio of the magnetic paint. Further, as shown in FIG. 3, the device of the present invention has less regenerative demagnetization. In this way, even if both aluminum oxide and carbon black to which carbon black is not adsorbed are added, in such cases, if the amount added is small, there will be no effect on light transmittance or regenerative demagnetization.
On the other hand, when the amount added increases, the squareness ratio and color S/N decrease, and improvements in both properties cannot be obtained.However, when carbon black adsorbed aluminum oxide is used, both properties improve, and carbon The use of aluminum oxide and carbon black, to which no black is adsorbed, brings about features that would be unimaginable. The reason for using carbon black with an average particle size of 100 mμ or less and a specific surface area of 30 m 2 /g or more is that the squareness ratio and color S/N differ slightly depending on the carbon black to be adsorbed. If the particle size is too large, the tape surface will become rough and the color S/N will tend to decrease. Conversely, if the specific surface area of carbon black is too small, the adsorption to aluminum oxide will be low. , dispersibility, and squareness ratio tend to decrease, and carbon black has an average particle size of 100 mμ or less and a specific surface area of 30 mμ.
This is because it is particularly preferable that the ratio is m 2 /g or more. As described above, the magnetic recording medium according to the present invention has an average grain size of 100 mμ or less and a specific surface area of 30 m 2 /
Since the magnetic powder contains approximately 0.5% by weight or more of carbon black adsorbed on aluminum oxide powder, the magnetic layer has high wear resistance and durability, has low regenerative demagnetization, and has no static charge. It is highly effective in preventing dirt and dust from adhering to it, has excellent runnability, and has excellent light-shielding properties, preventing the tape end detection mechanism using optical sensors from malfunctioning, and has particularly improved these characteristics. The additives added for this purpose are effective even in small amounts, and therefore the packing density of the magnetic powder can be relatively large, the electromagnetic conversion characteristics are good, and the squareness ratio is also large. It has the following features.
第１図〜第４図は、磁気記録媒体の角型比、光
透過率、再生減磁及びカラーＳ／Ｎの特性を示す
グラフである。
1 to 4 are graphs showing the squareness ratio, light transmittance, reproduction demagnetization, and color S/N characteristics of a magnetic recording medium.
Claims (1)
30m2／ｇ以上のカーボンブラツクを酸化アルミニ
ウム粉末に吸着させたものを磁性粉末に対して約
0.5重量％以上含むことを特徴とする磁気記録媒
体。1 In the magnetic layer, the average particle size is 100 mμ or less and the specific surface area is
Carbon black of 30m 2 /g or more is adsorbed on aluminum oxide powder, and the magnetic powder
A magnetic recording medium characterized by containing 0.5% by weight or more.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57137892A JPS5930238A (en) | 1982-08-10 | 1982-08-10 | Magnetic recording medium |
| US06/521,577 US4595631A (en) | 1982-08-10 | 1983-08-09 | Magnetic recording media comprising carbon black-adsorbed metal oxide particles in a magnetic recording layer |
| DE3328719A DE3328719C2 (en) | 1982-08-10 | 1983-08-09 | Magnetic recording material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57137892A JPS5930238A (en) | 1982-08-10 | 1982-08-10 | Magnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5930238A JPS5930238A (en) | 1984-02-17 |
| JPH039530B2 true JPH039530B2 (en) | 1991-02-08 |
Family
ID=15209110
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57137892A Granted JPS5930238A (en) | 1982-08-10 | 1982-08-10 | Magnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5930238A (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5218561B2 (en) * | 1973-06-29 | 1977-05-23 | ||
| JPS5724026A (en) * | 1980-07-16 | 1982-02-08 | Tdk Corp | Magnetic recording medium |
| JPS5724027A (en) * | 1980-07-16 | 1982-02-08 | Tdk Corp | Magnetic recording medium |
-
1982
- 1982-08-10 JP JP57137892A patent/JPS5930238A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5930238A (en) | 1984-02-17 |
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