JPH0221049B2 - - Google Patents
Info
- Publication number
- JPH0221049B2 JPH0221049B2 JP967481A JP967481A JPH0221049B2 JP H0221049 B2 JPH0221049 B2 JP H0221049B2 JP 967481 A JP967481 A JP 967481A JP 967481 A JP967481 A JP 967481A JP H0221049 B2 JPH0221049 B2 JP H0221049B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- magnetic
- substrate
- orientation
- coating film
- 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
Links
- 238000000576 coating method Methods 0.000 claims description 22
- 239000011248 coating agent Substances 0.000 claims description 21
- 239000000758 substrate Substances 0.000 claims description 18
- 239000010419 fine particle Substances 0.000 claims description 15
- 239000003973 paint Substances 0.000 claims description 14
- 230000005415 magnetization Effects 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 239000006249 magnetic particle Substances 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 230000003746 surface roughness Effects 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000004220 aggregation Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 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 2
- 239000000843 powder Substances 0.000 description 2
- 238000007788 roughening Methods 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 159000000009 barium salts Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 150000001868 cobalt Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000002505 iron Chemical class 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 239000006247 magnetic powder Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 150000003608 titanium Chemical class 0.000 description 1
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
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/852—Orientation in a magnetic field
Landscapes
- Manufacturing Of Magnetic Record Carriers (AREA)
Description
本発明は、垂直磁気記録媒体を製造方法および
これに用いられる磁場配向装置に係り、特に高い
配向率と表面平滑さを有した記録媒体を製造し得
る様にした垂直磁気記録媒体製造用磁場配向に関
する。
磁気記録は一般に記録媒体の面内長手方向の磁
化を用いる方式によつている。しかしこの面内長
手方向の磁化を用いる記録方式にあつては、記録
の高密度化を図ろうとすると、記録媒体内の減磁
界が増加するため、記録密度をそれ程向上させる
ことはできない。
そこで、この様な不具合を解消するために近
年、記録媒体の表面と垂直な方向の磁化を用いる
垂直磁気記録方式が提案されている。この垂直磁
気記録方式では記録密度が高まる程、記録媒体中
の減磁界が減少するので本質的に高密度記録に適
した記録方式と云える。
しかしてこの様な垂直磁気記録方式を採用する
には表面とは垂直な方向に磁化容易軸を有する磁
気記録媒体を必要とする。この様な要望を満す記
録媒体として、従来記録膜をCo−Crスパツタ膜
で形成するものや記録膜を磁性微粒子の塗布層で
形成するものが提案されている。
ところで、記録膜を磁性微粒子の塗布層で形成
するものにあつては次の様な製造方法が考えられ
る。すなわち、磁性微粒子として、たとえば
BaFe12O19等の六方晶系フエライトを用いる。六
方晶系フエライトを用いる理由はこのフエライト
は平板状を成しており、しかも、磁化容易軸か板
面に垂直であるため、磁場配向処理もしくは機械
的処理によつて容易に垂直配向を行ない得るから
である。この様な六方晶系フエライトの磁性微粒
子とバインダとを混合し、これを非磁性テープの
表面に塗布後この塗布層を磁場中にその表面が磁
界の方向と直交するように配置することによつて
各磁性微粒子の磁化容易軸を磁界の方向に一致さ
せて配列させた後塗料を乾燥させれば垂直磁気記
録に適した記録媒体を得ることができる。
しかし上述したいわゆる塗布法によつて垂直磁
気記録媒体を製造する場合には次の様な点を考慮
する必要がある。すなわち、従来の面内磁気記録
方式に比べて垂直磁気記録方式の利点を有するた
めには記録最小単位をサブミクロンのオーダにす
る必要がありそのためにはサブミクロン以下の磁
性微粒子を用いる必要がある。この様な微小寸法
の磁性微粒子は単磁区構造、すなわち微小な磁石
となるため互いに磁気的に結合し易い。したがつ
てバインダ内で均一に分散するよう注意を払う必
要がある。
また、均一な分散がなされた所望の磁性塗料が
得られた場合であつても、この様な磁性塗料を基
体上に塗布して磁場配向装置によつて垂直配向さ
せる場合に於いて下記の如き現象が往々にして起
こり易い。すなわちNS極を対向配置させた磁場
配向器の磁極間に磁性塗料を塗布した基体をその
表面が磁界と直交する様に配置すると、塗料中の
磁性微粒子は磁化容易軸が磁界の方向と一致する
様に回転配向する。この様に配向させた後、磁場
の印加を停止するかあるいは基体を磁場外へその
まま取り出すと、塗膜の両面に残留する磁極のた
めに上記配向磁場の磁界の方向とは反対方向に反
磁場が生じこの反磁場の磁界の方向と角度をなす
磁性微粒子が面内方向にトルクを受け、この結果
磁場配向器によつて得られた垂直配向が著しく阻
害されたものとなる。また塗布された基体を磁場
配向装置内で乾燥する様にした場合は、磁性微粒
の垂直配向は確保されるが、磁界の方向と一致す
る様に回転して配向した微粒子は次には塗膜表面
の静磁エネルギを減らすよう塗料粒子の移動（磁
気的面荒れ）が起こり、磁性塗布膜の表面が著し
く荒れる。
垂直磁気記録媒体の記録特性は塗布中の磁性微
粒子の磁化容易軸が媒体表面に対して垂直に位置
しているものの比率（配向率）と記録媒体表面の
平滑さに密接に関係し配向率が高く表面が平滑な
程、高い再生出力と高密度記録が可能となる。こ
の様なことから配向工程時に於いて、高配向率と
磁気凝集のない媒体が得られる磁場配向装置の出
現が強く望まれているのが実情である。
本発明はこの様な事情に鑑みてなされたもの
で、その目的とするところは磁気的面荒れがなく
高配向率を有した記録媒体を製造し得る垂直磁気
記録媒体製造用磁場配向装置を提供することにあ
る。
すなわち、本発明は、基体に磁性粒子を含む塗
料を塗布して、塗膜を形成した後、上記塗膜に対
し磁界を印加して上記磁性微粒子を配向させるに
あたり、磁場強度に勾配を持たせた垂直磁界を形
成し、この磁場で磁性粒子を配向することによ
り、塗膜表面が平滑でかつ高い配向性を有する磁
気記録媒体を得ることを特徴とするものである。
配向磁場を印加する際、塗膜は常温で配向しても
良いが、磁界中で塗膜形成基体を支持する支持板
を加熱しておいても良い。支持板を加熱しておけ
ば、塗膜の粘度が高粘度となり、磁界印加による
磁気凝集を防止することができるため、表面平滑
性に対する配向磁界の影響を低減することができ
る。
以下本発明を具体的に説明する。
本発明に於いて使用される磁性微粒子はバリウ
ムフエライトなどの六方晶フエライトにイオン置
換を行なつて保磁力を制御したもの（高密度記録
を目的として粒径は0.3μｍ以下が望ましい）のほ
か、一軸異方性を有する各種磁性微粒子である。
そしてこのような磁性微粒子粉を分散剤、溶剤、
バインダおよびその他の添加剤と共に分散混練し
て磁性塗料を作製しこの塗料を用いて次の磁場配
向装置を利用して垂直磁化記録媒体を製造する。
すなわち、第１図に示す様に供給リール１に巻
き取られている基体、つまり非磁性テープ２を巻
き戻し、これを案内ロール３を介してロール４，
５，６，７からなるコーターヘツドを通過させ、
このコーターヘツドで基体２の一表面に磁性塗料
８を塗布し、基体２上に平担な塗膜を形成させ
る。この様に一表面に塗膜が形成された基体９を
案内ロール１０，１１を介して加熱可能な支持板
１２上を走行する。ここで磁界勾配のある磁場配
向装置１３の磁界内通過させた後、乾燥装置１４
によつて塗膜を乾燥させる。この様な経過をへて
垂直磁気記録媒体を製造すると基体２の表面に塗
布された（基体９）塗膜中の磁性微粒子は低磁場
から高磁場へ移ると比例して配向する。
この様な配向経過をたどらせると、磁場勾配の
ない垂直配向磁石１５で直接配向させた場合にく
らべて磁性微粒子の配向率と塗膜の表面性とが向
上することが確認された。
次に、このような本発明装置を使つて垂直磁気
記録媒体を製造した実施例を説明する。
まず、バリウム塩、鉄塩、コバルト塩、チタン
塩を含む水溶液にアルカリを滴下し、共沈物を得
た後、アルカリ除去を行ない加熱してCo−Ti置
換えのバリウムフエライト微粒子を得た。これら
は結晶粒径0.1μｍ以下で板状性をもち、又この紛
体の磁気特性は飽和磁化60（emu／ｇ）、抗磁力
1000（Oe）であつた。次に表−１の組成の磁性塗
料を作製してリバースコータにて非磁性テープ上
に塗布したのち、第１図に示した磁場配向装置を
使つて配向させ乾燥を行なつた。
そして、配向用磁石の磁界は図Ａ点で1000Oe，
Ｂ点で4000Oe（それぞれ一定）となるよう、磁界
勾配を持たせ、この状態で支持板の温度を変化さ
せた場合の塗膜の垂直配向率（反磁界補正した残
留磁化Mr／Msで評価した値）、および表面性
（指
The present invention relates to a method of manufacturing a perpendicular magnetic recording medium and a magnetic field orientation device used therein, and particularly relates to a magnetic field orientation device for manufacturing a perpendicular magnetic recording medium that enables the manufacture of a recording medium with a particularly high orientation rate and surface smoothness. Regarding. Magnetic recording generally relies on a system that uses magnetization in the in-plane longitudinal direction of a recording medium. However, with this recording method that uses magnetization in the in-plane longitudinal direction, if an attempt is made to increase the recording density, the demagnetizing field within the recording medium will increase, so the recording density cannot be improved that much. In order to solve this problem, a perpendicular magnetic recording system has recently been proposed that uses magnetization in a direction perpendicular to the surface of the recording medium. In this perpendicular magnetic recording system, the demagnetizing field in the recording medium decreases as the recording density increases, so it can be said to be a recording system that is essentially suitable for high-density recording. However, in order to employ such a perpendicular magnetic recording method, a magnetic recording medium having an axis of easy magnetization in a direction perpendicular to the surface is required. As recording media that meet these demands, there have been proposed conventional recording media in which the recording film is formed of a Co--Cr sputtered film and in which the recording film is formed by a coated layer of magnetic fine particles. By the way, in the case where the recording film is formed by a coating layer of magnetic fine particles, the following manufacturing method can be considered. That is, as magnetic fine particles, for example
A hexagonal ferrite such as BaFe 12 O 19 is used. The reason for using hexagonal ferrite is that this ferrite has a flat plate shape, and its axis of easy magnetization is perpendicular to the plate surface, so it can be easily vertically aligned by magnetic field alignment treatment or mechanical treatment. It is from. By mixing such magnetic fine particles of hexagonal ferrite with a binder, coating the mixture on the surface of a non-magnetic tape, and then placing this coated layer in a magnetic field so that the surface is perpendicular to the direction of the magnetic field. A recording medium suitable for perpendicular magnetic recording can be obtained by arranging the easy magnetization axes of the magnetic particles so as to coincide with the direction of the magnetic field and then drying the paint. However, when manufacturing perpendicular magnetic recording media by the above-mentioned so-called coating method, the following points need to be taken into consideration. In other words, in order to have the advantages of perpendicular magnetic recording over conventional longitudinal magnetic recording, the minimum recording unit must be on the order of submicrons, and for this purpose it is necessary to use submicron or smaller magnetic particles. . Such minute magnetic particles have a single-domain structure, that is, form minute magnets, and therefore are easily magnetically coupled to each other. Therefore, care must be taken to ensure uniform dispersion within the binder. In addition, even if a desired magnetic paint with uniform dispersion is obtained, when applying such a magnetic paint onto a substrate and vertically aligning it using a magnetic field orientation device, the following problems occur. Phenomena often occur. In other words, if a substrate coated with magnetic paint is placed between the magnetic poles of a magnetic field orientator with NS poles facing each other so that its surface is perpendicular to the magnetic field, the axis of easy magnetization of the magnetic particles in the paint will match the direction of the magnetic field. rotationally oriented. After being oriented in this way, when the application of the magnetic field is stopped or the substrate is taken out of the magnetic field, a demagnetizing field is generated in the opposite direction to the direction of the magnetic field of the above-mentioned orienting magnetic field due to the magnetic poles remaining on both sides of the coating film. occurs, and the magnetic fine particles forming an angle with the direction of the magnetic field of this demagnetizing field are subjected to a torque in the in-plane direction, and as a result, the vertical orientation obtained by the magnetic field orientator is significantly inhibited. Furthermore, if the coated substrate is dried in a magnetic field orientation device, the vertical orientation of the magnetic fine particles is ensured, but the fine particles rotated and oriented to match the direction of the magnetic field are then dried in the coating film. Movement of paint particles (magnetic surface roughening) occurs to reduce the static magnetic energy on the surface, and the surface of the magnetic coating film becomes extremely rough. The recording characteristics of perpendicular magnetic recording media are closely related to the ratio of the easy magnetization axes of the magnetic particles being coated perpendicular to the medium surface (orientation rate) and the smoothness of the recording medium surface. The higher the height and the smoother the surface, the higher the reproduction output and the higher density recording possible. For these reasons, there is a strong desire for a magnetic field orientation device that can provide a medium with a high orientation rate and no magnetic aggregation during the orientation process. The present invention has been made in view of the above circumstances, and its purpose is to provide a magnetic field orientation apparatus for manufacturing perpendicular magnetic recording media that can manufacture recording media with high orientation ratio without magnetic surface roughening. It's about doing. That is, the present invention applies a paint containing magnetic particles to a substrate to form a paint film, and then applies a magnetic field to the paint film to orient the magnetic fine particles by creating a gradient in the magnetic field strength. By forming a perpendicular magnetic field and orienting the magnetic particles with this magnetic field, a magnetic recording medium having a smooth coating surface and high orientation can be obtained.
When applying the orientation magnetic field, the coating film may be oriented at room temperature, but the support plate that supports the coating film formation substrate may also be heated in the magnetic field. If the support plate is heated, the viscosity of the coating film becomes high and magnetic aggregation due to the application of a magnetic field can be prevented, so that the influence of the orienting magnetic field on the surface smoothness can be reduced. The present invention will be specifically explained below. The magnetic fine particles used in the present invention include hexagonal ferrite such as barium ferrite with ion substitution to control the coercive force (the particle size is preferably 0.3 μm or less for the purpose of high-density recording), and These are various magnetic fine particles that have uniaxial anisotropy.
Then, such magnetic fine particle powder is mixed with a dispersant, a solvent,
A magnetic coating material is prepared by dispersing and kneading it together with a binder and other additives, and this coating material is used to manufacture a perpendicular magnetization recording medium using the following magnetic field orientation device. That is, as shown in FIG.
Pass through a coater head consisting of 5, 6, 7,
The coater head applies the magnetic paint 8 to one surface of the substrate 2 to form a flat coating film on the substrate 2. The substrate 9 with a coating film formed on one surface in this manner is run on a heatable support plate 12 via guide rolls 10 and 11. Here, after passing through the magnetic field of the magnetic field orientation device 13 with a magnetic field gradient, the drying device 14
Dry the coating film. When a perpendicular magnetic recording medium is produced through this process, the magnetic fine particles in the coating film applied to the surface of the substrate 2 (substrate 9) become oriented proportionally as the magnetic field changes from a low magnetic field to a high magnetic field. It has been confirmed that when such an orientation process is followed, the orientation rate of the magnetic fine particles and the surface properties of the coating film are improved compared to the case where the orientation is directly performed using the vertically oriented magnet 15 without a magnetic field gradient. Next, an example in which a perpendicular magnetic recording medium was manufactured using such an apparatus of the present invention will be described. First, an alkali was dropped into an aqueous solution containing a barium salt, an iron salt, a cobalt salt, and a titanium salt to obtain a coprecipitate, and then the alkali was removed and heated to obtain Co-Ti-substituted barium ferrite fine particles. These particles have a crystal grain size of 0.1 μm or less and have plate-like properties, and the magnetic properties of this powder are a saturation magnetization of 60 (emu/g) and a coercive force.
It was 1000 (Oe). Next, a magnetic paint having the composition shown in Table 1 was prepared and coated on a non-magnetic tape using a reverse coater, and then oriented using the magnetic field orientation device shown in FIG. 1 and dried. The magnetic field of the orientation magnet is 1000Oe at point A in the figure.
The perpendicular orientation rate of the coating film when the temperature of the support plate is changed in this state by creating a magnetic field gradient so that it is 4000 Oe (each constant) at point B (evaluated by the residual magnetization Mr/Ms corrected by the demagnetizing field) value), and superficiality (finger
【表】
針型表面粗さ計による表面粗度）を測定した結果
第３図に示す結果を得た。
また、同じ塗料を用いて第２図の平担な垂直配
向磁石4000Oeで配向した場合の得られた結果を
比較例として第４図に示した。
第３図から明らかな様に本発明装置によつて得
られた媒体は、支持板の温度依存性があるものの
比較例第４図に比べてその配向率、表面平滑さが
大幅に改善されていることがわかる。
なお、本発明は、他の磁性粉を垂直に配向させ
る場合においても同等の作用効果を奏することは
言うまでもない。[Table] As a result of measuring the surface roughness using a needle type surface roughness meter, the results shown in FIG. 3 were obtained. Further, as a comparative example, the results obtained when the same paint was used and oriented using the flat vertically oriented magnet of 4000 Oe shown in FIG. 2 are shown in FIG. As is clear from FIG. 3, the orientation rate and surface smoothness of the medium obtained by the apparatus of the present invention are significantly improved compared to the comparative example shown in FIG. 4, although there is a temperature dependence of the support plate. I know that there is. It goes without saying that the present invention provides similar effects even when other magnetic powders are oriented vertically.
第１図は本発明の一実施例に係る磁場配向装置
の概略側面図、第２図は比較例を説明するための
図、第３図は本発明装置を使用したときの配向性
および表面粗さの変化を示す図、第４図は、比較
例装置を使用したときの配向性および表面粗さの
変化を示す図である。
２…基体、９…塗料を塗布した基体、１２…支
持板、１３…磁場配向装置、１４…乾燥装置。
Fig. 1 is a schematic side view of a magnetic field orientation device according to an embodiment of the present invention, Fig. 2 is a diagram for explaining a comparative example, and Fig. 3 shows orientation and surface roughness when using the device of the present invention. FIG. 4 is a diagram showing changes in orientation and surface roughness when the comparative example device is used. 2... Substrate, 9... Substrate coated with paint, 12... Support plate, 13... Magnetic field orientation device, 14... Drying device.
Claims (1)
て磁性塗膜を形成した後、該塗膜に磁場を印加し
て磁性微粒子の磁化容易軸を塗膜面に垂直な方向
に配向するようにした垂直磁気記録媒体の製造に
おいて、配向磁場の磁場強度が基体進行方向に従
つて低磁場から高磁場へ変化する磁界強度勾配を
持つように配設された磁場配向装置により磁界を
印加することを特徴とする垂直磁気記録媒体の製
造方法。 ２ 磁界印加を、塗膜を形成した基体の加熱下に
おいて行うことを特徴とする特許請求の範囲第１
項記載の垂直磁気記録媒体の製造方法。 ３ 被処理基体の進行方向に従つて低磁場から高
磁場へ変化する磁界強度勾配を持つ磁界を発生す
る磁場配向装置と、該装置の磁場内に配置された
加熱可能な支持板を具備した垂直磁気記録媒体の
製造装置。[Scope of Claims] 1. After coating a paint containing magnetic fine particles on a substrate to form a magnetic coating film, a magnetic field is applied to the coating film to align the axis of easy magnetization of the magnetic particles perpendicular to the coating surface. In the production of perpendicular magnetic recording media that are oriented in the direction of the substrate, a magnetic field orientation device is used, which is arranged so that the magnetic field strength of the orientation magnetic field has a magnetic field strength gradient that changes from a low magnetic field to a high magnetic field according to the direction of movement of the substrate. A method for manufacturing a perpendicular magnetic recording medium, the method comprising applying a magnetic field. 2. Claim 1, characterized in that the magnetic field is applied while the substrate on which the coating film is formed is heated.
A method for manufacturing a perpendicular magnetic recording medium as described in . 3. A vertical machine comprising a magnetic field orientation device that generates a magnetic field with a magnetic field intensity gradient that changes from a low magnetic field to a high magnetic field according to the direction of movement of the substrate to be processed, and a heatable support plate disposed within the magnetic field of the device. Magnetic recording media manufacturing equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP967481A JPS57127931A (en) | 1981-01-27 | 1981-01-27 | Method and apparatus for manufacture of vertical magnetic recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP967481A JPS57127931A (en) | 1981-01-27 | 1981-01-27 | Method and apparatus for manufacture of vertical magnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57127931A JPS57127931A (en) | 1982-08-09 |
| JPH0221049B2 true JPH0221049B2 (en) | 1990-05-11 |
Family
ID=11726753
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP967481A Granted JPS57127931A (en) | 1981-01-27 | 1981-01-27 | Method and apparatus for manufacture of vertical magnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57127931A (en) |
-
1981
- 1981-01-27 JP JP967481A patent/JPS57127931A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57127931A (en) | 1982-08-09 |
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