JPS59207029A - Magnetic recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium suitable for high-density recording by vertical magnetic recording by forming an anodic oxide film having many micropores on the surface of Al or an Al alloy and by filling a magnetic body into the micropores. CONSTITUTION:A magnetic body is filled into micropores of 400-1,000Angstrom diameter in an anodic oxide film formed on the surface of Al or an Al alloy to manufacture a magnetic recording medium. Anodic oxidation is carried out by a conventional method. The anodically oxidized Al or Al alloy is immersed in a mixed soln. contg. 1-30wt% sulfamic acid and 0.1-1wt% phosphoric acid at 10-50 deg.C for 5-30min while stirring the soln. to expand uniformly the micropores in the anodic oxide film to 400-1,000Angstrom from the top to the bottom. The magnetic body is filled into the micropores by carrying out electrolysis in an aqueous soln. contg. a salt of a metal as the magnetic body. At this time, peaks in the electric current at the positive and negative sides are adjusted to 0.2-0.5, and a peak in the current density at the negative side is adjusted to 0.5-4A/dm<2> to increase the filling rate of the magnetic body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a perpendicular magnetic recording medium in which the fine pores of an anodic oxide film of aluminum or an aluminum alloy are filled with a magnetic material, and a method for manufacturing the same. By setting it to 1000X, the coercive force H
c is set to 10,000e or less, and the fine pores of the anodic oxide film are enlarged to the above-mentioned pore diameter by immersing the film in a mixed solution of sulfamic acid and phosphoric acid after the anodizing treatment.

In recent years, perpendicular magnetic recording methods, in which magnetic recording is performed by magnetizing a magnetic recording medium in a direction perpendicular to its film surface, have attracted attention because of its ability to perform high-density recording. As a method of manufacturing such perpendicular magnetic recording media, as shown in Japanese Patent Publication No. 51-21562, etc., conventionally, an anodic oxidation treatment is applied to aluminum oxide or an aluminum alloy to remove fine particles of the anodic oxide film. A method has been proposed in which the holes are filled with magnetic material. However, the anodic oxide film obtained by conventional methods has a micropore diameter of 100X to 200X at most.
The perpendicular magnetic recording material obtained by filling the microscopic pores with magnetic material has a high coercive force (coercive force) of about 10,000 e or more in the direction perpendicular to the film surface, and is therefore suitable for high-density recording. When recording or erasing with a narrow gear knob head, the tip of the head becomes magnetic! There was a problem in that @sum occurred, making high-density recording difficult in practice. In addition, 1000 pores obtained by precipitating the alloy into such small pores of 111
In a magnetic recording material with a coercive force of 0e or less, even if its easy magnetization direction is parallel to the film surface or has anisotropy in a perpendicular direction, the residual magnetization is less than 300G, and reproduction is sufficient. Therefore, it was not suitable for use as a perpendicular magnetic recording material for high-density recording and edge strips.

By the way, as a method of enlarging the micropores of the anodic oxide film,
Conventionally, a method has been proposed in Japanese Patent Publication No. 56-23207 in which aluminum or aluminum alloy, on which an anodic oxide film has been formed, is re-anodized using a phosphoric acid solution. Disadvantages include the fact that the anodic oxide skin becomes fragile, or that only the diameter of the upper part of the micropores is enlarged, but not the bottom, so that when the micropores are filled with magnetic material, the direction of easy magnetization becomes horizontal. was there.

In order to solve the above-mentioned problems, the inventors of the present invention have conducted various studies on the appropriate pore size of the microscopic pores of the anodized skin, and have determined that the pore size is within the range of 400 to 1,000×. By doing so, the coercive force increases from 200 to 10' OOO
(e) A magnetic recording medium with an easy magnetization direction perpendicular to the surface of the image is obtained, and a mixed solution of sulfamic acid and phosphoric acid with weak chemical dissolving power is used as a micropore expansion treatment after anodizing aluminum or aluminum alloy. By performing the immersion treatment in the anodic oxide film, the anodic oxide film is coated almost uniformly from the top to the bottom with an impurity of 400 to ioO without weakening the anodic oxide film.

It was discovered that an anodized film having ridges and pores with a pore diameter of X can be obtained, and this invention was completed.

Therefore, it is an object of the present invention to provide a magnetic recording medium suitable for high-density recording using perpendicular magnetic recording, which has a coercive force of 10,000 e or less and has an easy magnetization direction perpendicular to the film surface, and has excellent magnetic properties, and a method for manufacturing the same. This is the purpose. The magnetic recording medium of the first invention has an anodic oxide film formed on the surface of aluminum or an aluminum alloy with a large number of 12 holes having a diameter within the range of 4oo-1oooX, and whose +i! 1. The number of hours t is defined as the fact that the magnetic material is filled in the A-hole, and the method for producing a magnetic recording medium of the second invention is characterized in that the magnetic recording medium is filled in the A-hole.
Or, by performing a single-body awakening process on aluminum alloy,
Then, after performing a immersion treatment in a mixed solution consisting of sulfamic acid and phosphoric acid, the immeric material is filled into the imitative Akata holes of the anodic oxide film.

This invention will now be described in more detail.

In the magnetic recording medium of the first invention, as described above, the micropores of the anodic oxide film of aluminum or aluminum alloy have a diameter of 400 to 1000X, and the micropores are filled with a magnetic material. If the diameter of the pores a is less than 400X, the problem explained in the conventional example described above cannot be solved, and the coercive force becomes 1.
000 Oe or more. On the other hand, if the distance exceeds too long, the area occupied by the focus on the recording medium increases and the axis of easy magnetization tilts in the horizontal direction, which is disadvantageous for high-density recording. By setting the diameter of the micropores to 400 to 100OX, the perpendicular magnetic recording method can be used. ; %'a degree recording becomes possible in actual recording.

As mentioned above, the pore diameter of the anodic oxide film micropores is 400 to 10.
In order to expand to 0OX, it is necessary to generate an anodized film with many micropores on the surface of the aluminum alloy by anodizing treatment, and then immerse it in a mixed solution consisting of sulfamino acid and phosphoric acid. There is.

Here, the first stage of anodizing treatment may be carried out according to a conventional method, for example, using an aqueous solution of an inorganic acid such as sulfuric acid or chromic acid, or an organic acid such as shiulic acid with a commercial weight of 1 to 30, and a liquid temperature of 5.
The electrolysis may be carried out at -50 DEG C. using a direct current or AC/DC superimposed voltage of 10 to 100 V for electrolysis, while stirring the liquid by air stirring or liquid circulation.

On the other hand, the dipping treatment is only for enlarging the micropores of the anodic oxide film.
In a mixed liquid containing 1 to 1 weight 14%, the liquid temperature is 10 to 5.
It is desirable to immerse the aluminum or aluminum alloy after anodizing treatment at 0° C. for 5 to 30 minutes while stirring the p-liquid by air stirring or liquid circulation. If the phosphoric acid concentration in the mixed solution used for this immersion treatment exceeds 1% by weight, only the upper part of the micropores tends to be enlarged;
If it is less than sewing, the processing time will be longer, so as mentioned above, it is desirable to keep the phosphoric acid concentration within the range of 0.1 to 1% by weight.In addition, sulfamino acid acts as a stabilizer for the liquid and reduces the pore size. However, if it is less than 1% by weight, the effect is small, and if it exceeds 30% by weight, the effect of adding sulfamino acid will be saturated and it will be disadvantageous in terms of cost. Furthermore, it is desirable that the pore size be within the range of 1 to 30 mm.By immersion treatment using such a mixed solution, the micropores will have a uniform pore diameter of 400 to 1 ooo3 from the bottom to the top. In this case, the 1-polar oxide film is effectively prevented from becoming brittle.

After applying the immersion treatment to expand the micropores as described above,
The micropores are filled with a magnetic material. A common method for this filling is to carry out AC electrolytic deposition in an aqueous solution containing a salt of a magnetic metal such as nickel, cobalt or iron, as proposed in Japanese Patent Publication No. 51-15597. , the present inventors particularly used asymmetric alternating current for electrolysis,
It has been found that by setting the ratio of the 89iIllI peak current to the θ side peak current and the e side peak current density within specific ranges, it is possible to significantly increase the filling rate of the magnetic material into the pores compared to the conventional method. Ta. This higher filling rate of magnetic material means that when used as a magnetic recording medium, the saturation magnetic flux density and residual magnetic flux density become thicker9, which contributes to higher recording density and improved SIN ratio. . The present inventors introduced Fe into the micropores of the anodic oxide film by varying the current conditions.
, conducted an experiment in which Co or Ni was electrolytically deposited, and the saturation magnetic flux density B was obtained.

The results of the investigation are shown in Figure 11d and Figure 2. However, in Figure 1, the ■ side peak 91, the current density A0, and the θ side peak current density A
When the ratio A+/A- is constant at 0.3 and the e-side peak current density A- is changed, the saturation magnetic flux density BS at each value is the maximum of the data of those saturation magnetic flux densities. value BS
It is expressed as a ratio value (Bs/Bsmax) to maX. Figure 2 also shows each A+/A when the e-side peak current density A- is constant at 08 A/dm2 and the value of A+/A- is changed.
The value of the saturation magnetic flux density B5 at - value is set to BS/
BS nla X to grow. Note that Fe, Co,
Alternatively, for electrolytic deposition of Ni, use either ammonium iron sulfate, cobalt sulfate, or nickel sulfate at 50 PA.
An mT:M solution containing 30 ml of boric acid and 2 f/lj of glycerin was used. As is clear from Figures 1 and 2, the peak current 1 on the θ side with respect to the other electrodes is 0.5 to 4 A/dm2, and the peak current A+ of the singing beak is 115 to 1 of the e1 law peak current -. It has been found that the saturation magnetic flux density is high in the range of /2, and that the magnetic filling rate is high when these ranges are satisfied.

Therefore, in carrying out the method of the second invention,
e Measured peak current density is A-1e side peak current density is A+
Binding, A- is 0.5 to 4 A/dm2, A, /A- is 0
．． It is desirable to fill the micropores with the magnetic material by electrolytic deposition using an asymmetrical alternating current within the range of 2 to 0.5. A
If the value of - and the ratio of A+/A- are out of the above range, the magnetic material filling factor will increase, the saturation magnetic flux density and residual magnetic flux density will become low, and the recording S/'N ratio etc. will deteriorate. There is a risk.

Examples of the present invention will be described below.

Example A thin aluminum plate with a purity of 99.99 and a thickness of 95 μm was used as the substrate.The substrate was subjected to an anodic dispersion treatment with a 3% by weight aqueous solution of 7-euric acid, and then treated with 5% by weight of sulfamine and phosphorus. Soaking a containing 0.8% by weight of acid
It was immersed in a liquid. By changing the soaking time in the soaking process, the acupuncture hole diameter can be adjusted to 1! It became history.

Furthermore, as a magnetic substance filling treatment, ferrous ammonium 50 f7'lJ was added in the first step.

Due to the electrolysis containing 1130' Jill, Glycerin 2971), differentiation using -C asymmetric parentheses deposits Ij'c in the mountain pores. The peak current density is 0.3 Vd+n.
It was held constant. In addition, in the process of city analysis, IT-responsible resident gold,]
4 gradually precipitates from the bottom of the hole toward the surface, and when the hole is filled, the surface of the film shows a positive, land-change-reverse-torsional, and 11-degree swamp, but the magnetic metal is deposited from the imitative KIll hole. If it overflows and precipitates on the surface (and twists, the gloss will be lost and the surface of Table 1 will take on a white tinge. Therefore, in each example, the holes i and +11 were completely filled with one magnetic wire). After confirming this with the first eye, we cut off the 4th screen to '.After filling the fine pores V'C with Fe in this way, it appeared on the film surface and the retention effect in the vertical and horizontal directions. Power Elc and Towa 1fBr, -11℃
Find out the sum of magnetic flux 'd degrees BS between the straight and quadrilateral directions. The names of these 31 Yoshirai and each treatment condition are shown in Table 1.

In the magnetic material filling process, cobalt sulfate 50f/13
, 30 P/11 of porosity, and 2 vi of glycerin were used to precipitate the outside of the point plate in the Cof micropores in substantially the same manner as in Examples 1 to 10.

The results and each condition are also shown in Table 1.

Examples 16 to 20 In the magnetic material filling process, Ni was precipitated into micropores using an electrolytic solution containing nickel sulfate 509/hahout (230V/131 glycerin 2'!-/l) except for μ. The experiments were carried out in substantially the same manner as in Examples 1 to 10. The results and conditions are also shown in Table 1.

For Examples 1 to 20 shown in Table 1, the relationship between the micropore diameter, vertical coercive force Hc, and vertical residual magnetic flux density Br after immersion treatment is shown in FIGS. 3 and 4. Figures 3 and 4
As shown in the figure, the vertical coercive force and residual magnetic flux density vary depending on the type of magnetic metal filled, but generally change smoothly as the hole diameter increases. 200 to 10 with a pore diameter of 1000
It is clear that a value of 000e is obtained.

Example 21 The procedure was the same as in Example 2, except that the immersion treatment liquid contained 5% by weight of sulfur amino acid and 3% by weight of phosphoric acid, and the electrolytic deposition time of the magnetic material filling treatment was different. Processed. The results and each condition are shown in Table 2.

In the case of Example 21, since the phosphoric acid concentration of the dipping treatment solution was high, roughness was noticeable on the surface of the film, and the film formed by the anodic oxidation treatment also became thinner due to the dipping treatment.

Furthermore, as a result of the relatively enlarged upper part of the hole, the horizontal magnetization component increased and the vertical residual magnetic flux density Br decreased.

In addition, in each of the other Examples, almost no change in film thickness was observed before and after the immersion treatment.

Example 22 Processing was carried out in the same manner as in Example 2, except that in the electrolytic deposition of the magnetic material filling treatment after the immersion treatment, asymmetrical AC was not used, but a normal symmetrical AC of 12 V was used. The results and each condition are also shown in Table 2.

In the case of Example 22, the saturation magnetic flux density was reduced to about 60% compared to Example 2, although the pre-processes up to the electrolytic deposition step were the same as in Example 2. From this, it is clear that the use of asymmetrical alternating current allows the fine pores to be more densely filled with the invasive material than the electrolytic deposition using normal alternating current.

Example 23 The treatment was carried out in the same manner as in Example 2 except that the immersion treatment liquid contained sulfamic acid (15% by weight and 0.8% by weight of phosphoric acid). It is also shown in the table.

In the case of Example 23, the concentration of sulfamic acid in the immersion treatment liquid was low, and the vertical residual magnetic flux density Br was lower than in Example 2.

Table 2, Examples 24 to 28 The composition of the immersion treatment solution was such that the concentration of sulfamic acid was constant at 5% by weight, and the acid concentration was varied within the range of 0.1 to 5% by weight. In addition, the immersion treatment time is
Adjusted so that it takes about a long time. Other conditions, such as the composition of the electrolytic solution in the magnetic material filling process, are the same as in Examples 16-20. The results and conditions are shown in Table 3, and the relationship between the phosphoric acid concentration of the immersion treatment solution, the vertical residual magnetic flux density, the horizontal residual magnetic flux density, and the vertical squareness ratio is shown in FIG.

It is clear from FIG. 5 that when the phosphoric acid concentration is 01 to 1% by weight, the vertical remanence is high and the squareness ratio is close to 1.

Examples 29 to 33 The composition of the immersion treatment solution was such that the phosphoric acid concentration was kept constant at 0.8% by weight, and the sulfamino acid concentration was varied in the range of 0 to 30% by weight. The immersion treatment time was adjusted so that the diameter of the micropores was approximately 500 mm. Other conditions, such as the composition of the electrolytic solution for magnetic material filling treatment, are in Examples 16 to 2.
Same as 0.

The results and conditions are also shown in Table 3, and the relationship between the sulfamino acid concentration of the α-soaking solution, the vertical and horizontal residual waste densities, and the squareness ratio is shown in FIG.

From Figure 6, when sulfamino acid is not added (concentration 0
When 1 to 30% by weight of sul-7 amino acids were added, the vertical residual magnetic flux density was higher and the squareness ratio was 1.
It is clear that it is close to .

As is clear from the above description, in the magnetic recording medium of the first invention, the -f1 diameter of the anodic oxide film filled with the magnetic material is 400 mm.
~1000X, the coercive force is 10000
e~2000Q and has an easy direction of magnetization perpendicular to the film surface. Therefore, according to the magnetic recording medium of the first invention, high-density recording using the perpendicular magnetic recording method can practically achieve 0T performance. Become. In addition, according to the manufacturing method of the second invention, it is possible to uniformly expand the micropores from the bottom to the top to the above-mentioned pore diameter, and the anodic oxide film is not weakened, resulting in excellent properties as described above. A medium for vertical aeration recording can be manufactured industrially.

[Brief explanation of drawings]

Figure 1 is a graph showing the change in the saturation magnetic flux density of the product medium when the e 1t (11 peak current density) of the asymmetric alternating current used for electrolytic deposition of a magnetic substance-filled reservoir is changed. Similarly, FIG. 3 is a graph showing the change in saturation magnetic flux density when the ratio A+/A- of the e-side peak current density A+ and the θ-side peak current density A- of the asymmetrical alternating current is changed. A graph showing the relationship between the micropore diameter and the vertical coercive force HC of the product medium in No. 20.
A graph showing the relationship between the micropore diameter and the vertical residual magnetic flux density Br of the product medium in Examples 24 to 20, and FIG. FIG. 6 is a graph showing the relationship between the sulfamine g concentration of the immersion treatment mixture and the magnetic properties of the product medium in Examples 29 to 33. Applicant Nippon Musical Instruments Manufacturing Co., Ltd. Agent Patent Attorney Yutaka 1) Takehisa (and 1 other person) Procedural amendment (method) 1. Display of the case 1981 Patent Application No. 81458 2 Name of the invention Magnetic recording media and its manufacturing method 3 Person making the amendment Relationship to the case Patent applicant Address 10-1 Nakazawa-cho, Hamamatsu City, Shizuoka Prefecture Name
(407) Nippon Gakki Mfg. Co., Ltd. 4, Agent address: 3-4-18-5, Mita, Minato-ku, Tokyo, Date of amendment order: August 30, 1980 (shipment date) 6. Drawings subject to amendment 7. Contents of correction

Claims (4)

[Claims] (1) 7iv minium or aluminum alloy 4i
[A magnetic recording medium in which an anodic oxide film having a large number of micropores with a diameter within the range of 400 to 1.000 K is formed on the surface, and the micropores are filled with a magnetic material. (2) 7# minium or aluminum alloy is anodized, then immersed in a mixture of sulfamino acid and phosphoric acid, and then the fine pores of the anodic oxide film are filled with magnetic material. Manufacturing method for magnetic recording media. (3) The production method according to claim 2, wherein the mixed solution used for the immersion treatment contains 1 to 30 Sk% by weight of sulfur amino acids and 01 to 1% by weight of phosphoric acid. (4) In filling the micropores with the AiJ-recording material, asymmetrical alternating current is used, and the ratio A/A of the peak current density A+ on the ■ side and the peak current density A- on the e side of the asymmetrical alternating current.
-wo 0.2-0.5 range IJ'i4, e 1111
I Heater? M flow 'M degree 8 value 0.5~4A/d
The manufacturing method according to claim 2, wherein the magnetic metal is electrolytically deposited under conditions within the range of m.