JPS58169902A - Preparation of magnetic powder for magnetic recording - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium with excellent abrasion resistance and a high S/N value by a method wherein fine particles of ferrite, c, alpha-Fe2O3 are simultaneously precipitated by heat-treating an amorphous body having a preselected composition and the mixture of the powder is used. CONSTITUTION:By heat-treating an amorphous body having a composition within the range (however, excluding points on straight lines AB, AC, BC) enclosed by a constituent point A (50mol% BaO, 50mol% B2O3), a constituent point B (100mol% Fe2O3) and a constituent point C (85.7mol% Fe2O3, 14.3mol% BaO), the intended fine particles of ferrite c, alpha-Fe2O3 are simultaneously precipitated and the mixture of the powder is used. It is thus possible to obtain a magnetic recording medium with excellent abrasion resistance and a high S/N value as compared with another using simple ferrite.

Description

DETAILED DESCRIPTION OF THE INVENTION [Fourth technical summary of the invention] The present invention has excellent characteristics for high-density magnetic recording, and effectively improves the wear resistance of media for magnetic recording. The present invention relates to a method for producing magnetic powder containing fine particles that become colored by coloring.

[Prior art and its problems]

For magnetism conventionally used for video recording, digital recording, etc. As a solid medium, one in which acicular particles such as 1-Fe2O3, CrO2, etc. are coated and oriented on the support surface 1 has been widely used. In order to obtain an 8/N value that is sufficient for this meshing, it is necessary to make the particle size of the magnetic powder sufficiently small in terms of the minimum size. For example, in the case of current video recording, acicular magnetic powder having a length of approximately (13 μm) is used for the shortest recording wavelength of 1 μm.
Considering that the improvement of 1.1 is 1.1 and the minimum unit of recording is entering the sub-micron range, finer particles are strongly desired in the current acicular magnetic powder.

By the way, as the magnetic powder for magnetic recording, it is preferable to use one having a negative axis of easy magnetization. In other words, in current recording media, the magnetic distribution is given uniaxial anisotropy and the signal is recorded in the direction of the easy axis of magnetization. This is because a medium in which powder is coated and oriented so that the recording direction and its easy axis direction are parallel is generally used. - As a particle having an axial easy axis of magnetization, 1-F'e203. In addition to CrO2 and the like, hexagonal ferrites such as Bay elite are promising. However, in this type of ferrite, the coercive force j[ is too large and recording by the head cannot be performed sufficiently at that tt, so it is necessary to perform 1-Toyo substitution to control the coercive force.

[Summary of the invention]

The present invention n et al. have a particle size of 0 as magnetic powder for high-density magnetic recording.
．． It is less than 3 μm and requires a coating of 111#, which is required to uniformly coat the paint. In order to provide a mechanically separated nine-substituted macrogonal ferrite without agglomerations,
As a result of various experimental studies, we found that the raw materials containing the basic components of ferrite and the substituted components for reducing the coercive force were mixed in a certain ratio with glass cedar composite materials, and the bond was dissolved in S. By applying heat sensation 1 to a non-island body obtained by rapidly cooling an object, a circular substitution type hexagonal ferrite is generated in the non-island body with coercive force control, and in the acid purification section, A circle obtained by removing only the glass matrix,
It has been found that these powders have well-separated particles and are preferable as magnetic powders for magnetic recording.

Furthermore, the present inventors have discovered that the ferrite can be precipitated,
After considering the amorphous composition of Kashira, 9M! 1st power, 1st power
In the B2O3-An-Fe 203 triangular component diagram shown in the figure (where included = #Sr, Pb can partially replace Ca), s a + air (AO50 mol% s B2035
α-
Only Fe203 precipitates, and the λ point, B point and Ca(Fe2
O385,7mol/'%,AO...14.311-ru4)
(does not include the above points), α-Fe203 and magnetobrambite ferrite co-precipitate, 11+IAC,
In the region containing more F and AO acid components, magnetobrambite-type ferrite was deposited.

In the amorphous composition region where ferrite can be obtained as a single phase, it is recommended to use a straight line ^CJ: and a composition with a slightly larger amount of AO acid than that. I started it.

By the way, the inventors of the present invention created a magnetic recording tape using -... magnetoblanbite ferrite obtained by heat-treating an amorphous material having the above-mentioned composition range,
When we investigated its characteristics, we found that the conventional rFl! It was found that the tape was coated with 20B and compared to 9 media, and it was found that the high accident recording had OT performance, but on the other hand, it became clear that the tape was easily worn out by sliding with the 1 sickle playback head. In contrast, it has been found that by incorporating fine particles with a relatively large hardness (Mohs hardness of 6 or higher) into the magnetic coating, as is normally done, tape wear can be reduced. 1 The abrasive particles commonly used have a wide particle distribution, which improves the abrasion resistance of the tape, but it also has the drawback of providing surface smoothness and lowering the S/N value. had.

The present invention eliminates such drawbacks and creates a mixed powder of magnetic powder and abrasive particles suitable for producing a dense magnetic recording medium having excellent wear resistance and a high 87N value. It is on offer.

That is, the present invention is based on the triangular component diagram shown in FIG.
AA(in 05Q(-#%, BzOa 50 mol t4
), B 4 (Fe20a 100% k '16
), and 0 points (F'e20385.7 mol, AO14
, 3 moles) (however, the straight line A r, (, k
By heat-treating the non-6 material having the composition C, B (the point on C remains unchanged), the desired blowjob 4) c, α-
By co-precipitating Fe20311 particles and using this mixed powder, we provide a magnetic recording medium that uses a ferrite umbrella and has superior abrasion resistance and is comparable in terms of 8/N value compared to 9 media. It is something to do. Magnetobrambite 117 elite obtained by heat-treating an amorphous material within the above composition range has an average particle size of 0.
It is in the range of 1 to 0.2 μm, and the saturation magnetization is also α-Fe.
If the amount of 203 mixed in is corrected, it has a high value of 66 emv/g or more, which is comparable to the magnetic powder precipitated from the Ba ferrite single phase region. The particle size of 1'e203 is 0.2 to 0.
It is well aligned in the range of 6 μm, and the cedar shape is spherical! t
stomach.

〔Effect of the invention〕

The present inventors created a magnetic tape by applying this mixed powder as a paint onto a film, and found that the wear resistance of the tape was found to be higher than that of the magnetic tape using the above-mentioned single ferrite powder. Improved 16°-5-e. ):
! kF7zt I1 Engineering 1.

At the end of the day, [tD a-PeiO3 particles (0,2~2,
flm).

When I created a magnetic tape by converting it into fractional paint, I found the same result (,
Although it was recognized that the tape had improved II stain resistance, it was also found that the magnetic tape using the mixed powder obtained by the present invention was superior in S/N value.

The above facts demonstrate that the α-F'e203 image particles co-precipitated with the magnetic powder in the method of the present invention have the effect of improving the wear resistance of the tape as an abrasive, and that the particle size is comparable to that of the magnetic powder. This is thought to be due to the fact that it has a small grain size and a steep grain distribution, so even if one of them is present, the surface properties of the tape will not deteriorate much.

Further, in the present invention, α-Fe203 is contained in the amorphous body.
Since the ferrite and ferrite are uniformly precipitated, the mixing trend of these two types of copper particles is good, and compared to the case where α-Pe203 is added later, the magnetic field is uniform and has a good 87N@ The recording medium is a factor that makes it easy to obtain. Furthermore, there is also an industrial advantage in that α-Fe203 particles, which have excellent performance as an abrasive, can be produced simultaneously with magnetic powder.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described.

(Example 1) BaQ B2O3, Pe203.7ri02 k and C
As oo, Ba■,.

Using Fe2O3, TiO2, CoCO3, H3BO4, Ba0=33.2 moA/4, B2O3=2
6.8 Moj' *, Fe20B = 30.59 mol%, Ti02 = 4.71 mol l, Co0 = 4.
71% Tonal 1 raw material is mixed as shown in the figure, placed in a platinum crucible with a nozzle at the tip, heated to 1350°0 with a high-frequency heater, melted, and then air pressure applied to melt the melt. The material was poured from a nozzle onto a rotating collection roll to produce amorphous flakes approximately 50 μm thick. This non-fertilized material was heat-treated for 4 hours at soo'o in an electric furnace. The amorphous material after heat treatment is washed with an acetic acid aqueous solution to dissolve the glass matrix, and the average particle size is about 0.1.
A mixed powder of mBa ferrite and α-1'e203 with an average particle size of about 0.3 μm was obtained. At this time, the content of α-Fe203 in the magnetic powder was approximately 4 wt %.

Next, to 80 parts of this mixed powder, 10,311 parts of vinyl monide-vinyl acetate copolymer resin, 1 part of polyurethane/resin
0 weight ts, lecithin 1 weight, stearic acid 0.2 a
l t16 s methyl ethyl ketone 120 t
, 120 ml of toluene was added, and it was made into a foreign paint using Su/Donru. A tol of inocyanate was added to the thus prepared magnetic tooth, coated on the surface of a polyethylene terephthalate film, and subjected to drying calender treatment 1 to obtain a magnetic recording medium.

(Actual example 2) 411 ratio is Ba0- = 37.0 mol%, B2O3'
-33,Qt-A/%,Fe2O3-22,94Mok
Yu, Ti02-a. 53 mol%, CoQ...3.5
Example 1 except that the four ingredients were mixed so that the amount was 36 roux.
Exactly the same as 11! ! Ba ferrite and rx-
A mixed powder of Fe203 was obtained. However, α-1'e20
The content of Ba ferrite in No. 3 was about 20 wt. Using this, a magnetic recording medium was obtained in the same manner as in Example 1.

(Comparative Example 1) 4ii cutting ratio is BaCL-38.0 mol% s”z03
...32.0%, F'e203 ・22.94
q4, Ti02-3.53 mol'4, COO...
353 molti, except that Il was mixed.
A Ba ferrite single phase powder having an average particle size of about 01 μm was obtained in the same manner as in Example 1, and a magnetic recording medium was obtained in the same manner as in Example 1 using this powder.

(Comparative Example 2) Commercially available Q-Fe 203 powder (0.2-2tim) was added to the Ba Mitsu 1 light phase powder prepared in Comparative Example 1 for 4W.
t170t, and using this, 48 magnetic 4-pin recording media were prepared in the same manner as in Example 1.

This relates to the above examples and comparative examples. Early S of magnetic recording media
/N value and a decrease in output when the magnetic head was repeatedly moved 20 times in sliding contact with the magnetic head at approximately 4 m/sec.

Table 1 As is clear from the above facts, compared to Comparative Example 1, which contains α-Fe20B, the media of Actual Example 1 and Comparative Example 2, which contain α-Fe203, have better head-to-head contact. No decrease in output was observed after contact was lost, indicating that it has excellent wear resistance.

By comparing Example 1 and Comparison-2, it can be seen that α
-Pet's g5 addition (approximately 4 wt%) is the same -t4,
The mixed powder obtained by the method of the present invention has a higher 8
/NIl& can be obtained.

From the above facts, it can be seen that the recording medium prepared by the present invention using mixed and fine particles of magnetobrambite ferrite and α-Fe203 can be obtained by using phosphorous phase fine particles of magnetobrambite ferrite. compared to
C1-PE 0:4m, which is commercially available and has improved wear resistance without significantly reducing S/Nld.
Even when the particles are compared with a medium added after forming the paint, a high S/N ratio is shown, which indicates the effectiveness of the present invention.

By the way, the AO acid component of the present invention includes, in addition to BaO,
For example, 'T'1-CoTi may be used as a substituted component such as 8r, Pb, or a part of them replaced with Ca. It's also good.

[Brief explanation of the drawing]

FIG. 1 is an l-shaped diagram showing the triangular component diagram of the B203-AO-Pe 203 glass.

Claims (1)

[Claims] ill glass-forming substance B2O3 and general formula, V)
-nFe203 (However, A is at least one type selected from Ba, Sr, and Pb, and can be partially replaced with Ca)
The amorphous material is melted and rapidly cooled to form an amorphous material. The magnetic powder for magnetic recording is characterized by applying heat treatment to precipitate substitutional magnetoblanbite type ferrite particles with controlled coercive force, and then extracting the fine particles from the glass matrix. Regarding the manufacturing method, the amorphous composition is B2O3, Aqre 203 (
Fe 203 includes a ms component, and A is Ha,
At least one selected from Sr, Pb, and C
The following three points (a) 8203 = 50. A'1=5QmoAz%, (b) Pe203='100%, (c)
Within the l1llVlt region surrounded by AO = 14.3, Bie203 = 95.7 mol = 4 (however, @fan,
(The composition of b% (c) and the straight line -F connecting them are not included). manufacturing method.