JPS5842203A - Manufacture of magnetic powder for high density magnetic recurding medium - Google Patents

Abstract

PURPOSE:To obtain magnetic powder for high density magnetic recording medium by heating and maintaing amorphous magnetic powder made from glass material and a magnetoplumbite-type ferrite at a temperature at which its particles have an (n) value of less than the specified value and forming particles from it. CONSTITUTION:A raw material mixture including glass material of such as B2O3 and B2O3-SiO2, the fundamental component of a magnetoplumbite-type ferrite given by a general formula Ao.nFe2O3 (where A is chosen from Ba, Sr or Pb and is partically substitutable for Ca) and its substitution component for contralling the coercive force, is molten and colled rapidly to obtain amorphous material. This amorphous material is then heat-treated at a certain temperature below 200 deg.C for 1hr or less at which its particles have an (n) value of less than 6.2, precipitating substitution-type magnetoplumbite type ferrite particles having the controlled coercive force. These particles are extracted from the glass matrix and are formed into particles having a maximum particle diameter of less than 0.3mum, which can be used to form a recording medium for high density magnetic recording.

Description

[Detailed description of the invention] The present invention relates to a method for producing magnetic powder for high-grade drills.

BACKGROUND ART Conventionally, magnetic recording media used in video recording devices, digital recorders, etc. are widely used in which acicular particles such as r-F@lO1, Crag, etc. are coated and oriented on a support. In addition, in recent years, with the further improvement of record v11 degrees, the smallest unit of p1 record has entered the realm of napkin chron. In such a high f11 degree recording, sufficient 8/N
To obtain the ratio, K is magnetic+! In addition, it is necessary to make the particle size of 11 particles sufficiently smaller than the minimum recording unit.

For example, in the case of video recording, the shortest recording wavelength is 1 μm.
Magnetic powder having a length of approximately 0.3 μm is required. And ζro, the above r-re@o,, Cr01O!
51 acicular particles Kji- have sufficient magnetic properties,
Furthermore, it has become clear that it is difficult to obtain particles having a length of 0.3 zm or less, and that it is not possible to sufficiently cope with high-density recording at present.

On the other hand, in current recording media, the magnetic recording layer is given uniaxial anisotropy, and signals are recorded in the direction of the axis of easy magnetization.
, in this ninth position, a reef at which has a -axial easy axis of magnetization,
The coating is generally oriented so that the recording direction and the easy axis direction are parallel to each other. As a particle having this -axis O magnetization bird axis, s r -F@vor,
In addition to Cr pseudo, hexagonal ferrites such as Ba mitsutite are promising. However, this type of 7-piece has a very high coercive force, and if it is left in the trench, the head will not be able to record sufficiently.
It is necessary to control the coercive force. By the way, this species 07
Even in the case of m-lite magnetic powder, it was difficult to obtain magnetic powder with excellent magnetic properties, although the particle size of the magnetic powder was 6υ in the nine ranges of Kosho Ranki #.

The present inventors have developed grain gI as magnetic powder for high-density magnetic recording.
It is a substituted hexagonal ferrite (substituted hexagonal ferrite) which is mechanically well separated without sintering agglomeration, and has a k of less than 3 yen, and is rounded to be uniformly dispersed in the paint.臘)岑RITO), which we have conducted various experiments and research on, is made by heating and melting the glass-forming substance and ferrite raw material, making it amorphous, and then heat-treating it to create a matrix of microorganisms in the glass matrix. By precipitating netopkumbite mold particles and adopting specific heat treatment conditions in the so-called glass crystallization method, the maximum grain size required for high-density magnetic recording and brass is 0.3zm or less. The inventors have discovered that it is possible to obtain a magnetic dish with uniform distribution and excellent magnetic properties, leading to the completion of the present invention.

That is, the present invention comprises a glass-forming material and a compound having the general formula 0. a
Contains the basic component of magnetobukumbite ferrite represented by F@tOn (at least one selected from AFiBa, Sr, and PbfJ, which can be partially replaced with Ca) and a replacement component for coercive force control. The raw material mixture is melted and rapidly cooled to form an amorphous body.After that, this amorphous body is heat-treated to control the coercive force and the amount of substitution. precipitate,
After that, the glass matrix], the process to extract the microparticles! In the method for producing magnetic powder for magnetic recording, the amorphous material is heated at a heating rate of 200°C/hour or less, and then heated at a temperature such that the n value of the resulting fine particles is 6.2 or less. 4 Concerning a method for producing magnetic powder for high-density magnetic recording by heating to produce fine particles with a maximum particle size of 0.3 μm or less
It is 0.

The present invention will be explained in detail in detail. The magnetog2mbite reduction 782ite that is lost by the method of the present invention is expressed by the general formula M0・n ((F・*−xMx) y Os)0 In the formula, M is selected from Bm, 8r, and Pb, and at least one element can be substituted with To, and a part of it can also be replaced with Ca. A preferred element is Bm.

1*, M is a rounded substitution component that controls the coercive force of phe2ite in the magnetoblumbite group.

Lm, Za, G@, NI+, Zr, V, La & etc. may be used alone or in combination of two or more. Specifically, In,
Co-Tl, Co-Zr.

L嘱Co-(h, ee-'Ik, Co-V, ZEI
-TI, Zn -V, Zn-(h, k-Z
r.

Zm -Nb #111Ff to tL Luca, *preferably-* Preferably, Co-Ti.

It is C.-Zr. By controlling the amount of substitution (represented by X in the formula) of this substitution element, am and t having desired coercivity can be obtained.

9n is the composition ratio of Mu0 and (Fat-xMXhOs-T
It is desirable to take a theoretical value of Ka8 from the viewpoint of obtaining a perfect magnetopran ferrite, but for practical purposes, a value of &0-12 is sufficient.

As 1slRIII of the development method of the present invention, the above-mentioned glass-forming substance and magnedobucumbite Ji17s')
A raw material mixture consisting of four basic components and a substituted component is heated and melted. This raw material mixture is made by subjecting oxides, carbonates, etc. of each metal element constituting the magnetogumbite fi7e2ite represented by the above general formula, or a mixture thereof, to a solid phase reaction, and then converting them into fetuite in advance. The amount to be added as a compound is determined by the values of XjP and n in the general formula. Magnedogukunpai) 117
) Among the light components, AO and the glass-forming substance are mixed in equimolar amounts), and the glass-forming substance is blended in a lower sR ratio.

In heating and melting, the raw material mixture is generally mixed in a well-known machine and then heated and melted in an inert container made of platinum or the like using a well-known means such as high-frequency heating. The atmosphere at the time of melting is only briefly observed in the air.

The glass-forming substances used in this publication are the components of magnetobrambite ferrite! There are 6 members of the #family that form the rasp, specifically B, false.

80@・BmOa-84 system etc. are mentioned, but the B crystal is especially statically combined.

This melt is then rapidly cooled to become amorphous. Amorphization can be achieved, for example, by dropping the molten material into a high-speed rotating metal grate or an entertainment drum - the so-called single grate method.
Any known means such as rolling quenching or centrifugal quenching may be employed.

The obtained amorphous body preferably has a thickness of 80 meters or less.
It is necessary to keep it below Ops.

If this thickness exceeds JIG/lin, the quenching effect will not be sufficient and some magnetobrambite ferrite will already come out in the amorphous body before the next step, Fujidokoro 1) , Judokoro JIK Yote, rounding that grows into large particles of J/A order, is unfavorable.

In the obtained Ogami crystalloid, there are 2 Magnedogs) 11
7 Although each element that makes up x light is included,
It has not yet reached the point of crystallization, and by heat-treating it, crystallization is promoted by K. Gacus Matrix Medium K
The crystallization mechanism of magnetobrambite-type ferrite is not necessarily clear, but it is likely to be explained in the following passage.

In other words, in the low-temperature region where ferrite mold particles begin to precipitate from an amorphous state, horizontal layers are first formed centering on the F-101 component, but these nuclei or microcrystals are composed of abnormal KF-gos components rather than the stoichiometric composition. There are many. That is, the composition of Magnedog II is much larger than 6 for the general value of 0.nF@*oaK.

At this point, it appears that a normal heptadite lattice is not formed. Both the saturation magnetization and coercive force of these microcrystals are much smaller than their original values.

However, as the heat treatment temperature is increased, n becomes closer to the original value and the magnetic q# property 4 becomes better. As a result of studies conducted by the present inventors, it has become clear that in order to have sufficient magnetic 4I properties, it is necessary to heat-treat KFi at a temperature such that at least the above-mentioned Fe2'ite has a temperature of 2 or less. In addition, this temperature was generally located somewhere between the glass crystallization temperature and the melting point.

In short, the intention of the present invention is to round the precipitated particles to increase their magnetism, heat-treating them at as high a temperature as possible; The aim is to suppress grain growth by reducing the heating rate and rounding up the grain diameter.

By reducing the heating rate, the particles are made into fine particles.
This is thought to be due to the fact that S-cus is heat-treated at low temperatures for a long period of time, which results in rounding and the formation of nuclei, and that S-cus has a higher viscosity and is less likely to grow grains compared to rapid heating.

The heat treatment in this development @ is performed by heating externally at a temperature increase rate of 200°C/hour or less, and the l value of the resulting fine particles is &
When the temperature is suitable, such that the temperature is 2 or less, the temperature is maintained for a certain period of time, and heating is stopped when crystallization has sufficiently progressed. At this time, if the temperature increase rate exceeds 200 υ/hour, the width of the obtained grain ridges will increase], and in order to keep the maximum grain size to 3 μm or less than the required high density grain, the holding temperature must be adjusted. It is necessary to set the temperature at a relatively low temperature of 11 degrees Celsius), - Satisfactory characteristics cannot be obtained in terms of egg formation and holding power. On the other hand, when heating at a temperature increase rate of less than zoo'0/hour, the width of the grain size distribution of the crystals becomes narrower, so setting the holding temperature to a temperature close to the solidification temperature will increase the maximum temperature. Magnetic powder having sufficient magnetic properties can be obtained without the particle size exceeding 0.3 μm. Although there is no reason to specifically limit the lower limit of the temperature increase rate, from the viewpoint of the workability of the manufacturing worker 1, it is desirable that the temperature increase rate be at least ssυ/hour. The temperature at which the n value is &,2 or less is, as mentioned above, a temperature near the middle between the glass crystallization temperature and the melting point), and is generally a temperature of 6 sO<0>C or more. First, the time for holding this warm IRK must be at least 30 minutes.

Next, the heat-treated amorphous body is treated with a dilute acid to dissolve and remove the glass matrix and separate the magnetobrambite-proof huezite mold particles. Examples of the dilute acids used in this case include organic acids and inorganic acids such as dilute acetic acid, dilute hydrochloric acid, and dilute nitric acid. This dilute acid treatment removes the υj glass matrix and turns it into a magnetobutene bite! 1
7! Fine particles of T. nigra are obtained in the form of a mold with a maximum particle size of less than a O, S μm, which is mechanically separated by drying (by a conventional method) to produce a nine-magnetic powder.

The magnetic powder thus obtained is spread over a non-magnetic support along with a resin binder, a binder agent, and other additives, and a magnetic recording medium such as a magnetic tape is passed sideways. I can do it. This magnetic recording medium is r
It has become clear that it is possible to use needle-like soft particles such as -re l o14P Chrome to produce magnetic recording materials with extremely high writing accuracy compared to round magnetic recording materials.9.

The present invention will be explained below with reference to Examples.

Example 1 As coercivity-controlled 960,000-crystalline 7-elite, a part of iron is selected as a constituent atom, and 1lBa ferrite is selected as a TmuCo atom pair, and B1Os is used as a glass-forming substance. Selected 0 created non-Jk quality JIIE HaB@O@-31,04#%, BaO・
= 39.04 #%.

F@kaiOr” 2LS@Jl k %, Tl01
”・3.72 Mok%, CoO+++ 3.72
It's a duck. To create the amorphous material, first, the raw materials were sufficiently mixed in a mixer, and this mixture was charged into a platinum side container having a nozzle at the tip. Next, heat the mixture using a high-frequency heater for 13 seconds. $0'OK After heating and melting, gas pressure is applied from above the platinum container to directly pour the mixed melt.
Ik2 (m) was poured onto twin rolls with a rotational speed of 100 Orp, p and m, and rapidly cooled to create an amorphous glass with a thickness of 60 m. The crystallization temperature of this amorphous material was approximately 630°C. This amorphous material was heated in an electric furnace at a moderate temperature of 200°C/hour or less.
After heat treatment at a heat treatment temperature of 650°C or higher, the 7-2ite particles were extracted with a 20% acetic acid solution. Table 1 shows the average grain II (Dm), maximum grain size (Dnu
x), obtained from the particle size distribution and imaged the mid-range value width (ΔD) with Dm, 900 million (ΔD/Dm), saturation magnetization (6p) * Coercive force (H
c).

Comparative Example 1 A circle in which the amorphous material prepared in Example 1 was subjected to approximately ``C'' treatment at a heating rate of Zoo°C/hour or higher and a heat treatment salt temperature of 650°C or higher.

Comparing the #characteristics of several kinds of samples obtained with Example 1,
11.

Example 2 In the same manner as in Example 1, B snow Oa... 3 lines 04 le duck.

kiao −・−4 (LO4#%, Ih@0@=
1 & 804 #%, TiO2-=3.104%, Coo...3L104-R creates an amorphous glass composition with a rare composition. This amorphous material was heat-treated in an electric furnace at a heating rate of 200°C/hour or less and a heat treatment temperature of 650°C or more, and fine particles were extracted from the glass matrix in the same manner as in Example 1. The characteristics of the sample are shown in the first true.

Comparative Example 2 The Ogami crystal produced in Example 2 was heated in an electric furnace and heated through IIL.
Heat treated at 20G°C/hour or more at a heat treatment temperature of 650°C or more9. Examining the characteristics of nine kinds of samples obtained Example 2
A comparison is shown in Table 1.

As is clear from Table 1 in the margin below, n of the extracted fine particles is generally
It can be seen that sufficient saturation magnetization is obtained when is smaller than about 2. However, as can be seen from the comparative example, when the temperature increase rate is about 30 μ/hour, the particle size increases to 0.3 μm at high temperatures where - is less than &2.
There are particles having a particle size of the above particle size. However, the temperature increase
It can be seen that at 200° C./hour or less, fine particles having high saturation magnetization with n of 2 or less and a maximum particle size controlled to α3ptt* or less can be obtained.

Furthermore, these fine particles were made into paint and coated on a film to make a prototype magnetic tape.
The characteristics were compared with the magnetic tape coated with "most".

l! Brass wave number I X 1G' (reproduction output at m- (
Compare the recording brass regeneration with a ring head) in Table 1 KJt.

According to the same table, the Maro & 20 sample, which was heat-treated at a temperature of less than
I weigh 10g and stay ovh. 411 heating rate 100℃/
It can be seen that the nine samples had excellent tape characteristics after being heat-treated for less than an hour.

Example 3 A magnet** was produced in the same manner as in Example 1, with the same temperature and heat sensitivity as shown in II2. As a result, as shown in the same table, when the particle size was less than 0.3 meters, the To
〉, Hc is below 9000@, #t is 57-59・1
9. Indicates the value of m1/l.

Comparative Example 3 Regarding Sample 1 of Example 1, if the thickness of the amorphous material obtained by converting it into an amorphous body was 100 m, a magnetic dish could be produced in the same manner as in Example 1, and the The result was 1lIit.
With a maximum sa of 2 μm and an average particle weight, it was not suitable for use with a spring υ Takasho straight Ie drill.

The results below are more than the margins, @! The value is controlled to below o, spm,
And the replacement Jlv Gnetopkumbite 臘7 recruitment light with good magnetic properties also has a higher l! It is clear that the above-mentioned heat treatment conditions are necessary to obtain a powder suitable for hardening and for rounding such fine particles to be produced by the glass crystallization method.

Claims (1)

[Claims] 0 (1) Glass-forming substance and general formula 杏1-nF＠鵞0
．． (However, A is at least one selected from Ba, Sr, and Pb, or a part of these is Cm
A raw material mixture containing a substituted component is melted and rapidly cooled to form an amorphous body, and then the amorphous body is heat-treated to produce a substituted magnetoblanbite with controlled coercive force. In the manufacturing method of a**, which consists of the step of precipitating fezite particles and then extracting the fine particles from a glass matrix, the thickness obtained (by converting into an amorphous state) is 80
After heating an amorphous substance of 1200°C/hour or less, heating and holding the resulting fine particles at a temperature where the n value is 6.2 or less, the maximum grain size is 0.3 m. High-density magnetic recording sickle magnet a characterized by creating the following fine particles:
Manufacturing method of S. (Tomi) Madanetopukunpaito! 7J method for producing magnetic powder for multi-density magnetic recording according to claim 1, wherein the 1lL7et is Paricum 7ztite. (S) A method for producing a high-density magnetic recording-m** appetizer according to item 1 or 2, characterized in that the S lath forming substance is a, O, or the like. (4) The rounding substitution component for coercive force control is Co -TJ
The magnet for high-density magnetic recording according to the fifth, fifth, or second claim of the patent claim, characterized in that the magnet +! Lateral advancement method of klI&. (5) The thickness of Ogami crystal obtained by amorphization is *op
rm or less! A method for producing magnetic powder for use in Kosho Taka Magnetography. (＠) A method of manufacturing high-quality reef air g-operated magnetic cylindrical fabrication method of m1ll@1 section Kichin, which is claimed to be tatami mold when the heating temperature increase moderation is less than 100°C/hour.