KR960003300B1 - Metal powder producing method for high-density recording medium - Google Patents

Abstract

preparing goetite of small grain size by lowering the goetite forming temperature and NaOH concentration; transferring the formed goetite solution to the reaction bath of 10-20 deg.C; and adding Zn2- to it until the concentration of goetite(α-FeOOH) reaches 0.1-0.3mM and reacting them. The method produces goetite with small grain size and large diameter.

Description

Manufacturing method of metal powder for high recording density

The present invention relates to a method for producing a metal powder for high recording density, and in particular, to a multi-stage reaction step and a method for adding metal ions to improve the recording and reproducing characteristics of a high-tight mill while maintaining the specific surface area of the particles as they are. The present invention relates to a method for producing a high recording density metal powder for producing high tite.

In general, a method for preparing a magnetic material is to prepare goethite (FeO · OH) by adding alkali as a starting material of FeSO ₄ · 7H ₂ O or FeCl ₂ , FeCl ₃ , and dehydrate, reduce and reoxidize the gotite. Magnetic materials used in audio tapes, video tapes, and the like are manufactured by the method of the present invention.

The magnetic material prepared as described above maintains a needle-shaped high-tight shape during the first high-tight formation reaction. Therefore, the shape of the initially produced hightite has a decisive influence on the shape of the final magnetic particles.

In addition, the shape of the initially produced hightite is affected by reaction conditions such as air flow rate, acid temperature, added alkali, initial FeSO ₄ concentration, and the like.

In general, in order to improve the recording and reproduction characteristics of the high frequency (high recording density) signal, the longitudinal particle size (L) of the hightight should be made small, and the longitudinal particle diameter (D) should be increased at the same particle size (ie, When magnetic material is called needle shape, it is necessary to reduce the length of needle and increase the thickness of needle), and reduce particle size (L) to reduce particle noise, increase effective recording area, and increase particle size (D). Saturation magnetization (σ _s ) can be increased and dispersibility can be improved, so that high frequency recording and reproduction characteristics can be improved.

On the contrary, when the particle diameter (D) decreases, the specific surface area increases, so that dispersibility decreases. In addition, when the particle size (D) decreases, the saturation magnetization of the magnetic particles decreases, thereby degrading the magnetic properties.

It can be seen from the above results that the particle size (L) should be made small and the particle size (D) should be increased at the same particle size (L) in order to increase the high frequency magnetic properties when producing the magnetic material.

However, in the actual magnetic body manufacturing process, a general method in the reaction generation step of gotite which determines the particle formation of the magnetic body. That is, needle-like hightite was produced using a constant temperature, a constant oxygen flow rate, and a constant concentration of FeSO ₄ or NaOH, and the shape of the hightite was changed to the shape of magnetic particles as it is. In addition, the particle size (L) can be controlled by changing the conditions such as temperature, flow rate, concentration, etc., when manufacturing the gotite using the above-described general manufacturing method, but controlling the particle diameter (D) or the acicular ratio at the same particle size (L). Was impossible.

An object of the present invention is to prepare a high recording density metal powder by the multi-stage reaction step and the addition method of metal ions so that the specific surface area of the particles can be maintained while lowering the needle ratio to improve the recording and reproducing characteristics of the high-tight mill. To provide a method of manufacturing.

In order to achieve the above object of the present invention, the high-tight formation temperature and the concentration of NaOH are lowered to obtain high-tight particles of low particle size (L), and the resulting high-tight aqueous solution is transferred to a reaction tank of 10 ° C. to 20 ° C. to Zn ^{+. + Is} added to 0.1-0.3 mM of high-tight (α-FeO.OH) and reacted to produce high-tightness metal powder with low particle size (L) and high particle size (D). A manufacturing method is provided.

Hereinafter, the present invention will be described in more detail.

In the present invention, in order to produce high particle of low particle size (L) and high particle diameter (D), the high-tight formation temperature and NaOH concentration are lowered to obtain high particle of low particle size (L), and the high-tight colloid produced (collid) Aqueous solution was transferred to a reactor at 10 ° C to 20 ° C, and Zn ⁺⁺ was added to 0.1 to 0.3 mM of hightite (α-FeO.OH) to obtain high particle diameter (D). , And specific experimental conditions are as shown in Table 1 below.

TABLE 1

Conditions of each experiment

*One ; Initial FeSO ₄ # Concentration

*2 ; Alkali concentration R, R; 2Na ⁺ / Fe ⁺⁺ concentration ratio

Table 2 below is a table comparing particle lengths, particle diameters, and needle ratios of various examples according to the present invention.

TABLE 2

Measurement result table

Looking at the above experimental results, it can be seen that the particle size is reduced by 50% as the experiment 1 changed from the conditions to the conditions of the experiment 2, but there is no needle bed ratio.

Experiment 2 Under the conditions, the lower temperature and lower alkali concentration R can reduce the particle size to 0.15㎛, but the reaction time is longer than 8 hours, and in some cases, hightite (α-FeO.OH) and Magnetite (Fe ₃ O ₄ ) of spherical particle shape is precipitated at the same time and the experiment fails.

In addition, as in Experiment 3 and Experiment 7, when the secondary reaction is carried out in a multistage reaction without adding Zn ⁺⁺ , precipitation reaction is suppressed, and the needle length is decreased by decreasing the particle length. Able to know.

In addition, in the case of the second high-tight reaction at 10 ° C. as in Experiment 4 to Experiment 6 and at 20 ° C. as in Test 8 to Experiment 10, the addition of Zn ⁺⁺ drastically lowered the bed ratio. It can be seen that the particle diameter (D) value increases rapidly.

As such, it can be seen that the case where the relative particle diameter (D) value is increased by the addition of Zn ⁺⁺ is greater at 10 ° C than at 20 ° C. In other words, in the case of 20 ° C, when the concentration of Zn ⁺⁺ is added 2mM or more, the bedding ratio becomes 6.5 / 1, but in the case of the secondary reaction at 10 ° C, the bed ratio of 6.0 / 1 can be obtained even by adding 1mM of Zn ^++. In this way, a rapid relative particle diameter (D) increase effect can be obtained.

The crystal growth by the addition of Zn ⁺⁺ as described above is suppressed, and finally by reducing acicular ratio is therefore the reason that occurs is increased effect of the relative particle size (D) is tight and generated because the ionization tendency of the Zn ⁺⁺ greater than the Fe It is considered that the reaction required for epitaxial growth (two-dimensional longitudinal growth), ie, the effect of re-reducing Fe ⁺³ in the following chemical reaction mechanism.

Fe ⁺² → Fe ⁺³ → α-FeO

The effect of the addition of metal ions as described above is also used for the reduction reaction of the particle size (L), for example, by the addition of Cu ⁺⁺ during the initial reaction, becomes the reaction reaction, and rapidly high initial (α- FeO.OH) nucleation, thereby reducing the particle size (L) by the effect of lowering the initial FeSO ₄ concentration of the remaining solution.

Fe ⁺² + Cu ⁺⁺ → Fe ⁺³ + Cu ⁺

This is to use the Fe tends to ionize larger than Cu.

As described above, the present invention obtains a small particle size (L) by appropriate reaction conditions, and as shown in Experiment 3 to Experiment 10, the particle size and particle diameter are reduced by the secondary low temperature reaction and the addition of metal ions. In addition, by producing a metal powder by dehydration and reduction of the resulting hightite, a high-density (high-frequency) recording and reproducing characteristics were obtained, and an excellent magnetic medium was improved.

The present invention as described above was able to obtain the desired shape by changing the production method of high-tight, which directly affects the shape of the metal powder in order to produce a metal powder having a small particle size and a large particle size, and by adding a metal additive. In the present invention, the metal powder having a small particle size and large particle diameter, which can be produced by the present invention, has a large magnetic characteristic (σ _S ) value, a low noise, a particle size having the same specific surface area, and a relatively small particle size. It is expected to play a decisive role in improving the recording and reproducing characteristics of high recording density (high frequency) such as excellent acidity.

Claims (1)

Gotite formation temperature and the concentration of NaOH were lowered to obtain hightite of low particle size (L), and the resulting aqueous solution of gotite was transferred to a reaction vessel of 10 ° C to 20 ° C, and Zn-- was added to hightite (α-FeO.OH). A method of producing a metal powder for high recording density, characterized by producing a high tite having a small particle size (L) and a large particle diameter (D) by adding to and reacting with 0.1 to 0.3 mM.