JPS6020974A - Production of magnetic material for magnetic paint - Google Patents

Abstract

PURPOSE:To produce the titled material having excellent dispersibility in high yields, by dispersing an acicular magnetic iron oxide powder in a specified org. solvent contg. a Co compd. dissolved therein, heat-treating the dispersion and cooling it. CONSTITUTION:A Co compd. (e.g. cobalt naphthenate) is dissolved in an org. solvent (e.g. toluene) or a mixture of two or more solvents selected from among aromatics, ketones, satd. hydrocarbons, ethers and halogenated hydrocarbons. An acicular magnetic iron oxide powder is dissolved in the resulting soln. and the dispersion is heated to react Co with he magnetic iron oxide powder. The resulting dispersion is cooled to room temp. Alternatively, the org. solvent is distilled off to obtain a powder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a liquid-based or powder-based magnetic material for magnetic paint.

Here, the liquid system refers to a dispersion system in which cobalt-containing magnetic iron oxide is dispersed in an organic solvent, and the powder system refers to the cobalt-containing magnetic iron oxide powder itself.

Conventionally, cobalt-containing magnetic iron oxide, which is a magnetic material for magnetic coatings, has been obtained by the following manufacturing methods (1) to (3).

(2) When obtaining acicular hydrated iron oxide, cobalt ions are allowed to coexist, and the manufacturing conditions for hydrated iron oxide are adjusted, for example, at a temperature of 0.5. A method of co-precipitating cobalt ions in hydrated iron oxide by adjusting H, and firing the cobalt ions to form magnetic iron oxide.

■ Acicular iron oxide (hydrated iron oxide; α-F6203: ”
A method in which FezO5,0<Z<1) is mixed or coated with a cobalt compound and then fired.

■ A method in which the surface of magnetic iron oxide is tightly coated with a cobalt compound.

However, in order to disperse the magnetic powder obtained by these conventional manufacturing methods into a paint and make it into a magnetic paint, in addition to processes such as filtration, washing, drying, and pulverization, it is necessary to disperse the powder into the paint and to form a magnetic paint. The process of forming an adsorption layer of surfactant or polymer on the powder surface to improve the crumbling property as a modification, or when premixing, it is filtered and dried until it reaches the state of secondary particles. Do I need a powerful disperser to loosen it? 2
1, which is a magnetic paint, has many disadvantages in that it involves a variety of processes, and great care was required.

Many of these drawbacks were thought to be due to the use of water as a solvent.

Therefore, in recent years, organic solvents and gold JJ baths in the organic solvents have been developed.
A method for producing magnetic powder was developed by dispersing ferromagnetic iron oxide powder in a solution consisting of four compounds and heat-treating it, thereby causing metal particles to form inside the ferromagnetic iron oxide particles (Special Publications Publication No. 1983).
-31729).

However, the organic solvents used in this production method include alcohols, fatty acids, semi-drying oils, fatty acid esters,
These organic solvents, such as oxycarboxylic acids, dimethylformamide, and dimethyl oxide, are completely unsuitable as solvents for binders for magnetic paints.

Therefore, the material obtained by this method has 5fL magnetic oxidation.
2 metals in iron particles! Part 4 of the reaction thread that made L people
It could not be used as a magnetic paint, and the organic solvent in the reaction system had to be distilled off to make magnetic powder before it could be used as a magnetic paint.

In addition, since the above-mentioned magnetic powder needs to be washed and dried with TPX, when it is dispersed in a solvent, it has poor compatibility with the solvent of the binder for magnetic paint and has poor dispersibility within the paint. Also, cleaning,
Eliminates the drawback of requiring multiple steps such as drying and re-grinding.
Was.

In view of the above-mentioned circumstances, the present inventors have made numerous studies and have determined that a final product can be produced by carrying out a reaction in which cobalt is introduced into particles of ferromagnetic iron oxide in the molten silicate of a binder for magnetic paint. The present invention was completed by discovering that it is possible to simplify the process by reducing the amount of paint in the paint.

The gist of the present invention is to dissolve a cobalt compound in a mixed organic solvent of one or more of aromatics, ketones, saturated hydrocarbons, ethers, or halogenated hydrocarbons, and then acicular magnetic iron oxide powder is dispersed in the powder, and then -11['.

After the dispersion is heated and reacted, it is cooled to room temperature to form a liquid dispersed thread (first invention), or the organic solvent is distilled off to form a powder (second invention). This is a method for producing magnetic materials for use as corruptible materials.

Hereinafter, the present invention will be specifically explained in accordance with the order of the steps.

First, a cobalt compound is dissolved in an organic solvent.

Organic solvents are used as binder solvents for magnetic paints, and examples include toluene and xylene for aromatics, methyl ethyl ketone, methyl isobutyl ketone, acetone, and cyclohegisanone for ethylbenzene 2 ketones. &M Japanese Hydrocarbon Purple): 11
and L7 are cyclohexane, methylcyclohexane, hashibutyl ether, amyl ether as ethers.
Examples of halogenated hydrocarbons include 2-ethylhexyldichloropentane chloride, and one or more selected from these may be used singly or in combination as the Q solvent. In this case, we are talking about binders for magnetic paints, such as vinyl chloride/vinyl acetate, rootstock polyurethane resin, nitrocellulose binder, etc.

Cobalt compounds include inorganic salts, 41 salts, chelate compounds, 11 salts, and imene aggregates that are soluble in the above-mentioned Nanki Yokuro, and they do not necessarily need to be soluble at room temperature and pressure. During the reaction, even a small amount of water may be exposed under heat or pressure in a bath. For example, as the organic salt, cobalt nandene, cobalt 2-ethyl hexanoate, or cobalt acetate is used, and as the inorganic salt, cobalt chloride, cobalt sulfate, cobalt carbonate, etc. are used.

Next, in the present invention, acicular magnetic iron oxide is dispersed in the above-mentioned dissolved system of the cobalt compound, and then the dispersed thread is heat-treated.

Through this heat treatment, cobalt reacts with the acicular magnetic iron oxide and is introduced.

This heat treatment may be performed simply by heating the dispersion system to an appropriate temperature. The above heating may be carried out under normal pressure, but depending on the type of organic solvent used, the reaction may be carried out by heating and pressurizing in an autoclave or the like.

The amount of cobalt added in this reaction: and the relationship between coercive force,
The relationship between reaction temperature and coercive force is as follows.

Toluene as an organic solvent and a cobalt compound7
The table below shows the results of a reaction using cobalt thenate in an autoclave while keeping the reaction time constant (6 hours) and varying the amount of cobalt naphthenate added and the reaction temperature.

(Margin below) Note *1: Weight percentage of 20g of Co/Fe.

*2. After the reaction was completed, the organic solvent was distilled off, and the dried product powder was measured and obtained.

In Tests A1 to A3, the amount of cobalt naphthenate added was varied from 1.5 to 3.5 at a constant reaction temperature (220°C), and the cobalt-containing liquid and product retention were The relationship with magnetic force is shown in Figure 1.

In addition, in test A1.4.5, the reaction temperature was raised to 200% under a constant cobalt naphthenate addition (2, Ovt,,'%).
Figure 2 shows the relationship between the reaction temperature and the coercive force of the product.

The following can be understood from FIGS. 1 and 2.

That is, in the production method according to the present invention, the coercive force of the product can be increased by increasing the amount of cobalt compound added as seen in Figure 1, and the reaction temperature can be increased as seen in Figure 2. The coercive force of the product can be increased by increasing the magnetic field.

Thus, in this reaction system, the coercive force of the product can be controlled by controlling the amount of cobalt compound added and the treatment temperature. These control conditions vary depending on the type of organic solvent used, and it is best to set the conditions by conducting a preliminary test.

This reaction can be carried out at normal pressure if the heavy equipment solvent used has a high boiling point, but even if the solvent has a low boiling point, a pressure vessel such as an autoclave is used and the atmosphere is changed to an oxidizing gas, reducing gas, inert gas, etc. I will do it as. Preferably it is nitrogen gas.

Further, in the present invention, the dispersion system that has undergone the heat treatment to complete the reaction is cooled to room temperature to obtain a liquid dispersion magnetic material for magnetic paint, or the organic solvent of the dispersion thread is distilled off by an appropriate means. Obtain magnetic material for powdered unique paint.

The above-mentioned liquid dispersion type magnetic material can also be prepared by distilling off a part of the organic solvent to adjust the amount of the solvent.
When the treatment is carried out under heat and pressure, the pressure can be easily adjusted by partially blowing out the pressurized atmosphere in the autoclave.

However, if the above-mentioned powder magnetic material is treated under heat and pressure using an autoclave, it can be simply turned into a dry powder by blowing out the entire amount of organic solvent after the reaction is completed.

Although the present invention obtains a magnetic material as described above,
A magnetic paint can be obtained using the magnetic material as follows.

In other words, in the case of liquid dispersion type magnetic materials, it is possible to obtain a magnetic paint extremely easily by directly dissolving the binder and dispersant into the dispersion threads and applying organic solvent to adjust the overall sensitivity. , and in powdered rice powder,
After premixing this powder magnetic phase with a binder, an organic solvent, and a dispersant according to a conventional method, an organic solvent, etc. is added,
Disperse to obtain magnetic paint.

Since the present invention is configured as described above, the following features are obtained.

■ Since the solvent of the magnetic paint binder is used as the reaction solvent, there is no contamination of the product with impurities such as salt.
In particular, since no water is used, there is no water as a contaminant that degrades the properties of the melt. Improves dispersibility.

■ Particularly for liquid dispersion type magnetic materials, it is possible to obtain surface magnetic paints by adding a binder or dispersion cutting to this dispersion system, so the conventional manufacturing process can be greatly shortened. The large amount of water and time required to wash away the alkali in the manufacturing method results in unsatisfactory results. 1
However, there is no need to allow any product to pass through, so there is extremely little product loss.

Next, examples of the present invention will be described.

Example-1 Cobalt naphthenate as Co/2r-Fe20s 5
The sif was adjusted to 2.0 (tJ-, %) at 4% and ζ was added to 200 (mt) of toluene as a solvent, and then to this bath liquid was added ``-F6203 (He: 410 (Oe)
) (:s: 720 (emu/F) axial length 0.4
(μ), axial ratio 8) 50 ()), and toluene to make the total amount 420 (d).

This solution was dispersed using an ultrasonic homogenizer, and while stirring in an autoclave, one bag of reaction source was heated at 20℃ for 6 hours.
Allow time to react.

After the reaction was completed, the solvent was blown for about 350 m (7 m) to bring the pressure to normal pressure, and then the product was taken out in a compressed and dispersed state in toluene to obtain a liquid dispersion type magnetic material.

By drying a portion of the product and adding 1llllll of magnetic properties, the following effect was obtained.

GC magnetic force 6so (Oe), fa sum magnetization 74.4 (em
u/S') Squareness ratio 0.52, Fe"/Fe" 0°07CO/f-Fe2Q, 2. O ← %) A magnetic paint was obtained using this liquid dispersion magnetic material in the following manner.

Toluene was added so that the toluene/magnetic 1/31j amount ratio in the magnetic moon was 50 ()) 150 (!i') and adjusted to i+, [, 1. Then, according to a conventional method, a binder and the like were directly added to the prepared magnetic phase described above so as to have the following composition.

Prepared liquid dispersion magnetic material 100'y-Vinyl chloride/vinyl acetate copolymer 8.87 (polymerization ratio 91:6) Polyurethane resin 3.72 Lecithin 1.0 Nomethyl isophthyl ketone 50 (When I made a magnetic tape by coating it on 'br jiff film, the coercive force was z68
Obtained as 0 (Oe).

Example-2 2-enalhexane aqueous cobal) k0 to CO/7-1
Toluene 200 (mA) with a weight percentage of 3 (-2)
and further (pe2Q3(l(c: 410 (
oe) (fs'12.0(emu/P), axial length 0.4μ
The total amount was 420 (m/), and the reaction was carried out at a reaction temperature of 220° C. for 6 hours with stirring using an autoclave. Although this removal pressure increased to 8 (shi), the magnetic/II properties of the obtained magnetic powder were as follows: coercive force 520 (Oe), saturation magnetization 72.4 (emu/P), and squareness ratio 0.49. .

Sarani, when analyzed, Fe / Fe is o, 04 Co /
7Fe20s was 1.7Ctpt%). Chloride Example-3 Cobalt chloride (CoCIC6H, 0) was converted into CO2-core, 0
°OMfk percentage 4.0 <wt%) was added to methyl ethyl ketone (MEI () 2007!
e・0s(He: 410 (Oe)fs 72.0
(emu/9) axial length 0.4 (μ), axial ratio 8) to 50
y was added, and Soja was adjusted to 420 (d), and the mixture was reacted for 1.5 hours at a reaction temperature of 200° C. while stirring using an autoclave. At this time, the pressure rose to 201).

The magnetic properties of the magnetic powder obtained by A ( ) have a coercive force of 970 (Oe
) Saturation magnetization 78.4 (emu/y-) Squareness ratio 0.5
It was 3.

Sarani, analysis truto Fe"/F'e"ij: 0.31
(h/γ-Fet03 is 3.5 (LI)t%)

Example-4 Cobalt acetate (Co (CI(scOo)z・44it
O) as a weight percentage of CO/J FetOm is 4.0
(!%), methyl in butyl ketone (IVIIBK)
200 (d) and further (1'-Fe203
(He: 41.0 (Oe) rs near 2,
0 (emu/9) Axial length 0.4 (p) Axial ratio 8)
ft50 (P) was added to bring the total amount to 420 (mZ), and the reaction was carried out for 2 hours at a reaction temperature of 200° C. using an autoclave.

(The following is a margin) At this time, the pressure rose to (ton). The magnetic properties of the obtained magnetic powder are as follows: coercive force 1130 (Oe), saturation on magnetization 7
4.8 (amψ), and the squareness ratio was 0.54.

Further analysis shows that FJyFe” is 0.15, Co/
and -Fe, Os is 3.5 (wt grain.

Example-5 Cobalt acetate (Go (OHsooo), -4H2
0) at a weight percentage of C04-Fet Oa of 4. Q (
wt%) was added to 200 (mg) of a 1:1 mixed solution of methyl inbutyl ketone (MIBK) and toluene [additionally
c F-Fex os However c: 410 (Oe) φs:
72.0 (emu/r), axial length 0.4 (μ), axial ratio 8)
50(r) was added to make the total amount f: 420(d), and the mixture was reacted for 5 hours at a reaction temperature of 200° C. using an autoclave.

The pressure at this time rose to 10(-).

The magnetic properties of the obtained magnetic powder were as follows: coercive force 860 (Oe);
Saturation magnetization was 75.3 (e prefecture square ratio 0.53).

Further analysis shows that Fe""' F, i+, 0-10
, Co/J.

) inferiority Fe, to was 3.3 (incident).

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the cobalt content and the coercive force of the product when the reaction time and reaction temperature are kept constant and the amount of cobalt added is varied in the reaction of the present invention. Figure 2 is a graph showing the relationship between the cobalt content and the coercive force of the product. 2 is a graph showing the relationship between the reaction temperature and the coercive force of the product when the cobalt addition amount and reaction time are kept constant and the reaction temperature is varied in the reaction. Patent Applicant Asan 1461 S1 Company Agent Patent Attorney Tosa Hide Akira/Fuji Con) A+ (w%)

Claims (2)

[Claims] (1) A cobalt compound is dissolved in an organic solvent selected from aromatics, ketones, saturated hydrocarbons, ethers, or halogenated hydrocarbons (or a mixture of two or more); Thereafter, acicular magnetic iron oxide powder is dispersed in the melted thread, the dispersion system is heat-treated, cobalt is introduced, and the dispersion system is cooled to room temperature to form a liquid dispersion system. Manufacturing method of magnetic material for use. (2) A cobalt compound is dissolved in an organic solvent selected from aromatics, keto/s, saturated hydrocarbons, ethers, or halogenated hydrocarbons (or a mixture of two or more), and then For magnetic paint, characterized in that the dispersion system in which acicular magnetic iron oxide powder is dispersed in the dissolving thread is heat-treated, cobalt is added thereto, and the organic solvent of the dispersion system is distilled off to form a powder. Manufacturing method for magnetic materials.