JPS58214330A - Dispersant for metallic oxide powder useful for raw material of soft ferrite - Google Patents

Abstract

PURPOSE:To make it possible to prepare high concn. slurry of metallic oxide powder useful for a raw material of a soft ferrite without deteriorating magnetic characteristics of ferrite, by using ammonium salt or alkanolamine salt of acrilic acid polymer as a dispersant. CONSTITUTION:One kind or more of a polymer salt with an average M.W. of 500-30,000 selected from a group consisting of ammonium salt or alkanolamine salt of acrylic acid polymer (1), ammonium salt or alkanolamine salt of methacrylic acid polymer (2) and ammonium salt or alkanolamine salt of copolymer comprising acrylic acid and methacrylic acid (3) is added to metallic oxide. The addition amount of this polymer salt is different according to the particle size of a metallic oxide powder but within a range of 0.05-5%, pref., 0.2-0.4% on the basis of a wt. of the metallic oxide powder. By this dispersant, the concn. of the metallic oxide powder useful for soft ferrite can be increased up to about 75% in the slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dispersant for soft ferrite raw metal oxide powder.

Soft ferrite is made of a metal oxide whose main component is iron oxide, and is particularly useful as a material for the magnetic core of a magnetic coil. Soft ferrite is usually manufactured by the following process.

(1) Mix raw materials such as iron oxide, manganese oxide, zinc oxide, and nickel oxide with water. 3)
This is spray-dried, (4) then press-molded and calcined, (5)
Furthermore, water is added, and this is crushed to about 2 to 4 microns using a crusher, a binder is added, (6) it is spray-dried [7] to form granules, and (7) this is press-molded and sintered.

In the above-mentioned pulverization steps (2) and (5), it is common to grind the raw material metal oxide powder into a water slurry of about 50% by weight. By increasing the water slurry concentration (which means decreasing the water content in the slurry), the following favorable effects can be realized.

(1) In the pulverization process, the pulverization efficiency increases; the time required to pulverize particles to the desired particle size is shortened.

(2) The time required for spray drying is shortened.

(3) The bulk density of the spray-dried metal oxide powder is increased, and the press pressure during press molding is reduced.

All of the above effects lead to improved productivity and significant savings in power energy.

However, if the slurry concentration is increased simply by reducing water, the viscosity of the slurry increases, which increases the grinding time and makes it difficult to transport the slurry, making it difficult to improve productivity and save power energy. stomach.

As dispersants for inorganic powders such as calcium carbonate powder and titanium oxide powder, sodium polyacrylate, sodium ligninsulfonate, and sodium salt of formalin condensate of naphthalenesulfonate are commercially available. If used as a dispersant for metal oxide powder for industrial use, the purpose of reducing the slurry viscosity can be achieved to some extent, but the magnetic permeability of the final product, ferrite, will deteriorate, so these dispersants should not be used. Can not. For this reason, there is a strong demand in the industry for a dispersant that can form a highly concentrated slurry without degrading the magnetic properties of the final product, ferrite.

The present inventors were keenly aware of the current situation, and as a result of intensive research, they found: (1) ammonium salt or alkanolamine salt of acrylic acid polymer, (2) ammonium salt or alkanolamine salt of methacrylic acid polymer, and (2) acrylic acid. A dispersant containing one or more polymer salts selected from the group consisting of ammonium salts and methacrylic acid copolymers deteriorates the magnetic properties of the final product, ferrite. The present invention has been completed by discovering that it is possible to form a highly concentrated slurry of soft ferrite raw material metal oxide powder without any problems.

The above polymer salts (1) and (2) are produced by conventional methods. For example, it can be produced by adding aqueous ammonia or alkanolamine to an aqueous solution of acrylic acid or methacrylic acid to form an ammonium salt or alkanolamine salt, then heating it to 60 to 110°C, and polymerizing while dropping a polymerization catalyst. Examples of alkanolamines used in the production of polymer salts include monoethanolamine, jetanolamine, triethanolamine, and the like.

It is preferable to add ammonia or alkanolamine in an amount sufficient to completely hydrate acrylic acid or methacrylic acid, but not in an amount that leaves some unneutralized substances to the extent that the performance of the polymer salt is not impaired. Good too. The polymer salt preferably has an average molecular weight of 500 to 30,000, more preferably 1,000 to 15,000. Polymer salts with an average molecular weight of less than 50 and an average molecular weight of 3
Polymer salts greater than 0,000 have insufficient ability to reduce slurry viscosity.

An aqueous dispersion of metal oxide powder for soft 7 elite is easily produced by mixing the metal oxide powder and water in the presence of the dispersant of the present invention.

There are no particular restrictions on the manufacturing procedure; for example, the metal oxide powder is added to an aqueous solution of a polymer salt and stirred, or a small amount of water is added to the metal oxide powder to form a cake. It can be produced by adding and stirring an aqueous solution of a polymer salt. The amount of the polymer salt according to the present invention added depends on the particle size of the metal oxide powder, but is in the range of 0.05 to 5% by weight based on the metal oxide powder, preferably L < [0 , 2 to 4 inches. By using the dispersant of the present invention, the concentration of the water slurry of metal oxide powder for soft ferrite can be increased to about 75%.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Put 18.81 g of an aqueous solution of 40 g of ammonium polyacrylate (average molecular weight 4,000) into a stainless steel beaker with an internal volume of 21 g, add 258.6 g of water, and stir.
to make the system uniform.

Next, soft ferrite raw material metal oxide blended powder (which contains 63% Fe 20 on a weight basis).

Powder containing 20% MnO and 17% ZnO with an average particle size of 1.8μ was added to the powder and stirred with a spatyl, followed by homodisper (mixer manufactured by Tokushu Kika Kogyo Co., Ltd.) The mixture was stirred for 3 minutes at a rotational speed of 3,000 revolutions per minute to obtain an aqueous dispersion containing 75 particles of metal oxide powder. The viscosity of this aqueous dispersion at 25°C was measured using a Brookfield type viscosity needle. The results are shown in Table 1.

This aqueous dispersion was added to polyvinyl alcohol (average polymerization degree 1.
ooo) was added, stirred well with a spatyl, and then spray-dried with a small spray dryer to obtain an average particle size of 10.
μ granules were obtained.

Form this granule (length x width x depth = 10m x 40 dragon x 1
0) Pour K, press under pressure of 1t/1M2, sinter in air at 1200℃, 8mm x 30mm, x 5
I got my friend's soft ferrite. 25℃ of this ferrite
The magnetic permeability was measured at a frequency of 10 KH2. The results were as shown in Table 1.

Example 2 A 40 volume aqueous solution of the polyacrylic acid ammonium salt (average molecular [4000) used in Example 1] was added to 10 f, and water was added to 344 kg.
1. 6501 metal oxide blend powder, 6.5 liters of polyvinyl alcohol.

In the same manner as in Example 1 except for the above, the metal oxide powder was
An aqueous dispersion containing ferrite and ferrite were obtained. The viscosity of this dispersion and the magnetic permeability of ferrite were measured under the same conditions as in Example 1. The results were as shown in Table 1.

Example 3 In place of the polyacrylic acid ammonium salt (average molecular weight 4000) used in Example 1, a 50% aqueous solution of polymethacrylic acid monoethanolamine salt (average molecular weight 6000) was used at 15F and water was used at 242.5F. In the same manner as in Example 1, an aqueous dispersion containing 75 pieces of metal oxide powder and ferrite were obtained. The viscosity of this dispersion and the magnetic permeability of the ferrite were measured under the same conditions as in Example 1. The results are shown in Table 1.

Example 4 Instead of the polyacrylic acid ammonium salt (average molecular weight t4000) used in Example 1, acrylic acid/methacrylic acid coelectrolyte (mole ratio 1/1)) 11 ethanolamine salt (average molecular weight 7000) was used. Aqueous solution of 18.8
An aqueous dispersion containing 75 parts of metal oxide powder and ferrite were obtained in the same manner as in Example 1 except that f was used.

The viscosity of this dispersion and the magnetic permeability of ferrite were measured under the same conditions as in Example 1. The results were as shown in Table 1. Comparative Example 1 The metal oxide blended powder used in Example 1 was added to 500 f of water, and 50 g of the metal oxide powder was added in the same manner as in Example 1.
An aqueous dispersion was obtained. Next, Example 1 was added to this aqueous dispersion.
Adding the polyvinyl alcohol 5f used in Example 1, soft ferrite 5 was obtained in the same manner as in Example 1. The viscosity of the aqueous dispersion and the magnetic permeability of the ferrite were measured under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 2 Same as Example 1 except that a 40% aqueous solution of sodium polyacrylate (average molecular weight 4500) was used in place of the ammonium polyacrylate salt (average molecular weight 400) used in Example 1. In the same manner, the viscosity of the aqueous dispersion containing 75 pieces of metal oxide powder and the aqueous dispersion of ferrite obtained and the magnetic permeability of the ferrite were measured under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 3 Instead of the polyacrylic acid ammonium salt (average molecular weight t400) used in Example 1, a 50% aqueous solution of lignin sulfonic acid sodium salt (trade name Lignaconc, manufactured by Juto Paper Co., Ltd.) was added at 15F and water. An aqueous dispersion containing 75 pieces of metal oxide powder and ferrite was obtained in the same manner as in Example 1 except that 242.5 F was used. The viscosity of this aqueous dispersion and the magnetic permeability of the ferrite were measured under the same conditions as in Example 1. Result is:! ! It was as per 1.

Comparative Example 4 In place of the polyacrylic acid ammonium salt (average molecular weight 4000) used in Example 1, a powder of 7talenesulfonic acid formalin condensate soda salt (42% aqueous solution having a viscosity of 75 centiboise at 20°C) was used. ) to 7.5?
An aqueous dispersion containing 75 ml of metal oxide powder and ferrite was obtained in the same manner as in Example 1 except that 2,502 ml of water was used. The viscosity of this aqueous dispersion and the magnetic permeability of ferrite were measured under the same conditions as in Example 1.

The results are shown in Table 1.

Comparative Example 5 Instead of the ammonium polyacrylate salt (average molecular weight - Ji4000) used in Example 1, an aqueous solution of ammonium ligninsulfonate (trade name: Polespers NH, manufactured by Borregaard in the Netherlands) was used for 18.8F. An aqueous dispersion containing 75 pieces of metal oxide powder and ferrite were obtained in the same manner as in Example 1, except for the following. The viscosity of this aqueous dispersion and the magnetic permeability of ferrite were measured under the same conditions as in Example 1. The results are shown in Table 1.

Table 1

Claims (1)

[Claims] 1, σ) ammonium salt or alkanolamine salt of acrylic acid A dispersant for soft ferrite raw metal oxide powder, characterized in that it contains one or more polymer salts selected from the group consisting of alkanolamine salts and alkanolamine salts. 2. The dispersant for soft ferrite raw metal oxide powder according to claim 1, wherein the polymer salt has an average molecular weight of 500 to 30,000.