JPH09266110A - Dispersant for hard ferrite material powdered metal oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To disperse oxide film powder into water slurry in high concentration by containing a strontium salt of a copolymer of olefin having a carbon number in a specific range and maleic anhydride. SOLUTION: A copolymer is obtained by copolymerizing in an organic solvent such as hydrocarbon a monomer mixture of maleic anhydride and olefin having a carbon number of 4 to 10 of aliphatic monoolefin and the like such as isobutene, butene-1, and butene-2; cyclic monoolefin such as cyclopentene and cyclooctene using a radical initiator such as organic peroxide and azo compounds. The copolymer is brought into reaction with strontium hydroxide in water to produce aqueous strontium salt. Hereby, metal oxide powder is dispersed into water slurry in high concentration.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dispersant for hard ferrite raw material metal oxide powder, and more specifically,
The present invention relates to a dispersant that can disperse a metal oxide powder, which is a raw material of hard ferrite, in an aqueous slurry at a high concentration and does not deteriorate the magnetic characteristics of hard ferrite.

[0002]

2. Description of the Related Art Hard ferrite (hard ferrite)
Is a complex oxide containing ferric oxide as a main component, and is a ferromagnetic material in which various substances are added or solid-dissolved. The composition of hard ferrite is generally expressed as a compound (MO.nFe ₂ O ₃ ) of ferric oxide (Fe ₂ O ₃ ) and a divalent metal oxide (MO). Examples of the divalent metal include Sr and Ba.

There are various methods such as a dry method, a coprecipitation method and a spray pyrolysis method for producing hard ferrite, and the most general method is the dry method. The manufacturing process of the dry method is
The process can be divided into mixing, drying, calcination, crushing, granulation, forming in a magnetic field, firing and finishing. The main raw materials for hard ferrite are Fe ₂ O ₃ , SrO, and Ba.
Metal oxides such as O, but Fe (OH) ₃ , Sr
Hydroxides such as (OH) ₂ and Ba (OH) ₂ and SrC
Carbonates such as O ₃ and BaCO ₃ are also used because they become metal oxides by calcination.

Even in the dry manufacturing method of hard ferrite, a wet method is often used in the mixing step and the crushing / granulating step. For example, to obtain powder before calcination,
In the mixing step, various metal oxide powders are weighed at a predetermined mixing ratio and mixed with water to prepare an aqueous slurry, which is pulverized with a wet attritor or the like, and then the slurry is dried.

For the drying of the aqueous slurry, spray drying by a spray dryer or hot air drying is often used, and concentration by a filter press may be performed before drying. At this time, it is desirable to increase the concentration of the metal oxide powder in the aqueous slurry in order to reduce the energy required for drying, shorten the drying time, and increase the bulk density of the dried metal oxide powder.

An aqueous slurry of ferrite powder is also used in the pulverization / granulation process. Also in this case, in order to improve the pulverization efficiency, it is desirable to increase the concentration of the metal oxide powder in the aqueous slurry.

If the amount of water used is simply decreased in order to increase the concentration of the aqueous slurry, the viscosity of the slurry becomes high, the mixing property of the metal oxide powder is deteriorated, and the transportation becomes difficult. On the contrary, there arises a problem that the grinding efficiency may be lowered.

In the manufacturing process of hard ferrite, as a dispersant for an aqueous slurry, sodium polyacrylate, sodium lignin sulfonate, sodium naphthalene sulfonate, a formalin condensate of olefin-olefin, which are generally used as a dispersant for inorganic powders, are used. If a soda salt of a maleic acid copolymer or the like is used, sodium ions are mixed in and the magnetic characteristics of the hard ferrite are adversely affected.

Therefore, conventionally, in the manufacturing process of hard ferrite, a chain olefin having 2 to 8 carbon atoms and / or carbon has been proposed for manufacturing soft ferrite (for example, JP-A-59-22638). The ammonium or alkanolamine salts of the copolymers of the cyclic olefins of number 4 to 7 with maleic acid have been used as dispersants in aqueous slurries.

However, when an ammonium salt or an alkanolamine salt is used, ammonia or amine is generated when heated in the subsequent drying step or calcination step, and the bad odor thereof causes a deterioration of the work environment or pollution. Become.

The present inventors have also proposed to use a water-soluble polycarboxylic acid polyvalent metal salt for the production of soft ferrite (Japanese Patent Application No. 7-56493). This has the feature that no bad odor is generated in the manufacturing process of hard ferrite. However, from the research results of the present inventors, for hard ferrite production, the polyvalent metal salt influences the magnetic properties, and not all polyvalent metal salts can be used, and the magnetic properties are not A dispersant that does not have an adverse effect has been desired.

[0012]

An object of the present invention is to disperse a metal oxide powder, which is a raw material of hard ferrite, in an aqueous slurry at a high concentration, and to deteriorate the magnetic characteristics of the hard ferrite. It is to provide a dispersant that does not exist.

The inventors of the present invention have conducted extensive studies to overcome the above-mentioned problems of the prior art. As a result, it was found that a strontium salt of a copolymer of an olefin having 4 to 10 carbon atoms and maleic anhydride is used as a dispersant. It was found that the viscosity of the aqueous slurry can be significantly reduced and that the magnetic properties of hard ferrite are not adversely affected. The present invention has been completed based on these findings.

[0014]

According to the present invention, there is thus provided a dispersant for a hard ferrite raw material metal oxide powder containing a strontium salt of a copolymer of an olefin having 4 to 10 carbon atoms and maleic anhydride. Provided.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (Copolymer of C4-10 olefin and maleic anhydride) The copolymer used in the present invention has a carbon number of 4-10.
Is a copolymer of olefin and maleic anhydride. The copolymerization ratio of the olefin having 4 to 10 carbon atoms and maleic anhydride is usually 30:70 to 70:30, and particularly preferably 50:50.

The weight average molecular weight of the copolymer is usually 500 to 100,000, preferably 1,000 to 1
It is 0000. The weight average molecular weight is a standard polystyrene conversion value measured by a gel permeation chromatography (GPC) method. If the weight average molecular weight is excessively large, the dispersibility is lowered, and the thickening or aggregation action is brought about, which is not preferable.

Specific examples of the olefin having 4 to 10 carbon atoms to be used include isobutene, butene-1, butene-2,
Pentene-1, Pentene-2, 2-Methyl-butene-
1,2-methyl-butene-2, hexene-1,2,2
Aliphatic monoolefins such as 4-trimethyl-pentene-1,2,2,4-trimethyl-pentene-2 and the like; cyclic monoolefins such as cyclopentene and cyclooctene and the like can be mentioned. Further, aromatic monoolefins such as styrene, α-methylstyrene and vinyltoluene can be used.

The method for producing the copolymer is not particularly limited, but a monomer mixture of an olefin having 4 to 10 carbon atoms and maleic anhydride is treated in an organic solvent such as hydrocarbon with an organic peroxide or an azo compound. It can be easily obtained by copolymerizing with a radical initiator such as.

(Strontium Salt of Copolymer) The method for producing the strontium salt of the copolymer is not particularly limited, but usually, the copolymer obtained by the above method is reacted with strontium hydroxide or strontium oxide in water. By doing so, a water-soluble strontium salt can be obtained. The amount of strontium hydroxide or strontium oxide used is appropriately selected according to the amount of the copolymer and the amount of maleic anhydride in the copolymer, but usually, the strontium compound is 30 to 100 mol relative to maleic anhydride. %use.

(Dispersant for Hard Ferrite Raw Material Metal Oxide Powder) The hard ferrite raw material metal oxide powder dispersant of the present invention comprises a strontium salt of a copolymer of an olefin having 4 to 10 carbon atoms and maleic anhydride. The dispersant, which is contained as the main component, may be in the form of a solid or an aqueous solution, but from the viewpoint of handling, it is usually used as an aqueous solution of 10 to 70% by weight.

The amount used as the dispersant for the hard ferrite raw material metal oxide powder of the present invention is appropriately selected depending on the particle size and concentration of the metal oxide powder and is not particularly limited, but usually 100 parts by weight of the metal oxide powder is used. On the other hand, 0.01-5
Parts by weight, preferably 0.1 to 2 parts by weight. If the amount used is too small, the effect of lowering the viscosity of the metal oxide aqueous slurry will disappear, while if it is too large, it will not only be economically disadvantageous, but will also adversely affect the magnetic properties of the product after firing. Not preferable.

By using the dispersant for metal oxide powder of the hard ferrite raw material of the present invention, the aqueous slurry of the metal oxide powder used as the raw material of the hard ferrite has a high solid concentration of about 50 to 80% by weight. Can be

[0023]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The parts and% in the examples, comparative examples and reference examples are based on weight unless otherwise specified.

(Reference Example 1) (Production of C5 olefin-maleic anhydride copolymer) 98 parts of maleic anhydride in an autoclave, C5 olefin fraction obtained by extractive distillation from C5 fraction obtained by purification of naphtha (pentene) -1 = 5.3%, penten-2 =
5.3%, 2-methyl-butene-1 = 7.9%, 2-methyl-butene-2 = 3.7%, n-pentane = 43.6.
%, Including i-pentane = 28.8%) 380 parts (C
5 olefins (including 87 parts), benzoyl peroxide 4 parts and a C20-C28 α-olefin and maleic anhydride copolymer (PA-208 manufactured by Mitsubishi Chemical Corporation) 1
A part was charged and the reaction was carried out by stirring at 70 to 75 ° C. for 3 hours. The product was a C5 olefin-maleic anhydride alternating copolymer having a weight average molecular weight of 6,000.

(Reference Example 2) (Production of strontium salt of C5 olefin-maleic anhydride copolymer) C5 olefin obtained in Reference Example 1
A suspension of maleic anhydride copolymer was charged with 133 parts of strontium hydroxide octahydrate and 550 parts of water,
After neutralization at C, unreacted C5 olefin and C5 paraffin were distilled off to obtain an aqueous strontium salt solution of C5 olefin-maleic anhydride copolymer having PH = 6 (concentration of active ingredient = 30%).

Reference Example 3 (Production of Ammonium Salt of C5 Olefin-Maleic Anhydride Copolymer) A suspension of the C5 olefin-maleic anhydride copolymer obtained in Reference Example 1 was added with 25% aqueous ammonia. 100 parts and 500 parts of water were charged, neutralization reaction was carried out at 70 ° C., unreacted C5 olefin and C5 paraffin were distilled off, and an ammonium salt aqueous solution of C5 olefin-maleic anhydride copolymer of PH = 6 (active ingredient Concentration = 30%).

Reference Example 4 (Production of Magnesium Salt of C5 Olefin and Maleic Anhydride Copolymer) C5 olefin obtained in Reference Example 1
To a suspension of and a maleic anhydride copolymer, 44 parts of magnesium hydroxide and 500 parts of water were charged, neutralized at 70 ° C., unreacted C5 olefin and C5 paraffin were distilled off, and PH = 6. An aqueous magnesium salt solution of a C5 olefin-maleic anhydride copolymer (active ingredient concentration = 30%) was obtained.

Example 1 Preparation of Aqueous Slurry I, Viscosity Measurement, and Magnetic Properties of Hard Ferrites Obtained Using the aqueous solutions obtained in Reference Examples 2-4, the following formulation was used to prepare an aqueous slurry I ( Hard ferrite raw material metal oxide concentration in the aqueous slurry = 50
%) Was prepared. (Aqueous slurry composition) Iron oxide (Sumitomo Metal Co., Ltd.) 200 parts by weight Strontium carbonate (Sakai Chemical Industry Co., Ltd. SW-P) 30 parts by weight Distilled water + dispersant 230 parts by weight

First, weigh a predetermined amount of distilled water into a container,
To this, 3.8 parts of an aqueous dispersant solution (the amount of the active ingredient is 0.5% relative to the raw metal oxide) is added, and then weighed iron oxide and strontium carbonate are added. The obtained mixture was stirred with a stirrer (MT-4 type manufactured by Nakamura Scientific Machinery Co., Ltd.)
By stirring at 400 rpm for 10 minutes, an aqueous slurry I containing 50% of metal oxide powder was obtained. The viscosity of the obtained aqueous slurry I was measured at 25 ° C. using a Brookfield viscometer at a rotor rotation speed of 60 rpm.
The results are shown in Table 1.

After drying each of the obtained slurries,
It was calcined at 1,275 ° C. The calcined powder thus obtained was used as a jaw crusher (No. 1023 manufactured by Yoshida Seisakusho Co., Ltd.).
A), sample mill (TAS from Tokyo Atomizer Manufacturing Co., Ltd.)
Coarsely pulverized with an M-1 type) and then with an attritor (IM-1S type, manufactured by Mitsui Miike Seisakusho Co., Ltd.) to an average particle size of 0.8 μm. Then magnetic field press machine (RS made by Sunkus Co.
Molded in a magnetic field at
Hard ferrite was prepared by firing at ℃.
The magnetic characteristics of the obtained hard ferrite were measured with a BH tracer (Model 3257 manufactured by Yokogawa Electric Co., Ltd.). Table 1 shows the results
Shown in

[0031]

[Table 1]

From Table 1, by using the strontium salt of C5 olefin-maleic anhydride copolymer,
It can be seen that the viscosity of the aqueous slurry is significantly reduced as compared with the case of no addition (Comparative Example 1). When an ammonium salt was used (Comparative Example 2), a strong pungent odor of ammonia was generated during calcination. Example 1 and Comparative Examples 1 and 3
Had almost no odor. When the magnesium salt was used (Comparative Example 3), the magnetic characteristics of the hard ferrite deteriorated significantly.

From the above experimental results, by using the dispersant of the present invention, it is possible to reduce the viscosity of the aqueous slurry of the raw material metal oxide of hard ferrite and to prevent the generation of pungent odor during firing. Further, it can be seen that the hard ferrite obtained by such a method has good magnetic properties.

Example 2 (Preparation of Aqueous Slurry II) Hard Ferrite Raw Material Metal Oxide Concentration in Aqueous Slurry = 70% (Aqueous Slurry II) Iron Oxide (Sumitomo Metal Industries, Ltd.) 200 parts by weight Strontium carbonate (Sakai Chemical Co., Ltd.) SW-P manufactured by Kogyo Co., Ltd. 30 parts by weight Distilled water + dispersant 99 parts by weight

First, 4.6 parts by weight of the strontium salt aqueous solution of Reference Example 2 (0.6% of active ingredient to metal oxide powder) and 94 parts by weight of distilled water were weighed in a container and stirred with a stirrer (Nakamura Scientific Machinery). 2,000 rpm with MT-4 type manufactured by Kogyo Co., Ltd.
The weighed iron oxide and strontium carbonate were gradually added with stirring. A free-flowing aqueous slurry II was obtained. The viscosity of the slurry measured by the same method as in Example 1 was 1,500 centipoise. When the dispersant was not added, the composition was in the form of a solid and had no fluidity. The magnetic characteristics of the hard ferrite prepared from the aqueous slurry II by the same method as in Example 1 are
It was substantially the same as in Example 1.

[0036]

According to the present invention, it is possible to disperse a metal oxide powder, which is a raw material of hard ferrite, in an aqueous slurry at a high concentration, and further, to obtain magnetic properties of the hard ferrite obtained from the aqueous slurry. It does not deteriorate the characteristics.

An embodiment of claim 1 will be described below. (1) The copolymer of an olefin having 4 to 10 carbon atoms and maleic anhydride has a molar ratio of the olefin to maleic anhydride of 30:70 to 70:30, preferably 50: 50. (2) The weight average molecular weight of the copolymer is 500 to 10
It is 50,000, preferably 1,000 to 100,000. (3) The olefin having 4 to 10 carbon atoms is an aliphatic monoolefin, a cyclic monoolefin or an aromatic monoolefin. (4) The amount of the strontium salt of the copolymer used is 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the hard ferrite raw material metal oxide powder. (5) The strontium salt of the copolymer is used as a solid or an aqueous solution. (6) The strontium salt of the copolymer is obtained by reacting 30 to 100 mol% of a water-soluble strontium compound with respect to maleic anhydride in the copolymer in water. (7) The water-soluble strontium compound is strontium hydroxide and / or strontium oxide.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiichiro Nakano, 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture Sumitomo Special Metals Co., Ltd. (72) Fumiaki Kikui, 2-chome, Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture 15-17 No. 17 Sumitomo Special Metals Co., Ltd. (72) Inventor Junichi Tsujimoto 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture Sumitomo Special Metal Co., Ltd. (72) Fumiya Fukushi Sunayama, Hazaki-cho Kashima-gun, Ibaraki Prefecture Address 16 Kashima Electronic Materials Co., Ltd.

Claims (1)

[Claims] 1. A dispersant for a hard ferrite raw material metal oxide powder, which comprises a strontium salt of a copolymer of an olefin having 4 to 10 carbon atoms and maleic anhydride.