JPS63105901A - Magnetic particle powder essentially consisting of iron alloy exhibiting spherical shape and its production - Google Patents

Abstract

PURPOSE:To obtain magnetic particle powder having good sphericity, grain size uniformity and large bulk density by oxidizing the ferrous hydroxide colloid obtd. by preliminarily adding water soluble silicate to a starting raw material while heating the same under prescribed conditions. CONSTITUTION:An aq. terrous salt soln. and 0.8-0.99 equiv. (with respect to ferrous salt) alkali hydroxide preliminarily added with the water soluble silicate are brought into reaction. A liquid contg. 0.1-5atomic% (in terms of Si with respect to Fe) said silicate and contg. the ferrous hydroxide colloid is prepd. While the liquid is kept heated to 70-100 deg.C, an oxygencontg. gas is permeated therethrough to oxidize the ferrous hydroxide. Further, >=1 equiv. (with respect to the remaining ferrous salt) alkali hydroxide is added thereto under the same heating and oxidizing conditions mentioned above. The magnetic particle powder having body centered cubic structure (X-ray diffraction diagram) of 0.5-2g/cm<3> bulk density and >=90emu/g saturation mangetization is thus obtd.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a material having a bulk density of 0.5 to 2.0 grad and containing 0.1 to 5.0 at% of St to Fe. and has a saturation magnetization value of 90 emu/g or more,
Iron (110
) plane diffraction peak intensity 1 (I+.,) and the (311) plane diffraction peak intensity of magnetite with spinel structure■
. The intensity ratio of 11° is In+s+ / (1(II@l
A magnetic particle powder mainly composed of an iron alloy, which has a spherical shape and consists of magnetic particles mainly composed of an iron alloy, which has a spherical shape with + LzI (+) of 0.1 to 1.0, and a method for producing the same. It is.

The main use of the spherical magnetic particle powder of the present invention, which is mainly composed of an iron alloy, is as a material particle powder for magnetic toners, carriers, etc. for electrostatic copying.

[Conventional technology]

In recent years, the spread of electrostatic copying machines has been remarkable, and along with this, research and development of magnetic toners and carriers, which are developers, are active, and improvements in their properties are required.

Developers used for electrostatic copying machines consist of toner and a carrier that transports the toner.This type of developer that has been commonly used in the past includes two-component developers and one-component developers. There is.

A two-component developer uses iron powder, glass beads, or the like of a certain particle size as a carrier to supply toner to a latent image.

Currently, iron powders having an average diameter of 50 to 120μ are widely used as carriers, and these iron powders are, for example, iron or iron alloys obtained by heating reduction of iron oxide particles in a reducing gas. A method of granulating magnetic particles whose main component is to a certain size and then heating and firing them, or a method of kneading the magnetic particles whose main component is iron or iron alloy with a resin and molding them to a certain size. etc.

On the other hand, a -component developer is called a magnetic toner, and because the toner itself is magnetically sensitive, it is transported and developed by itself without using a carrier, and magnetic particles are mixed into a synthetic resin. It is a dispersed powder with a constant particle size.

In recent years, there has been a trend toward higher copying speeds in electrostatic copying machines, and as a result, there is a demand for improved conveyance of magnetic toner. As such, both the saturation magnetization σS and the residual magnetization σr are required to be large.

This fact is reflected in, for example, Japanese Patent Publication No. 57-60765, which states, ``...In order to improve conveyance, it is necessary that the strength of magnetization of magnetic toner particles, that is, the residual magnetic flux Br, be high; In order to obtain magnetic toner particles having such characteristics, it is necessary that the granular magnetic particle powder, which is the raw material for the magnetic toner, has as large a saturation magnetization σS as possible and a high coercive force. It is clear from this.

In addition, if both the saturation magnetization σ3 and the residual magnetization σr of the magnetic particle powder are large, it is possible to vary the ratio of the magnetic particle powder and the resin over a wide range when manufacturing the magnetic toner, and the electrical resistance of the magnetic toner can be increased. Moreover, it is easy to control the charging property of the magnetic toner, which is advantageous from this point of view; furthermore, when the residual magnetization σr of the magnetic particle powder is a suitably high value, the spikes of magnetic toner on the magnetic drum can be easily controlled. It has the effect of improving the appearance and increasing the image density, and improving the saturation magnetization σS of the magnetic particles is also important when producing color toner with vivid colors. That is, the saturation magnetization σS of the magnetic toner is determined by, for example, Japanese Patent Application Laid-Open No. 59-220747.
The publication states, ``...The strength of saturation magnetization of magnetic toner is 25.
〜45e■u/g, the required image density (
In this case, 1.3 mg/cd) is obtained. As described in ``...'', the content is adjusted to a constant value, but if magnetic particle powder with high saturation magnetization is used, the content can be reduced, and as a result, it becomes the main coloring agent. This is because a large amount of dye particles and dye particles can be used.

Conventionally, magnetite particles have been generally used as magnetic particles for magnetic toner, but the saturation magnetization σ3 of the magnetite particles is as low as about 85 esu/g, which affects the transportability of the magnetic toner. This is the main reason for limiting improvement, and also makes the colors of color toners unclear.

Incidentally, by increasing the size of the magnetite particles, a saturation magnetization of about 90 emu/g can be obtained in some cases, but in this case, ■(11°)/(1(+11
11+113111) becomes 0, and the residual magnetization σr becomes 4.
It becomes about emu/g.

Recently, as copying speeds and image quality have increased, magnetic toner has been developed that has characteristics suitable for improving transportability, improving resolution, and sharpening images that produce both black and intermediate tones without fogging. Examples of magnetic particles include the above-mentioned magnetic particles whose main component is iron or iron alloy.

As mentioned above, magnetic particles mainly composed of iron or iron alloy have large saturation magnetization and are therefore preferable as material particles for magnetic toners and carriers. In order to achieve this, it is necessary to have particles with high filling properties when granulating magnetic particles mainly composed of iron or iron alloys, or when kneading into resin. It is required that the particle shape is as uniform as possible, especially spherical, and the particle size is uniform, and that there is little cohesion between the particles, and as a result, the powder has a large bulk density. 0 If it is possible to obtain magnetic particle powder mainly composed of iron or iron alloy, which has high packing properties due to improved sphericity, the powder can be packed in the closest density, thereby improving the performance of magnetic toner and carrier. be able to.

[Problem that the invention seeks to solve]

Although there is a current demand for magnetic particles mainly composed of iron or iron alloys with improved sphericity, the particles obtained by the above-mentioned known methods are still not considered particles with high sphericity. It's hard to say.

That is, the well-known magnetic particles mainly composed of iron or iron alloys are produced by adding oxygen such as air to a suspension containing ferrous hydroxide colloid obtained by the reaction of a ferrous salt aqueous solution and an alkaline aqueous solution. Magnetite particles are produced by a so-called wet method in which gas is blown into them, and the magnetite particles are used as a starting material and are heated and reduced in a reducing gas as described above, but the magnetite particle powder obtained by the wet method is - a, granular or cubic particles, dry powder;
The cohesiveness between the particles is strong, and therefore, the magnetic particles mainly composed of iron or iron alloy obtained by heating and reducing the magnetite particles as a starting material are naturally granular or cubic particles. , the cohesion between the particles is strong.

In addition to granular or cubic magnetite particles, attempts have also been made to obtain spherical magnetite particles using a wet method, such as those described in JP-A-49-35900 and JP-A-60-71529. There is a method.

However, as shown in Comparative Example 2 below, the cobalt-containing magnetite particles obtained by the method described in JP-A-49-35900 have insufficient sphericity and asymmetric particle sizes. Moreover, the cohesion between the particles is strong. This is produced by the hydrolysis reaction of iron carbonate obtained from ferrous sulfate and cobalt sulfate and an alkali metal carbonate, so cobalt ferrite core particles are rapidly precipitated and formed, resulting in a change in shape. It is thought that sufficient control was not possible.

In addition, although the magnetite particles obtained by the method described in JP-A-60-71529 have considerably improved sphericity and cohesiveness between particles, they have poor heat resistance and are sintered during thermal reduction. The sphericity and inter-particle cohesiveness of the iron-based magnetic particles obtained by heat reduction using the magnetite particles as a starting material are still not sufficient. This is thought to be because the particle formation and the growth of the magnetite core particles are not performed densely and uniformly, so the particle shape of the starting raw material particles cannot be sufficiently maintained during thermal reduction, resulting in the shape being distorted.

As mentioned above, there is a strong desire to establish a method for producing magnetic particles whose main component is iron or iron alloy with improved sphericity.

[Means for solving problems]

The present inventor has arrived at the present invention as a result of various studies on a method for producing magnetic particle powder whose main component is iron or iron alloy with improved sphericity.

Partly, the present invention has a bulk density of 0.5 to 2.0 g/c+
1, contains 0.1 to 5.0 at% of Si relative to Fe, has a saturation magnetization value of 90elIIJ/g or more, and has a body-centered cubic structure in its X-ray diffraction pattern. The intensity ratio of the diffraction peak intensity 1 (11°) of the (110) plane of magnetite and the intensity 1 + 31° of the diffraction peak of the (311) plane of magnetite having a spinel structure is II (to + / (
1 (1t.) + 10111) of 0.1 to 1.0, magnetic particles mainly composed of spherical iron alloy. Contains a ferrous hydroxide colloid obtained by reacting a powder and an aqueous ferrous salt solution with an alkali hydroxide in an amount of 0.80 to 0.99 equivalent to the ferrous salt in the aqueous ferrous salt solution. In oxidizing the ferrous hydroxide colloid by passing an oxygen-containing gas through the ferrous salt aqueous solution while heating it, either the alkali hydroxide or the ferrous salt aqueous solution containing the ferrous hydroxide colloid. Add water-soluble silicate to Fe in advance
0.1 to 5.0 at. After oxidizing the ferrous oxide colloid, 1.00 equivalents or more of alkali hydroxide is added to the ferrous salt remaining in the reaction mother liquor to produce spherical St-containing magnetite particles, and then The main component is an iron alloy that has a spherical shape and is made of magnetic particles whose main component is an iron alloy that has a spherical shape by heating and reducing the spherical Si-containing magnetite particles in a reducing gas. This is a method for producing magnetic particle powder.

[For production]

First, the most important point in the present invention is that during thermal reduction, a ferrous salt aqueous solution as a starting material is reacted with an alkali hydroxide in an amount of 0.80 to 099 equivalents to Fe'' in the ferrous salt aqueous solution. In oxidizing the ferrous hydroxide colloid by passing an oxygen-containing gas through the ferrous salt aqueous solution containing the ferrous hydroxide colloid obtained by heating, the alkali hydroxide or the ferrous hydroxide colloid is A water-soluble silicate is added in advance to any of the ferrous salt aqueous solutions containing iron colloids, and then an oxygen-containing gas is bubbled through while heating in the temperature range of 70 to 100°C, and then the heating oxidation conditions are the same as those of the heating oxidation conditions. Magnetite particles with improved sphericity obtained by adding 1.00 equivalent or more of alkali hydroxide to the ferrous salt remaining in the reaction mother liquor after oxidizing the ferrous hydroxide colloid under the following conditions. The point is that .

In the present invention, the reason why spherical magnetic particles mainly composed of iron alloys are obtained is that the spherical magnetite particles, which are the starting materials, control the sphericity due to the generation mechanism. However, since it was produced densely and uniformly, we believe that it was able to maintain its sphericity even during thermal reduction. That is, in the spherical magnetite particles according to the present invention, as a result of the addition of water-soluble silicate, the generation of magnetite nuclei is dense and uniform, and as a result, the magnetite nuclei grow equidistantly, and then the sphericity It is considered that magnetite epitaxially grew densely and uniformly on the surface of magnetite particles exhibiting an improved spherical shape.

Conventionally, when producing magnetite particles, water-soluble silicate is added, for example, in Japanese Patent Publication No. 55-282.
There are methods described in No. 03 and Japanese Patent Application Laid-open No. 58-2226.

However, none of the above methods relates to spherical magnetite particles, and the added water-soluble silicate is either heated and roasted to form a magnetite sintered body, or The water-soluble silicic acid in the present invention has the effect of controlling particle growth during roasting when producing red iron oxide, and controls the particle shape of spherical magnetite particles generated in an aqueous solution. This effect is completely different from that of salt.

Next, various conditions for implementing the present invention will be described.

The ferrous salt aqueous solution in the present invention includes ferrous sulfate,
Ferrous chloride or the like is used.

The alkali hydroxide in the present invention includes sodium hydroxide,
Alkali metal hydroxides such as potassium hydroxide, alkaline earth metal oxides and hydroxides such as magnesium hydroxide and calcium hydroxide can be used.

In the present invention, the amount of alkali hydroxide used to precipitate the ferrous hydroxide colloid is determined by the amount of F in the ferrous salt aqueous solution.
The amount is 0.80 to 0.99 equivalent to "e".

If it is 0.80 equivalent or less or 0.99 equivalent or more,
It is difficult to produce spherical magnetite particles.

In the present invention, the reaction temperature when oxygen-containing gas is passed through the ferrous salt reaction aqueous solution containing ferrous hydroxide colloid is 70°C.
℃~100℃.

If the temperature is 70° C. or lower, acicular goethite particles are mixed, and even if the temperature is 100° C. or higher, spherical magnetite particles are produced, but this is not suitable for industrial use.

The oxidation means is carried out by passing an oxygen-containing gas (for example, air) into the liquid.

Water-soluble silicates used in the present invention include sodium and potassium silicates.

The amount of water-soluble silicate added is 0.1 to 5.0 atomic % based on Fe in terms of Si.

If it is less than 0.1 atomic %, it is impossible to obtain the starting material, magnetite particle powder exhibiting a spherical shape with excellent sphericity.

When the amount is 5.0 atomic % or more, the added water-soluble silicate precipitates alone and is mixed in spherical magnetite particles.

The water-soluble silicate in the present invention is involved in the shape of the generated spherical magnetite particles. It is necessary to generate magnetite particles by passing an oxygen-containing gas into the salt reaction aqueous solution, and it is added to either an alkali hydroxide or a ferrous salt aqueous solution containing a ferrous hydroxide colloid. be able to.

When water-soluble silicate is added to the ferrous salt aqueous solution, it is precipitated as 5ift at the same time as the water-soluble silicate is added, so it is possible to obtain spherical magnetite particles with improved sphericity as starting raw material particles. I can't.

Almost the entire amount of the added water-soluble silicate is contained in the produced magnetite particle powder, and as shown in the examples below, the obtained magnetite particle powder contains almost the same amount as the added amount. .

In the present invention, the amount of alkali hydroxide added to Fe'' remaining in the mother liquor after oxidation of the ferrous hydroxide colloid is 1.00 equivalent or more.

If the amount is less than 1.00 equivalent, the entire amount of Fe'' will not precipitate, 1.0
A preferable amount is 0 equivalent or more in consideration of industrial efficiency.

In the present invention, the reaction temperature and oxidation means when adding alkali hydroxide to Fe'' remaining in the reaction mother liquor are as follows: The conditions may be the same as those for .

The heating reduction temperature in the present invention is 550°C or lower.

If the temperature is 550° C. or higher, the reduction reaction rapidly progresses, causing deformation of the spherical particles and sintering of the particles and the particles themselves.

In the present invention, it is not necessary to completely reduce the iron alloy to an iron alloy, and even in the case of a mixed phase of an iron alloy and magnetite, the effects of the present invention can be sufficiently exhibited.
(110) of iron with body-centered cubic structure in line diffraction pattern
Intensity of surface diffraction peak! . 1°, and the intensity of the diffraction peak from the (311) plane of magnetite with a spinel structure is 1
The intensity ratio of 1HI( is ■(th 01/(1(th or +
L2+n) must be 0.1 to 1.0. Therefore, the lower limit of the heating reduction temperature is not particularly limited.

I(I+.,/(ItI(o+ + ItffI
(If +3 is smaller than 0.1, the value of residual magnetization σr when the magnetic field is set to 0 will be 7 emu/g or less, which is not preferable.

In the thermal reduction in the present invention, the particle surface of the spherical magnetite particles may be coated in advance with one or more types of Cu, Ni, AI, Mg, Zn, etc., which have a sintering prevention effect. good.

In the present invention, the magnetic particle powder mainly composed of an iron alloy after thermal reduction can be produced by a well-known method, for example, by immersing it in an organic solvent such as toluene, and in the atmosphere of the magnetic particle powder mainly composed of an iron alloy after reduction. After replacing the inert gas with -H inert gas, the inert gas can be taken out into the air by gradual oxidation by gradually increasing the oxygen content in the inert gas and finally converting it into air.

〔Example〕

Next, the present invention will be explained with reference to Examples and Comparative Examples.

In addition, the average particle diameter in the following Examples and Comparative Examples is shown as the average value of numerical values measured from electron micrographs, the oil absorption amount and bulk density were measured by the method described in JIS K 5101, and the coloring power was measured by the method described in JIS K 5101. L(if
(brightness). The lower the L value, the better the coloring power and the better the dispersibility.The colorimetric test piece was made of 0.5g of magnetic particle powder mainly composed of iron alloy and titanium white 1. 5g of castor oil and 1.5cc of castor oil were kneaded with a two-wheeled muller to make a paste, and 4.5g of clear lacquer was added to this paste and kneaded to form a paint, which was obtained by applying it onto Miracoat paper using a 6ail applicator. .

The amount of Si in the particles was determined using the Fluorescent
JIS K 01
The measurement was carried out by performing fluorescent X-ray analysis according to the general rules for fluorescent X-ray analysis in No. 19.

In addition, the values of saturation magnetization σS and residual magnetization ff were measured using a VSM manufactured by Toei Kogyo, applying an external magnetic field up to 10 KOa.

The X-ray diffraction pattern was obtained using a special X-ray diffraction device manufactured by Rigaku Denki.
Characteristics of e) were automatically measured using IKα, and t
ut. l and IT3111 are the xwA of the diffraction peak from the (1,1,0) plane of iron with a body-centered cubic structure, respectively.
(3,1) of magnetite with strength and spinel structure
, 1) is the count value of the X-ray intensity of the diffraction peak from the surface.

Figure 1 shows these intensity ratios, saturation magnetization σS, and residual magnetization σ
The intensity ratio of the X-ray diffraction pattern is expressed as I (11°, /
(1<I(@++1+3□)].

Production of magnetite particle powder exhibiting a spherical shape) Example 1
~101. Comparative Examples 1 to 3; Example I Ferrous sulfate aqueous solution 2 containing 1.5 mol/1 of Pa”
0m+ was added in advance to the reactor with sodium silicate (3 at.
No.) (Sing 28.55 wt%) 18.99 was added to the 2,85-N NaOH aqueous solution 201 obtained by adding (corresponding to 0.95 equivalent to Fe''), po
6.9, an aqueous ferrous salt solution containing Fe(OR)t was produced at a temperature of 93°C.

The above ferrous salt aqueous solution containing Fe (OH)
100A per minute at 3℃! 240 minutes to produce a ferrous salt aqueous solution containing magnetite particles.

Next, 1.58-N NaOH aqueous solution 21 was added to the ferrous salt aqueous solution containing the magnetite particles (corresponding to 1.05 equivalents to "Fe"), and the solution was heated at 201/min at pH 11.8 and temperature 93°C. of air was passed through the tube for 60 minutes to generate magnetite particles.

The produced particles were washed with water, separated from P, dried, and crushed by a conventional method.

As is clear from the electron micrograph (x20,000) shown in Figure 2, the obtained magnetite particles are spherical particles with an average particle diameter of 0.22 μ-, without entanglement between the particles. Met.

Further, as a result of fluorescent X-ray analysis, this spherical magnetite particle powder contained 0.29 at% of St to Fe, had a bulk density of 0°57 g/aJ, and an oil absorption of 17 cm. The dispersibility was 1/100 g and the L value was 34.8, and the dispersibility was extremely good.

Examples 2 to 10 Type, concentration and usage amount of ferrous salt aqueous solution in production of ferrous salt reaction aqueous solution containing ferrous hydroxide colloid, type, concentration and usage amount of alkali hydroxide, water-soluble silicic acid Magnetite particle powder was obtained in the same manner as in Example 1, except that the type, amount and timing of addition of the salt, the type and amount of alkali hydroxide used in the precipitation of residual Fe, and the reaction temperature in each step were varied. .

Table 1 shows the main manufacturing conditions and the properties of the produced magnetite particles.

As a result of electron microscopic observation, the magnetite particles obtained in Examples 2 to 10 were all spherical particles with no entanglement between particles.

Comparative Example I A sulfuric acid primary drinking water solution 201 containing 1.5 mol/l of Fe”° was prepared in advance in a reactor.
In addition to 5-N NaOH aqueous solution 201 (1 for Fe”)
．． This corresponds to 15 equivalents. ), pH 12.8, temperature 9
A ferrous salt aqueous solution containing Fe(Off)x was produced at 0°C.

Above Fe(OH)! A ferrous salt aqueous solution containing
Magnetite particles were produced by blowing air at 1001/min for 220 minutes at .

The obtained magnetite particles were hexahedral particles, as is clear from the electron micrograph (x 20,000) shown in FIG.

This hexahedral magnetite particle powder has an average particle diameter of 0.17 μ-, a bulk density of 0.25 g/aJ,
Oil absorption f#29 1/100g and L value 40. It was l.

Comparative Example 2 An aqueous ferrous sulfate solution 20j1 containing 1.5 mol/jl of Fe"" was prepared in advance in a reactor.
In addition to 92-N NaOH aqueous solution 201 (corresponds to 0.64 equivalent to Fe"), ptl 4.8,
A ferrous salt aqueous solution containing g of Fe(OH) was produced at a temperature of 90°C.

The temperature of the ferrous salt aqueous solution containing Fe(OH)x is 90°C.
Magnetite particles were generated by blowing air at 100 l/min for 190 minutes.

The obtained magnetite particles were irregularly shaped particles, as is clear from the electron micrograph (X20,000) shown in FIG.

This amorphous magnetite particle powder had an average particle diameter of about 0.19 μ-, a bulk density of 0.34 g/cj, an oil absorption of 27 m1/100 g, and an L value of 39.0.

Comparative Example 3 20 g of ferrous sulfate aqueous solution containing 1.5 mol/1
In addition to 20 Il of 5-N NazCO1 aqueous solution (pe!+
This corresponds to 0.95 equivalent. ), pH6.6,
A ferrous salt aqueous solution containing FeCO5 was produced at a temperature of 90°C.

A ferrous salt aqueous solution containing magnetite particles was produced by passing air through the ferrous salt aqueous solution containing magnetite particles at a rate of 100 l/min for 240 minutes at a temperature of 90°C.

Next, 1.58-N NaOH aqueous solution 21 was added to the ferrous salt aqueous solution containing the magnetite particles (corresponding to 1.05 equivalent to Fe''), pH 11.6,
Magnetite particles were generated by blowing 2M air per minute for 60 minutes at a temperature of 90°C.

The generated particles were washed with water, separated in an oven, dried, and pulverized by a conventional method.

As shown in the electron micrograph (X20,000) shown in FIG. 5, the obtained magnetite particles had an irregular shape and could hardly be called spherical.

The average particle diameter of this magnetite particle powder is approximately 0.12μ
m, bulk density 0.299/cj, oil absorption 23m+
It was 1/100g and the L value was 38.4.

Production of spherical magnetic particles mainly composed of iron or iron alloy> Examples 11 to 20 Comparative Example 4; Example 11 Spherical magnetite particles containing St obtained in Example 1 Using a spherical magnetite particle powder, 120 g of the spherical magnetite particles were put into a No. 31 retort container with one end open, and Hz gas was supplied at a rate of 30 per minute while driving and rotating the container. The mixture was aerated at a rate of 400° C. and reduced at a reduction temperature of 400° C. for 180 minutes.

The magnetic particles mainly composed of iron alloy obtained by reduction are immersed in toluene and evaporated to prevent rapid oxidation when taken out into the air. A stable oxide film is applied to the surface.

The obtained metal particle powder whose main component is an iron alloy is shown in the electron micrographs (X 10.000 and
20.0OO), there was no entanglement between the particles, and the particles were spherical with an average diameter of 0.22 μm.

In addition, as a result of fluorescent X-ray analysis, this spherical magnetic particle powder mainly composed of iron alloy has a Si content of 0.2% compared to Fe.
Contains 94 atom% and has a bulk density of 0.75
God, oil absorption is 24.5ml/100g, and magnetism is saturation magnetization TFS 123. Oemu/g, residual magnetization t
yr 11. Oemu/gs coercive force 1350s, In+u/ (1I(+u+ 1+3111)) is 0
．． It was 48.

Example 12 After washing the spherical magnetite particles containing St obtained in Example 2, 1515 g of press cake (corresponding to 1000 g as solid content) was put into 151 water and dispersed with a strong stirrer. It was made into a slurry. The pu of the slurry at this time was 8.9.

Subsequently, the pH was adjusted to 6.0 using acetic acid, and then N
i (CH,C00)z' 48zO to 32.28
(corresponding to 1.0at% as Ni/Fe) was added and mixed with stirring for 10 minutes. Next, Mg(C
HsCOO) t・4H20 at 19.5g (Mg/Fe
(corresponding to 0.7 at%) was added. After thoroughly stirring and mixing to make the mixture homogeneous, the pH was adjusted to 9.3 using aqueous ammonia, followed by filtration and drying.

120 g of Si-containing spherical magnetite particles obtained in this way were subjected to surface coating treatment with Ni and Mg compounds, and heated to 430° C. in the same manner as in Example 11.
The mixture was heated and reduced for 0 minutes. After cooling to room temperature in a nitrogen gas atmosphere, Nt gas 51/win, air 21/I
(Aerate the mixed gas at a ratio of
The surface oxidation treatment was carried out by venting only gas until the heat generation disappeared. Further, the N yoga flow rate was gradually reduced to 0, and after confirming that no heat was generated again even if only air was passed through, metal particles powder whose main component was an iron alloy containing Ni, Mg, and Si was taken out into the air.

As is clear from the electron micrograph (X 20 , 000) shown in FIG. 8, the obtained metal particle powder containing iron alloy as a main component has little entanglement between the particles and has an average particle diameter of 0.24μ. The particles were spherical.

Further, as a result of fluorescent X-ray analysis, this spherical magnetic particle powder mainly composed of iron alloy has a Si content of 0.00% compared to Fe.
471 atomic%, 1.03 atomic% Ni to Fe, Fe
Against? Contains 0.702 at% Ig, bulk density 0.86 g/aj, oil absorption 123.4 ml/10
0g, and the magnetic properties are that the saturation magnetization σS is 105.5
eo+u/g, residual magnetization σr is 10.6 emu/g
, coercive force 1150e, In+e+ / (E
, +ro+ + Ls+u) was 0.31.

Examples 13 to 20 Magnetic particle powders containing iron alloy as the main component were obtained in the same manner as in Examples 11 and 12, except that the types of starting materials, the types of added metals, and the heating reduction temperature were varied. Table 2 shows the main manufacturing conditions and characteristics at this time.

In Examples 15 and 16, the samples were taken out in toluene in the same manner as in Example 11, and in Example 20, an oxidizing gas was introduced into toluene to perform surface oxidation treatment.

As a result of electron microscopy, the magnetic particles obtained in Examples 13 to 20, each consisting mainly of an iron alloy, had a spherical shape with no entanglement between the particles.

Comparative Example 4 A spherical magnetite particle powder was produced in the same manner as in Example 1, except that sodium silicate (No. 3) was not added, and the same procedure as in Example 11 was carried out using the magnetite particle powder as a starting material. Magnetic particle powder containing iron alloy as the main component was obtained.

As is clear from the electron micrograph (X20.0OO) shown in Fig. 9, the obtained magnetic particles mainly composed of iron alloy maintain a spherical shape in some parts, but the crystals are dense due to the Si content. Sintering progressed due to the low oxidation, resulting in significant shape deformation and agglomeration between particles.

[Effects] As shown in the previous example, the spherical magnetic particle powder of the present invention, which is mainly composed of an iron alloy, is a spherical particle with improved sphericity and a uniform particle size. Due to the shape of the particles, there is little cohesiveness among particles, and as a result, the bulk density is large. In the production of 0Mi toner and carrier, which are suitable as magnetic material powder, close-packing is achieved when magnetic particle powder mainly composed of an iron alloy and exhibiting a spherical shape with improved sphericity obtained by the present invention is used. This makes it possible to improve the performance of magnetic toner and carrier.

[Brief explanation of the drawing]

Figure 1 shows the saturation magnetization as and residual magnetization σr of magnetic particles mainly composed of iron alloy and 1+11111/([111
61+Ls+n). Figures 2 to 5 are microscopic photographs (X20.000) showing the particle morphology (structure) of magnetite particles.
2 shows the spherical magnetite particles obtained in Example 1, FIG. 3 shows the hexahedral magnetite particles obtained in Comparative Example 1, and FIG. 4 shows the magnetite particles obtained in Comparative Example 2. Regular-shaped magnetite particle powder, FIG. 5 shows magnetite particle powder with insufficient sphericity obtained in Comparative Example 3. 6 to 9 are electron micrographs showing the particle shape B (structure) of magnetic particles mainly composed of iron alloy, and FIGS. Magnetic particle powder mainly composed of (magnification is XIo, 00
0. 8 is the iron alloy magnetic particle powder obtained in Example 2 (X20,000), FIG. 9 is the iron alloy magnetic particle powder obtained in Comparative Example 4 (X20,000)
It is.

Claims (2)

[Claims] (1) The bulk density is 0.5 to 2.0 g/cm^3, the Si content is 0.1 to 5.0 atomic % relative to Fe, and the saturation magnetization value is 90 emu/g or more. And X
(110) of iron with body-centered cubic structure in line diffraction pattern
The intensity of the diffraction peak of the (110) plane and the intensity of the diffraction peak of the (311) plane of magnetite with a spinel structure I(
311) is I(110)/[I(110)+I
(311)] is 0.1 to 1.0. A spherical magnetic particle powder mainly composed of an iron alloy. (2) Ferrous hydroxide colloid obtained by reacting a ferrous salt aqueous solution with an alkali hydroxide in an amount of 0.80 to 0.99 equivalent to the ferrous salt in the ferrous salt aqueous solution. In oxidizing the ferrous hydroxide colloid by passing an oxygen-containing gas through the ferrous salt aqueous solution while heating, either the alkali hydroxide or the ferrous salt aqueous solution containing the ferrous hydroxide colloid. A water-soluble silicate was added in advance to Fe in an amount of 0.1 to 5.0 atomic % in terms of Si, and then 70%
After bubbling oxygen-containing gas while heating in the temperature range of ~100°C, the ferrous hydroxide colloid is converted to the ferrous salt remaining in the reaction mother liquor after oxidation under the same heating oxidation conditions. 1.00 equivalent or more of alkali hydroxide is added to produce spherical Si-containing magnetite particles, and then the spherical Si-containing magnetite particles are heated and reduced in a reducing gas. A method for producing magnetic particle powder mainly composed of an iron alloy, which is composed of magnetic particles mainly composed of an iron alloy and exhibiting a spherical shape.