JP2802543B2 - Manufacturing method of non-magnetic black pigment powder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a nonmagnetic black pigment powder composed of particles having a hematite structure containing iron as a main component in which Mn is dissolved. .

The main use of the black pigment particle powder according to the present invention is a developing toner, a paint, a coloring material for a resin, and the like.

[Conventional technology]

The black pigment particle powder is widely used as a developing toner by kneading and dispersing in a resin and then molding, and as a coating material by mixing and dispersing in a vehicle.

In recent years, black pigment powders that are nonmagnetic, safe, harmless, and excellent in workability and heat resistance are strongly demanded from the viewpoint of improving work efficiency, safety and health, and improving various characteristics in the energy saving era. ing.

In order to improve workability, it is important that the pigment powder is non-magnetic and has an appropriate size and thus has excellent dispersibility and is easy to handle.

Speaking of heat resistance, the development toner, which has been increasing in demand in recent years with the spread of copying equipment, has a high temperature of 150 ° C. or more in the manufacturing process. It is necessary that the color be stable even at a temperature of 150 ° C. or higher.

Further, in baking coating for drying a coating film at a high temperature, a pigment that does not discolor even at a high temperature of 400 ° C. is required since curing is performed at a temperature of 100 to 400 ° C., though it varies depending on the coating resin.

Conventionally, magnetite particle powder and carbon black particle powder have been widely and generally used as black pigment powder.

Examples of the non-magnetic black pigment powder composed of a mixed oxide of iron and manganese include the prior arts disclosed in Japanese Patent Publication Nos. Sho 17-17288 and Sho 47-30085.

[Problems to be solved by the invention]

Non-magnetic and complete, harmless, and black pigment powder excellent in workability and heat resistance is the most required at present, but known magnetite particle powder,
Due to the magnetism, the particles were re-agglomerated between the particles, making the dispersibility difficult, and the workability was poor. In addition, the magnetite particle powder began to change into magnetite at a temperature of 150 ° C. or higher, so that the color changed from black to brown and there was a problem in heat resistance.

Although carbon black is excellent in heat resistance, it is an ultrafine particle of about 0.01 to 0.1 μm, and is a bulky powder that is difficult to handle and has poor workability. Also, safety and hygiene problems such as carcinogenicity have been pointed out.

On the other hand, in the technical means shown in JP-B-47-30085, in which an iron compound and a manganese compound are fired at 800 to 920 ° C. to form a mixed oxide of iron and manganese, the raw materials are dry-mixed and fired. Therefore, it has a strong brown color and is inferior in blackness.

Further, the process described in Japanese Patent Publication No.
In the technical means of firing a pigment kneaded product obtained at a value of about 3.5 to 6.5 and adding a manganese metal and / or a manganese compound so as to be homogeneously distributed during the process at 600 to 800 ° C., most of them are used. Is brownish and the method for Fe ₃ O ₄ has been found to give a more complete shade of black, but the blackness is still insufficient with the technical means.

Accordingly, an object of the present invention is to provide a pigment powder that is nonmagnetic, safe, harmless, and excellent in workability and heat resistance and has good blackness.

[Means for solving the problem]

The present inventor has made various studies on the above-mentioned technical problems, and as a result, has arrived at the present invention.

That is, the present invention relates to a ferrous hydroxide colloid obtained by reacting an aqueous ferrous salt solution with 1.0 to 1.3 equivalents of an aqueous alkali hydroxide solution with respect to Fe ²⁺ in the aqueous ferrous salt solution. The suspension containing magnetite particles is generated by oxidizing the ferrous hydroxide colloid by a magnetite generation reaction in which an oxygen-containing gas is passed while heating the suspension containing the oxygen-containing gas to a temperature range of 45 to 100 ° C. to generate magnetite particles. A suspension,
After adding Mn or Mn and Fe2 ⁺ to the suspension containing the magnetite particles in the form of an aqueous solution so that Mn of 18 to 32 atomic% based on the total Fe in the liquid was present, the suspension was removed. The surface of the magnetite particles is coated with a Mn compound or a Mn compound and a Fe compound by heating and oxidizing under the same conditions as the magnetite generation reaction, and then the Mn compound or the Mn compound and Fe
The magnetite particles coated with the compound are separated, washed with water, dried, and then heated and calcined in a temperature range of 750 to 1000 ° C., so that Mn has a hematite structure mainly composed of iron in which solid solution forms. against Fe ²⁺ in the non-magnetic black pigment powder preparation and ferrous salt aqueous solution and said aqueous ferrous salt solution, which consists of obtaining a granular particles 0.2~0.8μm
A suspension containing ferrous hydroxide colloid obtained by reacting 0.80 to 0.99 equivalents of an aqueous alkali hydroxide solution, 45 to 10
A magnetite particle is generated by oxidizing the ferrous hydroxide colloid by a magnetite generation reaction in which an oxygen-containing gas is passed while heating to a temperature range of 0 ° C. to form a suspension containing magnetite particles. 18-32 atomic% Mn based on the total Fe in the liquid
1.For the aqueous solution of the compound, the Mn compound and the residual Fe ²⁺ ,
After adding an amount of an alkali hydroxide aqueous solution in excess of 00 equivalents, the surface of the magnetite particles is coated with a Mn compound and an Fe compound by heating and oxidizing under the same conditions as the magnetite generation reaction, and then the Mn compound and The magnetite particles coated with the Fe compound are separated, washed with water, dried, and then heated and calcined in a temperature range of 750 to 1000 ° C., so that the average has a hematite structure mainly composed of iron in which Mn is dissolved. This is a method for producing a nonmagnetic black pigment powder, which comprises obtaining spherical particles having a particle diameter of 0.2 to 0.8 μm.

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

As the ferrous salt aqueous solution in the present invention, ferrous sulfate, ferrous chloride and the like can be used.

As the aqueous solution of the Mn compound in the present invention, manganese sulfate, manganese chloride, or the like can be used. In order to uniformly coat the surface of the magnetite particles, it is preferable to add the aqueous solution.

As the aqueous alkali hydroxide solution in the present invention, sodium hydroxide, potassium hydroxide and the like can be used.

As a method for producing the magnetite particles having a granular shape to obtain a nonmagnetic black pigment powder of the granular particles in the present invention, for example, the technical means disclosed in Japanese Patent Publication No. 44-668 can be used.

The amount of the aqueous alkali hydroxide solution is determined by the amount of Fe in the aqueous ferrous salt solution.
1.01 to 1.3 equivalents to ²⁺ . If it is less than 1.01 equivalent, it is difficult to control the alkali addition ratio, and in some cases, the equivalent ratio may be less than 1.0, and it may be difficult to control the particle size and the like. If it exceeds 1.3 equivalents, acicular goethite particles are mixed.

Also, the reaction temperature is in the temperature range of 45-100 ° C, 45 ° C
If it is less than 1, needle-like goethite particles may be mixed, and even when the temperature exceeds 100 ° C., granular magnetite particles are generated, but this is not economical.

Mn that covers the particle surface of the granular magnetite particles of the present invention with a Mn compound or a Mn compound and an Fe compound
Is 18 to 32 atomic% based on the total Fe in the suspension. Mn
Is less than 18 at% or more than 32 at%, a nonmagnetic pigment powder can be obtained, but the brown color becomes strong, which is not preferable.
Pigment powders with good blackness can be obtained at 18-32 atomic%. More preferably, it is 20 to 25 atomic%.

The reason for adding Fe ²⁺ to Mn is to facilitate coating of Mn on the surface of the magnetite particles.
The amount of ²⁺ is less than 25 atomic% based on the total Fe in the suspension, and when it exceeds 25 atomic%, a nonmagnetic black pigment powder can be obtained, but the blackness is slightly inferior. .

It should be noted that the Fe ²⁺ compound to be added is desirably the same as the ferrous salt aqueous solution used for the generation of the magnetite particles, and in the coating treatment, an alkali hydroxide aqueous solution may be further added. Good. The conditions such as the processing temperature for coating may be the same as the conditions for forming the magnetite particles.

As a method for producing spherical magnetite particles from which the non-magnetic black pigment powder of spherical particles is obtained in the present invention, for example, the technical means disclosed in Japanese Patent Publication No. Sho 62-51208 can be used.

The amount of the aqueous alkali hydroxide solution is determined by the amount of Fe in the aqueous ferrous salt solution.
0.80 to 0.99 equivalents to ²⁺ . Less than 0.80 equivalent or 0.
If the amount exceeds 99 equivalents, it is difficult to produce spherical magnetite particles.

Also, the reaction temperature is in the temperature range of 45-100 ° C, 45 ° C
If it is less than 1, needle-like goethite particles may be present, and if the temperature exceeds 100 ° C., spherical magnetite particles can be produced, but this is not economical.

The amount of Mn added to the spherical magnetite particles in the present invention is also 18 to 32 atomic% based on the total Fe in the suspension. The reason is the same as in the case of the magnetite particles having a granular shape.

Further, the amount of the aqueous alkali hydroxide solution added to coat the Mn compound and the Fe compound is an amount exceeding 1.00 equivalent to the added Mn compound and the remaining Fe ²⁺ . If the amount is less than 1.00 equivalent, since Mn and Fe ²⁺ do not all precipitate, uniform coating cannot be performed. When it exceeds 1.00 equivalent, it is an amount in consideration of economy, preferably 1.01 to
1.3 equivalents.

The alkali hydroxide aqueous solution to be added is desirably the same as the alkali hydroxide aqueous solution used for generating the magnetite particles, and conditions such as a treatment temperature for coating may be the same as the conditions for generating the magnetite particles. .

Oxygen-containing gas (for example, air) may be used as the oxidation means of the reaction in the method for producing both magnetite particles of the present invention.
Can be carried out by aeration of the reaction suspension, and is preferably carried out in a reactor provided with a stirring function.

The non-magnetic black pigment powder obtained in the present invention has an average particle diameter of 0.2 to 0.8 μm. When the particle size is less than 0.2 μm, the particle size of the magnetite particles is required to be less than 0.15 μm.When the magnetite particles having a particle size of less than 0.15 μm are fired, the reaction activity becomes high. Control becomes difficult. If it exceeds 0.8 μm, the particles become too large and the coloring power decreases, which is not preferable.
Desirably, it is less than 0.5 μm.

Therefore, the particle diameter of each of the magnetite particles obtained by the method for producing both magnetite particles in the present invention is preferably 0.15 to 0.5 μm, and the magnetite particles having a particle diameter of 0.15 to 0.5 μm have a Mn compound or a Mn compound and an Fe compound. And then heating and baking, the size of the particles becomes slightly larger, and a black pigment powder having the above particle diameter is obtained.

In the present invention, the temperature range for heating and firing the magnetite particles coated with the Mn compound or the Mn compound and the Fe compound is 750 to 1000 ° C. If the temperature is lower than 750 ° C., the degree of blackness is insufficient. If the temperature exceeds 1000 ° C., the particles become too large and the coloring power cannot be obtained.

Note that the heating and firing is performed in the air. The heating and firing in the air is for oxidizing the magnetite to transform it into hematite.

In the present invention, Si, Al, P, B, Cu, Zn, Cr, C
o, Sn, Cd, V, a metal compound such as Mo may be added before or during the reaction in both the production methods, or magnetite particles coated with a Mn compound or a Mn compound and a Fe compound after the reaction is completed. The purpose of the present invention is not impaired even if the surface of the particles is coated with the above-mentioned metal compound to form or maintain the particle shape.

[Action]

In the present invention, the magnetite particles coated with the Mn compound or the Mn compound and the Fe compound are heated and calcined in a temperature range of 750 to 1000 ° C., whereby the magnetite is oxidized and changes to hematite, and the coated Mn compound is particles. The nonmagnetic black pigment powder having a good degree of blackness can be obtained because the particles are diffused inside and form a solid solution to form particles having a hematite structure mainly composed of iron in which Mn is dissolved.

Although the reason is not clear, it is thought that the blackness was improved because Mn was dissolved in the hematite structure in an exquisite balance due to the coating of the Mn compound on the particle surface.

The non-magnetic black pigment powder obtained in the present invention has a uniform particle size for both magnetite particles obtained in the reaction step, and is then fired after coating the Mn compound or the Mn compound and the Fe compound. Therefore, uniform particle size is maintained.

Note that the granular magnetite particles in the present invention are heated, fired, and baked, so that the granular particles become rounded particles.

In addition, since the particles have a hematite structure and become non-magnetic, the particles do not agglomerate due to magnetism, and thus are excellent in dispersibility and workability.

Furthermore, since it is obtained by firing at a high temperature in the temperature range of 750 to 1000 [deg.] C., it is a black pigment powder which is excellent in heat resistance and does not discolor even when heated when used for paints or toners.

In addition, the fact that the nonmagnetic black pigment powder obtained according to the present invention is excellent in blackness means that the L ^* value, a ^* value, and b ^* value are each measured by Hunter's Lab space. ^* Value is 21.0-0, a ^* Value is 1.0-0, b ^* Value is-
Since it is within the range of 0.7 to -1.7, it can be said that the pigment powder has good blackness.

〔Example〕

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

The average diameter of the particles in the following Examples and Comparative Examples was indicated by the average value of the numerical values measured from electron micrographs.

The magnetization value is measured in a powder state in a magnetic field of 10 KOe.

The L ^* value (brightness), a ^* value, and b ^* value were measured using a multi-light source spectrophotometer MSC-IS-2D (manufactured by Suga Test Instruments Co., Ltd.). The L ^* value, a
^* Value and b ^* value were indicated by colorimetric values.

The test sample was prepared by kneading 0.5 g of non-magnetic black pigment particles and 1.0 cc of castor oil with a Hoover-type muller into a paste, adding 4.5 g of clear lacquer to the paste, kneading the mixture, and forming a paint. Obtained by application using a 6 mil applicator.

Example 1 19.91 of FeSO ₄ aqueous solution containing 1.35 mol / Fe ²⁺ was added to 22.09 of 2.758 N NaOH aqueous solution prepared in advance in a reactor equipped with a stirrer (corresponding to 1.08 equivalent to the amount of Fe ²⁺ ). A ferrous salt aqueous solution containing Fe (OH) ₂ was produced at a pH of 13 or more and a temperature of 85 ° C.

Air was passed through the aqueous ferrous solution containing Fe (OH) ₂ at 90 ° C. for 100 minutes at 150 ° C. for 150 minutes to produce magnetite particles.

Then, to the suspension containing the magnetite, Mn ²⁺ 1.68m
ol / containing MnSO ₄ aqueous solution 5 (Mn content corresponds to 25 atomic% based on total Fe) and Fe ²⁺ 1.344 mol / containing FeSO ₄ aqueous solution 5 (Fe ²⁺ content is Against
This corresponds to 20 atomic%. ) Of 6.05N NaOH aqueous solution 5 (Mn
This corresponds to 1.14 equivalents with respect to the amount and the added Fe ²⁺ amount. ) At pH 13 or higher and at 90 ° C with 40
Vent for a minute to produce magnetite particles covering the Mn compound and the Fe compound.

The generated particles were separately washed with water, dried, and pulverized by a conventional method to obtain black particle powder.

Subsequently, the obtained black particle powder was placed in a porcelain crucible and fired in an electric furnace at 800 ° C. for 2 hours in air to obtain black particle powder.

The obtained black particle powder was analyzed by an electron microscope (× 20,0
As shown in (00), granular particles having an average diameter of 0.5 μm
The n content was 14.5 wt% as a result of X-ray fluorescence analysis, and the color was as follows: lightness L ^* was 18.89, a ^* value was 0.60, and b ^* value was-
It was 1.54.

Further, as shown in the X-ray diffraction diagram of FIG. 2, a hematite peak was observed.

The magnetism is 0.69 emu / g when an external magnetic field of 10 kOe is applied.
And was substantially the same as hematite.

Further, 10 g of the above-mentioned black pigment powder was heat-treated at 500 ° C. in air for 60 minutes to conduct a heat-resistant treatment test. As for the color of the heat-treated product, the lightness L ^* was 19.53, the a ^* value was 0.44, and the b ^* value was -1.70.

Example 2 An aqueous solution of FeSO ₄ containing 1.5 mol / Fe ²⁺ was mixed with an aqueous solution of 2.64 N NaOH 20 prepared in advance in a reactor equipped with a stirrer.
( ^Equivalent to 0.88 equivalent to Fe ²⁺ ), and pH 6.
9. An aqueous ferrous salt solution containing Fe (OH) ₂ was produced at a temperature of 90 ° C.

Air was flowed through the aqueous ferrous solution containing Fe (OH) ₂ at a temperature of 90 ° C. at a rate of 100 air per minute for 120 minutes to produce an aqueous ferrous salt solution containing magnetite particles.

Then, MnSO ₄ aqueous solution 5 containing suspension of Mn ²⁺ 1.2 mol / including the residual Fe ²⁺ and the magnetite particles (Mn amount corresponds to 20 atomic% with respect to the total Fe.) And 4.64N of NaOH Aqueous solution 5 (corresponding to 1.21 equivalents with respect to the amount of Mn and residual Fe ²⁺ ) was added at pH 13 or higher and at a temperature of 90 ° C. at a rate of 100
Was passed through for 40 minutes to produce magnetite particles covering the Mn compound and the Fe compound.

The generated particles were separately washed with water, dried, and pulverized by a conventional method to obtain brown particle powder.

Subsequently, the obtained brown-colored particle powder was placed in a porcelain crucible and fired in an electric furnace at 800 ° C. for 2 hours in air to obtain black particle powder.

The obtained black particle powder was obtained by using an electron microscope (× 20,0
00), spherical particles having an average diameter of 0.5 μm,
The n content was 12.3 wt% as a result of X-ray fluorescence analysis, and the color was as follows: lightness L ^* was 19.74, a ^* value was 0.86, and b ^* value was-
1.32.

Further, as shown in the X-ray diffraction diagram of FIG. 4, a peak of hematite was observed.

Magnetism is 0.51 emu / g when an external magnetic field of 10 kOe is applied
And was substantially the same as hematite.

Further, 10 g of the above-mentioned black pigment powder was heat-treated at 500 ° C. in air for 60 minutes to conduct a heat-resistant treatment test. As for the color of the heat-treated product, the lightness L ^* was 20.45, the a ^* value was 0.71, and the b ^* value was -1.49.

Examples 3 to 5, Comparative Examples 1 to 5 The type and amount of the aqueous ferrous salt solution for the magnetite generation reaction,
Kind and amount of aqueous alkali hydroxide, oxidation reaction time, amount and type of Mn salt aqueous solution for Mn compound or Mn compound and Fe compound coating treatment, type and amount of added ferrous salt aqueous solution, additional addition A black pigment powder was obtained in the same manner as in Example 1 except that the kind and amount of the aqueous alkali hydroxide solution and the heating and firing temperature were variously changed.

 The main manufacturing conditions and various characteristics at this time are shown in Tables 1 to 3.

[Effect of the Invention] The black pigment powder according to the present invention has a non-magnetic, safe, harmless, and hematite structure containing iron as a main component in which Mn is dissolved as described in the above Examples. Since it is a black particle powder composed of particles having the compound, it is excellent in dispersibility, workability and heat resistance, and has good blackness, and is suitable as a developing toner and a coloring material for a coating resin.

[Brief description of the drawings]

1 and 3 are electron micrographs (× 20,000) showing the particle structure of the black pigment powder obtained in Example 1 and Example 2.
It is. FIG. 2 and FIG. 4 are X-ray diffraction diagrams of the black pigment powder obtained in Example 1 and Example 2.

Claims (2)

(57) [Claims] 1. A ferrous salt aqueous solution and Fe in the ferrous salt aqueous solution.
While heating the suspension containing ferrous hydroxide colloid obtained by reacting 1.01 to 1.3 equivalents of an aqueous alkali hydroxide solution with respect to ²⁺ , while heating to a temperature range of 45 to 100 ° C., the oxygen-containing gas was removed. A suspension containing magnetite particles is generated by oxidizing the ferrous hydroxide colloid by a magnetite generation reaction through aeration to generate magnetite particles, and Mn or Mn and Fe ²⁺ are added to the suspension containing the magnetite particles. Is added in the form of an aqueous solution to obtain 18 to 32 atomic% of Mn based on the total Fe in the liquid.
After heating, the suspension is heated and oxidized under the same conditions as the magnetite generation reaction to coat the magnetite particle surface with a Mn compound or a Mn compound and a Fe compound, and then the Mn compound or the Mn compound. And magnetite particles coated with Fe compound, washed with water, dried,
Next, by heating and firing in a temperature range of 750 to 1000 ° C., non-magnetic particles are obtained, having a hematite structure containing iron as a main component and having an average diameter of 0.2 to 0.8 μm. Manufacturing method of magnetic black pigment powder. 2. A ferrous salt aqueous solution and Fe in the ferrous salt aqueous solution.
^The suspension containing the ferrous hydroxide colloid obtained by reacting 0.80 to 0.99 equivalents of an aqueous alkali hydroxide solution with respect to ²⁺ is heated to a temperature range of 45 to 100 ° C. while the oxygen-containing gas is removed. The suspension containing magnetite particles is formed by oxidizing the ferrous hydroxide colloid by a magnetite generation reaction that is aerated to generate magnetite particles, and the suspension containing the magnetite particles is 18% of the total Fe in the liquid. ~ 32
After adding an aqueous solution of an atomic% Mn compound and an aqueous solution of an alkali hydroxide in an amount exceeding 1.00 equivalent to the Mn compound and the remaining Fe ²⁺ , by heating and oxidizing under the same conditions as the magnetite formation reaction, The magnetite particle surface is coated with a Mn compound and an Fe compound, and then the magnetite particles coated with the Mn compound and the Fe compound are separately washed with water, dried, and then heated and fired in a temperature range of 750 to 1000 ° C. A method for producing a nonmagnetic black pigment powder, wherein spherical particles having an average particle diameter of 0.2 to 0.8 μm having a hematite structure containing iron as a main component in which Mn is dissolved as a main component are obtained.