JPH07277729A - Production of barium sulfate - Google Patents

Abstract

PURPOSE:To stably produce barium sulfate capable of assuming a structure having a platy and spindle-like cross section and manifesting a desired average grain diameter, aspect ratio, ratio of the perimeter to the area and X-ray peak ratio. CONSTITUTION:The method for producing barium sulfate is to react a solution of barium hydroxide or a barium salt (hereinafter referred to as a barium compound) with a solution of sulfuric acid or a sulfate (hereinafter referred to as a sulfuric acid compound) under conditions of 0.02-0.6mol/l concentrations of each compound at (1/10) to (5/1) molar ratio of the barium compound to the sulfuric acid compound, 50-100 deg.C reactional temperature and amounts thereof fed so as to provide 0.001-0.1mol/l barium sulfate concentration in completing the reaction for 10-300sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing barium sulfate having a particle size and shape suitable as a cosmetic ingredient, excellent feeling in use and hiding, high light diffusivity and transparency.

[0002]

2. Description of the Related Art Barium sulfate is harmless to the human body and has a strong hiding property, and is therefore widely used industrially as an X-ray contrast agent, a γ-ray absorber, a white pigment and the like. However, when it is used for cosmetics, and particularly when it is used for foundations and the like, conventional barium sulfate is poor in extensibility and adhesiveness, and lacks in usability. Further, it has a defect that it lacks transparency and the bare skin feel is poor after makeup.

On the other hand, many research results have been reported from a long time ago regarding the production of barium sulfate crystals and the growth of the crystals by soaking by heating. For example, Bull. Chem. Soc.
According to Japan, Vol. 27, No. 3, pp. 121-125 (1954), in a batch reaction in which an aqueous solution of a barium compound and a sulfuric acid compound is instantaneously mixed, the particle size and shape are controlled by the concentration of the mixed raw materials. , As the concentration decreases, atypical, spherical,
It has been shown that the particles are variously deformed into a spindle type, a diamond type and the like, and the maximum particle diameter is significantly changed from 0.013 μm to about 2 μm. However, with this method, it was difficult to obtain a powder having a suitable particle size and shape that meet the object of the present invention.

Also, Proc. World Congress III of Che
mical Engineering, Tokyo, pp. 1040-1043 (1986) and
Proc. 6th European Conference on Mixing, Pavia, 1
On pages 61-170 (1988), a semi-batch reaction in which a solution of a barium compound and a sulfuric acid compound is supplied in water at a predetermined time is adopted, and the reaction solution supply position, reaction solution concentration, temperature, pH, stirring speed The effect on particle size is reported. Here, the reaction solution concentrations are 0.69 to 1.37M and 1M, respectively.
Is disclosed (Table 2 on page 1042 for the former, 1 for the latter)
Page 63, line 8). The volume average diameters of particles produced by these methods are 0.8 to 7.5 μm and 0.8 to 1, respectively.
Although it was 1.4 μm, there is no description about the shape of the particles. And, as will be described later, under the reaction conditions reported in these documents, it is considered difficult to obtain a powder having a suitable particle size or shape that meets the purpose of the present invention.

As a means for solving the above-mentioned drawbacks, Japanese Patent Application Laid-Open No. 58-41718 discloses a method of increasing the particle size of barium sulfate, and Japanese Patent Application Laid-Open No. 62-174238 discloses a method for producing a barium sulfate crystal form. JP-A-5-43226 discloses a method for producing a barium sulfate pigment. However, all of these require heat treatment after treatment and mineral acid treatment, and therefore the manufacturing process is complicated, which is not preferable in industrial production. Further, even after such post-treatment, it is difficult to completely remove the former skeleton, and the size and shape of the obtained barium sulfate particles are not satisfactory as a cosmetic ingredient.

[0006]

As described above, in the prior art, it is difficult to produce barium sulfate particles suitable for use as a cosmetic ingredient such as foundation, or the production process is complicated. There were problems such as being there. Therefore, an object of the present invention is to use barium sulfate having a reasonably large and special plate-like structure so that a suitable feeling of use and concealing property can be imparted when barium sulfate is used as a cosmetic ingredient such as a foundation. It is to provide a method of manufacturing.

[0007]

Under such circumstances, the inventors of the present invention have conducted diligent research to solve the above-mentioned problems, and as a result, the reaction raw material for synthesizing barium sulfate, the reaction solution concentration, the reaction temperature, A method for stably producing barium sulfate having a light diffusivity and transparency, which has a suitable particle size and shape that meet the purpose of the present invention, is studied in detail and quantitatively the conditions such as reaction operation factors. Established and completed the present invention.

That is, the gist of the present invention is: (1) a solution of barium hydroxide or barium salt (hereinafter referred to as barium compound) and a solution of sulfuric acid or sulfate (hereinafter referred to as sulfuric acid compound). A method for producing barium sulfate, characterized in that the reaction is carried out under the following conditions (a) and (b): (a) the concentration of the barium compound and the solution of the sulfuric acid compound are both 0.02 to 0.6 mol /
Liter, molar ratio of barium compound to sulfuric acid compound is 1/10 to 5/1, reaction temperature is 50 to 100 ° C.,
(B) The barium sulfate concentration at the end of the reaction is 0.001-
Supply in an amount of 0.1 mol / liter for 10 to 300 seconds (2) The production method according to (1) above, wherein the barium compound is barium hydroxide or barium chloride, and the sulfuric acid compound is sulfuric acid, (3) is obtained. Barium sulfate is the following (c), (d),
(E) The manufacturing method according to (1) or (2) above, wherein (c) a light scattering transmittance of 55% or more when a thin film having a concentration of 20% by weight and a thickness of 15 μm is formed, (d) The whiteness of a green pigment mixed with 20% by weight is 57 or less,
(E) It has a plate-like structure and its perimeter length area ratio (square of perimeter of plate-like surface / area of orthogonal projection plane of plate-like surface) is 12.5.
-40 (4) The obtained barium sulfate has an average particle size of 3 to 10 μm.
The manufacturing method according to any one of (1) to (3) above.

Next, the present invention will be described in detail. The barium compound used in the present invention is not particularly limited as long as it produces barium ions in a solvent such as water or alcohol,
Examples thereof include barium hydroxide and barium salts such as barium chloride, barium sulfide, barium nitrate and barium acetate. Preferable examples include barium hydroxide, barium chloride, barium nitrate and barium acetate. Furthermore, barium hydroxide and barium chloride are most preferred because of the ease of processing and availability of by-products generated during the reaction.

The sulfuric acid compound used in the present invention is
Any compound that produces a sulfate ion in a solvent such as water or alcohol may be used, and examples thereof include sulfuric acid, sodium sulfate, sodium hydrogen sulfate, ammonium sulfate, potassium sulfate, and lithium sulfate. Preferably, sulfuric acid, sodium sulfate,
Examples thereof include sodium hydrogensulfate and ammonium sulfate, but sulfuric acid is most preferable in terms of availability and price.

These barium compound and sulfuric acid compound are dissolved in a solvent such as water or alcohol to be used as a barium compound solution and a sulfuric acid compound solution, respectively. As the alcohol, an alcohol having 4 or less carbon atoms (for example,
(Methanol, ethanol, isopropyl alcohol, etc.)
Is desirable. However, it is more preferable to use it as an aqueous solution because of the cost of the solvent and the necessity of recovery. Here, ion-exchanged water, distilled water, or tap water is more preferable in order to reduce impurities. Ion exchanged water and distilled water are most preferred.

The concentration of the barium compound solution (that is, barium ion concentration) and the concentration of the sulfuric acid compound solution (that is, sulfate ion concentration) are usually 0.02 to 0.6 mol / liter, and preferably 0.04 to 0. 4 mol / liter, more preferably 0.05 to 0.2 mol
/ Liter. When the concentration of the reaction solution is lower than this range, the particles tend to be coarse and are extremely dilute, which is not suitable as an industrial production method. Also, Proc.
World Congress III of Chemical Engineering, Tokyo,
1040-1043 (1986) and Proc. 6th European Confer
ence on Mixing, Pavia, 161-170 (1988), when a solution having a concentration exceeding this range is used, nucleation is increased due to the large degree of supersaturation and fine particles are generated. However, in some cases, they tend to agglomerate and the desired smoothness and transparency cannot be obtained.

Molar ratio of barium compound to sulfuric acid compound (moles of barium compound / moles of sulfuric acid compound)
Is usually 1/10 to 5/1, preferably 1/2 to
It is 2/1. If the molar ratio is outside this range, not only the yield will decrease, but also the operation of removing unreacted raw materials and by-products tends to be complicated. When the barium compound is present in excess of this range, the light diffusivity is poor. On the other hand, when the amount of the sulfuric acid compound is excessive, the transparency tends to deteriorate, and thus neither is suitable for the purpose of the present invention. It is preferable to adjust the concentration and the molar ratio by adjusting the barium compound and the sulfuric acid compound that satisfy these conditions.

When the reaction temperature is set to 50 ° C. to 100 ° C., preferably 70 ° C. to 95 ° C., the performance of the obtained barium sulfate is further improved. If the reaction temperature is lower than this range, the particles tend to agglomerate, and it tends to be difficult to obtain the desired smoothness and transparency. If the temperature exceeds this range, pressure resistance equipment is required, which is not desirable.

As a reaction method, both of the barium compound solution and the sulfuric acid compound solution described above are stirred into a solvent prepared in a reaction tank under stirring so that the barium sulfate concentration at the end of the reaction is 0.001 to 0.1 mol / mol. Liter, preferably 0.
10 to only 003 to 0.03 mol / l
The reaction is carried out by simultaneously supplying for 300 seconds. Stirring
It suffices that the reaction liquids be mixed, and the stirring Reynolds number (= stirring speed × (stirring blade diameter) ² / liquid kinematic viscosity) is preferably 1000 or more, more preferably 2000 or more. When the stirring Reynolds number is smaller than this range, the particle growth is slowed down,
It tends to be difficult to obtain a desired particle size. The stirring blade may be a turbine blade, a propeller blade, an anchor blade, etc.,
It doesn't matter the format. As the solvent in the reaction tank, ion exchanged water, distilled water, tap water, etc. are used.

The barium compound and the sulfuric acid compound are supplied continuously or intermittently. It is desirable that the molar ratio of the barium compound to the sulfuric acid compound being supplied is always maintained at 1/10 to 5/1 for the reason described in the section of the raw material molar ratio. In the present invention, the reason why these reaction solutions (barium compound solution, sulfuric acid compound solution) are simultaneously supplied to the solvent to carry out the reaction is that the degree of supersaturation in the reaction tank is changed depending on the reaction solution concentration, reaction temperature and supply time. This is to control the size and shape of the particles. That is, in the method in which one of the barium compound and the sulfuric acid compound is charged first and the other is supplied, the molar ratio at the initial stage of supply is 1/10 to 5 /.
This is because the range of 1 is exceeded and particles that meet the object of the present invention cannot be obtained.

The feeding time is usually 10 to 300 seconds, preferably 60 to 200 seconds in order to obtain barium sulfate having a suitable particle size. If the supply time is shorter than this range, the degree of supersaturation will be extremely large, so that the barium sulfate crystals will be dendritic, and it will be difficult to obtain the desired smoothness and transparency. On the other hand, if it exceeds this range, the degree of supersaturation is suppressed to a low level, resulting in coarse particles, which tends to deteriorate the feeling of use such as elongation and sticking and the light scattering property.

To exemplify the preferred embodiment of the present invention under the various conditions described above, it is most desirable to satisfy the following conditions (1) and (2) at the same time. (1) Barium hydroxide or barium chloride is used as the barium compound, sulfuric acid is used as the sulfuric acid compound, and the concentration of each aqueous solution is 0.05 to 0.2 mol.
/ Liter, the molar ratio of barium compound and sulfuric acid compound is 1
/ 2 to 2/1, the reaction temperature is 70 to 95 ° C., and (2) an aqueous solution of a barium compound and a sulfuric acid compound is simultaneously introduced into ion-exchanged water, and the barium sulfate concentration at the end of the reaction is 0.
0-2 as much as 003-0.03 mol / l
Supply in 00 seconds.

In carrying out the process according to the invention, various types are possible in relation to the reactor, without departing from the scope of the invention.

The barium sulfate particles produced according to the present invention are as shown in schematic diagrams (b) to (d) in FIG.
Usually, it has a plate-like structure as a whole and a spindle-shaped structure in the cross section AB. The perimeter area ratio (square of perimeter of plate-shaped surface / area of orthogonal projection surface of plate-shaped surface) is usually 12.5 to
40. Here, the area of the orthographic projection surface of the plate-like surface means the area of the orthographic projection surface projected on the plate-like surface, and the perimeter of the plate-like surface is the orthographic projection surface of the plate-like surface. The length of the contour of the projection plane. In addition, the schematic diagram (a) in FIG. 1 shows barium sulfate particles obtained by a conventional manufacturing method, but in such a perfect plate shape having a rectangular cross section AB, the light scattering transmittance described below is obtained. It is lower than the product of the present invention.

Here, the perimeter length area ratio is, for example, the perimeter length area ratio of 30 particles (= square of perimeter of plate-like surface / orthogonal projection of plate-like surface) from a photograph taken with a scanning electron microscope. It can be obtained by calculating the average value of the area of the surface).

The particles have a concentration of 20% by weight and a thickness of 15 μm.
The light scattering transmittance when forming a thin film of m is 55% or more,
It is preferably 60% or more. When it is less than this range, the light diffusivity is low, and when the cosmetic film is used, the effect of suppressing the image clarity tends to be poor, which is not preferable as an extender pigment for cosmetics.

The light scattering transmittance was measured by adding 20% by weight of barium sulfate powder using a dispersion medium and kneading the mixture uniformly to form a thin film with an applicator. Using this as a sample, a haze meter (Murakami Color Research Laboratory, Format: HR-100
Etc.), the parallel light transmittance (Tp) and the scattered light transmittance (Td) are measured, and [Td / (Tp + Td)] × 100
Can be obtained by

Further, the particles contain 20% by weight of a green pigment.
When mixed, the whiteness is 57 or less, preferably 55.5 or less. If it exceeds this range, the transparency tends to be low, and when the cosmetic film is used, the feeling of bare skin tends to be poor, which is not preferable as an extender pigment for cosmetics.

The whiteness is determined by dispersing a green pigment and barium sulfate powder in a dispersion medium, filtering and drying, and using the obtained mixed powder as a sample, a spectrophotometer (manufactured by Hitachi Ltd., model: U-
It can be given by the L value when the color of the mixed powder is digitized by the L, a, and b values.

Further, the barium sulfate particles produced according to the present invention have an aspect ratio (average diameter of plate-like surface / average thickness) of 3 to 100 and well-developed (020) plane, which is When X-ray diffraction is performed, the diffraction peak intensity ratio (I ₍₀₂₀₎ / I of the (020) plane and the (021) plane
₍₀₂₁₎ ) reaches 0.2 to 5. The aspect ratio can also be obtained in the same manner as the above-described peripheral long area ratio.

The average particle size (average diameter of the plate surface)
Is usually 3 to 10 μm, preferably 3 to 7 μm. If it is smaller than this range, the elongation tends to be poor when applied to the skin, and if it is larger than this range, the sticking property after application and the familiarity tend to become poor.

The average particle size is obtained by dispersing barium sulfate powder in an aqueous solution together with a suitable dispersant, measuring the particle size distribution with a particle size distribution measuring device (manufactured by Horiba, Ltd., model: LA-700, etc.), and the cumulative volume is 50. It can be calculated as a particle size which is%.

[0029]

EXAMPLES The present invention will be further described with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these Examples and the like. In this example and the comparative example, the average particle size, aspect ratio, perimeter area ratio, X-ray peak ratio, light scattering transmittance and whiteness were evaluated as follows.

Average Particle Size The barium sulfate suspension synthesized in the present invention was cooled to around room temperature. Next, this suspension is dispersed in a 0.1% aqueous solution of sodium polyacrylate (trade name: Poise 530), and a particle size distribution analyzer (manufactured by Horiba, Ltd., model: LA-7) is used.
00). The average particle size was defined as the particle size at which the cumulative volume was 50%.

Aspect Ratio, Perimeter Area Ratio The barium sulfate suspension synthesized according to the present invention is cooled to around room temperature, filtered through 5C filter paper, and dried at 120 ° C. for 3 hours or more to obtain barium sulfate powder. It was Next, this barium sulfate powder was scanned with a scanning electron microscope (manufactured by JEOL, model: J
It was observed with SM-T-100) and photographed. From the photograph, the aspect ratio of 30 particles (= average diameter of plate-like surface /
The average value of the average thickness) and the perimeter area ratio (= the square of the perimeter of the plate-shaped surface / the area of the orthogonal projection surface of the plate-shaped surface) was calculated.

X-ray peak ratio Barium sulfate powder was manufactured by Rigaku Denki (type: RAD-20
0) CuKα ray, 40kV, 80m using X-ray diffractometer
X-ray diffraction was performed at A, and the (020) plane of the crystal and (021)
The intensity ratio (I ₍₀₂₀₎ / I ₍₀₂₁₎ ) of the surface was calculated.

Light-Scattering Transmittance Amino-modified silicone oil (trade name: SF8417, manufactured by Toray Silicone Co., Ltd.) is used as a dispersion medium, 20% by weight of barium sulfate powder is added and uniformly kneaded, and a thin film of about 15 μm is formed with an applicator. Is formed into a glass plate. Further, this was measured for parallel light transmittance (Tp) and scattered light transmittance (Td) with a haze meter (manufactured by Murakami Color Research Laboratory, model: HR-100), and [Td /
(Tp + Td)] × 100 was defined as the light scattering transmittance.

Whiteness 0.1 g of green pigment CrO (OH) ₂ (trade name: Ginegreen, manufactured by Daito Kasei) and 0.5 g of barium sulfate powder are dispersed in 50 ml of ethanol for 1 hour or more by a magnetic stirrer and filtered. Then, the mixed powder was dried at 100 ° C. for 2 hours or more. 0.5 g of the obtained mixed powder was filled in a powder cell, and a spectrophotometer (manufactured by Hitachi Ltd., model: U) was used.
-4000) and was measured by the reflection method. The color of the mixed powder was digitized by L, a, and b values, and the whiteness of the barium sulfate powder was evaluated by the L value.

Example 1 Special grade reagent 1.893 g of barium hydroxide octahydrate and 0.589 g of special grade reagent sulfuric acid were deionized water to 100 m each.
1 and a solution having a molar ratio of 1 was prepared at 0.06 mol / liter. Further, 1800 ml of ion-exchanged water was charged into a glass separable flask having an internal volume of 2 liters, and the temperature was raised to 95 ° C. while stirring with a Teflon crescent blade. Next, a barium hydroxide solution and a sulfuric acid solution filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm were simultaneously added dropwise in 200 seconds. Then, after stirring was continued at 95 ° C. for 60 minutes, the reaction was terminated (the barium sulfate concentration at the end of the reaction was 0.003 mol.
/liter). Then, the mixture was cooled to room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain 1.10 g of barium sulfate powder.

The powder thus obtained has an average particle size of 5.4.
5 μm, aspect ratio 5, perimeter area ratio 16, X-ray peak ratio 0.3, light scattering transmittance 62.6%, whiteness 50.9
Met.

Example 2 3.155 g of special grade reagent barium hydroxide octahydrate and 0.981 g of special grade reagent sulfuric acid were deionized water to 50 ml each.
And a solution having a molar ratio of 0.20 mol / liter was prepared. In addition, 1900 ml of ion-exchanged water was charged into a glass separable flask having an internal volume of 2 liters,
The temperature was raised to 70 ° C while stirring with a Teflon crescent blade.
Next, a barium hydroxide solution and a sulfuric acid solution filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm were simultaneously added dropwise over 60 seconds. Then 70
After continuing stirring at 60 ° C. for 60 minutes, the reaction was terminated (barium sulfate concentration at the end of the reaction was 0.005 mol / liter). Then, it is cooled to around room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain barium sulfate powder 1.
87 g was obtained.

The powder thus obtained has an average particle size of 4.5.
4 μm, aspect ratio 7, peripheral length area ratio 20, X-ray peak ratio 0.4, light scattering transmittance 61.9%, whiteness 53.9.
Met.

Example 3 2.613 g of special-grade reagent barium nitrate and 4.904 g of special-grade reagent sulfuric acid were made up to 500 ml with distilled water, respectively.
Solutions of 02 and 0.10 mol / liter and a molar ratio of 0.2 were prepared. Further, 1000 ml of ion-exchanged water was charged into a glass separable flask having an inner volume of 2 liters, and the temperature was raised to 50 ° C. while stirring with a Teflon crescent blade. Next, a barium nitrate solution and a sulfuric acid solution filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm were simultaneously supplied into the solution for 250 seconds. Then, the reaction was terminated after continuing stirring at 50 ° C. for 60 minutes (the barium sulfate concentration at the end of the reaction was 0.00
5 mol / liter). Then, cool to around room temperature,
After filtering through a 5C filter paper, it was dried at 120 ° C. for 3 hours to obtain 1.73 g of barium sulfate powder.

The powder thus obtained has an average particle size of 5.3.
7 μm, aspect ratio 20, perimeter area ratio 16, X-ray peak ratio 0.2, light scattering transmittance 63.7%, whiteness 51.
It was 8.

Example 4 Special grade reagent 7.33 g of barium chloride dihydrate and special grade reagent
0.852 g of sodium sulfate was added to each of 5 with deionized water.
A solution of 0.60 and 0.12 mol / liter and a molar ratio of 5 was prepared, respectively. Also the internal volume 2
Tap water in a liter glass separable flask.
Charge 00 ml and stir with a Teflon crescent blade 1
The temperature was raised to 00 ° C., and the generated steam was refluxed by the reflux device. Next, a barium chloride solution and a sodium sulfate solution, which were filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm, were simultaneously added dropwise over 20 seconds.
After that, stirring was continued for 60 minutes while refluxing at 100 ° C., and then the reaction was terminated (barium sulfate concentration at the end of the reaction was 0.003 mol / liter). Then, the mixture was cooled to around room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain 1.27 g of barium sulfate powder.

The powder thus obtained has an average particle size of 4.
68 μm, aspect ratio 10, perimeter area ratio 20, X-ray peak ratio 2, light scattering transmittance 65.0%, whiteness 54.6
Met.

Comparative Example 1 Special grade reagent 9.77 g of barium chloride dihydrate and special grade reagent
3.92 g of sulfuric acid was made up to 50 ml with deionized water,
A solution having a molar ratio of 0.80 mol / liter was prepared. Further, 1900 ml of ion-exchanged water was charged into a glass separable flask having an inner volume of 2 liters, and the temperature was raised to 90 ° C. while stirring with a Teflon crescent blade. next,
A barium chloride solution and a sulfuric acid solution filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm were simultaneously added dropwise over 120 seconds. Then, at 90 ℃ 6
After continuing stirring for 0 minutes, the reaction was terminated (barium sulfate concentration at the end of the reaction was 0.02 mol / liter). Then, cool to around room temperature, filter with 5C filter paper, and then
After drying at 0 ° C. for 3 hours, 7.63 g of powder of barium sulfate was obtained.

The powder thus obtained has an average particle size of 2.
The dendritic shape was 37 μm, the aspect ratio was 30, the peripheral area ratio was 100, and the X-ray peak ratio was 10. The light scattering transmittance was as high as 67.1%, but the whiteness was as high as 64.0.

Comparative Example 2 Special grade reagent 0.997 g of barium chloride dihydrate and 0.568 g of special grade reagent sodium sulfate were made 250 ml each with ion-exchanged water to prepare solutions of 0.016 mol / liter and a molar ratio of 1, respectively. In addition, 1500 ion-exchanged water is placed in a glass separable flask with an internal volume of 2 liters.
90 ml while stirring with a Teflon crescent blade.
The temperature was raised to. Next, a barium chloride solution and a sodium sulfate solution, which were filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm, were simultaneously added dropwise in 240 seconds. Then, after stirring at 90 ° C. for 60 minutes,
The reaction was completed (the barium sulfate concentration at the end of the reaction was
0.002 mol / liter). Then, the mixture was cooled to around room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain 0.49 g of barium sulfate powder.

The powder thus obtained has an average particle size of 1
It had a perfect plate-like shape with a rectangular cross section and an aspect ratio of 10, a peripheral length area ratio of 16, and an X-ray peak ratio of 0.2. The light scattering transmittance was 30.5%, which was extremely low, and the whiteness was 50.0.

Comparative Example 3 Special grade reagent Barium chloride dihydrate (7.33 g) and special grade reagent
Sulfuric acid (0.294 g) was made up to 50 ml with ion-exchanged water to prepare solutions having 1.00 and 0.10 mol / liter and a molar ratio of 10, respectively. In addition, a glass separable flask with an internal volume of 2 liters is charged with 190
Charge 0 ml and stir with a Teflon crescent wing for 90 minutes
The temperature was raised to ° C. Next, a barium chloride solution and a sulfuric acid solution which had been filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm were simultaneously added dropwise over 120 seconds. Then, the reaction was terminated after continuing stirring at 90 ° C. for 60 minutes (the barium sulfate concentration at the end of the reaction was 0.00
25 mol / liter). Then, the mixture was cooled to around room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain 0.56 g of barium sulfate powder.

The powder thus obtained has an average particle size of 2.
Small as 78 μm, aspect ratio 30 and perimeter length area ratio 6
It was 0 and the X-ray peak ratio was 7. Light scattering transmission is 67.6
%, But the whiteness was as high as 57.6.

Comparative Example 4 3.155 g of special grade reagent barium hydroxide octahydrate and 0.981 g of special grade reagent sulfuric acid were deionized water to 100 m each.
1 and a solution having a molar ratio of 0.1 was prepared. Further, 1800 ml of ion-exchanged water was charged into a glass separable flask having an internal volume of 2 liters, and the temperature was maintained at 25 ° C. while stirring with a Teflon crescent blade. Next, a barium hydroxide solution and a sulfuric acid solution filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm were simultaneously added dropwise over 120 seconds. Then, after continuing stirring at 25 ° C. for 60 minutes, the reaction was terminated (the barium sulfate concentration at the end of the reaction was 0.005 mol.
/liter). Then, the mixture was cooled to around room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain 1.90 g of barium sulfate powder.

The powder thus obtained has an average particle size of 4.
It is an aggregate of 09 μm and has an aspect ratio of 1 for primary particles.
The ratio was 0, the perimeter area ratio was 20, and the X-ray peak ratio was 15. The light scattering transmittance was as low as 53.8% and the whiteness was as high as 60.2.

Comparative Example 5 Special grade reagent 15.77 g of barium hydroxide octahydrate and 4.904 g of special grade reagent sulfuric acid were deionized water to 500 m each.
1 and a solution having a molar ratio of 0.1 was prepared. Further, 1000 ml of ion-exchanged water was charged into a glass separable flask having an internal volume of 2 liters, and the temperature was raised to 90 ° C. while stirring with a Teflon crescent moon blade. Next, a barium hydroxide solution filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm was added dropwise in 20 seconds, and a sulfuric acid solution was added in 300 seconds. Then, after continuing stirring at 90 ° C. for 60 minutes, the reaction was terminated (the barium sulfate concentration at the end of the reaction was 0.025 mol.
/liter). Then, it was cooled to around room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain 9.1 g of barium sulfate powder.

The powder thus obtained has an average particle size of 2.
Small as 80 μm, aspect ratio 20 and perimeter area 5
The peak ratio was 0 and the X-ray peak ratio was 8. Light scattering transmission is 60.4
%, But the whiteness was as high as 58.0.

Comparative Example 6 3.155 g of special grade reagent barium hydroxide octahydrate and 0.981 g of special grade reagent sulfuric acid were deionized water to 250 m each.
1 and a solution having a molar ratio of 1 was prepared at 0.04 mol / liter. Further, 1500 ml of ion-exchanged water was charged into a glass separable flask having an internal volume of 2 liters, and the temperature was raised to 90 ° C. while stirring with a Teflon crescent moon blade. Next, a barium hydroxide solution and a sulfuric acid solution filtered through a membrane filter (cellulose acetate membrane, manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.2 μm were simultaneously added dropwise for 500 seconds. Then, after continuing stirring at 90 ° C. for 60 minutes, the reaction was terminated (the barium sulfate concentration at the end of the reaction was 0.005 mol.
/liter). Then, it was cooled to around room temperature, filtered through a 5C filter paper, and dried at 120 ° C. for 3 hours to obtain 1.23 g of barium sulfate powder.

The powder thus obtained has an average particle size of 1
The particles were coarse with 3.53 μm, and the aspect ratio was 5, the peripheral area ratio was 16, and the X-ray peak ratio was 0.3. The light scattering transmittance was as low as 43.6%, and the whiteness was 50.0.

The following is a further description of the embodiment of the present invention. (1) A method for producing barium sulfate, which comprises reacting a solution of barium hydroxide or barium salt with a solution of sulfuric acid or a sulfate salt under the following conditions (a) and (b). (A) The concentration of the aqueous solution of the barium compound and the sulfuric acid compound is both 0.05 to 0.2 mol / liter, the molar ratio of the barium compound to the sulfuric acid compound is 1/2 to 2/1, and the reaction temperature is 70 to 95 ° C. is there. (B) An aqueous solution of a barium compound and a sulfuric acid compound is simultaneously introduced into ion-exchanged water, and the barium sulfate concentration at the end of the reaction is 0.
60-only as much as 003-0.03 mol / liter
Supply in 200 seconds. According to this aspect, the manufacturing method of the present invention can be carried out more suitably.

(2) A solution of barium hydroxide or barium salt and a solution of sulfuric acid or a sulfate salt are mixed with the following (a):
A method for producing barium sulfate, characterized in that the barium sulfate obtained by the reaction under the condition (b) has the following properties (c) to (g). (A) The concentration of the barium compound and the solution of the sulfuric acid compound are both 0.02 to 0.6 mol / liter, the molar ratio of the barium compound to the sulfuric acid compound is 1/10 to 5/1, and the reaction temperature is 50 to 100 ° C. is there. (B) The barium sulfate concentration at the end of the reaction is 0.001-
Supply in an amount of 0.1 mol / liter in 10 to 300 seconds. (C) The light scattering transmittance when forming a thin film having a concentration of 20% by weight and a thickness of 15 μm is 55% or more. (D) The whiteness when mixed with 20% by weight of the green pigment is 57 or less. (E) It has a plate-like structure and its perimeter length area ratio (square of perimeter of plate-like surface / area of orthogonal projection plane of plate-like surface) is 12.5.
-40. (F) Aspect ratio (average diameter of plate-like surface / average thickness) is 3
~ 100. (G) The (020) plane and (021) by X-ray diffraction of the crystal.
The diffraction peak intensity ratio (I ₍₀₂₀₎ / I ₍₀₂₁₎ ) of the surface is 0.2
~ 5.

(3) A solution of barium hydroxide or barium salt and a solution of sulfuric acid or a sulfate salt are mixed in the following (a),
A method for producing barium sulfate, which comprises reacting under the condition (b) to obtain barium sulfate having a plate-like shape and a spindle-shaped cross section as a whole. (A) The concentration of the solution of the barium compound and the sulfuric acid compound is 0.02 to 0.6 mol / liter, the molar ratio of the barium compound to the sulfuric acid compound is 1/10 to 5/1, and the reaction temperature is 50 to 100 ° C. is there. (B) The barium sulfate concentration at the end of the reaction is 0.001-
Supply in an amount of 0.1 mol / liter in 10 to 300 seconds.

[0058]

According to the manufacturing method of the present invention, it has an average particle size of 3 to 10 μm, has a plate-like structure and a spindle-shaped cross section, and has an aspect ratio of 3 to 100 and a peripheral length area ratio of 12.5.
-40, it is possible to stably produce barium sulfate having an X-ray peak ratio of (020) plane to (021) plane of 0.2 to 5. Such a powder has physical properties of a light scattering transmittance of 55% or more and a whiteness of 57 or less, is excellent in feeling in use and hiding, and is useful as an extender pigment for cosmetics.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a perspective view and a sectional view of barium sulfate particles obtained by a conventional method or a production method of the present invention. (A) is based on the conventional method, and (b)-
(D) is based on the manufacturing method of the present invention.

Claims (4)

[Claims] 1. A solution of barium hydroxide or barium salt (hereinafter, referred to as barium compound) and a solution of sulfuric acid or sulfate (hereinafter, referred to as sulfuric acid compound) are prepared according to the following (a) and (b): A method for producing barium sulfate, which comprises reacting under the conditions. (A) The concentrations of the barium compound and the sulfuric acid compound solutions are both 0.02 to 0.6 mol / liter, the molar ratio of the barium compound to the sulfuric acid compound is 1/10 to 5/1, and the reaction temperature is 50 to 100 ° C. (B) The barium sulfate concentration at the end of the reaction is 0.001-
Supply in an amount of 0.1 mol / liter in 10 to 300 seconds 2. The method according to claim 1, wherein the barium compound is barium hydroxide or barium chloride, and the sulfuric acid compound is sulfuric acid. 3. The obtained barium sulfate has the following (c):
The manufacturing method according to claim 1 or 2, which has the properties (d) and (e). (C) Light scattering transmittance of 55% or more when a thin film having a concentration of 20% by weight and a thickness of 15 μm is formed, (d) Whiteness of 57% or less when 20% by weight of a green pigment is mixed, (e) It has a plate-like structure and its perimeter length area ratio (square of perimeter of plate-like surface / area of orthogonal projection plane of plate-like surface) is 12.5.
~ 40 4. The average particle size of the obtained barium sulfate is 3 to.
It is 10 micrometers, The manufacturing method in any one of Claims 1-3.