JP6696191B2 - Spherical barium sulfate and method for producing the same - Google Patents

Description

The present invention relates to spherical barium sulfate and a method for producing the same.

Inorganic particles are often blended as a functional material in applications where cosmetic extensibility to the skin, that is, slipperiness is required. The inorganic particles include plate-like particles and spherical particles, and the spherical particles have a role of further improving the slip of the plate-like particles. As the inorganic particles, barium sulfate is used because it is poorly soluble in acids and alkalis, has low solubility in water and organic solvents, and is inexpensive and easily chemically synthesized. There is. Patent Documents 1 and 2 disclose conventional spherical barium sulfate.

JP-A-8-225316 JP, 2011-15727, A

However, conventional spherical barium sulfate has a low sphericity, and may contain impurities such as sulfide and soluble barium salt which are harmful to the human body, and therefore safety is also a concern. In addition, since barium sulfate generally has a large specific gravity, for example, when it is blended in a cosmetic composition, it tends to settle, and when applied to the skin surface, it feels heavy, and the dry and light feel required in summer is There is a problem of conflict. However, barium sulfate particles having a low specific gravity may be easily crushed. Particles that are easily crushed, that is, particles having low strength, will be crushed when rubbed against the skin, for example, and the feel will be poor. From these points of view, the conventional spherical barium sulfate has not yet reached a practical level.

Patent Document 1 describes spherical barium sulfate and a method for producing the same. The spherical barium sulfate obtained in the examples is obtained by reacting a water-soluble barium salt with a water-soluble sulfate, filtering, and drying. There is. The particles obtained by such a method are presumed to have a large specific gravity, so that a good feeling cannot be obtained, and the safety is concerned because of the large amount of impurities. Further, as another manufacturing method, it is described that a dispersion liquid of fine barium sulfate having a particle size of 0.1 μm or less may be spray-dried, but the spherical barium sulfate obtained by such a manufacturing method has insufficient strength. It is thought that there are many impurities. Patent Document 2 discloses an aggregate of granular barium sulfate and describes that a dispersion of barium sulfate particles is spray-dried as a manufacturing method. However, the barium sulfate particles obtained by such a manufacturing method have a high strength. It is considered not to be sufficient and there are many impurities. Therefore, in any of Patent Documents 1 and 2, spherical barium sulfate particles having a small specific gravity, sufficient strength and safety are not obtained.

In view of the present situation, the present invention provides a spherical barium sulfate having a low specific gravity and a high sphericity, having sufficient strength, excellent slipperiness and safety, and having an extremely good feel, and It is an object of the present invention to provide a manufacturing method for realizing such spherical barium sulfate.

The present inventors have variously studied the method for producing spherical barium sulfate, and after spray-drying a slurry of barium sulfate particles having a predetermined particle size, by firing at a predetermined temperature, low specific gravity and sphericity It was found that spherical barium sulfate having a high degree of elasticity, sufficient strength, excellent slipperiness and safety, and a very good feel can be obtained, and the present invention has been completed.

That is, in the present invention, the step (1) of spray-drying a slurry of barium sulfate particles having an average primary particle size of 0.005 to 0.25 μm, and the dried product obtained in the step (1) at 200 to 1100 ° C. A method for producing spherical barium sulfate including the step (2) of firing.

The firing time in the step (2) is preferably 0.5 to 12 hours. As a result, the primary particles forming the spherical barium sulfate are sintered together, and the resulting spherical barium sulfate particles become more dense, so that the strength is further increased, and it is possible to obtain spherical barium sulfate having a better feel. become.

The present invention also provides a spherical barium sulfate having an average particle diameter of 0.5 to 100 μm, a sphericity of 1.0 to 1.2, and a true specific gravity of 4.45 or less,
Further, it is also a spherical barium sulfate having a D90 / D10 of 4.5 or less after irradiating an ultrasonic wave having a frequency of 20 kHz and an output of 75 W for 2 minutes with respect to 100 ml of the water slurry having a spherical barium sulfate concentration of 20 g / L. ..

The spherical barium sulfate is preferably compatible with "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006". This makes it even more useful for applications requiring strict safety standards, such as cosmetics, pharmaceuticals, and quasi drugs.

The spherical barium sulfate is preferably obtained by the production method of the present invention described above. By adopting the production method of the present invention, the spherical barium sulfate of the present invention can be obtained easily and easily.

According to the method for producing spherical barium sulfate of the present invention, it is possible to obtain spherical barium sulfate having a low specific gravity, a high sphericity, a sufficient strength, excellent slipperiness and safety, and an extremely good feel. In particular, the production method of the present invention makes it possible to obtain spherical barium sulfate that is compatible with "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006". Further, the spherical barium sulfate obtained by the production method of the present invention, and the spherical barium sulfate of the present invention is highly safe, and since it can give the dry and light feel required in summer, etc., cosmetics It is particularly useful as a raw material for and is very suitable for the needs of the market. In addition, it is also useful as a sebum adsorbent because it has excellent sebum adsorption power. In addition to cosmetics, it is also useful for various applications such as pharmaceuticals, quasi drugs, radiation shielding materials, paints, resin materials, catalysts, printing toners and lubricants.

1 is an electron micrograph of spherical barium sulfate obtained in Example 1. 3 is an electron micrograph of spherical barium sulfate obtained in Example 2. 5 is an electron micrograph of spherical barium sulfate obtained in Example 3. 5 is an electron micrograph of spherical barium sulfate obtained in Example 4. 5 is an electron micrograph of spherical barium sulfate obtained in Example 5. 7 is an electron micrograph of spherical barium sulfate obtained in Example 6. 3 is an electron micrograph of barium sulfate obtained in Comparative Example 1. 5 is an electron micrograph of spherical barium sulfate obtained in Comparative Example 2. 5 is an electron micrograph of spherical barium sulfate obtained in Comparative Example 3. 5 is an electron micrograph of spherical barium sulfate obtained in Comparative Example 4. It is an electron micrograph of arsenic barium sulfate (Comparative Example 5). 3 is an electron micrograph of a particle cross section of the spherical barium sulfate obtained in Example 2 (Example 2-a). 3 is an electron micrograph of a particle cross section of spherical barium sulfate obtained in Example 2 (Example 2-b). It is an electron micrograph image | photographed after performing the particle strength confirmation test about the spherical barium sulfate obtained in Example 1 (Example 1-a). It is an electron micrograph image | photographed after performing the particle strength confirmation test about the spherical barium sulfate obtained in Comparative Example 2 (Comparative Example 2-a).

Hereinafter, one example of the present invention will be specifically described, but the present invention is not limited to the following description, and can be appropriately modified and applied within a range not changing the gist of the present invention.

<Method for producing spherical barium sulfate>
The method for producing spherical barium sulfate, which is the first aspect of the present invention, will be described.
The method for producing spherical barium sulfate of the present invention includes a step (1) of spray-drying a slurry of barium sulfate particles and a step (2) of firing the dried product obtained in the step (1), but it is necessary. It may include one or more other steps depending on the type. Other steps are not particularly limited.

Here, the dried product obtained in the step (1) is spherical particles, and may be an aggregate or an aggregate of primary particles of barium sulfate particles. In the present specification, this dried product is also referred to as "dried product of barium sulfate particles" or "dried product of spherical barium sulfate particles".
The product (spherical barium sulfate) finally obtained through the step (2) is spherical particles, and may be an aggregate or agglomerate of primary particles of barium sulfate particles, or may be precipitated barium sulfate. Is preferred. In the present specification, the product (spherical barium sulfate) finally obtained through the above step (2) is also referred to as “spherical barium sulfate particles”. The production method of the present invention can also be referred to as a production method of barium sulfate spherical agglomerates or a production method of precipitated spherical barium sulfate.

First, the step (1) will be described.
The step (1) is a step of spray-drying a slurry of barium sulfate particles (also simply referred to as a slurry). By passing through the spray drying step, the obtained dried product of barium sulfate particles becomes spherical, and since some voids are formed inside, a dried product of spherical barium sulfate particles having a small specific gravity can be obtained.

The method of spray drying (also referred to as spray drying) is not particularly limited, but it is preferable to spray the slurry by a nozzle system such as a two-fluid system or a rotating disk system. For example, a spray dryer can be used, and in that case, the rotation speed of the rotating disk is not particularly limited, but is preferably 15,000 to 25,000 rpm. The inlet temperature and the outlet temperature are not particularly limited, but it is preferable to set the outlet temperature to 90 ° C or higher (more preferably 90 to 140 ° C).

The slurry to be spray-dried is not particularly limited as long as it contains barium sulfate particles, but it is preferable that the barium sulfate particles are dispersed in a liquid medium. The liquid medium is not particularly limited, and water and organic solvents (for example, alcohols, silicone oils, glycols) can be used.

The above-mentioned slurry may contain a dispersant, an organic binder, etc., if necessary, within a range that does not impair the effects of the present invention. Examples of usable dispersants include SN Dispersant 5468 (manufactured by San Nopco).

The barium sulfate particles used in the above slurry have an average primary particle diameter of 0.005 to 0.25 μm. By using barium sulfate particles having an average primary particle diameter within this range, spherical barium sulfate particles having a low specific gravity and high sphericity can be obtained. It is preferably 0.01 to 0.25 μm. If the particle size exceeds 0.25 μm, the resulting dried product will have an irregularly shaped shape with corners, and if a spherical dried product cannot be obtained, or the aggregation of primary particles of barium sulfate particles will weaken. However, even if firing is performed, sufficient strength cannot be obtained.
In the present specification, the “average primary particle diameter” is a value obtained by the method described in Examples below.

The shape of the barium sulfate particles used in the slurry is not particularly limited.
As the barium sulfate particles used in the above slurry, commercially available barium sulfate particles (for example, Varifine (R) BF series manufactured by Sakai Chemical Industry Co., Ltd., Variclear (R) series manufactured by Resino Color Industry Co., Ltd.) may be used. However, barium sulfate particles obtained by the reaction of barium hydroxide and sulfuric acid may be used, or soluble barium salts (barium sulfide, barium chloride, barium nitrate, etc.) and sulfuric acid or soluble sulfates (sodium sulfate, ammonium sulfate, etc.) You may use the barium sulfate particle obtained by the reaction with a). Above all, it is more preferable to use barium sulfate particles obtained by the reaction between barium sulfide or barium hydroxide and sulfuric acid, or the reaction between barium chloride and sodium sulfate, and the content of impurities (by-products from the reaction) is lower. From the viewpoint, it is more preferable to use barium sulfate particles obtained by the reaction of barium hydroxide and sulfuric acid.

Further, as described above, it is preferable to use at least one selected from the group consisting of barium hydroxide, barium sulfide and barium chloride as the barium source. Among them, it is preferable to use barium sulfide and / or barium hydroxide as the barium source, which allows spherical particles that are more suitable and more comfortable to the "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006". Barium sulfate can be easily obtained.

The pH during the reaction between the barium source and sulfuric acid or soluble sulfate for obtaining the barium sulfate particles used in the above-mentioned slurry is not particularly limited, but may be set so as to be maintained within the range of 4 to 10, for example. preferable. By setting it within this range, the generation of by-products such as soluble barium salt can be more sufficiently suppressed. Further, the pH of the slurry of barium sulfate particles is also preferably within this range. It is particularly preferable to set the pH according to the barium source used as the raw material. For example, when barium sulfide is used as the barium source, the pH is preferably 5-9, more preferably 6-8. When barium hydroxide is used as the barium source, the pH is preferably 4-10, more preferably 6-9. When barium chloride is used as the barium source, the pH is preferably 5-10, more preferably 5-8.

The method for preparing the slurry is not particularly limited, for example, commercially available barium sulfate particles and, after the reaction between the barium source and sulfuric acid or soluble sulfate, filtered, washed with water, barium sulfate particles obtained by drying, water, It may be prepared by repulping into a pulp, or the slurry after the reaction between the barium source and sulfuric acid or soluble sulfate may be used as it is.

The viscosity of the slurry is not particularly limited, but is preferably 1 to 2000 mPa · s, for example. When the viscosity is within this range, spray drying is more preferably performed. It is preferably 1 to 1000 mPa · s, more preferably 10 to 900 mPa · s. When the viscosity of the slurry is more than 2000 mPa · s, a spherical dried product may not be obtained such that the dried product obtained after spray-drying may have a dent, which is not preferable.
In the present specification, the “viscosity of slurry” is a value obtained by the method described in Examples below (measured at 20 ° C.).

Next, the step (2) will be described.
Step (2) is a step of firing the dried product obtained in step (1).
Conventionally, spherical barium sulfate was usually used without being fired (see Patent Documents 1 and 2). It is presumed that this is because the firing efficiency, which exceeds the labor and cost of firing, has not been found. Contrary to such conventional recognition, the present inventors sinter the primary particles constituting the spherical barium sulfate, thereby making it possible to obtain more dense and strong spherical barium sulfate. did. In the case of unbaking, the strength of the obtained particles is not sufficient, so that when the particles are rubbed into the skin, for example, the particles are crushed and the feeling is deteriorated. On the other hand, by firing, the particle strength becomes sufficient and the feel becomes good. In addition, since sulfides are sufficiently reduced by firing, spherical barium sulfate that is suitable for "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006" can be obtained.

The firing temperature in the step (2) is 200 to 1100 ° C. When the firing temperature is within this range, the primary particles constituting the spherical barium sulfate are sintered together, and it becomes possible to obtain more dense and strong spherical barium sulfate. In order to eliminate uneven firing, it is preferable to perform firing so as to have a uniform temperature distribution. If the firing temperature is less than 200 ° C, spherical barium sulfate having high strength cannot be obtained, and if the firing temperature exceeds 1100 ° C, the spherical barium sulfate particles are fused and spherical particles cannot be obtained.

It is particularly preferable to set the firing temperature according to the barium source used as the raw material for the barium sulfate particles in the slurry used in step (1).
For example, when barium hydroxide is used as the barium source, the firing temperature is preferably 200 to 650 ° C. As a result, spherical barium sulphate is obtained which is less likely to collapse in shape, has higher strength, and is closer to a true sphere. The temperature is more preferably 200 to 600 ° C., whereby reduction of impurities can be expected.
When barium sulfide is used as the barium source, the firing temperature is preferably 750 to 1100 ° C. This further reduces the risk of sulfide formation, and provides spherical barium sulfate with higher safety. More preferably, it is 800 to 950 ° C.
When barium chloride is used as the barium source, the firing temperature is preferably 450 ° C to 750 ° C. As a result, spherical barium sulphate is obtained which is less likely to collapse in shape, has higher strength, and is closer to a true sphere. More preferably, it is 500 ° C to 700 ° C.

The firing time is preferably 0.5 to 12 hours, for example. As a result, the primary particles forming the spherical barium sulfate are sintered together, and it becomes possible to easily obtain a denser and stronger spherical barium sulfate. It is more preferably 0.5 to 5 hours. Even if the firing time exceeds 12 hours, an effect commensurate with the firing time may not be obtained, and the productivity may not be improved, which is not preferable.

In the present specification, the "calcination temperature" means the maximum temperature during the baking. "Baking time" means the holding time of the maximum temperature at the time of baking, and does not include the temperature rising time until the maximum temperature is reached. The temperature raising time is not particularly limited, but it is preferable to make it as short as possible.

The calcination method is not particularly limited, and may be, for example, a fluidized bed calcination method or a fixed bed calcination method. The firing atmosphere is not particularly limited, and the firing may be performed in an inert gas atmosphere such as an air atmosphere or a nitrogen or argon atmosphere.

In the above manufacturing method, the step (2) (baking step) may be repeated a plurality of times as necessary. When the firing step is repeated a plurality of times, it is preferable that the total firing time be within the above-mentioned preferable firing time range.

In the above production method, the obtained barium sulfate spherical aggregate (spherical barium sulfate) may be washed with water and dried, if necessary.

<Spherical barium sulfate>
The spherical barium sulfate which is the second embodiment of the present invention will be described.
The spherical barium sulfate of the present invention is a particle having an average particle diameter, a sphericity and a true specific gravity within predetermined ranges, and having a D90 / D10 of 4.5 or less after being irradiated with ultrasonic waves under predetermined conditions. Such spherical barium sulfate can be easily and conveniently obtained by the production method of the present invention described above.

The average particle diameter of the spherical barium sulfate is 0.5 to 100 μm. When the average particle diameter is within this range, it becomes easy to handle and has excellent feel and slipperiness, and is useful for various applications. Especially when used for direct contact with skin such as cosmetics, the average particle size is within this range, so that when applied to the skin, there is no squeaky or rough feel, and it feels good. Become. The thickness is preferably 1 to 50 μm, more preferably 1 to 30 μm.
In the present specification, the "average particle size" means that a diagonal line is drawn on an image taken by a field emission scanning electron microscope (JSM-7000F, manufactured by JEOL Ltd.), and the major axis and the minor axis of 100 particles on the line. It means the arithmetic average particle diameter obtained by measuring the diameter and calculating "(major diameter + minor diameter) / 2".

The sphericity of the spherical barium sulfate is 1.0 to 1.2. When the sphericity is within this range, the feel and slipperiness are excellent, and the sphericity is useful for various applications. It is preferably 1.09 or less, more preferably 1.07 or less, still more preferably 1.05 or less.
In the present specification, the "sphericity" is a value obtained by the method described in Examples below. High sphericity means that the sphericity is close to a sphere, that is, close to 1.0.

The true specific gravity of the spherical barium sulfate is 4.45 or less. Since the true specific gravity of this range is smaller than that of conventional barium sulfate particles, it is useful for various applications. For example, when blended in cosmetics, the risk of sedimentation is reduced, and when it is applied to the surface of the skin, it gives a dry and light feel, and therefore meets market needs. It is preferably 4.42 or less, more preferably 4.40 or less. Further, it is preferably 1 or more from the viewpoint of handleability and the like.
In the present specification, the “true specific gravity” is a value obtained by the method described in Examples below.

The average friction coefficient of the spherical barium sulfate is preferably 0.6 or less. When the average coefficient of friction is in this range, the feel and the slipperiness are excellent, and it is useful for various applications, especially for direct skin contact such as cosmetics. It is more preferably 0.59 or less, still more preferably 0.57 or less.
In the present specification, the “average friction coefficient” is a value obtained by the method described in Examples below.

The spherical barium sulfate, water slurry (i.e., the spherical barium sulfate 20 g / prepared aqueous slurry to be L) spherical barium sulfate concentration is 20 g / L to 100 ml, frequency 20 kHz, output 75W super The particles have a D90 / D10 of 4.5 or less after being irradiated with a sound wave for 2 minutes. When the strength of the particles is low, the particles are crushed when an external impact is applied, and the crushed particles are partially aggregated to cause a broad peak in the particle size distribution chart. That is, the sharp peaks in the particle size distribution chart, even when subjected to an external impact of ultrasonic waves of the above strength, means that the particles are not easily broken. Since such particles have sufficient strength, they do not break even when rubbed against the skin, and have a good feeling. If D90 / D10 exceeds 4.5 after irradiation under the above-mentioned conditions, the strength of the particles is not sufficient and the particles are broken when rubbed into the skin, resulting in poor feel. It is preferably 4 or less, more preferably 3.5 or less, still more preferably 3.3 or less.
In the present specification, "D90 / D10 after irradiating ultrasonic waves having a frequency of 20 kHz and an output of 75 W for 2 minutes with respect to 100 ml of an aqueous slurry having a spherical barium sulfate concentration of 20 g / L" means the examples described later. “D90” (particle diameter at which the cumulative value from the small particle side is 90% of the total particle volume) obtained by the calculation method of “4, (2) Particle intensity (with ultrasonic irradiation)” described in It is a value divided by "D10" (particle diameter at which the cumulative value from the small particle side is 10% of the total particle volume).

The spherical barium sulfate preferably has a change rate of D50 within ± 40% before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes). If the rate of change is within ± 40%, the particles are less likely to be crushed even if an external shock of irradiating an ultrasonic wave with a frequency of 20 kHz and an output of 75 W for 2 minutes is applied, so that the particles are less likely to be crushed. This means that the change in D50 is small. Since such particles have sufficient strength, the particles do not break even when they are rubbed on the skin and have a better feeling.
In the present specification, “the change rate of D50 before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes)” refers to a method of calculating “5, (1) change rate of D50” described in Examples below. Is a value obtained by

The spherical barium sulfate preferably has a change rate of D90 / D10 within ± 40% before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes). If the rate of change is within ± 40%, there is almost no change in the particle size distribution because the particles are less likely to be crushed even if an external shock of irradiating ultrasonic waves with a frequency of 20 kHz and an output of 75 W for 2 minutes is applied. This shows that the change in D90 / D10 is small compared to the case where no impact is applied. Since such particles have sufficient strength, they do not break even when they are rubbed on the skin and have a better feeling.
In the present specification, the "rate of change of D90 / D10 before and after ultrasonic irradiation (frequency 20 kHz, output 75 W x 2 minutes)" means "5, (2) rate of change of D90 / D10" described in Examples below. (%) ”Is a value obtained by the calculation method.

The specific surface area of the spherical barium sulfate is preferably 0.1 to 30 m ² / g, for example. When the specific surface area is within this range, it has more sufficient strength and is more excellent in slipperiness and feel. In addition, the sebum adsorbing power becomes more excellent. It is more preferably 0.2 to 29 m ² / g, further preferably 0.3 to 28 m ² / g, and particularly preferably 0.4 to 25 m ² / g.

The spherical barium sulfate preferably satisfies any one or more of the following (i) to (iii). That is, it is preferable to meet at least one of the purity items of the hydrochloric acid-soluble substance, the soluble barium salt and the sulfide specified in “Barium sulfate” described in “Standards for Quasi-drug Raw Materials 2006”. Above all, it is more preferable that at least the following (i) is satisfied, and it is further preferable that all of the following (i) to (iii) are satisfied. As a result, it becomes more excellent in safety, and thus it can be suitably applied to applications such as cosmetics, pharmaceuticals, and quasi-drugs that require strict safety standards. Particularly preferably, it conforms to "barium sulfate" described in "Quasi-drug raw material standard 2006".
(I) Conform to the purity item of the hydrochloric acid-soluble substance specified in "Barium sulfate" described in "Quasi-drug raw material standard 2006". That is, the amount of the residue determined according to the purity test (4) (hydrochloric acid soluble matter) of the same standard is 15 mg or less.
(Ii) Conform to the purity item of soluble barium salt specified in the above standard. That is, the liquid obtained according to the purity test (4) (soluble barium salt) of the same standard should not become cloudy.
(Iii) Shall meet the sulfide purity items specified in the above standards. That is, lead acetate paper obtained according to the purity test (3) (sulfide) of the same standard should not turn black.

The spherical barium sulfate preferably has, for example, a proportion of sebum adsorbed on the spherical barium sulfate of 15% by mass or more. It is more preferably 18% by mass or more, still more preferably 20% by mass or more. Although the upper limit is not particularly limited, it is preferably 50% by mass or less depending on the formulation to be mixed.
In the present specification, the "proportion of sebum adsorbed on spherical barium sulfate" is the "proportion of sebum adsorbed on powder (mass%)" obtained in the "11, sebum adsorption force" test described in Examples below. It is.

<Use>
The spherical barium sulfate obtained by the first aspect (production method) of the present invention, and the spherical barium sulfate of the second aspect are both low in specific gravity and high in sphericity and have sufficient strength. It has excellent slipperiness and safety, and has extremely good feel. Therefore, it is preferably blended in various products such as cosmetics, pharmaceuticals, quasi-drugs, radiation shielding materials, paints, resin materials, catalysts, printing toners and lubricants. Among them, it is particularly suitable for cosmetics. Thus, the spherical barium sulfate obtained by the production method of the present invention or the cosmetic material containing the spherical barium sulfate of the present invention is one of the preferred embodiments of the present invention.

The cosmetic contains spherical barium sulfate obtained by the production method of the present invention or the spherical barium sulfate of the present invention, so that it has good slipperiness and can give a dry and light feel required in summer and the like. It is extremely comfortable to touch, and is expected to have a soft focus effect and sebum adsorption effect. Therefore, it is particularly suitable for the needs of the recent market. The cosmetics are not particularly limited, and examples thereof include foundations, makeup bases, eye shadows, blushers, mascaras, lipsticks, sunscreen agents, degreasing papers, etc., but foundations are particularly preferable.

The following examples are provided to explain the present invention in detail, but the present invention is not limited to these examples.
In addition, in the following Examples and Comparative Examples, various physical properties and the like were evaluated as follows.

1. Slurry viscosity Measured at 20 ° C. using a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.).

2. Average primary particle size A diagonal line was drawn on an image taken by a field emission scanning electron microscope (JSM-7000F, manufactured by JEOL Ltd.), and the major axis and minor axis of 30 particles on the line were measured. The arithmetic average particle diameter obtained by "(major axis + minor axis) / 2" was defined as the average primary particle diameter.
When measuring the average primary particle size of barium sulfate particles in the slurry, the slurry is filtered, washed with water, and then dried at 105 ° C. for 2 hours using a constant temperature dryer (SONW-450 manufactured by As One Co.). The particles obtained are used.

3, specific surface area (BET specific surface area)
The measurement was performed using a fully automatic specific surface area measuring device (Macsorb (R) HM model-1220, manufactured by Mountech Co., Ltd.).

4. Particle size distribution and particle strength (1) Particle size distribution (no ultrasonic irradiation except for the measuring device)
The particle size distribution was determined under the following measurement conditions A, and the particle sizes at which the volume cumulative values from the small particle side were 10%, 50%, and 90% of the total particle volume were D10, D50, and D90, respectively.
-Measurement condition A-
Device: Laser diffraction / scattering particle size distribution measurement device (MT3300, manufactured by Nikkiso Co., Ltd.)
Solvent: 0.2 mass% sodium hexametaphosphate aqueous solution Dispersion condition in the apparatus: 40 W in the apparatus, irradiation for 10 seconds

(2) Particle strength (with ultrasonic irradiation)
To a 200 ml beaker, 2 g of the powder obtained in each of Examples and Comparative Examples was added to 100 ml of water to prepare 100 ml of a 20 g / L slurry. For 100 ml of the obtained slurry, an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., US-600) was used with a chip size of 26φ, the frequency was set to 20 kHz, the vibration amplitude was set to 50 to 60 μm, and the ultrasonic wave was set to 200 μA (output 75 W). Was irradiated for 2 minutes.
Then, after filtering with 5c filter paper (5 type C filter paper) and drying the filtered material for 2 hours at 105 ° C., the particle size distribution of the obtained powder (particles) is measured under the following measurement condition B. The particle diameters at which the cumulative volume values are 10%, 50%, and 90% of the total particle volume are D10, D50, and D90, respectively. The value of "D90 / D10" was calculated by dividing "D90" thus obtained by "D10".
-Measurement condition B-
Device: Laser diffraction / scattering particle size distribution measurement device (MT3300, manufactured by Nikkiso Co., Ltd.)
Solvent: 0.2 mass% sodium hexametaphosphate aqueous solution Dispersion condition in the device: 40 W in the device, irradiation for 10 seconds

5. Rate of change before and after ultrasonic irradiation (frequency 20 kHz, output 75 W x 2 minutes) "(1) Particle size distribution (without ultrasonic irradiation other than measuring device)" in "4. Particle size distribution and particle strength" (hereinafter, The change rate of D50 and D90 / D10 of “(2) Particle intensity (with ultrasonic irradiation)” (hereinafter referred to as particle size distribution B) with respect to the particle size distribution A was calculated using the following formulas. ..
(1) D50 change rate (%)
(“D50 value obtained with particle size distribution B” − “D50 value obtained with particle size distribution A”) / (“D50 value obtained with particle size distribution A”) × 100
(2) D90 / D10 change rate (%)
("Value of D90 / D10 obtained in particle size distribution B"-"Value of D90 / D10 obtained in particle size distribution A") / ("Value of D90 / D10 obtained in particle size distribution A") x 100

6. Average particle diameter A diagonal line was drawn on an image taken by a field emission scanning electron microscope (JSM-7000F, manufactured by JEOL Ltd.), and the major axis and minor axis of 100 particles on the line were measured. The arithmetic average particle size obtained by "(major axis + minor axis) / 2" was defined as the average particle size.

7. True Specific Gravity The true specific gravity was measured according to the following measuring method using a Gerysack type specific gravity bottle (manufactured by AS ONE).
-Measurement method-
1) After placing the electronic balance horizontally, weigh about 10 g of the sample.
2) After measuring the weight W ₀ of the pycnometer, put the sample in the pycnometer with a funnel, and weigh the weight W (mass when the sample is put in the pycnometer).
3) About half or more of water or n-butanol is put into the specific gravity bottle of the above 2, put in a desiccator, and deaerated for 2 hours with an aspirator.
4) After degassing, add water or n-butanol until the specific gravity bottle of 3 above is filled.
5) After putting the specific gravity bottle of the above 4) in a constant temperature bath of 20 ° C. for 30 minutes, the weight W ₂ of the specific gravity bottle at that time (mass when the specific gravity bottle was filled with the sample and water or n-butanol) was measured. measure.
6) The above steps 3) to 5) are performed without placing the sample in the specific gravity bottle, and the weight W _{1 of the} specific gravity bottle (mass when the specific gravity bottle is filled with water or n-butanol) is measured.
7) Using W ₀ , W, W ₁ and W ₂ (all units are g) obtained as described above, calculate D (specific gravity at 20 ° C .; g / cm ³ ) calculated by the following formula 1. , With true specific gravity. In the formula, D ₁ is the specific gravity (20/20 ° C.) of the solvent (water or n-butanol).

8. A diagonal line was drawn on the image photographed with a sphericity field emission scanning electron microscope (JSM-7000F, manufactured by JEOL Ltd.), and the major axis and minor axis of 100 particles on the line were measured. The average value of “major axis / minor axis” of each particle was defined as the sphericity.

9. Feeling (1) Average friction coefficient Using a friction tester (KES-SE manufactured by Kato Tech Co., Ltd.), a double-sided tape is attached to a slide glass, the sample is placed on the adhesive surface, and the sample is evenly spread with a cosmetic sponge. Then, the friction element was set and measured.
(2) Sensory test For 13 panelists, an appropriate amount of the powder obtained in each of Examples and Comparative Examples was applied to the back of a hand, and the slipperiness when stretched with a finger was "slip is particularly good and elongation was particularly good (4. 4 points of "point"), "slip is good, stretch is good (3 points)", "slightly rough or squeaky (2 points)", "rough or squeaky (1 point)" The score was evaluated by. The average value of each evaluation was obtained, and the slipperiness was evaluated according to the following criteria.
-Criteria-
◎: 3.0 points or more ○: 2.5 points or more and less than 3.0 points △: 2 points or more and less than 2.5 points ×: less than 2 points

10. Impurity (1) Sulfide The purity test (3) (sulfide) of "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006" (sulfide) was performed to determine the presence or absence of sulfide. Specifically, it was determined that the sulfide was detected when the lead acetate paper turned black, and the sulfide was not detected when the lead acetate paper did not turn black.
(2) Hydrochloric acid-soluble product "Barium sulfate" purity test (4) (hydrochloric acid-soluble product) described in "Quasi-drug raw material standard 2006" was performed to determine the amount of residue (mg).
(3) Soluble barium salt A purity test (4) (soluble barium salt) of "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006" (soluble barium salt) was performed to determine the presence or absence of the soluble barium salt. Specifically, it was determined that the soluble barium salt was detected when the solution became cloudy, and that the soluble barium salt was not detected when the solution was not cloudy.

11. Sebum adsorption power 0.5 g of the sample powder (sample) and 2.5 g of artificial sebum (a mixture of oleic acid, squalene and olive oil) were diluted with isopropanol (IPA) and mixed in a centrifuge tube. After standing for 30 minutes, the powder and the solvent were separated by centrifugation, and the separated solvent was transferred onto an aluminum foil by a hydraulic press. After measuring the IR spectrum of the transferred sebum (measuring instrument: NICOLET iS10, manufactured by Thermo Fisher Scientific Co., Ltd.) and calculating the peak area of C—H bond near 3040 to 2780 cm ⁻¹ , the sebum amount and the peak area The amount of sebum was calculated back from the peak area based on a calibration curve (R ² ≈0.98, which is the square of the correlation coefficient) having a correlation with. The amount of sebum before and after mixing with the sample powder was compared, and the amount of sebum reduced by the mixing was defined as "the amount of sebum adsorbed on the powder (g)" (measurement was performed 3 times, and the average value thereof is shown in Table 3). did). Using this "amount of sebum adsorbed on the powder (g)", the "ratio (mass%) of sebum adsorbed on the powder" was calculated by the following calculation formula.
Percentage of sebum adsorbed on the powder (mass%) = (amount of sebum adsorbed on the powder (g)) / (total amount of sebum input 2.5 g) × 100

[Examples 1 to 3]
40 L of 0.42 mol / L barium hydroxide aqueous solution and 12 L of 1.33 mol / L dilute sulfuric acid were simultaneously injected into the reaction vessel so as to maintain pH 7 to 10 to obtain a slurry of barium sulfate particles 70 g / L.
The obtained slurry was spray-dried using a spray dryer (manufactured by Ashizawa, Niro atomizer) at a rotation speed of 16850 rpm and an outlet temperature of 98 to 115 ° C. The obtained dried product was fired at the temperature and time shown in Table 1 to obtain barium sulfate spherical aggregates.
In addition, in order to confirm the average primary particle diameter of the barium sulfate particle slurry, the slurry was filtered, washed with water, and then dried at 105 ° C. for 2 hours using a constant temperature dryer (SONW-450 manufactured by As One Co.), and an electric field was applied. Using an emission scanning electron microscope (JSM-7000F, manufactured by JEOL Ltd.), the average primary particle diameter was calculated as 0.02 μm according to the above-mentioned calculation method of “2, average primary particle diameter”.

[Example 4]
1 kg of barium sulfate (Varifine (R) BF-1, manufactured by Sakai Chemical Industry Co., Ltd., average primary particle diameter 0.05 μm, BET specific surface area 23.4 m ² / g) obtained by reaction of barium sulfide and sulfuric acid is repulped in water. Then, a slurry of 100 g / L barium sulfate particles was prepared.
The slurry thus obtained was spray-dried using a spray dryer (a disk atomizer manufactured by Okawara Kakoki Co., Ltd.) at a rotation speed of 20000 rpm and an outlet temperature of 90 ° C. or higher to obtain a dried product. The obtained dried product was calcined at 900 ° C. for 0.5 hour to obtain a barium sulfate spherical aggregate.
The average primary particle diameter of the slurry of barium sulfate particles was calculated by the same method as that described in Example 1, and it was 0.05 μm.

[Example 5] A 1.5 mol / L barium chloride aqueous solution and a 1.5 mol / L sodium sulfate aqueous solution were simultaneously injected into a reaction vessel to obtain a slurry having 160 g / L of barium sulfate particles. The obtained slurry was filtered and washed with water, and then the obtained filter cake was repulped to prepare a slurry of 35 g / L barium sulfate particles. This slurry was spray-dried using a spray dryer (manufactured by Okawara Kakoki Co., Ltd., disk atomizer) at a rotation speed of 20000 rpm and an outlet temperature of 90 ° C or higher to obtain a dried product. The obtained dried product was calcined at 600 ° C. for 1.0 hour, then washed with water and dried to obtain a barium sulfate spherical aggregate. The average primary particle diameter of the slurry of barium sulfate particles was calculated by the same method as that described in Example 1, and was 0.04 μm.

Example 6 A 1.5 mol / L barium chloride aqueous solution and a 1.5 mol / L sodium sulfate aqueous solution were simultaneously injected into a reaction container to obtain a slurry having 160 g / L of barium sulfate particles. The obtained slurry was filtered and washed with water, and then the obtained filter cake was repulped to prepare a slurry of 180 g / L barium sulfate particles. This slurry was spray-dried using a spray dryer (manufactured by Okawara Kakoki Co., Ltd., disk atomizer) at a rotation speed of 20000 rpm and an outlet temperature of 90 ° C. or higher to obtain a dried product. The obtained dried product was calcined at 600 ° C. for 1.0 hour, then washed with water and dried to obtain a barium sulfate spherical aggregate. The average primary particle diameter of the slurry of barium sulfate particles was calculated by the same method as that described in Example 1, and was 0.04 μm.

[Comparative Example 1]
40 L of 0.42 mol / L barium hydroxide aqueous solution and 12 L of 1.33 mol / L dilute sulfuric acid were simultaneously injected into the reaction vessel so as to maintain pH 7 to 10 to obtain a slurry having barium sulfate particles of 70 g / L. ..
The obtained slurry was filtered and washed with water, and the obtained filter cake was dried at 105 ° C. for 2 hours using a constant temperature dryer (SONW-450 manufactured by As One Co.), and subsequently the obtained barium sulfate was 200 ° C. After firing for 1 hour, barium sulfate was obtained.
In order to confirm the average primary particle diameter of the barium sulfate particle slurry, the average primary particle diameter was calculated using the same method as that described in Example 1, and the average primary particle diameter was 0.03 μm.

[Comparative Example 2]
40 L of 0.42 mol / L barium hydroxide aqueous solution and 12 L of 1.33 mol / L dilute sulfuric acid were simultaneously injected into the reaction vessel so as to maintain pH 7 to 10 to obtain a slurry having barium sulfate particles of 70 g / L. ..
The obtained slurry was spray-dried using a spray dryer (manufactured by Ashizawa, Niro atomizer) at a rotation speed of 16850 rpm and an outlet temperature of 98 to 115 ° C to obtain a dried product.
In order to confirm the primary particle diameter of the barium sulfate particle slurry, the average primary particle diameter was calculated by using the same method as that described in Example 1 and found to be 0.03 μm.

[Comparative Example 3]
1 kg of barium sulfate (Varifine (R) BF-1, manufactured by Sakai Chemical Industry Co., Ltd., average primary particle diameter 0.05 μm, BET specific surface area 23.4 m ² / g) obtained by reaction of barium sulfide and sulfuric acid is repulped in water. Then, a slurry of 100 g / L barium sulfate particles was prepared.
The obtained slurry was spray-dried using a spray dryer (Okawara Kakohki Co., Ltd., disk atomizer) at a rotation speed of 20000 rpm and an outlet temperature of 90 ° C. or higher to obtain a dried product.
The average primary particle diameter of the slurry of barium sulfate particles was calculated by the same method as that described in Example 1, and it was 0.05 μm.

[Comparative Example 4]
1 kg of barium sulfate (Variace (R) B-54, manufactured by Sakai Chemical Industry Co., Ltd., BET specific surface area 4.0 m ² / g) obtained by the reaction of barium sulfide and sulfuric acid was repulped in water to obtain 100 g / L barium sulfate particles. Was prepared.
The obtained slurry was spray-dried using a spray dryer (manufactured by Okawara Kakoki Co., Ltd., disk atomizer) at a rotation speed of 20000 rpm and an outlet temperature of 90 ° C. or higher to obtain a dried product. The obtained dried product was baked at 950 ° C. for 1.0 hour to obtain a barium sulfate spherical aggregate.
The average primary particle diameter of the slurry of barium sulfate particles was calculated by the same method as that described in Example 1, and was 0.4 μm.

[Comparative Example 5]
Evaluation was carried out using BAX-M (manufactured by Sakai Chemical Industry Co., Ltd.), which is a commercial product of barium arsenic sulfate obtained by crushing ore and sieving.

[Comparative Example 6] A 1.5 mol / L barium chloride aqueous solution and a 1.5 mol / L sodium sulfate aqueous solution were simultaneously injected into a reaction container to obtain a slurry having 160 g / L of barium sulfate particles. The obtained slurry was filtered and washed with water, and the obtained filter cake was repulped to prepare a slurry of 35 g / L barium sulfate particles. This slurry was spray-dried using a spray dryer (manufactured by Okawara Kakoki Co., Ltd., disk atomizer) at a rotation speed of 20000 rpm and an outlet temperature of 90 ° C. or higher to obtain a dried product. The average primary particle diameter of the slurry of barium sulfate particles was calculated by the same method as that described in Example 1, and was 0.04 μm.

[Comparative Example 7] A 1.5 mol / L barium chloride aqueous solution and a 1.5 mol / L sodium sulfate aqueous solution were simultaneously injected into a reaction vessel to obtain a slurry having 160 g / L of barium sulfate particles. The obtained slurry was filtered and washed with water, and then the obtained filter cake was repulped to prepare a slurry of 180 g / L barium sulfate particles. This slurry was spray-dried using a spray dryer (manufactured by Okawara Kakoki Co., Ltd., disk atomizer) at a rotation speed of 20000 rpm and an outlet temperature of 90 ° C. or higher to obtain a dried product. The average primary particle diameter of the slurry of barium sulfate particles was calculated by the same method as that described in Example 1, and was 0.04 μm.

Various physical properties of the spherical barium sulfate obtained in each Example and Comparative Example were measured or evaluated (in Comparative Example 5, arsenic barium sulfate was used). The results are shown in Tables 1 and 2. In addition, regarding the barium sulfate obtained in Examples 1 to 6 and Comparative Examples 1 to 5, the particle shape was observed with a field emission scanning electron microscope (JSM-7000F, manufactured by JEOL Ltd.) (FIGS. 1 to 11). ..

The following was confirmed from the above Examples and Comparative Examples.
Comparative Example 1 (using barium sulfate obtained by the reaction of barium hydroxide and sulfuric acid) is an example different from the manufacturing methods of Examples 1 to 3 in that the drying step is not a spray drying step. It was confirmed that the barium sulfate obtained in Comparative Example 1 had a non-spherical particle shape (see FIG. 7) and the coating feeling was significantly inferior.

Comparative Example 2 (using barium sulfate obtained by the reaction of barium hydroxide and sulfuric acid) is an example different from the manufacturing methods of Examples 1 to 3 in that the firing step is not performed. The spherical barium sulfate obtained in Comparative Example 2 was found to have a remarkably poor particle strength because the particle size distribution after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes) became broad, and in addition, the coating feel Was also markedly inferior. In addition, when the rates of change of D50 and D90 / D10 before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes) were observed, it was confirmed that all were significantly changed. Furthermore, it was found from the results of comparison between Example 1-a and Comparative example 2-a described later that the presence or absence of firing had a great influence on the particle strength.

Comparative Example 3 (using barium sulfate obtained by the reaction of barium sulfide and sulfuric acid) is an example different from the manufacturing method of Example 4 in that the firing step is not performed. The spherical barium sulphate obtained in Comparative Example 3 was found to be significantly inferior in particle strength because the particle size distribution was broadly changed due to ultrasonic irradiation and thus was significantly inferior, and the coating feel was also inferior. Was also confirmed. In addition, when the rates of change of D50 and D90 / D10 before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes) were observed, it was confirmed that all were significantly changed. Further, in Example 4 in which barium sulfate similarly made of barium sulfide was used, no sulfide was detected, whereas in Comparative Example 3, sulfide was detected.

In Comparative Example 4 (using barium sulfate obtained by the reaction of barium sulfide and sulfuric acid), although the spray drying step and the firing step were performed, the average primary particle diameter of the barium sulfate particles in the slurry subjected to the spray drying step was This is an example that exceeds the numerical range defined by the manufacturing method of the present invention. The spherical barium sulfate obtained in Comparative Example 4 was found to be significantly inferior in particle strength because the particle size distribution was broadly changed by irradiation with ultrasonic waves and thus became broad, and in addition, the coating feel was significantly inferior. Was also confirmed. In addition, looking at the rate of change of D50 and D90 / D10 before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes), it was confirmed that D90 / D10 was particularly greatly changed.

Although Comparative Example 5 is a commercially available product of barium arsenic sulfate, it can be confirmed from FIG. 11 that the particle shape is obviously not spherical.

Comparative Example 6 (using barium sulfate obtained by the reaction of barium chloride and sodium sulfate) is an example different from Example 5 in that the firing step is not performed. The spherical barium sulphate obtained in Comparative Example 6 was found to have a markedly poor particle strength because the particle size distribution was broadly changed by irradiation with ultrasonic waves, resulting in a significantly inferior particle strength. Was also confirmed. In addition, when the rates of change of D50 and D90 / D10 before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes) were observed, it was confirmed that all were significantly changed.

Comparative Example 7 (using barium sulfate obtained by the reaction of barium chloride and sodium sulfate) is an example different from Example 6 in that the firing step is not performed. The spherical barium sulphate obtained in Comparative Example 7 was found to be significantly inferior in particle strength because the particle size distribution was broadly changed by irradiation with ultrasonic waves and thus was broadly inferior, and in addition, the coating feel was remarkably inferior. Was also confirmed. In addition, looking at the rate of change of D50 and D90 / D10 before and after ultrasonic irradiation (frequency 20 kHz, output 75 W × 2 minutes), it was confirmed that D90 / D10 was particularly greatly changed.

On the other hand, the spherical barium sulphate obtained in Examples 1 to 6 has low specific gravity and high sphericity, and the particle size distribution became sharp even after ultrasonic irradiation, so it can be confirmed that it has sufficient strength. Furthermore, it was confirmed that the feeling was very good, sulfide was not detected, and the safety was high. It can be confirmed from FIGS. 1 to 6 that the particle shape is very close to a true sphere. From these results, to produce spherical barium sulfate through a predetermined spray drying step and firing step, and the spherical barium sulfate has an average particle diameter, sphericity and true specific gravity within a predetermined range, and under predetermined conditions. It can be seen that the fact that D90 / D10 after being irradiated with ultrasonic waves is a particle in a predetermined range is a particularly important factor in terms of feel and safety.
Although not shown in the table, the spherical barium sulfates obtained in Examples 1 to 6 are the hydrochloric acid-soluble substances and soluble barium salts defined in "barium sulfate" described in "Standards for Quasi-drugs 2006". It satisfies all the items except sulfides. Therefore, the spherical barium sulfates obtained in Examples 1 to 6 are barium sulfates compatible with "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006".

[Examples 2-a, 2-b]
With respect to the spherical barium sulfate obtained in Example 2, the particle cross section was observed with a field emission scanning electron microscope (JSM-7000F, manufactured by JEOL Ltd.) (FIGS. 12 and 13). From these electron micrographs, it was found that the spherical barium sulfate of the present invention had voids inside the particles, and there were particles having a hollow shape inside.

[Example 1-a]
The spherical barium sulfate obtained in Example 1 was subjected to the above-mentioned “4, (2) Particle strength (with ultrasonic irradiation)” test, and powder (particles) obtained was subjected to a field emission scanning electron microscope (JEOL). It was observed by JSM-7000F manufactured by the company (FIG. 14).

[Comparative Example 2-a]
The spherical barium sulfate obtained in Comparative Example 2 was subjected to the above-mentioned "4, (2) Particle strength (with ultrasonic irradiation)" test, and the powder (particles) obtained was subjected to a field emission scanning electron microscope (JEOL). It was observed by JSM-7000F manufactured by the company (FIG. 15).

The manufacturing method of Example 1 and Comparative Example 2 differ only in whether or not the firing step is performed after the spray drying step of the slurry. Under such a difference, when the spherical barium sulfate obtained in each example was irradiated with ultrasonic waves, the spherical barium sulfate obtained in Example 1 showed almost no change in particle shape before and after irradiation with ultrasonic waves. None (FIGS. 1 and 14). On the other hand, in the spherical barium sulfate obtained in Comparative Example 2, the particles became coarse after the irradiation of ultrasonic waves, and the shape was significantly changed (FIGS. 8 and 15). Therefore, it was confirmed that by performing the firing step, the particle strength was improved and the strength was sufficient to withstand external stimuli such as ultrasonic waves.

[Example 2-c]
The spherical barium sulfate obtained in Example 2 was subjected to the above-mentioned “11, sebum adsorption force” test to evaluate sebum adsorption force. The results are shown in Table 3.

[Comparative Example 8]
The nylon beads (product name "SP-500", average particle size = 5 µm) manufactured by Toray Industries, Inc. were subjected to the above-mentioned "11, sebum adsorption force" test to evaluate sebum adsorption force. The results are shown in Table 3.

Nylon beads are generally used as a sebum adsorbent used for preventing makeup from falling apart, but the sebum adsorbing power between spherical barium sulfate obtained in Example 2-c and nylon beads (Comparative Example 8) is In comparison, Table 3 shows that the spherical barium sulfate of the present invention is also useful as a sebum adsorbent because it is at the same level.

Spherical barium sulfate obtained by the production method of the present invention, and spherical barium sulfate of the present invention, in addition to cosmetics, pharmaceuticals, quasi drugs, radiation shielding materials, paints, resin materials, printing toners, catalysts, lubricants, It can be used for various purposes such as wood.

Claims (4)

A step (1) of spray-drying a slurry of barium sulfate particles having an average primary particle diameter of 0.005 to 0.25 μm, and a step (2) of baking the dried product obtained in the step (1) at 200 to 1100 ° C. ) And a method for producing spherical barium sulfate. The method for producing spherical barium sulfate according to claim 1, wherein the firing time in the step (2) is 0.5 to 12 hours. A spherical barium sulfate having an average particle diameter of 0.5 to 100 μm, a sphericity of 1.0 to 1.2, and a true specific gravity of 4.45 or less,
Moreover, D90 / D10 after irradiating ultrasonic waves having a frequency of 20 kHz and an output of 75 W for 2 minutes with respect to 100 ml of the water slurry having a spherical barium sulfate concentration of 20 g / L is 4.5 or less. Barium sulfate. The spherical barium sulfate according to claim 3, wherein the spherical barium sulfate is compatible with "barium sulfate" described in "Standards for Quasi-drug Raw Materials 2006".