JP2003183396A - Method for producing spherical silicone fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain spherical silicone fine particles having a narrow particle size distribution. <P>SOLUTION: (A) An organotrialkoxysilane is hydrolyzed in an acidic water having an electrical conductivity of ≤10 μS/cm to obtain a silanol solution. (B) An alkaline aqueous solution is added to the solution and mixed to adjust the electrical conductivity to 30-100 μS/cm. The mixture is subjected to polycondensation reaction in the state of still standing. Before adding the alkaline aqueous solution, a ≥4C alcohol is added in an amount of 1-80 pts.wt. based on 100 pts.wt. organotrialkoxysilane and in step (B), the change in temperature is controlled within ±2°C while maintaining a temperature of 5-20°C until fine particles are deposited. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing spherical silicone fine particles, and more particularly to a method for producing spherical polyorganosilsesquioxane fine particles having a very narrow particle size distribution and a very uniform particle size. Regarding

[0002]

2. Description of the Related Art Conventionally, as a method for producing spherical silicone fine particles, for example, the method disclosed in JP-A-63-77940 is known.

In this method, methyltrialkoxysilane and / or a partial hydrocondensate thereof, or a mixture of methyltrialkoxysilane and / or a partial hydrocondensate thereof and an organic solvent is used as an upper layer, and an alkali represented by ammonia is used. A mixture of components and an organic solvent is used as the lower layer, and methyltrialkoxysilane and / or its partial hydrocondensate is hydrolyzed / condensed at these interfaces to form polymethyl spheroids having independent spherical particles. This is a method for obtaining silsesquioxane fine particles.

However, this method has a problem that the maintenance of the reaction interface for hydrolyzing and polycondensing methyltrialkoxysilane and / or its partial hydrolyzate is complicated, and the production efficiency with respect to the apparatus volume is low. . Further, not all reactions are completed on the interface, and the effect in each solvent and / or each solute affects, so that the particle size distribution of the obtained fine particles tends to be broad. Therefore, there has been a demand for a manufacturing method in which fine particles having a narrow particle size distribution and a uniform particle size are obtained with respect to a target particle size.

There is also known a method of obtaining silicone fine particles having a narrow particle size distribution by carrying out hydrolysis / condensation in a uniform solution without forming the above-mentioned two-layer interface.

For example, in Japanese Unexamined Patent Publication (Kokai) No. 6-248081, the amount of chlorine atoms contained in methyltrialkoxysilane and / or its partial hydrocondensate is minimized, and hydrolysis is carried out under acidic conditions to homogeneity with water. There is disclosed a method of obtaining spherical silicone fine particles having a narrow particle size distribution by producing a solution and then adding an alkali to promote hydrolysis / condensation to precipitate a silicone component.

Further, in Japanese Unexamined Patent Publication No. 6-263875, a trialkoxysilane having a substituent other than a methyl group such as a vinyl group or a phenyl group is also examined. In the first step, organotrialkoxy is used. A method is disclosed in which silane is partially hydrolyzed with an organic acid in water and then hydrolyzed and condensed in an alkaline aqueous solution to obtain silicone fine particles having a desired substituent.

Further, in JP-A-2000-186148, methyltrialkoxysilane and / or its partial hydrocondensate is hydrolyzed under acidic conditions,
A method of obtaining spherical silicone fine particles is disclosed in which an alkaline aqueous solution is added after a uniform solution with water is generated and hydrolysis / condensation is allowed to proceed in a stationary state.

[0009]

However, although a method of depositing a silicone component from these homogeneous solutions can give silicone fine particles having a fairly narrow particle size distribution, it has recently been used as a material for adding a light diffusion function to a liquid crystal display device. In response to the expansion of applications in, the realization of fine particles having a narrower particle size distribution is required.

The present invention has been made in view of the above circumstances, and provides a method for producing spherical silicone fine particles having an average particle diameter in the range of 5 to 10 μm and an extremely narrow particle size distribution. The purpose is to

[0011]

The method for producing spherical silicone fine particles according to the present invention comprises the steps of:
(A) Organotrialkoxysilane at 10 μS / c
a step of obtaining an organosilanetriol and / or a partial condensate thereof (hereinafter simply referred to as a silanol solution) by hydrolysis in acidic water adjusted to have an electric conductivity of m or less; and (B) the silanol solution is alkaline. An aqueous solution is added and mixed to adjust the electric conductivity to 30 to 100 μS / cm or less, and the organosilanetriol and / or a partial condensate thereof is subjected to polycondensation reaction in a static state of this mixed solution to obtain spherical silicone fine particles. Before the addition of the alkaline aqueous solution in the step (B), the reaction system has a carbon number of 1 to 80 parts by weight per 100 parts by weight of organotrialkoxysilane used for the reaction. The above monohydric alcohol is added,
In the step (B), the organosilanetriol and / or its partial condensate is subjected to a polycondensation reaction while maintaining the temperature of 5 to 20 ° C., and the addition of the alkaline aqueous solution to the precipitation of the spherical silicone fine particles is performed. The temperature change of the mixed solution is controlled within ± 2 ° C.

In this manufacturing method, for example, 5 to 10
It is possible to obtain spherical silicone fine particles having a desired average particle size in the range of μm and having a very narrow particle size distribution, that is, a standard deviation of the particle size is extremely small.

In the present invention, the electric conductivity is used as the unit of concentration of acid or alkali because the amount of acid or alkali used is very small and the error in weight unit becomes large.

In the step (A) in the method for producing spherical silicone fine particles of the present invention, the organotrialkoxysilane is hydrolyzed in acidic water obtained by adding an acidic catalyst to water,
This is a step of obtaining a silanol solution.

Examples of the organotrialkoxysilane used in the present invention include the organotrialkoxysilanes represented by the following general formula (I). R ¹ Si (OR ² ) ₃ ... (I) (In the formula, R ¹ represents a monovalent group selected from the group consisting of a substituted or unsubstituted alkyl group, an alkenyl group and a phenyl group, R ² represents the same or different substituted or unsubstituted alkyl group)

This organotrialkoxysilane is hydrolyzed in acidic water to form an organosilanetriol represented by the following general formula (II) and / or a partial condensate thereof. R ¹ Si (OH) ₃ …………… (II)

As R ¹ in the above general formula (I),
A methyl group is suitable. R ² is an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group or an octyl group; a cycloalkyl group such as a cyclohexyl group;
Aralkyl groups such as 2-phenylethyl group and 2-phenylpropyl group; alkenyl groups such as vinyl group and allyl group; aryl groups such as phenyl group and tolyl group; alkenylaryl groups such as vinylphenyl group and 2-methoxyethyl Examples thereof include alkoxy-substituted alkyl groups such as a group, a 2-ethoxyethyl group, a 2-propoxyethyl group, and a 2-butoxyethyl group. Among these, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group are preferable from the viewpoint of reaction rate and availability of raw materials, and alcohol released by hydrolysis may affect the particle size finally obtained. Therefore, the methyl group, which has the least influence, is more preferable.

Examples of preferable methyltrialkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, methyltriisopropoxysilane and methyltris (2-methoxyethoxy) silane. A mixture of two or more species is used.

As such an organotrialkoxysilane, for example, one obtained by alkoxylating organotrichlorosilane with a suitable alcohol by a known method is preferably used.

The hydrolysis of the organotrialkoxysilane is carried out in a reaction system which is made acidic by adding an acidic catalyst to water. As the acid that is an acidic catalyst, either an organic acid or an inorganic acid can be used.

Examples of the organic acid include formic acid, acetic acid, propionic acid, oxalic acid, citric acid, etc., but it is easy to control the electric conductivity and control the partial condensation reaction of the produced polymethylsilanetriol. Since acetic acid is easy, acetic acid is particularly preferable. Examples of the inorganic acid include hydrogen acids such as hydrochloric acid and hydrofluoric acid, and oxo acids such as sulfuric acid and nitric acid. Any inorganic acid can be used as long as it does not leave impurities such as ionic substances that limit the applications of the finally obtained polymethylsilsesquioxane fine particles, but it is easily available. Therefore, hydrochloric acid is particularly preferable.

The presence of a small amount of hydrogen chloride as an impurity in the organotrialkoxysilane and the presence of organochlorosilanes such as methyltrichlorosilane change the electric conductivity of the water used for the hydrolysis to cause the hydrolysis reaction. Therefore, it is an obstacle to achieving the object of the present invention of precisely controlling the average particle size and standard deviation of the polyorganosilsesquioxane fine particles finally obtained, and therefore it should be avoided as much as possible.

As the water used for the hydrolysis, ion-exchanged water or distilled water having an electric conductivity of less than 1.2 μS / cm is suitable. Since the amount of acid used varies depending on the amount of water used, it is desirable to control it by the electrical conductivity of an acid aqueous solution in which the acid is dissolved.

The electrical conductivity of the aqueous acid solution used for hydrolysis in the present invention is preferably in the range of 2 to 10 μS / cm. A more preferable range is 3 to 5 μS / cm. When the electrical conductivity of the aqueous acid solution is less than 2 μS / cm, sufficient progress of hydrolysis cannot be obtained and the reproducibility of the average particle size and particle size distribution of the finally obtained particles becomes poor. Further, when the electric conductivity exceeds 10 μS / cm, it becomes difficult to obtain polyalkylsilsesquioxane fine particles having a sufficiently narrow particle size distribution.

The amount of water used for the hydrolysis reaction is preferably in the range of 2 to 70 mol per 1 mol of organotrialkoxysilane. When the amount of water is less than 2 mol, the hydrolysis does not proceed sufficiently, and when it exceeds 70 mol, the yield of the finally obtained polymethylsilsesquioxane fine particles is reduced and the production efficiency is reduced. descend.

The average particle diameter of the resulting polyalkylsilsesquioxane fine particles can be controlled by the amount of water used during hydrolysis, the type of alcohol having 4 or more carbon atoms described below, and the amount added.

The temperature of the hydrolysis reaction is not particularly limited, but in order to produce organosilanetriol and / or its partial condensate in good yield and to control the average particle diameter and the standard deviation of the particle diameter distribution with high accuracy, 10-6
It is preferable to carry out the reaction while maintaining the temperature at 0 ° C. for 1 to 18 hours.

Thus, by hydrolysis of the organotrialkoxysilane used in the step (A),
The organosilanetriol and / or its partial condensate is obtained in the form of a solution dissolved in a mixture of excess water other than that consumed for hydrolysis and the alcohol produced by the reaction. In addition, as described later, when a monohydric alcohol having a carbon number of 4 or more and having a certain solubility in water is added and mixed in the reaction system in the step (A), this is added to the solution. Alcohol will also be present.

In the step (B) of the present invention, the alkaline aqueous solution is rapidly added to the organosilanol solution which has been subjected to the step (A), and the homogeneously mixed reaction system is allowed to stand still more quickly. Done by putting. Then, in the present invention, the addition of the alkaline aqueous solution is performed in a state where the monohydric alcohol having 4 or more carbon atoms is added and contained in the reaction system. The addition of the monohydric alcohol,
It can be carried out at any stage before the addition of the alkaline aqueous solution in the step (B), but especially in the state before the addition of the organotrialkoxysilane in the step (A) and hydrolysis. It is preferable to keep.

The alcohol having 4 or more carbon atoms used in the present invention is a monovalent alcohol having one alcoholic hydroxyl group in one molecule and has a solubility in water within a predetermined range. To do. That is, those having a solubility in water in the range of 0.2 to 25% by weight at 20 ° C. are used. The alcohol may be any of primary (first), secondary (second) or tertiary (third) alcohols, and the carbon skeleton may be linear, branched, cyclic or a combination thereof.

Alcohols that can be used include monohydric alkyl alcohols such as 1-butanol, 1-pentanol, 1-hexanol, 1-octanol, 1-decanol and 2-ethylhexanol, 2-butanol and 2-pentanol. And other secondary alkyl alcohols (secondary alcohols), 1,1-dimethylethanol and other tertiary alkyl alcohols (tertiary alcohols), cyclopentanol, cyclohexanol, cycloheptanol and other cyclic alcohols, cyclohexylmethanol, etc. Cyclic substituted alcohols, aryl-substituted alkyl alcohols such as 2-phenylethanol, and the like. Especially 1-
When hexanol is used, true spherical silicone fine particles having an average particle size of about 8 μm and a wide range of application fields and a preferable particle size distribution and an extremely narrow particle size distribution can be obtained.

The action and effect of adding a monohydric alcohol having 4 or more carbon atoms to the reaction system is considered as follows. That is, since the alcohol has a certain solubility in water, the organosilanol solution containing and containing this alcohol is added with an alkaline aqueous solution and mixed, and then the reaction system is allowed to stand, which will be described later. By controlling the temperature of the reaction system (mixed solution) in such a manner, the atmosphere (solution state) in which the silicone fine particles are deposited is controlled to the optimum condition for the deposition of fine particles having a predetermined particle size, and the same supersaturation condition is maintained. As it is, the precipitation of particles can be promoted. As a result, particles having an extremely uniform particle size can be obtained.

Since the monohydric alcohol having a carbon number of 3 or less is easily soluble in water (solubility is ∞), the above-mentioned action and effect cannot be obtained. Further, even when a monohydric alcohol having 4 or more carbon atoms is used, this alcohol is added at the same time as the addition of the alkaline aqueous solution in the step (B).
That is, when added immediately before the precipitation of particles, the solubility of alcohol in water is not so high, so the dissolved state of silanol is rarely changed, and therefore particle formation cannot be sufficiently affected.

The amount of the monohydric alcohol having 4 or more carbon atoms added to the silanol solution is 1 to 80 parts by weight, preferably 2 to 20 parts by weight, per 100 parts by weight of the organotrialkoxysilane used. The amount of this alcohol does not include the amount of alcohols by-produced by hydrolysis of the organotrialkoxysilane.

The step (B) of the production method of the present invention comprises
This is a step of obtaining spherical polyorganosilsesquioxane fine particles by a polycondensation reaction from the silanol solution obtained in the step (A).

The alkaline aqueous solution used in the step (B) may be a basic aqueous solution. This alkaline aqueous solution acts not only as a neutralizing agent for the acid used in the step (A) but also as a catalyst for the polycondensation reaction of the organosilanetriol and / or its partial condensate.

Examples of the alkaline substance used in the alkaline aqueous solution include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; ammonia; and organic amines such as monomethylamine and dimethylamine. It can be illustrated. Among these, ammonia and organic amines are preferable because they do not leave a trace amount of impurities that limit the use of the obtained spherical polyorganosilsesquioxane fine particles,
Ammonia is particularly preferred because it is easily removed.

The amount of the alkaline aqueous solution used is such that it neutralizes the acid and effectively acts as a catalyst for the polycondensation reaction. This is an amount that can maintain the time during which the silsesquioxane fine particles can be promptly placed in a static state before being produced and deposited.

That is, assuming that the amount required for neutralization is exceeded, for example, an aqueous solution of ammonia having a concentration of 0.1 to 0.5% is used as the silanol solution 1 obtained in the step (A).
0.5 to 5 parts by weight is added to 00 parts by weight. Then, the electric conductivity of the mixed solution is set to 30 to 100 μS / cm.
More preferably, it is adjusted to the range of 35 to 80 μS / cm. Electric conductivity after adding alkaline aqueous solution is 30μS /
When it is less than cm, the desired reaction does not proceed and a small amount of gel is produced. Moreover, the electric conductivity is 100 μS / c.
When it exceeds m, not only the average particle diameter of the obtained particles becomes too small but also the particle size distribution becomes wide, which is not preferable.

The concentration of the resin (polyorganosilsesquioxane) theoretically obtained in the step (B) is preferably 20% by weight or less, more preferably 15% by weight or less.

In the step (B), a silanol solution is charged into a reaction vessel, the above alkaline solution is added to the silanol solution, and the mixture is rapidly and uniformly mixed by any means such as stirring, and then the system is added. To allow polycondensation to complete. The addition method of the alkaline solution is not particularly limited as long as it can be effectively added within the minimum mixing time,
It may be added from above the silanol solution or may be fed into the silanol solution through a nozzle or the like. The mixing time is a suitable minimum time necessary for dissolving the alkali catalyst in the reaction system, for example, 5 to 40 ° C., preferably 5 to 40 ° C.
It is carried out at 20 ° C for 0.5 to 10 minutes, preferably 0.5 to 5 minutes including the addition time.

By allowing the reaction system to stand, a preferable average particle size can be realized, and particles having a particle size far from the target particle size are not mixed and particles having a uniform particle size are obtained. You can In addition, since it becomes possible to manufacture with excellent efficiency with respect to time and device volume,
Allow to stand for 24 hours, preferably 4-18 hours.

Then, the organosilanetriol and / or its partial condensate is subjected to a polycondensation reaction while maintaining the temperature of the reaction system at 5 to 20 ° C. throughout the step (B). Further, it is desirable to control the temperature change of the mixed solution from the addition of the alkaline aqueous solution to the completion of the precipitation of fine particles within ± 2 ° C.

If the temperature of the reaction system is lower than 5 ° C., not only the reaction time becomes too long and the production efficiency deteriorates, but also the temperature control during that period becomes difficult. Also, the reaction temperature is 20 ℃
If it exceeds, fine particles having a desired narrow particle size distribution cannot be obtained. Further, even when the temperature change of the mixed solution until the fine particles are completely deposited is larger than ± 2 ° C, fine particles having a sufficiently narrow particle size distribution cannot be obtained.

By the polycondensation reaction in the step (B), spherical polyorganosilsesquioxane fine particles can be obtained as a disversion or sol in a water / alcohol mixture.

The spherical silicone fine particles obtained by the present invention are true spherical polyorganosilsesquioxane fine particles having an average particle diameter of 5 to 10 μm and an extremely narrow particle size distribution. The standard deviation of the obtained fine particles is 0.25 μm or less when the average particle size is about 5 μm, and the average particle size is about 10 μm.
If it is μm, it becomes about 0.5 μm. The spherical silicone fine particles can be used as they are in the form of a diversion or a sol, and if necessary, they can be further subjected to an appropriate treatment such as filtration, drying, crushing, etc. to be recovered as a fine powder. .

[0047]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In these examples, parts represent parts by weight. The invention is not limited by these examples.

The ratio of the standard deviation to the average particle diameter (standard deviation ÷ average particle diameter × 100) is the coefficient of variation.
The values of standard deviation and coefficient of variation were used as an index showing the degree of variation in particle size distribution.

Example 1 [Step (A)] A reaction vessel equipped with a thermometer, a reflux condenser and a stirrer was charged with an electric conductivity meter (manufactured by Toa Denpa Kogyo KK).
-14P) has an electric conductivity of 1.0 μS /
cm of distilled water was charged and diluted hydrochloric acid was added to adjust the electric conductivity of the solution to 5.0 μS / cm.

Then, 1-hexanol 3.
6 parts was added, 60 parts of methyltrimethoxysilane was further added with stirring, and the mixture was stirred at room temperature at a rotation speed of 200 rpm. Hydrolysis proceeded, and the liquid temperature, which was 23 ° C. at the initial stage of the reaction, increased to 34 ° C. 10 minutes later and became a transparent solution. Stirring was continued at room temperature for another 5 hours.

[Step (B)] The liquid temperature of the mixed solution obtained in the step (A) was cooled to 15 ° C., and 6.0 parts of a 0.38% aqueous ammonia solution was added thereto with stirring, and 1 Stir for minutes. Then, stirring is stopped and the liquid temperature is changed to 16 ± 2.
The mixture was allowed to stand overnight while maintaining the temperature at 0 ° C. to complete the hydrolysis / condensation reaction. Next, this solution was passed through a wire mesh filter of 200 mesh to remove the gel, and then washed with a water / ethanol mixed solution. This was dried overnight at 150 ° C. to obtain 42 parts of white dry particles.

The average particle diameter of the obtained particles (Beckman ·
Coulter Co., Ltd., laser scattering particle size distribution analyzer LS230) was 8.0 μm, the standard deviation of particle size was about 0.35 μm, and the coefficient of variation was 4.4%.
And, it had a very sharp particle size distribution in which 90% of the number of particles was distributed in the range of 8.0 μm ± 0.4 μm. Further, when observed with an electron microscope, the particles are spherical and the minimum value of the particle size is 7.5 μm and the maximum value is 8.4 μm.
It was m.

Further, this powder was placed in a magnetic crucible and heated in air to 900 ° C. for thermal decomposition, and the remaining amount was 89.0%. This is the theoretical amount of polymethylsilsesquioxane that decomposes into oxidative heat to form silicon dioxide.
It is a value close to 9.6%. As a result of X-ray analysis of this thermal decomposition product, it was confirmed to be amorphous silica.

Example 2 [Step (A)] Distilled water 36 having an electric conductivity of 0.9 μS / cm was charged in a reaction vessel equipped with a thermometer, a reflux condenser and a stirrer.
0 part was charged and diluted hydrochloric acid was added to adjust the electric conductivity of the solution to 4.4 μS / cm.

Next, 2.5 parts of 2-ethylhexanol was added to this solution, 60 parts of methyltrimethoxysilane was further added with stirring, and the mixture was stirred at room temperature at a rotation speed of 200 rpm. Hydrolysis proceeds, and 23
The liquid temperature, which was ℃, rose to 35 ℃ after 10 minutes, and became a transparent solution. Stirring was continued at room temperature for another 5 hours.

[Step (B)] The liquid temperature of the mixed solution obtained in the step (A) was cooled to 14 ° C., and while stirring, 6.0 parts of a 0.38% ammonia solution was added to Stir for minutes. Then, the stirring is stopped and the liquid temperature is adjusted to 15 ± 2.
The mixture was allowed to stand overnight while maintaining the temperature at 0 ° C. to complete the hydrolysis / condensation reaction. Next, this solution was passed through a wire mesh filter of 200 mesh to remove the gel, and then washed with a water / ethanol mixed solution. This was dried overnight at 150 ° C. to obtain 43 parts of white dry particles.

The average particle diameter of the obtained particles is 7.2 μm,
Standard deviation of particle size is 0.35μm, coefficient of variation is 4.7%
Met. And 90% of the number of particles is 7.2 μm ± 0.
It had an extremely sharp particle size distribution of being distributed in the range of 4 μm. Furthermore, when observed by an electron microscope, the particles are spherical and the minimum value of the particle size is 7.0 μm.
The maximum value was 7.8 μm.

Comparative Example 1 [Step (A)] Distilled water 36 having an electric conductivity of 1.0 μS / cm was placed in a reaction vessel equipped with a thermometer, a reflux condenser and a stirrer.
0 part was charged and diluted hydrochloric acid was added to adjust the electric conductivity of the solution to 4.5 μS / cm.

Then, 60 parts of methyltrimethoxysilane was added to this solution with stirring, and the mixture was stirred at room temperature at a rotation speed of 200 rpm. Hydrolysis proceeded, and the liquid temperature, which was 23 ° C in the initial stage of the reaction, increased to 35 ° C after 10 minutes,
It became a clear solution. Stirring was continued at room temperature for another 5 hours.

[Step (B)] The liquid temperature of the mixed solution obtained in the step (A) was cooled to 15 ° C., and 6.0 parts of a 0.38% aqueous ammonia solution was added thereto with stirring to Stir for minutes. Then, stirring is stopped and the liquid temperature is changed to 16 ± 2.
The mixture was allowed to stand overnight while maintaining the temperature at 0 ° C. to complete the hydrolysis / condensation reaction. Next, this solution was passed through a wire mesh filter of 200 mesh to remove the gel, and then washed with a water / ethanol mixed solution. This was dried overnight at 150 ° C. to obtain 43 parts of white dry particles.

The average particle diameter of the obtained particles is 4.5 μm,
Standard deviation of particle size is 0.32μm, coefficient of variation is 7.1%
Met. In addition, as a result of observation with an electron microscope, the particles are truly spherical and have a minimum particle size of 3.9 μm and a maximum value of 4.9.
was μm. The particles have a wider particle size distribution than those of the particles obtained in Examples 1 and 2 and are 4.5 μm ± 0.3.
The ratio of the number of particles distributed in the μm range was 70%.

Comparative Example 2 [Step (A)] Distilled water 36 having an electric conductivity of 1.2 μS / cm was placed in a reaction vessel equipped with a thermometer, a reflux condenser and a stirrer.
0 part was charged and diluted hydrochloric acid was added to adjust the electric conductivity of the solution to 5.0 μS / cm.

Then, 1-hexanol 3.
6 parts was added, 60 parts of methyltrimethoxysilane was further added with stirring, and the mixture was stirred at room temperature at a rotation speed of 200 rpm. Hydrolysis proceeded, and the liquid temperature, which was 22 ° C. in the initial stage of the reaction, increased to 34 ° C. 10 minutes later, and became a transparent solution. Stirring was continued at room temperature for another 5 hours.

[Step (B)] The liquid temperature of the mixed solution obtained in the step (A) was cooled to 15 ° C., and 6.0 parts of a 0.38% aqueous ammonia solution was added thereto while stirring, Stir for minutes. Then, the stirring was stopped and the mixture was left standing overnight to complete the hydrolysis / condensation reaction. At this time, the liquid temperature is 17
It fluctuated within a range of ± 4 ° C. Next, this solution was passed through a wire mesh filter of 200 mesh to remove the gel, and then washed with a water / ethanol mixed solution. This one
It was dried at 50 ° C. overnight to obtain 41 parts of white dry particles.

The average particle diameter of the obtained particles is 7.6 μm,
Standard deviation of particle size is 0.84 μm, coefficient of variation is 11.0
%Met. In addition, when observed with an electron microscope, the particles are truly spherical and have a minimum particle diameter of 6.0 μm and a maximum value of 7.
It was 9 μm. The particles have a wider particle size distribution than the particles obtained in Examples 1 and 2 and are 7.6 μm ± 0.
The ratio of the number of particles distributed in the range of 4 μm was 60%. From the above results, it can be seen that, according to the example, spherical silicone fine particles having an average particle diameter of 5 to 10 μm and a coefficient of variation of 5% or less and a very small variation in particle diameter can be obtained.

[0066]

According to the production method of the present invention, it is possible to obtain spherical silicone fine particles having an average particle size of 5 to 10 μm and a very narrow particle size distribution.

The spherical silicone fine particles obtained by the present invention are spherical polyorganosilsesquioxane fine particles which are insoluble and non-melting in an organic solvent, and the surface of which is excellent in water repellency and lubricity and is of an inorganic type. While having a specific gravity smaller than that of the powder, it is superior in heat resistance to the organic powder, has less cohesiveness, and is excellent in dispersibility. Further, the most important feature is that the standard deviation of the particle diameter is controlled to be small, that is, the particle diameter is made uniform, so that it is excellent in slipping property and rolling property and has a uniform light reflection or light diffusing action.

Therefore, taking advantage of such characteristics,
It is useful as a filler and a slipperiness improver for paints, plastics, rubber, paper, cosmetics, etc., or as an additive for modifying plastics for the purpose of adding a light diffusion function to an optical liquid crystal display device.

Claims (3)

[Claims] 1. An organotrialkoxysilane (A) is hydrolyzed in acidic water adjusted to have an electric conductivity of 10 μS / cm or less to give organosilanetriol and / or
Alternatively, a step of obtaining a solution of the partial condensate thereof, and (B) adding an alkaline aqueous solution to the solution of the organosilanetriol and / or the partial condensate thereof and mixing the mixture with each other for 30 to 30
The step of adjusting the electric conductivity to 100 μS / cm or less and subjecting the mixed solution to a static state to cause polycondensation reaction of the organosilanetriol and / or its partial condensate to form spherical silicone fine particles; Before the addition of the alkaline aqueous solution in the step (B),
1 to 80 parts by weight of a monohydric alcohol having 4 or more carbon atoms per 100 parts by weight of organotrialkoxysilane used for the reaction is added to the reaction system, and (B)
In the step of, the polysilane condensation reaction of the organosilanetriol and / or its partial condensate is performed while maintaining the temperature of 5 to 20 ° C., and the temperature of the mixed solution from the addition of the alkaline aqueous solution to the precipitation of the spherical silicone fine particles. A method for producing spherical silicone fine particles, characterized in that the change is controlled within ± 2 ° C. 2. The organotrialkoxysilane is
The method for producing spherical silicone fine particles according to claim 1, which is methyltrimethoxysilane. 3. The water used for hydrolysis is ion-exchanged water or distilled water having an electric conductivity of less than 1.2 μS / cm before being acidified.
The method for producing spherical silicone fine particles according to any one of 1.