JP2003183395A - Method for producing spherical silicone fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain spherical silicone fine particles having a large average particle diameter in the range of 10-30 μm and a narrow size distribution. <P>SOLUTION: In the method for producing spherical silicone fine particles by hydrolyzing an organotrialkoxysilane in an acidic water to obtain a silanol solution, adding an alkaline aqueous solution to the solution, mixing the resulting mixture, and subjecting the mixture to polycondensation reaction in the state of still standing to form silicone fine particles, a ≥4C alcohol having a specific solubility in water is added to the reaction system before adding the alkaline aqueous solution. <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, more specifically, spherical polyorganosyl having a large average particle diameter of 10 to 30 μm and a uniform particle diameter (narrow particle size distribution). The present invention relates to a method for efficiently producing sesquioxane fine particles.

[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, those having a narrow particle size distribution with respect to the target average particle size, particularly particles having a particle size largely separated from the target particle size, for example, particles having a particle size of 1/2 or less or 2 times or more of the desired particle size. There has been a demand for a manufacturing method that does not mix the two.

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, in any of these methods of depositing a silicone component from a uniform solution, the average particle size of the finally obtained silicone fine particles is small, and the average particle size exceeds 10 μm. There was a problem that it was difficult to obtain particles. For example, the average particle diameter of the silicone fine particles obtained by the above-mentioned conventional method is usually 0.1 to 5 μm and the maximum is 10 μm, as is clear from each example, and the particle diameter of 10 μm or more is obtained by these methods. It was difficult to obtain spherical silicone fine particles having a narrow particle size distribution.

A method for producing silicone fine particles having a large average particle diameter is disclosed in JP-A-5-25279.
The silicone component deposited by hydrolysis / condensation is subjected to a stirring step having a shearing force in a solvent before the curing by the condensation is allowed to proceed, whereby a spherical or fibrous number 1
A method for preparing fine particles having a particle size of 0 μm to several mm is disclosed.

However, in this method, the shape of the obtained particles was likely to be fibrous or cylindrical. Further, there is a drawback in that the particles are aggregated by vigorous stirring before curing and a large amount of gel-like solid matter is generated.

The present invention has been made to solve such a conventional problem and has an average particle diameter of 10 to 30 μm.
It is an object of the present invention to provide a method for efficiently producing spherical silicone fine particles having a narrow particle size distribution and a relatively large particle size in the above range.

[0013]

The method for producing spherical silicone microparticles according to the present invention according to claim 1 is characterized in that (A) an organotrialkoxysilane is hydrolyzed in acidic water to obtain an organosilanetriol and / or the organosilanetriol. A step of obtaining a solution of a partial condensate (hereinafter, simply referred to as a silanol solution); (B) an alkaline aqueous solution is added to and mixed with the silanol solution, and the mixed solution is allowed to stand,
In the method for producing spherical silicone fine particles, which comprises a step of subjecting the organosilanetriol and / or its partial condensate to a polycondensation reaction to form spherical silicone fine particles, before the addition of the alkaline aqueous solution in the step (B). It is characterized in that 5 to 80 parts by weight of a monohydric alcohol having 4 or more carbon atoms is added to 100 parts by weight of organotrialkoxysilane used for the reaction in the reaction system.

In the manufacturing method according to the first aspect, spherical silicone fine particles having a relatively large particle size in the range of 10 to 30 μm and a narrow particle size distribution can be obtained.

In the method for producing spherical silicone fine particles according to the present invention as defined in claim 2, the organotrialkoxysilane (A) is hydrolyzed in acidic water adjusted to an electric conductivity of 500 μS / cm or less to obtain a silanol solution. And (B) an alkaline aqueous solution is added to and mixed with the silanol solution to adjust the electric conductivity to 100 μS / cm or less, and the mixed solution is allowed to stand, and the organosilanetriol and / or its A method for producing spherical silicone fine particles, which comprises a step of polycondensing a partial condensate to form spherical silicone fine particles, which is used in the reaction system before the addition of the alkaline aqueous solution in the step (B). Organotrialkoxysilane 1
1 to 5 to 80 parts by weight per 00 parts by weight having 4 or more carbon atoms
It is characterized in that a hydric alcohol is added.

In the manufacturing method described in claim 2, the average particle size has a relatively large particle size in the range of 10 to 30 μm, and the particle size distribution is narrower than that of the method described in claim 1. It is possible to obtain spherical silicone fine particles having the above, that is, having a small standard deviation with respect to the average particle diameter.

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

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)

R ¹ in the general formula (I) is
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 because of the reaction rate and the availability of raw materials, and the alcohol released by hydrolysis affects 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, organotrichlorosilane alkoxylated by a known method with a suitable alcohol is preferably used.

Hydrolysis of the organotrialkoxysilane is carried out in a reaction system which is acidified 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 water used for hydrolysis, resulting in a 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 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 500 μS / cm. When the electrical conductivity is less than 2 μS / cm, sufficient progress of hydrolysis cannot be obtained, and reproducibility of average particle size and particle size distribution of particles finally obtained becomes poor. When the electric conductivity is more than 500 μS / cm, it is difficult to control the hydrolysis reaction, the average particle diameter of the finally obtained polyalkylsilsesquioxane fine particles becomes small, and the particle size distribution is controlled. Becomes difficult.

The amount of water used for the hydrolysis reaction is preferably in the range of 2 to 70 mol with respect to 2 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 size of the obtained polyalkylsilsesquioxane fine particles can be controlled by the amount of water used at the time of hydrolysis and the addition amount of an alcohol having 4 or more carbon atoms, which will be described later. The standard deviation can be controlled by the electric conductivity during hydrolysis.

The temperature of the hydrolysis reaction is not particularly limited, but in order to produce the 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.

In this way, the first step (step (A))
By the hydrolysis of the organotrialkoxysilane used in 1., the organosilanetriol and / or its partial condensate was dissolved in a mixture of excess water other than that consumed for hydrolysis and the alcohol produced by the reaction. Obtained in the form of a solution. Also, as described below,
In the step (A), when a monohydric alcohol having a carbon number of 4 or more and having a certain solubility in water is added to the reaction system, the added alcohol also exists in the solution. Become.

In the step (B) of the present invention, an alkaline aqueous solution is rapidly added to and mixed with the organosilanol solution after the step (A), and the uniformly mixed reaction system is allowed to stand still more rapidly. Done by putting in a state. 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 having 4 or more carbon atoms can be carried out at any stage prior to the addition of the alkaline aqueous solution in the step (B), but particularly in the step (A). It is preferable to add the alkoxysilane in the state before it is added and hydrolyzed.

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 is characterized by having a solubility in water within a predetermined range. . Solubility in water is 20
It is preferably in the range of 0.2 to 25% by weight at ° C. 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.

As such alcohols, monovalent alkyl alcohols such as 1-butanol, 1-pentanol, 1-hexanol, 1-octanol, 1-decanol and 2-ethylhexanol, 2-butanol, 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.

The action and effect of adding such an alcohol to the reaction system are considered as follows. That is, by adding and mixing an alkaline aqueous solution to an organosilanol solution containing and containing an alcohol having a carbon number of 4 or more and having a certain solubility in water, and further leaving the reaction system in a stationary state, silicone The atmosphere (solution state) in which particles are deposited changes. Then, such a change in the deposition atmosphere acts to increase the particle size.

By the addition of the above-mentioned alcohol,
Since the solubility of the partial condensate before precipitation becomes high, the supersaturation time can be extended, and as a result, the average particle size of the precipitated particles becomes large. Furthermore, the addition of alcohol changes the hydration state of the partial condensate before precipitation. That is, it is considered that the alcohol acts as a kind of surfactant, which acts to increase the particle size.

By the way, since a monohydric alcohol having a carbon number of 3 or less is easily soluble in water (solubility is ∞), even if such an alcohol is added, particles having an average particle diameter of 10 μm or more are obtained. I can't. 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 5 to 80 parts by weight, preferably 10 to 70 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 such an 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, and the reaction system that is rapidly added and mixed and uniformly mixed is used as a polyorgano 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 exceeds the amount necessary for neutralization, 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.

The theoretical resin concentration in the step (B) is 2
It is preferably 0% 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. The addition method 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 10 minutes.
0.5 to 10 minutes including the addition time at -25 ° C,
It is preferably carried out over 0.5 to 5 minutes.

After uniformly mixing the reaction system, the system is allowed to stand to complete polycondensation. By allowing it to stand, it is possible to achieve a preferable average particle size, and at the same time, a particle size that is far from the target particle size, for example, a particle size that is ½ or less of the target particle size or twice or more. Particles having a particle size are not substantially mixed, and particles having a uniform particle size can be obtained. In addition, since it is possible to manufacture with excellent efficiency with respect to time and apparatus volume, for example, the above-mentioned mixing temperature can be maintained at 2
Let stand for ~ 24 hours, preferably 4-18 hours.

In order to obtain particles having a large average particle size and having a particle size of 1/2 or less or 2 times or more of the desired particle size substantially not mixed, a stationary state is established. It is preferable that the time interval from completion to generation / precipitation of fine particles is large (for example, 10 minutes or more). Further, in order to control the particle size distribution more precisely, it is preferable that the solution temperature at the time of precipitation of particles is 30 ° C. or lower, more preferably 10 to 20 ° C.

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 have a relatively large average particle size of 10 to 30 μm, and substantially have a particle size of 1/2 or less or 2 times or more the target particle size. It is a polyspherical polyorganosilsesquioxane fine particle that does not mix and has a narrow particle size distribution. 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. .

[0051]

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 used as the coefficient of variation.
The value of the coefficient of variation was used as one of the indexes showing the degree of variation in the particle size distribution.

Example 1 [(A) Step] An electric conductivity meter (manufactured by Toa Denpa Kogyo Co., Ltd., CM) was placed in a reaction vessel equipped with a thermometer, a reflux condenser and a stirrer.
-14P) has an electric conductivity of 0.95μS
Distilled water (360 parts / cm 3) was charged, and diluted hydrochloric acid was added to adjust the electric conductivity of the mixed solution to 4.90 μS / cm.

Then, cyclohexanol 3 was added to this solution.
0 part was added, 90 parts of methyltrimethoxysilane was further added with stirring, and stirring was continued. Hydrolysis progresses,
The liquid temperature, which was 25 ° C. at the initial stage of the reaction, increased to 38 ° C. after 10 minutes and became a transparent solution. Stirring was continued for another 4 hours at room temperature.

[Step (B)] The liquid temperature of the mixed solution obtained in the step (A) is cooled to 18 ° C., 2 parts of 0.38% aqueous ammonia solution is added to the solution with stirring, and the solution is further added for 5 minutes. Stirring was performed. Then, stirring is stopped and the liquid temperature is set to 18 ° C.
When left still for 1 hour, the solution became cloudy after 1 hour, and precipitation / sedimentation of particles was observed. 1 of this reaction solution
After leaving at room temperature for 2 hours to complete the hydrolysis and condensation, the particles were redispersed by stirring. Next, this solution was passed through a 200-mesh wire mesh filter to remove gel-like substances, and suction filtration was performed to obtain a wet cake. This 15
It was dried overnight at 0 ° C. to obtain 39 parts of white dry particles.

The average particle diameter of the obtained particles (Beckman ·
Coulter Co., Ltd., particle size distribution analyzer LS230) is 22.3 μm, particle size variation coefficient is 23%
Met. In addition, when observed with an electron microscope, the particles are spherical and the minimum value is 13 μm and the maximum value is 26 μm.
Met. The target particle size (20 μm) is 1
Particles having a particle size of ½ or less or twice or more were not mixed.

Further, this powder was put in a magnetic crucible and heated in air to 900 ° C. for thermal decomposition. As a result, 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.

Examples 2 to 6 Polymethylsilsesquioxane fine particles were obtained in the same manner as in Example 1, except that the type of alcohol to be added and the amount thereof added were changed as shown in Table 1. Then the shape of the particles obtained,
The average particle size and the coefficient of variation of the particle size were measured in the same manner as in Example 1. The measurement results are shown in Table 1. It should be noted that none of the particles obtained in any of the Examples had a particle size of 1/2 or less or 2 times or more of the target particle size (10 to 20 μm).

[0059]

[Table 1]

Comparative Example 1 [Step (A)] Distilled water 3 having an electric conductivity of 0.95 μS / cm was charged in a reaction vessel equipped with a thermometer, a reflux condenser and a stirrer.
After adding 60 parts, dilute hydrochloric acid was added to adjust the electric conductivity of the aqueous solution to 5.25 μS / cm. When 90 parts of methyltrimethoxysilane was added to this solution while stirring and stirring was continued, hydrolysis proceeded, and the liquid temperature, which was 25 ° C in the initial stage of the reaction, rose to 39 ° C after 10 minutes, and a clear solution was obtained. Became. Stirring was continued at room temperature for another 4 hours.

[Step (B)] The liquid temperature of the mixed solution obtained in the step (A) was cooled to 16 ° C., 2 parts of 0.38% aqueous ammonia solution was added to the solution with stirring, and the solution was further added for 5 minutes. Stirring was performed. Then, stirring is stopped and the liquid temperature is changed to 16 ° C.
When the solution was allowed to stand while being kept at 1, the solution began to become cloudy after 1.5 hours, and precipitation / sedimentation of particles was observed. The reaction solution was left at room temperature for 12 hours to complete hydrolysis / condensation, and then stirred to redisperse the particles. Next, this solution was passed through a 200-mesh wire mesh filter to remove gel-like substances, and suction filtration was performed to obtain a wet cake. This 15
It was dried at 0 ° C. overnight to obtain 41 parts of white dry particles (polymethylsilsesquioxane particles).

The average particle diameter of the obtained particles is 7.3 μm,
The variation coefficient of particle diameter was 9.5%. Further, when observed with an electron microscope, the particles were truly spherical, and there was no particle having a particle diameter of 2 times or more the average particle diameter, but a small amount of particles having a particle diameter of 1/2 or less were mixed.

Comparative Example 2 [Step (A)] A reaction vessel equipped with a thermometer, a reflux condenser and a stirrer was charged with distilled water 3 having an electric conductivity of 1.02 μS / cm.
After adding 60 parts, diluted hydrochloric acid was added to adjust the electric conductivity of the aqueous solution to 4.80 μS / cm. 90% ethanol in this solution
90 parts of methyltrimethoxysilane was added while stirring, and stirring was continued. When 90 parts of methyltrimethoxysilane was added with stirring and the stirring was continued, hydrolysis proceeded, and the liquid temperature, which was 29 ° C. at the initial stage of the reaction, rose to 38 ° C. after 10 minutes, and became a transparent solution. .
Stirring was continued at room temperature for another 4 hours.

[Step (B)] The liquid temperature of the mixed solution obtained in the step (A) was cooled to 18 ° C., 2 parts of 0.38% aqueous ammonia solution was added to the solution while stirring, and the solution was further added for 5 minutes. Stirring was performed. Then, stirring is stopped and the liquid temperature is set to 18 ° C.
When left still for 2 hours, the solution became cloudy after 2 hours, and precipitation / sedimentation of particles was observed. 1 of this reaction solution
After allowing to stand at room temperature for 6 hours to complete hydrolysis / condensation, the particles were redispersed by stirring. Next, this solution was passed through a 325-mesh wire mesh filter to remove gel-like substances, and suction filtration was performed to obtain a wet cake. This is 10
It was dried overnight at 5 ° C. to obtain 36 parts of white dry particles (polymethylsilsesquioxane particles).

The obtained particles have an average particle size of 4.7 μm,
The coefficient of variation of particle size was 8.2%. Further, when observed by an electron microscope, the particles were spherical, but a small amount of particles having a particle size of 1/2 or less of the average particle size and particles having a particle size of 2 times or more of the average particle size were mixed. From the above results, according to the example,
The average particle diameter is 10 to 30 μm, which is a relatively large particle diameter, and the variation in the particle diameter is small (particles having a diameter greatly different from the target particle diameter are not substantially mixed).
It is understood that spherical silicone fine particles can be efficiently obtained.

[0066]

According to the production method of the present invention, spherical silicone fine particles having a large average particle size of 10 to 30 μm and a narrow particle size distribution can be obtained.

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 significant feature is that the standard deviation of the particle size is controlled to be small, that is, the particle size is made uniform, so that the rolling property is excellent and the uniform light reflection or light diffusing action is provided.

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 (4)

[Claims] 1. A step of hydrolyzing (A) an organotrialkoxysilane in acidic water to obtain a solution of organosilanetriol and / or a partial condensate thereof,
(B) An alkaline aqueous solution is added to and mixed with the solution of the organosilanetriol and / or its partial condensate, and the mixed solution is allowed to stand to polycondense the organosilanetriol and / or its partial condensate. In the method for producing spherical silicone fine particles, the step of reacting to form spherical silicone fine particles, prior to the addition of the alkaline aqueous solution in the step (B),
A method for producing spherical silicone fine particles, characterized in that 5-80 parts by weight of a monohydric alcohol having 4 or more carbon atoms is added to 100 parts by weight of organotrialkoxysilane used for the reaction in the reaction system. 2. A step of hydrolyzing (A) an organotrialkoxysilane in acidic water adjusted to an electric conductivity of 500 μS / cm or less to obtain a solution of organosilanetriol and / or a partial condensate thereof, (B) An alkaline aqueous solution is added to and mixed with the solution of the organosilanetriol and / or its partial condensate.
Spherical silicone comprising a step of adjusting the electric conductivity to 0 μS / cm or less and subjecting the mixed solution to a polycondensation reaction with the organosilanetriol and / or its partial condensate in a stationary state to form spherical silicone fine particles. In the method for producing fine particles, before the addition of the alkaline aqueous solution in the step (B),
A method for producing spherical silicone fine particles, characterized in that 5-80 parts by weight of a monohydric alcohol having 4 or more carbon atoms is added to 100 parts by weight of organotrialkoxysilane used for the reaction in the reaction system. 3. The organotrialkoxysilane is
The method for producing spherical silicone fine particles according to claim 1 or 2, which is methyltrimethoxysilane. 4. The water used for hydrolysis is ion-exchanged water or distilled water having an electric conductivity of less than 2 μS / cm before being acidified, according to any one of claims 1 to 3. The method for producing spherical silicone fine particles according to item 1.