JPH0488023A - Production of spherical fine silicone particle - Google Patents

Abstract

PURPOSE:To obtain the subject fine particles, having an extremely narrow particle size distribution, excellent in water repellency, heat resistance and slippery characteristics and useful as cosmetics, etc., by stirring a methyltrialkoxysilane, etc., and water, preparing a homogeneous solution and then adding an alkali thereto. CONSTITUTION:A methyltrialkoxysilane (e.g. methyltrimethoxysilane) or a partially hydrolyzed condensate thereof or both are hydrolyzed and condensed to produce spherical fine silicone particles (preferably having <=1.1 ratio of the major axis to the minor axis, 0.1-20mum average particle diameter and <=20% coefficient of variation). In the process, the methyltrialkoxysilane or the partially hydrolyzed condensate thereof or both are previously stirred with water to afford a homogeneous solution and an alkali such as caustic alkali is then added to advance hydrolysis and condensation. Thereby, the objective fine particles are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing spherical silicone fine particles, that is, a method for producing polymethylsilsesquioxane fine particles having a spherical shape and an extremely narrow particle size distribution.

<Prior art> A method for producing polymethylsilsesquioxane, which is characterized by its spherical shape, involves combining methyltrialkoxysilane and/or its partially hydrolyzed condensate with an aqueous solution of ammonia and/or amine. A method of forming two layers and conducting hydrolysis and condensation at the interface (Japanese Patent Application Laid-open No. 637
No. 7940).

<Problems to be Solved by the Invention> In the method disclosed in JP-A No. 63-77940, it is important to control the stirring speed, special stirring equipment is required, the reaction occurs at the interface, and alkali The reaction rate is extremely limited because there are very few opportunities for contact with the alkali, and since ammonia or amines are used as the alkali, there is a limit to the strength of the alkali. (For example, 0.1 to 20
Problems remain, such as the difficulty of controlling ILIn).

The purpose of the present invention is to produce polymethylsilsesquioxane fine particles that are spherical in shape and have an extremely narrow particle size distribution, which does not require special equipment, is easy to operate, and is therefore suitable for inexpensive industrial production. Furthermore, the present invention provides a manufacturing method that allows the particle size to be freely controlled over a wide range.

<Means for Solving the Problems> That is, the present invention provides a method for producing spherical silicone fine particles by hydrolyzing and condensing methyltrialkoxysilane and/or its partially hydrolyzed condensate. methyltrialcodixylan and/or its partially hydrated The decomposition condensation product and water are stirred to form a homogeneous solution, then an alkali is added and stirred, and after the alkali is mixed uniformly, the stirring is stopped and the hydrolysis/condensation is allowed to proceed while standing still. This is a method for producing spherical silicone particles.

As the raw material methyltrialkoxysilane in the present invention, those in which the alkoxy moiety is alkyl having 1 to 4 carbon atoms are preferably used, such as methyltrimethoxysilane, methyldimethoxyethoxysilane, methyltriethoxysilane, and methyltripropoxysilane. , methyltributoxysilane, methylmethoxydibutoxysilane and the like.

In addition, the partial hydrolyzed condensate is a product obtained by hydrolyzing and condensing a part of the alkoxy group of the above-mentioned methyltrialkoxysilane, and is itself liquid, and is not mixed with methyltrialkoxysilane, water, an organic solvent, or any of these. It is soluble in the mixture.

These methyltrialkoxysilanes and their partially hydrolyzed condensates may be used alone or in mixtures, or methyltrialkoxysilanes may be simply mixed in advance with water, an organic solvent, or a mixture of water and an organic solvent. It is possible to use a material that is dissolved into a homogeneous solution.

Among these methyltrialkoxysilanes, methyltrimethoxysilane, which is easily available, is most preferably used.

Methyltrialkoxysilane is generally made from methyltrichlorosilane and usually has some residual chlorine. However, residual chlorine does not interfere with the purpose of the present invention, and it can be used normally regardless of the amount of residual chlorine. However, when considering the required amount of alkali, it goes without saying that it is preferable to use less chlorine, which consumes alkali.

In the present invention, it is important to homogenize methyltrialkoxysilane and/or its partially hydrolyzed condensate and water in advance.

Methyltrialkoxysilane originally has an extremely slow hydrolysis rate and does not easily form a homogeneous solution with water. However, since it generally contains a small amount of acid or alkali, it may be easily homogenized in a relatively short time without adding anything. Moreover, a catalyst can be newly added in order to adjust the hydrolysis rate, that is, the rate of uniformization.

The catalyst used here can be freely selected from acids, bases, and organometallic compounds such as titanium and tin, which are generally widely used as hydrolysis/condensation catalysts, but preferably acids or bases. However, in the presence of a condensation catalyst, gelation will proceed if care is not taken, and insoluble matters will easily form. For this reason, care must be taken in setting the dissolution conditions (amount of catalyst added, temperature, time).

For ordinary methyltrialkoxysilane in which a very small amount of acid or alkali is present, temperature, time, stirring conditions, etc. can be selected from a wide range. However, in this case as well, if you take too long, there is a possibility that a highly viscous oil or grease-like substance will be formed, so it is usually within 20 hours when the temperature is 10 to 15 degrees Celsius, and within 4 to 5 hours when the temperature is 70 to 80 degrees Celsius. is used as an appropriate condition.

The amount of methyltrialkoxysilane and/or its partially hydrolyzed condensate added to water can also be selected from a wide range for the purpose of the present invention, but preferably 0.01 to 1 part by weight of water. 1 part by weight is used.

Further, when homogenizing, water alone or a mixture of water and an organic solvent can be used. The organic solvent is
For example, lower alcohols, ketones, ethers, esters, and other substances that dissolve well in water can be used. The concentration of the organic solvent is also not particularly limited, but is usually preferably 30% or less.

In the present invention, after homogenization as described above, an alkali is added to proceed with hydrolysis and condensation to produce spherical silicone fine particles. Any of these can be used. In general, the periodic table I
Examples include hydroxides, oxides, carbonates, organic nitrogen compounds, and ammonia of group a and IIa metals.

Particularly preferably caustic soda, caustic potash, etc. I of the periodic table
Group A metal hydroxides, organic nitrogen compounds such as ethylene diamine, diethylamine, triethylamine, and ammonia are used.

These alkalis may be used alone or in combination of two or more, or may be a mixed solution of these aqueous solutions or water-soluble organic solvents such as lower alcohols, ketones, and ethers. Available for use.

In the present invention, the amount of alkali added is not particularly limited either. However, the amount of alkali, that is, the pH
has a large effect on the particle size of the spherical silicone particles produced. The particle size can be controlled by increasing the pH if small particles are to be obtained, and by decreasing the pH if large particles are to be obtained. Therefore, a pH suitable for the target particle size may be selected. Generally, the pH is selected between 8 and 14.

When adding the alkali, and after addition, stirring is of course performed to uniformly mix the alkali.

In the method of the present invention, after adding the alkali and stirring and mixing, stirring may be continued, but it is preferable to stop stirring after the alkali is mixed uniformly and allow hydrolysis and condensation to proceed while standing still. It is highly effective in narrowing the particle size distribution and suppressing aggregation between particles.

However, if the mixture is allowed to stand still for hydrolysis and condensation to proceed, the produced particles will inevitably settle and accumulate at the bottom of the reactor. However, after the generation of particles is finished, re-slurry can be done by normal stirring and there is no problem.

There are no particular limitations on the temperature at which the method of the present invention is carried out. It can be selected from the range from O'C, which is the freezing point of water, to 100°C, which is the boiling point at normal pressure. Further, the reaction may be carried out at 1.00° C. or higher under pressure if necessary. Generally, a temperature of 15°C to 80°C is often used. Furthermore, it is also possible to start from a low temperature (for example, 10 to 15°C) and then gradually raise the temperature (for example, to 80°C).

The time required for atomization is also related to temperature and cannot be generally limited, but generally the total time for homogenization, alkali addition, and standing is about 0.5 to 10 hours.

The spherical silicone particles produced in this way are then separated by filtration and washed with water or an organic solvent, or neutralized by adding an acidic substance, separated by filtration, washed with water, or washed with an organic solvent, and then dried. However, if necessary, it can be crushed to obtain fine particles.

The obtained particles are spherical silicone fine particles having a ratio of major axis to minor axis of 1.1 or less, a particle diameter of 0.1 to 20 μs, and a coefficient of variation of 20% or less, and with little aggregation between particles.

<Example> Hereinafter, the content of the present invention will be explained using examples.

The evaluation of the produced particles in the examples was carried out by measuring 50 or more particles from scanning electron micrographs and determining the average particle diameter (D) [μ
s], the length/breadth ratio, and the coefficient of variation [particle diameter standard deviation σ/average particle diameter DX100 (%)] were calculated. The yield is (methylsilsesquioxane/methyltrialkoxysilane) [
% by mole].

Example 1 1! Attach a stirrer, a thermometer, and a dropping funnel to a round-bottomed flask, and add 600 g of water to the flask at 20 Orpm.
The temperature was raised using an oil stove while stirring. When the temperature reached 50°C, methyltrimethoxysilane (Cf20
．． After about 15 minutes, the temperature rose to 55°C due to heat generation, and at this point the reaction system became a homogeneous and transparent solution. 30 minutes after adding methyltrimethoxysilane, add N/1ONaOH aqueous solution 17
ml and stirred for 1 minute at 200+pm, then stirring was stopped. Keep it at 50-55℃, and after starting to stand still, 2
After 5 minutes, the inside of the reaction system suddenly became cloudy and the generation of fine particles started. After 4 hours, most of the settled particles were reslurried by stirring, neutralized by adding 1 ml of 1% acetic acid water, filtered, washed with water, and washed with methanol, and finally dried in an oven at 150°C for 2 hours. 95 g of white powder was obtained (yield: 9
7 mol%). As a result of measuring the particle size with a scanning electron microscope, the average particle size was 5.2, and the ratio of major axis to minor axis was 1.0.
3. Spherical silicone fine particles without aggregation with a coefficient of variation of 6.5%.

Example 2 11! , Attach a stirrer, a thermometer, and a dropping funnel to a Yotsuka round-bottomed flask, and put 600 g of water into the flask.
The temperature was raised in an oil bath while stirring at 11 m. 50℃
After that, methyltrimethoxysilane (CI20.5 p
pm) 40 g was added. After 10 minutes, the solution turned into a homogeneous transparent solution. Add methyltrimethoxysilane, 30
After 10 minutes, 10
21 g of a wt % aqueous solution of caustic soda was added in its entirety. 4
The inside of the reaction system became cloudy in ~5 seconds. After treatment for 1 hour at a temperature of 50 to 55°C and stirring at 20 Orpm, 10% by weight acetic acid was added to 31.
5g was added to neutralize. Filtered, washed with water, washed with methanol, and dried in an oven at 150°C for 2 hours.
g of white powder was obtained (yield 76 mol%).

As a result of observing this powder with a scanning electron microscope, the average particle diameter was 0.5 μs, the major axis/minor axis ratio was 1.05, and the coefficient of variation was 15%.
The particles were perfectly spherical silicone particles.

The amount of agglomeration of particles was such that a small number of 5 to 10 particles were observed.

Example 3 Methyltrimethoxysilane 4 with chlorine content of 0.6% by weight
The same procedure as in Example 2 was carried out except that 23.7 g of a 10% caustic soda aqueous solution was used.

The same procedure as in Example 2 was carried out, except that hydrochloric acid acted as a catalyst for hydrolysis and condensation of methyltrimethoxysilane, and a homogeneous transparent liquid was obtained in a short time of 4 minutes after addition.

The obtained dry powder was 14.8 g (yield: 75 mol%). As a result of observation with a scanning electron microscope, the average particle size was 0.55μ
, a true spherical silicone fine particle with a major axis/minor axis ratio of 1.03 and a coefficient of variation of 17%.

Example 4 Everything was carried out in the same manner as in Example 2, except that 30 g of a 20% by weight methanol solution of ethylenediamine was used as the alkali.

The obtained dry powder was 17.6 g (yield: 89 mol%). They were truly spherical silicone fine particles with an average particle diameter of 0.9LLII+, a length/breadth ratio of 1.03, and a coefficient of variation of 9%.

Comparative Example 1 Using the same apparatus as in Example 1, 600 g of water was added to the flask.
The mixture was stirred at 200 pm and then heated in an oil bath. After reaching 50℃, methyltrimethoxysilane (
020.5 ppm) was added. After 10 minutes, it was still not completely homogenized and remained in an emulsion state.

Add 1.7 ml of N/10 Na OH to this and add 2
After stirring at 0 Orpm for 1 minute, stirring was stopped and the mixture was allowed to stand still. The emulsion in the reaction system was separated into two layers, an upper layer and a lower layer, by standing still.

After about 20 minutes, the lower layer began to become cloudy, and near the interface where the two layers had been separated, a viscous oil-like gelled substance was observed adhering to the inner wall, and finally became a lumpy gelled substance. After 4 hours, stir to reslurry, scrape off the product adhering to the inner wall and stirring rod, and perform post-treatment in the same manner as in Example 1.
90 g (yield: 91 mol%) of white powder was obtained.

It was a mixed powder of spherical particles of 2 to 4 microns and irregularly shaped lumps. In addition, 200 + for 4 hours after adding N/1ONaOH
Similar results were obtained even if stirring was continued at pm.

<Effects of the Invention> The method of the present invention produces spherical silicone fine particles with a ratio of major axis to minor axis of 1.1 or less, an average particle diameter of 0.1 to 201 m, a coefficient of variation of 20% or less, and less particle aggregation. became possible to manufacture.

In addition, the fine particles obtained by the present invention can be used in cosmetics, paints,
When added to adhesives, etc., it is effective in improving water repellency, heat resistance, and sliding properties, etc. Furthermore, when added to resins, it is used as a stress reliever and absorbent that occurs due to curing, shrinkage, and expansion due to heat. It can be effectively used as In addition, new functions can be added and used by adsorbing and bonding dyes, ultraviolet absorbers, etc. to the surface, or plating metal.

Claims (2)

[Claims] (1) Before hydrolyzing and condensing methyltrialkoxysilane and/or its partially hydrolyzed condensate to produce spherical silicone fine particles, methyltrialkoxysilane and/or its partially hydrolyzed condensate and water are stirred in advance. A method for producing spherical silicone fine particles, which comprises adding an alkali after forming a homogeneous solution. (2) Before hydrolyzing and condensing methyltrialkoxysilane and/or its partially hydrolyzed condensate to produce spherical silicone fine particles, methyltrialkoxysilane and/or its partially hydrolyzed condensate and water are stirred in advance. A method for producing spherical silicone fine particles, which is characterized in that after forming a homogeneous solution, adding and stirring an alkali, and after uniformly mixing the alkali, stirring is stopped and hydrolysis and condensation are allowed to proceed while standing still. .