JPH06248081A - Production of spherical silicone fine particle - Google Patents

Abstract

PURPOSE:To obtain the subject fine particles having extremely narrow particle size distribution at a low cost without using particular apparatus by using a methyltrialkoxysilane having specific residual chlorine content, its partially hydrolyzed and condensed product and water having specified specific conductance. CONSTITUTION:A homogenized mixture is produced by mixing 1 pt.wt. of water having a specific conductance of <=30mus/cm with 0.01-1 pt.wt. of a methyltrialkoxysilane and/or its partial hydrolyzed and condensed product having a chlorine content of <=10ppm preferably at 20-80 deg.C for 10min to 5hr. The obtained homogeneous solution is incorporated with an alkali (preferably caustic soda, etc.) to proceed the hydrolysis and condensation and obtain the objective fine particles having an average particle diameter of 0.1-20mum. The water having a specific conductance of <=30mus/cm is preferably produced by ion-exchange resin treatment. The fine pulverization with the alkali is preferably carried out in general at 15-80 deg.C for 0.5-10hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing spherical silicone microparticles, that is, a method for producing polymethylsilsesquioxane microparticles having a spherical shape, particularly close to a true sphere and having an extremely narrow particle size distribution.

[0002]

2. Description of the Related Art A method for producing polymethylsilsesquioxane, which is characterized by having a spherical shape, is a method of preparing methyltrialkoxysilane and / or its partially hydrolyzed condensate and an aqueous solution of ammonia and / or amine. Two
A method of hydrolyzing and condensing at the interface while forming a layer (JP-A-63-77940).

Further, a method for producing by limiting the concentration of an aqueous solution of an alkali metal hydroxide and the dropping rate of methyl trialkoxy silaan and / or its partial hydrolysis-condensation product (JP-A-2-209927, JP-A-2-209927). 4-8802
No. 2) is known.

Further, a method in which methyltrialkoxysilane and / or its partially hydrolyzed condensate is made into a uniform solution with water and then an alkali is added, and hydrolysis / condensation is allowed to proceed while still standing (Japanese Patent Application Laid-Open No. Hei 10-1999) No. 4-88023) is known.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the method according to Japanese Patent No. 7940, it is important to control the stirring speed, special stirring requires equipment, and the reaction is at the interface. Since the chance of contact with alkali is very small, the reaction speed is extremely low. It is difficult to control the particle size of the spherical fine particles to be produced in a high range (for example, 0.1 to 20 μm), because the alkali strength is limited because ammonium or amines is used as the alkali. Issues such as that are left.

Further, in the methods described in JP-A-2-209927 and JP-A-4-88022, methyltrialkoxy sila and / or its partial hydrolysis-condensation product is dropped into an aqueous alkali metal hydroxide solution. It is intended to obtain polymethylsilsesquioxane having a uniform and narrow particle size distribution by limiting the rate of drying, but under these limited conditions, the dropping time becomes long and the industrial production efficiency decreases. And other issues remain.

Further, in the method according to the above-mentioned JP-A-4-88023, the alkali is added after homogenizing methyltrialkoxysilane and / or its partial hydrolysis-condensation product and water. In this case, the homogenization may not always proceed, and an acid, a base and an organometallic compound such as titanium or tin may be separately added for homogenization. The silicone fine particles produced from such a homogenizing solution have increased variation in particle diameter and increased aggregation.

The object of the present invention is to produce polymethylsilsesquioxane fine particles having a spherical shape and an extremely narrow particle size distribution, without requiring any special equipment, easy to operate, and therefore inexpensive. The present invention provides a production method suitable for production and capable of freely controlling the particle size over a wide range.

[0009]

That is, the present invention is based on water 1
0.01 to 1 part by weight of methyltrialkoxysilane and / or its partial hydrolysis-condensation product is stirred and mixed with respect to parts by weight to form a uniform solution, and then alkali is added to allow hydrolysis and condensation to proceed to form spherical particles. The above-mentioned methyltrialkoxysilane and / or
Alternatively, the amount of chlorine contained in the partially hydrolyzed condensate is 1
A method for producing spherical silicone fine particles having an average particle diameter of 0.1 to 20 μm, which is characterized by homogenizing with water having a specific conductivity of 0 ppm or less and the water specific electric conductivity of 30 μs / cm or less.

As the raw material methyltrialkoxysilane in the present invention, an alkoxy having an alkyl moiety having 1 to 4 carbon atoms is preferably used, and examples thereof include methyltrimethoxysilane, methyldimethoxyethoxysilane, methyltriethoxysilane and methyl. Examples include tripropoxysilane, methyltributoxysilane, and methylmethoxydibutoxysilane.

The partial hydrolysis-condensation product 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 methyltrialkoxysilane, water and an organic solvent. Alternatively, it is soluble in these mixed liquids.

These methyltrialkoxysilanes and their partial hydrolysis-condensation products may be used alone or as a mixture.

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

In the present invention, it is important that the amount of chlorine remaining in the raw material methyltrialkoxysilane and / or its partial hydrolysis-condensation product is 10 ppm or less.

Chlorine as used herein is chlorine that can be titrated with silver nitrate, and is chlorine bonded to silicon derived from methyltrichlorosilane which is usually used as a raw material for the production of methyltrialkoxysilane.

When chlorine in the raw material contains more than 10 ppm, the neutralization salt produced during the production of spherical silicone fine particles by adding an alkali described later to cause hydrolysis / condensation causes variation in particle diameter of the particles. It has an adverse effect such as an increase in aggregation.

In the present invention, it is important that the water has a specific electric conductivity of 30 μs / cm or less. It is necessary to remove the ionic substance and make the specific electric conductivity 30 μs / cm or less.

Ionic substances are usually natural water, industrial water,
Ions Ca ²⁺ , Mg ²⁺ , Fe ³⁺ contained in tap water,
Al ³⁺ , Na ⁺ , NH ₄ ⁺ , HCO ₃ ⁻ , SO ₄ ²⁻ , P
Examples thereof include O ₄ ³⁻ , Cl ⁻ , and organic ionic substances represented by carboxylic acids, amines, and phenols.

The removal of these ionic substances can be carried out by a method generally used, for example, an ion exchange resin treatment, distillation, adsorption treatment or the like. Industrially, the ion exchange resin treatment is the most efficient. Often used. Although the specific conductivity varies depending on the temperature, the display in the present invention means a value at room temperature.

The water contains an ionic substance and has a specific electric conductivity of 3
If it exceeds 0 μs / cm, the compatibility with the above-mentioned raw material methyltrialkoxysilane deteriorates, and it becomes difficult to obtain a uniform solution. Further, even if a uniform solution is obtained, when a spherical silicone fine particle is produced by adding an alkali to be hydrolyzed and condensed as described later, particle size variation and aggregation increase.

As described above, in the present invention, the content of chlorine in the raw material methyltrialkoxysilane and / or its partial hydrolysis-condensation is 10 ppm or less, and the water used has an electric conductivity of 30 μm and contains almost no ionic substance.
The use of water at s / cm or less is a great feature, and it is important for obtaining spherical silicone fine particles having a very narrow particle size distribution.

In the present invention, the homogenizing mixing ratio of the water and the raw material is 0.01 to 1 with respect to 1 part by weight of water.
Parts by weight. When the ratio of the raw material to water is less than 0.01, the production efficiency is significantly reduced, and when it is more than 1, the concentration of the raw material is too high and the agglomeration of spherical silicone fine particles to be produced remarkably increases. Is not preferred.

The homogenizing method is usually carried out by mixing and stirring the water and the raw materials, and conditions such as temperature, time and stirring speed are not particularly limited, but usually 1 to 100 ° C., preferably 20 to 80. C., 1 minute to 10 hours, preferably 10 minutes to 5 hours, and the stirring speed may be a speed at which the liquid normally flows and is stirred and mixed.

Next, the formation of fine particles by adding an alkali to the above-mentioned homogeneous solution to promote hydrolysis / condensation will be described.

As the alkali used here, any alkali can be used as long as its aqueous solution shows alkalinity. In general, hydroxides, oxides, carbonates, organic nitrogen compounds, ammonia and the like of metals of Group Ia and IIa of the Periodic Table are mentioned. Particularly preferably, Group Ia metal hydroxides such as caustic soda and caustic potash, organic nitrogen compounds such as ethylenediamine, diethylamine and triethylamine, and ammonia are used.

These alkalis may be used alone or in combination of two or more. Also, the amount of alkali added is not particularly limited. However, the amount of alkali,
That is, the pH greatly affects the particle size of the spherical silicone particles produced. If you want to get small particles, p
If H is high and large particles are to be obtained, the particle size can be controlled by lowering the pH. Therefore, it suffices to select an addition amount suitable for the intended particle size.

Although the addition rate of the alkali is not limited, it is preferable that the addition is carried out as quickly as possible and the mixture is uniformly mixed as early as possible. When the alkali is added, and of course, sufficient stirring is naturally performed.

In the method of the present invention, the alkali may be added, and the stirring may be continued after the mixing. However, the stirring is stopped after the alkali is uniformly mixed, and the hydrolysis and condensation are allowed to proceed while standing. This is very effective in suppressing the agglomeration of the generated particles.

However, when the hydrolysis and condensation are allowed to proceed by standing still, the produced particles inevitably settle and accumulate at the bottom of the reactor. However, after the generation of particles is completed, the slurry can be re-slurried by ordinary stirring without any problem.

There is no particular limitation on the temperature at which the method of the present invention is carried out. It can be selected from the range of 0 ° C., which is the freezing point of water, to 100 ° C., which is the boiling point of normal pressure. If necessary, the reaction may be carried out at 100 ° C. or higher under pressure. Generally, 15 ° C. to 80 ° C. is often used. Furthermore, initially at low temperatures (eg 10-
Start from 15 ° C and gradually raise the temperature (eg 80
℃) is also possible.

The time required for microparticulation has a relationship with temperature and cannot be unconditionally limited, but generally the total time of homogenization, addition of alkali, and microparticulation including time is 0.5 to 10 hours. It is a degree.

In the method of the present invention, the average particle size is 0.1.
In order to obtain spherical silicone fine particles of ˜20 μm, the particle size can be freely controlled by selecting the mixing ratio of the raw material and water, the addition amount of the alkali, and the temperature at the time of preparing the uniform solution.

The method of the present invention is particularly suitable for producing relatively large particles having an average particle size of 1 μm or more. That is, in order to obtain particles of 1 μm or more, the mixing ratio of the raw material to the water is set to be high, for example, 0.1 to 1 part by weight with respect to 1 part by weight of water, and the amount of alkali added is very small. For example, strong base caustic soda can be produced by selecting a condition of 500 ppm or less with respect to a homogeneous solution.

Therefore, it is easily affected by the quality of the raw material and the used water, and the chlorine content in the raw material methyltrialkoxysilane and / or its partial hydrolysis-condensation product, which is the method of the present invention, is set to 10 ppm or less, and it is used. Specific electric conductivity of 30μs / which reduces the content of ionic substances in water as much as possible
It is necessary to use pure water of less than cm.

The spherical silicone fine particles produced in this manner are then filtered, separated, washed with water or washed with an organic solvent. After neutralization by adding an acidic substance, they are similarly separated by filtration, washed with water or washed with an organic solvent. And dry and optionally crush 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 μm, a coefficient of variation of 5% or less, and less aggregation between particles. .

[0037]

EXAMPLES The contents of the present invention will be described below with reference to examples.

In the evaluation of the fine particles produced in the examples, 50 or more particles were measured from a scanning electron micrograph, and the average particle diameter (D) [μm], the long diameter / short diameter ratio, and the variation coefficient [particle diameter standard deviation σ]. / Average particle diameter D × 100 (%)] was calculated.
The yield was represented by (methylsilsesquioxane / methyltrialcooxysilane) [mol%].

Example 1 A 1-liter four-necked round-bottomed flask was equipped with a stirrer, a thermometer, and a dropping funnel, and 600 g of ion-exchange treated water having a specific electric conductivity of 0.5 μs / cm was put into the flask and stirred at 200 rpm. The temperature was raised in an oil bath. When the temperature reached 60 ° C., 75 g of methyltrimethoxysilane having a chlorine content of 0.5 ppm was added, and after about 5 minutes, the temperature rose to 62 ° C. due to heat generation, at which point the reaction system became an average transparent solution. 30 minutes after adding methyltrimethoxysilane, 1
6.0 ml of N-NaOH aqueous solution was added. 3 at 200 rpm
At the time of stirring for 0 seconds, white turbidity started and stirring was stopped at the same time. After keeping the temperature at 60 to 65 ° C. for 1 hour, most of the fine particles that have settled are reslurried by stirring and then 10% acetic acid water 3.
6 g was added, neutralized, filtered, washed with water and washed with methanol, and finally dried in an oven at 150 ° C. for 2 hours to obtain 34 g of a white powder (yield 93% mol%). As a result of measuring the particle size with a scanning electron microscope, it was found to be non-aggregated spherical silicone fine particles having an average particle size of 1.1 μm, a major axis / minor axis ratio of 1.03 and a coefficient of variation of 3.0%.

Example 2 A 1-liter four-necked round bottom flask was equipped with a stirrer, a thermometer and a dropping funnel, and 600 g of water having a specific electric conductivity of 20 μs / cm was put in the flask and stirred in an oil bath at 200 rpm. The temperature was raised. After reaching 50 ℃, chlorine content 0.1ppm
40 g of methyltrimethoxysilane was added. After 10 minutes, it turned into a uniform transparent solution. Methyltrimethoxysilane was added, and after 30 minutes had passed, 21 g of a 10 wt% aqueous sodium hydroxide solution was added all at once to the homogeneous solution stirred at 200 rpm. The reaction system became cloudy in 4 to 5 seconds. Temperature 5
After treatment at 0 to 55 ° C. and stirring at 200 rpm for 1 hour, 31.5 g of 10 wt% acetic acid was added to neutralize. It was filtered, washed with water and washed with methanol, and dried in an oven at 150 ° C. for 2 hours to obtain 15.0 g of a white powder (yield 77 mol%).

As a result of observing this powder with a scanning electron microscope, the average particle diameter was 0.5 μm, the ratio of major axis / minor axis was 1.07,
The spherical silicone fine particles had a coefficient of variation of 5%. The aggregation of particles was such that a small amount of 2 to 4 aggregates was found.

Example 3 The same procedure as in Example 2 was carried out except that 30 g of an aqueous solution of 20% by weight ethylenediamine was used as the alkali.

The dry powder obtained was 18.2 g (yield 93
Mol%). Average particle size 0.9 μm, ratio of major axis / minor axis 1.
03, true spherical silicone fine particles having a coefficient of variation of 4.5%.

Example 4 Ion-exchange resin treated water 525 having a specific electric conductivity of 0.5 μs / cm
g, homogenization, atomization, and post-treatment were carried out in the same manner as in Example 1 except that 150 g of a 50 wt% aqueous solution of a partial hydrolyzed condensate of methyltrimethoxysilene was used. Agglomerated spherical silicone fine particles having a ratio of minor axis of 1.05 and a coefficient of variation of 4.5% were obtained (yield 90 mol%).

Comparative Examples 1 to 6 Using the same apparatus as in Example 1, the amount of water charged was 600 g,
The stirring, temperature, and standing time were set in the same manner as in Example 1, and the amount of chlorine in the raw material methyltrimethoxysilane and / or its partial hydrolysis-condensation product, the specific conductivity of the charged water, water /
Table 1 shows the results obtained by changing the weight ratio of raw materials and the amount of alkali added.

[0046]

[Table 1] * 1: Tap water is used as it is.

* 2: Pure water obtained by treating tap water with an ion exchange resin.

* 3: NaCl in pure water that has been subjected to ion exchange treatment
Water added with 50 ppm.

* 4: NH ₄ Cl 2 in ion exchange treated water
Water added with 0 ppm.

* 5: CH ₃ COON in ion-exchanged water
a Water added with 50 ppm.

[0051]

According to the method of the present invention, the average particle diameter is 0.
When the particle size is 1 to 20 μm, it is possible to produce spherical silicone fine particles having a very narrow particle size distribution and less aggregation of particles.

Further, the fine particles obtained by the present invention are added to cosmetics, paints, adhesives, etc. to obtain water repellency, heat resistance,
It has the effect of improving the sliding property and the like, and can be effectively used as a relieving agent and an absorbent of stress caused by curing and shrinkage and expansion by being added to the resin. In addition, a new function can be imparted and used by adsorbing and binding a dye, an ultraviolet absorber or the like on the surface, or plating a metal.

Claims (1)

[Claims] 1. Methyltrialkoxysilane and / or its partial hydrolysis-condensation product 0.0 per 1 part by weight of water.
After stirring and mixing 1 to 1 part by weight to form a uniform solution, an alkali is added to proceed hydrolysis and condensation to produce spherical silicone microparticles, and the methyltrialkoxysilane and / or its partial hydrolyzed condensate is produced. A spherical silicone fine particle having an average particle diameter of 0.1 to 20 μm, which is characterized in that the chlorine content in the water is 10 ppm or less and the specific conductivity of the water is 30 μs / cm or less. Production method.