JP3970453B2 - Method for producing silicone fine particles - Google Patents

Description

［実施例７〜９］第１工程において用いた反応容器より保温性に優れた反応容器を用いて、表２に示した条件でポリメチルシルセスキオキサン微粒子を得た。結果を表３に示す。
【００４６】
また実施例７〜９で得られた微粒子を走査型電子顕微鏡によって撮影した像を図１〜図３に示す。
【００４７】
【表２】

【表３】

［比較例１］
温度計、還流器および撹拌機を備えた反応容器に、電気伝導度０．１６８ｍＳ／ｍの蒸留水１２４２部を仕込み、塩酸水溶液を添加して混合溶液の電気伝導度を２０３０ｍＳ／ｍとした。これを２５℃で撹拌しつつ、メチルトリメトキシシラン１３６０部を添加したところ、加水分解が進行し、３分間で温度が６１℃まで上昇し、透明な反応液が得られた。ついで、撹拌を数時間継続したところ溶液が白濁し、撹拌を停止すると反応液は２層に分離した。この下層を分液して分析したところ、分子量増大により析出したメチルシラントリオールおよび／またはその部分縮合物がその主成分であることが分かった。
【図面の簡単な説明】
【図１】は、実施例７のポリメチルシルセスキオキサン微粒子の粒子構造を示す写真である。
【図２】は、実施例８のポリメチルシルセスキオキサン微粒子の粒子構造を示す写真である。
【図３】は、実施例９のボリメチルシルセスキオキサン微粒子の粒子構造を示す写真である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing silicone fine particles. More specifically, the present invention relates to a method for producing silicone fine particles having a spherical shape, uniform particle diameters, and capable of precisely controlling the average particle size in the range of 0.1 μm to 1 μm. It relates to a manufacturing method.
[0002]
[Prior art]
Conventionally, the following methods are known as methods for producing silicone fine particles.
[0003]
Japanese Patent Application Laid-Open No. 60-13813 neutralizes methyltrialkoxysilane and / or its partial hydrolysis condensate with chlorine atoms present in the methyltrialkoxysilane and / or its partial hydrolysis condensate. It is disclosed that a polymethylsilsesquioxane powder excellent in free-flowing property can be obtained by hydrolysis and condensation in an aqueous solution of ammonia or amine with a sufficient amount necessary for the addition of a catalyst and a necessary amount as a catalyst. Has been.
[0004]
Japanese Patent Application Laid-Open No. 63-77940 discloses a method for producing spherical silicone fine particles as methyl-polyalkoxysilane and / or a partial hydrolysis condensate thereof or methyltrialkoxysilane and / or a partial hydrolysis condensation thereof. The mixed liquid of the product and the organic solvent is the upper layer, and the mixed liquid of ammonia and / or amine and the organic solvent is the lower layer, and methyl 卜 alkoxysilane and / or its partial hydrolysis condensate is hydrolyzed at these interfaces. A method for producing a polymethylsilsesquioxane powder is disclosed in which the particles are condensed in the form of independent spheres and the particle size distribution is in the range of ± 30% of the average particle size.
[0005]
Further, JP-A-63-295537 discloses that the amount of methyltrialkoxysilane and / or its partial hydrolysis condensate is 1/10 or less of the weight of water, particularly ammonia and / or amine. The manufacturing method which obtains spherical silicone powder whose average particle diameter is 0.05-0.8 micrometer by making the density | concentration of 0.01-5 weight% is disclosed.
[0006]
The silicone powder obtained by such a method is used as a modifying additive in paints, plastics, rubbers, cosmetics, paper, and the like for the purpose of imparting water repellency and imparting slipperiness.
[0007]
However, in the production method according to JP-A-60-13813, spherical silicone fine particles cannot be obtained. In addition, the method described in JP-A-63-77940 cannot obtain spherical silicone fine particles having a particle size range of 0.1 to 1.0 μm.
By the way, the silicone fine particles used for the purpose of imparting the slipperiness of the plastic film for video tapes have an average particle diameter of 0.1 to 1.0 μm and a variation (standard deviation) of the average particle diameter for each production unit is ±. Control within an extremely narrow variation range of 0.05 μm is required.
[0008]
However, the manufacturing method described in Japanese Patent Laid-Open No. 63-295537 cannot be controlled within such a narrow variation range, and there is a problem that the apparatus efficiency is insufficient, such as using a large amount of water. It was.
[0009]
[Problems to be solved by the invention]
The present invention has been made to solve such a conventional problem, and provides a method for producing silicone fine particles capable of precisely and efficiently controlling the average particle diameter within a range of 0.1 μm to 1 μm. Objective.
[0010]
The method for producing silicone fine particles of the present invention comprises: (A) General formula: CH ₃ Si (OR) ₃ ( I )
(Wherein R represents a substituted or unsubstituted alkyl group) is hydrolyzed in acidic water adjusted to an electric conductivity of 0.5 to 200 mS / m by adding hydrochloric acid. Te, one general _{formula: CH 3 Si (OH) 3} ...... (II)
A water / alcohol solution of methylsilane triol and / or its partial condensate represented by formula (B): (B) a water / alcohol solution of said methylsilane triol and / or its partial condensate is dropped into an alkaline aqueous solution and And a step of performing a condensation reaction to obtain a suspension containing silicone fine particles.
[0011]
Silicone fine particles obtained by the production method of the present invention are spherical, and the average particle size is extremely uniform in the range of 0.1 μm to 1 μm, and the variation (standard deviation) in average particle size for each production unit is ± 0. It is controlled within a very narrow variation range of .05 μm.
[0012]
The manufacturing method of the present invention comprises the following two steps.
[0013]
In the first step (step (A)) of the production method of the present invention, the methyltrialkoxysilane represented by the general formula (I) is hydrolyzed in the presence of an acid catalyst to produce the general formula (II). ), And / or a partial condensate thereof.
[0014]
As the methyltrialkoxysilane in the first step, for example, a product obtained by alkoxylating methyltrichlorosilane with an appropriate alcohol by a known method can be used. That is, R in the general formula (I) is an alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group, and a 2-methoxyethyl group, a 2-ethoxyethyl group, a 2-propoxyethyl group, or a 2-butoxy group. Examples include substituted alkyl groups such as an ethyl group.
[0015]
Among these, a methyl group, an ethyl group, and a 2-methoxyethyl group are preferable from the viewpoint of reaction rate, and a methyl group is particularly preferable.
[0016]
In the hydrolysis reaction in the first step, an inorganic acid aqueous solution in which an inorganic acid serving as a catalyst is dissolved in excess water is used. The purpose of using the inorganic acid as the acid catalyst is to control the molecular weight of the resulting methylsilanetriol and / or its partial condensate by controlling the hydrolysis reaction.
[0017]
When an organic acid is used as the acid catalyst, it becomes difficult to efficiently control the hydrolysis reaction.
[0018]
Examples of the inorganic acid used as the acid catalyst in the present invention include hydrochloric acid and hydroacid such as hydrofluoric acid, and oxoacid such as sulfuric acid and nitric acid. Hydrochloric acid is preferred because it is easily available and handled.
[0019]
The amount of the acid catalyst used is such that the electrical conductivity of the aqueous solution used when hydrolyzing methyltrialkoxysilane is 0.1 to 200 mS / m, preferably 0.5 to 100 mS / m.
[0020]
When the electrical conductivity of water added with an acid catalyst is less than 0.1 mS / m, hydrolysis does not proceed sufficiently, and when it exceeds 200 mS / m, the variation in particle diameter should be controlled within a very narrow variation range. Becomes difficult.
[0021]
In addition, as water to which the acid catalyst is added in the first step (water before addition of the acid catalyst), ion-exchanged water having an electric conductivity of 1.0 mS / m or less is preferable, and ions having 0.5 mS / m or less are further preferable. More preferably, it is exchange water.
[0022]
The amount of water used for the hydrolysis in the first step is preferably 2 to 10 mol with respect to 1 mol of methyltrialkoxysilane. When the amount of water is less than 2 mol, hydrolysis does not proceed sufficiently, and when it exceeds 10 mol, methylsilanetriol and / or its partial condensate becomes unstable and tends to precipitate.
[0023]
The temperature at the time of hydrolysis is preferably in the range of 10 to 60 ° C. in order to precisely control the average particle size and standard deviation of the final silicone fine particles, and the reaction is preferably carried out within this range. The hydrolysis reaction in the first step is performed by continuing stirring of the mixed solution for 1 to 10 hours.
[0024]
The second step (the step (B)) of the production method of the present invention is an aqueous alkali solution obtained from methylsilanetriol and / or a partial condensate thereof obtained in the first step or further diluted with water. This is a step of adding a suspension containing silicone fine particles by polycondensation reaction.
[0025]
It is not necessary to add an organic solvent to control the particle size.
[0026]
The alkali used in the second step is not particularly limited as long as the aqueous solution exhibits basicity, and this alkali is used as a neutralizing agent for the inorganic acid used in the first step, and further for the polycondensation reaction in the second step. Acts as a catalyst.
[0027]
Examples of such alkali include metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, or amines such as ammonia, monomethylamine and dimethylamine. Among these, ammonia or amines such as monomethylamine and dimethylamine are preferable because they do not leave a trace amount of impurities that limit the use of the silicone fine particles, and ammonia is particularly preferable because it can be easily removed. The amount of the alkali used is an amount that neutralizes the inorganic acid and effectively acts as a catalyst for the polycondensation reaction. For example, in the case of using ammonia as the alkali, all the amounts used in the first step and the second step are used. 0.05 parts by weight or more (as NH ₃ ) is used with respect to 100 parts by weight of water.
[0028]
The required amount of alkali added can be easily determined experimentally, although the degree of dissociation differs for each alkali.
[0029]
In the polycondensation reaction in the second step, an aqueous alkali solution is charged into a reaction vessel, and methylsilanetriol and / or a partial condensate thereof (hereinafter referred to as “silano”) obtained in the first step while sufficiently stirring the inside of the reaction vessel. The solution is referred to as “one solution” and is brought into contact with the alkaline solution.
[0030]
The dropping rate of the silanol solution is preferably such that the entire amount is dropped over 5 minutes or more, and more preferably over 10 to 240 minutes. Basically, if the amount of hydrolyzate adjusted in the first step increases, the scale of the second step also increases, so if the dropping rate per unit time is the same, the dropping time varies greatly depending on the reaction scale. There is no. The stirring in the second step is preferably continued for about 2 to 10 hours after the dropping, as well as during the dropping of the silanol solution.
[0031]
By performing the polycondensation reaction in this way, a suspension containing silicone fine particles can be obtained. Furthermore, if necessary, dehydration, drying and crushing can be performed to obtain silicone fine particles.
[0032]
【The invention's effect】
According to the production method of the present invention, silicone fine particles whose average particle size is precisely controlled can be obtained with good yield and apparatus efficiency in an average particle size range of 0.1 μm to 1 μm, which is difficult with the conventional production method. be able to.
[0033]
The silicone fine particles obtained by the production method of the present invention are useful as surface modifiers for paints, plastics, rubbers, papers and the like.
[0034]
In particular, it is suitable as a slipperiness imparting agent and heat resistance imparting agent for plastic films used for video tapes and video printer tapes.
[0035]
【Example】
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 present invention is not limited by these examples.
[0036]
[Example 1]
First step : The electric conductivity measured by using an electric conductivity meter (CM-11P manufactured by Toa Denpa Kogyo Co., Ltd.) in a reaction vessel equipped with a thermometer, a refluxer and a stirrer is 0.136 mS. 1242 parts of distilled water / m was added, and an aqueous hydrochloric acid solution was added to make the electric conductivity of the mixed solution 9.96 mS / m.
[0037]
When 1360 parts of methyltrimethoxysilane was added while stirring this solution at 23 ° C., hydrolysis proceeded, the temperature rose to 50 ° C. in about 5 minutes, and a transparent reaction solution was obtained. Subsequently, stirring was continued for 3 hours, followed by filtration to obtain a silanol solution.
[0038]
The average molecular weight of methylsilanetriol and / or its partial condensate in the silanol solution obtained by this hydrolysis reaction was measured by GPC (gel permeation chromatography) using THF (tetrahydrofuran) as a developing solvent. . GPC measurement was performed using GPC system-11 manufactured by Showa Denko. The measured average molecular weight was 430.
[0039]
Second step: 3875 parts of water and 23 parts of 25% aqueous ammonia solution were charged into a reaction vessel equipped with a thermometer, a reflux condenser and a stirrer.
[0040]
While stirring this at 24 ° C., 1000 parts of the silanol solution obtained in the first step was added dropwise over about 10 minutes.
[0041]
After completion of dropping, stirring was continued for 6 hours. During the stirring, polymethylsilsesquioxane fine particles were precipitated, and the reaction solution turned into a milky white dispersion.
[0042]
This was centrifuged to remove the fine particles, which were taken out and dried in a dryer at 200 ° C. for 24 hours to obtain white fine particles.
[0043]
When the fine particles were observed with an electron microscope, the particle shape was spherical, the average particle size was 0.68 μm, and the standard deviation was 0.09 μm.
[0044]
When the fine particles were put in a magnetic crucible and thermally decomposed by heating to 900 ° C. in air, the remaining amount was 89.1%. This is a value close to the theoretical amount of 89.6% in which polymethylsilsesquioxane is oxidized and thermally decomposed into silicon dioxide. Moreover, as a result of X- ray analysis of this thermal decomposition product, it was confirmed that it was amorphous silica. It was confirmed that the white fine particles obtained from this were polymethylsilsesquioxane.
[Examples 2 to 6] In the same manner as in Example 1, polymethylsilsesquioxane fine particles were obtained under the conditions shown in Table 1. The results are shown in Table 3 .
[0045]
[Table 1]

[Examples 7 to 9] Polymethylsilsesquioxane fine particles were obtained under the conditions shown in Table 2 using a reaction vessel having better heat retention than the reaction vessel used in the first step. The results are shown in Table 3.
[0046]
Moreover, the image which image | photographed the microparticles | fine-particles obtained in Examples 7-9 with the scanning electron microscope is shown in FIGS.
[0047]
[Table 2]

[Table 3]

[Comparative Example 1]
In a reaction vessel equipped with a thermometer, a refluxer and a stirrer, 1242 parts of distilled water having an electric conductivity of 0.168 mS / m was charged, and an aqueous hydrochloric acid solution was added to make the electric conductivity of the mixed solution 2030 mS / m. When 1360 parts of methyltrimethoxysilane was added while stirring this at 25 ° C., hydrolysis proceeded, the temperature rose to 61 ° C. in 3 minutes, and a transparent reaction solution was obtained. Subsequently, when stirring was continued for several hours, the solution became cloudy. When the stirring was stopped, the reaction solution was separated into two layers. When the lower layer was separated and analyzed, it was found that methylsilanetriol and / or a partial condensate thereof precipitated due to the increase in molecular weight was the main component.
[Brief description of the drawings]
1 is a photograph showing the particle structure of polymethylsilsesquioxane fine particles of Example 7. FIG.
2 is a photograph showing the particle structure of polymethylsilsesquioxane fine particles of Example 8. FIG.
FIG. 3 is a photograph showing the particle structure of polymethylsilsesquioxane fine particles of Example 9.

Claims (4)

(A) General formula: CH ₃ Si (OR) ₃ ( I )
(Wherein R represents a substituted or unsubstituted alkyl group) is hydrolyzed in acidic water adjusted to an electric conductivity of 0.5 to 200 mS / m by adding hydrochloric acid. Te, one general _{formula: CH 3 Si (OH) 3} ...... (II)
Obtaining a water / alcohol solution of methylsilanetriol and / or its partial condensate represented by:
(B) adding a water / alcohol solution of the methylsilanetriol and / or a partial condensate thereof to an alkaline aqueous solution to cause a polycondensation reaction to obtain a suspension containing silicone fine particles. A method for producing silicone fine particles. The method for producing silicone fine particles according to claim 1, wherein the average molecular weight of methylsilanetriol and / or its partial condensate produced in the step (A) is in the range of 100 to 1,000. The method for producing silicone fine particles according to claim 1 or 2, wherein the water to which hydrochloric acid is added in the step (A) is ion-exchanged water having an electric conductivity of 0.5 mS / m or less. The method for producing silicone fine particles according to any one of claims 1 to 3, wherein the amount of water used in the step (A) is in the range of 2 to 10 mol with respect to 1 mol of methyltrialkoxysilane.

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