JP5953942B2 - Silicone fine particles and method for producing the same - Google Patents

Description

  The present invention relates to silicone fine particles and a method for producing the same, and more particularly to spherical silicone fine particles having a small particle diameter of about 0.05 to 1.0 μm and a method for producing the same.

  Various techniques are known as techniques for producing silicone fine particles. For example, Patent Document 1 describes a method for producing silicone fine particles using organotrialkoxysilane. Patent Document 2 describes a method for producing silicone fine particles using trialkylsiloxytrialkoxysilane and organotrialkoxysilane. As a similar example, Patent Document 3 describes a method for producing silicone fine particles using methyltrialkoxysilane. As described above, many methods for producing silicone fine particles using only trialkoxysilane (trifunctional alkoxysilane) have been disclosed.

  Patent document 4 discloses a method for producing silicone fine particles using tetraalkoxysilane, trialkoxysilanol and organotrialkoxysilane. Furthermore, for the purpose of further reducing the particle size of the silicone fine particles, Patent Document 5 discloses a method for producing silicone fine particles using organotrialkoxysilane and tetraalkoxysilane.

Japanese Patent Laid-Open No. 5-140314 JP-A-5-148364 JP-A-6-49209 JP-A-6-192426 JP 2001-192452 A

  In the conventional method for producing silicone fine particles using only trifunctional alkoxysilane, it has been difficult to produce silicone fine particles having a smaller particle size, for example, a particle size of about 0.05 to 1.0 μm. Even in this method, it is not impossible to reduce the diameter by using a large amount of solvent in the production stage. However, in this case, mass productivity is remarkably lowered, so that it is difficult to say that the method can be practically used industrially. In addition, when silicone fine particles were produced using only trifunctional alkoxysilane, the resulting silicone fine particles were likely to have silanol groups remaining, and could not exhibit sufficient hydrophobicity depending on the application.

  As described in Patent Documents 4 and 5, in the method using a combination of alkoxysilanes other than trialkoxysilane, although the diameter can be reduced, the synthesis reaction of the silicone fine particles does not proceed sufficiently or is still sufficient. Inconveniences such as inability to obtain hydrophobicity were likely to occur.

  Therefore, the present invention has been made in view of such circumstances, and provides a silicone fine particle that has a smaller particle diameter than conventional ones and can exhibit high hydrophobicity, and a method for producing the same. Objective.

  In order to achieve the above object, the silicone fine particles of the present invention contain a tetrafunctional alkoxysilane, a trifunctional alkoxysilane, and a bifunctional alkoxysilane, and the content of the tetrafunctional alkoxysilane in the total thereof is 2 mol% or more and 15%. It is characterized by being not more than mol%.

  The silicone fine particles of the present invention contain at least a combination of tetrafunctional, trifunctional and bifunctional alkoxysilanes, and the total amount of tetrafunctional alkoxysilanes in the total is within the specific range. In addition, a sufficiently cross-linked structure is formed, so that suitable particles can be obtained, and high hydrophobicity can be exhibited because the residual amount of silanol groups is small.

  In the silicone fine particles of the present invention, the molar ratio of trifunctional alkoxysilane to bifunctional alkoxysilane (trifunctional alkoxysilane: bifunctional alkoxysilane) is preferably in the range of 3: 7 to 7: 3. Thereby, it becomes easy to obtain the effect of high hydrophobicity and diameter reduction.

  In addition, the trifunctional alkoxysilane and the bifunctional alkoxysilane preferably have a methyl group or a phenyl group bonded to an Si atom. When the trifunctional and bifunctional alkoxysilanes have these structures, the silicone fine particles of the present invention are easily obtained.

  As described above, the silicone fine particles of the present invention are likely to have a sufficiently small particle diameter because of having the above-mentioned specific configuration, and specifically, the particle diameter is 0.05 to 1.0 μm. easy.

  The present invention also provides a first step in which acid and water are added to a mixture containing tetrafunctional alkoxysilane, trifunctional alkoxysilane and bifunctional alkoxysilane to cause hydrolysis, and an alkali is added to the mixture after the first step. And a method of producing a silicone fine particle comprising a step of condensing to produce a silicone fine particle.

  In such a method for producing silicone fine particles of the present invention, since tetrafunctional, trifunctional and bifunctional alkoxysilanes are used in combination, it is easy to reduce the size of the silicone fine particles, and excessively silanol groups. Can be easily prevented, so that silicone fine particles having high hydrophobicity can be obtained.

  In the method for producing silicone fine particles of the present invention, in the first step, the content of tetrafunctional alkoxysilane in the total of tetrafunctional alkoxysilane, trifunctional alkoxysilane and bifunctional alkoxysilane is 2 mol% or more and 15 mol. % Or less is preferable. Thereby, in addition to being able to form a sufficient cross-linked structure even if the diameter is further reduced, it becomes possible to further reduce the residual amount of silanol groups and obtain silicone fine particles having better hydrophobicity.

  In the first step, the molar ratio of trifunctional alkoxysilane to bifunctional alkoxysilane (trifunctional alkoxysilane: bifunctional alkoxysilane) is preferably in the range of 3: 7 to 7: 3. In this case, the remaining amount of silanol groups can be effectively reduced while causing sufficient crosslinking, so that it is easier to reduce the diameter and it is easier to obtain excellent hydrophobicity.

  In addition, the trifunctional alkoxysilane and the bifunctional alkoxysilane preferably have a methyl group or a phenyl group bonded to an Si atom. When the trifunctional and bifunctional alkoxysilanes have these structures, the silicone fine particles can be easily synthesized, so that the silicone fine particles can be produced more easily.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the silicone fine particle which has a small particle diameter compared with the past, and can exhibit high hydrophobicity, and its manufacturing method.

  Hereinafter, preferred embodiments of the present invention will be described.

  A silicone fine particle of a preferred embodiment includes a combination of a tetrafunctional alkoxysilane, a trifunctional alkoxysilane, and a bifunctional alkoxysilane. And content of the tetrafunctional alkoxysilane in these sum total is 2 mol% or more and 15 mol% or less. The shape of the silicone fine particles of the present embodiment is not particularly limited and can be appropriately selected according to the use. However, since the diameter can be reduced and it can be applied to various uses, a spherical shape is preferable.

  Here, the alkoxysilane in the present embodiment is a compound in which an alkoxy group is bonded to a silicon (Si) atom. The group other than the alkoxy group bonded to the Si atom is not particularly limited, and a group capable of bonding to the Si atom in the alkoxysilane is usually selected. For example, an alkyl group, an alkenyl group, and a phenyl group can be mentioned. An alkoxysilane having four alkoxy groups bonded to Si atoms is a tetrafunctional alkoxysilane, and similarly, an alkoxysilane having three alkoxy groups bonded to Si atoms is a trifunctional alkoxysilane. Yes, an alkoxysilane having two alkoxy groups bonded to Si atoms is a bifunctional alkoxysilane.

As such alkoxysilane, for example, a compound having a structure represented by the formula (A) is preferable.
(R ¹ ) _n Si (OR ² ) _4-n (A)

In formula (A), R ¹ represents an alkyl group, an alkenyl group or a phenyl group, and when there are a plurality of R ^{1 s} , they may be the same or different. R ² represents an alkyl group, and when there are a plurality of R ² , they may be the same or different. In the compound represented by the formula (A), a compound in which n is 0 in the formula (A) is a tetrafunctional alkoxysilane, a compound in which n is 1 is a trifunctional alkoxysilane, and a compound in which n is 2 It corresponds to each bifunctional alkoxysilane.

In formula (A), examples of R ¹ include an alkyl group having 1 to 6 carbon atoms, an alkyl group having 2 to 6 carbon atoms, and a phenyl group. From the viewpoint of easily generating a reaction for obtaining silicone fine particles, R ¹ is preferably a methyl group or a phenyl group. As the R ^2, include methyl group, ethyl group or propyl group.

  Examples of the tetrafunctional alkoxysilane include tetramethoxysilane, tetraethoxysilane, and tetra-n-propoxysilane. The tetrafunctional alkoxysilane may contain only one type or a plurality of types. Especially, since tetramethoxysilane and tetraethoxysilane are easily hydrolyzed, the silicone fine particles containing these tend to be easily manufactured. In particular, tetramethoxysilane is preferable because it easily forms silicone fine particles having good characteristics in terms of size reduction and hydrophobicity.

  Examples of the trifunctional alkoxysilane include methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, methyltri-n-propoxysilane, and methyltriisopropoxysilane. Among these, since methyltrimethoxysilane has good reactivity, the production of silicone fine particles containing methyltrimethoxysilane is easy.

  Examples of the bifunctional alkoxysilane include dimethyldimethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, and diphenyldiethoxysilane. Among them, since dimethyldimethoxysilane has good reactivity, the production of silicone fine particles containing methyltrimethoxysilane is easy.

In the silicone fine particles of the present embodiment, the content of the tetrafunctional alkoxysilane is 2 mol% or more and 15 mol% or less in the total of the tetrafunctional alkoxysilane, the trifunctional alkoxysilane, and the bifunctional alkoxysilane. The content of the tetrafunctional alkoxysilane can be derived according to the following formula (B).
Content of tetrafunctional alkoxysilane (mol%) = number of moles of tetrafunctional alkoxysilane / (number of moles of tetrafunctional alkoxysilane + number of moles of trifunctional alkoxysilane + number of moles of bifunctional alkoxysilane) × 100 (B)

  When the content of the tetrafunctional alkoxysilane is less than 2 mol%, the synthesis reaction does not proceed sufficiently at the time of the synthesis of the silicone fine particles, the dispersion of the particle diameter becomes large, and a sufficient crosslinked structure is not formed. When the diameter is reduced, a good particle shape (spherical shape) cannot be maintained. On the other hand, if the content of the tetrafunctional alkoxysilane exceeds 15 mol%, the reaction will occur excessively during the synthesis of the silicone fine particles, resulting in a large variation in the particle diameter, and the residual amount of silanol groups will increase, which is sufficient. Hydrophobicity cannot be obtained.

  The silicone fine particles of this embodiment contain a combination of tetrafunctional, trifunctional and bifunctional alkoxysilanes. As a result of the study by the present inventors, it has been found that, when bifunctional alkoxysilane is contained, high hydrophobicity is obtained, but synthesis reaction does not occur well during the production of silicone fine particles, and it is difficult to obtain fine particles. did. On the other hand, by including 2 to 15 mol% of tetrafunctional alkoxysilane as in the present embodiment, it is possible to reduce such inconvenience, and as a result, the particle diameter is small and the particle diameter varies. Even small silicone fine particles can be obtained.

  In the silicone fine particles, the molar ratio of trifunctional alkoxysilane to bifunctional alkoxysilane (trifunctional alkoxysilane: bifunctional alkoxysilane) is preferably in the range of 3: 7 to 7: 3.

  When the ratio of the trifunctional alkoxysilane to the bifunctional alkoxysilane is larger than the range of this molar ratio, the residual amount of silanol groups may increase, and the hydrophobicity may be reduced as compared with the case within this range. On the other hand, when the ratio of the bifunctional alkoxysilane to the trifunctional alkoxysilane is larger than the range of this molar ratio, a sufficient cross-linked structure is not formed and it is difficult to obtain small-sized fine particles as compared with the case within this range. There is a fear.

The tetrafunctional alkoxysilane, the trifunctional alkoxysilane, and the bifunctional alkoxysilane contained in the silicone fine particles have the same group corresponding to R ² in the above formula (A), and the reaction in the production of the silicone fine particles It tends to occur and tends to be easy to manufacture. For example, combinations of tetrafunctional alkoxysilane, trifunctional alkoxysilane, and bifunctional alkoxysilane include tetramethoxysilane, methyltrimethoxysilane, and dimethyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane. The combination of is mentioned.

  In addition to the tetrafunctional alkoxysilane, the trifunctional alkoxysilane, and the bifunctional alkoxysilane, the silicone fine particles may further contain other components to the extent that the characteristics are not excessively affected. For example, the silicone fine particles may contain monofunctional alkoxysilane to such an extent that the effects of the present invention are not reduced.

  Next, an example of a method for producing the silicone fine particles of the preferred embodiment described above will be described.

  First, a tetrafunctional alkoxysilane, a trifunctional alkoxysilane, a bifunctional alkoxysilane, and other components as necessary are prepared as raw materials for the silicone fine particles, and these are blended to obtain a mixture. As these components, those similar to those described above for the silicone fine particles can be applied.

  Under the present circumstances, it mix | blends so that the quantity of tetrafunctional alkoxysilane may be 2 mol% or more and 15 mol% or less with respect to the sum total of tetrafunctional alkoxysilane, trifunctional alkoxysilane, and bifunctional alkoxysilane. This makes it possible to produce silicone fine particles with a moderately crosslinked structure due to hydrolysis and condensation reactions, which will be described later, so that the particle size is small and the particle size variation is small, and silanol groups do not exist excessively, and are highly hydrophobic. Silicone fine particles having the above can be obtained.

  In the mixture, the molar ratio of trifunctional alkoxysilane to bifunctional alkoxysilane (trifunctional alkoxysilane: bifunctional alkoxysilane) is preferably in the range of 3: 7 to 7: 3. This makes it possible to form an appropriate crosslinked structure in the synthesis reaction of the silicone fine particles to produce fine particles, and to easily obtain silicone fine particles having excellent hydrophobicity.

  In the production of silicone fine particles, an acid and water are added to such a mixture to cause a hydrolysis reaction (first step). As the acid, either an organic acid or an inorganic acid can be applied. Examples of the organic acid include formic acid, acetic acid, propionic acid, oxalic acid, maleic acid, succinic acid, and citric acid. Of these, acetic acid is preferred. On the other hand, examples of the inorganic acid include sulfuric acid, nitric acid, hydrochloric acid and the like. Of these, hydrochloric acid is preferred. By adding these acids in the form of an aqueous solution, both acid and water can be added to the mixture.

The amount of acid added is preferably such that the acid concentration is in the range of 1 to 100 × 10 ⁻⁵ normal. If the acid concentration is too low, hydrolysis does not proceed easily. On the other hand, if the acid concentration is too high, it is difficult to control the hydrolysis reaction, and in any case, production of silicone fine particles may be difficult.

  Moreover, it is preferable that the quantity of water shall be 10-200 times (mol) with respect to the total amount (mol) of tetrafunctional, trifunctional, and bifunctional alkoxysilane. When the amount of water is less than this, the alkoxysilane is excessively aggregated, and it becomes difficult to obtain silicone fine particles having a small particle diameter. On the other hand, when the amount is larger than this, hydrolysis reaction occurs too much, and subsequent reaction is unlikely to occur and productivity tends to be lowered.

  In the hydrolysis reaction, alcohol may be further added. By further adding alcohol, the hydrolysis reaction rate can be appropriately controlled, and the particle diameter of the resulting silicone fine particles can also be controlled. However, when alcohol is added, the rate of the hydrolysis reaction may be slowed down. Therefore, it is preferable to add alcohol according to the purpose.

  The reaction temperature during the hydrolysis reaction is preferably 5 to 70 ° C. The reaction time is preferably 0.5 to 6 hours.

  As a result of such hydrolysis reaction, the tetrafunctional, trifunctional and bifunctional alkoxysilanes are silanol solutions in which at least part of the alkoxy groups they have is replaced with hydroxy groups to form silanols, and various silanols are contained. Is obtained.

  Next, an alkali is added to the silanol solution (mixture after the first step) generated by the hydrolysis reaction to cause a condensation reaction to generate silicone fine particles (second step). In the second step, an alkali atmosphere is added by adding an amount of alkali more than the acid added in the first step is neutralized, thereby causing a condensation reaction.

  Examples of the alkali include sodium hydroxide, potassium hydroxide, ammonia, and organic amines such as dimethylamine and trimethylamine. Among these, ammonia is preferable because it is easy to remove from the reaction solution and is easy to handle.

  Examples of the method for adding an alkali include a method in which the above alkali is dissolved in water to form an aqueous solution, and this is dropped into a silanol solution. As described above, the dripping amount is set so that an amount of alkali exceeding the amount neutralizing the acid added in the first step is added.

  Specifically, for example, a method in which an aqueous ammonia solution having a concentration of 0.1 to 0.5% is dropped into a silanol solution. In this case, the dropping amount of the aqueous ammonia solution is preferably set to such an amount that ammonia is 0.001 to 0.1 mol with respect to 100 mol of silanol in the silanol solution. When the dropping amount of the aqueous ammonia solution is smaller than this, the speed of the condensation reaction becomes slow, the particle size becomes too large, and the variation in the particle size tends to increase. On the other hand, when the dropping amount of the aqueous ammonia solution is larger than this, the condensation reaction becomes too fast, and there is a possibility that the dispersion of the particle diameter becomes large. As a guide, when dropping an aqueous ammonia solution, it is preferable to set the total dropping amount and dropping rate so that the silanol solution becomes cloudy in about 3 to 30 minutes.

  In the second step, alcohol or a surfactant can be added as needed in addition to the alkali.

  Examples of the alcohol include methanol, ethanol, n-propanol, isopropyl alcohol, n-butanol, 2-butanol, izobutanol, t-butanol and the like. By adding alcohol, it may be possible to moderately adjust the speed of the condensation reaction and to adjust the particle size of the resulting silicone fine particles to some extent.

  As the surfactant, any of anionic, nonionic, cationic and amphoteric surfactants can be applied. Among these, it is preferable to use an anionic surfactant because spherical silicone fine particles tend to be easily obtained. Anionic surfactants include alkyl sulfates, alkylbenzene sulfonates, alkenyl succinates, sulfosuccinates, polyoxyethylene alkyl ether sulfates, fatty acid salts, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene alkyls. Examples include ether acetate.

  When causing the condensation reaction, it is preferable to gently stir the solution obtained by adding alkali or the like to the silanol solution. For example, when a stirring blade is used, the stirring speed is preferably about 50 rpm. As a result, a condensation reaction can be caused to occur moderately, and silicone fine particles having a good particle diameter can be easily obtained.

  The reaction temperature of the condensation reaction is preferably 5 to 70 ° C. The lower the condensation reaction temperature, the smaller the particle size and the easier the particle size to be adjusted. Therefore, the reaction temperature is more preferably in the range of 5 ° C to 20 ° C. The reaction time is preferably 0.5 to 6 hours.

  In such a second step, a condensation (dehydration condensation) reaction occurs between various silanols derived from the tetrafunctional alkoxysilane, the trifunctional alkoxysilane and the bifunctional alkoxysilane generated in the first step, and they are polycondensed. As a result, silicone fine particles having a three-dimensional crosslinked structure represented by -Si-O-Si- are obtained.

  Since the particle size of the silicone fine particles obtained by the above method varies depending on conditions such as the reaction temperature in hydrolysis and condensation reaction, the amount of tetrafunctional alkoxysilane used as a raw material, the amount of solvent, the amount of catalyst, etc. By setting these conditions appropriately, silicone fine particles having a desired particle diameter can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example.

[Manufacture of silicone fine particles]
(Evaluation example 1)
In a reaction vessel equipped with a thermometer, a refluxer and a stirrer, 108 g of ion-exchanged water having an electric conductivity of 0.05 mS / m was added, and hydrochloric acid was added so that the acid concentration became 5 × 10 ⁻⁵ N. . To this solution, while maintaining the condition at 20 ° C., 0.61 g of tetramethoxysilane, 3.4 g of methyltrimethoxysilane, and 3.0 g of dimethyldimethoxysilane were respectively added dropwise, and then stirred at a speed of 50 rpm for 4 hours. A hydrolysis reaction was caused to produce a silanol solution (first step). The dropped alkoxysilane had a molar ratio of tetramethoxysilane: methyltrimethoxysilane: dimethyldimethoxysilane = 0.16: 1: 1.

  Next, while maintaining the obtained silanol solution at 20 ° C., stirring was continued at a speed of 50 rpm, and then a 1% aqueous ammonia solution was dropped into the silanol solution so that the amount of ammonia added was 0.272 g. By stirring for 4 hours, silicone fine particles 1 were obtained (second step).

(Evaluation Examples 2 to 16)
In the same manner as in Evaluation Example 1, except that the amounts of various alkoxysilanes and water (ion-exchanged water) and the reaction temperatures in the first and second steps were changed as shown in Table 1, silicone fine particles 2 to 16 were prepared. I got each.

(Evaluation Example 17)
Half of the methyltrimethoxysilane was replaced with phenyltrimethoxysilane (ie, the molar ratio of tetramethoxysilane: methyltrimethoxysilane: dimethyldimethoxysilane: phenyltrimethoxysilane was 0.16: 0.5: 1: 0. Except that, silicone fine particles 17 were obtained in the same manner as in Evaluation Example 1.

  The conditions in Evaluation Examples 1 to 17 are summarized in Table 1. In addition, Evaluation Examples 1-3, 5-6, 9-11, and 13-17 correspond to Examples that satisfy the conditions of the present invention, and Evaluation Examples 4, 7, 8, and 12 satisfy the conditions of the present invention. There is no comparative example.

[Characteristic evaluation]
(Measurement of particle diameter)
The particle diameter and variation (variation coefficient CV) of the silicone fine particles 1 to 17 were measured by the following method. That is, for each silicone fine particle, an image was captured at a magnification of 45,000 times using a Hitachi SEM (HITACHI S-4800), and the particle size of the silicone fine particle and its variation were measured by processing the image. . And it measured similarly about 100 samples per each silicone microparticle, and measured the average value and the coefficient of variation. The obtained results are shown in Table 2. In Table 2, in the column of the particle diameter result, when the particle diameter cannot be measured because fine particles are not formed or the fine particles are aggregated, the former case is indicated as “non- The case of “particulate” and the latter were indicated as “aggregation”. The remarks column in Table 2 also shows the result of observing the shape of the silicone fine particles. In the same column, when spherical fine particles are formed in a monodispersed state, “spherical”, when the fine particles are dispersed but partially agglomerated, “partially agglomerated”, the fine particles are hardly dispersed. The case where the particles are aggregated is indicated as “aggregate”, and the case where the particles are formed into a jelly without forming fine particles is indicated as “jelly”.

(Water supply rate and 300 ° C weight loss)
The water supply rate of silicone fine particles 1 to 17 and the weight loss at 300 ° C. were measured under the following conditions. For the measurement, TG-DTA (TG / DTA7200) manufactured by SII was used.

  That is, first, the silicone fine particles were removed from the solution by centrifugation, and then dried at 100 ° C. for 1 hour in a vacuum dryer. Next, it was left to stand for 10 hours under conditions of a temperature of 40 ° C. and a humidity of 40%. About this silicone fine particle after standing, the water supply rate and the weight loss at 300 degreeC were measured by TG-DTA. Specifically, the film was heated from 30 ° C. to 105 ° C. at a temperature rising rate of 10 ° C./min, and held at 105 ° C. for 10 minutes. The water absorption was calculated with the weight loss at this time as the water absorption. Next, it heated from 105 degreeC to 300 degreeC with the temperature increase rate of 10 degree-C / min, and hold | maintained at 300 degreeC for 10 minutes. The weight loss at this time was calculated, and the value was regarded as the weight loss at 300 ° C. (the water content was corrected). The obtained results are shown in Table 2.

  As shown in Table 2, first, the silicone fine particles 1 of Evaluation Example 1 were clean spherical fine particles. Although the particle diameter is small, C.I. V. Was a low value. Further, it was confirmed that the water absorption rate was small, so that the hydrophobicity was high and the weight loss at 300 ° C. was small.

  On the other hand, when dimethyldimethoxysilane was not used (Evaluation Example 4), the proportion of methyl groups in the entire silicone fine particles was lower than that in Evaluation Example 1, so that the water absorption was high and the hydrophobicity was insufficient. Turned out to be.

  Evaluation Example 2 and Evaluation Example 3 are examples in which the amount of methyltrimethoxysilane is larger than that of Evaluation Example 1, but good characteristics are obtained except that the water absorption rate is slightly higher than that of Evaluation Example 1. It has been found.

  Evaluation Examples 5 and 6 are examples in which the amount of methyltrimethoxysilane was less than that of Evaluation Example 1, and in each case, silicone fine particles were obtained. However, the silicone fine particles 5 of the evaluation example 5 have more aggregation than the evaluation example 1, and the particle diameter and C.I. V. Was a high value, and the weight loss at 300 ° C. was slightly increased.

  Evaluation Example 7 is an example in which methyltrimethoxysilane was not used. In Evaluation Example 7, three-dimensional cross-linking was not sufficiently formed, and it was difficult to maintain the shape of the particles, and only a jelly-like dimethylsiloxane type silicone was obtained, and silicone fine particles could not be obtained.

  Evaluation Example 8 is a case where tetramethoxysilane was not used. Also in this case, the three-dimensional crosslinking was insufficient, it was difficult to maintain the shape of the particles, and it was impossible to obtain silicone fine particles only by obtaining a jelly-like dimethylsiloxane type silicone.

  Evaluation Examples 9 to 12 are obtained by changing the amount of tetramethoxysilane. Since the silicone fine particles 9 of Evaluation Example 9 have a small amount of tetramethoxysilane, compared with Evaluation Example 1, the crosslinking component is small, the particle diameter is large, and the weight loss at 300 ° C. is large. It was confirmed that as the amounts of 11 and tetramethoxysilane were increased, a small particle size was easily obtained.

  On the other hand, Evaluation Example 12 is a case where tetramethoxysilane was used in excess. In this case, the particles aggregated and monodisperse silicone fine particles could not be produced. From this result, it was found that it is important to use an appropriate amount of tetrafunctional alkoxysilane in order to obtain silicone fine particles having a small particle diameter.

  Evaluation Examples 13 to 15 are obtained by changing the reaction temperature in the second step. From these results, it was found that the smaller the reaction temperature, the smaller the diameter of the particles.

  Evaluation Example 16 is the result when the amount of water is reduced as compared with Evaluation Example 1. Thus, it was found that when the first step is performed under the condition where the acid concentration is high, the particle diameter becomes larger than that in the case of Evaluation Example 1.

  Evaluation Example 17 is a result when a part of methyltrimethoxysilane in Evaluation Example 1 is replaced with phenyltrimethoxysilane. Thus, by using phenyltrimethoxysilane, compared with the evaluation example 1, the fall of water absorption and the fall of 300 degreeC weight reduction were seen.

As described above, according to the evaluation example that satisfies the conditions of the present invention, it was confirmed that silicone fine particles having low water absorption and high hydrophobicity can be obtained. It was also confirmed that submicron-sized silicone fine particles, which were difficult to synthesize in the past, were obtained.

Claims (5)

Tetrafunctional alkoxysilanes, 3 comprise functional alkoxysilane and bifunctional alkoxysilane, the tetrafunctional alkoxy der content of less than 15 mol% 2 mol% or more silanes of these total in is, the said trifunctional alkoxysilane molar ratio of 2-functional alkoxysilane (the trifunctional alkoxysilane: the bifunctional alkoxysilane) is 3: 7 to 7: range der 3 Ru, silicone microparticles, characterized in that. The trifunctional alkoxysilane and the bifunctional alkoxysilane is a methyl group or a phenyl group bonded to Si atom, it is characterized in claim 1 Symbol placement of silicone microparticles. Particle diameter of 0.05 to 1.0 [mu] m, and wherein the claim 1 or 2 Symbol placement of silicone microparticles. A first step of adding acid and water to a mixture containing tetrafunctional alkoxysilane, trifunctional alkoxysilane and bifunctional alkoxysilane to cause hydrolysis;
By adding an alkali to cause the condensation reaction to the mixture after the first step, seen including generating a silicone microparticles, a,
In the first step, the content of the tetrafunctional alkoxysilane in the total of the tetrafunctional alkoxysilane, the trifunctional alkoxysilane, and the bifunctional alkoxysilane is 2 mol% or more and 15 mol% or less, and the trifunctional A method for producing silicone fine particles, wherein a molar ratio of alkoxysilane to the bifunctional alkoxysilane (the trifunctional alkoxysilane: the bifunctional alkoxysilane) is in the range of 3: 7 to 7: 3 . The trifunctional alkoxysilane and the bifunctional alkoxysilane method according to claim 4 Symbol mounting of silicone microparticles characterized by having a methyl group or a phenyl group bonded to Si atom.