JP2501059B2 - Method for producing fine particles of spherical silicone resin - Google Patents

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 resin fine particles, and more particularly to a method for efficiently producing spherical silicone resin fine particles having a particle diameter of 1 .mu.m or less with easy process control.

[0002]

2. Description of the Prior Art A method for producing fine particles of polymethylsilsesquioxane is known, which is carried out by hydrolyzing an alkoxysilane and then condensing it. Regarding this hydrolysis method, methyltrimethoxysilane or methyltriethoxysilane is used in an alkaline aqueous solution such as an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, ammonium hydroxide or an organic amine in an amount equal to or more than 6 times the equivalent of silane. Water (see Japanese Examined Patent Publication No. 40-14917), chlorine is used in 0.1
A method of hydrolyzing 5.0% of methyltrialkoxysilane in an aqueous solution containing an alkaline earth metal hydroxide or an alkali metal carbonate (Japanese Patent Publication No. 56-398).
No. 08), or a method of hydrolyzing in ammonia water (see Japanese Patent Publication No. 22767/1990).

However, a method using these series of methyltrialkoxysilanes as a starting material is a method using methyltrichlorosilane as a starting material (Belgian Patent No. 57241).
In general, it is widely practiced because the reaction control is easy as compared with (see No. 2 specification). In addition, here, it is pointed out that factors such as raw material silane, selection of catalyst, stirring conditions, hydrolysis concentration, hydrolysis temperature, etc. are particularly pointed out as factors influencing the formation of fine particles.As an example, methyltrimethoxysilane is gently stirred in ammonia water under stirring conditions. It is reported that fine particles having excellent spherical properties can be obtained by carrying out hydrolysis at the interface while maintaining the two-phase state below (JP-A-63-77).
940).

[0004]

As a method for obtaining the fine particles having a small particle size, methyltrimethoxysilane is hydrolyzed at the interface while maintaining a two-phase state in ammonia water under a mild stirring condition. A method of controlling trimethoxysilane to 1/10 or less of the weight of water is also known (see Japanese Patent Application Laid-Open No. 63-295637), but this method is difficult to control and dry powder is taken out. In this case, the concentration of the fine particles in the aqueous ammonia solution is low, which is a disadvantage that the efficiency is poor.As another method, the organotrialkoxysilane is hydrolyzed to an organosilanol in the presence of an organic acid, and then in an alkaline aqueous solution. Method of hydrolyzing with (Japanese Patent Laid-Open No. 1-21703
No. 9) is also known, but this has the drawback that it is difficult to obtain spherical particles because the organic acid salt remains in the fine powder and aggregation occurs during hydrolysis.

[0005]

The present invention relates to a method for producing spherical silicone resin fine particles which solves the above disadvantages and drawbacks. The method is as follows: A) 2 to 8 parts by weight of organotrialkoxysilane having a pH of 3.0. ~ 8.0 water 10
A step of adding and stirring 0 parts by weight to obtain a dispersion or a solution of organotrialkoxysilane, B) a step of adding an alkaline substance or an aqueous solution thereof, and hydrolyzing and condensing, and C) the organotrialkoxysilane. Is added, followed by hydrolysis and condensation.

That is, the present inventors have conducted various studies on a method for efficiently producing spherical silicone resin fine particles. As a result, organotrialkoxysilane was used as a starting material, and 2 to 8 parts by weight of this was used in 100 parts by weight of water. Add to and stir to make a dispersion or solution of organotrialkoxysilane, add an alkaline substance to this to hydrolyze and condense, and then add organotrialkoxysilane to it to hydrolyze and condense. It was found that the target spherical silicone resin fine particles can be efficiently obtained with a particle size of 1 μm or less, and the present invention was completed by conducting research on these various conditions. This will be described in more detail below.

[0007]

The present invention relates to a method for producing spherical silicone resin fine particles, which is prepared by using organotrialkoxysilane as a starting material, and adding an alkaline substance to this water dispersion or water dissolution product for hydrolysis condensation. This is to add organotrialkoxysilane to the system again and then carry out hydrolytic condensation, which makes it possible to efficiently produce the target product having a particle size of 1 μm or less with easy process control.

The method for producing spherical silicone resin fine particles according to the present invention uses organotrialkoxysilane as a starting material as described above. The organotrialkoxysilane used in step A) has the general formula R ¹ Si. (OR ² ) ₃ (1), R ¹ is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, or an amino group, an epoxy group, a vinyl group. A monovalent organic group having at least one of R ¹ and R ² is an alkyl group having 1 to 6 carbon atoms, which is the same as R ¹ .

The organotrialkoxysilane may be one kind or a mixture of two or more kinds, which includes methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane and methyltrioxysilane. Butoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, phenyltri Methoxysilane and the like are exemplified, but methyltrimethoxysilane is preferable from the viewpoint of hydrolyzability and cost.

When the amount of the organotrialkoxysilane used in step A) is less than 2 parts by weight with respect to 100 parts by weight of water, the silicone resin fine particles obtained have a particle size of 1 μm.
When the amount is not more than 8 parts by weight, the silicone resin fine particles obtained will not be less than 1 μm even when the amount is more than 8 parts by weight, and in this case, irregularly shaped particles are generated and further lumps are generated, which is preferable. Therefore, this should be in the range of 2 to 8 parts by weight, but the preferred range is 4
~ 6 parts by weight.

The water used in step A) has a pH of
When the pH is less than 3, the obtained spherical silicone resin fine particles aggregate with each other, and when the pH is higher than 8.0, the obtained spherical silicone resin fine particles do not become particles of 1 μm or less. It is required that the range is 0.0 to 8.0, but the preferable range is 4.0 to 8.0.
It is preferable to set it to 7.0. Therefore, in the step A), the organotrialkoxysilane of 3 to
It is necessary to add 8 parts by weight to 100 parts by weight of water having a pH of 3.0 to 8.0 and stir to make this organotrialkoxysilane an aqueous dispersion or a water dissolved product.

If the time required for this step A) is less than 0.1 hours, it is not possible to obtain silicone resin fine particles having a particle diameter of 1 μm or less because the organotrialkoxysilane is insufficiently dispersed or dissolved. When the time is longer than 8.0 hours, the organotrialkoxysilane is partially hydrolyzed depending on the conditions, and particles having a particle size of 1 μm or less cannot be obtained. However, the preferable range is 0.5
~ 2.0 hours.

Further, if the liquid temperature in this step A) is less than 0 ° C., the liquid will be solidified, and if it is higher than 60 ° C., the organotrialkoxysilane will be partially hydrolyzed and condensed and the silicone resin having a particle size of 1 μm or less. Since it is difficult to obtain fine particles, it is preferable to set the temperature in the range of 0 to 60 ° C, but this preferable temperature range is set to 0 to 20 ° C.

In the step B) of the present invention, an alkaline substance serving as a catalyst for the hydrolysis reaction of the organotrialkoxysilane is added to the aqueous dispersion or the water-dissolved product of the organotrialkoxysilane obtained in the above step A). , Which is hydrolyzed and condensed, the alkaline substance used here is potassium hydroxide, sodium hydroxide,
Alkali metal hydroxides such as lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide, alkali metal carbonates such as potassium carbonate and sodium carbonate, ammonia or monomethylamine, dimethylamine, monoethylamine And amines such as diethylamine and ethylenediamine.

Although the alkaline substance may be an aqueous solution thereof, among them, solubility in water, catalytic activity,
Ammonia is preferable because it can be easily removed from the powder by volatilization, and a commercially available aqueous ammonia solution (concentration: 28%) may be used. When this aqueous ammonia solution (concentration 28%) is used and the addition amount is less than 0.1 parts by weight relative to 100 parts by weight of water, the particles of the silicone resin obtained by this hydrolysis fuse with each other to cause gelation. However, if the amount is more than 5.0 parts by weight, the hydrolysis-condensation product cannot be obtained as spherical fine particles, so this is preferably in the range of 0.1 to 5.0 parts by weight. Is 1.
It is set to 0 to 3.0 parts by weight.

Further, if the liquid temperature at the time of carrying out the step B) is less than 0 ° C., the liquid will be solidified, and if the temperature is higher than 20 ° C., the desired spherical silicone resin fine particles having a particle diameter of 1 μm or less will be obtained. Therefore, the temperature range may be 0 to 20 ° C., but the preferable temperature range is 0 to 10 ° C. If the time for carrying out this step B) is longer than 2 hours, the resulting spherical silicone resin fine particles agglomerate with each other.
The time range may be set, but the preferable range is 5 to 2
It is set to 0 minutes.

In the step C) of the present invention, the organotrialkoxysilane is added to the liquid after the step B) and the organotrialkoxysilane is subsequently hydrolyzed and condensed, whereby the objective spherical silicone resin is obtained. Although fine particles are produced, the organotrialkoxysilane used here may be one or a mixture of two or more of the same ones as those used in the above step A).

The amount of the organotrialkoxysilane added in the step C) is 10% of water having a pH of 3.0 to 8.0.
If the amount is less than 5.0 parts by weight with respect to 0 parts by weight, the concentration of the obtained spherical silicone resin fine particles in water becomes low, resulting in poor efficiency. If the amount is more than 30 parts by weight, the obtained silicone resin fine particles aggregate. Therefore, it is preferable that the range is 5.0 to 30.0 parts by weight, and the preferable range is 15 to 25 parts by weight.

The liquid temperature in the step C) should be in the range of 0 to 40 ° C. because if the temperature is lower than 0 ° C., the liquid will solidify and if it is higher than 40 ° C., the spherical silicone resin fine particles obtained will agglomerate. However, the preferable range is 5 to 20 ° C. In addition, when the liquid is agitated strongly, agglomeration occurs between the spherical silicone resin fine particles and amorphous particles are also produced, so that this is preferably a gentle agitation. Therefore, this agitation device uses a propeller blade, It is preferable to make it like a flat blade.

In the addition and addition of the organotrialkoxysilane in the step C), if the stirring conditions are gentle, this mixing amount may be added at one time, and even in this case, the two-phase state is maintained while gradually adding water from the interface. Although decomposition can be performed, when the stirring is such that the two-phase state cannot be maintained, when the organotrialkoxysilane is charged for less than 1 hour, agglomeration of particles occurs, and for a time longer than 10 hours, the particle size is increased. Since fine particles of 1 μm or less cannot be obtained, it is advisable to gradually add it within 1 to 10 hours, preferably 1.5 to 7 hours.

In this case, the addition of the organotrialkoxysilane may be divided into different types, and particularly the organotrialkoxysilane to be added last may be obtained by selecting the type. The resin fine particles may have a functional group on the surface thereof.

After the step C), the system is preferably kept under stirring for a while until the hydrolysis condensation reaction is completed. However, the system may be heated to complete the hydrolysis condensation reaction. If necessary, an acidic substance may be added for neutralization.

If the steps A), B) and C) described above are carried out, the desired spherical silicone resin fine particles can be efficiently produced by simple process control. The spherical silicone resin fine particles thus obtained There is no particular limitation on the method of taking out, and this may be carried out by removing water by heating or heating under reduced pressure, but this is a method of leaving the dispersion still, stirring,
The method may be performed while flowing, a method of spraying and dispersing the dispersion liquid in an air stream such as spray drying, a method of using a flowing heat medium, and the like.

In carrying out the method of the present invention, a method of concentrating the dispersion by a method such as heat dehydration, filtration, centrifugation, decantation or the like may be combined as a pretreatment, and if necessary, it may be combined. Although it may be washed with water, when the fine particles taken out from the dispersion liquid are agglomerated, it is necessary to disintegrate it with a pulverizer such as a jet mill or a ball mill.

[0025]

EXAMPLES Next, examples and comparative examples of the present invention will be described. Example 1 Water 5,510 at pH = 6.8 in a 5 liter glass container
g, charge water temperature to 3 ° C, and rotate blade at 200 rpm
With stirring, 180 g of methyltrimethoxysilane was added thereto, and the mixture was stirred for 1 hour. Next, 90 g of an aqueous ammonia solution (concentration 28%) was added thereto, and the mixture was stirred for 10 minutes while maintaining the liquid temperature at 3 to 7 ° C. Then, 540 g of methyltrimethoxysilane was added to this while maintaining the liquid temperature at 5 to 10 ° C, and 2 It was charged for 5 hours.

After completion of the addition, stirring is continued for 1 hour while maintaining the liquid temperature at 5 to 10 ° C., then the mixture is heated to 75 to 80 ° C. and stirred for 1 hour, and the obtained slurry is filtered with a pressure filter. A cake with a water content of about 30%, 105 ° C
The dried product obtained by drying in a dryer of 1 was crushed with a jet mill, and the obtained fine particles were observed with an electron microscope.
This is shown in Fig. 1, which has a particle size of 0.5-
It was a spherical silicone resin fine powder of 0.9 μm.

Example 2 Water 5,510 at pH = 6.8 in a 5 liter glass container
g, charge water temperature to 3 ° C, and rotate blade at 200 rpm
With stirring, 180 g of methyltrimethoxysilane was added thereto, and the mixture was stirred for 1 hour. Next, 90 g of ammonia water (concentration 28%) was added to this, and the liquid temperature was adjusted to 3 ~.
After stirring for 10 minutes while maintaining at 7 ° C., 460 g of methyltrimethoxysilane was added thereto over 2.2 hours while maintaining the liquid temperature at 5 to 10 ° C., and subsequently 72 g of methyltrimethoxysilane and N-β (aminoethyl). ) A mixture of 8 g of γ-aminopropyltrimethoxysilane and a liquid temperature of 5-1
The mixture was charged for 0.4 hours while maintaining the temperature at 0 ° C.

Next, this product was treated in the same manner as in Example 1 to prepare spherical silicone resin fine particles, and this product was observed with an electron microscope. As a result, this product had a particle size of 0.5 to 0.
The particles were spherical silicone resin fine particles of 9 μm.

Example 3 In a 5 liter glass container, 3,510 water of pH = 6.8
After charging g, 1.3 g of acetic acid was added to adjust the pH of water to 4.0, the water temperature was set to 3 ° C., and the blade rotation speed was set to 200 rpm. It was stirred. Next, 90 g of an aqueous ammonia solution (concentration 28%) was added thereto, and the mixture was stirred for 10 minutes while maintaining the liquid temperature at 3 to 7 ° C. Then, 540 g of methyltrimethoxysilane was added to this while maintaining the liquid temperature at 5 to 10 ° C, and 2 ．
After being charged for 5 hours, the spherical silicon resin fine particles were treated in the same manner as in Example 1 to make spherical silicone resin fine particles, and observed with an electron microscope. As a result, it was found that the spherical silicone resin particles had a particle size of 0.4 to 0.8 μm. It was fine particles.

Comparative Example 1 3,510 g of water and 90 g of aqueous ammonia solution (concentration 28%) were charged into a 5 liter glass container, and the temperature of the water was set to 5 ° C. and the blade rotation speed was set to 200 rpm. Was 11.6. Then, add 720 g of methyltrimethoxysilane to the solution at a liquid temperature of 5
The mixture was charged for 3.0 hours while maintaining the temperature at -10 ° C., and then the same treatment as in Example 1 was performed to prepare silicone resin fine particles.
When this was observed with an electron microscope, it was a spherical fine powder having a particle size of 1.4 to 1.6 μm.

Comparative Example 2 3,510 g of water and 90 g of aqueous ammonia solution (concentration 28%) were charged in a 5 liter glass container and stirred at a water temperature of 5 ° C. and a blade rotation speed of 10 rpm. Had a pH of 11.6. Then, 720 g of methyltrimethoxysilane was gently added to this to maintain a two-layer state of an aqueous ammonia solution and methyltrimethoxysilane, and a hydrolysis-condensation reaction proceeded at the interface.
During this period, the liquid temperature was kept at 5 to 10 ° C., but since the layer of methyltrimethoxysilane disappeared after 4.0 hours, the same procedure as in Example 1 was carried out to prepare silicone resin fine particles. When observed under a microscope, the particles were spherical silicone resin fine particles having a particle size of 1.3 to 1.5 μm.

Comparative Example 3 In a 5 liter glass container, 3,510 water having a pH of 6.8 was used.
g, charged with 3.6 g of hydrochloric acid to adjust the pH of the water to 2.0, set the water temperature to 3 ° C., and set the blade rotation speed to 200 rpm, and then add 180 g of methyltrimethoxysilane to this for 1 hour. It was stirred. Next, 90 g of an aqueous ammonia solution (concentration 28%) was added thereto, and the mixture was stirred for 10 minutes while keeping the liquid temperature at 3 to 7 ° C., and then 540 g of methyltrimethoxysilane was kept at 5 to 10 ° C. at 2. 5
I put in it over time. After the addition is complete, further increase the liquid temperature by 5 to 1
After stirring for 1 hour while maintaining at 0 ° C, 75 to 8
When heated to 0 ° C. and stirred for 1 hour, the obtained slurry was found to have many agglomerates larger than 1 mm.

Comparative Example 4 3,510 glass of pH = 6.8 in a 5 liter glass container.
1.1 g of aqueous ammonia solution (concentration 28%)
Was added to adjust the pH of the water to 9.0, and the water temperature was set to 3 ° C.
After setting the blade rotation speed to 200 rpm, 180 g of methyltrimethoxysilane was added thereto and stirred for 1 hour. Next, add 90 g of aqueous ammonia solution (concentration 28%).
The mixture was charged and stirred for 10 minutes while maintaining the liquid temperature at 3 to 7 ° C., and then 540 g of methyltrimethoxysilane was added to the liquid temperature at 5
It was added over 2.5 hours while maintaining at -10 ° C. Next, this was treated in the same manner as in Example 1 to make spherical silicone resin fine particles, which were observed with an electron microscope. As a result, it was found that the spherical silicone resin fine particles had a particle size of 1.4 to 1.6 μm. there were.

[0034]

INDUSTRIAL APPLICABILITY The present invention relates to a method for producing spherical silicone resin fine particles, which is, as mentioned above, A).
2 to 8 parts by weight of organotrialkoxysilane was added to pH 3.
Pour into 100 parts by weight of water of 0 to 8.0 and stir to make a dispersion or solution of organotrialkoxysilane,
B) Then, an alkaline substance is added to this to be hydrolyzed and condensed, and C) Next, an organotrialkoxysilane is added to this, which is then hydrolyzed and condensed. Is easier and
This provides an advantage that the desired spherical silicone resin fine particles can be easily obtained with a particle diameter of 1 μm or less.

[Brief description of drawings]

FIG. 1 is an electron micrograph of spherical silicone resin fine particles obtained in Example 1 of the present invention.

Claims (1)

(57) [Claims] 1. A) Organotrialkoxysilanes 2 to 8
Adding 100 parts by weight of water having a pH of 3.0 to 8.0 to 100 parts by weight of the mixture to obtain a dispersion or solution of organotrialkoxysilane by stirring, B) and then adding an alkaline substance or an aqueous solution thereof,
A method for producing spherical silicone resin fine particles, which comprises a step of hydrolyzing and condensing, and C) a step of adding organotrialkoxysilane to the mixture and then performing hydrolytic condensation.