JP2004262981A - Preparation process for polyorganosiloxane particle and preparation process for silica particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for efficiently preparing a monodisperse particulate polyorganosiloxane which is especially suitable for a liquid crystal display spacer and has a relatively large particle diameter (about 1-30 μm) controllable to a desired value in a nm order. <P>SOLUTION: A silicon compound having a silicon-bonded non-hydrolyzable group or groups and a silicon-bonded hydrolyzable alkoxyl group or groups is dissolved in water, then hydrolyzed and condensed to give a seed particle liquid. To this liquid, an aqueous solution containing the silicon compound or its hydrolyzate is added to conduct a seed-particle growth reaction. During the reaction, the particle diameter is measured continuously or intermittently at a fixed time interval. Thus, the objective particulate polyorganosiloxane is prepared. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing polyorganosiloxane particles and a method for producing silica particles. More specifically, the present invention provides polyorganosiloxane particles satisfying a particle size range (about 1 to 30 μm) suitable for a spacer or a standard particle for a liquid crystal display device and having a monodispersed particle size distribution. A method for producing a product in a short time and in a high yield by a simple operation so as to obtain a product having a particle size of, and baking the polyorganosiloxane particles obtained by this method to obtain a spacer or a standard particle for a liquid crystal display device. The present invention relates to a method for producing silica particles suitable as the above.
[0002]
[Prior art]
Conventionally, monodispersed silica particles having a particle size distribution (hereinafter sometimes simply referred to as monodispersed silica particles) are known to be useful as various fillers, ceramic raw materials, and the like. Attention has been paid to its use as a spacer for a liquid crystal display device, and it has begun to be used.
[0003]
Conventionally, glass fiber chips or fine particles of a synthetic resin have been used for the spacer of the liquid crystal display device. However, glass fiber chips have excellent fiber diameter accuracy, but their lengths vary widely, and those that are too long may be visually observed and degrade image quality. There is a possibility that the formed alignment film, protective film, color filter, electric element, or the like may be damaged. Further, fine particles of synthetic resin have poor particle size accuracy, and thus may not be able to satisfy the performance required as a spacer for a liquid crystal display device. Therefore, when a higher gap accuracy is required, there is a possibility that the electric element such as an alignment film, a protective film, a color filter or an ITO conductive film formed on the substrate has a good particle size accuracy and is spherical. Is required.
[0004]
In order to satisfy these requirements, silica particles obtained by hydrolyzing and polycondensing silicon alkoxide have been proposed. The silica particles
(1) High purity, little influence on liquid crystal by eluted components
(2) Good particle size accuracy;
CV (%) = [standard deviation of fine particle diameter (μm)]
/ [Average particle size (μm)] × 100
CV value (coefficient of variation) obtained by
(3) Since almost perfect spheres can be formed, there is an advantage that there is no risk of damaging electric elements such as an alignment film, a protective film, a color filter and an ITO conductive film formed on the substrate. I have.
[0005]
Recently, non-hydrolyzable alkyl groups such as alkyltrialkoxysilanes (methyltrialkoxysilanes) have been used to impart a certain degree of softness to the particles to improve the adhesion of the particles in a liquid crystal cell. Polyorganosiloxane (polymethylsilsesquioxane) particles obtained by hydrolyzing and condensing a silicon alkoxide having a (methyl group) are also used as spacers in a liquid crystal display device.
As a method for producing such polymethylsilsesquioxane particles, a methyltrialkoxysilane or a partially hydrolyzed condensate thereof and an aqueous solution containing ammonia or an amine or a mixed solvent solution of water and an organic solvent are substantially mixed. A method of causing a reaction while maintaining a two-layer state without performing the method has been proposed (see Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Publication No. 4-70335
However, in this method, the particle size of the generated polymethylsilsesquioxane particles is controlled by the concentration of ammonia or amine in the lower layer at the time of preparation. Variations in the number of nuclei are likely to occur, and even if the reaction is performed under the same reaction conditions, the diameter of the finally obtained particles does not become the target particle diameter. For example, if production is performed 10 times under the same conditions in order to obtain particles having an average particle size of 5 μm, a variation of about 40% (about ± 2.0 μm) with respect to the target particle size occurs.
[0007]
On the other hand, there has been proposed a method for producing polyorganosiloxane particles having a monodisperse particle size distribution and having a desired particle size. (See Patent Document 2).
[0008]
[Patent Document 2]
JP-A-2000-80598
In this method, methyltrialkoxysilane is hydrolyzed and condensed to form seed particles comprising polyorganosiloxane particles, and then the seed particles are grown to produce polyorganosiloxane particles having a larger particle size. At that time, using a certain calculation formula, from the average particle size of the seed particles and the concentration of the particle growth solution, to derive the dilution ratio of the seed particle liquid determined according to the target final particle size, The present invention is characterized in that a seed particle liquid is diluted by such a dilution ratio and added to a liquid for particle growth to produce polyorganosiloxane particles having a desired particle diameter.
[0009]
However, in this method, it is necessary to calculate a dilution ratio for each production batch and perform a dilution operation. Although polyorganosiloxane particles having a particle size of about 4 to 10 μm and a particle size distribution of monodisperse can be obtained, the control of the particle size is performed on the order of μm, and when the particle size is to be uniformed to the order of nm, It was difficult to control the particle size. Further, it is generally difficult to produce polyorganosiloxane particles having a large particle size exceeding 10 μm, and there has been almost no report on a method for obtaining a polyorganosiloxane having a large particle size having a monodispersed particle size.
[0010]
[Problems to be solved by the invention]
Under such circumstances, a first object of the present invention is to satisfy a particle size range (about 1 to 30 μm) suitable as a spacer or a standard particle for a liquid crystal display device and to have a monodisperse particle size distribution. An object of the present invention is to provide a method for producing polyorganosiloxane particles in a short time and in a high yield by a simple operation so that particles having a desired particle size are obtained each time.
A second object of the present invention is to sinter the polyorganosiloxane particles to obtain high particle size accuracy [low CV value, low particle size blur (target particle size−obtained particle size)]. It is an object of the present invention to provide an industrially advantageous method for producing the silica particles of the above by a simple operation in a short time.
[0011]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, an aqueous solution of a silicon compound in which a non-hydrolyzable group and a hydrolyzable alkoxyl group are bonded to a silicon atom is hydrolyzed and condensed. After preparing the seed particle liquid, an aqueous solution containing the silicon compound or a hydrolyzate thereof is added to perform a seed particle growth reaction, and the particle diameter is measured continuously or at regular time intervals to obtain a first particle liquid. It has been found that the purpose can be achieved.
[0012]
In addition, the present inventor heat-treats the polyorganosiloxane particles and, when producing silica particles, preliminarily calcinates at a specific temperature, and then calcinates at a temperature equal to or higher than the decomposition temperature of the organic group of the polyorganosiloxane. As a result, it has been found that the reduction in the breaking strength of the particles and the cracking of the particles, which are observed during the heat treatment, are eliminated, and the second object can be achieved.
[0013]
The present invention has been completed based on such findings.
That is, the present invention
(1) General formula (I)
R¹nSi (OR²)_4-n                            … (I)
(Where R¹Is a non-hydrolyzable group, which is an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms having a (meth) acryloyloxy group or an epoxy group, an alkenyl group having 2 to 20 carbon atoms, An aryl group having 6 to 20 or an aralkyl group having 7 to 20 carbon atoms, R²Is an alkyl group having 1 to 6 carbon atoms, n is an integer of 1 to 3,¹When there are a plurality of¹May be the same or different, and OR²If there is more than one, each OR²They may be the same or different. )
Is hydrolyzed and condensed in the presence of a catalyst to form seed particles composed of polyorganosiloxane particles, and then the silicon compound represented by the general formula (I) or a hydrolyzate thereof is Adding an aqueous solution containing the seed particles, while continuously performing the growth reaction of the seed particles, measuring the particle diameter continuously or at regular intervals, and stopping the reaction when the target particle diameter is reached. A method for producing siloxane particles,
(2) The particle size measurement, which is carried out continuously or at regular time intervals, was performed by collecting a part of the reaction solution and contacting it with a protective colloid-forming agent to form a protective colloid on the particles in the reaction solution. Then, the method for producing polyorganosiloxane particles according to the above (1), which is performed by a Coulter method,
(3) The method for producing polyorganosiloxane particles according to (1) or (2) above, wherein the polyorganosiloxane particles are polymethylsilsesquioxane particles.
(4) When polyorganosiloxane particles having a particle size exceeding 10 μm are to be obtained, the rate of addition of the aqueous solution containing the silicon compound or its hydrolyzate is 0.01 ml per 1 ml of the solution to be added. / Min or less, the method for producing polyorganosiloxane particles according to any one of the above (1) to (3),
(5) The method according to any one of (1) to (4) above, wherein the finally obtained polyorganosiloxane particles have a particle size of 1 to 30 μm and a coefficient of variation of 3% or less. Method for producing polyorganosiloxane particles, and
(6) The polyorganosiloxane particles obtained by the method according to any one of (1) to (5) above, at a temperature of 100 ° C. lower than the decomposition temperature of the organic group contained therein, and After preliminarily calcined in a range below the decomposition temperature of the organic group, a method for producing silica particles, characterized by performing a baking treatment at a temperature equal to or higher than the decomposition temperature of the organic group,
Is to provide
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the method for producing the polyorganosiloxane particles of the present invention will be described.
In the method of the present invention, the raw material represented by the general formula (I)
R¹nSi (OR²)_4-n                                  … (I)
Is used.
[0015]
In the above general formula (I), R¹Is an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms having a (meth) acryloyloxy group or an epoxy group, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a carbon number. And represents 7 to 20 aralkyl groups. Here, the alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, and the alkyl group may be linear, branched or cyclic. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, cyclopentyl. Group, cyclohexyl group and the like. As the alkyl group having 1 to 20 carbon atoms having a (meth) acryloyloxy group or an epoxy group, an alkyl group having 1 to 10 carbon atoms having the above substituent is preferable, and this alkyl group is linear, branched, Any of a ring shape may be sufficient. Examples of the alkyl group having the substituent include a γ-acryloyloxypropyl group, a γ-methacryloyloxypropyl group, a γ-glycidoxypropyl group, a 3,4-epoxycyclohexyl group, and the like. The alkenyl group having 2 to 20 carbon atoms is preferably an alkenyl group having 2 to 10 carbon atoms, and the alkenyl group may be any of linear, branched and cyclic. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a hexenyl group, an octenyl group and the like. The aryl group having 6 to 20 carbon atoms is preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. The aralkyl group having 7 to 20 carbon atoms is preferably an aralkyl group having 7 to 10 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, a phenylpropyl group, and a naphthylmethyl group.
[0016]
On the other hand, R²Is an alkyl group having 1 to 6 carbon atoms, which may be linear, branched or cyclic, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group and an n- Butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl and the like.
n is an integer of 1 to 3;¹When there are a plurality of¹May be the same or different, and OR²If there is more than one, each OR²Each may be the same or different.
[0017]
Examples of the silicon compound represented by the general formula (I) include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and propyltrimethoxysilane. Ethoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyl Oxypropyltrimethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane and the like can be mentioned. Of these, methyltrimethoxysilane and vinyltrimethoxysilane are particularly preferred.
[0018]
In the present invention, as the raw material, one kind of the silicon compound represented by the general formula (I) may be used, or two or more kinds may be used in combination.
In the method of the present invention, the silicon compound is converted into an aqueous solution, and hydrolyzed and condensed in the presence of a catalyst to form a polyorganosiloxane particle liquid, which is used as a seed particle liquid. This is a method of growing and controlling the particle size to a target particle size using a hydrolyzed aqueous solution of a silicon compound, and specifically includes the following operation.
[0019]
(1) Preparation of liquid for forming seed particles
(2) Formation of seed particles
(3) Preparation of liquid for particle size growth and control
(4) Growth and control to target particle size
and
(5) Stopping the reaction
Hereinafter, each of the above operations will be described in detail.
[0020]
(1)Preparation of seed particle forming liquid
In the method of the present invention, the formation of the seed particles and the growth of the particle size are carried out in a homogeneous system, respectively. From the compounds represented, they can be appropriately selected and used irrespective of the specific gravity. When the formation of the seed particles and the growth of the particle size are each performed by the two-layer method, it is necessary to use a silicon compound having a specific gravity lower than that of the aqueous medium, so the type of the raw material is limited. However, in the present invention, since there is no such restriction on the specific gravity, the degree of freedom in selecting a raw material is large.
[0021]
The silicon compound is not particularly limited as long as it has miscibility with an aqueous medium, and the various silicon compounds described above are used. Among them, those easily soluble in an aqueous medium, for example, silicon having a methoxy group Compounds are preferred.
Further, as the aqueous medium, water or a mixture of water and a water-miscible organic solvent can be used. Here, the water used is preferably as small as possible in cations, and has a conductivity of^-4It is preferably at most S / cm.
[0022]
Examples of the water-miscible organic solvent include lower alcohols such as methanol, ethanol, propanol and butanol, and ketones such as acetone. These may be mixed alone with water, or may be mixed with water in combination of two or more.
The preparation of the seed particle forming liquid is performed by adding the silicon compound to the aqueous medium and stirring the mixture at a temperature of usually about 0 to 50 ° C. to form a uniform aqueous solution. At this time, the concentration of the silicon compound is preferably 20% by mass or less. If the concentration exceeds 20% by mass, the coefficient of variation of the particle size distribution increases, and if the concentration is too low, the volume efficiency and the like deteriorate, and this is industrially disadvantageous. A more preferred concentration is in the range of 5 to 15% by mass.
[0023]
(2)Seed particle formation
While stirring the liquid for forming seed particles prepared in the above (1), a basic catalyst, preferably an aqueous solution containing ammonia and / or amine, is added at once as a catalyst, and the silicon compound is hydrolyzed and condensed to form a seed. Particles are formed to form a seed particle liquid.
If the ammonia and / or amine-containing aqueous solution is added slowly, the system becomes uniform, a large amount of new core particles are generated, and the particle size becomes small. Therefore, it is preferable to add them all at once.
[0024]
The stirring speed at the time of adding the aqueous solution containing ammonia and / or amine can be appropriately selected depending on the size of the reaction tank and the shape and size of the blade. Here, as the amine, for example, monomethylamine, dimethylamine, monoethylamine, diethylamine, ethylenediamine and the like can be preferably mentioned. The ammonia and the amine may be used alone or in combination of two or more. However, ammonia is preferred because of its low toxicity, easy removal and low cost.
[0025]
Examples of the aqueous solution containing ammonia and / or amine include a solution in which ammonia and / or amine is dissolved in water or a mixed solvent of water and a water-miscible organic solvent. Here, it is sufficient that the water used has few cations, and the conductivity is 0.5 × 10^-4It is preferably at most S / cm. Examples of the water-miscible organic solvent include the same ones as exemplified in the description of the preparation of the seed particle forming liquid in the above (1).
It is advantageous to select the amount of the aqueous solution containing ammonia and / or amine so that the pH of the seed particle liquid after the formation of the seed particles is preferably in the range of 8.2 to 11.0.
[0026]
The reaction temperature depends on the type of the silicon compound as the raw material and the like, but is generally selected in the range of 0 to 50 ° C. If the temperature is lower than 0 ° C., the used aqueous medium freezes and does not exhibit its function, and if it is synthesized at 50 ° C. or more, the alkoxide used evaporates and the yield decreases. 5 ° C. to 30 ° C. for producing polyorganosiloxane particles having a relatively large particle diameter (particle diameter of more than 10 μm to about 30 μm), and 35 ° C. for producing polyorganosiloxane particles having a small particle diameter (1 μm to 10 μm). It is preferred to produce at -40C.
[0027]
Usually, the formation time of the seed particles is within 1 hour. When the seed particles are formed by the two-layer method, it takes about 4 to 10 hours. However, if a method based on a homogeneous system is employed as in the present invention, the seed particles can be formed in a much shorter time.
After the formation of the seed particles, the particle size of the obtained seed particles is measured. The method for measuring the particle size is not particularly limited, but can be measured by the Coulter method or a video micrometer using an optical microscope, and is preferably measured by the Coulter method in view of the simplicity and speed of the measurement operation.
[0028]
Here, the Coulter method refers to a measuring method using an apparatus for electrically measuring the size of particles dispersed in a solution. In this device, a tube having pores (aperture tube) is installed in an electrolyte solution in which measurement particles are suspended and dispersed. Electrodes are placed inside and outside the aperture tube, and the electrolyte solution It is configured such that current flows between both electrodes. When the measurement particles dispersed in the electrolytic solution are sucked and passed through the micropores of the aperture tube, the electrolytic solution corresponding to the particle volume is replaced and a change occurs in the electric resistance between the two electrodes. Then, the particle size is measured by amplifying and detecting this.
[0029]
When measuring the particle diameter, various protective colloid-forming agents used for suspending the particles can be used, but it is preferable to use an aqueous polyvinyl alcohol solution.
The present invention relates to a method of forming seed particles having a smaller particle size than a target final particle size, and then growing the seed particles to a target particle size using a liquid for particle size growth / control. On the other hand, when the particle size of the obtained seed particles is too small compared to the target final particle size, the seed particles are appropriately adjusted to a suitable particle size (for example, the method described in JP-A-2002-80598). After having grown to a size smaller than the target final particle size), it can be subjected to a particle size growth / control step using the following liquid for particle size growth / control.
[0030]
(3)Preparation of liquid for particle size growth and control
An aqueous solution containing the silicon compound represented by the general formula (I) or a hydrolyzate thereof is used as the liquid for particle size growth / control.
[0031]
Examples of the silicon compound represented by the general formula (I) include the various silicon compounds described above. Further, the hydrolyzate of the silicon compound represented by the general formula (I) refers to a partially or completely hydrolyzed silicon compound having 1 to 3 alkoxyl groups represented by the general formula (I). Things.
[0032]
The aqueous solution containing the silicon compound or the hydrolyzate thereof may be prepared by using the water or the mixture of water and the water-miscible organic solvent used in the preparation of the seed particle forming liquid of the above (1) or the seed particles of the above (2). Using the aqueous solution containing ammonia and / or amine used in the formation of
In the preparation of the liquid for particle size growth / control, the type of the silicon compound, its concentration and the type of the aqueous medium may be the same as those of the seed particle forming liquid, or may be different. Although the same is preferable, the same one is preferable from the viewpoint of workability and properties of the obtained particles.
The aqueous solution containing the silicon compound represented by the general formula (I) or its hydrolyzate used as the particle size growth / control solution is subjected to the following reaction in a homogeneous solution state.
[0033]
(4)Particle size growth and control
The liquid for particle size growth / control obtained in (3) is added to the seed particle liquid obtained in (2) while stirring, and the particle size is grown to the target particle size.
The reaction temperature at this time depends on the type of the silicon compound as the raw material and the like, but is generally selected in the range of 0 to 50 ° C.
The rate of addition of the particle size growth / control liquid is not particularly limited, but is preferably 0.02 ml / min or less, more preferably 0.01 ml / min, per 1 ml of the added solution containing the seed particles. It is as follows. In the case of obtaining polyorganosiloxane particles having a large particle size (more than 10 μm), if the addition rate exceeds 0.01 ml / min with respect to 1 ml of the volume of the solution to be added, the fine particles are contained in the whole particle group. Is generated, and particles having a portion having a different refractive index may be observed inside each particle. Therefore, it is preferably 0.01 ml / min or less per 1 ml of the volume of the solution to be added. Note that the particles having the portions having different refractive indices are considered to have air bubbles, and are hereinafter referred to as air bubble particles.
[0034]
In this step, the particle size is measured continuously or at regular intervals until the desired final particle size is reached. Here, the method for measuring the particle size is not particularly limited, and can be measured by a Coulter method or a method using an optical microscope video micrometer, but is preferably measured by the Coulter method. The measurement of the particle size by the Coulter method is as described in detail in the above (2) Formation of seed particles.
[0035]
The average particle size and CV value in the present invention were calculated by the following methods.
First, from the measurement result of the Coulter method, an isolated particle size distribution peak width is preliminarily selected as a measurement range, and a preliminary average particle size value and σ (standard deviation) are calculated. Then, a range of ± 3σ was selected from the preliminary average particle size value, and the average particle size and the CV value were calculated again within the range.
When there were a plurality of isolated particle size distribution peaks, calculation was performed for each of the peaks.
[0036]
(5)Stopping the reaction
After the addition of the liquid for particle size growth / control in (4) above, the particle size is measured continuously or at regular intervals, and when it is confirmed that the target particle size has been reached, the particle size growth / control is performed. The addition of the working solution is stopped, and aging is performed by adding an aqueous solution containing ammonia and / or amine. This aging is usually performed at a temperature in the range of 0 to 50 ° C. for about 6 to 24 hours, depending on the type of the silicon compound as the raw material.
[0037]
When the grain size is grown by employing the two-layer method, it generally takes about 6 to 10 hours. In the present invention, the growth and control of the grain size is generally sufficient within 3 hours, and is much shorter. Can grow the particle size. In the case of the two-layer method, the silicon compound in the upper layer undergoes self-condensation due to moisture in the air and deteriorates. Although the amount may decrease and particles having a desired particle size may not be obtained, such a problem does not occur in the method of the present invention because the particle size is grown in a uniform system.
In addition, in the present invention, it is not necessary to calculate the dilution rate of the seed particle forming liquid or to perform the dilution operation when adding the particle diameter growth / control liquid, and it is possible to produce polyorganosiloxane particles by a simple operation. Furthermore, the particle size of the resulting polyorganosiloxane particles can be controlled on the order of nm.
[0038]
In the present invention, after the reaction of the above (5) is stopped, the generated particles are sufficiently washed in accordance with a conventional method, and then, if necessary, a classification treatment is carried out to remove the maximum or minimum particles, followed by a drying treatment. The classification method is not particularly limited, but a wet classification method in which classification is performed by utilizing the fact that the sedimentation speed varies depending on the particle size is preferable. The drying treatment is usually performed at a temperature in the range of 100 to 200C. In the present invention, in the drying treatment, aggregation of particles does not substantially occur.
In this way, polyorganosiloxane particles having the desired final particle size can be obtained in high yield.
[0039]
The polyorganosiloxane particles obtained by the method of the present invention have an average particle size of 1 to 30 μm, preferably 3 to 25 μm, more preferably 3 to 20 μm, and a coefficient of variation (CV) of the particle size distribution. Value) is 3% or less, preferably 2.5% or less, and is a truly spherical monodisperse particle.
[0040]
Next, a method for producing the silica particles of the present invention will be described.
In this method, polyorganosiloxane particles are calcined to decompose organic groups contained therein to produce silica particles, and the polyorganosiloxane particles are used as the polyorganosiloxane particles obtained by the above-described production method. Organosiloxane particles are used.
[0041]
In this method, the polyorganosiloxane particles obtained by the above method are preliminarily treated at a temperature of 100 ° C. lower than the decomposition temperature of the organic group contained therein and at a temperature lower than the decomposition temperature of the organic group. After the baking treatment, the baking treatment is performed at a temperature equal to or higher than the decomposition temperature of the organic group to produce silica particles.
[0042]
When the temperature is immediately raised to a temperature equal to or higher than the decomposition temperature of the organic groups contained in the polyorganosiloxane particles and baked, decomposition and desorption of the organic groups occur rapidly, and the breaking strength of the particles decreases, and in some cases, It may not be able to withstand sudden shrinkage and may cause undesirable situations such as cracking of particles. However, as in the present invention, after performing the pre-baking treatment at a temperature of 100 ° C. or lower than the decomposition temperature of the organic group and a temperature lower than the decomposition temperature of the organic group, the temperature is higher than the decomposition temperature of the organic group. By carrying out the sintering treatment at the temperature described above, the above-mentioned undesirable situation can be avoided. The selection of the calcination time depends on the type of the organic group constituting the polyorganosiloxane particles. When the organic group has an easily heat-decomposable organic group, it is desirable to perform the treatment at a relatively low temperature, and conversely, the heat decomposition is difficult When it has an organic group, it is preferable to perform the treatment at a high temperature. In any case, optimal conditions may be selected according to the required breaking strength and elastic modulus. Specifically, in the case of polymethylsilsesquioxane (PMSO) particles, after pre-baking by holding at a temperature in a range of 250 to 350 ° C. for about 3 to 50 hours, a temperature in a range of 500 to 1300 ° C. A baking treatment is performed at a temperature for about 3 to 50 hours to completely decompose the organic groups.
[0043]
The atmosphere in the baking treatment preferably has an oxygen concentration of not less than a certain value, for example, not less than 10% by volume, in order to oxidize and decompose organic groups into silica. The firing device is not particularly limited, and a known firing device such as an electric furnace or a rotary kiln can be used.
[0044]
【Example】
Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
[0045]
Example 1
(1) Preparation of liquid for forming seed particles
In a 5000 ml separable flask equipped with a stirrer, 2500 g of ion-exchanged water and 250 g of methyltrimethoxysilane (hereinafter abbreviated as MTMS) were added, and the mixture was stirred at 100 rpm in a thermostat adjusted to 30 ° C. did. Initially, MTMS was dispersed in the form of oil droplets in the aqueous solution, but after about 3 hours, the MTMS was completely dissolved to form a homogeneous solution, which was used as a seed particle forming liquid.
[0046]
(2) Formation of seed particles
The stirring speed was reduced to 30 rpm, and 25 mL of 1 mol / L aqueous ammonia was added at a time to the seed particle forming liquid prepared in the above (1). One minute after adding the aqueous ammonia, polymethylsilsesquioxane particles were generated, and the solution became cloudy.
After 30 minutes and 40 minutes from the addition, 0.2 ml of each seed particle liquid was collected, and 2 ml of a 0.1% by mass aqueous solution of polyvinyl alcohol was added thereto, and immediately using Coulter Counter Multisizer II (manufactured by Coulter). The particle size of 50,000 particles was measured by the Coulter method. As a result, the average particle diameter of both seed particle liquids was 2.85 μm (CV value: 2.24%), and it was confirmed that the particle growth was completed. It was 15 μm smaller.
[0047]
(3) Preparation of liquid for particle size growth and control
In a 5000 ml separable flask equipped with a stirrer, 2500 g of ion-exchanged water and 250 g of MTMS were added, and the mixture was stirred at 100 rpm in a thermostat adjusted to 30 ° C. Initially, MTMS was dispersed in the form of oil droplets in the aqueous solution, but after about 3 hours, the MTMS was completely dissolved to form a uniform solution, which was used as a liquid for particle size growth and control.
[0048]
(4) Growth and control of particle size
To the polymethylsilsesquioxane seed particle liquid of the above (2) that did not reach the target final particle diameter, the liquid for particle diameter growth / control of the above (3) was added at 10 ml / min (for 1 ml of the volume of the solution to be added) At a rate of 0.0036 ml / min) using a metering pump, and mixing was started.
Until the particle size increased by 0.15 μm, the particle size growth was observed every 5 minutes by the Coulter method under the same conditions as in (2). It was found that the desired polymethylsilsesquioxane particles of 3.00 μm (CV value: 2.07%) were obtained when 900 ml of the particle size growth liquid was added from the start of the dropping.
[0049]
(5) Stopping the reaction
Immediately, the addition of the liquid for particle size growth / control was stopped, and a mixed solution of 15 g of 25% by mass aqueous ammonia and 35 g of ion-exchanged water was dropped by a quantitative pump, and ripening was performed at room temperature for 16 hours.
[0050]
(6) Fine classification and drying
The solution containing the polymethylsilsesquioxane particles obtained in (5) is subjected to centrifugal separation to separate the particles, followed by irradiating ultrasonic waves in methanol and then performing decantation plural times. And the fine particles were removed. After the remaining polymethylsilsesquioxane particles were air-dried, they were heated to 150 ° C. and dried to remove residual methanol.
The polymethylsilsesquioxane particles thus obtained were subjected to particle size measurement by the Coulter method in the same manner as in (2), and as a result, the average particle size was 3.00 μm (CV value: 2.01%). .
[0051]
Comparative Example 1
The same operations as those described in (1) Preparation of seed particle forming liquid and (2) Formation of seed particles in Example 1 were performed.
As a result, polyorganosiloxane particles having an average particle size of 2.85 μm (CV value: 2.24%) were obtained, but 0.15 μm smaller than the target final particle size of 3.00 μm.
From the comparison between Example 1 and Comparative Example 1, it can be seen that, in the present invention, polyorganosiloxane particles having a monodispersed particle size distribution can be produced by adjusting the particle size in the order of nm.
[0052]
Example 2
(1) Preparation of liquid for forming seed particles
In a 10000 ml separable flask equipped with a stirrer, 5000 g of ion-exchanged water and 500 g of MTMS were added, and the mixture was stirred at 100 rpm in a thermostat adjusted to 30 ° C. Initially, MTMS was dispersed in the form of oil droplets in the aqueous solution, but after about 3 hours, the MTMS was completely dissolved to form a homogeneous solution, which was used as a seed particle forming liquid.
[0053]
(2) Formation of seed particles
The temperature of the thermostat was lowered to 10 ° C., the stirring speed was lowered to 30 rpm, and 5.0 ml of 1 mol / l ammonia water was added at a time to the seed particle forming liquid prepared in the above (1). Fifteen minutes after the addition of the aqueous ammonia, polymethylsilsesquioxane particles were generated, and the solution became cloudy.
At 60 minutes and 70 minutes after the addition, 0.2 ml of each of the seed particle liquids was collected, and 2 ml of a 0.1% by mass aqueous solution of polyvinyl alcohol was added thereto, and immediately followed by the Coulter method in the same manner as in (2) of Example 1. Thus, the particle diameter of 50,000 particles was measured. As a result, the average particle diameter of both seed particle liquids was 8.20 μm (CV value: 2.05%), and it was confirmed that the particle growth was completed. It was 80 μm smaller.
[0054]
(3) Preparation of liquid for particle size growth and control
In a 10000 ml separable flask equipped with a stirrer, 5000 g of ion-exchanged water and 500 g of MTMS were added, and the mixture was stirred at 100 rpm in a thermostat adjusted to 30 ° C. At the beginning of the addition of MTMS, it was dispersed in the form of oil droplets in the aqueous solution, but after about 3 hours, the MTMS was completely dissolved to form a uniform solution. Thereafter, the temperature of the thermostat was adjusted to 10 ° C., and the solution was stirred until the temperature of the MTMS-dissolved solution reached 10 ° C. to obtain a liquid for particle size growth and control.
[0055]
(4) Growth and control of particle size
The half of the polymethylsilsesquioxane seed particle liquid of the above (2), which did not reach the target final particle size, was carefully transferred to a 10000 ml separable flask equipped with a stirrer, and then the temperature was adjusted to 10 ° C. The mixture was stirred at 30 rpm in the thermostat. The liquid for particle size growth / control of the above (3) was dropped and mixed at a rate of 25 ml / min (0.009 ml / min per 1 ml of the solution to be added) using a metering pump.
Until the particle size was increased by 2.80 μm, the particle size growth was observed every 5 minutes by the Coulter method under the same conditions as (2). It was found that the desired polymethylsilsesquioxane particles of 11.00 μm (CV value 1.99%) were obtained at the stage of adding 4800 ml of the particle size growth liquid from the start of the dropping.
[0056]
(5) Stopping the reaction
Immediately, the addition of the liquid for particle size growth / control was stopped, and a mixed solution of 15 g of 25% by mass aqueous ammonia and 35 g of ion-exchanged water was dropped by a quantitative pump, and ripening was performed at room temperature for 16 hours.
[0057]
(6) Fine classification and drying
The solution containing the polymethylsilsesquioxane particles obtained in (5) is subjected to centrifugal separation to separate the particles, followed by irradiating ultrasonic waves in methanol and then performing decantation plural times. And the fine particles were removed. After the remaining polymethylsilsesquioxane particles were air-dried, they were heated to 150 ° C. and dried to remove residual methanol.
The polymethylsilsesquioxane particles thus obtained were measured for particle size by the Coulter method in the same manner as in (2), and as a result, the average particle size was 11.00 μm (CV value: 1.81%). .
[0058]
Comparative Example 2
The same operation as the operation described in (1) Preparation of seed particle forming liquid and (2) Formation of seed particles in Example 2 was performed.
As a result, polyorganosiloxane particles having an average particle size of 8.20 μm (CV value: 2.05%) were obtained, but 2.80 μm smaller than the target final particle size of 11.00 μm.
From Example 2, it can be seen that, in the present invention, polyorganosiloxane particles having a large particle diameter exceeding 10 μm can be produced. It can be seen that monodispersed polyorganosiloxane particles can be produced by adjusting the particle size in the order of nm.
[0059]
Example 3
(1) Preparation of seed particle forming liquid, (2) Formation of seed particles, (3) Preparation of particle size growth / control liquid, and (4) Growth and control of particle size
Half of the polymethylsilsesquioxane seed particle liquid obtained in (2) of Example 2 above, which did not reach the target final particle diameter, was carefully transferred to a 10000 ml separable flask equipped with a stirrer. Thereafter, the mixture was stirred at 30 rpm in a thermostat adjusted to 10 ° C. With respect to this solution, the particle size growth / control solution prepared in (3) of Example 2 was quantified at a rate of 50 ml / min (0.018 ml / min per 1 ml of the volume of the solution to be added). Dropping and mixing were started using a pump.
Until the particle size increased by 2.80 μm, the particle size growth was observed every 5 minutes by the Coulter method under the same conditions as in (2) of Example 2. It was found that the desired polymethylsilsesquioxane particles of 11.00 μm (CV value 1.88%) were obtained at the stage of adding 4800 ml of the particle size growth liquid from the start of the dropping.
[0060]
(5) Stopping the reaction
Immediately, the addition of the liquid for particle size growth / control was stopped, and a mixed solution of 15 g of 25% by mass aqueous ammonia and 35 g of ion-exchanged water was dropped by a quantitative pump, and ripening was performed at room temperature for 16 hours. When the obtained particles were observed with an optical microscope, generation of bubble particles was confirmed.
From Example 3, it can be seen that in the present invention, polyorganosiloxane particles having a large particle diameter exceeding 10 μm can be produced, and the particle diameter distribution is determined by comparing Example 3 with Comparative Example 2. It can be seen that monodispersed polyorganosiloxane particles can be produced by adjusting the particle size in the order of nm.
Further, according to the comparison between Example 2 and Example 3, when producing polyorganosiloxane particles having a large particle diameter, the rate of addition of the particle diameter growth / control solution is set to 0 with respect to 1 ml of the volume of the solution to be added. It can be seen that bubble particles are generated when the rate exceeds 0.01 ml / min.
[0061]
Example 4
After drying the polymethylsilsesquioxane particles having an average particle diameter of 3.00 μm obtained in Example 1, the temperature was raised from room temperature to 340 ° C. under the condition of an air flow rate of 1 liter / min. After preheating for 12 hours, the temperature was raised to 540 ° C., and the temperature was maintained for 12 hours for main firing to obtain silica particles. After the main firing, the temperature was cooled to room temperature, and the fired particles were taken out. Observation of the fired particles by the Coulter method revealed that the average particle size was 2.50 μm and the CV value was 2.10%.
[0062]
【The invention's effect】
According to the method of the present invention, polyorganosiloxane particles satisfying a relatively large particle size range (approximately 1 to 30 μm) and having a monodispersed particle size distribution can be obtained each time with a desired particle size. In addition, it can be produced in a short time with a high yield by a simple operation that does not require a dilution operation of the seed particle growth liquid or the like. The polyorganosiloxane particles obtained by this method are suitable as spacers for liquid crystal display devices and standard particles.
Further, according to the method of the present invention, the polyorganosiloxane particles obtained by the above method, by baking under specific conditions, has a particle size suitable as a liquid crystal display device spacer or standard particles, Moreover, silica particles having a highly monodispersed particle size distribution can be produced in a short time by a simple operation.

Claims (6)

General formula (I)
R ¹ nSi (OR ² ) _4-n (I)
(Wherein, R ¹ is a non-hydrolyzable group, and is an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms having a (meth) acryloyloxy group or an epoxy group, and 2 to 20 carbon atoms. An alkenyl group, an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, R ² is an alkyl group having 1 to 6 carbon atoms, n is an integer of 1 to 3, and when there are a plurality of R ¹ each R ¹ may be different from one another identical, if OR ² there are a plurality, each OR ² may be different even identical to each other.)
Is hydrolyzed and condensed in the presence of a catalyst to form seed particles composed of polyorganosiloxane particles, and then the silicon compound represented by the general formula (I) or a hydrolyzate thereof is Adding an aqueous solution containing the seed particles, while continuously performing the growth reaction of the seed particles, measuring the particle diameter continuously or at regular intervals, and stopping the reaction when the target particle diameter is reached. A method for producing siloxane particles. The measurement of the particle size, which is performed continuously or at regular intervals, is performed by collecting a part of the reaction solution, contacting the protective solution with a protective colloid-forming agent to form the protective colloid on the particles in the reaction solution, The method for producing polyorganosiloxane particles according to claim 1, wherein the method is carried out by a method. 3. The method for producing polyorganosiloxane particles according to claim 1, wherein the polyorganosiloxane particles are polymethylsilsesquioxane particles. When polyorganosiloxane particles having a particle size of more than 10 μm are to be obtained, the rate of addition of the aqueous solution containing the silicon compound or its hydrolyzate is 0.01 ml / min or less per 1 ml volume of the solution to be added. The method for producing polyorganosiloxane particles according to any one of claims 1 to 3, wherein 5. The method for producing polyorganosiloxane particles according to claim 1, wherein the particle size of the finally obtained polyorganosiloxane particles is 1 to 30 μm, and the coefficient of variation is 3% or less. Method. The polyorganosiloxane particles obtained by the method according to any one of claims 1 to 5, which are at least 100 ° C lower than the decomposition temperature of the organic group contained therein and lower than the decomposition temperature of the organic group. And baking at a temperature equal to or higher than the decomposition temperature of the organic group.