JP2023109579A - Inorganic particles, and low dielectric material and low refractive index material including the inorganic particles, and method for producing inorganic particles - Google Patents

Abstract

To provide inorganic particles that have excellent strength despite having high porosity and can prevent penetration of liquid materials into the interior of the particles.SOLUTION: Provided are inorganic particles having an average particle outer diameter of 0.1 to 70 μm and a specific surface area of 50 m2/g or less, and including two or more spaces inside. The inorganic particles herein can be produced by a method for producing inorganic particles having two or more spaces inside, the method including a seed particle liquid preparation step in which an inorganic compound is hydrolyzed and condensed in a solution to prepare a seed particle liquid, a particle size growth step in which an inorganic compound containing solution is added to the seed particle liquid and the mixture is stirred to grow the particle size, a measurement step in which the particle size is measured continuously or at predetermined intervals during the particle size growth step, and a reaction stop step in which the reaction is stopped during the particle size growth step.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to inorganic particles, a low dielectric material and a low refractive index material using the inorganic particles, and a method for producing the inorganic particles.

Inorganic particles having internal spaces are used in a wide range of fields such as fillers, spacers, ceramic raw materials, resin modifiers, adsorbents, electronic materials, semiconductor materials, paints and cosmetics. In recent years, various techniques are being developed for the purpose of improving the performance of inorganic particles and imparting properties according to various uses.

For example, Patent Document 1 discloses colloidal particles made of silica as a dispersoid and an inorganic oxide other than silica, and the surfaces of the colloidal particles are thinly coated with a film such as silica or a synthetic resin. The colloidal particles prior to coating are disclosed as colloidal particles that are porous microparticles.

Patent Document 2 discloses a coating step of obtaining coated polymer particles by forming a polyorganosiloxane film on polymer particles containing a polyorganosiloxane polymer, and a baking step of baking the coated polymer particles. , to produce inorganic particles in which the inorganic particles are present in the hollow portion.

JP-A-7-133105 JP 2011-132087 A JP-A-2002-80598

As described above, various techniques are being developed for the purpose of improving the performance of inorganic particles and imparting properties according to various uses. For this purpose, a method of kneading hollow inorganic particles into a material such as resin or ceramics to create an air layer inside the material is used. At this time, in order to uniformly disperse the inorganic particles in the other material, a force such as stirring is applied when kneading the material and the inorganic particles, but the force breaks the inorganic particles and creates an air layer in the material. I have a problem with not being able to do it.

On the other hand, in order to improve the strength of hollow inorganic particles, the thicker the outer shell, the lower the porosity, and there is a problem that the original effect of creating an air layer inside the material cannot be exhibited. .

Further, as in Patent Document 1, for the purpose of lowering the refractive index, a technique has been proposed in which the pore entrances of the particles are closed by coating the surface of the porous particles. It is difficult to densify the layer, resulting in a surface with pores, and there is a problem that the liquid material penetrates into the inside of the particles.

Therefore, the main object of the present technology is to provide inorganic particles that are excellent in strength despite having a high porosity and that are capable of preventing permeation of liquid substances into the interior of the particles.

The present applicant previously discovered a new technology for producing polyorganosiloxane particles and filed a patent application of Patent Document 3. The polyorganosiloxane particles produced by this production technique are particles that do not have internal spaces, but by devising this production technique, it is possible to solve the above problems by creating two or more internal spaces. The present inventors have succeeded in producing inorganic particles having such properties, and have completed the present invention.

That is, in the present technology, first, the average particle outer diameter is 0.1 to 70 μm,
a specific surface area of 50 m ² /g or less,
An inorganic particle having two or more spaces inside is provided.
The inorganic particles according to the present technology can be made from a silicon compound represented by the following general formula (1).
[Chemical 1]

(In the formula, R ¹ is a non-hydrolyzable group, an alkyl group having 1 to 20 carbon atoms, a (meth)acryloyloxy group or an epoxy group-containing alkyl group having 1 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 multiple R ¹ , each R ¹ may be the same or different, and when there are multiple OR ² , each OR ² may be the same or different.)
The ratio of the total volume of the spaces to the volume of the inorganic particles according to the present technology can be 5 to 50%.
The inorganic particles according to the present technology can be surface-treated with a silane coupling agent.

Inorganic particles according to the present technology can be used for low dielectric materials and low refractive index materials.

In the present technology, next, a seed particle liquid preparation step of hydrolyzing and condensing an inorganic compound in a solution to prepare a seed particle liquid;
a particle size growth step of adding an inorganic compound-containing solution to the seed particle liquid and stirring to grow the particle size;
a measuring step of measuring the particle size continuously or at predetermined intervals during the particle size growing step;
a reaction stopping step of stopping the reaction during particle size growth;
and providing a method for producing inorganic particles having two or more spaces inside.

According to the present invention, it is possible to provide inorganic particles that are excellent in strength despite having a high porosity and that can prevent permeation of liquid substances into the interior of the particles.
Note that the effects described here are not necessarily limited, and may be any of the effects described in this specification.

1 is a cross-sectional image diagram showing an example of a cross-sectional structure of an inorganic particle 1 according to the present technology; FIG. 1 is a flowchart of a method for manufacturing inorganic particles 1 according to the present technology; FIG. 10 is an optical micrograph of inorganic particles according to Example 9. FIG.

Preferred embodiments for carrying out the present invention will be described in detail below with reference to the drawings.
It should be noted that the embodiments described below are examples of representative embodiments of the present invention, and the scope of the present invention should not be construed narrowly.

<1. Inorganic particles 1>
FIG. 1 is a cross-sectional image diagram showing an example of the cross-sectional structure of inorganic particles 1 according to the present technology. The inorganic particles 1 according to the present invention are characterized by having an average particle outer diameter of 0.1 to 70 μm, a specific surface area of 50 m ² /g or less, and two or more spaces 11 inside.

The average particle outer diameter of the inorganic particles 1 according to the present technology is 0.1 to 70 μm. By setting the particle outer diameter of the inorganic particles 1 according to the present technology to 0.1 μm or more, the proportion of particles dispersed in the state of primary particles without aggregating increases. In addition, by setting the particle outer diameter of the inorganic particles 1 according to the present technology to 70 μm or less, it is possible to increase the filling rate of the particles when mixing with other materials such as resins, resulting in a low dielectric constant and a low refractive index. It is possible to sufficiently exhibit the intended effect such as the rate.

The particle outer diameter of the inorganic particles 1 according to the present technology can be appropriately designed according to the purpose, as long as the average particle outer diameter is within the range of 0.1 to 70 μm. Particularly in the present technology, the average particle outer diameter of the inorganic particles 1 is preferably 0.1 to 30 μm, more preferably 0.5 to 10 μm.

The inorganic particles 1 according to the present technology have a specific surface area of 50 m ² /g or less and have a structure without pores on the surface. Therefore, it is possible to prevent penetration of the liquid substance into the inside of the particles. The specific surface area of the inorganic particles 1 according to the present technology is not particularly limited as long as it is 50 m ² /g or less, preferably 45 m ² /g or less, and more preferably 40 m ² /g or less.

The inorganic particles 1 according to the present technology have two or more spaces 11 inside. By providing two or more spaces 11, a sufficient air layer can be created in the material to be kneaded, and as a result, the desired effects such as low dielectric constant and low refractive index can be sufficiently exhibited. In addition, by having two or more spaces instead of one space, the inside of the inorganic particle 1 has a pillar structure, so that the strength can be improved compared to inorganic particles having the same space ratio and one space. can.

The number of spaces 11 provided in the inorganic particles 1 according to the present technology can be freely set according to the size, form, and the like of the spaces 11 as long as the number is two or more. Particularly in the present technology, the number of spaces 11 provided in the inorganic particles 1 according to the present technology is preferably 3 or more, more preferably 5 or more.

The ratio of the total volume of the space 11 to the volume of the inorganic particles 1 according to the present technology can be freely set as long as the effect of the present technology is not impaired. % is more preferred, and 20 to 50% is even more preferred. By setting the ratio of the total volume of the space 11 to the volume of the inorganic particles 1 according to the present technology to be 5% or more, it is possible to create a sufficient air layer in the material to be kneaded, resulting in a low dielectric constant and a low refractive index. It is possible to sufficiently exhibit the intended effect such as. By setting the ratio of the total volume of the spaces 11 to the volume of the inorganic particles 1 according to the present technology to 50% or less, the strength of the particles can be improved.

The CV value (coefficient of variation of particle size distribution) of the inorganic particles 1 according to the present technology is not particularly limited as long as the effect of the present technology is not impaired. Particularly in the present technology, the CV value of the inorganic particles 1 is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less.

When the CV value of the inorganic particles 1 according to the present technology is 20% or less, the ratio of particles larger than the average particle outer diameter decreases, and the material is suitable for applications in which inclusion of coarse particles is disliked.

Note that, in the present technology, the CV value is a value calculated by the following formula.
CV value (%) = {[standard deviation of particle outer diameter (μm)]/[average particle outer diameter (μm)]}×100

The sphericity of the inorganic particles 1 according to the present technology is not particularly limited as long as the effects of the present technology are not impaired. Particularly in the present technology, the sphericity of the inorganic particles 1 is preferably 0.8 or more, more preferably 0.9 or more.

When the sphericity of the inorganic particles 1 according to the present technology is 0.8 or more, the fluidity of the particles increases when mixed with other materials such as resin, and an increase in viscosity can be suppressed.

In addition, in the present technology, the sphericity is a value calculated by the following formula.
Sphericality = [minor diameter of particle outer diameter]/[long diameter of particle outer diameter]

The material forming the inorganic particles 1 according to the present technology is not particularly limited, and can be formed from materials that can be used for general inorganic particles. In particular, it is preferable to use a silicon compound represented by the following general formula (1) in the present technology.

(In the formula, R ¹ is a non-hydrolyzable group, an alkyl group having 1 to 20 carbon atoms, a (meth)acryloyloxy group or an epoxy group-containing alkyl group having 1 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 multiple R ¹ , each R ¹ may be the same or different, and when there are multiple OR ² , each OR ² may be the same or different.)

Here, in the non-hydrolyzable group R ¹ , the alkyl group having 1 to 20 carbon atoms preferably has 1 to 10 carbon atoms, and the alkyl group may be linear, branched or cyclic. may be Examples of this alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl and cyclopentyl. group, cyclohexyl group, and the like.

In R ¹ , which is a non-hydrolyzable group, the alkyl group having 1 to 20 carbon atoms having a (meth)acryloyloxy group or an epoxy group is preferably an alkyl group having 1 to 10 carbon atoms having the above substituents, and This alkyl group may be linear, branched or cyclic. Examples of alkyl groups having this substituent include γ-acryloyloxypropyl group, γ-methacryloyloxypropyl group, γ-glycidoxypropyl group, 3,4-epoxycyclohexyl group and the like.

In the non-hydrolyzable group R ¹ , 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 linear, branched or cyclic. There may be. Examples of this alkenyl group include vinyl group, allyl group, butenyl group, hexenyl group, octenyl group and the like.

In the non-hydrolyzable group R ¹ , the aryl group having 6 to 20 carbon atoms preferably has 6 to 10 carbon atoms, such as phenyl, tolyl, xylyl and naphthyl groups. The aralkyl group having 7 to 20 carbon atoms preferably has 7 to 10 carbon atoms, such as benzyl group, phenethyl group, phenylpropyl group and naphthylmethyl group.

R ² , which is an alkyl group having 1 to 6 carbon atoms, may be linear, branched, or cyclic, and examples thereof include methyl, ethyl, n-propyl, isopropyl, n -butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, cyclopentyl group, cyclohexyl group and the like.

Examples of the silicon compound represented by the general formula (I) include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, Methoxysilane, propyltriethoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, dimethyldiethoxysilane, divinyldimethoxysilane, Divinyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trivinylmethoxysilane, trivinylethoxysilane, etc., may be mentioned, and these may be used singly or in combination of two or more. It is possible.

The surface of the inorganic particles 1 according to the present technology may be treated with a resin, a silane coupling agent, or the like for the purpose of improving fluidity and suppressing viscosity increase when mixed with other materials such as resin.

Specific examples of silane coupling agents include phenyltriethoxysilane, phenyltrimethoxysilane, diphenyldiethoxysilane, diphenyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, N- 2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, 3-glycides xypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, alkyltriethoxysilane, alkyltrimethoxysilane, dialkyldiethoxysilane, dialkyldimethoxysilane , alkyltrimethoxysilane, etc., and these may be used singly or in combination of two or more.

The inorganic particles 1 according to the present technology may be a mixture of two or more inorganic particles 1 having different average particle diameters. By having two or more types of particle sizes, the filling rate of the particles can be improved when kneading into materials such as resins and ceramics, and the ratio of the air layer can also be improved. As a result, the desired effects such as low dielectric constant and low refractive index can be sufficiently exhibited.

Applications of the inorganic particles 1 according to the present technology described above are not particularly limited, and the general inorganic particles 1 can be applied to various uses. The inorganic particles 1 according to the present technology can be suitably used as particles for dielectric constant adjustment and refractive index adjustment.

<2. Low Dielectric Material, Low Refractive Index Material>
The inorganic particles 1 according to the present technology can be suitably used for low dielectric materials and low refractive index materials by utilizing their dielectric constant lowering action and refractive index lowering action. Low dielectric materials and low refractive index materials using inorganic particles 1 according to the present technology are used in a wide range of fields such as fillers, spacers, ceramic raw materials, resin modifiers, adsorbents, electronic materials, semiconductor materials, paints, cosmetics, etc. It can be used as a low dielectric material and a low refractive index material.

<3. Method for producing inorganic particles 1>
FIG. 2 is a flow diagram of a method for manufacturing inorganic particles 1 according to the present technology. The method for manufacturing the inorganic particles 1 according to the present technology is a method that performs at least the seed particle liquid preparation step S1, the particle size growth step S2, the measurement step S3, and the reaction termination step S4. Moreover, in the present technology, it is also possible to perform the drying step S5 and the baking step S6 as necessary. Each step will be described in detail below in chronological order.

(1) Seed particle liquid preparation step S1
The seed particle liquid preparation step S1 is a step of hydrolyzing and condensing an inorganic compound in a solution to prepare a seed particle liquid.

An aqueous medium is preferably used for the solution, and water or a mixture of water and a water-miscible organic solvent can be used. Examples of water-miscible organic solvents include lower alcohols such as methanol, ethanol, propanol and butanol, and ketones such as acetone. These may be mixed with water alone, or may be mixed with water in combination of two or more.

The seed particle-forming liquid is prepared by adding the compound represented by the general formula (1) to the aqueous medium and stirring at a temperature of about 0 to 50° C. to obtain a uniform aqueous solution. It is done by In this case, the concentration of the compound represented by the general formula (1) is preferably 20% by mass or less, and more preferably in the range of 5 to 15% by mass from the viewpoint of volumetric efficiency.

(2) Particle size growth step S2
The particle diameter growth step S2 is a step of adding an inorganic compound-containing solution to the seed particle liquid prepared in the seed particle liquid preparation step S1 and stirring to grow the particle diameter.

As the inorganic compound-containing solution, the same solution as the seed particle liquid prepared in the seed particle liquid preparation step S1 can be used. The type of liquid may be different from that of the seed particle forming liquid. From the viewpoint of workability and the properties of the obtained particles, it is preferable to use the completely same solution as the seed particle liquid prepared in the seed particle liquid preparing step S1 as the inorganic compound-containing solution.

A catalyst is preferably used in the particle size growth step S2. As a catalyst, it is preferable to use, for example, ammonia and/or amines. Specifically, when the inorganic compound-containing solution is added to the seed particle liquid prepared in the seed particle liquid preparation step S1 and stirred, the ammonia-containing aqueous solution and/or the amine-containing aqueous solution are added at once, and the general The compound represented by Formula (1) is hydrolyzed and condensed to grow the particle size.

Examples of amines include monomethylamine, dimethylamine, monoethylamine, diethylamine, ethylenediamine and the like, and these may be used singly or in combination of two or more.

In the present technology, ammonia is suitable as the catalyst because it is less toxic, easy to remove, and inexpensive.

Further, examples of the ammonia-containing aqueous solution and/or amine-containing aqueous solution include a solution obtained by dissolving ammonia and/or amine in water or a mixed solvent of water and a water-miscible organic solvent. Here, examples of the water-miscible organic solvent are the same as those exemplified in the explanation of the preparation of the seed particle forming liquid in (1) above.

The amount of the ammonia-containing aqueous solution and/or the amine-containing aqueous solution to be added is not particularly limited as long as it does not impair the effects of the present technology, but the pH of the seed particle liquid after seed particle formation is preferably 8.2 to 11.0. is preferably set within the range of The reaction temperature can be freely set according to the kind of the compound represented by the general formula (1) as a starting material, and can be set, for example, in the range of 0 to 50°C. The formation time of the seed particles is also not particularly limited, but usually within 1 hour is sufficient.

(3) Measurement step S3
The measuring step S3 is a step of measuring the particle size continuously or at predetermined intervals during the particle size growing step S2.

The method for measuring the particle size is not particularly limited, and a general measuring method capable of measuring microparticles can be freely selected and used. Examples thereof include a measuring method using an optical microscope video micrometer and a measuring method using a Coulter counter.

(4) Reaction stop step S4
The reaction stopping step S4 is a step of stopping the reaction during particle size growth. In the method for producing the inorganic particles 1 according to the present technology, it is important to stop the reaction while the particle diameter is growing. If the reaction is stopped after the particle size has grown completely, there is a possibility that the inorganic particles will have no internal space. Inorganic particles 1 having

Specifically, while performing the particle size growth step S2, the measurement step S3 is performed continuously or at predetermined intervals, and when the particle size changes, the ammonia-containing aqueous solution and/or the amine-containing aqueous solution is added for aging. This aging can be freely set according to the type of the compound represented by the general formula (1), which is the raw material. .

(5) Drying step S5
The drying step S5 is a step of drying the produced particles after the termination step S4. By performing the drying step S5, it is possible to prevent the aggregation of the inorganic particles 1 from occurring.

Specifically, after completion of the reaction stop step S4, the generated particles are sufficiently washed in accordance with a conventional method, and if necessary, classified to remove extremely large or extremely small particles, followed by drying. The classification treatment method is not particularly limited, but a wet classification method or the like can be used in which the sedimentation velocity is different depending on the particle diameter. Drying treatment can be performed at a temperature in the range of, for example, 100 to 200°C.

(6) Firing step S6
The firing step S6 is a step of firing the particles after the drying step S5. By firing the particles, the organic groups in the particles are decomposed, and the inorganic particles 1 can be obtained.

The firing method in the firing step S6 can be freely set as long as the effect of the present technology is not impaired. It is preferable to preliminarily calcine at a temperature below the temperature, and then calcine at a temperature equal to or higher than the decomposition temperature of the organic group. If the temperature is immediately raised to a temperature higher than the decomposition temperature of the organic groups contained in the particles and fired, the decomposition and detachment of the organic groups will occur rapidly, and the breaking strength of the particles will decrease, and in some cases, they will shrink rapidly. It may lead to unfavorable situations such as cracking of particles. However, after performing a pre-baking treatment at a temperature that is at least 100°C lower than the decomposition temperature of the organic group and below the decomposition temperature of the organic group, the baking treatment is performed at a temperature that is at least the decomposition temperature of the organic group. By doing so, it is possible to avoid the above-mentioned undesirable situation.

The sintering temperature and sintering time in the sintering step S6 can be freely set according to the type of organic group constituting the particles. If it has an organic group that is easily thermally decomposed, it is desirable to treat it at a relatively low temperature, and if it has an organic group that is difficult to thermally decompose, it is preferable to treat it at a high temperature.

As a specific example, in the case of polymethylsilsesquioxane (PMSO)/polyvinylsilsesquioxane (PVSO) composite particles, pre-baking is maintained at a temperature in the range of 300 to 500° C. for about 3 to 50 hours. After the treatment, the substrate is maintained at a temperature in the range of 600 to 1300° C. for about 3 to 50 hours for firing treatment, whereby the organic groups can be completely decomposed.

The atmosphere in the firing step S6 preferably has an oxygen concentration of a certain level or more, for example, 10% by volume or more, in order to oxidatively decompose the organic groups in the particles. Also, the firing device is not particularly limited, and a general firing device such as an electric furnace or a rotary kiln can be used.

The present invention will be described in more detail below based on examples.
It should be noted that the examples described below are examples of representative examples of the present invention, and the scope of the present invention should not be construed narrowly.

<Experimental example 1>
In Experimental Example 1, the difference in dielectric constant due to the difference in the form of inorganic particles was verified.

1. Production of Inorganic Particles Inorganic particles according to Examples 1 to 9 were produced by the following method.

[Example 1]
(1) Preparation of Seed Particle Liquid 500 g of methyltrimethoxysilane (hereinafter abbreviated as MTMS) was added to 5000 g of ion-exchanged water, and the mixture was stirred at 30° C. and 100 rpm. At the beginning of the addition of MTMS, it was dispersed in the aqueous solution in the form of oil droplets, but after about 3 hours, MTMS was completely dissolved to form a uniform solution, which was used as the seed particle forming liquid.

(2) Preparation of Particle Size Growth Liquid 3300 g of MTMS was added to 33000 g of deionized water, and the mixture was stirred at 30° C. and 100 rpm. At the beginning of the addition of MTMS, it was dispersed in the aqueous solution in the form of oil droplets, but after about 1 hour, MTMS was completely dissolved to form a uniform solution, which was used as the particle size growth liquid.

(3) Formation of Seed Particles In the seed particle-forming solution prepared in (1) above, the stirring speed was lowered to 30 rpm, and 50 ml of 1 mol/liter ammonia water was added at once. Two minutes after the addition of aqueous ammonia, particles grew and the solution became cloudy.

(4) Growth of Particle Diameter 3360 g of the seed particle liquid obtained in (3) was added to the total amount of 36,300 g of the particle diameter growth liquid obtained in (2) while stirring at 20 rpm.

(5) Termination of Reaction Every 10 minutes after the addition of the seed particle solution in (4) above, the particle diameter was measured with an optical microscope video micrometer. 50 minutes after the addition during particle size growth, 500 g of 25% by mass aqueous ammonia was added dropwise with a metering pump, and aging was carried out at room temperature for 16 hours.

(6) Drying and Firing After drying the obtained particles, the temperature is raised from room temperature to 400° C. under the condition of an air flow rate of 2 liters/minute, and after pre-firing at that temperature for 24 hours, 900° C. and maintained at that temperature for 9 hours for main firing. After main firing, the mixture was cooled to room temperature to produce inorganic particles.

[Example 2]
Inorganic particles were produced in the same manner as in Example 1 except that the amount of MTMS added in (1) was changed to 5 g and the amount of MTMS added in (2) was changed to 33 g.

[Example 3]
Inorganic particles were produced in the same manner as in Example 1 except that the amount of MTMS added in (1) was changed to 10 g and the amount of MTMS added in (2) was changed to 100 g.

[Example 4]
Inorganic particles were produced in the same manner as in Example 1 except that the amount of MTMS added in (1) was changed to 20 g and the amount of MTMS added in (2) was changed to 500 g.

[Example 5]
Inorganic particles were produced in the same manner as in Example 1 except that the amount of MTMS added in (1) was changed to 100 g and the amount of MTMS added in (2) was changed to 1000 g.

[Example 6]
Inorganic particles were produced in the same manner as in Example 1 except that the amount of MTMS added in (1) was changed to 200 g and the amount of MTMS added in (2) was changed to 2000 g.

[Example 7]
Inorganic particles were produced in the same manner as in Example 1 except that the amount of MTMS added in (1) was changed to 700 g and the amount of MTMS added in (2) was changed to 4950 g.

[Example 8]
Inorganic particles were produced in the same manner as in Example 1 except that the amount of MTMS added in (1) was changed to 1000 g and the amount of MTMS added in (2) was changed to 4950 g.

[Example 9]
(1) Preparation of Seed Particle Forming Liquid 200 g of MTMS was added to 1000 g of ion-exchanged water, and the mixture was stirred at 20° C. and 100 rpm. At the beginning of the addition of MTMS, it was dispersed in the aqueous solution in the form of oil droplets, but after about 3 hours, MTMS was completely dissolved to form a uniform solution, which was used as the seed particle forming liquid.

(2) Preparation of first-stage particle size growth liquid 200 g of MTMS was added to 1000 g of ion-exchanged water, and the mixture was stirred at 30° C. and 100 rpm. At the beginning of the addition of MTMS, it was dispersed in the aqueous solution in the form of oil droplets, but after about 1 hour, MTMS was completely dissolved to form a uniform solution, which was used as the first-stage particle size growth liquid.

(3) Preparation of Second-Step Particle Size Growth Liquid 6000 g of MTMS was added to 30000 g of deionized water, and the mixture was stirred at 30° C. and 100 rpm. At the beginning of the addition of MTMS, it was dispersed in the aqueous solution in the form of oil droplets, but after about 1 hour, MTMS was completely dissolved to form a uniform solution, which was used as the first-stage particle size growth liquid.

(4) Formation of Seed Particles In the seed particle-forming solution prepared in (1) above, the stirring speed was lowered to 30 rpm, and 10 ml of 1 mol/liter ammonia water was added at once. Aqueous ammonia was added and stirring was continued for 30 minutes to obtain seed particles.

(5) Particle size growth 1st stage 300 g of the seed particle solution obtained in (4) above is added to the total amount of 1200 g of the first stage particle size growth liquid of (2) above while stirring at 20 rpm, Stirring was continued for 45 minutes to obtain first-stage particle size growth particles.

(6) Growth of particle size, second stage: While stirring the total amount of 36,000 g of the liquid for second-stage particle size growth in (3) above at 20 rpm, the liquid for first-stage particle size growth obtained in (5) above is added. 1500 g was added and stirring continued for 10 hours.

(7) Termination of Reaction After stirring for 10 hours in (6) above, 500 g of 25% by mass aqueous ammonia was added dropwise with a metering pump, and aging was carried out at room temperature for 3 hours.

(8) Drying and Firing After drying the obtained particles, the temperature is raised from room temperature to 340° C. under the condition of an air flow rate of 2 liters/minute, and the temperature is maintained for 24 hours for firing, and then cooled to room temperature. to produce inorganic particles.

2. Measurement The average particle size, specific surface area, specific gravity, spatial ratio, and dielectric constant of the inorganic particles produced above were measured using the following methods. As a comparative example, silica particles having an average particle diameter of 5.027 μm and containing no internal space (“Hipresica FQ N2N” manufactured by Ube Exsimo Co., Ltd.) were used. In addition, the inorganic particles of Example 9 were observed with an optical microscope. A photomicrograph is shown in FIG.

[Average particle size]
The average particle size was measured with a Coulter counter.

[Specific surface area]
The specific surface area was measured by the gas adsorption method.

[specific gravity]
The specific gravity was measured using nitrogen gas by the gas replacement method.

[Spatial ratio]
The space ratio was calculated using the following formula.
Spatial ratio = {([Specific gravity of Comparative Example 1] - [Specific gravity of each example]) / [Specific gravity of Comparative Example 1]} x 100

[Permittivity]
Epoxy resin (“jER828” manufactured by Mitsubishi Chemical Co., Ltd.): curing agent (“YH306” manufactured by Mitsubishi Chemical Co., Ltd.): 2-ethyl-4-methylimidazole = 5: 6: 0.05 weight ratio resin mixture 20% by weight of the inorganic particles prepared above were added to the mixture and kneaded with a spatula. Next, the kneaded resin mixture was kneaded three times with a roll mill ("desktop roll mill" manufactured by Kodaira Seisakusho Co., Ltd.) adjusted to a gap of 0.08 mm to prepare a resin mixture. The resulting resin mixture was poured into a mold of 1.2 mm×1.2 mm×70 mm and cured by heating at 120° C. for 6 hours to prepare a dielectric constant evaluation sample. The dielectric constant of the obtained sample was measured at a frequency of 5.8 GHz using the cavity resonator perturbation method.

3. Results The results are shown in Table 1 below.

4. Discussion As shown in FIG. 3, the inorganic particles according to the present technology had two or more spaces inside. Further, as shown in Table 1, the inorganic particles of Examples 1 to 9 had lower specific gravities and lower dielectric constants than the inorganic particles of Comparative Example 1, which had no internal space. It was also confirmed that the inorganic particles of Examples 1 to 9 had a specific surface area of 50 m ² /g or less, and almost no pores were present on the particle surfaces.

1: inorganic particles 11: space

Claims (7)

an average particle outer diameter of 0.1 to 70 μm,
a specific surface area of 50 m ² /g or less,
Inorganic particles having two or more spaces inside. 2. The inorganic particles according to claim 1, which are inorganic particles made from a silicon compound represented by the following general formula (1).
[Chemical 1]

(In the formula, R ¹ is a non-hydrolyzable group, an alkyl group having 1 to 20 carbon atoms, a (meth)acryloyloxy group or an epoxy group-containing alkyl group having 1 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 multiple R ¹ , each R ¹ may be the same or different, and when there are multiple OR ² , each OR ² may be the same or different.) 3. The inorganic particles according to claim 1, wherein the ratio of the total volume of said spaces to the volume of said inorganic particles is 5 to 50%. 4. The inorganic particles according to any one of claims 1 to 3, which are surface-treated with a silane coupling agent. A low dielectric material using the inorganic particles according to any one of claims 1 to 4. A low refractive index material using the inorganic particles according to any one of claims 1 to 4. a seed particle liquid preparation step of hydrolyzing and condensing an inorganic compound in a solution to prepare a seed particle liquid;
a particle size growth step of adding an inorganic compound-containing solution to the seed particle liquid and stirring to grow the particle size;
a measuring step of measuring the particle size continuously or at predetermined intervals during the particle size growing step;
a reaction stopping step of stopping the reaction during particle size growth;
A method for producing inorganic particles having two or more spaces inside.