Silicone particles and method for producing the same

Abstract

This invention provides silicone particles with a shape not previously proposed and a method for producing the same. [Solution] The present invention is a method for producing silicone particles, comprising the steps of: hydrolyzing and condensing a silane monomer having polymerizable unsaturated groups in a solvent A containing water to obtain a dispersion of a polysiloxane compound having polymerizable unsaturated groups; mixing a solvent X that is immiscible with solvent A and also immiscible with the polysiloxane compound with the dispersion; and radical polymerization of the polysiloxane compound.

Description

[Technical Field]

[0001] The present invention relates to silicone particles and a method for producing the same. [Background technology]

[0002] In polymer particles formed from silane monomers having polymerizable unsaturated groups, non-spherical particles such as those with uneven surfaces, pebble-like particles, convex lens-like particles, and flattened particles have been proposed. These particles are attracting attention as additives for various resins and substrates due to their mechanical and optical properties derived from their distinctive shapes.

[0003] For example, Patent Document 1 discloses polymer fine particles formed from 100 parts by mass of alkoxysilane (A) having an ethylenically unsaturated bond-containing group and 40 parts by mass or more of tetraalkoxysilane (B), and having at least one recess whose major axis is 0.5 or more relative to the particle diameter. It is stated that the recess is formed by the difference in the ease with which alkoxysilane (A) having an ethylenically unsaturated bond-containing group and tetraalkoxysilane (B) undergo hydrolysis and polycondensation.

[0004] Furthermore, Patent Document 2 discloses polymer particles having shrinkage marks on their surface, wherein the ratio of the minor axis of the shrinkage mark to the diameter D of the polymer fine particles (minor axis of shrinkage mark / polymer fine particle diameter D) is greater than 0 and less than 1, and the silicon atom content is 3% by mass or more. It is described that such polymer particles can be produced by hydrolyzing and polycondensing polymerizable organic alkoxysilane to form siloxane particles (seed particles), absorbing vinyl monomers into the siloxane particles, polymerizing them using a water-soluble polymerization initiator, and drying them. It is also described that when vinyl monomers are polymerized into the network formed by the polycondensation of alkoxysilane, if the polymerization is initiated with a water-soluble polymerization initiator, areas with a low polymerization density of vinyl monomers occur, causing partial shape changes, while areas that maintain their shape due to the original siloxane network remain, resulting in the formation of granular or streaky shrinkage marks on the surface. [PRIOR ART DOCUMENT] [PATENT DOCUMENTS]

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2017-66328 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2017-128706 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] An object of the present invention is to provide silicone particles having a shape that has not been conventionally proposed, and a method for producing the same. [Means for Solving the Problems]

[0007] The present invention that has achieved the above object is as follows. [1] A step of hydrolyzing and condensing a silane-based monomer having a polymerizable unsaturated group in a solvent A containing water to obtain a dispersion of a polysiloxane-based compound having a polymerizable unsaturated group; a step of mixing the dispersion with a solvent X that is incompatible with the solvent A and also incompatible with the polysiloxane-based compound; and a step of radically polymerizing the polysiloxane-based compound. A method for producing silicone particles. [2] The production method according to [1], wherein the polysiloxane-based compound is a linear polysiloxane-based compound. [3] The production method according to [1] or [2], wherein the solvent X is a hydrocarbon-based solvent. [4] Silicone particles having a defective portion on the surface or inside of the particle, wherein the shape of the defective portion is a shape of at least a part of a sphere. Silicone particles. [5] The silicone particles according to [4], wherein the silicone particles have a defective portion opening on the particle surface, and a diameter of the opening is more than 0 and less than 1 relative to a diameter of the silicone particles. [6] Silicone particles according to [4] or [5], having a number-average particle size of 1 to 9 μm. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide silicone particles with a shape different from conventionally proposed silicone particles, and a method for producing the same. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a photograph used as a substitute for a diagram, showing the SEM observation of the silicone particles E1 obtained in Example 1. [Figure 2] Figure 2 is a photograph used as a substitute for a diagram, showing the SEM observation of the silicone particles E2 obtained in Example 2. [Modes for carrying out the invention]

[0010] 1. Method for manufacturing silicone particles The present invention provides a method for producing silicone particles, comprising: (1) hydrolyzing and condensing a silane monomer having polymerizable unsaturated groups in a solvent A containing water to obtain a dispersion of a polysiloxane compound having polymerizable unsaturated groups; (2) mixing a solvent X that is immiscible with solvent A and also immiscible with the polysiloxane compound with the dispersion; and (3) radical polymerization of the polysiloxane compound.

[0011] 1-1. Step to obtain a dispersion of polysiloxane compounds (1) In this process, a silane monomer having a polymerizable unsaturated group is hydrolyzed and condensed in solvent A containing water to obtain a polysiloxane compound. The silane monomer having a polymerizable unsaturated group preferably has at least one polymerizable unsaturated group bonded to a silicon atom in one molecule, and more preferably one polymerizable unsaturated group per molecule of the silane monomer. Examples of the polymerizable unsaturated group include a group having a vinyl group or a (meth)acryloyl group at its terminus, and a group represented by the following formula (1) is preferred.

[0012] [ka] In formula (1), R 1 R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms. 2 * represents an alkylene group having 1 to 10 carbon atoms, where m is 0 or 1, n is 0 or 1, and the group represented by formula (1) is bonded to a silicon atom by *.

[0013] R 1 Examples of alkyl groups having 1 to 10 carbon atoms include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups; and branched alkyl groups such as isopropyl, isobutyl, isopentyl, neopentyl, and 2-ethylhexyl groups.

[0014] R 1 Examples of aryl groups with 6 to 10 carbon atoms include phenyl, o-tolyl, m-tolyl, p-tolyl, 2-ethylphenyl, 3-ethylphenyl, and 4-ethylphenyl. Examples include phenyl groups, 2,3-dimethylphenyl groups, 2,4-dimethylphenyl groups, o-isopropylphenyl groups, m-isopropylphenyl groups, p-isopropylphenyl groups, and 4-butylphenyl groups.

[0015] Of these, R 1 It is preferably hydrogen or an alkyl group having 1 to 10 carbon atoms, more preferably hydrogen or an alkyl group having 1 to 5 carbon atoms, even more preferably hydrogen or an alkyl group having 1 to 2 carbon atoms (methyl group or ethyl group), even more preferably hydrogen or an alkyl group having 1 carbon atom (methyl group), and particularly preferably a methyl group.

[0016] R 2is an alkylene group having 1 to 10 carbon atoms, and examples of the alkylene group include linear alkylene groups such as a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, and a decylene group; and branched alkylene groups such as a methylmethylene group, a dimethylmethylene group, a methylethylene group, a dimethylethylene group, a methylpropylene group, and a dimethylpropylene group. Among these, linear alkylene groups are preferable. The number of carbon atoms in the alkylene group is preferably 1 to 7, more preferably 1 to 6, still more preferably 2 to 4, and even more preferably 3.

[0017] m is preferably 1, n is preferably 1, and it is more preferable that both m and n are 1.

[0018] In the silane-based monomer having a polymerizable unsaturated group, it is preferable that one or more hydrolyzable groups are bonded to a silicon atom together with the polymerizable unsaturated group, and the hydrolyzable group is -OR a1 (R a1 represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an acyl group having 2 to 10 carbon atoms), a halogen atom, a cyano group, an isocyanate group, and the like, and -OR a1 the group represented by is more preferable.

[0019] Per molecule of the silane-based monomer having a polymerizable unsaturated group, the total number of polymerizable unsaturated groups and hydrolyzable groups bonded to a silicon atom is preferably 2 or more, more preferably 3 or more, and may be 4. When the total number of polymerizable unsaturated groups and hydrolyzable groups bonded to a silicon atom per molecule of the silane-based monomer having a polymerizable unsaturated group is 2 or 3, the remaining bonding site of the silicon atom is bonded to another group R a2 is preferably bonded, and the group R a2 includes, for example, a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0020] R a1 and R a2As alkyl groups with 1 to 10 carbon atoms, R 1 Examples of alkyl groups similar to those listed above include R. a1 and R a2 If it contains two or more alkyl groups with 1 to 10 carbon atoms, they may be different or the same, but it is preferable that they be the same. a1 and R a2 A linear alkyl group is preferred. The fewer carbon atoms in the alkyl group, the faster the hydrolysis rate; therefore, 1 to 7 carbon atoms are preferred, 1 to 4 carbon atoms are more preferred, 1 to 2 carbon atoms are even more preferred, and 1 carbon atom is even more preferred.

[0021] R a1 and R a2 As for aryl groups with 6 to 10 carbon atoms, R 1 Examples of aryl groups similar to those listed above include R. a1 and R a2 If the compound contains two or more aryl groups having 6 to 10 carbon atoms, these groups may be different or the same, but it is preferable that they be the same. The number of carbon atoms in the aryl groups is preferably 6 to 9, more preferably 6 to 8, even more preferably 6 to 7, and even more preferably 6.

[0022] R a1 Examples of acyl groups having 2 to 10 carbon atoms include acetyl groups and propionyl groups. The number of carbon atoms in the acyl group is preferably 2 to 7, more preferably 2 to 4, and 2 ~3 is more preferable, and 2 is even more preferable.

[0023] The total number of carbon atoms in formula (1) is preferably 2 to 10, more preferably 3 to 9, and even more preferably 5 to 8.

[0024] The groups represented by formula (1) are preferably vinyl groups; (meth)acryloyloxy groups; alkyl groups of (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and t-butyl (meth)acrylate.

[0025] The silane monomer having a polymerizable unsaturated group is preferably a compound represented by the following formula (2).

[0026] [ka] In formula (2), R Z R is a group represented by the above formula (1), a21 The above R a2 This is synonymous with X being a hydrolyzable group, a being 1 or 2, b being 1 to 3, and a+b being 2 to 4.

[0027] R in equation (2) Z The preferred range of is the same as the preferred range of formula (1) above, and the preferred range of X is the same as the preferred range of the hydrolyzable group described above. a21 The preferred range is the above R a2 This is the same as the preferred range of R. Z The preferred range of R a21 The preferred ranges for and X can be combined as appropriate.

[0028] The compound represented by the above formula (2) is R Z However, R in equation (1) 1 is hydrogen, or an alkyl group having 1 to 3 carbon atoms, R 2 It is an alkylene group having 1 to 5 carbon atoms, where both m and n are 1, and R a21 is a linear alkyl group having 1 to 4 carbon atoms, and X is -OR a1 (R a1The group is represented by a linear alkyl group having 1 to 4 carbon atoms, and it is preferable that the compound has a group of 1 or 2 (particularly 1), b is 1 to 3 (particularly 2 or 3), and a+b is 3 or 4.

[0029] Specifically, silane monomers having polymerizable unsaturated groups include γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylethyldiethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-acryloxypropylethyldimethoxysilane, γ-acryloxypropylmethyldiethoxysilane, γ-acryloxypropylethyldiethoxysilane, and γ-methacryloxyethylmethyl Examples include dialkoxysilanes having a (meth)acryloxyalkyl group, such as dimethoxysilane and γ-methacryloxyethoxypropylmethyldimethoxysilane; trialkoxysilanes having a (meth)acryloxyalkyl group, such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, and γ-acryloxypropyltriethoxysilane; and dialkoxysilanes having a vinyl group, such as vinylmethyldimethoxysilane and vinylmethyldiethoxysilane. Of these, dialkoxysilanes having a (meth)acryloxyalkyl group or trialkoxysilanes having a (meth)acryloxyalkyl group are preferred, and γ -Methacryloxypropylmethyldimethoxysilane or γ-methacryloxypropyltrimethoxysilane are more preferred. These may be used alone or in combination of two or more, but it is preferable to use them alone.

[0030] In the process of obtaining the polysiloxane compound, other silane monomers other than the polymerizable unsaturated group-containing silane monomer may be added. Examples of other silane monomers include silane monomers that do not have polymerizable unsaturated groups, specifically R in formula (2) above. ZHowever, examples include hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Examples of alkyl groups having 1 to 10 carbon atoms and aryl groups having 6 to 10 carbon atoms include R 1 Examples of other silane monomers include groups similar to the alkyl and aryl groups mentioned above. Specific examples of other silane monomers include dimethyldimethoxysilane, diethyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, dimethyldiacetoxysilane, and diethyldiacetoxysilane. These may be used individually or in combination of two or more.

[0031] The amount of the silane monomer having polymerizable unsaturated groups charged is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of solvent A containing water.

[0032] Hydrolysis and condensation of silane monomers having polymerizable unsaturated groups may be carried out in the presence of a dispersant. Using a dispersant can improve the dispersibility of particles during hydrolysis and condensation, and make it easier to control the shape of defects in the resulting particles. Known dispersants can be used, for example, water-soluble polymer dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, cellulose, gelatin, sodium polyacrylate, and sodium polymethacrylate; anionic surfactants such as sodium lauryl sulfate and polyoxyethylene alkylphenyl ether sulfate (e.g., polyoxyethylene distyrylphenyl ether sulfate ammonium); cationic surfactants such as alkylamine salts and quaternary ammonium salts; amphoteric surfactants such as lauryldimethylamine oxide; and nonionic surfactants such as polyoxyethylene alkyl ethers. These may be used individually or in combination of two or more. It is preferable to use a water-soluble polymer dispersant. The amount of dispersant used is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 30 parts by mass, and most preferably 1 to 20 parts by mass, per 100 parts by mass of the silane monomer having polymerizable unsaturated groups. The dispersant may be added during hydrolysis and condensation, as well as in subsequent steps, but if the dispersant is present in the subsequent steps after being added during hydrolysis and condensation, it is not necessary to add it again.

[0033] The solvent A used during the hydrolysis and condensation of the polymerizable unsaturated silane monomer may contain an organic solvent in addition to water. Examples of organic solvents include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, and 1,4-butanediol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; (cyclo)paraffins such as isooctane and cyclohexane; ethers such as dioxane and diethyl ether; and aromatic hydrocarbons such as benzene and toluene. These may be used individually or in combination of two or more. Among the organic solvents, alcohols are more preferred. The amount of organic solvent is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and preferably 45 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less, per 100 parts by mass of the total amount of organic solvent and water.

[0034] The hydrolysis and condensation of the silane monomer having polymerizable unsaturated groups is preferably carried out in the presence of a catalyst. As the catalyst, an acid catalyst or a basic catalyst can be used. The hydrolysis and condensation of the silane monomer having polymerizable unsaturated groups may be carried out collectively in the presence of a basic catalyst, or the hydrolysis of the silane monomer having polymerizable unsaturated groups may be carried out in the presence of an acid catalyst, and the resulting hydrolysate-containing liquid may be mixed with a basic catalyst, and the condensation reaction may be carried out in the presence of the basic catalyst. In particular, it is preferable that the hydrolysis and condensation of the silane monomer having polymerizable unsaturated groups be carried out collectively in the presence of a basic catalyst.

[0035] Examples of basic catalysts include ammonias, amines, quaternary ammonium compounds, alkali metal hydroxides, and alkaline earth metal hydroxides. Examples of ammonias include ammonia and ammonia generators such as urea. Examples of amines include aliphatic amines such as methylamine, ethylamine, propylamine, n-butylamine, dimethylamine, dibutylamine, trimethylamine, and tributylamine; alicyclic amines such as cyclohexylamine; aromatic amines such as benzylamine; and alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine. Examples of quaternary ammonium compounds include tetramethylammonium hydroxide and tetrabutylammonium hydroxide. Examples of alkali metal hydroxides include sodium hydroxide. Examples of alkaline earth metal hydroxides include magnesium hydroxide. The basic catalyst is preferably ammonias. One or more basic catalysts may be used. Any acid, whether organic or inorganic, can be used as the acid catalyst, and preferably their aqueous solutions are used. Specifically, examples of organic acids include formic acid, acetic acid, propionic acid, oxalic acid, and citric acid, while examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. One or more of these acid catalysts may be used.

[0036] The amount of catalyst (or the total amount if multiple types are used) is preferably 0.005 to 0.2 parts by mass, and more preferably 0.01 to 0.1 parts by mass, per 100 parts by mass of the silane monomer having polymerizable unsaturated groups.

[0037] The hydrolysis and condensation of the silane monomer having polymerizable unsaturated groups can be carried out, for example, by mixing a solvent A containing water with the silane monomer having polymerizable unsaturated groups, further mixing in a catalyst and / or dispersant as needed, and stirring for a period of preferably 10 minutes to 100 hours, more preferably 30 minutes to 50 hours, even more preferably 1 to 10 hours, and even more preferably 1 to 2 hours. The temperature during stirring is preferably 0 to 100°C, more preferably 10 to 70°C, and even more preferably 20 to 50°C. The order of adding water, a solvent other than water as needed, a silane monomer having polymerizable unsaturated groups, and a catalyst and / or dispersant as needed is not particularly limited, but it is preferable to first mix water, a solvent other than water, a catalyst and / or dispersant, and then dropwise add and mix the silane monomer having polymerizable unsaturated groups, or to first mix water, a catalyst and / or dispersant, and then dropwise add and mix a mixture of the silane monomer having polymerizable unsaturated groups and a solvent other than water.

[0038] It is preferable to hydrolyze the silane monomer having polymerizable unsaturated groups with water and then condense it to form a chain-like polysiloxane compound. In forming the chain-like polysiloxane compound, a cyclic polysiloxane compound may be formed by hydrolysis and condensation of the silane monomer, and then the chain-like polysiloxane compound may be formed by ring-opening polymerization.

[0039] It is preferable to carry out ring-opening polymerization of cyclic polysiloxane compounds in the presence of a reaction catalyst, which is at least one selected from organo-onium compounds, alkali metal hydroxides, and organic sulfonic acids. These reaction catalysts may be used individually or in combination of two or more. This is also acceptable. The reaction catalyst is more preferably at least one selected from the group consisting of organo-onium compounds and alkali metal hydroxides, and even more preferably an organo-onium compound. This facilitates ring-opening polymerization of the cyclic polysiloxane compound.

[0040] The organo-onium compound is an onium compound having at least one hydrocarbon group. Preferred organo-onium compounds include organo-ammonium compounds and organo-phosphonium compounds. Of these, organo-ammonium compounds are more preferred. Examples of organo-ammonium compounds include quaternary ammonium halogenated salts having hydrocarbon groups. Examples of organo-phosphonium compounds include quaternary phosphonium halogenated salts having hydrocarbon groups. These may be used individually or in combination of two or more. The amount of reaction catalyst charged is preferably 1 to 10 parts by mass per 100 parts by mass of polymerizable unsaturated group-containing silane monomer.

[0041] 1-2. Step (2) of mixing solvent X with the dispersion of the polysiloxane compound. Next, the dispersion of the polysiloxane compound obtained in step (1) is mixed with solvent X. Solvent X is a solvent that is immiscible with solvent A and also immiscible with the polysiloxane compound. In the present invention, because such a solvent X is used, the shape of the silicone particles obtained from a silane monomer of the same composition (such as the opening diameter of the defect described later) can be controlled without changing the composition of the silane monomer, which is the raw material for the particles. Solvent X is preferably a hydrocarbon solvent, more preferably an aliphatic hydrocarbon solvent, even more preferably an aliphatic saturated hydrocarbon solvent, even more preferably an aliphatic saturated hydrocarbon solvent having 5 to 15 carbon atoms, and particularly preferably an aliphatic saturated hydrocarbon solvent having 7 to 13 carbon atoms. Solvent X may be used alone or in combination of two or more types.

[0042] The procedure for mixing the dispersion of the polysiloxane compound with solvent X is not particularly limited, but it is preferable to add solvent X to the dispersion of the polysiloxane compound. If the aforementioned cyclic polysiloxane compound is obtained by hydrolysis and condensation of a silane monomer, it is preferable to add the reaction catalyst, which is at least one selected from the aforementioned organo-onium compound, alkali metal hydroxide, and organosulfonic acid, to the dispersion of the cyclic polysiloxane compound together with solvent X.

[0043] The amount of solvent X is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, and preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less, based on 100 parts by mass of the silane monomer having polymerizable unsaturated groups charged.

[0044] After mixing the dispersion of the polysiloxane compound with solvent X, it is preferable to stir for about 5 minutes to 3 hours. After this stirring, the polysiloxane compound and solvent X are usually dispersed in a phase-separated state.

[0045] 1-3. Step (3) of radical polymerization of polysiloxane compounds After step (2), the polysiloxane compound is subjected to radical polymerization. More specifically, the dispersion of the polysiloxane compound obtained in step (2) and a mixture of solvent X are mixed with a radical polymerization initiator.

[0046] As radical polymerization initiators, thermal polymerization initiators are preferred, and examples include peroxide-based polymerization initiators and azo compound-based polymerization initiators. Examples of peroxide-based polymerization initiators include benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, and cyclophosphate. Examples of azo compound polymerization initiators include lohexanone peroxide, t-butyl hydroperoxide, and diisopropylbenzene hydroperoxide. These may be used individually or in combination of two or more. Among these, azo compound polymerization initiators are preferred. The amount of radical polymerization initiator is not particularly limited, but using a large amount will increase the heat generation and make it difficult to control the reaction, while using a small amount may prevent radical polymerization from proceeding. Therefore, the amount of radical polymerization initiator to be charged is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 3 parts by mass, per 100 parts by mass of the silane monomer having polymerizable unsaturated groups.

[0047] The temperature for radical polymerization can be appropriately selected depending on the radical polymerization initiator used, but 30 to 100°C is preferred, and 50 to 80°C is more preferred, due to the ease of controlling the reaction. The reaction time for radical polymerization is preferably 1 to 4 hours, and more preferably 1 to 3 hours.

[0048] Silicone particles produced by radical polymerization can be isolated from the slurry using conventionally known methods such as filtration, centrifugation, and vacuum concentration. The silicone particles are then classified as needed, and typically washed and dried, and sometimes calcined. The drying temperature is not particularly limited, but 50°C to 250°C is preferred, and 80°C to 150°C is more preferred. The drying time is preferably 1 to 12 hours. Washing can be done using deionized water, methanol, etc.

[0049] 2. Silicone particles 2-1. Shape of Silicone Particles According to the manufacturing method of the present invention, silicone particles having defects on the surface or inside the particles are obtained, and the shape of the defects is that of at least a part of a sphere. The mechanism by which defects having the shape of at least a part of a sphere are formed in silicone particles is not necessarily limited to the following, but the following mechanism is possible. In a dispersion of a polysiloxane compound formed by hydrolysis and condensation of a silane monomer having polymerizable unsaturated groups, solvent X, which is immiscible with both solvent A and the polysiloxane compound, exists in an energetically stable spherical form. At least a part of the spherical solvent X is present in a manner that it penetrates the polysiloxane compound, and as polymerization of the polysiloxane compound proceeds in this state, silicone particles having defects caused by contact with solvent X are formed. Therefore, the shape of the defects is caused by at least a part of the shape of the spherical solvent X, that is, the shape is that of at least a part of a sphere.

[0050] The polysiloxane compound is usually spherical, and it is preferable that the resulting silicone particles are also silicone particles having the aforementioned defects on the surface or inside the spherical particles.

[0051] The defects in the silicone particles may be located inside the silicone particles or on the particle surface. Defects on the particle surface may be defects that open to the particle surface. When a silicone particle has a defect that opens to the particle surface, the diameter of the opening relative to the diameter of the silicone particle is greater than 0 and less than 1, preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and also preferably 0.9 or less, more preferably 0.8 or less, and even more preferably 0.6 or less.

[0052] The particle size of the silicone particles is preferably 1 μm or larger, more preferably 1.2 μm or larger, even more preferably 1.5 μm or larger, and also preferably 9 μm or smaller, more preferably 7 μm or smaller, and even more preferably 5 μm or smaller. The particle size of the silicone particles can be measured using a precision particle size distribution analyzer based on the Coulter principle (for example, the "Coulter Multisizer III" manufactured by Beckman Coulter), and it is preferable that the number-average particle size is within the above range. As a sample for particle size measurement, an aqueous solution with a particle concentration of 0.1 to 3 mass% and containing about 0.5 to 2 mass% of emulsifier may be used.

[0053] 2-2. Composition of Silicone Particles The silicone particles produced by the manufacturing method of the present invention have a structure derived from a silane monomer having polymerizable unsaturated groups, and preferably have a chain-like polysiloxane structure represented by the following formula (3).

[0054] [ka]

[0055] Equation (3) is -Si(R x )(R y This means that p units of )O are linked together in a row. p represents an integer greater than or equal to 3, p pieces of R x Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a group represented by the following formula (4), and at least one R x This is the group represented by the following formula (4). p pieces of R y Each of these independently represents O-* (where * is the bond with silicon in other silane monomers), hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0056] [ka]

[0057] In formula (4), R b1 This represents hydrogen, an alkyl group with 1 to 10 carbon atoms, or an aryl group with 6 to 10 carbon atoms. R b2 This represents an alkylene group with 1 to 10 carbon atoms. q is either 0 or 1, r is either 0 or 1. * indicates a link, ** indicates a bond with Si.

[0058] R y As for the above R a2 Examples include O-* (* represents the bond with silicon in other silane monomers) in siloxane bonds Si-O-Si, which are formed by the further condensation of Si-OH groups obtained by hydrolysis of hydrolyzable groups bonded to a silicon atom, similar to the above. y These may be the same group or different groups, but multiple R y It is preferable that they are the same group.

[0059] R x The alkyl groups having 1 to 10 carbon atoms and the aryl groups having 6 to 10 carbon atoms are as follows: R in equation (1) 1 Examples include alkyl groups with 1 to 10 carbon atoms and aryl groups with 6 to 10 carbon atoms. Multiple R x These may be the same group or different groups, but multiple R x It is preferable that the groups are the same. Multiple R x It is more preferable that the group is represented by formula (4).

[0060] R b1 For example, R in equation (1) above. 1 Similar groups can be cited. b2 For example, R in equation (1) above. 2Similar groups can be cited. q is 0 or 1, and q is preferably 1. r is 0 or 1, and r is preferably 1. The sum of q and r is preferably 1 or 2, and more preferably 2.

[0061] In the above formula (3), p represents an integer of 3 or more, preferably between 3 and 21, more preferably between 6 and 18, even more preferably between 6 and 15, particularly preferably between 6 and 12, and most preferably 9. Also, p is preferably a multiple of 3.

[0062] In the chain-like polysiloxane structure, it is preferable that the p consecutively linked structural units represented by formula (3) are all the same structural unit. That is, the R of the p consecutively linked structural units represented by formula (3) x Each of them is the same, and the R of the constituent unit y It is preferable that these components are the same. When synthesizing such a chain-like polysiloxane structure, it is not necessary to use various raw materials during the synthesis, resulting in a stable quality chain-like polysiloxane structure.

[0063] The bonds* of the portion of the group represented by formula (4) that originates from a polymerizable unsaturated group may be bonded to groups other than the adjacent group represented by formula (4), but it is preferable that they be bonded to the adjacent group represented by formula (4).

[0064] The linear polysiloxane structure containing the constituent unit shown in formula (3) is linear in nature, with both ends not bonded to each other. That is, the polysiloxane skeleton in the linear polysiloxane compound does not form a cyclic structure. The groups bonded to both ends of the linear polysiloxane structure can be, independently, hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. Among these groups, the above R 1 The bases and -OR listed above a1 Examples of groups similar to those represented by the symbol are given.

[0065] The silicone particles of the present invention can be used in the form of non-conductive or conductive particles in applications such as conductive materials for liquid crystal display elements, spacers for liquid crystal display elements, fillers for liquid chromatography, lubricants for films, and toners for electrostatic image development. [Examples]

[0066] The present invention will be described in more detail below with reference to examples. The present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit described below, and all such modifications are included within the technical scope of the present invention.

[0067] The silicone particles obtained in the examples were measured by the following method.

[0068] (1) Observation of particle shape and measurement of the ratio of the diameter of the opening of the defect to the particle diameter. The particle shape was observed using a SEM (JEOL Ltd. JSM-6510, pressurized at 20kV, magnification 3000x, platinum sputtering). For each of the 100 particles, the particle diameter and the diameter of the opening of the defect were measured using calipers. The ratio of the opening diameter of the defect to the particle diameter was determined for each particle, and the arithmetic mean of these ratios was calculated.

[0069] (2) Measurement of the number-average particle diameter of the particles The dispersion was prepared as the measurement sample by adding 20 parts of a 1% aqueous solution of polyoxyethylene alkyl ether sulfate ammonium salt (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., "Hytenol® N-08"), an emulsifier, to 0.1 parts of particles and dispersing it with ultrasound for 10 minutes. The particle size (μm) of 30,000 particles was measured using a particle size distribution analyzer (manufactured by Beckman Coulter, "Coulter Multisizer III"), and the number-average particle size was determined.

[0070] Example 1: Preparation of silicone particles E1 In a four-necked flask equipped with a condenser, thermometer, and dropper port, 975 parts of deionized water, 235 parts of methanol, 2.0 parts of polyvinyl alcohol (Mitsubishi Chemical Corporation, "Gosenol GH-17R"), and 0.2 parts of 25% aqueous ammonia solution (Fujifilm Wako Co., Ltd.) were charged and maintained at 30°C. To this, 100 parts of 3-methacryloxypropylmethyldimethoxysilane (Shin-Etsu Chemical Co., Ltd., "KBM502", hereinafter "MPDMS"), a silane monomer with polymerizable unsaturated groups, were added dropwise, and the mixture was stirred at an internal temperature of 35°C for 90 minutes to carry out hydrolysis and condensation reactions of 3-methacryloxypropylmethyldimethoxysilane, thereby producing an emulsion of polysiloxane particles (polymerizable polysiloxane particles) containing methacryloxy groups.

[0071] Next, a solution was prepared by dissolving 1.3 parts of benzyldodecyldimethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) as a ring-opening polymerization agent in 400 parts of deionized water. To this solution, 50 parts of decane were added as solvent X, and the mixture was emulsified and dispersed to prepare an emulsion. One hour after the start of emulsification and dispersion, the obtained solvent X-containing emulsion was added to an emulsion of polysiloxane particles (seed particles), and further stirring was performed. One hour after the addition of the solvent X-containing emulsion, the mixture was sampled and observed under a microscope, confirming that the polysiloxane particles and solvent X were dispersed in a phase-separated state.

[0072] Next, 2.0 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., "V-65") were added to the reaction solution as a radical polymerization initiator. Radical polymerization was carried out by raising the temperature to 65°C under a nitrogen atmosphere and holding it at 65°C for 2 hours. After cooling the reaction solution, the resulting emulsion was subjected to solid-liquid separation, and the resulting cake was washed with deionized water and then methanol. After drying at 120°C under a nitrogen atmosphere for 2 hours, silicone particles E1 were obtained.

[0073] Example 2: Preparation of silicone particles E2 A four-necked flask equipped with a condenser, thermometer, and dropper port was charged with 974 parts of deionized water, 2.0 parts of polyvinyl alcohol (Mitsubishi Chemical Corporation, "Gosenol GH-17R"), and 0.2 parts of 25% aqueous ammonia solution (Fujifilm Wako Co., Ltd.), and maintained at 30°C. 3-methacryloxypropyltrimethoxy, a silane monomer with polymerizable unsaturated groups, was then added to the mixture and maintained at 30°C. 100 parts of silane (Shin-Etsu Chemical Co., Ltd., "KBM503", hereinafter "MPTMS") and 235 parts of methanol were added dropwise, and the mixture was stirred at an internal temperature of 35°C for 90 minutes to hydrolyze and condense 3-methacryloxypropyltrimethoxysilane, thereby producing an emulsion of polysiloxane particles (polymerizable polysiloxane particles) having a methacryloxy group. Next, 50 parts of decane were added as solvent X, and the mixture was stirred for 30 minutes. Then, 2.0 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd., "V-65") were added to the reaction solution as a radical polymerization initiator, and the temperature was raised to 65°C under a nitrogen atmosphere and held at 65°C for 2 hours to carry out radical polymerization. After cooling the reaction solution, the obtained emulsion was separated into solid and liquid components, and the resulting cake was washed with deionized water and then methanol. After drying under a nitrogen atmosphere at 120°C for 2 hours, silicone particles E2 were obtained.

[0074] Comparative Example 1: Preparation of Silicone Particle No. C1 In a four-necked flask equipped with a condenser, thermometer, and dropper port, 974 parts of deionized water, 2.0 parts of polyvinyl alcohol (Mitsubishi Chemical Corporation, "Gosenol GH-17R"), and 0.2 parts of 25% aqueous ammonia solution (Fujifilm Wako Co., Ltd.) were charged and maintained at 30°C. To this, 100 parts of 3-methacryloxypropylmethyldimethoxysilane (Shin-Etsu Chemical Co., Ltd., "KBM502"), a silane monomer with polymerizable unsaturated groups, and 235 parts of methanol were added dropwise. The mixture was stirred at an internal temperature of 35°C for 90 minutes to carry out hydrolysis and condensation reactions of 3-methacryloxypropylmethyldimethoxysilane, thereby producing an emulsion of polysiloxane particles (polymerizable polysiloxane particles) containing methacryloxy groups. Next, 5.2 parts of benzyldodecyldimethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the reaction solution as a ring-opening polymerization agent, and the temperature was raised to 60°C and held at 60°C for 3 hours to carry out anionic ring-opening polymerization. Then, 2.0 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., "V-65") was added to the reaction solution as a radical polymerization initiator, and the temperature was raised to 65°C under a nitrogen atmosphere and held at 65°C for 2 hours to carry out radical polymerization. After cooling the reaction solution, the resulting emulsion was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and then methanol, and then dried under a nitrogen atmosphere at 120°C for 2 hours to obtain silicone particles C1.

[0075] The results measured using the methods described in (1) and (2) above are shown in Table 1 and Figure 1.

[0076] [Table 1]

[0077] Figure 1 shows the results of electron microscope observation of silicone particle E1, and Figure 2 shows the results of electron microscope observation of silicone particle E2. Figures 1 and 2 show that silicone particles E1 and E2 have defects on or inside the particle surface, and the shape of the defect is at least a part of the shape of a sphere.

Claims

1. A step of hydrolyzing and condensing a silane monomer having polymerizable unsaturated groups in solvent A containing water to obtain a dispersion of a polysiloxane compound having polymerizable unsaturated groups, A step of mixing solvent X, which is immiscible with solvent A and also immiscible with the polysiloxane compound, with the dispersion; A method for producing silicone particles, comprising the step of radical polymerization of the polysiloxane compound.

2. The method for producing the polysiloxane compound according to claim 1, wherein the polysiloxane compound is a chain-like polysiloxane compound.

3. The manufacturing method according to claim 1 or 2, wherein the solvent X is a hydrocarbon solvent.

4. Silicone particles having defects on the surface or inside the particle, The shape of the defect is a silicone particle that is at least a part of the shape of a sphere.

5. The silicone particle according to claim 4, wherein the silicone particle has a defect opening on the particle surface, and the diameter of the opening relative to the diameter of the silicone particle is greater than 0 and less than 1.

6. Silicone particles according to claim 4 or 5, wherein the number-average particle diameter is 1 to 9 μm.

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