Organopolysiloxane particles and method for producing organopolysiloxane particles

Abstract

The recovery percentage of these organopolysiloxane particles is 90% or more under measurement conditions in which a load is applied to the organopolysiloxane particles until the compression displacement of the organopolysiloxane particles reaches 20% of the particle diameter. These organopolysiloxane particles have a 10% compressive elastic modulus within the range 0.3 GPa to 1 GPa.

Description

Organopolysiloxane particles and method for producing organopolysiloxane particles

[0001] The present invention relates to organopolysiloxane particles and a method for producing organopolysiloxane particles.

[0002] Patent Document 1 discloses organopolysiloxane particles having a 10% compressive modulus of elasticity of 2 GPa or more.

[0003] Japanese Patent Application Laid-Open No. 2018-145320

[0004] Organopolysiloxane particles that have the ability to restore to their original shape when a compressive load is released may be required to have flexibility.

[0005] One aspect of the present invention is organopolysiloxane particles having a recovery rate of 90% or more under measurement conditions in which a load is applied to the organopolysiloxane particles until the compressive displacement of the organopolysiloxane particles becomes 20% of the particle diameter, and a 10% compressive elastic modulus in the range of 0.3 GPa or more and 1 GPa or less.

[0006] Another aspect of the present invention is a method for producing organopolysiloxane particles, wherein the organopolysiloxane particles have a recovery rate of 90% or more under measurement conditions in which a load is applied to the organopolysiloxane particles until a compressive displacement of the organopolysiloxane particles becomes 20% of a particle diameter, and the organopolysiloxane particles have a 10% compressive modulus of elasticity in the range of 0.3 GPa or more and 1 GPa or less, and the method includes a step of preparing a seed particle dispersion containing seed particles made of organopolysiloxane. a particle growth step of growing the seed particles in the seed particle dispersion using an alkoxysilane to obtain a grown particle dispersion containing grown particles; a solidified particle preparation step of solidifying and drying the grown particles to obtain solidified particles; and a firing step of firing the solidified particles to obtain the organopolysiloxane particles, wherein the alkoxysilane used in the particle growth step contains a first alkoxysilane represented by the following general formula (1) and a second alkoxysilane represented by the following general formula (2):

[0007] R１ Si(OR ２ ) ３ ... (1) R ３ ２ Si(OR ４ ) ２ ... (2) (In general formula (1) and general formula (2), R １ and R ３ is a non-hydrolyzable organic group selected from an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. At least one hydrogen atom in the alkyl group may be substituted with a methacryloyloxy group, an acryloyloxy group, or an epoxy group. ２ and R ４ is an alkyl group having 1 to 6 carbon atoms. ２ , multiple R ３ and multiple R ４ may be the same or different from each other.)

[0008] According to one aspect of the present invention, organopolysiloxane particles that have the restorability to return to their original shape when a compressive load is released can be made to exhibit flexibility.

[0009] An embodiment of the organopolysiloxane particles and a method for producing the organopolysiloxane particles will be described below. <Organopolysiloxane Particles> The organopolysiloxane particles are particles having a siloxane skeleton and a Si-C bond. The siloxane skeleton contains -Si-O-Si- as a repeating unit. The Si in the Si-C bond is the Si possessed by the siloxane skeleton. The organic component of the organopolysiloxane particles is bonded to Si. The organopolysiloxane particles do not contain any organic component not bonded to Si. "The organopolysiloxane particles do not contain any organic component not bonded to Si" means that the organopolysiloxane particles are substantially free of any organic component not bonded to Si, and it is acceptable for the organopolysiloxane particles to contain, for example, a trace amount of organic component not bonded to Si as an impurity. That is, the organopolysiloxane particles may contain organic components that are not bonded to Si at a concentration of, for example, 0.01% by mass or less, 0.001% by mass or less, or 0.0001% by mass or less.

[0010] The recovery rate of the organopolysiloxane particles is 90% or more under measurement conditions in which a load is applied to the organopolysiloxane particles until the compressive displacement of the organopolysiloxane particles is 20% of the particle diameter. The higher this recovery rate, the better the ability to return to the original shape when the compressive load is released. The recovery rate of the organopolysiloxane particles is preferably 93% or more, more preferably 95% or more, under measurement conditions in which a load is applied to the organopolysiloxane particles until the compressive displacement of the organopolysiloxane particles is 20% of the particle diameter.

[0011] The 10% compressive elastic modulus of the organopolysiloxane particles is in the range of 0.3 GPa or more and 1 GPa or less. The smaller the 10% compressive elastic modulus, the higher the flexibility of the organopolysiloxane particles. The 10% compressive elastic modulus of the organopolysiloxane particles is preferably 0.4 GPa or more, and more preferably 0.5 GPa or more.

[0012] The average particle size of the organopolysiloxane particles is preferably in the range of 0.5 μm or more and 200 μm or less, more preferably 3 μm or more, and even more preferably 7 μm or more, and more preferably 100 μm or less, and even more preferably 70 μm or less.

[0013] The coefficient of variation (CV value) in the particle size distribution of the organopolysiloxane particles is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0014] The coefficient of variation (CV value) is expressed by the following formula: CV value (%) = {standard deviation of particle diameter [μm] / average particle diameter [μm]} × 100 Applications of the organopolysiloxane particles include, for example, spacers for liquid crystal displays, spacers for EL displays, spacers for touch panels, spacers for maintaining a uniform distance between various substrates, core materials for conductive particles, core materials for fixed particles, etc.

[0015] For example, the conductive particles include organopolysiloxane particles and a conductive layer provided on the outer surface of the organopolysiloxane particles. Examples of materials for the conductive layer include metals, metal salts, and conductive resins. The adhesive particles include organopolysiloxane particles and a fixing layer provided on the outer surface of the organopolysiloxane particles. Examples of materials for the fixing layer include thermoplastic resins, thermosetting resins, and photocurable resins.

[0016] <Method for producing organopolysiloxane particles> Next, a method for producing the organopolysiloxane particles will be described. The method for producing the organopolysiloxane particles includes (A) a seed particle dispersion preparation step, (B) a particle growth step, (C) a solidified particle preparation step, and (D) a firing step.

[0017] <(A) Seed Particle Dispersion Preparation Step> In the seed particle dispersion preparation step, a seed particle dispersion containing seed particles made of organopolysiloxane is prepared. The seed particles have Si—C bonds and siloxane bonds and exist as droplets in the dispersion. The average particle diameter of the seed particles is, for example, in the range of 1 μm or more and 50 μm or less.

[0018] The seed particle dispersion liquid is obtained by hydrolyzing a raw material containing an alkoxysilane having a non-hydrolyzable organic group in an aqueous solvent, followed by condensation using a catalyst. The raw material for the seed particles preferably contains an alkoxysilane represented by the following general formula (a):

[0019] R ５ ｎ Si(OR ６ ) ４－ｎ ...(a) In the above general formula (a), R ５ is a non-hydrolyzable organic group selected from an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. At least one hydrogen atom in the alkyl group may be substituted with a methacryloyloxy group, an acryloyloxy group, or an epoxy group. ６ is an alkyl group having 1 to 6 carbon atoms, and n is 1 or 2. ６may be the same or different. When n is 2, multiple R ５ The alkoxysilanes may be the same or different. One or more alkoxysilanes may be used.

[0020] Examples of trialkoxysilanes (n=1) represented by the above general formula (a) include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0021] Examples of the dialkoxysilane (n=2) represented by the above general formula (a) include dimethyldimethoxysilane, dimethyldiethoxysilane, and diphenyldimethoxysilane.

[0022] As the raw material for the seed particle, a compound represented by the above general formula (a) and a tetraalkoxysilane in which n is 0 or a monoalkoxysilane in which n is 3 in the above general formula (a) can also be used. Examples of tetraalkoxysilanes in which n is 0 in the above general formula (a) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Examples of monoalkoxysilanes in which n is 3 in the above general formula (a) include trimethylmethoxysilane, trimethylethoxysilane, triisobutylmethoxysilane, diisobutylmethylmethoxysilane, and triethylmethoxysilane. The raw material for the seed particle may contain both a tetraalkoxysilane and a monoalkoxysilane.

[0023] The seed particle raw material preferably contains trialkoxysilane. The content of trialkoxysilane in the raw material is preferably 60 mol% or more, more preferably 80 mol% or more. From the viewpoint of excellent reactivity in hydrolysis and condensation, the trialkoxysilane preferably contains at least one of methyltrimethoxysilane and vinyltrimethoxysilane.

[0024] The seed particle dispersion can be prepared by stirring a raw material solution containing an alkoxysilane, a catalyst, and a solvent. The catalyst used to prepare the seed particle dispersion is preferably a basic catalyst, and ammonia or an amine can be used. Examples of amines include monomethylamine, dimethylamine, monoethylamine, diethylamine, and ethylenediamine. One or more catalysts can be used.

[0025] As the aqueous solvent for alkoxysilane, i.e., the aqueous dispersion medium for seed particles, a mixture of water and a water-miscible organic solvent, or water, can be used. Examples of the water-miscible organic solvent include lower alcohols, ketones, ethers, etc. Examples of the lower alcohols include methanol, ethanol, propanol, butanol, etc. Examples of the ketones include acetone, diethyl ketone, methyl ethyl ketone, etc. Examples of the ethers include diethyl ether, dipropyl ether, etc. One or more types of water-miscible organic solvents can be used.

[0026] <(B) Particle Growing Step> In the particle growing step, the seed particles in the seed particle dispersion are grown using alkoxysilane to obtain a grown particle dispersion containing grown particles.

[0027] The alkoxysilane used in the particle growth step contains a first alkoxysilane represented by the following general formula (1) and a second alkoxysilane represented by the following general formula (2): １ Si(OR ２ ) ３ ... (1) R ３ ２ Si(OR ４) ２ ... (2) In general formula (1) and general formula (2), R １ and R ３ is a non-hydrolyzable organic group selected from an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. At least one hydrogen atom in the alkyl group may be substituted with a methacryloyloxy group, an acryloyloxy group, or an epoxy group. ２ and R ４ is an alkyl group having 1 to 6 carbon atoms. ２ , multiple R ３ and multiple R ４ may be the same or different from each other.

[0028] Examples of the first alkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0029] The first alkoxysilane may be one or more types. The first alkoxysilane preferably includes methyltrimethoxysilane. Examples of the second alkoxysilane include dimethyldimethoxysilane, dimethyldiethoxysilane, and diphenyldimethoxysilane. The second alkoxysilane may be one or more types. The second alkoxysilane preferably includes dimethyldimethoxysilane.

[0030] When the mass of the first alkoxysilane is W1 and the mass of the second alkoxysilane is W2, the content of the second alkoxysilane can be expressed by the following formula (3): W2 / (W1+W2)×100[%] (3) The content of the second alkoxysilane is preferably in the range of 1% to 60%, more preferably in the range of 20% to 55%, and even more preferably in the range of 30% to 51%.

[0031] When the content of the second alkoxysilane is 1% or more, it is possible to easily reduce the 10% compressive modulus of the organopolysiloxane particles.When the content of the second alkoxysilane is 60% or less, it is possible to easily suppress a decrease in the recovery rate of the organopolysiloxane particles.

[0032] In the particle growth step, in addition to the first and second alkoxysilanes, a third alkoxysilane may also be used. Examples of the third alkoxysilane include monoalkoxysilane and tetraalkoxysilane.

[0033] The alkoxysilane used in the particle growth step may include an alkoxysilane represented by the general formula (a) above. ５ is a non-hydrolyzable organic group selected from an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. At least one hydrogen atom in the alkyl group may be substituted with a methacryloyloxy group, an acryloyloxy group, or an epoxy group. ６ is an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 3. When n is 2 or more, multiple R ５ When n is 2 or less, a plurality of hydrolyzable organic groups OR ６ may be the same or different from each other.

[0034] The total content of the first alkoxysilane and the second alkoxysilane in the alkoxysilane used in the particle growth step is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, when the total amount of alkoxysilane used in the particle growth step is taken as 100% by mass. In this case, the first alkoxysilane and the second alkoxysilane can be used to easily suppress a decrease in the recovery rate of the organopolysiloxane particles and easily reduce the 10% compressive modulus.

[0035] The content of the first alkoxysilane in the alkoxysilane used in the particle growth step is preferably in the range of 25% by mass or more and 99% by mass or less, more preferably in the range of 30% by mass or more and 80% by mass or less, and even more preferably in the range of 45% by mass or more and 70% by mass or less, when the total amount of the alkoxysilane is 100% by mass.

[0036] The content of the second alkoxysilane in the alkoxysilane used in the particle growth step is preferably in the range of 1% by mass or more and 60% by mass or less, more preferably in the range of 20% by mass or more and 55% by mass or less, and even more preferably in the range of 30% by mass or more and 51% by mass or less, when the total amount of the alkoxysilane is 100% by mass.

[0037] In the particle growth step, a particle growth solution is prepared by dissolving an alkoxysilane in an aqueous solvent. The aqueous solvent may be the same as that described in the (A) seed particle dispersion preparation step. The particle growth solution may also contain a stabilizer. The stabilizer, for example, increases the solubility of the alkoxysilane. Examples of the stabilizer include surfactants. Examples of the surfactant include anionic surfactants. The anionic surfactant preferably contains an alkyl sulfate having an alkyl group with 6 to 30 carbon atoms. Examples of the alkyl sulfate include potassium salts, sodium salts, and ammonium salts. The alkyl sulfate preferably contains at least one of sodium dodecyl sulfate and ammonium dodecyl sulfate.

[0038] In the particle growth step, the particle growth solution and the seed particle dispersion are mixed and then stirred to allow the seed particles to absorb the alkoxysilane. This results in a grown particle dispersion containing grown particles formed by growing the seed particles. The particle growth step may be repeated multiple times to further increase the particle diameter of the grown particles.

[0039] <(C) Solidified Particle Preparation Step> In the solidified particle preparation step, the grown particles are solidified and dried to obtain solidified particles. In the solidified particle preparation step, a catalyst is added to the grown particle dispersion to mature the grown particles. That is, a condensation reaction of the hydrolyzate of the alkoxysilane contained in the grown particles is promoted. This causes the grown particles in the grown particle dispersion to solidify, thereby obtaining a solidified particle dispersion. The solidified particles in the solidified particle dispersion are separated and washed as necessary to obtain wet solidified particles. The obtained solidified particles are dried to obtain dry solidified particles. The solidified particles are particles made of organopolysiloxane. The solidified particles have Si—C bonds.

[0040] <(D) Calcination Step> In the calcination step, the solidified particles are calcined to obtain the organopolysiloxane particles. The heating temperature in the calcination step is preferably in the range of 200°C or higher and 300°C or lower, more preferably in the range of 200°C or higher and 280°C or lower, and even more preferably in the range of 200°C or higher and 260°C or lower. The calcination device used in the calcination step is not particularly limited, and examples thereof include an electric furnace and a rotary kiln. The calcination step can be carried out, for example, under an air atmosphere, an inert gas atmosphere, or a mixed gas atmosphere of air and an inert gas. Examples of the inert gas include nitrogen and argon.

[0041] <Actions and Effects of the Present Embodiment> Next, the actions and effects of the present embodiment will be described. (1) The recovery rate of the organopolysiloxane particles is 90% or more under measurement conditions in which a load is applied to the organopolysiloxane particles until the compressive displacement of the organopolysiloxane particles is 20% of the particle diameter. The 10% compressive modulus of the organopolysiloxane particles is in the range of 0.3 GPa or more and 1 GPa or less. This configuration allows the organopolysiloxane particles, which have the ability to recover to their original shape when the compressive load is released, to exhibit flexibility.

[0042] As a result, for example, when the organopolysiloxane particles are used as spacers disposed between substrates, the flexibility of the organopolysiloxane particles can mitigate impacts on the substrates, and when a compressive load applied to the organopolysiloxane particles between the substrates is released, the restoring properties of the organopolysiloxane particles can stably maintain the gap between the substrates.

[0043] (2) The organopolysiloxane particles preferably have an average particle size in the range of 0.5 μm to 200 μm. The coefficient of variation (CV value) in the particle size distribution of the organopolysiloxane particles is preferably 5% or less. In this case, the organopolysiloxane particles can be suitably used for various applications, such as spacers.

[0044] (3) In the method for producing organopolysiloxane particles, the alkoxysilane used in the particle growth step contains a first alkoxysilane represented by the general formula (1) and a second alkoxysilane represented by the general formula (2). This method makes it possible to easily produce the organopolysiloxane particles.

[0045] More specifically, it is believed that the use of the first and second alkoxysilanes in the particle growth step results in a lower siloxane bond density in the solidified particles obtained in the solidified particle preparation step than when only the first alkoxysilane is used. This is believed to result in solidified particles having a flexible siloxane skeleton. By firing such solidified particles having a flexible siloxane skeleton in the firing step, it is possible to easily obtain organopolysiloxane particles having a recovery rate and 10% compressive modulus within the above ranges.

[0046] (4) In the particle growth step, the content of the second alkoxysilane represented by the formula (3) is preferably in the range of 1% to 60%. When this content is 1% or more, the 10% compressive modulus can be easily reduced.

[0047] (5) The total content of the first alkoxysilane and the second alkoxysilane in the alkoxysilane used in the particle growth step is preferably 80% by mass or more, when the total amount of the alkoxysilane is 100% by mass. In this case, it is presumed that the formation of a flexible siloxane skeleton by the first alkoxysilane and the second alkoxysilane can be promoted. In other words, it becomes possible to more easily produce the organopolysiloxane particles.

[0048] (6) The heating temperature in the baking step is preferably in the range of 200° C. to 300° C. In this case, the organopolysiloxane particles can be produced more easily.

[0049] <Modifications> The above embodiment may be modified as follows: The above embodiment and the following modifications may be combined and implemented within the scope of technical compatibility.

[0050] Colored particles can also be obtained by coloring the organopolysiloxane particles. That is, the colored particles contain organopolysiloxane particles and a colorant. Examples of colorants include dyes and pigments. The recovery rate of the colored particles is preferably 90% or more under measurement conditions in which a load is applied to the colored particles until the compressive displacement of the colored particles becomes 20% of the particle diameter. The 10% compressive elastic modulus of the colored particles is preferably in the range of 0.3 GPa or more and 1 GPa or less. The colored particles can be obtained, for example, by adding a colorant to a seed particle dispersion, a particle growth solution, a grown particle dispersion, or the like. Alternatively, the colored particles can be obtained by dyeing the organopolysiloxane particles with a dye.

[0051] Next, examples and comparative examples will be described. (Example 1) <(A) Seed particle dispersion liquid preparation step> 20 g of ion-exchanged water was added to 200 g of alkoxysilane, and the mixture was stirred at 35°C and about 200 rpm. After about 2 hours, a solution containing a hydrolyzate of alkoxysilane was prepared. Methyltrimethoxysilane (MTMS) was used as the alkoxysilane.

[0052] 1200g of ion-exchanged water and 1N NH ３ A catalyst solution was prepared by stirring 12 g of the aqueous solution at a rotation speed of 80 rpm. The catalyst solution was added to the solution containing the hydrolyzate, and then stirred for 30 minutes to obtain a seed particle dispersion.

[0053] <(B) Particle Growth Step> 120 g of the first alkoxysilane and 120 g of the second alkoxysilane were added to 1,170 g of ion-exchanged water, and the mixture was stirred at 200 rpm at 25° C. for about 1 hour to prepare a solution containing an alkoxysilane hydrolysate. 30 g of a 1% aqueous solution of ammonium dodecyl sulfate was added to this solution to obtain a particle growth solution.

[0054] Methyltrimethoxysilane (MTMS) was used as the first alkoxysilane. Dimethyldimethoxysilane (DMDMS) was used as the second alkoxysilane. The content of the second alkoxysilane represented by the above formula (3) is shown in the "Content of second alkoxysilane" column of Table 1.

[0055] 450 g of the seed particle dispersion was added to the particle growth solution, and the mixture was stirred at a rotation speed of about 80 rpm to grow the seed particles, thereby obtaining a grown particle dispersion containing grown particles formed from the seed particles.

[0056] <(C) Solidified Particle Preparation Step> After stirring the grown particle dispersion for approximately 8 hours, 100 g of 5% by mass ammonia water was added and heated to 70°C to mature the particles. This solidified the grown particles in the grown particle dispersion, preparing a solidified particle dispersion. Next, the solidified particle dispersion was separated into solid and liquid by decantation, and then washed three times with water and methanol. The wet solidified particles were then dried in dry air for approximately 8 hours and further dried by heating at 100°C to obtain solidified particles. The average particle size and CV value of the solidified particles were measured using the measurement method described below. The average particle size was 16.1 μm and the CV value was 1.3%.

[0057] <(D) Calcination Step> The solidified particles were calcined in an air atmosphere at a heating temperature of 260° C. for 5 hours using a muffle furnace, thereby obtaining organopolysiloxane particles of Example 1.

[0058] Example 2 In Example 2, organopolysiloxane particles were obtained in the same manner as in Example 1, except that the heating temperature in the baking step was changed to 200°C.

[0059] Example 3 In Example 3, organopolysiloxane particles were obtained in the same manner as in Example 1, except that the amount of DMDMS added in the particle growth step was changed from 120 g to 60 g and the heating temperature in the baking step was changed to 200°C.

[0060] Comparative Example 1 In Comparative Example 1, organopolysiloxane particles were obtained in the same manner as in Example 1, except that the particle growth step was carried out without adding DMDMS and the heating temperature in the baking step was changed to 280°C.

[0061] Comparative Example 2 In Comparative Example 2, organopolysiloxane particles were obtained in the same manner as in Example 1, except that the baking step was omitted.

[0062] (Measurement of average particle size and CV value) The average particle size of the seed particles in the seed particle dispersion obtained in the preparation step of each example was measured using a Coulter counter (manufactured by Beckman Coulter, Inc., product name: Multisizer 3). The average particle size of the seed particles in each example is shown in the "Average particle size of seed particles [μm]" column in Table 1.

[0063] The average particle size and standard deviation of the particle sizes of the organopolysiloxane particles of each example were measured using the Coulter Counter, and the CV value was calculated from the average particle size and standard deviation of the particle sizes. The average particle size and CV value of the organopolysiloxane particles of each example are shown in the "Average Particle Size" and "CV Value" columns of Table 1.

[0064] (Measurement of Recovery Rate) In measuring the recovery rate, a load test was first performed using a microcompression tester (Shimadzu Corporation, product name: Shimadzu Microcompression Tester, MCT-W200-J) to apply a load to the organopolysiloxane particles. The load test was performed under measurement conditions in which a load was applied to the organopolysiloxane particles until the compressive displacement of the organopolysiloxane particles was 20% of the particle diameter. That is, in the load test, when the particle diameter of the organopolysiloxane particles was taken as 100, the compressive displacement of the organopolysiloxane particles was taken as 20. The load at this time was taken as the reverse load value, and after holding at the reverse load value for 2 seconds, the load was unloaded until the load value for origin (0.02 gf) was reached. The loading rate and unloading rate were 1.422 mN / sec (0.145 gf / sec). The load-compression displacement at this time was measured, and the displacement from the origin load value to the reverse load value was defined as L1, and the displacement from the reverse load value to the origin load value after the reverse load was removed was defined as L2. These were then substituted into the following formula to determine the recovery rate.

[0065] Recovery rate [%] = {(L1 - L2) / L1} × 100 The recovery rate of the organopolysiloxane particles of each example is shown in the "Recovery rate" column of Table 1. (Measurement of 10% Compression Modulus) The 10% compression modulus of the organopolysiloxane particles can be determined based on the compression behavior of the organopolysiloxane particles. To measure the 10% compression modulus, first, a load is applied to the organopolysiloxane particles at a constant loading rate using a 50 μm diameter flat indenter in a microcompression tester (Shimadzu Corporation, product name: Shimadzu Microcompression Tester, MCT-W200-J) and observations are made. The 10% compression modulus E can be calculated from the displacement and load at 10% deformation using the following formula:

[0066] E = (3 / 2 １／２ ) × F × (1-K ２ ) x S －３／２ ×r －１／２ F: Load when organopolysiloxane particle is deformed by 10% K: Poisson's ratio of particle (constant: 0.38) S: Displacement when organopolysiloxane particle is deformed by 10% r: Radius of organopolysiloxane particle The 10% compressive elastic modulus of the organopolysiloxane particles of each example is shown in the "10% compressive elastic modulus" column of Table 1.

[0067]

[0068] As shown in Table 1, the organopolysiloxane particles of Examples 1 to 3 had recovery rates of 90% or more and 10% compressive moduli in the range of 0.3 GPa to 1 GPa. Therefore, in Examples 1 to 3, the organopolysiloxane particles have the recovery property to return to their original shape when the compressive load is released, and can exhibit flexibility.

Claims

1. An organopolysiloxane particle having a recovery rate of 90% or more under measurement conditions in which a load is applied to the organopolysiloxane particle until the compressive displacement of the organopolysiloxane particle becomes 20% of the particle diameter, and a 10% compressive elastic modulus in the range of 0.3 GPa or more and 1 GPa or less.

2. The organopolysiloxane particles according to claim 1, having an average particle size in the range of 0.5 μm or more and 200 μm or less, and a coefficient of variation (CV value) in the particle size distribution of 5% or less.

3. A method for producing organopolysiloxane particles, wherein the organopolysiloxane particles have a recovery rate of 90% or more under measurement conditions in which a load is applied to the organopolysiloxane particles until the compressive displacement of the organopolysiloxane particles becomes 20% of the particle diameter, and the organopolysiloxane particles have a 10% compressive elastic modulus in the range of 0.3 GPa or more and 1 GPa or less, the method comprising: a seed particle dispersion preparation step of preparing a seed particle dispersion containing seed particles made of organopolysiloxane; a particle growth step of growing the seed particles in the seed particle dispersion using an alkoxysilane to obtain a grown particle dispersion containing grown particles; a solidified particle preparation step of solidifying and drying the grown particles to obtain solidified particles; and a firing step of firing the solidified particles to obtain the organopolysiloxane particles, the alkoxysilane used in the particle growth step being A first alkoxysilane represented by the following general formula (1) and a second alkoxysilane represented by the following general formula (2): １ Si(OR ２ ) ３ ... (1) R ３ ２ Si(OR ４ ) ２ ... (2) (In general formula (1) and general formula (2), R １ and R ３ is a non-hydrolyzable organic group selected from an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. At least one hydrogen atom in the alkyl group may be substituted with a methacryloyloxy group, an acryloyloxy group, or an epoxy group. R ２ and R ４ is an alkyl group having 1 to 6 carbon atoms. ２ , multiple R ３ and multiple R ４ may be the same or different from each other.

4. The method for producing organopolysiloxane particles described in claim 3, wherein when the mass of the first alkoxysilane used in the particle growth process is W1 and the mass of the second alkoxysilane is W2, the content of the second alkoxysilane represented by the following formula (3): W2 / (W1+W2)×100[%]...(3) is within the range of 1% or more and 60% or less.

5. A method for producing organopolysiloxane particles as described in claim 4, wherein the total content of the first alkoxysilane and the second alkoxysilane in the alkoxysilane used in the particle growth process is 80 mass% or more when the total amount of the alkoxysilane is 100 mass%.

6. A method for producing organopolysiloxane particles described in any one of claims 3 to 5, wherein the heating temperature in the baking step is within the range of 200°C or higher and 300°C or lower.

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