Silicone composition and method for producing the same

Abstract

To provide a silicone composition having excellent handling properties and high tear strength after curing.SOLUTION: There is provided a silicone composition which comprises (A) 100 pts.mass of an organopolysiloxane having a viscosity at 25°C of 0.01 to 100 Pa s and two or more alkenyl groups bonded to a silicon atom in one molecule, (B) 10 to 500 pts.mass of hydrophobic silica particles having an average particle diameter in the range of 10 nm to 1000 nm, a hydrophobicity degree of 60% or more by the methanol titration method and an alkenyl group bonded to a silicon atom on the surface, (C) an organohydrogen polysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule in an amount so that hydrogen atoms bonded to silicon atoms in the component (C) is 0.4 to 5.0 times mole relative to the total alkenyl groups bonded to all silicon atoms in the composition, and (D) a platinum group metal-based catalyst.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Silicone rubber has excellent heat resistance, cold resistance, and electrical insulation, and is widely used in various industries such as electrical and electronics, automobiles, and construction. The siloxane polymer that forms silicone rubber has very small intermolecular forces, so silicone rubber formed by curing only the polymer becomes a rubber with very weak strength. When silicone rubber is used as an adhesive, sealing material, or potting material for parts that generate high heat, there is a problem that the silicone rubber material is stressed and cracked due to thermal expansion caused by the heat of the parts, so high mechanical strength is required. In addition, when used as a mold making material or a lens material for ultrasonic probes, it is used at room temperature, but both are subjected to stress during use, so high tear strength is required. This makes it a material with inadequate strength for practical use. To solve this problem, reinforcing silica such as fumed silica is usually blended with the aim of improving mechanical strength. Silicone compositions that blend reinforcing agents such as silica particles and silicone resins with the aim of improving mechanical strength have also been proposed (Patent Documents 1 and 2). However, when silica particles that have not been subjected to a hydrophobic treatment or that have not been sufficiently treated on the surface are used, the viscosity and thixotropy increase, the flowability decreases, and the handling is poor. In addition, when only silicone resin is used as a reinforcing agent, the degree of improvement in mechanical strength is low and sufficient strength cannot be obtained. In addition, silicone compositions with high transparency have been proposed by using sol-gel silica with a hydrophobic surface, but the mechanical strength is insufficient (Patent Documents 3 and 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-351901 A [Patent Document 2] JP 2013-64089 A [Patent Document 3] JP 2012-144595 A [Patent Document 4] JP 2019-1975 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for the development of a high-strength silicone rubber material that is easy to handle and does not crack even when subjected to stress.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a silicone composition that has excellent handleability (fluidity) and high tear strength after curing, and a method for producing the same. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides The following components (A) to (D): (A) an organopolysiloxane having a viscosity at 25°C of 0.01 to 100 Pa s and having two or more alkenyl groups bonded to silicon atoms per molecule: 100 parts by mass, (B) Hydrophobic silica particles having a volume-based median diameter in the range of 10 nm to 1,000 nm, a hydrophobicity degree of 60% or more according to a methanol titration method, and having alkenyl groups bonded to silicon atoms on the surface: 10 to 500 parts by mass, (C) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule: an amount such that the number of silicon-bonded hydrogen atoms in component (C) is 0.4 to 5.0 times the molar amount of all silicon-bonded alkenyl groups in the composition; and (D) a platinum group metal catalyst: an effective amount, The silicone composition comprises:

[0007] The silicone composition of the present invention has excellent handleability and exhibits high tear strength after curing.

[0008] At this time, the component (B) forms R on the silica surface. 2 SiO 3 / 2 Units (R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; and R A (a) R 3 (3-a) SiO 1 / 2 The unit (a is an integer from 1 to 3, and R A are the same or different, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms, R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms. Furthermore, R 3 3SiO 1 / 2 Units (R 3 are the same or different, substituted or unsubstituted monovalent hydrocarbon groups having 1 to 6 carbon atoms.

[0009] Component (B) containing such units has an improved degree of hydrophobicity and can be suitably used in the silicone composition of the present invention.

[0010] Furthermore, the volume-based median diameter of component (B) is preferably 10 nm to 200 nm.

[0011] A silicone composition containing such a component (B) has excellent handleability and exhibits high tear strength after curing.

[0012] Furthermore, the blending amount of the component (B) is preferably 100 to 300 parts by mass per 100 parts by mass of the component (A).

[0013] Such a silicone composition has excellent handleability and exhibits high tear strength after curing.

[0014] Furthermore, it is preferable that the composition contains 0.01 to 5.0 parts by mass of (E) a reaction inhibitor per 100 parts by mass of the component (A).

[0015] The silicone composition of the present invention may contain such a reaction inhibitor.

[0016] The present invention also provides a method for producing the above-mentioned silicone composition, the method comprising the steps of producing component (B) through the following steps including (α), (β), and (γ), and mixing at least component (B), components (A), (C), and (D): (α) a step of obtaining a dispersion of hydrophilic silica particles by hydrolyzing and condensing at least one of a tetrafunctional silane compound represented by the following general formula (i) and an alkyl silicate represented by the following general formula (ii) in a mixed liquid of a hydrophilic organic solvent and water in the presence of a basic substance: Si(OR 4 4(i) Si(OR 4 )3-(-SiO(OR 4 )2-) m -Si(OR 4 )3(ii) (In the formula, R 4 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. m is 1 to 100. (β) A step of adding at least one of a trifunctional silane compound represented by the following general formula (iii) and its (partial) hydrolysis condensate (partial hydrolysis condensate or hydrolysis condensate) to the obtained dispersion of hydrophilic silica particles to treat the surfaces of the hydrophilic silica particles, thereby obtaining a dispersion of silica particles which is an intermediate of the component (B): R 2 Si(OR 5 )3(iii) (In the formula, R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R 5 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. (γ) adding a surface treatment agent containing at least one of a silazane compound represented by the following general formula (iv) and a monofunctional silane compound represented by the following general formula (v) to the obtained dispersion liquid of silica particles, which are an intermediate of the component (B), to treat the surfaces of the silica particles, which are an intermediate of the component (B), thereby obtaining hydrophobic silica particles, which are the component (B), having alkenyl groups bonded to silicon atoms on their surfaces: R A (a) R 3 (3-a) SiNHSiR A (a) R 3 (3-a) (iv) R A (a) R 3 (3-a) SIX (v) (In the formula, a is an integer of 1 to 3, and R A are the same or different, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms; R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.

[0017] A production method including such steps can easily produce a silicone composition that is easy to handle and has high tear strength.

[0018] It is preferable that the surface treatment agent in step (γ) further contains at least one of a silazane compound represented by the following general formula (vi) and a monofunctional silane compound represented by the following general formula (vii). R 3 3SiNHSiR 3 3(vi) R 3 3SiX (vii) (In the formula, R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.

[0019] A production method including such a step can easily produce a silicone composition that has improved hydrophobicity in component (B) and is easier to handle. Effect of the Invention

[0020] As described above, the silicone composition of the present invention is excellent in handling and has high tear strength after curing. Such a silicone composition of the present invention can be used in applications that require fluidity, transparency, and high tear strength. For example, it can be used as a material that requires crack resistance, such as an adhesive or sealing material for heat generating components, or potting. It can also be used as a material that is used at room temperature, such as a molding material or ultrasonic probe material, but requires high tear strength. That is, when the silicone composition of the present invention is used, it has mechanical strength that can suppress cracks that may occur due to thermal stress or external stress after curing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] As described above, there is a need for a silicone composition that is easy to handle and has high tear strength after curing.

[0022] Means for Solving the Problems The present inventors have conducted extensive research in order to achieve the above-mentioned object, and as a result have discovered that by containing silica particles whose surfaces have been highly hydrophobized and which have alkenyl groups bonded to silicon atoms, a silicone composition can be obtained which is easy to handle and has high tear strength after curing, and have thus completed the present invention.

[0023] That is, the present invention provides the following components (A) to (D): (A) an organopolysiloxane having a viscosity at 25°C of 0.01 to 100 Pa s and having two or more alkenyl groups bonded to silicon atoms per molecule: 100 parts by mass, (B) Hydrophobic silica particles having a volume-based median diameter in the range of 10 nm to 1,000 nm, a hydrophobicity degree of 60% or more according to a methanol titration method, and having alkenyl groups bonded to silicon atoms on the surface: 10 to 500 parts by mass, (C) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule: an amount such that the number of silicon-bonded hydrogen atoms in component (D) is 0.4 to 5.0 times the molar amount of all silicon-bonded alkenyl groups in the composition; and (D) platinum group metal catalyst, The silicone composition comprises:

[0024] The present invention will be described in detail below, but the present invention is not limited thereto.

[0025] The silicone composition of the present invention contains (A) an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms per molecule, (B) hydrophobic silica particles having a volume-based median diameter in the range of 10 nm to 1,000 nm and a hydrophobicity degree of 60% or more as measured by methanol titration method, and having alkenyl groups bonded to silicon atoms on their surfaces, (C) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms per molecule, (D) a platinum group metal catalyst, and, if necessary, (E) a reaction inhibitor.

[0026] [Component (A)] Component (A) is an organopolysiloxane having a viscosity at 25°C of 0.01 to 100 Pa·s, preferably 0.03 to 10 Pa·s, and containing two or more alkenyl groups bonded to silicon atoms per molecule. If the viscosity at 25°C is less than 0.01 Pa·s, the mechanical strength of the cured product will be insufficient, and if it exceeds 100 Pa·s, the viscosity of the composition will be high and the flowability will be poor. Note that the viscosity referred to in the present invention is a value measured using a B-type rotational viscometer (hereinafter the same).

[0027] There are no particular limitations on the organopolysiloxane (A), so long as it satisfies the above-mentioned viscosity and alkenyl group content, and any known organopolysiloxane can be used. The structure may be either linear or branched, and the component (A) may be a mixture of two or more organopolysiloxanes having different viscosities.

[0028] The alkenyl group bonded to the silicon atom contained in the component (A) of the present invention preferably has 2 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, and examples thereof include vinyl groups, allyl groups, 1-butenyl groups, and 1-hexenyl groups. Among these, vinyl groups are preferred in terms of ease of synthesis and cost. The alkenyl groups may be present either at the terminals or in the middle of the molecular chain of the organopolysiloxane, but are preferably present only at both terminals in terms of flexibility.

[0029] The organic group other than the alkenyl group bonded to the silicon atom contained in the component (A) of the present invention is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Examples of such monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl; aryl groups such as phenyl; aralkyl groups such as 2-phenylethyl and 2-phenylpropyl; and halogen-substituted monovalent hydrocarbon groups in which some or all of the hydrogen atoms of these hydrocarbon groups have been substituted with halogen atoms such as chlorine, fluorine, and bromine, such as fluoromethyl, bromoethyl, chloromethyl, and 3,3,3-trifluoropropyl. Of these, it is preferable that 90 mol % or more of the groups be methyl groups in terms of ease of synthesis and cost.

[0030] [(B) component] Component (B) is a hydrophobic silica particle having an alkenyl group bonded to a silicon atom on the surface. By including component (B), the mechanical strength of the cured product can be increased while maintaining the fluidity of the composition.

[0031] The volume-based median diameter of component (B) is 10 to 1,000 nm, preferably 10 to 500 nm, and particularly preferably 10 to 200 nm. If the particle diameter is smaller than 10 nm, aggregation becomes severe, and fluidity and transparency are lost. If the particle diameter is larger than 1,000 nm, transparency is lost and the effect of improving mechanical strength is small. The volume-based median diameter can be determined as the particle diameter equivalent to 50% of the cumulative distribution when the particle size distribution is expressed as a cumulative distribution using a laser analysis scattering type particle size distribution measuring device.

[0032] The hydrophobicity of component (B) measured by methanol titration is 60% or more, preferably 64% or more. There is no particular upper limit to the hydrophobicity, but it is preferably 80% or less, more preferably 75% or less. Silica particles with a high hydrophobicity do not aggregate even when highly loaded in the composition, and can increase the mechanical strength of the cured product without impairing the flowability.

[0033] The degree of hydrophobicity can be determined by the following methanol titration method. (1) The sample is suspended in a specified amount of ion-exchanged water, and methanol is added dropwise while stirring. (2) Read the amount of the dropped sample when the entire amount of the sample is suspended in the ion-exchanged water. (3) The volume percentage calculated by [{amount of methanol dropped (mL)} / {amount of methanol dropped (mL) + amount of ion-exchanged water (mL)} × 100] is the degree of hydrophobicity.

[0034] The shape of the component (B) of the present invention is not particularly limited, but it is preferably spherical.

[0035] The blending amount of component (B) is 10 to 500 parts by mass, preferably 20 to 400 parts by mass, and more preferably 100 to 300 parts by mass, per 100 parts by mass of component (A). If it is less than 10 parts by mass, the effect of improving mechanical strength is small, and if it exceeds 500 parts by mass, the viscosity becomes too high and the flowability is poor.

[0036] In addition, component (B) is added to the silica surface by R 2 SiO 3 / 2 Units (R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; and R A (a) R 3 (3-a) SiO 1 / 2 The unit (a is an integer from 1 to 3, R A are the same or different, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms, R 3are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms. 3 3SiO 1 / 2 Units (R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms.

[0037] Such a component (B) is, for example, a hydrophilic silica particle obtained by hydrolysis and condensation of a tetrafunctional silane compound, an alkyl silicate, or a mixture thereof, and is provided with R 2 SiO 3 / 2 Units, then R A (a) R 3 (3-a) SiO 1 / 2 Units and R if necessary 3 3SiO 1 / 2 It can be obtained by introducing units by hydrolysis and condensation.

[0038] [Method of synthesizing component (B)] Specifically, the component (B) of the present invention is preferably synthesized through the following three steps. Step (α): Synthesis step of hydrophilic silica particles; Step (β): Surface hydrophobization step of hydrophilic silica particles; Step (γ): A step of subjecting the surface of the intermediate component (B) to hydrophobic treatment and introducing an alkenyl group.

[0039] Each step will be explained below in order. Step (α): Synthesis of hydrophilic silica particles This is a step of obtaining a dispersion of hydrophilic silica particles by hydrolyzing and condensing at least one of a tetrafunctional silane compound represented by the following general formula (i) and an alkyl silicate represented by the following general formula (ii) in a mixture of a hydrophilic organic solvent and water in the presence of a basic substance. Si(OR 4 4(i) Si(OR 4)3-(-SiO(OR 4 )2-) m -Si(OR 4 )3(ii) (In the formula, R 4 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. m is 1 to 100.

[0040] In the above general formulas (i) and (ii), R 4 R are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and particularly preferably 1 to 2 carbon atoms. 4 Examples of the monovalent hydrocarbon group represented by the formula (I) include alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group; and aryl groups such as a phenyl group. Of these, a methyl group, an ethyl group, a propyl group, or a butyl group is preferable, and a methyl group or an ethyl group is particularly preferable.

[0041] In the above general formula (ii), m is an integer of 1 to 100, preferably 1 to 50, and particularly preferably 1 to 25.

[0042] The tetrafunctional silane compound represented by the above general formula (i) may, for example, be tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, etc.; and tetraphenoxysilane, preferably tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane, particularly preferably tetramethoxysilane and tetraethoxysilane. The alkyl silicate represented by the general formula (ii) may, for example, be methyl silicate, ethyl silicate, etc., preferably methyl silicate.

[0043] These may be used alone or in combination of two or more.

[0044] The hydrophilic organic solvent used in step (α) is not particularly limited as long as it dissolves the tetrafunctional silane compound represented by general formula (i) or the alkyl silicate represented by general formula (ii) and water, and examples thereof include alcohols; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and cellosolve acetate; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane and tetrahydrofuran, and the like.Preferably, alcohols and cellosolves, and particularly preferably, alcohols.The alcohols include the alcohol represented by the following general formula (xv). R 6 OH (xv) (In the formula, R 6 is a monovalent hydrocarbon group having 1 to 6 carbon atoms.

[0045] In the above general formula (xv), R 6 R is a monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and particularly preferably 1 to 2 carbon atoms. 6 The monovalent hydrocarbon group represented by the formula (xv) may be, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group, preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, more preferably a methyl group or an ethyl group. The alcohol represented by the formula (xv) may be, for example, methanol, ethanol, propanol, isopropanol, or butanol, preferably methanol or ethanol. The more carbon atoms in the alcohol, the larger the particle size of the silica particles produced. Therefore, in order to obtain the desired small silica particles, methanol is preferred.

[0046] Examples of the basic substance used in step (α) include ammonia, dimethylamine, diethylamine, etc., preferably ammonia and diethylamine, and particularly preferably ammonia. These basic substances may be dissolved in a required amount in water, and then the resulting aqueous solution (basic) may be mixed with a hydrophilic organic solvent.

[0047] The amount of the basic substance used in step (α) is preferably 0.01 to 2 moles, more preferably 0.02 to 0.5 moles, and particularly preferably 0.04 to 0.12 moles, per mole of the total of the hydrocarbyloxy groups of the tetrafunctional silane compound represented by general formula (i) and / or the alkyl silicate represented by general formula (ii). At this time, the smaller the amount of the basic substance, the smaller the desired silica particles will be. The basic substance may also be added to the mixture of water and the hydrophilic organic solvent at the same time as the addition of the tetrafunctional silane compound and / or the alkyl silicate and the hydrophilic organic solvent.

[0048] The amount of water used in the above hydrolysis and condensation is preferably 0.5 to 5 moles, more preferably 0.6 to 2 moles, and particularly preferably 0.7 to 1 mole, per mole of the total of the hydrocarbyloxy groups of the tetrafunctional silane compound represented by formula (i) and / or the alkyl silicate represented by formula (ii). The ratio of water to the hydrophilic organic solvent is preferably 10 to 200 parts by mass of the hydrophilic organic solvent per 100 parts by mass of water.

[0049] The obtained dispersion containing hydrophilic silica particles may be used as is in step (β); however, it is preferable to convert the dispersion containing hydrophilic silica particles into an aqueous dispersion containing hydrophilic silica particles by adding water to the dispersion containing hydrophilic silica particles, evaporating off the hydrophilic organic solvent, and converting the dispersion into an aqueous dispersion, whereby the remaining alkoxy groups are hydrolyzed.

[0050] The dispersion medium of the silica particle dispersion can be changed to water, for example, by adding water to the dispersion and distilling off the hydrophilic organic solvent (repeated as necessary). The amount of water added at this time is preferably 50 to 200 parts by mass, particularly preferably 80 to 150 parts by mass, based on 100 parts by mass of the total of the hydrophilic organic solvent used and the amount of alcohol generated in the synthesis step of the hydrophilic silica particles.

[0051] Step (β): Surface treatment step for hydrophilic silica particles This is a step in which at least one of a trifunctional silane compound represented by the following general formula (iii) and its (partial) hydrolysis condensation product (partial hydrolysis condensation product or hydrolysis condensation product) is added to the dispersion of hydrophilic silica particles obtained in step (α) to treat the surfaces of the hydrophilic silica particles, thereby obtaining a dispersion of silica particles (hydrophobic silica particle intermediate), which is an intermediate of component (B). R 2 Si(OR 5 )3(iii) (In the formula, R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R 5 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms.

[0052] In the above general formula (iii), R 2 The monovalent hydrocarbon group represented by R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 3 carbon atoms, and particularly preferably 1 to 2 carbon atoms. 2 Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, butyl, and hexyl groups, preferably methyl, ethyl, n-propyl, or isopropyl, and more preferably methyl or ethyl. Some or all of the hydrogen atoms in these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine, chlorine, or bromine, and preferably fluorine-substituted alkyl groups.

[0053] In the above general formula (iii), R 5 The monovalent hydrocarbon groups represented by R are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, and particularly preferably 1 to 2 carbon atoms. 5 Examples of the alkyl group include an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group, of which a methyl group, an ethyl group, or a propyl group is preferred, and a methyl group or an ethyl group is particularly preferred.

[0054] Examples of the trifunctional silane compound represented by the general formula (iii) include unsubstituted or halogen-substituted trialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltrimethoxysilane, and heptadecafluorodecyltrimethoxysilane, and preferably methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane, and more preferably methyltrimethoxysilane and methyltriethoxysilane.

[0055] The amount of the trifunctional silane compound represented by formula (iii) added is preferably 0.001 to 1 mol, more preferably 0.01 to 0.4 mol, and particularly preferably 0.01 to 0.2 mol per mol of Si atoms in the hydrophilic silica particles used. If the amount added is 0.001 mol or more, the hydrophobicity of the resulting (B) component is increased, resulting in excellent dispersibility, and if it is 1 mol or less, the risk of aggregation of the (B) component can be suppressed.

[0056] Step (γ): Surface treatment of the intermediate component (B) and introduction of an alkenyl group A surface treatment agent containing at least one of a silazane compound represented by the following general formula (iv) and a monofunctional silane compound represented by the following general formula (v) is added to the obtained dispersion liquid of silica particles, which are an intermediate of component (B), to treat the surfaces of the silica particles, which are an intermediate of component (B), thereby obtaining hydrophobic silica particles, which are component (B), having alkenyl groups bonded to silicon atoms on their surfaces. This step converts the silanol groups remaining on the surfaces of the hydrophobic silica particle intermediate into triorganosilylated R A (a) R 3 (3-a) SiO 1 / 2 Units are introduced onto the surface. RA (a) R 3 (3-a) SiNHSiR A (a) R 3 (3-a) (iv) R A (a) R 3 (3-a) SiX (v) (In the formula, a is an integer of 1 to 3, and R A are the same or different substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms, R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.

[0057] In the above general formulas (iv) and (v), R A The alkenyl group represented by the formula (I) has 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 3-butenyl group, a 5-hexenyl group, etc. Among these, the vinyl group is particularly preferred from the standpoint of ease of synthesis and cost.

[0058] In the above general formulas (iv) and (v), R 3 The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms, and examples thereof preferably include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, etc., and particularly preferably a methyl group or an ethyl group. In addition, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, and a fluorine-substituted alkyl group is preferred.

[0059] In the above general formula (v), X is an OH group or a hydrolyzable group, and examples of the hydrolyzable group include a chlorine atom, an alkoxy group, an amino group, and an acyloxy group, and is preferably an alkoxy group or an amino group, more preferably an alkoxy group, and particularly preferably a methoxy group or an ethoxy group.

[0060] Examples of the silazane compound represented by the above general formula (iv) include hexavinyldisilazane, dimethyltetravinyldisilazane, and tetramethyldivinyldisilazane, with tetramethyldivinyldisilazane being preferred.

[0061] Examples of the monofunctional silane compound represented by general formula (v) include monosilanol compounds such as dimethylvinylsilanol and diethylvinylsilanol; monochlorosilanes such as dimethylvinylchlorosilane and diethylvinylchlorosilane; monoalkoxysilanes such as dimethylvinylmethoxysilane and dimethylvinylethoxysilane; monoaminosilanes such as dimethylvinylsilyldimethylamine and dimethylvinylsilyldiethylamine; and monoacyloxysilanes such as dimethylvinylacetoxysilane. Of these, dimethylvinylsilanol, dimethylvinylmethoxysilane, or dimethylvinylsilyldiethylamine is preferred, and dimethylvinylsilanol or dimethylvinylmethoxysilane is particularly preferred.

[0062] In step (γ), it is preferable that the surface treatment agent further contains at least one of a silazane compound represented by the following general formula (vi) and a monofunctional silane compound represented by the following general formula (vii). R 3 3SiNHSiR 3 3(vi) R 3 3SiX (vii) (In the formula, R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.

[0063] In the above general formulas (vi) and (vii), R 3The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms, and examples thereof preferably include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, etc., and particularly preferably a methyl group or an ethyl group. In addition, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, and a fluorine-substituted alkyl group is preferred.

[0064] The above X is an OH group or a hydrolyzable group, and examples of the hydrolyzable group include a chlorine atom, an alkoxy group, an amino group, and an acyloxy group, and is preferably an alkoxy group or an amino group, more preferably an alkoxy group, and particularly preferably a methoxy group or an ethoxy group.

[0065] Examples of the silazane compound represented by the general formula (vi) include hexamethyldisilazane and tetraethyldisilazane, with hexamethylsilazane being preferred.

[0066] Examples of the monofunctional silane compound represented by the general formula (vii) include monosilanol compounds such as trimethylsilanol and triethylsilanol; monochlorosilanes such as trimethylchlorosilane and triethylchlorosilane; monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane; monoaminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine; and monoacyloxysilanes such as trimethylacetoxysilane. Of these, trimethylsilanol, trimethylmethoxysilane, or trimethylsilyldiethylamine is preferred, and trimethylsilanol or trimethylmethoxysilane is particularly preferred.

[0067] The amount of the silazane compound and / or monofunctional silane compound used is preferably 0.1 to 0.5 mol, more preferably 0.2 to 0.4 mol, and particularly preferably 0.25 to 0.35 mol, relative to 1 mol of Si atom of the hydrophilic silica particles used. If the amount used is 0.1 mol or more, the hydrophobicity of the obtained hydrophobic silica particles will be high and the dispersibility will be excellent, and if the amount used is 0.5 mol or less, it is sufficient in consideration of costs, etc.

[0068] In order to convert the dispersion medium of the mixed solvent dispersion of the hydrophobic silica particle intermediate obtained in step (β) from a mixture of water or a hydrophilic organic solvent and an alcohol generated during hydrolysis to a ketone-based solvent, the dispersion can be converted by adding a ketone-based solvent to the dispersion and distilling off the water or the hydrophilic organic solvent and the alcohol mixture (repeating this operation as necessary). The amount of the ketone-based solvent added at this time is 50 to 500 parts by mass, preferably 100 to 300 parts by mass, per 100 parts by mass of the obtained hydrophobic silica particle intermediate. Specific examples of the ketone-based solvent used here include methyl ethyl ketone, methyl butyl ketone, acetylacetone, etc., and methyl isobutyl ketone is particularly preferred.

[0069] The component (B) obtained as described above can be dried in the usual manner, such as under normal pressure or reduced pressure, to obtain a powder.

[0070] [(C) component] Component (C) is an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms (Si-H groups) in one molecule. It acts as a crosslinking agent that crosslinks with the alkenyl groups in components (A) and (B) through a hydrosilylation reaction. Component (C) is not particularly limited as long as it satisfies the above amount of Si-H groups, but is preferably one represented by the following average composition formula (viii). R 7 a H b SiO (4-a-b) / 2 (viii) (In the formula, R 7each independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bonds, a is a number satisfying 0.7≦a≦2.1, b is a number satisfying 0.001≦b≦1.0, and a+b is a number satisfying 0.8≦a+b≦3.0.

[0071] In the above average composition formula (viii), R 7 Examples of unsubstituted or substituted monovalent hydrocarbon groups containing no aliphatic unsaturated bonds and represented by the formula (I) include monovalent hydrocarbon groups having preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Examples of such monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups; aryl groups such as phenyl groups; aralkyl groups such as 2-phenylethyl and 2-phenylpropyl groups; and halogen-substituted monovalent hydrocarbon groups in which some or all of the hydrogen atoms of these hydrocarbon groups have been substituted with halogen atoms such as chlorine, fluorine, and bromine, such as fluoromethyl, bromoethyl, chloromethyl, and 3,3,3-trifluoropropyl groups, and are preferably methyl or phenyl groups.

[0072] In the above average composition formula (viii), a is a number that satisfies 0.7 to 2.1, b is a number that satisfies 0.001 to 1.0, and a+b is a number that satisfies 0.8 to 3.0, and preferably, a is a number that satisfies 1.0 to 2.0, b is a number that satisfies 0.01 to 1.0, and a+b is a number that satisfies 1.1 to 2.6.

[0073] The hydrogen atoms bonded to silicon atoms (Si-H groups) contained in one molecule of component (C) may be located either at the molecular chain terminals or in the middle of the molecular chain, or may be located at both locations. The molecular structure of this organohydrogenpolysiloxane may be linear, cyclic, branched, or a three-dimensional network structure, and the number of silicon atoms (or degree of polymerization) in one molecule is preferably 2 to 400, more preferably 3 to 200, and particularly preferably 4 to 100.

[0074] The organohydrogenpolysiloxane of component (C) preferably has a viscosity at 25° C. of 1,000 mPa·s or less (typically 1 to 1,000 mPa·s), and more preferably 5 to 200 mPa·s.

[0075] Specific examples of the organohydrogenpolysiloxane of component (C) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(hydrogendimethylsiloxy)methylsilane, tris(hydrogendimethylsiloxy)phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane-dimethylsiloxane cyclic copolymer, methylhydrogenpolysiloxane capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both ends with trimethylsiloxy groups, dimethylpolysiloxane capped at both ends with dimethylhydrogensiloxy groups, Dimethylsiloxane-methylhydrogensiloxane copolymer, methylhydrogensiloxane-diphenylsiloxane copolymer with trimethylsiloxy groups at both ends, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer with trimethylsiloxy groups at both ends, methylhydrogensiloxane-methylphenylsiloxane-dimethylsiloxane copolymer with trimethylsiloxy groups at both ends, methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymer with dimethylhydrogensiloxy groups at both ends, methylhydrogensiloxane-dimethylsiloxane-methylphenylsiloxane copolymer with dimethylhydrogensiloxy groups at both ends, (CH3)2HSiO 1 / 2 Units and (CH3)3SiO 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)2HSiO units. 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)2HSiO units. 1 / 2 Units and SiO 4 / 2 Units and (C6H5)3SiO 1 / 2In addition, copolymers consisting of the following general formulas (ix) to (xiv): R 7 3SiO[SiR 7 (H)O] t SiR 7 3(ix) R 7 3SiO[SiR 7 (H)O] t [SiR 7 2O] u SiR 7 3(x) R 7 2(H)SiO[SiR 7 (H)O] t Si(H)R 7 2(xi) R 7 2(H)SiO[SiR 7 2O] u Si(H)R 7 2(xii) R 7 2(H)SiO[SiR 7 (H)O] t [SiR 7 2O]Si(H)R 7 2 (xiii) [SiR 7 (H)O] v (Cyclic form) (xiv) (In the formula, R 7 is the same as above, t and u are integers of 1 to 100, preferably 2 to 25, and v is an integer of 4 to 8. Examples include those represented by the following formula:

[0076] The component (C) may use either a single compound, or a combination of two or more different compounds.

[0077] The amount of component (C) is such that the hydrogen atoms bonded to silicon atoms (Si-H groups) in component (C) are 0.4 to 5.0 times by mole, preferably 0.5 to 5.0 times by mole, and more preferably 0.7 to 3.5 times by mole, relative to the total of all alkenyl groups bonded to silicon atoms in the composition, i.e., in components (A) and (B), etc. If the amount is less than 0.4 times by mole or more than 5.0 times by mole, the crosslinking balance will be inappropriate, and a cured product with the desired high tear strength will not be obtained.

[0078] [(D) component] Component (D) is a platinum group metal catalyst. The platinum group metal catalyst may be any catalyst that promotes the addition reaction between the alkenyl group in component (A) or component (B) and the Si-H group in component (C), and may be any catalyst known in the art. Among these, catalysts selected from platinum and platinum compounds are preferred.

[0079] Examples of such catalysts include platinum group metals such as platinum (including platinum black), rhodium, and palladium; chlorides such as H2PtCl4·nH2O, H2PtCl6·nH2O, NaHPtCl6·nH2O, KHPtCl6·nH2O, Na2PtCl6·nH2O, K2PtCl4·nH2O, PtCl4·nH2O, PtCl2, and Na2HPtCl4·nH2O (wherein n is an integer of 0 to 6, and preferably 0 or 6); Examples of such catalysts include platinum, chloroplatinic acid and chloroplatinic acid salts, alcohol-modified chloroplatinic acid, complexes of chloroplatinic acid and olefins, platinum black, platinum group metals such as palladium supported on carriers such as alumina, silica, and carbon, rhodium-olefin complexes, chlorotris(triphenylphosphine)rhodium (Wilkinson's catalyst), complexes of platinum chloride, chloroplatinic acid or chloroplatinic acid salts with vinyl group-containing siloxanes, etc. These platinum group metal catalysts may be used alone or in combination of two or more.

[0080] The amount of the (D) component is not particularly limited as long as it is an effective amount as a catalyst, and is an amount that can promote the reaction of the (A) and (B) components with the (C) component, and may be appropriately adjusted according to the desired curing speed. The amount is preferably 0.1 to 7,000 ppm, more preferably 1 to 6,000 ppm, based on the mass of the (A) component, calculated as platinum group metal atoms. If the amount of the (D) component is 0.1 ppm or more, the effect as a catalyst works properly, and if the cost and the like are taken into consideration, it is sufficient if the amount is 7,000 ppm or less.

[0081] [(E) component] The silicone composition of the present invention may further contain a reaction inhibitor as component (E). The reaction inhibitor can suppress the progress of the curing reaction at room temperature and extend the shelf life and pot life. The reaction inhibitor is not particularly limited as long as it can suppress the catalytic activity of component (D), and known reaction inhibitors can be used. Examples of the reaction inhibitor include acetylene compounds such as 1-ethynyl-1-cyclohexanol and 3-butyn-1-ol, various nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds. Among them, acetylene alcohols that are not corrosive to metals are preferred.

[0082] The amount of the (E) component is 0.01 to 5 parts by mass, preferably 0.05 to 1 part by mass, based on 100 parts by mass of the (A) component. If the amount of the reaction inhibitor is 0.01 parts by mass or more, sufficient shelf life and pot life are obtained, and if the amount of the reaction inhibitor is 5 parts by mass or less, the curability of the composition is not reduced. The reaction inhibitor may be diluted with an organic solvent such as toluene, xylene, or isopropyl alcohol to improve dispersibility in the silicone resin.

[0083] [Other ingredients] In addition to the above components (A) to (E), the silicone composition of the present invention may contain known additives as necessary. Examples of such additives include silane coupling agents, silicone resins, silicone / non-silicone adhesive aids, hindered phenol antioxidants, reinforcing and non-reinforcing fillers such as calcium carbonate, and polyethers as thixotropy improvers. Furthermore, colorants such as pigments and dyes may be added as necessary.

[0084] [Method of producing silicone composition] The method for producing the silicone composition of the present invention is not particularly limited, and any conventionally known method can be used. That is, the silicone composition of the present invention can be obtained by mixing the components (A) to (D) and, if necessary, other components.

[0085] The method for producing the silicone composition of the present invention particularly preferably comprises a step of producing component (B) through steps including the following (α), (β), and (γ), and a step of mixing at least component (B), components (A), (C), and (D). (α) a step of obtaining a dispersion of hydrophilic silica particles by hydrolyzing and condensing at least one of a tetrafunctional silane compound represented by the following general formula (i) and an alkyl silicate represented by the following general formula (ii) in a mixed liquid of a hydrophilic organic solvent and water in the presence of a basic substance: Si(OR 4 4(i) Si(OR 4 )3-(-SiO(OR 4 )2-) m -Si(OR 4 )3(ii) (In the formula, R 4 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. m is 1 to 100. (β) A step of adding at least one of a trifunctional silane compound represented by the following general formula (iii) and its (partial) hydrolysis condensate (partial hydrolysis condensate or hydrolysis condensate) to the obtained dispersion of hydrophilic silica particles to treat the surfaces of the hydrophilic silica particles, thereby obtaining a dispersion of silica particles which is an intermediate of the component (B): R 2 Si(OR 5 )3(iii) (In the formula, R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R 5 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. (γ) a step of adding at least one of a silazane compound represented by the following general formula (iv) and a monofunctional silane compound represented by the following general formula (v) to the obtained dispersion liquid of silica particles, which is an intermediate of component (B), to treat the surfaces of the silica particles, which are an intermediate of component (B), thereby obtaining hydrophobic silica particles, which are component (B), having alkenyl groups bonded to silicon atoms on the surfaces thereof: R A (a) R 3 (3-a) SiNHSiR A (a) R 3 (3-a) (iv) R A (a) R 3 (3-a) SIX (v) (In the formula, a is an integer of 1 to 3, and R A are the same or different, substituted or unsubstituted alkenyl groups having 2 to 6 carbon atoms; R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.

[0086] The detailed production method of component (B) is as described above and will not be described here.

[0087] The process for mixing the components (A) to (D) is not particularly limited. For example, a one-liquid type composition can be stored for a long period of time by refrigeration or freezing, and a two-liquid type composition can be stored for a long period of time at room temperature.

[0088] A one-liquid type composition can be obtained, for example, by placing components (A) and (B) in a Gate Mixer (manufactured by Inoue Seisakusho Co., Ltd., product name: Planetary Mixer), heating and mixing for 3 hours at 150° C. After cooling the mixture, component (E) is added and mixed at room temperature for 30 minutes, and then components (C) and (D) are added and mixed at room temperature for 30 minutes.

[0089] The two-liquid type composition can be composed of any combination, so long as the combination of components (A), (C), and (D) and the combination of components (B), (C), and (D) do not coexist. For example, components (A) and (B) are placed in a gate mixer, heated and mixed at 150°C for 3 hours, and after cooling, component (D) is added and mixed at room temperature for 30 minutes. The resulting composition is designated as material A, and components (A), (C), and (E) are placed in a gate mixer, mixed at room temperature for 1 hour, and the resulting composition is designated as material B, to obtain a two-liquid type composition of materials A and B.

[0090] The viscosity of the silicone composition of the present invention at 25°C is preferably 0.1 to 100 Pa·s, and more preferably 1 to 50 Pa·s. If the viscosity at 25°C is 0.1 Pa·s or more, the desired mechanical strength can be obtained, and if it is 100 Pa·s or less, excellent handleability can be obtained. The viscosity is measured using a B-type rotational viscometer.

[0091] The curing conditions of the silicone composition are not particularly limited, and can be the same as those of known curable silicone compositions. The silicone composition can be cured at room temperature, but may also be cured by heating, preferably at a temperature of 20°C to 180°C, more preferably 50 to 150°C, for preferably 0.1 to 3 hours, more preferably 0.5 to 2 hours.

[0092] The cured product of the silicone composition of the present invention preferably has a tear strength in accordance with JIS K 6252-1:2015 of 15 kN / m or more, and more preferably 20 kN / m or more.

[0093] According to the present invention, the silicone composition has high handleability and high tear strength after curing. The silicone composition of the present invention can be used in applications where high tear strength is required because cracks may occur due to thermal stress or external stress after curing. For example, it can be used as an adhesive, sealant, or potting agent that is used for heat-generating members and requires crack resistance. It can also be used as a molding material or ultrasonic probe lens material that generates high external stress. That is, when the silicone composition of the present invention is used as an adhesive, sealant, or protective potting material around heat-generating members, or as a molding material or ultrasonic probe lens material, it has mechanical strength that can suppress cracks that may occur due to thermal stress or external stress after curing. EXAMPLES

[0094] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Each component used in the examples and comparative examples is described below.

[0095] Component (A) A-1: Organopolysiloxane represented by the following formula, having a viscosity of 5 Pa·s at 25°C [ka] A-2: Organopolysiloxane represented by the following formula, having a viscosity of 5 Pa·s at 25°C [ka]

[0096] (B) Component Hydrophobic silica particles (B-1), (B-2), (B-3), and (B-4) were prepared by the following procedure.

[0097] [Synthesis Example 1] Step (α): Synthesis of hydrophilic silica particles 623.7g of methanol, 41.4g of water, and 49.8g of 28% by mass ammonia water were mixed in a 3-liter glass reactor equipped with a stirrer, a dropping funnel, and a thermometer. The solution was adjusted to 35°C, and 1,163.7g of tetramethoxysilane and 418.4g of 5.4% ammonia water were added simultaneously while stirring, and dropped over 5 hours. After the dropping was completed, stirring was continued for another 0.5 hours to perform hydrolysis, thereby obtaining a suspension of hydrophilic spherical silica particles. An ester adapter and a cooling tube were attached to the glass reactor, and the reactor was heated to 60-70°C to distill off 649g of methanol, at which point 1,600g of water was added, and then the reactor was further heated to 70-90°C to distill off 160g of methanol, thereby obtaining an aqueous suspension of hydrophilic silica particles.

[0098] Step (β): Surface treatment step for hydrophilic silica particles To this aqueous suspension, 115.8 g of methyltrimethoxysilane (0.1 equivalent to SiO2) and 46.6 g of 5.4% aqueous ammonia were added dropwise over 0.5 hours at 25°C, and the mixture was then heated to 50°C and aged for 1 hour. After completing the reaction, the mixture was cooled to 25°C and the hydrophilic silica particle surfaces were treated.

[0099] Step (γ): Surface treatment of the intermediate component (C) and introduction of an alkenyl group After adding 1,000g of methyl isobutyl ketone to the dispersion thus obtained, the dispersion was heated to 80-115°C while maintaining the intense wave motion of the liquid interface, and 1,336g of a mixture of methanol and water was distilled off over 11 hours. A mixture of 3.6g of 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 353.8g of hexamethyldisilazane was added to the dispersion obtained at 25°C, and the dispersion was heated to 120°C and reacted for 3 hours, resulting in a dispersion of hydrophobic silica particles having alkenyl groups bonded to silicon atoms on the surface by surface treatment of the silica particles. Thereafter, the dispersion medium was distilled off under heating with an evaporator to obtain 477g of hydrophobic silica particles (B-1).

[0100] [Synthesis Example 2] 470 g of hydrophobic silica particles (B-2) were obtained in the same manner as in step (α) of Synthesis Example 1, except that 1,163.7 g of tetramethoxysilane was changed to 901.9 g of methyl silicate (Methyl silicate 51, manufactured by Colcoat Co., Ltd.).

[0101] [Comparative Synthesis Example 1] 470 g of hydrophobic silica particles (B-3) were obtained in the same manner as in Synthesis Example 1, except that in step (γ), a mixture of 3.6 g of 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 353.8 g of hexamethyldisilazane was changed to 357.4 g of hexamethyldisilazane.

[0102] [Comparative Synthesis Example 2] 300 g of hydrophobic silica particles (B-4) were obtained in the same manner as in Synthesis Example 1, except that in step (γ), a mixture of 3.6 g of 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 353.8 g of hexamethyldisilazane was changed to 119.1 g of hexamethyldisilazane.

[0103] [Measurement method] The obtained hydrophobic silica particles were measured according to the following measurement methods 1 and 2. The obtained results are shown in Table 1.

[0104] 1. Particle size measurement of hydrophobic silica particles (1) 0.1 g of sample was placed in a glass bottle, 20 g of methanol was added and stirred. (2) The mixture was dispersed in an ultrasonic dispersing device for 10 minutes to prepare a measurement sample. (3) The sample in (2) was measured using a laser analysis scattering type particle size distribution measuring device (NanotraC150, manufactured by Nikkiso Co., Ltd.), and the volume-based median diameter (particle diameter equivalent to 50% of the cumulative distribution when the particle size distribution is expressed as a cumulative distribution) was taken as the particle diameter.

[0105] 2. Measurement of hydrophobicity of hydrophobic silica particles (methanol titration method) (1) 0.2 mg of sample was weighed into a 500 mL Erlenmeyer flask. (2) 50 mL of ion-exchanged water was added to (1) and stirred with a stirrer. (3) While stirring, methanol was added dropwise from a burette, and the amount added was read when the entire amount of the sample was suspended in the ion-exchanged water. (4) The degree of hydrophobicity was calculated using the following formula. Hydrophobicity (%) = {amount of methanol dropped (mL)} / {amount of methanol dropped (mL) + amount of ion-exchanged water (mL)} x 100

[0106] [Table 1]

[0107] (C) Component C-1: Organohydrogensiloxane represented by the following formula: [ka] C-2: Organohydrogensiloxane represented by the following formula: [ka]

[0108] (D) Component D-1: Dimethylpolysiloxane solution of platinum-divinyltetramethyldisiloxane complex (Both ends are capped with dimethylvinylsilyl groups, dissolved in dimethylpolysiloxane with a viscosity of 0.6 Pa s at 25°C. Contains 1% by mass of platinum atoms.)

[0109] (E) Component E-1: 1-ethynyl-1-cyclohexanol

[0110] [Examples 1 to 3 and Comparative Examples 1 to 4] Preparation of Silicone Composition Components (A) and (B) were added to a gate mixer (Inoue Seisakusho Co., Ltd., 5L planetary mixer) in the amounts shown in Table 2, and heated and mixed at 150°C for 3 hours. Next, component (E) was added in the amount shown in Table 2, and mixed at 25°C for 30 minutes. Finally, components (C) and (D) were added in the amount shown in Table 2, and mixed at 25°C for 30 minutes until uniform. The physical properties of each of the obtained compositions were measured by the methods shown below. The results are also shown in Table 2.

[0111] 〔viscosity〕 The viscosity of each silicone composition at 25° C. was measured using a B-type viscometer.

[0112] [Tear strength] Each silicone composition was press-cured at 120° C. for 10 minutes and then heated for 20 minutes in an oven at 120° C. The tear strength of the resulting silicone sheet having a thickness of 2.0 mm was measured in accordance with JIS K 6252-1:2015.

[0113] [Hardness] Each silicone composition was press-cured at 120° C. for 10 minutes and then heated in an oven at 120° C. for 50 minutes. Three of the obtained silicone sheets, each 2.0 mm thick, were stacked, and the hardness was measured using a Type A durometer specified in JIS K 6253-3:2012.

[0114] [Tensile strength, elongation at break] Each silicone composition was press-cured at 120° C. for 10 minutes and then heated in an oven at 120° C. for 50 minutes. The tensile strength and elongation at break of the resulting silicone sheets having a thickness of 2.0 mm were measured in accordance with JIS K 6251:2017.

[0115] [Density after curing] Each silicone composition was press-cured at 120° C. for 10 minutes and then heated for 20 minutes in an oven at 120° C. The post-cured density of the resulting silicone sheets having a thickness of 2.0 mm was measured in accordance with JIS-K6249:2003.

[0116] [Table 2]

[0117] As shown in Table 2, the silicone compositions of the present invention prepared in Examples 1 to 3 had viscosities that allowed easy handling, and the cured products had tear strengths of 22 kN / m or greater in accordance with JIS K 6252-1:2015.

[0118] On the other hand, Comparative Example 1, which did not contain component (B), and Comparative Examples 2 and 3, which replaced component (B) with hydrophobic silica having no alkenyl groups on the surface, had insufficient tear strength and inferior mechanical properties. Also, Comparative Example 4, which used component (B) with insufficient hydrophobicity, had a composition with too high a viscosity to handle.

[0119] From the above, it is clear that the present invention provides a silicone composition that is easy to handle and has high tear strength after curing.

[0120] The present invention includes the following aspects. [1]: The following components (A) to (D); (A) an organopolysiloxane having a viscosity at 25°C of 0.01 to 100 Pa s and having two or more alkenyl groups bonded to silicon atoms per molecule: 100 parts by mass, (B) Hydrophobic silica particles having a volume-based median diameter in the range of 10 nm to 1,000 nm, a hydrophobicity degree of 60% or more according to a methanol titration method, and having alkenyl groups bonded to silicon atoms on the surface: 10 to 500 parts by mass, (C) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule: an amount such that the number of silicon-bonded hydrogen atoms in component (C) is 0.4 to 5.0 times the molar amount of all silicon-bonded alkenyl groups in the composition; and (D)Platinum group metal catalyst A silicone composition comprising: [2]: The component (B) is a compound having a R 2 SiO 3 / 2 Units (R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; and R A (a) R 3 (3-a) SiO 1 / 2 The unit (a is an integer from 1 to 3, R A are the same or different, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms, R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms. [3]: The component (B) further comprises R on the silica surface. 3 3SiO 1 / 2 Units (R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms. [4] The silicone composition according to any one of the above [1] to [3], wherein the volume-based median diameter of the component (B) is 10 nm to 200 nm. [5]: The silicone composition according to any one of the above [1] to [4], characterized in that the blending amount of the (B) component is 100 parts by mass to 300 parts by mass per 100 parts by mass of the (A) component. [6]: The silicone composition according to any one of the above [1] to [5], further comprising (E) a reaction inhibitor in an amount of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A). [7]: A method for producing a silicone composition according to any one of the above [1] to [6], comprising the steps of producing the component (B) through the steps including the following (α), (β), and (γ), and mixing at least the component (B) with the components (A), (C), and (D): (α) a step of obtaining a dispersion of hydrophilic silica particles by hydrolyzing and condensing at least one of a tetrafunctional silane compound represented by the following general formula (i) and an alkyl silicate represented by the following general formula (ii) in a mixed liquid of a hydrophilic organic solvent and water in the presence of a basic substance: Si(OR 4 4(i) Si(OR 4 )3-(-SiO(OR 4 )2-) m -Si(OR 4 )3(ii) (In the formula, R 4 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. m is 1 to 100. (β) A step of adding at least one of a trifunctional silane compound represented by the following general formula (iii) and its (partial) hydrolysis condensate to the obtained dispersion of hydrophilic silica particles to treat the surfaces of the hydrophilic silica particles, thereby obtaining a dispersion of silica particles which is an intermediate of the component (B): R 2 Si(OR 5 )3(iii) (In the formula, R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R 5 are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. (γ) a step of adding a surface treatment agent containing at least one of a silazane compound represented by the following general formula (iv) and a monofunctional silane compound represented by the following general formula (v) to the obtained dispersion liquid of silica particles, which is an intermediate of the component (B), to treat the surfaces of the silica particles, which are an intermediate of the component (B), thereby obtaining hydrophobic silica particles, which are the component (B), having alkenyl groups bonded to silicon atoms on the surfaces thereof: R A (a) R 3 (3-a) SiNHSiR A (a) R 3 (3-a) (iv) R A (a) R 3 (3-a) SiX (v) (In the formula, a is an integer of 1 to 3, and R A are the same or different, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms; R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group. [8]: The method for producing a silicone composition according to claim 7, wherein the surface treatment agent in step (γ) further contains at least one of a silazane compound represented by the following general formula (vi) and a monofunctional silane compound represented by the following general formula (vii): R 3 3SiNHSiR 3 3(vi) R 3 3SiX (vii) (In the formula, R 3 are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.

[0121] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention.

Claims

1. The following components (A) to (D): (A) an organopolysiloxane having a viscosity at 25° C. of 0.01 to 100 Pa s and having two or more alkenyl groups bonded to silicon atoms per molecule: 100 parts by mass, (B) Hydrophobic silica particles having a volume-based median diameter in the range of 10 nm to 1,000 nm, a hydrophobicity degree of 60% or more according to a methanol titration method, and having alkenyl groups bonded to silicon atoms on the surface: 10 to 500 parts by mass, (C) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule: an amount such that the number of silicon-bonded hydrogen atoms in component (C) is 0.4 to 5.0 times the molar amount of all silicon-bonded alkenyl groups in the composition; and (D) Platinum group metal catalyst A silicone composition comprising:

2. The component (B) is a compound having an R ２ SiO ３／２ Unit (R ２ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; and R Ａ （ａ） R ３ （３－ａ） SiO １／２ Units (a is an integer of 1 to 3, R Ａ are the same or different, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms; R ３ and each of the groups represented by the formula (1) is an alkyl group having 1 to 6 carbon atoms, ....

3. The component (B) further comprises R ３ ３ SiO １／２ Unit (R ３ and each of the groups represented by the formula (1) is an alkyl group having 1 to 6 carbon atoms, ....

4. 2. The silicone composition according to claim 1, wherein the volume-based median diameter of component (B) is 10 nm to 200 nm.

5. 2. The silicone composition according to claim 1, wherein the blending amount of the component (B) is 100 to 300 parts by mass per 100 parts by mass of the component (A).

6. 2. The silicone composition according to claim 1, further comprising: (E) 0.01 to 5.0 parts by mass of a reaction inhibitor per 100 parts by mass of component (A).

7. 7. A method for producing a silicone composition according to claim 1, comprising the steps of producing the component (B) through steps including the following (α), (β), and (γ), and mixing at least the component (B), and the components (A), (C), and (D): (α) a step of obtaining a dispersion of hydrophilic silica particles by hydrolyzing and condensing at least one of a tetrafunctional silane compound represented by the following general formula (i) and an alkyl silicate represented by the following general formula (ii) in a mixed liquid of a hydrophilic organic solvent and water in the presence of a basic substance: Si(OR ４ ) ４ (i) Si(OR ４ ) ３ -(-SiO(OR ４ ) ２ -) ｍ -Si(OR ４ ) ３ (ii) (In the formula, R ４ are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms; m is 1 to 100. (β) A step of adding at least one of a trifunctional silane compound represented by the following general formula (iii) and its (partial) hydrolysis condensate to the obtained dispersion of hydrophilic silica particles to treat the surfaces of the hydrophilic silica particles, thereby obtaining a dispersion of silica particles which is an intermediate of the component (B): R ２ Si (OR ５ ) ３ (iii) (In the formula, R ２ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R ５ are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms. (γ) adding a surface treatment agent containing at least one of a silazane compound represented by the following general formula (iv) and a monofunctional silane compound represented by the following general formula (v) to the obtained dispersion liquid of silica particles, which is an intermediate of the component (B), to treat the surfaces of the silica particles, which are an intermediate of the component (B), thereby obtaining hydrophobic silica particles, which are the component (B), having alkenyl groups bonded to silicon atoms on the surface thereof: R Ａ （ａ） R ３ （３－ａ） SiNHSiR Ａ （ａ） R ３ （３－ａ） (iv) R Ａ （ａ） R ３ （３－ａ） SiX (v) (In the formula, a is an integer from 1 to 3, and R Ａ are the same or different, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms; R ３ are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.

8. The method for producing a silicone composition according to claim 7, wherein the surface treatment agent in the step (γ) further comprises at least one of a silazane compound represented by the following general formula (vi) and a monofunctional silane compound represented by the following general formula (vii): R ３ ３ SiNHSiR ３ ３ (vi) R ３ ３ SiX (vii) (In the formula, R ３ are the same or different, substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, and X is an OH group or a hydrolyzable group.