Curable silicone composition

Abstract

To provide a curable silicone composition which exhibits good curability and has a sufficient pot life at normal temperature.SOLUTION: The curable silicone composition comprises at least (A) an organopolysiloxane having at least two alkenyl groups in one molecule, (B) an organopolysiloxane having at least two silicon atom-bonded hydrogen atoms in one molecule, (C) a catalyst for hydrosilylation reaction, and (D) a glycoluril compound represented by the general formula (where each R1 is independently a C1-6 alkyl group or a C3-6 alkenyl group, provided that at least one R1 is the alkenyl group; and each R2 is independently a hydrogen atom or a C1-6 alkyl group).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable silicone composition. [Background technology]

[0002] Curable silicone compositions that cure via an addition reaction in the presence of a hydrosilylation catalyst are widely used because they cure rapidly upon heating to form silicone cured products that have excellent heat resistance and weather resistance. However, such curable silicone compositions have the problem that attempts to accelerate their curing significantly shorten their pot life at room temperature.

[0003] For this reason, Patent Document 1 proposes controlling the cure initiation time and cure time of a curable silicone composition by incorporating a triazole-based compound, and Patent Document 2 proposes extending the pot life of a curable silicone composition by incorporating an acetylene alcohol derivative, but neither of these proposals achieves a balance between curability and pot life.

[0004] Meanwhile, Patent Document 3 proposes blending a glycoluril compound with a curable silicone composition containing a hydrosilylation catalyst to form a cured product with excellent transparency, heat resistance, sulfidation resistance, and adhesion. However, while Patent Document 3 describes blending 0.1 to 50 parts by mass of glycoluril compound per 100 parts by mass of alkenyl group-containing organopolysiloxane and silicon-bonded hydrogen atom-containing organopolysiloxane to achieve the above-mentioned objective, the examples also include blending 1 to 50 parts by mass, making it difficult to achieve both curability and pot life with such a composition. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-122271 [Patent Document 2] Special Publication No. 2019-504919 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-129274 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a curable silicone composition that has good curability and a sufficient pot life at room temperature. [Means for solving the problem]

[0007] The curable silicone composition of the present invention comprises: (A) 100 parts by mass of an organopolysiloxane having at least two alkenyl groups in one molecule, (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, in an amount such that there are 0.1 to 10 moles of silicon-bonded hydrogen atoms in this component per mole of total alkenyl groups in component (A); (C) a catalytic amount of a hydrosilylation catalyst, and (D) General formula: [ka] (In the formula, each R 1 are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 3 to 6 carbon atoms, provided that at least one R 1 is the alkenyl group, and each R 2 are independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 0.001 to 0.3 parts by mass of a glycoluril compound represented by the formula: The present invention is characterized by comprising at least the following:

[0008] In the present composition, component (B) is a compound represented by the formula: HRSiO 1 / 2(wherein each R is independently an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a fluoroalkyl group having 3 to 12 carbon atoms.) Component (B) is preferably an organopolysiloxane having a siloxane unit represented by the formula: HR2SiO 1 / 2 (wherein each R is independently the same group as defined above), and a siloxane unit represented by the formula: SiO 4 / 2 or an organopolysiloxane having a siloxane unit represented by the formula: HRSiO 1 / 2 and siloxane units represented by the formula: RSiO 3 / 2 (wherein each R is independently the same group as defined above) is preferred.

[0009] In the present composition, component (D) is a compound represented by the formula: [ka] It is preferable that the glycoluril compound is represented by the following formula:

[0010] The present composition preferably further contains (E) a hydrosilylation reaction inhibitor other than the aforementioned component (D). [Effects of the Invention]

[0011] The curable silicone composition of the present invention is characterized by its excellent curability and sufficient pot life at room temperature. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Curable Silicone Composition> Component (A) is the main component of the composition and is an organopolysiloxane containing at least two alkenyl groups per molecule. Examples of the alkenyl groups in component (A) include alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, and decenyl, with vinyl and hexenyl being preferred. Furthermore, examples of groups other than alkenyl groups that are bonded to silicon atoms in component (A) include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, and xylyl; aralkyl groups having 7 to 12 carbon atoms, such as benzyl and phenethyl; and fluoroalkyl groups having 3 to 12 carbon atoms, such as 3,3,3-trifluoropropyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, 6,6,6,5,5,4,4,3,3-nonafluorohexyl, and 7,7,7,6,6,5,5,4,4,3,3-undecafluoroheptyl, with methyl, phenyl, and 3,3,3-trifluoropropyl being preferred. To improve the oil resistance and cold resistance of the silicone cured product obtained by curing this composition, component (A) preferably contains a fluoroalkyl group. In this case, the proportion of fluoroalkyl groups in component (A) is not limited, but is preferably at least 5 mol%, 10 mol%, or 20 mol%, and at most 70 mol%, or at most 60 mol%, of all silicon-bonded organic groups, within the range between the above-mentioned lower and upper limits. Furthermore, small amounts of hydroxyl groups or alkoxy groups such as methoxy groups and ethoxy groups may be bonded to silicon atoms in component (A), provided that the objectives of the present invention are not impaired.

[0013] The molecular structure of component (A) is not limited, and examples include linear, branched, partially branched linear, and resinous. The viscosity of component (A) at 25°C is not limited, but it is preferably a liquid or crude rubber-like substance with a viscosity of at least 100 mPa·s at 25°C. If component (A) is liquid, its viscosity at 25°C is preferably within the range of 100 to 100,000 mPa·s, or 500 to 50,000 mPa·s. A viscosity of component (A) above the lower limit of this range improves the mechanical strength of the resulting silicone cured product, while a viscosity below the upper limit of this range improves the handling, workability, and fillability of the composition. The viscosity of component (A) at 25°C can be measured using a rotational viscometer in accordance with JIS K7117-1. On the other hand, when component (A) is in the form of a crude rubber, its Williams plasticity at 25°C as specified in JIS K 6249 is preferably in the range of 100 to 800, or in the range of 100 to 400.

[0014] Examples of such component (A) include dimethylpolysiloxanes terminally blocked with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally blocked with dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers terminally blocked with dimethylvinylsiloxy groups, methylvinylpolysiloxanes terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally blocked with silanol groups, and dimethylvinylpolysiloxanes terminally blocked with dimethylvinylsiloxane. and mixtures of two or more of these.

[0015] Component (B) is the crosslinking agent for the composition and is an organopolysiloxane having at least two silicon-bonded hydrogen atoms in each molecule. Examples of groups other than hydrogen atoms that are bonded to silicon atoms in component (B) include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, and xylyl; aralkyl groups having 7 to 12 carbon atoms, such as benzyl and phenethyl; and fluoroalkyl groups having 3 to 12 carbon atoms, such as 3,3,3-trifluoropropyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, 6,6,6,5,5,4,4,3,3-nonafluorohexyl, and 7,7,7,6,6,5,5,4,4,3,3-undecafluoroheptyl, with methyl, phenyl, and 3,3,3-trifluoropropyl being preferred. In order to improve the oil resistance and cold resistance of the silicone cured product obtained by curing this composition, if component (A) contains a fluoroalkyl group, component (B) preferably also contains a fluoroalkyl group. In this case, the proportion of fluoroalkyl groups in component (B) is not limited, but is preferably at least 5 mol%, 10 mol%, or 15 mol% of all silicon-bonded organic groups, while being no more than 70 mol%, 60 mol%, 50 mol%, or 40 mol%, within any range between the above-mentioned lower and upper limits. Furthermore, small amounts of hydroxyl groups or alkoxy groups such as methoxy groups or ethoxy groups may be bonded to silicon atoms in component (B) as long as the objectives of the present invention are not impaired.

[0016] The molecular structure of component (B) is not limited, and examples include linear, branched, partially branched linear, cyclic, and resinous. The viscosity of component (B) is not limited, but preferably has a kinematic viscosity of 1 to 10,000 mm at 25°C. 2 / s range, or 1 to 2,000 mm 2 / s. This is because when the viscosity of component (B) is at or above the lower limit of the above range, the mechanical strength of the resulting silicone cured product is improved, while when it is at or below the upper limit of the above range, the handling and filling properties of the composition are improved. The viscosity of component (B) can be measured using a viscometer in accordance with JIS K2283:2000 "Crude oil and petroleum products - Test method for kinematic viscosity and calculation method for viscosity index."

[0017] Examples of such component (B) include methylhydrogenpolysiloxanes terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminally blocked with trimethylsiloxy groups, dimethylpolysiloxanes terminally blocked with dimethylhydrogensiloxane, methylhydrogensiloxane-methyl(3,3,3-trifluoropropyl)siloxane copolymers terminally blocked with trimethylsiloxy groups, and dimethylsiloxane-methylhydrogensiloxane copolymers terminally blocked with trimethylsiloxy groups. Examples of suitable siloxanes include methyl(3,3,3-trifluoropropyl)polysiloxane copolymers, methyl(3,3,3-trifluoropropyl)polysiloxanes terminated at both ends with dimethylhydrogensiloxy groups, methyl(3,3,3-trifluoropropyl)polysiloxanes terminated at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane-methyl(3,3,3-trifluoropropyl)siloxane copolymers terminated at both molecular chain ends with dimethylhydrogensiloxy groups, and mixtures of two or more of these.

[0018] Generally, component (B) is a compound represented by the formula: HR2SiO 1 / 2 When an organopolysiloxane having a siloxane unit represented by the formula: HRSiO is used, the pot life of the curable silicone composition tends to be shortened. 1 / 2The pot life extension effect of adding component (D) is particularly pronounced when the organopolysiloxane has a siloxane unit represented by the formula: where R is independently an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a fluoroalkyl group having 3 to 12 carbon atoms, and examples thereof include the same groups as those described above.

[0019] Such component (B) includes compounds of the formula: HR2SiO 1 / 2 and siloxane units represented by the formula: SiO 4 / 2 and optionally having siloxane units represented by the formula: RSiO 2 / 2 Siloxane units represented by the formula: RSiO 3 / 2 Organopolysiloxanes which may contain siloxane units represented by the formula: HRSiO 1 / 2 and siloxane units represented by the formula: RSiO 3 / 2 and optionally having siloxane units represented by the formula: RSiO 2 / 2 Siloxane units represented by the formula: SiO 4 / 2 or an organopolysiloxane having a siloxane unit represented by the formula: HRSiO 1 / 2 and siloxane units represented by the formula: RSiO 2 / 2 and optionally having siloxane units represented by the formula: SiO 4 / 2 Siloxane units represented by the formula: RSiO 3 / 2 Specific examples include organopolysiloxanes that may contain siloxane units represented by the average unit formula: [HR2SiO 1 / 2 ] a (SiO 4 / 2 )1 Organopolysiloxanes represented by the average unit formula: [HR2SiO 1 / 2 ] b (RSiO 3 / 2 )1 Organopolysiloxanes represented by the general formula: HR2SiO(R2SiO) m SiR2H or an organopolysiloxane represented by the general formula: HR2SiO(R2SiO) m (HRSiO) n SiR2H Organopolysiloxanes represented by the following formula are exemplified.

[0020] In the above formula, R is the same as described above. Also, a is a number satisfying 0 < a ≤ 4, preferably a number satisfying 0.5 ≤ a ≤ 1.8. Also, b is a number satisfying 0 < b ≤ 3, preferably a number satisfying 0.5 ≤ b ≤ 1.8. Further, m and n are such that the kinematic viscosity of component (B) at 25°C is in the range of 1 to 10,000 mm 2 / s, or a positive number in the range of 1 to 2,000 mm 2 / s.

[0021] The content of component (B) is an amount within the range such that the silicon atom-bonded hydrogen atoms in this component are 0.1 to 10 moles with respect to a total of 1 mole of alkenyl groups in component (A), preferably an amount within the range of 0.5 to 10 moles, an amount within the range of 0.8 to 5 moles, and an amount within the range of 1.1 to 5 moles. This is because when the content of component (B) is not less than the lower limit of the above range, the composition cures sufficiently, while when it is not more than the upper limit of the above range, the heat resistance of the resulting silicone cured product is good.

[0022] Component (C) is a hydrosilylation catalyst for accelerating the curing of the composition. Examples of component (C) include platinum-based catalysts, palladium-based catalysts, and rhodium-based catalysts, with platinum-based catalysts being preferred. Examples of platinum-based catalysts include non-microencapsulated hydrosilylation catalysts such as chloroplatinic acid, chloroplatinic acid hexahydrate, platinum dichloride, alcohol solutions of chloroplatinic acid, platinum olefin complexes, platinum carbonyl complexes, platinum alkenylsiloxane complexes, platinum diketone complexes, and platinum olefin complexes, as well as microencapsulated hydrosilylation catalysts made of a resin with a softening point of 40 to 170°C, such as an acrylic resin, a polycarbonate resin, or a silicone resin, in which these platinum-based catalysts are dispersed or contained. In the platinum alkenylsiloxane complex, examples of the alkenylsiloxane include 1,3-divinyltetramethyldisiloxane, 1,1,3,3-tetravinyldimethyldisiloxane, and dimethylvinylsiloxy group-blocked methyl(3,3,3-trifluoropropyl)siloxane oligomer.

[0023] The content of component (C) is a catalytic amount that accelerates the curing of the composition, specifically an amount that results in the catalytic metal in component (C) being in the range of 0.1 to 1,000 ppm, 0.1 to 500 ppm, or 0.1 to 250 ppm by mass relative to the composition. This is because, when the content of component (C) is at or above the lower limit of the above range, the curing of the composition is sufficiently accelerated, while, when it is at or below the upper limit of the above range, the resulting silicone cured product is less likely to suffer from problems such as discoloration.

[0024] Component (D) is a glycoluril compound for adjusting the curability of the composition, and has the general formula: [ka] It is expressed as:

[0025] In the formula, each R 1 are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 3 to 6 carbon atoms. 1Examples of alkyl in R include methyl, ethyl, propyl, butyl, pentyl, and hexyl. 1 Examples of the alkenyl group include an allyl group, a butenyl group, a pentenyl group, and a hexenyl group. 1 is the alkenyl group, preferably an allyl group.

[0026] In addition, in the above formula, each R 2 are independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 2 Examples of the alkyl group include the same groups as the alkyl group of R1.

[0027] An example of such component (D) is a glycoluril compound represented by the following formula: [ka] [ka] [ka] [ka]

[0028] The content of component (D) in the composition is within the range of 0.001 to 0.3 parts by mass, preferably 0.001 to 0.2 parts by mass, per 100 parts by mass of component (A). When a microencapsulated hydrosilylation catalyst is used as component (C), the content is preferably within the range of 0.001 to 0.3 parts by mass or 0.001 to 0.2 parts by mass. When a non-microencapsulated hydrosilylation catalyst is used, the content is preferably within the range of 0.001 to 0.3 parts by mass, 0.001 to 0.2 parts by mass, or 0.001 to 0.15 parts by mass. This is because, when the content of component (D) is at or above the lower limit of the above range, the pot life of the composition at room temperature is sufficient. On the other hand, when the content of component (D) is at or below the upper limit of the above range, the composition exhibits good curability and the resulting silicone cured product exhibits a low compression set.

[0029] In addition to component (D), the present composition may also contain (E) a hydrosilylation reaction inhibitor other than component (D) in order to adjust the curing rate of the present composition. Examples of component (E) include alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol, 2-ethynylisopropanol, and 2-ethynylbutan-2-ol; silylated acetylene alcohols such as trimethyl(3,5-dimethyl-1-hexyn-3-oxy)silane, dimethylbis(3-methyl-1-butynoxy)silane, methylvinylbis(3-methyl-1-butyn-3-oxy)silane, and [(1,1-dimethyl-2-propynyl)oxy]trimethylsilane; 2-isobutyl-1-buten-3-yne, 3,5-dimethyl-3-hexen-1-yne, 3-methyl-3-penten-1-yne, 3-methyl-3-hexen-2-yne, and 3-methyl-3-hexen-2-yne. Examples include ene-yne compounds such as cyclohexene-1-yne, 1-ethynylcyclohexene, 3-ethyl-3-buten-1-yne, and 3-phenyl-3-buten-1-yne; unsaturated carboxylic acid esters such as diallyl maleate, dimethyl maleate, diethyl fumarate, diallyl fumarate, bis-2-methoxy-1-methylethyl maleate, monooctyl maleate, monoisooctyl maleate, monoallyl maleate, monomethyl maleate, monoethyl fumarate, monoallyl fumarate, and 2-methoxy-1-methylethyl maleate; alkenyl siloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and benzotriazole.

[0030] The content of component (E) is not limited, but is preferably 5 parts by mass or less, or 3 parts by mass or less, per 100 parts by mass of the total of components (A) and (B), while the lower limit is 0.01 parts by mass or more, or 0.1 parts by mass or more. The content of component (E) can be within any range combining the above upper and lower limits.

[0031] The present composition may contain a fine silica powder to improve the mechanical properties of the silicone cured product obtained by curing the composition. Examples of this fine silica powder include dry-process silica such as fumed silica and wet-process silica such as precipitated silica. Furthermore, finely powdered silica whose surface has been hydrophobized with an organosilicon compound such as organosilane, hexaorganodisilazane, diorganopolysiloxane, or diorganocyclopolysiloxane can also be used. The BET specific surface area of this fine silica powder is not limited, but is preferably 50 m. 2 / g~500m 2 / g range or 100-500m 2 / g.

[0032] There are no restrictions on the amount of silica fine powder contained, but in order to achieve good mechanical properties in the resulting silicone cured product, it is preferable that the amount be 5 parts by mass or more per 100 parts by mass of component (A), while in order to achieve good moldability in the composition, it is preferable that the amount be 200 parts by mass or less per 100 parts by mass of component (A).

[0033] Additionally, the present composition may contain various other additives that are commonly used in curable silicone compositions, provided that the purpose of the present invention is not impaired. These compounding agents include extender fillers such as diatomaceous earth, quartz powder, and calcium carbonate; thermal conductivity improvers such as alumina, zinc oxide, and boron nitride; flame retardant improvers such as magnesium hydroxide and aluminum hydroxide; carbon blacks such as acetylene black, furnace black, and channel black; pigments such as titanium oxide and red iron oxide; heat resistance improvers such as rare earth oxides, cerium silanolate, and cerium fatty acid salts; mold release agents such as stearic acid, zinc stearate, and calcium stearate, and fatty acids and their metal salts; dispersants such as alkoxysilanes, diphenylsilanediol, carbon functional silanes, and diorganosiloxane oligomers capped with silanol groups at both ends of the molecular chain; vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl ... Alkoxysilanes such as trimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane; alkenyl-containing diorganosiloxane oligomers with silanol groups blocked at both ends of the molecular chain, such as dimethylsiloxane-methylvinylsiloxane copolymer oligomers with silanol groups blocked at both ends of the molecular chain and methylvinylsiloxane oligomers with silanol groups blocked at both ends of the molecular chain; and 3-glycidoxypropyltrimethoxysilane and 2-(3,4 Examples of such an alkoxysilane include a reaction mixture of the above alkenyl-containing diorganosiloxane oligomer having silanol groups blocked at both molecular chain terminals with 3-methacryloxypropyltrimethoxysilane, a reaction mixture of the above epoxy-containing alkoxysilane with 3-aminopropyltriethoxysilane, and other adhesion promoters such as tris(3-trimethoxysilylpropyl)isocyanurate.

[0034] The method for curing the present composition is not limited, and can be mold molding, compression molding, transfer molding, injection molding, extrusion molding, calendar molding, etc. The curing method is also not limited, and can be selected from well-known curing methods such as steam vulcanization and hot air vulcanization. [Example]

[0035] The curable silicone composition of the present invention will be described in more detail using examples. However, the present invention is not limited to these examples. In the examples, properties such as viscosity and plasticity are values at room temperature (25°C) unless otherwise specified. Viscosity (Pa·s) is a value measured using a rotational viscometer in accordance with JIS K7117-1, and kinematic viscosity (mm 2 / s) was measured using an Ubbelohde viscometer in accordance with JIS Z8803. The curability and pot life (change in viscosity) of the curable silicone composition, as well as the physical properties of the resulting cured silicone product, were measured as follows.

[0036] <Curability> The curable silicone composition was measured for the following vulcanization properties using a Curastometer Model III (manufactured by JSR) in accordance with JIS K6300 at 130°C for 3 minutes. T10: The time from the beginning of heating required for 10% vulcanization to progress (i.e., until the torque reaches 10% of the maximum torque value MH on the vulcanization curve) (= vulcanization initiation point) T90: The time from the beginning of heating required for vulcanization to progress to 90% (i.e., until the torque reaches 10% of the maximum torque value MH on the vulcanization curve) (= optimal vulcanization point)

[0037] <Pot life (change in viscosity)> The initial viscosity (Pa s) of the curable silicone composition immediately after preparation at 25°C and the viscosity (Pa s) after standing at 25°C for a specified period of time were measured using a rotational rheometer (TA Instruments AR500 viscoelasticity measuring device) in accordance with the method specified in JIS K7117-2:1999. This measurement was carried out using a 20 mm diameter, 2° angle cone plate at a shear rate of 10.0 (S -1 ) was decided.

[0038] <Hardness> The test was conducted in accordance with the test method using a Type A hardness tester specified in JIS K6253, and three 2 mm thick test pieces were stacked on top of each other.

[0039] <Compression set rate> According to the method specified in JIS K6262, the compression set rate was measured after 22 hours under conditions of 180°C and 25% compression.

[0040] <Examples 1-14, Comparative Examples 1-6> The following components were mixed uniformly to prepare curable silicone compositions as shown in Table 1-3. In the table, SiH / Vi indicates the number of moles of silicon-bonded hydrogen atoms in component (B) per mole of alkenyl groups in component (A).

[0041] The following components were used as component (A): (a-1): Dimethylpolysiloxane with a viscosity of 10,000 mPa·s and terminated at both ends with dimethylvinylsiloxy groups (vinyl group content = approximately 0.13% by mass) (a-2): Dimethylpolysiloxane with a viscosity of 40,000 mPa·s and terminated at both ends with dimethylvinylsiloxy groups (vinyl group content = approximately 0.09% by mass) (a-3): Dimethylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups capped at both ends of the molecular chain, with a viscosity of 40,000 mPa·s (vinyl group content: approximately 0.13% by mass)

[0042] The following components were used as component (B): (b-1):Kinematic viscosity 25mm 2 Average unit formula for / s: [H(CH3)2SiO 1 / 2 ] 1.6 (SiO 4 / 2 )1 (content of silicon-bonded hydrogen atoms = approximately 0.97% by mass) (b-2):Kinematic viscosity 10mm 2 / s, formula: H(CH3)2SiO 1 / 2 Siloxane units represented by the formula: (CH3)2SiO 2 / 2 and siloxane units represented by the formula: H(CH3)SiO 2 / 2 Dimethylsiloxane-methylhydrogensiloxane copolymer (silicon-bonded hydrogen atom content = approx. 0.39% by mass) terminated at both molecular chain ends with dimethylhydrogensiloxy groups and consisting of siloxane units represented by the formula: (b-3):Kinematic viscosity 5mm 2 / s, formula: (CH3)3SiO 1 / 2 Siloxane units represented by the formula: (CH3)2SiO 2 / 2 and siloxane units represented by the formula: H(CH3)SiO 2 / 2 Dimethylsiloxane-methylhydrogensiloxane copolymer (silicon-bonded hydrogen atom content = approx. 0.77% by mass) terminated at both ends of the molecular chain by trimethylsiloxy groups and consisting of siloxane units represented by the formula: (b-4):Kinematic viscosity 10mm 2 / s, formula: H(CH3)2SiO 1 / 2 and siloxane units represented by the formula: (CH3)2SiO 2 / 2 Dimethylpolysiloxane (content of silicon-bonded hydrogen atoms = approximately 0.16% by mass) terminated at both molecular chain ends with dimethylhydrogensiloxy groups and consisting of siloxane units represented by the formula: (b-5): Kinematic viscosity 15mm 2 / s, formula: (CH3)3SiO 1 / 2 Siloxane units represented by the formula: (CH3)2SiO 2 / 2 Siloxane units represented by the formula: H(CH3)SiO 2 / 2 and siloxane units represented by the formula: CH3SiO 3 / 2A branched-chain dimethylsiloxane-methylhydrogensiloxane copolymer (silicon-bonded hydrogen atom content = approximately 0.83% by mass) consisting of siloxane units represented by the formula (1) and terminated at the molecular chain ends with trimethylsiloxy groups.

[0043] The following components were used as component (C): (c-1): 1,3-divinyltetramethyldisiloxane solution of platinum complex in 1,3-divinyltetramethyldisiloxane (platinum metal content = approximately 6,700 ppm)

[0044] The following components were used as component (D): (d-1):Formula: [ka] A glycoluril compound represented by the formula (product name TA-G, manufactured by Shikoku Chemical Industry Co., Ltd.)

[0045] In addition, the following components were used for comparison with component (D). (d-2): N,N'-diallyl cyanuric acid compound (trade name LDAIC, manufactured by Shikoku Chemicals Corporation) (d-3): Triallyl isocyanurate (d-4): Bis(N,N'-diallyl cyanuric acid) compound (product name DD-1, manufactured by Shikoku Chemicals Corporation)

[0046] The following component was used as component (E): (e-1): A mixture of 2 parts by mass of 1-ethynyl-cyclohexan-1-ol and 98 parts by mass of a dimethylpolysiloxane (vinyl group content = approximately 0.13% by mass) terminated at both ends of the molecular chain with dimethylvinylsiloxy groups and having a viscosity of 10,000 mPa·s.

[0047] The following components were used as component (F): (f-1): BET specific surface area is 255m 2 / g fumed silica

[0048] The component (f-1) was blended as a silica masterbatch prepared as follows, but in Table 1-3, each component is listed separately.

[0049] <Preparation of Silica Masterbatch> 100 parts by mass of the above component (a-2), 40 parts by mass of the above component (f-1), 7 parts by mass of hexamethyldisilazane, 1.7 parts by mass of water, and 0.2 parts by mass of a dimethylsiloxane-methylvinylsiloxane copolymer (vinyl group content: approximately 10.9% by mass) capped at both molecular chain ends with dimethylhydroxysiloxy groups and having a viscosity of 20 mPa s were charged into a Ross mixer and mixed at room temperature until uniform, followed by heat treatment under reduced pressure at 200°C for 2 hours to prepare a flowable silica masterbatch.

[0050] [Table 1]

[0051] [Table 2]

[0052] [Table 3]

[0053] <Examples 15-18, Comparative Example 7> Curable silicone compositions were prepared by uniformly mixing the following ingredients in addition to the above components to obtain the composition shown in Table 4. In the table, SiH / Vi indicates the number of moles of silicon-bonded hydrogen atoms in component (B) per mole of alkenyl groups in component (A).

[0054] The following components were used as component (A): (a-4): Methyl(3,3,3-trifluoropropyl)polysiloxane (vinyl group content = approximately 0.15% by mass) terminated at both ends of the molecular chain by dimethylvinylsiloxy groups, with a viscosity of 50,000 mPa·s

[0055] The following components were used as component (B): (b-4):Kinematic viscosity 7mm 2 / s, average unit formula: [H(CH3)2SiO 1 / 2 ] 1.5 (CF3C2H4SiO 3 / 2 )1 A branched-chain organopolysiloxane (content of silicon-bonded hydrogen atoms = approximately 0.60% by mass) represented by the formula

[0056] The following components were used as component (C): (c-2): A dimethylpolysiloxane dispersion capped with vinyldimethylsiloxy groups at both molecular chain ends (platinum metal content = approximately 4,000 ppm) with a viscosity of 2,200 mPa·s, containing 40 mass% of an encapsulated catalyst with a glass transition temperature of approximately 65°C, which is a 1,3-divinyltetramethyldisiloxane solution of platinum 1,3-divinyltetramethyldisiloxane complex microencapsulated in silicone resin.

[0057] The following component was used as component (E): (e-2): 2-methyl-3-butyn-2-ol

[0058] As the component (F), the above components (f-1) and (f-2) were used. In Examples 15 to 18 and Comparative Example 7, component (f-1) was blended as a silica masterbatch prepared in the same manner as above, but in Table 4, each component is listed separately. (f-2): Cerium oxide powder with an average particle size of approximately 14 μm

[0059] [Table 4]

[0060] <Examples 19-22, Comparative Examples 8-9> Curable silicone compositions were prepared by uniformly mixing the following ingredients in addition to the above components to obtain the composition shown in Table 5. In the table, SiH / Vi indicates the number of moles of silicon-bonded hydrogen atoms in component (B) per mole of alkenyl groups in component (A).

[0061] As the component (A), in addition to the above components (a-1) and (a-2), the following components were used. (a-5): Dimethylsiloxane-methylvinylsiloxane copolymer with a viscosity of 340 mPa·s, both ends of which are capped with dimethylvinylsiloxy groups (vinyl group content: approximately 1.17% by mass).

[0062] As the component (B), the above component (b-1) was used.

[0063] In addition to the above component (c-2), the following components were used as component (C). (c-3): A dimethylpolysiloxane dispersion capped with vinyldimethylsiloxy groups at both molecular chain ends, with a viscosity of 2,200 mPa·s, containing 40 mass% of a capsule-type catalyst with a glass transition temperature of approximately 65°C, which is a 1,3-divinyltetramethyldisiloxane solution of platinum 1,3-divinyltetramethyldisiloxane complex microencapsulated in acrylic resin (platinum metal content = approximately 4,000 ppm).

[0064] Furthermore, the component (e-1) was used as the component (E).

[0065] The following components were used as component (F): (f-3): BET specific surface area is 400m 2 / g fumed silica

[0066] In Examples 19-22 and Comparative Examples 8-9, component (f-3) was blended as a silica masterbatch prepared as follows, but in Table 5, each component is listed separately.

[0067] <Preparation of Silica Masterbatch> 100 parts by mass of the above component (a-2), 50 parts by mass of the above component (f-3), 10 parts by mass of hexamethyldisilazane, 0.36 parts by mass of tetramethyldivinylsilazane, 2 parts by mass of water, and 0.26 parts by mass of a dimethylsiloxane-methylvinylsiloxane copolymer (vinyl group content = approximately 10.9% by mass) capped at both molecular chain terminals with dimethylhydroxysiloxy groups and having a viscosity of 20 mPa s were charged into a Ross mixer and mixed at room temperature until uniform, followed by heat treatment under reduced pressure at 200°C for 2 hours to prepare a flowable silica masterbatch.

[0068] [Table 5] [Industrial Applicability]

[0069] The curable silicone composition of the present invention has good curability and a sufficient pot life at room temperature, making it suitable as a silicone material for use in, for example, mold molding, compression molding, transfer molding, injection molding, extrusion molding, or calendar molding.

Claims

1. (A) 100 parts by mass of an organopolysiloxane having at least two alkenyl groups in one molecule, (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in each molecule; The silicon-bonded water in this component is 1 mole per mole of the total alkenyl groups in component (A). an amount that provides 0.1 to 10 moles of elementary atoms; (C) a catalytic amount of a hydrosilylation catalyst, and (D) General formula: [Chemical Formula 1] (In the formula, each R １ are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 3 to 6 carbon atoms, provided that at least one R １ is the alkenyl group, and each R ２ are independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 0.001 to 5 / 72 parts by mass of a glycoluril compound represented by the formula: consisting of at least A curable silicone composition in which component (B) is an organopolysiloxane having siloxane units represented by the formula: HR 2 SiO 1 / 2 (wherein each R independently represents an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a fluoroalkyl group having 3 to 12 carbon atoms).

2. The component (B) is a compound represented by the formula: HR ２ SiO １／２ (wherein each R is independently the same group as defined above), and a siloxane unit represented by the formula: SiO ４／２ 2. The curable silicone composition according to claim 1, wherein the organopolysiloxane has siloxane units represented by the formula:

3. The component (B) is a compound represented by the formula: HR ２ SiO １／２ and siloxane units represented by the formula: RSiO ３／２ 2. The curable silicone composition according to claim 1, which is an organopolysiloxane having siloxane units represented by the formula: wherein each R is independently the same group as defined above.

4. The component (D) is a compound represented by the formula: 【Chemistry 2】 2. The curable silicone composition according to claim 1, wherein the glycoluril compound is represented by the formula:

5. 2. The curable silicone composition according to claim 1, further comprising (E) a hydrosilylation reaction inhibitor other than component (D).

Images