Addition-curable silicone resin composition

Abstract

To provide an addition-curable silicone resin composition excellent in curability, and resin strength and elongation of a cured product, and having both thermal conductivity and electrical conductivity.SOLUTION: An addition-curable silicone resin composition comprising (A) a linear organopolysiloxane having two or more alkenyl groups having 2 to 8 carbon atoms in one molecule, (B-1) a branched organohydrogenpolysiloxane, (B-2) a linear organohydrogenpolysiloxane, (C) a flaky silver powder surface-treated with a branched organohydrogenpolysiloxane having two or more hydrogen atoms directly bonded to silicon atoms in one molecule, being liquid at 25 °C, and having a weight average molecular weight Mw of 1,500 to 6,000, and (D) an addition reaction catalyst.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an addition-curable silicone resin composition. [Background technology]

[0002] Traditionally, silver powder has been used as a filler for various polymers due to its high thermal conductivity and electrical conductivity. Examples of the application of silver powder to silicone resins are presented below. First, in addition to surface treatment with fatty acids, silver powders that have been surface-treated with specific organosilicon compounds are known. While there is a description of the electrical conductivity of silicone cured products using this silver powder, there is no description of the flexibility or thermal conductivity of the resulting cured products (Patent Document 1).

[0003] Another well-known method involves treating a flake-shaped silver powder surface-treated with a fatty acid with a basic compound. This method produces bare, flaky aggregated silver powder with the fatty acid removed from the particle surface. However, the binder resin used in the silver paste composition is a thermal radical-curing methylvinylpolysiloxane, which is subject to oxygen inhibition in the atmosphere. Therefore, heat and pressure treatment is required to produce a cured product, making it unsuitable for general use. Furthermore, the use of addition-curing silicone resins as binder resins has not been addressed (Patent Document 2).

[0004] It is also known that silver powder and finely powdered silica are mixed in advance, left at room temperature for 30 days, and then the mixed powder is sieved to remove agglomerated powder. However, this method is not preferable from the viewpoint of atom economy, and there is no description of the surface condition of the raw material silver powder (Patent Document 3).

[0005] A silver paste using an ultraviolet-curable addition-curing silicone resin as a binder resin is known. This resin produces a flexible cured product, but there is no mention of its thermal conductivity, and there is no mention of the shape of the silver powder, let alone the surface condition, raising concerns about its range of application (Patent Document 4).

[0006] Another known surface treatment method for silver powder is to apply tetraethoxysilane to spherical reduced silver powder and then apply an SiO2-based gel coating. However, there are no examples of this method being applied to polymer binders, and only the behavior of the silver powder itself during high-temperature sintering has been described (Patent Document 5).

[0007] As described above, it has been difficult for conventional addition-curable silicone resin compositions containing silver powder to provide excellent curability, strength and elongation of the cured product, and both thermal conductivity and electrical conductivity. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 07-109501 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-149707 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-336273 [Patent Document 4] Japanese Patent Application Publication No. 2020-083928 [Patent Document 5] Japanese Patent Application Laid-Open No. 2008-262916 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above problems, and an object of the present invention is to provide an addition-curable silicone resin composition that exhibits excellent curability, resin strength and elongation of the cured product, and that combines thermal conductivity and electrical conductivity. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides an addition-curable silicone resin composition, comprising: (A) a linear organopolysiloxane having two or more alkenyl groups having 2 to 8 carbon atoms per molecule; (B-1) A branched organohydrogenpolysiloxane represented by the following general formula (1): [Chemical formula] (In the formula, R , , , 3 ,

[0011] , 4 / 2 , , , , , ,

[0012] , c are independently an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and n is 1 or 2.) (B-2) A linear organohydrogenpolysiloxane represented by the following general formula (2): [Chemical formula] (In the formula, R 1 is the same as described above, R 2 is independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and 0 <x, 0 ≤ y.) (C) The following general formula (3) (HR 3 2SiO 1 / 2 ) a (R 3 3SiO 1 / 2 ) b (SiO 4 / 2 ) c (3) (In the formula, R 3 is independently an alkyl group having 1 to 12 carbon atoms, 0 <a <0.6, 0 ≤ b <0.4, 0 <c <0.6, provided that a + b + c = 1.) Flaky silver powder surface-treated with a branched organohydrogenpolysiloxane having two or more hydrogen atoms directly bonded to silicon atoms represented by and being liquid at 25 °C and having a weight average molecular weight Mw of 1,500 to 6,000, and (D) An addition reaction catalyst, To provide an addition-curable silicone resin composition containing the same.

[0011] With such an addition-curable silicone resin composition, an addition-curable silicone resin composition excellent in curability, resin strength and elongation of the cured product, and compatible with both thermal conductivity and conductivity can be obtained.

[0012] In the present invention, the linear organopolysiloxane of component (A) is represented by the following general formula (4): [ka] (In the formula, R 4 are independently an alkenyl group having 2 to 8 carbon atoms or an alkyl group having 1 to 12 carbon atoms, and R 1 is the same as above, and the total R 1 80% or more of the molar ratios of the linear organopolysiloxanes are methyl groups. k is an integer greater than 0, and the linear organopolysiloxane has a kinematic viscosity at 25°C of 10 to 1,000,000 mm, as measured by the method described in JIS Z 8803:2011. 2 / s.) Preferably, the organosiloxane is an alkenyl-containing linear organopolysiloxane represented by the formula:

[0013] In the addition-curable silicone resin composition of the present invention, such component (A) is preferred.

[0014] In the present invention, the viscosity of the branched organohydrogenpolysiloxane of component (C) at 25°C, as measured by the method described in JIS K 7117-1:1999, is preferably 10 Pa·s or greater.

[0015] Such branched organohydrogenpolysiloxanes as component (C) are preferred because they are easy to handle when pulverized into flaky silver powder.

[0016] In the present invention, the branched organohydrogenpolysiloxane of component (C) is HR 3 2SiO 1 / 2 Unit source, R 3 3SiO 1 / 2 Unit source, and SiO 4 / 2 A co-hydrolysis condensate of unit sources, 4 / 2 The unit source is preferably a partial hydrolysis condensate of a tetraalkoxysilane.

[0017] Such a branched organohydrogenpolysiloxane as component (C) can have a high weight average molecular weight and a low content of volatile hydrosilyl group-containing low molecular weight siloxanes. [Effects of the Invention]

[0018] As described above, the addition-curable silicone resin composition of the present invention can provide an addition-curable silicone resin composition that exhibits excellent curability even with a small amount of catalyst, that exhibits excellent resin strength and elongation in the cured product, and that combines thermal conductivity and electrical conductivity. For these reasons, the addition-curable silicone resin composition of the present invention is extremely useful. DETAILED DESCRIPTION OF THE INVENTION

[0019] As described above, there has been a need for the development of an addition-curable silicone resin composition that exhibits excellent curability, resin strength and elongation of the cured product, and that combines thermal conductivity and electrical conductivity.

[0020] As a result of extensive research into the above-mentioned problems, the present inventors discovered that by using a specific organopolysiloxane in combination with silver powder that has been surface-treated with a specific organohydrogenpolysiloxane, it is possible to achieve better curability, resin strength and elongation of the cured product than before, and to achieve both thermal conductivity and electrical conductivity, and thus completed the present invention.

[0021] That is, the present invention provides an addition-curable silicone resin composition, (A) a linear organopolysiloxane having two or more alkenyl groups having 2 to 8 carbon atoms per molecule; (B-1) a branched organohydrogenpolysiloxane represented by the following general formula (1): [ka] (In the formula, R 1 are independently an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and n is 1 or 2. (B-2) A linear organohydrogenpolysiloxane represented by the following general formula (2), [Chemical formula] (In the formula, R 1 is the same as described above, and R 2 is independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and 0 < x, 0 ≦ y.) (C) The following general formula (3) (HR 3 2SiO 1 / 2 ) a (R 3 3SiO 1 / 2 ) b (SiO 4 / 2 ) c (3) (In the formula, R 3 is independently an alkyl group having 1 to 12 carbon atoms, 0 < a < 0.6, 0 ≦ b < 0.4, 0 < c < 0.6, provided that a + b + c = 1 is a number that satisfies.) A flaky silver powder surface-treated with a branched organohydrogenpolysiloxane having two or more hydrogen atoms directly bonded to silicon atoms in one molecule, which is liquid at 25 ° C and has a weight average molecular weight Mw of 1,500 to 6,000, and (D) An addition reaction catalyst, It is an addition-curable silicone resin composition containing

[0022] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0023] <Addition-curable silicone resin composition> The addition-curable silicone resin composition of the present invention contains (A) a linear organopolysiloxane, (B-1) a branched organohydrogenpolysiloxane, (B-2) a linear organohydrogenpolysiloxane, (C) a flaky silver powder, and (D) an addition reaction catalyst. Hereinafter, each component will be described.

[0024] <(A) Linear organopolysiloxane> Component (A) is a linear organopolysiloxane having two or more alkenyl groups having 2 to 8 carbon atoms per molecule, and is the main component of the present invention. Furthermore, component (A) is represented by the following general formula (4): [ka] (In the formula, R 4 are independently an alkenyl group having 2 to 8 carbon atoms or an alkyl group having 1 to 12 carbon atoms, and R 1 is the same as above, and the total R 1 80% or more of the molar ratios of the linear organopolysiloxanes are methyl groups. k is an integer greater than 0, and the linear organopolysiloxane has a kinematic viscosity at 25°C of 10 to 1,000,000 mm, as measured by the method described in JIS Z 8803:2011. 2 / s.) Preferably, the organosiloxane is an alkenyl-containing linear organopolysiloxane represented by the formula:

[0025] In the above general formula (4), R 4 Specific examples of the alkenyl group having 2 to 8 carbon atoms, particularly 2 to 6 carbon atoms, include vinyl, allyl, isopropenyl, butenyl, pentenyl, hexenyl, and cyclohexenyl groups, with vinyl being particularly preferred in terms of reactivity.

[0026] In the above general formula (4), R 4 Specific examples of alkyl groups having 1 to 12 carbon atoms, particularly 1 to 10 carbon atoms, include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl. 4 As the alkyl group, in consideration of the heat resistance under high temperature conditions of the silicone cured product produced from the resulting addition-curable silicone resin composition, a methyl group, an ethyl group, a propyl group, an isopropyl group, etc. are preferred, and a methyl group is particularly preferred.

[0027] In the above general formula (4), R 1Specific examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a naphthyl group, with a phenyl group being particularly preferred. When a linear organopolysiloxane having a predetermined number of phenyl groups introduced therein is used, the storage modulus in the low temperature range of the cured product obtained from the addition-curable silicone resin composition of the present invention can be kept low.

[0028] In the above general formula (4), R 1 Specific examples of the alkyl group having 1 to 12 carbon atoms include the above-mentioned R 4 The same can be exemplified. 1 More than 80% of the moles are methyl groups.

[0029] The kinematic viscosity of the component (A) at 25°C measured using a Cannon-Fenske viscometer according to JIS Z 8803:2011 is 10 to 1,000,000 mm 2 / s, and more preferably 100 to 100,000 mm 2 / s range.

[0030] In the general formula (4), k is an integer greater than 0, and is a number that ensures that the kinematic viscosity falls within the above range.

[0031] Specific examples of the component (A) include the following. [ka]

[0032] <(B-1) Branched organohydrogenpolysiloxane> The component (B-1) is a branched organohydrogenpolysiloxane represented by the following general formula (1). [ka] (In the formula, R 1 are independently an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and n is 1 or 2.

[0033] In the above general formula (1), R 1 Specific examples of alkyl groups having 1 to 12 carbon atoms, particularly 1 to 10 carbon atoms, include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl. 1 As the alkyl group, in consideration of the heat resistance under high temperature conditions of the silicone cured product produced from the resulting addition-curable silicone resin composition, a methyl group, an ethyl group, a propyl group, an isopropyl group, etc. are preferred, and a methyl group is particularly preferred.

[0034] In the above general formula (1), R 1 Specific examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a naphthyl group, with a phenyl group being particularly preferred. When a branched organohydrogenpolysiloxane having a predetermined number of phenyl groups introduced therein is used, the storage modulus in the low temperature range of the cured product obtained from the addition-curable silicone resin composition of the present invention can be kept low.

[0035] In the above general formula (1), n ​​is 1 or 2, and preferably 2.

[0036] Such branched organohydrogenpolysiloxanes contain an abundance of siloxane units having silicon-bonded hydrogen atoms on the M units, and therefore can improve the curability of addition-curable silicone resin compositions of the present invention containing such organohydrogenpolysiloxanes and the elongation of the resulting cured products.

[0037] Specific examples of the branched organohydrogenpolysiloxane of component (B-1) include the following: [ka] (In the above formula, Me represents a methyl group, and Ph represents a phenyl group.)

[0038] <(B-2) Linear Organohydrogen Polysiloxane> (Component (B-2) is a linear organohydrogenpolysiloxane represented by the following general formula (2). [Chemical formula] (In the formula, R 1 is the same as described above, and R 2 is independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, where 0 <x and 0 ≤ y.)

[0039] In the above general formula (2), as the alkyl group having 1 to 12 carbon atoms, particularly preferably 1 to 10 carbon atoms, of R 2 , specifically, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group etc. can be exemplified. As the alkyl group of R 2 above, considering the heat resistance of the silicone cured product produced from the obtained addition-curable silicone resin composition under high temperature conditions, methyl group, ethyl group, propyl group, isopropyl group etc. are preferable, and particularly the methyl group is preferable.

[0040] In the above general formula (2), as the aryl group having 6 to 12 carbon atoms of R 2 , specifically, phenyl group, naphthyl group etc. are exemplified, and particularly the phenyl group is preferable. When using a linear organohydrogenpolysiloxane into which a predetermined amount of phenyl group is introduced in this way, the storage elastic modulus in the low temperature region of the cured product obtained from the addition-curable silicone resin composition of the present invention can be suppressed low.

[0041] In the above general formula (2), 0 <x and 0 ≤ y, preferably, 5 <x ≤ 100 and 0 ≤ y ≤ 50.

[0042] In the above general formula (2), R 1 is the same as R 1 in the above general formula (1).

[0043] By including such a linear organohydrogenpolysiloxane having hydrogen atoms directly bonded to silicon atoms in side chains on the molecular chain, the addition-curable silicone resin composition of the present invention can improve the hardness and strength of the resulting cured product.

[0044] Specific examples of the linear organohydrogenpolysiloxane of component (B-2) include the following: [ka]

[0045] Furthermore, the amounts of components (B-1) and (B-2) blended are preferably such that the total amount of silicon-bonded hydrogen atoms in components (B-1) and (B-2) combined is in the range of 1.0 to 3.0 moles, and particularly preferably 1.2 to 2.0 moles, per mole of silicon-bonded alkenyl groups in the entire addition-curable silicone resin composition. When the total amount of silicon-bonded hydrogen atoms in components (B-1) and (B-2) combined is within this range, the curing reaction proceeds smoothly, and a silicone cured product with excellent strength and elongation can be obtained.

[0046] Furthermore, depending on the object of the present invention, a linear organohydrogenpolysiloxane other than the component (B-2) may be added. Specific examples include linear organohydrogenpolysiloxanes having hydrogen atoms directly bonded to silicon atoms only at both ends.

[0047] If a linear organohydrogenpolysiloxane other than the optional component (B-2) is added, the amount of the added organohydrogenpolysiloxane is added to the amounts of the components (B-1) and (B-2) above, and the amount of the added organohydrogenpolysiloxane is then added to the amount of the alkenyl groups in the composition.

[0048] <(C) Flake silver powder> Component (C) is represented by the following general formula (3): (HR 3 2SiO 1 / 2 ) a (R3 3SiO 1 / 2 ) b (SiO 4 / 2 ) c (3) (wherein R 3 is independently an alkyl group having 1 to 12 carbon atoms, 0 < a < 0.6, 0 ≤ b < 0.4, 0 < c < 0.6, provided that a + b + c = 1.) It is a flaky silver powder surface-treated with a branched organohydrogenpolysiloxane that has two or more hydrogen atoms directly bonded to silicon atoms represented by and is liquid at 25°C and has a weight-average molecular weight Mw of 1,500 to 6,000.)

[0049] The branched organohydrogenpolysiloxane of the above general formula (3) is used as a lubricant when obtaining flaky silver powder by mechanically pulverizing spherical reduced silver powder or atomized silver powder as a raw material with a ball mill or the like. Also, a part of it remains on the surface of the target flaky silver powder. When pulverizing silver powder into flakes, the addition amount of the above branched organopolysiloxane is preferably 1 to 200% by mass, more preferably 10 to 100% by mass, based on 100% by mass of the spherical silver powder as the raw material. A solvent may also be added, and it is used for the purpose of dissolving the branched organohydrogenpolysiloxane of the above general formula (3) and improving the contact efficiency with silver powder. Examples of the solvent include various alcohols.)

[0050] In the above general formula (3), as the alkyl group having 1 to 12 carbon atoms, particularly preferably 1 to 10 carbon atoms, for R 3 , specifically, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. can be exemplified. As the alkyl group of the above R 3 , considering the heat resistance of the silicone cured product produced from the resulting addition-curable silicone resin composition under high-temperature conditions, a methyl group, ethyl group, propyl group, isopropyl group, etc. are preferable, and particularly a methyl group is preferable.)

[0051] Also, in the above general formula (3), HR 3 2SiO 1 / 2 The content ratio a of the unit is in the range of 0 < a < 0.6 with respect to the total of the siloxane units a + b + c = 1, and particularly preferably in the range of 0.2 ≤ a ≤ 0.5. Also, R 3 3SiO 1 / 2 The content ratio b of the unit is 0 ≤ b < 0.4 with respect to the total of the siloxane units a + b + c = 1, and particularly preferably in the range of 0 ≤ b ≤ 0.3. Further, the content ratio c of the SiO 4 / 2 unit is 0 < c < 0.6 with respect to the total of the siloxane units a + b + c = 1, and particularly preferably in the range of 0.45 ≤ c ≤ 0.55.

[0052] Also, the branched organohydrogenpolysiloxane in the above general formula (3) has a weight average molecular weight in the range of 1,500 or more and 6,000 or less, and particularly preferably in the range of 2,500 or more and 5,000 or less. When the weight average molecular weight of the branched organohydrogenpolysiloxane is outside the above range, the pulverization process into flaky silver powder does not proceed smoothly.

[0053] In addition, the weight average molecular weight referred to in the present invention means the weight average molecular weight based on polystyrene measured by gel permeation chromatography (GPC) under the following conditions. [Measurement Conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.6 mL / min Detector: Differential refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperH4000 (6.0 mm I.D. × 15 cm × 1) TSKgel SuperH3000 (6.0 mm I.D. × 15 cm × 1)[[ID=3,4]] TSKgel SuperH2000 (6.0 mm I.D. × 15 cm × 2) (All are manufactured by Tosoh Corporation) Column temperature: 40 °C Sample injection volume: 20 μL (0.5% by mass THF solution)

[0054] Furthermore, the viscosity of the branched organohydrogenpolysiloxane of component (C) at 25°C, as measured by the method described in JIS K 7117-1:1999, is preferably 10 Pa·s or more, and more preferably 200 to 1,500 Pa·s. When the branched organohydrogenpolysiloxane of general formula (3) satisfies the above viscosity, it is easy to handle during pulverization into flake silver powder. In the present invention, "liquid" refers to a substance having fluidity that allows viscosity measurement at 25°C using a rotational viscometer, and particularly refers to a substance having a viscosity at 25°C of 10,000 Pa·s or less.

[0055] Furthermore, the branched organohydrogenpolysiloxane in the general formula (3) preferably has two or more hydrosilyl groups per molecule, and the amount of hydrosilyl groups in the branched organohydrogenpolysiloxane is preferably 0.1 to 2 mol / 100 g, and particularly preferably 0.2 to 0.9 mol / 100 g. If the branched organohydrogenpolysiloxane has fewer than two hydrosilyl groups per molecule, the pulverization process into the flaky silver powder does not proceed smoothly, and lumps may form.

[0056] The branched organohydrogenpolysiloxane of the general formula (3) can be easily synthesized by mixing the compounds serving as the source units in the above-mentioned ranges and using a known method. 3 2SiO 1 / 2 Unit source, R 3 3SiO 1 / 2 Unit source, and SiO 4 / 2 A co-hydrolysis condensate of unit sources, 4 / 2 The unit source is preferably a partial hydrolysis condensate of tetraalkoxysilane. 4 / 2When a partial hydrolysis condensate of tetramethoxysilane and / or tetraethoxysilane is used as the unit source, it is possible to obtain a branched organohydrogenpolysiloxane with a high weight average molecular weight and a low content of volatile hydrosilyl group-containing low-molecular-weight siloxanes.

[0057] In addition, the above SiO 4 / 2 When a partial hydrolysis condensate of tetramethoxysilane and / or tetraethoxysilane is used as the unit source, it is preferable that the content of monomers such as tetramethoxysilane contained in the partial hydrolysis condensate is low. The content of monomers is preferably 10% by mass or less, and particularly preferably 5% by mass or less. If the monomer content in the hydrolysis condensate is high, the branched organohydrogenpolysiloxane in general formula (3) will contain a large amount of volatile hydrosilyl group-containing low-molecular-weight siloxane, which will deteriorate the stability of the silicone coating present on the surface of component (C) produced using the branched organohydrogenpolysiloxane.

[0058] In the present invention, the average particle size (D50) refers to the median diameter based on volume as measured by laser diffraction, and can be selected depending on the intended film thickness when mounted. The average particle size (D50) of the above-mentioned flake silver powder is preferably in the range of 0.1 to 20.0 μm, more preferably in the range of 1.0 to 10.0 μm.

[0059] The amount of component (C) blended is preferably in the range of 65 to 95 mass%, and more preferably 80 to 90 mass%, based on 100 mass% of the entire addition-curable silicone resin composition. When the amount of component (C) blended is within this range, the cured product obtained from the addition-curable silicone resin composition exhibits high thermal conductivity and electrical conductivity while maintaining resin strength and elongation.

[0060] <(D) Addition reaction catalyst> The addition reaction catalyst (D) is incorporated to promote the addition curing reaction of the addition-curable silicone resin composition of the present invention. Examples of such catalysts include those containing platinum group metal elements, such as platinum, palladium, and rhodium. From the standpoint of cost and other factors, platinum itself, platinum-based catalysts such as chloroplatinic acid (e.g., HPtCl₆·mH₂O, KPtCl₆, KHPtCl₆·mH₂O, KPtCl₄, KPtCl₄·mH₂O (m is a positive integer), and complexes of these with hydrocarbons such as olefins, alcohols, or alkenyl-group-containing organopolysiloxanes are preferred. These catalysts can be used alone or in combination of two or more. Platinum-based catalysts may also be complexes that become active when exposed to ultraviolet light due to ligand cleavage.

[0061] The amount of addition reaction catalyst blended is preferably in the range of 0.1 to 100 ppm, more preferably 1 to 50 ppm, in platinum group metal mass units, per 100 parts by mass of the entire addition-curable silicone resin composition. When the amount of addition reaction catalyst blended is within this range, the addition-curable silicone resin composition has good storage properties and the addition curing reaction proceeds smoothly when heated.

[0062] <Additives> The addition-curable silicone of the present invention may also contain other known additives, such as cure inhibitors, adhesion promoters, and anti-settling agents.

[0063] <Cure inhibitor> The addition-curable silicone resin composition of the present invention can contain a cure inhibitor for purposes such as adjusting the cure rate. Examples of cure inhibitors include vinyl-containing organopolysiloxanes such as tetramethyltetravinylcyclotetrasiloxane, hexavinyldisiloxane, and 1,3-divinyltetramethyldisiloxane; acetylene alcohols such as ethynylcyclohexanol and 3-methyl-1-butyn-3-ol, as well as silane- and siloxane-modified versions thereof; hydroperoxides; tetramethylethylenediamine; benzotriazole; triallyl isocyanurate; alkyl maleates; and mixtures thereof. In particular, ethynylcyclohexanol is preferably used in view of the decomposition potential during curing and the effect on heat resistance due to residual fragments.

[0064] When a cure inhibitor is added, it is preferably added in an amount of 0.001 to 1.0 part by mass, and particularly preferably 0.005 to 0.5 part by mass, per 100 parts by mass of the total addition-curable silicone resin composition.

[0065] <Adhesion promoter> The addition-curable silicone resin composition of the present invention can be blended with an adhesion promoter to improve adhesion to a substrate. Examples of adhesion promoters include alkoxysilane monomers such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane; epoxy group-containing organopolysiloxanes such as hydrolysis condensates of dimethyldiorganosilane and 3-glycidoxypropyltrimethoxysilane; compounds containing an isocyanuric acid skeleton such as tris(3-trimethoxysilylpropyl)isocyanurate; and acrylic compounds such as 5-ethyl-5-(hydroxymethyl)-β,β-dimethyl-1,3-dioxane-2-ethanol diacrylate (trade name: KAYARAD R-604, manufactured by Nippon Kayaku Co., Ltd.).

[0066] When an adhesion promoter is added, the amount can be 0.01 to 5% by mass relative to 100% by mass of the entire addition-curable silicone resin composition.

[0067] <Anti-settling agent> The addition-curable silicone resin composition of the present invention may contain an anti-settling agent to prevent separation of the filler and resin component during storage. Examples of anti-settling agents include fumed silica and zinc oxide.

[0068] When an anti-settling agent is added, the amount may be 0.01 to 5% by mass relative to 100% by mass of the entire addition-curable silicone resin composition. [Example]

[0069] The present invention will be specifically explained below using Production Examples, Examples and Comparative Examples, but the present invention is not limited to these.

[0070] In addition, "parts" means "parts by mass," Me represents a methyl group, Vi represents a vinyl group, and Ph represents a phenyl group. The weight average molecular weight Mw refers to the weight average molecular weight measured by GPC under the conditions described above. In the following examples, the amount of hydrosilyl groups refers to the number of moles of hydrogen atoms directly bonded to silicon atoms in a molecule, and is measured by a Bruker Nuclear Magnetic Resonance (NMR) measurement device. 1 The values ​​were determined by H-NMR measurement using dimethyl sulfoxide (DMSO) as an internal standard. The amount of SiVi groups refers to the number of moles of vinyl groups directly bonded to silicon atoms in a molecule, and is measured using a Bruker nuclear magnetic resonance (NMR) measurement device. 1 The values ​​were determined by H-NMR measurement using DMSO as an internal standard. The kinematic viscosity is a value measured by a method using a Cannon-Fenske viscometer as described in JIS Z 8803:2011. The viscosity is a value measured by a method using a rotational viscometer as described in JIS K 7117-1:1999. The average particle size (D50) is a median diameter based on volume measured by laser diffraction.

[0071] [Manufacturing Example 1] Spherical reduced silver powder with an average particle size (D50) of 4.0 μm was prepared by the following formula: (HMeSiO 1 / 2 ) 0.50 (SiO 4 / 2 ) 0.50 The powder was immersed in a 1-butanol solution of organohydrogenpolysiloxane with a viscosity of 1,200 Pa·s at 25°C, a weight-average molecular weight Mw of 3,700 as measured by GPC, and a hydrosilyl group content of 0.70 mol / 100 g, and then ground using a ball mill. After washing and drying, flake-shaped silver powder (c-1) with an average particle size (D50) of 5.8 μm was obtained. Analysis of the cross-section of (c-1) particles by STEM-EDX revealed a layer containing Si elements of 1 to 5 nm on the particle surface. Furthermore, analysis of the outermost particle surface of (c-1) by XPS revealed the presence of Me2SiO 2 / 2 The unit was detected. This is HMe2SiO 1 / 2 It was suggested that the units were converted by a chemical reaction on the surface of the silver particles, and that surface treatment was performed by chemical bonding.

[0072] [Manufacturing Example 2] Spherical reduced silver powder with an average particle size (D50) of 4.0 μm was prepared by the following formula: (HMe2SiO 1 / 2 ) 0.25 (MeSiO 1 / 2 ) 0.25 (SiO 4 / 2 ) 0.50 The powder was immersed in a 1-butanol solution of organohydrogenpolysiloxane with a viscosity of 320 Pa·s at 25°C, a weight-average molecular weight Mw of 2,600 measured by GPC, and a hydrosilyl group content of 0.40 mol / 100 g, and then ground using a ball mill. After washing and drying, flake-shaped silver powder (c-2) with an average particle size (D50) of 5.3 μm was obtained. Analysis of the cross-section of (c-2) particles by STEM-EDX revealed a layer containing Si elements in the range of 1 to 5 nm on the particle surface. Furthermore, analysis of the outermost particle surface of (c-2) by XPS revealed the presence of Me2SiO 2 / 2 The unit was detected. This is HMe2SiO 1 / 2 It was suggested that the units were converted by a chemical reaction on the surface of the silver particles, and that surface treatment was performed by chemical bonding.

[0073] [Comparative Manufacturing Example 1] Spherical reduced silver powder with an average particle size (D50) of 4.0 μm, the siloxane units of which are MeSiO 3 / 2 The silver powder (c-3) was immersed in a 1-butanol solution of organopolysiloxane (KR-220L, manufactured by Shin-Etsu Chemical Co., Ltd.), which is solid at 25°C and has a weight-average molecular weight (Mw) of 3,600 as measured by GPC and a SiOH group content of 0.20 mol / 100 g, expressed in units of 100 mol%, and was then ground using a ball mill. After washing and drying, spherical silver powder (c-3) with an average particle size (D50) of 4.2 μm was obtained. Furthermore, STEM-EDX analysis of the cross-sections of (c-3) particles revealed no layer containing Si element on the particle surface.

[0074] [Comparative Manufacturing Example 2] Spherical reduced silver powder with an average particle size (D50) of 4.0 μm was prepared by the following formula: (MeSiO 1 / 2 ) 0.44 (SiO 4 / 2 ) 0.56 The powder was immersed in a 1-butanol solution of organopolysiloxane, which is solid at 25°C and has a weight-average molecular weight (Mw) of 4,400 as measured by GPC and a SiOH group content of 0.10 mol / 100 g, and then ground using a ball mill. After washing and drying, spherical silver powder (c-4) with an average particle size (D50) of 4.1 μm was obtained. Furthermore, STEM-EDX analysis of the particle cross-sections of (c-4) revealed no layer containing elemental silicon on the particle surface.

[0075] [Comparative Manufacturing Example 3] Spherical reduced silver powder with an average particle size (D50) of 4.0 μm was prepared by the following formula: (MeSiO 1 / 2 )2(HMeSiO 2 / 2 ) 50 The silver powder was immersed in a 1-butanol solution of organohydrogenpolysiloxane with a viscosity of 25 mPa·s at 25°C, a weight-average molecular weight Mw of 4,200 measured by GPC, and a hydrosilyl group content of 1.55 mol / 100 g, and then ground using a ball mill. After washing and drying, an ellipsoidal silver powder (c-5) containing a gel with an average particle size (D50) of 5.1 μm was obtained. Furthermore, STEM-EDX analysis of the particle cross-section of (c-5) revealed sparse layers containing Si elements ranging from 1 to 100 nm on the particle surface. Furthermore, XPS analysis of the outermost particle surface of (c-5) revealed the presence of MeSiO 3 / 2 The unit was detected. This is HMeSiO 2 / 2 It was suggested that the units were converted by a chemical reaction on the surface of the silver particles, and that surface treatment was performed by chemical bonding.

[0076] [Comparative Manufacturing Example 4] Spherical reduced silver powder with an average particle size (D50) of 4.0 μm was prepared by the following formula: (HMe2SiO 1 / 2 ) 0.66 (SiO 4 / 2 ) 0.34 The powder was immersed in a 1-butanol solution of organohydrogenpolysiloxane with a viscosity of 2.6 Pa·s at 25°C, a weight-average molecular weight Mw of 1,300 measured by GPC, and a hydrosilyl group content of 1.00 mol / 100 g, and then ground using a ball mill. After washing and drying, ellipsoidal silver powder (c-6) with an average particle size (D50) of 5.0 μm was obtained. Furthermore, STEM-EDX analysis of the particle cross-section of (c-6) revealed a sparse layer containing Si elements in the range of 1 to 2 nm on the particle surface. Furthermore, XPS analysis of the outermost particle surface of (c-6) revealed that Me2SiO 2 / 2 The unit was detected. This is HMe2SiO 1 / 2 It was suggested that the units were converted by a chemical reaction on the surface of the silver particles, and that surface treatment was performed by chemical bonding.

[0077] <Component (A)> (a-1): The following formula (ViMe2SiO 1 / 2 )2(Ph2SiO 2 / 2 ) 10 (MeSiO 2 / 2 ) 188 The SiVi group content is 0.015 mol / 100 g, and the kinematic viscosity at 25 ° C is 998 mm 2 / s is a linear organopolysiloxane (a-2): The following formula (ViMe2SiO 1 / 2 )2(Me2SiO 2 / 2 ) 200 The SiVi group content is 0.013 mol / 100 g, and the kinematic viscosity at 25 ° C is 1,018 mm 2 / s is a linear organopolysiloxane

[0078] <(B-1) component> (b1-1): The following formula [ka] The organohydrogenpolysiloxane has a hydrosilyl group content of 0.76 mol / 100 g and a viscosity of 6.6 mPa·s at 25°C. (b1-2): The following formula [ka] The organohydrogenpolysiloxane has a hydrosilyl group content of 0.90 mol / 100 g and a viscosity of 2.0 mPa·s at 25°C.

[0079] <(B-2) component> (b2-1): The following formula (MeSiO 1 / 2 )2(HMeSiO 2 / 2 ) 36 (MeSiO 2 / 2 ) 12 The organohydrogenpolysiloxane has a hydrosilyl group content of 1.14 mol / 100 g and a viscosity of 45.0 mPa·s at 25°C. (b2-2): The following formula (MeSiO 1 / 2 )2(HMeSiO 2 / 2 )8 The organohydrogenpolysiloxane has a hydrosilyl group content of 1.25 mol / 100 g and a viscosity of 4.5 mPa·s at 25°C.

[0080] <Linear organohydrogenpolysiloxane other than component (B-2)> (b3-1): The following formula (HMe2SiO 1 / 2 )2(Me2SiO 2 / 2 ) 18 The organohydrogenpolysiloxane has a hydrosilyl group content of 0.10 mol / 100 g and a viscosity of 16.5 mPa·s at 25°C.

[0081] <(C) component> (c-1): Flake silver powder with an average particle size (D50) of 5.8 μm prepared in "Production Example 1" (c-2): Flake silver powder with an average particle size (D50) of 5.3 μm prepared in "Production Example 2" (c-3): Spherical silver powder with an average particle size (D50) of 4.2 μm prepared in "Comparative Production Example 1" (c-4): Spherical silver powder with an average particle size (D50) of 4.1 μm prepared in "Comparative Manufacturing Example 2" (c-5): Elliptical silver powder containing gel particles with an average particle size (D50) of 5.1 μm prepared in "Comparative Production Example 3" (c-6): Oval-shaped silver powder with an average particle size (D50) of 5.0 μm prepared in "Comparative Production Example 4" (c-7): Spherical atomized silver powder with an average particle size (D50) of 5.0 μm (Tokuriki Honten Co., Ltd.: AGF-5S) (c-8): Flake silver powder (manufactured by Tokuriki Honten Co., Ltd.: Silbestos TC-466) with an average particle size (D50) of 4.0 μm, whose surface has been treated with a fatty acid, and whose cross-section is analyzed by STEM-EDX to detect a layer containing C element derived from the fatty acid in the range of 1 to 5 nm on the particle surface.

[0082] <(D) component> (d-1): A 1,3-divinyltetramethyldisiloxane solution of a 1,3-divinyltetramethyldisiloxane complex of platinum (0), having a platinum content of 2 mass% and an SiVi group content of 1.05 mol / 100 g

[0083] <(E) Curing inhibitor> (e-1): Ethynylcyclohexanol

[0084] The addition-curable silicone resin compositions of Examples 1 to 6 and Comparative Examples 1 to 8 were prepared by blending the components described above in the proportions (parts by mass) shown in Tables 1 and 2. The resulting addition-curable silicone resin compositions were evaluated as follows. The results are shown in Tables 1 and 2.

[0085] (1) Uniformity The addition-curable silicone resin composition was sieved through a 150-mesh sieve, and those for which no agglomerates were found on the mesh were marked "Good", and those for which agglomerates were observed were marked "Poor".

[0086] (2) Viscosity The viscosity of the addition-curable silicone resin composition was measured according to the method described in JIK-7177. Viscometer used: Toki Sangyo Co., Ltd. "TVE-35" Cone used: 3° x R9.7 Rotation speed: 10 rpm ·Measurement temperature: 23.0℃

[0087] (3) Peak heat generation temperature The exothermic peak temperature of the addition-curable silicone resin composition was measured using a differential scanning calorimeter (DSC). Equipment used: Hitachi High-Tech DSC7020 ·Measurement start temperature: 25℃ Heating rate: 10℃ / min Measurement end temperature: 300℃ Measurement atmosphere: Nitrogen

[0088] (4) Hardness (Durometer Type A), tensile strength, elongation at break The addition-curable silicone resin composition was heated at 125°C for 1 hour in a hot air circulating dryer to produce a 2 mm thick cured silicone sheet. The hardness (Durometer Type A) of the cured silicone sheet was measured according to JIS K6253-3:2012, and the tensile strength and elongation at break were measured according to JIS K6251:2017.

[0089] (5) Volume resistance The addition-curable silicone resin composition was heated at 125°C for 1 hour using a hot air circulation dryer to produce a 1 mm thick cured silicone sheet. The volume resistivity of the cured silicone sheet was measured using the four-terminal method.

[0090] (6) Thermal conductivity The addition-curable silicone resin composition was heated at 125°C for 1 hour using a hot air circulation dryer to produce a 2 mm thick cured silicone sheet. The thermal conductivity of the cured silicone sheet was measured using the laser flash method (device used: LFA467HyperFlash, manufactured by Netsch Japan Co., Ltd.).

[0091] [Table 1]

[0092] [Table 2]

[0093] The results of the above evaluation tests showed that the addition-curable silicone resin compositions of the present invention (Examples 1 to 6) were excellent in curability, resin strength, and elongation, and had both good thermal conductivity and electrical conductivity.

[0094] On the other hand, the uniformity and the mechanical strength and thermal conductivity of the cured product were poor in Comparative Examples 1 and 2. The properties were very similar to those of Comparative Example 5, which used atomized silver powder (c-7), suggesting that the silver powder (c-3) used in Comparative Example 1 and the silver powder (c-4) used in Comparative Example 2 were in a nearly bare state. In addition, in Comparative Example 3, the thermal conductivity and electrical conductivity of the cured product were significantly poor, suggesting that the silicone film present on the surface of the silver powder (c-5) was so thick that it prevented the silver particles from contacting each other. In Comparative Example 4, the mechanical strength and thermal conductivity of the cured product were poor, and it was found that the silicone film on the surface of the silver powder (c-6) was insufficiently thick in terms of compatibility with the silicone resin. Furthermore, in Comparative Example 6, the curability was poor due to the influence of the fatty acid-containing silver powder (c-8), and the mechanical strength and thermal conductivity of the cured product were also poor. Comparative Examples 7 and 8 did not contain component (B-1) and component (B-2), respectively, and it was clear that the cured products were inferior in either tensile strength or elongation.

[0095] Therefore, it was confirmed that the addition-curable silicone resin composition of the present invention is excellent in curability, resin strength, and elongation, and is extremely useful because it achieves both heat conductivity and electrical conductivity.

[0096] This specification includes the following aspects. [1]: An addition-curable silicone resin composition, comprising (A) A linear organopolysiloxane having two or more alkenyl groups with 2 to 8 carbon atoms in one molecule, (B-1) A branched organohydrogenpolysiloxane represented by the following general formula (1), [Chemical formula] (In the formula, R 1 is independently an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and n is 1 or 2.) (B-2) A linear organohydrogenpolysiloxane represented by the following general formula (2), [Chemical formula] (In the formula, R 1 is the same as described above, R 2 is independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and 0 < x, 0 ≤ y.) (C) The following general formula (3) (HR 3 2SiO 1 / 2 ) a (R 3 3SiO 1 / 2 ) b (SiO 4 / 2 ) c (3) (In the formula, R 3 is independently an alkyl group having 1 to 12 carbon atoms, 0 < a < 0.6, 0 ≤ b < 0.4, 0 < c < 0.6, provided that a + b + c = 1.) A flake silver powder that has been surface-treated with a branched organohydrogenpolysiloxane that is liquid at 25°C and has a weight-average molecular weight Mw of 1,500 to 6,000, and has two or more hydrogen atoms directly bonded to silicon atoms per molecule, as shown in (D) an addition reaction catalyst; An addition-curable silicone resin composition comprising: [2]: The linear organopolysiloxane of the component (A) is represented by the following general formula (4): [ka] (In the formula, R 4 are independently an alkenyl group having 2 to 8 carbon atoms or an alkyl group having 1 to 12 carbon atoms, and R 1 is the same as above, and the total R 1 80% or more of the molar ratios of the linear organopolysiloxanes are methyl groups. k is an integer greater than 0, and the linear organopolysiloxane has a kinematic viscosity at 25°C of 10 to 1,000,000 mm, as measured by the method described in JIS Z 8803:2011. 2 / s.) The addition-curable silicone resin composition according to [1] above, characterized in that the organopolysiloxane is an alkenyl-containing linear organopolysiloxane represented by the formula: [3]: The addition-curable silicone resin composition of [1] or [2] above, wherein the viscosity of the branched organohydrogenpolysiloxane of component (C) at 25°C measured according to the method specified in JIS K 7117-1:1999 is 10 Pa s or higher. [4]: The branched organohydrogenpolysiloxane of component (C) is HR 3 2SiO 1 / 2 Unit source, R 3 3SiO 1 / 2 Unit source, and SiO 4 / 2 A co-hydrolysis condensate of unit sources, 4 / 2

[0013] The addition-curable silicone resin composition according to any one of [1] to [3] above, wherein the unit source is a partial hydrolysis condensate of a tetraalkoxysilane.

[0097] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An addition-curable silicone resin composition, comprising: (A) a linear organopolysiloxane having two or more alkenyl groups having 2 to 8 carbon atoms per molecule; (B-1) a branched organohydrogenpolysiloxane represented by the following general formula (1): 【Chemistry 1】 (In the formula, R １ are independently an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and n is 1 or 2. (B-2) a linear organohydrogenpolysiloxane represented by the following general formula (2): 【Chemistry 2】 (In the formula, R １ is the same as above, and R ２ are independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and 0<x and 0≦y. (C) the following general formula (3): (HR ３ ２ SiO １／２ , ａ (R ３ ３ SiO １／２ , ｂ (SiO ４／２ , ｃ (3) (In the formula, R ３ are independently alkyl groups having 1 to 12 carbon atoms, and are numbers satisfying 0<a<0.6, 0≦b<0.4, and 0<c<0.6, with the proviso that a+b+c=1.) a flake silver powder surface-treated with a branched organohydrogenpolysiloxane having a weight-average molecular weight Mw of 1,500 to 6,000, which is liquid at 25°C and has two or more hydrogen atoms directly bonded to silicon atoms in each molecule, and which is represented by the formula: (D) an addition reaction catalyst; An addition-curable silicone resin composition comprising:

2. The linear organopolysiloxane of the component (A) is represented by the following general formula (4): 【Transformation 3】 (In the formula, R ４ are independently an alkenyl group having 2 to 8 carbon atoms or an alkyl group having 1 to 12 carbon atoms, and R １ is the same as above, and the total R １ 80% or more of the molar ratios of the linear organopolysiloxane are methyl groups. k is an integer greater than 0, and the kinematic viscosity at 25°C measured by the method described in JIS Z 8803:2011 is 10 to 1,000,000 mm ２ / s.) 2. The addition-curable silicone resin composition according to claim 1, wherein the organopolysiloxane is an alkenyl-containing linear organopolysiloxane represented by the formula:

3. 2. The addition-curable silicone resin composition according to claim 1, wherein the viscosity of the branched organohydrogenpolysiloxane of component (C) at 25°C, as measured using the method specified in JIS K 7117-1:1999, is 10 Pa s or higher.

4. The branched organohydrogenpolysiloxane of component (C) is HR ３ ２ SiO １／２ Unit source, R ３ ３ SiO １／２ Unit source, and SiO ４／２ A co-hydrolysis condensate of unit sources, ４／２ 4. The addition-curable silicone resin composition according to claim 1, wherein the unit source is a partial hydrolysis condensate of a tetraalkoxysilane.

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