Polysiloxane composition

Abstract

This invention relates to a silicone composition having high thermal conductivity. This composition comprises silicone oil, (C-1) alumina with an average particle size of 0.1 μm to 4 μm, (C-2) alumina with an average particle size of 5 μm to 30 μm, and (C-3) alumina with an average particle size of 105 μm or more. This composition is usable in the art of thermally conductive materials.

Description

[Technical Field]

[0001] The present invention relates to the technical field of thermally conductive silicone compositions. [Background technology]

[0002] Chinese Patent Application Publication No. 114761492 discloses a curable silicone composition, sample 2 herein, which contains four types of spherical alumina: 35.0 parts of 120 μm, 23.6 parts of 45 μm, 26.4 parts of 2 μm, and 10.5 parts of 0.5 μm. The thermal conductivity of the composition is 7.968 W / mK. The extrusion rate ER of the product is 94 g / min, and the product is of high viscosity.

[0003] Chinese Patent No. 103059576 discloses a silicone thermal pad containing three types of alumina fillers: 3-5 μm, 40-50 μm, or 70-90 μm, where the mass ratio of the three particle sizes of the alumina fillers is (2-3):2:(5-7). The thermal conductivity of this product is 4 w / mK to 5 w / mK.

[0004] Chinese Patent No. 103436019 discloses a thermally conductive gasket containing large-particle alumina (70-100 μm) and small-particle alumina (4-6 μm), with a mass ratio of large-particle to small-particle alumina filler of 2:6. The thermal conductivity of this product is 4 w / mK to 5.5 w / mK. [Overview of the project]

[0005] The objective of the present invention is to obtain a composition with low viscosity and high thermal conductivity under high packing density.

[0006] The present invention Component (A) is an organopolysiloxane, preferably component (A-1) is an organopolysiloxane having two or more alkenyl groups per molecule; In some cases, component (B) is an organohydrogenpolysiloxane having two or more hydrogen atoms directly bonded to a silicon atom, and is contained in such an amount that the number of moles of hydrogen atoms directly bonded to the silicon atom in component (B) is 0.1 to 5 times the number of moles of alkenyl groups derived from component (A-1); Component (C) is a thermally conductive filler, (C-1) 10-25% by weight alumina with an average particle size of 0.1 μm or more and 4 μm or less [for example, the average particle size of (C-1) is 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 μm, and the content is 12% by weight, 14% by weight, 16% by weight, 18% by weight, 20% by weight, 22% by weight, and 24% by weight]; (C-2) 20-35% by weight alumina with an average particle size of 5 μm or more and 30 μm or less [for example, the average particle size of (C-2) is 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 μm, and the content is 20% by weight, 22% by weight, 24% by weight, 26% by weight, 28% by weight, 30% by weight, 32% by weight, 34% by weight, 36% by weight]; (C-3) 50-70% by weight alumina with an average particle size of 105 μm or more [for example, the average particle size of (C-3) is 110, 116, 120, 126, 130, 136, 140, 146, 150, 156, 160 μm, and the content is 50% by weight, 52% by weight, 54% by weight, 56% by weight, 58% by weight, 60% by weight, 62% by weight, 64% by weight]; Includes, In (C-1), (C-2), and (C-3), the total composition is calculated as 100% by weight, component (C); In some cases, component (D) is a platinum group metal-based hardening catalyst, and contains platinum group metal elements in a mass of 0.1 to 1000 ppm relative to component (A-1); A composition comprising, The filling density of the above-mentioned thermally conductive filler is 0.86 or higher, preferably 0.90 or higher, preferably 0.92 or higher, preferably 0.93 or higher, preferably 0.94 or higher, and preferably 0.95 or higher. A composition is provided.

[0007] In this invention, the filling ratio is (total amount of thermally conductive filler / total weight of composition). Generally, a filling ratio of 0.92 or higher is considered a high filling ratio.

[0008] In the above composition, the total amount of all alumina is more than 95% by weight, preferably more than 99% by weight, and more preferably more than 99.9% by weight, and the total amount of thermally conductive filler is calculated as 100% by weight.

[0009] In the above composition, the total amount of all alumina is more than 95% by weight, preferably more than 99% by weight, and more preferably more than 99.9% by weight, and the total amount of filler is calculated as 100% by weight.

[0010] In the above composition, the thermal conductivity of the composition is 7.1 W / mK or higher, preferably 7.2 W / mK or higher, and more preferably 7.5 W / mK or higher.

[0011] In the above composition, (C-1), (C-2), and (C-3) alumina are all spherical or nearly spherical.

[0012] In the above composition, the amount of amorphous alumina is less than 10% by weight, preferably less than 1% by weight, with the total weight of the composition being 100%.

[0013] In the above-described composition, the Al2O3 content in (C-1), (C-2), and (C-3) alumina is 98.1% or more, preferably 99.1% or more.

[0014] In the above composition, component (C) is (C-1) 10-20% by weight alumina with an average particle size of 0.5 μm or more and 3 μm or less. (C-2) 20-35% by weight of alumina with an average particle size of 7 μm to 15 μm. (C-3) 50-65% by weight alumina with an average particle size of 105 μm or more and 200 μm or less. Includes, In (C-1), (C-2), and (C-3), the total composition is calculated as 100% by weight.

[0015] In the above composition, the weight ratio of (C-1) / (C-3) is between 0.15 and 0.40, preferably between 0.17 and 0.38, for example 0.19, 0.21, 0.23, 0.25, 0.27, 0.29, 0.31, 0.33, 0.35.

[0016] In the above composition, the weight ratio of (C-2) / (C-3) is between 0.2 and 0.8, preferably between 0.25 and 0.75, for example 0.3, 0.4, 0.5, 0.6, 0.7.

[0017] In the above composition, the weight ratio of (C-1):(C-2):(C-3) is preferably 1:(1.5 - 2.5):(3.5 - 4.5), more preferably 1:(1.8 - 2.2):(3.8 - 4.2).

[0018] In the above composition, the ratio of the average particle size of (C-2) / (C-1) is between 8 and 18, preferably between 9 and 16, more preferably between 10 and 14, for example 10.5, 11, 11.5, 12, 12.5, 13, 13.5.

[0019] In the above composition, the ratio of the average particle size of (C-3) / (C-1) is between 70 and 250, preferably between 100 and 200, more preferably between 120 and 190, for example 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185.

[0020] In the above composition, the ratio of the average particle size of (C-3) / (C-2) is between 7.0 and 20.0, preferably between 7.5 and 18, more preferably between 8 and 16, for example 8.5, 9, 10, 11, 12, 13, 14, 15.

[0021] The definition of the average particle size refers to the value of the cumulative average particle size (D50 median) measured on a volume basis by a particle size analyzer LS 13 320 manufactured by BECKMAN COULTER.

[0022] The alumina sample (C-1) is prepared by the solution method. 0.1 g of the (C-1) sample is placed in 10 ml of anhydrous ethanol, dispersed using ultrasound (100 W), and stirred for 2 minutes to completely disperse the alumina. Two to three drops of the sample solution are taken and placed in the sample cell of the particle size analyzer.

[0023] The alumina samples (or other thermally conductive fillers with an average particle size of 7 μm or more) for (C-2) and (C-3) are prepared by the dry powder method, and an appropriate amount of the dried sample is placed in the loading cylinder of the particle size analyzer. The loading cylinder is then inserted into the detection slot of the instrument.

[0024] In the present invention, the particle size distribution of alumina (C-1), (C-2), and (C-3) is unimodal, or their particle sizes satisfy a unimodal or nearly unimodal particle size distribution.

[0025] In the present invention, a nearly unimodal particle size distribution means that, although there may be two or more peaks in the volume integral map of the measurement sample, the volume integral area of ​​the main peak accounts for more than 80%, preferably more than 85%, more preferably more than 90%, and more preferably more than 95% of the total volume integral area.

[0026] Spherical fillers are fillers whose external shape is typically spherical, and are obtained by treating amorphous fillers through chemical and / or physical (including heat treatment) processes.

[0027] Spherical alumina is a product obtained after heat treatment of amorphous alumina, and its external shape is usually spherical. The sphericity is 0.90 or higher, preferably 0.95 or higher.

[0028] Preferably, the thermally conductive silicone composition further contains component (E) in an amount of 1 to 100 parts by mass, preferably 1 to 50 parts by mass, and preferably 1 to 10 parts by mass, per 100 parts by mass of component (A).

[0029] Component (E) is selected from one or more of the following (E-1): (E-1) is an alkoxysilane compound represented by the following formula (1): [ka] (In the formula, Each R 1 This independently represents an alkyl group having 1 to 24 carbon atoms, preferably 6 to 24 carbon atoms, more preferably 12 to 18 carbon atoms. Each R 2 This independently represents an unsubstituted or substituted hydrocarbon group (preferably methyl or ethyl) having 1 to 10 carbon atoms. Each R 3 This independently represents an alkyl group having 1 to 6 carbon atoms (preferably methyl or ethyl), (where a represents an integer between 1 and 3, and b represents an integer between 0 and 2, and a + b is an integer between 1 and 3.) That is the case.

[0030] In the present invention, the weight ratio of component (C) to component (E-1) is between 100 and 800, preferably between 200 and 500, and more preferably between 200 and 400.

[0031] Furthermore, the thermally conductive silicone composition is a two-component composition, and the viscosity of either component is 10S. -1 At 25°C, the pressure is preferably 300,000 mPa·s or less, more preferably 250,000 mPa·s or less, more preferably 230,000 mPa·s, and more preferably 220,000 mPa·s or less.

[0032] Such thermally conductive silicone compositions exhibit excellent moldability.

[0033] Furthermore, the present invention provides a heat-conductive silicone cured product comprising a cured product of a heat-conductive silicone composition.

[0034] Such heat-conductive silicone cured products have excellent heat conductivity.

[0035] As described above, the thermally conductive silicone composition of the present invention is a silicone composition containing a specific organopolysiloxane, a hydrogenpolysiloxane, and a thermally conductive filler, which is carefully prepared and blended, so that the thermally conductive filler is densely packed into the substrate. This makes it possible to provide a thermally conductive silicone composition that can produce a thermally conductive silicone cured product having a high thermal conductivity of 7.2 W / mK or higher. Such a thermally conductive silicone cured product is particularly useful as a thermal conductive material interposed at the interface between the hot surface of a heat-generating electronic component and a heat dissipation member such as a heat sink or circuit board, for cooling electronic components by thermal conduction.

[0036] As described above, there has been a need for the development of thermally conductive silicone cured products (thermally conductive resin molded products) that have high thermal conductivity and good processability, as well as thermally conductive silicone compositions for molding these cured products.

[0037] As a result of diligent research to achieve the above objective, the inventors have discovered that by carefully adjusting and blending a silicone composition containing specific organopolysiloxanes and hydrogenpolysiloxanes, and by filling a substrate material with a high density of thermally conductive filler, a thermally conductive silicone cured product with a high thermal conductivity of 7.2 W / m·K or higher can be obtained.

[0038] Specifically, the present invention is a thermally conductive silicone composition comprising the following:

[0039] Component (A): Organopolysiloxane, preferably component (A-1): Alkenyl group-containing organopolysiloxane The above component (A) is an organopolysiloxane. Component (A) functions as the main component of the composition of the present invention. Generally, the main chain portion is usually composed of repeated basic diorganosiloxane units, but this molecular structure may include a partially branched structure or a cyclic structure. Nevertheless, the main chain is preferably a linear diorganopolysiloxane from the viewpoint of the physical properties of the cured product, such as mechanical strength.

[0040] The above component (A-1) is an organopolysiloxane-containing alkenyl group having two or more silicon atom-bonded alkenyl groups per molecule. Component (A-1) functions as the main component of the composition of the present invention. Generally, the main chain portion is usually composed of repeated basic diorganosiloxane units, but this molecular structure may include a partially branched structure or a cyclic structure. Nevertheless, the main chain is preferably a linear diorganopolysiloxane from the viewpoint of the physical properties of the cured product, such as mechanical strength.

[0041] Functional groups bonded to silicon atoms include unsubstituted or substituted monovalent hydrocarbon groups. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, and biphenylyl; aralkyl groups such as benzyl, phenylethyl, phenylpropyl, and methylbenzyl; and groups obtained by substituting some or all of the hydrogen atoms bonded to the carbon atoms of these groups with cyano groups or halogen atoms such as fluorine, chlorine, and bromine. Examples of such substituents include chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups. Typical examples of functional groups include those having 1 to 10 carbon atoms, with particularly representative examples being those having 1 to 6 carbon atoms. Preferred examples of functional groups include unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms (such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, and cyanoethyl groups), as well as unsubstituted or substituted phenyl groups (such as phenyl, chlorophenyl, and fluorophenyl groups). In addition, not all functional groups bonded to the silicon atom need to be the same.

[0042] Furthermore, alkenyl groups typically have 2 to 8 carbon atoms. Examples include vinyl groups, aryl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, and cyclohexenyl groups. Among these, lower alkenyl groups such as vinyl groups and aryl groups are preferred, and vinyl groups are particularly preferred. The number of alkenyl groups must be two or more per molecule, and it is preferable that each of the above alkenyl groups is bonded only to silicon atoms at the end of the molecular chain, which allows the resulting cured product to have good flexibility.

[0043] The organopolysiloxane, which is component (A), has a viscosity at 25°C preferably in the range of 10 to 100,000 mPa·s, particularly preferably in the range of 50 to 50,000 mPa·s, more preferably in the range of 50 to 20,000 mPa·s, more preferably in the range of 50 to 2,000 mPa·s, more preferably in the range of 50 to 1,000 mPa·s, more preferably in the range of 50 to 500 mPa·s, and more preferably in the range of 50 to 300 mPa·s. The organopolysiloxane, which is component (A), is preferably polydimethylsiloxane.

[0044] Component (A-1): The alkenyl group-containing organopolysiloxane has a viscosity in the range of 10 to 100,000 mPa·s at 25°C, particularly preferably 50 to 10,000 mPa·s, more preferably 50 to 1,000 mPa·s, and more preferably 50 to 200 mPa·s. When the viscosity is 10 mPa·s or higher, the resulting composition has good storage stability. On the other hand, when the viscosity is 100,000 mPa·s or lower, the resulting composition has good spreadability. The alkenyl group-containing organopolysiloxane, which is component (A-1), is preferably a vinyl-terminated polydimethylsiloxane.

[0045] The organopolysiloxane of component (A) may be used alone, or two or more types with different viscosities may be used in combination.

[0046] The alkenyl group-containing organopolysiloxane of component (A-1) may be used alone, or two or more types with different viscosities may be used in combination.

[0047] Optional component (B): Organohydrogenpolysiloxane Component (B) is an organohydrogenpolysiloxane in which at least two, preferably 2 to 100, hydrogen atoms per molecule are directly bonded to silicon atoms (Si-H groups). This component functions as a crosslinking agent for component (A-1). Specifically, the Si-H groups in component (B) are added to the alkenyl groups in component (A-1) by a hydrosilylation reaction promoted by a platinum group metal hardening catalyst, which is component (D) described later, thereby forming a three-dimensional network structure with a crosslinking structure. Note that if the number of Si-H groups per molecule in component (B) is less than two, hardening will not occur.

[0048] The organohydrogenpolysiloxane used is the following average structural formula (4): [ka] This may be shown, but is not limited to.

[0049] In the formula, each R' independently represents a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group that does not contain fatty acid unsaturated bonds, and at least two R' are hydrogen atoms. e represents an integer of 1 or more.

[0050] Examples of unsubstituted or substituted monovalent hydrocarbon groups in formula (4) that do not contain an aliphatic unsaturated bond other than hydrogen as R' include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, and biphenylyl; aralkyl groups such as benzyl, phenylethyl, phenylpropyl, and methylbenzyl; and groups obtained by substituting some or all of the hydrogen atoms bonded to the carbon atoms in these groups with cyano groups or halogen atoms such as fluorine, chlorine, and bromine. Examples of such substituents include chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups. Typical examples of monovalent hydrocarbon groups include those with 1 to 10 carbon atoms, and particularly typical examples include those with 1 to 6 carbon atoms. Preferred examples of monovalent hydrocarbons include unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms, such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, and cyanoethyl groups; as well as unsubstituted or substituted phenyl groups, such as phenyl, chlorophenyl, and fluorophenyl groups. Furthermore, not all R groups need to be the same.

[0051] The amount of component (B) added is such that the amount of Si-H groups derived from component (B) is 0.1 to 5.0 moles per mole of alkenyl groups derived from component (A-1) (i.e., the number of moles of hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups derived from component (A-1)), preferably 0.3 to 2.0 moles, and more preferably 0.5 to 1.0 moles. If the amount of Si-H groups derived from component (B) is less than 0.1 moles per mole of alkenyl groups derived from component (A-1), hardening may not occur, or the strength of the hardened product may be insufficient, resulting in a molded product that cannot maintain its shape and is difficult to handle. On the other hand, if it exceeds 5.0 moles, the hardened product may lose its flexibility and become brittle.

[0052] The organopolysiloxane of component (B) above may be used alone or in combination of two or more types with different viscosities.

[0053] In the above composition, component (B) includes component (B-1) and component (B-2).

[0054] The organic hydrogen-containing polysiloxane of component (B-1) is an organic hydrogen-containing polysiloxane having at least 3, preferably 3 to 100, hydrogen atoms (Si-H groups) directly bonded to silicon atoms in one molecule, and its hydrogen content is 0.5 to 4 mmol / g, preferably 0.8 to 3 mmol / g, more preferably 1.1 to 2.7 mmol / g, and even more preferably 1.5 to 2.3 mmol / g.

[0055] The organic hydrogen-containing polysiloxane of component (B-2) is an organic hydrogen-containing polysiloxane having two hydrogen atoms (Si-H groups) directly bonded to a silicon atom in one molecule, and the hydrogen content is 0.01 to 1.5 mmol / g, preferably 0.1 to 1.2 mmol / g, more preferably 0.3 to 1.0 mmol / g, and even more preferably 0.4 to 0.8 mmol / g.

[0056] In the above composition, component (B) includes (B-1) and (B-2), and the amount of component (B-1) is 0.5 to 3% by weight, preferably 1.5 to 2.8% by weight, when calculated with component (A-1) as 100% by weight.

[0057] In the above description, component (B) includes (B-1) and (B-2), and the amount of component (B-2) is 10 to 50% by weight, preferably 20 to 40% by weight, when component (A-1) is calculated as 100% by weight.

[0058] Ingredient (C): Thermally conductive filler The present invention overcomes the problems of the prior art by carefully preparing and formulating a silicone composition containing a specific organopolysiloxane, a hydrogenpolysiloxane, and a thermally conductive filler, and densely filling a substrate with the thermally conductive filler. The present invention provides a thermally conductive silicone composition that yields a thermally conductive silicone cured product with high thermal conductivity and excellent processability.

[0059] Preferably, component (C) is as follows: 10-25% by weight (C-1) alumina with an average particle size of 0.1 μm or more and 3 μm or less [for example, the average particle sizes are 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, and 2.8 μm]. 20-35 wt% (C-2) alumina with an average particle size of 7 μm or more and 20 μm or less [for example, with an average particle size of 6, 8, 10, 12, 14, 16, 18 μm], and 50-65% by weight (C-3) alumina with an average particle size of 105 μm to 250 μm [For example, the average particle sizes are 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 180, 190, 210, 220, and 230 μm] Includes, The amounts of (C-1), (C-2), and (C-3) above are calculated based on 100% by weight of the total composition.

[0060] In this way, particles containing alumina of different particle sizes as the main component are precisely combined. Specifically, components of small-diameter particles (C-1), medium-diameter particles (C-2), and large-diameter particles (C-3) are combined in a carefully tested ratio. This allows the small and medium-diameter particles to fill the gaps between the large-diameter particles, enabling high-density filling within the substrate.

[0061] On the other hand, if the particle sizes of the alumina in components (C-1), (C-2), and (C-3) are outside the range, or if the composition ratio of components (C-1), (C-2), and (C-3) is outside the range, these hinder the preparation of the thermally conductive silicone composition, resulting in a thermally conductive silicone cured product with a thermal conductivity of 7.2 W / m·K or higher and a relatively low viscosity.

[0062] Note that each average particle size is the volume-based cumulative average particle size (D50 median) measured using a BECKMAN COULTER LS 13 320 particle size analyzer.

[0063] The small-diameter alumina (filler) component (C-1) is combined with the medium- and large-diameter alumina components (C-2) and (C-3) to enhance the thermal conductivity and fluidity of the composition and prevent the precipitation of the filler. The average particle size of the small-diameter alumina is 0.1 μm or more and 4 μm or less, preferably 0.5 μm or more and 2 μm or less. If the average particle size is outside this range, the effect of enhancing the thermal conductivity and fluidity of the composition and preventing the precipitation of the filler will not be obtained when combined with components (C-2) and (C-3). One or more types of alumina of component (C-1) may be used as a composite material.

[0064] Component (C-1) is blended in amounts of 10-25% by weight, preferably 10-23% by weight, more preferably 10-18% by weight, for example 12%, 14%, 16%, 17%, and 22% by weight. Component (C-2) is blended in amounts of 22-33% by weight, preferably 23-30% by weight, more preferably 25-30% by weight, for example 22%, 24%, 26%, 28%, and 32% by weight. If the mass ratio is outside the range, the effect of increasing the thermal conductivity and fluidity of the composition and preventing precipitation of the filler caused by blending with component (C-3) will not be obtained.

[0065] The large-diameter alumina (filler) component (C-3) can significantly improve thermal conductivity. The average particle size of the large-diameter alumina is 105 μm to 200 μm, preferably 11 μm to 160 μm. If the average particle size is outside this range, the effect of improving thermal conductivity will decrease, the viscosity of the composition will increase, or the processability will decrease. One or more types of alumina of component (C-3) may be used as a composite material.

[0066] Component (C-3) is blended in amounts of 50-65% by weight, preferably 52-68% by weight, more preferably 55-63% by weight, preferably 55-60% by weight, for example, 56%, 58%, 62%, or 64% by weight. If the mass ratio is outside this range, the effect of enhancing thermal conductivity will decrease, the viscosity of the composition will increase, or the processability will decrease.

[0067] The amounts of (C-1), (C-2), and (C-3) above are calculated based on 100% by weight of the total composition.

[0068] Thermally conductive fillers generally do not contain fumed silica or precipitated silica.

[0069] In the composition of the present invention, the fumed silica and / or precipitated silica content is calculated based on 100% by weight of the total composition, and is preferably less than 0.1% by weight.

[0070] The type of thermally conductive filler is not particularly limited. For example, nonmagnetic metals such as copper and aluminum; metal oxides such as magnesia, corcoser, beryllia, titania, or zirconia; metal nitrides such as aluminum nitride, silicon nitride, or boron nitride; metal hydroxides such as aluminum hydroxide and magnesium hydroxide, artificial diamond, silicon carbide, and other materials generally considered to be thermally conductive can be used. Furthermore, particle sizes from 0.1 to 200 μm can be used. One or more of these materials may be used as a composite.

[0071] Component (C) must be blended in an amount of 800 to 4000 parts by mass, preferably 900 to 2000 parts by mass, and more preferably 900 to 1500 parts by mass, per 100 parts by mass of component (A). If the blending amount is less than 800 parts by mass, the resulting composition will have low thermal conductivity. If the blending amount exceeds 2000 parts by mass, the kneading operability will be impaired, and the cured product will become extremely brittle. To obtain a product with higher thermal conductivity, the filling density of the composition is generally 0.92 or higher.

[0072] Optional component (D): Platinum group metal curing catalyst Component (D) is a platinum group metal-based hardening catalyst and is not particularly limited as long as the catalyst promotes the addition reaction between the alkenyl group derived from component (A-1) and the Si-H group derived from component (B). Examples of catalysts include well-known catalysts used in hydrosilylation reactions. Specific examples include elemental platinum group metals such as platinum (including platinum black), rhodium, and palladium, platinum chloride, chloroplatinic acid, and platinum chloride salts such as H2PtCl4.nH2O, H2PtCl6.nH2O, NaHPtCl6.nH2O, KHPtCl6.nH2O, Na2PtCl6.nH2O, K2PtCl4.nH2O, PtCl4.nH2O, PtCl2, and Na2HPtCl4.nH2O (where n is an integer from 0 to 6, preferably 0 or 6); alcohol-modified chloroplatinic acid (see U.S. Patent No. 3,220,972); and chloroplatinic acid-olefin complexes (U.S. See Japanese Patent No. 3159601, No. 3159662, and No. 3775452; Examples include those obtained by supporting platinum group metals such as platinum black or palladium on a carrier such as alumina, silica, or carbon; rhodium-olefin complexes, chlorotris(triphenylphosphine)rhodium (Wilkinson catalyst); complexes of chlorplatinate salts and vinyl group-containing siloxanes, especially vinyl group-containing siloxanes that do not contain cyclic siloxanes; complexes of chlorplatinum, chloroplatinic acid, or chloroplatinic acid to which vinyl group-containing siloxanes have been added, especially those that do not contain vinyl group-cyclic siloxanes; and so on.

[0073] Component (D) is used in an amount such that the platinum group metal element content is 0.1 to 1000 ppm by mass relative to component (A-1). If the content is less than 0.1 ppm, sufficient catalytic activity cannot be obtained. If the content exceeds 1000 ppm, it only increases costs without enhancing the effect of promoting the addition reaction, and catalyst may remain in the cured product, potentially reducing its insulating properties.

[0074] Ingredient (E): Surface treatment agent By blending with component (E) which is a surface treatment agent, the heat conductive filler of component (C) is made water-repellent, and when adjusting the composition, the wettability by the organopolysiloxane of component (A) is improved, and the heat conductive filler of component (C) can be uniformly dispersed in the matrix of component (A). As component (E), component (E-1) and component (E-2) described below are particularly preferable.

[0075] Component (E-1): An alkoxysilane compound represented by the following formula (3):

Chemical formula

[0076] Examples of the alkyl group represented by R 1 in formula (1) include hexyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group and the like. When the number of carbon atoms of the alkyl group represented by R 1 satisfies the range of 6 to 15, the wettability of component (A) is sufficiently improved, and excellent handleability is realized. Furthermore, this composition is advantageous for low-temperature characteristics.

[0077] R 2Examples of substituted or substituted hydrocarbon groups represented by include alkyl groups (methyl, ethyl, vinyl, propyl, isopropyl, and other alkyl groups, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl groups, etc.), cycloalkyl groups (cyclopentyl, cyclohexyl, and cycloheptyl groups, etc.), allyl groups (phenyl, tolyl, xylyl, naphthyl, and biphenylyl groups, etc.), aralkyl groups (benzyl, phenylethyl, phenylpropyl, and methylbenzyl groups, etc.), and groups obtained by substituting some or all of the hydrogen atoms bonded to the carbon atoms of these groups with cyano groups, halogen atoms (fluorine, chlorine, and bromine, etc.) or similar entities. Examples of such substituents include chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, and 3,3,4,4,5,5,6,6-nonafluorohexyl groups. Common examples of monovalent hydrocarbons include those with 1 to 10 carbon atoms, with particularly typical examples being those with 1 to 6 carbon atoms. Preferred examples of monovalent hydrocarbon groups include unsubstituted or substituted alkyl groups (methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, cyanoethyl, etc.) and unsubstituted or substituted phenyl groups (phenyl, chlorophenyl, fluorophenyl, etc.) having 1 to 3 carbon atoms.

[0078] R 3 Examples of these groups include methyl, ethyl, propyl, butyl, and hexyl groups. Furthermore, a and b are not particularly limited, as long as a is an integer between 1 and 3, b is an integer between 0 and 2, and a+b is an integer between 1 and 3. Preferably, a is 1 and b is 0.

[0079] Component (E-1) is preferably an alkoxysilane containing a C6-18 long-chain alkyl group, more preferably a trialkoxysilane containing a C6-18 long-chain alkyl group, and more preferably hexadecyltrimethoxysilane, hexadecyltriethoxysilane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, dodecyltrimethoxysilane, or dodecyltriethoxysilane.

[0080] As a surface treatment agent for component (E), either or both of component (E-1) can be blended individually or in combination. Here, the amount of component (E) is preferably 1 to 100 parts by mass, particularly preferably 1 to 50 parts by mass, preferably 1 to 30 parts by mass, and more preferably 1 to 10 parts by mass, with component (A) being 100 parts by mass.

[0081] In the above composition, the amount of (E-1) is greater than 95% by weight, preferably greater than 99% by weight, and more preferably greater than 99.9% by weight, when the total amount of the surface treatment agent of component (E) is calculated as 100% by weight.

[0082] Component (F): Characterizing agent Component (F) is an organopolysiloxane represented by the following formula (3), having a viscosity of 10 to 100,000 mPa·s at 25°C: [ka] (In the formula, Each R 5 This independently represents a monovalent hydrocarbon that has 1 to 10 carbon atoms and does not possess aliphatic unsaturated bonds. (d is an integer between 5 and 2000) It is possible to add it.

[0083] Component (F) is appropriately used to impart properties such as viscosity modifiers and plasticizers to the thermally conductive silicone composition, but is not limited to this. One of these may be used alone, or two or more may be used in combination.

[0084] Each R 5 R independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms. 5 Examples include alkyl groups (methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl groups), cycloalkyl groups (cyclopentyl, cyclohexyl, and cycloheptyl groups), aryl groups (phenyl, tolyl, xylyl, naphthyl, and biphenylyl groups), aralkyl groups (benzyl, phenylethyl, phenylpropyl, and methylbenzyl groups), and groups obtained by substituting some or all of the hydrogen atoms bonded to the carbon atoms of these groups with cyano groups, halogen atoms (fluorine, chlorine, and bromine, etc.) or similar entities. Examples of such substituents include chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, and 3,3,4,4,5,5,6,6-nonafluorohexyl groups. Typical examples of hydrocarbon groups include those having 1 to 10 carbon atoms, with particularly typical examples being those having 1 to 6 carbon atoms. Preferred examples of monovalent hydrocarbons include unsubstituted or substituted alkyl groups (methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, and cyanoethyl groups, etc.) and unsubstituted or substituted phenyl groups (phenyl, chlorophenyl, and fluorophenyl groups, etc.) having 1 to 3 carbon atoms. Methyl and phenyl groups are particularly preferred.

[0085] d is preferably an integer between 5 and 2000, and particularly preferably an integer between 10 and 1000, from the viewpoint of the required viscosity.

[0086] Furthermore, the viscosity at 25°C is preferably 10 to 100,000 mPa.s, and particularly preferably 100 to 10,000 mPa.s. When the viscosity is 10 mPa.s or higher, the cured product hardly leaks oil. When the viscosity is 100,000 mPa.s or lower, the resulting thermally conductive silicone composition has appropriate flexibility.

[0087] When component (F) is added to the thermally conductive silicone composition of the present invention, the amount added is not particularly limited, and is approximately 10 to 100 parts by mass, with component (A) being 100 parts by mass. If the amount added is within this range, the good fluidity and mobility of the thermally conductive silicone composition before curing are maintained, and it becomes easy to fill it with the thermally conductive filler component (C).

[0088] In the thermally conductive silicone composition of the present invention, the amount of component (F) used is preferably less than 0.1 parts by mass, more preferably less than 0.01 parts by mass, based on 100 parts by mass of component (A). This method prevents oil leakage and contamination of the substrate of the thermally conductive silicone composition.

[0089] Optional component (G): Reaction inhibitor Component (G) can be an addition reaction inhibitor. Any known addition reaction inhibitor used in typical addition-curing silicone compositions can be used. Examples include acetylene compounds (such as 1-ethynyl-1-hexanol and 3-butyne-1-ol), various nitrogen compounds, organophosphorus compounds, oxime compounds, and organochlorine compounds. When component (G) is included, the amount used is 0.01 to 1 part by mass, more preferably 0.1 to 0.8 parts by mass, based on 100 parts by mass of component (A-1). With this amount, the curing reaction proceeds sufficiently without impairing molding efficiency.

[0090] Other ingredients The thermally conductive silicone composition of the present invention may be further formulated with other components as needed. Examples of optional components that can be incorporated include heat resistance modifiers such as iron oxide and cerium oxide, viscosity modifiers such as silica, colorants, and mold release agents.

[0091] Embodiment Thermally conductive silicone cured product and method for manufacturing the same The thermally conductive silicone cured product (thermally conductive resin molded product) in the present invention is a cured product of the thermally conductive silicone composition described above. The curing conditions for the cured product (molded product) of the thermally conductive silicone composition may be the same as those for known addition-curable silicone rubber compositions. For example, the thermally conductive silicone composition cures sufficiently at room temperature, but may be heated if necessary. Preferably, the thermally conductive silicone composition is work-cured at 100-120°C for 8-12 minutes, or preferably cured at room temperature for 7 days or less, or cured at room temperature for 1 day or less. Such cured products (molded products) of the present invention have excellent thermal conductivity.

[0092] Thermal conductivity of molded material The molded product of the present invention preferably has a thermal conductivity of 7.2 W / mK or higher, as measured at 25°C. Products with a thermal conductivity of 7.2 W / mK or higher can be applied to heat-generating components that generate a large amount of heat. Such thermal conductivity can be adjusted by adjusting the combination of the type and particle size of the thermally conductive filler.

[0093] Hardness of molded product The molded product of the present invention was tested using a Zwick hardness tester. This hardness can be adjusted by changing the ratio of component (A-1) to component (B), thereby adjusting the crosslinking density.

[0094] According to DIN 53019, an Anton Paar MCR302 apparatus was used to measure the kinematic and static viscosity of the composition of the present invention.

[0095] The components (A) to (G) used in the following examples and comparative examples are as follows:

[0096] Ingredient (A): Component (A-1) is an organopolysiloxane represented by the following formula (5). [ka] In the formula, X represents a vinyl group, and n represents the viscosity value at 120 mPa·s.

[0097] Ingredient (B): (B-1) is the side chain hydrogen polysiloxane, represented by the following formula (6), with a hydrogen content of 1.7 mmol / g. [ka]

[0098] (B-2) is a hydrogen-terminated polysiloxane represented by the following formula (7). [ka] In the formula, X represents hydrogen. The hydrogen content is 0.53 mmol / g.

[0099] Ingredients (C): (C-1) Nearly spherical alumina with an average particle size of 0.8 μm (C-2) Spherical alumina with an average particle size of 10 μm (C-3-1) Spherical alumina with an average particle size of 120 μm (C-3-1) Spherical alumina with an average particle size of 150 μm (C-4) Spherical alumina with an average particle size of 90 μm.

[0100] Ingredients (D): A 5% by weight solution of chloroplatinic acid with 2-ethylhexanol.

[0101] Ingredients (E): Cetyltrimethoxysilane.

[0102] Ingredients (G): Ethinylcyclohexanol as an addition reaction inhibitor.

[0103] The above materials are provided by Wacker Chemie AG.

[0104] The above components were added in predetermined amounts as shown in the examples and comparative examples in Table 1 below, and mixed in a planetary mixer for 60 minutes.

[0105] Molding method After mixing, the compositions shown in Table 1 were obtained.

[0106] The compositions obtained in Table 1 were poured into molds measuring 60 mm × 60 mm × 6 mm and molded using a press molding machine at 100°C for 60 minutes.

[0107] Method for evaluating thermal conductivity The compositions obtained in the examples and comparative examples in Table 1 were cured into sheets with thicknesses of 2 mm, 4 mm, and 6 mm under conditions of 100°C for 60 minutes.

[0108] The thermal conductivity of each composition was measured at 50°C using a TIM tester 1300-1400 compliant with ASTM 5470, with the sheets being used.

[0109] hardness The compositions obtained in the following examples and comparative examples were cured into 6 mm thick sheets as described above. Two sheets made from each composition were stacked and measured using a Zwick hardness tester to calculate the Shore 00 hardness value.

[0110] Table 1 Thermally conductive caulking compositions [Table 1]

[0111] Table 2 Thermal conductivity [Table 2]

[0112] Table 1 compares Comparative Example 1, which contains a low content of large-particle-sized alumina of the same type with small, medium, and large particle sizes, with Example 6. The resulting composition of Comparative Example 1 has high viscosity and low thermal conductivity.

[0113] Table 1 shows that when the aluminum oxide particles are of the same size (small, medium, and large), a comparison of Comparative Example 2 and Example 6 reveals that the composition obtained in Comparative Example 2 (using aluminum oxide with an average particle size of 90 μm) has higher viscosity and lower thermal conductivity.

[0114] In Table 1, when the types and amounts of small, medium, and large alumina are not within the appropriate range, Comparative Example 3 has the highest viscosity and the lowest thermal conductivity.

[0115] The product obtained in Example 6 has low viscosity, high thermal conductivity, a Shore hardness of 00 and 60, and appropriate elasticity.

Claims

1. Component (A) is an organopolysiloxane, preferably component (A-1) is an organopolysiloxane having two or more alkenyl groups per molecule; In some cases, component (B) is an organohydrogenpolysiloxane having two or more hydrogen atoms directly bonded to a silicon atom, and is contained in such an amount that the number of moles of hydrogen atoms directly bonded to the silicon atom in component (B) is 0.1 to 5.0 times the number of moles of alkenyl groups derived from component (A-1); Component (C) is a thermally conductive filler, (C-1) Alumina with an average particle size of 0.1 μm or more and 4 μm or less, in an amount of 10 to 25% by weight. (C-2) Alumina with an average particle size of 5 μm or more and 30 μm or less, 20 to 35% by weight, (C-3) 50-70% by weight of alumina with an average particle size of 105 μm or more, Includes, In (C-1), (C-2), and (C-3), the overall composition is calculated as 100% by weight, component (C); In some cases, component (D) is a platinum group metal-based hardening catalyst, wherein the platinum group metal element is present in a mass of 0.1 to 1000 ppm relative to component (A-1); A composition comprising, The filling rate of the thermally conductive filler is 0.86 or higher, preferably 0.90 or higher, preferably 0.92 or higher, preferably 0.93 or higher, preferably 0.94 or higher, and preferably 0.95 or higher. composition.

2. The composition according to claim 1, wherein the total amount of all alumina is greater than 95% by weight, preferably greater than 99% by weight, and more preferably greater than 99.9% by weight, and the total amount of filler is calculated as 100% by weight.

3. The composition according to claim 1 or 2, wherein the thermal conductivity of the composition is 7.1 W / mK or higher, preferably 7.2 W / mK or higher, and more preferably 7.5 W / mK or higher.

4. Component C is (C-1) 10 to 20% by weight of alumina with an average particle size of 0.5 μm or more and 3 μm or less, (C-2) Alumina with an average particle size of 7 μm or more and 15 μm or less, 20 to 35% by weight, (C-3) 50-65% by weight of alumina with an average particle size of 105 μm to 200 μm. Includes, In (C-1), (C-2), and (C-3), the total composition is calculated as 100% by weight. The composition according to any one of claims 1 to 3.

5. The composition according to any one of claims 1 to 4, wherein the weight ratio of (C-2) / (C-3) is 0.2 to 0.8, preferably 0.25 to 0.

75.

6. The composition according to any one of claims 1 to 5, wherein the weight ratio of (C-1):(C-2):(C-3) is preferably 1:(1.5-2.5):(3.5-4.5), more preferably 1:(1.8-2.2):(3.8-4.2).

7. The composition according to any one of claims 1 to 6, wherein the ratio of the average particle size of (C-3) / (C-1) is 70 to 250, preferably 100 to 200, and more preferably 120 to 190.

8. The composition according to any one of claims 1 to 7, wherein the ratio of the average particle size of (C-3) / (C-2) is 7.0 to 20.0, preferably 7.5 to 18, and more preferably 8 to 16.

9. The aforementioned composition is a two-component composition, The viscosity of any of the components is 10S at 25°C. －１ The pressure is 300,000 mPa·s or less, preferably 250,000 mPa·s or less, more preferably 230,000 mPa·s or less, and more preferably 220,000 mPa·s or less. The composition according to any one of claims 1 to 8.

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