Polysiloxane composition

Abstract

The invention relates to an organic silicon composition with low viscosity and thixotropic index under the condition of high filling rate. The organic silicon composition contains vinyl silicone oil, a heat-conducting filler, a silane compound and polysiloxane. The composition can be used in the technical field of heat conduction materials.

Description

Technical Field

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

[0002] CN113840881A discloses a thermal interface material containing a silicone oil capped with a long-chain alkyl group at one end and a hydroxyl group, a long-chain alkyl silicone oil, a silicone oil capped with a long-chain alkyl vinyl group, and a thermally conductive filler. In particular, the composition may further contain one or more silane coupling agents. The silicone oil capped with a long-chain alkyl group at one end and a hydroxyl group contains a long-chain alkyl side chain. The general formula of the silane coupling agent is: Y-(CH2) n -Si-X3, where Y is an organic functional group, X is a hydrolyzable group, and n is 10-20. That is, CN113840881A discloses that a silicone oil capped with a long-chain alkyl group at one end and a hydroxyl group and a long-alkyl silane coupling agent can be used in a thermal interface composition, where the number of carbon atoms in the long alkyl group is usually greater than or equal to 10.

[0003] US6169142 discloses a thermally conductive silicone rubber composition containing vinyl silicone oil, hydrogen-containing silicone oil, an alumina thermally conductive filler, and a long-chain alkyl alkoxysilane R 1 a Si(OR 2 ) (4-a) , where R 1 is a C6-20 hydrocarbon group. Table 2 specifically lists the comparative experiments of Example 6 and Comparative Example 2. The viscosity of the product of Example 6 (obtained with hexyltrimethoxysilane) at 100 °C is lower than that of Comparative Example 2 (obtained with methyltriethoxysilane).

[0004] Currently, when the potting device has a complex structure and narrow gaps, it is necessary to obtain a composition with lower flowability at different shear rates. Better fluidity can reduce the disadvantage of insufficient flow of the potting adhesive and avoid air bubbles and shrinkage cavities. Summary of the Invention

[0005] The present invention discloses a composition having a lower thixotropic index (lower thixotropy) under high load. And under high-shear and low-shear conditions, the composition has a lower viscosity.

[0006] In the present invention, high shear refers to a shear rate of 10 (1 / s); and low shear refers to a shear rate of 1 (1 / s).

[0007] The present invention provides a composition containing:

[0008] Component (A), which is an organopolysiloxane, preferably component (A-1), which is an organopolysiloxane having two or more alkenyl groups per molecule;

[0009] Optionally present component (B), which is an organohydrogenpolysiloxane having two or more hydrogen atoms directly bonded to silicon atoms, and the content thereof is such that the number of moles of hydrogen atoms directly bonded to silicon atoms in component (B) is 0.1 to 5.0 times the number of moles of alkenyl groups derived from component (A-1);

[0010] Component (C), which is a heat conductive filler,

[0011] wherein the filling rate of the heat conductive filler is greater than or equal to 0.80, preferably greater than or equal to 0.84, preferably greater than or equal to 0.88, preferably greater than or equal to 0.89, preferably greater than or equal to 0.90;

[0012] Optionally present component (D), which is a platinum group metal-based curing catalyst, and the content of platinum group metal elements is 0.1 to 1,000 ppm based on component (A-1) by mass,

[0013] Component (E-1), which is an alkoxysilane compound represented by the following formula (1); and

[0014] R 1 a R 2 b Si(OR 3 ) 4-a-b (1)

[0015] In formula (1),

[0016] each R 1 independently represents an alkyl group having 1 to 3 carbon atoms, preferably methyl or ethyl,

[0017] each R 2 independently represents an unsubstituted or substituted hydrocarbon group having 1 to 3 carbon atoms, preferably methyl or ethyl,

[0018] each R 3 independently represents an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, more preferably methyl or ethyl,

[0019] a represents an integer from 1 to 3, and b represents an integer from 0 to 2, provided that a + b is an integer from 1 to 3,

[0020] Component (E-2), which is a polysiloxane represented by the following general formula (2),

[0021] R 1 3SiO-(R 1 2SiO) m -Si-R 1 (3-n) R 2 n (2)

[0022] In formula (2),

[0023] each R 1 independently represents a hydrocarbon group having 1 to 6 carbon atoms, preferably an alkyl or alkenyl group having 1 to 3 carbon atoms, preferably methyl, ethyl, propyl, vinyl, more preferably methyl;

[0024] each R 2 independently represents -OH or -(CH2) p OH, p is an integer from 1 to 3, preferably a hydroxyl group;

[0025] m ≤ 50, more preferably m ≤ 20, more preferably 6 ≤ m ≤ 18, such as 8, 10, 12, 14, 16;

[0026] n is an integer, preferably n is 1 - 3, more preferably n is 1.

[0027] For the composition as described above, according to DIN53019, the viscosity of component (E - 2) at 25 °C is 500 mPa·s or lower, preferably 300 mPa·s or lower, more preferably 100 mPa·s or lower, more preferably 50 mPa·s or lower, more preferably between 10 - 40 mPa·s.

[0028] According to NMR measurement, the Mn of component (E - 2) is less than or equal to 5000 g / mol, preferably less than or equal to 3000 g / mol, more preferably less than or equal to 2000 g / mol, more preferably between 500 - 1500 g / mol.

[0029] According to NMR measurement, the hydroxyl value of component (E - 2) is 10% by weight or less, preferably 5% by weight or less, more preferably 3% by weight or less, more preferably 1.0 - 2.8% by weight.

[0030] For the composition as described above, its thixotropic index (Ti) at 25 °C is 1.70 or lower, preferably 1.05 - 1.70, more preferably 1.20 - 1.70, more preferably 1.30 - 1.55. When it exceeds 1.70, insufficient leveling may occur, and unfilled gaps may be generated during potting of a device with slits, which is not preferred.

[0031] In the present invention, the thixotropic index (Ti) is the ratio of the viscosity η1 at a shear rate of 1 (1 / s) to the viscosity η 10 at a shear rate of 10 (1 / s) at 25 °C, defined using a rheometer (Ti = η1 / η 10 ).

[0032] In the present invention, the ratio of component (E-1) to component (C) is between 0.02 - 1.00% by weight, preferably between 0.05 - 0.50% by weight, more preferably between 0.08 - 0.20% by weight, even more preferably between 0.08 - 0.15% by weight.

[0033] A composition as described above, wherein

[0034] the weight ratio of component (E-2) to component (E-1) is between 0.5 - 10, preferably between 1 - 6; preferably between 2 - 4; more preferably between 2.5 - 3.5; for example, 2.3, 2.7, 2.9, 3.1, 3.3, 3.7.

[0035] In the present invention, the ratio of component (E-2) to component (C) is between 0.05 - 1.00% by weight, preferably between 0.08 - 0.80% by weight, more preferably between 0.08 - 0.60% by weight, even more preferably between 0.10 - 0.40% by weight.

[0036] In the present invention, the ratio of the sum of components (E-1) and (E-2) to component (C) is between 0.05 - 2.00% by weight, preferably between 0.08 - 1.20% by weight, more preferably between 0.10 - 1.00% by weight, even more preferably between 0.10 - 0.80% by weight, even more preferably between 0.20 - 0.60% by weight.

[0037] In the present invention, based on the total amount of the composition being 100% by weight, the amount of the thixotropic agent is less than or equal to 1% by weight, preferably less than or equal to 0.1% by weight.

[0038] The thixotropic agent is selected from montmorillonite, bentonite or metal oxide particles with a BET specific surface area greater than or equal to 100 m 2 / g, preferably greater than or equal to 150 m 2 / g, such as fumed silica and precipitated silica.

[0039] A composition as described above, wherein component (C) is treated with component (E-1) and component (E-2).

[0040] A composition as described above, wherein component (C) is subjected to a heat surface treatment with component (E-1) and component (E-2).

[0041] Use of a composition as described above in the field of potting.

[0042] In electronics, potting is a process of filling an entire electronic component with a liquid or gel-like composition to exclude gas phenomena such as corona discharge, resist shock and vibration, and exclude water, moisture or corrosive agents.

[0043] A heat-conducting member, which comprises the above-mentioned composition or its cured product.

[0044] A heat dissipation structure, which comprises a heat-conducting member.

[0045] A heat dissipation structure, which is obtained by providing a heat dissipation member on a heat dissipation component or a circuit board including a mounted heat dissipation component via the composition or its cured product.

[0046] The heat dissipation structure is an electrical device or an electronic device.

[0047] For the composition as described above, when the thermal conductivity is greater than 2.5 W / mk, at 25 °C according to DIN53019, when the shear rate is 1 (1 / s), the initial viscosity of the composition after mixing is less than or equal to 100 Pa·s, preferably equal to or less than 60 Pa·s, more preferably equal to or less than 40 Pa·s.

[0048] For the composition as described above, when the thermal conductivity is greater than 2.5 W / mk, at 25 °C according to DIN53019, when the shear rate is 10 (1 / s), the initial viscosity of the composition after mixing is less than or equal to 50 Pa·s, preferably equal to or less than 30 Pa·s, more preferably equal to or less than 20 Pa·s.

[0049] For the composition as described above, when the thermal conductivity is less than 2.5 W / mk, at 25 °C according to DIN53019, when the shear rate is 1 (1 / s), the initial viscosity of the composition after mixing is less than or equal to 60 Pa·s, preferably equal to or less than 40 Pa·s, more preferably equal to or less than 20 Pa·s.

[0050] For the composition as described above, when the thermal conductivity is less than 2.5 W / mk, at 25 °C according to DIN53019, when the shear rate is 10 (1 / s), the initial viscosity of the composition after mixing is less than or equal to 40 Pa·s, preferably equal to or less than 30 Pa·s, more preferably equal to or less than 20 Pa·s, and even more preferably equal to or less than 10 Pa·s.

[0051] In the present invention, the filling rate = the total amount of heat-conducting filler / the total weight of the composition. Generally, a filling rate greater than or equal to 0.84 is considered a high filling rate.

[0052] In the present invention, component (C) is a heat-conducting filler.

[0053] Component (C) contains

[0054] 10 - 30% by weight of (C-1) aluminum hydroxide with an average particle size greater than or equal to 0.1 μm and less than or equal to 4 μm,

[0055] For example, (C-1) has average particle sizes of 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 μm, and contents of 18 wt%, 20 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt%;

[0056] 10 - 30 wt% of (C-2) aluminum hydroxide with an average particle size greater than or equal to 15 μm and less than or equal to 40 μm,

[0057] For example, (C-2) has average particle sizes of 18, 20, 22, 24, 26, 28, 30 μm, and contents of 18 wt%, 20 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt%,

[0058] 40 - 80 wt% of (C-3) aluminum hydroxide with an average particle size greater than or equal to 80 μm and less than or equal to 100 μm,

[0059] For example, (C-3) has average particle sizes of 82, 84, 86, 88, 90, 92, 94, 96, 98 μm, and contents of 44 wt%, 46 wt%, 48 wt%, 50 wt%, 52 wt%, 54 wt%, 56 wt%, 58 wt%, 60 wt%, 62 wt%, 64 wt%,

[0060] In (C-1), (C-2) and (C-3), the component (C) in the composition is calculated as 100 wt%.

[0061] The composition as described above, wherein based on the total amount of heat-conducting fillers being 100 wt%, the total amount of all aluminum hydroxides is greater than 95 wt%, preferably greater than 99 wt%, more preferably greater than 99.9 wt%.

[0062] The composition as described above, wherein the total amount of all aluminum hydroxides is greater than 95 wt%, preferably greater than 99 wt%, more preferably greater than 99.9 wt%, and the total amount of fillers is calculated as 100 wt%.

[0063] In the composition as described above, (C-1), (C-2) and (C-3) aluminum hydroxides are all in amorphous form.

[0064] In the composition as described above, based on the composition being 100 wt%, the amount of spherical fillers is less than 10 wt%, preferably less than 1 wt%.

[0065] In the composition as described above, based on the composition being 100 wt%, the amount of spherical alumina is less than 10 wt%, preferably less than 1 wt%.

[0066] In the composition as described above, among the aluminum hydroxides (C-1), (C-2) and (C-3), the content of Al(OH)3 is greater than or equal to 99.1%, preferably greater than or equal to 99.5%.

[0067] The composition as described above, wherein the aluminum hydroxides (C-1), (C-2) and (C-3), wherein the content of Na2O is less than or equal to 0.1%, preferably the total content of water-soluble Na2O and lattice Na2O is less than or equal to 0.1%.

[0068] The composition as described above, wherein the component (C) contains

[0069] 10-30% by weight of aluminum hydroxide (C-1) with an average particle size greater than or equal to 0.5 μm and less than or equal to 3 μm,

[0070] 10-30% by weight of aluminum hydroxide (C-2) with an average particle size greater than or equal to 15 μm and less than or equal to 40 μm,

[0071] 40-80% by weight of aluminum hydroxide (C-3) with an average particle size greater than or equal to 85 μm and less than or equal to 95 μm,

[0072] In (C-1), (C-2) and (C-3), the component (C) in the composition is calculated as 100% by weight.

[0073] The composition as described above, wherein the component (C) contains

[0074] 20-50% by weight of alumina (C-5) with an average particle size greater than or equal to 1 μm and less than or equal to 10 μm,

[0075] 50-80% by weight of alumina (C-6) with an average particle size greater than or equal to 30 μm and less than or equal to 95 μm,

[0076] In (C-5) and (C-6), the component (C) in the composition is calculated as 100% by weight.

[0077] The definition of the average particle size refers to the value of the cumulative average particle size (D50 median diameter) measured by a particle size analyzer LS13 320 manufactured by BECKMAN COULTE based on volume.

[0078] The sample of (C-1) is prepared by the solution method. Place 0.1 g of the sample in 10 ml of absolute ethanol, disperse and stir it by ultrasound (100 w) for 2 minutes so that the sample is completely dispersed. Take out 2-3 drops of the sample solution and put it into the sample cell of the particle size analyzer.

[0079] Prepare samples (C-2), (C-3), (C-5), (C-6) (or other thermal conductive fillers with an average particle size greater than or equal to 7 μm) by the dry powder method, and place an appropriate amount of the room-temperature dried samples in the loading cylinder of the particle size analyzer. Insert the loading cylinder into the detection slot of the device.

[0080] In the present invention, the particle size distribution of the thermal conductive fillers is unimodal, or their particle sizes satisfy a unimodal or nearly unimodal particle size distribution.

[0081] The nearly unimodal particle size distribution in the present invention means that in the volume integral diagram of the measured sample, there may be two or more peaks, but the volume integral area of the main peak accounts for more than 80%, preferably more than 85%, more preferably more than 90%, and even more preferably more than 95% of the entire volume integral area.

[0082] The outer contour of the spherical filler is generally spherical, and it is a filler material obtained by treating amorphous fillers through chemical and / or physical (including heat treatment) processes.

[0083] Spherical alumina is a product obtained by heat-treating amorphous alumina, and its outer contour is generally spherical.

[0084] In addition, the present invention provides a thermally conductive silicone cured product, which comprises a cured product of a thermally conductive silicone composition.

[0085] This thermally conductive silicone cured product is excellent in fluidity, thermal conductivity, and light weight.

[0086] As described above, according to the thermally conductive silicone composition of the present invention, a silicone composition containing a specific organopolysiloxane, hydrogen polysiloxane, and thermal conductive filler is finely adjusted and formulated so that the thermal conductive filler is filled into the base material at a high density. This makes it possible to provide a thermally conductive silicone composition that produces a thermally conductive silicone cured product with high thermal conductivity and light weight. This thermally conductive silicone cured product is useful as a thermal conductive material in potting applications, especially for cooling electronic components through thermal conductivity.

[0087] As described above, the present invention creates a thermally conductive silicone cured product (thermally conductive gel molded product) with low viscosity, low thixotropy, high fluidity, high thermal conductivity, and light weight, as well as a thermally conductive silicone composition for forming the cured product.

[0088] Specifically, the present invention is a thermally conductive silicone composition, which comprises:

[0089] Component (A): Organopolysiloxane, preferably Component (A-1): Alkenyl-containing organopolysiloxane

[0090] Component (A) is an organopolysiloxane. Component (A) is used as the main component of the composition of the present invention. Generally, the main chain portion is usually composed of repeating basic diorganosiloxane units, but the molecular structure may partially contain a branched structure or may be a cyclic structure. However, from the perspective of physical properties of the cured product such as mechanical strength, the main chain is preferably a linear diorganopolysiloxane.

[0091] Component (A-1) is an alkenyl-containing organopolysiloxane, and the number of alkenyl groups bonded to silicon atoms in each molecule is at least two. Component (A-1) is used as the main component of the composition of the present invention. Generally, the main chain portion is usually composed of repeating basic diorganosiloxane units, but the molecular structure may partially contain a branched structure or may be a cyclic structure. However, from the perspective of physical properties of the cured product such as mechanical strength, the main chain is preferably a linear diorganopolysiloxane.

[0092] The functional groups bonded to silicon atoms include unsubstituted or substituted monovalent hydrocarbon groups. Examples thereof 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 biphenyl; aralkyl groups such as benzyl, phenylethyl, phenylpropyl, and methylbenzyl; and groups obtained by substituting part or all of the hydrogen atoms bonded to the carbon atoms therein with cyano groups, halogen atoms such as fluorine, chlorine, and bromine, etc. Examples of such substituted groups include chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc. Typical examples of the functional groups include functional groups having 1 to 10 carbon atoms, and particularly typical examples thereof include functional groups having 1 to 6 carbon atoms. Preferred examples of the 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; and unsubstituted or substituted phenyl groups such as phenyl, chlorophenyl, and fluorophenyl. In addition, all the functional groups bonded to silicon atoms do not have to be the same.

[0093] In addition, the alkenyl group usually has about 2 to 8 carbon atoms. Examples thereof include vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, etc. Among them, lower alkenyl groups such as vinyl and allyl are preferred, and vinyl is particularly preferred. Note that the number of alkenyl groups in each molecule must be two or more, and each alkenyl group is preferably bonded only to the silicon atom at the end of the molecular chain so that the resulting cured product has good flexibility.

[0094] The viscosity of component (A), the organopolysiloxane, at 25 °C is preferably in the range of 10 to 100,000 mPa·s, particularly preferably 50 to 50,000 mPa·s, more preferably 50 to 20,000 mPa·s, and even more preferably 50 to 2,000 mPa·s. Component (A), the organopolysiloxane, is preferably polydimethylsiloxane.

[0095] Component (A-1): The viscosity of the alkenyl-containing organopolysiloxane at 25 °C is preferably in the range of 10 to 100,000 mPa·s, particularly preferably 50 to 10,000 mPa·s, more preferably 50 to 1,000 mPa·s, and even more preferably 50 to 200 mPa·s. When the viscosity is 10 mPa·s or higher, the resulting composition has good storage stability. At the same time, when the viscosity is 100,000 mPa·s or lower, the resulting composition has good ductility. Component (A-1), the alkenyl-containing organopolysiloxane, is preferably vinyl-terminated polydimethylsiloxane.

[0096] One kind of the organopolysiloxane of component (A) can be used alone, or two or more kinds having different viscosities, etc. can be used in combination.

[0097] One kind of the alkenyl-containing organopolysiloxane of component (A-1) can be used alone, or two or more kinds having different viscosities, etc. can be used in combination.

[0098] Optionally present component (B): Organohydrogenpolysiloxane

[0099] Component (B) is an organohydrogenpolysiloxane having at least two, preferably 2 to 100, hydrogen atoms (Si—H groups) directly bonded to silicon atoms per molecule. This component acts as a crosslinking agent for component (A-1). Specifically, through the hydrosilylation reaction promoted by the platinum group metal-based curing catalyst described later as component (D), the Si—H groups in component (B) are added to the alkenyl groups in component (A-1), thereby forming a three-dimensional network structure with a crosslinked structure. Note that if the number of Si—H groups per molecule in component (B) is less than 2, curing does not occur.

[0100] The organohydrogenpolysiloxane to be used can be represented by the following average structural formula (4), but is not limited thereto.

[0101]

[0102] In this formula, each R' independently represents a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group without aliphatic unsaturated bonds, and at least two R's are hydrogen atoms; e represents an integer of 1 or greater.

[0103] Examples of the unsubstituted or substituted monovalent hydrocarbon group of R' other than hydrogen in formula (4) that does not contain an aliphatic unsaturated bond 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 biphenyl; 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 therein with cyano groups, halogen atoms such as fluorine, chlorine, and bromine, etc. Examples of such substituted groups include chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc. Typical examples of the monovalent hydrocarbon group include a monovalent hydrocarbon group having 1 to 10 carbon atoms, and particularly typical examples thereof include a monovalent hydrocarbon group having 1 to 6 carbon atoms. Preferred examples of the monovalent hydrocarbon group include an unsubstituted or substituted alkyl group having 1 to 3 carbon atoms such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, and cyanoethyl; and an unsubstituted or substituted phenyl group such as phenyl, chlorophenyl, and fluorophenyl. In addition, all of the R's do not have to be the same.

[0104] The addition amount of component (B) is such that, relative to 1 mole of the alkenyl group derived from component (A-1), the amount of the Si-H group derived from component (B) is 0.1 to 5.0 moles (i.e., the number of moles of hydrogen atoms directly bonded to the silicon atom is 0.1 to 5.0 times the number of moles of the alkenyl group derived from component (A-1)), preferably 0.3 to 2.0 moles, and more preferably 0.5 to 1.0 mole. If the amount of the Si-H group derived from component (B) is less than 0.1 mole relative to 1 mole of the alkenyl group derived from component (A-1), curing does not occur, or the strength of the cured product is insufficient, such that the molded product cannot maintain its shape and in some cases cannot be processed. At the same time, if the amount exceeds 5.0 moles, the cured product may become inflexible and brittle.

[0105] The organopolysiloxane of component (B) can be used alone, or two or more kinds having different viscosities, etc. can be used in combination.

[0106] The composition as described above, wherein component (B) may contain (B-1) and (B-2).

[0107] Component (B-1) organopolysiloxane containing hydrogen is an organopolysiloxane having at least 3, preferably 3 - 100 hydrogen atoms (Si-H groups) directly bonded to silicon atoms in one molecule, wherein the hydrogen content is between 0.5 - 4 mmol / g, preferably between 0.8 - 3 mmol / g, more preferably between 1.1 - 2.7 mmol / g, and even more preferably between 1.5 - 2.3 mmol / g.

[0108] Component (B-2) organopolysiloxane containing hydrogen is an organopolysiloxane having 2 hydrogen atoms (Si-H groups) directly bonded to silicon atoms in one molecule, wherein the hydrogen content is between 0.01 - 1.5 mmol / g, preferably between 0.1 - 1.2 mmol / g, more preferably between 0.3 - 1.0 mmol / g, and even more preferably between 0.4 - 0.8 mmol / g.

[0109] The composition as described above, wherein component (B) contains (B-1) and (B-2), and is 100% by weight based on component (A-1), and the amount of component (B-1) is between 0.5 - 3% by weight, preferably 1.5 - 2.5% by weight.

[0110] The composition as described above, wherein component (B) contains (B-1) and (B-2), and is 100% by weight based on component (A-1), and the amount of component (B-2) is between 10 - 50% by weight, preferably between 20 - 40% by weight.

[0111] Component (C): Thermal conductive filler

[0112] The thermal conductive filler generally does not contain fumed silica or precipitated silica.

[0113] In the composition of the present invention, based on 100% by weight of the total composition, the content of fumed silica and / or precipitated silica is less than 1% by weight, preferably less than 0.1% by weight; wherein the BET specific surface area of fumed silica or precipitated silica is between 150 - 600 m 2 / g.

[0114] The thermal conductive filler contains materials generally considered as thermal conductive fillers, including metals, metal oxides, metal nitrides and metal hydroxides, further including non-magnetic metals such as silver, copper or aluminum; metal oxides such as alumina, silica, magnesia, iron oxide red, beryllium oxide, titanium dioxide or zirconium oxide; metal nitrides such as aluminum nitride, silicon nitride or boron nitride; metal hydroxides such as aluminum hydroxide, magnesium hydroxide; artificial diamond, silicon carbide, etc. Additionally, a particle size of 0.1 to 200 μm can be adopted. One or two or more of them can be used as composite materials.

[0115] Relative to 100 parts by mass of component (A), component (C) must be blended in an amount of 800 to 4,000 parts by mass, preferably 900 to 2,000 parts by mass, more preferably 900 to 1,500 parts by mass. If the blending amount is less than 800 parts by mass, the thermal conductivity of the resulting composition is poor. If the blending amount exceeds 2,000 parts by mass, the kneading operability is impaired, and the cured product becomes significantly brittle. In order to obtain a higher thermal conductivity and a light-weight product, the filling rate of the composition is usually greater than or equal to 0.84.

[0116] Optionally present component (D): platinum group metal-based curing catalyst

[0117] Component (D) is a platinum group metal-based curing catalyst and is not particularly limited as long as the catalyst promotes the addition reaction of the alkenyl group derived from component (A-1) and the Si-H group derived from component (B). Examples of the catalyst include 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 chloroplatinate salts such as H2PtCl4.nH2O, H2PtCl6.nH2O, NaHPtCl6.nH2O, KHPtCl6.nH2O, Na2PtCl6.nH2O, K2PtCl4.nH2O, PtCl4.nH2O, PtCl2, and Na2HPtCl4.nH2O (herein, in the formula, n is an integer from 0 to 6, preferably 0 or 6); alcohol-modified chloroplatinic acid (see the specification of U.S. Patent No. 3,220,972); complexes of chloroplatinic acid and olefins (see the specifications of U.S. Patent Nos. 3,159,601, 3,159,662, and 3,775,452); those obtained by loading platinum group metals such as platinum black and palladium on carriers such as alumina, silica, or carbon; rhodium-olefin complexes, tris(triphenylphosphine)rhodium chloride (Wilkinson catalyst); complexes of platinum chloride, chloroplatinic acid, or chloroplatinate salts with vinyl-containing siloxanes, especially cyclic siloxanes no longer containing vinyl; and so on.

[0118] The amount of component (D) used is such that the content of the platinum group metal element is 0.1 to 1,000 ppm by mass relative to component (A-1). If the content is less than 0.1 ppm, sufficient catalyst activity cannot be obtained. If the content exceeds 1,000 ppm, only the cost increases but the effect of promoting the addition reaction is not enhanced, and the catalyst remaining in the cured product may also reduce the insulation performance.

[0119] Component (E-1): an alkoxysilane compound represented by the following formula (1),

[0120] ·R 1 a R2 b Si(OR 3 ) 4-a-b (1)

[0121] · In formula (1),

[0122] · Each R 1 independently represents an alkyl group having 1 to 3 carbon atoms, preferably methyl, ethyl,

[0123] · Each R 2 independently represents an unsubstituted or substituted hydrocarbon group having 1 to 3 carbon atoms, preferably an unsubstituted or substituted alkyl group having 1 to 3 carbon atoms, preferably methyl, ethyl,

[0124] · Each R 3 independently represents an alkyl group having 1 to 3 carbon atoms, preferably methyl, ethyl,

[0125] · a represents an integer from 1 to 3, and b represents an integer from 0 to 2, provided that a + b is an integer from 1 - 3; preferably, a is 1 and b is 0.

[0126] Component (E-1) is preferably an alkoxysilane containing an alkyl group having 1 to 3 carbon atoms; more preferably a trialkoxysilane containing an alkyl group having 1 to 3 carbon atoms; more preferably methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, propyltrimethoxysilane, propyltriethoxysilane; more preferably methyltrimethoxysilane, methyltriethoxysilane.

[0127] As a surface treatment agent, component (E-1) can be blended alone or in combination.

[0128] There is no particular limitation on the surface treatment method using component (E-1) and component (E-2). The thermally conductive inorganic filler in component (D) can, for example, undergo a direct treatment method, an overall blending method, or a drying and concentration method. The direct treatment method includes a dry method, a slurry method, and a spray method. The overall blending method includes a direct method and a masterbatch method. The drying method includes a slurry method and a direct method. Preferably, component (D) and component (E-1), component (E-2) are mixed together all at once or in stages in advance using a conventional mixing device.

[0129] In the present invention, the surface treatment method using component (E-1) and component (E-2) is preferably a direct treatment method, and more preferably a heating surface treatment method of mixing and heating (basic heating) component (D) with component (E-1) and component (E-2). Specifically, after uniformly mixing component (D) or some of component (D) with component (E-1), component (E-2), and optionally some of the main components (A) or (B), the remaining component (D) can be stirred into the mixture at a heating temperature of 100 to 200 °C and preferably under reduced pressure. The temperature conditions and stirring time can be set based on the amount of the sample used, but are preferably 90 to 180 °C and 0.25 to 10 hours.

[0130] The mixing device is not particularly limited and can be a single-axis or twin-axis continuous mixer, a two-roll mixer, a Ross mixer, a Hobart mixer, a dental mixer, a planetary mixer, a kneading mixer, or a Henschel mixer.

[0131] Component (F): property imparting agent

[0132] As component (F), an organopolysiloxane having a viscosity of 10 to 100,000 mPa·s at 25 °C and represented by the following formula (3) can be added.

[0133]

[0134] where each R 5 independently represents a monovalent hydrocarbon group having 1 to 10 carbon atoms and not having an aliphatic unsaturated bond; and d represents an integer of 5 to 2,000.

[0135] Component (F) is appropriately used to impart properties such as a viscosity regulator and a plasticizer to the thermally conductive silicone composition, but is not limited thereto. One of these can be used alone, or two or more of them can be used in combination.

[0136] Each R 5 independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms. R 5Examples 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 biphenyl; 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 therein with cyano groups, halogen atoms such as fluorine, chlorine, and bromine, etc. Examples of such substituted groups include chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc. Typical examples of the monovalent hydrocarbon group include a monovalent hydrocarbon group having 1 to 10 carbon atoms, and particularly typical examples thereof include a monovalent hydrocarbon group having 1 to 6 carbon atoms. Preferred examples of the monovalent hydrocarbon group include an unsubstituted or substituted alkyl group having 1 to 3 carbon atoms, such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, and cyanoethyl; and an unsubstituted or substituted phenyl group, such as phenyl, chlorophenyl, and fluorophenyl. Methyl and phenyl are particularly preferred.

[0137] From the perspective of the required viscosity, d is preferably an integer of 5 to 2,000, particularly preferably an integer of 10 to 1,000.

[0138] In addition, the viscosity at 25 °C is preferably 10 to 100,000 mPa·s, particularly preferably 100 to 10,000 mPa·s. When the viscosity is 10 mPa·s or higher, the cured product of the resulting composition hardly shows oil bleeding. When the viscosity is 100,000 mPa·s or lower, the resulting thermally conductive silicone composition has appropriate flexibility.

[0139] When component (F) is added to the thermally conductive silicone composition of the present invention, the addition amount is not particularly limited and may be 10 to 100 parts by mass relative to 100 parts by mass of component (A). When the addition amount is within this range, it makes it easy to maintain good fluidity and workability of the thermally conductive silicone composition before curing, and it is easy to fill the thermally conductive filler of component (C) into the composition.

[0140] In the thermally conductive silicone composition of the present invention, the amount of component (F) used is preferably less than 0.1 part by mass, more preferably less than 0.01 part by mass, relative to 100 parts by mass of component (A). In this way, oil leakage and contamination of the base material of the thermally conductive silicone composition can be avoided.

[0141] Optionally present component (G): reaction inhibitor

[0142] As component (G), an addition reaction inhibitor is available. As the addition reaction inhibitor, any known addition reaction inhibitor used in a silicone composition that can be cured by an addition reaction can be employed. Examples thereof include acetylene compounds such as 1-ethynyl-1-hexanol and 3-butyn-1-ol, various nitrogen compounds, organic phosphorus compounds, oxime compounds, organic chlorine compounds, etc. When component (G) is blended, the usage amount is preferably 0.01 to 1 part by mass, more preferably 0.1 to 0.8 part by mass, relative to 100 parts by mass of component (A-1). At this blending amount, the curing reaction proceeds sufficiently and the molding efficiency is not impaired.

[0143] Other components

[0144] As needed, the thermally conductive silicone composition of the present invention can be further blended with other components. Examples of optional components that can be blended include heat resistance improvers such as iron oxide and cerium oxide; colorants; mold release agents; and the like.

[0145] Embodiments

[0146] Thermally conductive silicone cured product and method for producing the same

[0147] The thermally conductive silicone cured product (thermally conductive resin molded product) according to the present invention is a cured product of the above thermally conductive silicone composition. The curing conditions for curing (molding) the thermally conductive silicone composition can be the same as those for known silicone rubber compositions that can be cured by an addition reaction. For example, the thermally conductive silicone composition is also sufficiently cured at normal temperature, but can be heated as needed. Preferably, the thermally conductive silicone composition is subjected to addition curing at 100 to 120 °C for 8 to 12 minutes. Such a cured product (molded product) of the present invention is excellent in thermal conductivity.

[0148] Thermal conductivity of the molded product

[0149] The molded product of the present invention has a thermal conductivity of preferably 2.0 W / m·K or more, which is a measured value measured by the hot disk method at 25 °C. A product with a thermal conductivity of 2.0 W / m·K or more is suitable for heat generating members that generate a large amount of heat. Note that such a thermal conductivity can be adjusted by coordinating the combination of the type or particle size of the thermally conductive filler.

[0150] Hardness of the molded product

[0151] The molded product of the present invention is tested by a Zwick hardness tester. Note that such hardness can be adjusted by changing the ratio of component (A-1) and component (B) to adjust the crosslinking density.

[0152] According to DIN53019, an Anton Paar MCR302 instrument is used to test the kinematic viscosity and static viscosity of the composition of the present invention.

[0153] Components (A) to (G) used in the following examples and comparative examples are shown below.

[0154] Component (A):

[0155] (A-1) component, an organopolysiloxane represented by the following formula (5), where X represents vinyl and n represents the number that gives a viscosity of 120 mPa·s.

[0156]

[0157] Component (B):

[0158] (B-1) Side-chain hydrogen polysiloxane represented by the following formula (6), with a hydrogen content of 1.7 mmol / g.

[0159]

[0160] (B-2) End-capped hydrogen polysiloxane represented by the following formula (7), where X represents hydrogen. The hydrogen content is 0.53 mmol / g.

[0161]

[0162] Component (C):

[0163] (C-1) Aluminum hydroxide with an average particle size of 1.5 μm

[0164] (C-2) Aluminum hydroxide with an average particle size of 25 μm

[0165] (C-3) Aluminum hydroxide with an average particle size of 90 μm

[0166] (C-5) Aluminum oxide with an average particle size of 5 μm

[0167] (C-6) Aluminum oxide with an average particle size of 40 μm

[0168] Component (E-2):

[0169] Monoterminal hydroxy silicone oil 1,

[0170] R 1 3SiO-(R 1 2SiO) m -Si-R 1 (3-n) R 2 n (2)

[0171] In formula (2), R 1 is methyl, R 2 is hydroxy, m is between 9 and 15, n = 1,

[0172] The viscosity is between 15 - 30 mPa·s, Mn is between 700 - 1200 g / mol according to NMR measurement, and the hydroxyl value is between 1.5 - 2.5 wt%.

[0173] Component (G):

[0174] Ethynylmethylenemethanol as an addition reaction inhibitor.

[0175] The above materials are provided by Wacker Chemie AG.

[0176] Add the components in the predetermined amounts shown later in the examples and comparative examples in Table 1 or 2, and knead for 30 - 60 minutes at 90 °C using a planetary mixer.

[0177] Molding method

[0178] After mixing, the compositions in Table 1 were obtained.

[0179] Pour each of the compositions obtained in Table 2 into a mold with dimensions of 60 mm × 60 mm × 6 mm, and mold at 100 °C for 60 minutes using a molding press.

[0180] Thermal conductivity evaluation method:

[0181] Pour each of the compositions obtained in Table 1 and Table 2 into a mold with dimensions of 60 mm × 60 mm × 6 mm, and use for measuring the thermal conductivity.

[0182] Under the conditions of 100 °C and 60 minutes, cure the compositions obtained in the following examples and comparative examples in Table 2 into sheet form with a thickness of 6 mm. Use two sheets from each composition and measure the thermal conductivity with a thermal conductivity meter (product name: TC3000E, manufactured by Xi'an Xiatech Electronics Co., Ltd.).

[0183] Hardness:

[0184] Cure the compositions obtained in the following examples and comparative examples into sheet form with a thickness of 6 mm as described above. Stack two sheets from each composition on top of each other, and measure the Shore 00 value using a Zwick hardness tester.

[0185] Density:

[0186] Measure using Mettler Toledo ML204.

[0187] Table 1: Thermal conductive compositions

[0188]

[0189] In Table 1, when using the combination of component (E-1) and component (E-2), the composition can obtain a lower viscosity under both low-speed shear and high-speed shear conditions. In particular, the thixotropic values TI = D1 / D10 of Examples 3, 4, and 6 are lower, below 1.7.

[0190] Table 2: Thermal Conductive Potting Composition

[0191]

[0192] In Table 2, component A and component B are stirred and mixed at a ratio of 1:1. When the shear rate is 1 (1 / s), the initial viscosity of the product obtained in Example 12 after mixing is about 6200 mPa·s; when the shear rate is 10 (1 / s), the initial viscosity after mixing is about 4300 mPa·s.

[0193] The thixotropic index TI of component A and component B in Example 12 is low (both below 1.7), and the fluidity is excellent, and it can be used for potting electronic products containing delicate parts. On the other hand, the thixotropic index TI of component A and component B in Comparative Example 13 is relatively high, which easily leads to the disadvantage of insufficient flow during the potting process. The product obtained from Example 12 has a slightly higher thermal conductivity and better performance.

Claims

1. A composition, comprising: Component (A), which is an organopolysiloxane, preferably component (A-1), which is an organopolysiloxane having two or more alkenyl groups per molecule; Optionally present component (B), which is an organohydrogenpolysiloxane having two or more hydrogen atoms directly bonded to silicon atoms, and the content thereof is such that the number of moles of hydrogen atoms directly bonded to silicon atoms in the component (B) is 0.1 to 5.0 times the number of moles of alkenyl groups derived from the component (A-1); Component (C), which is a heat conductive filler, wherein the filling rate of the heat conductive filler is greater than or equal to 0.80, preferably greater than or equal to 0.84, preferably greater than or equal to 0.88, preferably greater than or equal to 0.89, preferably greater than or equal to 0.90; Optionally present component (D), which is a platinum group metal-based curing catalyst, and the content of platinum group metal elements is 0.1 to 1,000 ppm by mass relative to the component (A-1), Component (E-1), which is an alkoxysilane compound represented by the following formula (1); and R 1 a R 2 b Si(OR 3 ) 4-a-b (1) In the formula (1), each R 1 independently represents an alkyl group having 1 to 3 carbon atoms, preferably methyl, ethyl, each R 2 independently represents an unsubstituted or substituted hydrocarbon group having 1 to 3 carbon atoms, preferably methyl, ethyl, each R 3 independently represents an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, more preferably methyl, ethyl, a represents an integer from 1 to 3, and b represents an integer from 0 to 2, provided that a + b is an integer from 1 to 3, Component (E-2), which is a polysiloxane represented by the following general formula (2), R 1 3SiO-(R 1 2SiO) m -Si-R 1 (3-n) R 2 n (2) In the formula (2), each R 1independently represents a hydrocarbon group having 1 to 6 carbon atoms, preferably an alkyl or alkenyl group having 1 to 3 carbon atoms, preferably methyl, ethyl, propyl, vinyl, more preferably methyl; Each R 2 independently represents -OH or -(CH2) p OH, where p is an integer from 1 to 3, preferably a hydroxyl group; m ≤ 50, more preferably m ≤ 20, more preferably 6 ≤ m ≤ 18; n is an integer, preferably n is 1 - 3, more preferably n is 1.

2. The composition according to claim 1, wherein the thixotropic index (Ti) at 25 °C is preferably 1.70 or less, preferably 1.05 - 1.70, more preferably 1.20 - 1.70, more 3. The composition according to claims 1 - 2, wherein the viscosity of component (E - 2) at 25 °C according to DIN53019 is 500 mPa·s or lower, preferably 300 mPa·s or lower, more preferably 100 mPa·s or lower, more preferably 50 mPa·s or lower, more preferably between 10 - 40 mPa·s.

4. The composition according to any one of claims 1 - 3, wherein component (E - 1) is preferably an alkoxysilane containing an alkyl group having 1 to 3 carbon atoms; more preferably a trialkoxysilane containing an alkyl group having 1 to 3 carbon atoms; more preferably methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, propyltrimethoxysilane, propyltriethoxysilane; more preferably methyltrimethoxysilane, methyltriethoxysilane.

5. The composition according to any one of claims 1 - 4, wherein the ratio of component (E - 1) to component (C) is between 0.02 - 1.00 wt%, preferably between 0.05 - 0.50 wt%, more preferably between 0.08 - 0.20 wt%, more preferably between 0.08 - 0.15 wt%.

6. The composition according to any one of claims 1 - 5, wherein the weight ratio of component (E - 2) to component (E - 1) is between 0.5 - 10, preferably between 0.8 - 6; preferably between 2 - 4; more preferably between 2.5 - 3.

5.

7. The composition according to any one of claims 1 - 6, wherein the ratio of component (E - 2) to component (C) is between 0.05 - 1.00 wt%, preferably between 0.08 - 0.80 wt%, more preferably between 0.08 - 0.60 wt%, more preferably between 0.10 - 0.40 wt%.

8. The composition according to any one of claims 1 - 7, wherein the ratio of the sum of components (E-1) and (E-2) to component (C) is between 0.05 - 2.00 wt%, preferably between 0.08 - 1.20 wt%, more preferably between 0.10 - 1.00 wt%, still more preferably between 0.10 - 0.80 wt%, yet more preferably between 0.20 - 0.60 wt%.

9. Use of the composition according to any one of claims 1 - 8 in the field of potting.

10. A heat conducting member comprising the composition according to any one of claims 1 - 8 or a cured product thereof.

11. A heat dissipation structure comprising the heat conducting member according to claim 10.

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