Thermal grease

Abstract

A heat dissipation grease comprising a matrix component and a filler component, wherein the matrix component contains a silicone A and a surfactant B, the filler component contains alumina D1, and magnesium oxide D2 and / or aluminum nitride D3, the contained amount of the surfactant B may be 15 mass% or more with respect to the total amount of the matrix component, and the total contained amount of the magnesium oxide D2 and the aluminum nitride D3 is 10-60 mass% with respect to the total amount of the filler component.

Description

[Technical Field]

[0001] This invention relates to heat dissipation grease. [Background technology]

[0002] With the miniaturization and increased power output of heat-generating electronic components such as the CPU (Central Processing Unit) in personal computers, the amount of heat generated per unit area from these components has become extremely large. This amount of heat can reach approximately 20 times that of an iron. To prevent these heat-generating electronic components from failing over the long term, cooling of these components is necessary.

[0003] For cooling, metal heatsinks and enclosures are used, and thermally conductive materials are also used to efficiently transfer heat from heat-generating electronic components to the cooling parts such as heatsinks and enclosures. If heat-generating electronic components and heatsinks are brought into contact without thermally conductive materials, air will be present at the interface at a microscopic level, hindering heat conduction. Therefore, by placing thermally conductive materials between the heat-generating electronic components and heatsinks, heat can be efficiently transferred by replacing the air present at the interface.

[0004] Examples of thermally conductive materials include thermally conductive pads and sheets formed by filling a thermosetting resin with a thermally conductive filler and molding it into a sheet, heat dissipation greases that can be applied or made into thin films by filling a fluid resin with a thermally conductive filler, and phase-change thermally conductive materials that soften or flow at the operating temperature of heat-generating electronic components.

[0005] Sheet-type heat dissipation materials are easy to handle and have excellent long-term shape retention, but they have high contact thermal resistance and are inferior to grease-type materials in terms of automated mounting. Therefore, in recent years, there has been an increase in the use of thermal grease at thicknesses that were previously mainly used for sheets.

[0006] Such heat-dissipating greases generally contain an inorganic filler in the resin that has been surface-treated with a silane coupling agent or the like. As surface treatment agents other than silane coupling agents, for example, copolymers containing polybutadiene units, units having hydrolyzable silyl groups, and units having a polysiloxane skeleton are known (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2018-062552 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, conventional thermal greases are prone to changes in hardness due to prolonged use, leading to problems such as reduced heat dissipation. Therefore, there is a need for a thermal grease that achieves low viscosity and high thermal conductivity while being less susceptible to changes in hardness.

[0009] This invention has been made in view of the above-mentioned problems, and aims to provide a heat dissipation grease that achieves low viscosity and high thermal conductivity while being less prone to changes in hardness. [Means for solving the problem]

[0010] In other words, the present invention is as follows. [1] It contains matrix components and filler components, The matrix component comprises silicone A and surfactant B. The filler component comprises alumina D1, magnesium oxide D2 and / or aluminum nitride D3. The amount of surfactant B may be 15% by mass or more relative to the total amount of matrix components. The total content of the magnesium oxide D2 and the aluminum nitride D3 is 10 to 60% by mass based on the total amount of the filler component. Heat dissipation grease. 〔2〕 The content of the filler component is 60 to 95% by volume based on the total amount of the heat dissipation grease. The heat dissipation grease according to 〔1〕. 〔3〕 The average particle size of the magnesium oxide D2 is 25 to 300 μm. The average particle size of the aluminum nitride D3 is 25 to 300 μm. The heat dissipation grease according to 〔1〕 or 〔2〕. 〔4〕 The alumina D1 further contains alumina D11 having an average particle size of 55 μm or more. The heat dissipation grease according to any one of 〔1〕 to 〔3〕. 〔5〕 The silicone A is a low molecular weight silicone A1 having a weight average molecular weight of 500 or more and 100,000 or less, and a high molecular weight silicone A2 having a weight average molecular weight of 150,000 or more and 1,000,000 or less. The heat dissipation grease according to any one of 〔1〕 to 〔4〕. 〔6〕 The content of the low molecular weight silicone A1 is 50 to 80% by mass based on the total amount of the matrix component. The heat dissipation grease according to any one of 〔1〕 to 〔5〕. 〔7〕 The content of the high molecular weight silicone A2 is 3.0 to 25% by mass based on the total amount of the matrix component. The heat dissipation grease according to any one of 〔1〕 to 〔6〕. 〔8〕 The content of the surfactant B is 15 to 55% by mass based on the total amount of the matrix component. The heat dissipation grease according to any one of 〔1〕 to 〔7〕. 〔9〕 The surfactant B is Surfactant B1 having a silicone (meth)acrylic monomer unit γ1 with a weight-average molecular weight of 1000 or more and less than 8000, and / or The surfactant B2 contains a silicone (meth)acrylic monomer unit γ2 having a weight-average molecular weight of 8000 to 50000. A heat dissipation grease as described in any one of items [1] to [8].

[10] The matrix component further comprises the silane coupling agent C. A heat dissipation grease as described in any one of items [1] to [9].

[11] The content of the silane coupling agent C is 2.0 to 16% by mass relative to the total amount of the matrix components. The heat dissipation grease described in

[10] .

[12] The filler component further contains silica D4, The silica D4 content is 0.1 to 10% by mass relative to the total amount of the filler components. A heat dissipation grease as described in any one of items [1] to

[11] . [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a heat dissipation grease that achieves low viscosity and high thermal conductivity while being less prone to changes in hardness. [Modes for carrying out the invention]

[0012] The following describes in detail an embodiment of the present invention (hereinafter referred to as "this embodiment"), but the present invention is not limited thereto, and various modifications are possible without departing from its essence.

[0013] 1. Thermal grease The heat dissipation grease of this embodiment contains a matrix component and a filler component, the matrix component comprises silicone A and surfactant B, and the filler component comprises alumina D1, magnesium oxide D2 and / or aluminum nitride D3, the content of surfactant B may be 15% by mass or more relative to the total amount of the matrix component, and the total content of magnesium oxide D2 and aluminum nitride D3 is 10 to 60% by mass relative to the total amount of the filler component.

[0014] Conventional heat dissipation greases are prone to hardness changes due to prolonged use, leading to problems such as reduced heat dissipation performance. In contrast, this embodiment uses predetermined amounts of surfactant B, alumina D1, magnesium oxide D2, and / or aluminum nitride D3 in combination. This makes it possible to achieve a heat dissipation grease that is less susceptible to hardness changes while maintaining low viscosity and high thermal conductivity. The composition of the heat dissipation grease will be described in detail below.

[0015] 1.1 Matrix Components The matrix component comprises silicone A and surfactant B, and may further contain a silane coupling agent C or the like, as needed.

[0016] 1.1.1. Silicone A The shape of silicone A is not particularly limited, but examples include non-crosslinked silicones such as linear silicones, branched silicones, and cyclic silicones; and crosslinked silicones with three-dimensional crosslinking within the molecule. Among these, non-crosslinked silicones are preferred, and linear silicones are more preferred. By using such silicone A, viscosity tends to decrease and hardness changes tend to be further suppressed.

[0017] Generally, silicones are monofunctional units (R 1 SiO 1 / 2 ), two functional units (R 2 SiO 2 / 2 ), three functional units (R 3 SiO 3 / 2 ), and tetrafunctional units (SiO 4 / 2) can be represented. For example, linear silicone can be expressed as having monofunctional units (R 1 SiO 1 / 2 ) that constitute the terminals and difunctional units (R 2 SiO 2 / 2 ) that constitute the main chain (in the following formula, n3, n4 = 0), and cyclic silicone can be expressed as having difunctional units (RSiO 2 / 2 ) that constitute the ring (in the following formula, n1, n3, n4 = 0). Also, branched silicone and three-dimensionally crosslinked silicone have trifunctional units (R 3 SiO 3 / 2 ) and / or tetrafunctional units (SiO 4 / 2 ) that constitute the branch points, and further have monofunctional units (R 1 SiO 1 / 2 ) that constitute the terminals of the branched chains and difunctional units (R 2 SiO 2 / 2 ) that constitute the branched chains, and can be expressed as such.

[0018] The compositional formula using such units can be expressed as follows. In the following formula, n1 to n4 indicate the compositional ratios of the respective units, and can be shown in a ratio such that the sum of n1 to n4 is 1. Whether these units are included or not can be measured by a known method such as Si-NMR. Note that R 1 ~R 4 can each independently represent an arbitrary group. (R 1 SiO 1 / 2 ) n1 (R 2 SiO 2 / 2 ) n2 (R 3 SiO 3 / 2 ) n3 (SiO 4 / 2 )])]))]] n4

[0019] Silicone A is not particularly limited, but examples include non-curing silicones and curing silicones. Non-curing silicone resins are not particularly limited as long as they do not have the functional groups that contribute to curing that curing silicone resins have, or are not used in combination with a catalyst. Curing silicones are not particularly limited, but examples include those using a combination of two silicones having functional groups that react with each other. Such curing silicones are not particularly limited, but examples include addition-curing silicones, condensation-curing silicones, and peroxide-curing silicones.

[0020] Among these, silicone A is preferably a non-curing type silicone. By using such silicone A, a one-component heat dissipation grease can be obtained, and handling tends to be improved.

[0021] Furthermore, silicone A is not particularly limited, but examples include dimethyl silicone, diphenyl silicone, and methylphenyl silicone. These silicones may also have organic groups introduced into their side chains and / or terminals. Such silicones are not particularly limited, but examples include non-reactive silicones such as long-chain alkyl-modified silicones, polyether-modified silicones, aralkyl-modified silicones, fatty acid ester-modified silicones, and fatty acid amide-modified silicones; and reactive silicones such as amine-modified silicones, epoxy-modified silicones, mercapto-modified silicones, carboxyl-modified silicones, carbinol-modified silicones, and hydrogen-modified silicones.

[0022] Among these, dimethyl silicone, diphenyl silicone, methylphenyl silicone, and non-reactive silicone are preferred, with dimethyl silicone being more preferred. By using such silicone A, viscosity tends to decrease and hardness changes tend to be further suppressed.

[0023] The content of silicone A may preferably be 60% by mass or more, 65% by mass or more, 70% by mass or more, or 75% by mass or more, relative to the total amount of matrix components. Alternatively, the content of silicone A may preferably be 90% by mass or less, 85% by mass or less, or 80% by mass or less, relative to the total amount of matrix components. When the content of silicone A relative to the total amount of matrix components is within the above range, viscosity tends to decrease and hardness changes tend to be further suppressed.

[0024] Silicone A may contain at least one of low molecular weight silicone A1 having a weight-average molecular weight of 500 to 100,000, and high molecular weight silicone A2 having a weight-average molecular weight of 150,000 to 1,000,000, or both. Among these, it is preferable to contain both low molecular weight silicone A1 and high molecular weight silicone A2. Using low molecular weight silicone A1 and high molecular weight silicone A2 tends to reduce viscosity and further suppress hardness changes.

[0025] 1.1.1.1. Low molecular weight silicone A1 The weight-average molecular weight of low molecular weight silicone A1 may be 500 or more, preferably 1000 or more, 1500 or more, 2000 or more, or 2500 or more. Alternatively, the weight-average molecular weight of low molecular weight silicone A1 may be 100,000 or less, preferably 50,000 or less, 25,000 or less, 15,000 or less, 10,000 or less, or 7,500 or less. By using such low molecular weight silicone A1, viscosity tends to decrease and hardness changes tend to be further suppressed.

[0026] The viscosity of low molecular weight silicone A1 at 25°C is preferably 1.0 mPa·s or more, 5.0 mPa·s or more, 10 mPa·s or more, 20 mPa·s or more, or 30 mPa·s or more. Alternatively, the viscosity of low molecular weight silicone A1 at 25°C is preferably 5000 mPa·s or less, 4000 mPa·s or less, 3000 mPa·s or less, 2000 mPa·s or less, or 1000 mPa·s or less. When the viscosity of low molecular weight silicone A1 is within the above range, the viscosity tends to decrease and the change in hardness tends to be further suppressed.

[0027] The content of low molecular weight silicone A1 is preferably 50% by mass or more, 55% by mass or more, 60% by mass or more, or 65% by mass or more, relative to the total amount of matrix components. When the content of low molecular weight silicone A1 relative to the total amount of matrix components is 50% by mass or more, the viscosity tends to decrease.

[0028] The content of low molecular weight silicone A1 may preferably be 80% by mass or less, 75% by mass or less, 70% by mass or less, or 65% by mass or less, relative to the total amount of matrix components. When the content of low molecular weight silicone A1 relative to the total amount of matrix components is 80% by mass or less, the hardness change tends to be further suppressed.

[0029] 1.1.1.2. High-molecular-weight silicone A2 The weight-average molecular weight of polymeric silicone A2 may be 150,000 or more, preferably 200,000 or more, 250,000 or more, 300,000 or more, or 350,000 or more. Alternatively, the weight-average molecular weight of polymeric silicone A2 may be 1,000,000 or less, preferably 900,000 or less, 800,000 or less, 700,000 or less, or 600,000 or less. By using such polymeric silicone A2, viscosity tends to decrease and hardness changes tend to be further suppressed.

[0030] The viscosity of polymeric silicone A2 at 25°C is preferably 1000 Pa·s or more, 2500 Pa·s or more, 5000 Pa·s or more, 7500 Pa·s or more, or 10000 Pa·s or more. Alternatively, the viscosity of polymeric silicone A2 at 25°C is preferably 50000 mPa·s or less, 40000 mPa·s or less, 30000 mPa·s or less, 20000 mPa·s or less, or 15000 mPa·s or less. When the viscosity of polymeric silicone A2 is within the above range, the viscosity tends to decrease and the hardness change is further suppressed.

[0031] The content of polymeric silicone A2 may preferably be 3.0% by mass or more, 5.0% by mass or more, 7.0% by mass or more, 9.0% by mass or more, or 12% by mass or more, relative to the total amount of matrix components. When the content of polymeric silicone A2 relative to the total amount of matrix components is 3.0% by mass or more, the hardness change tends to be further suppressed.

[0032] The content of polymeric silicone A2 may preferably be 25% by mass or less, 20% by mass or less, 15% by mass or less, or 12.5% ​​by mass or less, relative to the total amount of matrix components. When the content of polymeric silicone A2 relative to the total amount of matrix components is 25% by mass or less, the viscosity tends to decrease.

[0033] The ratio of the content of low molecular weight silicone A1 to the content of high molecular weight silicone A2 (A1 / A2) is preferably 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, or 4.0 or more. Furthermore, the ratio of the content of low molecular weight silicone A1 to the content of high molecular weight silicone A2 (A1 / A2) is preferably 10 or less, 9.0 or less, 8.0 or less, 7.0 or less, or 6.0 or less. When the ratio (A1 / A2) is within the above range, viscosity tends to decrease and hardness changes tend to be further suppressed.

[0034] 1.1.2. Surfactants B The surfactant B is not particularly limited. Among these, a polymer having a silicone (meth)acrylic monomer unit γ is preferred as the surfactant B, and a copolymer having an anionic group (meth)acrylic monomer unit α, a cationic group (meth)acrylic monomer unit β, and a silicone (meth)acrylic monomer unit γ is more preferred. By using such a surfactant B, the dispersibility of the filler component can be maintained. Therefore, even if the filler component is highly packed from the viewpoint of thermal conductivity, the viscosity tends to decrease further and the hardness change tends to be suppressed further.

[0035] The content of surfactant B may be 15% by weight or more, preferably 17.5% by weight or more, 20% by weight or more, 22.5% by weight or more, 25% by weight or more, 27.5% by weight or more, or 30% by weight or more, relative to the total amount of matrix components. Furthermore, the content of surfactant B may be preferably 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, or 30% by weight or less, relative to the total amount of matrix components. When the content of surfactant B relative to the total amount of matrix components is within the above range, viscosity tends to decrease further and hardness changes tend to be suppressed further.

[0036] Furthermore, the content of surfactant B may be preferably 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 35 parts by weight or more, 40 parts by weight or more, 45 parts by weight or more, or 50 parts by weight or more, relative to 100 parts by weight of silicone A. Furthermore, the content of surfactant B may be preferably 75 parts by weight or less, 70 parts by weight or less, 65 parts by weight or less, or 60 parts by weight or less, relative to 100 parts by weight of silicone A. When the content of surfactant B relative to silicone A is within the above range, the viscosity tends to decrease further and the hardness change tends to be suppressed further.

[0037] The surfactant B will be described in more detail below. In this embodiment, "monomer" refers to a monomer having polymerizable unsaturated bonds before polymerization, and "monomer unit" refers to a repeating unit that constitutes part of surfactant B after polymerization and is derived from a predetermined monomer. Furthermore, (meth)acrylic includes acrylic and methacrylic, and (meth)acrylic monomers include (meth)acrylate and (meth)acrylamide. In addition, "(meth)acrylic monomer unit α," etc., will also be simply referred to as "unit α," etc.

[0038] 1.1.2.1. (Meth)acrylic monomer unit α The (meth)acrylic monomer unit α is a repeating unit having an anionic group. The anionic group is not particularly limited, but examples include a carboxyl group, a phosphate group, a phenolic hydroxyl group, and a sulfonic acid group. Among these, it is preferable that one or more are selected from the group consisting of a carboxyl group, a phosphate group, and a phenolic hydroxyl group. Having such a group tends to improve the dispersibility of the filler component.

[0039] Furthermore, it is preferable that unit α further has an electron-withdrawing group bonded to the anionic group. Such an electron-withdrawing group is not particularly limited as long as it has the effect of stabilizing the anion of the anionic group. For example, an acrylic monomer containing an electron-withdrawing substituent such as a halogen element at the α-carbon atom of the carboxyl group may be used. Having such a group tends to further improve the dispersibility of the filler component.

[0040] The unit α preferably has no electron-donating group bonded to the anionic group, or has a group with low electron-donating ability. Such an electron-donating group is not particularly limited as long as it has the effect of destabilizing the anion of the anionic group. For example, an acrylic monomer that does not have a substituent of an electron-donating group such as a methyl group on the carbon atom at the α position of the carboxyl group may be used. By adopting such a structure, the dispersibility of the filler component tends to be further improved.

[0041] Such (meth)acrylic monomers are not particularly limited, but examples include acrylic acid, methacrylic acid, acid phosphooxypropyl methacrylate, acid phosphooxypolyoxyethylene glycol monomethacrylate, acid phosphooxypolyoxypropylene glycol monomethacrylate, phosphate-modified epoxy acrylate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 4-hydroxyphenyl acrylate, 4-hydroxyphenyl methacrylate, 2-methacryloyloxyethyl succinic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

[0042] Among these, acrylic acid, 2-methacryloyloxyethyl acid phosphate, 4-hydroxyphenyl methacrylate, and 2-acrylamido-2-methylpropanesulfonic acid are preferred, with acrylic acid being more preferred. Including units derived from such monomers tends to further reduce viscosity and suppress changes in hardness. Unit α may be used alone or in combination of two or more types.

[0043] The content of unit α may preferably be 1.0 mol% or more, 5.0 mol% or less, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 45 mol% or more, based on 100 mol% of the total of units α, β, and γ. Furthermore, the content of unit α may preferably be 85 mol% or less, 80 mol% or less, 75 mol% or less, or 70 mol% or less, based on 100 mol% of the total of units α, β, and γ. When the content of unit α is within the above range, viscosity tends to decrease further and hardness changes tend to be suppressed further.

[0044] The molar ratio of unit α to unit β is preferably 0.5 or more, 1.0 or more, 2.5 or more, 5.0 or more, 10 or more, 15 or more, 20 or more, or 25 or more. Furthermore, the molar ratio of unit α to unit β is preferably 150 or less, 100 or less, 75 or less, 50 or less, or 40 or less. When the molar ratio of unit α to unit β is within the above range, viscosity tends to decrease further and hardness changes tend to be suppressed further.

[0045] 1.1.2.2. (Meth)acrylic monomer unit β The (meth)acrylic monomer unit β is a repeating unit having a cationic group. The cationic group is not particularly limited, but it is preferably one or more selected from the group consisting of primary amino groups, secondary amino groups, tertiary amino groups, and quaternary ammonium salts. Among these, tertiary amino groups are more preferred. Having such a group tends to improve the dispersibility of the filler component.

[0046] Furthermore, it is preferable that unit β further has an electron-donating group bonded to the cationic group. Such an electron-donating group is not particularly limited as long as it has the effect of stabilizing the cation of the cationic group. For example, an acrylic monomer containing an electron-donating substituent such as a methyl group at the α-carbon of the amino group may be used. Having such a group tends to further improve the dispersibility of the filler component.

[0047] The unit β preferably has no electron-withdrawing group bonded to the cationic group, or has a group with low electron-withdrawing properties. Such an electron-withdrawing group is not particularly limited as long as it has the effect of destabilizing the cation of the cationic group. For example, an acrylic monomer that does not have a substituent of an electron-withdrawing group such as a carboxyl group on the α-carbon of the amino group may be used. By adopting such a structure, the dispersibility of the filler component tends to be further improved.

[0048] Such (meth)acrylic monomers are not particularly limited, but examples include 1-aminoethyl acrylate, 1-aminopropyl acrylate, 1-aminoethyl methacrylate, 1-aminopropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, t-butylaminoethyl (meth)acrylate, dimethylaminoethyl methacrylate quaternary salt, 1,2,2,6,6-pentamethyl-4-piperidyl acrylic acid, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylic acid, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and dimethylaminoethyl acrylate benzyl chloride quaternary salt.

[0049] Among these, 1,2,2,6,6-pentamethyl-4-piperidyl acrylic acid, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, and 1-aminoethyl methacrylate are preferred, with 1,2,2,6,6-pentamethyl-4-piperidyl acrylic acid and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate being more preferred. Including units derived from such monomers tends to further reduce viscosity and suppress changes in hardness. Unit β may be used alone or in combination of two or more types.

[0050] The content of unit β is preferably 0.05 mol% or more, 0.10 mol% or more, 0.50 mol% or more, 1.00 mol% or more, or 1.50 mol% or more, relative to 100 mol% of the total of units α, β, and γ. Furthermore, the content of unit β is preferably 10 mol% or less, 8.0 mol% or less, 10 mol% or less, 6.0 mol% or less, 2.0 mol% or less, or 3.0 mol% or less, relative to 100 mol% of the total of units α, β, and γ. When the content of unit β is within the above range, viscosity tends to decrease further and hardness changes tend to be suppressed further.

[0051] 1.1.2.3. (Meth)acrylic monomer unit γ (Meth)acrylic monomer unit γ is a silicone (meth)acrylic monomer unit that does not contain cationic or anionic groups in its molecule and is a (meth)acrylic monomer having a silicone group.

[0052] The (meth)acrylic monomer γ preferably has a skeleton with high affinity or compatibility with other matrix components. The (meth)acrylic monomer γ has a silicone skeleton such as dimethylsiloxane, methylphenylsiloxane, or diphenylsiloxane. Having such a skeleton tends to improve compatibility with other matrix components and further improve the dispersibility of filler components in the heat dissipation grease.

[0053] Such (meth)acrylic monomers are not particularly limited, but examples include (meth)acrylic monomers having a siloxane skeleton such as α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane. Unit γ may be used alone or in combination of two or more types.

[0054] The weight-average molecular weight of (meth)acrylic monomer γ is preferably 300 or more, 1000 or more, 2000 or more, 3000 or more, 4000 or more, 5000 or more, 6000 or more, 7000 or more, or 8000 or more. Furthermore, the weight-average molecular weight of (meth)acrylic monomer γ is preferably 50000 or less, 40000 or less, 30000 or less, 20000 or less, 15000 or less, 12500 or less, 10000 or less, or 7500 or less. Moreover, when the weight-average molecular weight of (meth)acrylic monomer γ is within the above range, viscosity tends to decrease further and hardness changes tend to be suppressed further.

[0055] Furthermore, the (meth)acrylic monomer γ may contain at least one or both of the following: a silicone (meth)acrylic monomer unit γ1 having a weight-average molecular weight of 1000 or more and less than 8000; and a silicone (meth)acrylic monomer unit γ2 having a weight-average molecular weight of 8000 or more and 50000 or less.

[0056] The content of unit γ may preferably be 10 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, 30 mol% or more, 35 mol% or more, or 40 mol% or more, relative to 100 mol% of the total of units α, β, and γ. Furthermore, the content of unit γ may preferably be 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, or 50 mol% or less, relative to 100 mol% of the total of units α, β, and γ. When the content of unit γ is within the above range, viscosity tends to decrease further and hardness changes tend to be suppressed further.

[0057] 1.1.2.4.Weight average molecular weight The weight-average molecular weight of surfactant B is preferably 5000 or more, 7500 or more, 10000 or more, 20000 or more, 30000 or more, 40000 or more, or 50000 or more. A weight-average molecular weight of 5000 or more for surfactant B allows for maintaining dispersibility even when held at high temperatures for extended periods, and tends to further suppress changes in the hardness of the heat dissipation grease.

[0058] The weight-average molecular weight of surfactant B is preferably 500,000 or less, 250,000 or less, 150,000 or less, 125,000 or less, 100,000 or less, or 75,000 or less. When the weight-average molecular weight of surfactant B is 500,000 or less, the viscosity of the heat dissipation grease tends to decrease further, and the handling properties tend to improve further.

[0059] In this embodiment, each weight-average molecular weight can be determined by GPC (gel permeation chromatography).

[0060] 1.1.2.5. Surfactant B1 Surfactant B may contain at least one or both of surfactant B1, which has a silicone (meth)acrylic monomer unit γ1 with a weight-average molecular weight of 1000 or more and less than 8000, and surfactant B2, which has a silicone (meth)acrylic monomer unit γ2 with a weight-average molecular weight of 8000 or more and 50000 or less. It is preferable that it contains at least surfactant B2, and preferably both surfactant B1 and surfactant B2. This tends to further reduce viscosity and further suppress hardness changes.

[0061] Surfactant B1 has a silicone (meth)acrylic monomer unit γ1 with a weight-average molecular weight of 1000 or more and less than 8000, and may also have arbitrary units α and β. Using surfactant B1 tends to further reduce viscosity.

[0062] The content of surfactant B1 may preferably be 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more, relative to the total amount of matrix components. Alternatively, the content of surfactant B1 may preferably be 35% by mass or less, 30% by mass or less, 25% by mass or less, or 20% by mass or less, relative to the total amount of matrix components. When the content of surfactant B1 is within the above range, the viscosity tends to decrease further.

[0063] 1.1.2.6. Surfactant B2 Surfactant B2 has a silicone (meth)acrylic monomer unit γ2 with a weight-average molecular weight of 8000 to 50000, and may also have arbitrary units α and β. Hardness changes tend to be more suppressed.

[0064] The content of surfactant B2 may preferably be 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more, relative to the total amount of matrix components. Alternatively, the content of surfactant B2 may preferably be 35% by mass or less, 30% by mass or less, 25% by mass or less, or 20% by mass or less, relative to the total amount of matrix components. When the content of surfactant B2 is within the above range, hardness changes tend to be further suppressed.

[0065] 1.1.2.7.Viscosity The viscosity of surfactant B at 25°C is preferably 10 mPa·s or more, 50 mPa·s or more, 75 mPa·s or more, or 100 mPa·s or more. Alternatively, the viscosity of surfactant B at 25°C is preferably 2000 mPa·s or less, 1500 mPa·s or less, 1000 mPa·s or less, or 750 mPa·s or less. When the viscosity of surfactant B is within the above range, hardness changes tend to be more suppressed.

[0066] 1.1.2.8. Method for producing surfactant B The method for producing surfactant B is not particularly limited, and known polymerization methods for (meth)acrylic monomers can be used. Examples of polymerization methods include radical polymerization and anionic polymerization. Among these, radical polymerization is preferred.

[0067] The thermal polymerization initiator used in radical polymerization is not particularly limited, but examples include azo compounds such as azobisisobutyronitrile; and organic peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, and di-tert-butyl peroxide. The photopolymerization initiator used in radical polymerization is also not particularly limited, but examples include benzoin derivatives. Furthermore, known polymerization initiators used in living radical polymerization, such as ATRP and RAFT, can also be used.

[0068] Polymerization conditions are not particularly limited and can be adjusted as appropriate depending on the boiling point of the initiator and solvent used, as well as the type of monomer.

[0069] The order in which monomers are added is not particularly limited. For example, from the viewpoint of synthesizing a random copolymer, the monomers may be mixed and polymerization may be started, or from the viewpoint of synthesizing a block copolymer, the monomers may be added sequentially to the polymerization system.

[0070] 1.1.3. Silane coupling agent C The matrix component may further contain silane coupling agent C. The inclusion of silane coupling agent C tends to further reduce viscosity and suppress changes in hardness.

[0071] The silane coupling agent C is not particularly limited, but examples include epoxysilanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; aminosilanes such as aminopropyltriethoxysilane, ureidopropyltriethoxysilane, and N-phenylaminopropyltrimethoxysilane; and hydrophobic silane compounds such as phenyltrimethoxysilane, methyltrimethoxysilane, octadecyltrimethoxysilane, and n-decyltrimethoxysilane.

[0072] Among these, hydrophobic silane compounds are more preferred. Using such a silane coupling agent C tends to further reduce viscosity and suppress changes in hardness.

[0073] The content of silane coupling agent C may preferably be 2.0% by mass or more, 5.0% by mass or more, 7.0% by mass or more, or 10.0% by mass or more, relative to the total amount of matrix components. Alternatively, the content of silane coupling agent C may preferably be 16.0% by mass or less, 12.0% by mass or less, 10.0% by mass or less, 5.0% by mass or less, or 3.0% by mass or less, relative to the total amount of matrix components. When the content of silane coupling agent C is within the above range, viscosity tends to decrease further and hardness changes tend to be suppressed further.

[0074] 1.2. Filler components The filler components include alumina D1, magnesium oxide D2 and / or aluminum nitride D3, and may further include silica D4 or other fillers D5 as needed.

[0075] The filler component content may preferably be 60% or more by volume, 65% or more by volume, 70% or more by volume, 75% or more by volume, 80% or more by volume, or 85% or more by volume, relative to the total amount of heat dissipation grease. Alternatively, the filler component content may preferably be 95% or less by volume, or 90% or less by volume, relative to the total amount of heat dissipation grease. When the filler component content is within the above range, thermal conductivity tends to be further improved, viscosity to be further reduced, and hardness changes tend to be further suppressed.

[0076] Each filler component may be surface-treated with a surface treatment agent by a known wet or dry treatment method. The surface treatment agent is not particularly limited, but examples include the silane coupling agent C described above, although the silane coupling agent C may be provided separately regardless of this surface treatment.

[0077] 1.2.1. Alumina D1 The average particle size of alumina D1 is preferably 0.1 to 120 μm, and more preferably 0.1 to 90 μm. When the average particle size of alumina D1 is within this range, the fluidity, dispersibility, and packing properties tend to improve. In this embodiment, the average particle size refers to D50 (median diameter).

[0078] The alumina D1 content may preferably be 40% by mass or more, 45% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, or 70% by mass or more, relative to the total amount of filler components. Alternatively, the alumina D1 content may preferably be 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, or 70% by mass or less, relative to the total amount of filler components. When the alumina D1 content is within the above range, thermal conductivity tends to be further improved, viscosity further reduced, and hardness changes tend to be further suppressed.

[0079] Furthermore, alumina D1 may be used by mixing fillers with different average particle sizes. For example, alumina D1 may contain any of alumina D11 with an average particle size of 55 μm or more, alumina D12 with an average particle size of 10 μm or more and less than 55 μm, or alumina D13 with an average particle size of 0.10 μm or more and less than 10 μm, and these may be used in combination. Using such alumina D1 tends to further improve thermal conductivity, further reduce viscosity, and further suppress hardness changes.

[0080] 1.2.1.1. Alumina D11 Alumina D1 preferably further contains alumina D11 with an average particle size of 55 μm or more. This tends to further improve thermal conductivity.

[0081] The average particle size of alumina D11 is 55 μm or more, preferably 60 μm or more. Alternatively, the average particle size of alumina D11 may be 110 μm or less, 100 μm or less, 90 μm or less, or 80 μm or less. When the average particle size of alumina D11 is within the above range, thermal conductivity tends to be further improved, viscosity to be further reduced, and hardness changes tend to be further suppressed.

[0082] The alumina D11 content may preferably be 5% by mass or more, 10% by mass or more, or 15% by mass or more, relative to the total amount of filler components. Alternatively, the alumina D11 content may preferably be 35% by mass or less, 30% by mass or less, or 25% by mass or less, relative to the total amount of filler components. When the alumina D11 content is within the above range, thermal conductivity tends to be further improved, viscosity to be further reduced, and hardness changes tend to be further suppressed.

[0083] 1.2.1.2. Alumina D12 The average particle size of alumina D12 may be 10 μm or more, preferably 15 μm or more, or 20 μm or more. Alternatively, the average particle size of alumina D12 may be less than 55 μm, preferably 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, or 30 μm or less. When the average particle size of alumina D12 is within the above range, thermal conductivity tends to be further improved, viscosity to be further reduced, and hardness changes tend to be further suppressed.

[0084] The alumina D12 content may preferably be 1.0% by mass or more, 2.5% by mass or more, or 5.0% by mass or more, relative to the total amount of filler components. Alternatively, the alumina D12 content may preferably be 20% by mass or less, 15% by mass or less, or 10% by mass or less, relative to the total amount of filler components. When the alumina D12 content is within the above range, thermal conductivity tends to be further improved, viscosity to be further reduced, and hardness changes tend to be further suppressed.

[0085] 1.2.1.3. Alumina D13 The average particle size of alumina D13 may be 0.10 μm or more, preferably 0.20 μm or more, or 0.30 μm or more. Alternatively, the average particle size of alumina D13 may be less than 10 μm, preferably 8.0 μm or less, 6.0 μm or less, or 5.0 μm or less. When the average particle size of alumina D13 is within the above range, thermal conductivity tends to be further improved, viscosity to be further reduced, and hardness changes tend to be further suppressed.

[0086] The alumina D13 content may preferably be 20% by mass or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more, relative to the total amount of filler components. The alumina D12 content may preferably be 60% by mass or less, 55% by mass or less, 50% by mass or less, or 45% by mass or less, relative to the total amount of filler components. When the alumina D13 content is within the above range, thermal conductivity tends to be further improved, viscosity further reduced, and hardness changes tend to be further suppressed.

[0087] 1.2.2. Magnesium oxide D2 and / or aluminum nitride D3 The average particle size of magnesium oxide D2 is preferably 300 μm or less, 250 μm or less, 200 μm or less, 175 μm or less, 150 μm or less, or 125 μm or less. Furthermore, the average particle size of magnesium oxide D2 and aluminum nitride D3 is preferably 25 μm or more, 50 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, 100 μm or more, or 110 μm or more. When the average particle size of magnesium oxide D2 is within the above range, the thermal conductivity tends to improve, the viscosity to decrease further, and the hardness change to be more suppressed.

[0088] The average particle size of aluminum nitride D3 is preferably 300 μm or less, 250 μm or less, 200 μm or less, 175 μm or less, 150 μm or less, 125 μm or less, or 110 μm or less. The average particle size of magnesium oxide D2 and aluminum nitride D3 is preferably 25 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, or 90 μm or more. When the average particle size of aluminum nitride D3 is within the above range, the thermal conductivity tends to be further improved, the viscosity further reduced, and the hardness change further suppressed.

[0089] The total content of magnesium oxide D2 and aluminum nitride D3 is 10% by mass or more relative to the total amount of filler components, preferably 15% by mass or more, preferably 20% by mass or more, preferably 25% by mass or more, preferably 30% by mass or more, preferably 35% by mass or more, preferably 40% by mass or more, and preferably 45% by mass or more. Furthermore, the total content of magnesium oxide D2 and aluminum nitride D3 is 60% by mass or less relative to the total amount of filler components, preferably 55% by mass or less, preferably 50% by mass or less, and preferably 45% by mass or less. When the silica D2 content is within the above range, thermal conductivity tends to be further improved, viscosity further reduced, and hardness changes tend to be further suppressed.

[0090] 1.2.3. Silica D4 The filler component may also contain silica D4. This tends to further reduce viscosity and suppress changes in hardness.

[0091] The silica D4 content may preferably be 0.1% by mass or more, 1.0% by mass or more, 2.5% by mass or more, or 5.0% by mass or more, relative to the total amount of heat dissipation filler. Alternatively, the silica D4 content may preferably be 15% by mass or less, 10% by mass or less, or 5.0% by mass or less, relative to the total amount of heat dissipation filler. When the silica D4 content is within the above range, thermal conductivity tends to be further improved, viscosity to be further reduced, and hardness changes tend to be further suppressed.

[0092] 1.2.4. Other Fillers D5 Other fillers D4 are not particularly limited, but examples include boron nitride, silicon nitride, zinc oxide, aluminum hydroxide, metallic aluminum, diamond, carbon, indium, gallium, copper, silver, iron, nickel, gold, tin, and metallic silicon.

[0093] Among these, it is preferable to include at least one selected from the group consisting of boron nitride, silicon nitride, zinc oxide, aluminum hydroxide, metallic aluminum, copper, silver, and diamond. Using such filler D5 tends to improve filling performance and further enhance the thermal conductivity of the heat dissipation grease. These fillers D5 may be used individually or in combination of two or more types.

[0094] 2.Electronic equipment The electronic device of this embodiment comprises a heating element, a heat sink, and the thermal grease, with the thermal grease placed between the heating element and the heat sink. In this electronic device, the heating element and the heat sink are thermally bonded via the thermal grease.

[0095] Here, the heat-generating element is not particularly limited, but examples include motors, battery packs, circuit boards used in automotive power supply systems, power transistors, microprocessors, and other heat-generating electronic components. Among these, electronic components used in automotive power supply systems are preferred. Furthermore, the heat sink is not particularly limited as long as it is a component configured for the purpose of heat dissipation or heat absorption.

[0096] There are no particular limitations on the method of bonding the heat-generating element and the heat sink via thermal grease. For example, an electronic device may be obtained by bonding the heat-generating element and the heat sink using thermal grease. [Examples]

[0097] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples. Unless otherwise specified, each operation was carried out at room temperature (25°C).

[0098] 1. Preparation of heat dissipation grease (Examples 1-8 and Comparative Examples 1-4) A thermal grease was prepared by mixing silicone A, surfactant B, silane coupling agent C, and filler D according to the composition shown in Table 1. In Table 1, the composition of each component is shown such that the total amount of matrix and filler components is 100 parts by mass. The mixing ratio of matrix and filler components is expressed as the total amount of filler component. The following evaluations were performed using each of the obtained thermal greases. The results are shown in Table 1.

[0099] 1.1. Raw materials (Silicone A) Low molecular weight silicone A1: Shin-Etsu Silicone Co., Ltd. "KF-96-50CS" High-molecular-weight silicone A2: Momentive's "SRH-32" (Surfactant B) Surfactant B1 obtained by the following preparation example 1 Surfactant B2 obtained by the following preparation example 2 (Silane coupling agent C) n-decyltrimethoxysilane: Manufactured by Dow Toray Corporation, "DOWSIL Z-6210 Silane" (Alumina D1) Aluminum oxide: Manufactured by Denka Co., Ltd., "DAW120", average particle size: 120 μm Aluminum oxide: Manufactured by Denka Co., Ltd., "DAW70", average particle size: 70 μm Aluminum oxide: Manufactured by Denka Co., Ltd., "DAW20", average particle size: 20 μm Aluminum oxide: Manufactured by Denka Co., Ltd., "DAW05", average particle size: 5 μm Aluminum oxide: Manufactured by Denka Co., Ltd., "AA05", average particle size: 0.5 μm Aluminum oxide: Denka Co., Ltd., "ASFP40", average particle size: 0.4 μm Aluminum oxide: Denka Co., Ltd., "ASFP20", average particle size: 0.2 μm (Magnesium Oxide D2) Magnesium oxide: Manufactured by Denka Co., Ltd., "DMG120", particle size 120 μm (Aluminum Nitride D3) Aluminum nitride: Manufactured by Combustion Synthesis Co., Ltd., "AN-HF100LG", particle size 100 μm Aluminum nitride: Manufactured by Combustion Synthesis Co., Ltd., "AN-HF80LG", particle size 80 μm (Silica D4) Silica: Manufactured by Ryumori Co., Ltd., "5X", average particle size 1.2 μm

[0100] The average particle size of each filler component was measured using a Shimadzu Corporation "SALD-20 Laser Diffraction Particle Size Distribution Analyzer". For the evaluation sample, 5g of each filler component to be measured was added to 50ml of pure water in a glass beaker, stirred with a spatula, and then dispersed in an ultrasonic cleaner for 10 minutes. The dispersed solution of each filler component was then added drop by drop to the sampler section of the analyzer using a dropper, and measurements were taken once the absorbance stabilized. The average particle size was measured using D50 (median diameter).

[0101] 1.2. Preparation Example 1 (Surfactant B1) In an autoclave equipped with a stirrer, acrylic acid (manufactured by Toagosei Co., Ltd.) as unit α, methacrylate-1,2,2,6,6-pentamethyl-4-piperidyl (ADEKA Corporation's "ADEKA Stab LA-82") as unit β, and α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane (JNC Corporation's "Cylaprene FM-0725", number average molecular weight 5000) as unit γ were added. Next, azobisisobutyronitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) and a mixed solution of toluene and 2-propanol as solvents were added, and the autoclave was purged with nitrogen. After that, the autoclave was heated in an oil bath at 65°C for 20 hours to carry out radical polymerization. After polymerization was complete, the mixture was degassed under reduced pressure at 120°C for 1 hour to obtain surfactant B1.

[0102] Gas chromatography analysis revealed that the polymerization rate relative to 100% of the monomer charge was over 98%. From this, it was estimated that the ratio of each monomer unit in surfactant B1 was approximately the same as the monomer charge ratio. Specifically, surfactant B1 was a copolymer containing unit α: 48.4 mol%, unit β: 1.6 mol%, and unit γ: 50 mol%.

[0103] Furthermore, the weight-average molecular weight of the obtained surfactant B1 was determined using GPC (gel permeation chromatography) as a weight-average molecular weight equivalent to standard polystyrene, and was found to be 65,000. The measurement conditions were as follows. High-speed GPC system: Tosoh Corporation's "HLC-8020" Columns: One 6.0mm ID x 4.0cm column of Tosoh Corporation's "TSK guardcolumn MP (xL)" and two 7.8mm ID x 30.0cm columns of Tosoh Corporation's "TSK-GELMULTIPOREHXL-M" (16,000 theoretical plates), for a total of three columns (32,000 theoretical plates in total). Developing solvent: tetrahydrofuran Detector: RI (Differential Refractive Index Meter)

[0104] 1.3. Preparation Example 2 (Surfactant B2) In an autoclave equipped with a stirrer, acrylic acid (manufactured by Toagosei Co., Ltd.) as unit α, methacrylate-1,2,2,6,6-pentamethyl-4-piperidyl (ADEKA Corporation's "ADEKA Stab LA-82") as unit β, and α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane (JNC Corporation's "Cylaprene FM-0725", number average molecular weight 10000) as unit γ were added. Next, azobisisobutyronitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) and a mixed solution of toluene and 2-propanol as solvents were added, and the autoclave was purged with nitrogen. After that, the autoclave was heated in an oil bath at 65°C for 20 hours to carry out radical polymerization. After polymerization was complete, the mixture was degassed under reduced pressure at 120°C for 1 hour to obtain surfactant B2.

[0105] Gas chromatography analysis revealed that the polymerization rate relative to 100% of the monomer charge was over 98%. From this, it was estimated that the ratio of each monomer unit in surfactant B2 was approximately the same as the monomer charge ratio. Specifically, surfactant B2 was a copolymer containing unit α: 67.7 mol%, unit β: 2.3 mol%, and unit γ: 30 mol%.

[0106] Furthermore, the weight-average molecular weight of the obtained surfactant B2 was determined using GPC (gel permeation chromatography) as a weight-average molecular weight on a standard polystyrene basis, and was found to be 85,000. The measurement conditions were the same as in Preparation Example 1.

[0107] 2. Evaluation 2.1. Cracks Two 76mm square alkali-free glass plates were prepared. A layer of thermal grease, 20mm in diameter and 1mm thick, was applied to the center of one of the glass plates, and the sample was sandwiched between the other glass plates and kept in a 150°C environment. After 24 hours, the presence or absence of cracks was visually checked.

[0108] 2.2.Viscosity Using a Thermo Scientific MARS III rotary rheometer, a 35mm diameter parallel plate was used as the upper fixture. Thermal grease was placed on a 35mm diameter lower plate, which was temperature-controlled by a Peltier element, and compressed to a thickness of 1mm using the upper fixture. The excess was scraped off, and measurements were taken at 25°C. Shear rate: 10s -1 The viscosity was measured. A viscosity of 1000 Pa·s or less is preferable because it makes handling easier, such as the application of the grease.

[0109] 2.3. Thermal conductivity A rectangular copper jig with a heater embedded in it, with a 100mm tip. 2 (10mm x 10mm) and a rectangular copper jig with cooling fins attached, with a tip of 100mm 2Thermal resistance was measured by placing thermal grease between (10mm x 10mm) pieces and varying the gap thickness from 0.05mm to 0.30mm. The thermal conductivity (W / m·k) was calculated and evaluated from the gradient between thermal resistance and thickness. Thermal resistance was calculated using the following formula by applying 10W of power to a heater and holding it for 30 minutes, measuring the temperature difference (°C) between the copper jigs. Thermal resistance (℃ / W) = {temperature difference (℃) / power (W)} A thermal conductivity of 8.0 W / m·K or higher is preferable due to its excellent heat dissipation properties.

[0110] 2.4. Asker C Hardness Change The Asker C hardness of the heat dissipation grease was measured using the "Asker Rubber Hardness Tester Type C" manufactured by Polymer Instruments Co., Ltd. Table 1 shows some of the Asker C hardness values ​​measured after storage at a predetermined time of 0 to 500 hours in a 150°C environment, with the initial hardness measured immediately after preparation set as the baseline (0).

[0111] [Table 1] *This value represents the change in hardness after 500 hours.

[0112] [Table 2] -: The thermal conductivity is less than 8.0 W / m·K, which does not meet the target value, so no other evaluations were performed. [Industrial applicability]

[0113] The heat dissipation grease of the present invention has industrial applicability as a heat dissipation grease for thermally connecting a heat-generating element and a heat sink in electronic equipment.

Claims

1. It contains matrix components and filler components, The matrix component comprises silicone A and surfactant B. The filler component comprises alumina D1, magnesium oxide D2 and / or aluminum nitride D3. The content of surfactant B may be 15% by mass or more relative to the total amount of matrix components. The total content of magnesium oxide D2 and aluminum nitride D3 is 10 to 60% by mass relative to the total amount of the filler components. The aforementioned silicone A Non-crosslinked low molecular weight silicone A1 having a weight-average molecular weight of 500 or more and 100,000 or less, A non-crosslinked polymeric silicone A2 having a weight-average molecular weight of 150,000 or more and 1,000,000 or less, is included. Thermal grease.

2. The content of the filler component is 60 to 95% by volume relative to the total amount of the heat dissipation grease. The heat dissipation grease according to claim 1.

3. The average particle size of the magnesium oxide D2 is 25 to 300 μm. The average particle size of the aluminum nitride D3 is 25 to 300 μm. The heat dissipation grease according to claim 1.

4. The alumina D1 further comprises alumina D11 with an average particle size of 55 μm or more. The heat dissipation grease according to claim 1.

5. The content of the non-crosslinked low molecular weight silicone A1 is 50 to 80% by mass relative to the total amount of the matrix components. The heat dissipation grease according to claim 1.

6. The content of the non-crosslinked polymeric silicone A2 is 3.0 to 25% by mass relative to the total amount of the matrix components. The heat dissipation grease according to claim 1.

7. The content of surfactant B is 15 to 55% by mass relative to the total amount of the matrix components. The heat dissipation grease according to claim 1.

8. The surfactant B is Surfactant B1 having a silicone (meth)acrylic monomer unit γ1 having a weight-average molecular weight of 1000 or more and less than 8000, and / or The surfactant B2 contains a silicone (meth)acrylic monomer unit γ2 having a weight-average molecular weight of 8,000 or more and 50,000 or less. The heat dissipation grease according to claim 1.

9. The matrix component further comprises a silane coupling agent C. The heat dissipation grease according to claim 1.

10. The content of the silane coupling agent C is 2.0 to 16.0% by mass relative to the total amount of the matrix components. The heat dissipation grease according to claim 9.

11. The filler component further comprises silica D4, The silica D4 content is 0.1 to 10% by mass relative to the total amount of the filler components. The heat dissipation grease according to claim 1.

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