Thermally conductive grease composition

Abstract

A thermally conductive grease composition containing a base oil and a thermally conductive filler containing zinc oxide and aluminum nitride.

Description

Technical Field

[0001] This disclosure relates to a thermally conductive grease composition. Background Technology

[0002] Semiconductor components used in electronic devices, such as computer CPUs or power semiconductors used for power control, generate heat during operation. To protect these semiconductor components from heat and ensure their proper functioning, methods exist to conduct the generated heat to heat dissipation components such as heat sinks. Thermally conductive grease compositions are applied between the heat-generating semiconductor components and the heat dissipation components to ensure a tight seal and improve heat conduction.

[0003] As a thermally conductive grease composition, for example, Japanese Patent Application Publication No. 2006-210437 discloses: "A high thermal conductivity compound, characterized in that the high thermal conductivity compound contains (A) a metal powder with a thermal conductivity of 200 W / (m·K) or higher and an average particle size of 5 to 50 μm; (B) a coarse inorganic filler with a new Mohs hardness of 6 or higher and an average particle size of 5 to 50 μm; (C) a fine inorganic filler with an average particle size of 0.15 to 2 μm; (D) a base oil; and (E) a mixture selected from (poly)glycerol ethers and alkenyl succinimides." The high thermal conductivity compound contains one or more surface modifiers of its boron derivatives, wherein components (A), (B), (C), (D) and (E) are formulated in the following proportions: the total content of (A), (B) and (C) is in the range of 88 to 97% by mass in the total amount of the compound, and the mass ratio of the total content of (A) and (B) to the content of (C) is in the range of 20:80 to 85:15, the content of (D) is less than 12% by mass in the total amount of the compound, and the content of (E) is 0.08 to 4% by mass in the total amount of the composition.

[0004] Furthermore, in thermally conductive grease compositions, thermally conductive fillers selected from various thermally conductive materials are used to improve thermal conductivity. As thermally conductive materials, metal oxides such as zinc oxide and aluminum oxide are used; nitrides such as silicon nitride, aluminum nitride, and boron nitride; and metal powders such as aluminum, copper, and silver. Among these thermally conductive materials, aluminum nitride is known as a thermally conductive material with high thermal conductivity, and various improvements have been proposed (see, for example, Japanese Patent Application Publication No. 2017-014445 and International Publication No. 2014 / 123247). Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] With the miniaturization and increasing density of electronic devices, the demand for thermally conductive grease compositions with high thermal conductivity is increasing. As a means to improve the thermal conductivity of thermally conductive grease compositions, for example, high filling of thermally conductive fillers or the use of fillers with high thermal conductivity can be considered.

[0007] However, high filler content can lead to increased viscosity and reduced coatability of the thermally conductive grease composition. Reduced coatability makes film coating of the thermally conductive grease composition difficult, thus degrading thermal resistance. On the other hand, examples of fillers with high thermal conductivity include metal fillers and metal nitrides (such as aluminum nitride), but fillers with high thermal conductivity generally have poor compatibility with the resin components commonly used in thermally conductive grease compositions. Therefore, the presence of fillers with high thermal conductivity can lead to increased viscosity of the thermally conductive grease composition, which may also result in reduced coatability.

[0008] One embodiment of this disclosure aims to solve the problem of providing a thermally conductive grease composition with high thermal conductivity and excellent coatability.

[0009] Methods for solving problems

[0010] This disclosure includes the following aspects.

[0011] <1> A thermally conductive grease composition comprising a base oil and a thermally conductive filler comprising zinc oxide and aluminum nitride. <2> according to <1> The thermally conductive grease composition wherein the content of aluminum nitride is greater than the content of zinc oxide.

[0012] <3> according to <1> or <2> The thermally conductive grease composition comprises thermally conductive filler A with a volume average particle size of 0.15 μm or more and less than 2 μm, and thermally conductive filler B with a volume average particle size of 2 μm or more and less than 40 μm. Thermally conductive filler A comprises zinc oxide, and thermally conductive filler B comprises aluminum nitride.

[0013] <4> according to <3> The thermally conductive grease composition wherein the ratio of the content of thermally conductive filler A to the content of thermally conductive filler B, on a mass basis, is 0.20 or more and 0.80 or less.

[0014] <5> according to <3> The thermally conductive grease composition wherein the ratio of the content of thermally conductive filler A to the content of thermally conductive filler B, on a mass basis, is 0.50 or more and 0.95 or less.

[0015] <6> according to <5> The thermally conductive grease composition wherein the ratio of the content of thermally conductive filler A to the content of thermally conductive filler B, on a mass basis, is 0.50 or more and 0.80 or less.

[0016] <7> according to <1> ~ <6> The thermally conductive grease composition according to any one of the following methods, wherein the total content of thermally conductive fillers is 90% by mass or more and 98% by mass or less relative to the total amount of the thermally conductive grease composition.

[0017] <8> according to <1> ~ <7> The thermally conductive grease composition according to any one of the following, wherein the thermally conductive grease composition further comprises a dispersant.

[0018] <9> according to <1> ~ <8> The thermally conductive grease composition according to any one of the following methods, wherein the base oil comprises a polyalphaolefin and an organic ester.

[0019] Invention Effects

[0020] According to one embodiment of the present disclosure, a thermally conductive grease composition with high thermal conductivity and excellent coatability is provided. Detailed Implementation

[0021] The following describes an embodiment as an example of this disclosure. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the invention.

[0022] In the numerical ranges described in this specification, the upper or lower limit of one numerical range can be replaced with the upper or lower limit of another numerical range described in other stages. Furthermore, the upper or lower limit of the numerical range described in this specification can be replaced with the values ​​shown in the embodiments.

[0023] Each component may also contain multiple corresponding substances.

[0024] When referring to the amount of each component in a composition, if the composition contains multiple substances corresponding to each component, unless otherwise specified, it refers to the total amount of those multiple substances present in the composition.

[0025] In this disclosure, "mass%" and "weight%" have the same meaning, and "parts of mass" and "parts of weight" have the same meaning.

[0026] In this disclosure, a combination of two or more preferred methods is a more preferred method.

[0027] In this disclosure, "JIS" is an abbreviation for Japanese Industrial Standards.

[0028] Unless otherwise specified, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in this disclosure are calculated using a gel permeation chromatography (GPC) analyzer with a TSKgel SuperHM-H column (a product name manufactured by Tosoh Corporation), a solvent PFP (pentafluorophenol) / chloroform = 1 / 2 (mass ratio), a differential refractive index detector, and polystyrene as a standard substance.

[0029] <Thermoconductive grease composition>

[0030] The thermally conductive grease composition disclosed herein contains a base oil and a thermally conductive filler comprising zinc oxide and aluminum nitride.

[0031] With the above-described structure, the thermally conductive grease composition disclosed herein exhibits high thermal conductivity and excellent spreadability. The reason for this effect of the thermally conductive grease composition disclosed herein is not clear, but the inventors of this application speculate as follows.

[0032] Aluminum nitride is a material with excellent thermal conductivity. However, when aluminum nitride is used alone in high amounts as a thermally conductive filler in a thermally conductive grease composition, the spreadability of the grease composition may be significantly reduced, or the composition may fail to grease. Here, "grease formation" refers to the composition containing base oil and thermally conductive filler becoming a viscous paste under external force at room temperature (25°C). On the other hand, it is speculated that in the thermally conductive grease composition disclosed herein, by including both zinc oxide and aluminum nitride as thermally conductive fillers, the interaction between zinc oxide and aluminum nitride specifically results in high thermal conductivity and good spreadability.

[0033] (Base oil)

[0034] The thermally conductive grease compositions disclosed herein contain a base oil.

[0035] There are no specific limitations on base oils; examples include mineral oils, synthetic hydrocarbon oils, organic acid esters, phosphate esters, silicone oils, and fluorinated oils.

[0036] A thermally conductive grease composition may contain only one type of base oil or a combination of two or more base oils.

[0037] Examples of mineral oils include substances refined from the lubricating oil fraction of crude oil through appropriate combinations of solvent refining, hydrorefining, hydrocracking refining, and hydrodewaxing. Additionally, highly refined paraffinic mineral oils, such as those produced by solvent dewaxing or hydrodewaxing of hydrorefined oils and catalytic isomerized oils, can also be listed.

[0038] Examples of synthetic hydrocarbon oils include polyalphaolefins.

[0039] Polyalphaolefins include substances that are polymerized from two or more alpha-olefins, either alone or in combination, made from ethylene, propylene, butene, and their derivatives.

[0040] As a polyalphaolefin, polymers of alphaolefins with 6 or more and 18 or fewer carbon atoms are preferred.

[0041] As a polyalphaolefin, it preferably comprises at least one polymer selected from the group consisting of polymers selected from 1-decene and 1-dodecene polymers.

[0042] Examples of organic acid esters include monoesters, diesters, and polyol esters.

[0043] As monoesters, esters of monocarboxylic acids and alcohols can be listed.

[0044] As monocarboxylic acids, examples include butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, eicosanoic acid, docosanoic acid, palmitoleic acid, oleic acid, ricinoleic acid, and other fatty acids; acrylic acid; methacrylic acid, etc.

[0045] Alcohols used for synthesizing monoesters include oleyl alcohol, lauryl alcohol, methanol, ethanol, pentanol, hexanol, ethylene glycol, propylene glycol, glycerol, neopentyl glycol, trimethylolpropane, trimethylolpropane, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, lauryl alcohol, etc.

[0046] As diesters, esters of dicarboxylic acids and alcohols can be listed.

[0047] Examples of dicarboxylic acids include adipic acid, azelaic acid, sebacic acid, and dodecanoic acid.

[0048] The alcohol used to synthesize diesters can be a monohydric alcohol or a polyhydric alcohol having two or more hydroxyl groups in one molecule.

[0049] As an alcohol used for the synthesis of diesters, the same alcohol used for the synthesis of monoesters can be used.

[0050] As polyol esters, examples include esters of polyols and saturated fatty acids.

[0051] Examples of polyols include diols and polyols that do not have a hydrogen atom on the carbon at the β-position based on the hydroxyl group.

[0052] Examples of diols include ethylene glycol, propylene glycol, butanediol, 2-butyl-2-ethylpropanediol, and 2,4-diethyl-pentanediol.

[0053] Examples of polyols that are based on a hydroxyl group and do not have a hydrogen atom at the β-position of the carbon atom include neopentyl glycol, trimethylolpropane, and pentaerythritol.

[0054] There are no particular limitations on what constitutes a saturated fatty acid; examples include heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, benzanoic acid, etc.

[0055] Examples of phosphate esters include triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, and tridimethyl phosphate.

[0056] Examples of silicone oils include dimethylpolysiloxane, methylphenylpolysiloxane, and other polysiloxanes; modified silicones, etc.

[0057] Examples of fluorinated oils include perfluoropolyethers.

[0058] From the perspective of achieving a good balance between high thermal conductivity and coatability, the base oil preferably contains polyalphaolefins and organic acid esters. Furthermore, while using base oils containing low-molecular-weight siloxane gases may lead to contact failure due to these gases, using polyalphaolefins and organic acid esters is also preferable from the viewpoint of preventing contact failure caused by low-molecular-weight siloxane gases.

[0059] The content of polyalphaolefin relative to the total content of polyalphaolefin and organic acid ester is preferably 70% or more and 99% or less by mass, more preferably 80% or more and 99% or less by mass, and even more preferably 85% or more and 99% or less by mass.

[0060] The content of the base oil, relative to the total mass of the thermally conductive grease composition, is preferably 2.0% by mass or more and 8.5% by mass or less, more preferably 3.0% by mass or more and 8.0% by mass or less, and even more preferably 3.5% by mass or more and 7.0% by mass or less.

[0061] From the perspective of balancing high thermal conductivity and coatability, the kinematic viscosity of the base oil at 40°C (also known as the 40°C kinematic viscosity) is preferably 10 mm. 2 / s or higher and 600mm 2 / s or less, preferably 20mm 2 / s or higher and 450mm 2 / s or less.

[0062] The kinematic viscosity at 40℃ is a value obtained based on the JIS K 2283:2000 kinematic viscosity test method.

[0063] (Thermal conductive filler)

[0064] The thermally conductive grease composition disclosed herein contains a thermally conductive filler. The thermally conductive filler comprises zinc oxide and aluminum nitride. Because the thermally conductive filler comprises zinc oxide and aluminum nitride, the thermally conductive grease composition disclosed herein exhibits excellent thermal conductivity and coatability. From the viewpoint of balancing thermal conductivity and coatability, it is preferable that the content of aluminum nitride is greater than the content of zinc oxide.

[0065] In this disclosure, the thermally conductive filler is a filler with a thermal conductivity of 5 W / (m·K) or higher. The thermal conductivity of the thermally conductive filler is a value determined by laser flash method (JIS R1611:2010).

[0066] There are no particular restrictions on the shape of thermally conductive fillers. They can be granular, broken, spherical, or any other shape. A preferred form is spherical.

[0067] The volume average particle size of the thermally conductive filler is preferably 0.1 μm or more and 50 μm or less, more preferably 0.15 μm or more and 45 μm or less, and even more preferably 0.15 μm or more and 40 μm or less.

[0068] In this disclosure, the volume average particle size of the thermally conductive filler is determined by laser diffraction and scattering method according to JIS Z8825:2013 (corresponding international standard: ISO13320).

[0069] Specifically, the measurement sequence is as follows: first, a laser diffraction scattering particle size analyzer is used to measure the volume distribution of the thermally conductive filler in the sample. Then, based on the obtained measurement values ​​(volume distribution), the volume average particle size of the thermally conductive filler contained in the sample can be calculated.

[0070] As an example of a measuring device, a laser diffraction scattering particle size analyzer can be a device manufactured by Shimadzu Corporation, with the product name SALD-7500nano.

[0071] Zinc oxide

[0072] There are no particular limitations on zinc oxide; examples of zinc oxide commonly used as thermally conductive fillers can be listed. Thermally conductive fillers may contain one type of zinc oxide or two or more types.

[0073] From the viewpoint of balancing thermal conductivity and coatability, the preferred particle size of zinc oxide is a volume average particle size of 0.15 μm or more and 2.0 μm or less, more preferably 0.2 μm or more and 1.5 μm or less, and even more preferably 0.3 μm or more and 1.2 μm or less.

[0074] Aluminum nitride

[0075] There are no particular limitations on aluminum nitride; examples of aluminum nitride commonly used as thermally conductive fillers can be listed. Thermally conductive fillers may contain one type of aluminum nitride or two or more types.

[0076] From the viewpoint of balancing high thermal conductivity and coatability, the preferred particle size of aluminum nitride is a volume average particle size of 5 μm or more and 40 μm or less, more preferably 6 μm or more and 30 μm or less, and even more preferably 7.5 μm or more and 25 μm or less.

[0077] The thermally conductive grease compositions disclosed herein may also contain other thermally conductive fillers besides zinc oxide and aluminum nitride, within the scope of the effects described herein. The materials of these other thermally conductive fillers are not particularly limited, and examples include magnesium oxide, aluminum oxide, titanium oxide, boron nitride, carbon, silicon carbide, and silicon dioxide.

[0078] Thermally conductive fillers can also be surface-treated. Surface-treated thermally conductive fillers can help improve affinity with other components besides thermally conductive fillers.

[0079] There are no particular restrictions on the surface treatment of thermally conductive fillers. Known treatment methods that can treat the surface of the particles constituting the thermally conductive fillers can be applied, including both physical and chemical treatments.

[0080] As a surface treatment, treatment with a surface treatment agent is preferred.

[0081] Examples of surface treatment agents include silane-based coupling agents, titanium-based coupling agents, carboxylic acid-based coupling agents, phosphate-based coupling agents, fatty acids, polymers, surfactants, and oils.

[0082] From a dispersibility perspective, thermally conductive fillers can also be surface-treated using silane-based coupling agents.

[0083] The total content of thermally conductive filler relative to the total amount of the thermally conductive grease composition is preferably 80% by mass or more and 98% by mass or less, more preferably 85% by mass or more and 97% by mass or less, and even more preferably 90% by mass or more and 97% by mass or less.

[0084] From the perspective of balancing high thermal conductivity and coatability, the thermally conductive filler preferably includes two or more thermally conductive fillers with different volume average particle sizes.

[0085] From the viewpoint of balancing high thermal conductivity and coatability, a preferred approach for thermally conductive fillers is to include thermally conductive filler A with a volume average particle size of 0.15 μm or more and less than 2 μm, and thermally conductive filler B with a volume average particle size of 2 μm or more and less than 40 μm. Thermally conductive filler A contains zinc oxide, and thermally conductive filler B contains aluminum nitride.

[0086] Thermally conductive filler A and thermally conductive filler B can each be a single type of thermally conductive filler, or they can contain two or more types of thermally conductive fillers with different volume average particle sizes.

[0087] - Thermally conductive filler A-

[0088] Thermally conductive filler A is a thermally conductive filler with a volume average particle size of 0.15 μm or more and less than 2 μm, and contains zinc oxide. Thermally conductive filler A can be surface treated.

[0089] Thermally conductive filler A may include thermally conductive fillers other than zinc oxide, but from the perspective of balancing high thermal conductivity and coatability, thermally conductive filler A is preferably composed entirely of zinc oxide.

[0090] From the viewpoint of balancing thermal conductivity and coatability, the volume average particle size of the thermally conductive filler A is preferably 0.15 μm or more and 2.0 μm or less, more preferably 0.20 μm or more and 1.5 μm or less, and even more preferably 0.30 μm or more and 1.2 μm or less. When two or more thermally conductive fillers A are included, each of the two or more thermally conductive fillers A is preferably within the above-mentioned range of volume average particle size.

[0091] The determination order of the volume average particle size of thermally conductive filler A is as described above.

[0092] - Thermally conductive filler B-

[0093] Thermally conductive filler B is a thermally conductive filler with a volume average particle size of 2 μm or more and 40 μm or less, and contains aluminum nitride. Thermally conductive filler B can be surface treated.

[0094] Thermally conductive filler B may include thermally conductive fillers other than aluminum nitride, but from the viewpoint of high thermal conductivity, thermally conductive filler B is preferably composed entirely of aluminum nitride.

[0095] From the perspective of balancing thermal conductivity and coatability, the volume average particle size of the thermally conductive filler B is preferably 5 μm or more and 40 μm or less, more preferably 6 μm or more and 30 μm or less, and even more preferably 7.5 μm or more and 25 μm or less.

[0096] When two or more thermally conductive fillers B are included, the two or more thermally conductive fillers B are preferably within the range of the above-mentioned volume average particle size.

[0097] The determination order of the volume average particle size of thermally conductive filler B is as described above.

[0098] -Preferred method for thermally conductive filler A and thermally conductive filler B-

[0099] From the viewpoint of balancing thermal conductivity and coatability, the ratio of the content of thermally conductive filler A to the content of thermally conductive filler B (content of thermally conductive filler A / content of thermally conductive filler B) is preferably 0.20 or more and 0.80 or less by mass, more preferably 0.25 or more and 0.70 or less, and even more preferably 0.30 or more and 0.60 or less in one embodiment.

[0100] From the viewpoint of balancing thermal conductivity and coatability, and further improving thermal conductivity, the ratio of the content of thermally conductive filler A to the content of thermally conductive filler B (content of thermally conductive filler A / content of thermally conductive filler B) is preferably 0.50 or more and 0.95 or less by mass, more preferably 0.50 or more and 0.80 or less.

[0101] The total content of thermally conductive filler A and thermally conductive filler B, relative to the total mass of the thermally conductive filler, is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, further preferably 95% by mass or more and 100% by mass or less, and particularly preferably 100% by mass. That is to say, the thermally conductive filler contained in the thermally conductive grease composition according to this disclosure is preferably composed of thermally conductive filler A and thermally conductive filler B.

[0102] (Dispersant)

[0103] The thermally conductive grease compositions disclosed herein preferably contain a dispersant.

[0104] Various dispersants can be used as dispersants, with compounds having lipophilic portions and functional groups that adsorb onto thermally conductive fillers being preferred.

[0105] Specifically, carboxylic acid compounds and polyalkylene glycol compounds can be listed as dispersants.

[0106] Carboxylic acid compounds are compounds that have at least one carboxyl group within their molecule. Examples of carboxylic acid dispersants include fatty acids and polycarboxylic acids (i.e., compounds that have two or more carboxyl groups within a molecule).

[0107] The molecular weight of the carboxylic acid compound is preferably 100 or more and 2000 or less, more preferably 150 or more and 1500 or less, and even more preferably 200 or more and 1000 or less.

[0108] When a carboxylic acid compound exhibits a molecular weight distribution, its weight-average molecular weight refers to the weight-average molecular weight of polystyrene obtained by gel permeation chromatography (GPC). The determination conditions and apparatus are described below.

[0109] Measuring device: Shodex GPC-101

[0110] Chromatographic column: Shodex GPC LF-804 (number of columns: 3)

[0111] Detector: RI (Differential Refractive Index Detector)

[0112] Temperature 40℃

[0113] Mobile phase: THF (tetrahydrofuran)

[0114] Flow rate: 1 mL / min

[0115] Sample concentration: 1.0 mass% / vol%

[0116] Sample injection volume: 100 μL

[0117] Fatty acids that are carboxylic acid compounds include both saturated and unsaturated fatty acids. Examples of saturated fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and tetracosanoic acid. Examples of unsaturated fatty acids include decenoic acid, Linderic acid, myristoleic acid, palmitoleic acid, zoomarnic acid, petroselinic acid, octadecenoic acid (trans-6), oleic acid, transoleic acid, isoleic acid, Gadoleic acid, gondocetic acid, cetoleic acid, erucic acid, brassidicacid, squalene, linoleic acid, translinoleic acid, linolenic acid, and arachidonic acid. From the viewpoint of dispersibility and heat resistance, erucic acid and oleic acid are preferred as dispersants, with erucic acid being more preferred.

[0118] Other examples of carboxylic acid compounds include Hypermar KD-4 (weight average molecular weight: 1700), Hypermar KD-9 (weight average molecular weight: 760), Hypermar KD-12 (weight average molecular weight: 490), and Hypermar KD-16 (weight average molecular weight: 370) manufactured by Croda Japan.

[0119] Polyalkylene glycol compounds refer to polymeric compounds with repeating ether bonds, such as those manufactured by ring-opening polymerization of cyclic ethers. Polyalkylene glycol compounds having hydroxyl groups are preferred.

[0120] Polyalkylene glycol compounds containing hydroxyl groups tend to have high adhesion. Therefore, surface modifiers adsorbed on the surface of thermally conductive fillers adhere to the substrate, thus improving the dispersibility of thermoplastic fillers and helping to suppress pump-out phenomena. Pump-out phenomena refer to the displacement of the thermally conductive grease composition due to thermal shock.

[0121] Examples of polyalkylene glycol compounds containing hydroxyl groups include polyalkylene glycols and etherified forms of polyalkylene glycols.

[0122] Examples of polyalkylene glycols include polyethylene glycol, polypropylene glycol, and polybutane glycol.

[0123] As etherified compounds of polyalkylene glycols, examples include compounds formed by the combination of polyalkylene glycols and hydrocarbon groups via ether bonds.

[0124] The number of carbon atoms in the hydrocarbon group contained in the etherification of polyalkylene glycols can be, for example, 12 or more and 65 or less.

[0125] The structure of the hydrocarbon group is not particularly limited; it can be any type, such as straight-chain, branched-chain, or cyclic.

[0126] As etherifications of polyalkylene glycols, examples include polyoxyethylene monooleate ether, polyoxyethylene monostearyl ether, polyoxyethylene monohexadecyl ether, and polyoxyethylene lanolin alcohol. From the viewpoint of dispersibility and good suppression of pumping phenomenon, polyoxyethylene lanolin alcohol is preferred.

[0127] The content of the dispersant relative to the total amount of the thermally conductive grease composition is preferably 0.1% by mass or more and 1.0% by mass or less, more preferably 0.1% by mass or more and 0.7% by mass or less, and even more preferably 0.1% by mass or more and 0.5% by mass or less.

[0128] A thermally conductive grease composition may contain only one dispersant or a combination of two or more dispersants. When a thermally conductive grease composition contains two or more dispersants, the above-mentioned content refers to the total content of the dispersants.

[0129] (Other additives)

[0130] The thermally conductive grease compositions disclosed herein may contain additives other than base oils, thermally conductive fillers, and dispersants. Examples of such additives include anti-pumping agents (e.g., calcium carbonate particles), antioxidants, rust inhibitors, corrosion inhibitors, tackifiers, thickeners, detergents, etc.

[0131] (Physical property values ​​of thermally conductive grease compositions)

[0132] -Thermal conductivity-

[0133] From the viewpoint of high thermal conductivity, the thermal conductivity of the thermally conductive grease composition disclosed herein is preferably 4.0 W / (m·K) or higher, more preferably 4.5 W / (m·K) or higher, even more preferably 5.0 W / (m·K) or higher, even more preferably 6.0 W / (m·K) or higher, and particularly preferably 7.0 W / (m·K) or higher.

[0134] Thermal conductivity was measured in accordance with ISO 22007-2.

[0135] For example, the TPS2500S manufactured by Kyoto Electronics Co., Ltd. can be used to measure thermal conductivity.

[0136] -Shear viscosity-

[0137] Regarding the shear viscosity of the thermally conductive grease composition disclosed herein, from the viewpoint of coatability, the shear viscosity measured at a measurement temperature of 25°C and a shear rate of 10 [1 / s] is preferably 1000 Pa·s or less, more preferably 50 Pa·s or more and 900 Pa·s or less, even more preferably 100 Pa·s or more and 800 Pa·s or less, and particularly preferably 100 Pa·s or more and 700 Pa·s or less.

[0138] From the viewpoint of balancing thermal conductivity and coatability, the thermally conductive grease composition disclosed herein preferably has a thermal conductivity of 6.0 W / (m·K) or higher and a shear viscosity of 100 Pa·s or higher and 1000 Pa·s or lower when measured at a temperature of 25°C and a shear rate of 10 [1 / s]. More preferably, it has a thermal conductivity of 6.0 W / (m·K) or higher and a shear viscosity of 100 Pa·s or higher and 700 Pa·s or lower when measured at a temperature of 25°C and a shear rate of 10 [1 / s]. Even more preferably, it has a thermal conductivity of 7.0 W / (m·K) or higher and a shear viscosity of 100 Pa·s or higher and 600 Pa·s or lower when measured at a temperature of 25°C and a shear rate of 10 [1 / s].

[0139] In this disclosure, shear viscosity is measured using a viscoelasticity measuring apparatus under conditions of a measurement temperature of 25°C and a specified shear rate. For example, an apparatus manufactured by Anton Paar, with the product name MCR102e, can be used as the viscoelasticity measuring apparatus.

[0140] (use)

[0141] The thermally conductive grease composition disclosed herein has high thermal conductivity and excellent spreadability, and can be applied to the gap between various heat-generating and heat-dissipating elements.

[0142] Examples of heat-generating elements include semiconductor components, while examples of heat-dissipating elements include heat sinks.

[0143] (Method for manufacturing thermally conductive grease composition)

[0144] There are no particular limitations on the manufacturing method of the thermally conductive grease composition. It is preferable to add a dispersant to the base oil and thermally conductive filler, and to mix other additives as needed. There are no particular restrictions on the mixing order of the base oil, thermally conductive filler, dispersant and other additives; the components can be mixed sequentially in the base oil.

[0145] Example

[0146] The following examples are described, but the thermally conductive grease compositions involved in this disclosure are not limited to these examples.

[0147] <Examples A1-A5, Comparative Examples 1-6>

[0148] The base oil, thermally conductive filler, dispersant and other additives (antioxidant and antipumping agent) are mixed in the proportions (mass%) shown in Table 1 below.

[0149] It should be noted that blank columns in the composition column of Table 1 indicate that the corresponding ingredients have not been prepared.

[0150] In Examples A1 to A5, thermally conductive grease compositions having the compositions shown in Table 1 were prepared. On the other hand, in Comparative Examples 1 to 6, grease formation was not performed. Therefore, the performance evaluations described below were not conducted for Comparative Examples 1 to 6.

[0151] <Examples B1-B10>

[0152] Mix the base oil, thermally conductive filler, dispersant and other additives (antioxidant and anti-pumping agent) in the proportions (mass%) shown in Table 2 below.

[0153] In Examples B1 to B10, thermally conductive grease compositions having the compositions shown in Table 2 were prepared.

[0154] <Evaluation>

[0155] The following performance evaluations were performed using the thermally conductive grease compositions of the embodiments obtained as described above.

[0156] (thermal conductivity)

[0157] Thermal conductivity was measured in accordance with ISO 22007-2.

[0158] The thermal conductivity measurement device used was a TPS2500S manufactured by Kyoto Electronics Industry Co., Ltd.

[0159] A thermal conductivity of 4.0 W / (m·K) or higher indicates that the thermally conductive grease composition has high thermal conductivity.

[0160] A thermal conductivity of 6.0 W / (m·K) or higher is considered a thermally conductive grease composition with superior thermal conductivity, and a thermal conductivity of 7.0 W / (m·K) or higher is considered a thermally conductive grease composition with even more superior thermal conductivity.

[0161] (Coating performance evaluation)

[0162] Coating properties are evaluated using a viscoelasticity measuring device (product name: MCR102e, manufactured by Anton Paar) based on the shear viscosity measured at a temperature of 25°C and a shear rate of 10 [1 / s].

[0163] A shear viscosity of 1000 Pa·s or less, measured under 10 [1 / s] conditions, indicates that the thermally conductive grease composition has excellent coatability; a shear viscosity of 700 Pa·s or less indicates that the thermally conductive grease composition has particularly excellent coatability; and a shear viscosity of 600 Pa·s or less indicates that the thermally conductive grease composition has even better coatability.

[0164] The results are shown in Table 1.

[0165] [Table 1]

[0166]

[0167] [Table 2]

[0168]

[0169] In Tables 1 and 2, packing A and packing B correspond to thermally conductive packing A and thermally conductive packing B, respectively. Detailed information on each component in Tables 1 and 2 is recorded below.

[0170] (Base oil)

[0171] -Polyalphaolefin-

[0172] • Polyalphaolefin 1: Manufactured by INEOS Oligomeres, DURASYN-168, polyalphaolefin (polymer of 1-decene), kinematic viscosity at 40°C 46.4 mm. 2 / s

[0173] • Polyalphaolefin 2; Product name: INEOS Oligomeres, DURASYN-180R, kinematic viscosity at 40°C: 935 mmHg2 / s

[0174] • Polyalphaolefin 3; Product name: INEOS Oligomeres, DURASYN-170, kinematic viscosity at 40°C: 65.3 mm 2 / s

[0175] -Organic esters-

[0176] • Lauryl methacrylate; Product name: Light Ester L, manufactured by Kyoei Chemical Co., Ltd., lauryl methacrylate (thermally conductive filler).

[0177] Zinc oxide-

[0178] • Zinc oxide 1; Product name: Zinc oxide type 1, manufactured by Sakai Chemical Co., Ltd., zinc oxide particles, volume average particle size: 0.6μm - Aluminum nitride -

[0179] • Aluminum nitride 1; Product name: AN-HF07LG-HTZ, manufactured by MARUWA Corporation, aluminum nitride (AlN) particles, volume average particle size 7.0 μm

[0180] • Aluminum nitride 2; Product name A: N-HF30LG-HTZ, manufactured by MARUWA Corporation, aluminum nitride (AlN) particles, volume average particle size 30μm

[0181] • Aluminum nitride 3; Product name: HF-01Dh, manufactured by Tokuyama Corporation, aluminum nitride (AlN) particles, volume average particle size 1μm. • Aluminum nitride 4; Product name: HF-20h, manufactured by Tokuyama Corporation, aluminum nitride (AlN) particles, volume average particle size 17.8μm, surface treated.

[0182] • Aluminum nitride 5; Product name: HF-20, manufactured by Tokuyama Corporation, aluminum nitride (AlN) particles, volume average particle size 17.8μm, no surface treatment.

[0183] (Dispersant)

[0184] • Dispersant 1; Product Name: Hypermar KD-9, manufactured by Croda Japan Co., Ltd., carboxylic acid compound, polycarboxylic acid, weight average molecular weight: 760

[0185] • Dispersant 2; Product Name: Erucic Acid, manufactured by Nippon Oil Company, a carboxylic acid compound, erucic acid

[0186] • Dispersant 3; Product Name: Polychol 15, manufactured by Croda Japan Co., Ltd., polyoxyethylene lanolin alcohol

[0187] (Other additives)

[0188] • Antioxidant; Product name: Irganox L57, manufactured by BASF Japan, a product of the reaction of N-phenylaniline with 2,4,4-trimethylpentene.

[0189] • Anti-pumping agent; Product name: Baiyanhua 0, manufactured by Baishi Industrial Co., Ltd., calcium carbonate particles surface-treated with rosin-based compounds, with a volume average particle size of 30nm.

[0190] The results above show that the thermally conductive grease composition of this embodiment has high thermal conductivity and excellent coatability.

[0191] The disclosure of Japanese Patent Application No. 2023-039118, filed on March 13, 2023, is incorporated herein by reference in its entirety.

[0192] All documents, patent applications and technical standards described in this specification are incorporated herein by reference to the same extent as the specific and individual descriptions incorporated herein by reference.

Claims

1. A thermally conductive grease composition, wherein, The thermally conductive grease composition contains: Base oils; and Thermally conductive filler containing zinc oxide and aluminum nitride.

2. The thermally conductive grease composition according to claim 1, wherein, The content of aluminum nitride is greater than the content of zinc oxide.

3. The thermally conductive grease composition according to claim 1 or 2, wherein, The thermally conductive filler includes thermally conductive filler A with a volume average particle size of 0.15 μm or more and less than 2 μm, and thermally conductive filler B with a volume average particle size of 2 μm or more and less than 40 μm. The thermally conductive filler A includes zinc oxide, and the thermally conductive filler B includes aluminum nitride.

4. The thermally conductive grease composition according to claim 3, wherein, The ratio of the content of thermally conductive filler A to the content of thermally conductive filler B, based on a mass basis, is 0.20 or more and 0.80 or less.

5. The thermally conductive grease composition according to claim 3, wherein, The ratio of the content of thermally conductive filler A to the content of thermally conductive filler B, based on a mass basis, is 0.50 or more and 0.95 or less.

6. The thermally conductive grease composition according to claim 5, wherein, The ratio of the content of thermally conductive filler A to the content of thermally conductive filler B, based on a mass basis, is 0.50 or more and 0.80 or less.

7. The thermally conductive grease composition according to claim 1 or 2, wherein, The total content of the thermally conductive filler is 90% by mass or more and 98% by mass or less relative to the total amount of the thermally conductive grease composition.

8. The thermally conductive grease composition according to claim 1 or 2, wherein, The thermally conductive grease composition also contains a dispersant.

9. The thermally conductive grease composition according to claim 1 or 2, wherein, The base oil contains polyalphaolefins and organic acid esters.

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