Thermally conductive grease composition

Abstract

To provide a low-viscosity, thermally conductive grease composition. [Solution] A thermally conductive grease composition comprising a base oil (A), thermally conductive particles (B), and an acidic phosphate ester (C), wherein the acidic phosphate ester (C) comprises one or more compounds selected from the group consisting of a compound represented by the following general formula (C-1), a compound represented by the following general formula (C-2), and a compound represented by the following general formula (C-3). TIFF2026081577000010.tif66170

Description

Technical Field

[0001] The present invention relates to a thermal conductive grease composition.

Background Art

[0002] In electronic devices such as computers, automotive parts, and mobile phones, cooling components such as heat sinks are generally used to dissipate heat generated from heat sources such as semiconductor elements and mechanical parts, and thermal conductive grease is used for the purpose of enhancing the heat transfer efficiency to the cooling components.

[0003] For example, Patent Document 1 discloses a thermal conductive grease that transfers heat generated by a heat source to a cooling component, comprising a base oil composed of at least one selected from a copolymer of an unsaturated dicarboxylic acid dialkyl ester and an α-olefin, and a poly-α-olefin, a dispersant composed of a phosphoric acid-based anionic surfactant, and a thermal conductive filler. The thermal conductive grease is disclosed to have a property of lower viscosity than conventional ones when the type and amount of the thermal conductive filler are the same, that is, it has excellent thermal conduction efficiency.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, the heat dissipation characteristics of a thermal conductive grease composition become higher as the viscosity is lower when the type and content of the thermal conductive filler are the same. This is because the lower the viscosity, the thinner it tends to be when pressure-bonded under the same load, and the thermal resistance is reduced. With the recent miniaturization and increased performance of electronic devices, there is a demand for thermal conductive grease compositions with even lower viscosity than conventional thermal conductive grease compositions such as those described in Patent Document 1.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a low-viscosity thermally conductive grease composition. [Means for solving the problem]

[0007] To solve the above problems, the present invention employs the following configuration. [1] A thermally conductive grease composition comprising a base oil (A), thermally conductive particles (B), and an acidic phosphate ester (C), wherein the acidic phosphate ester (C) comprises one or more compounds selected from the group consisting of a compound represented by the following general formula (C-1) (C1), a compound represented by the following general formula (C-2) (C2), and a compound represented by the following general formula (C-3) (C3).

[0008] [ka] [In formula (C-1), Rc 1 and Rc 2 These are, independently, a hydrogen atom and an aliphatic hydrocarbon group having 18 or more carbon atoms. However, Rc 1 and Rc 2 None of them can become hydrogen atoms. In formula (C-2), Rc 3 and Rc 4 Each of these is independently an aliphatic hydrocarbon group with 18 or more carbon atoms. l is an integer from 1 to 5. m is an integer from 1 to 5. In formula (C-3), Rc 5 n is an aliphatic hydrocarbon group with 18 or more carbon atoms. n is an integer from 1 to 5. [2] The thermal conductive grease composition according to [1], wherein the thermal conductive particles (B) include thermal conductive particles (B1) having an average particle diameter D50 of less than 3 μm and thermal conductive particles (B2) having an average particle diameter D50 of 3 μm or more. [Effects of the Invention]

[0009] According to the present invention, a low-viscosity thermal conductive grease composition can be provided.

Mode for Carrying Out the Invention

[0010] (Thermal conductive grease composition) The thermal conductive grease composition of the present embodiment contains a base oil (A), a thermal conductive particle (B), and an acidic phosphate ester (C).

[0011] A thermal conductive grease is a grease used to increase the thermal conductivity by applying it between a heat-generating body and a cooling component to fill the gap.

[0012] <Base oil (A)> The thermal conductive grease composition of the present embodiment contains a base oil (A). The kinematic viscosity of the base oil (A) at 40°C is preferably 10 mm 2 / s or more, more preferably 20 mm 2 / s or more, and even more preferably 40 mm 2 / s or more. The kinematic viscosity of the base oil (A) at 40°C is preferably 700 mm 2 / s or less, more preferably 650 mm 2 / s or less, and even more preferably 450 mm 2 / s or less. <亮>

[0013] When the kinematic viscosity of the base oil (A) of the thermal conductive grease composition of the present embodiment is within the above preferred range, it becomes difficult for the base oil and the thermal conductive particles to separate.

[0014] For example, the kinematic viscosity of the base oil (A) at 40°C is preferably 10 mm 2 / s or more and 700 mm 2 / s or less, more preferably 20 mm 2 / s or more and 650 mm 2 / s or less, and even more preferably 40 mm 2 / s or more and 450 mm 2 / s or less.

[0015] The kinematic viscosity of base oil (A) at 100°C is 2 mm 2 Preferably 5mm or more / s 2 More preferably 7mm 2 / s or higher is even preferable. The kinematic viscosity of base oil (A) at 100°C is 100 mm². 2 Preferably less than / s, 90mm 2 / s or less is more preferable, 70mm 2 / s or less is even more preferable.

[0016] If the kinematic viscosity of the base oil (A) of the thermal conductive grease composition of this embodiment is within the above preferred range at 100°C, the base oil and thermal conductive particles will be less likely to separate.

[0017] For example, the kinematic viscosity of base oil (A) at 100°C is 2 mm². 2 / s or more 100mm 2 Preferably less than / s, 5mm 2 / s or more 90mm 2 / s or less is more preferable, 7mm 2 / s or more 70mm 2 / s or less is even more preferable.

[0018] In this specification, the kinematic viscosity at 40°C and 100°C refers to the kinematic viscosity at 40°C measured in accordance with JIS K2283:2000.

[0019] Examples of the base oil (A) of the thermally conductive grease composition of this embodiment include synthetic oil and mineral oil.

[0020] ≪Synthetic oil≫ Examples of synthetic oils include polyolefins such as poly-α-olefins, ester base oils such as diesters and polyol esters, polyalkylene glycols, alkylbenzenes, alkylnaphthalenes, ether base oils, silicone oils, and fluorine oils. Among the synthetic oils mentioned above, polyolefins are preferred from the viewpoint of availability, cost, viscosity characteristics, and oxidation stability, and poly-α-olefins (PAO) are more preferred. The base oil (A) of the thermally conductive grease composition of this embodiment may be a single synthetic oil or a mixture of multiple synthetic oils.

[0021] Mineral oil As the mineral oil, distillate obtained by atmospheric distillation of crude oil can be used. In addition, lubricating oil fractions obtained by further vacuum distillation of this distillate and then refined through various refining processes can also be used. The refining process can be a combination of various methods, including hydrogenation, solvent extraction, solvent dewaxing, hydrogenation dewaxing, sulfuric acid washing, and clay treatment. By combining these refining processes in an appropriate order, mineral oil can be obtained. Alternatively, a mixture of several refined oils with different properties, obtained by subjecting different crude oils or distillates to different refining process combinations, may be used.

[0022] As for the mineral oil, you can use base oils of API Group I (hereinafter referred to as "API Group I base oil"), Group II (hereinafter referred to as "API Group II base oil"), or Group III (hereinafter referred to as "API Group III base oil"), or a mixture thereof. API Group I base oils are mineral oil-based base oils having a sulfur content of more than 0.03% by mass and / or a saturation content of less than 90% by mass, and a viscosity index of 80 or more and less than 120. API Group II base oils are mineral oil-based base oils with a sulfur content of 0.03% by mass or less, a saturation content of 90% by mass or more, and a viscosity index of 80 or more and less than 120. API Group III base oils are mineral oil-based base oils with a sulfur content of 0.03% by mass or less, a saturation content of 90% by mass or more, and a viscosity index of 120 or higher.

[0023] The base oil (A) of the thermal conductive grease composition of this embodiment may be a single mineral oil or a mixture of multiple mineral oils. In a mixture of multiple mineral oils, the API classifications of those mineral oils may be the same or different.

[0024] The base oil (A) of the thermally conductive grease composition of this embodiment may be either mineral oil or synthetic oil, or a mixture of mineral oil and synthetic oil may be used. The base oil (A) of the thermally conductive grease composition of this embodiment preferably contains a synthetic oil, and more preferably contains a poly-α-olefin.

[0025] The base oil (A) content of the thermal conductive grease composition of this embodiment is preferably 3% by mass or more, more preferably 3.5% by mass or more, and even more preferably 4% by mass or more, based on the total amount of the thermal conductive grease composition. The base oil (A) content of the thermal conductive grease composition of this embodiment is preferably 21% by mass or less, more preferably 19% by mass or less, and even more preferably 17% by mass or less, based on the total amount of the thermal conductive grease composition. For example, the base oil (A) content of the thermal conductive grease composition of this embodiment is preferably 3% to 21% by mass, more preferably 3.5% to 19% by mass, and even more preferably 4% to 17% by mass, based on the total amount of the thermal conductive grease composition.

[0026] <Thermal conductive particles (B)> The thermally conductive grease composition of this embodiment contains thermally conductive particles (B). Examples of thermally conductive particles (B) include metals, metal oxides, metal nitrides, metal hydroxides, metal carbides, graphite, and carbon fibers.

[0027] Examples of metals include aluminum, silver, copper, and nickel. Examples of metal oxides include aluminum oxide, magnesium oxide, and zinc oxide. Examples of metallic nitrides include boron nitride and aluminum nitride. Examples of metal hydroxides include aluminum hydroxide. Examples of metal carbides include silicon carbide. Examples of carbon fibers include pitch-based carbon fibers, PAN-based carbon fibers, carbonized resin fibers, and graphitized resin fibers.

[0028] Among the above, metal nitrides are preferred as the thermally conductive particles (B), and aluminum nitride is more preferred.

[0029] The average particle diameter D50 of the thermally conductive particles (B) is preferably 0.1 μm or larger, more preferably 0.3 μm or larger, and even more preferably 0.5 μm or larger. The average particle diameter D50 of the thermally conductive particles (B) is preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. For example, the average particle diameter D50 of the thermally conductive particles (B) is preferably 0.1 μm or more and 150 μm or less, more preferably 0.3 μm or more and 100 μm or less, and even more preferably 0.5 μm or more and 50 μm or less.

[0030] In this specification, the average particle diameter D50 is the particle diameter at which the cumulative volume proportion from the smallest particle side becomes 50% in the volume-based cumulative particle diameter distribution curve obtained by laser diffraction / scattering particle diameter distribution measurement. The average particle size D50 of thermally conductive particles (B) can be measured using a commercially available laser diffraction / scattering particle size distribution analyzer.

[0031] The thermal conductive grease composition of this embodiment preferably contains two or more thermal conductive particles (B) with different average particle diameters D50, and preferably contains aluminum nitride (B1) with an average particle diameter D50 of less than 30 μm and aluminum nitride (B2) with an average particle diameter D50 of 30 μm or more.

[0032] Aluminum nitride (B1) has an average particle size D50 of less than 30 μm, preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The average particle size D50 of aluminum nitride (B1) is preferably 0.1 μm or larger, more preferably 0.3 μm or larger, and even more preferably 0.5 μm or larger. For example, the average particle size D50 of aluminum nitride (B1) is preferably 0.1 μm or more and less than 30 μm, more preferably 0.1 μm or more and 20 μm or less, even more preferably 0.3 μm or more and 15 μm or less, and particularly preferably 0.5 μm or more and 10 μm or less.

[0033] The aluminum nitride (B1) preferably contains aluminum nitride (B11) having an average particle size D50 of 3 μm or less, and aluminum nitride (B12) having an average particle size D50 greater than 3 μm and less than 30 μm.

[0034] Aluminum nitride (B11) has an average particle size D50 of 3 μm or less, preferably 2.5 μm or less, more preferably 2 μm or less, and even more preferably 1.5 μm or less. Aluminum nitride (B11) preferably has an average particle size D50 of 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.3 μm or more, and particularly preferably 0.5 μm or more. For example, aluminum nitride (B11) preferably has an average particle size D50 of 0.1 μm or more and 3 μm or less, more preferably 0.2 μm or more and 2.5 μm or less, even more preferably 0.3 μm or more and 2 μm or less, and particularly preferably 0.5 μm or more and 1.5 μm or less.

[0035] Aluminum nitride (B12) has an average particle size D50 of more than 3 μm, preferably 3.5 μm or larger, more preferably 4 μm or larger, and even more preferably 4.5 μm or larger. Aluminum nitride (B12) has an average particle size D50 of less than 30 μm, preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. For example, aluminum nitride (B12) preferably has an average particle size D50 of 3.5 μm or more and 20 μm or less, more preferably 4 μm or more and 15 μm or less, and even more preferably 4.5 μm or more and 10 μm or less.

[0036] Furthermore, in one embodiment, the material may contain thermally conductive particles (B01) with an average particle diameter D50 of less than 3 μm and thermally conductive particles (B02) with an average particle diameter D50 of 3 μm or more.

[0037] The average particle diameter D50 of the thermally conductive particles (B01) is less than 3 μm, may be 2 μm or less, 1.5 μm or less, or 1 μm or less. The average particle diameter D50 of the thermally conductive particles (B01) may be 0.1 μm or larger, 0.3 μm or larger, or 0.5 μm or larger. For example, the average particle diameter D50 of the thermally conductive particles (B01) may be 0.1 μm or more and less than 3 μm, 0.1 μm or more and 2 μm or less, 0.3 μm or more and 1.5 μm or less, or 0.5 μm or more and 1 μm or less.

[0038] The average particle diameter D50 of the thermally conductive particles (B02) is 3 μm or larger, may be 5 μm or larger, 7 μm or larger, or 8 μm or larger. The average particle diameter D50 of the thermally conductive particles (B02) may be 30 μm or less, 20 μm or less, or 10 μm or less. For example, the average particle diameter D50 of the thermally conductive particles (B2) may be 3 μm or more and 30 μm or less, 5 μm or more and 20 μm or less, 7 μm or more and 10 μm or less, or 8 μm or more and 10 μm or less.

[0039] In the thermal conductive grease composition of this embodiment, the mass ratio ((B2) / (B1)) of the content of aluminum nitride (B1) to the content of aluminum nitride (B2) is preferably 2 to 8, more preferably 3 to 7, and even more preferably 4 to 6.

[0040] In the thermal conductive grease composition of this embodiment, the mass ratio ((B02) / (B01)) of the content of aluminum nitride (B01) to the content of aluminum nitride (B02) is preferably 2 to 8, more preferably 3 to 7, and even more preferably 4 to 6.

[0041] The thermally conductive particles (B) may be used individually or in a mixture of multiple types. The thermal conductive particle (B) content of the thermal conductive grease composition of this embodiment is preferably 79% by mass or more, more preferably 81% by mass or more, and even more preferably 83% by mass or more, based on the total amount of the thermal conductive grease composition. The content of thermal conductive particles (B) in the thermal conductive grease composition of this embodiment is preferably 97% by mass or less, more preferably 96.5% by mass or less, and even more preferably 96% by mass or less, based on the total amount of the thermal conductive grease composition. For example, the content of thermal conductive particles (B) in the thermal conductive grease composition of this embodiment is preferably 79% to 97% by mass, more preferably 81% to 96.5% by mass, and even more preferably 83% to 96% by mass, based on the total amount of the thermal conductive grease composition.

[0042] <Acidic phosphate ester (C)> Acidic phosphate ester (C) includes one or more compounds selected from the group consisting of compounds represented by the following general formula (C-1) (C1), compounds represented by the following general formula (C-2) (C2), and compounds represented by the following general formula (C-3) (C3).

[0043] ≪Compound (C1)≫ Compound (C1) is a compound represented by the following general formula (C-1).

[0044] [ka] [In formula (C-1), Rc 1 and Rc 2 These are, independently, a hydrogen atom and an aliphatic hydrocarbon group having 18 or more carbon atoms. However, Rc 1 and Rc 2 None of these can become hydrogen atoms.

[0045] In the above formula (C-1), Rc 1 and Rc 2 The aliphatic hydrocarbon group having 18 or more carbon atoms is preferably an aliphatic hydrocarbon group having 18 to 40 carbon atoms, more preferably an aliphatic hydrocarbon group having 18 to 30 carbon atoms, and even more preferably an aliphatic hydrocarbon group having 18 to 25 carbon atoms.

[0046] In the above general formula (C-1), Rc 1 and Rc 2 The aliphatic hydrocarbon group having 18 or more carbon atoms in this compound may be linear or branched, and may be saturated or unsaturated aliphatic hydrocarbon.

[0047] In the above general formula (C-1), Rc 1 and Rc 2 Examples of aliphatic hydrocarbon groups in this context include alkyl groups, alkenyl groups, alkadienyl groups, and alkatrineyl groups.

[0048] Examples of alkyl groups with 18 or more carbon atoms include octadecyl, nonadecyl, icosyl, and henicosyl groups. Examples of alkenyl groups with 18 or more carbon atoms include the octadecenyl group, nonadecenyl group, icocenyl group, and henicocenyl group. The position of the double bond is arbitrary; for example, the oleyl group (9-octadecenyl group) is one such example.

[0049] In the above general formula (C-1), Rc 1 and Rc 2The aliphatic hydrocarbon group in is preferably an alkenyl group, an alkadienyl group, or an alkatrineyl group, and more preferably an alkenyl group.

[0050] In the above general formula (C-1), Rc 1 and Rc 2 Among the above, each is preferably an alkenyl group having 18 to 40 carbon atoms, more preferably an alkenyl group having 18 to 30 carbon atoms, even more preferably an alkenyl group having 18 to 25 carbon atoms, and particularly preferably an oleyl group.

[0051] Compound (C1) may be used alone or in combination with other compounds.

[0052] ≪Compound (C2)≫ Compound (C2) is a compound represented by the following general formula (C-2).

[0053] [ka] [In formula (C-2), Rc 3 and Rc 4 Each of these is independently an aliphatic hydrocarbon group with 18 or more carbon atoms. l is an integer from 1 to 5. m is an integer from 1 to 5.

[0054] In the above general formula (C-2), Rc 3 and Rc 4 In this context, an aliphatic hydrocarbon group with 18 or more carbon atoms is Rc 1 and Rc 2 Examples include aliphatic hydrocarbon groups with 18 or more carbon atoms, similar to those found in [the text].

[0055] In the above general formula (C-2), l is an integer between 1 and 5, preferably between 2 and 4, and more preferably between 2 and 3.

[0056] In the above general formula (C-2), m is an integer between 1 and 5, preferably between 2 and 4, and more preferably between 2 and 3.

[0057] Compound (C2) may be used alone or in combination with other compounds.

[0058] ≪Compound (C3)≫ Compound (C3) is a compound represented by the following general formula (C-3).

[0059] [ka] [In formula (C-3), Rc 5 n is an aliphatic hydrocarbon group with 18 or more carbon atoms. n is an integer from 1 to 5.

[0060] In the above general formula (C-3), Rc 5 In this context, an aliphatic hydrocarbon group with 18 or more carbon atoms is Rc 1 and Rc 2 Examples include aliphatic hydrocarbon groups with 18 or more carbon atoms, similar to those found in [the text].

[0061] In the above general formula (C-3), n is an integer between 1 and 5, preferably between 2 and 4, and more preferably between 2 and 3.

[0062] Compound (C3) may be used individually or in combination with other compounds.

[0063] The content of acidic phosphate ester (C) in the thermal conductive grease composition of this embodiment is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, and even more preferably 0.2% by mass or more, based on the total amount of the thermal conductive grease composition. The content of acidic phosphate ester (C) in the thermal conductive grease composition of this embodiment is preferably 10% by mass or less, more preferably 9% by mass or less, and even more preferably 8% by mass or less, based on the total amount of the thermal conductive grease composition. For example, the content of acidic phosphate ester (C) in the thermal conductive grease composition of this embodiment is preferably 0.1% to 10% by mass, more preferably 0.15% to 9% by mass, and even more preferably 0.2% to 8% by mass, based on the total amount of the thermal conductive grease composition.

[0064] <Optional ingredients> The thermally conductive grease composition of this embodiment may contain optional components other than the base oil (A), thermally conductive particles (B), and acidic phosphate ester (C) described above. Examples of such optional components include phosphite esters or their salts, thickeners, anti-wear agents, antioxidants, rust inhibitors, corrosion inhibitors, viscosity enhancers, diffusion inhibitors, and flame retardants.

[0065] <Phosphite esters or their salts> The thermally conductive grease composition of this embodiment may contain a phosphite ester or a salt thereof. Examples of phosphite esters include monooleyl hydrogen phosphite, dioleyl hydrogen phosphite, dibutyl hydrogen phosphite, di(nonylphenyl) hydrogen phosphite, dilauryl phosphite, ditetracosyl hydrogen phosphite, triphenyl phosphite, tri(p-cresyl) phosphite, tris(nonylphenyl) phosphite, triisooctyl phosphite, tristearin phosphite, trioleyl phosphite, di-2-ethylhexylhydrophene phosphite, and dilauryl hydrogen phosphite.

[0066] Examples of phosphite ester salts include alkali metal salts of phosphite esters and amine salts of phosphite esters.

[0067] Examples of alkali metals used as raw materials for alkali metal salts of phosphite esters include sodium and potassium.

[0068] Examples of amines used as raw materials for amine salts of phosphite esters include monoamines, polyamines, and alkanolamines.

[0069] Examples of monoamines include primary amines, secondary amines, and tertiary amines. Examples of primary amines include ethylamine, n-propylamine, butylamine, 1-ethylbutylamine, 1,3-diaminopropane, and cyclohexylamine. Examples of secondary amines include diethylamine, di-n-propylamine, di-n-butylamine, 4,4'-diaminodiphenylamine, diethylenetriamine, tetraethylenepentamine, and N-(2-aminoethyl)ethanolamine. Examples of tertiary amines include dimethylethylamine, diethylmethylamine, triethylamine, and tributylamine.

[0070] Examples of alkanolamines include monoethanolamine, diethanolamine, triethanolamine, diethylethanolamine, and propanolamine.

[0071] Examples of polyamines include alkylene polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, propylenediamine, dipropylenetriamine, tripylenetetramine, tetrapropylenepentamine, pentapropylenehexamine, butylenediamine, dibutylentriamine, tributylenetetramine, tetrabutylenepentamine, and pentabutylenehexamine; N-alkylethylenediamines such as N-methylethylenediamine, N-ethylethylenediamine, and N-propylethylenediamine; N-alkenylethylenediamines such as N-vinylethylenediamine, N-propenylethylenediamine, and N-butenylethylenediamine; and N-alkyl or N-alkenylalkylene polyamines such as N-alkyldiethylenetriamine, N-alkenyldiethylenetriamine, and N-alkyltriethylenetetramine. The above polyamines also include polyamines derived from fats and oils (such as beef tallow polyamines).

[0072] The phosphite ester or its salt preferably includes a compound represented by the following general formula (X-1) or its salt.

[0073] [ka] [In the formula, Rc 1 and Rc 2 Each of these is independently a hydrogen atom or an aliphatic hydrocarbon group having 16 or more carbon atoms. However, Rc 1 and Rc 2 None of these can become hydrogen atoms.

[0074] In the above general formula (X-1), Rc 1 and Rc 2 The aliphatic hydrocarbon group having 16 or more carbon atoms is preferably an aliphatic hydrocarbon group having 16 to 40 carbon atoms, more preferably an aliphatic hydrocarbon group having 16 to 30 carbon atoms, and even more preferably an aliphatic hydrocarbon group having 16 to 25 carbon atoms.

[0075] In the above general formula (X-1), Rc 1 and Rc 2 The aliphatic hydrocarbon group having 16 or more carbon atoms in this compound may be linear or branched, and may be saturated or unsaturated aliphatic hydrocarbon.

[0076] In the above general formula (X-1), Rc 1 and Rc 2 Examples of aliphatic hydrocarbon groups in this context include alkyl groups, alkenyl groups, alkadienyl groups, and alkatrineyl groups.

[0077] Examples of alkyl groups with 16 or more carbon atoms include palmityl group (hexadecyl group), stearyl group (octadecyl group), octadecyl group, nonadecyl group, icosyl group, and henicosyl group. Examples of alkenyl groups with 16 or more carbon atoms include hexadecenyl, octadecenyl, nonadecenyl, icocenyl, and henicocenyl groups. The position of the double bond is arbitrary; for example, an oleyl group (9-octadecenyl group) is one such example.

[0078] In the above general formula (X-1), Rc 1 and Rc 2 Among the above, each is preferably an alkenyl group having 16 to 40 carbon atoms, more preferably an alkenyl group having 16 to 30 carbon atoms, even more preferably an alkenyl group having 16 to 25 carbon atoms, and particularly preferably an oleyl group.

[0079] Examples of salts of the compound represented by the general formula (X-1) include alkali metal salts of the compound represented by the general formula (X-1) and amine salts of the compound represented by the general formula (X-1). Specifically, the Rc of a compound represented by the general formula (X-1) 1 and Rc 2 The Rc of compounds whose Rc is an alkali metal or represented by the general formula (X-1) 1 and Rc 2This compound is a group obtained by removing one hydrogen atom from the amine mentioned above.

[0080] If the thermally conductive grease composition contains a phosphite ester or a salt thereof, its content is, for example, 0.1 to 20% by mass of the total amount of the thermally conductive grease composition. The phosphite ester or a salt thereof may be used alone, or multiple phosphite esters or salts thereof may be used in mixture form.

[0081] Examples of thickeners include metal soap-based thickeners, urea-based thickeners, bentonite, and inorganic thickeners such as silica gel. When a thermal conductive grease composition contains a thickener, its content is, for example, 0.1 to 20% by mass of the total amount of the thermal conductive grease composition. The thickener may be used alone or in a mixture of multiple thickeners.

[0082] Examples of anti-wear agents include organozinc compounds such as zinc dialkyldithiophosphate and zinc dialkyldithiocarbamate; sulfur-containing compounds such as molybdenum dialkyldithiocarbamate, dihydrocarbyl polysulfide, sulfur esters, thiazole compounds, and thiadiazole compounds; and phosphorus-based extreme pressure agents such as phosphate esters, amine salts of acidic phosphate esters, and phosphite esters. When a thermal conductive grease composition contains an anti-wear agent, its content is preferably, for example, 0.1 to 10% by mass, and more preferably 0.5 to 1.5% by mass, relative to the total amount of the thermal conductive grease composition. The anti-wear agent may be used alone or in combination of multiple anti-wear agents.

[0083] Examples of antioxidants include phenolic compounds such as 2,6-di-t-butylphenol and 2,6-di-t-butyl-p-cresol; and amine compounds such as diphenylamine, dialkyldiphenylamine, phenyl-α-naphthylamine, and p-alkylphenyl-α-naphthylamine. When the thermal conductive grease composition contains an antioxidant, its content is, for example, 0.5 to 10% by mass of the total amount of the thermal conductive grease composition. The antioxidant may be used alone or in a mixture of multiple antioxidants.

[0084] Examples of rust inhibitors include amines, neutral or overbasic petroleum-based or synthetic oil-based metal sulfonates, carboxylate metal salts, esters, phosphoric acid, and phosphates. When a thermal conductive grease composition contains a rust inhibitor, its content is, for example, 0.005 to 5% by mass of the total amount of the thermal conductive grease composition. The rust inhibitor may be used alone or in a mixture of multiple rust inhibitors.

[0085] As corrosion inhibitors, known corrosion inhibitors such as benzotriazole compounds, tolyltriazole compounds, thiadiazole compounds, and imidazole compounds can be used. When the thermal conductive grease composition contains a corrosion inhibitor, its content is, for example, 0.01 to 10% by mass of the total amount of the thermal conductive grease composition. The corrosion inhibitor may be used alone or in a mixture of multiple corrosion inhibitors.

[0086] The thermally conductive grease composition of this embodiment contains a base oil (A), thermally conductive particles (B), and an acidic phosphate ester (C), wherein the acidic phosphate ester (C) includes one or more compounds selected from the group consisting of a compound represented by general formula (C-1) (C1), a compound represented by general formula (C-2) (C2), and a compound represented by general formula (C-3) (C3). Compounds (C1), (C2), and (C3) all have an aliphatic hydrocarbon group with 18 or more carbon atoms. Therefore, a thermally conductive grease composition containing the above compounds is The phosphate portion of the acidic phosphate ester (C) exhibits excellent adsorption to thermally conductive particles (B), and the aliphatic hydrocarbon group (hydrophobic portion) with 18 or more carbon atoms exhibits excellent affinity to the base oil (A), resulting in low viscosity. Therefore, the thermally conductive grease of this embodiment has low viscosity and tends to thin out when pressed under the same load, thus reducing thermal resistance. [Examples]

[0087] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0088] <Preparation of thermally conductive grease composition> The thermal conductive grease composition of Example 1 and the thermal conductive grease compositions of Comparative Examples 1 to 4 were prepared in the blending ratios shown in Tables 1 and 2. The values ​​in Tables 1 and 2 represent the blending ratio (mass%) relative to the total amount of the thermal conductive grease composition.

[0089] (1) Base oil (A) (A)-1: Poly-α-olefin (kinematic viscosity at 40°C = 412 mm) 2 / s, density 0.846g / cm 3 )

[0090] (2) Thermally conductive particles (B) • (B)-1: Aluminum nitride (spherical, average particle size D50 0.9 μm) (B)-2: Aluminum nitride (polyhedral, average particle size D50 8μm) (B)-3: Aluminum nitride (spherical, average particle size D50 30μm)

[0091] (3) Acid phosphate ester (C) • (C)-1: Diethylene glycol monooleyl ether acid phosphate (oleyl EO2 acid phosphate, manufactured by Johoku Chemical Co., Ltd.) • (c)-1: Diethylene glycol monolauryl ether acid phosphate (lauryl EO2 acid phosphate, manufactured by Johoku Chemical Co., Ltd.)

[0092] (4) Additives ·X-1: Half-ester alkenyl succinate ·X-2: Sodium β-laurylaminopropionate ·X-3: Succinimide

[0093] [ka]

[0094] [Measurement of rotational viscosity] The rotational viscosity of each example of the thermally conductive grease composition was measured under the following measurement conditions. The results are shown in Tables 1 and 2. <Measurement conditions> Equipment used: HAAKE MARS3 Measurement temperature: 25℃ Sensor used: Parallel plate type, 25mm Sample thickness: 1 mm Shear rate: 10s-1 In the table, "ND" indicates that the product did not become greasey-like and therefore viscosity could not be measured.

[0095] [Table 1]

[0096] [Table 2]

[0097] As shown in Tables 1 and 2, the thermal conductive grease composition of the example was found to have lower viscosity compared to the thermal conductive grease composition of the comparative example. Therefore, it can be seen that the thermal conductive grease composition of the example is easier to thin when pressed under the same load, reducing thermal resistance and thus exhibiting superior heat dissipation characteristics.

Claims

1. It contains a base oil (A), thermally conductive particles (B), and an acidic phosphate ester (C), The aforementioned acidic phosphate ester (C) is a thermally conductive grease composition comprising one or more compounds selected from the group consisting of a compound represented by the following general formula (C-1) (C1), a compound represented by the following general formula (C-2) (C2), and a compound represented by the following general formula (C-3) (C3). 【Chemistry 1】 [In formula (C-1), Rc １ and Rc ２ These are, independently, a hydrogen atom and an aliphatic hydrocarbon group having 18 or more carbon atoms. However, Rc １ and Rc ２ None of them can become hydrogen atoms. In formula (C-2), Rc ３ and Rc ４ Each of these is independently an aliphatic hydrocarbon group with 18 or more carbon atoms. l is an integer from 1 to 5. m is an integer from 1 to 5. In formula (C-3), Rc ５ [where n is an aliphatic hydrocarbon group with 18 or more carbon atoms, and n is an integer from 1 to 5]

2. The thermal conductive grease composition according to claim 1, wherein the thermal conductive particles (B) include thermal conductive particles (B1) having an average particle diameter D50 of less than 3 μm and thermal conductive particles (B2) having an average particle diameter D50 of 3 μm or more.

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