JP7724081B2 - Thermally conductive composition - Google Patents

Description

The present invention relates to a thermally conductive composition that can be used in electronic devices, etc.

There are components that generate heat during use, such as CPUs in electronic devices, Peltier elements, power semiconductors for power supply control such as LEDs, high-output inverters in hybrid and electric vehicles, etc. In recent years, as these devices have become smaller and more powerful, the heat density and heat generation amount have increased, and moreover, they are often installed in close proximity to other heat-generating components, so thermally conductive compositions are required to have better heat dissipation properties.
In order to protect these heat-generating components from heat and ensure their normal function, one method is to dissipate the generated heat by conducting it to a heat-dissipating component such as a heat spreader or a heat sink. A thermally conductive composition is applied between the heat-generating component and the heat-dissipating component so as to bring them into close contact with each other, and is used to efficiently conduct heat from the heat-generating component to the heat-dissipating component.
It is also desirable for the thermally conductive composition to have good flowability, which allows the thermally conductive composition to be easily applied to the surface of the component and to conform to microscopically rough surfaces.
The thermally conductive composition is a semi-solid composition consisting of (1) inorganic fillers such as metal oxides such as zinc oxide and aluminum oxide, metal nitrides such as boron nitride, silicon nitride, and aluminum nitride, and metal powders such as aluminum, silver, and copper, (2) base oils such as hydrocarbon synthetic oils, ester oils, and ether oils, and (3) additives classified into coupling agents, dispersants, surfactants, stabilizers, and the like.
As thermally conductive compositions, it has been discovered that a composition containing a specific ratio of base oil and an inorganic filler whose surface has been treated with a coupling agent has excellent thermal conductivity, consistency, oil separation resistance, and heat resistance (Patent Document 1), that by blending a specific amount of a specific perfluoroalkyl group-containing compound to improve the dispersibility of the inorganic filler, high consistency can be obtained even when the inorganic filler is highly loaded, and that the ability to prevent base oil diffusion in the thermally conductive composition can be significantly improved while increasing heat resistance and moisture resistance (Patent Document 2), and that by appropriately blending three types of inorganic powder fillers with different average particle sizes, it has been discovered that both thermal conductivity and malleability can be achieved (Patent Document 3).

Patent No. 5577553 Patent No. 6263042 Japanese Patent Application Laid-Open No. 2020-2212

Insulating heat-dissipating compounds suitable for use in electronic components often contain aluminum oxide as an inorganic filler for reasons of cost and stability, and many commercially available compounds have thermal conductivities in the range of 1 to 5 W/mK. Generally, the higher the thermal conductivity of a compound, the greater the amount of inorganic filler required. However, using a large amount of inorganic filler poses the problem of insufficient fluidity. A decrease in fluidity makes the heat-dissipating compound less likely to deform, potentially making it unable to conform to the microscopically rough surfaces of electronic components.
Therefore, an object of the present invention is to provide a thermally conductive composition that has higher thermal conductivity and excellent fluidity.

The present inventors have found that the inclusion of a polyether carboxylic acid compound results in excellent fluidity without impairing high thermal conductivity, and have thus completed the present invention. That is, the present invention provides the following thermally conductive composition.
1. A thermally conductive composition comprising (A) an inorganic filler, (B) a base oil, and (C) a polyether carboxylic acid compound.
2. The thermally conductive composition according to 1 above, wherein the polyether carboxylic acid compound (C) is represented by the following formula (I) or (II):
R ₁ O(R ₂ O) _n -R ₃ -COOH (I)
R ₄ O(R ₅ O) _m -C(=O)-R ₆ -COOH (II)
(In the formula, _R1 and _R4 each independently represent a linear or branched alkyl group having 1 to 36 carbon atoms, a linear or branched alkenyl group having 2 to 36 carbon atoms, an aliphatic hydrocarbon group having a cyclic structure having 3 to 36 carbon atoms, or an aryl group having 6 to 36 carbon atoms; _R2O and _R5O each independently represent oxyethylene or oxypropylene; _R3 and _R6 each independently represent a linear or branched alkyl group having 1 to 36 carbon atoms, a linear or branched alkenyl group having 2 to 36 carbon atoms, an aliphatic hydrocarbon group having a cyclic structure having 3 to 36 carbon atoms, or an aryl group having 6 to 36 carbon atoms; and n and m each independently represent the degree of polymerization and are a positive number of 1 or greater.)
3. The thermally conductive composition according to 1 above, wherein the polyether carboxylic acid compound (C) is at least one compound selected from the group consisting of poly(oxyethylene) alkyl ether carboxylic acids, poly(oxyethylene) alkenyl ether carboxylic acids, poly(oxyethylene) aryl ether carboxylic acids, poly(oxypropylene) alkyl ether carboxylic acids, poly(oxypropylene) alkenyl ether carboxylic acids, and poly(oxypropylene) aryl ether carboxylic acids.
4. (A) The inorganic filler is composed of a first inorganic filler in a proportion of 10% by mass or more and 40% by mass or less, a second inorganic filler in a proportion of 10% by mass or more and 40% by mass or less, and a third inorganic filler in a proportion of 40% by mass or more and 80% by mass or less, relative to 100% by mass of the inorganic filler;
The first inorganic filler has an average particle size of 0.1 to 2 μm,
the average particle size of the second inorganic filler is 2 times or more and 500 times or less than the average particle size of the first inorganic filler;
The average particle size of the third inorganic filler is 4 times or more and 5000 times or less than the average particle size of the first inorganic filler.
4. The thermally conductive composition according to any one of 1 to 3 above.
5. The thermally conductive composition according to any one of 1 to 4 above, which does not contain silicone oil.

The composition of the present invention exhibits excellent fluidity while having higher thermal conductivity.

(A) Inorganic Filler The inorganic filler used in the present invention is not particularly limited as long as it has a higher thermal conductivity than the base oil, but powders of metal oxides, metal nitrides, inorganic nitrides, metals, silicon compounds, carbon materials, etc. are preferably used. They can be used alone or in combination of two or more. Powders of metal oxides or metal nitrides are preferred. Powders of at least one type selected from the group consisting of aluminum nitride, zinc oxide, and aluminum oxide are particularly preferred. When two or three of these are used in combination, it is preferable to include aluminum nitride. Aluminum nitride is preferred because it has high insulation properties and high thermal conductivity.

It is preferable to use three types of inorganic fillers with different particle sizes (hereinafter, sometimes referred to as fine, medium, and coarse particles in order of decreasing particle size). The fine, medium, and coarse particles may be made of the same type of inorganic filler (for example, aluminum nitride may be used for the fine, medium, and coarse particles), or different types of inorganic fillers may be used (for example, aluminum nitride may be used for the fine and medium particles, and zinc oxide may be used for the coarse particles).
the inorganic filler is composed of a first inorganic filler (fine particles) in a proportion of 10% by mass or more and 40% by mass or less, a second inorganic filler (medium particles) in a proportion of 10% by mass or more and 40% by mass or less, and a third inorganic filler (coarse particles) in a proportion of 40% by mass or more and 80% by mass or less, relative to 100% by mass of the inorganic filler;
The first inorganic filler has an average particle size of 0.1 μm to 2 μm,
the average particle size of the second inorganic filler is 2 times or more and 500 times or less than the average particle size of the first inorganic filler;
When the average particle diameter of the third inorganic filler is 4 times or more and 5,000 times or less the average particle diameter of the first inorganic filler, the balance of fine particles, medium particles, and coarse particles is suitable for filling, and the filling rate of the inorganic filler in the thermally conductive composition can be increased compared to when only one type of fine particles, medium particles, or coarse particles is used, resulting in a higher thermal conductivity, which is preferable.
The term "average particle size" used in this specification means the particle size at 50% of the integrated value in the particle size distribution determined by a laser diffraction/scattering method (median diameter, D50).

In this embodiment, in particular
The first inorganic filler has an average particle size of 0.1 μm to 1.5 μm,
the average particle size of the second inorganic filler is 3 times or more and 150 times or less than the average particle size of the first inorganic filler;
When the average particle diameter of the third inorganic filler is 9 times or more and 1,500 times or less than the average particle diameter of the first inorganic filler, a filling structure can be formed in which fine particles are placed in the gaps between medium particles, and medium particles and fine particles are placed in the gaps between coarse particles, thereby further increasing the filling rate of the inorganic filler in the thermally conductive composition, which is preferable.
In this embodiment, the first to third inorganic fillers are more preferably aluminum nitride and/or zinc oxide.
In the above embodiment, more particularly
The first inorganic filler has an average particle size of 1.0 μm to 1.5 μm,
the average particle size of the second inorganic filler is 3 times or more and 15 times or less than the average particle size of the first inorganic filler;
It is preferable that the average particle diameter of the third inorganic filler is 30 times or more and 70 times or less than the average particle diameter of the first inorganic filler, because the balance of the particle diameter ratio of each particle is suitable for filling, and the filling rate of the inorganic filler in the thermally conductive composition can be further increased.
In these embodiments, it is more preferable that the first to third inorganic fillers are aluminum nitride.

In yet another embodiment, in particular
The first inorganic filler has an average particle size of 0.1 μm to 2 μm,
The average particle size of the second inorganic filler is more than 2 μm to 50 μm,
The average particle size of the third inorganic filler is preferably more than 50 μm and up to 500 μm from the viewpoint of improving the filling rate of the inorganic filler in the thermally conductive composition.
In the above embodiment, more particularly
The average particle size of the first inorganic filler is 1.0 μm to 1.5 μm,
The average particle size of the second inorganic filler is 5 μm to 15 μm,
A more suitable combination is one in which the average particle size of the third inorganic filler is greater than 50 μm and falls within the range of 150 μm.
In the above aspect, inter alia:
The average particle size of the first inorganic filler is 1.0 μm to 1.5 μm,
The average particle size of the second inorganic filler is 5 μm to 10 μm,
A more suitable combination is one in which the average particle size of the third inorganic filler is greater than 50 μm and falls within the range of 70 μm.
In these embodiments, it is more preferable that the first to third inorganic fillers are aluminum nitride.

The content of the inorganic filler is preferably 80 to 97 parts by mass, more preferably 90 to 97 parts by mass, and particularly preferably 94 to 97 parts by mass, when the total amount of components (A), (B), and (C) of the present invention is taken as 100 parts by mass. If the content is 98 parts by mass or more, sufficient fluidity may not be maintained or the thermally conductive composition may not be able to be prepared. If the content is 80 parts by mass or less, sufficient thermal conductivity may not be achieved or the thermally conductive composition may not become semi-solid.

(B) Base oil As the base oil used in the composition of the present invention, various base oils can be used, for example, hydrocarbon oils such as mineral oil, synthetic hydrocarbon oil, ester oil, ether oil, silicone oil and fluorine oil, etc. are listed, and hydrocarbon oil, ester oil and ether oil are preferred.Base oil may be used alone or in combination of two or more.However, since the volatile components in silicone oil may cause malfunction in electronic equipment, when the composition of the present invention is used in electronic equipment, it is not preferred to use silicone oil as base oil.
Examples of mineral oils include those obtained by refining mineral oil-based lubricating oil fractions through an appropriate combination of refining techniques such as solvent extraction, solvent dewaxing, hydrorefining, hydrocracking, and wax isomerization, and include 150 neutral oil, 500 neutral oil, bright stock, and high viscosity index base oils. Highly hydrorefined high viscosity index base oils are preferred as the mineral oil.
Examples of synthetic hydrocarbon oils include α-olefins produced from raw materials such as ethylene, propylene, butene, and derivatives thereof, polymerized alone or in combination of two or more. Preferred examples of α-olefins include those having 6 to 14 carbon atoms. Specific examples include polyα-olefins (PAO) obtained by polymerizing linear α-olefins, polyisobutylene, which is a polymer of isobutylene, and copolymers of ethylene or propylene with α-olefins. Furthermore, alkylbenzenes, alkylnaphthalenes, and the like can also be used.

Ester oils include diesters and polyol esters.
Examples of diesters include esters of dibasic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. The dibasic acid is preferably an aliphatic dibasic acid having 4 to 36 carbon atoms. The alcohol residue constituting the ester moiety is preferably a monohydric alcohol residue having 4 to 26 carbon atoms.
The polyol ester is an ester of neopentyl polyol having no hydrogen atom on the β-position carbon, and specific examples thereof include carboxylic acid esters of neopentyl glycol, trimethylolpropane, pentaerythritol, etc. The carboxylic acid residue constituting the ester moiety is preferably a monocarboxylic acid residue having 4 to 26 carbon atoms.
In addition to the above, esters of aliphatic dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, 2-butyl-2-ethylpropanediol, and 2,4-diethylpentanediol with linear or branched saturated fatty acids can also be used. As the linear or branched saturated fatty acid, monovalent linear or branched saturated fatty acids having 4 to 30 carbon atoms are preferred.
Furthermore, carbonate esters can also be used.

Examples of the ether oil include polyglycol and (poly)phenyl ether.
Examples of polyglycols include polyethylene glycol, polypropylene glycol, and derivatives thereof.
Examples of the (poly)phenyl ether include alkylated diphenyl ether, monoalkylated tetraphenyl ether, dialkylated tetraphenyl ether, and pentaphenyl ether.

The thermally conductive composition of the present invention is applied to heat-generating parts and is therefore exposed to high temperatures for long periods of time. For this reason, it is desirable for the base oil to have excellent thermal oxidation stability. Among the above base oils, synthetic oils are preferred, with synthetic hydrocarbon oils, ester oils, and ether oils being more preferred. Of these base oils, those with particularly excellent thermal oxidation stability are poly-α-olefins among synthetic hydrocarbon oils, polyol esters among ester oils, and alkyl diphenyl ethers among ether oils, and are used as preferred base oils. Furthermore, among these base oils, poly-α-olefins and polyol esters are preferred, as they have a relatively high viscosity index and can be used to prepare thermally conductive compositions that are soft and have excellent spreadability. Furthermore, if particularly excellent spreadability is not required, alkyl diphenyl ethers and (poly)phenyl ethers, which have high viscosity, can also be used.

A particularly preferred base oil is at least one selected from the group consisting of hydrocarbon synthetic oils, ether synthetic oils, and ester synthetic oils. More specific examples include hydrocarbon synthetic oils such as poly-α-olefins, copolymers of ethylene and α-olefins, alkylnaphthalenes, and alkylbenzenes, as well as alkyldiphenyl ethers, diesters, triesters, tetraesters, and synthetic esters obtained by dehydration condensation of polyhydric alcohols and fatty acids.

The kinematic viscosity of the base oil at 40°C is preferably 10 mm ² /s to 600 mm ² /s. A kinematic viscosity of 10 mm ² /s or more is preferred because evaporation of the base oil and oil separation at high temperatures tend to be suppressed. A kinematic viscosity of ^{600 mm 2} /s or less is preferred because it is easier to obtain appropriate fluidity.
As the base oil of the present invention, a poly-α-olefin having a kinematic viscosity of 10 to 100 mm ² /s at 40° C. is particularly preferred. Use of this base oil makes it easier to obtain appropriate fluidity for the thermally conductive composition.
The content of the base oil is preferably 2 to 19 parts by mass, more preferably 2 to 9 parts by mass, and particularly preferably 2 to 5 parts by mass, when the total amount of components (A), (B), and (C) of the present invention is taken as 100 parts by mass. If the content is 20 parts by mass or more, the thermally conductive composition may become too soft and may not become semi-solid. If the content is 1 part by mass or less, sufficient fluidity may not be maintained, or the thermally conductive composition may not be able to be prepared.

(C) Polyether Carboxylic Acid Compounds Examples of polyether carboxylic acid compounds that can be used in the present invention include those represented by the following formula (I) or (II).
R ₁ O(R ₂ O) _n -R ₃ -COOH (I)
R ₄ O(R ₅ O) _m -C(=O)-R ₆ -COOH (II)
In the formula, R ₁ and R ₄ are each independently a linear or branched alkyl group having 1 to 36 carbon atoms, a linear or branched alkenyl group having 2 to 36 carbon atoms, an aliphatic hydrocarbon group having a cyclic structure having 3 to 36 carbon atoms, or an aryl group having 6 to 36 carbon atoms; R ₂ O and R ₅ O are each independently oxyethylene or oxypropylene; R ₃ and R ₆ are each independently a linear or branched alkyl group having 1 to 36 carbon atoms, a linear or branched alkenyl group having 2 to 36 carbon atoms, an aliphatic hydrocarbon group having a cyclic structure having 3 to 36 carbon atoms, or an aryl group having 6 to 36 carbon atoms; and n and m represent the degree of polymerization and are each independently a positive number of 1 or more, for example, 1 to 15.
_R1 is preferably a linear alkenyl group having 16 to 18 carbon atoms. _R2O is preferably oxyethylene. _R3 is preferably an alkyl group having 1 carbon atom. n is preferably 1 or 2.
_R4 is preferably a linear alkyl group having 12 to 14 carbon atoms. _R5O is preferably oxyethylene. _R6 is preferably an alkenyl group having 2 carbon atoms. m is preferably 5 to 7.

The polyether carboxylic acid compound (C) is preferably at least one compound selected from the group consisting of poly(oxyethylene) alkyl ether carboxylic acids, poly(oxyethylene) alkenyl ether carboxylic acids, poly(oxyethylene) aryl ether carboxylic acids, poly(oxypropylene) alkyl ether carboxylic acids, poly(oxypropylene) alkenyl ether carboxylic acids, and poly(oxypropylene) aryl ether carboxylic acids.
Among these, at least one compound selected from the group consisting of poly(oxyethylene) alkenyl ether carboxylic acids is preferred. For example, a compound represented by the following formula (i):
CH ₃ (CH ₂ ) _x CH=CH(CH ₂ ) ₈ O(CH ₂ CH ₂ O) _y CH ₂ COOH (i) (in the formula, x=5 to 7, y to 2)
Preferred is a polyether carboxylic acid compound represented by the following formula (ii):
_CH3 ( _CH2 ) _7CH =CH( _CH2 ) _{8O ( CH2CH2O} ) _CH2COOH (ii)
Also preferred are polyether carboxylic acid compounds represented by the following formula:
It is more preferable that the polyether carboxylic acid compound (C) includes a compound represented by formula (i) or (ii).

The content of the polyether carboxylic acid compound is preferably 0.01 to 3 parts by mass, more preferably 0.1 to 2 parts by mass, and particularly preferably 0.5 to 1 part by mass, based on 100 parts by mass of the total amount of components (A), (B), and (C) of the present invention. If the content is less than 0.01 part by mass, it may be impossible to prepare a thermally conductive composition. On the other hand, if the content is more than 3 parts by mass, it is not possible to expect a balance between thermal conductivity and fluidity.

The unworked penetration of the composition of the present invention is preferably 265 or more. This indicates that the composition has appropriate fluidity. A value of 280 or more is more preferable, and a value of 295 or more is even more preferable. The unworked penetration is preferably 440 or less. This indicates that the composition is semi-solid. A value of 420 or less is more preferable, and a value of 400 or less is even more preferable. The unworked penetration of the composition of the present invention is the 1/4 unworked penetration value measured in accordance with JIS K 2220:2013.

The composition of the present invention may contain known additives used in greases, as needed. Examples include metal deactivators and antioxidants.

The metal deactivator may be at least one selected from the group consisting of benzotriazole derivatives, benzimidazole derivatives, dimercaptothiazole derivatives, oxyquinoline derivatives, salicylidene derivatives, thiocarbamate compounds, piperidine compounds, salicylic acid compounds, and thiophosphate compounds.
The content of the metal deactivator is preferably 0.01 to 2.0 parts by mass, and more preferably 0.02 to 0.5 parts by mass, when the total amount of components (A), (B), and (C) of the present invention is taken as 100 parts by mass. If the content of the metal deactivator is less than 0.01 part by mass, there is a risk of corrosion of the material to which the composition is applied, and even if the content exceeds 2.0 parts by mass, no significant difference in effect will be achieved.

The antioxidants include phenolic antioxidants and amine antioxidants.
Suitable phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane.
Suitable amine antioxidants include naphthylamines such as phenyl-α-naphthylamine and phenyl-β-naphthylamine, (alkylated) diphenylamines such as p,p'-dialkyldiphenylamine, diphenyl-p-phenylenediamine, dipyridylamines, and phenothiazines. Among these, naphthylamines and alkylated diphenylamines are preferred because they are highly oil-soluble and less likely to produce sludge, with alkylated diphenylamines being particularly preferred. Naphthylamines may or may not have an alkyl group. When naphthylamines have an alkyl group, those with an alkyl group on the phenyl group are preferred. In this case, the alkyl group preferably has 4 to 20 carbon atoms, more preferably 6 to 18 carbon atoms.

Examples of alkylated diphenylamines include monoalkylated diphenylamines, dialkylated diphenylamines, trialkylated diphenylamines, and tetraalkylated diphenylamines, with dialkylated diphenylamines being preferred.
The alkyl group in the alkylated diphenylamines is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 3 to 14 carbon atoms, and particularly preferably an alkyl group having 4 to 12 carbon atoms.
Amine-based antioxidants have the effect of preventing radical chain reactions at high temperatures, and because they themselves have low sublimation properties, they are effective in improving heat resistance compared to when other antioxidants are used.
These antioxidants may be used alone or in combination of two or more. The content of the antioxidant is preferably 0.05 to 2 parts by mass, more preferably 0.1 to 1 part by mass, per 100 parts by mass of the composition of the present invention. If the content of the antioxidant is less than 0.05 parts by mass, the effect is small, and if it is more than 2 parts by mass, not only cannot be expected to improve the effect, but also the composition tends to harden due to the influence of degradation products of the antioxidant itself when exposed to high temperatures for a long period of time.

Further examples include sulfur-based antioxidants such as sulfides, disulfides, trisulfides, and thiobisphenols; phosphorus-based antioxidants such as alkyl phosphites and ZnDTP; rust inhibitors such as sulfonates, carboxylic acids, carboxylates, and succinate esters; corrosion inhibitors such as compounds such as benzotriazole and its derivatives, and thiadiazole compounds; and thickeners such as polyisobutylene, polyalkyl methacrylate, olefin copolymers, and high-viscosity poly-α-olefins. The amounts of these additives to be added may be the usual amounts.

The composition of the present invention can be easily produced by uniformly mixing components (A), (B), and (C) and, if necessary, optional components, using a mortar, a planetary mixer, or the like to knead the components while heating, followed by further uniform kneading using a three-roll mill, or by kneading using a planetary mixer.
Generally, a semi-solid or solid substance obtained by dispersing a thickener in a raw base oil is called a grease, but a substance obtained by adding an inorganic filler or organic filler as specified in the present invention to a base oil instead of a thickener and making it into a paste form is also called a grease. The composition of the present invention is also sometimes called a compound.
The composition of the present invention can be used in parts that generate heat during use, such as CPUs in electronic devices, Peltier elements, power semiconductors for power supply control such as LEDs, and high-output inverters in hybrid and electric vehicles.

The thermally conductive compositions of the Examples and Comparative Examples were prepared as follows: The base oil, additives, and inorganic filler were placed in a centrifugal mixer "Awatori Rentaro ARE-310" (manufactured by Thinky Corporation) and mixed at 25°C and a revolution speed of 1,400 rpm so as to achieve the components and contents shown in Table 1. Subsequently, the thermal conductivity and fluidity were evaluated by the following methods.
<Thermal conductivity evaluation>
The thermal conductivity was measured at 25°C using a hot disc method thermophysical property apparatus "TPA-501" (manufactured by Kyoto Electronics Manufacturing Co., Ltd.).
<Liquidity evaluation>
The fluidity was evaluated by measuring the shear viscosity and consistency using a rheometer.
Measurement of Shear Viscosity The shear viscosity was measured using a rheometer "MCR301" (manufactured by Anton Paar). The shear viscosity values 3 minutes after the start of measurement are shown in Table 1.
[Measurement conditions]
Plate type: 25 mm parallel plate Distance between plate and stage: 200 μm
Shear rate: 1/sec Temperature: 25°C
Measurement time: 3 minutes. Measurement of Penetration: Unworked penetration was measured in accordance with JIS K 2220.
The results are shown in Tables 1 and 2.

In Tables 1 and 2, the values outside the parentheses for (A) inorganic filler mean mass % relative to 100 mass % of the thermally conductive composition, and the values in the parentheses mean mass % relative to 100 mass % of the inorganic filler.
*0: The average particle size of the inorganic filler (A) is the median diameter measured using a laser diffraction/scattering method.
*1: Polyoxyethylene oleyl ether carboxylic acid (Kao Corporation's "Akipo LS-O90")
* 2: Isopropyl triisostearoyl titanate (Ajinomoto Fine-Techno Co., Ltd.'s "Plenact TTS")
* 3: Acetoalkoxyaluminum diisopropylate (Ajinomoto Fine-Techno Co., Ltd. "Plenact AL-M")
* 4: Octyltriethoxysilane ("Silquest A-137" manufactured by Momentive)
*5: Erucic acid (Tokyo Chemical Industry Co., Ltd.)

Claims (3)

A thermally conductive composition comprising (A) an inorganic filler, (B) a base oil, and (C) a polyether carboxylic acid compound ,
(C) The thermally conductive composition, wherein the polyether carboxylic acid compound is at least one compound selected from the group consisting of poly(oxyethylene) alkyl ether carboxylic acids, poly(oxyethylene) alkenyl ether carboxylic acids, poly(oxyethylene) aryl ether carboxylic acids, poly(oxypropylene) alkyl ether carboxylic acids, poly(oxypropylene) alkenyl ether carboxylic acids, and poly(oxypropylene) aryl ether carboxylic acids . (A) the inorganic filler is composed of a first inorganic filler in a proportion of 10% by mass or more and 40% by mass or less, a second inorganic filler in a proportion of 10% by mass or more and 40% by mass or less, and a third inorganic filler in a proportion of 40% by mass or more and 80% by mass or less, relative to 100% by mass of the inorganic filler;
The first inorganic filler has a most frequent particle size of 0.1 to 2 μm,
the most frequent particle size of the second inorganic filler is 2 times or more and 500 times or less than the most frequent particle size of the first inorganic filler;
The most frequent particle size of the third inorganic filler is 4 times or more and 5000 times or less than the most frequent particle size of the first inorganic filler.
The thermally conductive composition of claim 1. 3. The thermally conductive composition according to claim 1, which is free of silicone oil.