JP2018053025A - Thermally conductive silicone grease composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally conductive silicone grease composition excellent in thermal conductivity.SOLUTION: A thermally conductive silicone grease composition contains (A) organopolysiloxane, (B) an aromatic-containing organic compound being liquid at room temperature, (total of components (A) and (B) is 100 pts.mass), (C) a thermally conductive inorganic filler having an average particle diameter of 5 μm or more and 100 μm or less, (D) a thermally conductive inorganic filler having an average particle diameter of 0.05 μm or more and less than 5 μm, where with respect to 100 pts.mass of the total of the components (A) and (B), the thermally conductive silicone grease composition contains 200-2,000 pts.mass of the total of the components (C) and (D), an SP value (SP (A)) of the component (A) and an SP value (SP(B)) of the component (B) satisfy a relationship of SP(B)-SP(A)>2, the viscosity of the thermally conductive silicone grease composition is 50-1,000 Pa s at 25°C, and the component (C) and the component (D) are the thermally conductive inorganic fillers having different pH.SELECTED DRAWING: None

Description

  The present invention relates to a thermally conductive silicone grease composition, and relates to a thermally conductive silicone grease composition having excellent thermal conductivity.

  Generally, since heat is generated during use of electric / electronic parts, heat removal is necessary to operate these parts properly. Conventionally, various heat conductive materials used for heat removal have been used. Proposed. In this case, there are two types of thermally conductive materials: (1) a sheet-like material that is easy to handle, and (2) a paste-like material called heat radiation grease.

  Of these, the sheet-like material (1) has the advantage of being easy to handle and excellent in stability, while the contact thermal resistance is inevitably increased. It will be inferior to the case. In addition, since a certain degree of strength and hardness is required to maintain the sheet shape, tolerances generated between the element and the housing cannot be absorbed, and the element may be destroyed by the stress.

  On the other hand, in the case of the heat radiation grease (2), not only can it be applied to mass production of electrical and electronic products by using a dispensing device, a printing device, etc., but also the heat radiation performance is low because the contact thermal resistance is low. There is an advantage of being excellent. However, when the viscosity of the heat-dissipating grease is lowered in order to obtain good dispensing performance and printing performance, the amount of thermally conductive inorganic filler is limited and sufficient heat conductivity cannot be ensured. As a result, the device may malfunction.

  Therefore, a specific organopolysiloxane, a thickener such as zinc oxide, alumina, aluminum nitride, boron nitride, and silicon carbide, an organopolysiloxane having at least one hydroxyl group directly bonded to a silicon atom in one molecule, and Grease-like silicone composition in which bleed of base oil is suppressed by combining alkoxysilane (Patent Document 1); liquid silicone, thermally conductive inorganic filler having a constant thermal conductivity and a Mohs hardness of 6 or more, and Thermally conductive silicone composition excellent in thermal conductivity and dispensing property comprising a combination of thermally conductive inorganic fillers having a constant thermal conductivity and a Mohs hardness of 5 or less (Patent Document 2); a specific base oil And a thermally conductive grease composition comprising a metal aluminum powder having an average particle size of 0.5 to 50 μm (Patent Document 3); Silicone grease composition with a high filling rate of aluminum nitride in silicone grease by mixing two different types of aluminum nitride powder (Patent Document 4); and increasing oil viscosity to suppress bleed-out A higher performance heat conductive silicone grease composition such as a silicone grease composition (Patent Document 5) has been proposed, but it can sufficiently cope with higher performance of electronic and electric parts used. Has not been obtained yet.

Japanese Patent Laid-Open No. 11-49958 JP-A-11-246884 JP 2000-63873 A JP 2000-169873 A JP 2003-301184 A

  Accordingly, an object of the present invention is to provide a thermally conductive silicone grease composition having excellent thermal conductivity.

  As a result of intensive studies to achieve the above object, the present inventor has found that a specific organopolysiloxane, an aromatic-containing organic compound that has a higher SP value than the organopolysiloxane and is liquid at room temperature, By combining two or more types of thermally conductive fillers having different surface charges at the pH of a mixture of an organopolysiloxane and an aromatic-containing organic compound that is liquid at room temperature, different types of thermally conductive fillers are electrostatically charged. Thus, the present inventors have found that a heat conductive silicone grease composition having an excellent heat conductivity can be obtained by actively aggregating the heat path and making the present invention.

（式中、Ｒ¹は同一又は異種の１価炭化水素基である。Ｘ¹、Ｘ²、Ｘ³はＲ¹又は−Ｒ²−ＳｉＲ¹ _a（ＯＲ³）_3-aで示される基であり、それぞれ異なっても良い。Ｒ¹は上記の通り、Ｒ²は酸素原子又は炭素数１〜４のアルキレン基、Ｒ³は炭素数１〜４のアルキル基、アルコキシアルキル基、アルケニル基又はアシル基であり、ａは１〜３の整数である。ｍ及びｎはそれぞれ１≦ｍ≦１，０００、０≦ｎ≦１，０００である。）
で示され、２５℃における粘度が０．００５〜１００ｍＰａ・ｓである３官能の加水分解性オルガノポリシロキサンである[１]記載の熱伝導性シリコーングリース組成物。
[３]．熱伝導性無機充填材（Ｃ）及び（Ｄ）成分が、それぞれアルミニウム、銀、銅、ニッケル、酸化亜鉛、酸化アルミニウム、酸化ケイ素、酸化マグネシウム、窒化アルミニウム、窒化ホウ素、窒化ケイ素、及び金属ケイ素から選ばれる１種又は２種以上の組み合せである[１]又は[２]記載の熱伝導性シリコーングリース組成物。 Accordingly, the present invention provides the following thermally conductive silicone grease composition.
[1]. (A) Organopolysiloxane: 20 to 90 parts by mass,
(B) Aromatic organic compound that is liquid at room temperature: 80 to 10 parts by mass,
(However, the sum of components (A) and (B) is 100 parts by mass.)
(C) a thermally conductive inorganic filler having an average particle size of 5 μm or more and 100 μm or less,
(D) Thermally conductive inorganic filler having an average particle size of 0.05 μm or more and less than 5 μm: The total of (C) and (D) components is based on 100 parts by mass of (A) and (B) components. A thermally conductive silicone grease composition containing 200 to 2,000 parts by mass, wherein the SP value of the component (A) (SP (A)) and the SP value of the component (B) (SP (B)) SP (B) -SP (A)> 2, the viscosity of the heat conductive silicone grease composition is 50 to 1,000 Pa · s at 25 ° C., and the pH _Pzc differs between the (C) component and the (D) component. A thermally conductive silicone grease composition, which is a thermally conductive inorganic filler having:
[2]. Organopolysiloxane (A) is represented by the following general formula (1)

Wherein R ¹ is the same or different monovalent hydrocarbon group. X ¹ , X ² and X ³ are groups represented by R ¹ or —R ² —SiR ¹ _a (OR ³ ) _3-a There, even different from each good .R ¹ is of the street, R ² represents an oxygen atom or an alkylene group having 1 to 4 carbon atoms, R ³ is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, an alkenyl group or an acyl A is an integer of 1 to 3. m and n are 1 ≦ m ≦ 1,000 and 0 ≦ n ≦ 1,000, respectively.
The heat conductive silicone grease composition according to [1], which is a trifunctional hydrolyzable organopolysiloxane having a viscosity of 0.005 to 100 mPa · s at 25 ° C.
[3]. The thermally conductive inorganic fillers (C) and (D) are each composed of aluminum, silver, copper, nickel, zinc oxide, aluminum oxide, silicon oxide, magnesium oxide, aluminum nitride, boron nitride, silicon nitride, and metal silicon. The heat conductive silicone grease composition according to [1] or [2], which is one or a combination of two or more selected.

  Since the heat conductive silicone grease composition of the present invention is excellent in heat conductivity, it is suitable for heat removal from electrical / electronic components that generate heat during use.

Hereinafter, the present invention will be described in detail.
[(A) component]
The (A) component organopolysiloxane constituting the thermally conductive silicone grease composition of the present invention is a liquid silicone having a viscosity at 25 ° C. of preferably 0.005 to 100 mPa · s.

  In the present invention, the viscosity of the organopolysiloxane of component (A) at 25 ° C. as measured by a B-type rotational viscometer is preferably in the range of 0.005 to 100 mPa · s as described above. More preferably, it is -50mPa * s. If the viscosity at 25 ° C. is less than 0.005 mPa · s, the resulting silicone grease composition will be separated during storage, resulting in poor stability, and if it is greater than 100 mPa · s, mixing with the component (B) will occur. May be difficult.

（式中、Ｒ¹は同一又は異種の１価炭化水素基である。Ｘ¹、Ｘ²、Ｘ³はＲ¹又は−Ｒ²−ＳｉＲ¹ _a（ＯＲ³）_3-aで示される基であり、それぞれ異なっても良い。Ｒ¹は上記の通り、Ｒ²は酸素原子又は炭素数１〜４のアルキレン基、Ｒ³は炭素数１〜４のアルキル基、アルコキシアルキル基、アルケニル基又はアシル基であり、ａは１〜３の整数である。ｍ及びｎはそれぞれ１≦ｍ≦１，０００、０≦ｎ≦１，０００である。） The organopolysiloxane of component (A) preferably contains at least a trifunctional hydrolyzable organopolysiloxane represented by the following general formula (1).

Wherein R ¹ is the same or different monovalent hydrocarbon group. X ¹ , X ² and X ³ are groups represented by R ¹ or —R ² —SiR ¹ _a (OR ³ ) _3-a There, even different from each good .R ¹ is of the street, R ² represents an oxygen atom or an alkylene group having 1 to 4 carbon atoms, R ³ is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, an alkenyl group or an acyl A is an integer of 1 to 3. m and n are 1 ≦ m ≦ 1,000 and 0 ≦ n ≦ 1,000, respectively.

（式中、Ｒ¹は独立に非置換又は置換の１価炭化水素基であり、Ｒ³は独立に炭素数１〜４のアルキル基、アルコキシアルキル基、アルケニル基又はアシル基であり、ｐは５〜１００の整数であり、ａは１〜３の整数である。）
で表され、好ましくは２５℃における粘度が０．００５〜１００ｍＰａ・ｓのオルガノポリシロキサンである。 More preferred organopolysiloxane (A) component for use in the present invention is represented by the following general formula (2):

Wherein R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ³ is independently an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, an alkenyl group or an acyl group, and p is (It is an integer of 5-100, and a is an integer of 1-3.)
Preferably, it is an organopolysiloxane having a viscosity at 25 ° C. of 0.005 to 100 mPa · s.

In the present invention, the viscosity is measured with a Malcolm viscometer, and the maximum value recorded with a plotter is taken as the viscosity.
Rotor: A (10 rpm)
Measurement conditions: 25 ° C ± 0.5 ° C
It is the value measured by.

  Organopolysiloxane (A) maintains the fluidity of the composition even when highly filled with the thermally conductive inorganic fillers of component (C) and component (D) in order to obtain a highly thermally conductive silicone grease composition. It also has a role of imparting good handling properties.

In the above formulas (1) and (2), R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms. Examples thereof include a linear alkyl group, a branched alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group, an aralkyl group, and a halogenated alkyl group. Examples of the linear alkyl group include a methyl group, an ethyl group, a propyl group, a hexyl group, and an octyl group. Examples of the branched alkyl group include isopropyl group, isobutyl group, tert-butyl group, and 2-ethylhexyl group. Examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the alkenyl group include a vinyl group and an allyl group. Examples of the aryl group include a phenyl group and a tolyl group. Examples of the aralkyl group include 2-phenylethyl group and 2-methyl-2-phenylethyl group. Examples of the halogenated alkyl group include 3,3,3-trifluoropropyl group, 2- (nonafluorobutyl) ethyl group, and 2- (heptadecafluorooctyl) ethyl group. R ¹ is preferably a methyl group, a phenyl group, or a vinyl group.

R ³ is independently an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, an alkenyl group, or an acyl group. Examples of the alkyl group include linear alkyl groups, branched alkyl groups, and cyclic alkyl groups similar to those exemplified for R ¹ . Examples of the alkoxyalkyl group include a methoxyethyl group and a methoxypropyl group. As an acyl group, C2-C8 is preferable, for example, and an acetyl group, an octanoyl group, etc. are mentioned. R ³ is preferably an alkyl group, particularly preferably a methyl group or an ethyl group.
n and m are as described above, preferably n + m is 10 to 50, and p is an integer of 5 to 100, preferably 10 to 50. a is an integer of 1 to 3, and is preferably 3. In addition, it is preferable to have 1 to 6, or 3 or 6 OR ³ groups in the molecule.

  The viscosity at 25 ° C. of the organopolysiloxane (A) is usually 0.005 to 100 mPa · s, particularly preferably 0.005 to 50 mPa · s. When the viscosity is lower than 0.005 mPa · s, oil bleed tends to occur from the room temperature moisture-curing heat conductive silicone grease composition obtained, and it tends to sag. If the viscosity is greater than 100 mPa · s, the fluidity of the resulting thermally conductive silicone grease composition becomes poor, and there is a possibility that the dispensing property and the printability will deteriorate.

  Preferable specific examples of the organopolysiloxane (A) include the following.

  (A) The compounding quantity of a component is 20-90 mass parts in a total of 100 mass parts of (A) and (B) component, 30-80 mass parts is more preferable, and 70-80 mass parts is more preferable. If the amount of the component (A) is less than 20 parts by mass, the thermally conductive silicone composition thickens and cannot be discharged. If the amount is more than 90 parts by mass, the viscosity becomes too low and the component (A) bleeds. .

[(B) component]
The aromatic-containing organic compound that is liquid at room temperature as the component (B) is preferably an organic compound having an organic group selected from an epoxy group, a phenol group, a cyanate group, an amino group, and a phenolic hydroxyl group in the molecule. These can be used individually by 1 type or in combination of 2 or more types.

  The following epoxy resin is mentioned as a compound which has an epoxy group. As for molecular structure, molecular weight, etc., the viscosity at 25 ° C. is preferably 10 to 1,000,000 mPa · s. As such an epoxy compound, for example, bis (4-hydroxyphenyl) methane, 2,2′-bis (4-hydroxyphenyl) propane or a diglycidyl ether of this halide and a condensation polymer thereof (so-called bisphenol F) Type epoxy resin, bisphenol A type epoxy resin, etc.), diglycidyl ether of resorcin, 1,4-bis (2,3-epoxypropoxy) benzene, 4,4′-bis (2,3-epoxypropoxy) diphenyl ether, 1 , 2-dioxybenzene or resorcinol, epoxy glycidyl ether obtained by condensing polyphenol and epichlorohydrin, naphthalene ring-containing epoxy resin, biphenyl type epoxy resin, phenol aralkyl type epoxy resin, biphenyl aralkyl type ester Carboxymethyl resins. May have an allyl group or a vinyl group in the above epoxy compounds.

  In addition, a monoepoxy compound may be used in combination with the epoxy resin as appropriate, and examples of the monoepoxy compound include styrene oxide and phenyl glycidyl ether, and these epoxy compounds have an allyl group or a vinyl group. May be.

  Examples of the phenol group-containing compound include bisphenol A, bisphenol F, trimethylol allyloxyphenol, phenol resins such as phenol novolac resin having a low polymerization degree, and dihydroxydiallyldiphenylmethane. In these phenol compounds, allyl group or It may have a vinyl group.

  Examples of the cyanate group-containing compound include 4,4′-methylidenebis [2,6-dimethylphenylene cyanate], 4,4 ′-(1-methylethylidene) bis [2-methylphenylene cyanate], 4,4 ′-(1 -Methylethylidene) bis [2,6-dimethylphenylene cyanate], 4,4'-methylenebis [2-methylphenylene cyanate], 4,4 '-(1-methyl-ethylidene) bis [2- (1,1- Dimethylethyl) phenylene cyanate] and the like, and examples of the cyanate ester represented by the formula (3) include a phenol novolak type cyanate ester and a cresol novolak type cyanate ester.

  Examples of the amino group-containing compounds include diaminodimethyldiphenylmethane, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, N-aminoethylpiperazine, bis (4-amino-3-methylcyclohexyl) methane, metaxylylenediamine, menthanediamine, 3, Amine compounds such as 9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro (5,5) undecane; epoxy resin-diethylenetriamine adduct, amine-ethylene oxide adduct, cyanoethylated polyamine, etc. Modified aliphatic polyamines; 4,4′-diaminodiphenylmethane, o-, m-, p-phenylenediamine, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,4-diaminotoluene, 2,5-dia Minotoluene, 2,4-diaminoxylene, 3,6-diaminodurene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dialkyl-4,4'-diaminobiphenyl, 2,2 '-Dimethoxy-4,4'-diaminobiphenyl, 2,2'-diethoxy-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl Sulfone, 3,3′-diaminodiphenylsulfone, 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) ) Benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, biphenyl [4- (4-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (4- Amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (3-amino-5-trifluoromethylphenoxy) phenyl] hexafluoropropane, 2,2-bis (4-amino) Phenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2-bis (3-a) No-4-hydroxyphenyl) hexafluoropropane, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 4,4′-bis (4-aminophenoxy) octafluorobiphenyl, 2,2 ′ -Bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,5-diaminobenzotrifluoride, 2.5-diaminobenzotrifluoride, 3,3'-bis (trifluoromethyl) -4,4 ' -Diaminobiphenyl, 3,3'-bis (trifluoromethyl) -5,5'-diaminobiphenyl, 4,4'-bis (4-aminotetrafluorophenoxy) tetrafluorobenzene, 4,4'-bis (4 -Aminotetrafluorophenoxy) octafluorobiphenyl, 4,4'-diaminobinaphthyl, 4,4'-diaminobenzanily Etc. The.

  (B) The compounding quantity of a component is 10-80 mass parts in a total of 100 mass parts of (A) and (B) component, 20-70 mass parts is preferable and 20-30 mass parts is more preferable. When the component (B) is too small, the desired thermal conductivity cannot be achieved, and when the component (B) is too large, the viscosity becomes high and workability deteriorates.

  The SP value (SP (A)) of the component (A) and the SP value (SP (B)) of the component (B) are SP (B)> SP (A) and SP (B) -SP (A )> 2, preferably SP (B) -SP (A) ≧ 2.5, more preferably SP (B) -SP (A) ≧ 3.

In this specification, the SP value is described by Toshinao Okitsu, “Adhesion”, Polymer Press, Vol. 40, No. 8 (1996) p342-350, ΔF of various atomic groups by Okitsu described in Table 1 below, It means the solubility parameter δ calculated by the following formula (3) using the Δv value. In the case of a mixed solvent or a copolymer, it means the solubility parameter δ calculated by the following formula (4).
δ = ΣΔF / ΣΔv (3)
δ _mix = φ ₁ δ ₁ + φ ₂ δ ₂ + ... φ _n δ _n (4)
In the formula, ΔF represents ΔF in Table 1 below, and Δv represents the molar volume Δv in Table 1 below. φ represents a volume fraction or a mole fraction, and φ ₁ + φ ₂ +... φ _n = 1.

For example, the SP value of heptane as a solvent is determined as follows.
Heptane has two —CH ₃ and five —CH ₂ — as atomic groups. The ΔF and Δv values are determined from Table 1 for each atomic group.
ΣΔF = 205 × 2 + 132 × 5 = 1070
ΣΔv = 31.8 × 2 + 16.5 × 5 = 146.1
Therefore, δ _hep of heptane can be obtained from the above equation (3) as follows.
δ _hep = ΣΔF / ΣΔv = 1070 / 146.1 = 7.32

Similarly, the bifunctional phenol resin of the following formula (i) has three groups of —CH ₂ —, two CH ₂ ═, two —CH═, two —OH (Arom), — It has 2 C ₆ H ₃ (Arom). The ΔF and Δv values are determined from Table 1 for each atomic group.
ΣΔF = 2594.0
ΣΔv = 241
Therefore, from the above formula (3), δ _{phOH of the} bifunctional phenol resin is obtained as follows.
δ _phOH = d * ΣΔF / ΣΔv = 1.15 * 2594.0 / 241 = 12.4
Dihydroxydiallyldiphenylmethane (SP value 12.9, viscosity 2,500 mPa · s)

Similarly, the bisphenol F type epoxy resin of the following formula (ii) has an SP value of 12.7 and a viscosity of 1,300 mPa · s.

Similarly, the following formula (iii) diaminodimethyldiphenylmethane has an SP value of 11.8 and a viscosity of 1,500 mPa · s.

  In addition, from the scientific chronology, the 84th volume, the thing 54 (410), the thermal conductivity of silicone is 0.16 W / mK, and the epoxy resin (Bis phenol A) is 0.21 W / mK.

  When the polyorganosiloxane (A) and the specific organic compound (B) are mixed, they are separated if the difference in SP value is greater than 2. The metal surface is affected by oxygen in the atmosphere to become a metal oxide, and the metal oxide itself and the surface of the metal nitride have hydroxyl groups or amino groups on the surface due to the effects of oxygen and moisture in the atmosphere. To do. By this surface functional group, the aromatic-containing organic compound having a high SP value has a strong interaction with the thermally conductive inorganic filler. In this way, the specific organic compound of the component (B) having an SP value that is intentionally different and having a higher SP value than the component (A) is placed between the thermally conductive inorganic filler islands floating in the silicone matrix. By carrying out crosslinking with an aromatic-containing organic compound, it has come to exhibit heat dissipation characteristics that were not found in conventional silicone-based heat conductive heat dissipation greases. In addition, by imparting thermosetting properties to the aromatic-containing organic compound, the heat path between the thermally conductive inorganic filler and the aromatic-containing organic compound can be reduced even when the grease is misaligned and deformed, or even in a low-temperature or high-temperature environment. Since it is maintained, it can be expected that the heat conduction characteristics do not change.

[(C) component, (D) component]
(C) Thermally conductive inorganic filler having an average particle diameter of 5 μm or more and 100 μm or less (D) Thermally conductive inorganic filler having an average particle diameter of 0.05 μm or more and less than 5 μm (C) and (D) components are: It is a filler that imparts thermal conductivity to the thermally conductive silicone grease composition of the present invention.

  The average particle diameter of the thermally conductive inorganic filler (C) is 5 μm or more and 100 μm or less, and preferably 5 μm or more and 20 μm or less. Even if the average particle size is smaller than 5 μm or larger than 100 μm, the grease becomes non-uniform and has a high viscosity. In the present invention, the average particle diameter is a volume-based cumulative average diameter measured by a laser diffraction method.

  The average particle size of the thermally conductive inorganic filler (D) is 0.05 μm or more and less than 5 μm, and more preferably 0.1 μm or more and 1 μm or less. Even if the average particle size is less than 0.05 μm or more than 5 μm, the grease becomes non-uniform and the viscosity becomes high.

  Examples of the thermally conductive inorganic filler of the components (C) and (D) include metal powder, metal oxide powder, metal hydroxide powder, and metal nitride powder, specifically, aluminum, A combination of one or more selected from silver, copper, nickel, zinc oxide, aluminum oxide, silicon oxide, magnesium oxide, aluminum nitride, boron nitride, silicon nitride, and metal silicon is preferable.

In the mixture of the components (A) and (B), the component (C) and the component (D) have different pH _pzc . pH _pzc (point of zero charge) refers to the pH at which the surface charge of a substance is zero. At a pH _lower than pH _pzc , the material surface is positively charged, and at a high pH, the material surface is negatively charged. For example, at pH 7, silicon oxide (pH _pzc = 2.6) is negatively charged, aluminum oxide (pH _pzc = 8.5) is almost neutral, zinc oxide (pH _pzc = 9.5) and magnesium oxide ( pH _pzc = 11.3) is positively charged.

  As in the present invention, in the system of the organopolysiloxane (A) and the aromatic-containing organic substance (B), protons are difficult to exist stably, so that the proton concentration becomes low and as a result, the pH becomes high. If only protons having a pH corresponding to 10 can exist in the system, zinc oxide is positive, aluminum oxide is electrically neutral to negative, and magnesium oxide is positive. For example, the pH can be effectively changed by blending a basic aromatic organic compound (aniline) or the like into the organopolysiloxane.

  As an example, when aluminum oxide is selected as the thermally conductive inorganic filler (C) and aluminum oxide is selected as the thermally conductive inorganic filler (D), they are repelled because they have the same charge. Therefore, it is difficult to form a thermal path, and a decrease in thermal conductivity is expected. When aluminum oxide is selected as the thermally conductive inorganic filler (C) and zinc oxide is selected as the thermally conductive inorganic filler (D), an attractive force acts between the particles because they have different charges, Improvement in thermal conductivity is expected.

The combination of the component (C) and the component (D) is not particularly limited as long as the pH _pzc is different. However, the component (C) is preferably aluminum powder or aluminum oxide powder, and the component (D) is oxidized. Zinc powder, magnesium oxide powder or silicon oxide powder is preferred. Furthermore, when aluminum powder is selected as the component (C), the component (D) is preferably zinc oxide powder or magnesium oxide powder, more preferably zinc oxide powder. Moreover, when aluminum oxide powder is selected as the component (C), the component (D) is preferably magnesium oxide.

  When the organopolysiloxane (A) is fixed and the aromatic-containing organic compound (B) is changed, a change in proton concentration is expected. In general, since phenol acts as an acid, it becomes proton-rich, and amine is expected to decrease protons. Even with the same thermally conductive inorganic filler composition, the attractive and repulsive forces acting between the particles differ.

  The blending amount of the components (C) and (D) is 200 to 2,000 parts by mass of the total of the components (C) and (D) with respect to 100 parts by mass of the components (A) and (B). 700 to 1,700 parts by mass are preferable. Moreover, 70 / 30-90 / 10 are preferable and, as for the compounding mass ratio of (C) component and (D) component, 75 / 25-85 / 15 are more preferable.

[Production method]
When producing the heat conductive silicone grease composition of the present invention, the components (A), (B), (C) and (D) and other components are added, and a trimix, twin mix, planetary mixer ( All are registered trademarks of the mixer manufactured by Inoue Seisakusho Co., Ltd., Ultramixer (registered trademark of the mixer manufactured by Mizuho Industry Co., Ltd.), Hibis Disper Mix (registered trademark of the mixer manufactured by Special Machine Industries, Ltd.) Mix using a mixer. If necessary, you may heat to 50-170 degreeC.

  The hardness when the thermally conductive silicone grease composition of the present invention is heated at 150 ° C. for 120 minutes is preferably from 5 to 75, more preferably from 10 to 60, as measured by Asker C. Thus, by hardening (or thickening), generation | occurrence | production of a crack and shift | offset | difference can be prevented.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Viscosity of organopolysiloxane and aromatic organic compounds]
Using a Brookfield type rotational viscometer, 25 ± 0.5 ° C., rotor No. The measurement was performed at 4, 10 rpm.

[Grease viscosity]
The viscosity of the thermally conductive silicone grease composition was measured at 25 ° C. using model number PC-1TL (rotation speed: 10 rpm) manufactured by Malcolm Corporation.

〔Thermal conductivity〕
The thermal conductivity was measured at 25 ° C. using TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.

In addition, (A)-(D) component in a table | surface is as follows.
[(A) component]
A-1: Organopolysiloxane (SP value 8.0, viscosity 30 mPa · s)

[(B) component]
B-1: Dihydroxydiallyldiphenylmethane (SP value 12.9, viscosity 2,500 mPa · s)

B-2: Bisphenol F type epoxy resin (SP value 12.7, viscosity 1,300 mPa · s)

B-3: Diaminodimethyldiphenylmethane (SP value 11.8, viscosity 1,500 mPa · s)

[(C) component]:
C-1: Aluminum powder (average particle size 10 μm)
pH _PZC : 8.5, thermal conductivity: 236 W / mK
C-2: Aluminum oxide powder (average particle size 10 μm)
pH _PZC : 8.5, thermal conductivity: 30 W / mK

(D) component:
D-1: Aluminum oxide powder (average particle size: 1.0 μm)
pH _PZC : 8.5, thermal conductivity: 30 W / mK
D-2: Zinc oxide powder (average particle size 1.1 μm)
pH _PZC : 9.5, thermal conductivity: 25 W / mK
D-3: Magnesium oxide powder (average particle size: 0.9 μm)
pH _PZC : 11.3, thermal conductivity: 50 W / mK
D-4: Silicon oxide powder (average particle size: 1.0 μm)
pH _PZC : 2.6, thermal conductivity: 1.3 W / mK
The particle size of the thermally conductive inorganic filler (component (C), component (D)) is a volume-based cumulative average diameter measured by Microtrac MT3300EX, a particle size analyzer manufactured by Nikkiso Co., Ltd.

  The thermally conductive silicone grease composition of the present invention has excellent thermal conductivity and is suitable for heat removal from electrical / electronic components that generate heat during use.

Claims (3)

(A) Organopolysiloxane: 20 to 90 parts by mass,
(B) Aromatic organic compound that is liquid at room temperature: 80 to 10 parts by mass,
(However, the sum of components (A) and (B) is 100 parts by mass.)
(C) a thermally conductive inorganic filler having an average particle size of 5 μm or more and 100 μm or less,
(D) Thermally conductive inorganic filler having an average particle size of 0.05 μm or more and less than 5 μm: The total of (C) and (D) components is based on 100 parts by mass of (A) and (B) components. A thermally conductive silicone grease composition containing 200 to 2,000 parts by mass, wherein the SP value of the component (A) (SP (A)) and the SP value of the component (B) (SP (B)) SP (B) -SP (A)> 2, the viscosity of the heat conductive silicone grease composition is 50 to 1,000 Pa · s at 25 ° C., and the pH _Pzc differs between the (C) component and the (D) component. A thermally conductive silicone grease composition, which is a thermally conductive inorganic filler having: Organopolysiloxane (A) is represented by the following general formula (1)

Wherein R ¹ is the same or different monovalent hydrocarbon group. X ¹ , X ² and X ³ are groups represented by R ¹ or —R ² —SiR ¹ _a (OR ³ ) _3-a There, even different from each good .R ¹ is of the street, R ² represents an oxygen atom or an alkylene group having 1 to 4 carbon atoms, R ³ is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, an alkenyl group or an acyl A is an integer of 1 to 3. m and n are 1 ≦ m ≦ 1,000 and 0 ≦ n ≦ 1,000, respectively.
The thermally conductive silicone grease composition according to claim 1, which is a trifunctional hydrolyzable organopolysiloxane having a viscosity of 0.005 to 100 mPa · s at 25 ° C.   The thermally conductive inorganic fillers (C) and (D) are each composed of aluminum, silver, copper, nickel, zinc oxide, aluminum oxide, silicon oxide, magnesium oxide, aluminum nitride, boron nitride, silicon nitride, and metal silicon. The thermally conductive silicone grease composition according to claim 1 or 2, which is one or a combination of two or more selected.