JP2930298B1 - Thermal conductive grease composition - Google Patents

Abstract

The present invention provides a heat-dissipating grease composition having excellent water resistance despite using aluminum nitride as a filler. SOLUTION: A) General formula R ¹ _a R ² _b SiY
50 to 95% by weight of aluminum nitride powder surface-treated with the organosilane represented by _4-ab and / or its partial hydrolysis condensate, and B) liquid silicone, liquid hydrocarbon oil and fluorocarbon A thermally conductive grease composition comprising 5 to 50% by weight of at least one base oil selected from hydrogen oil. However, R ¹ in the above formula is an alkyl group having 6 to 20 carbon atoms, or a group in which part or all of the hydrogen atoms bonded to the carbon atoms of this group are substituted with halogen atoms, and R ² is a carbon atom. A hydrocarbon group having 1 to 20 atoms,
Or a group in which part or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, Y is a hydrolyzable group, a is an integer of 1 to 3, b is an integer of 0 to 2, a + b Is 1
-3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-dissipating grease composition, and more particularly, to a heat-conductive grease composition having excellent moisture resistance and suitable as a heat-producing material for electronic parts.

[0002]

2. Description of the Related Art Since many electronic components generate heat during use, it is necessary to remove heat from the electronic components in order to function properly. Therefore, aluminum nitride, which has high thermal conductivity and electrical insulation,
It is expected to be applied as a heat dissipation material for electronic components. The use form in this case is various, such as a form as a molded product or as a filler for grease or synthetic rubber.

[0003] However, aluminum nitride has poor water resistance. In particular, in the case of powder, the aluminum oxide gradually decomposes even when left in the air, generates ammonia, and changes to aluminum hydroxide. Therefore, when aluminum nitride powder is used, for example, as a filler for increasing the heat radiation of a resin, poor water resistance becomes a problem.

Therefore, in order to improve the water resistance of aluminum nitride, an organic polymer is coated on the surface of the aluminum nitride powder, or the surface of the aluminum nitride powder is oxidized to form an aluminum oxide layer. Attempts have been made to do so. Also, JP-A-4-32150
Japanese Patent Application Laid-Open No. 6-26139 proposes a technique of coating an aluminum nitride powder surface by reacting an organosilane oligomer with a polyorganosiloxane having a silanol group using a catalyst.

[0005] However, none of these methods has been able to provide sufficient water resistance of aluminum nitride. Therefore, when these aluminum nitrides are used in a heat-dissipating silicone grease composition, there is a drawback that the heat-dissipating properties of the silicone grease composition gradually decrease.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a grease composition for heat radiation which has excellent water resistance despite using aluminum nitride powder as a filler.

[0007]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
A) the general formula ^{_{R 1 a R 2 b SiY 4}} -a-b organosilane represented by and / or aluminum nitride powder formed by the surface treatment by the partial hydrolysis-condensation product of 50 to 95
% By weight, and B) at least one base oil selected from liquid silicones, liquid hydrocarbon oils and fluorohydrocarbon oils in an amount of 5 to 50% by weight. Where R is
¹ is an alkyl group having 6 to 20 carbon atoms, or a group in which part or all of the hydrogen atoms bonded to the carbon atoms of the group are substituted with halogen atoms, and R ² is a hydrocarbon having 1 to 20 carbon atoms. A group or a group in which part or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, Y is a hydrolyzable group, a is an integer of 1 to 3, b is an integer of 0 to 2 ,
a + b is an integer of 1 to 3.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The alkyl group of R ¹ in the general formula R ¹ _a R ² _b SiY _4- ab of an organosilane used as a surface treating agent for aluminum nitride as the component A in the present invention is, for example, hexyl Group, octyl group,
Examples thereof include a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, and an octadecyl group, and an alkyl group having 6 to 14 carbon atoms is particularly preferable. a is 1, 2 or 3, and particularly preferably 1.

The hydrocarbon group for R ² includes an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group,
And aralkyl groups. Specific examples of R ² include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and a pentyl group; a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group; an alkenyl group such as a vinyl group and an allyl group. Aryl groups such as phenyl group and tolyl group; aralkyl groups such as 2-phenylethyl group and 2-methyl-2-phenylethyl group; 3,3,3-trifluoropropyl group and 2- (perfluorobutyl) ethyl Group, 2
Examples thereof include halogenated hydrocarbon groups such as-(perfluorooctyl) ethyl group and p-chlorophenyl group, and a methyl group is particularly preferable.

As the hydrolyzable group Y, a hydroxyl group,
Or a functional group selected from an alkoxy group having 1 to 6 carbon atoms, an acyloxy group, and an alkenyloxy group. Specific examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an acetoxy group, And a propenoxy group. In the present invention, among these, a hydroxyl group and an alkoxy group are particularly preferred.

An organosilane compound represented by the above general formula
Examples of the body include the following. C₆H₁₃Si (OCH₃)₃, C₁₀H₂₁Si (O
CH₃)₃, C₁₂H_{2 5}Si (OCH₃)₃, C₁₆
H₃₃Si (OCH₃)₃, C₁₀H₂₁Si (C
H₃) (OCH₃)₂, C₁₀H₂₁Si (C₆H₅)
(OCH₃)₂, C₆H₁₃Si (COCH₃)₃, C
₁₀H₂₁Si (CH₃) (COCH₃)₂, C₆H
₁₃Si (CH₂CH₂C₆H₅) (OH)₂, C₆H
₁₃Si (OH) ₃, C₁₀H₂₁Si (CH = C
H₂) (OCH₃)₂, C₁₀H₂₁Si (CH₂CH
₂CF₃) (OCH₃)₂, C₄F₉CH₂CH₂Si
(OH)₃, (C₄F₉CH₂CH₂)₂Si (OCH
₃)₂, C₈F₁₇Si (OCH₃)₃, C₈F₁₇S
i (COC₂H₅)₃

The amount of the organosilane used is preferably in the range of 0.1 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the aluminum nitride powder. If the amount is less than 0.1 part by weight, the water resistance of the treated aluminum nitride becomes insufficient, and if the amount is more than 30 parts by weight, the effect does not increase and it becomes uneconomical. When the amount of the aluminum nitride surface-treated with the above-mentioned organosilane is less than 50% by weight in the grease composition, the grease composition has poor heat radiation properties,
If the content is more than 95% by weight, the finished grease will have poor spreadability. Therefore, the content is preferably in the range of 50 to 95% by weight, particularly preferably 60 to 80% by weight.

The aluminum nitride powder used in the present invention generally has a hexagonal or wurtzite type crystal structure.
It is a group III-V nitride and has a white to grayish white appearance, and its particle shape is amorphous to spherical powder, depending on the manufacturing method.

As a method for producing aluminum nitride powder as a raw material before surface treatment, a direct nitriding method in which metallic aluminum powder and nitrogen or ammonia are directly reacted, or a mixed powder of alumina and carbon is heated in a nitrogen or ammonia atmosphere. alumina reduction method that causes reduction and nitriding simultaneously, a method of reacting aluminum vapor and nitrogen directly, or the method of manufacturing the thermal decomposition of AlCl 3 _· NH ₃ and the like. The characteristics such as chemical composition (impurities), particle shape, particle size distribution, and the like differ depending on the manufacturing method. The aluminum nitride powder used in the present invention can be used in any of the manufacturing methods. Mixtures of different production methods may be used.

The aluminum nitride powder thus obtained is extremely hard and has excellent heat conductivity, electrical insulation and mechanical strength. In the present invention, any material having a Mohs hardness in the range of 7 to 9 can be used, but particularly preferably 8 to 9. The aluminum nitride powder used in the present invention has an average particle size of 0.5 to 5 μm.
A wide range of m can be used, but from the viewpoint of dispersibility of the component B in the base oil, a range of 1 to 4 μm is preferable, and a range of 2 to 4 μm is particularly preferable.

If the average particle size is less than 0.5 μm, the thickening effect is too large, so that when the grease is used, the grease becomes low in consistency (hard and poor in dispensing properties),
Not preferred for use. On the other hand, when the average particle size is larger than 5 μm, the resulting heat conductive material has poor uniformity and poor stability, and has a severe separation of base oil (large oil separation). Therefore, of course, good grease cannot be obtained. The specific surface area is 0.1 to 10
0 m ² / g range can be used, and
In order to obtain a base composition, a composition of 1 to 10 m ² / g is preferable.
More preferably, it is particularly preferably ^{2 to 5} m ² / g.

The theoretical thermal conductivity of aluminum nitride is 7.
Although it is 7 × 10 ⁻¹ cal / cm · sec · ° C., the actual measured value is usually because the manufactured aluminum nitride powder contains some impurities and contains voids and bubbles in the powder. Is smaller than the theoretical value, 6.0 × 10 ⁻¹ cal /
cm · sec · ° C or less. The aluminum nitride powder used in the present invention has a thermal conductivity of 1.5 × 10 ^-1 ca at room temperature.
It is preferably at least 1 / cm · sec · ° C.
It is preferably at least 4 × 10 ⁻¹ cal / cm · sec · ° C. Thermal conductivity of 1.5 × 10 ^-1 cal / cm · sec · ° C
In the case of the following, high thermal conductivity, which is the object of the present invention, cannot be obtained when grease or sheet is used.

As the aluminum nitride that can be used in the present invention, trade names, US, manufactured by Toyo Aluminum Co., Ltd.
UF, UM, trade name XUS manufactured by Dow Chemical Co., Ltd.
-55548, trade name, H grade and F grade, manufactured by Tokuyama Corporation, FA and ES manufactured by Nippon Light Metal Co., Ltd.
-10, trade names of Advanced Refractory Technologies. Inc., A-100WR, A-100 and AG-SD.

The method for surface treatment of aluminum nitride of the present invention may be a known method. For example, aluminum nitride and organosilane or a partial hydrolyzate thereof may be mixed by trimixing.
Twin Mix, Planetary Mixer (both are registered trademarks of a mixer manufactured by Inoue Seisakusho Co., Ltd.), Ultra Mixer (registered trademark of a mixer manufactured by Mizuho Industry Co., Ltd.), Hibis Disvermix (manufactured by Tokushu Kika Kogyo Co., Ltd.) Mix with a mixer such as a registered trademark of a mixer).

When mixing, if necessary, 50-150
You may heat to ° C. In addition, a diluting solvent such as toluene, xylene, petroleum ether, mineral spirit, isoparaffin, isopropyl alcohol, and ethanol may be used for the mixing. In this case, it is preferable to remove the mixed solvent using a vacuum device or the like.

It is also possible to use a base oil of component B, which is a liquid component used in the present invention, as a diluting solvent. In this case, the treating agent, organosilane or a partial hydrolyzate thereof, may be mixed in advance with the base oil, and aluminum nitride powder may be added thereto to simultaneously perform the treatment and mixing. Compositions made in this manner are also encompassed by the present invention.

The liquid silicone used as the base oil of the component B is a known silicone which is liquid at room temperature, for example, polyorganosiloxane, polyorganosylalkylene,
It can be appropriately selected from polyorganosilanes and copolymers thereof, but from the viewpoint of heat resistance, stability, electric insulation and the like, polyorganosiloxanes are preferred,
In particular, the organopolysiloxane is preferably represented by the general formula ^{_{R 4 c SiO (4-c}} ) / 2. In the above formula, R ⁴
Represents at least one selected from the group consisting of a saturated or unsaturated monovalent hydrocarbon group having 1 to 18 carbon atoms.
Is a seed group. All R ⁴ may be the same or different from each other.

Examples of such a group include a methyl group,
Ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, etc., alkyl group; cyclopentyl group, cyclohexyl group, etc., cycloalkyl group; vinyl group Aryl groups such as phenyl and tolyl groups; aralkyl groups such as 2-phenylethyl group and 2-methyl-2-phenylethyl group; or hydrogen bonded to carbon atoms of these groups A chloromethyl group, a 3,3,3-trifluoropropyl group, a 2- (perfluorobutyl) ethyl group or a 2- (perfluorobutyl) group in which some or all of the atoms are substituted with a halogen atom, a cyano group, a hydroxyl group, or the like;
(Perfluorooctyl) the same or different unsubstituted or substituted C1-C30 halogenated hydrocarbon groups such as ethyl group and p-chlorophenyl group, cyanopropyl group, phenol group, hindered phenol group and the like. Monovalent hydrocarbon group, amino group-containing organic group, polyether group- containing organic group,
Although an epoxy group-containing organic group is exemplified, in the present invention, a saturated or unsaturated monovalent hydrocarbon having 1 to 18 carbon atoms is used.
Groups are preferred, and methyl groups, phenyl groups, and alkyl groups having 6 to 14 carbon atoms are particularly preferred.

From the viewpoint of the consistency required for the silicone grease composition, c is preferably in the range of 1.8 to 2.3, and particularly preferably in the range of 1.9 to 2.1. Also,
The viscosity at 25 ° C. of the organopolysiloxane used in the present invention is preferably 50 to 500,000 cs, and particularly preferably 100 to 10,000 cs. If it is lower than 50 cs, oil bleeding tends to occur when the grease composition is used, and if it is more than 500,000 cs, the extensibility when the grease composition is used becomes poor.

This organopolysiloxane is linear,
Any of a branched structure and a cyclic structure may be used. When using these, it is also necessary to use them alone.
Combinations of more than one species are also possible. c is in the range of 1.8 to 2.3, and particularly preferably in the range of 1.9 to 2.1, which is linear or more linear.

Such organopolysiloxanes include:
Examples thereof include dimethylpolysiloxane, diethylpolysiloxane, methylphenylpolysiloxane, polydimethyl-polydiphenylsiloxane copolymer, and alkyl-modified methylpolysiloxane. Particularly, the molecular chain ends are blocked with a trimethylsilyl group or a dimethylhydrosilyl group. Further, a homopolymer or copolymer of dimethylsiloxane, alkylmethylsiloxane, methylphenylsiloxane or diphenylsiloxane is preferred.

Examples of such an organopolysiloxane include those represented by the following chemical formula 1.

Embedded image

R ^{1 in} Chemical Formula ¹ is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group or an octyl group; an alkenyl group such as a vinyl group or an allyl group; an aryl group such as a phenyl group or a tolyl group. A chloromethyl group in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with halogen atoms, cyano groups, hydroxyl groups, etc.
It is a group selected from unsubstituted or substituted monovalent hydrocarbon groups having 1 to 30 carbon atoms such as a 3,3,3-trifluoropropyl group, a cyanopropyl group, a phenol group and a hindered phenol group.

R ² and R ³ are the same or different.
In valent organic group, the same monovalent hydrocarbon group as R ^1, an amino group-containing organic group, a polyether group-containing organic group and a group selected from an epoxy group-containing organic group,, R ⁴ is a hydrogen atom, the same as R ¹ A group selected from the same monovalent organic group as R ² or R ³ which is a monovalent hydrocarbon group, and a hydroxyl group;
Means that the polysiloxane is 50-500,00 at 25 ° C.
It is a positive number that becomes 0cs.

The organopolysiloxane used in the present invention is preferably one whose molecular chain end is blocked with a trimethylsilyl group. For the above R ^{1 to} R ³ , the simplicity of synthesis and the oil In terms of heat resistance and electrical insulation, alkyl groups such as methyl and ethyl groups, aryl groups such as phenyl and tolyl groups, and some of the hydrogen atoms bonded to carbon atoms of these groups were substituted with hydroxyl groups. Groups and the like are preferable, and a methyl group, a phenyl group, and an alkyl group having 6 to 14 carbon atoms are particularly preferable.

Such an organopolysiloxane oil may be produced by a conventionally known method. For example, a dimethylpolysiloxane oil is produced by a low-molecular cyclic siloxane such as octamethylcyclotetrasiloxane or decamethylcyclopentasiloxane. An acid catalyst such as sulfuric acid, chlorosulfonic acid, nitric acid, phosphoric acid, activated clay, acid clay, trifluoroacetic acid, or potassium hydroxide,
It may be carried out by a method in which a ring opening reaction is carried out in the presence of an alkaline catalyst such as sodium hydroxide, rubidium hydroxide, cesium hydroxide, potassium oxide, potassium acetate, calcium silanolate and the like, followed by polymerization.

In this case, in order to obtain a dimethylpolysiloxane having a desired viscosity by controlling the degree of polymerization of the obtained dimethylpolysiloxane, it is necessary to prepare hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane during the above polymerization. A low molecular weight siloxane having a terminal blocking group such as siloxane may be appropriately added.

The above-mentioned organopolysiloxane containing a carbon functional group, for example, an amino group-containing organopolysiloxane can be used to remove an organopolysiloxane containing at least one silanol group from an amino group-containing alkoxysilane. It may be synthesized by an alcohol condensation reaction,
Epoxy group or polyether group-containing organopolysiloxane is a compound containing an epoxy group or polyether group and an unsaturated group such as vinyl in the same molecule in the same molecule as an organohydrogenpolysiloxane containing a hydrogen atom bonded to a silicon atom. It may be synthesized by performing an addition reaction using siloxane and a platinum catalyst.

As the substituted monovalent hydrocarbon group for R ¹ , for example, from the viewpoint of improving heat resistance,
It may be a monovalent organic group having a hindered phenol structure described in No. 692. The organopolysiloxane in this case is exemplified by the following chemical formula 2, but it is a matter of course that the present invention is not limited thereto.

Embedded image

As R ⁵ in the above formula 2, for example, -C _{4
H 9, -C 6 H 13,} -C 8 H 17, -C 10 H 21, -C
_{12 H 25, -C 15 H 31} , -C 18 H 37 are exemplified, ^{R 6} is -
(CH ₂ ) _s -Q. S is a number from 1 to 6;
Is a group selected from monovalent organic groups having a hindered phenol structure exemplified in Chemical Formula 3 below.

Embedded image

R ⁷ is a 2-phenylethyl or 2-phenylpropyl group, and m, n, p, q and r are respectively 0 ≦ m ≦ 1,000, 0 ≦ n ≦ 100, 0 ≦ p ≤
1,000, 0 ≦ q ≦ 1,000, 0 ≦ r ≦ 2,000
0, 5 ≦ m + n + p + q + r ≦ 2,000. However, since the organopolysiloxane oil obtained by these methods is an equilibrium mixture of polysiloxanes of various degrees of polymerization generated in the synthesis process, usually, low-molecular-weight siloxane having siloxane units of 12 or less is close to 10%. Is also contained.

From the organopolysiloxane oil produced by the above-mentioned method, usually 120 to 25
Strip at a temperature of 0 ° C. to remove the low molecular siloxane. However, such a treatment still leaves 500 to 20,000 ppm of low molecular siloxane. Further, such a low-molecular siloxane has a higher adsorptivity than a non-polar flammable gas, and is volatilized and adsorbed on various electric contact parts.

The adsorbed low-molecular siloxane is oxidized to SiO ₂ .nH ₂ O and further becomes αSiO ₂ and deposits on the surface, causing contact troubles. Have been. It is also known that such a trouble can be prevented by setting the content of such low-molecular siloxane having a siloxane unit of 12 or less to 50 ppm or less, respectively.

Accordingly, the removal of the low-molecular siloxane is carried out by stripping the organopolysiloxane oil produced by the above method under a reduced pressure of 50 mmHg or less at a high temperature of 150 to 300 ° C. in a dry nitrogen gas atmosphere. Alternatively, it may be carried out by extracting the low molecular siloxane contained in the organopolysiloxane oil with an alcohol or ketone solvent. For the organopolysiloxane oil thus produced, the content of each low-molecular-weight siloxane contained was 5
0 ppm or less, and the siloxane unit is 2 to 2 ppm.
The total amount of all low molecular weight siloxanes of 12 is also 500p
pm or less.

The viscosity of the liquid silicone used in the present invention is, as described above, at 25 ° C. from the viewpoint of consistency and dispensing properties required for the silicone grease composition.
It is preferably 50 to 500,000 cs, and particularly preferably 100 to 100,000 cs. If the amount of the above liquid silicone is less than 5% by weight, it does not become grease-like and has poor extensibility, and if it exceeds 50% by weight, thermal conductivity is poor.
It is preferably in the range of 50% by weight, particularly preferably in the range of 7 to 30% by weight.

The characteristics required as the base oil of the liquid hydrocarbon oil or the fluorohydrocarbon oil used as the base oil of the component B in the present invention are as follows. It has appropriate viscosity characteristics, has little change in viscosity with temperature, and has a low solidification temperature (pour point). Low evaporability at high temperature and high flash point. Good oxidation stability and thermal stability. That is, the antioxidant is effective, and does not cause discoloration or deterioration even when heated to around 200 ° C. during production. Good oiliness. The influence on the surrounding materials is small, and the sealing material, resin or ceramic cover, etc. should not be deteriorated. Good affinity for filler (toner).

Examples of those having the above characteristics and usable in the present invention include naphthenic mineral oils and paraffinic mineral oils in mineral oils generally used as lubricating base oils. In applications such as greases used, other than silicone-based synthetic oils such as methyl-based silicone oil and phenyl-based silicone oil, synthetic oils that have better fluidity, viscosity index, and thermal stability than mineral oils are used as base oils. be able to.

Mineral oils and synthetic oils that can be used as such base oils include paraffinic oils, naphthenic oils, α-
Olefin oligomer (poly-α-olefin), polybutene (polyisobutylene), polyalkylene glycol (polyglycol, polyether, polyalkylene oxide), diester (dibasic acid ester), polyol ester (neopentyl polyol ester, hindered ester) ), Phosphate esters (phosphate esters), chlorofluorocarbons, fluoroesters,
Fluorine compounds such as perfluoroalkyl ethers (fluoropolyglycol, perfluoropolyether, polyperfluoroalkyl ether), and polyphenyl ethers are exemplified.

The α-olefin oligomer as a synthetic oil is generally represented by the following chemical formula 4, polybutene (polyisobrylene) is represented by chemical formula 5, alkylbenzene is represented by chemical formula 6, and polyalkylene glycol is represented by chemical formula 7.

Embedded image

Embedded image

Embedded image R and R ': _C10-18 alkyl groups

Embedded image R and R ″ in Chemical Formula 7 are a hydrogen atom or a C _1-20 alkyl group, R ′ is a hydrogen atom or a methyl group, and n is 5
~ 100. It is to be noted that in Chemical Formula 7, R and R ″ are generally polyethylene glycol or polypropylene glycol of H or CH ₃ , and may be a copolymer of both. Is a number.

The diester (dibasic acid ester) is generally 2ROH + HOOCR'COOH → ROOC
It is synthesized by an esterification reaction between an alcohol and a dibasic acid such as R′COOR + 2H ₂ O. Where R is H
Or a C4-18 alkyl group, wherein R 'is C4-18
Is an alkylene group.

The starting dibasic acid is HOOC (CH ₂ ) _n C
OOH is common, and examples are n = 4 adipic acid, n = 7 azelaic acid, n = 8 sebacic acid, and n = 10 dodecanedioic acid. As the alcohol, a primary alcohol in which the number of carbon atoms is having a side chain with 7-13 amino are used, 2-ethylhexanol C _8, isodecanol of C _10, such as tridecanol of C ₁₃ is illustrated .

Various diesters can be obtained by combining these acids and alcohols. Specifically, diisodecyl phthalate, di-2-ethylhexyl phthalate, dibutyl phthalate, diisodecyl adipate, diisononyl adipate, diisobutyl adipate,

Ester of mixed acid with 2-ethylhexanol, di-2-hexyl sebacate, dibutyl sebacate, di-2-ethylhexyl azelate, di-n-hexyl azelate, di-2-hexyl decanoate, di-2-hexyl sebacate Butoxyethoxyethyl adipate and the like.

Also, neopentyl polyol ester,
The polyol ester such as a hindered ester refers to an ester of a polyhydric alcohol such as neopentyl polyol and a monobasic fatty acid. As a raw material polyhydric alcohol,
Neopentyl polyol and the like, which are produced in large quantities as raw materials for alkyd resins and surfactants, are used. Specifically, neopentyl glycol (NPG), trimethylolpropane (TMP), trimethylolethane (TM
E), pentaerythritol (PE), dipentaerythritol (DPE) and the like.

As the carboxylic acid as the monobasic fatty acid, a linear or branched carboxylic acid having C ₃ -C ₁₃ is used. Specific examples thereof include linear as the C ₉ acid represented by the following formula 8, branched, neopentyl branched type are exemplified.

Embedded image Various polyol esters can be synthesized by combining these raw materials. In particular, an ester of a neopentyl-type acid and a neopentyl-type alcohol is preferable because of its high thermal stability.

For example, di (isooctyl) azelate synthesized from a normal alcohol and a normal acid as raw materials, bis (2,2-dimethyloctyl) azelate synthesized from a neopentyl alcohol and a normal acid as raw materials, and
Bis ( 2,2-dimethylpentyl) 2,2,2 synthesized from neopentyl alcohol and neopentyl acid
Comparing 8,8-tetraethyl azelate, it is known that the last neopentyl type combination has high stability against thermal decomposition.

The phosphoric acid ester is an ester of phosphoric acid, which is an inorganic acid, and phenol or alcohol. Since triphenyl phosphate is solid at normal temperature, it is generally used to make phenol into a liquid form using phenol with an alkyl side chain. Such phenyl esters include tricresyl phosphate (TCP),
Trixylenyl phosphate, tripropyl phenyl phosphate, tributyl phenyl phosphate and the like can be mentioned. Examples of the alkyl phosphate include tributyl phosphate (TBP) and tri-2-ethylhexyl phosphate (TOP).

The chlorofluorocarbon has a structure in which hydrogen of n-paraffin is replaced by fluorine and chlorine.
Specifically, it is obtained by low polymerization of chlorotrifluoroethylene, and can be made from a material having a small viscosity to a material having a large viscosity depending on the degree of polymerization. Generally, it is represented by the following chemical formula 9.

Embedded image

[0054] As the fluoro ester or esters of perfluoro alcohol and sebacic acid C _7, and pyromellitic acid or esters of camphor acid and perfluoro alcohol. The perfluoroalkyl ether is generally represented by the following chemical formula (10) or (11), and can be prepared from a material having a small viscosity to a material having a large viscosity depending on the degree of polymerization.

[0055]

Embedded image Rf is CF ₃ or _C 2 _{F 5,} n is a number of 5 to 60.

Embedded image Rf is CF ₃ or C ₂ F ₅ and m and n are m + n
Is a positive number from 5 to 60, and m and n may be the same or different.

The viscosity of the liquid hydrocarbon oil and / or fluorinated hydrocarbon oil used in the present invention is preferably 2 from the viewpoint of the consistency and dispensability required for the thermally conductive grease composition.
It is preferably 50 to 500,000 cs at 5 ° C., particularly preferably 100 to 100,000 cs.

The thickener used in the component C in the present invention needs to have a high thermal conductivity, and at least one inorganic compound powder selected from zinc oxide, alumina, boron nitride and silicon carbide Can be used.
The surface of these inorganic compound powders may be subjected to a hydrophobic treatment with an organosilane, an organosilazane, an organopolysiloxane, an organic fluorine compound, or the like, if necessary. If these thickeners are used in an amount of more than 30% by weight, the resulting grease composition will have poor extensibility. Therefore, it is preferable to use the grease composition in the range of 0 to 30% by weight, especially 0 to 15% by weight. It is preferable to use it in the range of weight%.

The zinc oxide used in the present invention is generally called zinc white (Zinc White), and is a white powder having a hexagonal or wurtzite crystal structure. In general, such a method of producing zinc oxide includes an indirect method of oxidizing zinc vapor generated by heating metallic zinc to 1000 ° C. with hot air, and a method of producing zinc oxide obtained by cultivating zinc ore into coal or the like. And the resulting zinc vapor is oxidized by hot air, or zinc ore leached with sulfuric acid and slag added with coke etc. is heated in an electric furnace to evaporate the zinc, The direct method of oxidizing with air is known.

In either method, the produced zinc oxide is cooled through an air cooler using a blower, and is separated according to the size of the particles. As another production method, there is a wet method in which an alkali carbonate solution is added to a zinc salt solution, and the precipitated basic zinc carbonate is cultivated. The zinc oxide powder produced by such a method is compliant with Japanese Industrial Standard JIS K14.
10 and JIS K5102 and American Standard AS
Specified in TM-D79. In the present invention, any zinc oxide produced by the above-described production method can be used, and a mixture of different production methods may be used.

Zinc oxide powder is mainly used as a rubber vulcanization accelerator, and is used in the fields of paints, ceramics, enamels, glass, ferrites, cosmetics, pharmaceuticals, and the like. It is also known to be used as a thermal conductivity imparting filler (Japanese Patent Laid-Open No.
-55870, JP-A-54-116055, JP-A-55
-45770, JP-A-56-28264, JP-A-61-1986
157587, JP-A-2-221556, JP-A-3-1
62493, JP-A-4-202496).

As the zinc oxide powder used in the present invention, those having an average particle size of 0.2 to 5 μm can be used, but from the viewpoint of the dispersibility of the component B in the base oil and the relationship with the aluminum nitride powder. Those having an average particle size of 0.3 to 4 μm are preferred, and those having an average particle size of 0.3 to 3 μm are particularly preferred. By doing so, the degree of oil separation of the obtained thermally conductive grease can be made 0.01% or less. The hardness is preferably 4 to 5 in Mohs hardness.

As the thermal conductivity imparting filler in the present invention
Has the chemical formula Al ₂O₃Acid represented by
Aluminum fluoride powder, which
Generally, alumina (alumina), α-alumina (α-alumina)
a), alumina single crystal fine particles (Single crystal corund
um fines) and spherical alumina (Spherical Alumina)
What are variously referred to as the like can be used.

In general, an industrial production method of alumina is a method called a Bayer method in which bauxite as a raw material is treated with hot caustic soda, and this method is a method of once producing aluminum hydroxide (Al (OH) ₃ ). Crystals are formed and are fired at a high temperature in a rotary kiln or the like to obtain alumina. Alumina is widely used in various refractories, abrasives, porcelain, white-filled pigments, catalysts, etc. because of its excellent thermal, mechanical and physicochemical properties.

The alumina powder is generally hexagonal or hexagonal
Α-Al having a planar lattice crystal structure ₂O₃And the appearance is white
Color powder, apparent particle size of 20-80μm on average
Each particle is a primary crystal of about 0.5 to 20 μm
It is composed of alumina and can be used according to each application.
Various grades of alumina powder are made. In particular, the
The shape and size are uniform when a grease composition is used.
It has a subtle effect on properties such as properties and consistency.

The alumina powder that can be used in the present invention has an apparent average particle size of 20 to 80 μm in a wide range, but from the viewpoint of dispersibility in a base oil such as liquid silicone, the alumina powder has an average particle size of 30 to 50 μm. Are preferred, especially 30
It is preferably from 40 to 40 μm. Alumina is generally very hard, and has a Mohs hardness in the range of 8 to 9. In the present invention, any material within this range can be used.

The theoretical thermal conductivity of alumina is 27.2 W /
Although it is mK, the measured value is usually smaller than the theoretical value because the produced alumina powder contains some impurities and contains voids and bubbles in the powder. The alumina powder used in the present invention has a thermal conductivity of 5 at room temperature.
It is preferably at least 0 W / mK. Thermal conductivity is 5.
This is because if it is less than 0 W / mK, high thermal conductivity cannot be obtained when grease or sheet is used.

The boron nitride powder used as the component C in the present invention is obtained by heating boric acid or borate together with a nitrogen-containing organic substance or a nitrogen compound such as ammonia to form an overlapping crystal structure similar to graphite in a hexagonal network. As a hexagonal boron nitride powder. Hexagonal boron nitride powder has excellent lubricating properties up to high temperatures, high electrical conductivity, high thermal conductivity, and is chemically stable and hardly wet by molten metal or glass. Used for conductive insulating fillers, solid lubricants, fillers for resin modification, etc.

The boron nitride powder having such a hexagonal crystal structure has a white appearance and an average particle size of 1 to 10 μm. In the present invention, those having a wide range of the above average particle size of 1 to 10 μm can be used, but it is preferably 1 to 5 μm from the viewpoint of dispersibility of the B component in base oil, prevention of oil separation, and the like. Further, boron nitride powder having a hexagonal crystal structure is generally soft. In the present invention, those having a Mohs hardness in the range of 1 to 3 can be used, but those having a Mohs hardness of about 2 are particularly preferable.

The theoretical thermal conductivity of boron nitride is 6 at room temperature.
Although it is 0.3 W / mK, the actual measured value is usually smaller than the theoretical value because the produced boron nitride powder contains some impurities and contains voids and bubbles in the powder. The boron nitride powder used in the present invention preferably has a thermal conductivity at room temperature of 5.0 W / mK or more. If the thermal conductivity is 5.0 W / mK or less, high thermal conductivity cannot be obtained when grease is used.

The above hexagonal boron nitride (Hexa
Gonal Boron Nitride) is treated as a raw material under high-temperature and high-pressure to convert it into cubic boron nitride (Cubic Boron Nitride) with the same structural principle as diamond. Such boron nitride powder having a cubic crystal structure has hardness next to diamond, is a brownish-black powder, and is commercially available in a particle size range of several μm to 800 μm. In the present invention, such cubic boron nitride can be used. However, the thermal conductivity of this cubic boron nitride powder is as low as 0.5 to 3.6 W / mK. It is not preferable from the viewpoint of obtaining good thermal conductivity, which is one of the objects.

Next, silicon carbide powder to be used as the C component is composed of silica and coke as main raw materials, and a high-purity α-SiC ingot synthesized in an electric furnace (Acheson furnace) is pulverized, decarburized, and iron-removed. , Made through the classification process. Depending on the intended use, ultra-fine powdered silicon carbide (Ultra Fine Silicon Carbide Powder) with various particle size distributions.

Regarding the particle size and particle size distribution of silicon carbide, JIS R6001, JIS R6002, and
Specified by IS R6124. The silicon carbide powder that can be used in the present invention has an average particle size of 0.4
Although it is a wide range of from 10 to 10 μm, from the viewpoint of dispersibility of the component B in the base oil and prevention of oil separation, etc.
It is preferably 5 μm. The silicon carbide powder has a blue-black appearance, a triangular prism crystal structure, and is generally hard. In the present invention, those having a Mohs hardness in the range of 8 to 9 can be used.

The theoretical thermal conductivity of silicon carbide is 10 at room temperature.
Although it is 0.4 W / mK, the measured value is usually smaller than the theoretical value because the produced silicon carbide powder contains some impurities and contains voids and bubbles in the powder. The silicon carbide powder used in the present invention preferably has a thermal conductivity at room temperature of 5.0 W / mK or more.
When the thermal conductivity is 5.0 W / mK or less, high thermal conductivity cannot be obtained when grease or a sheet is used.

To produce the grease composition of the present invention,
Among the above components, at least the A component and the B component are a trimix, a twin mix, a planetary mixer (all are registered trademarks of a mixer manufactured by Inoue Seisakusho Co., Ltd.), an ultra mixer (a mixer manufactured by Mizuho Industry Co., Ltd.) And Hibis Dispermix (registered trademark of a mixer manufactured by Tokushu Kika Kogyo Co., Ltd.).
If necessary, you may heat to 50-150 degreeC. In addition, after mixing, it is preferable to further perform a kneading operation under a high shear force for uniform finishing. Examples of the kneading apparatus include a three-roll mill, a colloid mill, and a sand grinder.
The method using this roll is preferred.

[0075]

According to the silicone grease composition of the present invention obtained as described above, a significant improvement in water resistance is observed, and the silicone grease composition exhibits stable hardness (consistency) and thermal conductivity over a long period of time. Can be done.

[0076]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
The moisture resistance was evaluated by leaving the silicone grease composition in a thermo-hygrostat at 40 ° C. and 95% humidity, and after one day,
The measurement was performed by measuring the consistency and the thermal conductivity after 7 days and 1 month. If the moisture resistance is maintained, the consistency and the thermal conductivity hardly change because the aluminum nitride does not change with time. Also, the measurement of the consistency is based on JIS K2220.
It went according to. The viscosities in the examples are values at 25 ° C.

Preparation Example 1 As shown in Table 1, C₁₀H
₂₁Si (OCH₃)₃10 g of organosilane
Aluminum fluoride powder (amorphous, average particle size 2.0 μm,
Specific surface area 4.0m ²/ G) 1000 g in 5 liter
Into a planetary mixer (manufactured by Inoue Manufacturing Co., Ltd.)
Stir and mix at room temperature for 30 minutes to obtain component (A-1).
A surface-treated aluminum nitride powder was obtained.

[0078]

[Table 1]

Preparation Examples 2 to 4. C ₁₀ H ₂₁ Si (OCH
₃ ) A surface-treated aluminum nitride powder as a component (A-2 to 4) was obtained in exactly the same manner as in Preparation Example 1 except that the mixing amounts of the organosilane and the aluminum nitride powder in ₃ were as shown in Table 1. Was.

Preparation Examples 5 to 8 As shown in Table 1, the organosilane of C ₁₀ H ₂₁ Si (OCH ₃ ) ₃ used in Preparation Example 1 was replaced with C ₁₂ H ₂₅ Si (OC), respectively.
H ₃ ) ₃ , C ₆ H ₁₃ Si (OCH ₃ ) ₃ , C ₁₀ H
₂₁ Si (CH ₃ ) (OCH ₃ ) ₃ and CH ₃ Si (O
A surface-treated aluminum nitride powder as a component (A-5 to 8) was obtained in exactly the same manner as in Preparation Example 1, except that the organosilane was CH ₃ ) ₃ .

Examples 1 to 11 and Comparative Examples 1 to 4. Table 2,
Each component having the compounding amount (parts by weight) shown in Table 3 was put into a 5 liter planetary mixer (registered trademark of a mixer manufactured by Inoue Seisakusho Co., Ltd.) and stirred at room temperature for 30 minutes.
The kneading with this roll was performed three times to produce silicone greases of Examples 1 to 11 and Comparative Examples 1 to 4.

[0082]

[Table 2]

[0083]

[Table 3]

However, B-1, B-2, C-1 and C-2 in the table are as follows. B-1: Viscosity 390cs B-2: Viscosity 500cs C-1: Zinc oxide powder (Amorphous, average particle size: 0.2-5
μm) C-2: alumina powder (amorphous, average particle size: 30 to 50)
μm)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C10M 107/38 C10M 107/38 107/50 107/50 113/00 113/00 113/08 113/08 // C10N 10:04 10:06 20:02 30:00 50:10 60:00 (72) Inventor Kenichi Isobe 1-10, Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Inside Silicon Electronic Materials Research Laboratory Shin-Etsu Chemical Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) C10M 101/00-177/00 C10N 10:00-80:00

Claims (6)

(57) [Claims] 1. A) The general formula R ¹ _a R ² _b SiY _4-ab
And 50 to 95% by weight of aluminum nitride powder surface-treated with an organosilane and / or a partially hydrolyzed condensate thereof represented by the following formula: A thermally conductive grease composition comprising from 5 to 50% by weight of at least one selected base oil; wherein R ¹ in the above formula is
An alkyl group having 6 to 20 carbon atoms, or a group in which part or all of the hydrogen atoms bonded to the carbon atoms of the group are substituted with halogen atoms, R ² is a hydrocarbon group having 1 to 20 carbon atoms, or A group in which part or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, Y is a hydrolyzable group, a is an integer of 1 to 3, b is an integer of 0 to 2, a + b
Is an integer of 1 to 3. 2. Component B) has the general formula R ⁴ _c SiO
_The thermally conductive grease composition according to claim 1, which is an organopolysiloxane represented by _{(4-c) / 2} and having a viscosity at 25C of 50 to 500,000 cs;
However, R ⁴ in the above formula is a saturated or unsaturated monovalent hydrocarbon group having 1 to 30 carbon atoms, an amino group-containing organic group, a polyether group-containing organic group, and an epoxy group-containing organic group. One or more groups selected from the group consisting of c
Is a number satisfying 1.8 ≦ c ≦ 2.3. 3. The liquid hydrocarbon oil is at least one selected from paraffinic oil, naphthenic oil, α-olefin oligomer, polybutene, polyalkylene glycol, diester, polyol ester and phosphate ester. 2. The thermally conductive grease composition according to 1. 4. A liquid hydrocarbon oil having a viscosity of 50 to 5 at 25 ° C.
4. The thermally conductive grease composition according to claim 1, wherein the composition is 000 cs. 5. The fluorinated hydrocarbon oil is at least one selected from polychlorotrifluoroethylene, fluoroester, and polyperfluoroalkyl ether.
The heat conductive grease composition according to claim 1. 6. The method according to claim 1, wherein the component (C) contains at least one thickener selected from zinc oxide, alumina, boron nitride and silicon carbide in an amount of not more than 30% by weight.
6. The thermally conductive grease composition described in any one of items 1 to 5.