JP2000063872A - Thermal conductive grease composition - Google Patents

Abstract

(57) [Problem] To provide 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-conducting grease composition having excellent moisture resistance and suitable as a heat-generating material for electronic parts.

[0002]

BACKGROUND OF THE INVENTION Many electronic components generate heat during use and it is necessary to remove heat from the electronic components in order for them 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 parts. In this case, there are various uses such as a molded product or a filler of grease or synthetic rubber.

However, aluminum nitride is poor in water resistance, and particularly in the case of powder, it is gradually decomposed even when left in the air, and ammonia is generated to change into aluminum hydroxide. Therefore, when the aluminum nitride powder is used as a filler for increasing the heat dissipation of the resin, poor water resistance becomes a problem.

Therefore, in order to improve the water resistance of aluminum nitride, the surface of aluminum nitride powder is coated with an organic polymer or the surface of aluminum nitride powder is oxidized to form an aluminum oxide layer, which is used as a protective film. Attempts have been made to do so. Further, Japanese Patent Laid-Open No. 4-32150
Japanese Unexamined Patent Publication (Kokai) No. 6 proposes a technique for coating the surface of an aluminum nitride powder by reacting an organosilane oligomer with a polyorganosiloxane having a silanol group using a catalyst.

However, the water resistance of aluminum nitride could not be made sufficient by any of these methods. Therefore, when these aluminum nitrides are used in a heat dissipation silicone grease composition, there is a drawback that the heat dissipation characteristics of the silicone grease composition gradually deteriorate.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a heat dissipating grease composition having excellent water resistance despite using aluminum nitride powder as a filler.

[0007]

The above objects of the present invention are as follows.
A) Aluminum nitride powder 50 to 95 which is surface-treated with an organosilane represented by the general formula R ¹ _a R ² _b SiY _4-ab and / or a partial hydrolysis-condensation product thereof.
%, And B) 5-50% by weight of at least one base oil selected from liquid silicones, liquid hydrocarbon oils and fluorohydrocarbon oils. Achieved by R;
¹ is an alkyl group having 6 to 20 carbon atoms, or a group in which a part or all of hydrogen atoms bonded to carbon atoms of this group are substituted with halogen atoms, and R ² is a hydrocarbon having 1 to 20 carbon atoms. Group, or a group in which a part or all of 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 1-3.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The alkyl group represented by R ¹ in the general formula R ¹ _a R ² _b SiY _4-a-b of the organosilane used as the surface treating agent for the aluminum nitride of 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 is an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group,
And aralkyl groups and the like. Specific examples of R ² include, for example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group and pentyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group and allyl group. An aryl group such as a phenyl group and a tolyl group; an aralkyl group such as a 2-phenylethyl group and a 2-methyl-2-phenylethyl group; a 3,3,3-trifluoropropyl group, 2- (perfluorobutyl) ethyl Base, 2
Examples thereof include halogenated hydrocarbon groups such as-(perfluorooctyl) ethyl group and p-chlorophenyl group, with methyl group being particularly preferable.

As Y which is a hydrolyzable group, 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 can be mentioned, and specific examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an acetoxy group, A propenoxy group etc. are mentioned. Of these, a hydroxyl group and an alkoxy group are particularly preferable in the present invention.

Component of organosilane represented by the above general formula
The following can be mentioned as a body example. C₆H_ThirteenSi (OCH_Three)_Three, C₁₀H₂₁Si (O
CH_Three)_Three, C₁₂H_{Two 5}Si (OCH_Three)_Three, C₁₆
H₃₃Si (OCH_Three)_Three, C₁₀H₂₁Si (C
H_Three) (OCH_Three)_Two, C₁₀H₂₁Si (C₆H₅)
(OCH_Three)_Two, C₆H_ThirteenSi (COCH_Three)_Three, C
₁₀H₂₁Si (CH_Three) (COCH_Three)_Two, C₆H
_ThirteenSi (CH_TwoCH_TwoC₆H₅) (OH)_Two, C₆H
_ThirteenSi (OH) _Three, C₁₀H₂₁Si (CH = C
H_Two) (OCH_Three)_Two, C₁₀H₂₁Si (CH_TwoCH
_TwoCF_Three) (OCH_Three)_Two, C_FourF₉CH_TwoCH_TwoSi
(OH)_Three, (C_FourF₉CH_TwoCH_Two)_TwoSi (OCH
_Three)_Two, C₈F₁₇Si (OCH_Three)_Three, C₈F₁₇S
i (COC_TwoH₅)_Three

The amount of the organosilane used is preferably 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 it is less than 0.1 part by weight, the water resistance of the treated aluminum nitride will be insufficient, and if it is more than 30 parts by weight, the effect will not increase and it will be uneconomical. Further, if 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 will have poor heat dissipation properties,
When the amount is more than 95% by weight, the finished grease has poor developability. Therefore, it 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 III-V group nitride, and the appearance is white to grayish white, and the particle shape is an irregular to spherical powder, depending on the manufacturing method. As the aluminum nitride powder used in the present invention, a wide range of average particle diameters of 0.1 to 100 μm can be used, but in order to obtain a uniform grease composition, 1 to 10 can be used.
It is preferably 0 μm, and particularly preferably 2 to 5 μm. Further, those having a specific surface area in the range of 0.1 to 100 m ² / g can be used, and in order to obtain a uniform grease composition, those having a specific surface area of 1 to 100 m ² / g are preferable, and particularly ^{2 to 5} m ² / g. Is preferred.

As a method for producing the aluminum nitride powder as a raw material before the surface treatment, a direct nitriding method in which a metal aluminum powder is directly reacted with nitrogen or ammonia, 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. Properties such as chemical composition (impurity), particle shape, and particle size distribution vary depending on the manufacturing method, but the aluminum nitride powder used in the present invention can be used by any manufacturing method. You may mix and use the thing of a different manufacturing method.

The aluminum nitride powder thus obtained is extremely hard and has excellent thermal conductivity, electrical insulation and mechanical strength. In the present invention, any Mohs hardness in the range of 7 to 9 can be used, but it is 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, 1 to 4 μm is preferable, and 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, it becomes a grease with low consistency (hard and poor in dispenseability).
Not preferable 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 the base oil is severely separated (great oil separation). Therefore, naturally, good grease cannot be obtained.

The theoretical thermal conductivity of aluminum nitride is 7.
Although it is 7 × 10 ⁻¹ cal / cm · sec · ° C., the manufactured aluminum nitride powder usually contains some impurities and contains voids and bubbles. Is smaller than the theoretical value, 6.0 × 10 ^-1 cal /
It is below cm · sec · ° C. 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 1 / cm · second · ° C. or higher, and particularly 2.
It is preferably 4 × 10 ⁻¹ cal / cm · sec · ° C. or higher. Thermal conductivity is 1.5 × 10 ^-1 cal / cm · sec · ° C
With the following, when the grease or the sheet is used, the high thermal conductivity which is the object of the present invention cannot be obtained.

The aluminum nitride that can be used in the present invention is manufactured by Toyo Aluminum Co., Ltd. under the trade name of US,
UF and UM, product 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, product names of Advanced Refractory Technologies, Inc. (Advanced Refractory Technologies. Inc), A-100WR, A-100, AG-SD and the like.

The surface treatment method 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 trimixed,
Twin Mix, Planetary Mixer (both are registered trademarks of Inoue Seisakusho Co., Ltd.), Ultra Mixer (Mizuho Kogyo Co., Ltd. mixer), Hibis Disbar Mix (Tokuseki Kika Kogyo Co., Ltd.) Mix with a mixer such as a registered trademark of a mixer).

When mixing, if necessary, 50 to 150
It may be heated to ℃. In addition, a diluting solvent such as toluene, xylene, petroleum ether, mineral spirits, 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, as the diluting solvent, the base oil of component B which is the liquid component used in the present invention. In this case, the treating agent organosilane or its partial hydrolyzate may be mixed with the base oil in advance, and aluminum nitride powder may be added thereto to perform the treatment and the mixing at the same time. Compositions made by this method are also included in the invention.

The liquid silicone used as the base oil of the component B is a known silicone which is liquid at room temperature, such as polyorganosiloxane and polyorganosylalkylene.
Although it can be appropriately selected from polyorganosilane and copolymers thereof, etc., from the viewpoint of heat resistance, stability, electrical insulation, etc., polyorganosiloxane is preferable,
In particular, the organopolysiloxane represented by the general formula R ⁴ _c SiO 2 _{(4-c) / 2} is preferable. In the above formula, R ⁴
Is at least 1 selected from the group consisting of saturated or unsaturated monovalent hydrocarbon groups having 1 to 18 carbon atoms.
It is the basis of seeds. All R ⁴ may be the same or different from each other.

Examples of such a group include a methyl group,
Alkyl groups such as ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group; vinyl group , An alkenyl group such as an allyl group; an aryl group such as a phenyl group and a tolyl group; an aralkyl group such as a 2-phenylethyl group and a 2-methyl-2-phenylethyl group; or a hydrogen bonded to a carbon atom of these groups. Chlormethyl group, 3,3,3-trifluoropropyl group, 2- (perfluorobutyl) ethyl group, 2-, in which some or all of the atoms are substituted with halogen atom, cyano group, hydroxyl group, etc.
(Perfluorooctyl) ethyl group, halogenated hydrocarbon group such as p-chlorophenyl group, cyanopropyl group, phenol group, hindered phenol group and the like, which is the same or different, and is unsubstituted or substituted with 1 to 30 carbon atoms. Examples thereof include a monovalent hydrocarbon group, an amino group-containing organic group, a polyether-containing organic group, and an epoxy group-containing organic group. In the present invention, a methyl group, a phenyl group, and 6 to 6 carbon atoms are particularly preferable.
14 alkyl groups are preferred.

From the viewpoint of the consistency required of 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 of the organopolysiloxane used in the present invention at 25 ° C. is preferably 50 to 500,000 cs, and particularly preferably 100 to 10,000 cs. When it is less than 50 cs, oil bleeding tends to occur when it is made into a grease composition, and when it is more than 500,000 cs, the extensibility when made into a grease composition becomes poor.

The organopolysiloxane is a straight chain,
It may have either a branched structure or a cyclic structure. In addition, when using these, they can be used alone.
Combinations of more than one species are also possible. Although a is 1.8 to 2.3, it is particularly preferably in the range of 1.9 to 2.1 which is linear or more linear.

As such an organopolysiloxane,
Examples thereof include dimethylpolysiloxane, diethylpolysiloxane, methylphenylpolysiloxane, polydimethyl-polydiphenylsiloxane copolymer, and alkyl-modified methylpolysiloxane. Particularly, the molecular chain end is blocked with a trimethylsilyl group or a dimethylhydrosilyl group. Further, a homopolymer or a copolymer of dimethylsiloxane, alkylmethylsiloxane, methylphenylsiloxane or diphenylsiloxane is preferable.

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

[Chemical 1]

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 such as a phenyl group or a tolyl group. Group, a part or all of the hydrogen atoms bonded to carbon atoms of these groups are halogen atoms, cyano groups, chloromethyl groups substituted with a hydroxyl group,
It is a group selected from an unsubstituted or substituted monovalent hydrocarbon group 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 1
A monovalent hydrocarbon group which is the same as R ¹ and is selected from a monovalent hydrocarbon group, an amino group-containing organic group, a polyether group-containing organic group, and an epoxy group-containing organic group, R ⁴ is a hydrogen atom, the same as R ^1. The same monovalent organic group as R ² or R ³ which is a monovalent hydrocarbon group, and a group selected from a hydroxyl group, and 1 (el)
This polysiloxane is 50 to 500,000 at 25 ° C.
It is a positive number such that it becomes 0 cs.

The organopolysiloxane used in the present invention is preferably one in which the molecular chain end is blocked with a trimethylsilyl group, and the above R ^{1 to} R ³ are easy to synthesize and the oil obtained is From the viewpoints of heat resistance and electrical insulation, alkyl groups such as methyl and ethyl, aryl groups such as phenyl and tolyl, and some of the hydrogen atoms bonded to the carbon atoms of these groups were replaced with hydroxyl groups. A group 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, dimethylpolysiloxane oil is produced by a low molecular cyclic siloxane such as octamethylcyclotetrasiloxane or decamethylcyclopentasiloxane. Acid catalyst such as sulfuric acid, chlorosulfonic acid, nitric acid, phosphoric acid, activated clay, acid clay, trifluoroacetic acid, or potassium hydroxide,
The ring-opening reaction may be 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, hexamethyldisiloxane, octamethyltrisiloxane and decamethyltetrasiloxane are used during the above polymerization. A low molecular weight siloxane having a terminal blocking group such as siloxane may be added as appropriate.

Incidentally, the above-mentioned organopolysiloxane containing a carbon functional group, for example, an amino group-containing organopolysiloxane is a compound obtained by removing an organopolysiloxane containing one or more silanol groups and an amino group-containing alkoxysilane. It may be synthesized by an alcohol condensation reaction,
An 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, which is an organohydrogenpolysiloxane containing a hydrogen atom bonded to a silicon atom. It may be synthesized by addition reaction using a siloxane and a platinum catalyst.

The substituted monovalent hydrocarbon group for R ¹ is, for example, from the viewpoint of improving heat resistance, JP-B-3-131.
It may be a monovalent organic group having a hindered phenol structure described in No. 692. Examples of the organopolysiloxane in this case include those represented by the following chemical formula 2, but the present invention is not limited thereto.

[Chemical 2]

R ⁵ in the above Chemical formula 2 is, 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 -
Is a (CH _{2) s} -Q. Also, s is a number from 1 to 6, and Q
Is a group selected from monovalent organic groups having a hindered phenol structure exemplified in Chemical Formula 3 below.

[Chemical 3]

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

The organopolysiloxane oil produced by the above method is usually synthesized under reduced pressure of 120 to 25 after synthesis.
Strip at a temperature of 0 ° C. to remove the low molecular weight siloxane. However, such treatment still leaves 500-20,000 ppm of low-molecular-weight siloxane. Further, such low-molecular-weight siloxane has stronger adsorptivity than nonpolar combustible gas, and is volatilized and adsorbed on various electric contact parts and the like.

The adsorbed low-molecular-weight siloxane is oxidized to SiO ₂ .nH ₂ O, and further becomes αSiO ₂ , which is deposited on the surface and causes contact trouble. Therefore, it is conventionally known that its presence is not preferable. Has been. It is also known that such troubles can be prevented by setting the content of such low-molecular-weight siloxane having 12 or less siloxane units to 50 ppm or less.

Therefore, the removal of the low-molecular-weight siloxane is performed 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, the low-molecular-weight siloxane contained in the organopolysiloxane oil may be extracted with an alcohol-based or ketone-based solvent. Regarding the organopolysiloxane oil produced in this way, the content of each low-molecular siloxane contained is 5
It can be 0 ppm or less, and the siloxane unit is 2 to
The total amount of all 12 low molecular weight siloxanes is 500 p
It can be 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 property required for a 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-mentioned organopolysiloxane used is less than 5% by weight, it does not become a grease and has poor extensibility, and if it is more than 50% by weight, it has poor thermal conductivity. It is preferably in the range, and particularly preferably in the range of 7 to 30% by weight.

The characteristics required for 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 evaporation at high temperature and high flash point. Good oxidative and thermal stability. That is, the effect of the antioxidant is good, and it does not cause discoloration or deterioration even if it is heated to near 200 ° C during manufacturing. Good oiliness. It does not affect the surrounding materials and does not alter the quality of the sealing material, resin or ceramic cover. Good affinity for fillers (modifiers).

The naphthenic mineral oil or the paraffinic mineral oil in the mineral oil generally used as a lubricating base oil can be mentioned as those having the above-mentioned characteristics and usable in the present invention, but particularly over a wide temperature range. For applications such as grease used, in addition to silicone-based synthetic oils such as methyl-based silicone oils and phenyl-based silicone oils, synthetic oils with better fluidity, viscosity index, and heat 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) ), Phosphoric acid ester (phosphate ester), chlorofluorocarbon, fluoroester,
Examples thereof include fluorine compounds such as perfluoroalkyl ether (fluoropolyglycol, perfluoropolyether, polyperfluoroalkyl ether), polyphenyl ether and the like.

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

[Chemical 4]

[Chemical 5]

[Chemical 6] R and R ′: C _10-18 alkyl group

[Chemical 7] In the chemical formula 7, R and R ″ are a hydrogen atom or a C _1-20 alkyl group, R ′ is a hydrogen atom or a methyl group, and n is 5
Is a number from -100. In general, the chemical formula 7 is a polyethylene glycol or polypropylene glycol in which R and R ″ are H or CH ₃ , and may be a copolymer of both. N is 5 to 100. Is a number.

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

The starting dibasic acid is HOOC (CH ₂ ) _n C
OOH is common, and adipic acid with n = 4, azelaic acid with n = 7, sebacic acid with n = 8, and dodecanedioic acid with n = 10 are exemplified. As the alcohol, a primary alcohol having 7 to 13 carbon atoms and a side chain is used, and examples thereof include C ₈ 2-ethylhexanol, C ₁₀ isodecanol, and C ₁₃ tridecanol. .

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-ethylhexyl malate, tri-2-ethylhexyl trimellitate, acetyltributyl citrate,
Examples thereof include dibutoxyethoxyethyl adipate.

Further, neopentyl polyol ester,
The polyol ester such as hindered ester means an ester of polyhydric alcohol such as neopentyl polyol and monobasic fatty acid. As the raw material polyhydric alcohol,
Neopentyl polyol, etc., which are produced in large quantities, are used as raw materials for alkyd resins and surfactants. 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 a carbon number of C _{3 to} C ₁₃ is used. As a specific example, for example, as the C ₉ acid, a linear type, a branched type, and a neopentyl branched type represented by the following chemical formula 8 are exemplified.

[Chemical 8] Various polyol esters can be synthesized by combining these raw materials, and in particular, esters of neopentyl-type acid and neopentyl-type alcohol are preferable because they have high thermal stability.

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

The phosphoric acid ester is an ester of inorganic acid phosphoric acid and phenol or alcohol. Since triphenyl phosphate is a solid at room temperature, it is generally made into a liquid form by using phenol having an alkyl side chain. Examples of such phenyl ester include tricresyl phosphate (TCP),
Examples include trixylenyl phosphate, tripropylphenyl phosphate, tributylphenyl phosphate and the like. Examples of the alkyl phosphate ester include tributyl phosphate (TBP) and tri-2-ethylhexyl phosphate (TOP).

Chlorofluorocarbon has a structure in which hydrogen of n-paraffin is replaced with fluorine and chlorine.
Specifically, it is obtained by low-polymerization of chlorotrifluoroethylene, and depending on the degree of polymerization, it is possible to produce from low viscosity to high viscosity. Generally, it is represented by the following chemical formula 9.

[Chemical 9]

Examples of the fluoroester include C ₇ perfluoroalcohol ester with sebacic acid, pyromellitic acid with camphoric acid and perfluoroalcohol ester. The perfluoroalkyl ether is generally represented by the following chemical formula 10 or chemical formula 11, and it is possible to prepare perfluoroalkyl ether having a low viscosity to a high viscosity depending on the degree of polymerization.

[0055]

[Chemical 10] Rf is CF ₃ or _C 2 _{F 5,} n is a number of 5 to 60.

[Chemical 11] Rf is CF ₃ or C ₂ F ₅ , m and n are m + n
Is a positive number of 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 2 from the viewpoint of consistency and dispensing property required for the heat conductive grease composition.
It is preferably 50 to 500,000 cs at 5 ° C., and particularly preferably 100 to 100,000 cs.

The thickener used as the component C in the present invention is required to have 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 hydrophobizing treatment with an organosilane, an organosilazane, an organopolysiloxane, an organic fluorine compound or the like, if necessary. Further, if more than 30% by weight of these thickeners are used, the resulting grease composition will have poor extensibility, so it is preferable to use in the range of 0 to 30% by weight, particularly 0 to 15%. It is preferably used in the range of wt%.

The zinc oxide used in the present invention is generally called zinc white and is a white powder having a hexagonal or wurtzite crystal structure. In general, such a method for producing zinc oxide includes an indirect method in which zinc vapor generated by heating metallic zinc to 1000 ° C. is oxidized by hot air, and a zinc oxide obtained by calcination of zinc ore. The resulting zinc vapor is oxidized with hot air, or a zinc ore slag (slag) leached slag (coke) is heated in an electric furnace to vaporize the zinc. The direct method of oxidizing with air is known.

In any of the methods, the produced zinc oxide is cooled through an air cooler using a blower and fractionated according to the particle size. As another manufacturing method, there is a wet method in which an alkaline carbonate solution is added to a solution of a zinc salt and the precipitated basic zinc carbonate is baked. Zinc oxide powder produced by such a manufacturing method is manufactured according to Japanese Industrial Standard JIS K14.
10 and JIS K5102 and American standard AS
It is specified in TM-D79. In the present invention, any zinc oxide produced by the above-mentioned production method can be used, and different production methods may be mixed and used.

Zinc oxide powder is mainly used as a rubber vulcanization accelerator, and is also used in the fields of paint, ceramics, enamel, glass, ferrite, cosmetics, pharmaceuticals, etc. Zinc oxide powder is used as a heat conductive grease. It is also known to be used as a filler for imparting thermal conductivity (JP-A-51).
-55870, JP-A-54-116055, JP-A-55
-45770, JP-A-56-28264, JP-A-61-
157587, JP-A-2-212556, JP-A3-1
62493, JP-A-4-202496).

The zinc oxide powder used in the present invention can be used in a wide range of average particle size of 0.2 to 5 μm. However, it is dispersible in the base oil of the component B and the relationship with the aluminum nitride powder. Those having an average particle diameter of 0.3 to 4 μm are preferable, and those having an average particle diameter of 0.3 to 3 μm are particularly preferable. By doing so, the oil separation degree of the obtained heat conductive grease can be set to 0.01% or less. The hardness is preferably 4-5 in Mohs hardness.

As a filler for imparting thermal conductivity in the present invention
The alumina powder has a chemical structure of Al _TwoO_ThreeAcid represented by
Aluminum fluoride powder, which is
Generally, alumina (Alumina), α-alumina (α-Alumina)
a), Single crystal corund
um fines), and spherical alumina (Spherical Alumina)
What is called variously, etc. can be used.

In general, the industrial production method of alumina is a so-called Bayer method in which bauxite as a raw material is treated with hot caustic soda. This method is a method of once converting aluminum hydroxide (Al (OH) ₃ ) A crystal is made and this is baked at a high temperature in a rotary kiln or the like to obtain alumina. Since alumina has excellent thermal, mechanical and physicochemical properties, it is widely used in various refractories, abrasives, porcelain, white filler pigments, catalysts and the like.

Alumina powder is generally hexagonal or hexagonal.
Α-Al having a plane lattice crystal structure _TwoO_ThreeAnd the appearance is white
It is a colored powder, and the apparent particle size is about 20-80 μm on average.
However, each particle is a primary crystal of about 0.5 to 20 μm.
It is composed of alumina, depending on the application
Various grades of alumina powder are made. Especially that
The shape and size are uniform when using a grease composition.
Delicately affects properties such as sex and consistency.

The alumina powder which can be used in the present invention has a wide range of apparent average particle size of 20 to 80 μm, but it is 30 to 50 μm in view of dispersibility in a base oil such as liquid silicone. Preferred, especially 30
It is preferably ˜40 μm. Alumina is generally extremely hard and has a Mohs hardness in the range of 8 to 9. In the present invention, those within this range can be used.

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

The boron nitride powder used as the C component in the present invention has a hexagonal mesh-like crystal structure similar to that of graphite by heating boric acid or borate with a nitrogen-containing organic substance or a nitrogen compound such as ammonia. Obtained as a hexagonal boron nitride powder. Hexagonal boron nitride powder has excellent lubricity up to a high temperature range, has high electrical insulation, has high thermal conductivity, and is chemically stable and does not easily get wet with molten metal or glass. Used as a conductive insulating filler, solid lubricant, resin modifying filler, etc.

The boron nitride powder having a hexagonal crystal structure has a white appearance and an average particle size of 1 to 10 μm. In the present invention, a wide range of the 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 component B in the base oil and prevention of oil separation. 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 actually measured value is smaller than the theoretical value because the produced boron nitride powder usually 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 of 5.0 W / mK or more at room temperature. This is because if the thermal conductivity is 5.0 W / mK or less, high thermal conductivity cannot be obtained when using grease.

The hexagonal boron nitride (Hexa
Gonal Boron Nitride) is used as a raw material, and it is converted to cubic boron nitride (Cubic Boron Nitride) according to the same structural principle as diamond by treating it under high temperature and high pressure. Such a boron nitride powder having a cubic crystal structure has a hardness second only to that of diamond, has a dark brown to black appearance, and is commercially available in the particle size range of several μm to 800 μm. In the present invention, such cubic boron nitride can also be used, but 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 purposes.

Next, the silicon carbide powder used as the C component was made of silica stone and coke as main raw materials, and crushed into a high-purity α-SiC ingot synthesized in an electric furnace (Acheson furnace) to decarburize and remove iron. , Made through the classification process. Depending on the application, from the fine particle size to the submicron range, it is thoroughly pulverized and used as a raw material, and after classification, it is refined by chemical treatment to produce ultrafine powdered silicon carbide (Ultra Fine Silicon Carbide Powder) and various particle size distributions are manufactured.

Regarding the particle size and particle size distribution of silicon carbide, JIS R6001, JIS R6002, and J
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 in 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, 0.4
It is preferably 5 μm. The silicon carbide powder has a blue-black appearance and a triangular prismatic 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 actual measured value is smaller than the theoretical value because the produced silicon carbide powder usually 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 of 5.0 W / mK or more at room temperature.
This is because if the thermal conductivity is 5.0 W / mK or less, high thermal conductivity cannot be obtained when using grease or a sheet.

To produce the grease composition of the present invention,
Of the above components, at least component A and component B are trimix, twin twin, planetary mixer (all are registered trademarks of the mixer manufactured by Inoue Seisakusho Co., Ltd.), and ultramixer (mixer manufactured by Mizuho Industry Co., Ltd.) (Registered trademark of a mixer manufactured by Tokushu Kika Kogyo Co., Ltd.) and the like.
If necessary, you may heat at 50-150 degreeC. After mixing, it is preferable to carry out a kneading operation under a higher shearing force for uniform finish. As a kneading device, there are three rolls, a colloid mill, a sand grinder, etc.
The method using the present roll is preferable.

[0075]

EFFECTS OF THE INVENTION The silicone grease composition of the present invention obtained as described above shows a significant improvement in water resistance and 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 below with reference to examples, but the present invention is not limited thereto.
The evaluation of the moisture resistance effect was carried out by leaving the silicone grease composition in a thermo-hygrostat at 40 ° C. and 95% humidity for 1 day,
It was carried out by measuring the consistency and the thermal conductivity after 7 days and 1 month. If the moisture resistance is maintained, the aluminum nitride does not change with time, and thus the consistency and the thermal conductivity hardly change. Also, the measurement of the consistency is JIS K2220
It was carried out according to. The viscosity in the examples is the value at 25 ° C.

Preparation Example 1. As shown in Table 1, C₁₀H
₂₁Si (OCH_Three)_ThreeWith 10 g of organosilane
Aluminum powder (amorphous, average particle size 2.0 μm,
Specific surface area 4.0 m ^Two/ G) 1000 g of 5 liter
Put into a planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.),
Stir-mix for 30 minutes at room temperature to obtain the component (A-1)
A surface-treated aluminum nitride powder was obtained.

[0078]

[Table 1]

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

Preparation Examples 5-8. As shown in Table 1, the C ₁₀ H ₂₁ Si (OCH ₃ ) ₃ organosilane used in Preparation Example 1 was replaced with C ₁₂ H ₂₅ Si (OC
_{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 the component (A-5 to 8) was obtained in exactly the same manner as in Preparation Example 1 except that the organosilane of CH ₃ ) ₃ was used.

Examples 1-11 and Comparative Examples 1-4. Table 2,
The ingredients shown in Table 3 (parts by weight) were added to a planetary mixer (registered trademark of Inoue Seisakusho Co., Ltd.) having a capacity of 5 liters, and the mixture was stirred at room temperature for 30 minutes and then 3
Kneading with this roll was carried out three times to produce the silicone greases of Examples 1-11 and Comparative Examples 1-4.

[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)

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[Procedure amendment]

[Submission date] January 13, 1999 (1999.1.1
3)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

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[Claims]

[Procedure Amendment 2]

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[Correction target item name] 0013

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

[Procedure 3]

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If the average particle size is less than 0.5 μm, the thickening effect is too large, so that when the grease is used, it becomes a grease with low consistency (hard and poor in dispenseability).
Not preferable 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 the base oil is severely separated (great oil separation). Therefore, naturally, good grease cannot be obtained. The specific surface area is 0.1-10
A range of 0 m ² / g can be used, and uniform
Of ¹ to 10 m ² / g is preferable to obtain a saccharide composition.
More preferably, it is particularly preferably ^{2 to 5} m ² / g.

[Procedure amendment 4]

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Examples of such a group include a methyl group,
Alkyl groups such as ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group; vinyl group , An alkenyl group such as an allyl group; an aryl group such as a phenyl group and a tolyl group; an aralkyl group such as a 2-phenylethyl group and a 2-methyl-2-phenylethyl group; or a hydrogen bonded to a carbon atom of these groups. Chlormethyl group, 3,3,3-trifluoropropyl group, 2- (perfluorobutyl) ethyl group, 2-, in which some or all of the atoms are substituted with halogen atom, cyano group, hydroxyl group, etc.
(Perfluorooctyl) ethyl group, halogenated hydrocarbon group such as p-chlorophenyl group, cyanopropyl group, phenol group, hindered phenol group and the like, which is the same or different, and is unsubstituted or substituted with 1 to 30 carbon atoms. Monovalent hydrocarbon group, amino group-containing organic group, polyether group- containing organic group,
Examples of the organic group include an epoxy group, but in the present invention, a saturated or unsaturated monovalent hydrocarbon having 1 to 18 carbon atoms.
A group is preferable, and a methyl group, a phenyl group, and an alkyl group having 6 to 14 carbon atoms are particularly preferable.

[Procedure Amendment 5]

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The organopolysiloxane is a straight chain,
It may have either a branched structure or a cyclic structure. In addition, when using these, they can be used alone.
Combinations of more than one species are also possible. Although c is 1.8 to 2.3, it is particularly preferably in the range of 1.9 to 2.1 which is linear or more linear.

[Procedure correction 6]

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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 property required for a silicone grease composition.
It is preferably 50 to 500,000 cs, and particularly preferably 100 to 100,000 cs. When the amount of the above-mentioned liquid silicone used is less than 5% by weight, it does not form a grease and has poor extensibility, and when it is more than 50% by weight, it has poor thermal conductivity.
It is preferably in the range of 50% by weight, particularly preferably in the range of 7 to 30% by weight.

[Procedure Amendment 7]

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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 Examples include butoxyethoxyethyl adipate and the like.

[Procedure Amendment 8]

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

[Procedure Amendment 9]

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[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 chemical formula 11, and it is possible to prepare perfluoroalkyl ether having a low viscosity to a high viscosity depending on the degree of polymerization. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 7, 1999 (1999.4.7)

[Procedure Amendment 1]

[Document name to be amended] Statement

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[Claims]

[Procedure Amendment 2]

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

[Chemical 1]

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10M 105/74 C10M 105/74 107/08 107/08 107/32 107/32 107/38 107/38 107 / 50 107/50 113/00 113/00 113/08 113/08 113/16 113/16 // C10N 10:04 10:06 20:02 30:00 50:10 60:00 (72) Inventor Isobe Kenichi Gunma Prefecture Usui-gun Matsuida-cho 1-ji, Hitomi 10 Shin-Etsu Chemical Co., Ltd. Silicon Electronic Materials Research Laboratory F-term (reference) 4H104 AA13B AA17C AA21B AA26B BA01A BA06A BB33A BB34A BD01A BD06A CD06A CD06A CDA04A CB02C02 EA08C EA09C FA02 FA03 LA04 LA13 QA18

Claims (6)

[Claims] 1. A) The general formula R ¹ _a R ² _b SiY _4-a-b.
50 to 95% by weight of aluminum nitride powder surface-treated with an organosilane represented by and / or a partial hydrolysis-condensation product thereof, and B) a liquid silicone, a liquid hydrocarbon oil or a fluorinated hydrocarbon oil. A thermally conductive grease composition, characterized in that it comprises 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 a part or all of the hydrogen atoms bonded to the carbon atoms of this group are substituted with halogen atoms, R ² is a hydrocarbon group having 1 to 20 carbon atoms, or , A group in which some or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, Y is a hydrolyzable organic 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) is of the general formula R ⁴ _c SiO 2.
_The thermally conductive grease composition according to claim 1, which is an organopolysiloxane represented by _{(4-c) / 2} and having a viscosity at 25 ° C. of 50 to 500,000 cs.
However, R ⁴ in the above formula is one or more groups selected from the group of saturated or unsaturated monovalent hydrocarbon groups having 1 to 18 carbon atoms, and c is 1. It is a number of 8 ≦ c ≦ 2.2. 3. The liquid hydrocarbon oil is at least one selected from paraffin oils, naphthene oils, α-olefin oligomers, polybutenes, polyalkylene glycols, diesters, polyol esters and phosphoric acid esters. The thermally conductive grease composition described in 1. 4. A liquid hydrocarbon oil having a viscosity of 50 to 5 at 25 ° C.
The heat conductive grease composition according to claim 1 or 3, which has a viscosity of 0,000 cs. 5. The fluorohydrocarbon oil is at least one selected from polychlorotrifluoroethylene, fluoroesters and polyperfluoroalkyl ethers.
The heat conductive grease composition according to claim 1. 6. The component (C) contains at least one thickener selected from zinc oxide, alumina, boron nitride and silicon carbide in an amount of 30% by weight or less.
The heat conductive grease composition described in any one of to 5.