Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
  • C10M169/02—Mixtures of base-materials and thickeners
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/04—Elements
  • C10M2201/05—Metals; Alloys
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/06—Metal compounds
  • C10M2201/061—Carbides; Hydrides; Nitrides
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/06—Metal compounds
  • C10M2201/062—Oxides; Hydroxides; Carbonates or bicarbonates
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
  • C10M2229/02—Unspecified siloxanes; Silicones
  • C10M2229/025—Unspecified siloxanes; Silicones used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
  • C10M2229/04—Siloxanes with specific structure
  • C10M2229/044—Siloxanes with specific structure containing silicon-to-hydrogen bonds
  • C10M2229/0445—Siloxanes with specific structure containing silicon-to-hydrogen bonds used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2010/00—Metal present as such or in compounds
  • C10N2010/04—Groups 2 or 12
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2010/00—Metal present as such or in compounds
  • C10N2010/06—Groups 3 or 13
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/055—Particles related characteristics
  • C10N2020/06—Particles of special shape or size
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/02—Pour-point; Viscosity index
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/08—Resistance to extreme temperature
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/14—Electric or magnetic purposes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
  • C10N2050/10—Form in which the lubricant is applied to the material being lubricated semi-solid; greasy

Definitions

• the present invention relates to a thermally conductive grease.
• heat amount generated from a unit area of these electronic components has become extremely large.
• the total heat amount of these electronic components corresponds to about 20 times of that of an iron for pressing clothes.
• cooling of these heat-generating electronic components is necessary.
• a heat sink or a housing made of metal is employed, and further, in order to efficiently transfer a heat from a heat-generating electronic component to a cooling portion such as a heat sink or a housing, a thermally conductive material is employed.
• a thermally conductive material is employed. The reason for using such a thermally conductive material, is that if such a heat-generating electronic component is directly contact with e.g.
• a heat sink air is present on their interface from microscopic observation, which prevents heat conduction. Accordingly, instead of the air present on the interface, by disposing a thermally conductive material in the gap between the heat-generating electronic component and e.g. the heat sink, it is possible to efficiently transfer heat.
• thermally conductive sheet produced by curing a silicone rubber blended with a thermally conductive powder; a thermally conductive pad that has flexibility and produced by curing a flexible silicone such as a silicone gel blended with a thermally conductive powder; a thermally conductive grease having flowability produced by blending a liquid silicone with a thermally conductive powder; or a phase change type thermally conductive material which becomes soft or flowable according to the operation temperature of a heat-generating electronic component; may be mentioned.
• a thermally conductive grease is particularly suitable for transferring heat.
• a thermally conductive grease is produced by blending a base oil that is a liquid silicone such as a silicone oil with a thermally conductive powder.
• a base oil that is a liquid silicone such as a silicone oil
• a thermally conductive powder In order to satisfy requirement for high thermal conductivity, it is proposed to employ an aluminum nitride powder as the thermally conductive powder (Patent Document 1).
• an aluminum nitride powder has a hexagonal crystal structure and its particle shape is not spherical, it is not possible to sufficiently increase packing amount of such a thermally conductive powder to achieve sufficiently high thermal conductivity.
• Patent Document 5 In order to solve the problem of separation of silicone oil being a base oil, it is proposed to use a special silicone (Patent Document 5), but this document does not describes as to high thermal conductivity.
• Patent Document 1 JP-A-2000-169873
• Patent Document 2 JP-A-2002-194379
• Patent Document 3 JP-A-2005-54099
• Patent Document 4 JP-A-2005-170971
• Patent Document 5 JP-A-2004-917743
• the present invention employs the following means.
• the thermally conductive material (A), (B) or (C) is one type or at least two types selected from the group consisting of metal aluminum, aluminum nitride and zinc oxide.
• thermally conductive material (A) is metal aluminum
• thermally conductive material (B) is aluminum nitride
• thermally conductive material (C) is zinc oxide.
• the viscosity of the base oil is from 300 to 1,000 mPa ⁇ s.
• the base oil is a silicone oil modified to have specific alkyl group.
• the content of the thermally conducive materials (A), (B) and (C) is from 60 to 80 vol %.
• the thermally conductive material (A) is from 50 to 70 vol %
• the thermally conductive material (B) is from 30 to 20 vol %
• the thermally conductive material (C) is from 20 to 10 vol %.
• the present invention provides a grease suitable for thermal conduction of e.g. heat generated from electronic components.
• the grease shows low thermal resistance and improved durability against heat cycle.
• the thermally conductive materials (A), (B) or (C) contained in the grease of the present invention is one type or at least two types selected from the group consisting of metal aluminum, aluminum nitride and zinc oxide.
• the thermally conductive material (A), (B) or (C) may contain a thermally conductive powder such as metal tin, metal silver, metal copper, silicon carbide, aluminum oxide, silicon nitride or boron nitride powder, and such a thermally conductive powder may replace preferably at most 5 vol %, particularly preferably at most 3 vol % of the total amount of metal aluminum, aluminum nitride and zinc oxide for use.
• the grease of the present invention contains the powder of thermally conductive material wherein the particle size distribution of the powder measured by a laser diffraction type particle distribution method has population peaks in the ranges of from 2.0 to 10 ⁇ m, from 1.0 to 1.9 ⁇ m and from 0.1 to 0.9 ⁇ m, respectively, whereby the number of contact points between thermally conductive materials can be increased. As a result, it is possible to improve thermal conductivity of the grease.
• One method of employing a powder of thermally conductive material having a particle distribution having such population peaks may be a method of blending thermally conductive materials having different particle size distributions.
• thermally conductive materials that are the thermally conductive materials (A), (B) and (C) having different average particle sizes
• thermally conductive materials (A), (B) and (C) having different average particle sizes it is possible to increase packing density. Namely, by blending a thermally conductive material (A) having an average particle size of from 2.0 to 10 ⁇ m, a thermally conductive material (B) having an average particle size of from 1.0 to 1.9 ⁇ m and a thermally conductive material (C) having an average particle size of from 0.1 to 0.9 ⁇ m, it is possible to increase the packing density of thermally conductive material. As a result, it is possible to improve the thermal conductivity of grease.
• the grease contain a thermally conductive material having a small average particle size of preferably from 0.1 to 10 ⁇ m, more preferably from 0.3 to 6 ⁇ m, it becomes possible to reduce the thickness of grease film containing the thermally conductive material, and to reduce the thermal resistance (difficulty of transferring heat). As a result, it becomes possible to produce a grease which extremely easily transfer heat.
• the thermally conductive material (A) having an average particle size of from 2.0 to 10 ⁇ m to be used in the present invention needs to have an average particle size of from 2.0 to 10 ⁇ m, preferably from 3 to 6 ⁇ m. If the average particle size is larger than 10 ⁇ m, forming of thin film of grease tends to be difficult, and the thermal resistance of the grease tends to increase. On the other hand, if the average particle size is smaller than 2.0 ⁇ m, metal aluminum becomes preferred as the thermally conductive material (A).
• the thermally conductive material (B) having an average particle size of from 1.0 to 1.9 ⁇ m to be employed in the present invention needs to have an average particle size of from 1.0 to 1.9 ⁇ m, preferably from 1.3 to 1.7 ⁇ m. If the average particle size is larger than 1.9 ⁇ m, the particle size becomes close to that of the thermally conductive material having an average particle size of from 2.0 to 10 ⁇ m, the packing density tends to be poor and the thermal resistance tends to increase.
• the thermally conductive material (B) is preferably aluminum nitride.
• the thermally conductive material (C) having an average particle size of from 0.1 to 0.9 ⁇ m being a zinc oxide powder to be employed in the present invention needs to have an average particle size of from 0.1 to 0.9 ⁇ m, preferably from 0.3 to 0.7 ⁇ m. If the average particle size is larger than 0.9 ⁇ m, the particle size becomes close to that of the thermally conductive material having an average particle size of from 1.0 to 1.9 ⁇ m, whereby the packing density tends to be poor and the thermal resistance tends to increase. If the average particle size is smaller than 0.1 ⁇ m, the packing density of entire thermally conductive material tends to be poor and the thermal resistance tends to increase.
• the thermally conductive material (C) is preferably zinc oxide.
• the content of the thermally conductive materials (A), (B) and (C) in the grease is preferably from 60 to 80 vol %, more preferably from 65 to 75 vol %. If the content of the thermally conductive material exceeds 80 vol %, the grease tends to be hard, and the thermal resistance tends to increase. Further, if the content of the thermally conductive material is less than 60 vol %, since the packing amount of the thermally conductive material is small, heat tends to be hardly transferred, and the thermal resistance tends to increase.
• the composition ratio of the three types of thermally conductive materials having different average particle sizes is such that the thermally conductive material (A) is preferably from 50 to 70 vol %, particular preferably from 55 to 65 vol %, the thermally conductive material (B) is preferably from 30 to 20 vol %, particularly preferably from 27 to 25 vol %, and the thermally conductive material (C) is preferably from 20 to 10 vol %, particularly preferably from 17 to 13 vol %. If the content ratio of the thermally conductive material (A) becomes less than 50 vol %, the grease tends to be hard, and the thermal resistance tends to increase. If it becomes more than 70 vol %, the packing density of the thermally conductive material tends to be poor and the thermal resistance tends to increase.
• the average particle size in the present invention was measured by using a “Laser Diffraction Particle Size Analyzer SALD-200” manufactured by Shimadzu Corporation.
• An evaluation sample was prepared in the following manner. 5 g of thermally conductive powder to be analyzed was added to 50 cc of purified water in a glass beaker, they were stirred by using a spatula, and subjected to dispersion treatment by an ultrasonic cleaner for 10 minutes. The solution of the powder of thermally conductive material subjected to the dispersion treatment, was dropped onto the sampler unit of the analyzer by using a dropping piplet, and left until it became stable enough to measure the light absorptivity. When the light-absorptivity is thus stabilized, the measurement is carried out.
• the laser diffraction particle size analyzer calculates a particle size distribution from light intensity distribution of light diffracted/scattered by particles detected by a sensor.
• the average particle size is calculated by multiplying the value of particle size by a relative particle amount (difference %) and dividing the multiplied product by the total 100% of the relative particle amount.
• the average particle size is the average diameter of particles.
• the base oil employed in the present invention has a surface tension at 25° C. of from 25 to 40 dyn/cm, particularly preferably from 30 to 35 dyn/cm. If the surface tension is lower than 25 dyn/cm, when a heat cycle is repeatedly applied to the grease, the base oil tends to be separated, and thereby the grease tends to be hard and the thermal conductivity tends to be poor. Further, if the surface tension is higher than 40 dyn/cm, the wet property of the grease tends to be poor, and the grease is hardly spread and the thermal conductivity tends to be poor.
• the surface tension is a property of liquid that the liquid tends to make its surface area as small as possible, and the surface tension is a type of interface tension.
• the liquid When a liquid is in contact with a gas, the liquid has a property of shrinking its surface area as much as possible.
• a molecule in the liquid is attracted by molecules around the molecule by an attracting force, while a molecule on a surface is not receive an effect of attracting force of other liquid molecules in a direction where the molecule does not contact with the liquid. By this effect, molecules on the surface have excess energy, which produces a surface tension.
• the surface tension is strong, the base oil is hard to be separated from the grease.
• Wilhelmy method is preferred as a method for measuring surface tension.
• Wilhelmy method is such that when a plate (mainly a platinum plate) is vertically dipped into a liquid surface, the liquid creeps up along the plate, and increase of the surface area of the liquid produced by the creep up, a surface tension occurs. By dividing the force by the perimeter length (twice of the total of width and thickness) of the plate, a force per a until length (dyne/cm) is obtained. A surface tension can be obtained from this value.
• an “automatic surface tension meter” manufactured by Kyowa Interface Science Co., Ltd., etc. may be employed.
• Surface tension of the base oil can be adjusted by adding an additive having a large surface tension to a base oil having small surface tension.
• an additive having a large surface tension For example, by adding a silane coupling agent having an alkyl group to e.g. a dimethyl silicone oil having small surface tension, it is possible to adjust the surface tension.
• the viscosity of the base oil is preferably from 300 to 1,000 mPa ⁇ s, particularly preferably from 500 to 700 mPa ⁇ s. If the viscosity of base oil is less than 300 mPa ⁇ s, the base oil and the thermally conductive material in the grease tends to be separated by a heat cycle, whereby the thermal resistance tends to increase. If the viscosity of base oil exceeds 1,000 mPa ⁇ s, it tends to be difficult to densely pack the thermally conductive material, whereby the thermal conductivity of the grease tends to be poor.
• the viscosity of the base oil is measured by a “Digital Viscosity Meter DV-I” manufactured by Brookfield. Using an RV spindle set, a rotor No. 1 and a container capable of adapting the rotor and capable of containing the base oil to a baseline, are used. The rotor is immersed into the base oil, and the viscosity of the base oil was evaluated at a rotation speed of 10 rpm.
• a silicone oil having a surface tension of from 27 to 37 dyn/cm and a viscosity of from 400 to 800 mPa ⁇ s that is produced by modifying a dimethyl silicone oil having a surface tension of preferably from 25 to 40 dyn/cm and having a viscosity of from 300 to 1,000 mPa ⁇ s so that its methyl group is modified to have an alkyl group having at least 3, particularly preferably from 8 to 12 carbon atoms.
• Such a silicone oil modified to have specific alkyl group has large surface tension, and suppresses deterioration of grease in thermal resistance due to heat cycle.
• the grease of the present invention contains a silane coupling agent that functions as a surface adulterant which can impart hydrophobic property to the filler, improve its dispersibility and modify the quality of organic resin.
• a preferred silane coupling agent may, for example, be an alkylsilane having an alkyl group containing from 8 to 10 carbon atoms.
• An example of preferred silane coupling agent may, for example, be n-octyl trimethoxysilane, n-octyl triethoxysilane or n-decyl trimethoxysilane.
• the grease of the present invention may contain besides the above components, an antioxidant or an anticorrosive agent for metals as the case requires.
• the grease of the present invention can be produced by kneading the above material by a multi-functional mixer stirrer, a kneader, a hybrid mixer, etc.
• the method for measuring the thermal resistance of grease is as follows. A grease is sandwiched between a copper jig of cubic shape in which a heater is embedded and having a leading edge of 1 cm 2 (1 cm ⁇ 1 cm) and a copper jig of cubic shape to which a cooling fin is attached and having a leading edge of 1 cm 2 (1 cm ⁇ 1 cm), and a load of 4 kg per 1 cm square is applied so that the sample and the copper jigs are closely contact. The amount of sample is selected so that the sample fills the entire contact surface.
• the thermal resistance of the grease of the present invention is preferably at most 0.2° C./W, particularly preferably at most 0.1° C./W considering the thermal conductivity of grease.
• the separation state of the grease of the present invention was evaluated in the following manner. Namely, between two transparent glass plates of 1 mm thick and 10,000 mm 2 (100 mm ⁇ 100 mm) area, a grease of 100 ⁇ m thick and 900 mm 2 (30 mm ⁇ 30 mm) area was applied, and in this state, a heat cycle at ⁇ 40° C. for 30 min and at 130° C. for 30 min was applied. The number of cycles was 100 cycles. The weight of the base oil separated from the thermally conductive grease was measured to evaluate separation.
• the thermal resistance and the separation state of the grease obtained was evaluated and the results are shown in Table 4. Further, in the evaluation result, a thermally conductive grease having a thermal resistance of more than 0.2° C./W was designated as a Comparative Example since it does not transfer heat from a heat-generating portion to a cooling portion efficiently.
• the grease of the present invention shows low thermal resistance, it is not significantly deteriorated by heat cycle, and thus, it can efficiently transfer heat from heat-generating electronic components to a cooling portion such as a heat sink or a casing.
• the thermally conductive grease of the present invention can be suitably applied to various applications.
• the grease can efficiently transfer heat when the grease is disposed between a heat-generating electronic components and e.g. a heat sink, the grease is usable for e.g. cooling of heat-generating electronic components.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)

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• 2007
  • 2007-10-16 US US12/445,746 patent/US20100048435A1/en not_active Abandoned
  • 2007-10-16 CN CNA2007800385479A patent/CN101528902A/zh active Pending
  • 2007-10-16 JP JP2008539832A patent/JP5231236B2/ja active Active
  • 2007-10-16 WO PCT/JP2007/070200 patent/WO2008047809A1/fr not_active Ceased
  • 2007-10-17 TW TW096138907A patent/TWI457434B/zh active

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