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  • C08K3/00—Use of inorganic substances as compounding ingredients
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  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
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  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2296—Oxides; Hydroxides of metals of zinc
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  • C08K2201/00—Specific properties of additives
  • C08K2201/014—Additives containing two or more different additives of the same subgroup in C08K

Definitions

• the present invention relates to a heat conductive silicone composition, and more particularly to a heat conductive silicone composition that does not damage a silicon chip and has excellent displacement resistance.
• heat conductive materials used for the heat removal have been used. Proposed. In this case, there are two types of heat conductive materials: (1) a sheet-shaped material that is easy to handle, and (2) a paste-shaped material called a heat dissipation grease.
• the sheet-like product of (1) has an advantage that it is not only easy to handle but also excellent in stability, but the contact heat resistance is inevitably large. It is inferior to the case of grease.
• a certain degree of strength and hardness are required to maintain the sheet shape, it is not possible to absorb the tolerance generated between the element and the housing, and the stress may destroy the element.
• the heat dissipation grease of (2) not only can it be applied to mass production of electric and electronic products by using a coating device, etc., but it also has the advantage of excellent heat dissipation performance because of its low contact thermal resistance. There is. However, if the viscosity of the heat dissipation grease is lowered for large-scale use by screen printing, etc., the heat dissipation grease will be displaced due to the thermal shock of the element (pump-out phenomenon), resulting in insufficient heat removal. As a result, the element may malfunction.
• a grease-like silicone composition in which bleeding of base oil is suppressed by combining with silane Patent Document 1: JP-A-11-49958
• liquid silicone and heat having a constant thermal conductivity and a Mohs hardness of 6 or more.
• a thermally conductive silicone composition having excellent thermal conductivity and dispenseability which is formed by combining a conductive inorganic filler and a thermally conductive inorganic filler having a constant thermal conductivity and a Mohs hardness of 5 or less
• Patent Reference 2 Japanese Patent Application Laid-Open No. 11-246884
• a heat conductive grease composition comprising a combination of a specific base oil and metallic aluminum powder having an average particle size of 0.5 to 50 ⁇ m
• Patent Document 3 Japanese Patent Application Laid-Open No. 2000-2000).
• Patent Document 4 JP 2000-2000A. No. 1699873
• Patent Documents 5 to 8 Patent No. 4130091, Patent No. 5388329, Patent No. 5283553, and Japanese Patent Laid-Open No. 2010-2010.
• Higher performance thermally conductive silicone grease compositions such as JP-A-015633) have been proposed.
• the present invention has been made in view of the above circumstances, and an object thereof is to provide a heat conductive silicone composition which is excellent in workability and displacement resistance without damaging a silicon chip.
• the present inventors have conducted extensive studies in order to achieve the above-mentioned object, and as a result, for a specific organopolysiloxane, only a thermally conductive inorganic filler having a specific Mohs hardness was used, and the thermal conductivity was diluted with a solvent.
• the present inventors have found that a silicone composition can obtain good results in terms of workability and resistance to misalignment without damaging silicon chips.
• the present invention provides the following thermally conductive silicone composition.
• (B) Thermally conductive inorganic filler having a Mohs hardness of 5 or less and an average particle diameter of 0.1 to 200 ⁇ m: 100 to 3,000 parts by mass, and (C) (A) and (B) components dispersed Alternatively, a volatile solvent capable of dissolving: A thermally conductive silicone composition containing 0.1 to 100 parts by mass and containing no thermally conductive inorganic filler having a Mohs hardness of more than 5.
• the organopolysiloxane of the component (A) other than the one-terminal trifunctional hydrolyzable organopolysiloxane (a1) represented by the general formula (1) has at least one alkenyl group in one molecule.
• R 3 is independently a saturated or unsaturated monovalent hydrocarbon group having 1 to 20 carbon atoms
• R 4 is independently a hydrogen atom or R 3
• n is an integer of 1 to 1,000.
• thermoly conductive silicone composition as described in 1.
• the solvent of the component (C) is an isoparaffin-based solvent having a boiling point of 80 to 360°C.
• the heat-conductive silicone composition of the present invention not only excels in heat conductivity, but also has no damage to silicon chips, and has good workability and resistance to misalignment, so that electric and electronic parts that generate heat during use It is suitable for removing heat from.
• the organopolysiloxane of the component (A) constituting the heat conductive silicone composition of the present invention has a thixotropy ⁇ defined by ⁇ 1/ ⁇ 2 of 1.51 to 2.00 and a B type rotation at 25° C. It is a liquid silicone having a viscosity of 10 to 1,000,000 mPa ⁇ s measured by a viscometer at a rotor rotation speed of 2 rpm.
• ⁇ 1 is a viscosity measured at 25° C. with a B-type rotational viscometer at a rotor rotation speed of 2 rpm
• ⁇ 2 is measured at 25° C. with a B-type rotational viscometer at a rotor rotation speed of 4 rpm. It is the viscosity when it is done.
• the thixotropy of the component (A) is represented by the thixotropy ⁇ , and the larger the thixotropy ⁇ , the stronger the viscosity of the oil.
• the organopolysiloxane as the component (A) has a thixotropy ⁇ of 1.51 to 2.00, and particularly preferably 1.60 to 1.90.
• the thixotropy ⁇ is less than 1.51, the deviation resistance is insufficient, and when it is more than 2.00, it is difficult to disperse in the solvent and the workability is deteriorated.
• the viscosity of the organopolysiloxane (A) at 25° C. measured with a B type rotational viscometer at a rotor rotation speed of 2 rpm is 10 to 1,000,000 mPa ⁇ s as described above. However, the range of 100 to 100,000 mPa ⁇ s is particularly preferable. If the viscosity at 25° C. is less than 10 mPa ⁇ s, the stability of the resulting thermally conductive silicone composition will be poor, and if it is greater than 1,000,000 mPa ⁇ s, it will be difficult to mix with the component (B).
• the organopolysiloxane as the component (A) preferably contains 1 to 95% by mass of a trifunctional hydrolyzable organopolysiloxane (a1) having one terminal represented by the following general formula (1).
• R 1 is independently an alkyl group having 1 to 6 carbon atoms
• R 2 is independently a saturated or unsaturated monovalent hydrocarbon group having 1 to 20 carbon atoms
• b is 5 to 120. It is an integer.
• R 1 in the general formula (1) is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group and a propyl group, and preferably a methyl group.
• R 2 is a group selected from the group consisting of saturated or unsaturated monovalent hydrocarbon groups having 1 to 20 carbon atoms, for example, a methyl group, an ethyl group, a propyl group, a hexyl group, an octyl group, Decyl group, dodecyl group, tetradecyl group, hexadecyl group, alkyl group such as octadecyl group, cyclopentyl group, cycloalkyl group such as cyclohexyl group, vinyl group, alkenyl group such as allyl group, phenyl group, aryl group such as tolyl group, Aralkyl groups such as 2-phenylethyl group and 2-methyl-2
• b is an integer of 5 to 120, preferably 10 to 100. If b is too small, the viscosity of the composition may be too low and oil may ooze out from the resulting composition. If b is too large, the viscosity of the composition may be too high, resulting in an excessively high viscosity of the composition itself and poor handling. May be.
• the organopolysiloxane other than the trifunctional hydrolyzable organopolysiloxane (a1) having one terminal represented by the general formula (1) is not particularly limited.
• an organopolysiloxane having at least one alkenyl group in one molecule and an organohydrogenpolysiloxane having at least one SiH group represented by the following general formula (2), which will be described later, are mixed with platinum alone and chloride.
• the addition reaction product (organopolysiloxane) (a2) obtained by the addition reaction using a platinum catalyst such as platinum acid, platinum-olefin complex, platinum-alcohol complex or the like is preferable.
• the above-mentioned organopolysiloxane having an alkenyl group has at least one, preferably 2 to 5 in each molecule, an alkenyl group directly bonded to a silicon atom.
• the molecular structure of the organopolysiloxane having an alkenyl group is not particularly limited and may be linear or branched, but the main chain is basically composed of repeating diorganosiloxane units, and both ends of the molecular chain are triorganosiloxy groups. It is preferably a linear diorganopolysiloxane blocked with. Moreover, the organopolysiloxane having an alkenyl group may be used alone or in combination of two or more.
• alkenyl group examples include a vinyl group, an allyl group, a 1-butenyl group and a 1-hexenyl group, but a vinyl group is preferable from the viewpoint of ease of synthesis and cost.
• the alkenyl group bonded to the silicon atom may be present at the terminal of the molecular chain of the organopolysiloxane or in the middle thereof. From the viewpoint of flexibility, it is preferable that they are present only at both ends, but some may be present only at one end.
• organic groups bonded to a silicon atom include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a dodecyl group, an aryl group such as a phenyl group, a 2-phenylethyl group, a 2-phenylpropenyl group.
• alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a dodecyl group
• an aryl group such as a phenyl group, a 2-phenylethyl group, a 2-phenylpropenyl group.
• monovalent hydrocarbon groups such as aralkyl groups such as chloro group, and halogen-substituted monovalent hydrocarbon groups such as chloromethyl group and 3,3,3-trifluoropropyl group.
• the alkenyl group-containing organopolysiloxane has a viscosity at 25° C. measured using an Ostwald viscometer of preferably 10 to 100,000 mm 2 /s, and more preferably 100 to 30,000 mm 2 /s. preferable. Also, a mixture of two or more different viscosities may be used.
• the organohydrogenpolysiloxane having at least one, preferably 2 to 100, and more preferably 2 to 50 SiH groups is represented by the following general formula (2).
• R 3 is independently a saturated or unsaturated monovalent hydrocarbon group having 1 to 20 carbon atoms
• R 4 is independently a hydrogen atom or R 3
• n is an integer of 1 to 1,000.
• m is an integer of 0 to 1,000.
• R 3 in the general formula (2) is at least one group selected from the group of saturated or unsaturated monovalent hydrocarbon groups having 1 to 20 carbon atoms, and examples thereof include a methyl group, an ethyl group and a propyl group.
• n and m are respectively 1 ⁇ n ⁇ 1,000 and 0 ⁇ m ⁇ 1,000, preferably 2 ⁇ n ⁇ 100, 1 ⁇ m ⁇ 200, more preferably 2 ⁇ n ⁇ 50, 2 ⁇ m ⁇ 100. If n is too large, the viscosity may be too high and handling may be poor, and if m is too large, the viscosity may be too high and handling may be poor.
• the organohydrogenpolysiloxane having at least one SiH group may be used alone or in combination of two or more.
• the amount of the organohydrogenpolysiloxane having a SiH group used is such that (the number of SiH groups of the organohydrogenpolysiloxane having a SiH group)/(the number of alkenyl groups of the organopolysiloxane having an alkenyl group) is 0.
• the amount is preferably 0.3 to 3.0, and more preferably 0.4 to 1.5. If the value is too small, the desired thixotropy may not be obtained, and if it is too large, the fluidity may be lost and handling may be difficult.
• the amount of the platinum-based catalyst used is not particularly limited, but the platinum group metal mass conversion based on the total mass of the alkenyl group-containing organopolysiloxane and the at least one SiH group-containing organohydrogenpolysiloxane. It is preferably 1 to 200 ppm, and particularly preferably 5 to 100 ppm.
• the addition reaction of the above-mentioned organopolysiloxane having an alkenyl group and the above-mentioned organohydrogenpolysiloxane having at least one SiH group may be carried out according to a conventional method under the reaction conditions of 100 to 180° C. Particularly, it is preferable to set the temperature at 120 to 160° C. for 0.5 to 5 hours, especially 1 to 3 hours.
• the organopolysiloxane having an alkenyl group and the organohydrogenpolysiloxane having at least one SiH group may be subjected to an addition reaction in a state of being mixed with another organopolysiloxane such as the component (a1). it can.
• the content of the trifunctional hydrolyzable organopolysiloxane (a1) having one terminal represented by the general formula (1) in the organopolysiloxane (A) is preferably 1 to 95% by mass, and 20 to 90% by mass. Mass% is more preferable, and 30-80 mass% is further preferable. When the content is less than 1% by mass, the compatibility between the component (B) and the component (A) becomes poor, and when it is more than 95% by mass, the deviation resistance becomes poor.
• organopolysiloxane of the component (A) is mixed with the component (a3) other than the components (a1) and (a2) such as dimethylpolysiloxane having no reactive group in the range of 10 to 50% by mass.
• the component (a3) other than the components (a1) and (a2) such as dimethylpolysiloxane having no reactive group in the range of 10 to 50% by mass.
• the amount of the component (a1) or the component (a2) described above is used. Can be achieved by adjusting the amount of the organohydrogenpolysiloxane, etc.
• the component (B) constituting the heat conductive silicone composition of the present invention is a heat conductive inorganic filler having a Mohs hardness of 5 or less and an average particle diameter of 0.1 to 200 ⁇ m. Although it is an inorganic filler that imparts thermal conductivity to the conductive silicone composition, in the present invention, it is effective to prevent breakage of the silicon chip by setting the Mohs hardness and the average particle diameter thereof to be in the specific ranges.
• the Mohs hardness referred to here is sometimes referred to as the old Mohs hardness, but the hardness of the hardest diamond is 10 and is an index representing the hardness of a substance in 10 steps.
• the component (B) has a Mohs hardness of 5 or less, preferably 2 to 5. If the Mohs hardness exceeds 5, silicon chips are likely to be damaged.
• the thermally conductive silicone composition of the present invention does not contain a thermally conductive inorganic filler having a Mohs hardness of more than 5.
• the average particle diameter of the component (B) is smaller than 0.1 ⁇ m, the viscosity of the heat conductive silicone composition becomes too high, which makes it difficult to handle, and when it exceeds 200 ⁇ m, the obtained heat conductive silicone composition is unsatisfactory.
• the thickness is required to be 0.1 to 200 ⁇ m because it tends to be uniform, but is preferably 0.5 to 100 ⁇ m, and more preferably 0.5 to 50 ⁇ m.
• the average particle diameter is a volume-based average particle diameter, and can be measured by Microtrac MT3300EX manufactured by Nikkiso Co., Ltd.
• the type of the thermally conductive inorganic filler of the component (B) may be any as long as the Mohs hardness is 5 or less, but at least one type is selected from aluminum powder, zinc oxide powder, boron nitride powder and aluminum hydroxide powder. It is preferable to select. Aluminum powder and zinc oxide powder are particularly preferred because of their good filling properties. Further, two or more kinds having different kinds and different average particle diameters may be blended and used.
• the blending amount of the component (B) needs to be in the range of 100 to 3,000 parts by mass, preferably 500 to 2,000 parts by mass, relative to 100 parts by mass of the organopolysiloxane of the component (A). It is a range. If the amount is less than 100 parts by mass, not only sufficient thermal conductivity cannot be obtained, but also the strength of the grease cannot be maintained, which tends to cause deviation. If it is more than 3,000 parts by mass, the handling will be poor.
• the volatile solvent of the component (C) constituting the heat conductive silicone composition of the present invention has the function of lowering the viscosity of the heat conductive silicone composition and improving workability, and for example, toluene, Dissolves (A) component organopolysiloxane and (B) component thermally conductive inorganic filler such as xylene, acetone, methyl ethyl ketone, cyclohexane, n-hexane, n-heptane, butanol, isopropyl alcohol (IPA), and isoparaffin.
• any solvent can be used as long as it can be dispersed.
• an isoparaffin solvent having a boiling point of 80 to 360°C. If the solvent has a boiling point of less than 80° C., volatilization will be too fast and the viscosity will increase during the printing operation, causing problems. When the boiling point exceeds 360° C., it tends to remain in the thermally conductive silicone composition and the thermal properties tend to deteriorate.
• isoparaffinic solvent having a boiling point of 80 to 360° C. examples include IP solvent 2028MU and IP solvent 2835 manufactured by Idemitsu Kosan Co., Ltd.
• the addition amount of the component (C) in the present invention is 0.1 to 100 parts by mass with respect to 100 parts by mass of the component (A). If the addition amount of the component (C) is less than 0.1 parts by mass, the viscosity of the heat conductive silicone composition cannot be lowered sufficiently. Further, if it is more than 100 parts by mass, the settling of the thermally conductive inorganic filler is accelerated and the storability of the thermally conductive silicone composition is deteriorated, so that the range of 5 to 70 parts by mass is preferable, and particularly 10 to 50 parts by mass. It is preferably in the range.
• the shift resistance of the heat conductive silicone composition is more suppressed when an organopolysiloxane having a higher viscosity is used as the component (A). Moreover, when the filling amount of the heat conductive inorganic filler is increased to improve the heat conductive performance, the viscosity of the heat conductive silicone composition increases. That is, both the suppression of the shift resistance and the improvement of the heat conduction performance increase the viscosity of the heat conductive silicone composition. However, there is a limit to the allowable viscosity from the viewpoint of handleability and the like. Therefore, in the present invention, the viscosity of the thermally conductive silicone composition is adjusted by adding the component (C). By doing so, it becomes possible to put into practical use a heat-conductive silicone composition that achieves a higher level of workability and heat dissipation performance than ever before.
• the heat conductive silicone composition of the present invention when the heat conductive silicone composition of the present invention is thinly applied to a heat sink or the like by using a printing means such as a metal screen, the contained solvent is heated at room temperature or actively to be easily volatilized. Therefore, a high-performance thermally conductive silicone composition, which has been difficult to apply uniformly and thinly in the past, can be easily put into practical use.
• components (A) to (C) are added, and Trimix, Twin Twin and Planetary Mixer (all are registered trademarks of Inoue Seisakusho Co., Ltd.) ), an ultra mixer (registered trademark of a mixer manufactured by Mizuho Industry Co., Ltd.), and a Hibis Dispermix (registered trademark of a mixer manufactured by Tokushu Kika Kogyo Co., Ltd.). It may be heated to 50 to 150° C. if necessary. However, in the case of heating, from the viewpoint of safety, it is preferable to heat and mix only the components (A) and (B), then cool and then add the component (C) and further mix.
• the thermally conductive silicone composition of the present invention measured at 25° C. using a Malcolm viscometer at a rotor rotation speed of 10 rpm is less than 10 Pa ⁇ s, the thermally conductive inorganic filler easily precipitates and the storage stability is improved. If it is worse than 500 Pa ⁇ s and screen printing becomes difficult when it is more than 500 Pa ⁇ s, the range of 10 to 500 Pa ⁇ s is preferable, and the range of 30 to 300 Pa ⁇ s is more preferable.
• the heat conductive silicone composition of the present invention is preferably used for heat dissipation of heat generating devices such as CPUs and GPUs of notebook computers and heat generating devices of vehicle-mounted ECUs.
• ⁇ 1 is a viscosity measured at 25° C. with a rotational speed of the rotor of 2 rpm by a B-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd.: Model TVB-10), and ⁇ 2 is the rotational speed of the rotor. Viscosity measured at 25° C. at 4 rpm.
• the particle size of the thermally conductive inorganic filler ((B) component) is a volume-based cumulative average diameter measured by Microtrac MT3300EX, which is a particle size analyzer manufactured by Nikkiso Co., Ltd.
• the thermal conductivity of the thermally conductive silicone composition was measured at 25° C. using TPS-2500 manufactured by Kyoto Electronics Manufacturing Co., Ltd.
• the viscosity of the heat conductive silicone composition was measured using a model number PC-1TL (rotation speed 10 rpm) manufactured by Malcolm Co., Ltd.
• the deviation of the heat conductive silicone composition was evaluated by the numerical value measured according to the following steps. (1) After applying 0.5 cc of the thermally conductive silicone composition to an aluminum plate, it was placed in a chamber at 80° C. for 30 minutes to volatilize the solvent. Then, after taking out from the chamber and cooling, a spacer of 1.5 mm is provided, sandwiched with a slide glass, fixed with a clip (sandwich the thermally conductive silicone composition so as to have a circular shape of about 2 cm in diameter), and a test piece. It was made. (2) Next, this test piece is set vertically to the ground, and a heat cycle test is repeated so that -40°C and 150°C (each 30 minutes) are repeated alternately.
• the test piece was placed in a tester (model number: TSE-11-A) and 1,000 cycle tests were performed. (3) After the 1,000-cycle test, how much the heat conductive silicone composition deviated from the original place was measured. If it was 3 mm or less, it was evaluated as ⁇ , and if it was more than 3 mm, it was evaluated as x.
• organohydrogenpolysiloxane represented by the following formula (3) (4.5 g (organohydrogen with respect to the total of vinyl groups in the organopolysiloxane))
• B-1 Aluminum powder (average particle size 10.3 ⁇ m) Mohs hardness: 2.9
• B-2 Aluminum powder (average particle size 1.5 ⁇ m) Mohs hardness: 2.9
• B-3 Aluminum hydroxide powder (average particle size 0.9 ⁇ m) Mohs hardness: 3
• B-4 Zinc oxide powder (average particle size 1.1 ⁇ m) Mohs hardness: 4 to 5
• B-5 Boron nitride powder (average particle size 8.0 ⁇ m) Mohs hardness: 2.0 ⁇ B-6 and B-7 are for comparative examples>
• B-6 Alumina powder (average particle size 10.0 ⁇ m) Mohs hardness: 8-9
• B-7 Aluminum nitride powder (average particle size 7.0 ⁇ m) Mohs hardness: 8
• C component C-1: IP Solvent 2028MU (Isoparaffinic solvent, trade name of Idemitsu Kosan Co., Ltd.) Boiling point; 210-254°C C-2: IP solvent 2835 (Isoparaffinic solvent, trade name of Idemitsu Kosan Co., Ltd.) Boiling point; 270-350°C

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• 2019
  • 2019-01-10 JP JP2019002591A patent/JP7001071B2/ja active Active
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