Heat-conductive silicone adhesive composition, and heat-conductive composite

Abstract

To provide a heat-conductive silicone adhesive composition good in handleability, capable of obtaining sufficient adhesive strength, and excellent in storage stability of adhesive strength.SOLUTION: A heat-conductive silicone adhesive composition includes: (a) a linear or branched organopolysiloxane having an average degree of polymerization of 100 to 20,000; (b) a heat-conductive filler; (c) an organopolysiloxane including a constituent having an alkenyl group in one molecule of 0.05 to 0.15 mol / 100 g; (d) an adhesive constituent; and (e) an organic peroxide. A heat-conductive composite includes heat-conductive adhesive members formed from the heat-conductive silicone adhesive composition on both sides of a reinforcement material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive silicone adhesive composition and a thermally conductive composite. [Background technology]

[0002] Semiconductors such as transistors used in electronic devices and LED elements used as light sources for lighting etc. are generating large amounts of heat as they become more powerful, faster, smaller, and more integrated. The temperature rise in the device due to this heat can cause malfunctions or even destruction of the device. Therefore, many heat dissipation methods and heat dissipation materials used for these methods have been proposed to suppress the temperature rise of semiconductors during operation.

[0003] Conventionally, in electronic devices, heat generated by semiconductors is dissipated to the outside via a thermally conductive material to a cooling component such as a heat sink or housing made of a metal plate with high thermal conductivity. Thermally conductive sheets with insulating properties are often used as the thermally conductive material. Screws and clips are used to fasten the cooling component to the semiconductor. The thermally conductive sheet between them is also fastened by pressure from the screws or clips. However, fastening methods using screws and clips require many parts and processes, resulting in very poor manufacturing efficiency. Furthermore, components such as screws and clips hinder the miniaturization and thinning of electronic devices themselves, which is a major disadvantage in terms of product design.

[0004] Therefore, a method has been considered in which adhesive properties are imparted to a thermally conductive sheet interposed between a cooling member and a semiconductor, thereby fixing the housing and semiconductor element. Specifically, an adhesive-coated thermally conductive sheet can be produced by applying an adhesive to both sides of the thermally conductive sheet. However, because the adhesive itself does not have thermal conductivity, the thermal conductivity of an adhesive-coated thermally conductive sheet is significantly reduced. For example, Patent Documents 1, 2, and 3 disclose thermally conductive adhesive tapes that use a thermally conductive filler in the adhesive. Patent Document 4 also discloses a thermally conductive silicone adhesive tape that uses silicone for its heat resistance, cold resistance, and durability.

[0005] However, conventional adhesive tapes have poor adhesive strength compared to general adhesive materials, posing challenges in terms of screwless installation. Furthermore, single-layer adhesive tapes also have room for improvement in terms of workability, insulation, and strength. On the other hand, adhesive tapes are characterized by the fact that they can achieve better adhesive strength than pressure-sensitive adhesive tapes by applying heat and pressure. However, in order to achieve sufficient adhesive strength, a heating process under high pressure is generally required, which means that they cannot be used on heat dissipation components that are sensitive to pressure.

[0006] On the other hand, some types of heat-curing adhesives that are not in sheet or tape form also have high adhesion to heat-dissipating components, providing high adhesive strength and heat dissipation performance. However, they have issues such as complicated application processes, inferior workability and reworkability compared to adhesive (bonding) sheets and tapes, and the risk of voids being introduced. Furthermore, refrigerated storage is often recommended for addition-curing adhesives to prevent loss of adhesive strength over time, which complicates quality control and leaves room for improvement. Furthermore, when it comes to adhesive (bonding) sheets and tapes, users are strongly demanding products that do not significantly lose performance even in temperatures of approximately 40°C, taking into account product transportation by sea and storage in outdoor warehouses. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-034652 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-062220 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-121529 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-260798 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an object of the present invention is to provide a thermally conductive silicone adhesive composition that has good handling properties, can obtain sufficient adhesive strength, and is also excellent in the storage stability of the adhesive strength. Another object is to provide a thermally conductive composite excellent in strength and insulation properties.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above object, the present inventors have found that the following thermally conductive silicone adhesive composition can achieve the above object, and thus have completed the present invention. That is, the present invention provides the following thermally conductive silicone adhesive composition and a thermally conductive composite using the composition.

[0010] [1] A thermally conductive silicone adhesive composition containing the following components (a) to (e). (a) Linear or branched organopolysiloxane having an average degree of polymerization of 100 to 20,000: 100 parts by mass (b) Thermally conductive filler: 1,300 to 7,500 parts by mass (c) An organopolysiloxane composed of a component (c-1) represented by the following general formula (1) and having 0.05 to 0.15 mol / 100 g of alkenyl groups in one molecule and a component (c-2) represented by the following general formula (2): 150 to 600 parts by mass

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[10] The thermally conductive composite according to [9], wherein the synthetic resin is at least one selected from aromatic polyimide resins, polyamide resins, polyamideimide resins, polyester resins, and fluororesins.

[11] The thermally conductive composite according to any one of [6] to

[10] , wherein a substrate whose surface has been treated with a release agent is further laminated on the outermost layer of the thermally conductive adhesive member.

[12]

[11] The thermally conductive composite according to

[11] , wherein the release agent is a fluorine-modified silicone having a fluorine substituent bonded to the main chain. [Effects of the Invention]

[0011] The thermally conductive silicone adhesive composition of the present invention is easy to handle and can be easily applied to heat-dissipating components. Furthermore, the thermally conductive silicone adhesive composition provides desirable thermal conductivity between a heat-generating element and a heat-dissipating component, and exhibits good adhesive strength, enabling strong fixation between the components. Furthermore, when thermocompression-bonding (bonding) the composition to a heat-dissipating component, a high-pressure curing process is not required; the composition cures by leaving it at high temperature for a certain period of time, achieving sufficient adhesive strength, making it suitable for bonding a wide range of heat-dissipating components. The composition also has excellent storage stability, suppressing deterioration in adhesive strength over time. Furthermore, by laminating thermally conductive adhesive layers formed from the thermally conductive silicone adhesive composition on both sides of a reinforcing layer to form a thermally conductive composite, it is possible to improve strength and insulating properties. Therefore, the thermally conductive silicone adhesive composition of the present invention is highly useful as a thermally conductive component interposed between a heat-generating element and a heat-dissipating component, transferring heat generated by the heat-generating element to the heat-dissipating component and securing the component. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The thermally conductive silicone adhesive composition of the present invention is characterized by comprising: (a) a linear or branched organopolysiloxane having an average degree of polymerization of 100 to 20,000; (b) a thermally conductive filler; (c) an organopolysiloxane containing a component having an alkenyl group content per molecule of 0.05 to 0.15 mol / 100 g; (d) an adhesive component; and (e) an organic peroxide.

[0013] (a) Organopolysiloxane Component (a) is a linear or branched organopolysiloxane having an average degree of polymerization of 100 to 20,000, and is preferably an organopolysiloxane represented by the following average composition formula (7). [ka] (In formula (7), R is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, and x is a positive number of 1.98 to 2.02.)

[0014] In the above formula (7), R is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms. Examples of the monovalent hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, and butyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl, allyl, butenyl, and hexenyl; aryl groups such as phenyl and tolyl; and chloromethyl and trifluoropropyl groups in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups have been substituted with halogen atoms. Of these, methyl, vinyl, phenyl, and trifluoropropyl groups are preferred.

[0015] The organopolysiloxane of formula (7) above may or may not have alkenyl groups in one molecule. When the organopolysiloxane does not have alkenyl groups, it is preferred that 50% or more of the total number of substituents R in the organopolysiloxane of formula (7) above be methyl groups, more preferably 80% or more, and particularly preferably all of the substituents R are methyl groups.

[0016] Furthermore, when the organopolysiloxane of formula (7) above has alkenyl groups, it is preferable that the number of alkenyl groups per molecule is 2 or more, more preferably 2 to 20, and particularly preferably 2 to 10. With regard to the substituents R other than alkenyl groups, it is preferable that 50% or more, and more preferably 80% or more of the total number of substituents R in the organopolysiloxane of formula (7) above are methyl groups.

[0017] (a) The organopolysiloxane is preferably linear, but may have some branching as long as the rubber strength as a thermally conductive adhesive is not impaired, and may also be a mixture of two or more types of organopolysiloxanes with different molecular structures or degrees of polymerization. Furthermore, the organopolysiloxane has an average degree of polymerization of 100 to 20,000, preferably 200 to 10,000. The average degree of polymerization is a value determined as a number-average degree of polymerization in terms of polystyrene by gel permeation chromatography (GPC). [Measurement conditions] Developing solvent: tetrahydrofuran (THF) Flow rate: 0.6mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-H TSKgel SuperH4000(6.0mmI.D.×15cm×1) TSKgel SuperH3000(6.0mmI.D.×15cm×1) TSKgel SuperH2000(6.0mmI.D.×15cm×1) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 50 μL (2.0% by mass THF solution)

[0018] The content of component (a) in the thermally conductive silicone adhesive composition of the present invention is preferably 1 to 25 mass %, and more preferably 5 to 20 mass %.

[0019] (b) Thermally conductive filler The thermally conductive filler (b) may be any known filler used in thermally conductive silicone compositions, preferably one or more selected from the group consisting of metals, metal oxides, and metal nitrides. Examples of known thermally conductive fillers include non-magnetic metals such as copper and aluminum, metal oxides such as alumina, silica, magnesia, red iron oxide, beryllia, titania, and zirconia, and metal nitrides such as aluminum nitride, silicon nitride, and boron nitride. The thermally conductive filler should have an average particle size of 0.1 to 70 μm, preferably 0.5 to 60 μm, and more preferably 1 to 50 μm. One type of thermally conductive filler may be used alone, or multiple types may be used in combination. Two or more types of particles with different average particle sizes may also be used. In the present invention, the average particle size is the volume average particle size, measured using a Microtrac particle size distribution analyzer MT3300EX (Nikkiso Co., Ltd.).

[0020] The thermally conductive filler may be subjected to various known surface treatments as long as the effects of the present invention, such as thermal conductivity, are not significantly impaired. Specific examples of such surface treatments include treatment with a coupling agent such as a silane or titanate coupling agent, and plasma treatment.

[0021] The amount of the thermally conductive filler is 1,300 to 7,500 parts by mass, preferably 2,000 to 6,000 parts by mass, per 100 parts by mass of component (a). If the amount of the thermally conductive filler exceeds 7,500 parts by mass, the thermally conductive adhesive member (thermally conductive adhesive layer) may become brittle, resulting in reduced workability. On the other hand, if the amount is less than 1,300 parts by mass, the desired thermal conductivity may not be achieved in the thermally conductive adhesive member (thermally conductive adhesive layer).

[0022] (c) Organopolysiloxane The organopolysiloxane of component (c) is an organopolysiloxane composed of the following components (c-1) and (c-2), and functions to impart cohesive force to the thermally conductive adhesive member (thermally conductive adhesive layer), imparting workability, and obtaining good adhesive strength in the thermally conductive adhesive member (thermally conductive adhesive layer) after curing.

[0023] (c-1) (Component (c-1) is an organopolysiloxane represented by the following general formula (1), and the alkenyl group in one molecule is 0.05 to 0.15 mol / 100 g.) [Chemical formula] (In formula (1), R 1 is independently a group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms, and R 2 is independently an alkenyl group having 2 to 8 carbon atoms. 0 < a1 ≤ 10, 0 < b1 ≤ 10, 0 ≤ c1 ≤ 10, 0 ≤ d1 ≤ 10, 0 ≤ e1 ≤ 10. However, it is assumed to satisfy the range of 0.5 ≤ a1 / (d1 + e1) ≤ 2.0.)

[0024] (c-2) (Component (c-2) is an organopolysiloxane represented by the following general formula (2).) [Chemical formula] (In formula (2), R<00000​​​​​​is a group independently selected from an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms. Specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, cyclohexyl group, heptyl group; aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group; aralkyl groups such as benzyl group, phenethyl group; halogen-substituted alkyl groups such as chloromethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, etc. are mentioned. Particularly, a methyl group and a vinyl group are preferred.

[0026] R 2 is independently an alkenyl group having 2 to 8 carbon atoms. Specifically, vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, cyclohexenyl group, heptenyl group, etc. are mentioned. Particularly, a vinyl group is preferred.

[0027] In formula (1), 0 < a1 ≤ 10, preferably 1 ≤ a1 ≤ 5. Also, 0 < b1 ≤ 10, preferably 1 ≤ b1 ≤ 5. Also, 0 ≤ c1 ≤ 10, preferably 0 ≤ c1 ≤ 5. Also, 0 ≤ d1 ≤ 10, preferably 0 ≤ d1 ≤ 5. And 0 ≤ e1 ≤ 10, preferably 1 ≤ e1 ≤ 5. However, it is assumed to satisfy the range of 0.5 ≤ a1 / (d1 + e1) ≤ 2.0, preferably the range of 0.6 ≤ a1 / (d1 + e1) ≤ 1.8, and more preferably the range of 0.7 ≤ a1 / (d1 + e1) ≤ 1.5. When a1 / (d1 + e1) is less than 0.5, it becomes difficult to highly fill the heat-conductive filler of component (b), and the thermal conductivity of the heat-conductive adhesive member (heat-conductive adhesive layer) may decrease. Also, when a1 / (d1 + e1) exceeds 2.0, the cohesive force of the heat-conductive adhesive member (heat-conductive adhesive layer) decreases, and the workability may decrease.

[0028] (Component (c-1)) has an alkenyl group content of 0.05 to 0.15 mol / 100 g in one molecule, preferably 0.06 to 0.14 mol / 100 g, and more preferably 0.07 to 0.12 mol / 100 g. If the alkenyl group content in one molecule is less than 0.05 mol / 100 g, it may be difficult to obtain sufficient adhesive strength in the thermally conductive adhesive member (thermally conductive adhesive layer), which is not preferable. If it is more than 0.15 mol / 100 g, the thermally conductive adhesive member (thermally conductive adhesive layer) becomes hard and brittle, and the workability may deteriorate, which is not preferable.

[0029] In formula (2), R 1 is independently a group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms, 0 < a2 ≤ 10, preferably 1 ≤ a2 ≤ 5. Also, 0 ≤ c2 ≤ 10, preferably 0 ≤ c2 ≤ 5. Also, 0 ≤ d2 ≤ 10, preferably 0 ≤ d2 ≤ 5. And 0 < e2 ≤ 10, preferably 1 ≤ e2 ≤ 5. However, it satisfies the range of 0.7 ≤ a2 / e2 ≤ 2.5, preferably the range of 0.8 ≤ a2 / e2 ≤ 2.2, and more preferably the range of 0.9 ≤ a2 / e2 ≤ 2.0.

[0030] When a2 / e2 is less than 0.8, it becomes difficult to highly fill the thermally conductive filler of component (b), and the thermal conductivity of the thermally conductive adhesive member (thermally conductive adhesive layer) may decrease. Also, when a2 / e2 exceeds 2.5, the cohesive force of the thermally conductive adhesive member (thermally conductive adhesive layer) decreases, and the desired adhesive strength may not be obtained.

[0031] R 1 is most preferably all methyl groups for reasons such as cost, availability, chemical stability, and environmental load, unless special properties such as solvent resistance are required. When the organopolysiloxane of component (c) is solid, it can be used as a toluene solution of 50 to 70% by mass. The kinematic viscosity at 25°C in that case is 10 to 500 mm 2 / s, preferably 100 to 250 mm2 The kinematic viscosity is a value measured at 25°C using a Cannon-Fenske viscometer as specified in JIS Z8803:2011.

[0032] How to measure the ratio of M-units, T-units and Q-units The trifunctional R 1 SiO 3 / 2 Units (T units) and tetrafunctional SiO 4 / 2 At least one branched siloxane unit selected from the group consisting of a monofunctional R 1 3SiO 1 / 2 The ratio of the unit (M unit), i.e., the value of a1 / (d1+e1) in the component (c-1) and the value of a2 / e2 in the component (c-2) are 29 It can be determined by Si-NMR. 29 There are no particular limitations on the method for preparing a sample for Si-NMR, but for example, a sample can be prepared by dissolving 1 part by mass of organopolysiloxane in 3 parts by mass of deuterated chloroform.

[0033] The amount of organopolysiloxane (c) is 150 to 600 parts by mass, preferably 170 to 550 parts by mass, and more preferably 200 to 500 parts by mass per 100 parts by mass of component (a). If the amount of component (c) added is less than 150 parts by mass, the thermally conductive adhesive member (thermally conductive adhesive layer) may not have the desired adhesive strength. If it exceeds 600 parts by mass, the thermally conductive adhesive member (thermally conductive adhesive layer) may become brittle and lack flexibility, which may reduce workability. Component (c) itself is a solid or viscous liquid at room temperature, and can be used dissolved in a solvent. In this case, the amount added to the composition should be adjusted so that the resin content excluding the solvent falls within the above range.

[0034] The organopolysiloxane of component (c) is formed by combining the above-mentioned components (c-1) and (c-2). In this case, the amount of component (c-1) is preferably 10 to 60 mass% and more preferably 15 to 50 mass% of the total amount of component (c). When the proportion of component (c-1) is within this range, good adhesive strength can be obtained.

[0035] (d) Adhesive component Component (d) is an adhesive component represented by the following structural formulas (3) and (4), which has a triazine skeleton and contains an alkenyl group and a trialkoxy group. Component (d) not only exhibits good wettability with the adherend interface and functions to increase the adhesive strength of the thermally conductive adhesive member (thermally conductive adhesive layer), but also contributes to improving the storage stability of the adhesive strength of the thermally conductive adhesive member (thermally conductive adhesive layer) compared to known organohydrogenpolysiloxane-based adhesive components. [ka] (In formula (3), R 6 is an alkyl group having 1 to 5 carbon atoms, and n is a number from 1 to 12. [ka] (In formula (4), R 6 is an alkyl group having 1 to 5 carbon atoms, and n is a number from 1 to 12.

[0036] In the above formulas (3) and (4), R 6 are independently monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms, but do not contain aliphatic unsaturated bonds such as alkenyl groups. Examples of monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, and isopropyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and aralkyl groups such as benzyl, phenylethyl, and phenylpropyl. Among these, alkyl and aryl groups are preferred, and methyl is more preferred. In the above formulas (3) and (4), n is independently 1 to 12, preferably 1 to 10, and more preferably 1 to 8. When n is within this range, the desired adhesive strength of the thermally conductive adhesive member (thermally conductive adhesive layer) can be obtained.

[0037] The blending amount of component (d) is 0.5 to 20 parts by mass, preferably 1 to 15 parts by mass, per 100 parts by mass of component (a). If the amount of component (d) is less than 0.5 parts by mass, the wettability to the adherend may decrease, and the adhesive strength of the thermally conductive adhesive member (thermally conductive adhesive layer) may decrease. If the amount is more than 20 parts by mass, the excess adhesive component may weaken the thermally conductive adhesive member (thermally conductive adhesive layer), resulting in a decrease in adhesive strength. The adhesive component may be used alone or in combination of two or more.

[0038] (e) Organic peroxide Component (e) is an organic peroxide that decomposes under specific conditions to generate free radicals, and functions to promote the curing of the thermally conductive adhesive member (thermally conductive adhesive layer) at high temperatures and increase the adhesive strength. The organic peroxide may be any conventionally known organic peroxide, and is not particularly limited, and may be used alone or in appropriate combination of two or more. Examples of peroxyketals include 1,1-di(t-butylperoxy)cyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane; hydroperoxides such as p-menthane hydroperoxide and diisopropylbenzene hydroperoxide; dialkyl peroxides such as dicumyl peroxide and t-butylcumyl peroxide; diacyl peroxides such as dibenzoyl peroxide and disuccinic acid peroxide; peroxyesters such as t-butyl peroxyacetate and t-butyl peroxybenzoate; and peroxydicarbonates such as diisopropyl peroxydicarbonate. In particular, the use of peroxyketals, hydroperoxides, dialkyl peroxides, and peroxyesters, which have relatively high decomposition temperatures, is preferred from the standpoint of ease of handling and storage. These organic peroxides may be diluted with any organic solvent, hydrocarbon, liquid paraffin, inert solid, or the like.

[0039] The blending amount of component (e) is 1 to 40 parts by mass, preferably 5 to 30 parts by mass, per 100 parts by mass of component (a). If the amount of component (e) is less than 1 part by mass, the thermally conductive adhesive member (thermally conductive adhesive layer) may not be cured sufficiently when cured after being fixed to the heat dissipation member, resulting in reduced adhesive strength. If the amount of component (e) is more than 40 parts by mass, the thermally conductive adhesive member (thermally conductive adhesive layer) may be significantly affected by decomposition residues when cured, resulting in reduced adhesive strength.

[0040] (f) Surface treatment agent The thermally conductive silicone adhesive composition of the present invention may further contain a surface treatment agent (component (F)). Component (f) functions to uniformly disperse the thermally conductive filler (b) throughout the organopolysiloxane matrix (a) during preparation of the composition. Component (f) is an alkoxysilane compound (f-1) represented by the following general formula (5) and / or a dimethylpolysiloxane (f-2) represented by the following general formula (6). In other words, component (f-1) and component (f-2) may be used singly or in combination.

[0041] (f-1) Alkoxysilane compound represented by the following general formula (5): [ka] (In formula (5), R 3 are independently alkyl groups having 6 to 15 carbon atoms, and R 4 are independently alkyl groups having 1 to 5 carbon atoms, and R 5 are independently an alkyl group having 1 to 6 carbon atoms, m is a number from 1 to 3, and n is a number from 0 to 2, with the proviso that m+n is a number from 1 to 3.

[0042] (f-2) Dimethylpolysiloxane represented by the following general formula (6): [ka] (In formula (6), R 5 are independently alkyl groups having 1 to 6 carbon atoms, and p is a number from 5 to 100.

[0043] In the above general formula (5), R 3 Examples of the alkyl group represented by R include a hexyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, and a tetradecyl group. 3 When the number of carbon atoms in the alkyl group represented by the formula satisfies the range of 6 to 15, the wettability of the above-mentioned component (b) is sufficiently improved, and the handling properties of the composition become good.

[0044] R 4is an alkyl group having 1 to 5 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group.

[0045] R 5 is an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and a butyl group. Of these, a methyl group is most preferred.

[0046] The amount of component (f) is preferably 1 to 40 parts by mass, more preferably 2 to 35 parts by mass, and even more preferably 3 to 30 parts by mass, per 100 parts by mass of component (a). If the amount of component (f) is less than 1 part by mass, it will be difficult to highly fill component (b) into component (a), and if it exceeds 40 parts by mass, the adhesive strength of the thermally conductive adhesive member (thermally conductive adhesive layer) may be significantly reduced.

[0047] Other ingredients In addition to the above-mentioned components (a) through (f), pigments and dyes for coloring, flame retardants, and various other additives for improving functionality can also be added to the thermally conductive silicone adhesive composition of the present invention, provided that the addition does not impair the objectives of the present invention.

[0048] Method for producing the composition The thermally conductive silicone adhesive composition of the present invention is prepared by uniformly mixing the above-mentioned components (a) to (e), optional component (f), and other components. The mixing method may be any conventionally known method. Preferably, components (a), (b), and (c) and optional components (component (f) and other components) are mixed together, followed by mixing components (d) and (e).

[0049] Manufacturing method of thermally conductive adhesive member (thermally conductive adhesive layer) The thermally conductive silicone adhesive composition of the present invention can be applied to a substrate (described below) in the form of a thin film tape, molded, and dried to obtain a thermally conductive adhesive member (thermally conductive adhesive layer) for the thermally conductive composite of the present invention. Drying conditions are 60 to 100°C for 5 to 20 minutes, preferably 70 to 90°C for 5 to 15 minutes. If the drying conditions are outside the above ranges, residual solvent may reduce thermal conductivity, or the curing reaction of the composition may proceed, making it difficult to adhere the dried thermally conductive adhesive member (thermally conductive adhesive layer) to a heat-dissipating component. The thermally conductive adhesive member (thermally conductive adhesive layer) of the present invention can firmly bond the heat-dissipating member and the heat-generating member by mounting an uncured thermally conductive silicone adhesive composition between the heat-dissipating member and the heat-generating member and then subjecting the composition to a heat-curing treatment. The thickness of the thermally conductive adhesive member (thermally conductive adhesive layer) after curing is preferably 50 to 300 μm, and more preferably 75 to 250 μm. If the thickness of the thermally conductive adhesive member (thermally conductive adhesive layer) is less than 50 μm, it is difficult to handle and the adhesive strength decreases. On the other hand, if the thickness of the thermally conductive adhesive member (thermally conductive adhesive layer) exceeds 300 μm, it is difficult to obtain the desired thermal conductivity. Furthermore, when coating and molding, a solvent such as toluene or xylene can be added to adjust the viscosity.

[0050] The thermally conductive adhesive member (thermally conductive adhesive layer) of the present invention may have a substrate (such as polyethylene-laminated paper or PET film) surface-treated with a release agent as a separator film. That is, both sides of the thermally conductive adhesive member (thermally conductive adhesive layer) may be protected with a release-treated film. By laminating a separator film to the thermally conductive adhesive member (thermally conductive adhesive layer), handling properties such as transportation and cutting to a fixed length can be improved. In this case, the peel strength of the separator film can be adjusted by changing the amount and type of release agent or the film material. Examples of such separator films include polyethylene-laminated paper and PET film that have been subjected to a release treatment with a cured coating of fluorine-modified silicone in which fluorine substituents, such as perfluoroalkyl groups or perfluoropolyether groups, are bonded to the main chain. The perfluoropolyether group can be represented by the following formulas (8) to (10): [ka] (p is 1 to 5, and q is 3 to 10)

[0051] As commercially available products of the fluorine-modified silicone, for example, X-70-201, X-70-258, X-41-3035 manufactured by Shin-Etsu Chemical Co., Ltd. can be used.

[0052] Examples of molding methods include, but are not limited to, methods in which a liquid material (thermally conductive silicone adhesive composition) is applied to a substrate (polyethylene-laminated paper, PET film, etc.) using a bar coater, knife coater, comma coater, spin coater, etc.

[0053] The thermally conductive adhesive member (thermally conductive adhesive layer) of the present invention is in the form of a thin tape or sheet, can be easily placed in a desired location, and exhibits excellent thermal conductivity. Furthermore, when the above-mentioned separator films are provided on both sides of the thermally conductive adhesive member (thermally conductive adhesive layer), one separator film is peeled off and the member is attached to a heat-generating electronic component or a heat-dissipating component, and then the remaining separator film is peeled off and the member is attached to a cooling component, etc., thereby bonding the cooling component and the heat-generating electronic component or the heat-dissipating component via the thermally conductive adhesive member (thermally conductive adhesive layer) (transfer method).

[0054] Furthermore, the thermally conductive adhesive member (thermally conductive adhesive layer) of the present invention provides good adhesion between components and enables strong fixation by heat generation by a heating element or by heat treatment after mounting. The heat treatment after mounting is performed at 130°C to 190°C for 15 to 90 minutes, preferably 150°C to 170°C for 20 to 60 minutes. Since pressure is not particularly required during heating, it can also be used for heat dissipation components that are sensitive to pressure.

[0055] Furthermore, the thermally conductive composite of the present invention is obtained by bonding a reinforcing material (reinforcing layer) described below to the thermally conductive adhesive member (thermally conductive adhesive layer) in order to reinforce strength and insulating properties. The reinforcing material (reinforcing layer) in the present invention is preferably glass cloth or a synthetic resin film which is excellent in heat resistance and electrical insulation, as well as being flexible and having high mechanical strength, and can be appropriately selected from known substrates.

[0056] The glass cloth preferably has a thickness of 10 μm or more and 50 μm or less, and a weight of 45 g / m 2 More preferably, the thickness is 20 μm or more and 40 μm or less, and the weight is 30 g / m 2The following is preferred. Glass cloth has a relatively low thermal conductivity, so a thinner thickness is preferable in consideration of thermal conductivity. However, if it is too thin, the strength decreases and the desired reinforcing effect cannot be obtained. Alternatively, moldability becomes poor, so a thickness within the above-mentioned range is preferred. The glass cloth may be pre-sealed with a silicone composition that forms a thermally conductive adhesive member (thermally conductive adhesive layer). Alternatively, the thermally conductive adhesive member (thermally conductive adhesive layer) may be directly attached without pre-sealing. In the latter case, thermocompression bonding is preferred because it makes it easier for the thermally conductive adhesive member (thermally conductive adhesive layer) to fill the holes in the cloth.

[0057] The synthetic resin film has a thickness of 2 to 30 μm, preferably in the range of 5 to 20 μm. If the synthetic resin film is thicker than 30 μm, the thermal conductivity of the thermally conductive composite of the present invention will be impaired, and if it is thinner than 2 μm, the strength required as a reinforcing material (reinforcing layer) will be insufficient and the withstand voltage characteristics will be deteriorated, resulting in insufficient electrical insulation performance. Furthermore, the synthetic resin film is preferably a film without holes that would reduce the withstand voltage characteristics. Examples of the synthetic resin for the synthetic resin film include aromatic polyimides, polyamides, polyamideimides, polyesters such as polyethylene naphthalate, and fluororesins such as polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers. When using the above fluororesins as the synthetic resin, it is preferable to subject the surface of the film to a chemical etching treatment using a metal sodium / naphthalene-based treatment solution in order to improve the adhesiveness of the thermally conductive composite. The synthetic resin film is preferably a heat-resistant film having a melting point of 200° C. or higher, preferably 250° C. or higher, so that its mechanical strength is not reduced by thermal deformation. An example of a heat-resistant synthetic resin film having a melting point of 250° C. or higher is Kapton (registered trademark) MT (trade name, manufactured by DuPont-Toray Co., Ltd.), which is an aromatic polyimide film.

[0058] Method for manufacturing thermally conductive composite The method for producing a thermally conductive composite having a thermally conductive adhesive member (thermally conductive adhesive layer) and a reinforcing material (reinforcing layer) according to the present invention will be described in detail below. The method for producing a thermally conductive composite of the present invention involves laminating the above-mentioned thermally conductive adhesive member (thermally conductive adhesive layer) as an outer layer on both sides of a reinforcing material (reinforcing layer) by room temperature compression bonding or thermocompression bonding. The lamination method is not particularly limited, and may be carried out as appropriate according to a conventionally known method for producing a composite. In the case of room temperature pressure bonding, for example, the thermally conductive adhesive member (thermally conductive adhesive layer) formed in advance on the separator film may be transferred to both sides of the reinforcing material (reinforcing layer). In the case of thermocompression bonding, the pressing jig is heated to 50 to 100° C. and pressure-bonding and transfer are carried out in the same manner. In addition to press-bonding, roll-bonding and the like may also be used for the pressure-bonding. Alternatively, the thermally conductive composite may be produced by diluting the thermally conductive silicone adhesive composition with a solvent and applying the diluted composition to both sides of the reinforcing material (reinforcing layer) and drying it.

[0059] When glass cloth is used as the reinforcing material (reinforcing layer), the glass cloth may be previously sealed with the above-mentioned thermally conductive silicone adhesive composition. When applying the thermally conductive silicone adhesive composition to the glass cloth, the composition is continuously applied to the glass cloth using a coating device such as a comma coater, knife coater, or kiss coater equipped with a drying oven, a heating oven, and a winding device, and the solvent is then dried and evaporated, and the composition is heated and cured at 130 to 170°C, preferably 140 to 160°C, for 20 to 40 minutes to obtain glass cloth sealed with the silicone composition. Alternatively, an unsealed glass cloth may be used, and the thermally conductive adhesive member (thermally conductive adhesive layer) formed on the separator film may be transferred to the reinforcing material (reinforcing layer) while simultaneously laminating the thermally conductive adhesive member (thermally conductive adhesive layer). In this case, the transfer is preferably performed by heating the press jig to 50 to 100°C. Pressure bonding may be performed by press bonding or roll bonding. If the transfer temperature is lower than 50°C, the thermally conductive adhesive member (thermally conductive adhesive layer) may not adhere well to the glass cloth, and the mesh of the cloth may not be filled, resulting in reduced insulation and thermal conductivity. If the temperature exceeds 100°C, the thermally conductive adhesive member (thermally conductive adhesive layer) may harden. The overall thickness of the thermally conductive composite is preferably 100 to 450 μm, more preferably 150 to 400 μm. As with the thermally conductive adhesive member (thermally conductive adhesive layer) described above, the thermally conductive composite can be heated by a heating element or subjected to heat treatment during use to provide good adhesion between the components, enabling them to be firmly fixed together. [Example]

[0060] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The components (a) to (f) constituting the thermally conductive adhesive layer used in the following examples and comparative examples are as follows.

[0061] (a) Ingredients: (a-1) Dimethylpolysiloxane raw rubber having an average degree of polymerization of 7,000 (a-2) Dimethylpolysiloxane oil having an average degree of polymerization of 650 and vinyl groups at both ends

[0062] (b) Ingredients: (b-1) Granular alumina having a volume average particle size of 1 μm (b-2) Granular aluminum nitride having a volume average particle size of 1 μm (b-3) Spherical alumina with a volume average particle size of 20 μm (b-4) Granular aluminum nitride having a volume average particle size of 20 μm (b-5) Spherical alumina with a volume average particle size of 45 μm

[0063] (c) Ingredients: (c-1) A toluene solution (50% by mass, kinematic viscosity 10 mm) of an organopolysiloxane resin represented by the following formula (1'), in which 0.08 mol / 100 g of alkenyl groups are bonded only to D units and the M / Q (molar ratio) is 0.9, is prepared. 2 / s) [ka] (In formula (1'), R 1' is a methyl group, and R 2' is a vinyl group, and a1 ' is 1.8, and b1 ' is 1 and c1 ' is 1 and d1 ' is 1 and e1 ' is 1 and a1 ' / (d1 ' +e1 ' )=0.9)

[0064] (c-2) The molar ratio M / Q was 1.2, and all of the substituents bonded to the silicon atoms of the M units were methyl groups. 2 / s) [ka] (In formula (2'), R 1' are all methyl groups, and a2 ' is 1.2 and c2 ' is 0, and d2 ' is 0, and e2 ' is 1 and a2 ' / e2 ' =1.2)

[0065] (d) Ingredients: (d-1): Adhesive component represented by the following structural formula [ka] (d-2): Adhesive component represented by the following structural formula [ka] (d-3): Adhesive component represented by the following structural formula [ka] (d-4): For comparative example [ka]

[0066] (e) Ingredients: 2,5-dimethyl-2,5-di(t-butylperoxy)hexane

[0067] (f) Ingredients: KBM-3103C (decyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0068] The above components (a), (b), (c), and (f) were charged into a Shinagawa-type universal mixer in the amounts shown in Tables 1 and 2 and mixed for 60 minutes. Next, components (d) and (e) were added in the amounts shown in Tables 1 and 2 and mixed uniformly to obtain a thermally conductive silicone adhesive composition. However, in Comparative Example 1, component (d) was not added, and 5 parts by mass of KF-99P, a known organohydrogenpolysiloxane manufactured by Shin-Etsu Chemical Co., Ltd., was added as the adhesive component.

[0069] [Production of thermally conductive adhesive material (thermally conductive adhesive layer)] A fluorine-treated PET film (separator film) was produced by subjecting the surface of a 38 μm-thick PET film (separator film) to release treatment with a release agent (X-41-3035 (manufactured by Shin-Etsu Chemical Co., Ltd.)). An appropriate amount of toluene was added to the thermally conductive silicone adhesive composition obtained above to prepare a toluene solution. The toluene solution was applied to the PET film (separator film), and the toluene was evaporated at 80°C to form a thermally conductive adhesive member (thermally conductive adhesive layer). The PET film (separator film) was then laminated on top of the thermally conductive adhesive member (thermally conductive adhesive layer) to obtain a thermally conductive adhesive member (thermally conductive adhesive layer) with a thickness of 150 μm. This thickness is the thickness of the thermally conductive adhesive member (thermally conductive adhesive layer) only, and does not include the thickness of the separator films on both sides of the thermally conductive adhesive member (thermally conductive adhesive layer).

[0070] [Preparation of thermally conductive composite] A reinforcing material (reinforcing layer) was laminated on the thermally conductive adhesive member (thermally conductive adhesive layer) obtained by the above method by the following method to prepare a tape-shaped thermally conductive composite. The thermally conductive composite using glass cloth as the reinforcing material (reinforcing layer) was produced by thermocompressing a thermally conductive adhesive member (thermally conductive adhesive layer) to both sides of the glass cloth (30 μm) at 70°C. The thermally conductive composite, which uses aromatic polyimide resin as a reinforcing material (reinforcing layer), was produced by thermocompressing a thermally conductive adhesive member (thermally conductive adhesive layer) onto both sides of an aromatic polyimide resin (7.5 μm) at 70°C. The overall thickness of the thermally conductive composite having the thermally conductive adhesive member (thermally conductive adhesive layer) and the reinforcing material (reinforcing layer) is as shown in Tables 1 and 2. The thermally conductive composite was in the form of a tape, and measured 200 mm x 300 mm.

[0071] [Evaluation method] (1) Handling: When the thermally conductive adhesive member (thermally conductive adhesive layer) or the thermally conductive adhesive layer surface of the thermally conductive composite was attached to a heat dissipation member (aluminum heat sink), an evaluation was conducted to determine whether the desired adhesion could be obtained. The separator film on one side of the thermally conductive adhesive member (thermally conductive adhesive layer) or thermally conductive composite was peeled off, and the thermally conductive adhesive member (thermally conductive adhesive layer) portion was attached to an aluminum heat sink. Then, when the other separator film was peeled off, the attached thermally conductive adhesive member (thermally conductive adhesive layer) or thermally conductive composite was fixed to the heat sink without slipping, and the handling was evaluated based on whether or not it was fixed. Those that were fixed without slipping were marked with an O, and those that were displaced were marked with an X, and these are shown in the table.

[0072] (2) Thermal conductivity: The separator films on both sides of the thermally conductive adhesive member (thermally conductive adhesive layer) or thermally conductive composite was peeled off, sandwiched between aluminum plates, and evenly pressed. After heating and curing at 150°C for 1 hour using a dryer, the thermal resistance was measured using the laser flash method (ASTM E1461). The thermal conductivity was calculated using the usual method from the relationship between thickness and thermal resistance.

[0073] (3) Shear adhesive strength: A thermally conductive adhesive member (thermally conductive adhesive layer) or a thermally conductive composite having the thickness shown in the table was sandwiched between 10 mm x 10 mm aluminum plates, uniformly pressed, and then heat-cured in a dryer at 150°C for 1 hour. The shear stress of the obtained test piece against the aluminum plate at room temperature was measured using a Nordson 4000Plus bond tester. Furthermore, after storing the molded thermally conductive adhesive member (thermally conductive adhesive layer) or thermally conductive composite at 40°C for one month, the shear adhesive strength to the aluminum plate was measured again using the same method, and the change in adhesive strength was calculated as a reduction rate to evaluate the storage stability.

[0074] (4) Breakdown voltage: Based on JIS K6249:2003, the breakdown voltage of the thermally conductive adhesive member (thermally conductive adhesive layer) or thermally conductive composite from which the separator films on both sides had been peeled off was measured in air.

[0075] (5) Tensile strength: After peeling off the separator films on both sides, the tensile strength of the thermally conductive adhesive member (thermally conductive adhesive layer) or the thermally conductive composite was measured using an autograph in accordance with JIS K6249:2003.

[0076] [Table 1]

[0077] [Table 2]

[0078] In Examples 1 to 10, the thermally conductive silicone adhesive composition containing appropriate amounts of components (a) to (f) was molded into a thin film to produce a thermally conductive adhesive member (thermally conductive adhesive layer) or thermally conductive composite. These adhesive members were easy to handle, could be easily mounted on an adherend, and had good thermal conductivity. Furthermore, after heat curing, they exhibited good adhesive strength, and no significant decrease in adhesive strength was observed when stored at 40°C. In Comparative Example 1, the adhesive strength was significantly reduced after storage at 40°C due to the use of a known organohydrogenpolysiloxane as component (d). In Comparative Example 2, the amount of the adhesive component (d) blended was less than 1 part by mass, so the adhesive strength was lower than in Example 2. In Comparative Example 3, the blending amount of the thermally conductive filler (b) exceeded 7,500 parts by mass, so the thermally conductive adhesive member (thermally conductive adhesive layer) became brittle, and the handling properties and adhesive strength were reduced. In Comparative Example 4, the blending amount of the adhesive component (d) exceeded 20 parts by mass, so the thermally conductive adhesive member (thermally conductive adhesive layer) became brittle and the adhesive strength decreased. In Comparative Example 5, the blending amount of the silicone resin (component (c)) was less than 150 parts by mass, so the cohesive force of the thermally conductive adhesive member (thermally conductive adhesive layer) decreased, and the handling properties and adhesive strength decreased. In Comparative Example 6, the amount of the organic peroxide (component (e)) blended was less than 1 part by mass, and therefore the adhesive strength was lower than in Example 6. In Comparative Example 7, a composite was formed using the thermally conductive adhesive member (thermally conductive adhesive layer) of Comparative Example 1 and glass cloth, but similar to Comparative Example 1, the adhesive strength decreased significantly after storage at 40°C.

Claims

1. A thermally conductive silicone adhesive composition comprising the following components (a) to (e): (a) Linear or branched organopolysiloxane having an average degree of polymerization of 100 to 20,000: 100 parts by mass (b) Thermally conductive filler: 1,300 to 7,500 parts by mass (c) 150 to 600 parts by mass of an organopolysiloxane comprising a component (c-1) represented by the following general formula (1) and having an alkenyl group content per molecule of 0.05 to 0.15 mol / 100 g, and a component (c-2) represented by the following general formula (2): 【Chemical 1】 (In formula (1), R 1 are independently selected from alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and aralkyl groups having 7 to 10 carbon atoms; R 2 are independently alkenyl groups having 2 to 8 carbon atoms. 0<a1≦10, 0<b1≦10, 0≦c1≦10, 0≦d1≦10, and 0≦e1≦10, provided that the range of 0.5≦a1 / (d1+e1)≦2.0 is satisfied. 【Chemistry 2】 (In formula (2), R 1 are independently a group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms, and 0<a2≦10, 0≦c2≦10, 0≦d2≦10, and 0<e2≦10, provided that the range of 0.7≦a2 / e2≦2.5 is satisfied. (d) an adhesive component represented by the following structural formula (3) and / or an adhesive component represented by the following structural formula (4): 0.5 to 20 parts by mass 【Chemistry 3】 (In formula (3), R 6 is an alkyl group having 1 to 5 carbon atoms, and n is independently a number from 1 to 12. 【Chemistry 4】 (In formula (4), R 6 is an alkyl group having 1 to 5 carbon atoms, and n is independently a number from 1 to 12. (e) Organic peroxide: 1 to 40 parts by mass

2. 2. The thermally conductive silicone adhesive composition according to claim 1, wherein component (b) is at least one member selected from the group consisting of metals, metal oxides, and metal nitrides.

3. 3. The thermally conductive silicone adhesive composition according to claim 1, wherein the proportion of component (c-1) relative to the total amount of component (c) is 10 to 60 mass %.

4. 2. The thermally conductive silicone adhesive composition according to claim 1, wherein component (a) is a linear or branched organopolysiloxane containing two or more alkenyl groups per molecule.

5. 2. The thermally conductive silicone adhesive composition according to claim 1, further comprising 1 to 40 parts by mass of a component (f-1) represented by the following general formula (5) and / or a component (f-2) represented by the following general formula (6), per 100 parts by mass of component (a): 【Chemistry 5】 (In formula (5), R 3 are independently alkyl groups having 6 to 15 carbon atoms, and R 4 are independently alkyl groups having 1 to 5 carbon atoms, and R 5 are independently an alkyl group having 1 to 6 carbon atoms, m is a number from 1 to 3, and n is a number from 0 to 2, with the proviso that m+n is a number from 1 to 3. 【Chemistry 6】 (In formula (6), R 5 are independently alkyl groups having 1 to 6 carbon atoms, and p is a number from 5 to 100.

6. A thermally conductive composite having thermally conductive adhesive members formed from the thermally conductive silicone adhesive composition of claim 1 on both sides of a reinforcing material.

7. 7. The thermally conductive composite according to claim 6, wherein the thermally conductive adhesive member has a thermal conductivity of 2.0 W / m·K or more.

8. 7. The thermally conductive composite according to claim 6, wherein a thermally conductive adhesive member is laminated.

9. 7. The thermally conductive composite according to claim 6, wherein the reinforcing material is a synthetic resin or a glass cloth.

10. 10. The thermally conductive composite according to claim 9, wherein the synthetic resin is at least one selected from the group consisting of aromatic polyimide resins, polyamide resins, polyamideimide resins, polyester resins, and fluororesins.

11. 7. The thermally conductive composite according to claim 6, wherein a substrate whose surface has been treated with a release agent is further laminated on the outermost layer of the thermally conductive adhesive member.

12. 12. The thermally conductive composite according to claim 11, wherein the release agent is a fluorine-modified silicone having fluorine substituents bonded to the main chain.

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