Heat conductive spacer and heat conductive composition

Abstract

To provide a heat conductive spacer which is excellent in handleability.SOLUTION: A heat conductive spacer contains a thermosetting resin, and a heat conductive filler, wherein when elongation at a break point, which is subjected to a tension test using a dumbbell No.8 type according to JIS K 6251, is represented by Xa, and elongation at a maximum stress point is represented by Xb, the following expression (1): (Xa-Xb) / Xb≥1.0 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As heat-generating electronic components, such as central processing units (CPUs) in personal computers, become smaller and more powerful, the amount of heat generated per unit area by these components has become extremely large. This amount of heat can reach approximately 20 times that of an iron. To prevent these heat-generating electronic components from breaking down over the long term, they must be cooled. Metal heat sinks and housings are used for cooling. However, when a heat-generating electronic component is placed directly in contact with a heat sink, microscopic air exists at the interface, which can impede heat conduction. Therefore, to efficiently transfer heat, a thermally conductive material is often placed between the heat-generating electronic component and the heat sink.

[0003] Examples of thermally conductive materials include thermally conductive spacers, which are made by filling a thermosetting resin with a thermally conductive filler and molding it into a sheet, and thermally conductive grease, which is made by filling a fluid resin with a thermally conductive filler and can be spread or made into a thin film.

[0004] To date, thermally conductive spacers (see Patent Document 1) have been developed that have improved flexibility in addition to thermal conductivity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2023 / 162928 Summary of the Invention [Problem to be solved by the invention]

[0006] The thermally conductive spacer can be compressed and placed between the heat generating element and the heat sink. The thermally conductive spacer may crack or break when pulled or compressed during installation. Therefore, there is a need for a thermally conductive spacer that is easy to handle and less likely to crack or break when pulled or compressed during installation.

[0007] Therefore, an object of the present invention is to provide a thermally conductive spacer and a thermally conductive composition that are easy to handle. [Means for solving the problem]

[0008] As a result of intensive research to achieve the above-mentioned object, the inventors discovered that a thermally conductive spacer in which the elongation at the breaking point and the elongation at the maximum stress point have a predetermined relationship in a tensile test can solve the above-mentioned problem, and thus completed the present invention.

[0009] That is, the present invention is as follows. [1] a thermosetting resin and a thermally conductive filler; When a tensile test is performed on a dumbbell No. 8 in accordance with JIS K6251, the elongation at the breaking point is defined as Xa, and the elongation at the maximum stress point is defined as Xb. The following formula (1) is satisfied: (Xa-Xb) / Xb ≧1.0 (1) Thermally conductive spacer. [2] Thermal conductivity measured in accordance with ASTM D5470 is 2.5 W / m·K or greater. [1] The thermally conductive spacer according to the present invention. [3] Asker C hardness is 1 to 20. [1] or [2]. The thermally conductive spacer according to [1] or [2]. [4] the thermally conductive filler comprises polyhedral alumina; The thermally conductive spacer according to any one of [1] to [3]. [5] [1] to [4], for producing the thermally conductive spacer according to any one of [1] to [4], Thermally conductive compositions. [6] A thermosetting resin having a penetration of 80 to 150 is included. [5] The thermally conductive composition according to [5]. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a thermally conductive spacer and a thermally conductive composition that are easy to handle. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a stress-strain curve C of a thermally conductive spacer. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the gist of the present invention.

[0013] 1.Thermal conductive spacer The thermally conductive spacer of this embodiment contains a thermosetting resin and a thermally conductive filler, and satisfies the following formula (1) when the elongation at the breaking point in a tensile test using a dumbbell No. 8 in accordance with JIS K6251 is Xa and the elongation at the maximum stress point is Xb. (Xa-Xb) / Xb ≥ 1.0 (1).

[0014] Thermally conductive spacers are used in contact with uneven heating or radiating elements, compressed under pressure to improve adhesion between the heating and radiating elements, or tensioned during installation. The tension and compression vary depending on the application. In this case, if the thermally conductive spacer has poor conformability to the uneven surface and breaks under compression or tension, handling becomes a problem. On the other hand, flexibility and elongation are also important for thermally conductive spacers used under compression or tension. Therefore, improving the handleability of thermally conductive spacers is not sufficient simply by improving their tensile strength. While increasing the elongation at the maximum stress point is also an option to improve the handleability of thermally conductive spacers, if they break immediately after reaching the maximum stress point, it is difficult for the installer of the thermally conductive spacer to predict the level of tension required to cause breakage.

[0015] Therefore, the thermally conductive spacer of this embodiment is specified to satisfy the above formula (1). The above formula (1) will be explained using FIG. 1. FIG. 1 is a schematic diagram showing a stress-strain curve C of a thermally conductive spacer. As shown in FIG. 1, when strain ε is applied to the thermally conductive spacer, stress σ increases and reaches a maximum stress at point B where elongation is Xb. If strain ε is subsequently increased, the thermally conductive spacer breaks at point A where elongation is Xa. The left side of the above formula (1) is the value obtained by normalizing the elongation amount from elongation Xb at maximum stress point B to elongation Xa at breaking point A by elongation Xb. In other words, the above formula (1) specifies that the elongation Xa-Xb from the maximum stress point to the breaking point must be equal to or greater than the elongation Xb at maximum stress point B.

[0016] Thus, a thermally conductive spacer that satisfies the above formula (1) can elongate more than twice the elongation at the maximum stress point without breaking even after reaching the maximum stress point. Therefore, even when installing a thermally conductive spacer while pulling or compressing it, the installer can use the stress from the thermally conductive spacer as an indicator and predict that further pulling or compression may result in breakage. As described above, the thermally conductive spacer of this embodiment is easy to handle.

[0017] 1.1.Physical properties of thermally conductive spacers Tensile Test In this embodiment, the thermally conductive spacer satisfies the above formula (1), and therefore has excellent handleability. From the same viewpoint, the value of (Xa-Xb) / Xb is preferably 1.2 or more, 1.8 or more, 2.0 or more, 5.0 or more, 6.0 or more, or 7.0 or more. The upper limit of (Xa-Xb) / Xb is not particularly limited, and the value of (Xa-Xb) / Xb may be 20 or less, 18 or less, 15 or less, 12 or less, or 10 or less.

[0018] The value of the elongation Xa at break is not particularly limited, but is preferably 5.0 to 200 mm, 10 to 150 mm, 15 to 120 mm, 20 to 100 mm, 25 to 90 mm, or 30 to 80 mm.

[0019] The value of the elongation Xb at the maximum stress point is not particularly limited, but is preferably 0.5 to 100 mm, 1.0 to 80 mm, 1.5 to 60 mm, 2.0 to 50 mm, 2.5 to 40 mm, or 3.0 to 30 mm.

[0020] The difference (Xa-Xb) between the elongation Xa and the elongation Xb is not particularly limited, but is preferably 1 to 100 mm, 2 to 80 mm, 3 to 60 mm, 5 to 50 mm, 8 to 40 mm, 10 to 35 mm, or 15 to 30 mm.

[0021] When the values ​​of the elongation Xa and the elongation Xb and the difference between them are within the above ranges, the handleability of the thermally conductive spacer tends to be further improved.

[0022] In this embodiment, the stress (tensile strength) of the thermally conductive spacer at the maximum stress point is preferably 10 to 300 kPa, 15 to 200 kPa, or 20 to 150 kPa. When the tensile strength is 10 kPa or more, the thermally conductive spacer is prevented from breaking due to unexpected stress, and the handleability of the thermally conductive spacer is further improved. When the tensile strength is 300 kPa or less, the thermally conductive spacer can be stretched with an appropriate force, and the handleability of the thermally conductive spacer is further improved. Within the above range, the tensile strength of the thermally conductive spacer may be 30 kPa or more, 50 kPa or more, or 60 kPa or more.

[0023] In this embodiment, the tensile test of the thermally conductive spacer is performed using a dumbbell No. 8 in accordance with JIS K6251: 2023. More specifically, the measurement can be performed by the method described in the examples.

[0024] To keep the values ​​of elongation Xa and elongation Xb and the difference between them within the above ranges and satisfy the above formula (1), for example, the composition of the thermally conductive spacer can be adjusted. To increase the value of (Xa-Xb) / Xb, for example, at least one of the filling amount, particle size distribution, and specific surface area of ​​the thermally conductive filler can be adjusted, or the viscosity and penetration of the thermosetting resin can be adjusted, or polyhedral alumina can be used as the thermally conductive filler.

[0025] 1.1.2.Asker C hardness The thermally conductive spacer can be disposed between the heat generating element and the heat dissipating element so that the thermally conductive spacer is compressed. Therefore, from the viewpoint of mitigating physical impact on the heat generating element and the heat dissipating element, it is preferable that the flexibility of the thermally conductive spacer, in other words, its hardness, be within a certain range.

[0026] Therefore, the Asker C hardness of the thermally conductive spacer is preferably 1 to 20, 2 to 19, or 3 to 18. The Asker C hardness may be 5 or more, or 8 or more, or 15 or less, 12 or less, or 5 or less.

[0027] The Asker C hardness of the thermally conductive spacer can be measured at 25°C using an Asker C type spring hardness tester conforming to SRIS0101, and more specifically, can be measured by the method described in the examples.

[0028] The Asker C hardness can be adjusted to fall within the above range by, for example, adjusting the composition of the thermally conductive spacer, such as by changing the type of thermosetting resin or adjusting the content of the thermally conductive filler.

[0029] 1.1.3.Heat Conduction Properties The thermally conductive spacer of this embodiment is suitable for use as a thermally conductive heat dissipation material. Therefore, it is preferable that the thermal conductivity of the thermally conductive spacer be high. Specifically, the thermal conductivity measured in accordance with ASTM D5470 is preferably 2.5 W / m·K or more, 2.6 W / m·K or more, 2.8 W / m·K or more, or 3.0 W / m·K or more. While the upper limit of the thermal conductivity measured in accordance with ASTM D5470 is not particularly limited, the thermal conductivity may be, for example, 10 W / m·K or less, 8.0 W / m·K or less, 7.0 W / m·K or less, or 4.5 W / m·K or less.

[0030] The thermal conductivity of the thermally conductive spacer is measured in accordance with ASTM D5470 under a condition of 30% compression, and more specifically, can be measured by the method described in the examples.

[0031] In order to set the thermal conductivity within the above range, for example, the type and content of the thermally conductive filler may be adjusted.

[0032] 1.2. Composition of the thermally conductive spacer The thermally conductive spacer of this embodiment contains a thermosetting resin and a thermally conductive filler, and may contain a surfactant, a curing catalyst, or other components as necessary. The thermally conductive spacer preferably contains the thermosetting resin in a cured state, but some uncured thermosetting resin may remain.

[0033] 1.2.1.Thermosetting resin A The thermosetting resin A is not particularly limited, but examples thereof include silicone resin, epoxy resin, acrylic resin, urethane resin, and phenol resin. Among these, silicone resin is preferred from the viewpoint of improving heat resistance and flexibility. The thermosetting resin may be used alone or in combination of two or more.

[0034] The thermosetting resin A preferably contains an addition-curable silicone resin that cures by an addition reaction. The addition-curable silicone resin is not particularly limited, but examples thereof include polyorganosiloxanes having alkenyl groups and polyorganosiloxanes having hydrosilyl groups. The alkenyl group contained in the polyorganosiloxane is preferably a vinyl group. The thermally conductive spacer may contain a commercially available thermosetting silicone resin and / or a cured product thereof.

[0035] The penetration of thermosetting resin A is preferably 80 to 150 mm, 90 to 130 mm, or 100 to 120 mm. The penetration is an index of the viscosity of a thermosetting resin, and the larger the value, the lower the viscosity tends to be. By including a thermosetting resin having a penetration within the above range, the value of (Xa-Xb) / Xb tends to be increased.

[0036] The penetration of a thermosetting resin can be measured, for example, using a "Penetrometry Tester" manufactured by Yasuda Seiki Seisakusho Co., Ltd. A cured thermosetting resin placed in a designated container is measured at 25°C using a standard needle (50 g) to measure the penetration amount (mm) in 5 seconds, and this value is taken as the penetration.

[0037] The viscosity of thermosetting resin A at 25°C is preferably 30 to 800 mPa·s, 50 to 700 mPa·s, 80 to 600 mPa·s, or 90 to 550 mPa·s. Although the penetration is an index of the viscosity of a thermosetting resin, it does not accurately represent the viscosity. Therefore, by keeping the viscosity of the thermosetting resin at 25°C within the above range, the value of (Xa - Xb) / Xb tends to be synergistically further increased. The viscosity of the thermosetting resin at 25°C may be, within the above range, 120 mPa·s or more, 180 mPa·s or more, 220 mPa·s or more, 30 mPa·s or more, or 400 mPa·s or more, or 400 mPa·s or less, 300 mPa·s or less, 250 mPa·s or less, 180 mPa·s or less, 150 mPa·s or less, or 120 mPa·s or less.

[0038] The viscosity of a thermosetting resin at 25°C can be measured using a Brookfield DV-1 digital viscometer. Using an RV spindle set and rotor No. 1, a container is used that can accommodate the rotor and be filled with thermosetting resin up to the reference line. The rotor is immersed in the thermosetting resin, and the viscosity is measured at 25°C and 10 rpm. Note that the viscosity of the thermosetting resin is the value before the thermosetting resin hardens.

[0039] The content of thermosetting resin A is preferably 60 to 100% by weight, or 80 to 100% by weight, based on the total of the components other than thermally conductive filler B. When the content of thermosetting resin A is within the above range, the value of (Xa-Xb) / Xb tends to be increased.

[0040] The thermally conductive spacer preferably contains, as the thermosetting resin A, a vinyl-modified organopolysiloxane having a vinyl group and a hydrosilyl-modified organopolysiloxane having a hydrosilyl group. Either the vinyl-modified organopolysiloxane or the hydrosilyl-modified organopolysiloxane may be the base polymer, and either may be the curing agent. Alternatively, the thermosetting resin A may be prepared by mixing approximately equal amounts of the vinyl-modified organopolysiloxane and the hydrosilyl-modified organopolysiloxane. The compounding ratio of the vinyl-modified organopolysiloxane to the hydrosilyl-modified organopolysiloxane may be adjusted so that the vinyl groups of the vinyl-modified organopolysiloxane and the hydrosilyl groups of the hydrosilyl-modified organopolysiloxane are equivalent.

[0041] 1.2.1.1. Vinyl-modified organopolysiloxane The vinyl-modified organopolysiloxane is an organopolysiloxane having at least two vinyl groups. The vinyl-modified organopolysiloxane may have vinyl groups on side chains and / or terminals. Such organopolysiloxanes have a structural unit represented by the following formula (a-1) or a terminal structure represented by formula (a-2). The vinyl-modified organopolysiloxane may have, for example, at least one of the structural unit represented by formula (a-1) and the terminal structure represented by formula (a-2), and a structural unit represented by formula (a-3).

[0042] [ka]

[0043] In formulas (a-1), (a-2), and (a-3), R represents any monovalent hydrocarbon group that may have a substituent. Examples of such monovalent hydrocarbon groups include, but are not limited to, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, 2-phenylethyl, and 2-phenylpropyl; and groups having a substituent in these groups. Examples of substituents that the monovalent hydrocarbon groups may have include halogen atoms, particularly fluorine and chlorine atoms.

[0044] The vinyl-modified organopolysiloxane may be used alone or in combination of two or more. The number of vinyl groups in the vinyl-modified organopolysiloxane is not particularly limited, and may be, for example, an average of 2.0 to 6.0 or 2.0 to 5.0 per molecule.

[0045] The average number of vinyl groups per molecule of the vinyl-modified organopolysiloxane can be measured by NMR. Specifically, for example, the vinyl-modified organopolysiloxane can be dissolved in deuterated chloroform as a heavy solvent using an ECP-300NMR manufactured by JEOL Corporation. The average number of vinyl groups per molecule can be calculated by dividing the measurement result thus obtained by the average molecular weight of the vinyl-modified organopolysiloxane.

[0046] 1.2.1.2. Hydrosilyl-modified organopolysiloxane The hydrosilyl-modified organopolysiloxane is an organopolysiloxane having at least two hydrosilyl groups. The hydrosilyl-modified organopolysiloxane may have hydrosilyl groups on side chains and / or terminals. Such organopolysiloxanes have a structural unit represented by the following formula (b-1) or a terminal structure represented by formula (b-2). The hydrosilyl-modified organopolysiloxane may have, for example, at least one of the structural unit represented by formula (b-1) and the terminal structure represented by formula (b-2), and a structural unit represented by formula (b-3).

[0047] [ka]

[0048] In formulas (b-1), (b-2), and (b-3), R represents any monovalent hydrocarbon group which may have a substituent. That is, in the hydrosilyl-modified organopolysiloxane, any monovalent hydrocarbon group which may have a substituent is bonded to a side chain of the siloxane skeleton. Examples of such monovalent hydrocarbon groups include the same monovalent hydrocarbon groups that may be contained in the vinyl-modified organopolysiloxane.

[0049] The hydrosilyl-modified organopolysiloxane may be used alone or in combination of two or more. The number of hydrosilyl groups in the hydrosilyl-modified organopolysiloxane is not particularly limited, and may be, for example, an average of 2.0 to 6.0 or 2.0 to 5.0 per molecule.

[0050] The average number of hydrosilyl groups per molecule of the hydrosilyl-modified organopolysiloxane can be measured by NMR. Specifically, for example, an ECP-300NMR manufactured by JEOL Corporation can be used to dissolve the hydrosilyl-modified organopolysiloxane in deuterated chloroform as a heavy solvent. The average number of hydrosilyl groups per molecule can be calculated by dividing the measurement result thus obtained by the average molecular weight of the hydrosilyl-modified organopolysiloxane.

[0051] 1.2.2.Thermal Conductive Filler B The thermally conductive filler B is a filler having thermal conductivity. The thermal conductivity of the thermally conductive filler B is not particularly limited, but is, for example, 10 W / m·K or more. The thermally conductive filler B is not particularly limited, but examples thereof include aluminum oxide (hereinafter also referred to as "alumina"), aluminum nitride, silica (particularly crystalline silica), boron nitride, silicon nitride, silicon oxide, zinc oxide, aluminum hydroxide, metallic aluminum, magnesium oxide, diamond, carbon, indium, gallium, copper, silver, iron, nickel, gold, tin, metallic silicon, and the like.

[0052] The thermally conductive filler B preferably contains one or more selected from the group consisting of boron nitride, aluminum nitride, aluminum oxide, silicon nitride, silicon oxide, magnesium oxide, metallic aluminum, and zinc oxide, more preferably contains one or more selected from the group consisting of aluminum oxide, magnesium oxide, aluminum nitride, and metallic aluminum, and even more preferably contains aluminum oxide. This is because the thermally conductive filler has high thermal conductivity, high insulating properties, and is inexpensive. The thermally conductive filler B may be used alone or in combination of two or more.

[0053] The aluminum oxide contained in thermally conductive filler B may be spherical alumina or polyhedral alumina. Thermally conductive filler B preferably contains polyhedral alumina, and more preferably contains both spherical alumina and polyhedral alumina. When thermally conductive filler B contains polyhedral alumina, the anchor effect tends to increase the value of (Xa-Xb) / Xb.

[0054] The average particle size of the thermally conductive filler B is preferably 0.05 to 120 μm, more preferably 0.1 to 100 μm. When the average particle size of the thermally conductive filler B is within the above range, the dispersibility and filling property of the thermally conductive filler B tend to be further improved.

[0055] Furthermore, fillers with different average particle sizes may be mixed and used as the thermally conductive filler B. As the thermally conductive filler B, it is preferable to use a combination of two or more of the thermally conductive filler (B-1) having an average particle size of 30 to 100 μm, the thermally conductive filler (B-2) having an average particle size of 10 to 25 μm, and the thermally conductive filler (B-3) having an average particle size of 0.3 to 8.0 μm, and it is more preferable to use a combination of all of these.

[0056] The thermally conductive filler B preferably contains polyhedral alumina as the thermally conductive filler (B-3), that is, the thermally conductive filler B preferably contains polyhedral alumina having an average particle size of 0.3 to 8.0 μm.

[0057] The average particle size of thermally conductive fillers can be measured using, for example, a Shimadzu SALD-20 laser diffraction particle size analyzer. The evaluation sample is prepared by adding 50 ml of pure water and 5 g of the thermally conductive filler powder to a glass beaker, stirring with a spatula, and then dispersing in an ultrasonic cleaner for 10 minutes. The dispersed thermally conductive filler powder solution is then added dropwise to the sampler using a dropper. Measurements can be performed once the absorbance has stabilized. The laser diffraction particle size analyzer calculates the particle size distribution from the light intensity distribution data of the diffraction / scattering holes detected by the sensor. The average particle size is calculated by multiplying the measured particle size value by the relative particle amount (difference %) and dividing by the total relative particle amount (100%). The average particle size is the average diameter of the particles and can be calculated as the cumulative weight average D50 (median diameter).

[0058] In this case, the content of the thermally conductive filler (B-1) relative to the total amount of the thermally conductive filler B is preferably 30 to 75% by weight or 40 to 70% by weight. The content of the thermally conductive filler (B-2) is preferably 0 to 30% by weight or 10 to 20% by weight based on the total amount of the thermally conductive filler B. The content of the thermally conductive filler (B-2) may be 5% by weight or more based on the total amount of the thermally conductive filler B. The content of the thermally conductive filler (B-3) relative to the total amount of the thermally conductive filler B is preferably 5 to 55 wt %, 10 to 50 wt %, or 15 to 35 wt %. By using the thermally conductive filler B as described above, the dispersibility and packing property of the thermally conductive filler B are improved, and the value of (Xa-Xb) / Xb tends to be increased.

[0059] The content of the thermally conductive filler B is preferably 300 to 2500 parts by weight, 600 to 2000 parts by weight, or 800 to 1500 parts by weight per 100 parts by weight of the content of components other than the thermally conductive filler B. When the content of the thermally conductive filler B is within the above range, the thermal conductivity of the thermally conductive spacer tends to be further improved, and the value of (Xa-Xb) / Xb tends to be increased.

[0060] 1.2.3.Surfactant C The surfactant C may be a component that improves the wettability of the thermally conductive filler B with the thermosetting resin. From the viewpoint of further improving the wettability of the thermally conductive filler, the surfactant preferably has at least one of an anionic group, a cationic group, and a group having a siloxane skeleton.

[0061] The anionic group is not particularly limited, but examples thereof include a carboxy group, a phosphate group, a phenolic hydroxy group, and a sulfonic acid group. Among these, the anionic group is preferably at least one selected from the group consisting of a carboxy group, a phosphate group, and a phenolic hydroxy group, and is preferably a carboxy group.

[0062] The cationic group is not particularly limited, but examples thereof include a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium cationic group. Of these, the anionic group is preferably a tertiary amino group.

[0063] The group having a siloxane skeleton is not particularly limited, but examples thereof include groups having an organopolysiloxane skeleton, and among these, the group having a siloxane skeleton is preferably a group having a polydimethylsiloxane skeleton.

[0064] The weight-average molecular weight of the surfactant C is, for example, 20,000 to 150,000, 30,000 to 120,000, or 40,000 to 100,000. When the weight-average molecular weight of the surfactant is within the above range, the dispersibility of the thermally conductive filler B tends to be further improved.

[0065] The surfactant C is preferably an organopolysiloxane having a polydimethylsiloxane skeleton and having alkoxysilyl groups at its terminals, such as methoxy, ethoxy, propoxy, butoxy, pentoxy, and hexyloxy groups, with methoxy being preferred.

[0066] The content of surfactant C is preferably 0 to 30% by weight, 0.5 to 20% by weight, 1.0 to 15% by weight, or 2.0 to 10% by weight, based on the total weight of components other than thermally conductive filler B. When the content of surfactant C is within the above range, the dispersibility of thermally conductive filler B tends to be further improved.

[0067] 1.2.4.Curing catalyst D The curing catalyst D is not particularly limited as long as it catalyzes the curing reaction of the thermosetting resin. When the thermosetting resin A contains a vinyl-modified organopolysiloxane and a hydrosilyl-modified organopolysiloxane, it is sufficient that it catalyzes the addition reaction between the two. Examples of such curing catalysts D include platinum compound catalysts, rhodium compound catalysts, and palladium compound catalysts. Among these, platinum compound catalysts are preferred.

[0068] The platinum compound catalyst is not particularly limited, but examples thereof include simple platinum, platinum compounds, and platinum-supported inorganic powders. The platinum compound is not particularly limited, but examples thereof include chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum coordination compounds, etc. The platinum-supported inorganic powder is not particularly limited, but examples thereof include platinum-supported alumina powder, platinum-supported silica powder, and platinum-supported carbon powder. The curing catalyst D may be used alone or in combination of two or more types.

[0069] The content of the curing catalyst D is preferably 0.05 to 10 parts by weight, 0.1 to 5.0 parts by weight, or 0.3 to 3.0 parts by weight, relative to 100 parts by weight of the content of the components other than the thermally conductive filler B.

[0070] 1.2.5.Other Ingredients In addition to the above components, the thermally conductive spacer may contain additives such as a curing agent, a curing retarder, a colorant, a silane coupling agent, a viscosity modifier, etc., as needed.

[0071] The curing retarder is not particularly limited as long as it is a component that retards the curing reaction of the thermosetting resin. For example, when the thermosetting resin A contains a vinyl-modified organopolysiloxane and a hydrosilyl-modified organopolysiloxane, an alkenyl alcohol such as 1-ethynyl-1-cyclohexanol can be used as the curing retarder. When the thermally conductive spacer contains a curing retarder, the content of the curing retarder is preferably 0.001 to 1.0 part by weight, more preferably 0.01 to 0.1 part by weight, per 100 parts by weight of the content of the components other than the thermally conductive filler B.

[0072] Examples of the silane coupling agent include epoxy-based silane coupling agents such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 3-glycidoxypropylmethyldimethoxysilane; (meth)acrylic acid-modified silane coupling agents such as 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxytrimethoxysilane; and amino-based silane coupling agents such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0073] Examples of viscosity modifiers include polysiloxanes other than vinyl-modified organopolysiloxanes and hydrosilyl-modified organopolysiloxanes, synthetic rubber latex, urethane resins, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, polyvinyl alcohol, polyethylene oxide, and dibenzylidene sorbitol.

[0074] When the thermally conductive spacer contains additives such as a curing agent, a colorant, a silane coupling agent, a viscosity modifier, etc., the content of the additives is, for example, 0.001 to 0.2 parts by weight per 100 parts by weight of the content of components other than the thermally conductive filler B.

[0075] 2.Applications The thermally conductive spacer of this embodiment can be suitably used as a thermally conductive heat dissipating material disposed between a heat generating body such as an electronic component and a heat dissipating body such as a heat sink.

[0076] Examples of electronic components include, but are not limited to, heat-generating electronic components such as motors, battery packs, circuit boards mounted on in-vehicle power supply systems, power transistors, microprocessors, etc. Examples of heat sinks include, but are not limited to, housings, particularly metal housings.

[0077] 3. Manufacturing method The thermally conductive spacer of this embodiment can be produced by curing a thermally conductive composition containing a thermosetting resin and a thermally conductive filler. The thermally conductive spacer of this embodiment may include, for example, a step of mixing the components to obtain a thermally conductive composition (hereinafter referred to as a "mixing step"), a step of applying the thermally conductive composition to a substrate (hereinafter referred to as an "application step"), and a step of curing the thermally conductive composition applied to the substrate (hereinafter referred to as a "curing step").

[0078] In the mixing step, the components including the thermosetting resin and the thermally conductive filler are mixed. For example, a mixer such as a roll mill, kneader, Banbury mixer, or line mixer is used for mixing. More specifically, for example, a universal mixer, a hybrid mixer, a Trimix (manufactured by Inoue Seisakusho), or a static mixer is used for kneading. In the mixing step, for example, the above components A to D are mixed with optional additives.

[0079] In the coating step, the thermally conductive composition obtained in the mixing step is coated onto a substrate and molded. The coating method is preferably a doctor blade method, but depending on the viscosity of the composition, extrusion, pressing, calendar roll, or other methods may also be used. Examples of substrates include metal plates and resin films such as PET films. Coating and molding are preferably performed so that the thickness of the thermally conductive spacer is 0.3 to 10 mm, or 0.5 to 5.0 mm.

[0080] In the curing step, the thermally conductive composition applied to the substrate is cured to form a thermally conductive spacer. The curing conditions may be adjusted depending on the type of thermosetting resin and the type of curing catalyst, but for example, the curing step may be a step of heating at 100 to 170°C for 5 to 60 minutes.

[0081] After the curing step, the cured thermally conductive composition may be used as a thermally conductive spacer as it is, or may be further aged at a predetermined temperature after the curing step and then used as a thermally conductive spacer.

[0082] 4. Thermally conductive composition The thermally conductive composition of this embodiment is a composition for producing the thermally conductive spacer of this embodiment. As described in detail in the above section 3. Production method, the thermally conductive composition of this embodiment can be molded and cured to produce the thermally conductive spacer.

[0083] The thermally conductive composition of this embodiment may contain the above-mentioned components A to D in the above-mentioned amounts. The thermally conductive composition may further contain additives such as a curing agent and a cure retarder in the above-mentioned amounts. [Example]

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0085] 1. Manufacturing of thermally conductive spacers The components shown below were mixed in the blending ratios shown in Table 1. The components were mixed using a hybrid mixer ARE-310 (trade name, manufactured by Thinky Corporation).

[0086] Silicone resin A1: Two-component addition-curing silicone (density 0.98 g / cm 3 , viscosity of agent A: 200 mPa·s, viscosity of agent B: 100 mPa·s, penetration of cured product: 110) A2: SE1885 (DOW / Toray Industries, Inc.) Two-component addition-curing silicone (density 0.97 g / cm 3 , viscosity of agent A: 575 mPa·s, viscosity of agent B: 350 mPa·s, needle penetration of cured product: 95) A3: Equivalent mixture of the following vinyl-modified organopolysiloxane and hydrosilyl-modified organopolysiloxane (penetration of cured product: 90) Vinyl-modified organopolysiloxane RH-Vi100E (manufactured by Runhe Chemical Industry Co., Ltd., trade name) (a vinyl-modified organopolysiloxane with two vinyl groups per molecule on average, a vinyl group equivalent weight of 0.39 mol / kg, a weight-average molecular weight of 11,000, and a density of 0.98 g / cm) 3 , viscosity: 100mPa·s) Hydrosilyl-modified organopolysiloxane RH-H33 (manufactured by Runhe Chemical Industry Co., Ltd., product name), a hydrosilyl-modified organopolysiloxane with trimethylsilyl side chains at both ends, average number of hydrosilyl groups per molecule: 3 or more, hydrosilyl equivalent: 1.8 mol / kg, weight-average molecular weight: 3000-4000, density: 0.98 g / cm 3 , Viscosity: 80mPa·s

[0087] ·Curing catalyst Platinum complex polymethylvinylsiloxane solution (Blue Star Silicone, product name: Silicolyse Catalyst 12070)

[0088] ·Cure retarder Dimethyl maleate (Kanto Chemical Co., Ltd., trade name)

[0089] Thermally conductive filler Denka Corporation, spherical alumina, average particle size: 90 μm, thermal conductivity 35 W / m·K DAW45S (product name, manufactured by Denka), spherical alumina, average particle size: 45 μm, thermal conductivity 35 W / m·K Denka Corporation, spherical alumina, average particle size: 20 μm, thermal conductivity 35 W / m·K DAW05 (product name, manufactured by Denka Co., Ltd.), spherical alumina, average particle size: 5 μm, thermal conductivity: 35 W / m·K Polyhedral alumina manufactured by Denka, average particle size: 5 μm, thermal conductivity 35 W / m·K

[0090] The mixed composition was then applied to a PET film using a doctor blade. The amount of coating was adjusted so that the thickness of the cured thermally conductive spacer would be 1.0 mm. The composition was then cured by heating at 150°C for 60 minutes. The cured product obtained in the curing process was used as a thermally conductive spacer.

[0091] 2. Measurement and evaluation of physical properties (Tensile test) A 1.0 mm thick thermally conductive spacer was cut into a No. 8 dumbbell shape as specified in JIS K6251:2023 and used as a measurement sample. The measurement sample was placed in a tensile testing machine (Shimadzu, EZ-LX) and a tensile test was performed at a speed of 200 mm / min to create a stress-strain curve. From the stress-strain curve, the elongation at the break point Xa, the elongation at the maximum stress point Xb, and the tensile strength were read. The average values ​​of three measurements are shown in Table 1.

[0092] (Asker C hardness measurement) The Asker C hardness was measured at 25°C in accordance with SRIS0101 using an "Asker Rubber Hardness Tester Type C" manufactured by Kobunshi Keiki Co., Ltd. Specifically, the thermally conductive spacer was punched out into 2 cm square pieces using a punching blade, and the Asker C hardness (Asker C Hardness 1) of 12 stacked pieces was measured. The results are shown in Table 1.

[0093] (Evaluation of thermal conductivity characteristics) Using a 1mm thick thermally conductive spacer cut into a 10mm x 10mm piece, thermal resistance was measured under a 30% compression condition using a resin material thermal resistance measuring device (manufactured by Hitachi Technology & Services Co., Ltd.) in accordance with ASTM D5470. Thermal resistance values ​​were measured for thermally conductive spacers of several thicknesses (1mm, 2mm), and the thickness vs. thermal resistance values ​​were plotted. The thermal conductivity was calculated from the slope of each point. The results are shown in Table 1.

[0094] (Handling evaluation) We checked whether it was possible to predict the breakage point when a thermally conductive spacer was held with both hands and pulled left and right. Specifically, the thermally conductive spacer was pulled left and right, and the pulling of the thermally conductive spacer was stopped immediately when it was felt that the maximum stress point had been exceeded. This test was conducted three times, and if no cracks or breaks occurred in the thermally conductive spacer in any of the tests, it was rated as A, and if cracks or breaks occurred in any of the tests, it was rated as X. The results are shown in Table 1.

[0095] [Table 1]

Claims

1. a thermosetting resin and a thermally conductive filler; When a tensile test is performed using a dumbbell No. 8 in accordance with JIS K6251, the elongation at the breaking point is defined as Xa, and the elongation at the maximum stress point is defined as Xb, and the following formula (1) is satisfied: (Xa-Xb) / Xb ≧1.0 (1) Thermally conductive spacer.

2. The thermal conductivity measured in accordance with ASTM D5470 is 2.5 W / m K or more. The thermally conductive spacer according to claim 1 .

3. Asker C hardness is 1 to 20. The thermally conductive spacer according to claim 1 .

4. the thermally conductive filler comprises polyhedral alumina; The thermally conductive spacer according to claim 1 .

5. For producing the thermally conductive spacer according to any one of claims 1 to 4, Thermally conductive compositions.

6. A thermosetting resin having a penetration of 80 to 150 mm is included. The thermally conductive composition according to claim 5 .

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