Thermally conductive member and thermally conductive composition

Abstract

Provided is a thermally conductive member including a silicone matrix and a thermally conductive filler, wherein, in a 1H-NMR spectrum measured for a component extracted by immersing the thermally conductive member in deuterated chloroform, the ratio alpha of the integrated value of a multi-peak at 0.45±0.06 ppm to the integrated value of a peak derived from Si-CnH2n+1 is 0.05-0.30%.

Description

Thermally conductive member and thermally conductive composition

[0001] The present invention relates to a thermally conductive member and a thermally conductive composition.

[0002] In electronic devices such as computers, automobile parts, and mobile phones, heat sinks and other heat dissipators are commonly used to dissipate heat generated by heat-generating elements such as semiconductor devices and mechanical parts. It is known that a heat-conducting material such as a thermally conductive sheet or grease is placed between the heat generating element and the heat dissipating element to improve the efficiency of heat transfer to the heat dissipating element.

[0003] As device structures become more complex, thermally conductive materials are required to be molded into three-dimensional shapes that can better conform to the heating elements. To improve adhesion to device drive parts, thermally conductive materials must not only conform to the three-dimensional shape, but also exhibit low compression set under high-temperature conditions.

[0004] For example, Patent Document 1 discloses a silicone rubber molded product obtained by molding a thermally conductive composition by compression molding, injection molding, transfer molding, or other methods. The thermally conductive silicone rubber composition in Patent Document 1 is characterized by comprising 100 parts by weight of organopolysiloxane raw rubber, 10 to 500 parts by weight of alumina powder having a specific average particle size and particle size distribution, and a curing agent. In the examples, a dimethylsiloxane-methylvinylsiloxane copolymer rubber capped at both ends with dimethylvinylsiloxy groups is used as the organopolysiloxane raw rubber.

[0005] Furthermore, thermally conductive members are often processed into sheets or the like for use, and even in such cases, it may be necessary to reduce the compression set under high-temperature environments in order to improve adhesion to heating elements or the like.

[0006] Japanese Patent Application Laid-Open No. 2002-038012

[0007] Meanwhile, thermally conductive molded bodies having a three-dimensional shape are required to have good thermal conductivity and moldability, and also low hardness after curing. However, it is difficult for conventional thermally conductive members to reduce compression set in high-temperature environments while maintaining these properties.

[0008] For example, in Patent Document 1, although the compression set is low, the content of the thermally conductive filler is insufficient, and the thermal conductivity cannot be said to be good. Also, while the use of highly cross-linked silicone is known as a common method for reducing compression set, this method increases the hardness, which may damage the device, or may reduce moldability due to poor moldability.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a thermally conductive member that has low compression set while retaining the properties required for a thermally conductive molded body, such as low hardness and high thermal conductivity.

[0010] As a result of extensive research, the present inventors have found that the above problems can be solved by using a polyorganosiloxane having an alkenyl group in the side chain as a silicone matrix so as to satisfy specific requirements, and have completed the present invention as described below. That is, the present invention provides the following [1] to

[20] . [1] A thermally conductive member comprising a silicone matrix and a thermally conductive filler, wherein the thermally conductive member is immersed in deuterated chloroform and the extracted components are measured. １ In the H-NMR spectrum, Si—C ｎ H ２ｎ＋１(where n is an integer of 1 or greater)), the ratio α of the integral value of the multi-peak at 0.45±0.06 ppm to the integral value of the peak derived from the multi-peak at 0.45±0.06 ppm is 0.05% or greater and 0.30% or less. [2] The thermally conductive member according to the above item [1], having an E-hardness of 3 or greater and 90 or less. [3] The thermally conductive member according to the above item [1] or [2], having a thermal conductivity of 1.0 W / (m·K) or greater. [4] The thermally conductive member according to any of the above items [1] to [3], wherein the content of the silicone matrix is ​​20% by volume or greater and 50% by volume or less. [5] The thermally conductive member according to any of the above items [1] to [4], wherein the content of the thermally conductive filler is 50% by volume or greater and 80% by volume or less. [6] The thermally conductive member according to any of the above items [1] to [5], wherein the thermally conductive filler contains at least one of aluminum hydroxide and aluminum oxide. [7] A thermally conductive composition comprising a resin component containing an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane, and a thermally conductive filler, wherein the alkenyl group-containing organopolysiloxane contains an organopolysiloxane having alkenyl groups only in the side chain. [8] The thermally conductive composition according to [7] above, wherein the content of the organopolysiloxane having alkenyl groups in the side chain in the resin component is 5% by mass or more and 93% by mass or less. [9] The thermally conductive composition according to [7] or [8] above, wherein the ratio of hydrosilyl groups contained in the resin component to alkenyl groups contained in the resin component is 0.36 to 2.15 on a molar basis.

[10] The thermally conductive composition according to any one of [7] to [9] above, wherein the organopolysiloxane having alkenyl groups in the side chain has a functional group concentration of 1 μmol / g to 5,000 μmol / g.

[11] The thermally conductive composition according to any one of [7] to

[10] above, wherein the hydrosilyl group-containing organopolysiloxane has at least two or more hydrosilyl groups.

[12] The thermally conductive composition according to any one of [7] to

[11] above, wherein the organopolysiloxane having alkenyl groups in its side chains has a viscosity of 50,000 mPas or less at 23°C.

[13] The thermally conductive composition according to any one of [7] to

[12] above, wherein the content of the resin component is 20% by volume or more and 50% by volume or less.

[14] The thermally conductive composition according to any one of [7] to

[13] above, wherein the content of the thermally conductive filler is 50% by volume or more and 80% by volume or less.

[15] The thermally conductive composition according to any one of [7] to

[14] above, wherein the cured product of the thermally conductive composition has an E hardness of 3 or more and 90 or less.

[16] The thermally conductive composition according to any one of [7] to

[15] above, wherein the cured product of the thermally conductive composition has a thermal conductivity of 1.0 W / (m K) or more.

[17] The cured product of the thermally conductive composition was immersed in deuterated chloroform, and the components extracted were measured. １ In the H-NMR spectrum, Si—C ｎ H ２ｎ＋１ The thermally conductive composition according to any one of [7] to

[16] above, wherein the ratio α of the integral value of the multi-peak at 0.45±0.06 ppm to the integral value of the peak derived from the organopolysiloxane is 0.05% or more and 0.30% or less.

[18] The thermally conductive composition according to any one of [7] to

[17] above, wherein the ratio of alkenyl groups in the side chains of the organopolysiloxane to the total alkenyl groups contained in the resin component is 20% by mass or more and 100% by mass or less.

[19] A thermally conductive member which is a cured product of the thermally conductive composition according to any one of [7] to

[18] above.

[20] The thermally conductive member according to any one of [1] to [6] and

[19] above, which has a three-dimensional shape.

[0011] The present invention can provide a thermally conductive member that has low hardness, high thermal conductivity, and other properties, while also exhibiting low compression set.

[0012] [Thermal Conductive Member] The thermal conductive member of the present invention is a thermal conductive member containing a silicone matrix and a thermally conductive filler. The thermal conductive member can be formed from a thermally conductive composition described below.

[0013] [Integral Value Ratio α] The thermal conductive member of the present invention was immersed in deuterated chloroform and the ratio was measured for the components extracted. １ In the H-NMR spectrum, Si—C ｎ H ２ｎ＋１ The ratio α of the integral value of the multi-peak at 0.45±0.06 ppm to the integral value of the peak of origin (n is an integer of 1 or more) is 0.05 or more and 0.30% or less.

[0014] The multiple peaks at 0.45±0.06 ppm are peaks resulting from the addition reaction of a side-chain alkenyl group with a hydrosilyl group, and are due to hydrogen atoms bonded to carbon atoms to which Si derived from the hydrosilyl group is directly bonded. For example, when the alkenyl group is a vinyl group, the peaks are due to hydrogen atoms of the methylene group indicated by the arrows below.

[0015] Also, Si—C ｎ H ２ｎ＋１ The peaks derived from this are due to the alkyl groups (C ｎ H ２ｎ＋１ ) and is typically a peak derived from a methyl group bonded to Si. Therefore, the above ratio α can be said to mean the ratio of crosslinked structures derived from side-chain alkenyl groups in the organopolysiloxane skeleton. ｎ H ２ｎ＋１ The resulting peaks typically appear between 0.00 and 0.16 ppm.

[0016] When the ratio α is within the above range, the thermally conductive member of the present invention can achieve low compression set at high temperatures while retaining the properties required for a thermally conductive molded article, such as hardness and thermal conductivity. While the underlying mechanism is unclear, when the ratio α is within the above range, the silicone matrix contains a certain amount of crosslinked structures (network structures) derived from the side chain alkyl groups, reducing the amount of uncrosslinked and unreacted components. Therefore, it is presumed that the crosslinked structures derived from the side chain alkyl groups can reduce compression set at high temperatures while maintaining the properties required for a thermally conductive member, such as hardness and thermal conductivity. On the other hand, when the ratio α is lower than 0.05%, the absolute amount of crosslinked structures derived from the side chain alkenyl groups decreases, making it difficult to reduce compression set. Furthermore, when the ratio α is higher than 0.30%, the absolute amount of crosslinked structures derived from the side chain alkyl groups increases, or the amount of uncrosslinked and unreacted components increases, making it difficult to reduce compression set.

[0017] From the viewpoint of improving the compression set at high temperatures while improving the hardness, thermal conductivity, etc., the ratio α is preferably 0.07% or more, more preferably 0.09% or more, even more preferably 0.11% or more, and preferably 0.27% or less, more preferably 0.23% or less, and even more preferably 0.20% or less. As described below, the ratio α can be adjusted by adding a side-chain alkenyl group-containing organopolysiloxane to the thermally conductive composition and appropriately changing its content and the ratio of side-chain alkenyl groups to all alkenyl groups. The ratio α can also be adjusted by adding a side-chain alkenyl group-containing organopolysiloxane and then appropriately changing the molar ratio of hydrosilyl groups to alkenyl groups (H / Vi) in the thermally conductive composition. Specifically, as H / Vi approaches 1, the ratio α tends to be near the lower limit within the above-mentioned range, while as it deviates from 1, the value tends to increase.

[0018] In the thermally conductive member, the silicone matrix is ​​formed from an organopolysiloxane. As described below, the organopolysiloxane is preferably a curable organopolysiloxane, and therefore the silicone matrix is ​​preferably formed by curing the curable organopolysiloxane. As described below, the curable organopolysiloxane preferably contains an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane. Furthermore, the silicone matrix may appropriately contain components other than the silicone matrix and a thermally conductive filler such as an additive, as described in the thermally conductive composition described below.

[0019] In the thermally conductive member, the thermally conductive filler is dispersed and held in the silicone matrix. The thermal conductivity of the thermally conductive member is improved by containing the thermally conductive filler. Details of the thermally conductive filler are as described below in the thermally conductive composition section.

[0020] The content of the silicone matrix in the thermally conductive member is preferably 20% by volume or more and 50% by volume or less. A content of 20% by volume or more allows the silicone matrix to properly retain the thermally conductive filler. Furthermore, a content of 50% by volume or less makes it easier to incorporate components other than the silicone matrix, such as a thermally conductive filler, into the thermally conductive member. The content of the silicone matrix is ​​more preferably 24% by volume or more and 45% by volume or less, even more preferably 27% by volume or more and 43% by volume or less, and even more preferably 29% by volume or more and 39% by volume or less. The volumetric content of the thermally conductive filler is preferably 50% by volume or more and 80% by volume or less, assuming the thermally conductive member to be 100% by volume. A thermally conductive filler content of 50% by volume or more can impart a certain level of thermal conductivity to the thermally conductive member. A content of the thermally conductive filler content of 80% by volume or less allows the thermally conductive filler to be properly dispersed in the silicone matrix. Furthermore, an unnecessarily high viscosity of the thermally conductive composition can be prevented. The volumetric content of the thermally conductive filler is more preferably 54% by volume or more and 75% by volume or less, even more preferably 56% by volume or more and 72% by volume or less, and even more preferably 60% by volume or more and 70% by volume or less.

[0021] <Thermal conductive composition> The thermal conductive composition of the present invention contains a resin component and a thermally conductive filler. The thermally conductive composition of the present invention is a composition for forming a thermally conductive member, and specifically, the thermally conductive member can be obtained by curing the thermally conductive composition. Each component contained in the thermally conductive composition will be described in detail below.

[0022] [Resin Component] The resin component of the present invention contains an organopolysiloxane. The organopolysiloxane contains a curable organosiloxane, and the organosiloxane is cured to form the silicone matrix. Specifically, the resin component of the present invention contains an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane.

[0023] (Alkenyl Group-Containing Organopolysiloxane) In the present invention, the alkenyl group-containing organopolysiloxane comprises an organopolysiloxane having at least an alkenyl group in the side chain (hereinafter also referred to as "side-chain alkenyl group-containing organopolysiloxane"). In the present invention, the thermally conductive composition contains an organopolysiloxane having an alkenyl group in the side chain, thereby improving the properties required for thermally conductive members, such as hardness and thermal conductivity, while reducing compression set. Although the mechanism behind this is unclear, it is believed that the presence of an alkenyl group in the side chain results in the formation of a crosslinked structure within the organopolysiloxane structure, resulting in an apparently uniform dispersion of crosslinks within the cured product, thereby improving the brittleness caused by spatial non-uniformity within the matrix. Therefore, the molecular weight of the crosslinked points in the gel is relatively large, thereby reducing localized increases in hardness and imparting flexibility to the crosslinked points, which was difficult to achieve with conventional structures. It is therefore believed that the cured product is more likely to exhibit restoring properties even at low hardness, and that compression set can be reduced.

[0024] The side-chain alkenyl group-containing organopolysiloxane may have one or more alkenyl groups in the side chain, but preferably has two or more alkenyl groups. The side-chain alkenyl group-containing organopolysiloxane may also have an alkenyl group at the end in addition to the side chain, but preferably has an alkenyl group only in the side chain. By having an alkenyl group only in the side chain, the molecular weight of the crosslinked portion in the gel is kept relatively large, and while maintaining good hardness, thermal conductivity, etc., the compression set is made lower. The side-chain alkenyl group refers to an alkenyl group directly bonded to a silicon atom in the organopolysiloxane chain.

[0025] In addition, when the weight average molecular weight (g / mol) is Mw and the alkenyl group concentration (μmol / g) is C, the average number of alkenyl groups per molecule is Mw×C×10 －６It can be calculated by the formula: The average number of alkenyl groups calculated in this way is preferably 2 or more, more preferably 2.2 or more, and even more preferably 2.4 or more. By making the average number of alkenyl groups per molecule 2 or more, a crosslinked structure can be appropriately introduced, and it becomes easier to further reduce compression set while maintaining good hardness, thermal conductivity, etc. Furthermore, the average number of alkenyl groups may be, for example, 5 or less, but is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3 or less.

[0026] The organopolysiloxane containing side chain alkenyl groups may be linear or branched, or may be a mixture of linear and branched groups, but linear groups are preferred. The alkenyl groups contained in the side chains are contained at positions other than the ends of the molecular chain of the polysiloxane structure. The alkenyl groups are not particularly limited, but examples include those having 2 to 8 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, and octenyl groups. Of these, vinyl groups are preferred from the standpoints of ease of synthesis and reactivity. Furthermore, it is preferable that the double bond in the alkenyl group be provided at the end of the alkenyl group. Furthermore, it is preferable that the alkenyl group be an alkenyl group directly bonded to a silicon atom.

[0027] Examples of residual groups bonded to silicon atoms other than alkenyl groups include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl; aryl groups such as phenyl; and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl. Specific examples also include substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl. Of these, hydrocarbon groups are preferred, and methyl groups are more preferred from the standpoint of ease of synthesis. Furthermore, of the residual groups bonded to silicon atoms, preferably 80 mol % or more are methyl groups, more preferably 90 mol % or more are methyl groups, and even more preferably 100 mol % are methyl groups. It is preferable that the side-chain alkenyl group-containing organopolysiloxane does not have hydrogen atoms as residual groups bonded to silicon atoms; that is, the side-chain alkenyl group-containing organopolysiloxane does not contain hydrosilyl groups. The organopolysiloxane containing alkenyl groups in the side chains may be used alone or in combination of two or more.

[0028] The side-chain alkenyl group-containing organopolysiloxane is preferably liquid at 25°C. The viscosity of the side-chain alkenyl group-containing organopolysiloxane at 23°C is preferably 50,000 mPas or less, more preferably 10,000 mPas or less, and even more preferably 3,000 mPas or less. By setting the viscosity of the side-chain alkenyl group-containing organopolysiloxane to the upper limit or less, it is possible to prevent a decrease in reactivity and a high viscosity of the thermally conductive composition. Furthermore, the viscosity of the side-chain alkenyl group-containing organopolysiloxane at 23°C is preferably 50 mPas or more, more preferably 100 mPas or more, and even more preferably 200 mPas or more. By setting the viscosity of the side-chain alkenyl group-containing organopolysiloxane to the above-mentioned lower limit or more, it is possible to prevent an increase in crosslink density and to easily reduce the hardness after curing. In addition, it prevents the reactivity from becoming too rapid, making it easier for the addition reaction to proceed appropriately. The viscosity is measured using a Brookfield B-type viscometer in accordance with JIS K7117-1. The spindle in the Brookfield B-type viscometer should be appropriately selected so that the torque is 10 to 80%.

[0029] The weight-average molecular weight (Mw) of the side-chain alkenyl group-containing organopolysiloxane is preferably 5,000 to 100,000, more preferably 10,000 to 50,000, and even more preferably 15,000 to 35,000. By setting the weight-average molecular weight of the side-chain alkenyl group-containing organopolysiloxane to the upper limit or less, it is possible to prevent a decrease in reactivity and a high viscosity of the thermally conductive composition. Furthermore, by setting the weight-average molecular weight of the side-chain alkenyl group-containing organopolysiloxane to the lower limit or more, it is possible to prevent an increase in crosslink density and reduce the hardness after curing. Furthermore, it is possible to prevent excessively rapid reactivity and facilitate the appropriate progress of the addition reaction.

[0030] The functional group concentration of the side-chain alkenyl group-containing organopolysiloxane is preferably 1 μmol / g or more and 5000 μmol / g or less. When the functional group concentration is 1 μmol / g or more, the amount of side-chain alkenyl groups is at least a certain level, allowing for the formation of an appropriate crosslinked structure. On the other hand, when the functional group concentration is 5000 μmol / g or less, an increase in crosslink density is prevented, flexibility after curing is ensured, and hardness is easily reduced. The functional group concentration of the side-chain alkenyl group-containing organopolysiloxane is more preferably 20 μmol / g or more and 1000 μmol / g or less, and even more preferably 50 μmol / g or more and 400 μmol / g or less. The functional group concentration (μmol / g) is the concentration of alkenyl groups in the side-chain alkenyl group-containing organopolysiloxane, and is typically the vinyl group concentration. The functional group concentration is measured using an NMR measurement device. １ It can be calculated from the integral ratio of the H-NMR spectrum.

[0031] The content of the side-chain alkenyl group-containing organopolysiloxane in the resin component is preferably, for example, 5% by mass or more and 93% by mass or less. When the content of the side-chain alkenyl group-containing organopolysiloxane is 5% by mass or more, it is possible to achieve a certain amount of side-chain alkenyl groups in the resin component, which facilitates lowering of compression set while maintaining good hardness, thermal conductivity, etc. Furthermore, when the content is 93% by mass or less, it is possible to incorporate a certain amount of hydrosilyl group-containing organopolysiloxane. The content of the side-chain alkenyl group-containing organopolysiloxane in the resin component is preferably 8% by mass or more, more preferably 20% by mass or more, even more preferably 50% by mass or more, and even more preferably 60% by mass or more. Furthermore, the content of the side-chain alkenyl group-containing organopolysiloxane in the resin component is preferably 91% by mass or less, more preferably 88% by mass or less, even more preferably 86% by mass or less, and even more preferably 81% by mass or less.

[0032] The alkenyl group-containing organopolysiloxane in the thermally conductive composition may consist solely of a side-chain alkenyl group-containing organopolysiloxane, or may further contain an alkenyl group-containing organopolysiloxane other than the side-chain alkenyl group-containing organopolysiloxane. Therefore, the alkenyl group-containing organopolysiloxane may contain, in addition to the side-chain alkenyl group-containing organopolysiloxane, an organopolysiloxane containing an alkenyl group at its terminal (also referred to as a "terminal alkenyl group-containing organopolysiloxane"). The terminal alkenyl group-containing organopolysiloxane contains an alkenyl group at its terminal and does not contain an alkenyl group in its side chain. The terminal alkenyl group-containing organopolysiloxane is preferably liquid at 25°C.

[0033] The number of alkenyl groups in the alkenyl-terminated organopolysiloxane may be one or more per molecule, but two or more is preferred. The number of alkenyl groups in one molecule of the alkenyl-terminated organopolysiloxane is not particularly limited as long as it is two or more, but is preferably 2 to 4, more preferably 2 to 3, and even more preferably 2. The alkenyl-terminated organopolysiloxane may be linear or branched, or may be a mixture of linear and branched groups, but linear is preferred. It is also more preferred that the alkenyl-terminated organopolysiloxane contains alkenyl groups at both ends. Details of the alkenyl groups and the remaining groups bonded to silicon atoms other than the alkenyl groups are the same as those for the side-chain alkenyl-group-containing organopolysiloxane described above, and therefore further description is omitted. The alkenyl-terminated organopolysiloxane may be used alone, or two or more types may be used in combination. The content of the organopolysiloxane containing terminal alkenyl groups may be adjusted so that the ratio of side chain alkenyl groups to all alkenyl groups, as described below, is as follows:

[0034] The proportion of alkenyl groups on the side chains of the organopolysiloxane relative to all alkenyl groups contained in the resin component (i.e., alkenyl group-containing organopolysiloxane) is preferably 8% by mass or more, preferably 20% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. By maintaining the amount of alkenyl groups on the side chains at a certain level as described above, it becomes easier to further reduce compression set while maintaining good hardness, thermal conductivity, etc. The proportion of alkenyl groups on the side chains relative to all alkenyl groups in the resin component is not particularly limited, and may be 100% by mass or less, but may also be 99% by mass or less, or 97% by mass or less. The proportion of alkenyl groups on the side chains relative to all alkenyl groups is typically the proportion of vinyl groups on the side chains of the organopolysiloxane relative to all vinyl groups in the resin component.

[0035] The content of the alkenyl group-containing organopolysiloxane is not particularly limited and may be appropriately selected so that the H / Vi ratio described below can be adjusted within the desired range. However, the content is preferably 25% by mass or more and 95% by mass or less, and more preferably 30% by mass or more and 90% by mass or less, based on the total amount of organopolysiloxane contained in the thermally conductive composition.

[0036] (Hydrosilyl Group-Containing Organopolysiloxane) As described above, the resin component contains a hydrosilyl group-containing organopolysiloxane. By containing the hydrosilyl group-containing organopolysiloxane in the thermally conductive composition, the hydrosilyl group-containing organopolysiloxane undergoes an addition reaction with the alkenyl group-containing organopolysiloxane to extend the chain, thereby forming a cured product with appropriate hardness. It is preferable that the hydrosilyl group-containing organopolysiloxane has at least two or more functional hydrosilyl groups. By containing two or more functional hydrosilyl groups, the thermally conductive composition can be appropriately cured, and a crosslinked structure can be introduced into the cured product (thermally conductive member).

[0037] The hydrosilyl group-containing organopolysiloxane may be linear or branched, may contain a cyclic structure, or may be a mixture of two or more of these, but preferably contains a linear hydrosilyl group-containing organopolysiloxane. The linear or branched hydrosilyl group-containing organopolysiloxane may contain hydrosilyl groups at either the terminal or side chain of the molecular chain of the polysiloxane structure, or may contain hydrosilyl groups at both the terminal and side chain, but preferably contains hydrosilyl groups at at least the terminal, and more preferably contains two hydrosilyl groups at each of the terminals of the molecular chain of the polysiloxane structure. The number of functional groups (the number of hydrosilyl groups per molecule) of the linear or branched hydrosilyl group-containing organopolysiloxane is preferably 2 to 25, more preferably 3 to 20. The hydrosilyl group-containing organopolysiloxane should be liquid at 25°C.

[0038] The hydrosilyl group-containing organopolysiloxane may contain a hydrosilyl group-containing organopolysiloxane having a cyclic structure, but the content thereof may be small, for example, from 0.01% by mass to 1% by mass, preferably from 0.03% by mass to 0.5% by mass in the resin component. However, the hydrosilyl group-containing organopolysiloxane having a cyclic structure should have a high functional group concentration (i.e., hydrosilyl group concentration). Specifically, it is sufficient to use one having a functional group concentration of about 1000 μmol / g to 20000 μmol / g, preferably from 2000 μmol / g to 10000 μmol / g.

[0039] In the hydrosilyl group-containing organopolysiloxane, examples of residual groups bonded to silicon atoms other than hydrosilyl groups include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl; aryl groups such as phenyl; and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl. Specific examples also include substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl. Of these, methyl groups are preferred from the standpoint of ease of synthesis. Furthermore, of the residual groups bonded to silicon atoms, preferably 80 mol % or more are methyl groups, more preferably 90 mol % or more are methyl groups, and even more preferably 100 mol % are methyl groups. It is preferable that the hydrosilyl group-containing organopolysiloxane does not have alkenyl groups as residual groups bonded to silicon atoms; that is, the hydrosilyl group-containing organopolysiloxane does not contain alkenyl groups. The hydrosilyl group-containing organopolysiloxanes may be used alone or in combination of two or more.

[0040] The content of the hydrosilyl group-containing organopolysiloxane is not particularly limited and may be appropriately selected so that the H / Vi ratio described below can be adjusted to fall within the desired range. However, it is preferably from 4 to 74% by mass, more preferably from 9 to 69% by mass, based on the total amount of resin components contained in the thermally conductive composition.

[0041] The contents of the alkenyl group-containing organopolysiloxane and the hydrosilyl group-containing organopolysiloxane may be adjusted so that the ratio (H / Vi) of the hydrosilyl groups contained in the resin component to the alkenyl groups contained in the resin component is 0.36 to 2.15 on a molar basis. Note that H / Vi is typically the molar ratio of hydrosilyl groups to vinyl groups. When H / Vi is within the above range, the amount of uncrosslinked components and unreacted components is reduced while a crosslinked structure is appropriately introduced, thereby improving properties such as hardness and thermal conductivity while reducing compression set. H / Vi is preferably 0.4 to 2.1, more preferably 0.5 to 1.8, and even more preferably 0.65 to 1.5. Note that H / Vi can be calculated from the hydrosilyl group concentration, alkenyl group concentration, and content of each component. The hydrosilyl group concentration and alkenyl group concentration of each component can be calculated from the integral ratio of the 1H-NMR spectrum measured by NMR measurement.

[0042] (Other Resin Components) The thermally conductive composition may contain organopolysiloxanes other than hydrosilyl group-containing organopolysiloxanes and alkenyl group-containing organopolysiloxanes (also referred to as other organopolysiloxanes). Specific examples include silicone oils, organopolysiloxanes having at least one alkoxy group (alkoxy group-containing organopolysiloxanes), organopolysiloxanes having at least one hydroxyl group (hydroxyl group-containing organopolysiloxanes), and organopolysiloxanes having a group with an aromatic structure such as pyrene or perylene, preferably a polycyclic aromatic structure (aromatic group-containing organopolysiloxane).

[0043] Examples of silicone oils include straight silicone oils such as dimethyl silicone oil and phenylmethyl silicone oil, as well as non-reactive modified silicone oils in which a non-reactive organic group is introduced into a main chain having a polysiloxane structure, a side chain bonded to the main chain, or the end of the main chain.The non-reactive organic group is an organic group that does not have an addition reaction group.Examples of non-reactive modified silicone oils include polyether-modified silicone oil, aralkyl-modified silicone oil, fluoroalkyl-modified silicone oil, long-chain alkyl-modified silicone oil, higher fatty acid ester-modified silicone oil, higher fatty acid amide-modified silicone oil, and phenyl-modified silicone oil.Among the above, straight silicone oil is preferred as the silicone oil, and among straight silicone oils, dimethyl silicone oil is more preferred.The silicone oil may be used alone or in combination of two or more.

[0044] The alkoxy group-containing organopolysiloxane may be linear or branched, or may be a mixture of linear and branched structures, but linear is preferred. The alkoxy group-containing organopolysiloxane may be an organopolysiloxane having at least one alkoxy group. An organopolysiloxane having at least one alkoxy group at the molecular chain terminal of the polysiloxane structure is preferred, and an organopolysiloxane having at least one alkoxy group at only one terminal is more preferred. The alkoxy group-containing organopolysiloxane functions as a dispersant for the thermally conductive filler. The alkoxy group-containing organopolysiloxane, especially the terminal alkoxy group, easily reacts or interacts with functional groups present on the surface of the thermally conductive filler. Furthermore, the polysiloxane structure reduces the friction of the filler, making it easier to reduce the viscosity of the thermally conductive composition.

[0045] The alkoxy group-containing organopolysiloxane preferably has a group represented by the following formula (1), and the group represented by formula (1) is preferably bonded to Si that constitutes the polysiloxane structure via a linking group: —SiR１ ａ (OR ２ ３－ａ ) (1) In the formula (1), R １ , R ２ are each independently a hydrocarbon group, preferably an alkyl group. １ , R ２ The number of carbon atoms in R is, for example, 1 to 8, preferably 1 to 4, and more preferably 1 or 2. １ , R ２ Preferred specific examples of the above are a methyl group and an ethyl group. a is an integer of 0 to 2, preferably 0 or 1, and more preferably 0. The linking group connecting the group represented by formula (1) to Si is either an oxygen atom, a divalent hydrocarbon group, or an ester structure, with a divalent hydrocarbon group being preferred. Examples of divalent hydrocarbon groups include those having approximately 1 to 8 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, and a methylethylene group, with an ethylene group being preferred. The alkoxy-containing organopolysiloxane has a siloxane skeleton (—Si—O—), and the number of repeating units, n, of the siloxane skeleton is, for example, 10 to 320, preferably 20 to 280, and more preferably 25 to 230.

[0046] The hydroxyl-containing organopolysiloxane may have only one hydroxyl group, or two or more hydroxyl groups. While the upper limit of the number of hydroxyl groups is not particularly limited, it is preferably six or fewer hydroxyl groups, and more preferably three or fewer hydroxyl groups. The hydroxyl-containing organopolysiloxane functions as a dispersant for the thermally conductive filler. The hydroxyl-containing organopolysiloxane has hydroxyl groups, which facilitate reaction or interaction with functional groups on the surface of the thermally conductive filler, thereby improving the dispersibility of the thermally conductive filler and reducing the viscosity of the composition. The hydroxyl-containing organopolysiloxane may have only one hydroxyl group, and is preferably an organopolysiloxane having a hydroxyl group at one end of the main chain. The hydroxyl group may be directly bonded to the end of the organopolysiloxane chain, but it is preferably bonded via a linking group. One hydroxyl group may be bonded to one Si via a linking group, or multiple hydroxyl groups (for example, two or three) may be bonded to one Si via a linking group. The linking group is a hydrocarbon group that may contain an ester bond, an amide bond, an ether bond, an oxime ester bond (-C=N-O-C(=O)-), etc., and is preferably a hydrocarbon group having an ether bond. The linking group has about 1 to 20 carbon atoms, preferably 2 to 15, and more preferably 3 to 10. The organopolysiloxane having hydroxyl groups of the present invention has a siloxane skeleton (-Si-O-), and the number of repeating units, n, of the siloxane skeleton is preferably 11 to 350, more preferably 20 to 300, and even more preferably 50 to 270.

[0047] In the alkoxy group-containing organopolysiloxane and the hydroxy group-containing organopolysiloxane, the specific explanation of the residual group bonded to the silicon atom is the same as that for the side-chain alkenyl group-containing organopolysiloxane, and therefore will not be repeated. Furthermore, the alkoxy group-containing organopolysiloxane, the hydroxy group-containing organopolysiloxane, or the aromatic group-containing organopolysiloxane is preferably an organopolysiloxane that is liquid at 25°C.

[0048] The content of other organopolysiloxanes in the resin component is not particularly limited, but may be, for example, 0.1% by mass or more and 40% by mass or less, preferably 0.1% by mass or more and 28% by mass or less, more preferably 0.1% by mass or more and 12% by mass or less, and is preferably 0.5% by mass or more and 5% by mass or less.

[0049] Furthermore, the thermally conductive composition may contain a resin component other than the organopolysiloxane as long as the effects of the present invention are achieved. However, the organopolysiloxane may be the main component of the resin component. Specifically, the content of the organopolysiloxane may be, for example, 70% by mass or more and 100% by mass or less, preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 100% by mass, based on the total resin component. In other words, it is preferable that the resin component does not contain any resin component other than the organopolysiloxane.

[0050] The content of the resin component in the thermally conductive composition is substantially the same as the content of the silicone matrix in the thermally conductive member, and therefore the content of the resin component in the thermally conductive composition is preferably 20% by volume or more and 50% by volume or less, more preferably 24% by volume or more and 45% by volume or less, even more preferably 27% by volume or more and 43% by volume or less, and even more preferably 29% by volume or more and 39% by volume or less.

[0051] [Thermal Conductive Filler] Examples of thermally conductive fillers include metals, metal oxides, metal nitrides, metal hydroxides, carbon materials, oxides other than metals, nitrides, carbides, and organic fibers. The thermally conductive filler may be spherical or in the form of an irregular powder. Examples of metals in the thermally conductive filler include aluminum, copper, and nickel. Examples of metal oxides include aluminum oxide (e.g., alumina), magnesium oxide, and zinc oxide. Examples of metal nitrides include aluminum nitride. Examples of metal hydroxides include aluminum hydroxide. Examples of carbon materials include spherical graphite, diamond, and carbon fibers. Examples of oxides, nitrides, and carbides other than metals include quartz, boron nitride, and silicon carbide. Examples of organic fibers include polyparaphenylene benzoxazole fibers. Among these, metal oxides, metal nitrides, and carbon materials are preferred as thermally conductive fillers from the viewpoint of improving thermal conductivity, and metal oxides are more preferred. Specifically, aluminum oxide, aluminum hydroxide, and boron nitride are preferred, with aluminum oxide and aluminum hydroxide being more preferred. Among these, aluminum oxide is preferred from the viewpoint of improving the heat dissipation properties of the thermally conductive member, and aluminum hydroxide is preferred when it is desired to improve flame retardancy or when it is desired to reduce the specific gravity of the inorganic filler to reduce the weight of the thermally conductive resin composition or the thermally conductive member. These thermally conductive fillers may be used alone or in combination of two or more.

[0052] The average particle size of the thermally conductive filler may be, for example, approximately 0.1 to 1000 μm, preferably 0.1 to 200 μm, more preferably 0.3 to 100 μm, and even more preferably 0.5 to 70 μm. It is preferable to use a small-particle thermally conductive filler with an average particle size of 0.1 μm or more and 5 μm or less in combination with a large-particle thermally conductive filler with an average particle size of more than 5 μm and 200 μm or less. Another preferable embodiment of the large-particle thermally conductive filler is to use a first large-particle thermally conductive filler with an average particle size of more than 5 μm and 20 μm or less in combination with a second large-particle thermally conductive filler with an average particle size of more than 20 μm and 200 μm or less. The average particle size of the thermally conductive filler is D50, which can be calculated by observing the thermally conductive filler under a microscope and using the major axis as the diameter. More specifically, it means the particle size corresponding to a cumulative frequency of 50% when the major axis of at least 500 random particles is measured using, for example, an electron microscope or optical microscope. Specifically, it can be determined from a particle size distribution curve using a thermally conductive filler as a sample, with the horizontal axis representing particle size and the vertical axis representing cumulative frequency. The particle size distribution curve is a numerical particle size distribution curve obtained by sequentially accumulating the particle sizes of thermally conductive fillers, starting with the smallest particle size. The particle size can be determined by measuring the major axis, and for example, in the case of fibrous materials described below, the length in the major axis direction (fiber length) can be measured.

[0053] The content of the thermally conductive filler in the thermally conductive composition is substantially the same as the content of the thermally conductive filler in the thermally conductive member. Therefore, the volumetric content of the thermally conductive filler is preferably 50% by volume or more and 80% by volume or less, more preferably 54% by volume or more and 75% by volume or less, even more preferably 56% by volume or more and 72% by volume or less, and even more preferably 60% by volume or more and 70% by volume or less, based on 100 parts by volume of the thermally conductive composition. The content of the thermally conductive filler in the thermally conductive composition or the thermally conductive member in parts by mass is preferably 150 parts by mass or more and 3000 parts by mass or less, more preferably 200 parts by mass or more and 2000 parts by mass or less, even more preferably 300 parts by mass or more and 1500 parts by mass or less, and even more preferably 400 parts by mass or more and 1000 parts by mass or less, based on 100 parts by mass of the resin component (i.e., in the thermally conductive member, based on 100 parts by mass of the silicone matrix).

[0054] The thermally conductive filler may be either an anisotropic filler or a non-anisotropic filler. The anisotropic filler is preferably oriented in one direction of the thermally conductive member, and more preferably in the thickness direction of the thermally conductive member. This facilitates increasing the thermal conductivity of the thermally conductive member in one direction, for example, increasing the thermal conductivity of a sheet-shaped thermally conductive member in the thickness direction. When an anisotropic filler is oriented in the thickness direction, its major axis does not need to be strictly parallel to the thickness direction; even if the major axis is slightly tilted relative to the thickness direction, it is still considered to be oriented in the thickness direction. Specifically, an anisotropic filler whose major axis is tilted by less than 20° is also considered to be oriented in the thickness direction, and such anisotropic fillers are considered to be oriented in the thickness direction if they constitute the majority of the thermally conductive sheet (e.g., more than 60%, preferably more than 80% of the total number of anisotropic fillers).

[0055] An anisotropic filler is a filler that has an anisotropic shape and can be oriented. Examples of anisotropic fillers include fibrous materials and scaly materials, with scaly materials being preferred. An anisotropic filler has a high aspect ratio, specifically, an aspect ratio of greater than 2, preferably 5 or greater. Increasing the aspect ratio to greater than 2 makes it easier to orient the anisotropic filler in one direction, such as the thickness direction, and thus improves the thermal conductivity of the thermally conductive layer in one direction, such as the thickness direction. The upper limit of the aspect ratio is not particularly limited, but is practically 100. The aspect ratio is the ratio of the major axis length to the minor axis length of the anisotropic filler. In the case of fibrous materials, it means the fiber length / fiber diameter, and in the case of scaly materials, it means the major axis length / thickness of the scaly material.

[0056] When the anisotropic filler is a fibrous material, its average fiber length is preferably 10 μm or more and 300 μm or less, more preferably 20 μm or more and 200 μm or less, and even more preferably 30 μm or more and 100 μm or less. The average fiber length can be calculated by observing the anisotropic filler under a microscope. More specifically, the fiber lengths of 50 pieces of any anisotropic filler can be measured using, for example, an electron microscope or an optical microscope, and the average fiber length (arithmetic mean value) can be used as the average fiber length.

[0057] Furthermore, when the anisotropic filler is a scaly material, its average particle size may be, for example, 5 μm to 1000 μm, preferably 5 μm to 300 μm, more preferably 10 μm to 200 μm, and even more preferably 15 μm to 100 μm. By setting the average particle size to 10 μm or more, the anisotropic fillers can easily come into contact with each other, ensuring a heat transfer path and improving thermal conductivity. On the other hand, by setting the average particle size to 1000 μm or less, it is possible to highly fill the anisotropic filler into the silicone matrix.

[0058] The anisotropic filler may be any known material having thermal conductivity. However, when oriented by magnetic field orientation as described below, it is preferable for the filler to have diamagnetic properties. On the other hand, when oriented by flow orientation or when the anisotropic filler is not oriented, it does not need to have diamagnetic properties. Specific examples of anisotropic fillers include carbon-based materials such as carbon fiber or flake carbon powder, metal materials such as metal fiber and metal oxides, boron nitride, metal nitrides, metal carbides, metal hydroxides, and polyparaphenylene benzoxazole fibers. Among these, carbon-based materials are preferred due to their low specific gravity and good dispersibility in binder components, and graphitized carbon materials with high thermal conductivity are more preferred. Graphitized carbon materials have diamagnetic properties due to the alignment of graphite planes in a specific direction. Boron nitride is also a preferred anisotropic filler. While not particularly limited, boron nitride is preferably used as a flake material. The scaly boron nitride may be agglomerated or non-agglomerated, but it is preferable that some or all of the boron nitride is non-agglomerated. Note that boron nitride also has diamagnetic properties when its crystal planes are aligned in a specific direction. The anisotropic filler may be used alone or in combination of two or more types.

[0059] The aspect ratio of the non-anisotropic filler is 2 or less, and preferably 1.5 or less. When used in combination with an anisotropic filler, a non-anisotropic filler with such a low aspect ratio is more likely to be arranged in the gaps between the anisotropic filler, making it easier to improve thermal conductivity. Furthermore, by setting the aspect ratio to 2 or less, an increase in the viscosity of the mixed composition described below can be prevented, enabling high filling.

[0060] Specific examples of non-anisotropic fillers include metals, metal oxides, metal nitrides, metal hydroxides, carbon materials, and oxides, nitrides, and carbides other than metals. The shapes of the non-anisotropic fillers include spherical, polyhedral, and irregularly shaped powders. Examples of metals in non-anisotropic fillers include aluminum, copper, and nickel. Examples of metal oxides include aluminum oxide (e.g., alumina), magnesium oxide, and zinc oxide. Examples of metal nitrides include aluminum nitride. Examples of metal hydroxides include aluminum hydroxide. Examples of carbon materials include spherical graphite. Examples of oxides, nitrides, and carbides other than metals include quartz, boron nitride, and silicon carbide. Among these, aluminum oxide and aluminum are preferred because of their high thermal conductivity and the ease of obtaining spherical fillers. The non-anisotropic fillers may be used alone or in combination of two or more of the above.

[0061] The average particle size of the non-anisotropic filler is, for example, 0.1 μm or more and 200 μm or less, preferably 0.3 μm or more and 100 μm or less, and more preferably 0.5 μm or more and 70 μm or less. Furthermore, when the non-anisotropic filler is used in combination with an anisotropic filler, the average particle size of the non-anisotropic filler is preferably 0.1 μm or more and 50 μm or less, more preferably 0.3 μm or more and 35 μm or less, and even more preferably 0.5 μm or more and 15 μm or less. By setting the average particle size to 50 μm or less, problems such as disturbance of the orientation of the anisotropic filler are less likely to occur even when used in combination with an anisotropic filler. Furthermore, by setting the average particle size to 0.1 μm or more, the specific surface area of ​​the non-anisotropic filler does not become larger than necessary, and even when a large amount is blended, the viscosity of the mixed composition is less likely to increase, making it easier to highly fill the non-anisotropic filler.

[0062] The volumetric ratio of the content of the non-anisotropic filler to the content of the anisotropic filler in the thermally conductive member is not particularly limited, but is preferably 0.1 to 10, more preferably 0.3 to 3, and more preferably 0.5 to 2. By setting the filling rate ratio within the above range, the non-anisotropic filler is appropriately filled between the anisotropic fillers, forming efficient heat transfer paths, thereby further improving the thermal conductivity of the thermally conductive member.

[0063] The thermally conductive filler may be surface-treated with a surface treatment agent. The surface-treated thermally conductive filler can be obtained by mixing the surface treatment agent with the thermally conductive filler. Furthermore, from the viewpoint of facilitating the surface treatment during mixing, it is preferable to use a wet treatment method, a dry treatment method, or the like. In the wet treatment method, for example, the thermally conductive filler is added to a solution in which the surface treatment agent is dispersed or dissolved, and mixed, followed by heat treatment to bond or adhere the surface treatment agent to the surface of the thermally conductive filler. The dry treatment method is a surface treatment method that does not use a solution, and specifically, it is a method in which the thermally conductive filler and the surface treatment agent are mixed and stirred in a mixer or the like, followed by heat treatment to bond or adhere the surface treatment agent to the surface of the thermally conductive filler.

[0064] Examples of surface treatment agents include silane coupling agents and fatty acids. As the silane coupling agent, known agents can be used without particular limitation, and examples thereof include dimethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, n-decyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, and 3-phenylaminopropyltrimethoxysilane. Other examples include alkenyltriethoxysilanes having an alkenyl group with approximately 8 to 18 carbon atoms, such as octenyltrimethoxysilane. Furthermore, the fatty acid may be a fatty acid that is liquid at room temperature (25°C), or a fatty acid that is solid at room temperature. Liquid fatty acids include saturated fatty acids such as butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, and pelargonic acid, and unsaturated fatty acids such as myristoleic acid, palmitoleic acid, ricinoleic acid, oleic acid, linoleic acid, and linolenic acid. Solid fatty acids include saturated fatty acids with approximately 10 to 24 carbon atoms, such as capric acid, palmitic acid, and stearic acid, and unsaturated fatty acids such as crotonic acid and sorbic acid. Among these, stearic acid is preferred. Surface treatment agents may be used alone or in combination. Surface treatment with a surface treatment agent such as a silane coupling agent may also be performed using an integral blending method. Therefore, a surface treatment agent such as a silane coupling agent may be incorporated into the resin component, and the thermally conductive filler may be surface-treated with the silane coupling agent or fatty acid incorporated into the resin component.

[0065] (Other Additives) The thermally conductive composition of the present invention may contain various additives, such as curing catalysts, reaction control agents, dispersants, flame retardants, plasticizers, antioxidants, colorants, surface treatment agents, and volatile compounds.

[0066] Among the above, it is preferable that the thermally conductive composition contains a curing catalyst. The curing catalyst may be any catalyst that promotes the addition reaction between the alkenyl group-containing organopolysiloxane and the hydrosilyl group-containing polysiloxane. By including a curing catalyst in the thermally conductive composition, the curing and crosslinking of the thermally conductive composition can be appropriately promoted. Examples of curing catalysts include platinum group curing catalysts. Examples of platinum group curing catalysts include, but are not limited to, chloroplatinic acid, complex compounds of chloroplatinic acid with olefins, vinylsiloxanes, or acetylene compounds, and the like. The content of the platinum group curing catalyst in the thermally conductive composition is not particularly limited as long as it is contained in an amount that promotes the addition reaction, but is, for example, 0.0001 to 1 part by mass, preferably 0.001 to 0.5 parts by mass, per 100 parts by mass of the organopolysiloxane contained in the thermally conductive composition.

[0067] The thermally conductive composition of the present invention may also contain a volatile compound. The volatile compound may be incorporated into the thermally conductive composition when a thermally conductive member is manufactured by the flow orientation method described below. In the flow orientation method, if the thermally conductive composition contains a volatile compound, even if the content of the thermally conductive filler is increased, a sheet-like molded body can be appropriately formed by coating in step (B) described below. Examples of volatile compounds include volatile silane compounds and volatile solvents. Examples of volatile silane compounds include alkoxysilane compounds. An alkoxysilane compound is a compound having a structure in which one to three of the four bonds possessed by a silicon atom (Si) are bonded to alkoxy groups, and the remaining bond is bonded to an organic substituent. Among alkoxysilane compounds, alkoxysilane compounds having a methoxy group or an ethoxy group are preferred from the viewpoint of availability.

[0068] Specific examples of alkoxysilane compounds include alkyl group-containing alkoxysilane compounds, vinyl group-containing alkoxysilane compounds, acryloyl group-containing alkoxysilane compounds, methacrylic group-containing alkoxysilane compounds, aromatic group-containing alkoxysilane compounds, amino group-containing alkoxysilane compounds, isocyanate group-containing alkoxysilane compounds, isocyanurate group-containing alkoxysilane compounds, epoxy group-containing alkoxysilane compounds, and mercapto group-containing alkoxysilane compounds. Among these, alkyl group-containing alkoxysilane compounds are preferred, such as alkyltrialkoxysilanes and dialkyldialkoxysilanes. The type of volatile solvent is not particularly limited, but it is preferable to use aromatic compounds such as toluene or aliphatic compounds such as n-hexadecane. The content of the volatile compound in the thermally conductive composition is preferably 5 to 100 parts by mass, more preferably 15 to 70 parts by mass, per 100 parts by mass of the organopolysiloxane. The volatile compound may be evaporated by appropriate heating or the like after obtaining the sheet-shaped molded body, but a portion may remain in the thermally conductive member.

[0069] [Physical Properties of Thermally Conductive Member and Cured Product of Thermally Conductive Composition] (E Hardness) The thermally conductive composition of the present invention becomes a thermally conductive member upon curing. The E hardness of the cured product of the thermally conductive composition of the present invention, i.e., the thermally conductive member of the present invention, is preferably 3 or more and 90 or less. When the E hardness is 90 or less, the hardness of the thermally conductive member is not too high, and it can be used for thermally conductive molded bodies having three-dimensional shapes. Furthermore, by setting the E hardness to 3 or more, it is possible to prevent the hardness from becoming lower than necessary, and to easily reduce compression set. The E hardness is more preferably 10 or more, even more preferably 20 or more, and even more preferably 24 or more. Furthermore, from the viewpoint of improving conformability to heating elements, etc., the E hardness is more preferably 80 or less, even more preferably 70 or less, and even more preferably 55 or less. The E hardness is the type E hardness specified in JIS K6253.

[0070] (OO Hardness) The OO hardness of the cured product of the thermally conductive composition of the present invention, i.e., the thermally conductive member of the present invention, is not particularly limited, but is preferably 15 or more, more preferably 30 or more, even more preferably 40 or more, and preferably 92 or less, more preferably 90 or less, even more preferably 88 or less, and even more preferably 75 or less. The type OO hardness is measured by measuring the hardness of a 10 mm thick test piece in a 25 ° C environment using the method specified in ASTM D2240. If the thickness is less than 10 mm, the test piece is made by stacking the minimum number of thermally conductive members so that the total thickness is 10 mm or more, and the hardness is measured. The hardness, thermal conductivity, and flame retardancy of the cured product of the thermally conductive composition may be measured on a cured product obtained by heating the thermally conductive composition, for example, at 150 ° C for 4 hours.

[0071] (Thermal Conductivity) The thermal conductivity of the cured product of the thermally conductive composition of the present invention, i.e., the thermally conductive member of the present invention, is preferably 1.0 W / (m K) or more. When the thermal conductivity of the thermally conductive member is 1.0 W / (m K) or more, the heat dissipation properties can be improved, and the heat dissipation properties required for a thermally conductive molded body having a three-dimensional shape can be appropriately ensured. From the viewpoint of further improving heat dissipation, the thermal conductivity is more preferably 1.5 W / (m K) or more, and even more preferably 2.0 W / (m K) or more. The upper limit of the thermal conductivity is not particularly limited, but in practice, it is, for example, 40 W / (m K) or less, and more preferably 20 W / (m K) or more.

[0072] (Flame Retardancy) The flame retardancy of the cured product of the thermally conductive composition of the present invention, i.e., the thermally conductive member of the present invention, is preferably V-1 or higher, more preferably V-0, according to the UL94 standard. Flame retardancy of V-1 is easily achieved by incorporating a predetermined amount or more of a thermally conductive filler. Flame retardancy of V-0 is also easily achieved by using a substance capable of imparting flame retardancy, such as aluminum hydroxide, as the thermally conductive filler.

[0073] (Ratio α) Measured for components extracted by immersing a cured product of the thermally conductive composition of the present invention in deuterated chloroform. １ In the H-NMR spectrum, Si—Cｎ H ２ｎ＋１ The ratio α of the integral value of the multi-peak at 0.45±0.06 ppm to the integral value of the peak derived from the thermal conductive material is preferably 0.05% or more and 0.30% or less, similar to the ratio α of the thermal conductive material. The ratio α of the cured product of the thermal conductive composition is preferably 0.07% or more, more preferably 0.09% or more, even more preferably 0.11% or more, similar to the ratio α of the thermal conductive material. It is also preferably 0.27% or less, more preferably 0.23% or less, and even more preferably 0.20% or less. The ratio α of the cured product of the thermal conductive composition is obtained by heating the thermal conductive composition for example at 150° C. for 4 hours to obtain a cured product, and measuring the cured product in the same manner as for the thermal conductive material. １ It is advisable to calculate based on the H-NMR spectrum.

[0074] [One-component or Two-component Thermally Conductive Composition] The thermally conductive composition of the present invention may be a one-component or a two-component composition comprising a first component and a second component. A two-component composition is obtained by mixing the first and second components during use. In the case of a two-component composition, the components of the thermally conductive composition may be appropriately divided into the first and second components. For example, in a two-component thermally conductive composition, the first component may contain an alkenyl group-containing organopolysiloxane and a curing catalyst, but may not contain a hydrosilyl group-containing organopolysiloxane. In this case, the second component may contain a hydrosilyl group-containing organopolysiloxane but may not contain a curing catalyst. The second component may further contain an alkenyl group-containing organopolysiloxane. A thermally conductive filler may be contained in at least one of the first and second components, but it is preferable that a thermally conductive filler be contained in both the first and second components. Other organopolysiloxanes, other resin components, and additives may be appropriately divided into the first and second parts.

[0075] A one-component thermally conductive composition can be obtained by appropriately mixing the components that make up the thermally conductive composition. A two-component thermally conductive composition can be obtained by mixing the components that make up the first and second components to prepare the first and second components, respectively, and then mixing the first and second components. The method for mixing the first and second components to obtain the thermally conductive composition is not limited, and can be, for example, a static mixer, a mixer with stirring blades, a vibration mixer, or a planetary mixer.

[0076] [Shape and Manufacturing Method of Thermally Conductive Member] The thermally conductive member can be obtained by curing a thermally conductive composition. The thermally conductive member of the present invention is preferably formed by casting the thermally conductive composition into a mold such as a metal die, and molding it into a thermally conductive molded body having a three-dimensional shape that matches the shape of the mold. The thermally conductive composition of the present invention has the properties required for a thermally conductive molded body, such as low hardness and high heat dissipation, while also exhibiting low compression set at high temperatures, making it suitable for use as a thermally conductive molded body having a three-dimensional shape. The method for molding the thermally conductive composition into a thermally conductive molded body having a three-dimensional shape is not particularly limited, but examples include compression molding, injection molding, transfer molding, extrusion molding, vacuum forming, pressure forming, and calendar molding. The shape of the thermally conductive molded body having a three-dimensional shape is not particularly limited, but it may have a shape that matches the shape of the heat sink or heat generator to be used, and may have appropriate recesses or protrusions. The curing conditions for curing the thermosetting composition are not particularly limited, but may be, for example, heating at 80°C to 200°C for 30 seconds to 30 minutes, preferably at 100°C to 160°C for 1 minute to 15 minutes. Typically, this is done at 125°C for 8 minutes. Furthermore, secondary curing can be performed after the curing. For example, heating can be done at 150°C to 200°C for 24 hours or less. Preferably, the heating is done at 120°C to 180°C for 1 to 6 hours.

[0077] However, the thermally conductive member does not necessarily have to be a thermally conductive molded body having a three-dimensional shape, and may be a block-shaped thermally conductive member or a sheet-shaped thermally conductive member. Block-shaped or sheet-shaped thermally conductive members may also be produced by curing a thermosetting composition under the above-mentioned curing conditions. After curing, the thermosetting composition may be sliced ​​into a sheet. Furthermore, when the thermally conductive member contains an anisotropic filler, the anisotropic filler may be oriented in one direction. Orienting the anisotropic filler in one direction makes it easier to improve the thermal conductivity of the thermally conductive member in one direction. For example, in a sheet-shaped thermally conductive member, it is preferable to orient the anisotropic filler in the thickness direction in order to increase the thermal conductivity in the thickness direction.

[0078] Hereinafter, a manufacturing method for orienting an anisotropic filler will be described using as an example a method for obtaining a sheet-shaped thermally conductive member in which the anisotropic filler is oriented in the thickness direction. The manufacturing method for a thermally conductive member according to one embodiment of the present invention comprises the following steps (A) and (B): Step (A): A step of obtaining an oriented molded body in which the anisotropic filler is oriented along one direction. Step (B): A step of cutting the oriented molded body into sheets to obtain sheet-shaped molded bodies. Each step will be described in more detail below.

[0079] [Step (A)] In step (A), an oriented molded body is formed from the thermally conductive composition. The thermally conductive composition is preferably cured to form an oriented molded body. In addition, the oriented molded body preferably has an anisotropic filler oriented along one direction. More specifically, the oriented molded body can be obtained by a magnetic field orientation method, a flow orientation method, or the like.

[0080] (Magnetic Field Orientation Method) In the magnetic field orientation method, a thermally conductive composition is injected into a molding die such as a metal mold, placed in a magnetic field, and the anisotropic filler is oriented along the magnetic field. The thermally conductive composition is then cured to obtain an oriented molded body. The oriented molded body is preferably block-shaped. A release film may be placed inside the molding die at the portion where the molding die comes into contact with the thermally conductive composition. The release film may be, for example, a resin film with good release properties or a resin film whose one side has been treated with a release agent or the like. The use of a release film makes it easier to release the oriented molded body from the mold. The curing of the thermally conductive composition in the magnetic field orientation method is preferably carried out under the curing conditions described above.

[0081] The viscosity of the curable composition used in the magnetic field orientation manufacturing method at 25°C is preferably 10 to 300 Pa·s in order to achieve magnetic field orientation. By setting the viscosity at 10 Pa·s or higher, each filler is less likely to settle. Furthermore, by setting the viscosity at 300 Pa·s or lower, fluidity is improved, the anisotropic filler is properly oriented in the magnetic field, and problems such as excessive time required for orientation do not occur. Note that the viscosity at 25°C is the viscosity measured at 25°C using a rotational viscometer (Brookfield viscometer DV-E, spindle SC4-14) at a rotational speed of 10 rpm. However, when using a filler that is difficult to settle or when combining additives such as anti-settling agents, the viscosity of the mixed composition may be less than 10 Pa·s.

[0082] In the magnetic field orientation method, magnetic field generating sources for applying magnetic field lines include superconducting magnets, permanent magnets, electromagnets, etc., but superconducting magnets are preferred because they can generate a magnetic field with a high magnetic flux density. The magnetic flux density of the magnetic field generated from these magnetic field generating sources is preferably 1 to 30 Tesla. If the magnetic flux density is 1 Tesla or higher, it becomes possible to easily orient the anisotropic filler. Furthermore, if the magnetic flux density is 30 Tesla or lower, practical production becomes possible.

[0083] (Flow Orientation Method) In the flow orientation method, a thermally conductive composition is first prepared as described above, and then a shear force is applied to the thermally conductive composition to produce a preliminary sheet in which the anisotropic filler is oriented in the plane direction. Multiple sheets of this preliminary sheet are then stacked to produce a laminate block, which serves as an oriented molded article. The thermally conductive composition used in the flow orientation method has a relatively high viscosity so that a shear force is applied when stretched into a sheet. Specifically, the viscosity is preferably 3 to 500 Pa·s. Furthermore, the thermally conductive composition can be flattened and stretched into a sheet by applying a shear force, thereby orienting the anisotropic filler in the shear direction. For example, the thermally conductive composition can be formed into a sheet by applying a coating applicator such as a bar coater or doctor blade, or by extrusion molding or nozzle discharge. In this case, a substrate film may be further laminated on top of the thermally conductive composition coated on the substrate film. The substrate film laminated on the thermally conductive composition may be a gas-permeable film if the volatile compounds contained in the thermally conductive composition are to be volatilized. The coated thermally conductive composition may then be dried, semi-cured, or cured, as necessary, by heating. Furthermore, the volatile compounds contained in the thermally conductive composition may be volatilized by heating. The thickness of the preliminary sheet is preferably about 50 to 5,000 μm. In the preliminary sheet, the anisotropic filler is oriented in one direction along the surface direction of the sheet.

[0084] Next, multiple preliminary sheets are stacked so that they have the same orientation direction, and then appropriate pressure is applied in the stacking direction, and the thermally conductive composition is cured as needed by heating or the like, while the preliminary sheets are adhered to each other by a heat press or the like to form a laminated block, and this laminated block can be used as an oriented molded body.

[0085] In addition, when the preliminary sheets are cured or semi-cured, the contact surfaces of the preliminary sheets may be appropriately irradiated with VUV before the preliminary sheets are stacked. VUV stands for vacuum ultraviolet light, and refers to ultraviolet light with a wavelength of 10 to 200 nm. By irradiating the contact surfaces of the preliminary sheets with VUV and then stacking them on top of each other, the preliminary sheets can be easily firmly bonded together.

[0086] [Step (B)] In step (B), the oriented molded body obtained in step (A) is cut perpendicular to the orientation direction of the anisotropic filler by slicing or the like to obtain a sheet-like molded body. Slicing can be performed, for example, using a shear blade or a laser. Cutting the sheet-like molded body by slicing or the like may result in a portion of the anisotropic filler being exposed from the matrix at each cut surface. The sheet-like molded body obtained by slicing in step (B) may be further heated, or the sheet-like molded body may be secondary-cured by heating. Furthermore, if a volatile compound is blended into the thermally conductive composition, the sheet-like molded body may be heated to volatilize some or all of the volatile compound. The sheet-like molded body may be heated, for example, at 100 to 200°C, preferably 120 to 180°C, for example, for 30 minutes to 24 hours, preferably 1 to 6 hours.

[0087] The sheet-shaped product obtained through the step (B) may be used as a thermally conductive member as it is, or the surface may be polished. By polishing, the surface condition of the sheet-shaped product becomes better, and the thermal conductivity can be further improved.

[0088] The method for obtaining a sheet-shaped thermally conductive member in which an anisotropic filler is oriented in the thickness direction is not limited to the above, and for example, step (B) may be omitted. Specifically, in the magnetic field orientation method, step (B) can be omitted by producing a sheet-shaped oriented molded body instead of a block-shaped oriented molded body in step (A). In addition, in the above manufacturing method, step (B) may also be omitted when obtaining a block-shaped thermally conductive member, etc. Furthermore, when obtaining a thermally conductive member in which an anisotropic filler is oriented in one direction along the surface direction, part of step (A) and step (B) may be omitted, and the preliminary sheet obtained by the flow orientation method may be used as the sheet-shaped thermally conductive member.

[0089] <Uses of Thermally Conductive Member> The thermally conductive member of the present invention may be used for various electronic components, for example, by being disposed between a heat generating element and a heat sink. The thermally conductive member may be interposed between the heat generating element and the heat sink, thermally conducting the heat generated by the heat generating element to the heat sink, and dissipating the heat from the heat sink. Examples of the heat generating element include, but are not limited to, various electronic components such as CPUs, LEDs, coils, and lithium-ion batteries, as well as wiring through which large currents flow. Examples of the heat sink include heat sinks, heat pumps, and metal housings for electronic devices. A Peltier element may be disposed instead of the heat sink, and the thermally conductive member may be disposed on peripheral components such as bus bars, copper wires, and connectors around the heat generating element rather than directly on the heat generating element. The thermally conductive member of the present invention is preferably a thermally conductive molded article having a three-dimensional shape as described above. However, having a three-dimensional shape corresponding to the shape of the heat generating element or heat sink can further enhance adhesion and conformability to the heat generating element or heat sink.

[0090] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0091] The thermally conductive compositions and their cured products, that is, thermally conductive members, in the examples and comparative examples were evaluated by the following methods.

[0092] [Ratio α] 500 mg of the thermally conductive member was immersed in 2.5 g of deuterated chloroform (3.71 ml: specific gravity 1.484) and left at room temperature (25° C.) for 24 hours to extract the components of the thermally conductive molded body. The deuterated chloroform from which the components of the thermally conductive molded body had been extracted was then placed in an NMR tube as a sample to obtain a 1H NMR spectrum. １ In the H NMR spectrum, Si—C is present at 0.00 to 0.16 ppm. ｎ H ２ｎ＋１ The integral value of the peak derived from the NMR spectrum and the integral value of the multi-peak at 0.45±0.06 ppm were calculated to determine the ratio α. NMR measurement device: "Bruker Ascend 400" manufactured by Bruker Corporation Measurement frequency: 400 MHz Number of accumulations: 8 Standard substance: TMS (tetramethylsilane)

[0093] [E Hardness] The Type E hardness of the thermally conductive member was measured in accordance with Japanese Industrial Standard JIS K 6253. Specifically, the Type E hardness was measured for the thermally conductive members prepared in each Example and Comparative Example using a Type E durometer. The measurement was performed using a sample cut from the thermally conductive member to a length of 15 mm, a width of 15 mm, and a thickness of 10 mm.

[0094] [0000 Hardness] The hardness of the thermally conductive members prepared in each Example and Comparative Example was measured using a Type 00 durometer in accordance with ASTM D2240-05. The measurement was performed using a sample cut from the thermally conductive member to a length of 15 mm, a width of 15 mm, and a thickness of 10 mm.

[0095] [Flame Retardancy UL94] Flame retardancy was evaluated by the UL94 flame test established by Underwriters Laboratories Inc. of the United States. The thermally conductive members obtained in each Example and Comparative Example were cut to the size of a test specimen (127 mm long x 12.7 mm wide x 2 mm thick). The test specimen was held in a fixing clamp so that the longitudinal direction of the test specimen was vertical. The test specimen was then exposed to a burner flame for 10 seconds, and then removed from the flame to record the burning time of each test specimen. Furthermore, the time the flame was maintained after the second exposure (glowing time) and the presence or absence of dripping material that ignited the absorbent cotton placed below the test specimen were recorded. The above procedure was performed five times for each test specimen. The test specimen was then judged as pass / fail, with a rating of "V-0" or "V-1," based on the criteria shown in Table 1 below. In this flame retardancy rating, "V-0" indicates higher flame retardancy than "V-1."

[0096]

[0097] If the test did not achieve V-2, a horizontal flammability test was also conducted in accordance with UL94. The horizontal flammability test was conducted using samples 1 mm thick. Three samples, each measuring 125 mm x 13 mm x 1 mm, were prepared. Marks were made 25 mm and 100 mm from the edge of the sample. The sample was held horizontally and a burner flame was applied to the edge for 30 seconds, or until burning reached the 25 mm mark. The burning time from 25 mm to 100 mm of the sample was then measured. For all three samples, a "HB" rating was met if the sample either did not burn at a rate greater than 75 mm / min between the marks or ceased burning just before the 100 mm mark. However, if only one of the three samples did not meet the requirements, the three samples were retested, and if all met the requirements, the sample was deemed to meet the "HB" rating.

[0098] [Thermal Conductivity] The thermal conductivity (W / m·K) of the thermally conductive molded article was measured by a method in accordance with ASTM D5470-06.

[0099] [Compression Set] A test piece measuring 10 mm x 10 mm and 4 mm thick was prepared, sandwiched between a pair of stainless steel plates, and left at 85°C for 24 hours under 25% compression. The test piece was then released from compression, and the thickness of the test piece was measured after 0.5 hours at 25°C, and the compression set was calculated using the following formula. Details of the compression set measurement conditions were in accordance with JIS K 6262:2013. Compression set = (initial thickness - thickness after test) / (initial thickness - thickness during test). The improvement rate relative to the blank is the ratio of the compression set of the comparison (blank) to the compression set of each example and comparative example, expressed as a percentage.

[0100] The raw materials used in Examples 1 to 21 and Comparative Examples 1 to 9 were as follows: Organopolysiloxane 1: an organopolysiloxane having vinyl groups only on the side chains (weight average molecular weight 22,500, vinyl group concentration 128 μmol / g, viscosity at 23°C 700 mPa·s) Organopolysiloxane 2: an organopolysiloxane having vinyl groups on both ends (weight average molecular weight 17,700, vinyl group concentration 140 μmol / g) Organopolysiloxane 3: a mixture of an organopolysiloxane having vinyl groups on both ends and an organopolysiloxane having hydrosilyl groups on both ends and on the side chains (weight average molecular weight 15,700, vinyl concentration 66 μmol / g, hydrosilyl group concentration 638 μmol / g). Organopolysiloxane 4: A mixture of an organopolysiloxane having vinyl groups on the side chains and an organopolysiloxane having hydrosilyl groups (weight average molecular weight 15,100, vinyl concentration 59 μmol / g, hydrosilyl group concentration 550 μmol / g) Organopolysiloxane 5: A cyclic organopolysiloxane having hydrosilyl groups (hydrosilyl group concentration 4,415 μmol / g) *Organopolysiloxane 1 and Organopolysiloxane 2 contain a catalytic amount of platinum catalyst.

[0101] Dimethyl silicone oil 1: Dimethyl silicone oil (viscosity 300 cs) Dimethyl silicone oil 2: Dimethyl silicone oil (viscosity 110 cs)

[0102] Catalyst: Platinum catalyst Dispersant: Hydroxy group-containing organopolysiloxane, number average molecular weight 5,000, hydroxyl group concentration 25 mg KOH / g, compound having the following structure (n is a number corresponding to the molecular weight):

[0103] Aluminum hydroxide 1: Aluminum hydroxide (irregular, non-anisotropic, D50 = 10 μm) dry surface-treated with 7-octenyltrimethoxysilane. Aluminum hydroxide 2: Aluminum hydroxide (irregular, non-anisotropic, D50 = 10 μm) dry surface-treated with dimethyldimethoxysilane. Aluminum hydroxide 3: Aluminum hydroxide (irregular, non-anisotropic, D50 = 10 μm) dry surface-treated with n-decyltrimethoxysilane. Aluminum hydroxide 4: Aluminum hydroxide (irregular, non-anisotropic, D50 = 54 μm). Aluminum hydroxide 5: Aluminum hydroxide (irregular, non-anisotropic, D50 = 54 μm) dry surface-treated with dimethyldimethoxysilane. Aluminum hydroxide 6: Aluminum hydroxide (irregular, non-anisotropic, D50 = 1.0 μm) surface-treated with stearic acid.

[0104] Aluminum oxide 1: Aluminum oxide (spherical, non-anisotropic, D50 = 41 μm) Aluminum oxide 2: Aluminum oxide dry-surface-treated with 7-octenyltrimethoxysilane (spherical, non-anisotropic, D50 = 41 μm) Aluminum oxide 3: Aluminum oxide dry-surface-treated with dimethyldimethoxysilane (spherical, non-anisotropic, D50 = 2.2 μm) Aluminum oxide 4: Aluminum oxide dry-surface-treated with dimethyldimethoxysilane (spherical, non-anisotropic, D50 = 4.0 μm) Aluminum oxide 5: Aluminum oxide (irregular, non-anisotropic, D50 = 3.0 μm) Aluminum oxide 6: Aluminum oxide (polyhedral, non-anisotropic, D50 = 3.0 μm) Aluminum oxide 7: Aluminum oxide (polyhedral, non-anisotropic, D50 = 0.5 μm) Boron nitride: Boron nitride (flake-like, anisotropic, D50 = 50 μm)

[0105] Coloring pigment: triiron tetroxide (black pigment) Antioxidant: Adeka Stab AO-50 (manufactured by Adeka Corporation)

[0106] [Examples 1 to 20, Comparative Examples 1 to 8] Thermally conductive compositions were obtained by mixing the components according to the formulations shown in Tables 2 to 4. The thermally conductive compositions were cured in a thermostatic chamber at 120°C for 30 minutes to obtain sheet-like thermally conductive members having a thickness of 2.0 mm or a thickness according to the evaluation method.

[0107] [Example 21, Comparative Example 9] The components were mixed according to the formulation shown in Table 4 to obtain a thermally conductive composition. The thermally conductive composition was applied unidirectionally to a polyethylene terephthalate (PET) substrate film at 25°C using a bar coater as an applicator. The anisotropic filler (boron nitride) had its major axis aligned with the application direction. The applied thermally conductive composition was then cured by heating at 80°C for 16 hours to obtain a preliminary sheet having a thickness of 2.0 mm.

[0108] Both sides of each of the obtained preliminary sheets were irradiated with a VUV irradiation device (trade name Excimer MINI, manufactured by Hamamatsu Photonics K.K.) at room temperature (25°C) in the atmosphere with an integrated light dose of 20 mJ / cm on the surface of the primary sheet. ２ Next, 100 of the VUV-irradiated preliminary sheets were stacked and pressed with a roller at a pressure of 1.6 kgf / 50 mm in an environment of 25°C to obtain a laminated block. The obtained laminated block was sliced ​​with a cutter blade parallel to the stacking direction and perpendicular to the orientation direction of the anisotropic filler to obtain a sheet-like thermally conductive member having a thickness of 2 mm or a thickness conforming to the evaluation method, with each unit layer being 500 μm thick.

[0109]

[0110]

[0111]

[0112] [Examples 22 and 23, Comparative Examples 10 and 11] The components were mixed according to the formulations shown in Table 5 to obtain a thermally conductive composition. The thermally conductive composition was poured into a mold, and an 8 T magnetic field was applied in the thickness direction to orient the carbon fibers and flake graphite in the thickness direction. The composition was then cured by heating at 80°C for 60 minutes to obtain a block-shaped oriented molded product. Next, the block-shaped oriented molded product was sliced ​​into sheets using a shearing blade, and further cured by heating at 150°C for 2 hours to obtain a sheet-shaped thermally conductive member having a thickness of 2 mm or a thickness conforming to the evaluation method.

[0113] In Examples 22 and 23 and Comparative Examples 10 and 11, the polyorganosiloxanes 1 to 5, catalyst, and aluminum oxides 6 and 7 were also used as described above. The other raw materials used were as follows: Dimethylsilicone Oil 3: Dimethylsilicone oil (viscosity 1000 cs) Dispersant 2: Hydroxy-containing organopolysiloxane, number average molecular weight 15,000, hydroxyl group concentration 9 mg KOH / g, compound having the following structure (n is a number corresponding to the molecular weight): Aluminum hydroxide 7: amorphous, non-anisotropic, D50 = 10 μm Colorant: pigment Aluminum oxide 8: aluminum oxide, spherical, non-anisotropic, D50 = 25 μm Aluminum: non-anisotropic, D50 = 3.5 μm Carbon fiber 1: average fiber length: 120 μm Carbon fiber 2: average fiber length: 220 μm Carbon fiber 3: average fiber length: 200 μm Carbon fiber 4: average fiber length: 110 μm Flake graphite: flake-like, anisotropic, D50 = 15 μm

[0114]

[0115] The thermally conductive compositions of Examples 1 to 3 and Comparative Examples 2 and 3 are compared with Comparative Example 1, which has substantially the same type and content of thermally conductive filler and silicone matrix (resin component) content. Examples 1 to 3 contain a side-chain alkenyl group-containing organopolysiloxane as the resin component, and the proportion α is within the range of 0.05 to 0.30%. Therefore, compared to Comparative Example 1, the hardness and thermal conductivity are equivalent, but the compression set is improved. On the other hand, Comparative Examples 2 and 3 show no improvement in compression set when silicone oil and a terminal alkenyl group-containing organopolysiloxane are used instead of the side-chain alkenyl group-containing organopolysiloxane. The thermally conductive compositions of Examples 4 to 13 and Comparative Examples 5 and 6 are compared with Comparative Example 4, which has substantially the same type and content of thermally conductive filler and silicone matrix (resin component) content. Examples 4 to 13 contained a side-chain alkenyl group-containing organopolysiloxane as the resin component, and the ratio α was within the range of 0.05 to 0.30%, and thus, compared to Comparative Example 4, the compression set was improved while maintaining the same thermal conductivity. On the other hand, Comparative Example 5, even though silicone oil and a terminal alkenyl group-containing organopolysiloxane were used instead of the side-chain alkenyl group-containing organopolysiloxane, did not show an improvement in compression set compared to Comparative Example 4. Furthermore, Comparative Example 6 used a side-chain alkenyl group-containing organopolysiloxane, but because the ratio α was higher than 0.30%, no improvement in compression set was seen compared to Comparative Example 4. Furthermore, similar trends were observed in the comparisons between Comparative Example 7 and Examples 14 and 15, Comparative Example 8 and Examples 16 to 20, Comparative Example 9 and Example 21, Comparative Example 10 and Example 22, and Comparative Example 11 and Example 23.

Claims

1. A thermally conductive member containing a silicone matrix and a thermally conductive filler, the thermally conductive member was immersed in deuterated chloroform and the extracted components were measured. １ In the H-NMR spectrum, Si—C ｎ H ２ｎ＋１ A thermally conductive member in which the ratio α of the integral value of the multi-peak at 0.45±0.06 ppm to the integral value of the peak of origin (n is an integer of 1 or more) is 0.05% or more and 0.30% or less.

2. The thermally conductive member according to claim 1, having an E hardness of 3 or more and 90 or less.

3. A thermally conductive member according to claim 1 or 2, having a thermal conductivity of 1.0 W / (m·K) or more.

4. The thermally conductive member according to claim 1, wherein the content of said silicone matrix is ​​20% by volume or more and 50% by volume or less.

5. A thermally conductive member according to claim 1 or 4, wherein the content of the thermally conductive filler is 50% by volume or more and 80% by volume or less.

6. The thermally conductive member according to claim 1 or 2, wherein the thermally conductive filler contains at least one of aluminum hydroxide and aluminum oxide.

7. A thermally conductive composition comprising a resin component containing an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane, and a thermally conductive filler, wherein the alkenyl group-containing organopolysiloxane contains an organopolysiloxane having alkenyl groups only on side chains.

8. The thermally conductive composition according to claim 7, wherein the content of organopolysiloxane having alkenyl groups in the side chains in the resin component is 5% by mass or more and 93% by mass or less.

9. The thermally conductive composition according to claim 7 or 8, wherein the ratio of hydrosilyl groups contained in said resin component to alkenyl groups contained in said resin component is 0.36 or more and 2.15 or less on a molar basis.

10. A thermally conductive composition according to claim 7 or 8, wherein the organopolysiloxane having alkenyl groups in its side chains has a functional group concentration of 1 μmol / g or more and 5000 μmol / g or less.

11. The thermally conductive composition according to claim 7 or 8, wherein the hydrosilyl group-containing organopolysiloxane has at least two or more hydrosilyl groups.

12. The thermally conductive composition according to claim 7 or 8, wherein the organopolysiloxane having alkenyl groups in its side chains has a viscosity at 23°C of 50,000 mPas or less.

13. The thermally conductive composition according to claim 7, wherein the content of the resin component is 20% by volume or more and 50% by volume or less.

14. The thermally conductive composition according to claim 7 or 13, wherein the content of the thermally conductive filler is 50% by volume or more and 80% by volume or less.

15. The thermally conductive composition according to claim 7 or 8, wherein the cured product of the thermally conductive composition has an E hardness of 3 or more and 90 or less.

16. The thermally conductive composition according to claim 7 or 8, wherein the thermal conductivity of the cured product of the thermally conductive composition is 1.0 W / (m·K) or more.

17. The cured product of the thermally conductive composition was immersed in deuterated chloroform and the extracted components were measured. １ In the H-NMR spectrum, Si—C ｎ H ２ｎ＋１ The thermally conductive composition according to claim 7 or 8, wherein a ratio α of the integral value of the multi-peak at 0.45±0.06 ppm to the integral value of the peak derived from the multi-peak is 0.05% or more and 0.30% or less.

18. A thermally conductive composition according to claim 7 or 8, wherein the proportion of alkenyl groups in the side chains of the organopolysiloxane relative to the total alkenyl groups contained in the resin component is 20% by mass or more and 100% by mass or less.

19. A thermally conductive member which is a cured product of the thermally conductive composition according to claim 7.

20. The thermally conductive member according to claim 1 or 19, having a three-dimensional shape.

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