Thermally conductive components and hardeners

Abstract

The thermally conductive composition of the present invention contains a polysiloxane main material, a tackifier, and a thermally conductive filler, wherein the ratio (Mw1 / Mw2) of the weight average molecular weight Mw1 of the polysiloxane main material to the weight average molecular weight Mw2 of the tackifier is 0.5 or more and 8.5 or less. According to the present invention, a thermally conductive composition is provided, which contains a polysiloxane base material, a viscosity reducer, and a thermally conductive filler material, and has a high viscosity reduction effect.

Description

[Technical Field]

[0001] This invention relates to a thermally conductive composition and its hardened form. [Previous Technology]

[0002] Regarding thermally conductive components, the most well-known are hardenable liquids that are filled between a heating element and a heat sink, and then hardened to form a hardened material, which is then used as a thermally conductive component to conduct heat emitted by the heating element to the heat sink. Such thermally conductive components often contain a polysiloxane base material and a thermally conductive filler material. Generally, to improve heat dissipation, the content of the thermally conductive filler material must be increased; however, increasing the content of the thermally conductive filler material increases the viscosity of the thermally conductive component, thus worsening its workability. Therefore, to reduce the viscosity of the thermally conductive component, the industry is conducting various studies on the use of viscosity-reducing agents.

[0003] Specifically, the industry is researching the following: using low-viscosity polysiloxanes as the main polysiloxane material or viscosity reducer to reduce the viscosity of the resin component; incorporating low-viscosity viscosity reducers in the largest possible quantity; and using structures with excellent dispersion effects on thermally conductive fillers as viscosity reducers. For example, Patent Documents 1-4 disclose the incorporation of organopolysiloxanes with specific structures into thermally conductive compositions containing polysiloxane main materials and thermally conductive fillers. [Prior Art Documents] [Patent Documents]

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-286855; Patent Document 2: Japanese Patent Application Publication No. 2013-091683; Patent Document 3: Japanese Patent Application Publication No. 2013-227374; Patent Document 4: International Publication No. 2002 / 092693 [Summary of the Invention]

[0005] [The problem the invention aims to solve]

[0006] Although such prior art exists, considering the hardening properties of the thermally conductive composition or its properties after hardening, the amount of viscosity reducer cannot be increased, and there is a limit to the viscosity reduction of the composition. Furthermore, regarding viscosity reducers, various structures have been proposed, and methods using multiple viscosity reducers with different structures have been implemented, but currently, there is a limit to the viscosity reduction of the composition. Therefore, the object of the present invention is to provide a thermally conductive composition containing a polysiloxane base material, a viscosity reducer, and a thermally conductive filler material, and with a higher viscosity reduction effect. [Technical Means for Solving the Problem]

[0007] The inventors conducted active research and discovered a thermally conductive composition containing a polysiloxane main material, a viscosity reducer, and a thermally conductive filler. By setting the ratio (Mw1 / Mw2) of the weight average molecular weight Mw1 of the polysiloxane main material to the weight average molecular weight Mw2 of the viscosity reducer within a specific range, the viscosity of the thermally conductive composition can be effectively reduced, thereby completing the present invention. That is, the present invention provides the following [1] to [8].

[0008] [1] A thermally conductive composition comprising a polysiloxane base material, a tackifier, and a thermally conductive filler, wherein the molecular weight ratio (Mw1 / Mw2) of the weight average molecular weight Mw1 of the polysiloxane base material to the weight average molecular weight Mw2 of the tackifier is 0.5 or more and 8.5 or less. [2] The thermally conductive composition as described in [1] above, wherein the polysiloxane base material comprises: an alkenyl-containing organic polysiloxane and a hydrogenated organic polysiloxane. [3] The thermally conductive composition as described in [1] or [2] above, wherein the tackifier is a compound having an alkoxy group. [4] The thermally conductive composition described in any one of [1] to [3] above, wherein the tack reducer has a structure represented by the following formula (1): (where R1, R2, R4, and R5 are each independently saturated hydrocarbon groups, R3 is an oxygen atom or a divalent hydrocarbon group, n is an integer from 15 to 315, and m is an integer from 0 to 2). [5] The thermally conductive composition described in any one of [1] to [4] above, wherein the weight average molecular weight Mw1 of the polysiloxane main material is 10,000 to 30,000. [6] The thermally conductive composition described in any one of [1] to [5] above, wherein the weight average molecular weight Mw2 of the tack reducer is 1,150 to 20,000. [7] The thermally conductive composition described in any one of [1] to [6] above has a thermal conductivity of 6 W / m·K or higher. [8] A hardened material, formed by hardening the thermally conductive components described in any one of [1] to [7] above. [Effects of the Invention]

[0009] According to the present invention, a thermally conductive composition comprising a polysiloxane base material, a viscosity reducer, and a thermally conductive filler material can be provided, and the viscosity reduction effect is relatively high. Therefore, a thermally conductive composition with improved thermal conductivity and excellent operability can be provided.

Implementation Method

[0011] [Thermal Conductive Composition] Hereinafter, the thermal conductive composition of the present invention will be described in detail. The thermal conductive composition of the present invention contains a polysiloxane base material, a tackifier, and a thermally conductive filler material, and the molecular weight ratio (Mw1 / Mw2) of the weight average molecular weight Mw1 of the polysiloxane base material to the weight average molecular weight Mw2 of the tackifier is 0.5 or more and 8.5 or less.

[0012] <Molecular Weight, Molecular Weight Ratio> The molecular weight ratio (Mw1 / Mw2) of the polysiloxane main material (Mw1) and the viscosity reducer (Mw2) contained in the thermally conductive composition of the present invention is 0.5 or more and 8.5 or less. When the molecular weight ratio (Mw1 / Mw2) is less than 0.5 or more than 8.5, the viscosity reduction effect of the thermally conductive composition due to the addition of the viscosity reducer deteriorates. From the viewpoint of improving the viscosity reduction effect, the molecular weight ratio (Mw1 / Mw2) is preferably 0.9 or more and 8.3 or less, more preferably 1.2 or more and 7.2 or less, and even more preferably 1.4 or more and 4.5 or less.

[0013] By setting the molecular weight ratio (Mw1 / Mw2) within a specified range as described above, a viscosity reduction effect is achieved, the rationale for which is presumably as follows: Regarding the viscosity of the polysiloxane base material, when the dispersion state of the thermally conductive filler is the same, the viscosity of the thermally conductive component is related to the viscosity of the polysiloxane base material. Therefore, the smaller the molecular weight of the polysiloxane base material, the lower the viscosity of the thermally conductive component; conversely, the larger the molecular weight of the polysiloxane base material, the higher the viscosity of the thermally conductive component. However, if the molecular weight of the polysiloxane base material becomes too small, the hardness of the hardened thermally conductive component tends to increase. Therefore, in order to obtain a soft thermally conductive component, the molecular weight of the polysiloxane base material should not become too small; it is preferable to have a certain molecular weight. On the other hand, when the molecular weight of the viscosity reducer is small, its surface coverage of the thermally conductive filler is increased, thereby increasing the viscosity reduction effect. However, if the difference in molecular weight between the viscosity reducer and the polysiloxane base material is large, there is a risk that the compatibility between the polysiloxane base material and the viscosity reducer will deteriorate. On the other hand, when the molecular weight of the viscosity reducer is large, although the dispersion force of the thermally conductive filler material does not increase and the viscosity reduction effect is increased, the molecular chains of the polysiloxane base material and the viscosity reducer will become entangled, thus potentially impairing the viscosity reduction effect. Regarding the viscosity reduction effect resulting from the combined effect of these factors, the optimal range was studied, and the following hypothesis was made: when the molecular weight ratio (Mw1 / Mw2) of the polysiloxane base material (Mw1) to the viscosity reducer (Mw2) is 0.5 or higher and 8.5 or lower, the viscosity reduction effect of the thermally conductive component is greater.

[0014] Furthermore, from the viewpoint of improving viscosity reduction, the lower limit of the molecular weight ratio (Mw1 / Mw2) is preferably 0.9 or higher, more preferably 1.2 or higher, and even more preferably 1.4 or higher. The upper limit of the molecular weight ratio (Mw1 / Mw2) is preferably 8.3 or lower, more preferably 7.2 or lower, and even more preferably 4.5 or lower.

[0015] The weight average molecular weight Mw1 of the polysiloxane main material is not particularly limited, but is preferably 10,000 to 30,000, more preferably 12,000 to 29,500, and even more preferably 14,500 to 29,000. If the weight average molecular weight Mw1 of the polysiloxane main material is above or above these lower limits, cross-linking is easier to achieve when the thermally conductive component is hardened, and the hardened material is easier to impart the desired physical properties. If the weight average molecular weight of the polysiloxane main material is below or above these upper limits, the viscosity of the thermally conductive component is easier to reduce. Furthermore, in this specification, the range indicated by "~" refers to the range above and below the specified value recorded before and after "~".

[0016] Furthermore, the lower limit of the weight average molecular weight Mw1 of the polysiloxane main material is not particularly limited, but it is preferably 10,000 or more, more preferably 12,000 or more, and even more preferably 14,500 or more. If the weight average molecular weight Mw1 of the polysiloxane main material is above or above these lower limits, cross-linking is easier to achieve when the thermally conductive component is cured, and the cured material is more likely to acquire the desired physical properties. On the other hand, the upper limit of the weight average molecular weight Mw1 of the polysiloxane main material is not particularly limited, but it is preferably 30,000 or less, more preferably 29,500 or less, and even more preferably 29,000 or less. If the weight average molecular weight of the polysiloxane main material is below these upper limits, the viscosity of the thermally conductive component is easier to reduce.

[0017] The weight-average molecular weight (Mw2) of the viscosity reducer is not particularly limited, but is preferably 1,150 to 20,000, more preferably 1,300 to 18,000, and even more preferably 1,500 to 15,000. If the weight-average molecular weight (Mw2) of the viscosity reducer is within this range, it is easy to make the weight-average molecular weight (Mw1) of the polysiloxane main material within the above range, and it is easy to adjust the molecular weight ratio (Mw1 / Mw2) to the desired range. As a result, it is easy to improve the viscosity reduction effect of the thermally conductive component, and it is also easy to form a hardened material. Furthermore, in this specification, the weight-average molecular weight is the weight-average molecular weight converted from standard polystyrene by gel permeation chromatography (GPC), specifically determined by the method described in the examples. The weight-average molecular weight of the polysiloxane (PSM) base material and the anti-tack agent can be determined by GPC measurement of each component before the thermally conductive composition is prepared (i.e., before they are mixed). Alternatively, it can be determined by GPC measurement of each component after separating the PSM base material and anti-tack agent from the mixture by filtration. Furthermore, the separation of the PSM base material and anti-tack agent from the mixture can be performed, for example, by ultra-high performance liquid chromatography (UPLC).

[0018] Furthermore, the lower limit of the weight average molecular weight Mw2 of the viscosity reducer is not particularly limited, but it is preferably 1,150 or more, more preferably 1,300 or more, and even more preferably 1,500 or more. If the lower limit of the weight average molecular weight Mw2 of the viscosity reducer is as described above, it is easy to make the weight average molecular weight Mw1 of the polysiloxane main material fall within the above range, and it is easy to adjust the molecular weight ratio (Mw1 / Mw2) to the desired range. As a result, it is easy to improve the viscosity reduction effect of the thermally conductive component, and it is also easy to form a hardened material. Furthermore, the upper limit of the weight average molecular weight Mw2 of the viscosity reducer is not particularly limited, but it is preferably 20,000 or less, more preferably 18,000 or less, and even more preferably 15,000 or less. If the upper limit of the weight average molecular weight Mw2 of the viscosity reducer is as described above, it is easy to ensure that the weight average molecular weight Mw1 of the polysiloxane main material is within the above range, and it is easy to adjust the molecular weight ratio (Mw1 / Mw2) to the desired range. As a result, it is easy to improve the viscosity reduction effect of the thermally conductive component, and it is also easy to form a hardened product.

[0019] <Viscosity, Viscosity Ratio> The viscosity ratio (V1 / V2) of the polysiloxane main material contained in the thermally conductive composition of the present invention at 25°C (viscosity V1) to the viscosity of the viscosity reducer at 25°C (viscosity V2) is preferably 0.5 or more and 15 or less, more preferably 0.7 or more and 12 or less, further preferably 1.0 or more and 10 or less, and further preferably 1.4 or more and 7 or less. By adjusting the viscosity ratio (V1 / V2) to the above range, the viscosity reduction effect of the thermally conductive composition brought about by the incorporation of the viscosity reducer is easily improved.

[0020] Furthermore, the lower limit of the viscosity ratio (V1 / V2) of the polysiloxane main material contained in the thermally conductive composition of the present invention, which is the viscosity V1 at 25°C to the viscosity V2 of the viscosity reducer at 25°C, is preferably 0.5 or more, more preferably 0.7 or more, and even more preferably 1.0 or more, and even more preferably 1.4 or more. By adjusting the lower limit of the viscosity ratio (V1 / V2) to the above range, it is easy to improve the viscosity reduction effect of the thermally conductive composition brought about by the addition of the viscosity reducer. On the other hand, the upper limit of the viscosity ratio (V1 / V2) of the polysiloxane main material contained in the thermally conductive composition of the present invention, which is the viscosity V1 at 25°C to the viscosity V2 of the viscosity reducer at 25°C, is preferably 15 or less, more preferably 12 or less, even more preferably 10 or less, and even more preferably 7 or less. By adjusting the viscosity ratio (V1 / V2) to the above range, it is easy to improve the viscosity reduction effect of the thermally conductive components brought about by the addition of viscosity reducers.

[0021] The viscosity V1 of the polysiloxane base material at 25°C is not particularly limited, but is preferably 50–800 mPa·s, more preferably 80–600 mPa·s, and even more preferably 100–500 mPa·s. If the viscosity V1 of the polysiloxane base material is above or above these lower limits, cross-linking is easier to achieve when the thermally conductive components are hardened, and the hardened material is more easily endowed with the desired physical properties. If the viscosity V1 of the polysiloxane base material is below these upper limits, the viscosity of the thermally conductive components is easier to reduce.

[0022] Furthermore, the lower limit of the viscosity V1 of the polysiloxane base material at 25°C is not particularly limited, but it is preferably 50 mPa·s or more, more preferably 80 mPa·s or more, and even more preferably 100 mPa·s or more. If the viscosity V1 of the polysiloxane base material is at or above these lower limits, cross-linking is easier to achieve when the thermally conductive component is hardened, and the hardened material is more easily endowed with the desired physical properties. On the other hand, the upper limit of the viscosity V1 of the polysiloxane base material at 25°C is not particularly limited, but it is preferably 800 mPa·s or less, more preferably 600 mPa·s or less, and even more preferably 500 mPa·s or less. If the viscosity V1 of the polysiloxane base material is at or below these upper limits, the viscosity of the thermally conductive component is easier to reduce.

[0023] The viscosity V2 of the viscosity reducer at 25°C is not particularly limited, but is preferably 5–300 mPa·s, more preferably 7–250 mPa·s, and even more preferably 10–200 mPa·s. If the viscosity V2 of the viscosity reducer is within this range, it is easy to make the viscosity V1 of the polysiloxane base material within the above range, and it is easy to adjust the viscosity ratio (V1 / V2) to the desired range. As a result, it is easy to improve the viscosity reduction effect of the thermally conductive component, and it is also easy to form a hardened material. Furthermore, the viscosity V1 of the polysiloxane base material and the viscosity V2 of the viscosity reducer at 25°C were measured by the method described in the examples.

[0024] Furthermore, the lower limit of the viscosity V2 of the viscosity reducer at 25°C is not particularly limited, but it is preferably 5 mPa·s or more, more preferably 7 mPa·s or more, and even more preferably 10 mPa·s or more. If the lower limit of the viscosity V2 of the viscosity reducer is within this range, it is easy to make the viscosity V1 of the polysiloxane main material within the above range, and it is easy to adjust the viscosity ratio (V1 / V2) to the desired range. As a result, it is easy to improve the viscosity reduction effect of the thermally conductive component, and it is also easy to form a hardened material. On the other hand, the upper limit of the viscosity V2 of the viscosity reducer at 25°C is not particularly limited, but it is preferably 300 mPa·s or less, more preferably 250 mPa·s or less, and even more preferably 200 mPa·s or less. If the upper limit of the viscosity V2 of the viscosity reducer is within this range, it is easy to make the viscosity V1 of the polysiloxane base material within the above range, and it is easy to adjust the viscosity ratio (V1 / V2) to the desired range. As a result, it is easy to improve the viscosity reduction effect of the thermally conductive components, and it is also easy to form a hardened product.

[0025] <Polysiloxane Main Material> As the polysiloxane main material included in the thermally conductive composition of the present invention, examples include reaction-curing polysiloxane, non-reactive polysiloxane, etc., and preferably at least reaction-curing polysiloxane is included.

[0026] Reaction-curing polysiloxanes are organopolysiloxanes having reactive groups capable of forming cross-linking structures. Examples include addition-reaction-curing polysiloxanes, free-radical-reaction-curing polysiloxanes, condensation-reaction-curing polysiloxanes, ultraviolet or electron beam-curing polysiloxanes, and moisture-curing polysiloxanes. Preferably, the polysiloxane main material is an addition-reaction-curing polysiloxane.

[0027] As an addition reaction-cured polysiloxane, it is more preferably a product containing an alkenyl-containing organopolysiloxane (main agent) and a hydrogenated organopolysiloxane (curing agent). The aforementioned alkenyl-containing organopolysiloxane is preferably an organopolysiloxane having at least two alkenyl groups in one molecule. The alkenyl group is not particularly limited; examples include those with 2 to 8 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, etc. An alkenyl-containing organopolysiloxane can be used alone or in combination of two or more. The aforementioned hydrogenated organopolysiloxane is preferably a hydrogenated organopolysiloxane having at least two hydrosilyl groups in one molecule. Hydrosilyl groups refer to hydrogen atoms (SiH groups) that are bonded to silicon atoms. Hydrogenated organopolysiloxanes can be used alone or in combination of two or more. Addition-curing polysiloxanes react and harden through an addition reaction, thereby forming a matrix composed of polysiloxane rubber. Polysiloxane rubber is easily compressed and deformed; therefore, the hardened product formed from the thermally conductive components of this invention is easily assembled between a heat-generating element and a heat-dissipating element.

[0028] Examples of non-reactive polysiloxanes include pure polysiloxane oils such as dimethyl polysiloxane oil and benzyl polysiloxane oil. Furthermore, examples include non-reactive modified polysiloxane oils formed by introducing non-reactive organic groups into the main chain having siloxane bonds, the side chains bonded to the main chain, or the ends of the main chain. Examples of non-reactive modified polysiloxane oils include: polyether-modified polysiloxane oils, aralkyl-modified polysiloxane oils, fluoroalkyl-modified polysiloxane oils, long-chain alkyl-modified polysiloxane oils, higher fatty acid ester-modified polysiloxane oils, higher fatty acid amine-modified polysiloxane oils, and phenyl-modified polysiloxane oils. Of the above, pure polysiloxane oil is preferred as the non-reactive polysiloxane, and dimethyl polysiloxane oil is more preferred among pure polysiloxane oils. The above-mentioned non-reactive polysiloxane oil can be used alone or in combination of two or more.

[0029] <Thickness Reducing Agent> The thermally conductive composition of the present invention includes a viscosity reducing agent. A viscosity reducing agent is a compound capable of reducing the viscosity of the thermally conductive composition by incorporation therein. Preferably, the viscosity reducing agent is a compound having an alkoxy group, and more preferably, an organopolysiloxane compound having an alkoxy group. By using such a compound as a viscosity reducing agent, the viscosity reduction effect of the thermally conductive composition is improved.

[0030] As a viscosity reducer, it is preferred to have a structure represented by the following formula (1): (where R1, R2, R4, and R5 are each independently saturated hydrocarbon groups, R3 is an oxygen atom or a divalent hydrocarbon group, n is an integer from 15 to 315, and m is an integer from 0 to 2).

[0031] By using a viscosity reducer with the structure represented by formula (1), the viscosity reduction effect of the thermally conductive component is further improved. The reason is presumed to be as follows: The viscosity reducer of formula (1) has an alkoxy group at the end, so it is easy to react or interact with functional groups present on the surface of the thermally conductive filler material. Furthermore, the polysiloxane structure with a specific structure complements each other, thereby reducing the friction of the filler material and making it easier to reduce viscosity.

[0032] In formula (1), R1, R2, R4, and R5 are each independently a saturated hydrocarbon group. Examples of saturated hydrocarbon groups include: straight-chain alkyl, branched alkyl, cyclic alkyl, aryl, aralkyl, haloalkyl, etc. Examples of straight-chain alkyl groups include: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, nonadecanyl, eicosyl, etc. Examples of branched alkyl groups include: isopropyl, tributyl, isobutyl, 2-methylundecyl, 1-hexylheptyl, etc. Examples of cyclic alkyl groups include: cyclopentyl, cyclohexyl, cyclododecyl, etc. Examples of aryl groups include: phenyl, tolyl, xylyl, etc. Examples of aralkyl groups include: benzyl, phenethyl, 2-(2,4,6-trimethylphenyl)propyl, etc. Examples of alkyl halides include 3,3,3-trifluoropropyl and 3-chloropropyl.

[0033] From the viewpoint of improving viscosity reduction, R1 to R5, m, and n in formula (1) are preferably as follows. R1 in formula (1) is preferably an alkyl group with 1 to 8 carbons, more preferably an alkyl group with 2 to 6 carbons, and especially preferably butyl. R2, R4, and R5 in formula (1) are each preferably an alkyl group with 1 to 8 carbons, more preferably an alkyl group with 1 to 4 carbons, and especially preferably methyl. R3 in formula (1) is an oxygen atom or a divalent hydrocarbon group, preferably a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include divalent hydrocarbon groups with 1 or more carbons and 10 or less, and preferably divalent hydrocarbon groups with 1 or more carbons and 4 or less. Examples of divalent hydrocarbon groups include methylene, ethyl, propyl, butyl, methyl ethyl, etc., of which ethyl is preferred.

[0034] In formula (1), n ​​is an integer from 15 to 315, preferably an integer from 18 to 280, and more preferably an integer from 20 to 220. In formula (1), m is an integer from 0 to 2, preferably 0 or 1, and more preferably 0.

[0035] Also, the lower limit of n in equation (1) is an integer of 15 or more, preferably an integer of 18 or more, and even more preferably an integer of 20 or more. On the other hand, the upper limit of n in equation (1) is an integer of 315 or less, preferably an integer of 280 or less, and even more preferably an integer of 220 or less.

[0036] There is no particular limitation on the content of the anti-tack agent in the thermally conductive composition. It can be appropriately determined according to the viscosity setting of the thermally conductive composition. For example, it is 5 to 50 parts by mass relative to 100 parts by mass of the polysiloxane main material, more preferably 8 to 40 parts by mass, and even more preferably 10 to 25 parts by mass. If the content of the anti-tack agent is above or below these lower limits, the viscosity of the thermally conductive composition is easily reduced. If the content of the anti-tack agent is below these upper limits, the hardening of the thermally conductive composition is not easily suppressed, and it is easy to obtain a hardened product with the desired physical properties.

[0037] Furthermore, there is no particular limitation on the lower limit of the content of the anti-tack agent in the thermally conductive composition. It can be appropriately determined according to the viscosity setting of the thermally conductive composition. For example, it is 5 parts by mass or more, preferably 8 parts by mass or more, and more preferably 10 parts by mass or more, relative to 100 parts by mass of the polysiloxane main material. If the content of the anti-tack agent is above or above such a lower limit, the viscosity of the thermally conductive composition is easily reduced. On the other hand, there is no particular limitation on the upper limit of the content of the anti-tack agent in the thermally conductive composition. It can be appropriately determined according to the viscosity setting of the thermally conductive composition. For example, it is 50 parts by mass or less, preferably 40 parts by mass or less, and more preferably 25 parts by mass or less, relative to 100 parts by mass of the polysiloxane main material. If the content of the anti-tack agent is below such an upper limit, the hardening of the thermally conductive composition is not easily suppressed, and a hardened product with the desired physical properties is easily obtained.

[0038] <Thermal Conductive Filler Material> The thermally conductive composition of the present invention contains a thermally conductive filler material. By containing a thermally conductive filler material, the thermal conductivity of the thermally conductive composition and the hardened product formed by hardening the thermally conductive composition is improved. Examples of thermally conductive filler materials include: metals, metal oxides, metal nitrides, metal hydroxides, carbon materials, oxides, nitrides, carbides, etc., other than metals. Furthermore, the shape of the thermally conductive filler material can be spherical, amorphous powder, etc. Examples of thermally conductive filler materials include: metals such as aluminum, copper, and nickel; metal oxides such as aluminum oxide (represented by aluminum oxide), magnesium oxide, and zinc oxide; metal nitrides such as aluminum nitride; and aluminum hydroxide. Furthermore, examples of carbon materials include: spherical graphite, diamond, etc. Examples of oxides, nitrides, and carbides other than metals include quartz, boron nitride, and silicon carbide. Among these, metal oxides, metal nitrides, and carbon materials are preferred as thermally conductive fillers, especially aluminum oxides, aluminum nitride, and diamond, from the perspective of improving thermal conductivity. Furthermore, considering the higher viscosity reduction effect brought about by viscosity reducers, metal oxides are preferred as thermally conductive fillers, and aluminum oxides are even more preferred.

[0039] The lower limit of the average particle size of the thermally conductive filler material is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. Furthermore, the upper limit of the average particle size of the thermally conductive filler material is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 70 μm or less.

[0040] Furthermore, the average particle size of the thermally conductive filler material is preferably 0.1 to 200 μm, more preferably 0.3 to 100 μm, and even more preferably 0.5 to 70 μm. The thermally conductive filler material is preferably a combination of small-particle-size thermally conductive filler material with an average particle size of 0.1 μm or more and 5 μm or less, and large-particle-size thermally conductive filler material with an average particle size of more than 5 μm and 200 μm or less. By using thermally conductive filler materials with different average particle sizes, the filling rate can be improved. Moreover, the average particle size of the thermally conductive filler material can be measured by observation using an electron microscope or the like. More specifically, for example, the particle size of any 50 thermally conductive filler materials can be measured using an electron microscope or an optical microscope, and their average value (arithmetic mean) can be used as the average particle size.

[0041] The content of the thermally conductive filler material relative to 100 parts by weight of the polysiloxane main material is preferably 150 to 4000 parts by weight, more preferably 500 to 3500 parts by weight, and even more preferably 1500 to 3000 parts by weight. Furthermore, when the total amount of the thermally conductive composition is set to 100% by volume, the volume-based content of the thermally conductive filler material is preferably 50 to 95% by volume, more preferably 70 to 93% by volume, and even more preferably 80 to 90% by volume. By setting the content of the thermally conductive filler material to the lower limit or above mentioned above, a certain thermal conductivity can be imparted to the thermally conductive composition and its cured form. By setting the content of the thermally conductive filler material to the upper limit or below mentioned above, the thermally conductive filler material can be properly dispersed. Furthermore, it can also prevent the viscosity of the thermally conductive composition from becoming too high as required.

[0042] Furthermore, the lower limit of the content of the thermally conductive filler material relative to 100 parts by mass of the polysiloxane main material is preferably 150 parts by mass or more, more preferably 500 parts by mass or more, and even more preferably 1500 parts by mass or more. Also, when the total amount of the thermally conductive composition is set to 100% by volume, the lower limit of the volume-based content of the thermally conductive filler material is preferably 50% by volume or more, more preferably 70% by volume or more, and even more preferably 80% by volume or more. By setting the content of the thermally conductive filler material to the above-mentioned lower limit value or above, a certain thermal conductivity can be imparted to the thermally conductive composition and its cured form. On the other hand, the upper limit of the content of the thermally conductive filler material relative to 100 parts by mass of the polysiloxane main material is preferably 4000 parts by mass or less, more preferably 3500 parts by mass or less, and even more preferably 3000 parts by mass or less. Furthermore, when the total amount of the thermally conductive component is set to 100% by volume, the upper limit of the volume-based content of the thermally conductive filler material is preferably 95% by volume or less, more preferably 93% by volume or less, and even more preferably 90% by volume or less. By setting the content of the thermally conductive filler material to the above-mentioned upper limit value or less, the thermally conductive filler material can be properly dispersed. Also, it can prevent the viscosity of the thermally conductive component from becoming too high as required.

[0043] The thermally conductive components of the present invention may contain various additives. Examples of additives include: catalysts, dispersants, flame retardants, plasticizers, antioxidants, colorants, etc.

[0044] <Thermal Conductivity> The thermal conductivity of the thermally conductive component is not particularly limited, but is, for example, 4 W / m·K or higher, preferably 5 W / m·K or higher, more preferably 6 W / m·K or higher, and practically 15 W / m·K or lower. If a thermally conductive component with such thermal conductivity is used, the thermal conductivity of its hardened material also increases, resulting in better heat dissipation when used between a heat-generating element and a heat-dissipating element.

[0045] <Viscosity> The viscosity Va of the thermally conductive composition of the present invention at a temperature of 25°C and a shear rate of 1.00 (1 / s) is preferably 600 Pa·s or less, more preferably 550 Pa·s or less, and even more preferably 530 Pa·s or less. By making the thermally conductive composition have the viscosity described above, operability is easily improved. Furthermore, the thixotropic ratio [viscosity Vb / viscosity Va] of the thermally conductive composition can be appropriately adjusted according to the application of the thermally conductive composition, preferably 0.35 or more, more preferably 0.39 or more, and more preferably 0.80 or less, and even more preferably 0.71 or less. Moreover, the viscosity Vb refers to the viscosity of the thermally conductive composition at a temperature of 25°C and a shear rate of 4.64 (1 / s).

[0046] The thermally conductive composition of the present invention can be in the form of a single liquid or a two-liquid composition consisting of a first agent and a second agent, but from the viewpoint of preserving stability, a two-liquid composition is preferred. In the two-liquid thermally conductive composition, the mass ratio of the first agent to the second agent (second agent / first agent) is preferably 1 or a value close to 1, specifically, preferably 0.9 to 1.1, more preferably 0.95 to 1.05. Thus, by setting the mass ratio of the first agent to the second agent to 1 or a value close to 1, the thermally conductive composition is easily prepared. Furthermore, in the two-liquid thermally conductive composition, the viscosity ratio of the first agent to the second agent (second agent / first agent) is also preferably 1 or a value close to 1, specifically, preferably 0.5 to 2.0, more preferably 0.8 to 1.2. Thus, by setting the viscosity ratio of the first agent to the second agent to 1 or a value close to 1, the thermally conductive components can be easily and uniformly mixed. Furthermore, the method for adjusting the mass ratio or viscosity ratio will be described later.

[0047] When using the above-mentioned addition-reaction-cured polysiloxane containing an alkenyl group (main agent) and a hydrogenated organosiloxane (curing agent), the two-liquid thermally conductive components are more specifically, the first agent contains an alkenyl group-containing organosiloxane (main agent), and the second agent contains a hydrogenated organosiloxane (curing agent). The addition reaction catalyst is preferably included in the first agent and not in the second agent. This ensures excellent stability of the first and second agents before mixing, promotes the reaction after mixing, and allows for rapid curing, resulting in improved physical properties of the thermally conductive component obtained through curing. Although the exact factors are uncertain, the reason is presumed to be that addition reaction catalysts such as platinum catalysts, being located at the alkenyl group at the "addition reaction site of the main agent," facilitate curing.

[0048] The thermally conductive filler material may be included in at least one of the first agent and the second agent, preferably in both the first agent and the second agent. If the thermally conductive filler material is included in both the first agent and the second agent, it is easy to mix the first agent and the second agent. Furthermore, since the mass ratio and viscosity ratio of the second agent relative to the first agent when producing the thermally conductive composition can be set to 1 or a value close to 1, it is easy to use in a two-component form. Also, the second agent preferably contains an alkenyl-containing organopolysiloxane. By including an alkenyl-containing organopolysiloxane as a main agent in addition to a hydrogenated organopolysiloxane as a curing agent in the second agent, it is easy to adjust the mass ratio and viscosity ratio of the second agent relative to the first agent when producing the thermally conductive composition to a value close to 1. On the other hand, the first agent may not contain a hydrogenated organopolysiloxane as a curing agent.

[0049] The above-mentioned thermally conductive composition contains polysiloxane as the main material, a viscosity reducer, and a thermally conductive filler, and has a reduced viscosity compared to conventional thermally conductive compositions, i.e., a thermally conductive composition with a higher viscosity reduction effect.

[0050] [Curved Material] By curing the thermally conductive component of the present invention, a cured material of the thermally conductive component can be formed. The thermal conductivity of the cured material is not particularly limited, but is, for example, 4 W / m·K or higher, preferably 5 W / m·K or higher, more preferably 6 W / m·K or higher, and practically 15 W / m·K or lower. Furthermore, in the present invention, the term "cured state" can be considered, for example, as follows: when the "heat of reaction until the end of curing" measured using a differential scanning calorimeter (DSC) is set to 100%, the degree of progress of the curing reaction estimated from the heat of reaction is 50% or higher. This cured material can be disposed between a heating element and a heat sink, etc., and used as a heat dissipation component. [Example]

[0051] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples in any way.

[0052] [Weight-average molecular weight Mw1 of polysiloxane main material] For the sample after mixing polysiloxane A agent and polysiloxane B agent, which constitute the polysiloxane main material, gel permeation chromatography (GPC) (manufactured by Waters Corporation, RI: 2414, automatic sampler Alliance: e2695, guard column: KF-G, column: two Shodex KF806L in series) was performed to determine the weight-average molecular weight Mw1 of the polysiloxane main material. The weight-average molecular weight is the weight-average molecular weight converted from standard polystyrene. As a polystyrene standard sample (Shodex Standard SM-105 manufactured by Showa Denko Corporation), nine samples with the following weight-average molecular weights were used. Standard sample Nos (weight average molecular weight) for each sample: S-1.3 (1270), S-3.2 (3180), S-6.9 (6940), S-22 (21800), S-53 (52500), S-333 (333000), S-609 (609000), S-1345 (1350000), S-2704 (2700000). Molecular weight was plotted relative to the dissolution time indicated by the peak apex of each standard sample, and the resulting approximate straight line was used as a calibration curve. The polysiloxane base material sample was dissolved in tetrahydrofuran to prepare a 0.2 wt% solution. This solution was filtered using a 0.2 μm filter and then used for GPC determination. GPC determination was performed at a column temperature of 40°C, using tetrahydrofuran as the dissolution solution, and the flow rate of the mobile phase in the column was set to 1 mL / min.

[0053] [Weight-average molecular weight Mw2 of the viscosity reducer] In addition to using the viscosity reducer as a sample, the weight-average molecular weight Mw2 was determined by GPC in the same manner as the polysiloxane main material.

[0054] [Viscosity of Polysiloxane Main Material and Thickness Reducer] The viscosity V1 of the polysiloxane main material at 25°C and the viscosity V2 of the thickening agent at 25°C were measured as follows. Anton Paar MCR-302e rheometer was used. The sample temperature was adjusted to 25°C using a Peltier plate. A cone plate with an angle of 1° and a diameter of ϕ50 mm was used. The viscosity was measured while continuously changing the shear rate within the range of 10–100 (1 / sec). Furthermore, the viscosity V1 of the polysiloxane main material at 25°C and the viscosity V2 of the thickening agent at 25°C refer to the viscosity at a shear rate of 10 (1 / s).

[0055] [Viscosity of Adhesive] The viscosity of the adhesive was determined using the same method as that used to determine the viscosity V1 of the polysiloxane main material, before the curing reaction, using a sample (adhesive) after mixing polysiloxane A agent and polysiloxane B agent, which constitute the polysiloxane main material.

[0056] [Viscosity of the thermally conductive component] For the sample (thermally conductive component) immediately after mixing the first and second agents, before the hardening reaction, the temperature of the sample was adjusted to 25°C using an Anton Paar MCR-302e rheometer with a Peltier plate. Using a parallel plate with an ϕ25 mm diameter, the viscosity was measured while continuously changing the shear rate within the range of 1 to 10 (1 / s). The viscosities at shear rates of 1.00 (1 / s), 2.15 (1 / s), and 4.64 (1 / sec) are recorded in the table. The ratio (Vb / Va) of the viscosity Va at a shear rate of 1.00 (1 / sec) and the viscosity Vb at a shear rate of 4.64 (1 / sec), obtained by the above-described measurements, is taken as the thixotropic ratio.

[0057] [Thermal Conductivity of Thermally Conductive Components] The thermal conductivity of the thermally conductive components was determined by measuring the thermal resistance using a measuring apparatus according to ASTM D5470-06. Specifically, the thermally conductive component was prepared as a film thicker than the thickness required for measurement, covering the measuring die that became the heat source. It was then clamped by a heat sink and compressed under a load of 30 psi until the thickness of the thermally conductive component reached 0.9 mm, 0.8 mm, and 0.7 mm. The thermal resistance at each thickness was measured. For these three thermal resistance values, a graph was plotted with thickness on the horizontal axis and thermal resistance value on the vertical axis. An approximate straight line was obtained from the three points using the least squares method. The slope of this approximate straight line represents the thermal conductivity. The thermal resistance measurement was performed at 80°C using an LW-9389 manufactured by Long Win Science and Technology Corporation. The area of ​​the measuring die was set to 1 inch × 1 inch.

[0058] Examples 1 to 16 and Comparative Examples 1 to 9 were evaluated based on the following comprehensive evaluations 1 and 2.

[0059] [Overall Evaluation 1] The viscosity Va of the thermally conductive component at a shear rate of 1.00 (1 / sec) is less than 600 Pa·s, which is considered to be the qualified standard and is evaluated as "OK". The viscosity Va is more than 600 Pa·s, which is considered to be the unqualified standard and is evaluated as "NG".

[0060] [Comprehensive Evaluation 2] In the thermally conductive compositions of each embodiment and comparative example, the relative value (%) of viscosity Va and viscosity Va of each embodiment and comparative example where the viscosity Va of the lowest thermally conductive composition in the same comparative object group with only different types of viscosity reducers is set to 100% are evaluated according to the following criteria. Furthermore, the relative value is the value obtained by rounding the first decimal place. 5: Relative value is 100-104%, and viscosity Va is 600 Pa·s or less. 4: Relative value is 105-129%, and viscosity Va is 600 Pa·s or less. 3: Relative value is 130-199%, and viscosity Va is 600 Pa·s or less. 2: Relative value is 200% or more, and viscosity Va is 600 Pa·s or less. 1: Viscosity Va exceeds 600 Pa·s.

[0061] Furthermore, in the above comprehensive evaluation 2, the same group of comparative objects that differs only in the type of viscosity reducer is specifically as follows: • Examples 1-4, Comparative Example 1 • Examples 5-7, Comparative Examples 2-3 • Examples 8-10, Comparative Examples 4-5 • Examples 11-13, Comparative Examples 6-7 • Examples 14-16, Comparative Examples 8-9

[0062] <Polysiloxane Main Material> The polysiloxane main material uses the following A-1 to A-5. A-1 to A-5 are addition-reaction cured polysiloxanes containing alkenyl-containing organic polysiloxanes (main agents) and hydrogenated organic polysiloxanes (curing agents), and are two-component polysiloxane A agents and polysiloxane B agents. The mixture of these two liquids constitutes the polysiloxane main material. A-1: Viscosity V1 is 114 mPa·s, weight-average molecular weight Mw1 is 13,500. A-2: Viscosity V1 is 224 mPa·s, weight-average molecular weight Mw1 is 20,000. A-3: Viscosity V1 is 252 mPa·s, weight-average molecular weight Mw1 is 22,000. A-4: Viscosity V1 is 320 mPa·s, weight-average molecular weight Mw1 is 25,000. A-5: Viscosity V1 is 453 mPa·s, weight-average molecular weight Mw1 is 29,000.

[0063] <Viscosity Reducer> As an organopolysiloxane compound with an alkoxy group representing the structure of formula (1), B-1 to B-4 and B-5, which is dimethyl polysiloxane, can be used. B-1: In formula (1), R1 = butyl, R2 = methyl, R3 = ethyl, R5 = methyl, n = 20, m = 0. The viscosity V2 is 11 mPa·s, and the weight average molecular weight Mw2 is 1,640. B-2: In formula (1), R1 = butyl, R2 = methyl, R3 = ethyl, R5 = methyl, n = 55, m = 0. The viscosity V2 is 25 mPa·s, and the weight average molecular weight Mw2 is 3,500. B-3: In formula (1), R1 = butyl, R2 = methyl, R3 = ethyl, R5 = methyl, n = 125, m = 0. The viscosity V2 is 68 mPa·s, and the weight-average molecular weight Mw2 is 8,000. B-4: In formula (1), R1 = butyl, R2 = methyl, R3 = ethyl, R5 = methyl, n = 219, m = 0. The viscosity V2 is 157 mPa·s, and the weight-average molecular weight Mw2 is 14,000. B-5: Dimethyl polysiloxane with a viscosity V2 of 10 mPa·s and a weight-average molecular weight Mw2 of 1100.

[0064] [Example 1] As shown in Table 2, the type of polysiloxane main material is designated as A-1, and the type of anti-tack agent is designated as B-1. Various evaluations were performed on the thermal conductivity components of Composition 1 shown below. <Composition 1> Composition 1, as shown in Table 1, is a two-liquid composition of Agent 1 and Agent 2. Polysiloxane Agent A contains an alkenyl-containing organic polysiloxane and a trace amount of addition reaction catalyst (platinum catalyst). Polysiloxane Agent B contains an alkenyl-containing organic polysiloxane and a hydrogenated organic polysiloxane. Agent 1 consists of 100 parts by weight of polysiloxane A, 17.5 parts by weight of a thickener, 230 parts by weight of spherical alumina with an average particle size of 0.5 μm, 550 parts by weight of spherical alumina with an average particle size of 3.0 μm, 160 parts by weight of spherical alumina with an average particle size of 18 μm, 300 parts by weight of spherical alumina with an average particle size of 40 μm, and 1100 parts by weight of spherical alumina with an average particle size of 70 μm. Agent 2 consists of 100 parts by weight of polysiloxane B, 17.5 parts by weight of a thickener, 230 parts by weight of spherical alumina with an average particle size of 0.5 μm, 550 parts by weight of spherical alumina with an average particle size of 3.0 μm, 160 parts by weight of spherical alumina with an average particle size of 18 μm, 300 parts by weight of spherical alumina with an average particle size of 40 μm, and 1100 parts by weight of spherical alumina with an average particle size of 70 μm. A thermally conductive composition is prepared by mixing the first and second agents.

[0065] [Examples 2-16, Comparative Examples 1-9] The types of polysiloxane main materials and the types of anti-tack agents were changed as shown in Tables 2-6. Otherwise, thermally conductive compositions were prepared in the same manner as in Example 1. The evaluation results are shown in Tables 2-6.

[0066] [Table 1] Component 1 Composition 2 Composition 3 Composition 4 First dose Second dose First dose Second dose First dose Second dose First dose Second dose Polysiloxane main materials A-1 to A-5 Polysiloxane A agent Quality 100 100 100 100 Polysiloxane B agent 100 100 100 100 Viscosity reducers B-1 to B-5 17.5 17.5 15 15 12.5 12.5 17.5 17.5 Thermally conductive filler material The average particle size of the spherical alumina is 0.5 μm. 230 230 230 230 230 230 300 300 The average particle size of the spherical alumina is 3.0 μm. 550 550 550 550 550 550 690 690 The average particle size of the spherical alumina is 18 μm. 160 160 160 160 160 160 200 200 The average particle size of the spherical alumina is 40 μm. 300 300 300 300 300 300 375 375 The average particle size of the spherical alumina is 70 μm. 1100 1100 1100 1100 1100 1100 1375 1375 Volume percentage of polysiloxane main material 14.4 14.5 14.6 11.9 Volume percentage of viscosity reducer 2.6 2.2 1.8 2.1 Volume percentage of thermally conductive filler material 83.0 83.3 83.6 86.0

[0067] [Table 2] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Types of composition Component 1 Component 1 Component 1 Component 1 Component 1 Types of polysiloxane main materials A-1 A-1 A-1 A-1 A-1 Types of viscosity reducers B-1 B-2 B-3 B-4 B-5 Viscosity V1 of polysiloxane main material [mPa・s] 114 114 114 114 114 Viscosity V2 of the viscosity reducer [mPa・s] 11 25 68 157 10 Viscosity ratio (V1 / V2) 10.4 4.6 1.7 0.7 11.4 Adhesive viscosity [mPa·s] 76 94 104 121 74 Polysiloxane main material Mw1 13500 13500 13500 13500 13500 Viscosity reducer Mw2 1640 3500 8000 14000 1100 Molecular weight ratio (Mw1 / Mw2) 8.2 3.9 1.7 1.0 12.3 Viscosity of thermally conductive components [Pa·s] 1.00 [1 / s] 456 263 184 335 - 2.15 [1 / s] 286 188 125 253 - 4.64 [1 / s] 180 131 121 231 - Thixotropic ratio 0.39 0.54 0.66 0.69 - Thermal conductivity component viscosity / adhesive viscosity 6.0 2.7 1.8 2.8 13.4 Thermal conductivity [W / m・K] 6.0 6.0 6.0 6.0 - Overall rating 1 OK OK OK OK NG Overall rating 2 2 4 5 3 1 Remark Unable to determine Not made into slurry

[0068] Examples 1-4 and Comparative Example 1 in Table 2 are the same group of comparative objects where only the type of anti-tack agent differs in the thermally conductive components. The thermally conductive components of examples with a molecular weight ratio (Mw1 / Mw2) of 0.5 or higher and 8.5 or lower for the weight average molecular weight Mw1 of the polysiloxane main material to the weight average molecular weight Mw2 of the anti-tack agent have lower viscosity, and the results of Comprehensive Evaluation 1 and Comprehensive Evaluation 2 are good. Furthermore, Examples 2 and 3, with a molecular weight ratio (Mw1 / Mw2) of 1.4 or higher and 4.5 or lower, received a high evaluation of 4 or higher in Comprehensive Evaluation 2. In contrast, Comparative Example 1, with a molecular weight ratio (Mw1 / Mw2) exceeding 8.5, had too high a viscosity and did not form a paste, therefore no evaluations were conducted. It can be seen that although a lower weight-average molecular weight Mw2 was used as a viscosity reducer, the viscosity of the thermally conductive component did not decrease accordingly. The important thing is to adjust the molecular weight ratio (Mw1 / Mw2) to the specific range of the present invention.

[0069] [Table 3] Comparative Example 2 Example 5 Example 6 Example 7 Comparative Example 3 Types of composition Component 1 Component 1 Component 1 Component 1 Component 1 Types of polysiloxane main materials A-2 A-2 A-2 A-2 A-2 Types of viscosity reducers B-1 B-2 B-3 B-4 B-5 Viscosity V1 of polysiloxane main material [mPa・s] 224 224 224 224 224 Viscosity V2 of the viscosity reducer [mPa・s] 11 25 68 157 10 Viscosity ratio (V1 / V2) 20.3 8.9 3.3 1.4 22.4 Adhesive viscosity [mPa·s] 132 165 182 210 130 Polysiloxane main material Mw1 20000 20000 20000 20000 20000 Viscosity reducer Mw2 1640 3500 8000 14000 1100 Molecular weight ratio (Mw1 / MW2) 12.2 5.7 2.5 1.4 18.2 Viscosity of thermally conductive components [Pa·s] 1.00 [1 / s] 637 443 350 305 930 2.15 [1 / s] 369 283 258 264 444 4.64 [1 / s] 238 211 188 210 152 Thixotropic ratio 0.37 0.47 0.54 0.69 0.16 Thermal conductivity component viscosity / adhesive viscosity 4.8 2.5 1.9 1.5 7.2 Thermal conductivity [W / m・K] 6.0 6.0 6.0 6.0 6.0 Overall rating 1 NG OK OK OK NG Overall rating 2 1 3 4 5 1 Remark

[0070] Examples 5-7 and Comparative Examples 2-3 in Table 3 are the same group of comparative examples where only the type of anti-tack agent differs in the thermally conductive components. The thermally conductive components of examples with a molecular weight ratio (Mw1 / Mw2) of 0.5 or higher and 8.5 or lower for the weight average molecular weight Mw1 of the polysiloxane main material to the weight average molecular weight Mw2 of the anti-tack agent have lower viscosity, and the results of Comprehensive Evaluation 1 and Comprehensive Evaluation 2 are good. Furthermore, Examples 6 and 7, with a molecular weight ratio (Mw1 / Mw2) of 1.4 or higher and 4.5 or lower, received a high evaluation of 4 or higher in Comprehensive Evaluation 2. In contrast, the results of Comprehensive Evaluation 1 and 2 for Comparative Examples 2 and 3, with a molecular weight ratio (Mw1 / Mw2) exceeding 8.5, are worse than those of the examples. It can be seen that although a lower weight-average molecular weight Mw2 was used as a viscosity reducer, the viscosity of the thermally conductive component did not decrease accordingly. The important thing is to adjust the molecular weight ratio (Mw1 / Mw2) to the specific range of the present invention.

[0071] [Table 4] Comparative Example 4 Example 8 Example 9 Example 10 Comparative Example 5 Types of composition Component 1 Component 1 Component 1 Component 1 Component 1 Types of polysiloxane main materials A-3 A-3 A-3 A-3 A-3 Types of viscosity reducers B-1 B-2 B-3 B-4 B-5 Viscosity V1 of polysiloxane main material [mPa・s] 252 252 252 252 252 Viscosity V2 of the viscosity reducer [mPa・s] 11 25 68 157 10 Viscosity ratio (V1 / V2) 22.9 10.1 3.7 1.6 25.2 Adhesive viscosity [mPa·s] 146 182 200 232 143 Polysiloxane main material Mw1 22000 22000 22000 22000 22000 Viscosity reducer Mw2 1640 3500 8000 14000 1100 Molecular weight ratio (Mw1 / Mw2) 13.4 6.3 2.8 1.6 20.0 Viscosity of thermally conductive components [Pa·s] 1.00 [1 / s] 677 456 370 338 906 2.15 [1 / s] 395 291 273 283 513 4.64 [1 / s] 239 210 194 219 247 Thixotropic ratio 0.35 0.46 0.52 0.65 0.27 Thermal conductivity component viscosity / adhesive viscosity 4.6 2.5 1.8 1.5 6.3 Thermal conductivity [W / m・K] 6.0 6.0 6.0 6.0 6.0 Overall rating 1 NG OK OK OK NG Overall rating 2 1 3 4 5 1 Remark

[0072] Examples 8-10 and Comparative Examples 4-5 in Table 4 are the same group of comparative examples where only the type of anti-tack agent differs in the thermally conductive components. The thermally conductive components of examples with a molecular weight ratio (Mw1 / Mw2) of 0.5 or higher and 8.5 or lower for the weight average molecular weight Mw1 of the polysiloxane main material to the weight average molecular weight Mw2 of the anti-tack agent have lower viscosity, and the results of Comprehensive Evaluation 1 and Comprehensive Evaluation 2 are good. Furthermore, Examples 9 and 10, with a molecular weight ratio (Mw1 / Mw2) of 1.4 or higher and 4.5 or lower, received a high evaluation of 4 or higher in Comprehensive Evaluation 2. In contrast, the results of Comprehensive Evaluation 1 and 2 for Comparative Examples 4 and 5, with a molecular weight ratio (Mw1 / Mw2) exceeding 8.5, are worse than those of the examples. It can be seen that although a lower weight-average molecular weight Mw2 was used as a viscosity reducer, the viscosity of the thermally conductive component did not decrease accordingly. The important thing is to adjust the molecular weight ratio (Mw1 / Mw2) to the specific range of the present invention.

[0073] [Table 5] Comparative Example 6 Example 11 Example 12 Example 13 Comparative Example 7 Types of composition Component 1 Component 1 Component 1 Component 1 Component 1 Types of polysiloxane main materials A-4 A-4 A-4 A-4 A-4 Types of viscosity reducers B-1 B-2 B-3 B-4 B-5 Viscosity V1 of polysiloxane main material [mPa・s] 320 320 320 320 320 Viscosity V2 of the viscosity reducer [mPa・s] 11 25 68 157 10 Viscosity ratio (V1 / V2) 29.1 12.8 4.7 2.0 32.0 Adhesive viscosity [mPa·s] 177 221 244 283 174 Polysiloxane main material Mw1 25000 25000 25000 25000 25000 Viscosity reducer Mw2 1640 3500 8000 14000 1100 Molecular weight ratio (Mw1 / Mw2) 15.2 7.1 3.1 1.8 22.7 Viscosity of thermally conductive components [Pa·s] 1.00 [1 / s] 819 513 441 404 874 2.15 [1 / s] 475 329 330 334 561 4.64 [1 / s] 302 244 256 274 322 Thixotropic ratio 0.37 0.49 0.58 0.68 0.37 Thermal conductivity component viscosity / adhesive viscosity 4.6 2.4 1.8 1.4 5.0 Thermal conductivity [W / m・K] 6.0 6.0 6.0 6.0 6.0 Overall rating 1 NG OK OK OK NG Overall rating 2 1 3 4 5 1 Remark

[0074] Examples 11-13 and Comparative Examples 6-7 in Table 5 are the same group of comparative objects where only the type of anti-tack agent differs in the thermally conductive components. The thermally conductive components of examples with a molecular weight ratio (Mw1 / Mw2) of 0.5 or higher and 8.5 or lower for the weight average molecular weight Mw1 of the polysiloxane main material to the weight average molecular weight Mw2 of the anti-tack agent have lower viscosity, and the results of Comprehensive Evaluation 1 and Comprehensive Evaluation 2 are good. Furthermore, Examples 12 and 13, with a molecular weight ratio (Mw1 / Mw2) of 1.4 or higher and 4.5 or lower, received a high evaluation of 4 or higher in Comprehensive Evaluation 2. In contrast, the results of Comprehensive Evaluation 1 and 2 for Comparative Examples 6 and 7, with a molecular weight ratio (Mw1 / Mw2) exceeding 8.5, are worse than those of the examples. It can be seen that although a lower weight-average molecular weight Mw2 was used as a viscosity reducer, the viscosity of the thermally conductive component did not decrease accordingly. The important thing is to adjust the molecular weight ratio (Mw1 / Mw2) to the specific range of the present invention.

[0075] [Table 6] Comparative Example 8 Example 14 Example 15 Example 16 Comparative Example 9 Types of composition Component 1 Component 1 Component 1 Component 1 Component 1 Types of polysiloxane main materials A-5 A-5 A-5 A-5 A-5 Types of viscosity reducers B-1 B-2 B-3 B-4 B-5 Viscosity V1 of polysiloxane main material [mPa・s] 453 453 453 453 453 Viscosity V2 of the viscosity reducer [mPa・s] 11 25 68 157 10 Viscosity ratio (V1 / V2) 41.2 18.1 6.7 2.9 45.3 Adhesive viscosity [mPa·s] 236 295 325 376 232 Polysiloxane main material Mw1 29000 29000 29000 29000 29000 Viscosity reducer Mw2 1640 3500 8000 14000 1100 Molecular weight ratio (Mw1 / MW2) 17.7 8.3 3.6 2.1 26.4 Viscosity of thermally conductive components [Pa·s] 1.00 [1 / s] 875 599 508 456 985 2.15 [1 / s] 502 435 374 381 618 4.64 [1 / s] 321 295 288 320 358 Thixotropic ratio 0.37 0.52 0.57 0.70 0.36 Thermal conductivity component viscosity / adhesive viscosity 3.7 2.0 1.6 1.2 4.2 Thermal conductivity [W / m・K] 6.0 6.0 6.0 6.0 6.0 Overall rating 1 NG OK OK OK NG Overall rating 2 1 3 4 5 1 Remark

[0076] Examples 14-16 and Comparative Examples 8-9 in Table 6 are the same group of comparative objects, differing only in the type of anti-tack agent in each thermally conductive component. The thermally conductive components of examples with a molecular weight ratio (Mw1 / Mw2) of 0.5 or higher and 8.5 or lower for the weight average molecular weight Mw1 of the polysiloxane main material to the weight average molecular weight Mw2 of the anti-tack agent have lower viscosity, and the results of Comprehensive Evaluation 1 and Comprehensive Evaluation 2 are good. Furthermore, Examples 15 and 16, with a molecular weight ratio (Mw1 / Mw2) of 1.4 or higher and 4.5 or lower, received a high evaluation of 4 or higher in Comprehensive Evaluation 2. In contrast, the results of Comprehensive Evaluation 1 and 2 for Comparative Examples 8 and 9, with a molecular weight ratio (Mw1 / Mw2) exceeding 8.5, are worse than those of the examples. It can be seen that although a lower weight-average molecular weight Mw2 was used as a viscosity reducer, the viscosity of the thermally conductive component did not decrease accordingly. The important thing is to adjust the molecular weight ratio (Mw1 / Mw2) to the specific range of the present invention.

[0077] The thermally conductive compositions of Examples 17-21 and Comparative Examples 10-11 were evaluated using thermally conductive compositions with compositions different from those of Examples 1-16 and Comparative Examples 1-9 described above.

[0078] [Examples 17-21, Comparative Examples 10-11] As shown in Table 7, the types of polysiloxane main material, the types of anti-tack agents, and the types of thermally conductive components were set, and thermally conductive components were prepared and evaluated. Furthermore, components 2-4 are as shown in Table 1.

[0079] [Table 7] Example 17 Example 18 Comparative Example 10 Example 19 Example 20 Example 21 Comparative Example 11 Types of composition Composition 2 Composition 3 Composition 4 Composition 4 Composition 4 Composition 4 Composition 4 Types of polysiloxane main materials A-4 A-4 A-4 A-4 A-4 A-4 A-4 Types of viscosity reducers B-3 B-3 B-1 B-2 B-3 B-4 B-5 Viscosity V1 of polysiloxane main material [mPa・s] 320 320 320 320 320 320 320 Viscosity V2 of the viscosity reducer [mPa・s] 68 68 11 25 68 157 10 Viscosity ratio (V1 / V2) 4.7 4.7 29.1 12.8 4.7 2.0 32.0 Adhesive viscosity [mPa·s] 244 244 177 221 244 283 174 Polysiloxane main material Mw1 25000 25000 25000 25000 25000 25000 25000 Viscosity reducer Mw2 8000 8000 1640 3500 8000 14000 1100 Molecular weight ratio (Mw1 / Mw2) 3.1 3.1 15.2 7.1 3.1 1.8 22.7 Viscosity of thermally conductive components [Pa·s] 1.00 [1 / s] 479 518 1454 1096 986 1186 - 2.15 [1 / s] 337 366 - 599 620 819 - 4.64 [1 / s] 256 289 - 312 444 512 - Thixotropic ratio 0.53 0.56 - 0.28 0.45 0.43 - Thermal conductivity component viscosity / adhesive viscosity 2.0 2.1 8.2 5.0 4.0 4.2 - Thermal conductivity [W / m・K] 6.1 6.2 7.0 7.0 7.0 7.0 - Parts by weight of the viscosity reducer relative to 100 parts by weight of the main material 15.0 12.5 17.5 17.5 17.5 17.5 17.5 Volume percentage of thermally conductive filler 83.3 83.6 86.0 86.0 86.0 86.0 86.0 Remark Unable to determine Not made into slurry

[0080] Examples 17 and 18 are examples of preparing thermally conductive compositions by reducing the amount of thickener compared to Example 12. It is evident that thermally conductive compositions with low viscosity were obtained in Examples 17 and 18. Examples 19-21 and Comparative Examples 10-11 are examples of increasing the content of thermally conductive filler material. In this case, the viscosity of the thermally conductive compositions of Examples 19-21, whose molecular weight ratio (Mw1 / Mw2) satisfies 0.5 or more and 8.5 or less, is also lower than that of Comparative Examples 10-11, whose molecular weight ratio (Mw1 / Mw2) exceeds 8.5. Furthermore, Comparative Example 10 has significantly higher fluidity; therefore, its viscosity could not be properly measured at a shear rate of 2.15 (1 / s) or higher. The viscosity of Comparative Example 11 was too high to form a slurry, therefore, no evaluations could be performed. [Simplified Explanation of the Diagram]

[0010] None

Claims

1. A thermally conductive composition comprising a polysiloxane main material, a tackifier, and a thermally conductive filler, wherein the molecular weight ratio (Mw1 / Mw2) of the polysiloxane main material to the tackifier is 0.5 or more and 8.5 or less, and the tackifier has a structure represented by the following formula (1): (wherein, R1, R2, R4, and R5 are each independently saturated hydrocarbon groups, R3 is a divalent hydrocarbon group, n is an integer from 15 to 315, and m is an integer from 0 to 2).

2. As in claim 1, the thermally conductive component, wherein, The aforementioned polysiloxane main materials include: alkenyl-containing organic polysiloxanes and hydrogenated organic polysiloxanes.

3. The thermally conductive component as claimed in claim 1 or 2, wherein, The aforementioned viscosity reducers are compounds containing alkoxy groups.

4. The thermally conductive component as claimed in claim 1 or 2, wherein, The weight average molecular weight (Mw1) of the aforementioned polysiloxane main material is 10,000 to 30,000.

5. The thermally conductive component as claimed in claim 1 or 2, wherein, The weight-average molecular weight (Mw2) of the above-mentioned viscosity reducers is 1,150 to 20,000.

6. The thermally conductive components of claim 1 or 2 have a thermal conductivity of 6 W / m·K or higher.

7. A hardened material formed by hardening any one of the thermally conductive components of claims 1 to 6.