Thermally conductive member, thermally conductive composition, structure, and method for reworking a structure

Abstract

This thermally conductive member comprises a polymer matrix, a phase-change material having a melting point of greater than 25°C but no greater than 120°C, and a thermally conductive filler. When the thermally conductive member is sandwiched between glass cloth films, and is left to stand for 40 hours under 10% compression at 90°C, the percentage weight change B of the thermally conductive member is 0.05% to 3.0%.

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive member, a thermally conductive composition, a structure, and a method for reworking a structure. [Background technology]

[0002] A thermally conductive composition is used as a thermally conductive member that is filled between a heat generating element and a heat sink, and then hardened to transfer heat generated by the heat generating element to the heat sink. Because the thermally conductive composition has fluidity, it can fill any gap between the heat generating element and the heat sink, and is therefore used as a thermally conductive gap filler.

[0003] For example, Patent Document 1 discloses a crosslinked rubber composition based on a room-temperature curing silicone elastomer and containing at least one phase change material (PCM) as a thermally conductive composition. The crosslinked rubber composition described in Patent Document 1 has a Shore A hardness of 20 to 90, and is indicated to be incorporated into thermal control or regulation systems that can be used for passive air conditioning of buildings, heating of passenger cabins or engines of automobiles, airplanes or spacecraft, and underwater pipelines. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-28948 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, thermally conductive compositions have been considered for use as structural adhesives, embedded between lithium-ion batteries mounted in automobiles and cooling plates, in order to efficiently cool the batteries. However, if a battery malfunctions, the battery and cooling plate must be disassembled to repair or replace the battery. However, conventional thermally conductive compositions have excellent heat resistance and their adhesive strength does not decrease once bonded, so there is a risk that loads will be applied to each component during disassembly, causing damage to each component. Furthermore, since such disassembly requires a considerable amount of force, large-scale equipment is required, which is a problem as it requires a great deal of effort.

[0006] Patent Document 1 discloses that heat is released or absorbed by the phase change of the PCM, but does not disclose that this can be used to improve reworkability.

[0007] An object of the present invention is to provide a thermally conductive member and a thermally conductive composition that exhibit excellent reworkability even after bonding, as well as a structure having excellent reworkability and a method for reworking the structure. [Means for solving the problem]

[0008] After extensive research, the inventors discovered that the above problem can be solved by incorporating a phase-change material having a melting point within a specific range into a thermally conductive member and adjusting the weight loss rate of the thermally conductive member when left under certain conditions for a certain period of time to fall within a predetermined range, and thus completed the following invention. That is, the present invention provides the following [1] to

[15] .

[0009] [1] A thermally conductive member comprising a polymer matrix, a phase-change material having a melting point greater than 25°C and less than or equal to 120°C, and a thermally conductive filler, wherein the thermally conductive member has a weight loss rate B of 0.05% or more and 3.0% or less when sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours. [2] The thermally conductive member according to [1], wherein the modulus of elasticity G25 at 25°C and the modulus of elasticity G90 at 90°C satisfy the relationship of the following formula (1).

number

number

[10] A structure comprising a heat generating element, a heat dissipating element, and a thermally conductive member that bonds the heat generating element and the heat dissipating element, wherein the thermally conductive member comprises a polymer matrix, a phase change material having a melting point greater than 25°C and less than or equal to 120°C, and a thermally conductive filler, and the thermally conductive member is cut into a shape of 20 mm x 20 mm and 2 mm thick, and the thermally conductive member cut into said shape is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours. When this is done, the weight loss rate B of the thermally conductive member is 0.05% or more and 3.0% or less.

[11] The structure according to

[10] , wherein the heat generating element is a battery cell, and the heat dissipating element is a battery module case, a battery pack case, or a cooling plate.

[12] A structure comprising a heat generating element, a heat dissipating element, and a thermally conductive member that bonds the heat generating element and the heat dissipating element, wherein the thermally conductive member comprises a polymer matrix, a phase change material having a melting point greater than 25°C and less than 120°C, and a thermally conductive filler, and wherein the adhesive strength between the heat generating element and the heat dissipating element at 25°C is 0.05 MPa or more and 2.0 MPa or less, and the adhesive strength between the heat generating element and the heat dissipating element after heating at 90°C is smaller than the adhesive strength and is 0.2 MPa or less.

[13] A thermally conductive composition comprising a liquid polymer that is a precursor of a polymer matrix, a phase-change material having a melting point greater than 25°C and less than or equal to 120°C, and a thermally conductive filler, wherein a cured product of the thermally conductive composition is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours, and the weight loss rate B of the cured product is 0.05% or more and 3.0% or less.

[14] The thermally conductive composition according to

[13] , which is a combination of a first part filled in a first container, the first part including a main part made of the liquid polymer, a phase-change material having a melting point higher than 25°C and lower than 120°C, and a thermally conductive filler, and a curing agent made of the liquid polymer, a phase-change material having a melting point higher than 25°C and lower than 120°C, and a thermally conductive filler, and a second part filled in a second container.

[15] A method for reworking a structure including a heat generating element, a heat sink, and a thermally conductive member disposed between the heat generating element and the heat sink, wherein the thermally conductive member includes a polymer matrix, a phase change material having a melting point greater than 25°C and less than or equal to 120°C, and a thermally conductive filler, the method comprising heating the structure to a temperature equal to or greater than the melting point of the phase change material, and then peeling the heat generating element and the heat sink apart. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a thermally conductive member and a thermally conductive composition that can exhibit excellent reworkability even after bonding, as well as a structure having excellent reworkability and a method for reworking the structure. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a schematic diagram showing a sample for measuring weight loss rate B. [Figure 2] FIG. 2 is a schematic diagram showing a sample for a tensile test when measuring adhesive strength. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Thermal conductive material] The thermally conductive member of the present invention includes a polymer matrix, a phase-change material having a melting point higher than 25° C. and lower than or equal to 120° C., and a thermally conductive filler. The thermally conductive member of the present invention can be obtained by curing a thermally conductive composition described below. The thermally conductive member of the present invention can exhibit excellent reworkability by heating it to a temperature equal to or higher than the melting point of the phase-change material. Furthermore, even if the thermally conductive member of the present invention is temporarily heated above the melting point of the phase-change material during actual use, when it is cooled again below the melting point of the phase-change material, the phase-change material will solidify again, resulting in almost no decrease in adhesive strength compared to before heating.

[0013] (Weight reduction rate) The thermally conductive member of the present invention has a weight loss rate B (hereinafter simply referred to as "weight loss rate B") of 0.05% to 3.0% when sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours. If the weight loss rate B is less than 0.05%, the liquefied phase-change material will not bleed out sufficiently, which may result in insufficient reworkability after bonding the thermally conductive member. If the weight loss rate B exceeds 3.0%, the liquefied phase-change material will bleed out excessively. For example, when the thermally conductive member is used in a structure described below, this may contaminate the heat generating element or heat dissipating element, causing malfunctions of the heat generating element or heat dissipating element. In light of the above, the weight loss rate B is preferably 0.1% to 2.0%, more preferably 0.2% to 1.5%. The weight loss rate B can be adjusted to a desired range by, for example, the type, melting point, and content of the phase change material.

[0014] The weight loss rate B can be determined by the following method. 1, a sample 14 made of the thermally conductive member produced in each example and comparative example is sandwiched between glass cloth films 15 attached to a compression jig 11, and the sample 14 is compressed by 10% by tightening screws 12 fixed to spacers 13 to obtain a measurement sample 10. Thereafter, the measurement sample 10 is left in an environment at 90°C for 40 hours. After the above-mentioned leaving, the measurement sample 10 is returned to room temperature (25°C), the sample 14 is removed from the compression jig 11 to which the glass cloth film 15 is attached, and the weight of the sample 14 is measured and used as the weight of the sample 14 after leaving. In addition, the weight of the sample 14 before attaching it to the compression jig 11 is measured and used as the weight of the sample 14 before leaving. From the measured weights of the sample 14 before and after leaving, the weight loss rate B is calculated using the following formula. Weight loss rate B (%) = (weight (g) of sample 14 before being left - weight (g) of sample 14 after being left) / weight (g) of sample 14 before being left × 100

[0015] (elastic modulus) The thermally conductive member of the present invention preferably has a modulus of elasticity at 25° C. (hereinafter referred to as "G25") and a modulus of elasticity at 90° C. (hereinafter referred to as "G90") that satisfy the relationship of the following formula (1).

number

[0016] When the ratio of G25 to G90 (G25 / G90) is 1.2 or greater, the thermally conductive member's elastic modulus decreases significantly upon heating, making it easier to achieve excellent reworkability. From this perspective, G25 / G90 is preferably 2.3 or greater, and more preferably 4.5 or greater. From the perspective of reworkability, the higher the G25 / G90, the better, and there is no particular upper limit. However, from the perspective of ensuring a certain level of mechanical strength even at high temperatures and making it easier to maintain a certain level of adhesive strength after the thermally conductive member is heated and cooled, the ratio is, for example, 40 or less, preferably 30 or less, and more preferably 25 or less. The elastic modulus in the present invention is a storage modulus measured using a rheometer under conditions of 1% strain and 1 Hz frequency. Specifically, G25 and G90 can be measured by the method described in the Examples.

[0017] G90 is preferably 800,000 Pa or less, more preferably 500,000 Pa or less, and even more preferably 300,000 Pa or less. When G90 is the above upper limit or less, G25 / G90 is set to a certain level or more, and excellent reworkability is easily achieved. From the viewpoint of reworkability, the lower the G90, the better, and there is no particular lower limit. However, from the viewpoint of ensuring a certain level of mechanical strength even at high temperatures, it is, for example, 5,000 Pa or more, preferably 10,000 Pa or more, more preferably 15,000 Pa or more.

[0018] G25 is preferably 40,000 Pa or more, more preferably 50,000 Pa or more, and even more preferably 60,000 Pa or more. When G25 is equal to or greater than the lower limit, excellent reworkability is easily achieved by setting G25 / G90 to a certain value or more. From the viewpoint of easily imparting appropriate adhesive strength in a 25°C environment, G25 is preferably 1,000,000 Pa or less, more preferably 950,000 Pa or less, and even more preferably 920,000 Pa or less. The elastic modulus can be adjusted to a desired range by, for example, the type, melting point, and content of the phase-change material, the type of polymer matrix, and the like.

[0019] In the thermally conductive member of the present invention, the weight loss rate B, G25, and G90 preferably satisfy the relationship of the following formula (2).

[0020]

number

[0021] When the ratio of the weight loss rate B to G90 / G25 (B / (G90 / G25)) is 0.001 or more, excellent reworkability is likely to be exhibited. On the other hand, if B / (G90 / G25) is 1.0 or less, contamination of the heat generating element or heat sink can be easily prevented when the thermally conductive material is used in a structure, as described below. Furthermore, if B / (G90 / G25) is 1.0 or less, the G90 / G25 ratio does not become too small, the rate of decrease in the elastic modulus of the thermally conductive material when heated can be suppressed to a certain level or less, and the adhesive strength of the thermally conductive material after it has been heated and cooled can be easily maintained at a certain level or more. From the above viewpoints, B / (G90 / G25) is more preferably 0.002 or more and 0.5 or less, even more preferably 0.005 or more and 0.1 or less, and even more preferably 0.011 or more and 0.05 or less.

[0022] (thermal conductivity) The thermal conductivity of the thermally conductive material is preferably 1.0 W / m·K or higher, more preferably 1.5 W / m·K or higher, and even more preferably 2.0 W / m·K or higher. Setting the thermal conductivity above these lower limits ensures good thermal conductivity. Therefore, when used as a gap filler in a battery cell module, for example, the heat generated from the battery cells can be efficiently transferred to the module housing via the gap filler, preventing excessive increases in the temperature of the battery cells. The higher the thermal conductivity of the thermally conductive material, the better, but in practical use, it is, for example, 15 W / m·K or lower. Thermal conductivity is measured in accordance with ASTM D5470.

[0023] (Phase change materials) The thermally conductive member of the present invention includes a phase change material having a melting point greater than 25°C and less than or equal to 120°C. If the melting point of the phase change material is 25°C or less, the adhesive strength of the thermally conductive member may decrease during actual use, for example, during use in a structure described below. Furthermore, the phase change material may bleed out of the thermally conductive member, potentially contaminating the heating element or heat sink, a risk that increases particularly in the summer. Furthermore, if the melting point exceeds 120°C, the thermally conductive member must be heated to a high temperature during rework, and the high temperature during rework may cause malfunctions in the heating element or heat sink. For example, when reworking a thermally conductive member included in a lithium-ion battery, the high temperature during rework may cause malfunctions in the lithium-ion battery. From the above viewpoints, the melting point of the phase change material is preferably 30°C or higher and 100°C or lower, more preferably 40°C or higher and 85°C or lower, and even more preferably 50°C or higher and 80°C or lower. The melting points of the phase-change materials can be measured by heating a measurement sample at a heating rate of 10°C / min using a differential scanning calorimeter (DSC) as described in the Examples. The melting points of the phase-change materials referred to here are melting points measured using a thermally conductive member containing each phase-change material as a measurement sample. The phase change material contained in the thermally conductive member of the present invention is preferably at least one selected from ester compounds and hydrocarbon compounds.

[0024] <Ester compounds> The ester compound may be a monoester having one ester group, or a diester or other compound having two or more ester groups, but is preferably a monoester having 12 to 44 carbon atoms. By using a monoester having a carbon number within the above range, the melting point of the phase change material can be set within a predetermined range, and a thermally conductive member with excellent reworkability can be obtained. From this perspective, the carbon number of the monoester is more preferably 15 to 44, even more preferably 25 to 44, and even more preferably 28 to 40.

[0025] The ester compound is preferably an ester of a fatty acid and an alcohol. The number of carbon atoms in the fatty acid is preferably 2 or more and 25 or less, more preferably 7 or more and 22 or less, and even more preferably 12 or more and 18 or less. The number of carbon atoms in the fatty acid means the total number of carbon atoms including the carbonyl carbon of the carboxyl group. The alcohol may be an alcohol having one hydroxyl group or an alcohol having two or more hydroxyl groups. The number of carbon atoms in the alcohol is preferably 2 or more and 25 or less, more preferably 4 or more and 22 or less, and even more preferably 12 or more and 18 or less. Of the above ester compounds, esters of monocarboxylic acids and alcohols having one hydroxyl group are preferred. Specific examples of the ester compound include stearyl stearate, pentaerythritol distearate, cetyl myristate, myristyl stearate, behenyl behenylate, glycerin monostearyl ester, and ethylene glycol distearyl ester. Among these, at least one selected from stearyl stearate, cetyl myristate, and behenyl behenylate is preferred. Among these, stearyl stearate is more preferred from the viewpoint of obtaining the melting point most suitable for reworking the thermally conductive member. The ester compounds may be used alone or in combination of two or more.

[0026] <Hydrocarbon compounds> The hydrocarbon compound is not particularly limited as long as it has a melting point of more than 25°C and not more than 120°C, but is preferably an aliphatic hydrocarbon, more preferably paraffin, and even more preferably a linear aliphatic hydrocarbon. Examples of linear aliphatic hydrocarbons include n-octadecane (melting point 28°C), n-nonadecane (melting point 32°C), n-eicosane (melting point 37°C), n-heneicosane (melting point 40°C), n-docosane (melting point 44°C), n-tricosane (melting point 48 to 50°C), n-tetracosane (melting point 52°C), n-pentacosane (melting point 53 to 56°C), n-hexacosane (melting point 55 to 58°C), n-heptacosane (melting point 60°C), n-octacosane (melting point 62°C), and n-nonacosane. Examples of such compounds include triacontane (melting point 63 to 66°C), n-triacontane (melting point 66°C), n-tetratriacontane (melting point 73°C), pentatriacontane (melting point 75°C), n-hexatriacontane (melting point 74 to 76°C), n-heptatriacontane (melting point 77 to 79°C), n-octatriacontane (melting point 77°C), n-nonatriacontane (melting point 80 to 82°C), n-tetracontane (melting point 81°C), and n-hentetracontane (melting point 74 to 76°C). The hydrocarbon compounds may be used alone or in combination of two or more.

[0027] The thermally conductive member of the present invention preferably uses an ester compound as the phase change material. Compared to hydrocarbon compounds, ester compounds have relatively low compatibility with polymer matrices. Therefore, when an ester compound is included as the phase change material, the ester compound is more likely to bleed out when the thermally conductive member is heated, which makes it easier to impart excellent reworkability to the thermally conductive member. Furthermore, compared to adding hydrocarbon compounds, a small amount of ester compound can be added to achieve a predetermined amount of bleed-out, making it easier to relatively increase the content of other components. For example, increasing the content of the polymer matrix can easily increase mechanical strength and adhesiveness, and increasing the content of the thermally conductive filler can easily increase thermal conductivity.

[0028] The content of the phase change material is preferably 10 to 70 parts by mass, more preferably 15 to 70 parts by mass, and even more preferably 20 to 67 parts by mass, per 100 parts by mass of the polymer matrix. When the content of the phase change material is equal to or greater than the lower limit, the thermal conductive member is more likely to have excellent reworkability. Furthermore, when the content of the phase change material is equal to or less than the upper limit, the amount of phase change material that bleeds out during rework of the thermal conductive member is kept below a certain level, thereby preventing contamination of the heating element and heat sink.

[0029] The phase change material may be contained in the thermally conductive member in powder form, or may be mixed with a compatibilizer, for example, and then dissolved in a polymer matrix before being contained in the thermally conductive member. However, it is preferable that the phase change material be contained in the thermally conductive member in powder form. The phase change material can be incorporated into the thermally conductive member in a powder state by mixing the powder state with a liquid polymer without dissolving it in a compatibilizer, etc. By incorporating the phase change material in a powder state, it is not necessary to use a compatibilizer, so the proportion of the polymer matrix in the thermally conductive member can be increased, and the phase change material can be incorporated into the thermally conductive member without reducing the adhesiveness or mechanical strength of the thermally conductive member. Furthermore, when the phase-change material is incorporated into the thermally conductive member in powder form, it is preferable not to heat the thermally conductive composition to a temperature equal to or higher than the melting point of the phase-change material when preparing the composition, and it is more preferable to prepare the composition at a temperature 10°C or more lower than the melting point of the phase-change material. By not melting the powdered phase-change material, it is possible to prevent the viscosity of the thermally conductive composition from increasing more than necessary, and by incorporating the powdered phase-change material into the thermally conductive member, it is easier to improve adhesion compared to when the material is dissolved in the entire polymer matrix.

[0030] (polymer matrix) The thermally conductive member of the present invention contains a polymer matrix, which is obtained by curing a liquid polymer. Here, the liquid polymer is a polymer that is liquid at room temperature (25° C.), and examples thereof include raw materials for obtaining polymer matrices such as silicone rubber and polyurethane resin. The liquid polymer may be a non-reactive compound having no reactive groups, or a reactive compound having reactive groups, such as alkenyl groups, hydrosilyl groups, hydroxyl groups, and isocyanate groups.

[0031] Examples of liquid polymers include organopolysiloxanes, polyols, and polyisocyanates. The liquid polymer may be a single component or a mixture of two or more components. Among these, organopolysiloxanes are preferred as liquid polymers. That is, the polymer matrix constituting the thermally conductive member of the present invention is preferably a cured product of organopolysiloxane. Using organopolysiloxane as the liquid polymer makes it easier to increase the filling rate of the thermally conductive filler and improve the thermal conductivity of the thermally conductive member.

[0032] The organopolysiloxane may be, for example, an organopolysiloxane having a reactive group or an organopolysiloxane having no reactive group, but is preferably an organopolysiloxane having a reactive group. The organopolysiloxane having a reactive group is an organopolysiloxane having a reactive group capable of forming a crosslinked structure, and examples thereof include addition reaction curable silicones, radical reaction curable silicones, condensation reaction curable silicones, ultraviolet or electron beam curable silicones, and moisture curable silicones. Among these, the organopolysiloxane having a reactive group is preferably an addition reaction curable silicone. In other words, when the polymer matrix constituting the thermally conductive member of the present invention is a cured product of an organopolysiloxane, it is preferably a cured product of an addition reaction curable silicone.

[0033] The addition reaction curing type silicone is more preferably one containing an alkenyl group-containing organopolysiloxane (base resin) and a hydrogen organopolysiloxane (curing agent). The alkenyl group-containing organopolysiloxane is preferably an organopolysiloxane having at least two alkenyl groups per molecule. The alkenyl group is not particularly limited, but examples include those having 2 to 8 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, and octenyl. The alkenyl group-containing organopolysiloxanes can be used alone or in combination of two or more. The hydrogen organopolysiloxane is preferably a hydrogen organopolysiloxane having at least two hydrosilyl groups per molecule. A hydrosilyl group refers to a hydrogen atom bonded to a silicon atom (SiH group). The hydrogen organopolysiloxane may be used alone or in combination of two or more. The addition reaction curing silicone reacts and cures by addition reaction to form a matrix made of silicone rubber. Because silicone rubber is easily deformed by compression, the cured product formed from the thermally conductive composition of the present invention can be easily assembled between a heat generating element and a heat sink.

[0034] (Thermal conductive filler) The thermally conductive member of the present invention contains a thermally conductive filler, which improves the thermal conductivity of the thermally conductive member. Examples of the thermally conductive filler include metals, metal oxides, metal nitrides, metal hydroxides, carbon materials, oxides, nitrides, carbides, etc. The shape of the thermally conductive filler may be spherical or irregular powder. In the thermally conductive filler, examples of metals include aluminum, copper, nickel, etc.; examples of metal oxides include aluminum oxide, such as alumina, magnesium oxide, and zinc oxide; and examples of metal nitrides include aluminum nitride. Examples of metal hydroxides include aluminum hydroxide. Furthermore, examples of carbon materials include spherical graphite and diamond. Examples of oxides, nitrides, and carbides other than metals include quartz, boron nitride, and silicon carbide. Among these, aluminum oxide and aluminum hydroxide are preferred as the thermally conductive filler, and it is preferable to use aluminum oxide and aluminum hydroxide in combination.

[0035] The average particle size of the thermally conductive filler is preferably 0.1 μm or more and 200 μm or less, more preferably 0.3 μm or more and 100 μm or less, and even more preferably 0.5 μm or more and 70 μm or less. It is preferable to use a small-particle size thermally conductive filler with an average particle size of 0.1 μm to 5 μm inclusive in combination with a large-particle size thermally conductive filler with an average particle size of more than 5 μm to 200 μm inclusive in combination. By using thermally conductive fillers with different average particle sizes, the filling rate can be increased. The average particle size of the thermally conductive filler can be measured by observation using an electron microscope, etc. More specifically, for example, the particle sizes of 200 particles of any thermally conductive filler can be measured using an electron microscope or an optical microscope, and the average value (arithmetic mean value) can be used as the average particle size.

[0036] The content of the thermally conductive filler is preferably 100 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, and even more preferably 500 parts by mass or more and 1600 parts by mass or less, relative to 100 parts by mass of the total amount of the polymer matrix and the phase change material. By setting the content of the thermally conductive filler to the above lower limit or more, a certain level of thermal conductivity can be imparted to the thermally conductive composition and the thermally conductive member. By setting the content of the thermally conductive filler to the above upper limit or less, the thermally conductive filler can be properly dispersed. Furthermore, the viscosity of the thermally conductive composition can be prevented from becoming higher than necessary.

[0037] (dispersant) The thermally conductive member of the present invention may contain a dispersant. The inclusion of a dispersant makes it easier to disperse the thermally conductive filler in the polymer matrix, making it easier to impart excellent thermal conductivity to the thermally conductive member. The dispersant is preferably a silicon compound, and more preferably at least one selected from the group consisting of an alkoxysilane compound and an alkoxysiloxane compound.

[0038] Examples of alkoxysilane compounds include methyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, methylcyclohexyldimethoxysilane, methylcyclohexyldiethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, and n-decyltriethoxysilane. Among these, from the viewpoint of reducing the viscosity of the thermally conductive composition, n-decyltrimethoxysilane, dimethyldimethoxysilane, and n-octyltriethoxysilane are preferred, and n-decyltrimethoxysilane is more preferred.

[0039] Examples of the alkoxysiloxane compound include methyl methoxy siloxane oligomer, methyl phenyl methoxy siloxane oligomer, methyl epoxy methoxy siloxane oligomer, methyl mercapto methoxy siloxane oligomer, and methyl acryloyl methoxy siloxane oligomer.

[0040] One or more types of dispersants can be used. When a dispersant is used in the thermally conductive member, the content of the dispersant is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, relative to 100 parts by mass of the polymer matrix. When the content of the dispersant is equal to or greater than these lower limits, the thermally conductive filler can be easily dispersed in the polymer matrix. On the other hand, when the content of the dispersant is equal to or less than these upper limits, a decrease in the heat resistance of the thermally conductive member can be suppressed. The dispersant, particularly the alkoxysilane compound, may function as a compatibilizer, as described below. Furthermore, since alkoxysilane compounds such as n-decyltrimethoxysilane are volatile, bubbles originating from the alkoxysilane compound may be generated in the thermally conductive member. However, by setting the content to the above upper limit or less, the generation of bubbles originating from the alkoxysilane compound can be suppressed.

[0041] (Other ingredients) The thermally conductive member of the present invention preferably contains a catalyst for curing the liquid polymer. For example, when the liquid polymer is an addition reaction curable silicone, an addition reaction catalyst such as a platinum catalyst can be used as the catalyst. The thermally conductive member may also contain a compatibilizer as described above. The compatibilizer is not particularly limited as long as it is a compound that is compatible with a liquid polymer at room temperature (25°C), but an ester compound that is liquid at 25°C is preferred. The ester compound used as a compatibilizer may be a monoester or a diester, but a monoester is preferred. The ester compound used as a compatibilizer may be, for example, an ester of a fatty acid such as a saturated aliphatic acid with an alcohol such as an alkanol, and examples thereof include octyl laurate, 1-methylheptyl laurate, isopropyl myristate, 1-methylheptyl myristate, and isopropyl palmitate. The thermally conductive member may also contain additives other than those mentioned above, such as a flame retardant, an antioxidant, a colorant, and the like.

[0042] [Thermal conductive composition] The thermally conductive composition of the present invention comprises a liquid polymer that is a precursor of a polymer matrix, a phase change material having a melting point greater than 25°C and less than or equal to 120°C, and a thermally conductive filler, and the thermally conductive member is obtained by curing the thermally conductive composition. Each of these components of the thermally conductive composition has been described above, and therefore a detailed description thereof will be omitted. The melting point of the phase-change material is the melting point measured using a sample of the cured thermally conductive composition. The content of each component in the thermally conductive composition is the same as that in the thermally conductive member, except that the reference amount is 100 parts by mass of the liquid polymer instead of 100 parts by mass of the polymer matrix. In addition to the above components, the thermally conductive composition of the present invention may contain various additives such as the above-mentioned dispersants, catalysts, and compatibilizers.

[0043] The thermally conductive composition of the present invention exhibits a weight loss rate B of 0.05% to 3.0% when a cured product thereof is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours. Having the weight loss rate B within the above range prevents excessive bleeding of the phase change material, thereby improving reworkability. The weight loss rate B is preferably 0.1% or more and 2.0% or less, and more preferably 0.2% or more and 1.5% or less. The weight loss rate of the cured product of the thermally conductive composition can be determined by measuring a cured product sample obtained by curing the thermally conductive composition using the same method as for the thermally conductive member. In this case, the cured product sample should be one in which the thermally conductive composition has been substantially completely cured, and should be cured by leaving it at room temperature for a long period of time, for example, as described in the Examples below. Furthermore, the cured product of the thermally conductive composition of the present invention is similar to the thermally conductive member in terms of G25, G90, the ratio of G25 to G90 (G25 / G90), and the ratio of the weight loss rate B to G90 / G25 [B / (G90 / G25)], and therefore further explanation will be omitted.

[0044] (viscosity) The thermally conductive composition of the present invention preferably has a viscosity of 400 Pa·s or more and 50,000 Pa·s or less, more preferably 500 Pa·s or more and 30,000 Pa·s or less, and even more preferably 800 Pa·s or more and 100,000 Pa·s or less, as measured with a rheometer at a measurement temperature of 25°C and a shear rate of 0.1 (1 / s). If the viscosity of the thermally conductive composition is equal to or greater than the lower limit, the viscosity may become too low, preventing dripping and other problems. If the viscosity of the thermally conductive composition is equal to or less than the upper limit, workability, such as coatability, is likely to be improved.

[0045] (adhesive strength) The thermally conductive composition of the present invention preferably has an adhesive strength after heating to 90°C (hereinafter also referred to as "adhesive strength after heating") of 80% or less, more preferably 75% or less, and even more preferably 40% or less, of the initial adhesive strength when the thermally conductive composition is used to adhere an adherend, taken as 100%. The initial adhesive strength is the adhesive strength at room temperature (25°C) of a sample obtained by bonding a specific adherend described in the Examples via a thermally conductive composition and curing the thermally conductive composition. The post-heat adhesive strength is the adhesive strength after heating the sample to 90°C. When the ratio of the post-heating adhesive strength to the initial adhesive strength is equal to or less than the upper limit, the degree of decrease in adhesive strength due to heating of the thermally conductive member increases, and excellent reworkability is likely to be exhibited. Furthermore, the post-heating adhesive strength, when the initial adhesive strength is taken as 100%, is not particularly limited, but is preferably 3% or more, more preferably 5% or more, and even more preferably 8% or more. If the post-heating adhesive strength, when the initial adhesive strength is taken as 100%, is at least a certain level, it is possible to prevent a significant decrease in adhesive strength even when used in a high-temperature environment. Furthermore, it is easier to maintain the post-recovery adhesive strength, which will be described later, at least a certain level. The initial adhesive strength, adhesive strength after heating, and adhesive strength after recovery, which will be described later, can all be measured by the method described in the Examples.

[0046] The thermally conductive composition of the present invention preferably has an initial adhesive strength of 0.05 MPa or more, more preferably 0.08 MPa or more, and even more preferably 0.1 MPa or more. When the initial adhesive strength is equal to or greater than the above lower limit, the thermally conductive member is more likely to exhibit excellent adhesiveness. The initial adhesive strength is not particularly limited, but from the viewpoint of appropriately controlling the adhesive strength of the thermally conductive member and improving its ease of handling, it is, for example, 2.0 MPa or less, preferably 1.0 MPa or less, and more preferably 0.5 MPa or less.

[0047] The thermally conductive composition of the present invention preferably has a post-heating adhesive strength of 0.2 MPa or less, more preferably 0.15 MPa or less, and even more preferably 0.07 MPa or less. When the post-heating adhesive strength is equal to or less than the above upper limit, excellent reworkability is likely to be exhibited. Furthermore, from the viewpoint of easily maintaining a certain level of adhesive strength after the thermally conductive member is once heated and cooled, the post-heating adhesive strength is preferably 0.003 MPa or more, more preferably 0.005 MPa or more, and even more preferably 0.008 MPa or more. Note that the post-heating adhesive strength is the adhesive strength in a heated temperature environment.

[0048] The thermally conductive composition of the present invention preferably has a ratio (post-recovery adhesive strength / initial adhesive strength) of the adhesive strength when heated to 90°C and then cooled to 25°C (hereinafter also referred to as "post-recovery adhesive strength") to the initial adhesive strength of 0.7 or more, more preferably 1 or more, and even more preferably 1.05 or more. When the post-recovery adhesive strength / initial adhesive strength is equal to or greater than the above lower limit, the thermally conductive member has excellent reworkability and can maintain good adhesive strength even when heated to high temperatures during use. The post-recovery adhesive strength / initial adhesive strength is not particularly limited, but from the viewpoint of appropriately controlling the adhesive strength of the thermal conductive member and improving handling properties, it is good for the ratio to be, for example, 1.7 or less, and preferably 1.4 or less. The post-recovery adhesive strength is preferably 0.05 MPa or more, more preferably 0.08 MPa or more, and even more preferably 0.1 MPa or more. When the post-recovery adhesive strength is equal to or greater than the above-mentioned lower limit, the thermally conductive member is more likely to exhibit excellent adhesiveness. Furthermore, from the viewpoint of appropriately controlling the adhesive strength of the thermally conductive member and improving its ease of handling, the upper limit of the post-recovery adhesive strength is preferably 2.0 MPa or less, more preferably 1.0 MPa or less, and even more preferably 0.5 MPa or less. The above-mentioned adhesive strength after heating and adhesive strength after recovery are shown when a phase change material with a melting point of 85°C or less is used, but the adhesive strength after heating and adhesive strength after recovery of a thermally conductive member using a phase change material with a melting point of more than 85°C and not more than 120°C can be improved by heating to 130°C instead of 90°C.

[0049] (Form of thermally conductive composition) The thermally conductive composition of the present invention may be in the form of a one-component type or a two-component type comprising a first part and a second part, but from the viewpoint of storage stability, the two-component type is preferred. In a two-component thermally conductive composition, the mass ratio of the first part to the second part (second part / first part) is preferably 1 or close to 1, specifically, preferably 0.9 to 1.1, and more preferably 0.95 to 1.05. By setting the mass ratio of the first part to the second part to 1 or close to 1, the thermally conductive composition can be easily prepared. Furthermore, in a two-component thermally conductive composition, the viscosity ratio of the first part to the second part (second part / first part) is also preferably 1 or close to 1, specifically, preferably 0.5 to 2.0, and more preferably 0.8 to 1.2. By setting the viscosity ratio of the first part to the second part to 1 or close to 1, the thermally conductive composition can be easily mixed uniformly.

[0050] When using an addition reaction curable silicone containing the above-mentioned alkenyl group-containing organopolysiloxane (main component) and hydrogen organopolysiloxane (curing agent), in a two-component thermally conductive composition, the first component preferably contains the alkenyl group-containing organopolysiloxane (main component) and the second component preferably contains the hydrogen organopolysiloxane (curing agent). It is preferable that the addition reaction catalyst be contained in the first part but not in the second part. This allows the first and second parts to have excellent storage stability before mixing, and after mixing, the reaction is accelerated, allowing for rapid curing, thereby improving the various physical properties of the thermally conductive material obtained by curing. Although the reason for this is unclear, it is thought that the addition reaction catalyst, such as a platinum catalyst, becomes coordinated to the alkenyl group, which is the addition reaction site of the main part, making it easier for curing to proceed.

[0051] The phase-change material may be contained in at least one of the first and second parts, but is preferably contained in both the first and second parts. When the phase-change material is contained in both the first and second parts, it becomes easier to uniformly disperse the phase-change material in the polymer matrix.

[0052] The thermally conductive filler may be contained in at least one of the first and second parts, but is preferably contained in both the first and second parts. When the thermally conductive filler is contained in both the first and second parts, the first and second parts are easily mixed. Furthermore, when preparing the thermally conductive composition, the mass ratio and viscosity ratio of the second part to the first part can be set to 1 or close to 1, making it easier to use as a two-component composition. Furthermore, the second part preferably contains an alkenyl group-containing organopolysiloxane. By containing the alkenyl group-containing organopolysiloxane as the main component in addition to the hydrogen organopolysiloxane as the curing agent, the mass ratio and viscosity ratio of the second part to the first part when preparing the thermally conductive composition can be easily adjusted to 1 or close to 1. On the other hand, it is preferable that the first part does not contain the hydrogen organopolysiloxane as the curing agent.

[0053] The viscosity of each of the first and second parts, measured using a rheometer at a measurement temperature of 25°C and a shear rate of 0.1 (1 / s), is preferably 400 Pa·s or more and 50,000 Pa·s or less, more preferably 500 Pa·s or more and 30,000 Pa·s or less, and even more preferably 800 Pa·s or more and 100,000 Pa·s or more. If the viscosity of the first and second parts is equal to or greater than the above-mentioned lower limit, the viscosity will be too low, preventing dripping and other problems. If the viscosity of the first and second parts is equal to or less than the above-mentioned upper limit, workability, such as applicability, will be more easily improved.

[0054] The first and second agents are preferably stored separately in containers such as syringes, cartridges, pails, drums, etc. When syringes are used, they are preferably stored as a first syringe filled with the first agent and a second syringe filled with the second agent. In this case, the first and second syringes may be arranged in parallel to form a two-liquid parallel-type syringe. When syringes are used, the first syringe may be the first container and the second syringe may be the second container. As will be described later, the same applies when a cartridge, a pail, or a drum is used.

[0055] Furthermore, when cartridges are used, the first and second agents are preferably stored as a first cartridge filled with the first agent and a second cartridge filled with the second agent. In this case, the first and second cartridges may be arranged in parallel to form a two-liquid parallel type cartridge. Furthermore, when pails or drums are used, the first and second agents are preferably stored as a first pail or drum filled with the first agent and a second pail or drum filled with the second agent.

[0056] When filled into a syringe or cartridge, the first and second components are ejected from the first syringe or cartridge and the second syringe or cartridge, respectively, and mixed using a static mixer or the like to obtain a thermally conductive composition. The thermally conductive composition is then cured to form a thermally conductive member. When the first and second components are ejected, a certain shear force is generated, reducing the viscosity of the first and second components and facilitating their ejection. Furthermore, the coated product formed by the ejection is easily compressible and has excellent workability. For example, after ejecting a mixture of the first and second components between a heat generating element and a heat dissipating element to form a coated product of a certain thickness, the coated product can be easily stretched thinly with a small load.

[0057] (Method for producing thermally conductive composition) The method for producing the thermally conductive composition of the present invention is not particularly limited, but it may be prepared by mixing a liquid polymer, a phase-change material, and, if necessary, other optional components such as additives. When preparing the mixture, a known mixing method may be appropriately adopted, and for example, mixing may be performed using a known kneader, kneading roll, mixer, etc. In the case of a two-component type, the components constituting the first and second parts are mixed to prepare the first and second parts, and then the first and second parts are mixed to obtain the thermally conductive composition. In the case where a compatibilizer is used, the phase-change material is preferably dissolved in the compatibilizer and then mixed with the other components.

[0058] The thermally conductive member of the present invention can be used in a variety of applications, such as batteries, electronic devices, and semiconductor devices, and is preferably used for batteries. When used for batteries, the thermally conductive member is filled between battery cells, between a battery cell and a battery module case, between a battery cell and a battery pack case, between a battery cell and a cooling plate, between a battery module case and a cooling plate, or between a battery pack case and a cooling plate, and the filled gap material may be in close contact with the battery cell, the battery module case, the battery pack case, or the cooling plate. As a result, the gap material between the battery cells has the function of maintaining the battery cells spaced apart. Furthermore, the gap material between the battery cell and the battery module case, between the battery cell and the battery pack case, or between the battery cell and the cooling plate is in close contact with both the battery cell and the battery module case, the battery pack case, or the cooling plate, and has the function of transferring heat generated in the battery cell to the battery module case, the battery pack case, or the cooling plate.

[0059] When the thermally conductive member is used for a battery, it is not particularly limited, but is preferably used in an automobile, more preferably in an automobile equipped with a lithium-ion battery. Because the thermally conductive member of the present invention has excellent reworkability, for example, when a battery assembled to an automobile chassis needs to be repaired or replaced, it is possible to remove only the defective part (e.g., a defective battery module) without placing excessive stress on the battery cell, battery module, or other peripheral parts. Furthermore, since no large-scale equipment is required for rework, it is advantageous in terms of cost, etc. Furthermore, although the thermally conductive member is heated to a certain extent when peeling off, the thermally conductive member can be peeled off without heating to a particularly high temperature. Therefore, the thermally conductive member can be peeled off without causing problems with the battery's electrolyte, etc., due to high temperatures. Furthermore, as described above, even if the thermally conductive member of the present invention is temporarily heated, after cooling, the adhesive strength hardly decreases compared to before heating, so that even if a battery or the like is temporarily heated to a high temperature during use, the adhesive strength can be prevented from decreasing.

[0060] [Structure] The present invention also provides a structure including a heat generating element, a heat sink, and a thermally conductive member that bonds the heat generating element and the heat sink. More specifically, two types of structures are provided, as the following first and second embodiments. In both embodiments, the thermally conductive member included in the structure includes a polymer matrix, a phase change material having a melting point greater than 25°C and less than or equal to 120°C, and a thermally conductive filler.

[0061] (First embodiment) In a first embodiment, a structure is provided in which a heat conductive member included in the structure is cut into a shape of 20 mm x 20 mm and 2 mm thick, the heat conductive member cut into this shape is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours, and the weight loss rate B of the heat conductive member is 0.05% or more and 3.0% or less.

[0062] (Second embodiment) In the second embodiment, a structure is provided in which the adhesive strength between the heating element and the heat sink at 25°C is 0.05 MPa or more and 2.0 MPa or less, and the adhesive strength after heating between the heating element and the heat sink at 90°C is smaller than the adhesive strength and is 0.2 MPa or less. The configuration of the thermally conductive member included in the structure according to the first and second embodiments is as described above, and therefore a detailed description thereof will be omitted. In addition, the adhesive strength between the heating element and the heat sink at 25°C and the adhesive strength after heating at 90°C can be measured in accordance with the method for measuring adhesive strength and adhesive strength after heating shown in the examples.

[0063] In the structure of the present invention, the heat-generating element may be, for example, a battery cell, a CPU used in an electronic device, a power amplifier, a power supply, or other various electronic components, and the heat-dissipating element may be, for example, a battery module case, a battery pack case, a cooling plate, a heat sink, a heat pump, or a metal housing of an electronic device. However, it is preferable that the heat-generating element is a battery cell and the heat-dissipating element is a battery module case, a battery pack case, or a cooling plate. In the structure, the thermally conductive member may function as a gap material. Furthermore, when the heat-dissipating element is a battery module case or a battery pack case, it is preferable that a thermally conductive member be disposed inside the battery module case or the battery pack case.

[0064] [How to rework] The present invention also provides a method for reworking a structure including a heat generating element, a heat sink, and a thermally conductive member disposed between the heat generating element and the heat sink. The configurations of the thermally conductive member, the heat generating element, and the heat sink are as described above, and therefore detailed description thereof will be omitted. In the present invention, the structure may be reworked by heating the structure to a temperature equal to or higher than the melting point of the phase-change material and then peeling off the heating element and heat sink. The heating method is not particularly limited, and may be, for example, a thermostatic bath, a far-infrared heating furnace, or hot air. Furthermore, if the heat sink has a structure for circulating a liquid such as cooling water or a refrigerant, the structure may be heated by circulating the liquid heated to a predetermined temperature. Of these methods, the liquid circulation method is preferred because it is easy to control the temperature of the liquid and efficiently transfers heat to the structure, thereby making it easier to prevent the battery from overheating. In the present invention, excellent reworkability can be achieved by heating the structure above the melting point of the phase-change material. Although the mechanism is unclear, it is presumed to be as follows: When the phase-change material is heated above its melting point, it becomes liquid, reducing the elastic modulus of the thermally conductive member and making it easier to peel. It also bleeds out of the polymer matrix and tends to become localized at the interface between the thermally conductive member and the adherend, resulting in easier interfacial peeling. [Example]

[0065] 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.

[0066] [viscosity] The viscosity of the first and second parts, which were the thermally conductive compositions prepared in each of the Examples and Comparative Examples, was measured as follows. The viscosity of each of the first and second components was measured at a shear rate of 0.1 (1 / s) using a rheometer. Specifically, an Anton Paar MCR-302e rheometer equipped with a 20 mm diameter parallel plate was used. After applying the sample to the sample stage, the distance between the parallel plate and the sample stage was adjusted to 1.9 mm. Any excess sample spilling over the periphery of the parallel plate was removed. The sample was then left to stand at 25°C for 10 minutes, and the viscosity was measured.

[0067] [Weight reduction rate B] The weight loss rate B was calculated using the method described in the specification. A fluororesin-impregnated glass cloth ("FGF-400-2-300w" manufactured by Chukoh Chemical Industry Co., Ltd.) was used as the glass cloth film, and a 160 mm x 120 mm stainless steel plate was used as the compression jig. Furthermore, a sample of the thermally conductive member was cut out from a 20 mm thick block of cured material using a cutter into a shape of 20 mm x 20 mm and 2 mm thick. The same test was performed twice for each example and comparative example, and the average value of the two measurements was calculated.

[0068] Elasticity Modulus The thermally conductive members produced in each of the examples and comparative examples were measured for their moduli of elasticity at 25° C. and 90° C. (G25, G90) by the following measurement method. For the measurements, an Anton Paar MCR-302e rheometer equipped with a 20 mm diameter parallel plate was used. For each example and comparative example, a 2 mm thick sample was placed on the sample stage and compressed so that the gap between the parallel plate and the sample stage was 1.9 mm. The sample temperature was then controlled to 25°C and 90°C using a Peltier plate, and the elastic modulus of each sample was measured under conditions of a strain of 1% and a frequency of 1 Hz.

[0069] Based on the G25 and G90 values ​​obtained by the above measurements, the ratios G25 / G90 and G90 / G25 were calculated. In addition to G25 and G90, the ratio B / (G90 / G25) was also calculated based on the weight loss rate B obtained by the above measurements.

[0070] [Adhesive strength] For the thermally conductive compositions prepared in each of the Examples and Comparative Examples, the initial adhesive strength, adhesive strength after heating to 90°C (adhesive strength after heating), and adhesive strength after heating to 90°C and then cooling to 25°C (adhesive strength after recovery) were measured using the following measurement methods. 2, the thermally conductive composition 21 produced in each example and comparative example was applied to an aluminum jig 22 having a coating surface of 12.7 mm × 12.7 mm and a thickness of 38.0 mm so that the thickness after curing would be 1.5 mm, and then the applied aluminum jig 22 was attached to an aluminum jig 23 of the same shape, and the composition was left in this state at 25°C for 24 hours to cure, thereby obtaining a measurement sample 20. The curing conditions at this time were as shown below (described in the procedure for each example and comparative example). The initial adhesive strength was measured using the above measurement sample in a tensile test conforming to JIS K6849 in an environment of 25°C. The post-heat adhesive strength was measured using the above measurement sample in a tensile test conforming to JIS K6849 in an environment of 90°C. The post-recovery adhesive strength was measured by heating the above measurement sample at 90°C for 30 minutes, leaving it at 25°C for 60 minutes, cooling it, and then in a tensile test conforming to JIS K6849 in an environment of 25°C.

[0071] [Reworkability] The reworkability was evaluated based on the state of the tensile test. Specifically, after the tensile test, the reworkability was evaluated based on the following evaluation criteria. (Evaluation criteria) Cohesive failure: In the above tensile test, cohesive failure of the thermally conductive member occurred (parts of the thermally conductive member remained on both adherends). Interface: In the above tensile test, the thermally conductive member peeled off from the adherend without any cohesive failure of the thermally conductive member.

[0072] In each of the examples and comparative examples, the following components were used. <Liquid polymer> Silicone Agent A: Contains alkenyl-containing organopolysiloxane and a trace amount of addition reaction catalyst (platinum catalyst). Silicone Agent B: Contains alkenyl group-containing organopolysiloxane and hydrogen organopolysiloxane.

[0073] <Dispersant> n-Decyltrimethoxysilane

[0074] <Silicone oil> Dimethyl silicone oil (manufactured by Toray Dow Corning Co., Ltd., product name "SH-200", kinematic viscosity at 25°C 110 cSt)

[0075] <Phase change materials> The melting point of the phase change material was measured by weighing 20 mg of the material into an aluminum cell and then using a Shimadzu DSC-60 under nitrogen flow at a temperature increase rate of 10°C / min from 25°C to 100°C. When the phase change material was contained in a thermally conductive member, the melting point was measured using the same method after weighing 100 mg of the thermally conductive member into an aluminum cell. Stearyl stearate: melting point of 62°C alone, 58°C in thermally conductive material, carbon number 36 Cetyl myristate: Melting point of 55°C alone, 52°C in thermally conductive material, carbon number 30 Behenyl behenate, melting point of 75°C alone, melting point of 72°C in thermally conductive material, carbon number 44 Paraffin 1 melting point alone is 61°C, and in thermally conductive material is 60°C Paraffin 2 melting point alone is 71°C, and in thermally conductive material is 70°C

[0076] <Thermal conductive filler> Aluminum oxide, spherical, average particle size 40μm Aluminum hydroxide, irregular shape, average particle size 1μm Aluminum hydroxide, irregular shape, average particle size 10μm Aluminum hydroxide, irregular shape, average particle size 100μm

[0077] [Examples 1 to 10, Comparative Examples 1 and 2] A thermally conductive composition was obtained by mixing the first and second parts according to the formulations shown in Tables 1 to 3. The resulting thermally conductive composition was left to cure at 25°C for 24 hours to obtain a thermally conductive member. The first part, second part, thermally conductive composition, and thermally conductive member obtained in each of the examples and comparative examples were used to carry out evaluation tests. The results are shown in Tables 1 to 3.

[0078] [Table 1]

[0079] [Table 2]

[0080] [Table 3]

[0081] As is clear from the above results, the thermally conductive members produced in the examples had good adhesive strength at room temperature (25°C), but when heated, the adhesive strength decreased sufficiently, demonstrating excellent reworkability. In contrast, the thermally conductive members prepared in the comparative examples did not exhibit excellent reworkability because their adhesive strength did not decrease sufficiently when heated. In particular, the thermally conductive member prepared in comparative example 2, which contained silicone oil, showed a certain amount of bleeding, but its adhesive strength did not decrease sufficiently because the change in elastic modulus was small. [Explanation of symbols]

[0082] 10. Sample for measuring weight loss rate 11 Compression jig 12 screws 13 Spacer 14 Samples 15 Glass cloth film 20 Tensile test samples 21 Thermally conductive composition 22, 23 Aluminum jig

Claims

1. A thermally conductive member comprising: a polymer matrix; a phase change material having a melting point of more than 25°C and not more than 120°C; and a thermally conductive filler, the phase-change material is at least one selected from an ester compound and a hydrocarbon compound, When the phase-change material is an ester compound, the content of the phase-change material is more than 20 parts by mass and not more than 70 parts by mass with respect to 100 parts by mass of the polymer matrix; When the phase change material is a hydrocarbon compound, the content of the phase change material is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the polymer matrix; the weight loss rate B when the thermally conductive member is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours is 0.05% or more and 3.0% or less; A thermally conductive member, wherein the elastic modulus G25 at 25°C and the elastic modulus G90 at 90°C satisfy the relationship of the following formula (1). [Equation 1]

2. A thermally conductive member comprising: a polymer matrix; a phase change material having a melting point of more than 25°C and not more than 120°C; and a thermally conductive filler, the phase-change material is at least one selected from an ester compound and a hydrocarbon compound, When the phase-change material is an ester compound, the content of the phase-change material is more than 20 parts by mass and not more than 70 parts by mass with respect to 100 parts by mass of the polymer matrix; When the phase change material is a hydrocarbon compound, the content of the phase change material is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the polymer matrix; the weight loss rate B when the thermally conductive member is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours is 0.05% or more and 3.0% or less; A thermally conductive member, wherein the weight loss rate B, the elastic modulus G25 at 25°C, and the elastic modulus G90 at 90°C satisfy the relationship of the following formula (2). [Equation 2]

3. A thermally conductive member comprising: a polymer matrix; a phase change material having a melting point of more than 25°C and not more than 120°C; and a thermally conductive filler, the weight loss rate B when the thermally conductive member is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours is 0.05% or more and 3.0% or less; the phase change material is an ester compound; A thermally conductive member, wherein the content of the phase change material is more than 20 parts by mass and not more than 70 parts by mass per 100 parts by mass of the polymer matrix.

4. The thermally conductive member according to claim 3 , wherein the ester compound is a monoester having 12 to 44 carbon atoms.

5. 4. The thermally conductive member according to claim 1, wherein the polymer matrix is ​​a cured product of an organopolysiloxane.

6. 6. The thermally conductive member according to claim 5, wherein the cured product of the organopolysiloxane is a cured product of an addition reaction curable silicone.

7. The thermally conductive member according to claim 1 or 2, wherein the phase change material is a hydrocarbon compound.

8. A structure including a heat generating element, a heat dissipating element, and a thermally conductive member that fixes the heat generating element and the heat dissipating element together, the thermally conductive member includes a polymer matrix, a phase change material having a melting point greater than 25°C and equal to or less than 120°C, and a thermally conductive filler; the phase-change material is at least one selected from an ester compound and a hydrocarbon compound, When the phase-change material is an ester compound, the content of the phase-change material is more than 20 parts by mass and not more than 70 parts by mass with respect to 100 parts by mass of the polymer matrix; When the phase change material is a hydrocarbon compound, the content of the phase change material is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the polymer matrix; a structure in which the weight loss rate B of the thermally conductive member is 0.05% or more and 3.0% or less when the thermally conductive member is cut into a shape of 20 mm x 20 mm and 2 mm thick, the thermally conductive member cut into said shape is sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours.

9. the heating element is a battery cell, The structure according to claim 8 , wherein the heat sink is a battery module case, a battery pack case, or a cooling plate.

10. A structure including a heat generating element, a heat dissipating element, and a thermally conductive member that fixes the heat generating element and the heat dissipating element together, the thermally conductive member includes a polymer matrix, a phase change material having a melting point greater than 25°C and equal to or less than 120°C, and a thermally conductive filler; the phase-change material is at least one selected from an ester compound and a hydrocarbon compound, When the phase-change material is an ester compound, the content of the phase-change material is more than 20 parts by mass and not more than 70 parts by mass with respect to 100 parts by mass of the polymer matrix; When the phase change material is a hydrocarbon compound, the content of the phase change material is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the polymer matrix; the adhesive strength between the heat generating element and the heat dissipating element at 25°C is 0.05 MPa or more and 2.0 MPa or less, A structure in which the adhesive strength between the heat generating element and the heat dissipating element after heating at 90°C is smaller than the adhesive strength and is 0.2 MPa or less.

11. A thermally conductive composition comprising: a liquid polymer that is a precursor of a polymer matrix; a phase change material having a melting point higher than 25°C and lower than or equal to 120°C; and a thermally conductive filler, the phase-change material is at least one selected from an ester compound and a hydrocarbon compound, When the phase change material is an ester compound, the content of the phase change material is more than 20 parts by mass and not more than 70 parts by mass with respect to 100 parts by mass of the liquid polymer; When the phase change material is a hydrocarbon compound, the content of the phase change material is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the liquid polymer, a cured product of the thermally conductive composition has a weight loss rate B of 0.05% or more and 3.0% or less when sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours; A thermally conductive composition, wherein a cured product of the thermally conductive composition has an elastic modulus G25 at 25°C and an elastic modulus G90 at 90°C that satisfy the relationship of the following formula (1): [Equation 1]

12. A thermally conductive composition comprising: a liquid polymer that is a precursor of a polymer matrix; a phase change material having a melting point higher than 25°C and lower than or equal to 120°C; and a thermally conductive filler, the phase-change material is at least one selected from an ester compound and a hydrocarbon compound, When the phase change material is an ester compound, the content of the phase change material is more than 20 parts by mass and not more than 70 parts by mass with respect to 100 parts by mass of the liquid polymer; When the phase change material is a hydrocarbon compound, the content of the phase change material is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the liquid polymer, a cured product of the thermally conductive composition has a weight loss rate B of 0.05% or more and 3.0% or less when sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours; A thermally conductive composition, wherein the weight loss rate B, the elastic modulus G25 at 25°C, and the elastic modulus G90 at 90°C of the cured product of the thermally conductive composition satisfy the relationship of the following formula (2): [Equation 2]

13. A thermally conductive composition comprising: a liquid polymer that is a precursor of a polymer matrix; a phase change material having a melting point higher than 25°C and lower than or equal to 120°C; and a thermally conductive filler, a cured product of the thermally conductive composition has a weight loss rate B of 0.05% or more and 3.0% or less when sandwiched between glass cloth films, compressed by 10%, and left at 90°C for 40 hours; the phase change material is an ester compound; A thermally conductive composition, wherein the content of the phase change material is more than 20 parts by mass and not more than 70 parts by mass per 100 parts by mass of the liquid polymer.

14. The thermally conductive composition according to claim 13 , wherein the ester compound is a monoester having 12 to 44 carbon atoms.

15. a first agent containing a base agent made of the liquid polymer, a phase change material having a melting point higher than 25°C and lower than 120°C, and a thermally conductive filler, the first agent being filled in a first container; a second agent containing a curing agent made of the liquid polymer, a phase change material having a melting point higher than 25°C and lower than 120°C, and a thermally conductive filler, the second agent being filled in a second container; The thermally conductive composition according to any one of claims 11 to 13, comprising a combination of:

16. A method for reworking a structure including a heat generating element, a heat dissipating element, and a thermally conductive member disposed between the heat generating element and the heat dissipating element, comprising: the thermally conductive member includes a polymer matrix, a phase change material having a melting point greater than 25°C and less than or equal to 120°C, and a thermally conductive filler; the phase-change material is at least one selected from an ester compound and a hydrocarbon compound, When the phase-change material is an ester compound, the content of the phase-change material is more than 20 parts by mass and not more than 70 parts by mass with respect to 100 parts by mass of the polymer matrix; When the phase change material is a hydrocarbon compound, the content of the phase change material is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the polymer matrix; A method for reworking a structure, comprising heating the structure to a temperature equal to or higher than the melting point of the phase change material, and then peeling off the heat generating element and the heat sink.

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