Thermally conductive rubber composition

Abstract

This thermally conductive rubber composition contains a base rubber, a thermally conductive filler, and an aliphatic amine compound, and has a durometer hardness (type A) of 80 or less, a thermal conductivity of 3.0 W / mK or more, and an elongation at break of 300% or more.

Description

Thermally conductive rubber composition

[0001] The present disclosure relates to a thermally conductive rubber composition.

[0002] In recent years, the thermal load on devices such as electronic equipment has increased as devices have become smaller and more powerful. To reduce this load, it is necessary to attach a heat dissipation component with high thermal conductivity to the device to efficiently dissipate heat from the device.

[0003] If a gap due to air forms between the device and the heat dissipation member, the efficiency of heat transfer between them deteriorates. Therefore, highly flexible heat dissipation rubber that can adhere closely to the device is used as the heat dissipation member. Heat dissipation rubber is made of a thermally conductive rubber composition in which a high amount of filler with high thermal conductivity is filled into the rubber. Generally, the more filler is filled into the rubber, the more difficult it becomes to disperse the filler within the rubber, and the heat dissipation rubber is more likely to lose flexibility.

[0004] Therefore, for example, in Patent Documents 1 to 3, the filler is surface-treated with a silane coupling agent in order to improve the dispersibility of the filler in the rubber.

[0005] JP 2012-211250 A JP 2013-83699 A JP 2021-176931 A

[0006] However, the thermally conductive rubber compositions using a coupling agent as in Patent Documents 1 to 3 have room for improvement in terms of achieving both high thermal conductivity and low hardness.

[0007] In consideration of the above circumstances, an object of the present disclosure is to provide a thermally conductive rubber composition that is excellent in heat dissipation properties.

[0008] A thermally conductive rubber composition according to one embodiment of the present disclosure includes a base rubber, a thermally conductive filler, and an aliphatic amine compound, and has a durometer hardness (Type A) of 80 or less, a thermal conductivity of 3.0 W / mK or more, and an elongation at break of 300% or more.

[0009] The present disclosure can provide a thermally conductive rubber composition that is excellent in heat dissipation properties.

[0010] 1 is a schematic diagram of a heat-conducting rubber composition according to an embodiment. 2 is a diagram for explaining the action of an aliphatic amine compound in the heat-conducting rubber composition according to an embodiment. 3 is a table showing the properties of the heat-conducting rubber compositions of Examples 1-10 and Comparative Examples 1-3.

[0011] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. The dimensions and scale of each part in the drawings may differ from those of the actual parts, and some parts are shown schematically to facilitate understanding. The scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0012] 1. Embodiments Fig. 1 is a schematic diagram of a thermally conductive rubber composition 10 according to an embodiment. The thermally conductive rubber composition 10 is, for example, formed into a plate shape and used as a heat dissipation sheet that is attached to an electronic substrate of a device such as an electronic equipment. Note that the use of the thermally conductive rubber composition 10 is not limited to heat dissipation from the electronic substrate and is arbitrary.

[0013] The thermally conductive rubber composition 10 has a durometer hardness (Type A) of 80 or less, a thermal conductivity of 3.0 W / mK or more, and an elongation at break of 300% or more. This increases the thermal conductivity of the thermally conductive rubber composition 10 while also increasing the adhesion of the thermally conductive rubber composition 10 to the heat dissipation target, thereby achieving a thermally conductive rubber composition 10 with excellent heat dissipation properties. However, the durometer hardness (Type A) of the thermally conductive rubber composition 10 may be 80 or less, but is preferably 40 or more. This allows the thermally conductive rubber composition 10 to have appropriate flexibility.

[0014] The durometer hardness (Type A) is measured using a Type A hardness tester in accordance with, for example, JIS K 6253-3:2012. The thermal conductivity is measured in accordance with, for example, ASTM D7984. The elongation at break is measured in accordance with, for example, JIS K 6251.

[0015] As shown in FIG. 1 , a thermally conductive rubber composition 10 includes a rubber portion 11 and a thermally conductive filler 12 .

[0016] The rubber portion 11 includes a base rubber and an aliphatic amine compound. Therefore, the thermally conductive rubber composition 10 includes the base rubber, a thermally conductive filler 12, and an aliphatic amine compound. In addition to the base rubber and the aliphatic amine compound, the rubber portion 11 may also include additives as appropriate. Examples of such additives include crosslinking agents, photocuring agents, conductivity-imparting agents, flame retardant-imparting agents, softeners, antioxidants, ultraviolet absorbers, and colorants.

[0017] 1-1. Base Rubber The base rubber is not particularly limited, but preferably contains at least one rubber selected from the group consisting of ethylene propylene diene rubber, silicone rubber, acrylic rubber, nitrile rubber, and fluororubber, and more preferably contains ethylene propylene diene rubber or silicone rubber. This allows the thermally conductive rubber composition 10 to preferably achieve both high thermal conductivity and low hardness. The base rubber is obtained by crosslinking raw material polymers with a crosslinking agent.

[0018] 1-2. Aliphatic Amine Compounds Aliphatic amine compounds are compounds in which an amino group is bonded to a hydrocarbon having no aromatic ring. As will be described in detail later with reference to FIG. 2, such aliphatic amine compounds have the property of being easily mixed into the base rubber and easily physically adsorbed to the thermally conductive filler 12. This allows for improved dispersion of the thermally conductive filler in the base rubber. As a result, the thermally conductive rubber composition 10 can have a low hardness even when its thermal conductivity is increased. Furthermore, aliphatic amine compounds are less likely to react with each other, such as with silane coupling agents. Therefore, the thermally conductive rubber composition can have a low hardness compared to embodiments using silane coupling agents. Furthermore, the thermally conductive rubber composition can have a higher elongation at break compared to embodiments using silane coupling agents. From the above, the flexibility of the thermally conductive rubber composition 10 can be increased even when its thermal conductivity is increased. This allows for the provision of a thermally conductive rubber composition 10 with excellent heat dissipation properties.

[0019] The amine equivalent of the aliphatic amine compound contained in the thermally conductive rubber composition 10 is preferably 135 or less, and more preferably 78 to 135. When the amine equivalent of the aliphatic amine compound is within this range, the dispersibility of the thermally conductive filler 12 in the base rubber can be suitably improved. As a result, the hardness of the thermally conductive rubber composition 10 can be suitably reduced. The amine equivalent is the amount obtained by dividing the molecular weight of the amine by the number of active hydrogens in the amine, i.e., (molecular weight of amine) / (number of active hydrogens in amine).

[0020] More specifically, the aliphatic amine compound is CH ３ (CH ２ ) ｎ NH ２ (n is a natural number of 10 or more and 20 or less), ２ NHCH ２ CH ２ NH ２ ] ２ Triethylenetetramine represented by the formula: and NH ２ (CH ２ ) ｎ NH ２ (n is a natural number of 6 or more and 8 or less), and among these, one type may be used alone or two or more types may be used in combination. By using these aliphatic amine compounds, the dispersibility of the thermally conductive filler 12 in the base rubber can be suitably improved.

[0021] CH ３ (CH ２ ) ｎ NH ２ (n is a natural number of 10 or more and 20 or less), examples of the aliphatic amine compound include 1-aminodecane, 1-aminotridecane, hexadecylamine (1-aminohexadecane), stearylamine (1-aminooctadecane), etc., and among these, one type can be used alone or two or more types can be used in combination.

[0022] NH ２ (CH ２ ) ｎ NH ２(n is a natural number of 6 or more and 8 or less), examples of the aliphatic amine compound include 1,6-diaminohexane and 1,8-diaminooctane, and among these, one type can be used alone or two or more types can be used in combination.

[0023] The content of the aliphatic amine compound in the thermally conductive rubber composition 10 is preferably 5 parts by mass or more and 30 parts by mass or less, more preferably 10 parts by mass or more and 30 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the base rubber. By keeping the content within this range, it is possible to suitably improve the dispersibility of the thermally conductive filler 12 in the base rubber while making use of the properties of the base rubber.

[0024] In contrast, if the content of the aliphatic amine compound in the thermally conductive rubber composition 10 is too low, the dispersibility of the thermally conductive filler 12 in the base rubber tends to decrease depending on the type of the aliphatic amine compound or the thermally conductive filler, etc. On the other hand, if the content of the aliphatic amine compound in the thermally conductive rubber composition 10 is too high, the breaking strength of the thermally conductive rubber composition 10 tends to decrease depending on the type of the base rubber, etc.

[0025] The thermally conductive filler 12 is a powder having a higher thermal conductivity than the base rubber, and has the function of transmitting heat H more efficiently than the base rubber within the thermally conductive rubber composition 10. This enables the thermal conductivity of the thermally conductive rubber composition 10 to be increased.

[0026] It is preferable to use an insulating inorganic filler as the thermally conductive filler 12. Specifically, it is preferable that the thermally conductive filler 12 contains at least one filler selected from the group consisting of metal oxide fillers, metal nitride fillers, and metal oxynitride fillers. This makes it possible to easily ensure the insulation properties of the entire thermally conductive rubber composition 10 while suitably increasing the thermal conductivity of the thermally conductive rubber composition 10. Note that the thermally conductive filler 12 may be a filler obtained by subjecting the surface of a metal filler to an insulating treatment such as oxidation treatment.

[0027] In particular, it is preferable that the thermally conductive filler 12 contains a zinc oxide filler. Zinc oxide filler easily has hydroxyl groups present on its surface without any additional treatment. Therefore, when the thermally conductive filler 12 contains a zinc oxide filler, the action of the aliphatic amine compound can be favorably exerted, as described below. As a result, the thermal conductivity of the thermally conductive rubber composition 10 can be favorably increased. Note that the surface of the thermally conductive filler 12 may be subjected to a separate treatment, such as plasma treatment, to cause hydroxyl groups to be present on the surface of the thermally conductive filler 12.

[0028] The average particle size of the thermally conductive filler 12 is preferably 30 μm or more and 70 μm or less, and more preferably 40 μm or more and 60 μm or less. When the average particle size is within this range, there is an advantage that the total contact area between the thermally conductive filler 12 can be reduced, and the thermally conductive filler 12 can be easily arranged at a high density in the thermally conductive rubber composition 10. Due to this advantage, it is possible to suitably achieve both high thermal conductivity and low hardness of the thermally conductive rubber composition 10.

[0029] In particular, from the viewpoint of arranging the thermally conductive filler 12 at high density in the thermally conductive rubber composition 10 while reducing the total contact area between the thermally conductive filler 12, it is preferable that the thermally conductive filler 12 contain multiple types of fillers with different average particle sizes.

[0030] Here, the thermally conductive filler 12 includes a first filler and a second filler having an average particle size smaller than that of the first filler. The content of the first filler is greater than the content of the second filler. This allows the average particle size of the thermally conductive filler 12 to be increased while increasing the filling rate. That is, the first filler reduces the total contact area between the thermally conductive fillers 12, while the second filler increases the density of the thermally conductive filler 12 in the thermally conductive rubber composition 10. As a result, the thermally conductive rubber composition 10 can be advantageously made to have both high thermal conductivity and low hardness.

[0031] The average particle size of the first filler is preferably in the range of 60 μm to 80 μm, and the average particle size of the second filler is preferably in the range of 5 μm to 20 μm. By setting the average particle sizes of the first filler and the second filler within these ranges, the total contact area between the thermally conductive fillers 12 can be reduced, and the thermally conductive fillers 12 can be arranged at a high density in the thermally conductive rubber composition 10.

[0032] In addition to the first and second fillers, the thermally conductive filler 12 may also include a third filler having an average particle size smaller than that of the second filler. In this case, from the viewpoint of increasing the average particle size of the thermally conductive filler 12 while increasing the filling rate, the content of the third filler is preferably smaller than the content of the second filler. When the average particle sizes of the first and second fillers are within the aforementioned ranges, the average particle size of the third filler is preferably within the range of 0.5 μm or more and 2 μm or less. This allows the thermally conductive filler 12 to be densely arranged in the thermally conductive rubber composition 10 while reducing the total contact area between the thermally conductive fillers 12.

[0033] The particle shape of the thermally conductive filler 12 is not particularly limited, but is preferably spherical. That is, the thermally conductive filler 12 preferably contains spherical fillers. This makes it possible to arrange the thermally conductive fillers 12 at high density in the thermally conductive rubber composition 10 while reducing the total contact area between the thermally conductive fillers 12. From this perspective, when the thermally conductive filler 12 contains the above-mentioned first filler and second filler, it is preferable that the first filler be a spherical filler, and it is more preferable that each of the first filler and the second filler be a spherical filler.

[0034] The content of the thermally conductive filler 12 in the thermally conductive rubber composition 10 is preferably 1,500 parts by mass or more and 1,800 parts by mass or less, and more preferably 1,500 parts by mass or more and 1,700 parts by mass or less, relative to 100 parts by mass of the base rubber. By keeping the content within this range, it is possible to suitably achieve both high thermal conductivity and low hardness of the thermally conductive rubber composition 10.

[0035] On the other hand, if the content of the thermally conductive filler 12 in the thermally conductive rubber composition 10 is too small, it may be difficult to achieve a thermal conductivity of 3.0 W / mK or more of the thermally conductive rubber composition 10, depending on the type of the thermally conductive filler 12. On the other hand, if the content of the thermally conductive filler 12 in the thermally conductive rubber composition 10 is too large, it may be difficult to achieve a durometer hardness (Type A) of 80 or less of the thermally conductive rubber composition 10, depending on the shape of the thermally conductive filler 12 or the type of base rubber.

[0036] 1-4. Function of Aliphatic Amine Compound Fig. 2 is a diagram for explaining the function of the aliphatic amine compound in the heat conductive rubber composition 10 according to the embodiment. ３ (CH ２ ) ｎ NH ２ An embodiment using a compound represented by the following formula:

[0037] As shown in FIG. 2, hydroxyl groups (—OH) exist on the surface of the thermally conductive filler 12. Therefore, amino groups (—NH ２ ) is physically adsorbed by hydrogen bonding to the hydroxyl groups on the surface of the thermally conductive filler 12. Furthermore, the aliphatic amine compound has a linear alkyl chain that has excellent lipophilicity, and therefore is easily mixed into the base rubber.

[0038] When such an aliphatic amine compound is kneaded with the base rubber and the thermally conductive filler 12, it physically adsorbs onto the surface of the thermally conductive filler 12 during the kneading. This improves the dispersibility of the thermally conductive filler 12 in the thermally conductive rubber composition 10, thereby reducing the hardness of the thermally conductive rubber composition 10 and increasing the elongation at break of the thermally conductive rubber composition 10. As a result, the flexibility of the thermally conductive rubber composition 10 can be increased.

[0039] Furthermore, even when an aliphatic amine compound is used, the thermally conductive rubber composition 10 can be produced by the same method as that used for kneading ordinary rubber. Therefore, unlike the embodiment in which a silane coupling agent is used, there is no need to change the temperature or time during kneading, so the number of steps in producing the thermally conductive rubber composition 10 does not increase, and the energy cost for producing the thermally conductive rubber composition 10 is also low.

[0040] 2. Examples The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0041] 2-1. Production of Thermally Conductive Rubber Composition 2-1-1. Example 1 First, the following materials were kneaded in a kneader at a temperature of 70° C. for 10 minutes to obtain a compound.

[0042] EPDM polymer (EPT4045 manufactured by Mitsui Chemicals, Inc.): 100 parts by mass (phr) Crosslinking agent (Percumyl D manufactured by NOF Corporation): 3 parts by mass (phr) Thermally conductive filler (LPZINC-50S manufactured by Sakai Chemical Industry Co., Ltd.): 1085 parts by mass (phr) Thermally conductive filler (LPZINC-11 manufactured by Sakai Chemical Industry Co., Ltd.): 310 parts by mass (phr) Thermally conductive filler (zinc oxide type 1 manufactured by Sakai Chemical Industry Co., Ltd.): 155 parts by mass (phr) Aliphatic amine compound (1-aminodecane manufactured by Tokyo Chemical Industry Co., Ltd.): 10 parts by mass (phr)

[0043] The thermally conductive filler (LPZINC-50S, manufactured by Sakai Chemical Industry Co., Ltd.) is a spherical filler made of zinc oxide with a particle size of 70 μm. The thermally conductive filler (LPZINC-11, manufactured by Sakai Chemical Industry Co., Ltd.) is a spherical filler made of zinc oxide with a particle size of 11 μm. The thermally conductive filler (Zinc Oxide Type 1, manufactured by Sakai Chemical Industry Co., Ltd.) is a spherical filler made of zinc oxide with a particle size of 0.75 μm.

[0044] The molecular weight of 1-aminodecane is 157.3. The number of active hydrogens in 1-aminodecane is 2. The amine equivalent weight of 1-aminodecane is 78.8.

[0045] The obtained compound was rolled into a sheet shape and then molded by pressing at a temperature of 200° C. for 8 minutes, thereby obtaining the thermally conductive rubber composition of Example 1.

[0046] 2-1-2. Example 2 A thermally conductive rubber composition of Example 2 was obtained in the same manner as in Example 1, except that an aliphatic amine compound (1-aminotridecane, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0047] The molecular weight of 1-aminotridecane is 199.38. The number of active hydrogens of 1-aminotridecane is 2. The amine equivalent of 1-aminotridecane is 99.7.

[0048] 2-1-3. Example 3 A thermally conductive rubber composition of Example 3 was obtained in the same manner as in Example 1, except that an aliphatic amine compound (hexadecylamine, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0049] The molecular weight of hexadecylamine is 241.5. The number of active hydrogens in hexadecylamine is 2. The amine equivalent weight of hexadecylamine is 120.7.

[0050] 2-1-4. Example 4 A thermally conductive rubber composition of Example 4 was obtained in the same manner as in Example 1, except that an aliphatic amine compound (stearylamine, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0051] The molecular weight of stearylamine is 269.5. The number of active hydrogens in stearylamine is 2. The amine equivalent weight of stearylamine is 134.8.

[0052] 2-1-5. Example 5 A thermally conductive rubber composition of Example 5 was obtained in the same manner as in Example 1, except that an aliphatic amine compound (triethylenetetramine, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0053] The molecular weight of triethylenetetramine is 146.24. The number of active hydrogens in triethylenetetramine is 6. The amine equivalent weight of triethylenetetramine is 24.4.

[0054] 2-1-6. Example 6 A thermally conductive rubber composition of Example 6 was obtained in the same manner as in Example 1, except that an aliphatic amine compound (1,6-diaminohexane, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0055] The molecular weight of 1,6-diaminohexane is 116.21. The number of active hydrogens in 1,6-diaminohexane is 4. The amine equivalent weight of 1,6-diaminohexane is 29.1.

[0056] 2-1-7. Example 7 A thermally conductive rubber composition of Example 7 was obtained in the same manner as in Example 1, except that an aliphatic amine compound (1,8-diaminooctane, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0057] The molecular weight of 1,8-diaminooctane is 144.26. The number of active hydrogens in 1,8-diaminooctane is 4. The amine equivalent of 1,8-diaminooctane is 36.1.

[0058] 2-1-8. Example 8 A thermally conductive rubber composition of Example 8 was obtained in the same manner as in Example 1, except that the content of the aliphatic amine compound was set to 5 parts by mass (phr).

[0059] 2-1-9. Example 9 A thermally conductive rubber composition of Example 9 was obtained in the same manner as in Example 1, except that the content of the aliphatic amine compound was 20 parts by mass (phr).

[0060] 2-1-10. Example 10 A thermally conductive rubber composition of Example 10 was obtained in the same manner as in Example 1, except that the content of the aliphatic amine compound was 30 parts by mass (phr).

[0061] 2-1-11. Comparative Example 1 A thermally conductive rubber composition of Comparative Example 1 was obtained in the same manner as in Example 1, except that the incorporation of the aliphatic amine compound was omitted.

[0062] 2-1-12. Comparative Example 2 A thermally conductive rubber composition of Comparative Example 2 was obtained in the same manner as in Example 1, except that a plasticizer (PW-380 manufactured by Idemitsu Kosan Co., Ltd.) was used instead of the aliphatic amine compound.

[0063] 2-1-13. Comparative Example 3 A thermally conductive rubber composition of Comparative Example 3 was obtained in the same manner as in Example 1, except that octyltriethoxysilane (KBE-3083 manufactured by Shin-Etsu Silicones Co., Ltd.) was used instead of the aliphatic amine compound.

[0064] 2-2. Characteristics of the Thermally Conductive Rubber Composition The thermal conductivity, hardness (durometer hardness), breaking strength, and breaking elongation of the thermally conductive rubber compositions of Examples 1-10 and Comparative Examples 1-3 were measured. The results are shown in Figure 3.

[0065] 3 is a table showing the properties of the thermally conductive rubber compositions of Examples 1-10 and Comparative Examples 1-3. Durometer hardness (Type A) was measured using a Type A hardness tester in accordance with JIS K 6253-3:2012. Thermal conductivity was measured in accordance with ASTM D7984. Breaking strength and breaking elongation were each measured in accordance with, for example, JIS K 6251.

[0066] 3, the thermally conductive rubber composition of Example 1-10 has a thermal conductivity (3.0 W / mK or more) and breaking strength equivalent to those of the thermally conductive rubber composition of Comparative Example 1-3, but has a lower hardness and a significantly higher breaking elongation (300% or more) than the thermally conductive rubber composition of Comparative Example 1-3. In other words, the thermally conductive rubber composition of Example 1-10 has superior flexibility compared to the thermally conductive rubber composition of Comparative Example 1-3.

[0067] Here, the durometer hardness of the thermally conductive rubber composition of Example 1-10 is 80 or less. In particular, the durometer hardness of the thermally conductive rubber compositions of Examples 1-4, 1-9, and 10 is significantly below 80. In contrast, the durometer hardness of the thermally conductive rubber composition of Comparative Example 1-3 was significantly above 80.

[0068] 3. Supplementary Notes The following aspects, for example, can be understood from the above embodiment and modified examples.

[0069] (Appendix 1) A first embodiment, which is a preferred example of the thermally conductive rubber composition of the present disclosure, includes a base rubber, a thermally conductive filler, and an aliphatic amine compound, and has a durometer hardness (Type A) of 80 or less, a thermal conductivity of 3.0 W / mK or more, and an elongation at break of 300% or more. In the above embodiment, the use of the aliphatic amine compound can improve the dispersibility of the thermally conductive filler in the base rubber. As a result, the thermally conductive rubber composition can have a low hardness even when its thermal conductivity is increased. Moreover, since the aliphatic amine compound is less likely to react with itself, such as with a silane coupling agent, the thermally conductive rubber composition can have a low hardness compared to an embodiment using a silane coupling agent. Furthermore, the thermally conductive rubber composition can have a higher elongation at break compared to an embodiment using a silane coupling agent. As a result, the flexibility of the thermally conductive rubber composition can be increased even when its thermal conductivity is increased. This makes it possible to provide a thermally conductive rubber composition with excellent heat dissipation properties.

[0070] (Note 2) In a second aspect, which is a preferred example of the first aspect, the content of the aliphatic amine compound is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the base rubber. In this aspect, the dispersibility of the thermally conductive filler in the base rubber can be suitably improved while making the most of the properties of the base rubber.

[0071] (Appendix 3) In a third aspect which is a preferred example of the first or second aspect, the aliphatic amine compound has an amine equivalent of not more than 135. In this aspect, the dispersibility of the thermally conductive filler in the base rubber can be suitably improved.

[0072] (Appendix 4) In a fourth embodiment, which is a suitable example of any one of the first to third embodiments, the aliphatic amine compound is CH ３ (CH ２ ) ｎ NH ２ (n is a natural number of 10 or more and 20 or less). In the above embodiment, the dispersibility of the thermally conductive filler in the base rubber can be suitably improved.

[0073] (Appendix 5) In a fifth aspect, which is a preferred example of any one of the first to fourth aspects, the aliphatic amine compound includes triethylenetetramine. In the above aspect, the dispersibility of the thermally conductive filler in the base rubber can be suitably improved.

[0074] (Appendix 6) In a sixth embodiment, which is a preferred example of any one of the first to fifth embodiments, the aliphatic amine compound is NH ２ (CH ２ ) ｎ NH ２ (n is a natural number of 6 or more and 8 or less). In the above embodiment, the dispersibility of the thermally conductive filler in the base rubber can be suitably improved.

[0075] (Appendix 7) In a seventh aspect, which is a preferred example of any of the first to sixth aspects, the content of the thermally conductive filler is 1,500 parts by mass or more and 1,800 parts by mass or less per 100 parts by mass of the base rubber. In this aspect, it is possible to suitably achieve both high thermal conductivity and low hardness of the thermally conductive rubber composition.

[0076] (Appendix 8) In an eighth aspect, which is a preferred example of any one of the first to seventh aspects, the thermally conductive filler includes at least one filler selected from the group consisting of metal oxide fillers, metal nitride fillers, and metal oxynitride fillers. In the above aspect, the thermal conductivity of the thermally conductive rubber composition can be suitably increased while easily ensuring the insulation properties of the entire thermally conductive rubber composition.

[0077] (Appendix 9) In a ninth aspect which is a suitable example of any one of the first to eighth aspects, the thermally conductive filler includes a zinc oxide filler. In the above aspect, the thermal conductivity of the thermally conductive rubber composition can be suitably increased.

[0078] (Appendix 10) In a tenth aspect, which is a preferred example of any one of the first to ninth aspects, the thermally conductive filler has an average particle size of 30 μm or more and 70 μm or less. In this aspect, it is possible to suitably achieve both high thermal conductivity and low hardness of the thermally conductive rubber composition.

[0079] (Appendix 11) In an eleventh aspect, which is a preferred example of any one of the first to tenth aspects, the thermally conductive filler includes a first filler and a second filler having an average particle size smaller than that of the first filler, and the content of the first filler is greater than the content of the second filler. In this aspect, the average particle size of the thermally conductive filler can be increased while increasing the filling rate. As a result, it is possible to preferably achieve both high thermal conductivity and low hardness of the thermally conductive rubber composition.

[0080] (Appendix 12) In a twelfth aspect which is a suitable example of any one of the first to eleventh aspects, the durometer hardness (type A) is 40 or more. In the above aspect, the flexibility of the thermally conductive rubber composition can be made appropriate.

[0081] (Appendix 13) In a thirteenth aspect, which is a preferred example of any one of the first to twelfth aspects, the base rubber includes at least one rubber selected from the group consisting of ethylene propylene diene rubber, silicone rubber, acrylic rubber, nitrile rubber, and fluororubber. In the above aspect, it is possible to suitably achieve both high thermal conductivity and low hardness of the thermally conductive rubber composition.

[0082] 10...thermally conductive rubber composition, 11...rubber part, 12...thermally conductive filler.

Claims

1. A thermally conductive rubber composition comprising a base rubber, a thermally conductive filler, and an aliphatic amine compound, having a durometer hardness (Type A) of 80 or less, a thermal conductivity of 3.0 W / mK or more, and an elongation at break of 300% or more.

2. The thermally conductive rubber composition according to claim 1, wherein the content of the aliphatic amine compound is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the base rubber.

3. The thermally conductive rubber composition according to claim 2, wherein the aliphatic amine compound has an amine equivalent of 135 or less.

4. The aliphatic amine compound is CH ３ (CH ２ ) ｎ NH ２ The thermally conductive rubber composition according to claim 3 , comprising a compound represented by the formula: (n is a natural number of 10 or more and 20 or less).

5. The thermally conductive rubber composition according to claim 3, wherein the aliphatic amine compound includes triethylenetetramine.

6. The aliphatic amine compound is NH ２ (CH ２ ) ｎ NH ２ The thermally conductive rubber composition according to claim 3 , comprising a compound represented by the formula: (n is a natural number of 6 or more and 8 or less).

7. The thermally conductive rubber composition according to claim 1, wherein the content of the thermally conductive filler is 1,500 parts by mass or more and 1,800 parts by mass or less per 100 parts by mass of the base rubber.

8. The thermally conductive rubber composition according to any one of claims 1 to 7, wherein the thermally conductive filler comprises at least one filler selected from the group consisting of metal oxide fillers, metal nitride fillers, and metal oxynitride fillers.

9. The thermally conductive rubber composition according to claim 8, wherein the thermally conductive filler includes a zinc oxide filler.

10. The thermally conductive rubber composition according to any one of claims 1 to 7, wherein the average particle size of the thermally conductive filler is 30 μm or more and 70 μm or less.

11. The thermally conductive rubber composition according to claim 10, wherein the thermally conductive filler comprises a first filler and a second filler having an average particle size smaller than that of the first filler, and the content of the first filler is greater than the content of the second filler.

12. The thermally conductive rubber composition according to any one of claims 1 to 7, having a durometer hardness (type A) of 40 or more.

13. The thermally conductive rubber composition according to any one of claims 1 to 7, wherein the base rubber contains at least one rubber selected from the group consisting of ethylene propylene diene rubber, silicone rubber, acrylic rubber, nitrile rubber, and fluororubber.

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