JP2022135221A - thermal switch - Google Patents

Abstract

To provide a thermal switch superior in switching between the heat dissipation property and the heat retaining property by improving a material of an elastic thermal expansion member of which the volume reversibly changes accompanying the change in temperature.SOLUTION: A thermal switch comprises: a first base material; a second base material; and an elastic thermal expansion member interposed between the first and second base materials, connecting the first and second base materials as the expansion under a given temperature condition, and forming a heat transfer path from the first base material to the second base material. The elastic thermal expansion member is a crosslinked material of a composition containing (A) a crosslinkable elastomer, (B) a heat-conducting filler, and (C) a crosslinking agent. The elastic thermal expansion member has an average linear thermal expansion coefficient of 1×10-4/K to 10×10-4/K in a range of 0-100°C.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermal switch whose thermal conductivity changes with temperature.

Hybrid vehicles and electric vehicles are equipped with a battery pack containing a plurality of battery cells. In battery packs, the lower the temperature, the higher the internal resistance, so heat insulation is required to promote heat rise at low temperatures. Also, if the temperature becomes too high, the battery may be damaged, so heat dissipation is required at high temperatures.

As such a technique, a thermal switch is disclosed in which the thermal conductivity differs between the connected state where the first protective layer, the second protective layer and the thermal expansion member are in contact with each other and the non-connected state where they do not contact each other. (Patent Document 1)

International Publication No. 2014/156991

However, in Patent Document 1, ceramics are used for the thermal expansion member, and the thermal conductivity is high, so although the heat dissipation in the connected state is good, the average linear thermal expansion coefficient is low, so the accuracy of the gap is required. Also, since there is little expansion change due to temperature change, the responsiveness as a thermal switch to temperature change is not good. Also, if the gap is 0.1 to 100 μm, the expansion and contraction of the cell itself may not be absorbed, or sufficient heat insulation may not be provided in the non-connected state. Furthermore, since the thermal expansion member and the protective layer are hard, there is a problem that the connection state is unstable and the thermal expansion member may destroy the cells during thermal expansion.

The present invention has been made in view of such circumstances, and by improving the material of the thermal expansion member whose volume reversibly changes with temperature changes, it is possible to switch between heat dissipation and heat retention. The object is to provide a thermal switch. Another object of the present invention is to provide a battery pack having the thermal switch.

In order to solve the above problems, the thermal switch of the present invention can solve the above problems by using an elastomer that is flexible and has a large average linear thermal expansion coefficient and a thermally conductive filler as the material of the thermal expansion member.

It is interposed between the first base material, the second base material, and the first base material and the second base material, and expands under predetermined temperature conditions to form the first base material and the second base material. an elastic thermal expansion member connected to the base material and forming a heat transfer path between the first base material and the second base material,
the elastic thermal expansion member comprises a thermoset elastomer and a thermally conductive filler dispersed in the thermoset elastomer;
The thermal switch, wherein the elastic thermal expansion member has an average linear thermal expansion coefficient of 1×10 ^-4 /K to 10×10 ^-4 /K at 0 to 100°C.

The thermal switch of the present invention has a heat retaining effect because the elastic thermal expansion member is in a non-connected state at room temperature or low temperature, and the elastic thermal expansion member is in a connected state due to thermal expansion at high temperature. It acts as a thermal switch that conducts heat and has a heat dissipation effect.

Thus, by using a thermosetting elastomer having a large average linear thermal expansion coefficient and a thermally conductive filler for the elastic thermal expansion member, the thermal switch of the present invention exhibits a large expansion change with respect to temperature change. High responsiveness as a thermal switch. In addition, since the elastic thermal expansion member is flexible, the connection state with the mating member is stable, and the mating member and the like are not destroyed during thermal expansion.

1 is a schematic cross-sectional view showing Embodiment 1 of a thermal switch of the present invention; FIG. FIG. 4 is a schematic cross-sectional view showing Embodiment 2 of the thermal switch of the present invention; FIG. 4 is a schematic cross-sectional view showing Embodiment 3 of the thermal switch of the present invention;

Embodiments of the thermal switch of the present invention are described below. It should be noted that the thermal switch of the present invention is not limited to the following forms, and can be implemented in various forms with modifications and improvements that can be made by those skilled in the art without departing from the gist of the present invention. can be done.

<First Embodiment>
First, the configuration of the thermal switch 1 of this embodiment will be described. The figure on the left side of FIG. 1 shows the thermal switch 1 in a non-connected state of the elastic thermal expansion member 10 made of thermosetting elastomer, and the figure on the right side of FIG. 1 shows a thermal switch 1 at . As shown in FIG. 1, below a predetermined temperature, the elastic thermal expansion member 10 and the second base material 12 are in a state of having a gap without being in contact with each other (unconnected state). On the other hand, when the ambient temperature rises above a predetermined temperature due to the heat source, the elastic thermal expansion member 10 and the second base material 12 are connected to form a heat transfer path (connected state). Since the elastic thermal expansion member 10 is made of a material whose volume reversibly changes with changes in temperature, when the ambient temperature drops below a predetermined temperature, the elastic thermal expansion member 10 shrinks, causing the elastic thermal expansion member 10 to expand. and the second base material 12 are disconnected, and a gap is generated again. Also, the heat source for raising the ambient temperature may be on the first substrate side, on the second substrate side, or on both the first substrate side and the second substrate side.

The size of the gap is such that the elastic thermal expansion member 10, the first base material 11 and the second base material 12 are connected by thermal expansion of the elastic thermal expansion member 10 and heat conduction is possible. It is determined according to the relationship between 10 material properties and the usage environment. The size of the gap is not particularly limited as long as it satisfies the above requirements. Specifically, when the predetermined temperature is 100° C., the linear thermal expansion coefficient of the elastic thermal expansion member 10 is 4×10 ⁻⁴ /K, and the thickness of the elastic thermal expansion member is 10 mm, the elastic thermal expansion member 10 is elastic at room temperature (23° C.). When the shortest distance between the thermal expansion member 10 and the second base material 12 is 0.3 mm or less, the elastic thermal expansion member 10 and the second base material 12 come into contact with each other at 100° C., and the heat dissipation effect works. In addition, the elastic thermal expansion member 10 expands not only in the direction along the first base material 11 and the second base material 12, but also in the direction perpendicular to the direction along the first base material 11 and the second base material 12. It expands when the temperature rises. Therefore, on the four surfaces of the elastic thermal expansion member 10 other than the surface in contact with the first base material 11 and the second base material 12, a restriction member (not shown) having a small coefficient of linear thermal expansion for restricting thermal expansion is provided. This is preferable because the thermal expansion of the elastic thermal expansion member 10 in the direction along the first base member 11 and the second base member 12 is greater than when the restricting member is not provided.

<Second embodiment>
FIG. 2 is a schematic cross-sectional view showing a second embodiment of the thermal switch 1 of the invention. The difference from the thermal switch 1 of the first embodiment is that the elastic thermal expansion member 10 is fixed to the connecting member 13, and the elastic thermal expansion member 10, the first base material 11 and the second base material 12 are heated below a predetermined temperature. The point is that the heat insulating member 14 is provided on a part or the whole of the connecting member 13 without contact. In this case, the elastic thermal expansion member 10, the first base material 11, and the second base material are brought into contact with each other at a predetermined temperature. Moreover, by providing the heat insulating member 14, the first base material 11 and the second base material 12 are reliably insulated at a temperature lower than a predetermined temperature. Although the elastic thermal expansion member 10 does not come into contact with the first base material 11 and the second base material below the predetermined temperature here, the elastic thermal expansion member 10 and the first base material 11 do not come into contact with each other below the predetermined temperature. , may be non-contact with the second base material 12 , or may be in contact with the elastic thermal expansion member 10 and the second base material 12 and not in contact with the first base material 11 .

<Third embodiment>
FIG. 3 is a schematic cross-sectional view showing a third embodiment of the thermal switch 1 of the invention. The difference from the thermal switch 1 of the first embodiment is that the elastic thermal expansion member 10 of the first embodiment is interposed between the first base material 11 and the second base material 12. A thermal expansion member 10 is arranged so as to contact side surfaces of the first base material 11 and the second base material 12 . Even if the elastic thermal expansion member 10 is arranged in a space other than the space where the first base material 11 and the second base material 12 face each other in this manner, the elastic thermal expansion member 10 is positioned between the first base material 11 and the first base material 11 in the connected state. and the second substrate 12, and such an embodiment also has an elastic thermal expansion member interposed between the first and second substrates. shall be included in the expression.

The elastic thermal expansion member is preferably made of a material whose volume reversibly changes with temperature changes, and whose dimensions increase by 1% or more when the temperature rises by 100°C. If the dimension is less than 1%, there is a possibility that the elastic thermal expansion member will not function as a switch in actual use, resulting in poor responsiveness to temperature changes.
More preferably, the average coefficient of linear thermal expansion of the elastic thermal expansion member is in the range of 1×10 ⁻⁴ /K to 10×10 ⁻⁴ /K when the temperature changes from 0° C. to 100° C. If the average linear thermal expansion coefficient is less than 1×10 ⁻⁴ /K when the temperature changes from 0° C. to 100° C., the dimensional change of the elastic thermal expansion member is too small, and the elastic thermal expansion member and the first group The gap between the material and the second base material needs to be precise, and the responsiveness to temperature changes may also deteriorate. Further, if the average coefficient of linear thermal expansion is greater than 10×10 ⁻⁴ /K when the temperature changes from 0° C. to 100° C., the elastic thermal expansion member expands too much, and if the gap is set to allow for the expansion, the heat conduction Since the effect of the reactive filler is reduced, the thermal conductivity may be lowered and the heat dissipation may be deteriorated, which is not preferable.

The elastic thermal expansion member comprises a thermoset elastomer and a thermally conductive filler dispersed in the thermoset elastomer. Here, a thermosetting elastomer is an elastomer vulcanized or crosslinked with a vulcanizing agent or crosslinking agent. Examples of thermosetting elastomers include silicone rubber, urethane rubber, fluororubber, acrylic rubber, natural rubber, butadiene rubber, chlorinated polyethylene, epichlorohydrin rubber, chlorosulfonated polyethylene, and the like. Also, the thermosetting elastomer may be solid or foamed.

The thermal conductivity of the elastic thermal expansion member is 0.25 W/m·K or more. A preferable thermal conductivity is 0.4 W/m·K or more, more preferably 0.5 W/m·K or more. From the viewpoint of increasing the thermal conductivity of the elastic thermal expansion member, it is desirable that the elastic thermal expansion member contains a thermally conductive filler having a relatively high thermal conductivity. A preferable thermal conductivity of the thermally conductive filler used to increase the thermal conductivity of the elastic thermal expansion member is 20 W/m·K or more. Thermally conductive fillers with relatively high thermal conductivity include, for example, magnesium oxide, aluminum oxide, aluminum nitride, boron nitride, silicon carbide, metal powder, graphite, graphene oxide, ferrite, and the like. In particular, when the filler is used for a battery or the like, thermally conductive fillers having insulating properties are preferable in consideration of the possibility of electrical leakage. Thermally conductive fillers having insulating properties include magnesium oxide, aluminum oxide, aluminum nitride, boron nitride, and silicon carbide.

The content of the thermally conductive filler in the elastic thermal expansion member is 20 to 350 parts by mass, preferably 50 to 300 parts by mass, more preferably 100 to 250 parts by mass, per 100 parts by mass of the elastomer. be. If the amount of the thermally conductive filler is 20 parts by mass or less, the thermal conductivity of the elastic thermal expansion member will be less than 0.25 W/m·K, and heat dissipation may deteriorate. Moreover, when the amount of the thermally conductive filler is 350 parts by mass or more, the linear thermal expansion coefficient of the thermally conductive filler may decrease, and the responsiveness as a thermal switch may deteriorate. The thermally conductive filler may be oriented to increase the linear thermal expansion coefficient while maintaining the thermal conductivity of the elastic thermal expansion member. As a method for orienting the thermally conductive filler, a thermally conductive filler having a large aspect ratio and an elastomer may be extruded, or magnetic particles may be added to the thermally conductive anisotropic particles and the elastomer and oriented by a magnetic field.

[Orientation by magnetic field]
Orientation by a magnetic field will be described as an example of reducing the thermally conductive filler in the elastic thermal expansion member. Composite particles composed of thermally conductive anisotropic particles, magnetic particles and a binder are used as the thermally conductive filler that is oriented by a magnetic field. Particles with anisotropic thermal conductivity are particles that have anisotropic thermal conductivity, that is, particles that have different thermal conductivity depending on the direction, and have a large thermal conductivity in the direction of the crystal plane. The thermal conductivity of the anisotropic thermally conductive particles in the direction of the crystal plane is desirably 150 W/m·K or more. The shape of the thermally conductive anisotropic particles is desirably scaly. The thermally conductive anisotropic particles may be non-magnetic particles. Examples of anisotropic thermally conductive particles include boron nitride particles and graphite particles.

The magnetic particles may be those having excellent magnetization properties, for example, ferromagnetic materials such as iron, nickel, cobalt, gadolinium, stainless steel, magnetite, maghemite, manganese zinc ferrite, barium ferrite, strontium ferrite, MnO, Particles of antiferromagnetic materials such as Cr ₂ O ₃ , FeCl ₂ , MnAs, and alloys using these are preferred. Powders of iron, nickel, cobalt, and ferritic alloys thereof are preferably used from the viewpoints of easy availability as fine particles and high saturation magnetization.

The magnetic particles are attached to the surfaces of the anisotropic thermally conductive particles and play a role of orienting the anisotropic thermally conductive particles. The magnetic particles may adhere only to a part of the surface of the thermally conductive anisotropic particles, or may adhere so as to cover the entire surface.

As the binder for bonding the anisotropic thermally conductive particles and the magnetic particles, a water-soluble binder is preferable because it has little effect on moldability and is friendly to the environment. Examples thereof include methylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinyl alcohol and the like.

Since boron nitride particles are electrically insulating, the use of boron nitride particles as thermally conductive anisotropic particles is advantageous for applications that require insulating properties. However , if conductive particles are used as the magnetic particles attached to or coated on the surface, the insulating property of the elastic thermal expansion member is lowered. Therefore, in the case where the elastic thermal expansion member is required to have insulating properties, such as for heat dissipation applications of batteries and electronic parts, it is desirable to employ insulating particles as the magnetic particles. As the electrically insulating particles, iron oxide particles, manganese ferrite particles, and the like, which themselves have insulating properties, are suitable.

The content of the anisotropic thermally conductive particles in the elastic thermal expansion member may be appropriately determined according to the type of the anisotropic thermally conductive particles. If the content of the anisotropic thermally conductive particles is too low, the heat transfer path will not be sufficiently formed. Therefore, in order to obtain the effect of improving the thermal conductivity, the content of the anisotropic thermally conductive particles is desirably 20 parts by mass or more when the mass of the thermosetting elastomer is 100 parts by mass. On the other hand, from the viewpoint of reducing the influence of moldability and physical properties and preventing high costs, the content of the anisotropic thermally conductive particles is 300 parts by mass or less when the mass of the thermosetting elastomer is 100 parts by mass. is desirable.

The production method of the present invention relating to orientation of thermally conductive anisotropic particles into an elastomer by a magnetic field comprises a composite particle production step, a mixed raw material adjustment step, and a molding step.

First, the composite particles are produced by agitating each powder using an agitating granulator.

In addition to the elastomer component, the elastomer raw material may contain retarders, plasticizers, catalysts, foaming agents, foam stabilizers, flame retardants, antistatic agents, viscosity reducers, stabilizers, fillers, colorants, etc. include. The mixed raw material may be prepared by stirring and mixing the thermally conductive particles and the elastomer raw material using an intermixer, a stirring blade, or the like.

The molding step is a step of placing the raw material mixture prepared in the previous step in a mold and molding the raw material mixture in a magnetic field.

The mold may be closed or open. The magnetic field may be formed in a direction that orients the anisotropic thermally conductive particles. For example, when the thermally conductive anisotropic particles are oriented linearly, it is desirable to apply magnetic lines of force from one end to the other end of the mixed raw material. In order to form such a magnetic field, magnets may be arranged so as to sandwich the raw material mixture. A permanent magnet or an electromagnet may be used as the magnet. By using an electromagnet, it is possible to instantly switch on and off the formation of the magnetic field, making it easy to control the strength of the magnetic field.

In this step, it is desirable to apply a magnetic field having a substantially uniform magnetic flux density to the mixed raw material. Specifically, the difference in magnetic flux density in the mixed raw material is preferably within ±10%. Within ±5%, more preferably within ±3%. By applying a uniform magnetic field to the mixed raw material, uneven distribution of the thermally conductive anisotropic particles can be suppressed, and a desired orientation state can be obtained. Moreover, it is preferable that the molding be performed at a magnetic flux density of 150 mT or more and 1200 mT or less. By doing so, the thermally conductive anisotropic particles in the mixed raw material can be reliably oriented. After the molding is completed in this step, it is demolded and crosslinked to obtain the elastic thermal expansion member of the present invention.

In the thermal switch of the present invention, as a method for fixing the elastic thermal expansion member to the connecting member, the first base material and the second base material, it may be fixed by caulking with a metal member or the like, or by fixing with an adhesive. good too.

[Members other than elastic thermal expansion members]
The first base material and the second base material are not particularly limited as long as they have thermal conductivity, but it is preferable that the material has high thermal conductivity. Specifically, the first base material and the second base material are preferably made of a material having a thermal conductivity of 1 to 500 W/mK. The higher the thermal conductivity of the material, the greater the difference in apparent thermal conductivity between the connected state and the unconnected state of the thermal switch. The materials forming the first and second substrates are preferably metals or alloys.

The material for forming the connecting member is not particularly limited as long as it has heat insulating properties. As the material of the connecting member, a material having a relatively small thermal expansion with respect to heat change, and a material having a low thermal conductivity such as a resin or an elastomer may be used. Moreover, a heat insulating member may be provided on a part of the connecting member in order to improve heat retention.

The heat insulating member should just insulate heat, and its thermal conductivity is preferably 0.2 W/m·K or less. In addition, it is preferable that the average linear thermal expansion coefficient is not large, and the average linear thermal expansion coefficient when the temperature changes from 0 ° C. to 100 ° C. is in the range of 1 × 10 ^-6 /K to 5 × 10 ^-4 /K. is preferred.

The heat insulating member is not particularly limited, but resins and elastomers are preferable from the viewpoint of heat insulating properties. Resins and elastomers include acrylic, urethane, silicone, polystyrene, latex, synthetic rubber, polyester, polyvinyl alcohol, polypropylene, polyethylene, polyfluorocarbon, polycarbonate, polyamide, polyphenylene ether, polyacetal, polybutylene terephthalate, polyetheretherketone, epoxy. Any one selected from the group consisting of resin, phenol resin, polyphenylene sulfide and polyimide is preferable.

In order to further improve heat insulation, resin and elastomer foams, resin and elastomer mixed with ceramic particles such as titania, alumina and zirconia, engineering plastics such as silica, silica airgel, glass fibers and aramid fibers, and super engineering plastic fibers. may Silica airgel (thermal conductivity: 0.025 W/m·K) and ALC panel (thermal conductivity: 0.17 W/m·K) are preferable from the viewpoint of high heat insulation in a particularly small space.

In the thermal switch of the present invention, the method of providing the gap with a predetermined size is not particularly limited as long as the structure maintains heat retention in the non-connected state. As shown in FIG. 2, a connection member having heat insulation may be used for fixing.

Next, the temperature control function provided with the thermal switch of the present invention around the battery pack will be described. By changing the heat dissipation state at a predetermined temperature, the battery pack effectively utilizes the heat from the discharge and adjusts the temperature to improve the function of the battery. Specifically, since the temperature is low when the automobile is started, the battery resistance is high, and it is desirable to dissipate the heat inside the battery pack as little as possible. On the other hand, after the automobile is warmed up, the temperature inside the battery pack rises and there is a risk of ignition due to the decomposition of the electrolyte. Since the thermal switch of the present invention provided in the battery pack is in a non-connected state when the automobile is started, it is difficult to dissipate the heat inside the battery pack. can rise. On the other hand, after the vehicle warms up, the temperature inside the battery pack rises, the thermal switch is closed, and the heat transfer efficiency rises sharply, so the heat inside the battery pack can be actively released to the outside.

EXAMPLES Next, the present invention will be specifically described with reference to examples.

[Example 1]
100 parts by mass of natural rubber, 200 parts by mass of magnesium oxide powder ("RF-50SC" manufactured by Ube Materials Co., Ltd., thermal conductivity 45 W / m K) as a thermally conductive filler, zinc oxide (zinc oxide manufactured by Sakai Chemical Industry Co., Ltd.) Type 2) 5 parts by mass, zinc stearate (Lunax S30 manufactured by Kao Corporation) 1 part by mass, antioxidant A (Ozonon 6C manufactured by Seiko Chemical Co., Ltd.) 1.5 parts by mass, anti-aging agent B (Nonflex manufactured by Seiko Chemical Co., Ltd.) RD) 1 part by mass, vulcanizing aid (zinc monomethacrylate, PRO11542 manufactured by Sartomer) 3 parts by mass, wax (Sannok manufactured by Ouchi Shinko Kagaku Co., Ltd.) 2 parts by mass, oil (naphthene oil, Diana process manufactured by Idemitsu Kosan Co., Ltd.) NM-280) 5 parts by mass, vulcanization accelerator A (N-cyclohexyl-2-benzothiazolylsulfenamide, Ouchi Shinko Chemical Co., Ltd. Noccellar CZ) 2 parts by mass, vulcanization accelerator B (tetramethylthiuram disulfide , Suncellar TT manufactured by Sanshin Kagaku Kogyo Co., Ltd.) and 0.5 parts by mass of a vulcanizing agent (sulfur manufactured by Karuizawa Seirensho Co., Ltd.) were kneaded. In the kneading, first, materials other than the vulcanizing agent and the vulcanization accelerator are kneaded using a Banbury mixer at 140 ° C. for 5 minutes, and then the vulcanizing agent and the vulcanization accelerator are blended and opened. The mixture was kneaded at 60° C. for 5 minutes using a roll. Then, press molding (vulcanization) was performed under the conditions of 160° C. for 20 minutes to produce a natural rubber sheet of 100 mm long×100 mm wide×10 mm thick to obtain an elastic thermal expansion member.

A 100 mm×100 mm×1 mm aluminum plate (thermal conductivity: 237 W/m·K) was used for the first base material and the second base material.

The elastic thermal expansion member, the first base material and the second base material are attached to the connecting member with an adhesive, and a gap of 0.1 mm is provided between the elastic thermal expansion member and the first base material and the second base material. was provided to fabricate the thermal switch of Example 1.

[Example 2]
A thermal switch of Example 2 was produced in the same manner as in Example 1, except that the amount of magnesium oxide powder compounded in the elastic thermal expansion member was changed to 300 parts by mass.

[Example 3]
A thermal switch of Example 3 was produced in the same manner as in Example 1, except that the amount of magnesium oxide powder compounded in the elastic thermal expansion member was changed to 50 parts by mass.

[Comparative Example 1]
A thermal switch of Comparative Example 1 was produced in the same manner as in Example 1, except that the amount of the magnesium oxide powder compounded in the elastic thermal expansion member was changed to 0 parts by mass.

[Comparative Example 2]
A thermal switch of Comparative Example 2 was produced in the same manner as in Example 1, except that the amount of magnesium oxide powder compounded in the elastic thermal expansion member was changed to 400 parts by mass.

[Example 4]
<Production of Composite Particle A>
A thermally conductive filler was produced by an agitation granulation method. First, scale-like boron particles ("Flakes 70/500" manufactured by 3M Japan, average particle size (D ₅₀ ) 230 to 280 μm), and insulating stainless steel powder as magnetic particles ("Fe -3.5% Si-4.5% Cr” insulation treated product, spherical, average particle size 3 μm) and binder hydroxypropyl methylcellulose (HPMC, “TC-5” manufactured by Shin-Etsu Chemical Co., Ltd.) were prepared. .

Next, 300 g of scale-like boron particles, 150 g of insulating stainless steel powder, and 13.5 g of HPMC were charged into a container of an FM mixer (manufactured by Nippon Coke Kogyo Co., Ltd.) and mixed for 1 minute. After that, 125 g of water was added and mixed for another 6 minutes to produce composite particles A.

<Manufacture of elastic thermal expansion member>
Composite particles A were used to produce an elastic thermal expansion member. First, liquid silicone rubber (“EG-3100” manufactured by Dow Corning Toray Co., Ltd.) 100 parts by mass, hydrogen dimethicone (“KF9901” manufactured by Shin-Etsu Chemical Co., Ltd.) 0.2 parts by mass of a cross-linking agent, and acetylene glycol as a retarder ("Surfinol (registered trademark) 61" manufactured by Nissin Chemical Industry Co., Ltd.) and 0.05 parts by mass were mixed to produce a silicone compound.

Next, 104 parts by mass of Composite Particles A was added to prepare a mixed raw material. Subsequently, the mixed raw material was poured into an aluminum mold (the cavity was a rectangular parallelepiped of 100 mm long×100 mm wide×10 mm thick) preheated to 130° C. in an oven and sealed. Then, the mold was set in a magnetic induction molding apparatus, and the magnetic flux density in the cavity was set to about 1000 mT, and the molding was performed at 130° C. for 10 minutes while applying a magnetic field. After the molding was completed, the mold was removed to obtain an elastic thermal expansion member. After that, a thermal switch was produced in the same manner as in Example 1, and a thermal switch of Example 4 was obtained.

<Measurement of type A durometer hardness>
Using a JIS K6253-3:2012 hardness tester ("ASKER P1-A" manufactured by Kobunshi Keiki Co., Ltd.), three elastic thermal expansion members with a thickness of 1 mm were stacked to measure the type A durometer hardness. As the type A durometer hardness, an instantaneous value immediately after contact between the indenter and the elastic thermal expansion member was adopted.

<Measurement of thermal conductivity>
The thermal conductivity of the elastic thermal expansion member was measured using a heat flux meter "HC-074" manufactured by Eko Seiki Co., Ltd., which complies with the heat flow meter method of JIS A1412-2:1999.

<Average linear thermal expansion coefficient>
Regarding the average linear thermal expansion coefficient of the elastic thermal expansion member, the linear thermal expansion coefficient was measured based on JIS K7197-1991, and taken as the average linear thermal expansion coefficient.

<Evaluation of Thermal Switch>
A heat flux meter was used to evaluate how heat was transferred from the first base material to the second base material. Specifically, the temperature on the first base material side is adjusted, and the heat quantity is measured with a heat flux meter attached to the second base material when the temperature on the first base material side is set to 23 ° C and 150 ° C. did. As a result, in Example 3, the thermal conductivity of the elastic thermal expansion member was low, resulting in slightly inferior heat dissipation, but it functioned as a thermal switch. In Comparative Example 1, the thermal conductivity of the elastic thermal expansion member was low, and the heat dissipation was poor. In Comparative Example 2, the average linear thermal expansion coefficient of the elastic thermal expansion member was low, the elastic thermal expansion member did not come into contact with the second base material, and did not function as a thermal switch.

The thermal switch of the present invention can be used as a switch whose heat transfer performance changes with temperature. For example, in battery packs, exhaust gas filters, etc., even if the catalyst activity is low at the start of the cold state, it can be heated up to the activation temperature in a relatively short time by heat insulation. It is expected that the heat deterioration of the catalyst and the base material can be suppressed. When the thermal switch of the present invention is used in a battery pack, an exhaust gas filter, or the like, it is possible to maintain an optimum temperature by controlling heat dissipation and heat retention, thereby optimizing the discharge effect of the battery.

1 thermal switch 10 elastic thermal expansion member 11 first base material 12 second base material 13 connecting member 14 heat insulating member 15 supporting member

Claims (6)

It is interposed between the first base material, the second base material, and the first base material and the second base material, and expands under predetermined temperature conditions to form the first base material and the second base material. an elastic thermal expansion member connected to the base material and forming a heat transfer path between the first base material and the second base material,
the elastic thermal expansion member comprises a thermoset elastomer and a thermally conductive filler dispersed in the thermoset elastomer;
The thermal switch, wherein the elastic thermal expansion member has an average linear thermal expansion coefficient of 1×10 ^-4 /K to 10×10 ^-4 /K at 0 to 100°C.
The thermosetting elastomer is selected from crosslinkable elastomers such as silicone rubber, urethane rubber, fluororubber, acrylic rubber, natural rubber, butadiene rubber, chlorinated polyethylene, epichlorohydrin rubber, and chlorosulfonated polyethylene. 2. The thermal switch of claim 1.
3. The thermal switch according to claim 1, wherein the thermal conductivity of said thermally conductive filler is 20 W/m·K or more.
The thermal switch according to any one of claims 1 to 3, wherein the thermally conductive filler is 20 to 350 parts by mass with respect to 100 parts by mass of the thermosetting elastomer.
5. The thermal switch according to claim 1, wherein the thermally conductive filler is oriented in the elastic thermal expansion member so as to form a heat transfer path from the first substrate along the second substrate.
6. The thermal switch according to claim 5, wherein the thermally conductive filler is a composite particle composed of thermally conductive anisotropic particles, magnetic particles and a binder.

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