WO2013014981A1

WO2013014981A1 - Heat-conducting material and heat-conducting member using same

Info

Publication number: WO2013014981A1
Application number: PCT/JP2012/059084
Authority: WO
Inventors: 後藤　浩之; 久野　憲康
Original assignee: 日清オイリオグループ株式会社; 三和油脂株式会社
Priority date: 2011-07-22
Filing date: 2012-04-03
Publication date: 2013-01-31
Also published as: JP2014193935A

Abstract

[Problem] To develop a heat-conducting material free of thermal anisotropy that need not use silicone rubber while maintaining equivalent thermal conductivity to the thermal conductivity of conventional products, and to provide a heat-conducting member that uses the same. [Solution] This heat-conducting member is provided with: a matrix which is any of rubber, resin, paint, or cement; and a burned plant material which is any of soybean hulls, rapeseed meal, defatted sesame cake, cotton seed meal, cotton hulls, soybean chaff, soybean cake, cacao husks, palm empty fruit bunch, and palm kernel shells contained in the matrix; the components being pre-formed to match the shape of the heat-conducting member unit at the time of manufacture, and the burned plant material being included in a state uniformly dispersed in the matrix.

Description

Heat conducting material and heat conducting member using the same

The present invention relates to a heat conducting material and a heat conducting member using the same, and more particularly to a heat conducting material having no thermal anisotropy and a heat conducting member using the same.

As a non-metallic heat conductive member, Patent Document 1 includes silicone rubber, the heat conductivity of a vulcanized molded body is 0.4 W / m · K or more, and the volume resistivity is 10 ⁹ Ω · cm. The above heat conductive and electrically insulating silicone rubber composition is disclosed.

JP 2000-053864 A

However, as shown in Patent Document 1, the heat conductive member containing silicone rubber has a problem that generation of siloxane gas that causes contact failure such as a switch and a relay is concerned. For this reason, there is a demand for an alternative product that can obtain a thermal conductivity equal to or higher than that of a conventional product without using silicone rubber.

Therefore, the present invention has developed a non-metallic heat conductive material that does not require the use of silicone rubber while maintaining the same thermal conductivity as that of a conventional product, and heat conduction using the same. It is an object to provide a member. In particular, it is an object of the present invention to provide a heat conductive member that has no thermal anisotropy and has a very high thermal conductivity as a rubber-based material, and a heat conductive material used therefor.

In order to solve the above problems, the heat conducting member of the present invention is
The preforming according to the shape of the heat conduction member main body is made at the time of manufacture, and the baked plant is contained in a state of being uniformly dispersed with respect to the base material.

Moreover, the heat conductive material of the present invention includes the above-mentioned burned plant.

As the plant burned product, burned products such as soybean hulls, rapeseed meal, sesame meal, cottonseed meal, cotton hull, soybean hull, soybean hull, cacao husk, palm coconut empty fruit bunch, palm coconut shell, and the like can be used. As the base material, ethylene / propylene diene rubber, paint, cement, resin and the like can be used.

According to the present invention, for example, when each plant is used as a raw material, if the content is 200 [phr] with respect to the base material and the graphitization is performed at a firing temperature of 1500 ° C. or higher, for example, the thermal difference will occur. A thermal conductivity of 0.4 [W / (m · K)] or more with no directivity can be obtained.

Further, as will be described in detail in the embodiments described later, it is also confirmed that the heat conductive material of the present invention has an electromagnetic wave shielding effect, an electromagnetic wave absorbing effect, and a conductive effect.

It is a typical manufacturing process figure of the heat conductive member of embodiment of this invention. It is a figure which shows the measurement result of the heat conductivity of the heat conductive member manufactured through the pre-forming process demonstrated using FIG. It is a figure which shows the measurement result which supplements the content of FIG. It is a SEM photograph in the cross section of the X direction of the heat conductive member manufactured through the pre-forming process demonstrated using FIG. It is a SEM photograph in the cross section of the Y direction of the heat conductive member manufactured through the pre-forming process demonstrated using FIG. It is a SEM photograph in the section of the Z direction of the heat conduction member manufactured through the preliminary formation process explained using Drawing 1. It is a SEM photograph in the cross section of the X direction of the heat conductive member manufactured through the pre-forming process demonstrated using FIG. It is a SEM photograph in the cross section of the Y direction of the heat conductive member manufactured through the pre-forming process demonstrated using FIG. It is a SEM photograph in the section of the Z direction of the heat conduction member manufactured through the preliminary formation process explained using Drawing 1. It is a SEM photograph of the palm palm empty fruit bunch fired product obtained by firing at about 900 ° C. It is a SEM photograph of the palm eggplant empty fruit baked thing obtained by baking at about 3000 degreeC. It is a SEM photograph of the palm palm shell baked material obtained by baking at about 900 degreeC. It is a SEM photograph of the palm coconut shell baking products obtained by baking at about 3000 degreeC. It is a SEM photograph of the cacao husk fired product obtained by firing at about 3000 ° C. It is a SEM photograph of the coconut shell baked material which made the manufacturing process mentioned below different as a comparative example. It is a figure which shows the volume specific resistivity measured at arbitrary 9 points | pieces of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 900 degreeC. It is a figure which shows the surface resistivity measured at arbitrary 9 points | pieces of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 900 degreeC. It is a figure which shows the measurement result of the electromagnetic wave shielding amount of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 900 degreeC. It is a figure which shows the electromagnetic wave absorption characteristic of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 900 degreeC. It is a figure which shows the volume resistivity of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 3000 degreeC. It is a figure which shows the surface resistivity of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 3000 degreeC. It is a figure which shows the measurement result of the electromagnetic wave shielding amount of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 3000 degreeC. It is a figure which shows the electromagnetic wave absorption characteristic of the heat conductive member containing baking products, such as soybean hulls obtained by baking at about 3000 degreeC. It is a figure which shows the measurement result of the heat conductivity of the heat conductive member containing the heat conductive material shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the embodiment of the present invention, a case where, for example, a burned soybean hull obtained by baking soybean hull at a high temperature is used as a burned plant constituting the heat conductive member will be described. However, for plant burned products such as rapeseed meal, cotton hull, sesame meal, cottonseed meal, soybean husk, soybean meal, cacao husk, palm coconut empty fruit bunch, palm coconut shell, etc. It can be used for a baked plant that constitutes a heat conducting member. It should also be noted that it is not essential to graphitize the burned plant.

In addition, the cacao husk referred to in the present embodiment is mainly the skin itself covering a plurality of cacao beans contained in the fruit of cacao, and is sometimes referred to as cacao shell. In the present embodiment, such a thing is also subject to various experiments and evaluations, but only the cacao shell or a mixture of this and the skin covering the cacao bean is included in the cacao husk referred to in the present embodiment. .

The burned material of soybean hulls according to this embodiment is an inert gas atmosphere such as nitrogen gas selectively at a temperature of, for example, about 1500 [° C.] to 3000 [° C.] using a carbonization apparatus such as a stationary furnace or a rotary kiln. This is graphitized by baking soybean hulls or the like at an ultimate temperature for about 3 hours under or in a vacuum.

Here, the firing temperature and firing time may be the conditions necessary for graphitizing the burned soybean hulls beyond roasting. Therefore, it should be noted that there are some differences depending on the type of carbonization apparatus, the amount of soybean hull treated during carbonization, and the like.

Further, as a result of repeated research and experiments, it was found that the burned soybean hulls may be used by pulverization or may be used without pulverization depending on the use of the heat conducting member. As used herein, “use without pulverization” not only means that the baked soybean hulls are not pulverized, but also the soybean hulls themselves that are produced when producing edible oil and the like using soybeans as raw materials. However, it means that the pulverization treatment is not performed, that is, a so-called unglazed state is used.

The bulk density and packing density of the burned soybean hulls that were not crushed were measured. In order to investigate whether or not the bulk density and packing density change with time, the burned soybean hulls manufactured in October 2008, the burned soybean hulls manufactured in March 2009, and the burned soybean hulls manufactured in September 2010 Each dried product was measured. In addition, the burning temperature of all the burned soybean hulls was about 900 ° C. Moreover, the measurement method of the bulk density and the filling density is based on JIS K 1474 standard.

In the case of the burned material of soybean hulls manufactured in October 2008, the bulk density was 0.092 [g / ml] and the packing density was 0.203 [g / ml].

In the case of the burned soybean hull manufactured in March 2009, the bulk density was 0.0895 [g / ml] and the packing density was 0.1828 [g / ml].

In the case of the burned material of soybean hulls manufactured in September 2010, the bulk density was 0.088 [g / ml] and the packing density was 0.187 [g / ml].

From the above measurement results, it can be said that there is no change with time in the bulk density and packing density of the burned soybean hulls. The bulk density is considered to be approximately in the range of 0.08 [g / ml] to 0.1 [g / ml], and the packing density is approximately in the range of 0.18 [g / ml] to 0.25 [g. / Ml].

In this embodiment, this burned soybean hull is blended with ethylene / propylene diene rubber, silicon rubber, low density polyethylene, isoprene, urethane, glass wool, polyvinyl chloride resin and the like as the base material. The base material is preferably excellent in heat resistance and moldability. Hereinafter, unless otherwise specified, the case where ethylene / propylene diene rubber is used as a base material will be described as an example.

Next, the burned material of soybean hulls is blended with ethylene / propylene diene rubber in an amount of, for example, about 100 [phr] to about 400 [phr] (per hundred resin (rubber)). Thereafter, if the rubber is vulcanized and molded, a heat conductive member as a final product can be obtained.

Here, when a heat conductive material such as burned soybean hulls is kneaded with ethylene / propylene diene rubber as a base material, activation that is often performed on carbon materials with respect to the burned soybean hulls or the like It is known that the amount of kneading is reduced when the chemical treatment is performed, and it is difficult to knead, for example, 400 [phr]. In order to solve this problem, the heat conducting member of this embodiment is characterized in that it does not actively use a heat conducting material that has been subjected to a soot activation treatment. That is, it is preferable to use the heat conductive material of this embodiment that has not been subjected to the soot activation treatment.

FIG. 1 is a schematic manufacturing process diagram of a heat conducting member according to an embodiment of the present invention. First, with respect to raw soybean hulls generated during the production of edible oil, etc., a phenol resin such as a resol-type phenol resin is selectively added, and then set in a carbonization apparatus. The temperature is increased by about 2 [° C.] per minute to reach a predetermined temperature of 600 [° C.] to 3000 [° C.] (for example, 900 [° C.]). Then, carbonization baking treatment / graphitization treatment is performed at an ultimate temperature for several hours to several weeks, for example.

The graphitization treatment here is not only graphitized by firing at a firing temperature of, for example, 1500 [° C.] for a relatively long time, but also relatively short time at, for example, a firing temperature of 3000 [° C.]. It includes graphitization by firing. In addition, carbonization is performed by primary firing at a firing temperature of, for example, 900 [° C.], and graphitization is performed separately by firing at a firing temperature of, for example, 3000 [° C.].

When mixed with a resol type phenol resin, the strength and carbon content of the burned soybean hulls can be improved. However, it should be noted that the mixing itself is not always necessary for manufacturing the heat conducting member of the present embodiment.

Next, the baked soybean hulls are pulverized and then subjected to a sieving process to obtain a burned soybean hull having a median diameter of, for example, about 20 μm to about 60 μm. Thus, first, a heat conductive material is manufactured.

Next, various additives such as naphthenic process oil, aromatic process oil, and paraffinic process oil are mixed with the burned soybean hulls and ethylene / propylene diene rubber, and then set in a kneader. Knead.

The burned soybean hulls are uniformly dispersed with respect to the base material ethylene / propylene diene rubber by the kneading process. Uniformly dispersed here means that the burned soybean hulls having no shape specificity are not three-dimensionally distributed with respect to the ethylene / propylene diene rubber without orientation. Next, preliminary molding corresponding to the size of the molding machine for molding the heat conducting member is performed.

Here, when trying to manufacture a large-sized heat conductive member, simply pressing the kneaded material with a molding machine does not spread the kneaded material to a desired size, corners are not formed well, and the heat conductive member There is a problem that sufficient strength and durability cannot be imparted, or that the heat conducting member is easily broken or has a hole. In particular, when a large amount of a heat conductive material is kneaded with ethylene / propylene diene rubber (for example, 250 [phr] or more), the viscosity of the kneaded product increases, and this problem is spurred.

In addition, even if the heat conduction member is not large, even when trying to produce a very thin heat conduction sheet such as several mm or several μm, the kneaded material is spread to a desired size as described above. There are problems such as difficulty.

In order to avoid this, in general, for example, it may be possible to set in a molding machine by adopting an injection method in which the kneaded material is extruded from a required nozzle.

However, when the injection method is employed, the burned material of soybean hulls kneaded with ethylene / propylene diene rubber is oriented by the flow of the kneaded material generated at the time of extrusion, and directionality according to the shape may be generated. If it does so, the thermal conductivity member which will be mentioned later may occur in the heat conduction member which is a finished product.

In the first place, if the viscosity of the kneaded product is too high, it is difficult to adopt the injection method. This is because if the viscosity is too high, the nozzle may be clogged, and if not, directionality will occur in the burned soybean hulls kneaded with ethylene / propylene diene rubber.

Therefore, in the present embodiment, for example, when a heat conduction member of 150 mm square × 2.5 mm is to be manufactured, the heat is basically irrespective of the content of the burned soybean hulls with respect to ethylene / propylene diene rubber. Rather than simply setting the conductive member to the molding machine, the heat conductive member is preformed to a size of, for example, 120 mm square to 150 mm square × approximately 4.5 mm to 2.5 mm, and then set to the molding machine. I am doing so.

After that, if the kneaded product is subjected to a molding process and then vulcanized, the production of the heat conducting member is completed.

Here, the heat conduction member of the present embodiment uses a molding machine such as a mold having a required shape on the condition of preforming even if the content of the burned soybean hulls with respect to ethylene / propylene diene rubber is large. Can be molded. For this reason, even if the shape of the electronic substrate that is mounted on an electronic device or the like and requires a heat conductive member is not planar, it is possible to manufacture the heat conductive member according to the shape of the electronic substrate. Become.

However, the heat conducting member of this embodiment also has a degree of freedom of processing such as cutting and bending. This point is also an advantage in manufacturing the heat conducting member.

Here, due to space saving in the housing of the electronic device due to recent downsizing of the electronic device, it is difficult to use the heat conducting member, or the layout of the electronic device considering the arrangement space of the heat conducting member is There is a problem that it is necessary.

Since the heat conducting member of the present embodiment can have a shape corresponding to the shape of the space in the electronic device, there is no need to perform product layout considering the arrangement space of the heat conducting member. It also has an effect.

The heat conducting member of the present embodiment can be suitably used for electronic devices, inspection devices for electronic devices, building materials, and the like. That is, for example, the heat conducting member of the present embodiment is provided in a communication terminal main body such as a mobile phone, PDA (Personal Digital Assistant), or attached to an electronic board mounted on the communication terminal main body, various home appliances, automobiles, A central processing unit (CPU) of a personal computer, a graphics processing unit (GPU), various sensors, LED lighting equipment, a motor peripheral part, a so-called shield box, a roof material, a floor material, a wall material, etc. Therefore, it can also be used for work shoes and work clothes as an antistatic body.

By the way, when the object to be kneaded with ethylene / propylene diene rubber is a carbon-based material containing carbon nanotubes instead of burned soybean hulls, it is considered that thermal anisotropy occurs in the heat conducting member. (See JP2010-212520, JP2010-189272, etc.) The heat conducting member of this embodiment is unique in that it has no thermal anisotropy.

Moreover, the following experiment and measurement were performed on the burned material of soybean hulls according to the present embodiment. In this example, the burned material of soybean hulls has a median diameter of about 30 μm and about 60 μm, and several experiments and measurements have been performed. The difference was not seen.

(1) Regarding the burned material of soybean hulls according to the present embodiment, physical properties such as bulk specific gravity, BET specific surface area, and crystallite size were measured.

(2) About the burned soybean hulls according to the present embodiment, whether or not blending with a base material other than ethylene / propylene diene rubber was possible, and the burned product content with respect to rubber when blending was possible were measured.

First, as for physical property values, the following measurement results were obtained.
Bulk specific gravity: about 0.2 g / ml to about 0.6 g / ml (most band about 0.4 g / ml)
BET specific surface area: about 4.7 m ² / g to about 390 m ² / g
Crystallite size (Lc [002]): about 1 nm to about 100 nm

In addition, when what was baked at each calcination temperature of 900 [degreeC], 1500 [degreeC], and 3000 [degreeC], it turns out that a BET specific surface area changes with calcination temperatures.

Next, the measurement result of the thermal conductivity of the heat conducting member of this embodiment will be described. Thermal conductivity measurement was performed at a temperature of about 25 ° C. for each sample described below. The measurement method of thermal conductivity was a hot wire method, and was performed in accordance with JIS standard R2616.

In addition, the measurement of the thermal conductivity of the sample was performed in a state where eight heat conductive members having a size of length 100 mm × width 50 mm × thickness 2.5 mm were stacked (measurement of sample A and sample D). Only for the measurement of 150 [phr], a thickness of 2.0 mm × 10 sheets was laminated). As a measuring device, a rapid thermal conductivity meter QTM-500 (manufactured by Kyoto Electronics Co., Ltd.) was used. And the measurement of thermal conductivity was performed on the precision conditions from which the numerical value within the thermal conductivity specification value +/- 5% of the standard sample mentioned later is obtained.

FIG. 2 is a diagram showing the measurement results of the thermal conductivity of the heat conductive member of the present embodiment, that is, the heat conductive member manufactured through the preliminary forming step described with reference to FIG. FIG. 2 shows a case where a predetermined amount of various types of samples described below and any two types of carbon black (CB1, 2) distributed in the market as comparative examples are contained in a base material (ethylene / propylene diene rubber). The thermal conductivity of is shown.

For reference, FIG. 2 also shows thermal conductivity of foamed polyethylene (PE), silicon rubber, and quartz glass as standard samples. Moreover, about CB2, it was set as thickness 2.0mm x 10 sheet lamination | stacking.

First, the thermal conductivity of the standard sample is 0.036 [W / (m · K)] for foamed polyethylene (PE), 0.238 [W / (m · K)] for silicon rubber, and 1. 42 [W / (m · K)].

The thermal conductivity of carbon black (CB1, 2) was 0.377 [W / (m · K)] and 0.418 [W / (m · K)], respectively. The content of carbon black (CB1, 2) with respect to the base material was 100 [phr]. Further, the thermal conductivity of the base material itself was slightly 0.211 [W / (m · K)].

Specimen A is a heat conduction material manufactured by firing soybean hulls at a temperature of about 900 ° C. and without pulverizing them. The median diameter of this heat conducting material is about 30 μm. When the sample A is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.342 [W / (m · K)], 0.446 [W / (m · K)], 0.651 [W / (m · K)].

Sample B is a heat conduction material manufactured by baking soybean powder at a temperature of about 900 ° C. and finely pulverizing it. The median diameter of this heat conducting material is about 5 μm. When Sample B is contained in the base material at 100 [phr], 150 [phr], 200 [phr], 300 [phr], and 400 [phr], the thermal conductivity is 0.334, respectively. [W / (m · K)], 0.391 [W / (m · K)], 0.436 [W / (m · K)], 0.518 [W / (m · K)], 0 587 [W / (m · K)].

Sample C is a heat conduction material manufactured without firing and pulverizing soybean hulls at a temperature of about 1500 ° C. The median diameter of this heat conducting material is about 30 μm. When the sample C is contained in the base material at 100 [phr], 200 [phr], and 300 [phr], respectively, the thermal conductivity is 0.498 [W / (m · K)], It was 0.769 [W / (m · K)], 1.030 [W / (m · K)].

Sample D is a heat conduction material manufactured without firing and pulverizing soybean hulls at a temperature of about 3000 ° C. The median diameter of this heat conducting material is about 30 μm. When the sample D is contained in the base material at 150 [phr] and 400 [phr], the thermal conductivities are 1.100 [W / (m · K)] and 3.610 [W, respectively. / (M · K)].

Specimen N is a heat conduction material manufactured without baking and pulverizing rapeseed meal at a temperature of about 900 ° C. The median diameter of this heat conducting material is about 48 μm. When the sample N is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.344 [W / (m · K)], It was 0.460 [W / (m · K)], 0.654 [W / (m · K)].

Specimen M is a heat conduction material manufactured without firing and pulverizing cottonseed meal at a temperature of about 900 ° C. The median diameter of this heat conducting material is about 36 μm. When the sample N is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.348 [W / (m · K)], It was 0.482 [W / (m · K)], 0.683 [W / (m · K)].

Sample G is a heat conductive material produced by baking sesame seeds at a temperature of about 900 ° C. and without pulverizing them. The median diameter of this heat conducting material is about 61 μm. When the sample N is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.345 [W / (m · K)], It was 0.471 [W / (m · K)], 0.665 [W / (m · K)].

Sample CT is a heat conductive material produced by firing cotton hull at a temperature of about 900 ° C. and without pulverizing. The median diameter of this heat conducting material is about 34 μm. When the sample CT is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.361 [W / (m · K)], 0.495 [W / (m · K)], 0.705 [W / (m · K)].

Specimen CA is a heat conduction material manufactured without firing and pulverizing cacao husk at a temperature of about 900 ° C. The median diameter of this heat conducting material is about 39 μm. When the sample CA is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.355 [W / (m · K)], It was 0.483 [W / (m · K)], 0.692 [W / (m · K)].

First, when the thermal conductivity of the base material is compared with the thermal conductivity of each sample, it can be seen that the thermal conductivity of each sample is high. Therefore, it can be seen that it is better in terms of thermal conductivity to contain the heat conductive material of the present embodiment than to use only the base material as the heat conductive member.

The thermal conductivity when the sample A is contained in 100 [phr] with respect to the base material is not significantly different from that of each of the comparative examples. This seems to be due to the close carbon content of the base material. Moreover, although it can be evaluated that the thermal conductivity when the sample A is contained at 200 [phr] with respect to the base material is slightly better than that of each of the comparative examples, a marked increase cannot be confirmed. On the other hand, the thermal conductivity when Sample A was included in the base material at 400 [phr] increased to 1.5 times or more of each of the Comparative Examples.

Next, when the thermal conductivity of the sample A and the samples N, M, G, CT, and CA were compared, it was found that the same tendency was generally observed. That is, it can be understood that these samples all have the same thermal conductivity when the content of the heat conductive material with respect to the base material is the same. And all of these samples show that the heat conductivity increases as the content of the heat conductive material with respect to the base material increases.

Next, when sample A and sample B are compared, sample B using a heat conductive material having a smaller median diameter has a slight shadow on the increase in thermal conductivity. Therefore, if it is desired to increase the thermal conductivity, it is considered better to omit the “pulverization” step.

Next, when Sample A and Sample C are compared, it can be seen that the thermal conductivity increases as the firing temperature at the time of producing the thermal conductive material is increased. In the case of the sample C, the thermal conductivity of approximately 0.5 [W / (m · K)] can be confirmed even if the thermal conductivity material of only 100 [phr] is contained in the base material.

Similarly, even when Sample A and Sample D are compared, it can be seen that the thermal conductivity increases as the firing temperature at the time of manufacturing the thermal conductive material is increased. In the case of the sample D, the heat conductivity of approximately 1.1 [W / (m · K)] can be confirmed even if the heat conductive material of only 150 [phr] is contained in the base material. Furthermore, surprisingly, in the case of Sample D, when a heat conductive material of 400 [phr] is contained in the base material, the heat conductivity is about 17 times the heat conductivity of the base material itself. Is obtained.

Consider the reason why such a measurement result was obtained. First, carbon itself has heat conductivity. When the materials having heat transfer properties are close to each other, a heat bridge is formed. Since the heat conductive material of this embodiment has a high carbon content, it can be said that a heat bridge is easily formed. For this reason, the heat conductive member containing the heat conductive material of the present embodiment is considered to have excellent heat conductivity.

FIG. 3 is a diagram showing measurement results for supplementing the contents of FIG. In FIG. 3, the measurement result of the sample E manufactured and measured on the same conditions as the sample D shown in FIG. 2 is shown. Here, for reference, the thermal conductivity of foamed polyethylene (PE), silicon rubber, and quartz glass is also shown as a standard sample, as in FIG.

Here, the sample E was manufactured by burning the soybean hulls of the soybean hulls in the same process as the burned material of the soybean hulls according to the sample D after one year or more than the burned material of the soybean hulls according to the sample D. is there. That is, the sample E is a heat conducting member manufactured by baking soybean hulls at a temperature of about 3000 ° C. and finely pulverizing, like the sample D. The median diameter of the heat conducting material used for this heat conducting member is about 30 μm.

The thermal conductivity was measured when Sample E was included in the base material at 100 [phr], 150 [phr], 200 [phr], 300 [phr], and 400 [phr], respectively. The thermal conductivity when Sample E was contained at 100 [phr] with respect to the base material was 0.765 [W / (m · K)]. It can be seen that this is lower than the thermal conductivity when the sample E is contained in 150 [phr] with respect to the base material.

Further, the thermal conductivity when the sample E is contained in 150 [phr] with respect to the base material is the same as the thermal conductivity when the sample D is contained in 150 [phr] with respect to the base material. 100 [W / (m · K)]. In addition, when Sample E was included in the base material at 400 [phr], the thermal conductivity was 3.770 [W / (m · K)].

From this, it was found that the heat conduction member of this embodiment has high reproducibility with respect to the heat conductivity. In addition, the burned material of soybean hulls according to sample D and the burned material of soybean hulls according to sample E had similar results not only in thermal conductivity but also in physical properties and component analysis.

Further, when the sample E is contained in the base material at 200 [phr] and 300 [phr], the thermal conductivity is 1.680 [W / (m · K)] and 2.860 [W. / (M · K)].

Further, as is apparent from FIG. 3, it was found that as a result of linearly increasing the content of the sample E with respect to the base material, the thermal conductivity also increased linearly. Therefore, it became clear that the heat conductivity can be easily controlled for the burned plant according to the present embodiment by appropriately selecting the content of the base material. In other words, it became clear that there is linearity in the increase / decrease of the content ratio of the burned plant with respect to the base material and the level of the thermal conductivity of the heat conductive member body.

Next, the thermal anisotropy of the thermal conductivity of the heat conductive member of the present embodiment, that is, the heat conductive member manufactured through the preliminary forming process described with reference to FIG. 1 will be described. Here, a heat conduction member was produced by adding about 400 [phr] of the burned soybean hulls fired at about 3000 ° C. as the heat conduction material to the ethylene / propylene diene rubber as the base material. In addition, it is not essential to set it as this baking temperature, What is necessary is just to satisfy | fill the requirement of graphitization, for example.

A square planar heat conducting member having a thickness of about 10 mm is manufactured, a cube of about 10 mm square in the diagonal portion is cut out, and the X direction of each cube-shaped sample on the measurement surface using Emery paper No. 1500 and No. 2000 Three samples, Y direction and Z direction, were smoothed to the same extent to obtain two samples.

Next, the thermal conductivity was measured by repeating point contact with the probe of the thermophysical tester in the three directions described above.

The composition of the thermophysical tester and the outline of the measurement of thermal conductivity using it are published in “Seikei-Lakou Vol.21 No.10 2009 P595-599” which is incorporated herein by reference. Has been.

As a result of measuring the thermal conductivity, the minimum value of both samples was 9.610 [W / (m · K)] and the maximum value was 12.82 [W / (m · K)]. On the other hand, paying attention to the X direction, Y direction, and Z direction of each sample, the average of each measured value is 11.21 [W / (m · K)] in the X direction of sample 1, 11.07 [W / (m · K)] in the Y direction, 10.50 [W / (m · K)] in the Z direction of Sample 1, and X in the X direction of Sample 2 11.25 [W / (m · K)], 11.56 [W / (m · K)] in the case of the Y direction of the sample 2, and 10.39 [W / in the case of the Z direction of the sample 2 (M · K)].

Investigating the dispersion in statistics, the samples 1 in each direction were 1.010, 0.540, and 0.324. Similarly, the thing of each direction of the sample 2 was 0.569, 1.300, 0.372.

It should be noted that, using the above-mentioned thermophysical property tester, the heat of POCO-AXM-5Q1 graphite having no thermal anisotropy used as a standard sample in the National Institute of Standards (NIST), etc. When the measured conductivity value was measured, the minimum value was 14.90 [W / (m · K)], the maximum value was 16.40 [W / (m · K)], and the average value was 15.10 [W / (M · K)], and the measured thermal conductivity of the base material itself was 0.211 [W / (m · K)].

Considering the measurement result of the standard sample, it can be evaluated that there is no thermal anisotropy when attention is paid to the heat conducting member itself of the present embodiment. This is because the heat conduction member of the present embodiment is manufactured through the preliminary forming step described with reference to FIG. 1, and the burned soybean hulls having no shape specificity are dispersed in the base material. It means that it can be regarded as homogeneous on a macroscopic scale. Moreover, since the measured value shows a substantially constant value regardless of the location where the effective thermal conductivity is measured, the heat conducting member of the present embodiment means that it can be regarded as being thermally homogeneous.

Generally speaking, the heat conducting member has a low heat conductivity when the measured value of the thermal conductivity is 0.500 [W / (m · K)] to 2.000 [W / (m · K)]. If the conduction class is about 3.000 [W / (m · K)], the intermediate heat conduction class is 4.000 [W / (m · K)] to 5.000 [W / (m · K)]. If so, it is said to belong to the high thermal conductivity class. Therefore, it can be said that the heat conducting member of the present embodiment has no thermal anisotropy and can belong to a class exceeding the high heat conducting class.

4 to 9 are SEM photographs of the X, Y, and Z cross sections of the heat conducting member manufactured through the pre-forming process described with reference to FIG. These SEM photographs were taken using a scanning analytical electron microscope (JSM-5610LV) manufactured by JEOL. The shooting conditions were an acceleration voltage of 15 kV and a magnification of 200 times or 1000 times.

The heat conducting member to be measured is cut with a sharp blade and then immersed in an osmium tetroxide solution having a concentration of about 2% at a temperature of about 4 ° C. for photography. After washing, vacuum drying was performed at a temperature of about 40 ° C. for about 2 hours.

4 to 6 show SEM photographs taken in the X, Y, and Z directions taken at 200 times magnification. In each figure, a relatively dark portion is a heat conductive material, and a relatively bright portion is a base material. As shown in each figure, the heat conducting material has a cross-sectional length on the order of several μm to 100 μm, with some difference in size, and is uniform in any of the cross sections in the X, Y, and Z directions. It can be seen that they are dispersed.

7 to 9 show SEM photographs taken in the X, Y and Z directions taken at a magnification of 1000 times. In each figure, a relatively dark portion is a heat conductive material, and a relatively bright portion is a base material. As shown in each figure, it can be seen that the heat conducting material has a very large number of voids. In other words, it can be seen that the heat conductive material has a characteristic of a porous structure.

Here, in general, in the case of a porous structure, it is considered that the heat conduction efficiency is not good because the presence of the void portion acts adiabatically. However, actually, the heat conducting material of this embodiment has high heat conduction efficiency. This is because the heat conductive material of the present embodiment is made of carbon, which is a heat conductive material, so that the entire periphery of the gap portion is made of carbon, so that the heat conduction path may be extended for a long time. As described above, it is presumed that the heat conduction material grains that occupy a wide range per unit weight favor the heat propagation in the case of the heat conduction member. Therefore, the size of the heat conduction material is also considered to be an important factor when considering the heat conduction efficiency.

4 to 9, it can be said that the heat conducting member of the present embodiment has a porous heat conducting material uniformly dispersed three-dimensionally.

10 to 14 are SEM photographs of the burned plant. Note that the SEM photographs shown in FIGS. 10 to 14 are also manufactured through the preliminary forming process described with reference to FIG.

These SEM photographs were taken using a scanning analytical electron microscope (JSMOL JSM-5410LV) manufactured by JEOL. The shooting conditions were an acceleration voltage of 15 kV and a magnification of 1000 times or 1500 times.

The SEM photographs shown in FIGS. 10 and 11 are magnified photographs at 1000 magnifications of the fired product of the Palm Fruits） Bunch, which are fired at about 900 ° C. and about 3000 ° C., respectively. Palm palm empty fruit bunch refers to the processed residue left after peeling the fruit of palm from the palm palm bunch.

When both photographs are compared, they are mesh-like and have a bag-like shape. On the other hand, when baked at about 3000 ° C. compared to baked at about 900 ° C., other than carbon. The difference is that the substance appears to have become smaller and denser due to volatilization. Note that the fired product shown in FIG. 10 has not been subjected to the graphitization described above.

The SEM photographs shown in FIGS. 12 and 13 are magnified photographs at 1000 magnifications of a fired product of palm coconut shell, and are fired at about 900 ° C. and about 3000 ° C., respectively. Palm coconut shell is a shell after squeezing nuclear oil from seeds of palm fruit, and refers to an outer shell of fruit seed.

First, comparing the two photos, it is common in that it can be evaluated that there are a plurality of voids, and there seems to be no particular difference. Note that the fired product shown in FIG. 12 has not been subjected to the graphitization described above.

Moreover, when the SEM photographs shown in FIGS. 12 and 13 are compared with the SEM photographs shown in FIGS. 10 and 11, it cannot be confirmed from the SEM photographs such as FIG. The change in size cannot be confirmed.

The SEM photograph shown in FIG. 14 is an enlarged photograph of the cacao husk fired product at a magnification of 1500, and is fired at about 3000 ° C. here. According to FIG. 14, the presence of a spiral portion can be confirmed (substantially in the center of the photograph), and the presence of some nodes can also be confirmed (right of the photograph). When the SEM photograph shown in FIG. 14 is compared with the SEM photograph shown in FIG. 12 or the like, it can be seen that the shape is greatly different (note that the SEM photograph shown in FIG. 12 is taken at a different magnification). Wanna)

FIG. 15 is an SEM photograph of a fired product of the coconut shell shown as a comparative example and having a different manufacturing process described later. According to FIG. 15, although some dents can be confirmed on the surface, it cannot be evaluated that there are many voids.

In summary, according to the SEM photographs shown in FIGS. 10 to 14, these heat conductive materials have a porous structure as in the heat conductive material included in the heat conductive member shown in FIG. Common in that there is. On the other hand, it is difficult to say that the structure shown in FIG. 15 has a porous structure when viewed relatively.

Next, in order to verify whether or not the heat conductive material of the present embodiment is uniformly dispersed with respect to the base material, various electrical characteristics were examined instead of observation by SEM photographs. FIGS. 16 to 19 to be described below show various electrical characteristics of the heat conducting member including a fired product obtained by firing soybean hulls and the like at about 900 ° C., and FIGS. It shows various electrical characteristics of a heat conducting member including a fired product obtained by firing a skin or the like at about 3000 ° C.

16 (a) to 16 (d), FIG. 16 (a) is soybean hulls, FIG. 16 (b) is cacao husk, FIG. 16 (c) is palm palm empty fruit bunch, and FIG. 16 (d) is palm palm. It is a figure which shows the volume resistivity measured at the arbitrary 9 points | pieces of the heat conductive member containing each baked material obtained by baking a shell at about 900 degreeC, respectively. Here, some measurement results are shown in which the content rate [phr] of the burned material such as soybean hulls with respect to the base material is changed.

In FIGS. 17 to 23, which will be described later, (a) to (d) are the same as in FIG. 16, FIG. 17 (a) is soybean hull, FIG. 17 (b) is cacao husk, FIG. 17 (c) Etc. show the measurement results of palm palm empty fruit bunch, and FIG.

In all cases, the median diameter of the burned material such as soybean hulls is about 30 μm, the thickness of the mixture of the burned material such as soybean hulls and the base material is 2.5 [mm], and each material is about 900 ° C. Baked.

When comparing FIG. 16 (a) to FIG. 16 (d), it can be said that there are some waves of measured values depending on the material and the content rate, but in general, at any nine points of the same content rate. It can be seen that the measured values of the volume resistivity are almost the same. This means that the heat conductive member of this embodiment is uniformly dispersed with respect to the base material regardless of the presence or absence of graphitization treatment.

In addition, it turns out that a volume specific resistivity falls as the content rate of the heat conductive material with respect to a base material increases. Moreover, in any material, the volume resistivity is common in the vicinity of 1 × 10 ¹² [Ω · cm] at the content of 100 [phr], and the volume resistivity at the content of 300 [phr] and 400 [phr]. The ratio is common in the vicinity of 1 × 10 ¹ to 10 ² [Ω · cm], but it can also be seen that the specific volume resistivity varies depending on the material at 150 [phr] and 200 [phr].

FIG. 17 (a) to FIG. 17 (d) are diagrams showing surface resistivity measured at nine arbitrary points of a heat conducting member including a burned material such as soybean hulls obtained by baking at about 900 ° C. is there. The evaluation according to FIGS. 17A to 17D is the same as that for FIGS. 16A to 16D, and in the heat conducting member of this embodiment, the heat conducting material is compared to the base material. Thus, it can be seen that the particles are uniformly dispersed regardless of the presence or absence of graphitization.

The measurement results shown in FIGS. 17 (a) to 17 (d) show the measured values depending on the material and the content rate as compared with those shown in FIGS. 16 (a) to 16 (d). Although it can be said that the waves look somewhat rough, both the above-mentioned volume resistivity and the surface resistivity shown here apply a high voltage of several hundred volts to the heat conducting member at the time of measurement. Rather than being difficult to disperse uniformly, it is possible that a very large amount of heat-conducting material is contained in the base material and that the slight difference in the thickness of the heat-conducting member greatly affects the measured value. On the contrary, it can be evaluated that the measurement error only appears greatly.

In addition, since the surface resistivity of a single rubber, which is a base material, is generally very high, 1 × 10 ¹⁵ to 10 ¹⁶ [Ω · cm], if a heat conductive material is contained in the base material even a little, The surface resistivity decreases. Furthermore, since the difference differs greatly depending on the content of the heat conductive material with respect to the base material, if the heat conductive material is not uniformly distributed with respect to the base material, the surface at any nine points It can be said that the measured resistivity value should fluctuate. It can be said that the measurement results shown in FIGS. 17A to 17D are within an error range as long as they do not indicate the measured values that are disturbed.

FIGS. 18 (a) to 18 (d) are diagrams showing the measurement results of the electromagnetic wave shielding amount of the heat conducting member containing the burned material such as soybean hulls obtained by baking at about 900 ° C., respectively. As a whole, the measurement results shown in FIGS. 18A to 18D are excellent in electromagnetic wave shielding characteristics at any frequency of 300 [MHz] or less, particularly 200 [MHz] or less. In addition, it can be seen that the electromagnetic shielding properties are more excellent as the content [phr] of the heat conductive material with respect to the base material increases.

In particular, it is surprising that the palm palm empty fruit bunch fired product and the palm coconut shell fired product have realized a content of 500 [phr] with respect to the base material. On the other hand, it can be said that the heat conducting material is bonded to each other by a binder called a base material, rather than containing the heat conducting material.

The peak of the electromagnetic wave shielding amount is about 30 [dB], and the electromagnetic wave shielding amount as much as the heat conductive material obtained by firing at about 3000 ° C., which will be described later, was not obtained, but still 25 [dB]. The electromagnetic shielding amount exceeding can be confirmed. It can also be seen that the higher the content of the heat conductive material relative to the base material, the better the electromagnetic shielding properties.

FIGS. 19 (a) to 19 (d) are diagrams showing electromagnetic wave absorption characteristics of a heat conducting member including a fired product such as soybean hulls obtained by firing at about 900 ° C., respectively. In FIG. 19 (a) to FIG. 19 (d), the horizontal axis represents frequency [MHz], and the vertical axis represents electromagnetic wave absorption [dB].

First, looking at FIG. 19 (a) to FIG. 19 (d), in the frequency band of 2 [GHz] to 6 [GHz], 300% of the base material is obtained in the case of any baked product of plants. It can be said that there are effective frequency absorption characteristics when [phr] to 400 [phr] is contained. As a result, it was found that the frequency band where the electromagnetic wave absorption amount is maximum is around 4 [GHz] to 6 [GHz].

20 (a) to 20 (d) are diagrams showing the volume resistivity of the heat conducting member containing the burned material such as soybean hulls obtained by baking at about 3000 ° C., and FIG. This corresponds to FIG.

When comparing FIG. 20 (a) to FIG. 20 (d), although there are some waves of measurement values depending on the material and content, the volume resistivity at any nine points of the same content is generally obtained. It can be seen that the measured values are almost the same. This means that the heat conducting member of this embodiment is uniformly dispersed with respect to the base material regardless of the firing temperature of the heat conducting material.

Note that the volume resistivity decreases as the content of the heat conductive material increases. It can also be seen that the specific volume resistivity at 150 [phr] and 200 [phr] varies depending on the member.

FIG. 21 (a) to FIG. 21 (d) are diagrams showing the surface resistivity of the heat conducting member containing a fired product such as soybean hulls obtained by firing at about 3000 ° C., respectively. The evaluation according to FIGS. 21 (a) to 21 (d) is the same as that for FIGS. 20 (a) to 20 (d). In the heat conducting member of this embodiment, the heat conducting material is compared with the base material. It can be seen that they are uniformly distributed.

22 (a) to 22 (d) are diagrams corresponding to the measurement results of the electromagnetic wave shielding amount of the heat conducting member including the burned material such as soybean hulls obtained by baking at about 3000 ° C. FIG. The measurement results shown in FIGS. 22 (a) to 22 (d) are improved in the electromagnetic wave shielding amount as compared with the measurement results of the electromagnetic wave shielding amounts shown in FIGS. 18 (a) to 18 (d). I understand that.

Moreover, when paying attention to palm palm empty fruit bunches and palm coconut shells, in either case of FIG. 22 (c) and FIG. 22 (d), in the case of 100 [phr], 150 [phr], and 400 [phr], It can be seen that the electromagnetic shielding amount remains high up to the high frequency band. In particular, in the case of 400 [phr], since it exceeds 25 [dB] to approximately 1000 [MHz], it also functions as a stable electromagnetic wave shield.

FIG. 23 (a) to FIG. 23 (d) are diagrams showing electromagnetic wave absorption characteristics of a heat conducting member including a burned material such as soybean hulls obtained by baking at about 3000 ° C., respectively. Looking at FIGS. 23 (a) to 23 (d), in the frequency band of 2 [GHz] to 6 [GHz], 200 [phr] with respect to the base material in the case of the burned material of any plant. ] Can be said to have effective frequency absorption characteristics. As a result, it was found that the frequency at which the electromagnetic wave absorption amount is maximum is in the vicinity of 4 [GHz] to 6 [GHz].

FIG. 23 (a) to FIG. 23 (d) and FIG. 19 (a) to FIG. 19 (d) are compared with each other when electromagnetic waves are absorbed in a frequency band of 4 [GHz] to 6 [GHz]. Has the advantage that only a small amount of the heat conductive material fired at about 3000 ° C. may be used.

Next, as a comparative example, a coconut shell fired product was manufactured by changing the following points from the manufacturing process shown in FIG. The changes here are that the raw coconut shell is finely pulverized, and the raw coconut shell is mixed with alkali metals such as potassium carbonate and alkaline earth metals such as calcium hydroxide. However, other conditions such as the firing temperature are as described with reference to FIG.

In addition, the comparative example shown in FIG. 2 is a material in which the heat-conducting material and the firing temperature thereof are different, but the comparative example here differs in the manufacturing process of the heat-conducting material. It is a thing.

In this comparative example, the volume resistivity and the surface resistivity measured at arbitrary nine points as shown in FIG. 16A, FIG. 17A, etc. were measured. Was found to be uniformly distributed.

However, in the first place, this comparative example is difficult in terms of electromagnetic wave shielding characteristics. Specifically, even when the content is 100 [phr] to 400 [phr] with respect to the base material, 1 [ The frequency band below [GHz] did not exceed 10 [dB].

FIG. 24 is a diagram showing the measurement results of the thermal conductivity of the heat conducting member including the heat conducting material shown in FIG. 10 and the like. FIG. 24 also shows the measurement results of the thermal conductivity when a predetermined amount of the coconut shell fired product with different manufacturing processes is contained in the base material as a comparative example of various samples described below.

Sample EB1 is a heat conduction material manufactured without firing palm palm empty fruit bunch at a temperature of about 900 ° C. and finely pulverizing. The median diameter of this heat conducting material is about 33 μm. When the sample EB1 is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.340 [W / (m · K)], It was 0.462 [W / (m · K)], 0.629 [W / (m · K)].

Sample PS1 is a heat conductive material manufactured by firing palm coconut shells at a temperature of about 900 ° C. and without pulverizing them. The median diameter of the heat conducting material used for this heat conducting member is about 26 μm. When the sample PS1 is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.352 [W / (m · K)], They were 0.478 [W / (m · K)] and 0.654 [W / (m · K)].

Sample CA2 is a heat conduction material manufactured without firing and pulverizing cacao husk at a temperature of about 3000 ° C. The median diameter of this heat conducting material is about 25 μm. When the sample CA2 is contained in the base material at 100 [phr], 200 [phr], and 300 [phr], respectively, the thermal conductivity is 0.799 [W / (m · K)], It was 1.570 [W / (m · K)], 3.760 [W / (m · K)].

Sample EB2 is a heat conductive material manufactured without firing palm palm empty fruit bunch at a temperature of about 3000 ° C. and finely pulverizing. The median diameter of this heat conducting material is about 23 μm. When the sample EB2 is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.720 [W / (m · K)], It was 1.580 [W / (m · K)], 3.610 [W / (m · K)].

Sample PS2 is a heat conductive material manufactured by calcining palm coconut shells at a temperature of about 3000 ° C. without fine pulverization. The median diameter of this heat conducting material is about 32 μm. When the sample PS2 is contained in the base material at 100 [phr], 200 [phr], and 400 [phr], respectively, the thermal conductivity is 0.720 [W / (m · K)], It was 1.790 [W / (m · K)] and 3.780 [W / (m · K)].

The thermal conductivity when the comparative example is 100 [phr], 200 [phr], and 400 [phr] with respect to the base material is 0.276 [W / (m · K)], respectively. They were 0.321 [W / (m · K)] and 0.376 [W / (m · K)].

The content shown in FIG. 24 is consistent with that shown in FIG. 2, and as the content of the heat conductive material with respect to the base material increases and the firing temperature is higher than the relatively low temperature. It can be seen that the thermal conductivity also increases.

As described above, the heat conducting member of the present embodiment has an electromagnetic shielding effect or an electromagnetic wave absorbing effect that is difficult to obtain with the heat conducting member manufactured from the comparative example as well as having excellent heat conducting characteristics.

Specifically, since the heat conducting member of the present embodiment has an electromagnetic wave absorption effect, it can be suitably used for a cover (for example, a battery pack cover or an under cover) that covers an electromagnetic wave generation source in an electric vehicle. . Excellent heat conduction characteristics and electromagnetic wave absorption effect as well as the effect of reducing the irregular reflection of electromagnetic waves in the cover compared to metal materials. It becomes possible to prevent.

Moreover, since the heat conducting member of this embodiment is not a heat conducting member manufactured from a metal material, it also has an advantage of being lightweight. For this reason, the heat conductive member of this embodiment can be used suitably also in the product which attaches importance to weight reduction, such as a portable electronic device, for example.

Claims

A heat conducting member that is preformed according to the shape of the heat conducting member main body at the time of manufacture, and contains a plant baked product that is uniformly dispersed in the base material.
The heat conduction member according to claim 1, wherein at least one of a content ratio of the burned plant product with respect to the base material and a firing temperature of the burned plant product is controlled.
The burned plant product is a burned product of any one of soybean hulls, rapeseed meal, sesame meal, cottonseed meal, cotton hull, soybean hulls, soybean hulls, cacao husk, palm coconut empty fruit bunch, and palm coconut shells. The heat conduction member as described.
The heat conducting member according to claim 1, wherein the base material is one of rubber, resin, paint, and cement.
A heat-conducting material containing a plant fired product contained in the heat-conducting member according to claim 1.