JPH0240026B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention generally relates to carbon materials and products obtained from them, and particularly relates to large carbon products manufactured by joining carbon materials together and a method for manufacturing the same.
More specifically, it consists of a carbon material and a flexible graphite sheet between the carbon materials. A carbon product and its manufacturing method, characterized in that there is a partially non-bonded surface in an arbitrary shape and uniformly distributed, and the graphite sheet portion corresponding to the non-bonded surface is removed or not removed. Pertains to. In the carbon product of the present invention, a partial non-bonding surface is formed in an arbitrary shape and uniformly distributed on the bonding surface of the carbon material with the flexible graphite sheet,
This prevents stress from concentrating on the joint surface. By doing this, a large product can be made, and since it is integrated in a carbonized state, the electrical and thermal resistance is low and the strength is high. Therefore, there are a wide range of fields in which these characteristics can be utilized. [Conventional technology] In recent years, carbonaceous molded products based on carbonaceous materials such as carbon fibers and carbon particles have been used in various industrial fields, and as technology advances and demand increases, More and more advanced requirements such as improvements in productivity, productivity, and physical properties are increasing. Carbon materials have physical properties as materials, such as contact resistance,
Carbonaceous composite materials are excellent in conductivity, strength, etc., but in order to make more effective use of these excellent physical properties, carbonaceous composite materials are being developed in which carbon materials of the same or different types are combined and bonded together. Such carbonaceous composite materials have conventionally been used as carbon products simply pasted together using adhesives, but there have been problems with chemical resistance, electrical conductivity, dimensional stability, etc. In recent years, a method has been devised to solve the above-mentioned problems by bonding carbon materials together using an adhesive and firing them. However, when such a manufacturing method is used, the carbon materials may peel off at their adhesive surfaces due to the difference in expansion and contraction rates between the carbon materials during the firing process.
This often causes cracks in the product, resulting in a decrease in production yield. Furthermore, the demand for relatively large and/or complex-shaped carbon products from a structural and functional point of view has also increased in recent years;
In such a case, the above-mentioned problems such as peeling and cracking become particularly serious in the production process. In this way, with carbonaceous composite materials, the carbonaceous materials do not peel off from each other during manufacturing, the product does not crack, etc., and at the same time, the final product has excellent properties inherent to the carbon material itself, such as mechanical properties. Strict requirements are imposed on them to maintain strength, electrical properties, etc., and their manufacture is extremely difficult. [Problem to be solved by the invention] In view of the above-mentioned circumstances, the inventors of the present invention have repeatedly researched methods for joining carbon materials to produce carbonaceous composite materials, and as a result, they have found that a flexible graphite sheet is bonded between carbon materials. It was discovered that when the graphite sheet is interposed in the carbon material, it acts as a buffer layer for the difference in expansion and contraction of each carbon material during firing, making it possible to produce a carbonaceous composite material with desirable properties with high productivity.After that, further research was carried out. As a result, if partial non-bonded surfaces in any shape and uniformly distributed are provided on the bonding surface between the carbon material and the flexible graphite sheet, the stress at the bonded surface will be dispersed and the whole will be fired. We have discovered that it is possible to produce large-scale carbonaceous composite products with good yield, and have completed the present invention. That is, an object of the present invention is to provide a large-sized carbonaceous composite material that has excellent properties and is free from warping, peeling, and cracking. A further object of the present invention is to provide a method for producing a large-sized carbonaceous composite material that does not exhibit the drawbacks of the prior art described above, particularly without warping, peeling, cracking, etc. [Means for Solving the Problems] The above-mentioned object of the present invention is to interpose a flexible graphite sheet between carbon materials, to join the carbon material and the graphite sheet, and to bond at least one of the carbon materials. 20 to 80%, preferably 30 to 70%, of the bonded surfaces of the materials are provided with partial non-bonded surfaces of any shape and uniformly distributed, and then fired at a temperature of at least 800°C or higher to form carbon. This is achieved by the characteristics of the carbon product according to the present invention and its manufacturing method. The flexible graphite sheet used in the present invention has a particle size of 5
It is made by compressing expanded graphite particles obtained by acid-treating graphite particles of 1 mm or less and ^then heating them. In other words, the strain rate for a compressed weight of 1Kg/ ^cm2 ) is
It is 10 ^-4 cm ² /Kg or more, preferably 10 ^-3 cm ² /Kg or more, and among commercially available products, Graffoil manufactured by UCC is a suitable example. Further, the portion of the flexible graphite sheet corresponding to the non-bonding surface of the carbon material may be removed. The carbon materials to be joined according to the present invention may be materials of the same quality or materials of different quality in terms of physical properties. Examples of raw carbon materials for carbon products used in the present invention include the following, but are not limited thereto. A shaped carbon material consisting of a carbon aggregate selected from carbon fibers, carbon particles, and oxidized pitch particles and a binder. Various binders can be used, such as one type or a combination of two or more types selected from phenolic resins, furan resins, epoxy resins, petroleum-based pitches, and coal-based pitches. Molded from carbon aggregate and binder selected from carbon fibers, carbon particles, and oxidized pitch particles,
Furthermore, carbon material fired at 800℃ or higher. Various binders can be used, such as phenolic resin,
One type or a combination of two or more types selected from furan resin, epoxy resin, petroleum-based pitch, or coal-based pitch is used. A shaped carbon material comprising an aggregate of graphite particles and/or easily graphitizable carbon particles and a binder such as coal-based pitch, phenolic resin, furan resin, epoxy resin, petroleum-based pitch. A carbon material made by firing carbon material at a temperature of 800℃ or higher. In the present invention, any combination of these carbon materials is used as the raw carbon material. If the difference in linear expansion and contraction rates between the two carbon materials used during firing is too large, no bonding will occur even if a flexible graphite sheet is used and partially unbonded parts are placed on at least one side. There is a range that cannot be worn. At least the absolute value of the difference in linear expansion/contraction rate during firing between the two carbon materials used for joining is determined by the thickness of the flexible graphite sheet used, the strain rate, the maximum firing temperature, and the joint surface of the partially unjoined part. In this case, it is of course influenced by the size of the carbon product (size of the bonding surface), but it is necessary that it be at least 3% or less, preferably 1% or less. In the present invention, partial non-bonding surfaces in an arbitrary shape and uniformly distributed are provided at the portion of the raw carbon material that corresponds to the bonding surface with the flexible graphite sheet. Although the shape and arrangement of such partially non-bonded surfaces are arbitrary, it is desirable to arrange them evenly as a whole in order to prevent warping, peeling, cracking, etc. Furthermore, at least one of the bonding surfaces is provided with a non-bonding surface. The proportion of such partially unbonded surfaces is usually 1
A value that provides the desired effect may be selected from a range of 20 to 80%, preferably 30 to 70% per joint surface. If the proportion of partially non-bonded surfaces is too large, the proportion of bonded surfaces will naturally decrease, making peeling, cracking, etc. more likely to occur during firing. On the other hand, if the proportion of partially non-bonded surfaces is too small, the effect of stress dispersion on the bonded surfaces will be lost. By providing a partially non-bonded surface on at least one side according to the present invention, stress is alleviated not only at the bonded surface between that surface and the flexible graphite sheet, but also at the bonded surface between the other carbon material and the flexible graphite sheet. This results in a carbon product that is free from warping, peeling, and cracking even without providing a partially non-bonded surface on the other side. For example, one bonding surface may be fully bonded, and only the other bonding surface may be provided with a partial non-bonding surface.
Alternatively, a partial non-bonding surface may be provided at any position on both bonding surfaces. Furthermore, the flexible graphite sheet can also be provided with a partial non-bonding surface corresponding to the partial non-bonding surface of these carbon materials. In this case as well, the partially non-bonded surface of the carbon material may be provided on only one bonded surface or both bonded surfaces. That is, the graphite sheet portion corresponding to the non-bonding surface of the carbon material may be deleted. In the present invention, in the case of a molded carbon material, the binder used in the adhesive used to bond the carbon material and the flexible graphite sheet may also serve as the adhesive, but usually Use a separate adhesive. The adhesive may be an ordinary adhesive used for bonding carbon materials, but in particular, 5 to 200 parts by weight of phenolic resin, pitch, etc. to 100 parts by weight of a suitable solvent such as methanol, ethanol, acetone, and methyl ethyl ketone. dissolved,
Alternatively, it is preferable to use one selected from dissolved phenolic resins, epoxy resins, furan resins, etc.; In order to uniformly disperse the dots, it is more preferable to use one prepared by mixing 0 to 100 parts by weight of carbon particles with a diameter of 200 μm or less in 100 parts by weight of the adhesive. Although the thickness of this adhesive layer is not particularly limited, it is generally preferable to apply it uniformly to a thickness of 0.5 mm or less. Furthermore, the bonding of the carbon agent and graphite sheet using the adhesive is carried out at a temperature at least 50°C higher than the melting point of the binding material used as the adhesive, and at a press pressure of 0.1 to
It can be carried out within the range of 50Kg/ ^cm2 . To manufacture the carbon product of the present invention, the adhesive is applied to the surface of the carbon material having the partially non-bonded surface (or to the surface when the surface not having the partially non-bonded surface is to be bonded). The flexible graphite sheet is placed on top of the flexible graphite sheet, and the carbon material coated with the adhesive on one side is placed so that the adhesive-coated side faces the sheet, and then the above conditions are applied. The pieces are joined together under heat and pressure, and finally the whole is fired. At this time, a flexible graphite sheet is manufactured in situ by placing expanded graphite particles uniformly on the adhesive-coated surface of the carbon material and molding the expanded graphite particles under heat and pressure under the conditions described above. Can be done. This molded product can be taken out or left as is and joined to other adhesive-coated carbon materials as described above. At this time, the initial bonding surface of the carbon material is made flat. [Operations and Effects of the Invention] The carbon product obtained by the present invention exhibits the excellent characteristics inherent to carbon materials, and as is clear from the Examples and Comparative Examples described later, there is no possibility of intervening carbon materials between the carbon materials. The flexible graphite sheet acts as a buffer for thermal expansion or contraction between the carbon materials during heat treatment, and furthermore, the partial non-bonded surfaces of any shape and uniformly distributed on the bonded surfaces of the carbon materials reduce stress. Since concentration is prevented and dispersed, there is no peeling of raw carbon materials at the bonding surface during production, and there are no cracks in the product, making it possible to produce at a good production yield. . Such effects of the present invention are particularly obvious when compared with the case of bonding using only adhesive. In addition, in order to have the above-mentioned effects, the manufacturing method of the present invention can peel and peel large products and products with complicated shapes.
It can be manufactured without causing problems such as cracks and warping. [Examples] The present invention will now be explained in more detail by way of non-limiting examples. Example 1 A plate (150mm□×20mmt) of various carbon materials was created,
Table 1 shows the results of sintering at 2000°C after bonding with an adhesive using graph oil. Table 1
shows the number of sheets with good bonding properties after conducting an experiment of 10 sheets for each combination. Bonding was carried out by the method shown in FIGS. 1 and 2, in which 150 mm x 20 mm t surfaces and 150 mm x 150 mm surfaces were bonded together in order to see the bonded state of each bonded surface. The carbon material, flexible graphite sheet, adhesive, and bonding conditions used here are as follows. (1) Carbon material Carbon material-1 Short carbon fiber (manufactured by Kureha Chemical Industry Co., Ltd., product name M
-204S, average diameter 14μm, average length 400μm)
60wt%, phenolic resin (manufactured by Asahi Yukizai Co., Ltd.,
After mixing 40wt% (product name RM-210, resol type), supply it to the specified mold, molding temperature 130℃,
Carbon material molded under conditions of molding pressure of 50 kg/cm ² and pressure holding time of 20 minutes. Carbon material-2 Short carbon fiber (manufactured by Kureha Chemical Industry Co., Ltd., product name M
-204S, average diameter 14μm, average length 400μm)
and phenolic resin (manufactured by Asahi Yukizai Co., Ltd., product name)
RM-210, resol type) and 60wt%: 40wt
After mixing at a weight ratio of %, supply it to the specified mold,
The product was molded at a molding temperature of 130°C, a molding pressure of 50 kg/cm ² , and a pressure holding time of 20 minutes, and then heated to 2000°C at 50°C/hour in a nitrogen gas atmosphere using an electric furnace.
The carbon material was heated to a temperature of 100% and fired at that temperature for 60 minutes. Carbon material-3 Pitch oxide particles (manufactured by Kureha Chemical Industry Co., Ltd., trade name MH-P, average particle diameter 5 μm) were pre-calcined at 850°C in a nitrogen gas atmosphere, and phenol resin (Asahi Yokuzai) Co., Ltd., RM-210)
After mixing at a weight ratio of 65wt%:35wt%, it was supplied to a specified mold, and the molding temperature was 140℃ and the molding pressure was
Molding was performed under conditions of 100Kg/cm ² and pressure holding time of 30 minutes, and then molded under nitrogen gas atmosphere using an electric furnace for 50 minutes.
Carbon material heated to 2000℃/hour and fired at that temperature for 60 minutes. Carbon material-4 Commercially available graphite material (manufactured by Toyo Carbon Co., Ltd., product name A
−280, bulk density 1.7 g/cm ³ ). Of the two carbon materials used for joining,
A concave portion corresponding to 50% of the area of one carbon material was formed by molding or machining, and the concave portion was used as a partially non-bonding surface. (2) Flexible graphite sheet Commercially available flexible graphite sheet (made by UCC, Graphoil, 0.25 mm thick, bulk density 1.2 g/cm ³ , compressive strain rate 1×10 ^-3 cm ² /Kg). (3) Adhesive 100 parts by weight of methyl ethyl ketone and 80 parts by weight of phenol resin (RM-210, manufactured by Asahi Yokuzai Co., Ltd.) were dissolved at room temperature. (4) Bonding conditions After applying the adhesive to each bonding surface of the carbon materials to be bonded, the bonding temperature was 130℃, and the bonding pressure was 5Kg/
cm ² and bonding pressure was maintained for 30 minutes. (5) Firing After bonding, the temperature is raised to 2000℃ at 50℃/hour in a nitrogen gas atmosphere using an electric furnace.
Bake for a minute.

[Table] Means those that do not cause any slack.
From the results in Table 1, it can be seen that under these bonding conditions, carbon materials can be bonded together by interposing a flexible graphite sheet and by providing a partial non-bonding surface on the bonding surface of the carbon materials. It became clear that the state could be obtained. Comparative Example 1 Table 2 shows the results of bonding and firing using the same adhesive as in Example 1 without using graph oil. The carbon materials used and the bonding conditions were the same as those shown in Example 1.

[Table] Good bonding was achieved mainly when carbon materials were relatively homogeneous; however, in other cases, there were generally many defects and high quality carbon materials could not be obtained. Example 2 Carbon materials of various sizes were bonded with an adhesive using graph oil, and then fired at 2000°C. Table 3 shows the results. In this example, the first
The bonding method shown in FIG. 2 was used. The carbon materials, flexible graphite sheets, adhesives and bonding conditions used here are as follows:
The following were used. However, the repeated experiment was conducted with 10 sheets of each combination as in Example 1. (1) Carbon material Carbonaceous material Short carbon fiber (manufactured by Kureha Chemical Industry Co., Ltd., product name M
-204S, average diameter 14μm, average length 400μm)
and phenolic resin (manufactured by Asahi Yukizai Co., Ltd., product name)
RM-210, resol type) and 70wt%: 30wt
After mixing at a weight ratio of %, supply it to the specified mold,
Molded at a molding temperature of 130°C, a molding pressure of 50 kg/cm ² , and a pressure holding time of 20 minutes. Carbon material Pitch oxide particles (manufactured by Kureha Kagaku Kogyo Co., Ltd., trade name MH-P, average particle diameter 5 μm) pre-calcined at 850°C in a nitrogen gas atmosphere and phenolic resin (manufactured by Asahi Yokuzai Co., Ltd.) manufactured by RM-210)
After mixing at a weight ratio of 65wt%:35wt%, it was supplied to a specified mold, and the molding temperature was 140℃ and the molding pressure was
Molding was performed under conditions of 100Kg/cm ² and pressure holding time of 30 minutes, and then molded under nitrogen gas atmosphere using an electric furnace for 50 minutes.
The temperature was raised to 2000℃ per hour and fired at that temperature for 60 minutes. Graphite material Commercially available graphite material (Toyo Carbon Co., Ltd., product name A-
280, bulk density 1.7 g/cm ³ ). Incidentally, a concave portion was formed on the surface of one of the two carbon materials used for these bonding by molding or machining, and that portion was used as a partially non-bonded surface. (2) Flexible graphite sheet Commercially available flexible graphite sheet (made by UCC, Graphoil, 0.25 mm thick, bulk density 1.2 g/cm ³ , compressive strain rate 1×10 ^-3 cm ² /Kg). (3) Adhesive 100 parts by weight of methyl ethyl ketone and 80 parts by weight of phenol resin (RM-210, manufactured by Asahi Yokuzai Co., Ltd.) were dissolved at room temperature. (4) Bonding conditions After applying the adhesive to each bonding surface of the carbon materials to be bonded, the bonding temperature was 130℃, and the bonding pressure was 5Kg/
cm ² and bonding pressure was maintained for 30 minutes.

[Table] Comparative Example 2 Table 4 shows the results of carbon materials of various sizes being bonded with adhesive using graph oil and then fired at 2000°C. In this comparative example, the first
The bonding method shown in FIG. 2 was used. The carbon materials, flexible graphite sheets, adhesives, bonding conditions, and number of repeated experiments used here were the same as in Example 2, but the shapes of the bonded surfaces of the carbon materials were all flat, with some non-bonded surfaces. does not have.

[Table] For the carbon composite material of Comparative Example 1, in which an almost good bonding state could not be obtained by the conventional full-surface bonding method without intervening a flexible graphite sheet, we decided to interpose a flexible graphite sheet. Therefore, as shown in Comparative Example 2, it is possible to obtain a carbon composite material that does not exhibit warping, cracking, or peeling when the joint surface size is 500 mm square or less. However, even in this case 700
Carbon composites having dimensions larger than mm square cannot be obtained in high yield. Here, as shown in the present invention, by providing partial non-bonding surfaces in an arbitrary shape and uniformly distributed on the bonding surface of at least one carbon material.
It has become possible to obtain a carbon composite material with a size of 700 mm square or more without warping, cracking, or peeling at a high yield, and it has also become possible to obtain a large carbon composite material with a size of 1200 mm square or more.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic explanatory diagrams showing the method of joining carbon materials carried out in Examples and Comparative Examples.

Claims (1)

[Scope of Claims] 1. Consisting of a carbon material and a flexible graphite sheet between the carbon materials, the carbon material and the graphite sheet are bonded and the whole is fired to become an integrated carbon, and at least one of the carbon A carbon product characterized by having partially non-bonded surfaces in an arbitrary shape and uniformly distributed on the bonding surfaces of materials. 2. The carbon product according to claim 1, wherein a portion of the flexible graphite sheet corresponding to the partially non-bonded surface is removed. 3. The carbon product according to claim 1 or 2, wherein the proportion of the partially non-bonded surface in the bonded surface of the carbon material is 20 to 80% of the bonded surface. 4. The carbon product according to any one of claims 1 to 3, which is entirely fired at a temperature of 800°C or higher. 5. According to any one of claims 1 to 4, wherein the absolute value of the difference in the firing line expansion and contraction ratio when the two carbon materials to be subjected to the joining are fired is within 3%. Carbon products listed. 6 The carbon material is made of carbon aggregate and a binder, and is formed into a carbon material.The carbon material is made of a carbon aggregate and a binder, which is formed and then fired.The carbon material is made of a graphite aggregate and a binder, and is formed and then fired. The carbon material according to any one of claims 1 to 5, characterized in that the carbon material is selected from a carbon material made of graphite aggregate and a binder, molded, and then fired. carbon products. 7. The carbon product according to claim 6, wherein the carbon aggregate is selected from one type or a combination of two or more types from carbon fibers, carbon particles, and oxidized pitch particles. 8. The carbon according to claim 6, wherein the binder is selected from one type or a combination of two or more types from phenolic resin, furan resin, epoxy resin, petroleum-based pitch, and coal-based pitch. product. 9. The carbon product according to claim 6, wherein the graphite aggregate is graphite particles and/or graphitizable carbon particles. 10 The flexible graphite sheet is produced by compressing expanded graphite particles obtained by acid-treating graphite particles with a particle size of 5 mm or less and further heating, and has a thickness of 1 mm.
Below, the bulk density is 0.5 to 1.5 g/cm ³ and the compressive strain rate is
10 ^-4 cm ² /Kg or more, the carbon product according to any one of claims 1 to 9. 11 Consisting of a carbon material and a flexible graphite sheet between the carbon materials, the carbon material and the graphite sheet are bonded together and the whole is fired to form a single piece of carbon, and at least one of the carbon materials has an arbitrary bonded surface on its joint surface. A method for manufacturing a carbon product having a shape of , and having partially non-bonded surfaces uniformly distributed, the carbon product comprising bonding the carbon material and graphite sheet using an adhesive, and further firing. manufacturing method. 12. The method according to claim 11, wherein a portion of the flexible graphite sheet corresponding to the partially non-bonded surface is removed. 13. The method according to claim 11 or 12, wherein the proportion of the partially non-bonded surface in the bonded surface of the carbon material is 20 to 80% of the bonded surface. 14. The method according to any one of claims 11 to 13, characterized in that the entire product is fired at a temperature of 800°C or higher. 15. The carbon material according to any one of claims 11 to 14, wherein the absolute value of the difference in the firing line expansion and contraction ratio when fired at 2000°C is within 3%. Method. 16 The carbon material is: A carbon material made of carbon aggregate and a binder and formed. A carbon material made of carbon aggregate and a binder, formed and fired. A carbon material made of graphite aggregate and a binder and formed. The carbon material according to any one of claims 11 to 15, characterized in that the carbon material is selected from a carbon material made of graphite aggregate and a binder, molded, and then fired. the method of. 17. The method according to claim 16, wherein the carbon aggregate is selected from one type or a combination of two or more types from carbon fibers, carbon particles, and oxidized pitch particles. 18. The method according to claim 16, wherein the binder is selected from one type or a combination of two or more types from phenolic resin, furan resin, epoxy resin, petroleum-based pitch, and coal-based pitch. . 19. The method according to claim 16, wherein the graphite aggregate is graphite particles and/or graphitizable carbon particles. 20 The flexible graphite sheet is manufactured by compressing expanded graphite particles obtained by acid-treating graphite particles with a particle size of 5 mm or less and further heating, and has a thickness of 1 mm.
Below, the bulk density is 0.5 to 1.5 g/cm ³ and the compressive strain rate is
20. The method according to any one of claims 11 to 19, characterized in that it is 10 ^-4 cm ² /Kg or more. 21. Claim 11, wherein the bonding conditions for the carbon material are a temperature at least 50°C higher than the melting point of a binder used as an adhesive, and a press pressure in the range of 0.1 to 50 kg/ ^cm2 . Item ~ 2nd
The method according to any of item 0. 22 The adhesive is methanol, ethanol,
For 100 parts by weight of solvent such as acetone and methyl ethyl ketone, add 5 to 5 parts of phenolic resin, pitch, etc.
200 parts by weight dissolved or phenolic resin,
The method according to claim 21, characterized in that the method is selected from molten epoxy resins, furan resins, etc. 23. The method according to claim 22, characterized in that 0 to 100 parts by weight of carbon particles having a diameter of 200 μm or less are mixed with 100 parts by weight of the adhesive. 24 The flexible graphite sheet is placed in situ.
Claim 1 characterized in that the product is manufactured by
The method described in Section 1. 25 A carbon material is placed in a mold, an adhesive is applied to the surface of the mold, and expanded graphite particles are evenly placed thereon, and a flexible graphite sheet is manufactured on the spot by heating and compressing. A method according to claim 24.