JPS64352B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon foam structure having a carbon film layer and a method for manufacturing the same. It is characterized by a carbon foam structure consisting of a carbon film layer in which substances are entangled and laminated in close contact with each other, and a fibrous substance is entangled with and laminated on the resin foam surface or carbon foam surface, and then dried and fired. The present invention relates to a method for manufacturing a carbon foam structure having a carbon film layer.

Carbon foam is obtained by coating a resin foam such as polyurethane foam or phenol foam with a resin as necessary and then firing it at high temperature.The structure of carbon foam 1 is as shown in Figure 1. It has a three-dimensional network structure in which the skeletons 1A are three-dimensionally connected and the pores 1B have a substantially constant size. Because of this unique structure, it is less susceptible to stress concentration, and its mechanical strength is higher than other porous materials despite its high porosity.
It has the characteristics of high elasticity and low pressure loss. Furthermore, due to the properties of carbon, it has various characteristics such as being lightweight, and having excellent electrical conductivity, corrosion resistance, and heat resistance. For this reason, it has a wide variety of uses, including as a filter material for chemically reactive and corrosive gases and liquids, as a catalyst support material, and as a high-temperature heat insulating material.

As described above, carbon foam itself has excellent characteristics, but carbon foam itself has various problems in terms of handling and use. In other words, carbon foam alone has a fairly strong overall strength, but the strength of individual pores is weak, so when handling it during assembly, transportation, storage, etc., it has drawbacks such as surface scratching and poor abrasion resistance. In addition, permeated gas and liquid leak from the sides of filters, catalyst carriers, etc., resulting in insufficient product functionality. For this reason, forming a film layer on the surface of carbon foam alone is effective in terms of product functionality.In particular, in order to take advantage of the excellent characteristics of carbon foam, it is most effective to use carbon, which is the same material, as the film material. It was hot. However, due to the difference in shrinkage rate between the resin foam and the coating material during the drying and firing process when creating the carbon foam, it has been difficult to obtain a good carbon coating with strong surface strength and no peeling, cracking, chipping, or pinholes. .

Furthermore, in the case of a carbon foam having a normal three-dimensional network structure, when a carbon film is formed on the surface thereof, there is a problem in that the carbon film is extremely likely to peel off if only the bonding material is used in close contact with the foam.

That is, as shown in FIG. 1, on the surface of a low-density carbon foam, the density of the bonding portion with the coating is extremely low, and the bonding portion with the coating is almost a point contact. Therefore, if only a bonding material is used, the bonding density is too low and the bonding points are minute, so the strength is not sufficient, and they tend to peel off due to pressure, vibration, and other external conditions.

Conventionally, as a method for creating a carbon film on carbon foam, when creating a resin foam as a starting material, a method is known in which a film of the same resin is created on the surface of the resin foam and then baked to obtain a carbon film. There is. However, with this method, if a thick film is made to increase the surface strength, cracks, chips, pinholes, etc. will occur due to the shrinkage of the resin foam. There were problems such as low strength and poor sealing performance. In addition, a method is known in which a coating material made of carbon or graphite in the shape of grains, paper, felt, cloth, etc. is adhered to a green form made of micro hollow carbon bodies using a binder such as resin or tar pitch, and then fired at the same time. (Tokuko Sho 50-29838). In this method, since the shrinkage of the green foam is small, a good carbon film can be obtained, but when it is used on a resin foam having a normal three-dimensional network structure, there are the following problems.

1. The shrinkage of normal resin foam is much larger than that of green foam, so it is significantly different from the shrinkage of coating materials, causing cracks and chips.

2 As the coating material in the above manufacturing method, a coating material in the form of grains, paper, felt, cloth, etc. is used, but since this coating material is adhered to the foam surface with a binding material, shrinkage of this binding material causes , the quality of the carbon film is determined. Therefore, although a good carbon film can be obtained with a green foam that has small shrinkage and contains carbon micro-hollows, it is extremely difficult to match the shrinkage rate with ordinary resin foam that has a large shrinkage, resulting in cracks and chips. arise.

Another method is to create a carbon film by firing a resin foam, adhere a film material to the surface of the carbon foam, and create a carbon film by adhering a film material to the surface and firing it. In this case, since the base material carbon foam no longer shrinks due to firing, the difference in shrinkage rate between the two becomes large, resulting in peeling, cracking, etc.
Chips, pinholes, etc. occur, and a good carbon film cannot be obtained. Furthermore, since adhesive is used, it is difficult to obtain a smooth and strong carbon film for foams with large pore diameters.
Furthermore, there were various problems such as the fact that the adhesion process was time-consuming.

To summarize the problems of conventional manufacturing methods as described above, in short, the difference in shrinkage rate between the resin foam and the coating material is a major cause that hinders the production of a good carbon coating. In other words, it is known that resin foam undergoes extremely large volumetric shrinkage upon firing; for example, the volumetric shrinkage during carbonization firing reaches 60-75% for urethane foam, and approximately 50% for phenol foam. It is being For this reason, it is extremely difficult to control the large shrinkage of the resin foam during manufacturing, and the inherent shrinkage of the coating material also affects the coating material, resulting in peeling, cracks, chips, pinholes, etc. of the coating material during firing. It is difficult to avoid this, and the above-mentioned tendency becomes even more pronounced when a thick coating is applied to increase the surface strength.

As a result of intensive study on the above-mentioned problems, the inventor of the present invention found that by coating the resin foam with a coating material that freely follows the large shrinkage of the resin foam, it has no peeling, cracking, or chipping, has high surface strength, and has excellent sealing properties. They discovered that a carbon film with a high quality can be obtained. That is, the carbon foam structure of the present invention and its manufacturing method are characterized in that fibrous substances are intertwined with the surface of a resin foam or carbon foam, adhered and laminated, and then fired. In other words, when each fibrous substance dispersed in a liquid is adhered to and stacked on a foam, the individual fibers are not fixed to each other on the foam surface and are held only by entanglement, so the fibrous substances aggregate and stack. The resulting coating material has an extremely large degree of flexibility in shrinkage during firing, and even if the shrinkage rate of the base material changes greatly depending on various conditions such as material, pore size, manufacturing conditions, etc., it will not shrink during firing. It is possible to freely shrink or bond without shrinking according to the shrinkage of the foam without causing peeling, cracking, chipping, distortion, pinholes, etc. that are likely to occur.

Further, as other features of the manufacturing method of the present invention, 1. Even if the fiber coating layer is fired thickly, peeling, cracking, chipping, etc. do not occur due to the above reasons, so a thick carbon coating layer can be obtained, and therefore the surface strength is improved. A carbon foam structure with a large sealing property can be obtained.

2. When a fibrous material is adhered to and laminated on the foam surface, the fibrous material becomes entangled and attached to the foam skeleton on the foam surface, so that a carbon film layer with good adhesion can be obtained.

As described above, the carbon film layer obtained by the manufacturing method of the present invention has a structure in which fibrous carbon substances are entangled, tightly adhered, and laminated, and is also tightly adhered to the carbon foam skeleton, has a high surface strength, and is airtight. It is a carbon film layer with excellent properties.

Next, to specifically describe the manufacturing method of the present invention, 1. Dry or harden a resin foam such as phenol or polyurethane having a three-dimensional network structure, or a resin foam coated with an organic compound, and then By applying or drawing a liquid in which a fibrous substance is dispersed onto the surface of the resin foam, the fibrous substance is intertwined with the foam surface and adhered and laminated to form a fibrous film layer, and after drying, the resin foam is dried in an inert atmosphere. , roughly
A carbon foam structure having a carbon film layer is created by firing at a temperature of 500°C or higher.

2 A resin foam such as phenol or polyurethane having a three-dimensional network structure, or a resin foam coated with an organic compound, is dried or cured, and then fired at approximately 400°C or higher to create a carbon foam. By applying or drawing a liquid in which a fibrous material is dispersed onto the surface of the carbon foam, the fibrous material is intertwined with the surface of the carbon foam, adhered and laminated to form a fibrous film layer, and after drying, the liquid is placed in an inert atmosphere. Inside, a carbon foam structure having a carbon film layer is created by firing at approximately 500°C or higher.

Examples of the material for the resin foam used in the production method of the present invention include resins commonly used in forming foams, such as polystyrene, cellulose, polyurethane, phenol, furan, urea, and epoxy. In addition, the skeleton of the resin foam can be coated with an organic compound if necessary, and in this case, the organic compound may include natural polymers, synthetic polymers,
Examples include dry distillates of hydrocarbon compounds, pitch, asphalt, and thermosetting resins such as phenol, epoxy, and furan, and these may be used alone or in combination. At this time, the carbonization yield of the organic compound to be coated is preferably 5% or more. If it is less than 5%, the strength of the carbon foam skeleton obtained after firing will deteriorate.

Here, the carbonization yield was determined by the following method. That is, the dry sample weight W ₁ is measured, the sample is then heated to 1000°C at a heating rate of 100°C/hr in an inert gas, and the remaining weight W is calculated by firing the sample at 1000°C for 1 hour. ₂ was measured.

Carbonization yield=(W ₂ /W ₁ )×100(%) The combination of the resin foam and the organic compound to be coated must be appropriately selected from the viewpoints of shape retention and strength. For example, in the case of a resin foam with a low carbonization yield such as urethane foam, it is coated with an organic compound that has a high carbonization yield, and in the case of a resin foam with a high carbonization yield such as phenol foam, it is coated with an organic compound. You don't have to do it.

Next, the resin foam is dried, hardened or fired. When the resin foam is coated with a thermosetting resin and hardened, a hardening agent may be used to speed up the hardening speed. Further, when a carbon foam is created by firing a resin foam, it is preferable to perform the firing at a high temperature of at least 400° C. or higher in order to carbonize the resin foam. As the atmosphere at this time, a non-oxidizing atmosphere such as reducing, inert gas, vacuum, etc. is used.

A liquid in which fibrous substances are dispersed is applied or drawn onto the surface of the resin foam or carbon foam obtained in the above manner to create a fibrous film layer. Any organic fiber that can be carbonized by firing such as fibers and resin fibers may be used, such as cellulose, polyacrylonitrile, polyvinyl alcohol, polyacrylamide, polyamide, pituitary type, lignin type, urea type, polyvinyl chloride, polyvinylidene chloride. Carbon fibers, graphite fibers, etc. can also be used, and these can be used alone or in combination. At this time, the carbonization yield of the fibers is preferably 5% or more. If it is less than 5%, it will not remain on the foam surface as a fibrous film, impairing its function as a film material. Also, the thickness of the fibers is approximately
The thickness is preferably 100μ or less, preferably 50μ or less. If it is 100μ or more, it becomes difficult to entangle with the foam surface, making it difficult to obtain a good carbon film layer.

Next, the liquid for dispersing the fibrous material may be any liquid as long as it can disperse the fibers without dissolving them, such as water or a solvent. Further, a small amount of a thickening material such as carboxymethyl cellulose, polyacrylamide, or polyvinyl alcohol may be added to the liquid. By adding a sizing agent, the degree of adhesion of the fibers to the foam surface is further improved.

Using a liquid in which fibrous substances are dispersed, a fibrous film layer is formed on the surface of the foam by coating or drawing.The specific method involves intertwining each fibrous substance on the surface of the foam, adhering it, and laminating it. Any method may be used as long as it can be applied, and examples thereof include methods such as sifting, spraying, filtration, hand coating, and pressure application, and methods such as shaving and filtration are particularly preferred. By applying or drawing a liquid in which a fibrous substance is dispersed onto the foam surface using the above method, a fibrous film layer can be obtained in which the fibrous substance is entangled with the foam skeleton on the foam surface without sticking to each other. It will be done. Furthermore, by repeating the above method or increasing or decreasing the amount of fibrous material in the liquid, a fibrous film layer having an arbitrary thickness can be obtained.

After the fiber coating layer is created, the coating layer may be impregnated and coated with a resin or a resin to which a filler such as graphite or carbon black is added, if necessary. By impregnating and coating, a carbon film layer with even higher surface strength can be obtained, and the sealing properties of the film can also be improved.

After the fiber coating layer is created, it is dried and fired. In order to make the fiber coating layer into a carbon coating layer, it is preferable to bake at at least 500°C or higher. If the temperature is below 500°C, the strength of the carbon foam body and the carbon film layer will not be sufficient. As the atmosphere at this time, a non-oxidizing atmosphere such as reducing, inert gas, vacuum, etc. is used.

Next, examples of the present invention will be described.

Example 1 A rectangular urethane foam having a three-dimensional network structure was coated with phenolic resin and heated at 100°C for 15 hours.
It was heat cured. Next, a liquid in which polyacrylonitrile fibers (PAN fibers) having a diameter of 40μ are dispersed in a 3% carboxymethyl cellulose aqueous solution is created, and this liquid is poured onto the surface of the cured foam and paper is made on the foam. PAN in which PAN fibers are intertwined without sticking to each other on the foam surface
A foam structure in which the fiber film layers were adhered and laminated was obtained. Next, this foam structure was heated to 100℃.
Dry for 20hr and 50 to room temperature ~900℃ in inert gas
The temperature was raised at a temperature increase rate of °C/hr, and firing was performed at 900 °C for 1 hour. On the outer peripheral side of the obtained rectangular carbon foam, the PNA fiber coating layer was carbonized and shrunk as the foam contracted, and a carbon coating layer was formed that was free from peeling, cracking, and chipping.

Example 2 A cylindrical furan resin foam having a three-dimensional network structure was coated with polyvinyl chloride at 100°C for 15 hours.
Dry. Next, a liquid was created in which cellulose fibers having a diameter of 80μ were dispersed in a 2% polyvinyl alcohol aqueous solution, and this liquid was sprayed onto the foam, so that the cellulose fibers became entangled without sticking to the foam surface. A foam structure was obtained in which the cellulose fiber film layers were closely adhered and laminated. Next, this foam structure was heated at 100℃ for 15 hours.
Dry and store under inert gas at room temperature to 1000℃
The temperature was raised at a temperature increase rate of °C/hr, and firing was performed at 1000 °C for 1 hour. Around the side surfaces of the obtained cylindrical carbon foam, a carbon film layer with no cracks or cracks was formed as the cellulose fibers contracted while carbonizing in accordance with the shrinkage of the foam.

Example 3 A viscous liquid in which carbon fibers having a diameter of 8 μm were dispersed in a 5% polyacrylamide aqueous solution was applied by pressure onto a disc-shaped phenolic resin foam having a three-dimensional network structure. After creating a foam structure in which carbon fiber film layers in which carbon fibers were intertwined without being fixed to each other were adhered and laminated on the foam surface, the carbon fiber film layer was impregnated and coated with an epoxy resin. Next, this foam structure was dried at 100℃ for 15 hours and then heated to room temperature in an inert gas.
Raise the temperature to 1000℃ at a heating rate of 50℃/hr.
Baked for 1 hour. The surface of the obtained disc-shaped carbon foam has a
The carbon fiber coating layer shrank, and a carbon coating layer that was bonded by carbon obtained from the epoxy resin and free from peeling, cracking, and chipping was formed.

Example 4 A rectangular urethane foam with a three-dimensional network structure was coated with furan resin, heat-cured at 100°C for 15 hours, and then heated in an inert gas from room temperature to 800°C.
The temperature was raised at a temperature increase rate of 50°C/hr and fired at 800°C for 1 hour to create a carbon foam. then 2%
By creating a liquid in which cellulose fibers with a diameter of 40μ are dispersed in an aqueous solution of polyacrylamide, and filtering this liquid over carbon foam, cellulose in which the cellulose fibers are intertwined without sticking to each other on the surface of the carbon foam is created. A foam structure in which the fiber film layers were adhered and laminated was obtained.
Next, this foam structure was dried at 100℃ for 15 hours, and then dried at 150℃/hr from room temperature to 1000℃ in an inert gas.
The temperature was raised at a temperature increase rate of 1,000°C for 1 hour. Around the side surfaces of the obtained rectangular carbon foam, a carbon film layer was formed in which the cellulose fibers were carbonized without shrinking and were free from peeling, cracking, and chipping.

Example 5 A disc-shaped phenolic resin foam having a three-dimensional network structure was coated with polyvinylidene chloride and heated at 100°C.
After drying for 10 hours, store in an inert gas at room temperature to 1000℃
The temperature was increased at a temperature increase rate of 50°C/hr to 100°C, and the carbon foam was created by firing at 1000°C for 1 hour. Next, a liquid is prepared by dispersing petroleum pitch fibers having a diameter of 30μ in a 1% polyvinyl alcohol aqueous solution, and this liquid is drawn up on the carbon foam, so that petroleum pitch fibers are individually distributed on the surface of the carbon foam. After obtaining a foam structure in which the petroleum pit fiber coating layers were closely adhered and laminated without being fixed, polyvinyl alcohol to which graphite had been added was impregnated onto the petroleum pitch fiber coating layer to coat it. Next, this foam structure was heated at 100℃ for 15 hours.
Dry and store under inert gas at room temperature to 1000℃
The temperature was raised at a temperature increase rate of °C/hr, and firing was performed at 1000 °C for 1 hour. On the surface of the obtained disc-shaped carbon foam structure, a carbon film layer was formed, which was free from peeling, cracking, and chipping, in which graphite, petroleum pitch fibers, and polyvinyl alcohol were carbonized without shrinking.

As described above, the carbon film material of the carbon foam structure obtained by the manufacturing method of the present invention has no peeling, cracking, distortion, pinholes, etc., and has good adhesion and airtightness compared to the film material produced by the conventional manufacturing method. Furthermore, according to the manufacturing method of the present invention, a carbon film with a thick layer, which was difficult to obtain with conventional manufacturing methods, can be easily obtained, so a carbon film with high surface strength can be obtained. It has excellent characteristics such as being able to obtain an extremely stable carbon foam structure with no surface chips and high abrasion resistance in terms of handling.

Furthermore, when considered as a structure, peeling, especially at the joint between the carbon foam base and the film, is a major problem in terms of application. Not only the surface part of carbon foam,
By entangling the fibrous carbon material toward the inside and making surface contact, the joint area and strength can be greatly increased, and the fibrous carbon material that is in close contact with the joint part is entangled and continuous in the film. Therefore, it is possible to obtain an excellent carbon film that does not easily peel off even under repeated use under external conditions such as vibration and pressure.

The carbon foam structure obtained by the production method of the present invention has an excellent carbon film and is therefore used for building materials, civil engineering, chemical industry, electrical industry, aircraft industry, machinery industry, nuclear power industry, etc. industrial,
It can be used in a wide range of applications, including all types of carbon foam structure products, including medical applications, such as lightweight aggregates, high temperature insulation materials, electrodes, catalysts, catalyst supports, corrosive and high temperature filtration media, filter,
bearings, mechanical seals, dental and surgical prostheses and other medical implants, acoustic diaphragms utilizing the properties of carbon and foam structures;
It can be used for tone arms, and even as activated carbon molded products made by activating carbon foam.In other words, since pressure loss can be almost ignored, it can be used to remove hydrocarbons from automobile exhaust gas, and to incorporate air into air conditioners. It can be used for deodorization, etc., making a great contribution to industry.

[Brief explanation of drawings]

FIG. 1 is a plan view of the carbon foam used in the present invention. 1... Carbon form, 1A... Skeleton of carbon form 1, 1B... Holes in carbon form 1.

Claims (1)

[Scope of Claims] 1. A carbon foam structure comprising a carbon foam having a three-dimensional network structure and a carbon film layer in which fibrous carbon substances are intertwined and adhered to and laminated on the surface of the carbon foam. thing. 2. By drying or curing a resin foam having a three-dimensional network structure, or coating the resin foam with an organic compound, and then applying or drawing a liquid in which a fibrous substance is dispersed onto the surface of the resin foam. A method for manufacturing a carbon foam structure having a carbon film layer, which comprises: forming a fiber film layer by intertwining, adhering and laminating fibrous substances on the surface of the foam, followed by drying and firing. 3. A resin foam having a three-dimensional network structure, or a resin foam coated with an organic compound, is dried or cured, then fired to form a carbon foam, and then the liquid in which the fibrous material is dispersed is mixed into the carbon foam. A carbon foam having a carbon film layer, which is characterized in that a fibrous substance is entangled with the carbon foam surface by coating or drawing into the surface of the carbon foam, adhering to it, and laminating it to form a fiber film layer, which is then dried and fired. Method of manufacturing structures.