JPS605011A - Preparation of porous material of carbon having high strength - Google Patents

Abstract

PURPOSE:To prepare a porous material of carbon having fine, uniform, open cells and high strength, by calcining a porous material of a synthetic resin consisting of a specific phenolic resin composition in a nonoxidizing atmosphere. CONSTITUTION:A mixed solution consisting of (A) 20-55wt% (calculated as solid content) liquid phenolic resin (e.g., water-soluble resol resin), (B) 8-30wt% granular phenolic resin (average particle diameter; about 1-150mu), (C) 0.5-4wt% polyvinyl alcohol (polymerization degree; about 100-5,000, degree of saponification; >= about 70%), and (D) a pore-forming material (e.g., starch) is blended with (E) a curing catalyst and cured. The prepared porous material of synthetic resin having open cells is calcined in a nonoxidizing atmosphere at about 800-1,000 deg.C and carbonized. The prepared porous material of carbon having high strength is preferably useful as an electrode material for fuel cell, corrosion-resistant and heat-resistant filter, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides continuous pores obtained by adding a curing catalyst to a liquid mixture of a liquid phenol resin, a reactive granular or powdered phenol resin, polyvinyl alcohol, and a pore-forming material and curing the mixture by reaction. The present invention relates to a method for producing a carbon porous body having continuous pores such as glassy carbon by firing a synthetic resin porous body having the following properties in a non-oxidizing atmosphere.

In recent years, with the development of fuel cells and various secondary batteries, the requirements for the characteristics of porous carbon materials as electrode materials have become increasingly strict.
It has become to. That is, as an electrode material, it has characteristics such as high strength, not easily damaged, uniform pore distribution, high continuous porosity, good gas permeability, and low electrical resistance and low power loss. There is an increasing demand for porous carbon materials having the following characteristics.

Conventionally, porous carbon materials have been manufactured by a method of mixing amorphous or spherical carbon or graphite with resin, tar, or pitch, and then molding and firing the mixture. (% 1977-1967
188, etc.) However, the carbon porous bodies produced by these methods have a relatively large apparent specific gravity (1,0
o~1.50), therefore the porosity is also small.

In addition, a method for manufacturing porous bodies (Japanese Patent Publication No. 19999/1983) has been proposed in which carbon X micro hollow bodies are molded using a binder and then fired; 0°05 to 1°00), most of the pores are independent pores, and gas permeability is extremely low.

Furthermore, a method for producing a carbon porous body in which a thermosetting resin is attached to a fibrous structure and then fired is disclosed (Special Publication No. 49
-26196, etc.), but in this case, it is difficult to freely control the porosity to a desired size and to produce a carbon porous body having continuous pores with a uniform pore distribution. there were.

In addition to the above, a method has also been proposed in which polyurethane foam is impregnated with phenolic resin, furan resin, etc. and then carbonized (Japanese Patent Publication No. 125289/1989, etc.), but in this case, it is difficult to achieve high strength. It is difficult to obtain a porous carbon material having fine continuous pores, and it is unsuitable as an electrode material that requires high strength. In addition, a method has been proposed in which a foaming agent is added to liquid phenol resin, liquid furan resin, etc., foamed, and then fired to produce a carbon porous body, but in this case, the gas permeability is poor due to closed pores Moreover, only a porous carbon material with low strength can be obtained.

The present inventors completed the present invention as a result of intensive research in order to improve the defects observed in existing carbon porous materials, and the aim is to have fine and uniform continuous pores. Moreover, it is an object of the present invention to provide a new method for producing a high-strength carbon porous body.

The above purpose is to use a liquid phenol resin with a solid content of 20 to 20%.
55% by weight, reactive granular or powdered phenolic resin 8-60% by weight, polyvinyl alcohol I], 5
This is achieved by adding a curing catalyst to a mixed solution of ~4% electric value and a pore-forming material, and curing the resulting synthetic resin porous body with continuous pores in a non-oxidizing atmosphere.

The liquid phenolic resin used in the present invention is preferably a water-soluble resin-luminut resin.

Resol 4 gravimeter is an initial product produced by reacting phenols with aldehydes in the presence of a basic catalyst.1. Generally, 1 mole of phenol is reacted with 1.5 to 6.5 moles of aldehyde in the presence of a slightly excess alkali catalyst to maintain the initial condensate in a stable water-soluble state. A synthetic resol resin is obtained.

Phenols used in the production of resol resins most commonly include phenol and cresol. However, other phenols can also be used, such as phenol, O-cresol, m-cresol #p-cresol, 2,6-xylenol.

2,5-xylenol, 2,4-xylenol.

2.6-xylenol, 3.4-xylenol.

3, 5 = xylenol, 0-ethylphenol.

m-ethylphenol, p-ethylphenol.

Examples include p-phenylphenol, p-tert-butylphenol, jp-tert-aminophenol, bisphenol A, resorcinol, and mixtures of these phenols.

Formaldehyde is the most common aldehyde used for polycondensation with this phenol. However, monoaldehydes and dialdehydes such as noguraformaldehyde, hexamethylenetetramine, furfural, glutaraldehyde, azibaldehyde and glyoxal may also be used.

Basic catalysts used in the resol resin synthesis reaction include caustic alkali, alkali carbonate, barium hydroxide, calcium hydroxide, ammonia, quaternary ammonium compounds,
Known amines such as amines may be used, and caustic soda or ammonia is most commonly used.Also, the reactive granular or powdered phenol resin used in the present invention is a condensation of phenol and formaldehyde. A granular or powdered resin consisting of a material, which has an infrared absorption spectrum of 1 by KBr tablet method.
The absorption intensity of 6ooiw-1 (absorption peak attributed to benzene) is D1/100, 990 to 1015cs-
The maximum absorption intensity in the range of 1(Me)+:+-L group) is D990~1o1s, 89
When the absorption intensity of 0c+s-1 (absorption peak of isolated hydrogen atom of benzene nucleus) is expressed in Daoo, D990~1o1s/D16oo = 0-2 N9
-OD890/DI600 = 0.0 9~1.
It is made of granular or powdery phenol-formaldehyde resin having a D990 to 1o1s/DI600 = 0.5 to 7.
0D890 /D+6oo = 0.1ゞ0.9 Especially preferably D990~to1s /DI600 = [], 4ゞ5
・In the infrared absorption spectrum of granular or powdered phenol/forma where 0Da9o/D+6oo = 0.12 to 0.8, the peak of %I)i6oo shows the absorption attributed to the benzene nucleus, and the peak of D99Q to 1C15 shows the absorption attributed to the methylol group. Attributable absorption? and also DBP0
It is already widely known with respect to phenol-formaldehyde resin that the peak indicates the formation of a benzene nucleus and is attributable to a hydrogen atom.

The reactive granular powdered phenolic resin used in the present invention has a D99 (1 to 1o1s/D1600
Showing a characteristic value of =0.2 to 9.0 indicates that the resin contains at least a sufficient amount of methylol groups, and the methylol group content can be adjusted to a fairly wide range. There is. In particular, the resin suitable for use in the present invention with D990-1015 = 0.3-7.0, especially 0.4-5.0 contains a moderate degree of methylol group and is highly multistable.

Furthermore, the resin has Dap in the infrared absorption spectrum.
a/Dt6oo = 0.09-1.0, and the fact that a highly suitable resin exhibits the properties of D89D/D1600 = 0.1-o, 9, especially [112-0.8] indicates that the resin This shows the fact that the reaction sites (ortho and para positions) of the phenol molecule that participated in the reaction at L7 are moderately blocked by methylene bonds or methylol groups.

Cured products of conventionally known 1/sol resins are generally manufactured by D990.
~1015/D1600 and DBP0/D1600
Both or either of them are lower than the lower limit of the above-mentioned characteristic values of the reactive granular or powdered phenolic resin used in the present invention, and the hexamine-cured product of the wild duck resin also has DBP. The characteristic value of /D16oo is generally lower than the lower limit of 0.09 for the resin. As described above, the reactive granular or powdered phenolic resin used in the present invention can be obtained by pulverizing a cured product of a conventionally known resol resin or a cured product of Novolac 41 Jilt, or by pulverizing a conventionally known cured novolac resin fiber. This is a phenolic resin made of spherical particles and their secondary aggregates, which is completely different from that described above, and which is produced according to the production method described in JP-A-57-177011. Since this reactive granular or powdered phenol resin has a shape close to spherical, it is more difficult to use polyvinyl alcohol or liquid phenol resin than powder obtained by anointing known cured phenol resins. By using this resin, it becomes possible to obtain a synthetic resin porous body having continuous pores in which a large amount of phenolic resin powder is uniformly mixed. - The average particle size of the phenol resin powder is preferably 1 to 150 microns, particularly preferably 1 to 50 microns, in order to uniformly mix it into the resin porous body. Furthermore, since the phenolic resin powder has reactivity, bonding between the phenol resins is promoted during curing and carbonization of the synthetic resin porous body, making it possible to obtain a high-strength carbon porous body.

The polyvinyl alcohol used in the present invention is generally obtained by saponifying vinyl acetate, and there are no particular restrictions on its degree of polymerization, degree of saponification, branching, copolymerization with other monomers, etc., and it can be used alone or as a mixture of two or more monomers. It is preferable to use a polymer having a degree of polymerization of 100 to 5,000 and a degree of saponification of 70% or more.

As the pore-forming material for providing continuous pores, starch or other organic fine powders, water-soluble metal salts, or the like can be used. The type and size of the powder may be appropriately selected depending on the pore diameter of the intended porous body.

Generally, phetoluenesulfonic acid, benzenesulfonic acid, etc. are suitable as the curing catalyst used in the present invention. Addition I of the curing catalyst] and the shell may be appropriately determined depending on the type of catalyst used, the type of liquid phenol resin, degree A, curing temperature, etc.

In order to produce a synthetic resin porous body using the above-mentioned liquid phenolic resin, reactive granular or powdered phenolic resin, polyvinyl alcohol, and pore-forming material, first a predetermined amount of "liquid phenolic resin 1", reactive granular or powdered phenolic resin, and reactive A mixed forming material of granular or powdered phenol (m), fat (A), and vinyl alcohol is added and stirred, and after cooling to about 40° C., a curing catalyst is further added and mixed uniformly to form a desired mold.

The ratio of each component in the mixed solution of liquid phenol resin, reactive granular or powdered phenol resin, and polyvinyl alcohol prepared during the production of the above synthetic resin porous body is such that the solid content of the liquid phenol resin is 20 to 20.
55% by weight, 8 to 30% by weight of reactive granular or powdered phenolic resin, and 0.5% by weight of polyvinyl alcohol.
5 to 4% by weight of resin, preferably liquid phenolic resin (
10-27% by weight of granular or powdered phenolic resin having reactivity, 1-3% by weight of polyvinyl alcohol, most preferably 50-45% by weight of liquid phenolic resin, and most preferably 50-45% by weight of liquid phenolic resin. The granular or powdered phenol resin having the following properties is 12 to 25% by weight, and the polyvinyl alcohol is 1.5 to 2.5% by weight.

If too little liquid phenol resin is used in preparing the synthetic resin porous body of the present invention, the bonding strength between the granular or powdered phenolic resins in the resulting synthetic resin porous body will be low, and the synthetic resin porous body will Calcining the body in a non-oxidizing atmosphere 1-
However, a high-strength carbon porous material i-1' cannot be obtained. If there is too much liquid phenol resin, the number of independent pores increases, and it becomes difficult to obtain a carbon porous body with a large continuous porosity and good gas permeability.

In addition, the advantage of mixing granular or powdered phenolic resin with reactivity, which is necessary to create a synthetic 4v1 fat porous material, is that the pore distribution is uniform due to the interaction between the 4v1 fat powder and the pore-forming material. This is due to the fact that continuous pores are formed on the side. Furthermore, when the reactive granular or powdered phenol resin of the present invention reacts with the liquid phenol resin during the curing reaction, it helps improve the strength of the synthetic resin porous body.
It plays an important role in developing the strength of the carbon porous material obtained by firing.

If the amount of the resin powder mixed in is too small, the pore size distribution will be uneven, and large voids will easily form inside the sample during the curing reaction, and cracks will easily appear in the first drying process after the curing reaction. During this process, problems arise as the number of closed pores increases, making it difficult to obtain a carbon porous material with a large continuous porosity.

If the amount of the resin powder is too large, the resin powder becomes bulky and workability during mixing with other raw materials is significantly reduced, making it difficult to mix uniformly and making it impossible to obtain a good porous body.

Polyvinyl alcohol imparts a pore morphology unique to polyvinyl alcohol to the porous synthetic resin material through interaction with the pore-forming material, and plays an important role in forming continuous pores. If the amount of polyvinyl alcohol is too small, the pore morphology may change, and the pore distribution may become non-uniform.

On the other hand, if the amount is too high, the viscosity of the liquid mixture will increase and the workability will be significantly lowered, making it impossible to obtain a good porous body.

In addition, in the present invention, as mentioned above, the liquid phenol resin 1h is much larger than the polyvinyl alcohol, so the curing catalyst for the phenol resin can be used without adding a crosslinking agent for polyvinyl alcohol such as formaldehyde or nzaldehyde. A good synthetic resin porous body can be produced just by using the crosslinking agent.Of course, even if the crosslinking agent is added, there is no problem in the production of a synthetic resin porous body.

Furthermore, when creating the above synthetic resin porous body, resin powders such as known phenol resin, furan resin, epoxy resin, etc.
A high-strength carbon porous body with continuous pores can be produced by mixing appropriate amounts of fibrous materials, or inorganic powders such as silica, alumina, graphite, silicon carbide, and clay, and fibrous materials such as carbon fiber and asbestos. It is possible to suppress deformation during firing and improve shape retention without impairing the properties of the material.

The synthetic resin porous body obtained as described above may be further impregnated with or adhered to a phenolic resin such as a resol resin or a novolak resin, a furan resin, a melamine resin, an epoxy resin, a urea resin, or a pitch-tar.

Various known methods can be applied to apply these synthetic resins, but most commonly, continuous resins with a predetermined shape, size, pore size, and porosity are manufactured by the above-mentioned method. A synthetic resin porous body having pores may be immersed in a solution prepared by dissolving the aforementioned synthetic resin in a solvent, and then dried and cured.The synthetic resin porous body thus prepared is then treated with a non-oxidized under a neutral atmosphere, i.e. reduced pressure or argon gas,
It is heated to usually 800° C. or higher, preferably 1000° C. or higher in helium gas, nitrogen gas, etc., and carbonized and fired. There is no upper limit to the firing temperature, and heating may be performed at about 6000° C. 1 if necessary.

According to the research conducted by the present inventors, at around 200℃ during carbonization firing, gaseous compounds such as H2O, HOH
o, 00. OH4 etc. begin to be released from the porous body, but the generation of this pyrolysis gas is most noticeable in the temperature range of 25 (1 to 600°C), and the weight loss and shrinkage of the resin composition are noticeable in this temperature range. In this carbonization firing process, the external heating rate is not particularly limited and depends on the composition, shape, size, etc. of the porous body, and is usually 5°C/hr to 500°C/b.
It may be fired at about r.

The carbon porous body obtained by the above method is a network carbon structure consisting at least partially of glassy carbon, and has fine and uniform continuous pores. Further, the carbon porous body produced according to the present invention has a bending strength of 10 and an O
It has high strength of Jr9/cni or more, and also has good 1ttl resistance and oxidation resistance.

Carbon porous materials with such obsolete characteristics are suitable for the following uses: namely, they have high strength, excellent gas permeability, and good corrosion resistance, so they can be used as electrode materials for fuel cells and various secondary materials. Suitable for electrode materials for secondary batteries, and various filters for separating solids such as powder and impurities in gases and solids in liquids, especially corrosion-resistant or heat-resistant filters. I'm passing through. In addition, it can be used for media carriers, heat insulating materials, structural materials, air diffusers, surface heating elements, high temperature heat treatment jigs, radio wave shielding materials, heat collecting materials, etc.

Furthermore, by subjecting the porous body of the present invention to activated carbonization by steam activation treatment, chemical activation treatment, etc., the activated carbon having a network structure can be used to adsorb and separate mixed solutions and mixed gases.
It can be used for refining or as a heat storage material for to-boompu. In particular, activated carbon activated at relatively low temperatures can be used as a molecular sieve to separate various hydrocarbons and to separate atmospheric nitrogen and ridges.
i: VC can be used and is also suitable as a dazzling material.

The present invention will be specifically explained below with reference to Examples.

Example 1 Main unit degree 1700. Polyvinyl alcohol (pvA) with a saponification degree of 99% is dispersed in water and dissolved in a hot swamp, and then an aqueous dispersion of wheat flour starch having a predetermined particle size is added and mixed with stirring. Furthermore, a predetermined if previously dispersed in water is added to this solution.
Reactive granular phenol 4!1i = i (manufactured by Toribo ■ - trade name Belhar S1 average particle size 20μ, u) and water-soluble resol resin (manufactured by Sumitomo Delez ■, PR961A)
) and mix thoroughly. Water for adjusting the liquid volume was further added to this mixed liquid to adjust the weight of the mixed liquid to 104. The mixture of each component in the liquid mixture was measured by tightening so that the mixture was as shown in Table 1.

The powder concentration in this mixture was 2.5% by weight.

After cooling the above mixture to 40°C, add para-toluenesulfonic acid water (al(xbo) with a concentration of 50%).

After adding g and stirring further, the bottom surface becomes s o o ==%
It was cast into a square polypropylene Ha frame, reacted for 20 hours in a hot water bath at 70°C, removed from the mold, and washed in the shower for 6 days to obtain a synthetic resin porous body with continuous pores.

The synthesized porous material obtained as described above was dried at 110°C for 24 hours, then placed in an electric furnace at 20°C/20°C in a nitrogen atmosphere.
The temperature was raised to 1000'C for 8 hours to perform carbonization.

The composition of the synthetic resin porous body and the properties of the obtained carbon porous body are shown in Table 1. In addition, the pore size distribution of each sample of the carbon porous body prepared by this method was measured by mercury intrusion method. The average pore diameters of the samples were all within the range of 15 to 20 μm.

As described above, the carbon porous body obtained by the present invention has fine continuous pores and is a highly strong carbon porous body with a bending strength of about 10D/cf1 or more Table 1 Example 2 Same as Example 1 P'VA with a degree of polymerization of 500 and a degree of saponification of 99%, a reactive granular phenol resin (manufactured by Kanebo Co., Ltd., trade name: Bell Pearl S2, average particle size 30 μm), and a water-soluble Nzol resin (manufactured by Sumitomo Delez ■, PR961).
A) and potato starch of a predetermined particle size were used to achieve a PVA reactivity of 1.0% by weight. The mixed solution was prepared by changing the starch particle size to prepare 2 kg of each of the four types of starch. The starch concentration in this liquid mixture was 6.0% by weight.

Add 200 g of a 20% concentration oxalic acid aqueous solution as a curing catalyst to the above mixed solution, stir it, then cast it into a polypropylene frame with a 1100 x 200 square bottom, and place it in warm water at 65°C for 24 hours.
After reacting for an hour and removing the mold, it was washed with a shower for 3 days to obtain a synthetic resin porous body with continuous pores. The synthetic resin porous body was dried at 110°C for 24 hours, then placed in an electric furnace at 50°C in a nitrogen atmosphere. / hr and increase the temperature to 15
Carbonization was carried out by holding at 00°C for 5 hours. The properties of the carbon porous body thus obtained are shown in Table 2.

Table 2 The average pore diameter of the carbon porous material was measured using a scanning electron micrograph of the fracture surface. As shown in the first coating, by changing the particle size of starch, it was possible to produce a carbon porous body with an average pore diameter of 20 to iso μm.

Example 6 As a phenol fat powder, a reactive granular phenol resin (manufactured by Renbomi Co., Ltd., black market name: Belpearl S, average particle size 6) was used.
0μm), cured novolac fiber powder (Nippon Kynol@g, KFO2BT, 1m fiber length 1μm) and resol resin (manufactured by Gunei Kagaku Kogyo ■, AP-106GK) at 150%
Example 1 was prepared using six types of resol resin cured powders (average particle size 50 μm) obtained by curing at ℃ for 24 hours and then pulverizing.
A plate-shaped synthetic I☆I resin porous body was created by combining the same material with the above.

Raw materials other than the above include P'VA with a degree of polymerization of 1000 and a degree of saponification of 99%, water-soluble resol resin (manufactured by Sumitomo Durez ■, P) (961A), and horse-ageed potato starch, and sulfuric acid is used as a curing catalyst. did.

The amount of mixed liquid during the production of the synthetic resin porous body is 2 phantom, and the solid content concentration of water-soluble resol 11po in the mixed solution is 62% by weight, the concentration of polyvinyl alcohol is 2% by weight, and the concentration of the original material is 2% by weight. Then, the amount of phenol resin powder was changed to 3.
Instead, a porous body of 5f111 type was prepared as shown in the table. For the curing catalyst, add 60% sulfuric acid at 50% temperature to 2 kg of mixed liquid.
g added.

The curing conditions during production of the synthetic resin porous body were 70°C for 24 hours, and after curing, it was washed with a shower for 5 days and dried at 110°C for 24 hours. The synthetic resin plate-like porous body obtained in this way was
After cutting into 00 x 200 x 15 ms, it was placed in an electric furnace and heated at a rate of 60° C./hr in a nitrogen atmosphere, and then held at 1100° C. for 24 hours for carbonization firing.

The properties of the synthetic resin porous body and the obtained carbon porous body are described in the sixth section.
Shown in the table. This result shows that a high-strength carbon porous body can be obtained by using a granular phenolic resin having fu-reactivity.

Example 4 Table 3 was prepared in the same manner as in Example 1, with a degree of polymerization of 1000 and a degree of saponification of 99%.
pvA5-o weight%, reactive granular phenol tree 74116 Shigekura%, water bathable reso-# resin (Sumitomo f-
vstA: Ufjl, PR961A) (solid content) 25
Weight%, potato starch 2.8% by weight mixture 2 J
ty was adjusted and 70 g of 50% sulfuric acid was added as a curing catalyst to react and cure, and then washed in the shower for 5 days.
Dry at 0°C for 24 hours to create a cylindrical synthetic resin porous body with an outer diameter of 60'' x 200iμ, and the porous body with an inner dimension of 30
Place in an electric furnace of 0x500x650 in a nitrogen atmosphere
It was fired at 00°C to obtain a carbon porous body. Furthermore, the carbon porous body was held in the same electric furnace in a steam atmosphere at 700°C for 6 hours to produce activated carbon having a specific surface of g 560 m'/gt. The steam pig enclosure is heated to 80 degrees Celsius for 10 minutes.
It was created by blowing nitrogen gas at Q/min.

Claims (1)

[Scope of Claims] (1) 20 to 55% by weight of liquid phenol resin in solid content, 4M of reactive granular or powdered phenol
J+W8~60% by weight, polyvinyl alcohol 0.5~
A high oxidation method characterized by firing a synthetic resin porous body having continuous pores obtained by adding a curing catalyst to a mixed liquid consisting of 4-fold solids and a pore-forming material and curing it in a non-oxidizing atmosphere.・ , − Manufacturing method of carbon porous body. (Phantom) Method for manufacturing a porous carbon material according to claim (1), in which the liquid phenolic resin is a water-soluble resol (3) The reactive granular or powdered phenolic resin has an average particle size of 1 to 150 microns. The method for producing a porous carbon material according to claim (1), which is spherical-deficient particles and secondary aggregates thereof.