JPH01257175A - Production of carbonaceous porous body - Google Patents

Abstract

PURPOSE:To improve the dimensional stability of the resulting carbonaceous porous body at the time of use at a high temp. by graphitizing a hardened body of resol type phenol resin contg. a water soluble nickel compd. by calcining at a prescribed temp. CONSTITUTION:Resol type phenol resin is mixed with the water soluble nickel compd. such as nickel sulfate or nickel chloride, a hardening agent and a blowing agent. This mixture is charged into a mold and the blowing agent is expanded by heating to form a porous hardened body. At least part of the hardened body is graphitized by calcining at >=2,000 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a carbonaceous porous body, and more specifically, the present invention relates to a method for producing a carbonaceous porous body using a resol type phenolic resin. Regarding the method.

Until now, carbon porous bodies obtained by firing and carbonizing phenolic resin foams have been heated at temperatures of 1500°C or higher, especially 2000°C.
It is known that it is suitable as a heat insulating material for the above-mentioned high-temperature furnaces. The phenolic resin that is the raw material for this porous carbon material is
Unlike tar and pitch, which are known as other carbon raw materials, it does not easily graphitize by high-temperature heat treatment, that is, it is known as a non-graphitizable material. This carbon material made from phenolic resin does not cause problems in dimensional stability when used at temperatures of about 2000°C, but at high temperatures of 2500°C or higher, especially 3000°C, As a result of the inventors' study of countermeasures against shrinkage, it was observed that blackening progresses during use, resulting in dimensional shrinkage. It was found that dimensional shrinkage can be effectively prevented.

As a method for graphitizing such carbonized phenolic resins, for example, Ohkama et al.
A method has been reported in which a phenol resin plate is prepared by blending nickel into a phenol resin using 5NIC5H5), and the phenol resin plate is graphitized. However, this report concerns a thin plate-like carbon material. Unlike such thin plate-like carbon materials, carbonaceous porous materials have a higher-order structure in which many holes exist three-dimensionally, so there is a possibility that the holes will be destroyed during graphitization. In addition, there is a possibility that the additive may inhibit the molding of the phenolic resin foam, which is the raw material for the carbonaceous porous body.

That is, the phenolic resin foam cured product can be produced by blending a curing agent and a foaming agent into the phenolic resin prepolymer, which is the main raw material, and incorporating fine air bubbles into the cured product during curing. When producing such a foamed cured product, novolak type phenolic resin cannot effectively produce the cured product, so
Resol type phenolic resin etc. are used.

In the report by Okama et al., a novolac type phenolic resin is used. Although resol-type phenolic resins and novolak-type phenolic resins appear to have similar structural formulas, there are significant differences in their properties. That is, the novolac type phenolic resin prepolymer is a so-called thermoplastic resin that is solid at room temperature and melts when heated. On the other hand, a resol type phenolic resin prepolymer is in the form of an aqueous dispersion at room temperature. Therefore, lipophilic nickel compounds such as nilakerosene have low affinity with resol type phenolic resins, and it is extremely difficult to uniformly disperse them in resol type phenolic resins. Furthermore, even if a foamed hardened resol-type phenolic resin in which a nickel compound such as Nitsugerocell is forcibly dispersed is produced, and then fired at a low temperature, it is then fired at a high temperature for graphitization. Since graphitization does not proceed uniformly during the firing stage, there is a problem in that the dimensional shrinkage of the fired body becomes uneven and cracks are likely to occur. Furthermore, some nickel compounds significantly reduce the curing properties of resol-type phenolic resins when producing foams, and when such nickel compounds are used, carbonaceous porous bodies (carbocells) The problem is that it cannot be effectively manufactured.

Therefore, until now, there has been no known method for promoting graphitization of porous carbon materials other than increasing the heat treatment temperature.

The present invention is intended to solve the problems associated with the prior art as described above, and has good dimensional stability and does not warp or warp when used at high temperatures in applications such as insulation materials. The object of the present invention is to provide a method that can easily produce a carbonaceous porous body that is less prone to cracks.

Nine skins two: The method for producing a carbonaceous porous body according to the present invention involves firing a porous cured body of a resol type phenolic resin containing a water-soluble nickel compound to graphitize at least a portion of the porous cured body. It is characterized by

According to the method for producing a carbonaceous porous body according to the present invention, since the affinity between the water-soluble nickel compound and the resol type phenolic resin is very good, the porous cured body formed from the resol type phenolic resin is The water-soluble nickel compound is dispersed very uniformly. Therefore, by firing such a porous hardened material, graphitization progresses well even at low temperatures, and the resulting carbonaceous porous material is used as a heat insulating material to prevent warping or cracking due to shrinkage when used for long periods at high temperatures. The occurrence can be effectively prevented.

Chief sergeant I-W trigram The present invention will be explained in detail below.

In the method for producing a carbonaceous porous body according to the present invention, first,
A porous cured body of resol type phenolic resin containing a water-soluble nickel compound is prepared.

The phenol resin used in the method for producing a carbonaceous porous body according to the present invention is a resol type phenol resin.

That is, phenolic resins obtained by the reaction of phenols such as phenol, cresol, xylenol, and resorcinol with aldehydes such as formaldehyde, acetaldehyde, and furfural are produced by the reaction of phenol resins such as phenol, cresol, xylenol, and resorcinol with aldehydes such as formaldehyde, acetaldehyde, and furfural, depending on the charging ratio of phenol precipitate and aldehyde and the synthesis catalyst. Depending on whether an acidic catalyst or an alkaline catalyst is used, they are broadly classified into resol-type phenolic resins and novolak-type phenolic resins.

In the present invention, among such phenolic resins,
Uses resol type phenolic resin.

In addition, in the manufacturing method according to the present invention, resins other than phenolic resins or carbon source components can also be used within a range that does not impair the properties of the resol type phenolic resin.

Examples of such resins or carbon source components include cellulose, (meth)acrylic acid resins, charcoal, carbon black, pitch coke and petroleum coke, and carbon fibers.

In the method for producing a carbonaceous porous body according to the present invention, a water-soluble nickel compound is blended with the above resol type phenolic resin.

Water-soluble nickel compounds that can be used here include nickel salts of inorganic acids such as nickel sulfate, nickel chloride and nickel nitrate, and nickel salts of organic acids such as nickel acetate, nickel propanoate and nickel benzoate. I can do it. These water-soluble nickel compounds can be used alone or in combination.

In the present invention, water solubility means that the solubility in 100 g of water at 25° C. is 0.1. In the present invention, the content of nickel atoms in the water-soluble nickel compound is preferably 20% by weight or more, and the molecular weight is 150 to 300%.
Particularly preferred are water-soluble compounds within the range of .

Among such water-soluble nickel compounds, nickel chloride or nickel sulfate is preferred.

In particular, nickel chloride, unlike other nickel compounds,
Since it is dissolved in the resol type phenolic resin, it has the advantage that it can exist uniformly in the resol type phenolic resin, and the resol type phenolic resin can be graphitized very smoothly and uniformly.

Note that some of the water-soluble nickel compounds mentioned above have the effect of somewhat retarding the curing of resol-type phenolic resins, but when using such nickel compounds, the characteristics of this compound must be checked. It may be desirable to use a combination of other compounds to compensate.

The blending amount of the water-soluble nickel compound as described above is usually 0.01 to 50 parts by weight, particularly within the range of 0.1 to 10 parts by weight, based on 100 parts by weight of the above-mentioned resol type phenolic resin. It is preferable to use a water-soluble nickel compound; if the amount of the nickel compound is less than 0.01 parts by weight, the effect of using this nickel compound may not be expressed effectively, and even if it is used in an amount greater than 50 parts by weight, the amount Further, depending on the type of nickel compound, the viscosity of the resol type phenolic resin becomes extremely high, making stirring difficult and making it difficult to perform foam molding smoothly.

When producing a porous cured body from the resol-type phenolic resin containing the above-mentioned water-soluble nickel compound, the above-mentioned water-soluble nickel compound and resol-type phenolic resin are mixed, and a curing agent and a blowing agent are further added to this mixture. A method of preparing a mixture and heating and curing the mixture can be used.

The curing agents used here include sulfuric acid, hydrochloric acid, phosphoric acid,
Examples include acid curing agents such as lactic acid and acetic acid, and aromatic sulfonic acid curing agents.

Particularly in the present invention, it is preferable to use an aromatic sulfonic acid curing agent such as para-toluenesulfonic acid or phenolsulfonic acid.

The use and amount of such a curing agent can be determined as appropriate considering the type of curing agent used, etc., but it is usually 1 to 30 parts by weight and preferably 1 to 30 parts by weight based on 100 parts by weight of the resol type phenolic resin. is 5 to 20 parts by weight.

In addition, as the blowing agent, a blowing agent that is normally used when producing resin foam can be used, but in the present invention, it is liquid at room temperature, and its boiling point is the curing temperature of the resol type phenolic resin. Examples of such fluorocarbons for which it is preferable to use nearby fluorocarbons include trichlorofluoromethane, tetrachlorodifluoroethane, trichlorotrifluoroethane and dibromotetrafluoroethane.

The amount of blowing agent used depends on the characteristics of the carbonaceous porous material to be obtained (
For example, the amount can be set appropriately in consideration of the porosity, etc., but it is usually 0.1 to 20 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the resol type phenolic resin.

A mixture is prepared by mixing a resol-type phenolic resin, a water-soluble nickel compound, a curing agent, and a blowing agent as described above, and this mixture is introduced into a container of a desired shape.
By heating at a temperature of 0 to 120°C for 5 to 100 minutes, the foaming agent in the mixture vaporizes and expands, forming fine bubbles in the resin, as well as fine bubbles formed by the action of the curing agent. The resol type phenolic resin containing the water-soluble nickel compound is cured with bubbles remaining, and a porous cured body is formed.

By firing the porous cured body produced in this manner, the cured resin body forming the porous cured body is carbonized and at least a portion thereof is graphitized.

Firing can also be carried out by the usual method of raising the temperature continuously from room temperature to the firing temperature; It is desirable to employ a method of firing at a higher temperature than the above temperature (hereinafter sometimes simply referred to as "high temperature firing").

This low-temperature firing is usually performed by heating the porous cured body to a temperature of less than 2000° C. under conditions substantially free of oxygen. Especially low temperature firing temperature 750~15
It is preferable to set the porous hardened body within the range of 00°C.Also, for low temperature firing, the porous hardened body can be inserted into a firing furnace heated within the above range, but usually the porous hardened body is placed in a firing furnace etc. at room temperature. After loading the body, it is advantageous to employ a method of increasing the temperature to, for example, 0.1-b or 0.5-b formation temperature.

The temperature is raised as described above, and the porous cured body is heated and fired at the set low temperature firing temperature for 0 minutes to 10 hours.

In order to carbonize the porous cured body well by this low-temperature firing, the above-mentioned low-temperature firing is performed in an atmosphere substantially free of oxygen. Here, firing in an atmosphere substantially free of oxygen refers to This means that the porous cured body is not burnt out, such as in an inert atmosphere such as a nitrogen stream or an argon stream, or under reduced pressure.

By performing low-temperature firing in this manner, the resin components and the like constituting the porous cured body are carbonized.

After performing low-temperature firing in this manner, high-temperature firing is usually performed. This high-temperature firing is usually performed at a temperature of 1800°C or higher, preferably 2000°C or higher, in the same substantial absence of oxygen as described above. This is carried out by heating the above-mentioned low-temperature fired product at a temperature within the range of 3000°C.

The firing time in this high-temperature firing can be appropriately set in consideration of the low-temperature firing time and the degree of graphitization of the fired product, but is usually 10 hours or less, preferably 0.01 hours or less.
~10 hours.

In addition, the temperature increase rate when transitioning from low temperature firing to high temperature firing as described above is usually 1 to 2. Furthermore, after performing low temperature firing for a predetermined period of time, the temperature is raised at the temperature increase rate mentioned above to directly perform high temperature firing. Firing can be performed by heating to a high temperature, or firing can be performed by performing low-temperature firing, cooling once, and then heating to a high-temperature firing temperature at the above temperature increase rate.

By performing high-temperature firing in this manner, at least a portion of the porous hardened body carbonized by low-temperature firing is graphitized with bubbles remaining.

By performing high-temperature firing as described above, the carbonaceous porous body usually contains 1 to 50% ffi, preferably 5 to 2% ffi.
0% by weight of graphite is formed.

On the other hand, most of the water-soluble nickel compound used to prepare the porous cured product decomposes and decomposes during the high-temperature firing process.
It sublimates and is removed from the carbonaceous porous body. Therefore, the content of nickel component in the obtained carbonaceous porous body is usually 5001)l)1m or less, and the content of nickel can be reduced to 100% by firing under suitable conditions.
1) l) It is also possible to make it less than l.

As described above, since the affinity between the resol type phenolic resin and the water-soluble nickel compound is good, the water-soluble nickel compound can be dispersed very uniformly in the porous cured body of the resol type phenol resin. Therefore, by firing the porous cured body in which the water-soluble nickel compound is uniformly dispersed at a low temperature, graphite is uniformly distributed in the carbonized porous cured body. By firing such a carbonized porous hardened body at a high temperature, graphitization further progresses. The shrinkage rate of the body (carbonaceous porous body) decreases. Therefore, warpage or cracks are less likely to occur in the obtained carbonaceous porous body.

Furthermore, according to the method for producing a carbonaceous porous body of the present invention, the number of cells is higher than that of a carbonaceous porous body produced by a conventional method.
They tend to be smaller in size.

That is, the bubble size of the carbonaceous porous body obtained by the production method according to the present invention is approximately 1/3 to 1/10 of the bubble size of the carbonaceous porous body produced by the conventional method.

As described above, the carbonaceous porous body obtained by the production method according to the present invention has a small cell size, so that the carbonaceous porous body itself has excellent properties such as strength and heat insulation performance.

Note that no deterioration in pond characteristics was observed due to the use of the water-soluble nickel compound.

The carbonaceous porous body obtained in this manner can be used as a heat-resistant material such as a heat insulating material for a high-temperature furnace, in the same way as a carbonaceous porous body obtained by a conventional method.

[几匪五吃] According to the method for producing a carbonaceous porous material of the present invention, since the affinity between the water-soluble nickel compound and the resol-type phenolic resin is very good, The water-soluble nickel compound is very uniformly dispersed in the porous cured body. Therefore, by firing such a porous cured body, graphitization progresses well even at low temperatures, and the resulting carbonaceous porous body (Carbocell) can be used continuously at high temperatures for applications such as insulation. It is possible to effectively prevent warping or cracking caused by shrinkage due to progress of graphitization.

Next, the present invention will be explained by examples, but the present invention is not limited by these examples.

100 parts by weight of a resol-type phenolic resin obtained from euphenol and formaldehyde, 12 parts by weight of phenolsulfonic acid, 5 parts by weight of trichlorotrifluoroethane (Freon 113), and nickel chloride (molecular weight = 2).
38, Ni content = 24.8% by weight), the mixture was filled into a disposable cup, and heated for 60 minutes using an oven adjusted to 70°C to form a resol type phenolic resin. A porous cured body was prepared.

Although there was a tendency for the viscosity of the mixture to increase somewhat by adding nickel chloride, there was no change in the curing speed of the resol type phenolic resin, and nickel chloride was dispersed very uniformly throughout the resin. did.

Next, a prism with a side of 3 cm was cut out from this porous cured body, and this prism was placed in a firing furnace (normal pressure) in which the air inside was replaced with nitrogen gas, and heated at a heating rate of 5°C/min from room temperature. Do not raise the temperature to 1000℃.

In this manner, low temperature firing was performed by maintaining the temperature at 1000° C. for 30 minutes.

The low-temperature fired body obtained as described above was heated at a heating rate of 10'C/min from 1000°C under a nitrogen gas atmosphere for 23 hours.
The carbonaceous porous body of the present invention was manufactured by raising the temperature to 00°C and maintaining it at 2300°C for 30 minutes to perform high-temperature firing.

A carbonaceous porous body was produced in the same manner as in Example 1, except that the amount of nickel chloride was changed to 20 parts.

Although the viscosity of the composition increased considerably by adding nickel chloride, there was no particular problem with stirring, and the nickel chloride was able to be dispersed very uniformly throughout the resin. Further, no change was observed in the curing speed of the resol type phenolic resin.

A carbonaceous porous body was produced in the same manner as in Example 1 except that the amount of nickel chloride was changed to 5 parts by weight.

Although there was a tendency for the viscosity of the composition to slightly increase by blending nickel chloride, it was possible to disperse nickel chloride very uniformly throughout the resin. No change was observed in the curing speed of the resol type phenolic resin.

Shakutome Wataru A A carbonaceous porous body was produced in the same manner as in Example 1, except that nickel sulfate was used instead of nickel chloride, and the blended amount was 5 parts by weight.

Although nickel sulfate has a lower dispersibility than nickel chloride, it cannot be uniformly dispersed due to insufficient stirring for dispersion.

Furthermore, the curing performance and viscosity of the resol type phenolic resin did not change due to the addition of nickel sulfate.

A carbonaceous porous body was produced in the same manner as in Example 1, except that nickel sulfate was used instead of nickel chloride.

Fire pan 16 A carbonaceous porous body was produced in the same manner as in Example 1, except that nickel sulfate was used instead of nickel chloride, and the amount added was 20 parts by weight.

A carbonaceous porous body was produced in the same manner as in Example 1 except that nickel chloride was not used.

The carbonaceous porous bodies produced in Examples 1 to 6 and Comparative Example 1 were observed using a scanning electron microscope.

As a result, the average size of the bubbles constituting the carbonaceous porous bodies produced in Examples 1 to 6 was 20 μm. In contrast, the average diameter of the bubbles in the carbonaceous porous material produced in Comparative Example 1 was 60 μm, and the diameter distribution was wide and nonuniform.

In addition, the bubbles in the carbonaceous porous material obtained in the examples of the present invention were hardly destroyed, and the addition of the water-soluble nickel compound was found in the porous cured body or carbonaceous cured body of the resol type phenolic resin. It was confirmed that there was no inhibition of the formation of

X-ray diffraction analysis was performed on the carbonaceous porous bodies produced in Examples 1.5 and 6 and the carbonaceous porous body produced in Comparative Example 1 to measure the degree of graphitization.

The results are shown in Table 1.

Table 1

Claims (2)

[Claims] (1) A method for producing a carbonaceous porous body, which comprises firing a porous cured body of a resol-type phenol resin containing a water-soluble nickel compound to graphitize at least a portion of the porous cured body. (2) The method for producing a carbonaceous porous body according to claim 1, characterized in that the porous cured body is fired at a temperature of 2000° C. or higher.