JPH0867513A - Molecular sieve carbon and its production - Google Patents

Abstract

PURPOSE: To obtain high-quality molecular sieve carbon having uniform pore diameters. CONSTITUTION: A heated and pressurized molded article of a pulp fiber material containing a phenol resin is carbonized to give molecular sieve carbon having a whole pore volume of >=0.2ml/g, a ratio of ultramicro pore volume having <=10Å to the whole pore volume of >=75% and the center of the pore diameter distribution in the range of 3-5Å.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to porous carbon having a molecular sieving action, that is, molecular sieving carbon and a method for producing the same.

[0002]

2. Description of the Related Art Molecular sieve carbon has been used in hydrogen purification and nitrogen production processes because it has excellent heat resistance and chemical resistance and can be used even in the presence of polar substances. Further, in recent years, attention has been paid to its application to the separation and recovery of carbon dioxide and methane, and the recovery of carbon dioxide, in relation to the problem of global warming.

By the way, conventionally, there have been the following methods for producing molecular sieve carbon.

(1) Pyrolysis method: In general, a method of pyrolyzing and carbonizing wood, fruit shells, coal, or synthetic resins such as saran and vinylidene chloride.

(2) Heat shrinking method: A method in which fine porous carbonaceous material such as activated carbon, coke or Saran charcoal is fired at a high temperature to shrink the pores.

(3) Gas activation method: a method of gradually activating charcoal such as fruit shells, coal or synthetic resin under strict conditions to enlarge pores (for example, JP-A-53-11).
No. 95).

(4) Coating method: A method in which a resin or a tar-like polymer is added to a porous carbonaceous material for heat treatment and the pores are controlled by pyrolytic carbon (for example, JP-A-49-106982). , JP-A-59-45914).

(5) Vapor deposition method: 400 to 9 of various porous carbon materials
A method of reducing the pore size by heating to 00 ° C. and depositing pyrolytic carbon of a hydrocarbon gas such as benzene or toluene on the pore walls (for example, JP-A-56-130226).

However, in order to industrially produce molecular sieve carbon by the above-mentioned conventional method, a complicated step is required to control the pores on the carbon surface, and in the above-mentioned conventional method, like the case of zeolite type molecular sieve. However, it has been difficult to produce molecular sieve carbon having a uniform pore distribution.

Therefore, the present invention is intended to provide a method capable of inexpensively producing molecular sieve carbon having a uniform pore distribution and good quality.

[0011]

The molecular sieve carbon of the present invention can be obtained by carbonizing a heated and pressure-molded product of a pulp fiber body containing a phenol resin in an inert gas atmosphere.

Kraft paper, linter paper, recycled paper or the like can be used as the pulp fiber body containing the phenol resin.

Examples of the phenol resin include phenol / formaldehyde resin, phenols (phenol, cresol, alkylphenol, etc.), aldehydes (formalin, paraformaldehyde, etc.), plasticizers (tung oil, dehydrated castor oil, deer oil, phenol). A modified phenol resin containing a compounded oil or the like) can be used. The amount of aldehydes used is about 1.2 to 1.8 mol per mol of phenols.

As means for incorporating the above-mentioned phenol resin into the pulp fibrous body, a method of coating or impregnating a solution of the phenol resin, a reaction intermediate such as resistol (B stage) or prepolymer is mixed with the pulp for papermaking. There are ways.

The conditions for heating and pressurizing are temperature 13
The pressure is 0 to 170 ° C., the pressure is 50 to 100 Kgf / cm ² , and the time is about 40 to 120 minutes, for example, using a multi-stage hydraulic press machine.

The mixing ratio of the phenol resin contained in the heated and pressed molded product is preferably in the range of 23% by weight to 70% by weight, and when it is 23% by weight or less, delamination occurs and molding is difficult. If it exceeds 70% by weight, the ratio of the volume of the ultramicropores of 10Å or less becomes 75% or less after the carbonization treatment, and it becomes impossible to obtain high-quality molecular sieve carbon.

When the above-mentioned molded product is carbonized, it is crushed to an appropriate size with a hammer mill or the like, and then carbonized in an inert gas atmosphere such as N ₂ gas. The carbonization temperature is 600 to 900 ° C., preferably 650 to 800.
If it is outside the range, it is not possible to obtain a good quality molecular sieve carbon having a uniform pore size.

Even when the phenol resin molded product is made into a fine powder, granulated with a binder and then carbonized in an inert gas atmosphere such as N ₂ gas, the high-quality molecular sieve carbon of the present invention having a uniform pore size can be obtained. can get.

That is, the phenol resin molded product is finely pulverized and is preferably a fine powder having a particle size of about 0.1 to 300 μm, and most preferably a fine powder having a particle size of about 1 to 150 μm.

As the binder used for granulating and molding the fine powder of the phenol resin molded product, for example, polyvinyl alcohol, starch, water-soluble or water-swellable cellulose derivative, phenol resin, melamine resin, urea resin and the like thermosetting Resin, bentonite, coal tar, pitch and the like, water-soluble phenolic resin and melamine resin, in terms of hardness improvement of the granulated molded product and suitable micropore formation, and polyvinyl alcohol, granulation molding It is suitable in terms of workability. The water-soluble phenol resin is a self-heat-crosslinking resol resin having a molecular weight of 600 or less, which is usually rich in methylol groups, and contains 1.2 to 3.5 mol of aldehydes per mol of phenol in the presence of a slight excess of alkali catalyst. It is obtained by reacting with. The melamine resin is an initial condensate of melamine-formaldehyde and can be used as an aqueous solution. Furthermore, as polyvinyl alcohol,
Those having a degree of polymerization of 100 to 5,000 and a degree of saponification of 70% or more are preferably used. In the case of granulation molding, it is usually 20 to 10 with respect to 100 parts by weight of fine powder of a phenol resin molded product.
0 parts by weight of binder are used. The fine powder of the phenolic resin molded product and the binder are usually mixed with a ribbon mixer, a kneader, a Henschel mixer, etc., and the prepared homogeneous mixture is then granulated with a twin-screw wet extrusion granulator, a semi-dry disk pelleter, etc. It can be molded. Granulated granules have a diameter of 0.5-5 mm and a length of 1-
About 10 mm, in the case of spherical shape, the diameter is 0.5 to 10 mm
The degree is preferred.

The heat and pressure molded product of the pulp fibrous body containing the phenol resin is usually used to remove shavings adhering to the drill or press the burrs of the copper foil of the substrate during the drilling process of the printed wiring board. It is widely used for drilling jig plates and electrical insulating materials that are stacked on top and bottom of the board so that the copper foil surface of the board is not scratched. The jig plate for use is preferably used as a raw material for the molecular sieve carbon of the present invention.

[0022]

According to the above method, the total pore volume is 0.2 ml.
/ G or more and 10 Å or less of the ultra-micropore volume accounts for 75% or more of the total pore volume, and the center of the pore size distribution is 3
High quality molecular sieve carbon in the range of ~ 5Å can be obtained, and the reason is considered as follows.

First, a molded product obtained by heating and pressing a pulp fibrous body containing a phenol resin is used as a precursor for carbonization.

Such a heat and pressure molded product has a dense structure in which the phenol resin has penetrated into the pulp fiber, and when it is carbonized in an inert gas atmosphere, it does not yet result in carbonization. At (about 250 ° C.), the moisture in the pulp fiber (about 3% by weight to 7% by weight of the molded product) vaporizes and expands in volume, and this expansion causes many cracks in the molded product having a dense structure. , The water vapor escapes and the pore volume increases.

Subsequently, from about 290 ° C. during the temperature raising process, the pulp fibers are vaporized by thermal decomposition and expand in volume,
As a result, a crack is further generated inside the molded product of the phenol resin and the pulp fiber in the carbonization process, vaporized gas escapes from this crack, and the pore volume further expands.

Next, calcination of the carbide progresses by calcination in the carbonization process, and a large number of crack surfaces generated so far are fused with each other to form micropores.

[0027]

【Example】

(Example 1) <Production of Phenolic Resin Molded Article> After preparing a phenol resin varnish made of a water-soluble or alcohol-soluble resole resin, a resin is coated so that the coating resin amount is 30 parts by weight with respect to 70 parts by weight of a paper base material. Paper (basis weight: 200 g / m ² ) was applied and impregnated, and then dried at a temperature of 160 ° C. to prepare a prepreg. A large number of these prepregs were laminated, and the top and bottom of the laminate were sandwiched by stainless steel mirror plates, and cushioning materials were placed on both outer sides of the laminate, and the cushion plates were set between the hot plates of a multi-stage hydraulic press machine. In this state, the temperature 140
After hot pressing under conditions of ℃, pressure 70 kgf / cm ² and time 90 minutes, the plate is delaminated and the edges are trimmed to a thickness of 1.5 mm,
A phenol resin molded product having a size of 300 mm × 300 mm was obtained.

<Production of Molecular Sieve Carbon> This phenol resin molded product was roughly crushed to about 2.0 mm and heated at 10 ° C./min in a N ₂ gas atmosphere, and carbonized at 750 ° C. for 1 hour. I did. Specific surface area, total pore volume and pore volume of 10 Å or less are measured by BELSORP28 (manufactured by Bell Japan Ltd.) by BET multi-point method and Dollimore a
It was determined by applying the nd Heal method. Further, the pore diameter and the pore volume are determined by applying the Dubinin-Astakhov equation to the adsorption isotherms of four kinds of gases having different molecular diameters, and determining the ultimate adsorption volume of each gas. It was calculated as corresponding to the above volume.

Example 2 A phenolic resin molded product was pulverized to an average particle size of about 100 μm, and 100 parts by weight of a fine powder of phenolic resin was added to a water-soluble phenolic resin (Showa Polymer Co., Ltd., Shonor BRL-2854, 40 parts by weight of solid content concentration of 60 wt% and polyvinyl alcohol (Kuraray Co., Ltd., Poval 217, solid content concentration of 20 wt%)
%) In a kneader, and the mixed composition was extruded by a twin-screw extrusion granulator (Peretta Double, manufactured by Fuji Paudal Co., Ltd.). The granulated product obtained by extrusion was dried at 100 ° C. for 1 hour to obtain a granulated product of 2 mmφ × 3 mmL.

Carbide was obtained in the same manner as in Example 1 except that, instead of coarsely pulverizing the phenol resin molded article in Example 1, a fine powder of the phenol resin molded article was granulated with a binder. .

[Comparative Example 1] A carbide was obtained in the same manner as in Example 1 except that a commercially available phenol resin powder was used instead of coarsely pulverizing the phenol resin molded article in Example 1.

[Comparative Example 2] A carbide was obtained in the same manner as in Example 1 except that pulp (kraft paper) was used instead of coarsely crushing the phenol resin molded article in Example 1.

Table 1 shows the specific surface areas, the total pore volumes, and the pore volumes of 10 Å or less of Examples 1, 2 and Comparative Examples 1 and 2 which were obtained as described above. The distribution of the pore size of Example 1 is shown in FIG.

[0034]

[Table 1]

From Table 1, the carbon material manufactured using the phenol resin molded product occupies a pore volume of 10 Å or less as compared with the carbon material manufactured using the phenol resin powder or pulp (kraft paper) as a raw material. You can see that the ratio is high. Further, it can be seen from FIG. 1 that there is a sharp peak at 3.5 to 4.5 liters.

[0036]

As described above, according to the present invention, the ratio of the ultramicropore volume of the total pore volume of 0.2 ml / g or more and 10Å or less is 75% or more of the total pore volume, It is possible to obtain a good quality molecular sieve carbon having a pore size distribution center in the range of 3 to 5Å.

Further, according to the present invention, since the used product of the jig plate for drilling holes in the printed wiring board, that is, the industrial waste can be used as the raw material of the molecular sieve carbon, the molecular sieve carbon can be used. Can be manufactured at low cost and the industrial waste can be effectively used.

[Brief description of drawings]

FIG. 1 is a chart showing the distribution of pore volume in an example of the present invention.

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Claims (4)

[Claims] 1. A molecular sieve carbon obtained by carbonizing a heat-pressurized molded product of a pulp fiber body containing a phenol resin. 2. The total pore volume is 0.2 ml / g or more, 10
The molecular sieve carbon according to claim 1, wherein the proportion of the ultramicropore volume of Å or less is 75% or more of the total pore volume. 3. A method for producing molecular sieve carbon, which comprises carbonizing a heated and pressure-molded product of a pulp fiber body containing a phenol resin under an inert gas atmosphere. 4. The method for producing molecular sieve carbon according to claim 3, wherein the inert gas is N ₂ gas.