JPS6270215A - Production of molded carbon article - Google Patents

Abstract

PURPOSE:To produce a carbon material having both high strength and different porosities, by contact bonding plural cellulose sheets impregnated with a thermosetting resin in different amounts and firing the resultant bonded sheets under specific conditions to form a composite molded carbon article having the different porosities. CONSTITUTION:Cellulose sheets having respective >=90wt% cellulosic content are impregnated with a thermosetting resin, e.g. phenolic resin, in respective different amounts. The resultant plural sheets are contact bonded and fired in a nonoxidizing atmosphere at least 600 deg.C temperature to give a molded carbon article consisting of amorphous carbon called glassy carbon or graphite and fibrous carbon having a high strength. The porosity of a layer with a low impregnation ratio is 85-20% and the porosity of a layer with a high impregnation ratio is <=15% depending on the different in the impregnation amount of the thermosetting resin. Thereby, the aimed carbon material having both high strength and different porosities is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a carbon material, and more specifically, to a method for producing a carbon molded body by firing.

[Conventional technology]

Carbon materials have long been used as activated carbon and catalyst carriers, and plate-shaped materials have been used as gas distribution plates, furnace insulation materials, fuel cell separators, and the like.

Since carbon materials are inherently brittle materials, the problem is how to provide them with the necessary strength when used in actual industrial applications. In particular, in applications requiring a large surface area, the strength of the carbon material member is significantly reduced. When using a porous carbon material with a large specific surface area for activated carbon, gas dispersion plates, etc., the carbon material is inherently a brittle material, so its strength decreases significantly and the method of use One way to strengthen carbon material parts is to adopt a honeycomb structure.This method is applied to the production of activated carbon parts that require low gas flow resistance, but The process of manufacturing a honeycomb structure is very complicated.Also, there is a reinforcement method in which grooves are formed on a plate-shaped carbon material member.However, this method also requires a process of forming grooves after manufacturing the carbon plate. This is generally necessary and is not an advantageous method from a process standpoint.

[Problem that the invention seeks to solve]

Motoyama Ganjin is the patent application No. 1677-1983 and the patent application No. 1983-
No. 3149 proposed a method for manufacturing a high-strength carbon material, which involves impregnating a cellulose sheet with a sufficient amount of thermosetting resin, molding it, hardening it, and then firing it. Although the carbon material produced in this manner has high strength, it has almost no pores (open pores) and has a significantly small surface area. Therefore, in view of the fact that a method for producing a carbon material that has both high strength and porosity has not been provided, it is an object of the present invention to provide such a method for producing a carbon material.

[Means for Solving the Problems] The present invention impregnates a plurality of cellulose sheets or a plurality of sheets made of organic modified fibers for carbon fiber raw material with a thermosetting resin in different amounts, and then impregnates the plurality of sheets with a thermosetting resin in different amounts. By firing at a temperature of at least 600°C in a non-oxidizing atmosphere after pressing, the layer with a low impregnation amount has a porosity of 85 to 2.
The present invention is characterized in that it produces a composite carbon molded body having different porosity, in which the layer having a high impregnation amount has a porosity of 15% or less.

As the cellulose sheet used in the present invention, any ordinary paper other than processed paper such as art paper can be used, but in particular, paper with a cellulose content of 90% by weight or more such as filter paper, kraft paper, and linter paper can be used. Preferably.

Further, the organic fibers for carbon fiber raw materials used in the present invention are polyacrylonitrile, rayon, and coal tar pitch fibers treated to be infusible or flame-resistant, and these can be processed into sheets. Of course, these raw material fibers may be formed into a sheet and then subjected to infusibility treatment.

Furthermore, the thermosetting resin used in the present invention has a carbonizable organic substance such as a phenol resin, a furan resin, and a divinylbenzene resin as a main component.

The carbon molded body produced by the method of the present invention is made of amorphous carbon called glassy carbon, which has high hardness and good airtightness, and L< is made of graphite and high-strength fibrous carbon.

Furthermore, by varying the amount of thermosetting resin impregnated inside the laminate in the thickness direction, a composite carbon plate is obtained that includes a portion with a porosity of 15% or less and a portion with a porosity of 20 to 85%.

[For production]

If the entire carbon plate is made only of the carbon material with a porosity of 15% or less, the surface activity, air permeability, and porosity will be low.On the other hand, if the carbon plate is made only of the carbon material with a porosity of 20% or more, the carbon plate will be weak against bending. In the present invention, 1.
A dense portion having a porosity of 5% or less and a porous portion having a porosity of 20 to 85% are combined in the thickness direction. As a manufacturing method for such a composite carbon plate, it would be possible to manufacture each laminated part in advance using different molding conditions such as pressure and firing conditions such as temperature atmosphere, and then composite it. A significant advantage of the present invention is that composite carbon plates can be obtained simply by varying the amount of impregnation. Therefore, the present invention is configured to achieve such advantages. First, a thermosetting resin is used as the resin because such a resin does not have the problem of resin flowing out during the carbonization process after curing. This is also because the carbonized thermosetting resin has a glass-like appearance and has good airtightness. Furthermore, the reason why the firing is performed in a non-oxidizing atmosphere is to prevent the cellulose, organic modified fibers, or thermosetting resin from being burned. This purpose can be achieved by using not only an inert gas but also a coke filler or the like as the non-oxidizing atmosphere in the firing furnace. Firing temperature 60
The reason why the temperature is 0° C. or higher is for carbonization and high strength.

If it is preferable to increase the crystallinity of carbon in the product, 1
A graphite structure can be developed by heating at 000°C or higher.

The present invention will be explained in more detail below.

In the present invention, the amount of thermosetting resin impregnated is set to zero,
It is also possible to obtain a composite carbon plate containing a carbon material with extremely high porosity after firing. However, in this case, it is necessary to relatively increase the thickness of the cellulose sheet or modified organic fiber sheet that is impregnated with resin, or to increase the amount of resin impregnated therein. Applications of such composite carbon plates include plate-shaped activated carbon with a high adsorption rate, electrode plates for electrochemistry, and the like. below,
Unless otherwise specified, for manufacturing methods in which the amount of resin impregnation is not zero, the cellulose sheet or organic modified fiber sheet with a large amount of resin impregnation is referred to as sheet (A), and the cellulose sheet or organic modified fiber sheet with a small amount of resin impregnation is referred to as sheet (B). , give an explanation.

The amount of impregnation in the sheet (A) is preferably 40 to 12 (l vn) of the thermosetting resin, with the weight before yJ being 100. If the amount of impregnation is less than 40 parts, the strength after firing tends to be insufficient, and the weight before yJ is 100. If the amount of resin exceeds 100 mm, the resin will flow out when the mold hardens.When using cellulose-based paper with a small amount of residual carbon after firing, the smaller the amount of resin, the higher the strength after firing.

The amount of impregnation in the sheet (B) varies depending on the use of the carbon molded product, but an amount of impregnation of about 0.5 to 15 is suitable for the widest range of uses, taking the weight before impregnation as 100.

To make sheet CB), the paper-like material is quickly passed through a tank containing high-viscosity resin at a low temperature, and then the excess resin is removed by ironing or rolling, or further impregnation is performed. In order to obtain a sheet (B) with a stable quantity, it is immersed in a resin diluted with a solvent, passed through a roll at a constant pressure and at a constant speed, and then heated and dried.

Next, C) (A) and C) (B) are cured while being heat-pressed. When molding a flat composite, the desired number of sheets (A) and (B) are stacked together, sandwiched between flat heating plates, and the resin is heated under a pressure of 0.1 to 30 kg/cm. Cure under temperature conditions suitable for the type of resin.For example, in the case of phenolic resin, 140-150℃10
After heating for a minute and releasing the pressure to degas, the product is heated at 160° C. for 10 to 20 minutes while applying pressure again to harden and mold.

The method of laminating C) (A) and C) (B) depends on the use of the carbon molded product. For example, a combination of ABA is used when making a heat insulating wall for a furnace or an acoustic diaphragm, and AB or BAB is used when making a gas adsorption activated carbon plate or an electrode for large surface area electrochemical reaction. The thickness of each of the laminated sheets (A) and (B) also depends on the application. For the insulated walls of the furnace, the sheet (A) has a thickness of 0.1 to 1.0 mm, the sheet (B
) is 2 to 20 mm, sheet (A) for acoustic diaphragm
is 0°05~0.3 mm, sheet (B) is 0.5~5
Thicknesses in the range of mm are generally employed. In the case of electrodes, the sheet (A) is 0.3 to 11, and the sheet (B) is 0.3 to 11.
Thicknesses in the range 1-1 mm are generally employed. This thickness is the thickness before thermocompression bonding, and after thermocompression baking, it is 10
The thickness decreases in the range of ~35%. Furthermore, it goes without saying that the cellulose sheet for obtaining the thickness of Sheet (A) or Sheet (B) within the above range may be a stack of two or more cellulose sheets, if necessary. Furthermore, in sheets made of two or more sheets stacked one on top of the other, the amount of resin impregnated in each sheet is usually the same, but if you do not mind the complexity of the impregnation process where the amount of impregnation is changed for each sheet, the amount of resin impregnated can be changed for each sheet. It's okay.

The thermosetting resin-impregnated laminate obtained as described above is fired in a non-oxidizing atmosphere such as argon gas, CO gas, or argon+CO mixed gas.

At this time, if the laminate is sandwiched between fire-resistant plates and fired, it will be more effective in preventing the combustible components of the laminate from burning.
Deformation can be prevented. The fireproof plate is also used as a member that applies pressure to the laminate during firing and adjusts the density of the carbon molded body by adjusting the pressure.

When attempting to form a highly porous layer with a density of 0.3 or less, care must be taken to ensure that the pressure between the fire-resistant plates is less than Log/cm. After the refractory plate is used as a press-bonding plate during heat-press bonding for hardening and press-bonding is performed at a predetermined pressure, the pressure of the refractory plate can be adjusted in the firing step.

The above method is not limited to molding a flat plate-like molded article. For example, by preparing molds, you can make products of various shapes, such as tubes, spirals, rods, and trumpet shapes. for example,
When making a tubular insulation material, wrap sheet (A) and sheet (B) around a metal tube in the order of ABA, cover with heat shrink film, and blow hot air to wrap sheet (A) and sheet (B) into a metal tube. It can be molded by bringing it into close contact with the mold and holding it for about 60 minutes. After removing it from the mold, it can be buried in coke powder or the like and fired to obtain a double tubular molded body.

Furthermore, if activated carbon is required depending on the purpose of the carbon molded plate, heating the composite carbon plate in a steam or carbon dioxide atmosphere after firing will produce activated carbon with excellent gas and liquid adsorption properties.
- Generated in part (B).

According to the inventor's experiments, 12 parts of carbon dioxide, 2 parts of water vapor
Heating at 900°C for 60 minutes in an atmosphere of 8 parts
In order to investigate the surface activity of the composite carbon plate with B) activated, the surface area and pore volume were measured using the BET method using low-temperature nitrogen gas adsorption, and the surface area was 1280 m"/g and the pore volume was 0.85 ml/ g, equivalent to commercially available activated carbon.

〔Effect of the invention〕

According to the present invention, composite carbon plates having different porosities can be manufactured by a simple process, and composite carbon plates suitable for various uses can be freely manufactured.

Hereinafter, the performance of the composite carbon plate according to the present invention will be explained for each application.

If an ABA type composite carbon plate is used as an acoustic diaphragm, it is lightweight despite having high bending rigidity, and excellent tone characteristics can be obtained due to the high internal friction value characteristic of carbon composite materials.

In addition, when using a BAB type composite carbon plate in a phosphoric acid fuel cell, if a 2 mm wide groove is dug in the sheet (B) with a pinch 2III11, the sheet (B) will react with the phosphoric acid retention function. It has the function of a gas guide groove. Further, the sheet (A) portion has the function of a separator.

Conventionally, the electrode plate that also serves as gas dispersion for phosphoric acid fuel cells is
Porous carbon plates have low strength, so an expensive carbon fiber felt is grooved to form an electrode plate that supports phosphoric acid and disperses gas.0 A separator plate in which the composite carbon plate of the present invention is in contact with the felt. If used as an electrode and provided with a grooved surface as described above, the expensive carbon fiber nonwoven fabric will only function as an electrode. % reduction, making it possible to significantly reduce costs.

Moreover, the composite plate according to the present invention can also be used as an electrode for a battery. In this case, layer B is placed on the reaction surface, and layer A is placed on the opposite side to serve as a conductor and container wall, and primary and secondary batteries with the desired shape, such as flat, square, or cylindrical, are manufactured. be able to.

Further, by heating the sheet (B) portion of the composite carbon plate of the present invention in a steam or carbon dioxide atmosphere, activated carbon having excellent gas and liquid adsorption properties is produced, and the activated carbon is heated in the sheet (A) portion. A more firmly supported material can be obtained.

The present invention will be explained in detail below.

[Example 1] 100 parts by weight of 90 g/m'' linter was impregnated with 60 parts by weight of phenol resin (Showa Kobunshi Layer BRL-1202) and dried with hot air at 140°C for 3 minutes to form a prepreg sheet (
I made A). Next, a homogeneous linter was impregnated with 1 part of the above phenol resin diluted with 5 parts of acetone, and dried at 70°C for 2 hours and at 100°C for 30 minutes.
- I made (B). The amount of resin in the sheet (B) is 100
7 parts.

Next, sheet (A) and sheet (B) are 15cm x 30cm
Cut into 111 pieces, stack 1 A sheet, 5 B sheets, and 1 A sheet in that order, sandwich them between metal plates, and press under a press pressure of 7 kg/cm'' to 150 mm.
C. for 10 minutes and 170.degree. C. for 15 minutes to obtain a cured product with a thickness of 1.2i. This was sandwiched between a graphite plate and fired at 1100°C for 72 hours while applying a gravity of 2 g/cm.The obtained carbon composite plate was 10.5 cm x 21 cm, 0.8 R111+ thick, and a sheet (A ) part and the sheet (B) part each have a porosity of 7.5%.

57%, bending strength 780 kg/cm" elastic modulus 22
It was a smooth plate with a weight of 0.00 kg/mm'' and an average density of 0.95.

[Example 2] 8 sheets of Prepreg Sea (A) were stacked, 10 sheets of Sea 1- (B) were stacked on both sides, and the sheets were sandwiched between metal plate heaters and heated at 15 kg/cmz while applying a pressure of 15 kg/cmz.
After heating for 10 minutes at 0°C and 15 minutes at 170°C to harden the pressure, it was sandwiched between graphite plates and heated to 100°C over 96 hours under an inert atmosphere.
It was fired to 0°C. The resulting board has a bending strength of 770 kg
/cm”, average density 0.82.10.5cmX22c
It was a carbon plate with a thickness of 2.8 mm and porous on both sides.

The porosity of the sheet (A) part and the sheet (B) part was 6.9% and 61%, respectively.

[Example 3] Phenol resin (Showa Kobunshi type BLS741) 1 part diluted with 50 parts acetone to 300 g/m"
The mixture was impregnated into kraft paper, squeezed with a roll to remove excess liquid, and then dried with hot air at 110°C for 30 minutes. Resin impregnation amount is 0
．． It was 6wt%. This is prepreg sheet (B)
shall be.

Six sheets of prepreg sheets (A) treated in the same manner as in Example 1 were stacked and heated at 140 kg/ca+2 under a pressure of 100 kg/ca+2.
Pre-press for 1 minute at ℃, then apply pre-press on both sides
Stack two sheets of B) and put them on the metal plate heater again at 5kg/cm! 150°C for 10 minutes under pressure of 17
Heat at 0°C for 5 minutes, press and harden, 30cm x 30cm
A plate with a thickness of 2.6 mm was obtained. Sandwich this between graphite plates,
Baked at 950°C for 72 hours in an inert atmosphere,
A composite carbon plate having a size of 0.5 cm x 20.5 cn+ and a thickness of 1.41 mm was obtained. The bending strength of this composite carbon plate is 1040kg
/m stiffness 2, and sheet (A) part and sheet (B)
The porosity of the parts was 6.1% and 81%.

[Example 4] On the porous surface of the composite carbon plate of Example 2, square grooves with a depth of 0.8 mm and a width of 21 were cut in parallel every 2++u++ and at right angles on the front and back sides, and then immersed in a concentrated phosphoric acid solution. When it was pulled up and the change in weight was measured, it was found that it retained 60 mg/co+'' of phosphoric acid, indicating that it was a good phosphoric acid retainer for use in phosphoric acid fuel cells.

[Example 5] After activating the sheet (B) part of the composite carbon plate of Example 3, an air purifying device was created in which 10 composite carbon plates were arranged as shown in Figure 1, and the benzene-containing air was A purification test was conducted. Composite carbon plates 1 were arranged at intervals of 10 mm, and gaps 2 of 15 mm were alternately provided between the side surfaces and the case 3 to serve as air passages.

50pp of benzene by active both sides of each composite carbon plate 1
When the air containing r@ was purified at a flow rate of 0.15m3/min, the benzene concentration in the purified air was 10p.
pm, and almost no pressure drop was observed.

As described above, it was found that the adsorption rate was greatly improved when the activated composite carbon plate according to the present invention was used.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an air purifying device using a composite carbon plate according to the manufacturing method of the present invention. 1-Composite carbon plate, 2-Gap.

Claims (1)

[Scope of Claims] 1. Impregnating a plurality of cellulose sheets with a thermosetting resin in different amounts, pressing the plurality of cellulose sheets together, and then firing at a temperature of at least 600°C in a non-oxidizing atmosphere. As a result, the layer with low impregnation has a porosity of 85 to 2.
1. A method for manufacturing a carbon molded body, which comprises manufacturing a composite carbon molded body having different porosity, in which the layer having a high impregnation amount has a porosity of 15% or less. 2. After impregnating a plurality of sheets of organically modified fiber for carbon fiber raw material with a thermosetting resin in different amounts, and pressing the plurality of sheets together, at least
By firing at a temperature of 00°C, a composite carbon molded body with different porosity is produced, in which the layer with a low impregnated amount has a porosity of 80 to 20%, and the layer with a high impregnated amount has a porosity of 15% or less. A method for manufacturing a carbon molded body.