CA1309218C - Process for producing a carbonaceous thin plate by compressing pitch material between paper sheets - Google Patents
Process for producing a carbonaceous thin plate by compressing pitch material between paper sheetsInfo
- Publication number
- CA1309218C CA1309218C CA000515612A CA515612A CA1309218C CA 1309218 C CA1309218 C CA 1309218C CA 000515612 A CA000515612 A CA 000515612A CA 515612 A CA515612 A CA 515612A CA 1309218 C CA1309218 C CA 1309218C
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- carbonaceous
- paper
- raw material
- press
- thin plate
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/042—Electrodes formed of a single material
- C25B11/043—Carbon, e.g. diamond or graphene
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/52—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite
- C04B35/528—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite obtained from carbonaceous particles with or without other non-organic components
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/042—Electrodes formed of a single material
- C25B11/043—Carbon, e.g. diamond or graphene
- C25B11/044—Impregnation of carbon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/96—Carbon-based electrodes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Ceramic Engineering (AREA)
- Metallurgy (AREA)
- Manufacturing & Machinery (AREA)
- Structural Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Ceramic Products (AREA)
- Carbon And Carbon Compounds (AREA)
- Inorganic Fibers (AREA)
- Fuel Cell (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Disclosed herein is a process for producing a carbonaceous thin plate comprising disposing a composite material comprising a carbonaceous raw material which can be carbonized and solidifies after being softened by heating and paper-like substances which can be carbonized without melting, between the pressing-surfaces of a heating press, so as to sandwich said carbonaceous raw material between said paper-like substances and to contact said paper-like substances with each of the pressing-surfaces of said heating press, press-molding said composite material raising the temperature of said heating press successively heating the press-molded composite material under pressure, thereby carbonizing the press-molded composite material, and calcining the carbonized material under reduced-pressure or in an inert gas.
Disclosed herein is a process for producing a carbonaceous thin plate comprising disposing a composite material comprising a carbonaceous raw material which can be carbonized and solidifies after being softened by heating and paper-like substances which can be carbonized without melting, between the pressing-surfaces of a heating press, so as to sandwich said carbonaceous raw material between said paper-like substances and to contact said paper-like substances with each of the pressing-surfaces of said heating press, press-molding said composite material raising the temperature of said heating press successively heating the press-molded composite material under pressure, thereby carbonizing the press-molded composite material, and calcining the carbonized material under reduced-pressure or in an inert gas.
Description
~3~9~ L8 IITLE OF THE INVENTION
PROCESS ~OR PRODUCING A CARBONACEOUS
THIN PLAIE BY CO~PRESSING PlTCH MAl~RIAL
:BETWEEN PAPER sHEET3 BACKGROUND OF T~D3 INVENTION:
The present invention relates to a process for producing a carbonaceous thin plate, and more in detail, relates to a process for producing a carbonaceous thin plate of large size without crevices and cracks.
Since carbonaceous materials are excellent in heat-resistance, corrosion-resistance and electric conductivity, application of a carbonaceous thin plate which is dense and low in p~rmeability to gases and liquids to separators of phosphoric acid type fuel cells or electrodes for zinc-halogen accumulators has been tried, and the establishment of an industrial process for producing a carbonaceous thin plate of a large size has been desired.
1~ The carbonaceous thin plate according to the present invention may be used for the above-mentioned purposes and others, such as, electrodes for electrolysis, diaphragms for heat-resistant and corrosion-resistant heat e~changers.
Japanese Patent Application Laid-Open (KOKAI) No. 59-26907 (1984) (Kamijo et al.) discloses a graphite thin plate prepared by adding a liquid thermosetting resin to micronized graphite preliminarily treated at a temperature of at least 2,700C
and of not larger than 100 ~n in particle size, kneading the mi~cture thereby obtaining a paste, molding the paste into a thin plate shape by a roll-molding machinej hardening the molded thin plate by heating, for instance, by contacting~: ~ heated plal;es and bo~ sides of the thin plate under pressure, and subjecting the .
.
hardel~ed material to the conYentional heating and carbonizing treat~nent and a process of production $hereof.
Howe~er, in such a graphite thin plate, the adherence of the micronized graphite powders to the thermosetting resin is weak, and voids are apt to be formed in the interface therebetween when the paste is carbonized, and it has been deemed difficult to make the gas-permeability of the product lower than 1 x10-5 cmVs. Namely, such a graphite thin plate has a defect that the thickness ofthe plate must be large enough when high impermeability to gases is required.
Japanese Patent Application Laid-Open (KOKAI) No. 59-21512 (1984) Suda et al.
' discloses a process for producing a glass-like carbon thin plate, comprising mia~ing a chlorinated vinyl chloride resin and/or a vinyl chloride resi~ with a filran resin, kneading the mixture, molding the blend into a fikn or a sheet-like material, heat treating the molded body to obtain a carbon precursor, and calcining the carbon-precursor in an inert atmosphere.
Although the gas-permeability of the thus obtained thin plate is as small as 10-11 to 10-10 cm2/s (He, ~P = 1 atm.), since the carbonization yields of theresin in the steps of calcination and carbonization are small and the contraction rate of the material is large, it is e~tremely dif~lcult to produce a thin plate of large size without crevices and cracks, and with accurate dimensions. In addition, ~D since the resi~ as the raw material contains chlorine atoms, the chlorine atoms separate therefrom as stro~gly corrosive gaseous chlorine or hydrogen chloride, and accordingly, a special consideration for the construction and material of the apparatus is ~ecessary for ca~rying out the process.
n Japanese Patent Application Laid-Open (KOKAI) No. 58-150275 (1983) Yamada et al. a cell separator of fuel cells comprising a glass-like carbon produced by molding and carbonizing a liquid furan resin, liquid phenol resin or a mixture thereof is disclosed. ~lthough the gas-permeability of glass-like carbon is extremely low, ~L3~921~3 since it takes long time for producing it, its productivity is low resulting in a high production cost.
Although the production of the carbonaceous thin plate has been tried by each of the above-mentioned processes, there is another process wherein a carbonaceous thin plate is produced by carbonizing a carbonaceous raw material, which is carbonized and solidifies after being softened by heating under pressure with a heating press. Namely, a carbonaceous thin plate is produced by uniformly filling carbonaceous raw mater;al such as a pitch, etc. into a metal mold of a heating press, heating the carbonaceous raw material under pressure atI D a temperature at which the carbonaceous raw material is softened, calcining and carbonizing the carbonaceous raw material at a temperature up to about 600 C
under pressure, further calcining or graphitizing the thus carbonized material at predetermined temperature in a vacuum or in an inert gas.
In the above-mentioned process, the decomposition gas of the carbona~eous S- raw material generated at the carbonization under pressure with the heating press is scattered and released through the thin plate or through the interface between the thin plate and the pressing surface, or remains as bubbles within the thin plate. Accordingly, with increase of dimensions of the thin plate, it becomes difficult for the decomposition gas to scatter. As a result, the decomposition gas w remain as bubbles within the thirl plate and it becomes impossible to ob~ain adense carbonaceous thin plate. In addition, since the volume of the carbonaceousraw material such as a pitch, etc. is reduced by calcination and carbonization, the thin plate apts to contract in the direction parallel to its surface~ With increase of dimensions of the thin plate, a friction between the thin plate and the pressing-~ surface of the heating press is increased resulting in impossibility of contraction and finally an occurrence of crevices and cracks in the thin plate.
t -3-~ .
~L3~
Such phenomena are remarkable when a carbonaceous raw material which has a small carbonization yield and which undergoes large contraction during carbonization is used Accordingly, the carbonization is slowly carried out under pressure for a long time or the carbonaceous raw material is thermally treated before the carbonization to improve the carbonizatioll yield and to reduce an amount of thedecomposition gas 13owever, the above-mentioned processes are insufficient for the purpo~e.
As a result of the present inventors' studies for solving the problems of the above-mentioned conventional processes, it has been found that in the productionof a carbonaceous thin plate by carbonizing a carbonaceous raw material under pressure with a heating press, scattering of the decomposition gas is facilitated by interposing a paper-like substance, which can be carbonized without melting, between the carbonaceous raw material and the pressing surfaces of the heating press preventing an adhesion of the carbonaceous raw material to the pressing surface, and as a result the carbonaceous thin plate slides easily on the pressing surfaces, and the occurrence of crevices and cracks due to the contraction is prevented, and on the basis of those finding, the present inventors have attained the present invention.
~ Namely, the ~lrst object of the present invention is to provide a process which can commercially produce a dense carbonaceous thin plate of low permeability to gas or liquid, and of large size, for instance, about one meter in length and width, without crevices and cracks easily.
The second object of the present invention is to provide a carbonaceous thin - ~~ plate of large size not having crevices nor cracks.
~:U~ARY QFTHE INVENl~ON:
. .
~` ~L3~2~3L8 In a first aspect of the present inYention, t~ere is provided a process for producing a carbonaceous thin plate comprising, disposing a composite material comprising a carbonaceous raw material, which can be carbonized and solidifies after being softened by S heating, and paper -like substances which can be carbonized without melting, between the pressing-surfaces of a heating-press, so as to sandwich the carbonaceous raw material between the paper-like substances and to contact the paper-like substances with each of the pressing-surfaces of the heating press, 1~7 press-molding the composite material by raising the temperature of the heating press, successively heating the press-molded composite material under pressure to carbonize it, and calcining the carbonized material under reduced-pressure or in an inert 15 gas.
In a second aspect of the present invention, there is provided a carbonaceous thin plate produced by disposing a composite material comprising a carbonaceous raw material, which can be carbonized and solidifies after being softened by heating, and paper -like substances which can be carbonized without melting, betweenthepressing-surfaces of a heating-press, so as to sandwich the carbonaceous raw material between the paper-like substances and to contact the paper-like substances with each of the pressirlg-surfaces of the heating press, ~5 press-molding the composite material by raising the temperature of the heating press, ' ;
`:'' : ' ~. , ' 3L3~
successively heating the press-molded composite material under pressure to carbonize it, and calcining the carbonized material under reduced-pressure or in an inert gas.
D:E:TAILED DESCRIYIION OF THE INVENTION:
The constitutional feature of the present i~vention lies in a process for producing a carbonaceous thin plate wherein a carbonaceous raw material which can be carbonized and solidifies after being softened by heating is carbonized and press-molded with a heating press and the carbonized material is calcined / 0 successively, characterized in that a composite material of the carbonaceous raw material and paper-like substances which can be carbonized without meltin~ is disposed between the pressing-surfaces of a heating press, so as to sandwich thecarbonaceous raw material between the paper-like subs~nces and to contact the paper-like substances wit~ each of the pressing-surfaces of the heating press.
In the present invention, a carbonaceous raw material which can be carbonized after being sof~ened by heating is used, and it is ~ecessary to soften the raw ~aterial for molding first and then to sinter the molded material by heating and pressing in the carbonization step.
Practically, as the carbonaceous raw material of the present inve~tion, a ~0 pitch or a mixture of a pitch and a pulverized carbonaceous material may be mentioned. As the pitch, such as, a petroleum pitch, a coal pitch, a ma~erial produced by o~idizing a petroleum pitch or a coal pitch, a material produced by pitchfying the product obtained by o~idizing a coal tar, an asphalt, etc. may beused. On the other hand, as the pulverized carbonaceous material, for instance, ~' carbon black, pulverized coke, pulverized graphite etc. may be mentioned.
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In addition, as the carbonaceous raw materials, those }laving a high carbonization yield are preferable for producing a dense carbonaceous thin platebecause of the small amount of decomposition gas generated at the time of carbonization which is small enough not to form bubbles in the product, and those havingahigh carbonization yield are generally small in contraction on carbonization and those showing low contraction on carbonization hardly have the cre~ices and cracks. Howe~er, since the carbonaceous raw material having a high carbonization yield shows a high so~tening point and is di~lcult to plastically transform, such material generally has poor shaping and sintering properties.
Consequently, it is preferable to select the carbonaceous raw materials taking at least the above-mentioned situations into consideration. Although it is difficult to establish clear standards for the selection, those having a carbonization yield of 40 to 95% at a temperature up to 900C are preferable andaccordingly, the pitches mentioned above can preferably be used. Pul~erized 1~ carbonaceous material such as carbon black may be added to the raw materials ; for improving the carbonization yield and reducing the contraction of the raw material on carbonization. However, since an addition of such pulverized ~aterial in a large amount reduces the density, increases t~e pe~eability to gases and liquids, and reduces the strength of the obtained thin plate, the amount 2~ of addition of such pul~erized carbonaceous material is preferably less than half of the total amount of the raw material although it depends on the field of use of the product.
The process of the present inve~tion is put into practice by the steps of (1) inserting a paper-like substance, whi~ can be carbonized in a solid state without ~s~ melting, between a carbonaceous raw material such as pitch, and pressing surfaces of a heating press and (2) carbonizing the carbonaceous raw material and the paper-like substance by raising a temperature of the heating press slowly ~ .
~9~
wh;le applying pressure. A decomposition gas is generated from the carbonaceous raw material in the step of carbonization (the step of raising the temperature) and the generated decomposition gas is released easily outside the system through the paper-like substance inserted between the carbonaceous raw material and the pressing surfaces of the heating press. Accordingly, since the decomposition gas does not remain as bubbles within the thin plate, it is possible to produce a dense carbonaceous thin plate. The paper-like substance herein mentioned means the substance prepared by twisting vegetable fibers and other fibers and agglutinating thereof.
0 Since the paper-like substance is constituted by the twisted fibers, there exists voids making the substance permeable to gas.
In order t~at the paper-like substance may e~hibit the permeability to gas during the step ~f carbonization under pressure, it is necessary that the peper-like substance is carbonized in a solid state without melting, thereby retaining its 1~ permeability to gas.
In the conventional process of not inserting the paper-like substance, since the carbonaceous raw material contact directly with the pressing surfaces of theheating press and is softened without providiIlg any passage ~or the decomposition gas outside the system, it is dif~lcult to release the decomposition O gas and said gas is apt to remain as bubbles within the thin plate resulting in the culty of producing the dense carbonaceous thin plate.
Accord;ng to the process of the present invention, the direct contact of the carbonaceous raw material with the pressing surfaces is pre~ented by insertin~
the paper-like substance therebetweenJ and the paper-like substance is carbonized without melting, and consequently, the thin plate can easily slide onthe pressing surface without adhering thereto. Further, the paper-like substancecan release the decomposition gas from the system as described above.
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Accordingly, the process can provide the dense carbonaceous thin plate without crevices and cracks.
As the paper-like substance satisfying these purposes, a sheet of paper - manufactured from vegetable fibers by a known method is adequate for the purpose.
In addition, a sheet of paper manufactured mainly from vegetable ~lbers with a small amount of synthetic organic ~lbers can be used as far as the permeabilit~ of the carbonized sheet of paper to gas is not remarkably lowered by melting the synthetic organic fîbers in the step of carbonization under pressure.
/ As the synthetic organic fibers, those of polyethylene, polypropylene, rayon,acetate, polyvinyl alcohol, nylon, acrylate, polyester. etc. may be mentioned, and the amount of addition thereof is prefereably not more than 30% by weight of thetotal raw materials for the paper-like substance.
The paper-like substance used in the present invention is carbonized and 1~ remains as a part of the thin plate in the outer layer part thereof. Consequently, the density of the outer layer part of the thin plate is different from that of the inner part.
The thickness of the outer layer part depends on the thickness of the paper-like substance used. Although the thickness of the paper-like substance is ~0 determined considering a use of the thin plate, efficiency in the production and the economy in the production, it is preferable that the thickness of the papér-like substance is not more than 100 ~m.
In most of the papers produced at present, an inorganic substance such as a filler of terra alba, titanium oxide, etc. and pigments is added for the purpose of ~5~ densifying, opaquing and colorating the paper. For the purpose of the present inYention, a sheet of paper containing such an inorganic $ubstance is suitably used, however, depending on a use of the thin plate there is a case which is not , . .~ .
.;
preferable to contain such inorganic substance in it. Accordingly, the paper-like substance which has been manufactured without addition of inorganic substances such as fillers and pigments, and has not been sub~ected to a process such as a coating has a large permeability to gas and prevents the adhesion of the carbonaceous raw material to the metal mold, and is particularly preferable for use in the present i~vention.
As the method of inserting the paper-like substance betwee~ the carbonaceous raw material and the pressing surfaces of the heating press, eitherof the following two methods is adopted. I~ one method, a paper-like substance is disposed on the bottom of the lower metal mold of the press and after filling the pul~lerized carbonaceous raw material uniformly thereon, another paper-lil~e substance and an upper metal mold of the press are disposed in the order. In another method, the carbonaceous raw material is converted into a slurry or a solution with a solvent, a carbonizable supporting body is coated or impregnatedwith the slurry or solution, a shee~like carbonaceous raw material is produced by evaporating the sol~ent from the supporting body, a necessary number of the shee~like raw material are laminated, paper-like substances are combined above and below the laminated shee~like raw materials, and the combined material is put into the metal mold of the heating press.
As the carbonizable supporting body, those which are becoming one-body with the carbonaceous raw material after being carbonized, thereby mal~ing the carbonaceous thin plate, are preferable.
According to the present in~ention, the carbonaceous thin plate is produced by inserting the paper-like substance between the carbonaceous raw material and the pressing surfaces of the heating press, raising the temperature of the heating p~ess, press-molding the carbonaceous raw material and the paper-like substance '`;-gL3¢~ L8 and continuing the heating under pressure, thereby carbonizing the press-molded material.
As conditions of the press-molding, a pressure not more than 100 kg/cm2G, a temperature of 150 to 450C at which the carbonaceous raw material softens and a pressure-retaining time of 10 to 120 minutes are suitably used. It is preferable to carry out the carbonization under a pressure of 0.1 to 100 kg/cm2G, heating the raw material to a temperature of about 600 to 6~0C. Since the carbonization of the molded under pressure should be carried out without generating bubbles due to the generation of the decomposition gas from the raw / material which is still soft and also without bending the produced carbonaceous thin plate, it is necessary to carry out the carbonization by heating the heating press to a temperature of about 600 to 6~0C at which the carbonaceous raw material solidifies. The thin plate which has been heated to a temperature of about 600 to 650C under pressure, thereby having been carbonized, is taken out l~ from the press after cooling and after being interposed between the two flat and smooth graphite plates, the carboIlized thin plate is further calcined or graphitized under reduced pressure or in an inert gas to obtain the carbonaceousthin plate.
According to the process of the present invention which comprises ~0 disposing a composite material comprising a carbonaceous raw material which can be carbonized and solidifies af~er being softened by heating, and paper-likesubstances which can be carbonized without melting, between the pressing-surfaces of a heating press, so as to sandwich said carbonaceous raw material between said paper-like substances and to contact said paper-like substances with each of the pressing-surfaces of said heating press, press-molding said composite matenal by raising a temperature of said heating press and successively heating the press-molded composite material under pressure, thereby carbonizing the ;
:.
press-molding composite material, and calcining the carbonized material under reduced-pressure or in an inert gas. In other words! in the production of a carl~onaceous thin plate by carbonizing a carbonaceous raw material such as a pitch, etc. while pressing the carbonaceous raw material by a heating press, (1)inserting a paper-like substance, for instance, a sheet of paper made of Yegetable fibers which can be carbonized in a solid state without melting, between the car~onaceous raw material a~d the pressing surfaces of the heating press, thereby (2) releasing the decomposition gas generated at the carbonization of the raw material outside the system and (3) letting the decomposition gas not to 10 remain as bubbles within the carbonaceous thin plate, a dense carbonaceous thin plate of a large size is easily produced.
Also, according to a process of the present invention comprising disposing the paper-like substance on both sides of the carbonaceous raw material, therebyavoiding the direct contact and adherence of the carbonaceou~ raw material with the pressing surfaces of the heating press, facilitating the sliding of the carbonized thin plate along the pressing surface of the heating press, facilitating the easily shrinking of the carbonized thin plate with the progress of the carbonization and preventing the occurrence of crevices and cracks in the product, a carbonaceous thin plate of a large size is easily produced.
The present invention will be explained more in detail while referring to the non-limitative Examples and Comparative Example as follows:
In this connection, a softening point of the material and a permeation coefficient of the material to a gas are determined by the following methodsJ
respectively.
2~ Determination of the Softenin~Point of a Material:
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While using a KOKA-type flowtester (made by SHD!~AZU Works Co., Ltd.), one gram of a specimen pulverized to a size of not more than 250 }lm is filled up in a cylinder wh;ch is 1 cm2 in cross-sectional area and has a no~zle of 1 mm in diameter at the bottom thereof and the specimen is heated with a temperature S~ raising rate of 6CImin while applying a pressure of 10 l~g/cm2G on the specimen.
With the raising of the temperature, although the packing rate of the specimen in the cylinder increases by a softening of the specimen, the reduction of thé volume of the specimen stops over a certain temperature. The temperature at which the reduction of the volume of the powdery specimen stops is defined as the /o softening point of the specime~.
Determination of the ~as PermeabilitY of a sPecimen:
.
The gas permeability of a specimen is determined in conformity to "Method for determination of the mobility of oxygen gas through a plastic film and sheet"
of ASTM I)-3985-81, Namely, while flowing gaseous nitrogen along one side of /~ the specimen (a thin plate) to intercept an oxygen gas permeation from an atmosphere thereinto and introducing o~ygen gas of 100% in purity into the otherside of the specimen, the amount of the o~ygen gas which permeates and passes through the specimen into the nitrogen gas side is determined by an electricallyquantifiable method using an oxygen sensor. In addition, as the carbonaceous ~7 thin plate of the present illvention has a uniform quality all over, the rate of gas-permeability [cm3(s~T~p~)lcm2.s] is multiplied by the thickness of the specimen (unit: cm) to obtain the gas permeation coefficient (cm2ls; O2, ~P--1 atm.).
EXAMPLE 1:
An ethylene bottom oil was pitchfied by thermally treating the oil for 3 zs~ hours at 370C, thereby promoting the polymerization and condensation reaction ~- - 13 -;
iL8 of the oil, and at the same time, removing the low-boiling components therefrom,and the produced pitch was pulverized into particles of not more than 100 ~m size and was heated to 190C at a rate of 10C/hour in air to obtain a pitch (A) which showed a softening point of 285C and a carbonization yield of 72% by weight under calcination at 900C.
Pitch (B) was produced by thermally treating pitch (A) for 2 hours in gaseous nitrogen atmosphere at 400C and showed a softening point of 314C and a carbonization yield of 82% by weight under calcination at 900C.
On the bottom of a lower metal mold (600 mm x 600 mm) of a heating press, ~d a sheet of paper of 35 ~m thickness which was manufactured from pulp without an addition of any inorganic substances was disposed, a carbonaceous raw material prepared by uniformly mixing pitch (A) and pitch (B) in a weight ratio of 1:1 in a Henschel mixer was introduced on the sheet of paper in the lower mold uniformly, and after covering the combined material with a sheet of the paper, an /~~ upper metal mold of the heating press was lowered. The heating press was heated to 380C at a rate of 100C/hour, and after pressing the content for 30 minutes under a pressure of 15 kg/cm2~, the pressure was reduced to 2 kg/cm2G and the press was further heated to 600C at a rate of 50C/hour and was cooled to obtain a thin plate.
~ The obtained thin plate was interposed between the two flat and smooth graphite plates and then was calci~ed in a vacuum oven at 2,000C. Thereby, a dense carbonaceous thin plate having no crevices and cracks was obtained.
The specific properties of the obtained carbonaceous thin plate are shown in Table 1.
... ..
PROCESS ~OR PRODUCING A CARBONACEOUS
THIN PLAIE BY CO~PRESSING PlTCH MAl~RIAL
:BETWEEN PAPER sHEET3 BACKGROUND OF T~D3 INVENTION:
The present invention relates to a process for producing a carbonaceous thin plate, and more in detail, relates to a process for producing a carbonaceous thin plate of large size without crevices and cracks.
Since carbonaceous materials are excellent in heat-resistance, corrosion-resistance and electric conductivity, application of a carbonaceous thin plate which is dense and low in p~rmeability to gases and liquids to separators of phosphoric acid type fuel cells or electrodes for zinc-halogen accumulators has been tried, and the establishment of an industrial process for producing a carbonaceous thin plate of a large size has been desired.
1~ The carbonaceous thin plate according to the present invention may be used for the above-mentioned purposes and others, such as, electrodes for electrolysis, diaphragms for heat-resistant and corrosion-resistant heat e~changers.
Japanese Patent Application Laid-Open (KOKAI) No. 59-26907 (1984) (Kamijo et al.) discloses a graphite thin plate prepared by adding a liquid thermosetting resin to micronized graphite preliminarily treated at a temperature of at least 2,700C
and of not larger than 100 ~n in particle size, kneading the mi~cture thereby obtaining a paste, molding the paste into a thin plate shape by a roll-molding machinej hardening the molded thin plate by heating, for instance, by contacting~: ~ heated plal;es and bo~ sides of the thin plate under pressure, and subjecting the .
.
hardel~ed material to the conYentional heating and carbonizing treat~nent and a process of production $hereof.
Howe~er, in such a graphite thin plate, the adherence of the micronized graphite powders to the thermosetting resin is weak, and voids are apt to be formed in the interface therebetween when the paste is carbonized, and it has been deemed difficult to make the gas-permeability of the product lower than 1 x10-5 cmVs. Namely, such a graphite thin plate has a defect that the thickness ofthe plate must be large enough when high impermeability to gases is required.
Japanese Patent Application Laid-Open (KOKAI) No. 59-21512 (1984) Suda et al.
' discloses a process for producing a glass-like carbon thin plate, comprising mia~ing a chlorinated vinyl chloride resin and/or a vinyl chloride resi~ with a filran resin, kneading the mixture, molding the blend into a fikn or a sheet-like material, heat treating the molded body to obtain a carbon precursor, and calcining the carbon-precursor in an inert atmosphere.
Although the gas-permeability of the thus obtained thin plate is as small as 10-11 to 10-10 cm2/s (He, ~P = 1 atm.), since the carbonization yields of theresin in the steps of calcination and carbonization are small and the contraction rate of the material is large, it is e~tremely dif~lcult to produce a thin plate of large size without crevices and cracks, and with accurate dimensions. In addition, ~D since the resi~ as the raw material contains chlorine atoms, the chlorine atoms separate therefrom as stro~gly corrosive gaseous chlorine or hydrogen chloride, and accordingly, a special consideration for the construction and material of the apparatus is ~ecessary for ca~rying out the process.
n Japanese Patent Application Laid-Open (KOKAI) No. 58-150275 (1983) Yamada et al. a cell separator of fuel cells comprising a glass-like carbon produced by molding and carbonizing a liquid furan resin, liquid phenol resin or a mixture thereof is disclosed. ~lthough the gas-permeability of glass-like carbon is extremely low, ~L3~921~3 since it takes long time for producing it, its productivity is low resulting in a high production cost.
Although the production of the carbonaceous thin plate has been tried by each of the above-mentioned processes, there is another process wherein a carbonaceous thin plate is produced by carbonizing a carbonaceous raw material, which is carbonized and solidifies after being softened by heating under pressure with a heating press. Namely, a carbonaceous thin plate is produced by uniformly filling carbonaceous raw mater;al such as a pitch, etc. into a metal mold of a heating press, heating the carbonaceous raw material under pressure atI D a temperature at which the carbonaceous raw material is softened, calcining and carbonizing the carbonaceous raw material at a temperature up to about 600 C
under pressure, further calcining or graphitizing the thus carbonized material at predetermined temperature in a vacuum or in an inert gas.
In the above-mentioned process, the decomposition gas of the carbona~eous S- raw material generated at the carbonization under pressure with the heating press is scattered and released through the thin plate or through the interface between the thin plate and the pressing surface, or remains as bubbles within the thin plate. Accordingly, with increase of dimensions of the thin plate, it becomes difficult for the decomposition gas to scatter. As a result, the decomposition gas w remain as bubbles within the thirl plate and it becomes impossible to ob~ain adense carbonaceous thin plate. In addition, since the volume of the carbonaceousraw material such as a pitch, etc. is reduced by calcination and carbonization, the thin plate apts to contract in the direction parallel to its surface~ With increase of dimensions of the thin plate, a friction between the thin plate and the pressing-~ surface of the heating press is increased resulting in impossibility of contraction and finally an occurrence of crevices and cracks in the thin plate.
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Such phenomena are remarkable when a carbonaceous raw material which has a small carbonization yield and which undergoes large contraction during carbonization is used Accordingly, the carbonization is slowly carried out under pressure for a long time or the carbonaceous raw material is thermally treated before the carbonization to improve the carbonizatioll yield and to reduce an amount of thedecomposition gas 13owever, the above-mentioned processes are insufficient for the purpo~e.
As a result of the present inventors' studies for solving the problems of the above-mentioned conventional processes, it has been found that in the productionof a carbonaceous thin plate by carbonizing a carbonaceous raw material under pressure with a heating press, scattering of the decomposition gas is facilitated by interposing a paper-like substance, which can be carbonized without melting, between the carbonaceous raw material and the pressing surfaces of the heating press preventing an adhesion of the carbonaceous raw material to the pressing surface, and as a result the carbonaceous thin plate slides easily on the pressing surfaces, and the occurrence of crevices and cracks due to the contraction is prevented, and on the basis of those finding, the present inventors have attained the present invention.
~ Namely, the ~lrst object of the present invention is to provide a process which can commercially produce a dense carbonaceous thin plate of low permeability to gas or liquid, and of large size, for instance, about one meter in length and width, without crevices and cracks easily.
The second object of the present invention is to provide a carbonaceous thin - ~~ plate of large size not having crevices nor cracks.
~:U~ARY QFTHE INVENl~ON:
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~` ~L3~2~3L8 In a first aspect of the present inYention, t~ere is provided a process for producing a carbonaceous thin plate comprising, disposing a composite material comprising a carbonaceous raw material, which can be carbonized and solidifies after being softened by S heating, and paper -like substances which can be carbonized without melting, between the pressing-surfaces of a heating-press, so as to sandwich the carbonaceous raw material between the paper-like substances and to contact the paper-like substances with each of the pressing-surfaces of the heating press, 1~7 press-molding the composite material by raising the temperature of the heating press, successively heating the press-molded composite material under pressure to carbonize it, and calcining the carbonized material under reduced-pressure or in an inert 15 gas.
In a second aspect of the present invention, there is provided a carbonaceous thin plate produced by disposing a composite material comprising a carbonaceous raw material, which can be carbonized and solidifies after being softened by heating, and paper -like substances which can be carbonized without melting, betweenthepressing-surfaces of a heating-press, so as to sandwich the carbonaceous raw material between the paper-like substances and to contact the paper-like substances with each of the pressirlg-surfaces of the heating press, ~5 press-molding the composite material by raising the temperature of the heating press, ' ;
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successively heating the press-molded composite material under pressure to carbonize it, and calcining the carbonized material under reduced-pressure or in an inert gas.
D:E:TAILED DESCRIYIION OF THE INVENTION:
The constitutional feature of the present i~vention lies in a process for producing a carbonaceous thin plate wherein a carbonaceous raw material which can be carbonized and solidifies after being softened by heating is carbonized and press-molded with a heating press and the carbonized material is calcined / 0 successively, characterized in that a composite material of the carbonaceous raw material and paper-like substances which can be carbonized without meltin~ is disposed between the pressing-surfaces of a heating press, so as to sandwich thecarbonaceous raw material between the paper-like subs~nces and to contact the paper-like substances wit~ each of the pressing-surfaces of the heating press.
In the present invention, a carbonaceous raw material which can be carbonized after being sof~ened by heating is used, and it is ~ecessary to soften the raw ~aterial for molding first and then to sinter the molded material by heating and pressing in the carbonization step.
Practically, as the carbonaceous raw material of the present inve~tion, a ~0 pitch or a mixture of a pitch and a pulverized carbonaceous material may be mentioned. As the pitch, such as, a petroleum pitch, a coal pitch, a ma~erial produced by o~idizing a petroleum pitch or a coal pitch, a material produced by pitchfying the product obtained by o~idizing a coal tar, an asphalt, etc. may beused. On the other hand, as the pulverized carbonaceous material, for instance, ~' carbon black, pulverized coke, pulverized graphite etc. may be mentioned.
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In addition, as the carbonaceous raw materials, those }laving a high carbonization yield are preferable for producing a dense carbonaceous thin platebecause of the small amount of decomposition gas generated at the time of carbonization which is small enough not to form bubbles in the product, and those havingahigh carbonization yield are generally small in contraction on carbonization and those showing low contraction on carbonization hardly have the cre~ices and cracks. Howe~er, since the carbonaceous raw material having a high carbonization yield shows a high so~tening point and is di~lcult to plastically transform, such material generally has poor shaping and sintering properties.
Consequently, it is preferable to select the carbonaceous raw materials taking at least the above-mentioned situations into consideration. Although it is difficult to establish clear standards for the selection, those having a carbonization yield of 40 to 95% at a temperature up to 900C are preferable andaccordingly, the pitches mentioned above can preferably be used. Pul~erized 1~ carbonaceous material such as carbon black may be added to the raw materials ; for improving the carbonization yield and reducing the contraction of the raw material on carbonization. However, since an addition of such pulverized ~aterial in a large amount reduces the density, increases t~e pe~eability to gases and liquids, and reduces the strength of the obtained thin plate, the amount 2~ of addition of such pul~erized carbonaceous material is preferably less than half of the total amount of the raw material although it depends on the field of use of the product.
The process of the present inve~tion is put into practice by the steps of (1) inserting a paper-like substance, whi~ can be carbonized in a solid state without ~s~ melting, between a carbonaceous raw material such as pitch, and pressing surfaces of a heating press and (2) carbonizing the carbonaceous raw material and the paper-like substance by raising a temperature of the heating press slowly ~ .
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wh;le applying pressure. A decomposition gas is generated from the carbonaceous raw material in the step of carbonization (the step of raising the temperature) and the generated decomposition gas is released easily outside the system through the paper-like substance inserted between the carbonaceous raw material and the pressing surfaces of the heating press. Accordingly, since the decomposition gas does not remain as bubbles within the thin plate, it is possible to produce a dense carbonaceous thin plate. The paper-like substance herein mentioned means the substance prepared by twisting vegetable fibers and other fibers and agglutinating thereof.
0 Since the paper-like substance is constituted by the twisted fibers, there exists voids making the substance permeable to gas.
In order t~at the paper-like substance may e~hibit the permeability to gas during the step ~f carbonization under pressure, it is necessary that the peper-like substance is carbonized in a solid state without melting, thereby retaining its 1~ permeability to gas.
In the conventional process of not inserting the paper-like substance, since the carbonaceous raw material contact directly with the pressing surfaces of theheating press and is softened without providiIlg any passage ~or the decomposition gas outside the system, it is dif~lcult to release the decomposition O gas and said gas is apt to remain as bubbles within the thin plate resulting in the culty of producing the dense carbonaceous thin plate.
Accord;ng to the process of the present invention, the direct contact of the carbonaceous raw material with the pressing surfaces is pre~ented by insertin~
the paper-like substance therebetweenJ and the paper-like substance is carbonized without melting, and consequently, the thin plate can easily slide onthe pressing surface without adhering thereto. Further, the paper-like substancecan release the decomposition gas from the system as described above.
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Accordingly, the process can provide the dense carbonaceous thin plate without crevices and cracks.
As the paper-like substance satisfying these purposes, a sheet of paper - manufactured from vegetable fibers by a known method is adequate for the purpose.
In addition, a sheet of paper manufactured mainly from vegetable ~lbers with a small amount of synthetic organic ~lbers can be used as far as the permeabilit~ of the carbonized sheet of paper to gas is not remarkably lowered by melting the synthetic organic fîbers in the step of carbonization under pressure.
/ As the synthetic organic fibers, those of polyethylene, polypropylene, rayon,acetate, polyvinyl alcohol, nylon, acrylate, polyester. etc. may be mentioned, and the amount of addition thereof is prefereably not more than 30% by weight of thetotal raw materials for the paper-like substance.
The paper-like substance used in the present invention is carbonized and 1~ remains as a part of the thin plate in the outer layer part thereof. Consequently, the density of the outer layer part of the thin plate is different from that of the inner part.
The thickness of the outer layer part depends on the thickness of the paper-like substance used. Although the thickness of the paper-like substance is ~0 determined considering a use of the thin plate, efficiency in the production and the economy in the production, it is preferable that the thickness of the papér-like substance is not more than 100 ~m.
In most of the papers produced at present, an inorganic substance such as a filler of terra alba, titanium oxide, etc. and pigments is added for the purpose of ~5~ densifying, opaquing and colorating the paper. For the purpose of the present inYention, a sheet of paper containing such an inorganic $ubstance is suitably used, however, depending on a use of the thin plate there is a case which is not , . .~ .
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preferable to contain such inorganic substance in it. Accordingly, the paper-like substance which has been manufactured without addition of inorganic substances such as fillers and pigments, and has not been sub~ected to a process such as a coating has a large permeability to gas and prevents the adhesion of the carbonaceous raw material to the metal mold, and is particularly preferable for use in the present i~vention.
As the method of inserting the paper-like substance betwee~ the carbonaceous raw material and the pressing surfaces of the heating press, eitherof the following two methods is adopted. I~ one method, a paper-like substance is disposed on the bottom of the lower metal mold of the press and after filling the pul~lerized carbonaceous raw material uniformly thereon, another paper-lil~e substance and an upper metal mold of the press are disposed in the order. In another method, the carbonaceous raw material is converted into a slurry or a solution with a solvent, a carbonizable supporting body is coated or impregnatedwith the slurry or solution, a shee~like carbonaceous raw material is produced by evaporating the sol~ent from the supporting body, a necessary number of the shee~like raw material are laminated, paper-like substances are combined above and below the laminated shee~like raw materials, and the combined material is put into the metal mold of the heating press.
As the carbonizable supporting body, those which are becoming one-body with the carbonaceous raw material after being carbonized, thereby mal~ing the carbonaceous thin plate, are preferable.
According to the present in~ention, the carbonaceous thin plate is produced by inserting the paper-like substance between the carbonaceous raw material and the pressing surfaces of the heating press, raising the temperature of the heating p~ess, press-molding the carbonaceous raw material and the paper-like substance '`;-gL3¢~ L8 and continuing the heating under pressure, thereby carbonizing the press-molded material.
As conditions of the press-molding, a pressure not more than 100 kg/cm2G, a temperature of 150 to 450C at which the carbonaceous raw material softens and a pressure-retaining time of 10 to 120 minutes are suitably used. It is preferable to carry out the carbonization under a pressure of 0.1 to 100 kg/cm2G, heating the raw material to a temperature of about 600 to 6~0C. Since the carbonization of the molded under pressure should be carried out without generating bubbles due to the generation of the decomposition gas from the raw / material which is still soft and also without bending the produced carbonaceous thin plate, it is necessary to carry out the carbonization by heating the heating press to a temperature of about 600 to 6~0C at which the carbonaceous raw material solidifies. The thin plate which has been heated to a temperature of about 600 to 650C under pressure, thereby having been carbonized, is taken out l~ from the press after cooling and after being interposed between the two flat and smooth graphite plates, the carboIlized thin plate is further calcined or graphitized under reduced pressure or in an inert gas to obtain the carbonaceousthin plate.
According to the process of the present invention which comprises ~0 disposing a composite material comprising a carbonaceous raw material which can be carbonized and solidifies af~er being softened by heating, and paper-likesubstances which can be carbonized without melting, between the pressing-surfaces of a heating press, so as to sandwich said carbonaceous raw material between said paper-like substances and to contact said paper-like substances with each of the pressing-surfaces of said heating press, press-molding said composite matenal by raising a temperature of said heating press and successively heating the press-molded composite material under pressure, thereby carbonizing the ;
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press-molding composite material, and calcining the carbonized material under reduced-pressure or in an inert gas. In other words! in the production of a carl~onaceous thin plate by carbonizing a carbonaceous raw material such as a pitch, etc. while pressing the carbonaceous raw material by a heating press, (1)inserting a paper-like substance, for instance, a sheet of paper made of Yegetable fibers which can be carbonized in a solid state without melting, between the car~onaceous raw material a~d the pressing surfaces of the heating press, thereby (2) releasing the decomposition gas generated at the carbonization of the raw material outside the system and (3) letting the decomposition gas not to 10 remain as bubbles within the carbonaceous thin plate, a dense carbonaceous thin plate of a large size is easily produced.
Also, according to a process of the present invention comprising disposing the paper-like substance on both sides of the carbonaceous raw material, therebyavoiding the direct contact and adherence of the carbonaceou~ raw material with the pressing surfaces of the heating press, facilitating the sliding of the carbonized thin plate along the pressing surface of the heating press, facilitating the easily shrinking of the carbonized thin plate with the progress of the carbonization and preventing the occurrence of crevices and cracks in the product, a carbonaceous thin plate of a large size is easily produced.
The present invention will be explained more in detail while referring to the non-limitative Examples and Comparative Example as follows:
In this connection, a softening point of the material and a permeation coefficient of the material to a gas are determined by the following methodsJ
respectively.
2~ Determination of the Softenin~Point of a Material:
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While using a KOKA-type flowtester (made by SHD!~AZU Works Co., Ltd.), one gram of a specimen pulverized to a size of not more than 250 }lm is filled up in a cylinder wh;ch is 1 cm2 in cross-sectional area and has a no~zle of 1 mm in diameter at the bottom thereof and the specimen is heated with a temperature S~ raising rate of 6CImin while applying a pressure of 10 l~g/cm2G on the specimen.
With the raising of the temperature, although the packing rate of the specimen in the cylinder increases by a softening of the specimen, the reduction of thé volume of the specimen stops over a certain temperature. The temperature at which the reduction of the volume of the powdery specimen stops is defined as the /o softening point of the specime~.
Determination of the ~as PermeabilitY of a sPecimen:
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The gas permeability of a specimen is determined in conformity to "Method for determination of the mobility of oxygen gas through a plastic film and sheet"
of ASTM I)-3985-81, Namely, while flowing gaseous nitrogen along one side of /~ the specimen (a thin plate) to intercept an oxygen gas permeation from an atmosphere thereinto and introducing o~ygen gas of 100% in purity into the otherside of the specimen, the amount of the o~ygen gas which permeates and passes through the specimen into the nitrogen gas side is determined by an electricallyquantifiable method using an oxygen sensor. In addition, as the carbonaceous ~7 thin plate of the present illvention has a uniform quality all over, the rate of gas-permeability [cm3(s~T~p~)lcm2.s] is multiplied by the thickness of the specimen (unit: cm) to obtain the gas permeation coefficient (cm2ls; O2, ~P--1 atm.).
EXAMPLE 1:
An ethylene bottom oil was pitchfied by thermally treating the oil for 3 zs~ hours at 370C, thereby promoting the polymerization and condensation reaction ~- - 13 -;
iL8 of the oil, and at the same time, removing the low-boiling components therefrom,and the produced pitch was pulverized into particles of not more than 100 ~m size and was heated to 190C at a rate of 10C/hour in air to obtain a pitch (A) which showed a softening point of 285C and a carbonization yield of 72% by weight under calcination at 900C.
Pitch (B) was produced by thermally treating pitch (A) for 2 hours in gaseous nitrogen atmosphere at 400C and showed a softening point of 314C and a carbonization yield of 82% by weight under calcination at 900C.
On the bottom of a lower metal mold (600 mm x 600 mm) of a heating press, ~d a sheet of paper of 35 ~m thickness which was manufactured from pulp without an addition of any inorganic substances was disposed, a carbonaceous raw material prepared by uniformly mixing pitch (A) and pitch (B) in a weight ratio of 1:1 in a Henschel mixer was introduced on the sheet of paper in the lower mold uniformly, and after covering the combined material with a sheet of the paper, an /~~ upper metal mold of the heating press was lowered. The heating press was heated to 380C at a rate of 100C/hour, and after pressing the content for 30 minutes under a pressure of 15 kg/cm2~, the pressure was reduced to 2 kg/cm2G and the press was further heated to 600C at a rate of 50C/hour and was cooled to obtain a thin plate.
~ The obtained thin plate was interposed between the two flat and smooth graphite plates and then was calci~ed in a vacuum oven at 2,000C. Thereby, a dense carbonaceous thin plate having no crevices and cracks was obtained.
The specific properties of the obtained carbonaceous thin plate are shown in Table 1.
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3¢~9~ 8 Thickness ApparentGas PeImeation Specific Bending (r~) Density Coefficient Resistance Strength (g/cm3) (cmVs) (Ohm cm) (kg/cm2) :~
~ v~ 1.1 2.05 3.04 x 10-8 2.33 x 10-3_ 1,980 , COMPARA~IVE EXA~LE:
In the same manner as in Example 1 except for not inserting the sheets of paper between the carbonaceous raw material and the pressing surfaces of the heating press, a carbonaceous thin plate was produced.
/ It was found that the produced thin plate was splitted into a mosaic-like state in the metal mold, and a number of bubbles were observed in splitted pieces of the thin plate.
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EXAMPLE 2:
Pitch (C) having a softening point of 224C and a carbonization yield of 69%
/~~ by weight under calcination at 900C was produced by thermally treating an ethylene bottom oil for 5 hours at 400C under a reduced pressure of 20 mmHg abs. By uniformly mixing 70% by weight of pitch (C) pulverized to not larger than 10 ~n in size and 30% by weight of a powdery graphite having a size not larger than 10 Aum in a Henschel mixer, a carbonaceous raw material was prepared. The *O prepared carbonaceous raw material and a sheet of paper manufactured from a mixture of a pulp arld 20% by weight of Vinylon/~) fibers (KU~ARE-VINYLON~) VPB 105-2 made by ~URARE Co., Ltd., 3mm in length), were disposed in a heating press in the same manner as in Example 1, the heating press was heated to 350C at a rate of 100C/hour and after pressing for 30 minutes under a .
~3~21.8 pressure of 50 kg/cm2G~ the pressure was reduced to ~ kg/cm2G and the heating press was further heated to ~00C at a rate of 30C/hour. Thereafter, the pressure was released and the heating press was heated still further to 600C at a rate of 50C/hour, and then the heated carbonaceous raw material interposed between graphite plates was calcined at 2,000C to obtain a carbonaceous thin plate of 1.3 mm thickness. The specific properties of the obtained ca~bonaceous thin plate are shown in Table 2.
. ApparentGas Permeation SpecificBending Thlckness Density Coef~lcient ~esistanceStrength (mm) (g/crn3) ~cm2/s) (Ohm cm)(kg/cm2) 1.3 1.95 _ 2 24 x 1o-8 2.33 x 10-31,580 EXA~LE 3;
A slurry was prepared by pulveri~ing and rnixing 6 parts by weight of pitch ~5 (A), 14 parts by weight of pitch (B), 0.5 part by weight of methylcellulose (METLOSE~) 90SH-4000, made by SHINETSU Chem. Co., Ltd.), and 80 parts by weight of water for 24 hours in a ball mill. On the other hand, by using f~lbersprepared by oxidatively infusibilizing pitch fibers and further calcining the infusibilized pitch ~lbers at 600C in gaseous nitrogen, a paper-like supporting2~0 body of an areal weight of 30 g/m2 was prepared. After impregnating the prepared paper-like supporting body uniformly with the slurry, the wet supporting body was dried to obtain a sheet-like carbonaceous raw material of an areal weight of 210 g/m2.
The material prepared by laminating 4 sheets of the obtained sheet-like carbonaceous raw material was named X1, the sheet of paper used in Example 1 was named Yl and a stainless-steel plate of 0.4 mm thickness hav;ng two flat and ~3~ 8 smooth surfaces was named Zl. and a metal mold (a dimension of 600 mm x 600 mm) of the heating press was filled with the above three kinds of material in the order of Zl Yl Xl Yl Zl Yl Xl Yl Zl - - Zl Yl Xl Yl Zl from the bottom of the metal mold, so as to fill 30 sheets of Xl in total therein, and the upper metal mold was lowered. The heating press was heated to 330 C at a rate of 100C/hour, and after pressing the content for 30 minutes under a pressure of 20 kg/cm2G, the pressure was reduced to 3 kg~cm2G and the heating press was further heated to 600C at a rate of 30C/hour, then cooled to room temperature to O obtain a ~roup of thin plates. Each of the obtained thin plates was interposedbetween the two graphite plates having flat and smooth surfaces and calcined in a vacuum oven at 2,000C. Thereby, 30 pieces of the dense carbonaceous thin plate were produced. The specific properties of the obtained carbonaceous thin plate are shown in Table 3.
1~ TABLE 3 _ ApparentGas Permeation SpecificBending Thickness DensityCoefficient ResistanceStrength (mm) (glcm3) ~cm2/s) (Ohm un)(kg/cm2) 0.47 1.9~ ~.78 x 10-8 2.26 x 10-32,030 2,1~ EXAMPLE 4:
Pitch (D) showing a softening point of 330C and a carbonization yield nf 85% by weight under calcinat;on at 900C was prepared by thermally treating a coal tar for 3 hours at 300C while blowing air thereinto, pulverizing the treated coal tar to not larger than 100~un in size and heating the pulverized material to 225C at a rate of 10C/hour in air.
: ,~; , , ' ~1 31~31218 A slurry was prepared by pulverizing and mixing 12 parts by weight of pitch (A), 18 parts by weight of pitch (D~, 65 parts by weight of water, 6 parts by weight of methanol and 0.4 part by weight of the methylcellulose (same one used in Example 3) for 24 hours in a ball mill. After applying the prepared slurry onto a paper-like supporting body of an areal weight of 25 g/m2 manufactured from flame-proof fibers of polyacrylonitrile series (PYROMEX(~) made by TOHO Rayon Co., Ltd.), the treated supporting body was dried to obtain a sheet-like carbonaceous raw material of an aerial weight of 190 g/m2. After laminating two sheets of the obtained shee~like carbonaceous raw material and interposing the v laminate between two sheets of the same paper as in 13xample 1, the combined materials were filled in the metal mold of a heating press, and the heating press was heated to 430~C at a rate of 50C/hour, and after pressing the content for one hour under a pressure of 70 kg/cm2G, the pressure was reduced to 5 kg/cm2G and then the heatilng press was heated to 6~0C at a rate of 15C/hour. Thereafter, the ~5 heating press was cooled to obtain a thin plate. The obtained thin plate was interposed betwee~ two graphite plates ha~ing flat and smooth surfaces and was calcined at 2,000C to produce the carbonaceous thin plate. The specific properties of the produced carbonaceous thin plate are shown in Table 4.
Thickness ApparentGas Permeation Specific Bendl;ng (mm) DensityCoefficient Resistance Strength (g/cm3) (cm2/s) (Ohm cm) (kg/cm2) 0.23 1 76 _ 3.~1 x 10-8 2.9 x 10-3 1,820
~ v~ 1.1 2.05 3.04 x 10-8 2.33 x 10-3_ 1,980 , COMPARA~IVE EXA~LE:
In the same manner as in Example 1 except for not inserting the sheets of paper between the carbonaceous raw material and the pressing surfaces of the heating press, a carbonaceous thin plate was produced.
/ It was found that the produced thin plate was splitted into a mosaic-like state in the metal mold, and a number of bubbles were observed in splitted pieces of the thin plate.
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EXAMPLE 2:
Pitch (C) having a softening point of 224C and a carbonization yield of 69%
/~~ by weight under calcination at 900C was produced by thermally treating an ethylene bottom oil for 5 hours at 400C under a reduced pressure of 20 mmHg abs. By uniformly mixing 70% by weight of pitch (C) pulverized to not larger than 10 ~n in size and 30% by weight of a powdery graphite having a size not larger than 10 Aum in a Henschel mixer, a carbonaceous raw material was prepared. The *O prepared carbonaceous raw material and a sheet of paper manufactured from a mixture of a pulp arld 20% by weight of Vinylon/~) fibers (KU~ARE-VINYLON~) VPB 105-2 made by ~URARE Co., Ltd., 3mm in length), were disposed in a heating press in the same manner as in Example 1, the heating press was heated to 350C at a rate of 100C/hour and after pressing for 30 minutes under a .
~3~21.8 pressure of 50 kg/cm2G~ the pressure was reduced to ~ kg/cm2G and the heating press was further heated to ~00C at a rate of 30C/hour. Thereafter, the pressure was released and the heating press was heated still further to 600C at a rate of 50C/hour, and then the heated carbonaceous raw material interposed between graphite plates was calcined at 2,000C to obtain a carbonaceous thin plate of 1.3 mm thickness. The specific properties of the obtained ca~bonaceous thin plate are shown in Table 2.
. ApparentGas Permeation SpecificBending Thlckness Density Coef~lcient ~esistanceStrength (mm) (g/crn3) ~cm2/s) (Ohm cm)(kg/cm2) 1.3 1.95 _ 2 24 x 1o-8 2.33 x 10-31,580 EXA~LE 3;
A slurry was prepared by pulveri~ing and rnixing 6 parts by weight of pitch ~5 (A), 14 parts by weight of pitch (B), 0.5 part by weight of methylcellulose (METLOSE~) 90SH-4000, made by SHINETSU Chem. Co., Ltd.), and 80 parts by weight of water for 24 hours in a ball mill. On the other hand, by using f~lbersprepared by oxidatively infusibilizing pitch fibers and further calcining the infusibilized pitch ~lbers at 600C in gaseous nitrogen, a paper-like supporting2~0 body of an areal weight of 30 g/m2 was prepared. After impregnating the prepared paper-like supporting body uniformly with the slurry, the wet supporting body was dried to obtain a sheet-like carbonaceous raw material of an areal weight of 210 g/m2.
The material prepared by laminating 4 sheets of the obtained sheet-like carbonaceous raw material was named X1, the sheet of paper used in Example 1 was named Yl and a stainless-steel plate of 0.4 mm thickness hav;ng two flat and ~3~ 8 smooth surfaces was named Zl. and a metal mold (a dimension of 600 mm x 600 mm) of the heating press was filled with the above three kinds of material in the order of Zl Yl Xl Yl Zl Yl Xl Yl Zl - - Zl Yl Xl Yl Zl from the bottom of the metal mold, so as to fill 30 sheets of Xl in total therein, and the upper metal mold was lowered. The heating press was heated to 330 C at a rate of 100C/hour, and after pressing the content for 30 minutes under a pressure of 20 kg/cm2G, the pressure was reduced to 3 kg~cm2G and the heating press was further heated to 600C at a rate of 30C/hour, then cooled to room temperature to O obtain a ~roup of thin plates. Each of the obtained thin plates was interposedbetween the two graphite plates having flat and smooth surfaces and calcined in a vacuum oven at 2,000C. Thereby, 30 pieces of the dense carbonaceous thin plate were produced. The specific properties of the obtained carbonaceous thin plate are shown in Table 3.
1~ TABLE 3 _ ApparentGas Permeation SpecificBending Thickness DensityCoefficient ResistanceStrength (mm) (glcm3) ~cm2/s) (Ohm un)(kg/cm2) 0.47 1.9~ ~.78 x 10-8 2.26 x 10-32,030 2,1~ EXAMPLE 4:
Pitch (D) showing a softening point of 330C and a carbonization yield nf 85% by weight under calcinat;on at 900C was prepared by thermally treating a coal tar for 3 hours at 300C while blowing air thereinto, pulverizing the treated coal tar to not larger than 100~un in size and heating the pulverized material to 225C at a rate of 10C/hour in air.
: ,~; , , ' ~1 31~31218 A slurry was prepared by pulverizing and mixing 12 parts by weight of pitch (A), 18 parts by weight of pitch (D~, 65 parts by weight of water, 6 parts by weight of methanol and 0.4 part by weight of the methylcellulose (same one used in Example 3) for 24 hours in a ball mill. After applying the prepared slurry onto a paper-like supporting body of an areal weight of 25 g/m2 manufactured from flame-proof fibers of polyacrylonitrile series (PYROMEX(~) made by TOHO Rayon Co., Ltd.), the treated supporting body was dried to obtain a sheet-like carbonaceous raw material of an aerial weight of 190 g/m2. After laminating two sheets of the obtained shee~like carbonaceous raw material and interposing the v laminate between two sheets of the same paper as in 13xample 1, the combined materials were filled in the metal mold of a heating press, and the heating press was heated to 430~C at a rate of 50C/hour, and after pressing the content for one hour under a pressure of 70 kg/cm2G, the pressure was reduced to 5 kg/cm2G and then the heatilng press was heated to 6~0C at a rate of 15C/hour. Thereafter, the ~5 heating press was cooled to obtain a thin plate. The obtained thin plate was interposed betwee~ two graphite plates ha~ing flat and smooth surfaces and was calcined at 2,000C to produce the carbonaceous thin plate. The specific properties of the produced carbonaceous thin plate are shown in Table 4.
Thickness ApparentGas Permeation Specific Bendl;ng (mm) DensityCoefficient Resistance Strength (g/cm3) (cm2/s) (Ohm cm) (kg/cm2) 0.23 1 76 _ 3.~1 x 10-8 2.9 x 10-3 1,820
Claims (6)
1. A process for producing a carbonaceous, thin and dense plate comprising:
(1) disposing a composite material comprising:
(A) a carbonaceous raw material which can be carbonized and solidifies after being softened by heating; and (B) paper-like substances which can be carbonized without melting;
between the pressing surfaces of a heating press, so as to sandwich said carbonaceous raw material between said paper-like substances and to contact said paper-like substances with each of the pressing-surfaces of said heating press, said carbonaceous raw material being a pitch or a mixture of a pitch and a pulverized carbonaceous material; and each of said paper-like substances having a thickness of not more than 100 µm and being (i) a sheet of paper manufactured from vegetable fibers or (ii) a sheet of paper manufactured mainly from vegetable fibers with not more than 30% by weight of synthetic organic fibers based on the total weight of the raw material for the sheet of paper;
(2) press-molding the disposed composite material under the conditions of a temperature of 150 to 450°C, a pressure of not more than 100 kg/cm2G and a pressure-retaining time of 10 to 120 minutes;
(3) successively heating the press-molded composite material to a temperature of about 600 to 650°C under a pressure of 0.1 to 100 kg/cm2G,thereby carbonizing the press-molded composite material;
(4) taking out the obtained carbonized thin plate from the press; and (5) interposing the carbonized thin plate between two pieces of flat and smooth graphite plate and further, calcining or graphitizing the interposed plate under reduced pressure or in an inert gas to obtain said carbonaceous, thin and dense plate.
(1) disposing a composite material comprising:
(A) a carbonaceous raw material which can be carbonized and solidifies after being softened by heating; and (B) paper-like substances which can be carbonized without melting;
between the pressing surfaces of a heating press, so as to sandwich said carbonaceous raw material between said paper-like substances and to contact said paper-like substances with each of the pressing-surfaces of said heating press, said carbonaceous raw material being a pitch or a mixture of a pitch and a pulverized carbonaceous material; and each of said paper-like substances having a thickness of not more than 100 µm and being (i) a sheet of paper manufactured from vegetable fibers or (ii) a sheet of paper manufactured mainly from vegetable fibers with not more than 30% by weight of synthetic organic fibers based on the total weight of the raw material for the sheet of paper;
(2) press-molding the disposed composite material under the conditions of a temperature of 150 to 450°C, a pressure of not more than 100 kg/cm2G and a pressure-retaining time of 10 to 120 minutes;
(3) successively heating the press-molded composite material to a temperature of about 600 to 650°C under a pressure of 0.1 to 100 kg/cm2G,thereby carbonizing the press-molded composite material;
(4) taking out the obtained carbonized thin plate from the press; and (5) interposing the carbonized thin plate between two pieces of flat and smooth graphite plate and further, calcining or graphitizing the interposed plate under reduced pressure or in an inert gas to obtain said carbonaceous, thin and dense plate.
2. The process according to claim 1, wherein said carbonaceous raw material is a sheet-like substance obtained by (i) preparing a slurry or a solution of said carbonaceous raw material using a solvent, (ii) impregnating or applying the prepared slurry or solution to a carbonizable supporting body, which is a paper-like material manufactured from organic fibers, carbon fibers or a mixture thereof, and (iii) evaporating the solvent from the treated carbonizable supporting body impregnated or applied with the solution or slurry..
3. The process according to claim 1, wherein said pitch is selected from the group consisting of a petroleum pitch, a coal pitch, a material obtained by oxidatively treating a petroleum pitch or a coal pitch, and a material obtained by oxidatively treating a coal tar or an asphalt and further subjecting the treatedmaterial to pitch-preparation treatment.
4. The process according to claim 1, wherein said pulverized carbonaceous material is carbon black, pulverized coke or pulverized graphite.
5. The process according to claim 1, wherein said carbonaceous raw material is in powder form.
6. The process according to claim 1, wherein said synthetic organic fibers are selected from the group consisting of fibers of polyethylene, polypropylene, rayon, acetate, polyvinyl alcohol, nylon, acrylate (polyacrylonitrile) and polyester.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP185340/85 | 1985-08-23 | ||
| JP60185340A JPS6246909A (en) | 1985-08-23 | 1985-08-23 | Production of carbonaceous sheet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1309218C true CA1309218C (en) | 1992-10-27 |
Family
ID=16169083
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000515612A Expired - Fee Related CA1309218C (en) | 1985-08-23 | 1986-08-08 | Process for producing a carbonaceous thin plate by compressing pitch material between paper sheets |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4822538A (en) |
| EP (1) | EP0212965B2 (en) |
| JP (1) | JPS6246909A (en) |
| CA (1) | CA1309218C (en) |
| DE (1) | DE3675606D1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4847021A (en) * | 1986-06-26 | 1989-07-11 | Union Carbide Corporation | Process for producing high density carbon and graphite articles |
| JPS6479073A (en) * | 1987-09-22 | 1989-03-24 | Petoca Ltd | Porous isotropic carbon-carbon composite material and its production |
| US4950443A (en) * | 1988-01-07 | 1990-08-21 | Mitsubishi Pencil Co., Ltd. | Process for producing carbon product with coarse and dense structure |
| JP2655742B2 (en) * | 1990-07-16 | 1997-09-24 | 工業技術院長 | Tapered carbon microelectrode and method of manufacturing the same |
| JP3005814B2 (en) * | 1990-11-28 | 2000-02-07 | 日本原子力研究所 | Method for producing impermeable carbon fiber reinforced composite material |
| US5353813A (en) * | 1992-08-19 | 1994-10-11 | Philip Morris Incorporated | Reinforced carbon heater with discrete heating zones |
| US5322075A (en) * | 1992-09-10 | 1994-06-21 | Philip Morris Incorporated | Heater for an electric flavor-generating article |
| DE4234497A1 (en) * | 1992-10-13 | 1994-04-14 | Hoffmann Elektrokohle | Method for producing grinding wheels for electrical collectors or the like |
| JPH0850720A (en) * | 1994-06-01 | 1996-02-20 | Kao Corp | Method for manufacturing glassy carbon substrate for recording medium and supporting device for firing |
| US5726105A (en) * | 1995-04-20 | 1998-03-10 | International Fuel Cells | Composite article |
| JP3548447B2 (en) * | 1999-01-12 | 2004-07-28 | ニチアス株式会社 | Fuel cell separator and method of manufacturing the same |
| JP5322587B2 (en) * | 2008-08-12 | 2013-10-23 | 株式会社カネカ | Method for producing graphite film |
| US9527746B2 (en) * | 2011-08-09 | 2016-12-27 | Honeywell Federal Manufacturing & Technologies, Llc | Carbonized asphaltene-based carbon-carbon fiber composites |
| KR101851752B1 (en) * | 2016-10-21 | 2018-04-24 | 에스케이씨 주식회사 | Method for preparing graphite sheet |
| CN118979409B (en) * | 2024-09-29 | 2025-03-25 | 骊能新能源科技(北京)有限公司 | A pressurized carbonization process for improving the performance of carbon paper for gas diffusion layer and carbon paper thereof |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4064207A (en) * | 1976-02-02 | 1977-12-20 | United Technologies Corporation | Fibrillar carbon fuel cell electrode substrates and method of manufacture |
| US4226816A (en) * | 1977-07-16 | 1980-10-07 | Aisin Chemical Company, Limited | Method of manufacturing a clutch facing of the type used for automotive automatic transmissions |
| US4359438A (en) * | 1981-09-21 | 1982-11-16 | Ashland Oil, Inc. | Process for molding corrosion resistant fuel cell collecting plates |
| JPS58117649A (en) * | 1981-12-29 | 1983-07-13 | Kureha Chem Ind Co Ltd | Manufacture of electrode substrate of fuel cell |
| AU2395184A (en) * | 1983-02-08 | 1984-08-16 | Development Finance Corporation Of New Zealand, The | Production of green carbon from coal |
| JPS59232905A (en) * | 1983-06-06 | 1984-12-27 | グレ−ト・レ−クス・カ−ボン・コ−ポレ−シヨン | Manufacture of carbon product |
| JPS6042213A (en) * | 1983-08-19 | 1985-03-06 | Showa Denko Kk | Manufacture of carbon sheet |
| JPS60122711A (en) * | 1983-12-08 | 1985-07-01 | Oji Paper Co Ltd | Manufacture of porous carbon board |
-
1985
- 1985-08-23 JP JP60185340A patent/JPS6246909A/en active Granted
-
1986
- 1986-08-08 CA CA000515612A patent/CA1309218C/en not_active Expired - Fee Related
- 1986-08-08 US US06/894,333 patent/US4822538A/en not_active Expired - Lifetime
- 1986-08-18 EP EP86306377A patent/EP0212965B2/en not_active Expired - Lifetime
- 1986-08-18 DE DE8686306377T patent/DE3675606D1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0435434B2 (en) | 1992-06-11 |
| US4822538A (en) | 1989-04-18 |
| EP0212965A2 (en) | 1987-03-04 |
| EP0212965B1 (en) | 1990-11-14 |
| DE3675606D1 (en) | 1990-12-20 |
| JPS6246909A (en) | 1987-02-28 |
| EP0212965B2 (en) | 1995-08-09 |
| EP0212965A3 (en) | 1988-08-10 |
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