Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof

Definitions

• This invention relates generally to the field of formed structures or articles of carbon and techniques in the production thereof. More particularly, the invention concerns a new process for producing carbon formed articles having graphitisation characteristics and structural textures varying over Wide ranges from modified pitches (defined hereinafter) as starting materials.
• formed or shaped articles or structures of carbon of various kinds have been produced.
• carbon in a glass-like state are the so-called cellulose carbon manufactured by G.E.C., Ltd., of England, the so-called glass carbon manufactured by Tokai Denkyou Company, Ltd., of Japan, and carbon products developed by Shigen Gijutsu Shikenof Japan for which acetone-furfural resins are used as starting material.
• numerous other carbon products including porous products and filaments have been produced. While most of these various canbon products have excellent characteristics, they have had one or more drawbacks such as complicated or time-consuming processes in the products thereof or the necessity of using expensive starting materials.
• a process as stated above which is characterised by the steps of preparing a modified pitch (defined hereinafter) of a hydrogen-to-carbon (H/C) atomic ratio of from 0.2 to 0.6 and a softening point (as defined hereinafter) of at least 170 degrees C., forming this modified pitch as a principal starting material into a formed article, and subjecting this article to carbonisation and/or graphisation treatment in an inert gas, or
• modified pitch designates collectively pitches obtained by heat treatment, by treatment with a dehydrogenation agent such as ozone, oxygen, air, halogens, and sulphur, or by solvent extraction treatment of coal tar pitches, petroleum asphalts, and other tars and pitches produced industrially as byproducts, these modified pitches being further characterised in that their H/C atomic ratios and softening temperatures are from 0.2 to 0.60 and 170 degrees C. or higher, respectively.
• a dehydrogenation agent such as ozone, oxygen, air, halogens, and sulphur
• softening temperature or softening point used herein designates that temperature, as measured by means of a micromelting-point-measuring apparatus, at which a sample in the form of fine powder of the order of 0.1 mm. within a sealed tube fully assumes a spherical form.
• a large number of modified pitches having H/ C atomic ratios of the order of from 0.60 to 0.46 exhibit softening points of the order of from 170 to 300 degrees C.
• a process other than (A) and (B), above, for readily preparing a modified pitch having the objective characteristics is a treatment with chlorine gas.
• a modified pitch of a softening point of the order of from 170 to 300 degrees C. is obtained by the treatment up to a temperature of from to 270 degrees C.
• This modified pitch contains from 5 to 15 percent of chlorine.
• a process comprising an ozone treatment at room temperature and an immediately following air oxidation treatment up to a temperature of the order of 250 degrees C. is particularly effective in raising the softening points and reducing the H/ C atomic ratios of starting material pitches and, furthermore, in introducing a functional group containing oxygen of high thermal reactivity into a modified pitch already having characteristics within the aforestated ranges.
• oxygen in an amount up to approximately 30 percent can be readily introduced in this manner.
• a single modified pitch or a mixture of different pitches is ground to a suitable combination of sizes of particles, which are then formed, for example, by pressure moulding at a pressure of from 100 to 3,000 kg./cm.
• a feature of this process is that the admixture of an aggregate such as coke particles of a binder such as pitch is not necessary.
• the admixture of additives such as coke and graphite is possible, of course, particularly in cases when the softening oint of the pitch is relatively low.
• the forming operation of the invention may be accomplished by extrusion or by moulding in a die or mould cavity. In either case, good results are obtained by adding approximately 10 percent or less of alcohol or some other suitable liquid to the modified pitch.
• the pitch is formed, then dried, and thereafter gradually heated up to from 200 to 300 degrees C. in air at a temperature rise rate of from 0.1 to 3 degrees C./ minute.
• This temperature rise rate can be increased, and the maximum treatment temperature in air can be decreased in the case of a modified pitch of higher softening temperature and, moreover, in the case of a modified pitch having a thermal reactive functional group.
• lower temperature rise rates are preferable for formed articles of larger size.
• Carbonisation and graphitisation treatment with respect to formed articles requiring this treatment, is carried out with a temperature rise rate of approximately 5 degrees C./minute in an inert gas after heat treatment in air.
• An article having any porosity in the range of from 8 to 60 percent can be produced, depending on the softening point of the modified pitch and the forming pressure.
• these materials have a high degree of hardness.
• Shore hardness Hs
• the hardness of an article of a carbide with a porosity of approximately 30 percent or less is from 80 to 130, and that of an article which has undergone graphitisation treatment (at 2,800 degrees C.) and has a porosity of approximately 30 percent or less is from 50 to 90.
• articles of porosities of from 8 to 15 exhibit values of from 800 to 1,100 kg./ cm.
• articles of porosities of from 15 to 30 percent exhibit values of from 400 to 800 kg./cm. and articles of porosities above 30 percent exhibit values of from to 400 kg./cm.
• articles fired at 600 degrees C. exhibit values of bending strength of from 100 to 200 kg/cm. and values of shore hardness (Hs) of from 100 to 130.
• modified pitches prepared by the aforedescribed process (A) and modified pitches prepared by process (A) followed a process for introducing a thermal reactive functional group or another process, that is, processes (C) and (D) or some other process as stated above, result in easily graphitised carbon materials and carbon materials having slightly deficient graphitisation characteristics, and
• modified pitches prepared by process (B), process (C), process (D), or another treatment wherein a dehydrogenation agent is added and modified pitches prepared by combinations of these processes result in carbon materials ranging from those difficult to graphitise to those of intermediate graphitisation characteristics.
• modified pitches prepared by the various above described processes for preparing modified pitches having characteristics falling within the aforedefined ranges of H/ C atomic ratio of from 0.2 to 0.60 and of softening point of degrees C. or above.
• the coefficient of linear contraction or shrinkage is from 5 to 20 percent, being from 10 to 15 percent in most cases.
• the present invention makes possible the production of a large variety of materials and products of formed carbon for a wide range of users.
• formed articles of low porosity produced by the process of the invention can be used as various electrodes, electrolytic plates, structural materials, refractory materials, and aggregates and obviate the necessity of processes involving repetitions of firing, impregnation, and refiring.
• Formed articles of high porosity can be used for products such as electrodes for fuel cells, filter elements, and heat insulation materials.
• An important feature of the present invention is that it affords a process whereby it has become possible to produce readily carbon materials in a glass-like state of easily graphitisable or difiicult to graphitise characteristic and porous carbon materials of easily graphitisable or difficult to graphitise characteristic, this is, carbon materials which, in structure, range from those approaching glass to those of high porosity and, at the same time, have any basic structure ranging from easily graphitisable to difiicult to graphitise characteristic. This feature further widens the uses for glass-like carbon materials and porous carbon materials beyond the scope as conceivable heretofore.
• a further advantageous feature of the invention is that use is made in the process thereof of pitches which are most economical from the industrial viewpoint as starting materials.
• This pitch-like substance was formed under a pressure of 400 kg./cm. into a disk of ZO-mm. diameter and mm. thickness, which was heated in air at a temperature rise rate of 2 degrees C./minute to 320 degrees C.
• the atmosphere around the formed article was changed over to nitrogen gas, and the formed article was fired by heating at a temperature rise rate of 5 degrees C./minute to 1,000 degrees C.
• the fired article thus obtained was very uniform, and when a surface thereof was polished, a mirror surface was obtained.
• the properties of this article were as follows:
• This article was graphitised by heating up to 2,800 degrees C. in an inert gas.
• the resulting article was found to have the following properties.
• Example 2 A polyvinyl chloride powder was fired at a temperature of from 400 to 430 degrees C. in nitrogen gas, whereupon a pitch-like substance of a softening point of from 195 to 202 degrees C. was obtained. This substance, used as a starting material in powder form, was spread as much as possible and, in this state, was heated up to 200 degrees C. in air at a temperature rise rate of from 2 to 3 degrees C./minute thereby to cause oxidation thereof, whereupon a pitch of H/C atomic ratio of 0.48 was obtained.
• This pitch was ground and then formed under a forming pressure of 450 kg./cm. into a formed disk of 20- mm. diameter and 4-mm. thickness, which disk was thereafter subjected to the same process steps prior to the graphitisation step as set forth in the preceding Example 1.
• the formed article thus obtained was uniform and could be polished to a mirror surface. Measured properties of this article were as follows:
• Example 3 A coal pitch of a softening point of degrees C., produced by Kawasaki Seitetsu (Kawasaki Iron and Steel) of Japan was dry distilled at 380 degrees C. The resulting residue in the powder form as obtained was subjected to the action of ozone at room temperature and then oxidised by heating in air up to 200 degrees C. to prepare a first pitch material.
• the component insoluble in chloroform of the Kawasaki Seitetsu coal pitch was air oxidised by heating up to 200 degrees C., in the powder form as obtained, to prepare a second material.
• the resulting first and second materials were mixed in the weight ratio of 1:3, and the mixture was thoroughly ground, whereupon a pitch mixture having an average H/ C atomic ratio of 0.50 was obtained.
• This mixture was formed under a pressure of 400 kg./cm. into a formed article, which was thereafter subjected to the same process steps prior to the graphitisation step as set forth in Example l.
• the properties of the formed articles thus processed were as follows:
• Example 4 Coal pitch of the kind specified in Examples 1 and 3 (softening point 85 degrees C.) was dry distilled at 380 degrees C. for 60 minutes, and the residue, with 5 percent of tetramethylthiuram disulphide added thereto, was heat treated at 300 degrees C. for one hour and then ground, whereupon a pitch of H/ C atomic ratio of 0.45 was obtained.
• This pitch was formed under a pressure of kg./cm. into a disk of 20-mrn. diameter and 10mm. thickness, which was thereafter subjected to the same process steps prior to the graphitisation step as set forth in Example 1.
• the formed disk thus produced was uniform and could be polished to a mirror surface.
• the properties of this disk were as follows:
• Example 5 Kawasaki Seitetsu coal pitch (softening point 85 degrees C.) was dry distilled at 380 degrees C. for 30 minutes, and the residue was ground and placed in contact with chlorine gas at room temperature for 30 minutes. The resulting pitch had a H/ C atomic ratio of 0.41.
• This pitch was formed under a pressure of 300 kg./cm. in the same manner as set forth in Example 1 and there- 7 after was subjected to the same process steps prior to the graphitisation step as set forth in Example 1.
• the formed article thus produced was uniform and exhibited a mirror surface when polished.
• the properties of this article were as follows:
• Example 6 A pitch produced as a byproduct of cracking of petroleum naphtha and having a softening point of from 195 to 205 degrees C. and a H/C atomic ratio of 0.54 was used as a starting material pitch. This pitch was ground well and then formed under a pressure of 300 kg./cm. into a disk of 20-mm. diameter and S-mm. thickness.
• This disk was then heated in air up to 330 degrees C. at a temperature rise rate of from 1 to 2 degrees C./ minute and then fired by heating in an inert gas up to 1,000 degrees C. at a temperature rise rate of 5 degrees C./minute.
• the resulting formed article exhibited good uniformity and a mirror surface when polished and had the following properties.
• Example 7 Kawasaki Seitetsu coal pitch (softening point 85 degrees C.) was ground into a fine powder form and heated in this form and in contact with chlorine gas up to 250 degrees C.
• the sample thus obtained had a H/C atomic ratio of 0.38 and had no softening point up to a temperature of 360 degrees C.
• This formed article was heated in nitrogen gas up to 500 degrees C. at a temperature rise rate of from 2 to 3 degrees C./ minute and then fired by heating to a higher temperature at a temperature rise rate of 5 degrees C./minute.
• the resulting formed article had the same outer appearance as the corresponding articles in the foregoing examples and had the following properties.
• Example 8 The component insoluble in chloroform of Kawasaki Seitetsu coal pitch was used as a starting material.
• This material in powder form was spread for good contact with air and oxidised by heat up to 220 degrees C., whereupon a pitch of a H/C atomic ratio of 0.50 was obtained.
• This pitch was ground into a fine powder, which was then formed under a pressure of 450 kg./cm. into a disk of 204mm. diameter and 7-mm. thickness, which was fired under the same conditions as set forth in Example 5.
• the resulting formed article had an outer ap pearance similar to those of the corresponding articles of the foregoing examples and had the following properties.
• Example 9 500 grams of coal tar pitch (softening point degrees C.) was dry distilled at 400 degrees C. for 90 minutes as air was blown thereonto, whereupon a modified pitch of a softening point of from 238 to 245 degrees C. and a H/C atomic ratio of 0.46 was obtained.
• This pitch was ground and then formed under a pressure of 400 kg./cm. into a formed article, which was heated in air up to 300 degrees C. at a rate of 0.3 degree C./minute and then heated in nitrogen gas up to 2,800 degrees C. at a rate of 5 degrees C./minute.
• a diskshaped formed article of 40-mrn. diameter and 10-mm. thickness having a Shore hardness of 95, porosity of 12 percent, and bending strength of 600 kg./cm. was obtained.
• the lattice spacing as determined by the X-ray 002 diffraction line was 3.39 angstroms, and the specific resistivity was 3 10- ohm. cm.
• the product was a carbon material of difiicult graphitisability.
• Example 10 Petroleum asphalt was dry distilled at 390 degrees C. as air was blown thereonto. The resulting material was ground and treated in a chlorine gas atmosphere at temperatures up to 250 degrees C., whereupon a monified pitch of a H/C atomic ratio of 0.42 and a softening point which could not be definitely determined was obtained.
• This pitch was formed under a pressure of 300 kg./cm. into a formed article, which was heated in air up to 300 degrees C. at a rate of 1 degree C./minute and then heated in nitrogen gas up to 2,800 degrees C.
• the carbon material thus produced had a shore hardness of 68, porosity of 48 percent, bending strength of 78 kg./ cm. and specific resistivity of 13 10- ohm. cm. and was found to have a difficult-to-graphitise characteristic as determined by X-rays.
• a process for producing carbon shaped articles from a modified pitch having an H/C atomic ratio of 0.2 to 0.6 and a softening point of at least C. selected from the group consisting of (1) tars and pitches treated with chlorine, (2) tars and pitches treated with ozone immediately followed by air oxidation, (3) tars and pitches subjected to dry distillation in air at 380 C. to 430 C., and (4) tars and pitches subjected to dry 9 distillation in an inert gas at 380 C. to 500 C., which comprises:
• step (c) is carried out by heating the shaped article to a temperature between 200 C. to 300 C.
• step (c) is carried out by heating the shaped article to a temperature between from 200 C. to 300 C. at a rate of from 0.1 to 3.0 C./minute.
• step (b) 5. The process according to claim 1, in which alcohol is added to the pulverised pitch in step (b) in an amount of less than 10% to the total quantity thereof.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Electrochemistry (AREA)
• Metallurgy (AREA)
• Manufacturing & Machinery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Structural Engineering (AREA)
• Inorganic Chemistry (AREA)
• Carbon And Carbon Compounds (AREA)
• Ceramic Products (AREA)
• Working-Up Tar And Pitch (AREA)

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Cited By (31)

Families Citing this family (4)

• 1967
  • 1967-02-03 JP JP42006563A patent/JPS5112474B1/ja active Pending
• 1968
  • 1968-01-31 US US701827*A patent/US3558276A/en not_active Expired - Lifetime
  • 1968-02-02 GB GB5348/68A patent/GB1220482A/en not_active Expired
  • 1968-02-03 DE DE1646658A patent/DE1646658C3/de not_active Expired

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