WO2018147107A1 - 耐炎化炉の洗浄方法および耐炎化繊維、炭素繊維、黒鉛化繊維の製造方法 - Google Patents
耐炎化炉の洗浄方法および耐炎化繊維、炭素繊維、黒鉛化繊維の製造方法 Download PDFInfo
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- WO2018147107A1 WO2018147107A1 PCT/JP2018/002666 JP2018002666W WO2018147107A1 WO 2018147107 A1 WO2018147107 A1 WO 2018147107A1 JP 2018002666 W JP2018002666 W JP 2018002666W WO 2018147107 A1 WO2018147107 A1 WO 2018147107A1
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- flameproofing furnace
- furnace
- flameproofing
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- carbon fiber
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Images
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
- D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto
- B08B9/08—Cleaning containers, e.g. tanks
-
- 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
- C01B32/20—Graphite
- C01B32/205—Preparation
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/32—Apparatus therefor
-
- 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
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- C11D2111/20—
Definitions
- the present invention relates to a flameproofing furnace cleaning method for producing a flameproofed fiber by making a carbon fiber precursor fiber flameproof with an oxidizing gas.
- carbon fiber Since carbon fiber is excellent in specific strength, specific elastic modulus, heat resistance, and chemical resistance, it is useful as a reinforcing material for various materials and used in a wide range of fields such as aerospace applications, leisure applications, and general industrial applications. Has been. Since carbon fibers are often used in places where strength is required, it is necessary to uniformly and stably have extremely high characteristics, that is, excellent and high quality is required.
- a fiber obtained by bundling thousands to tens of thousands of single fibers of a polyacrylonitrile polymer (hereinafter abbreviated as carbon fiber precursor fiber) is made flame resistant. It is sent to a furnace, exposed to hot air in an oxidizing atmosphere such as air heated to 200-300 ° C, and then subjected to heat treatment (flame resistance treatment), and the resulting flame resistant fiber is sent to a carbonization furnace.
- heat treatment carbonization treatment
- pre-carbonization treatment pre-carbonization treatment
- the flame-resistant fiber which is an intermediate material, is widely used as a material for flame-retardant woven fabrics by taking advantage of its incombustible performance.
- silicone oil is often used for the carbon fiber precursor fiber in order to avoid the fusion of the flameproof fiber.
- the hot air circulation type flameproofing furnace constitutes a hot air circulation system including a heat treatment chamber for performing a flameproofing treatment on the carbon fiber precursor fiber and a hot air circulation path for heating and circulating the hot air. Since the hot air can be repeatedly used by the hot air circulation system, the hot air circulation type flameproof furnace has an advantage that the loss of heat energy can be reduced.
- the hot air circulation type flameproofing furnace has a disadvantage that impurities such as dust are likely to stay in the hot air in the flameproofing furnace for a long time because impurities staying in the hot air are not easily discharged outside the hot air circulation system. is there.
- dust generated from the silicone-based oil applied to the carbon fiber precursor fiber accumulates in the flameproofing furnace and adheres to the carbon fiber precursor fiber during the flameproofing treatment.
- the adhesion point of the dust adhering to the precursor fiber becomes a starting point of fuzz generation and single yarn breakage in the subsequent carbonization treatment, and significantly deteriorates the quality of the obtained carbon fiber.
- Dust that accumulates in the flameproofing furnace includes dust derived from the silicone-based oils described above, aggregates of oily agent components other than silicone oils, and dust that comes from outside the flameproofing furnace and adheres to the carbon fiber precursor fibers. Moreover, the dust etc. which are contained in the external air which flows in in a flame-proofing furnace, those consisting of those composites, etc. are mentioned.
- Patent Document 1 proposes a flameproofing furnace in which a watering nozzle and a drain port are provided above the flameproofing furnace rectifying plate to clean and remove dust adhering to the rectifying plate. According to this flameproofing furnace, it is not necessary to manually perform the operation of water spraying toward the rectifying plate that is blocked by dust adhering thereto, and cleaning is facilitated.
- Patent Document 2 proposes a flameproof furnace having an agglomeration mechanism that takes in hot air from a hot air circulation path, aggregates impurities, and returns hot air to the hot air circulation path again. According to this flameproofing furnace, dust can be efficiently removed from hot air, and operability can be improved.
- Patent Document 3 proposes a flameproofing furnace that discharges the oxidizing gas that has passed through the carbon fiber precursor fiber traveling region in the initial stage of flameproofing where dust is generated most, without circulating it. According to this flameproofing furnace, dust adhering to the furnace can be greatly reduced, and continuous operation for a long time is possible.
- Patent Document 4 proposes a flameproof furnace in which an exhaust port is provided in a hot air circulation path. According to this flameproofing furnace, the hot air in the hot air circulation system is exhausted from the exhaust port to the outside of the hot air circulation system before restarting after cleaning the inside of the furnace, so that dust remaining in the flameproofing furnace can be reduced. Thus, it is possible to prevent deterioration in the quality of the flame-resistant fiber that occurs in the initial stage after re-operation.
- Patent Document 1 has an effect of removing a fixed amount of adhering dust, but the cleaning / removal effect is insufficient only by watering.
- the present invention has been made in view of the above circumstances, and can obtain high-quality carbon fibers immediately after reactivation of the flameproofing furnace, and can easily clean the flameproofing furnace and stop production.
- An object of the present invention is to provide a method for cleaning a flameproofing furnace capable of shortening the period during which the flameproofing is performed, a method for manufacturing a flameproofing fiber having a step of cleaning the flameproofing furnace using the cleaning method, and a method for manufacturing a carbon fiber. To do.
- the present invention for solving the above problems employs any of the following configurations.
- a method for cleaning a flameproofing furnace in which the dust separated from the outside is discharged out of the flameproofing furnace and an oxidizing gas having a temperature of 40 ° C. or higher is circulated in the flameproofing furnace.
- the polyacrylonitrile-based carbon fiber precursor fiber is placed in an oxidizing atmosphere in the flameproofing furnace.
- a method for producing flame-resistant fibers which is flame-resistant at a maximum temperature of 200 to 300 ° C.
- the flame-resistant fibers are pre-carbonized by precarbonization at a maximum temperature of 300 to 1000 ° C. in an inert atmosphere.
- a method for producing carbon fiber comprising producing a fiber and carbonizing the pre-carbonized fiber at a maximum temperature of 1000 to 2000 ° C. in an inert atmosphere.
- a method for producing graphitized fiber comprising producing carbon fiber by the method for producing carbon fiber as described in (6) above, and then graphitizing the carbon fiber at a maximum temperature of 2000 to 3000 ° C. in an inert atmosphere.
- the method for cleaning a flameproofing furnace of the present invention high-quality flameproofing fibers can be stably obtained, and the flameproofing furnace can be continuously operated for a long time.
- the time and labor required for cleaning can be reduced, and the period during which production is stopped can be shortened.
- the present invention is a flameproofing furnace cleaning method for flameproofing a polyacrylonitrile-based carbon fiber precursor fiber in an oxidizing atmosphere, and is performed in a flameproofing furnace having a mechanism in which an oxidizing gas circulates inside.
- the flameproofing furnace 1 has a hot air circulation system and discharge means. As shown in FIGS. 1 and 2, the hot air circulation system includes a heat treatment chamber 3 in which hot air is blown to the carbon fiber precursor fiber 2 that travels while turning back and forth in a multistage traveling region, and a hot air is applied to the heat treatment chamber 3. It has a hot air circulation path 4 for circulating hot air in the hot air circulation system by blowing into the heat treatment chamber 3 and discharging it out of the heat treatment chamber 3.
- a hot air outlet 5 for blowing hot air into the traveling region of the carbon fiber precursor fiber 2 and a hot air outlet for discharging hot air from the traveling region of the carbon fiber precursor fiber 2 to the outside of the heat treatment chamber 3. 6 is provided. Further, a heater 7 for heating the hot air and a blower 8 for controlling the wind speed of the hot air are provided in the middle of the hot air circulation path 4. Further, as shown in FIG. 5, in order to keep the concentration of gas such as HCN generated from the carbon fiber precursor fiber 2 below a certain value, the hot air containing these gases is discharged out of the hot air circulation system. An exhaust fan 16 and an exhaust gas combustion device 17 for processing gas may be provided.
- the carbon fiber precursor fiber 2 is fed into the heat treatment chamber 3 from the slit 9 provided on the side wall of the heat treatment chamber 3 of the flameproofing furnace 1 and travels linearly in the heat treatment chamber 3 and then from the slit on the opposite side wall. It is once sent out of the heat treatment chamber 3. Thereafter, the sheet is folded back by the guide roll 10 provided on the side wall outside the heat treatment chamber 3 and is fed into the heat treatment chamber 3 again.
- the carbon fiber precursor fiber 2 is repeatedly diffracted in the traveling direction by the plurality of guide rolls 10, so that the feeding and sending into the heat treatment chamber 3 is repeated a plurality of times, and the inside of the heat treatment chamber 3 is multi-staged. As shown in FIG.
- the moving direction may be from bottom to top, and the number of turns of the carbon fiber precursor fiber 2 in the heat treatment chamber 3 is not particularly limited, and is appropriately designed depending on the scale of the flameproofing furnace 1 and the like.
- the guide roll 10 may be provided inside the heat treatment chamber 3.
- the carbon fiber precursor fiber 2 is flameproofed by hot air blown from the hot air outlet 5 while traveling inside the heat treatment chamber 3 while being turned back into a flameproof fiber.
- the carbon fiber precursor fibers 2 have a wide sheet-like form that is aligned so as to be parallel to a plurality of carbon fiber precursor fibers 2 in a direction perpendicular to the paper surface.
- the hot air outlet 5 is provided with a pressure loss by arranging a resistor such as a perforated plate and a rectifying member such as a honeycomb (both not shown) on the blowing surface.
- a resistor such as a perforated plate
- a rectifying member such as a honeycomb (both not shown)
- the flow of hot air blown into the heat treatment chamber 3 can be rectified by the flow regulating member, and hot air having a uniform wind speed can be blown into the heat treatment chamber 3.
- the hot air outlet 6 may be provided with a resistor such as a perforated plate on the suction surface to have a pressure loss, which is determined as necessary.
- Hot air blown into the heat treatment chamber 3 by the hot air outlet 5 heats the carbon fiber precursor fiber 2 while flowing in the heat treatment chamber 3 from above to below, that is, toward the discharge port 6 side.
- the hot air that has reached the downstream is discharged out of the heat treatment chamber 3 through the hot air discharge port 6 and guided to the hot air circulation path 4. And it heats to desired temperature with the heater 7 provided in the middle of the hot-air circulation path 4, and after the air speed is controlled by the air blower 8, it blows in the heat processing chamber 3 again from the hot air blower outlet 5.
- FIG. In this manner, the flameproofing furnace 1 can flow hot air having a predetermined temperature and wind speed into the heat treatment chamber 3 by the hot air circulation system including the heat treatment chamber 3 and the hot air circulation path 4.
- the direction of the hot air is not limited to the direction from the top to the bottom of the heat treatment chamber 3, and it may flow from the bottom to the top or in a direction parallel to the traveling yarn.
- the heater 7 used in the flameproofing furnace 1 is not particularly limited as long as it has a desired function.
- a known heater such as an electric heater may be used.
- the blower 8 is not particularly limited as long as it has a desired function.
- a known blower such as an axial fan may be used.
- the volatiles of the silicone-based oil agent from the carbon fiber precursor fiber 2 are generated immediately after the carbon fiber precursor fiber 2 is fed into the heat treatment chamber 3. Since the generated volatile matter is difficult to be discharged from the circulation system including the heat treatment chamber 3 and the hot air circulation path 4, dust generated from the volatile matter adheres to the circulation system. When the amount of dust adhering to the wall of the flameproofing furnace exceeds a certain level, it is separated by vibration and impact, and is carried to a place where the pressure loss such as the hot air outlet 5 is large by the circulating hot air to cause blockage. In addition, when floating dust touches the running yarn, it becomes the starting point of single yarn breakage, and as a result, the quality of the carbon fiber is significantly reduced.
- the cleaning method of the present invention is a cleaning method of the flameproofing furnace 1 in which the polyacrylonitrile-based carbon fiber precursor fiber is flameproofed in an oxidizing atmosphere as described above.
- the pressure in the direction perpendicular to the wall surface with respect to the dust adhering to the wall surface of the flameproofing furnace 1 becomes 2 MPa or more.
- the liquid is discharged to the outside of the flameproofing furnace 1 to discharge the dust separated from the wall surface to the outside of the flameproofing furnace 1, and further, oxidation at a temperature of 40 ° C. or higher in the flameproofing furnace.
- a characteristic gas is circulated.
- the pressure of the liquid in contact is 2 MPa or more in the direction perpendicular to the wall surface, preferably 3 MPa or more, and more preferably 3.5 MPa or more.
- the saturation of the effect on pressure it is also preferably 10 MPa or less.
- the time for bringing the liquid into contact with the wall surface is appropriately determined depending on the degree of dust adhesion, but is preferably 1 second or longer and more preferably 3 seconds or longer for the same location. On the other hand, considering the saturation of the effect on time, it is also preferably 1 minute or less.
- the method for measuring the pressure of the liquid in contact with the wall surface is not particularly limited, but a pressure-sensitive film (for example, Fujifilm Prescale LWPS or LLWPS) may be used.
- a pressure-sensitive film for example, Fujifilm Prescale LWPS or LLWPS
- the liquid used for cleaning is not particularly limited, but water is preferable from the viewpoint of economy.
- the water may contain an additive such as a surfactant, and may be ion-exchanged water or pure water.
- the dust used for cleaning can be discharged out of the flameproofing furnace 1 by discharging the liquid used for cleaning out of the flameproofing furnace 1. Therefore, it is preferable to provide an outlet (not shown) at the bottom of the flameproofing furnace 1 for discharging the liquid used for cleaning out of the flameproofing furnace in a short time.
- the cleaning method may be carried out by an operator directly entering the furnace.
- a cleaning device 12 including at least one cleaning nozzle 11 that can be operated from the outside is provided. Remote control may be used.
- the cleaning device 12 may be installed anywhere in the flameproofing furnace 1, but it is more preferable that the cleaning device 12 is installed in a flow path having a short side of 600 mm or less, which is difficult for an operator to enter directly into the cleaning.
- the oxidizing gas is circulated in the flameproofing furnace using the blower 8 or the like and the inside of the furnace is dried, the volume of the dust that cannot be removed and remains attached to the wall surface changes, and the dust is By peeling, a further sufficient cleaning effect can be obtained.
- the oxidizing gas is hot air, a difference in thermal expansion coefficient between the flameproofing furnace 1 and the adhering dust occurs, and the volume change when the moisture between the adhering dust and the flameproofing furnace wall evaporates. The accompanying impact removes the dust.
- the temperature of the hot air measured by a thermometer installed in the heat treatment chamber 3 and the hot air circulation path 4 is 40 ° C. or higher, 60 ° C. or higher, and further 80 ° C. or higher. Is preferred.
- the upper limit is preferably 200 ° C. or lower, and more preferably 150 ° C. or lower. It is preferable to heat the inside of the furnace to be in such a temperature range.
- the temperature measurement method is not particularly limited as long as it has a desired function. For example, a known thermometer such as a thermocouple may be used.
- the method for heating and supplying hot air is not particularly limited, but it is preferable to circulate the hot air in the flameproofing furnace 1 after heating with a known heater or the like in order to reduce loss of heat energy.
- the circulated gas contains separated dust, it is preferable to discharge the entire amount outside the flameproofing furnace after circulation. By discharging the circulated oxidizing gas outside the flameproofing furnace, the dust separated from the wall surface can be further discharged outside the flameproofing furnace.
- the impact force applied to the adhering dust due to the change in the wind speed of the oxidizing gas to circulate is effective in removing the dust adhering to the wall of the flameproofing furnace. Therefore, as shown in FIGS. 5 and 6, on the discharge side of the blower 8 that circulates the hot air in the flameproofing furnace 1, an opening and closing that can discharge 13 to 100% of the suction air amount of the blower 8 is possible. It is more preferable to provide an exhaust port 13 having a mechanism and a switching valve 14 that can block communication between the exhaust port and the circulation duct. In order to give an impact force to the adhering dust, the wind direction may be changed instead of changing the wind speed. The same effect can be achieved by changing the wind direction.
- the air supply port 15 having an opening / closing mechanism is provided on the downstream side of the exhaust port 13, and the air supply port 15 and the exhaust port are provided. It is more preferable to provide a switching valve 14 that can block communication between the circulation ducts 13.
- a method of changing the wind direction / velocity of the gas a method of intermittently changing the rotation speed of the blower 8 using a programming controller, or a gas ejection device is installed in the heat treatment chamber 3 or the hot air circulation path 4 in advance.
- a method of ejecting gas may be used.
- the contact with a fluid of 2 MPa or more in the direction perpendicular to the surface to be cleaned, drying the inside of the furnace after cleaning, and circulating the gas and switching the wind direction to discharge out of the flameproofing furnace are performed multiple times.
- the number of times is not limited.
- a hot air circulation system is used while using a hot air circulation type flameproof furnace with a low loss of thermal energy. It is easy to remove dust adhering to the flameproofing furnace. Therefore, since the time and labor required for cleaning the inside of the flameproofing furnace can be reduced, the maintenance cost can be greatly reduced as compared with the conventional flameproofing furnace cleaning. Further, since the amount of adhering dust remaining without being cleaned is reduced, the flameproofing furnace can be operated continuously for a long period of time, thereby improving the productivity of the flameproofing fiber. In addition, it is possible to suppress the deterioration of the quality of carbon fibers and flame-resistant fibers due to the re-scattering of the adhering dust that could not be cleaned immediately after restarting. And can be manufactured stably.
- the cleaning method of the present invention may be carried out in each of the carbon fiber production methods using a plurality of flameproofing furnaces, but the volatiles derived from the silicone oil are mostly flameproofed. Therefore, it is preferable to use the flameproofing furnace cleaning method of the present invention for cleaning at least the flameproofing furnace that performs the first flameproofing treatment. Thereby, the dust generated by the volatile matter from the carbon fiber precursor fiber 1 and adhered to the flameproofing furnace 1 can be efficiently removed from the flameproofing furnace 1, and the quality of the carbon fiber immediately after the production apparatus is restarted. Reduction can be suppressed. Therefore, when the cleaning method of the present invention is used, even when a plurality of flameproofing furnaces are used, a long-term continuous operation of the plurality of flameproofing furnaces becomes possible.
- polyacrylonitrile fiber As the carbon fiber precursor fiber used in the carbon fiber production method of the present invention, polyacrylonitrile fiber is used.
- Polyacrylonitrile fibers are prepared by dissolving an acrylonitrile polymer in an organic solvent or an inorganic solvent and spinning by a commonly used method, but the spinning method and spinning conditions are not particularly limited.
- the silicone oil applied to the polyacrylonitrile fiber used in the present invention must contain amino-modified silicone at least in part.
- the amount of silicone oil applied to the polyacrylonitrile fiber is preferably 0.05 to 3% by mass, more preferably 0.3 to 1.5% by mass.
- Such silicone oil may further contain a surfactant, a heat stabilizer and the like.
- dimethyl siloxane and those modified with functional groups are preferably used, including amino-modified dimethyl siloxane modified with amino groups as essential components, polyethylene oxide-modified dimethyl siloxane, epoxy It is more preferable to use a mixture with modified dimethylsiloxane to increase the thermal stability.
- the flame resistance treatment is performed by heat-treating the polyacrylonitrile fiber thus obtained at a maximum temperature of 200 to 300 ° C.
- fine particles such as dust generated by heating and oxidation of silicone oil, fine particles containing metal elements from outside air and equipment around the heat treatment furnace and fine particles such as dust
- the fine particles Due to continuous production of carbon fiber, it accumulates in the furnace, which causes quality degradation.
- fine particles having a particle size of 0.3 ⁇ m or more adhere to the carbon fiber surface.
- the fine particles cause a reduction in the tensile strength of the carbon fiber by forming a scratch of 0.3 ⁇ m or more on the surface of the flame-resistant fiber.
- the total number of fine particles having a particle diameter of 0.3 ⁇ m or more and scratches having a diameter of 0.3 ⁇ m or more on the surface of the flame-resistant fiber should be within 20 / 0.1 mm 2 . It is preferable that the number is 15 / 0.1 mm 2 or less.
- the cleaning may be performed at the elapse of a predetermined period set in advance based on the time when the number of fine particles and scratches on the surface of the flame resistant fiber is considered to exceed a predetermined number.
- An oxidizing gas such as air is used for the hot air circulating in the flameproofing furnace. It is better to have less fine particles such as dust in the oxidizing gas. However, because such fine particles are constantly generated and adhered in the oxidizing gas for the above reasons, it is industrially difficult to make the concentration zero. is there. Therefore, it is preferable to filter when taking in the outside air to be supplied into the flameproofing furnace, or to make the material of the metal part used in the apparatus to be a rust-resistant material such as stainless steel. In addition, the amount of silicone oil used is kept low within the range where desired physical properties are expressed, or silicone oil containing amino-modified silicone with good heat resistance is used to decompose the silicone oil in a flameproof furnace.
- the fine particle concentration at 2500 particles / L or less, for example, by suppressing it.
- the tensile strength level of the carbon fiber obtained can be kept at a high level.
- a light scattering particle counter (for example, RION KC-01E) can be used to measure the fine particle concentration. That is, gas is sucked for 34 seconds at a sample gas flow rate of 0.5 L / min, and 0.5 ⁇ m to less than 1.0 ⁇ m, 1.0 ⁇ m to less than 2.0 ⁇ m, 2.0 ⁇ m to less than 5.0 ⁇ m contained in 0.283 L
- the number of four-stage particles of 5.0 ⁇ m or more is simultaneously measured, and the values are set as D 0.5 , D 1.0 , D 2.0 , and D 5.0 (pieces / 0.283 L), respectively.
- grain into the particle number of 5.0 micrometers by the following conversion formulas is made into fine particle concentration.
- the flame resistance of the carbon fiber precursor fiber 2 is performed in an oxidizing atmosphere, specifically, as hot air at a maximum temperature of 200 to 300 ° C. under tension or stretching conditions.
- an oxidizing atmosphere specifically, as hot air at a maximum temperature of 200 to 300 ° C. under tension or stretching conditions.
- treated flame-resistant to a density of oxidized fiber after flame treatment is 1.30g / cm 3 ⁇ 1.40g / cm 3. If it is less than 1.30 g / cm 3 , the degree of progress of flame resistance is insufficient, and the carbon fiber obtained is likely to cause fusion between single yarns during pre-carbonization treatment and carbonization treatment performed after the flame resistance treatment. The quality of the product tends to deteriorate.
- the density of the flame-resistant fiber used for the fiber may exceed 1.40 g / cm 3 .
- it exceeds 1.50 g / cm 3 the time for firing the flameproof fiber becomes longer, which is not economically preferable. Therefore, it is preferred to treat oxidization to be in the range of 1.30g / cm 3 ⁇ 1.50g / cm 3.
- the hot air (oxidizing atmosphere) that fills the heat treatment chamber 3 of the flameproofing furnace 1 for performing the cleaning method of the present invention is not particularly limited as long as it is a gas containing oxygen, but air is used in terms of industrial production. Is particularly excellent in terms of economy and safety. Further, the oxygen concentration in the hot air can be changed for the purpose of adjusting the oxidation ability.
- Flame-resistant fibers obtained by flame-proofing are pre-carbonized at a maximum temperature of 300 to 1000 ° C in an inert atmosphere to produce pre-carbonized fibers, and carbonized at a maximum temperature of 1000 to 2000 ° C in an inert atmosphere. Carbon fiber is produced by processing. Further, after the carbon fiber is produced, it can be graphitized at a maximum temperature of 2000 to 3000 ° C. in an inert atmosphere to produce a graphitized fiber.
- the maximum temperature of the inert atmosphere in the pre-carbonization treatment is preferably 550 to 800 ° C.
- a known inert atmosphere such as nitrogen, argon, or helium can be adopted, but nitrogen is preferable from the viewpoint of economy.
- the pre-carbonized fiber obtained by the pre-carbonization process is then fed into a carbonization furnace and carbonized.
- a carbonization furnace In order to improve the mechanical properties of the carbon fiber, it is preferable to perform carbonization treatment at a maximum temperature of 1200 to 2000 ° C. in an inert atmosphere.
- the inert atmosphere filling the carbonization furnace a known inert atmosphere such as nitrogen, argon or helium can be adopted, but nitrogen is preferable from the viewpoint of economy.
- the carbon fiber thus obtained may be graphitized at a maximum temperature of 2000 to 3000 ° C. in an inert atmosphere, if necessary.
- a sizing agent may be added.
- the type of the sizing agent is not particularly limited as long as desired characteristics can be obtained, and examples thereof include a sizing agent mainly composed of an epoxy resin, a polyether resin, an epoxy-modified polyurethane resin, and a polyester resin. A known method can be used to apply the sizing agent.
- the carbon fiber may be subjected to electrolytic oxidation treatment or oxidation treatment for the purpose of improving the affinity and adhesion with the fiber reinforced composite material matrix resin, if necessary.
- the oxidizing gas having a temperature of 40 ° C. or higher is circulated in the flameproofing furnace and separated from the wall surface.
- the dust adhering to the inside of the flameproofing furnace can be efficiently removed.
- the productivity of flameproof fibers can be improved and the maintenance cost can also be reduced.
- the accumulation of dust in the flameproofing furnace is reduced, flameproof fiber without yarn breakage can be obtained, and as a result, high-quality carbon fiber can be produced from the early stage of restarting the flameproofing furnace 1. .
- the flame-resistant fiber was cut into a length of about 3 cm and fixed to a sample stage for an electron microscope so as not to move using a carbon tape. At this time, the yarn was spread thinly and uniformly, and was fixed so that the sample stage was not observed and the single yarns were not overlapped as much as possible.
- the particle size of the particle is represented by the length of the short diameter when the particle is approximated to an ellipse based on the least square method
- the size of the scratch is also the value when the scratch is approximated to an ellipse based on the least square method Expressed as the length of the minor axis. This observation was repeated over 1000 observation points, and the number of observed dust was divided by the total observation area and converted to the number of fine particles per 0.1 mm 2 .
- Example 1 A spinning stock solution was obtained by solution polymerization of a copolymer obtained by copolymerizing 99 mol% of acrylonitrile and 1 mol% of itaconic acid. This spinning dope was once discharged into the air using a spinneret and coagulated by a dry and wet spinning method introduced into a coagulation bath. The obtained coagulated yarn is washed with water, drawn and oiled, and then dried and steam drawn to obtain a polyacrylonitrile-based carbon fiber precursor fiber having a single yarn fineness of 1.1 dtex and a single yarn number of 10,000. It was.
- Oils include amino-modified dimethylsiloxane oil components that are water-dispersed using nonionic surfactants, and oil agents that are water-soluble by modifying dimethylpolysiloxane with polyethylene glycol, etc. A mixed amount was used.
- the carbon fiber precursor fiber was continuously fed into the flameproofing furnace 1 shown in FIGS. 1 and 6 and subjected to a flameproofing treatment.
- the temperature in the heat treatment chamber 3 was set to 250 ° C., and the carbon fiber precursor fiber 2 was subjected to flame resistance treatment under tension.
- the hot air outlet 5 in the flameproofing furnace 1 for flameproofing the polyacrylonitrile-based carbon fiber precursor fiber 2 to which the silicone-based oil is adhered under the above-mentioned flameproofing conditions has a large number of holes of ⁇ 10 mm made of SUS304 as a current plate.
- a perforated plate having a thickness of 2 mm was provided and subjected to flameproofing treatment continuously for one week.
- the obtained flame-resistant fiber was then fired at a maximum temperature of 700 ° C. in a pre-carbonization furnace, then fired at a maximum temperature of 1400 ° C. in a carbonization furnace, and subjected to sizing after electrolytic surface treatment to obtain a carbon fiber. .
- the flameproofing furnace 1 was stopped, and using the high pressure washer TRY-5NX2 manufactured by Ariko Kogyo Co., Ltd., the wall surface inside the flameproofing furnace was perpendicular to the surface to be cleaned. Washing was performed by supplying high-pressure water uniformly from a position 5.2 m away and bringing the high-pressure water into contact therewith. At this time, the pressure of the cleaning water contacting the wall surface to be cleaned was 2 MPa in the direction perpendicular to the wall surface. A prescale LWPS manufactured by FUJIFILM Corporation was used for pressure measurement. It took 10 hours to clean the entire flameproofing furnace, and the cleaning water was discharged out of the flameproofing furnace. Then, 80 degreeC hot air was circulated in the flameproofing furnace 1 using the air blower 8, and the inside of the flameproofing furnace was dried.
- TRY-5NX2 manufactured by Ariko Kogyo Co., Ltd.
- the flameproofing furnace 1 was restarted and the carbon fiber precursor fiber 2 was flameproofed. After the continuous treatment for 6 weeks, the inside of the flameproofing furnace was confirmed, and the perforated plate installed in the hot air outlet 5 was not clogged.
- the measurement result of the number of fine particles and scratches adhered to the flameproof fiber obtained one week after the start of operation was 18 / 0.1 mm 2 .
- Example 2 After one week of continuous flameproofing treatment, the flameproofing furnace 1 was stopped, and after performing high pressure washing, washing water discharge and drying as in Example 1, the circulation system of the flameproofing furnace as shown in FIG. A part of the duct was shut off by the switching valve 14, the exhaust port 13 and the air supply port 15 were opened, and the dust in the furnace was discharged by wind power from the blower 8. At this time, 90% of the suction air volume of the blower was exhausted, and the same amount of fresh air was introduced. By this operation, the wind speed in the flameproofing furnace changed instantaneously. Thereafter, the flameproofing furnace 1 was restarted, and the carbon fiber precursor fiber 2 was flameproofed. After the continuous treatment for 8 weeks, the inside of the flameproofing furnace was confirmed, and the perforated plate installed at the hot air outlet 5 was not clogged.
- the measurement result of the number of fine particles and scratches attached to the flameproof fiber obtained one week after the start of operation was 14 / 0.1 mm 2 .
- Example 3 After one week of continuous flameproofing treatment, the flameproofing furnace 1 was stopped, and cleaning was performed by supplying high-pressure water to the wall surface inside the flameproofing furnace from a position 4.3 m vertically away from the surface to be cleaned. Except for this, the procedure was the same as in Example 2. At this time, the pressure of the cleaning water contacting the wall surface to be cleaned was 3 MPa in the vertical direction. A prescale LLWPS manufactured by Fuji Film Co., Ltd. was used for pressure measurement. It took 8 hours to clean the entire flameproofing furnace. The flameproofing furnace 1 was restarted, and the carbon fiber precursor fiber 2 was flameproofed. After the continuous treatment for 9 weeks, the inside of the flameproofing furnace was confirmed, and the perforated plate installed at the hot air outlet 5 was not clogged.
- the measurement result of the number of fine particles and scratches attached to the flameproof fiber obtained one week after the start of operation was 12 / 0.1 mm 2 .
- Example 4 After the continuous flameproofing treatment for one week, the flameproofing furnace 1 was stopped and the temperature of the hot air circulated in the flameproofing furnace 1 was changed to 100 ° C., and was the same as in Example 3. Thereafter, the flameproofing furnace 1 was restarted, and the carbon fiber precursor fiber 2 was flameproofed. After the continuous treatment for 10 weeks, the inside of the flameproofing furnace was confirmed, and the perforated plate installed at the hot air outlet 5 was not clogged.
- the measurement result of the number of fine particles and scratches adhered to the flameproof fiber obtained one week after the start of operation was 10 / 0.1 mm 2 .
- Example 5 After one week of continuous flameproofing treatment, the flameproofing furnace 1 is stopped, and the same high pressure washing as in Example 3, discharge of washing water, drying in the furnace by circulating hot air, exhaust (discharge of dust), intake of fresh air After performing the above, before restarting the flameproofing furnace 1, the same high pressure washing as in Example 3, washing water discharge, drying in the furnace by circulating hot air, exhaust (dust discharge), and intake of fresh air are performed. It was. Thereafter, the flameproofing furnace 1 was restarted, and the carbon fiber precursor fiber 2 was flameproofed. After 11 weeks of continuous treatment, the inside of the flameproofing furnace was confirmed, and the perforated plate installed at the hot air outlet 5 was not clogged.
- the measurement result of the number of fine particles and scratches adhered to the flameproof fiber obtained one week after the start of operation was 10 / 0.1 mm 2 .
- Example 6 After one week of continuous flameproofing treatment, the flameproofing furnace 1 is stopped, and the same high pressure washing as in Example 4, washing water discharge, drying in the furnace by circulating hot air, exhaust (dust discharge), intake of fresh air Then, before restarting the flameproofing furnace 1, the same high pressure washing as in Example 4, washing water discharge, drying in the furnace by circulating hot air, exhaust (dust discharge), and intake of fresh air are performed. It was. Thereafter, the flameproofing furnace 1 was restarted, and the carbon fiber precursor fiber 2 was flameproofed. After the continuous treatment for 12 weeks, the inside of the flameproofing furnace was confirmed, and the perforated plate installed in the hot air outlet 5 was not clogged.
- the measurement result of the number of fine particles and scratches attached to the flameproof fiber obtained one week after the start of operation was 8 / 0.1 mm 2 .
- Example 1 the measurement result of the number of fine particles and scratches attached to the flameproof fiber obtained one week after the start of operation was 43 / 0.1 mm 2 .
- the flameproofing furnace 1 was restarted again, and the carbon fiber precursor fiber 2 was flameproofed. However, after continuous operation for 2 weeks, yarn breakage occurred in the flameproofing furnace, so the operation was stopped. When the operation was stopped and entered into the flameproofing furnace 1, it was confirmed that a plurality of portions clogged in the porous plate installed in the hot air outlet 5 were confirmed.
- Example 1 the measurement result of the number of fine particles and scratches attached to the flameproof fiber obtained one week after the start of operation was 33 / 0.1 mm 2 .
- the flameproofing furnace 1 was restarted again, and the carbon fiber precursor fiber 2 was flameproofed. However, after continuous operation for 3 weeks, yarn breakage occurred in the flameproofing furnace, so the operation was stopped. When the operation was stopped and entered into the flameproofing furnace 1, it was confirmed that a plurality of portions clogged in the porous plate installed in the hot air outlet 5 were confirmed.
- Example 1 the measurement result of the number of fine particles and scratches attached to the flameproof fiber obtained one week after the start of operation was 25 / 0.1 mm 2 .
- the flameproofing furnace 1 was restarted again, and the carbon fiber precursor fiber 2 was flameproofed. However, after continuous operation for 2 weeks, yarn breakage occurred in the flameproofing furnace, so the operation was stopped. When the operation was stopped and entered into the flameproofing furnace 1, it was confirmed that a plurality of portions clogged in the porous plate installed in the hot air outlet 5 were confirmed.
- Example 1 the measurement result of the number of fine particles and scratches attached to the flameproof fiber obtained one week after the start of operation was 40 / 0.1 mm 2 .
- the cleaning method of the present invention can remove the dust generated in the flameproofing treatment of the carbon fiber precursor fiber and adhered to the flameproofing furnace. As compared with the conventional cleaning method, it was evaluated that the flameproofing furnace can be operated continuously for a long time.
- the cleaning method for a flameproofing furnace of the present invention can be suitably used for the production of flameproofed fibers and carbon fibers.
Abstract
Description
(1) ポリアクリロニトリル系炭素繊維前駆体繊維を酸化性雰囲気中で耐炎化処理する耐炎化炉の洗浄方法であって、前記耐炎化炉は、酸化性気体が内部を循環する機構を有する耐炎化炉であり、該耐炎化炉の壁面に付着した粉塵に対し壁面に垂直な方向の圧力が2MPa以上となるように液体を接触させた後、該液体を耐炎化炉外に排出することで壁面から剥離した粉塵を耐炎化炉外に排出し、さらに、耐炎化炉内に温度40℃以上の酸化性気体を循環させる、耐炎化炉の洗浄方法。
(2) 酸化性気体を循環させた後、該酸化性気体を耐炎化炉外に排出することで壁面から剥離した粉塵をさらに耐炎化炉外に排出する、前記(1)に記載の耐炎化炉の洗浄方法
(3)耐炎化炉内に酸化性気体を循環させた後、次いで耐炎化炉内の酸化性気体の風向または風速を切り替え、その後に壁面から剥離した粉塵を耐炎化炉外に排出する、前記(2)に記載の耐炎化炉の洗浄方法。
(4) 耐炎化炉内に循環させる前記酸化性気体の温度が80℃以上である、前記(1)~(3)のいずれかに記載の耐炎化炉の洗浄方法。
(5) 前記(1)~(4)のいずれかに記載の耐炎化炉の洗浄方法により耐炎化炉を洗浄した後、ポリアクリロニトリル系炭素繊維前駆体繊維を耐炎化炉内で酸化性雰囲気中最高温度200~300℃で耐炎化処理する耐炎化繊維の製造方法。
(6) 前記(5)に記載の耐炎化繊維の製造方法により耐炎化繊維を製造した後、該耐炎化繊維を不活性雰囲気中最高温度300~1000℃で前炭素化処理して前炭素化繊維を製造し、該前炭素化繊維を不活性雰囲気中最高温度1000~2000℃で炭素化処理する炭素繊維の製造方法。
(7) 前記(6)に記載の炭素繊維の製造方法により炭素繊維を製造した後、該炭素繊維を不活性雰囲気中最高温度2000~3000℃で黒鉛化処理する黒鉛化繊維の製造方法。
壁面に接触する流体の壁面に垂直な方向の圧力測定は、富士フイルム株式会社製プレスケールLWPSおよびLLWPSを壁面に固定し、防水シートをかぶせた上で壁面に垂直に流体を万遍なく接触させた。その後、該プレスケールLWPSおよびLLWPSを取り外し、エプソン製スキャナーGT-F740 GT-X830を用いて該プレスケールLWPSおよびLLWPSの色の濃淡を読み取り、富士フイルム製プレスケール圧力画像解析システムFPD-8010Jを用いて壁面の接触圧力を測定した。なお、5カ所でこの圧力測定を行ったが、得られた圧力値のうちの最大値を壁面に対する垂直方向の接触圧力として採用した。
耐炎化繊維を約3cmの長さに切り出し、カーボンテープを用いて動かないように電子顕微鏡用サンプル台に固定した。この際、糸条は薄く均一に拡げ、サンプル台が観察されないように、また、なるべく単糸の重なりがないように固定した。イオンスパッタ(例えば、日立ハイテクノロジーズ社製E-1030)を用いて白金パラジウム合金により30秒間蒸着を行った後、走査型電子顕微鏡(SEM;例えば、日立ハイテクノロジーズ社製S4800)で加速電圧5.0kV、3000倍の倍率で単糸表面を観察し(1視野は42μm×32μm)、粒径0.3μm以上の微粒子の個数と、0.3μm以上の傷の個数をカウントした。ここで粒子の粒径とは、粒子を最小二乗法に基づき楕円形と近似したときの短径の長さで表し、傷の大きさも、傷を最小二乗法に基づき楕円状に近似したときの短径の長さで表した。本観察を観察点数1000点にわたり繰り返し行い、観察された粉塵の個数を観察総面積で割り、0.1mm2あたりの微粒子個数に換算した。
アクリロニトリル99モル%とイタコン酸1モル%が共重合してなる共重合体を、溶液重合法により紡糸原液を得た。この紡糸原液を、紡糸口金を用いて一旦空気中に吐出し、凝固浴に導入する乾湿式紡糸法により凝固させた。得られた凝固糸を、水洗、延伸、油剤付与した後、乾燥させ、スチーム延伸することで、単糸繊度1.1dtex、単糸本数10,000本のポリアクリロニトリル系炭素繊維前駆体繊維を得た。油剤は、アミノ変性されたジメチルシロキサン油剤成分を、ノニオン系界面活性剤を用いて、水分散系としたものと、ジメチルポリシロキサンをポリエチレングリコールで変性して水溶性にした油剤を純分で等量混合したものを用いた。
1週間の連続耐炎化処理の後、耐炎化炉1を停止し、実施例1と同様に高圧洗浄、洗浄水排出、および乾燥を行った後、図5に示すように耐炎化炉の循環系ダクトの一部を切り替え弁14で遮断し、かつ排気口13、給気口15を開放して、送風器8による風力で炉内の粉塵を排出した。このとき送風器の吸引風量の90%の風量を排気し、同量の新鮮な空気を取り入れた。この操作により、耐炎化炉内の風速が瞬間的に変化した。その後耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。8週間にわたる連続処理後、耐炎化炉内を確認したところ、熱風吹出口5に設置された多孔板に目詰まりはなかった。
1週間の連続耐炎化処理の後、耐炎化炉1を停止し、耐炎化炉内の壁面に、洗浄する面から垂直方向に4.3m離れた位置から高圧水を供給して洗浄を実施した以外は実施例2と同様とした。この時、洗浄する壁面に接触する洗浄水の圧力は垂直方向に3MPaであった。圧力の測定には富士フイルム株式会社製プレスケールLLWPSを用いた。耐炎化炉全体の洗浄には8時間を要した。耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。9週間にわたる連続処理後、耐炎化炉内を確認したところ、熱風吹出口5に設置された多孔板に目詰まりはなかった。
1週間の連続耐炎化処理の後、耐炎化炉1を停止し、耐炎化炉1内に循環させた熱風の温度を100℃にした以外は実施例3と同様とした。その後耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。10週間にわたる連続処理後、耐炎化炉内を確認したところ、熱風吹出口5に設置された多孔板に目詰まりはなかった。
1週間の連続耐炎化処理の後、耐炎化炉1を停止し、実施例3と同様の高圧洗浄、洗浄水排出、熱風循環による炉内乾燥、排気(粉塵の排出)、新鮮な空気の取り入れを行った後、耐炎化炉1を再稼動前に再度、実施例3と同様の高圧洗浄、洗浄水排出、熱風循環による炉内乾燥、排気(粉塵の排出)、新鮮な空気の取り入れを行った。その後耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。11週間にわたる連続処理後、耐炎化炉内を確認したところ、熱風吹出口5に設置された多孔板に目詰まりはなかった。
1週間の連続耐炎化処理の後、耐炎化炉1を停止し、実施例4と同様の高圧洗浄、洗浄水排出、熱風循環による炉内乾燥、排気(粉塵の排出)、新鮮な空気の取り入れを行った後、耐炎化炉1を再稼動前に再度、実施例4と同様の高圧洗浄、洗浄水排出、熱風循環による炉内乾燥、排気(粉塵の排出)、新鮮な空気の取り入れを行った。その後耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。12週間にわたる連続処理後、耐炎化炉内を確認したところ、熱風吹出口5に設置された多孔板に目詰まりはなかった。
1週間の連続耐炎化処理の後、耐炎化炉1を停止した後、耐炎化炉1の再稼働前に耐炎化炉1内に20℃の熱風を送風器8を用いて循環させた後、図5に示すように、耐炎化炉の循環系ダクトの一部を切り替え弁14で遮断し、かつ排気口13、給気口15を開放して、送風器8による風力で炉内の粉塵を排出した。このとき送風器8の吸引風量の90%の風量を排気し、同量の新鮮な空気を取り入れた。その後耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。
1週間の連続耐炎化処理の後、耐炎化炉1を停止し、耐炎化炉内の壁面に、洗浄する面から垂直方向に6.2m離れた位置から高圧水を供給して洗浄を実施した以外は実施例2と同様とした。この時洗浄する壁面に接触する洗浄水の圧力は垂直方向に1MPaであった。圧力の測定には富士フイルム株式会社製プレスケールLLWPSを用いた。24時間にわたり炉内を洗浄したが耐炎化炉内の壁面には洗浄しきれなかった粉塵が残存していた。
1週間の連続耐炎化処理の後、耐炎化炉1を停止し、耐炎化炉1内に循環させた熱風の温度を20℃にした以外は実施例3と同様とした。その後耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。耐炎化炉内の壁面には洗浄しきれなかった粉塵が残存していた。
1週間の連続耐炎化処理の後、耐炎化炉1を停止した後、耐炎化炉1内に循環させた熱風の温度を80℃にした以外は比較例1と同様とした。その後耐炎化炉1を再稼働し、炭素繊維前駆体繊維2の耐炎化処理を行った。耐炎化炉内の壁面には洗浄しきれなかった粉塵が残存していた。
2 炭素繊維前駆体繊維
3 熱処理室
4 熱風循環路
5 熱風吹出口
6 熱風排出口
7 加熱器
8 送風器
9 スリット
10 ガイドロール
11 洗浄ノズル
12 洗浄装置
13 排気口
14 切り替え弁
15 給気口
16 排気ファン
17 排ガス燃焼装置
Claims (7)
- ポリアクリロニトリル系炭素繊維前駆体繊維を酸化性雰囲気中で耐炎化処理する耐炎化炉の洗浄方法であって、前記耐炎化炉は、酸化性気体が内部を循環する機構を有する耐炎化炉であり、該耐炎化炉の壁面に付着した粉塵に対し壁面に垂直な方向の圧力が2MPa以上となるように液体を接触させた後、該液体を耐炎化炉外に排出することで壁面から剥離した粉塵を耐炎化炉外に排出し、さらに、耐炎化炉内に温度40℃以上の酸化性気体を循環させる、耐炎化炉の洗浄方法。
- 酸化性気体を循環させた後、該酸化性気体を耐炎化炉外に排出することで壁面から剥離した粉塵をさらに耐炎化炉外に排出する、請求項1に記載の耐炎化炉の洗浄方法
- 耐炎化炉内に酸化性気体を循環させた後、次いで耐炎化炉内の酸化性気体の風向または風速を切り替え、その後に壁面から剥離した粉塵を耐炎化炉外に排出する、請求項2に記載の耐炎化炉の洗浄方法。
- 耐炎化炉内に循環させる前記酸化性気体の温度が80℃以上である、請求項1~3のいずれかに記載の耐炎化炉の洗浄方法。
- 請求項1~4のいずれかに記載の耐炎化炉の洗浄方法により耐炎化炉を洗浄した後、ポリアクリロニトリル系炭素繊維前駆体繊維を耐炎化炉内で酸化性雰囲気中最高温度200~300℃で耐炎化処理する耐炎化繊維の製造方法。
- 請求項5に記載の耐炎化繊維の製造方法により耐炎化繊維を製造した後、該耐炎化繊維を不活性雰囲気中最高温度300~1000℃で前炭素化処理して前炭素化繊維を製造し、該前炭素化繊維を不活性雰囲気中最高温度1000~2000℃で炭素化処理する炭素繊維の製造方法。
- 請求項6に記載の炭素繊維の製造方法により炭素繊維を製造した後、該炭素繊維を不活性雰囲気中最高温度2000~3000℃で黒鉛化処理する黒鉛化繊維の製造方法。
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US16/468,135 US10612164B2 (en) | 2017-02-08 | 2018-01-29 | Method of cleaning oxidation oven and method of producing oxidized fiber, carbon fiber, and graphitized fiber |
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