WO2023093823A1 - 一种低缺陷聚丙烯腈基碳纤维制备方法 - Google Patents

一种低缺陷聚丙烯腈基碳纤维制备方法 Download PDF

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WO2023093823A1
WO2023093823A1 PCT/CN2022/134204 CN2022134204W WO2023093823A1 WO 2023093823 A1 WO2023093823 A1 WO 2023093823A1 CN 2022134204 W CN2022134204 W CN 2022134204W WO 2023093823 A1 WO2023093823 A1 WO 2023093823A1
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low
temperature
tow
temperature carbonization
furnace
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PCT/CN2022/134204
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French (fr)
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张国良
陈秋飞
郭鹏宗
刘高君
裴怀周
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中复神鹰碳纤维股份有限公司
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    • 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
    • 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
    • D01F9/328—Apparatus therefor for manufacturing filaments from polyaddition, polycondensation, or polymerisation products

Definitions

  • the present disclosure relates to but is not limited to a method for preparing low-defect polyacrylonitrile-based carbon fibers.
  • Carbon fiber reinforced epoxy resin composites have the highest specific strength and specific modulus among existing engineering materials.
  • the market demand for high-performance carbon fibers has also shown a huge increase, especially for high-performance polyacrylonitrile-based carbon fibers. Therefore, how to further improve The performance of polyacrylonitrile-based carbon fiber has always been the focus and difficulty in the development of carbon fiber technology.
  • the weight loss of carbon fiber is usually more than 40%.
  • the non-carbon elements O, H, and N in the fiber escape in large quantities.
  • the weightless fiber changes from solid to gaseous state, and a large amount of pyrolysis gas is bound to be produced.
  • the waste gas and tar produced are as follows: If it is not discharged in time, it will not only pollute the fibers running in the furnace cavity, produce local defects, and even cause larger defects in the high-temperature carbonization process, but also the accumulation of tar will shorten the production line operation cycle and indirectly increase the production line operation cost. Therefore, the instantaneous waste discharge of low temperature carbonization furnace is usually the focus of low temperature furnace structure design and process optimization.
  • the low-temperature carbonization process (usually between 300-1000°C) is dominated by thermal decomposition reactions, while the high-temperature carbonization process (usually between 1000-1500°C) is dominated by thermal polycondensation reactions, and the drafting ratio of the process is also different, so
  • the low-temperature carbonization and high-temperature carbonization furnaces are usually split-type design.
  • the application provides a method for preparing low-defect polyacrylonitrile-based carbon fibers, the method comprising:
  • the monofilament strength of the carbon fiber precursors is ⁇ 7.0cN/dtex, and the fineness of the carbon fiber precursors is 0.50dtex-0.70dtex;
  • the density range of the pre-oxidized silk tow is between 1.340g/cm 3 and 1.360g/cm 3 ;
  • the furnace head and the tail of the low-temperature carbonization furnace are equipped with two-stage Air-enclosed chamber, the pressure difference between the first-stage air-enclosed chamber and the second-stage air-enclosed chamber of the two-stage air-enclosed chamber is between 1Pa ⁇ 10Pa, and the draft rate of the tow in the low-temperature carbonization furnace is +1% ⁇ +5%;
  • the high carbon filament bundles are drawn into a sizing tank for sizing, and the sized high carbon filament bundles are dried at a temperature of 150°C.
  • the pre-oxidation temperature of each pre-oxidation furnace is 200°C-300°C, and the temperature control accuracy of the heating area of each pre-oxidation furnace is within ⁇ 2°C.
  • the first-stage air-sealing chamber of each of the two-stage air-sealing chambers of the low-temperature carbonization furnace is connected to the low-temperature furnace waste gas treatment system through a fan, so as to separate the first-stage air-sealing chamber from the second-stage air-sealing chamber.
  • the pressure difference between the chambers is maintained at 1Pa to 10Pa.
  • the secondary air-enclosed chamber located at the furnace head of the low-temperature carbonization furnace includes a heating device, and the heating temperature of the heating device is 150°C-400°C.
  • the low-temperature carbonization furnace includes 6 to 8 first heating temperature zones, the carbonization temperature of each of the first heating temperature zones is 300°C to 1000°C, and the heating rate of each of the first heating temperature zones is about 40 °C/min ⁇ 100°C/min.
  • the tail end of the low-temperature carbonization furnace is provided with a first water cooling system to control the temperature of the low-carbon filament bundle drawn from the low-temperature carbonization furnace not to exceed 150°C.
  • the tow dehumidification device is arranged at the furnace mouth of the high-temperature carbonization furnace, and there is a gap of 5 mm to 50 mm between the tow dehumidification device and the furnace mouth of the high-temperature carbonization furnace.
  • the tow dehumidification device blows hot air from the middle of the high-temperature carbonization furnace to both ends of the high-temperature carbonization furnace, the temperature of the hot air is between 110°C and 150°C, and the speed of the hot air does not exceed 5m/s.
  • the high-temperature carbonization furnace includes 4 to 8 second heating temperature zones, the carbonization temperature of each of the second heating temperature zones is 1000°C to 1600°C, and the temperature rise rate of each of the second heating temperature zones is 100°C/min ⁇ 150°C/min.
  • the surface treatment of the high-carbon filament bundle is carried out with an electrolyte, and the electrolyte is an ammonium salt electrolyte.
  • the electrolyte includes at least one of ammonium bicarbonate, ammonium dihydrogen phosphate and ammonium sulfate.
  • a sizing agent is accommodated in the sizing tank, and the high carbon filament tow is sized by infiltrating the high carbon filament tow with the sizing agent.
  • the sizing agent includes epoxy resin, and the concentration of the sizing agent is 0.5%-1.5%.
  • Fig. 1 is a schematic diagram of a low temperature carbonization furnace according to an exemplary embodiment.
  • Fig. 2 is a schematic diagram of a high temperature carbonization furnace according to an exemplary embodiment.
  • First air seal chamber 2: Second air seal chamber, 3: Fan; 4: Nitrogen air seal, 5: Electric heating, 6: Low temperature furnace body, 7: Third air seal chamber, 8, First water cooling System, 9, the fourth air-tight chamber; 10, exhaust pipe.
  • 11 Tow dehumidification device, 11-1: Hot air pipe, 12: High temperature furnace head air seal, 13, High temperature furnace head exhaust pipe, 14: High temperature furnace body, 15: Second water cooling system, 16: Furnace tail gas seal up.
  • An exemplary embodiment of the present disclosure provides a method for preparing low-defect polyacrylonitrile-based carbon fibers, including the following steps:
  • Step S110 Preparing carbon fiber precursors, the single filament strength of the carbon fiber precursors is ⁇ 7.0 cN/dtex, and the fineness of the carbon fiber precursors is 0.50 dtex ⁇ 0.70 dtex.
  • the carbon fiber precursor can be provided in the form of a coil, and the coil of the carbon fiber precursor is placed on the unwinding mechanism, so that the carbon fiber precursor can be continuously provided by the unwinding mechanism.
  • Step S120 Pulling the carbon fiber precursors, passing through multiple independent temperature-controlled pre-oxidation furnaces in turn, the total draft rate of the carbon fiber precursors for the multiple pre-oxidation furnaces is -12% to +5%, and pre-oxidizing the carbon fiber precursors to form
  • the pre-oxidized silk tow has a density range of 1.340 g/cm 3 to 1.360 g/cm 3 .
  • the carbon fiber precursors are pulled through multiple independent temperature-controlled pre-oxidation furnaces for pre-oxidation treatment.
  • the number of pre-oxidation furnaces is greater than two, and the number of pre-oxidation furnaces is set according to production requirements. Oxidation furnace, three pre-oxidation furnaces, four pre-oxidation furnaces, etc.
  • Each pre-oxidation furnace is independently heated to pre-oxidize the carbon fiber precursor.
  • the pre-oxidation temperature of each pre-oxidation furnace is 200° C. to 300° C.
  • the temperature control accuracy of the heating area of each pre-oxidation furnace is within ⁇ 2° C.
  • the carbon fiber precursors are uniformly pre-oxidized through multiple pre-oxidation furnaces to form pre-oxidized filament bundles.
  • Each pre-oxidation furnace is independently driven, therefore, a plurality of pre-oxidation furnaces may have different drafting ratios to the carbon fiber precursors.
  • the drafting rate of so that the total drafting rate of multiple pre-oxidation furnaces to carbon fiber precursors is -12% ⁇ +5%.
  • the total drafting rate of multiple pre-oxidation furnaces to carbon fiber precursors can be -12%, -10%, -8%, -6%, -4%, -2%, 0, 1%, 3% or 5%, etc.
  • Carbon fiber precursors are pre-oxidized to form pre-oxidized fiber bundles, and the density range of pre-oxidized fiber bundles is between 1.340g/cm 3 and 1.360g/cm 3 , for example, the density of pre-oxidized fiber bundles can be 1.340g/cm 3 cm 3 , 1.345 g/cm 3 , 1.350 g/cm 3 , 1.355 g/cm 3 or 1.360 g/cm 3 .
  • Step S130 pulling the pre-oxidized filament tow, and carrying out low-temperature carbonization treatment in a low-temperature carbonization furnace equipped with a two-stage air-enclosed chamber structure to form a low-carbon filament tow.
  • the pressure difference between the first air seal chamber and the second air seal chamber of the two air seal chambers is between 1Pa and 10Pa, and the draft rate of the tow in the low temperature carbonization furnace is +1% to +5%.
  • the pre-oxidized wire bundle is drawn into the low-temperature carbonization furnace for low-temperature carbonization treatment.
  • the secondary air-enclosed chamber located at the furnace head includes a heating device, and the heating temperature of the heating device is 150 ° C ⁇ 400°C, the maximum temperature of the secondary air-enclosed chamber at the furnace head is 400°C.
  • the heating device is used for heating the pre-oxidized silk tow, which is beneficial to improve the low-temperature carbonization efficiency of the pre-oxidized silk tow.
  • the low-temperature carbonization furnace includes 6 to 8 first heating temperature zones arranged in sequence, and the carbonization temperature of each first heating temperature zone is 300°C to 1000°C.
  • the heating rate of the first heating zone is 40°C/min-100°C/min.
  • the carbonization temperatures in the first heating temperature zone of the low-temperature carbonization furnace are approximately the same, so that the pre-oxidized filament bundles are uniformly carbonized at low temperature in the low-temperature carbonization furnace to form low-carbon filament bundles.
  • the carbonization temperature of each first heating temperature zone may be 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C or 1000°C.
  • the furnace tail of the low temperature carbonization furnace is equipped with a first water cooling system to control the temperature of the low carbon filament bundle drawn from the low temperature carbonization furnace not to exceed 150°C.
  • the carbonization temperature of the low-temperature carbonization furnace is relatively high, therefore, the temperature of the low-carbon filament tow formed by the low-temperature carbonization of the pre-oxidized filament tow is also high, and the low-carbon filament tow needs to pass through the tail end of the low-temperature carbonization furnace to enter the subsequent high-temperature carbonization In the furnace, the temperature of the low-carbon filament bundles is lowered to below 150°C after being cooled by the first water cooling system.
  • control the drafting rate by controlling the speed at which the low-temperature carbonization furnace drives and pulls the pre-oxidized silk tow, and the draft rate of the low-temperature carbonization furnace to the tow is +1% to +5%.
  • the draft ratio can be +1%, +2%, +3%, +4% or +5%.
  • Step S140 pulling the low-carbon filament tow, and performing high-temperature carbonization treatment in a high-temperature carbonization furnace equipped with a tow dehumidification device to form a high-carbon filament tow.
  • the draft rate of the high-temperature carbonization furnace for the tow is -2% to -8% %.
  • the high-temperature carbonization furnace includes a tow dehumidification device, and the tow dehumidification device is arranged on the side where the furnace mouth of the high-temperature carbonization furnace is located. There is a gap of 5 mm to 50 mm between the tow dehumidification device and the furnace mouth of the high temperature carbonization furnace at the front end of the mouth.
  • the height of the tow dehumidifier is 5 mm to 30 mm.
  • the tow dehumidifier can be a cylindrical structure with a height of 5 mm to 30 mm.
  • One opening of the cylindrical structure faces the low-temperature carbonization furnace, and the other opening of the cylindrical structure faces At the furnace mouth of the high-temperature carbonization furnace, the low-carbon filament bundle enters through one opening of the cylindrical structure, and passes through the other opening of the cylindrical structure into the high-temperature carbonization furnace.
  • the tow dehumidification device blows hot air from the middle to both ends.
  • the temperature of the hot air is 110°C to 150°C, and the speed of the hot air does not exceed 5m/s.
  • the hot air blows to remove the moisture on the surface of the low-carbon filament tow, and the moisture on the surface of the low-carbon filament tow escapes from the tow dehumidification device and the furnace mouth of the high-temperature carbonization furnace to ensure that the low-carbon filament tow entering the high-temperature carbonization furnace Dry with no residual moisture.
  • the cylindrical structure does not constitute a limitation to the tow dehumidification device, and the tow dehumidification device can be a structure capable of removing the surface moisture of the low-carbon filament tow, and the tow dehumidification device can be set as required For any shape and any structure.
  • the high-temperature carbonization furnace includes 4 to 8 second heating temperature zones arranged in sequence, and the number of the second heating temperature zones can be set to 4, 5, or 6 according to production requirements. or 8.
  • the carbonization temperature of each second heating temperature zone is 1000°C to 1600°C, for example, it can be 1000°C, 1200°C, 1500°C, 1600°C, and the heating rate of each second heating temperature zone is 100°C/min to 150°C °C/min.
  • the low-carbon filament bundles After entering the high-temperature carbonization furnace, the low-carbon filament bundles pass through each second heating temperature zone in turn, and the low-carbon filament bundles are uniformly carbonized at high temperature in the high-temperature carbonization furnace to form high-carbon filament bundles.
  • Step S150 Pulling the high-carbon filament bundles, passing through one to two-stage surface treatment tanks for surface treatment, cleaning the surface-treated high-carbon filament bundles, and drying the high-carbon filament bundles.
  • the surface of the high-carbon filament tow is treated with electrolyte to reduce the surface defects of the high-carbon filament tow, so as to facilitate subsequent sizing of the high-carbon filament tow.
  • the electrolyte is an ammonium salt electrolyte.
  • the electrolyte includes at least one of ammonium bicarbonate, ammonium dihydrogen phosphate and ammonium sulfate.
  • the power of surface treatment is set according to the application requirements, for example, it can be set to 1c/g-50c/g.
  • the high-carbon filament bundles were washed with deionized water to remove residual electrolyte. Next, dry the high-carbon filament bundles.
  • the high-carbon filament bundles can be dried by drying, but this does not constitute a limitation to this solution.
  • Step S160 Pulling the high carbon fiber bundles into a sizing tank for sizing, and drying the sized high carbon fiber bundles at a temperature of 150°C.
  • the high carbon fiber tow is soaked in the sizing tank.
  • the sizing agent is attached to the surface of the dry high carbon fiber tow, and the high carbon tow is sized by the sizing agent. .
  • the sizing agent can be an epoxy resin sizing agent, and the sizing agent includes epoxy resin; the concentration of the sizing agent is 0.5% to 1.5%, for example, the concentration of the epoxy resin in the sizing agent is 0.5%, 0.8%, 1.2% , 1.5%.
  • the sized high-carbon filament bundles were dried at a temperature of 150° C. to obtain low-defect polyacrylonitrile-based carbon fibers.
  • the low-defect polyacrylonitrile-based carbon fibers prepared in this example had few defects such as pores or holes on the surface, and at the same time Improved fiber strength.
  • this embodiment is an illustration of the above-mentioned embodiments.
  • the difference between this embodiment and the above-mentioned embodiments is that the first-stage air-enclosed chamber of each two-stage air-enclosed chamber of the low-temperature carbonization furnace is connected by a fan To the low-temperature furnace exhaust gas treatment system to maintain the pressure difference between the first-stage air confinement chamber and the second-stage air confinement chamber at 1Pa to 10Pa.
  • the pyrolysis gas generated by the low-temperature carbonization of the pre-oxidized silk tow in the low-temperature carbonization furnace is discharged to the low-temperature furnace exhaust gas treatment system through the fan, which improves the low-temperature carbonization process.
  • the waste discharge ability of the furnace can avoid the adverse effect of pyrolysis gas on the pre-oxidized filament bundle, so that the quality of the formed low-defect polyacrylonitrile-based carbon fiber can be improved, and the carbon fiber defect can be further reduced.
  • the method for preparing low-defect polyacrylonitrile-based carbon fibers in this embodiment, after unwinding the carbon fiber precursors, they sequentially go through the pre-oxidation furnace, low-temperature carbonization furnace, high-temperature carbonization furnace, surface treatment, water washing, sizing, drying and winding carbonization processes A low-defect polyacrylonitrile-based carbon fiber is obtained.
  • Figure 1 shows the structure of the low-temperature carbonization furnace used in the preparation method of the present embodiment.
  • the low-temperature carbonization furnace comprises a first air-enclosed chamber 1, a second air-enclosed chamber 2, and a low-temperature furnace body arranged in sequence. 6.
  • the first air confinement chamber 1 and the second air confinement chamber 2 form a two-stage air confinement chamber at the burner head of the low-temperature carbonization furnace, and the third air confinement chamber 7 and the fourth air confinement chamber 9 constitute two-stage confinement chambers at the tail end of the low-temperature carbonization furnace. Airlock.
  • the second air seal chamber 2 is provided with a nitrogen air seal 4 and a heating device 5; the low temperature carbonization furnace 6 also has a waste discharge pipeline 10, and the waste discharge pipe 10 is connected with a blower fan 3; the third air seal chamber 7 is provided with a first water cooling system 8. Both the first air-enclosed chamber 1 and the fourth air-enclosed chamber 9 (furnace tail) are provided with passages connected with the fan 3 .
  • FIG 2 shows the structure of the high-temperature carbonization furnace that is provided with a tow dehumidifier used in the preparation method of the present embodiment.
  • the tow dehumidifier 11 the high-temperature furnace burner air seal 12, High temperature furnace body 14, high temperature furnace tail gas seal 16.
  • the tow dehumidification device 11 is equipped with a hot air duct 11-1
  • the high temperature furnace head air seal 12 is equipped with a high temperature furnace head waste pipe 13
  • the high temperature carbonization furnace tail is provided with a second water cooling system 15.
  • carbon fiber precursors which are prepared by dry-jet wet spinning process.
  • the single filament strength of carbon fiber precursors is ⁇ 7.0cN/dtex, and the fineness of carbon fiber precursors is 0.50dtex-0.70dtex.
  • the carbon fiber precursor After the carbon fiber precursor is unwound, it passes through three independent temperature-controlled pre-oxidation furnaces in sequence.
  • the pre-oxidation temperature of each pre-oxidation furnace is between 200°C and 300°C. Temperature accuracy is within ⁇ 2°C.
  • the tow in the furnace is drawn to different degrees through the independent drive between each oxidation furnace, and the total draft rate of the three pre-oxidation furnaces is -12% to +5%.
  • the density range of the pre-oxidized silk bundles formed in this embodiment is between 1.340 g/cm3 and 1.360 g/cm3.
  • the pre-oxidized wire tow is drawn into a low-temperature carbonization furnace equipped with a high-efficiency coke discharge system, and the pre-oxidized wire tow passes through the low-temperature carbonization furnace from the furnace head to the furnace tail.
  • the burner head of the low-temperature carbonization furnace is provided with a first air seal chamber 1 and a second air seal chamber 2, the pressure difference between the first air seal chamber 1 and the second air seal chamber 2 is between 1Pa and 10Pa, and the second air seal chamber of the burner head
  • the maximum heating temperature in the air-enclosed chamber 2 is 400°C.
  • the tail of the low-temperature carbonization furnace is provided with a third air-enclosed chamber 7 and a fourth air-enclosed chamber 9.
  • the third air-enclosed chamber 7 is equipped with a first water-cooling device 8. To control the temperature of the tow passing through the low temperature carbonization furnace not to exceed 150°C.
  • the low-temperature carbonization furnace is divided into 6 to 8 heating temperature zones, the carbonization temperature is 300°C to 1000°C, and the heating rate is about 40°C/min to 100°C/min; the low-temperature carbonization draft rate is controlled by the front and rear drive speed ratio of the low-temperature carbonization furnace , the draft rate is +1% ⁇ +5%, and the pre-oxidized silk tow is carbonized at a low temperature in a low-temperature carbonization furnace to form a low-carbon tow.
  • the temperature of the low-carbon filament bundle passing through the low-temperature carbonization furnace is lower than 150° C., for example, the temperature of the low-carbon filament bundle passing through the low-temperature carbonization furnace can be 145° C., 140° C. or lower.
  • the low-carbon tow is pulled through the tow dehumidification device and then enters the high-temperature carbonization furnace.
  • the heating method of the tow dehumidification device 11 is to blow hot air from the middle to both ends.
  • the temperature of the hot air is between 110 and 150 ° C.
  • the tow dehumidification device 11 can use the first water cooling device of the low-temperature carbonization furnace 8 and the heat exchanged with low-carbon filament bundles for air heating, and the hot wind speed does not exceed 5m/s;
  • the system is used to reduce the temperature of the tow passing out of the high-temperature carbonization furnace.
  • the temperature of the tow passing out of the high-temperature carbonization furnace does not exceed 150°C.
  • the high temperature carbonization furnace is divided into 4 to 8 heating temperature zones, the carbonization temperature is 1000°C to 1600°C, and the heating rate is about 100°C/min to 150°C/min.
  • the low-carbon filament tow is carbonized by high temperature through a high-temperature carbonization furnace to form a high-carbon filament tow.
  • the draft ratio of the high temperature carbonization is controlled by controlling the front and rear driving speed ratio of the high temperature carbonization furnace, and the draft ratio is -8% to -2%.
  • the high-carbon filament bundles are drawn through one to two-stage surface treatment tanks, and electrolytes are accommodated in the surface treatment tanks, and the surface treatment of the high-carbon filament bundles is carried out through the electrolytes.
  • the electrolyte can include ammonium salt electrolytes such as ammonium bicarbonate, ammonium dihydrogen phosphate, and ammonium sulfate.
  • the surface treatment power is set according to the application requirements, preferably 1-50c/g; and the high-carbon filament bundles after surface treatment are washed with water After drying.
  • the sizing agent can be an epoxy resin sizing agent.
  • the sizing agent includes epoxy resin, and the concentration of the sizing agent is 0.5%. ⁇ 1.5%, for example, the concentration of sizing agent can be 0.5%, 0.8%, 1.2%, 1.5%.
  • the sized high-carbon filament bundles are dried in a drying oven at about 150°C to obtain low-defect polyacrylonitrile-based carbon fibers.
  • Table 1 shows the specific parameters of the preparation process in the method for preparing low-defect polyacrylonitrile-based carbon fibers of Examples 1-5. It should be pointed out that the specific parameters in the preparation method of the low-defect polyacrylonitrile-based carbon fiber of the present application are not limited to the data in Table 1.
  • Example 1 Example 2
  • Example 3 Example 4
  • Example 5 Example 6 pre-oxygen stretching 0.95 0.95 0.95 0.92 0.92 0.94
  • Pre-oxygenation temperature/°C 274 274 274 276 276 low carbon draft 1.02 1.02 1.02 1.02 1.01
  • Low carbon temperature/°C 700 700 700 720 720
  • Chamber pressure Pa -2 -4 -5 -5 -4 -3 Second chamber pressure Pa -1 -1 -2 -2 -1 -1 High carbon draft 0.96 0.96 0.96 0.97 0.97 0.95
  • Table 2 shows specific parameters for preparing carbon fibers in Comparative Example 1, Comparative Example 2 and Comparative Example 3.
  • Comparative example 1 Comparative example 2 Comparative example 3 pre-oxygen stretching 0.95 0.88 0.95 Pre-oxygenation temperature/°C 274 274 274 low carbon draft 1.02 1.02 1.02 Low carbon temperature/°C 700 700 700
  • Chamber pressure Pa none none -2 Second chamber pressure Pa +1 -1 -1 High carbon draft 0.95 0.97 0.95 High carbon temperature/°C 1450 1450 1450 High carbon dehumidification temperature/°C / / / High temperature furnace head dew point ppm 8.3 8.3 8.3
  • the small-angle X-ray diffraction method was used to detect the size and distribution of pores or holes on the low-defect polyacrylonitrile-based carbon fibers prepared in Examples 1-5 and the carbon fibers in Comparative Examples 1-3.
  • the test results are shown in Table 3.
  • the carbon fiber prepared by the low-defect polyacrylonitrile-based carbon fiber preparation method of the present application has smaller micropore volume and fewer structural defects, and at the same time improves the strength of the carbon fiber.
  • the low-defect polyacrylonitrile-based carbon fiber preparation method of this embodiment promotes the discharge of pyrolysis gas in the low-temperature carbonization furnace through the pressure difference between the first air-enclosed chamber and the second air-enclosed chamber, so as to avoid the disadvantages of the pyrolyzed gas to the pre-oxidized tow impact, can improve the quality of the formed low-defect polyacrylonitrile-based carbon fiber and reduce fiber defects; at the same time, the tow dehumidification device can dehumidify the tow entering the high-temperature carbonization furnace at high temperature to avoid water vapor damage to the tow during high-temperature carbonization, reducing the Defects in the high-temperature carbonization process; at the same time, this embodiment also further slows down the expansion of fiber defects generated in the carbonization process by adjusting the draft ratio of the three stages of pre-oxidation, low-temperature carbonization and high-temperature carbonization.
  • the pressure difference between the first air-sealed chamber and the second air-sealed chamber is used to promote the discharge of the pyrolysis gas in the low-temperature carbonization furnace, so as to avoid the impact of the pyrolysis gas on the carbon fiber.
  • the adverse effect of pre-oxidized tow can improve the quality of the formed low-defect polyacrylonitrile-based carbon fiber and reduce fiber defects; at the same time, the tow entering the high-temperature carbonization furnace is dehumidified at high temperature through the tow dehumidification device to avoid the high-temperature carbonization process.
  • this embodiment further slows down the expansion of fiber defects generated by the carbonization process by adjusting the drafting ratio of the three stages of pre-oxidation, low-temperature carbonization and high-temperature carbonization.

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Abstract

本申请公开一种低缺陷聚丙烯腈基碳纤维制备方法，涉及碳纤维技术领域，制备方法包括：准备碳纤维原丝；牵引碳纤维原丝经过多台独立控温的预氧化炉，将碳纤维原丝预氧化形成预氧丝丝束；牵引预氧丝丝束，经过设有两级气封室结构的低温碳化炉进行低温碳化处理，形成低碳丝丝束；牵引低碳丝丝束，经过设有丝束除湿装置的高温碳化炉进行高温碳化处理，形成高碳丝丝束；牵引高碳丝丝束，经过一至两级的表面处理槽进行表面处理；高碳丝丝束上浆后干燥。

Description

一种低缺陷聚丙烯腈基碳纤维制备方法
本公开基于申请号为202111415584.5、申请日为2021年11月25日、申请名称为“一种低缺陷聚丙烯腈基碳纤维制备方法”的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此引入本公开作为参考。
技术领域
本公开涉及但不限于一种低缺陷聚丙烯腈基碳纤维制备方法。
背景技术
碳纤维增强环氧树脂复合材料，其比强度及比模量在现有工程材料中是最高的。随着碳纤维复合材料在压力容器、航空和航天等领域中应用技术的日益成熟，市场对高性能碳纤维的需求也呈现巨大增长，尤其对高性能聚丙烯腈基碳纤维需求最为显著，故而如何进一步提升聚丙烯腈基碳纤维性能一直以来都是碳纤维技术开发的重点和难点。
低温碳化过程中碳纤维失重通常在40％以上，纤维中的非碳元素O、H、N大量逸出，失重的纤维由固态变为气态，势必有大量热解气体产生，产生的废气和焦油如不及时排出，不仅污染在炉腔内运行的纤维，产生局部缺陷，甚至导致其在高温碳化过程产生更大的缺陷，而且焦油的积聚也会缩短产线运行周期，间接增加产线运行成本。故而低温碳化炉的瞬时排废通常为低温炉结构设计和工艺优化的重点。以提质增效为出发点，碳纤维的单线产能正在稳步提升，这也对低温炉排废能力提出了更高的要求。此外，在低温碳化工艺管控中存在一个矛盾点，为减少废气和焦油对丝束的不利影响，需要尽可能增大废气排出能力，但随着排废能力的提升，炉头炉尾的气封效果又会大打折扣，甚至造成炉内进氧而导致碳纤维性能急剧下降，在日常工艺优化过程中经常需要耗费很长的时间寻找低温碳化状态的平衡点，费时费力且不利于产品性能的稳定性提升。
低温碳化过程(通常在300～1000℃之间)以热分解反应为主，而高温碳化过程(通常在1000～1500℃之间)以热缩聚反应为主，其过程牵伸倍率也不同，故而低温碳化和高温碳化炉通常为分体式设计，实际生产过程中通常在低温炉至高温炉中间留有3～5米的操作区域，这也导致低温炉出口的高热纤维(通常大于150℃)在此区域运行过程中(通常约1～5min)吸收空气中的水蒸气，并将其带入高温炉。尽管丝束带入的水汽大部分会由炉口气封吹出或者随着高温炉头排废管道排出，但仍会有一部分水汽被带入炉腔，并在高温碳化过程中与纤维上的碳原子结合并以CO+H2或CO的形式逸出，从而导致纤维孔隙甚至孔洞等缺陷的产生。
发明内容
以下是对本公开详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请提供了一种低缺陷聚丙烯腈基碳纤维制备方法，方法包括：
准备碳纤维原丝，所述碳纤维原丝的单丝强度≥7.0cN/dtex，所述碳纤维原丝的纤度为0.50dtex～0.70dtex；
牵引所述碳纤维原丝，依次经过多台独立控温的预氧化炉，多台所述预氧化炉对所述碳纤维原丝的总牵伸率为-12～+5％，将所述碳纤维原丝预氧化形成预氧丝丝束，所述预氧丝体丝束的密度范围在1.340g/cm 3～1.360g/cm 3之间；
牵引所述预氧丝丝束，经过设有两级气封室结构的低温碳化炉进行低温碳化处理，形成低碳丝丝束，所述低温碳化炉的炉头和炉尾均设有两级气封室，所述两级气封室的一级 气封室与二级气封室的压力差在1Pa～10Pa之间，所述低温碳化炉对丝束的牵伸率为+1％～+5％；
牵引所述低碳丝丝束，经过设有丝束除湿装置的高温碳化炉进行高温碳化处理，形成高碳丝丝束，所述高温碳化炉对丝束的牵伸率为-8％～-2％；
牵引所述高碳丝丝束，经过一至两级的表面处理槽进行表面处理，清洗表面处理后的所述高碳丝丝束后干燥所述高碳丝丝束；
牵引所述高碳丝丝束进入上浆槽上浆，将上浆后的所述高碳丝丝束在150℃温度条件下干燥。
其中，每台所述预氧化炉的预氧化温度为200℃～300℃，每台所述预氧化炉的加热区域的控温精度在±2℃以内。
其中，所述低温碳化炉每个所述两级气封室的所述一级气封室通过风机连接至低温炉废气处理系统，以将所述一级气封室与所述二级气封室之间的压力差维持在1Pa～10Pa。
其中，位于所述低温碳化炉的炉头的所述二级气封室包括加热装置，所述加热装置的加热温度为150℃～400℃。
其中，所述低温碳化炉包括6～8个第一加热温区，每个所述第一加热温区的碳化温度300℃～1000℃，每个所述第一加热温区的升温速率约40℃/min～100℃/min。
其中，所述低温碳化炉的炉尾设有第一水冷系统，以控制从所述低温碳化炉牵引出的所述低碳丝丝束的温度不超过150℃。
其中，所述丝束除湿装置设置在所述高温碳化炉的炉口处，所述丝束除湿装置和所述高温碳化炉的炉口之间具有5mm～50mm的间隙。
其中，所述丝束除湿装置自所述高温碳化炉的中间向所述高温碳化炉的两端吹扫热风，热风温度为110℃～150℃之间，热风风速不超过5m/s。
其中，所述的高温碳化炉包括4～8个第二加热温区，每个所述第二加热温区的碳化温度1000℃～1600℃，每个所述第二加热温区的升温速率为100℃/min～150℃/min。
其中，采用电解质对所述高碳丝丝束进行表面处理，所述电解质为铵盐类电解质。
其中，所述电解质包括碳酸氢铵、磷酸二氢铵和硫酸铵中的至少一种。
其中，所述上浆槽中容置上浆剂，通过所述上浆剂浸润所述高碳丝丝束对所述高碳丝丝束上浆。
其中，所述上浆剂包括环氧树脂，所述上浆剂的浓度为0.5％～1.5％。
在阅读并理解了附图和详细描述后，可以明白其他方面。
附图说明
并入到说明书中并且构成说明书的一部分的附图示出了本公开的实施例，并且与描述一起用于解释本公开实施例的原理。在这些附图中，类似的附图标记用于表示类似的要素。下面描述中的附图是本公开的一些实施例，而不是全部实施例。对于本领域技术人员来讲，在不付出创造性劳动的前提下，可以根据这些附图获得其他的附图。
图1为根据一示例性实施例示出的低温碳化炉的示意图。
图2为根据一示例性实施例示出的高温碳化炉的示意图。
附图说明：
1、第一气封室、2：第二气封室、3：风机；4：氮气气封、5：电加热、6：低温炉本体、7：第三气封室、8、第一水冷系统、9、第四气封室；10、排废管道。
11：丝束除湿装置、11-1：热风管道、12：高温炉炉头气封、13、高温炉炉头排废管道、14：高温炉本体、15：第二水冷系统、16：炉尾气封。
具体实施方式
下面将结合本公开实施例中的附图，对公开实施例中的技术方案进行清楚、完整 地描述，显然，所描述的实施例是本公开一部分实施例，而不是全部的实施例。基于本公开中的实施例，本领域技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本公开保护的范围。需要说明的是，在不冲突的情况下，本公开中的实施例及实施例中的特征可以相互任意组合。
本公开示例性的实施例中提供一种低缺陷聚丙烯腈基碳纤维制备方法，包括如下的步骤：
步骤S110：准备碳纤维原丝，碳纤维原丝的单丝强度≥7.0cN/dtex，碳纤维原丝的纤度为0.50dtex～0.70dtex。
碳纤维原丝可以卷料的形式提供，将碳纤维原丝的卷料置于放卷机构上，以便于通过放卷机构连续提供碳纤维原丝。
步骤S120：牵引碳纤维原丝，依次经过多台独立控温的预氧化炉，多台预氧化炉对碳纤维原丝的总牵伸率为-12％～+5％，将碳纤维原丝预氧化形成预氧丝丝束，预氧丝丝束的密度范围在1.340g/cm 3～1.360g/cm 3之间。
牵引碳纤维原丝依次经过多台独立控温的预氧化炉进行预氧化处理，预氧化炉的数量大于二，预氧化炉的数量根据生产需求设置，比如，可以牵引碳纤维原丝依次经过二台预氧化炉、三台预氧化炉、四台预氧化炉等。
每台预氧化炉独立加热对碳纤维原丝进行预氧化。本实施例中，每台预氧化炉的预氧化温度为200℃～300℃，每台预氧化炉的加热区域的控温精度在±2℃以内。以使碳纤维原丝经过多台预氧化炉被均匀预氧化形成预氧丝丝束。
每台预氧化炉独立驱动，因此，多台预氧化炉对碳纤维原丝的牵伸率可能不同，本实施例中，通过调整每台预氧化炉驱动牵引碳纤维原丝的速率调整对碳纤维原丝的牵伸率，以使多台预氧化炉对碳纤维原丝的总牵伸率为-12％～+5％，示例性的，多台预氧化炉对碳纤维原丝的总牵伸率可以为-12％、-10％、-8％、-6％、-4％、-2％、0、1％、3％或5％等。
碳纤维原丝被预氧化形成预氧丝丝束，预氧丝丝束的密度范围在1.340g/cm 3～1.360g/cm 3之间，比如，预氧丝丝束的密度可以为1.340g/cm 3、1.345g/cm 3、1.350g/cm 3、1.355g/cm 3或1.360g/cm 3。
步骤S130：牵引预氧丝丝束，经过设有两级气封室结构的低温碳化炉进行低温碳化处理，形成低碳丝丝束，低温碳化炉的炉头和炉尾均设有两级气封室，两级气封室的一级气封室与二级气封室的压力差在1Pa～10Pa之间，低温碳化炉对丝束的牵伸率为+1％～+5％。
自低温碳化炉的炉头向炉尾的方向，牵引预氧丝丝束进入低温碳化炉进行低温碳化处理，位于炉头的二级气封室包括加热装置，加热装置的加热温度为150℃～400℃，位于炉头的二级气封室的最高温度为400℃。加热装置用于加热预氧丝丝束，有利于提高预氧丝丝束的低温碳化效率。
自低温碳化炉的炉头向炉尾的方向，低温碳化炉包括依次设置的6～8个第一加热温区，每个第一加热温区的碳化温度为300℃～1000℃，每个第一加热温区的升温速率为40℃/min～100℃/min。其中，低温碳化炉的第一加热温区的碳化温度大致相同，以使预氧丝丝束在低温碳化炉中均匀的低温碳化，形成低碳丝丝束。示例性的，每个第一加热温区的碳化温度可以为300℃、400℃、500℃、600℃、700℃、800℃、900℃或1000℃。
低温碳化炉的炉尾设有第一水冷系统，以控制从低温碳化炉牵引出的低碳丝丝束的温度不超过150℃。
低温碳化炉的碳化温度较高，因此，预氧丝丝束低温碳化形成的低碳丝丝束的温度也较高，低碳丝丝束需经过低温碳化炉的炉尾进入到后续的高温碳化炉中，低碳丝丝束 经过第一水冷系统冷却后温度下降至低于150℃。
本实施例中，控制低温碳化炉驱动牵引预氧丝丝束的速度控制牵伸率，低温碳化炉对丝束的牵伸率为+1％～+5％，比如，低温碳化炉对丝束的牵伸率可以为+1％、+2％、+3％、+4％或+5％。
步骤S140：牵引低碳丝丝束，经过设有丝束除湿装置的高温碳化炉进行高温碳化处理，形成高碳丝丝束，高温碳化炉对丝束的牵伸率为-2％～-8％。
本实施例中，高温碳化炉包括丝束除湿装置，丝束除湿装置设置在高温碳化炉的炉口所在的一侧，沿着丝束行进的方向，丝束除湿装置设置在高温碳化炉的炉口的前端，丝束除湿装置与高温碳化炉的炉口之间具有5mm～50mm的间隙。
丝束除湿装置的高度为5mm～30mm，示例性的，丝束除湿装置可以为高度为5mm～30mm的筒形结构，筒形结构的一开口朝向低温碳化炉，筒形结构的另一开口朝向高温碳化炉的炉口，低碳丝丝束从筒形结构的一开口进入，从筒形结构的另一开口穿出进入到高温碳化炉中。
沿筒形结构的径向方向，丝束除湿装置自中间向两端吹扫热风，热风温度为110℃～150℃，热风风速不超过5m/s。热风吹扫去除低碳丝丝束表面的水分，低碳丝丝束表面的水分从丝束除湿装置与高温碳化炉的炉口之间的逸出，保证进入高温碳化炉的低碳丝丝束干燥，没有残留的水分。最大程度避免水汽进入到高温碳化炉中损伤丝束，从而更大程度上减少或避免聚丙烯腈基碳纤维在高温碳化过程中因纤维与表面微量水在高温条件下发生反应而产生的表面微孔隙甚至微孔洞等缺陷。
可以理解的是，筒形结构并不构成对丝束除湿装置的限制，丝束除湿装置可以是能够实现去除低碳丝丝束的表面水分的功能的结构，丝束除湿装置可以根据需要被设置为任何形状和任何结构。
本实施例中，沿着丝束的行进方向，高温碳化炉包括依次设置的4～8个第二加热温区，第二加热温区的数量可以根据生产需求设置为4个、5个、6个或8个。每个第二加热温区的碳化温度为1000℃～1600℃，比如，可以为1000℃、1200℃、1500℃、1600℃，每个第二加热温区的升温速率为100℃/min～150℃/min。
低碳丝丝束进入高温碳化炉后依次经过每个第二加热温区，低碳丝丝束在高温碳化炉中均匀的高温碳化，形成高碳丝丝束。
步骤S150：牵引高碳丝丝束，经过一至两级的表面处理槽进行表面处理，清洗表面处理后的高碳丝丝束后干燥高碳丝丝束。
高碳丝丝束从高温碳化炉穿出后，采用电解质对高碳丝丝束进行表面处理，以减少高碳丝丝束表面的缺陷，以便于后续对高碳丝丝束上浆。其中，电解质为铵盐类电解质。示例性的，电解质包括碳酸氢铵、磷酸二氢铵和硫酸铵中的至少一种。
表面处理的电量根据应用需求设定，比如，可以设定为1c/g～50c/g。
然后，用去离子水清洗高碳丝丝束以去除残留的电解质。接着，干燥高碳丝丝束，本实施例中，可以采用烘干的方式干燥高碳丝丝束，但不构成对本方案的限制。
步骤S160：牵引高碳丝丝束进入上浆槽上浆，将上浆后的高碳丝丝束在150℃温度条件下干燥。
上浆槽中容置有上浆槽中，高碳丝丝束进入上浆槽后浸润在上浆槽中，上浆剂附着在干燥的高碳丝丝束的表面上，通过上浆剂对高碳丝丝束上浆。
其中，上浆剂可以环氧树脂类上浆剂，上浆剂中包括环氧树脂；上浆剂的浓度为0.5％～1.5％，比如，上浆剂中环氧树脂的浓度为0.5％、0.8％、1.2％、1.5％。
将上浆后的高碳丝丝束置于150℃温度条件下干燥，获得低缺陷聚丙烯腈基碳纤维，本实施例制备的低缺陷聚丙烯腈基碳纤维的表面的孔隙或孔洞等缺陷少，同时提高了纤维强度。
在一些实施例中，本实施例是对上述实施例的说明，本实施例和上述实施例的区别之处在于，低温碳化炉的每个两级气封室的一级气封室通过风机连接至低温炉废气处理系统，以将一级气封室与二级气封室之间的压力差维持在1Pa～10Pa。从而通过一级气封室与二级气封室之前的压力差，将预氧丝丝束在低温碳化炉中低温碳化产生的热解气体通过风机排出至低温炉废气处理系统，提高了低温碳化炉的排废能力，避免热解气体对预氧丝丝束产生不利影响，如此，能够提高形成的低缺陷聚丙烯腈基碳纤维的品质，进一步降低碳纤维缺陷。
下面结合实施例，对本申请进一步说明。
本实施例的低缺陷聚丙烯腈基碳纤维制备方法，碳纤维原丝经过退绕后，依次经过预氧化炉、低温碳化炉、高温碳化炉、表面处理、水洗、上浆、烘干和卷绕碳化工序得到低缺陷聚丙烯腈基碳纤维。
如图1示出了本实施例的制备方法所用的低温碳化炉的结构，如图1所示，低温碳化炉包括依次设置的第一气封室1、第二气封室2、低温炉本体6、第三气封室7、第四气封室9。第一气封室1和第二气封室2在低温碳化炉的炉头构成两级气封室，第三气封室7和第四气封室9在低温碳化炉的炉尾构成两级气封室。第二气封室2设有氮气气封4、加热装置5；低温碳化炉6还具有排废管道10，排废管道10上连有风机3；第三气封室7设有第一水冷系统8。第一气封室1与第四气封室9(炉尾)均设有与风机3相连的通道。
如图2示出了本实施例的制备方法所用的设有丝束除湿装置的高温碳化炉的结构，如图2所示，依次设置的丝束除湿装置11、高温炉炉头气封12、高温炉本体14、高温炉炉尾气封16。其中，丝束除湿装置11上设置热风管道11-1，高温炉炉头气封12处设有高温炉炉头排废管道13，高温碳化炉的炉尾处设有第二水冷系统15。
本实施例的低缺陷聚丙烯腈基碳纤维制备方法，采用以下实施方式：
首先，提供碳纤维原丝，碳纤维原丝由干喷湿纺工艺制备，碳纤维原丝的单丝强度≥7.0cN/dtex，碳纤维原丝的纤度为0.50dtex～0.70dtex。
碳纤维原丝经过退绕后，依次经过三台独立控温的预氧化炉，每台预氧化炉的预氧化温度分别为200℃～300℃之间的温度，单个预氧化炉有效加热区域的控温精度在±2℃以内。通过每台氧化炉间独立的驱动对炉内的丝束给以不同程度的牵伸，三台预氧化炉的总牵伸率为-12％～+5％。本实施例形成的预氧丝丝束的密度范围在1.340g/cm3～1.360g/cm3之间。
然后，牵引预氧丝丝束进入配有一种高效排焦系统的低温碳化炉，预氧丝丝束从低温碳化炉的炉头向炉尾的方向从低温碳化炉中穿过。低温碳化炉的炉头设置有第一气封室1和第二气封室2，第一气封室1与第二气封室2的压力差在1Pa～10Pa之间，炉头的第二气封室2内的最高加热温度为400℃，低温碳化炉的炉尾设置有第三气封室7和第四气封室9，第三气封室7配有第一水冷装置8，用于控制从低温碳化炉穿出的丝束的温度不超过150℃。
低温碳化炉共分为6～8个加热温区，碳化温度300℃～1000℃，升温速率约40℃/min～100℃/min；通过低温碳化炉前后驱动速比来控制低温碳化牵伸率，牵伸率为+1％～+5％，预氧丝丝束在低温碳化炉中被低温碳化形成低碳丝丝束。从低温碳化炉穿出的低碳丝丝束的温度低于150℃，比如，从低温碳化炉穿出的低碳丝丝束的温度可以为145℃、140℃或者更低。
接着，牵引低碳丝丝束经过丝束除湿装置后再进入高温碳化炉。
丝束除湿装置11与高温碳化炉的炉口留有5mm～50mm的间隙，以便于低碳丝丝束上的湿气从间隙逸出而不被带入高温碳化炉，丝束除湿装置11内腔的高度约为5mm～30mm，丝束除湿装置11的加热方式为中间往两端热风吹扫，热风温度110～ 150℃之间，丝束除湿装置11可利用低温碳化炉的第一水冷装置8和低碳丝丝束热交换的热量进行空气加热，热风风速不超过5m/s；高温碳化的炉头配有氮气气封及排废管道，炉尾配有第二水冷系统，第二水冷系统用于降低从高温碳化炉穿出的丝束的温度，本实施例中，从高温碳化炉穿出的丝束的温度不超过150℃。高温碳化炉共分为4～8个加热温区，碳化温度为1000℃～1600℃，升温速率约为100℃/min～150℃/min。低碳丝丝束经过高温碳化炉，被高温碳化形成高碳丝丝束。本实施例中，通过控制高温碳化炉前后驱动速比来控制高温碳化的牵伸率，牵伸率为-8％～-2％。
接着，牵引高碳丝丝束经过一至两级的表面处理槽，表面处理槽中容置有电解质，通过电解质对高碳丝丝束进行表面处理。电解质可以包括碳酸氢铵、磷酸二氢铵和硫酸铵等铵盐类电解质，表面处理电量根据应用需求设定，优选1～50c/g；并对经过表面处理后的高碳丝丝束进行水洗后干燥。
接着，牵引高碳丝丝束继续经过上浆槽进行上浆，上浆槽中容置有上浆剂，上浆剂可以为环氧树脂类上浆剂，上浆剂中包括环氧树脂，上浆剂的浓度为0.5％～1.5％，例如，上浆剂的浓度可以为0.5％、0.8％、1.2％、1.5％。
接着，将上浆后的高碳丝丝束在150℃左右的干燥炉中进行干燥后，即可获得低缺陷聚丙烯腈基碳纤维。
表1示出了实施例1-5的低缺陷聚丙烯腈基碳纤维制备方法中制备过程的具体参数。需要指出的是，本申请的低缺陷聚丙烯腈基碳纤维制备方法中的具体参数并不局限于表1中数据。
表1低缺陷聚丙烯腈基碳纤维制备方法的具体实施例
  实施例1 实施例2 实施例3 实施例4 实施例5 实施例6
预氧牵伸 0.95 0.95 0.95 0.92 0.92 0.94
预氧温度/℃ 274 274 274 276 276 276
低碳牵伸 1.02 1.02 1.02 1.02 1.02 1.01
低碳温度/℃ 700 700 700 720 720 720
一室压力Pa -2 -4 -5 -5 -4 -3
二室压力Pa -1 -1 -2 -2 -1 -1
高碳牵伸 0.96 0.96 0.96 0.97 0.97 0.95
高碳温度/℃ 1450 1450 1450 1400 1400 1400
高碳除湿温度/℃ 110 110 120 120 150 150
高温炉头露点ppm -5.6 -5.6 -6.8 -6.8 -8.3 -8.1
作为参照，表2示出了对比例1、对比例2和对比例3中制备碳纤维的具体参数。
表2制备碳纤维制备方法的对比例
  对比例1 对比例2 对比例3
预氧牵伸 0.95 0.88 0.95
预氧温度/℃ 274 274 274
低碳牵伸 1.02 1.02 1.02
低碳温度/℃ 700 700 700
一室压力Pa 无 无 -2
二室压力Pa +1 -1 -1
高碳牵伸 0.95 0.97 0.95
高碳温度/℃ 1450 1450 1450
高碳除湿温度/℃ / / /
高温炉头露点ppm 8.3 8.3 8.3
选用小角X射线衍射法对实施例1-5制备获得的低缺陷聚丙烯腈基碳纤维以及对比例1-3的碳纤维上的孔隙或孔洞等尺寸及分布进行检测，检测结果如表3所示。
表3实施例1-5制备获得的碳纤维以及对比例1-3制备获得的碳纤维的检测结果
Figure PCTCN2022134204-appb-000001
根据表1、表2、表3可以看出，本申请的低缺陷聚丙烯腈基碳纤维制备方法制备得到的碳纤维的微孔体积更小、结构缺陷少，同时提升了碳纤维的强度。
本实施例的低缺陷聚丙烯腈基碳纤维制备方法通过第一气封室与第二气封室的压力差促进低温碳化炉中热解气体排出，避免热解气体对预氧丝丝束产生不利影响，能够提高形成的低缺陷聚丙烯腈基碳纤维的品质，降低纤维缺陷；同时，通过丝束除湿装置对进入高温碳化炉的丝束高温除湿，避免高温碳化过程中水汽损伤丝束，减少了高温碳化过程中的缺陷；同时，本实施例还通过调节预氧化、低温碳化和高温碳化三个阶段的牵伸率，进一步减缓碳化过程产生的纤维缺陷的扩大。
本说明书中各实施例或实施方式采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分相互参见即可。
在本说明书的描述中，参考术语“实施例”、“示例性的实施例”、“一些实施方式”、“示意性实施方式”、“示例”等的描述意指结合实施方式或示例描述的具体特征、结构、材料或者特点包含于本公开的至少一个实施方式或示例中。
在本说明书中，对上述术语的示意性表述不一定指的是相同的实施方式或示例。而且，描述的具体特征、结构、材料或者特点可以在任何的一个或多个实施方式或示例中以合适的方式结合。
在本公开的描述中，需要说明的是，术语“中心”、“上”、“下”、“左”、“右”、“竖直”、“水平”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本公开和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本公开的限制。
可以理解的是，本公开所使用的术语“第一”、“第二”等可在本公开中用于描述各种结构，但这些结构不受这些术语的限制。这些术语仅用于将第一个结构与另一个结构区分。
在一个或多个附图中，相同的元件采用类似的附图标记来表示。为了清楚起见，附图中的多个部分没有按比例绘制。此外，可能未示出某些公知的部分。为了简明起 见，可以在一幅图中描述经过数个步骤后获得的结构。在下文中描述了本公开的许多特定的细节，例如器件的结构、材料、尺寸、处理工艺和技术，以便更清楚地理解本公开。但正如本领域技术人员能够理解的那样，可以不按照这些特定的细节来实现本公开。
最后应说明的是：以上各实施例仅用以说明本公开的技术方案，而非对其限制；尽管参照前述各实施例对本公开进行了详细的说明，本领域技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本公开各实施例技术方案的范围。
工业实用性
本申请本实施例提供的一种低缺陷聚丙烯腈基碳纤维制备方法中，通过第一气封室与第二气封室的压力差促进低温碳化炉中热解气体排出，避免热解气体对预氧丝丝束产生不利影响，能够提高形成的低缺陷聚丙烯腈基碳纤维的品质，降低纤维缺陷；同时，通过丝束除湿装置对进入高温碳化炉的丝束高温除湿，避免高温碳化过程中水汽损伤丝束，减少高温碳化过程产生的缺陷；同时，本实施例还通过调节预氧化、低温碳化和高温碳化三个阶段的牵伸率，进一步减缓碳化过程产生的纤维缺陷的扩大。

Claims (13)

  1. 一种低缺陷聚丙烯腈基碳纤维制备方法，所述方法包括：
    准备碳纤维原丝，所述碳纤维原丝的单丝强度≥7.0cN/dtex，所述碳纤维原丝的纤度为0.50dtex～0.70dtex；
    牵引所述碳纤维原丝，依次经过多台独立控温的预氧化炉，多台所述预氧化炉对所述碳纤维原丝的总牵伸率为-12～+5％，将所述碳纤维原丝预氧化形成预氧丝丝束，所述预氧丝体丝束的密度范围在1.340g/cm 3～1.360g/cm 3之间；
    牵引所述预氧丝丝束，经过设有两级气封室结构的低温碳化炉进行低温碳化处理，形成低碳丝丝束，所述低温碳化炉的炉头和炉尾均设有两级气封室，所述两级气封室的一级气封室与二级气封室的压力差在1Pa～10Pa之间，所述低温碳化炉对丝束的牵伸率为+1％～+5％；
    牵引所述低碳丝丝束，经过设有丝束除湿装置的高温碳化炉进行高温碳化处理，形成高碳丝丝束，所述高温碳化炉对丝束的牵伸率为-8％～-2％；
    牵引所述高碳丝丝束，经过一至两级的表面处理槽进行表面处理，清洗表面处理后的所述高碳丝丝束后干燥所述高碳丝丝束；
    牵引所述高碳丝丝束进入上浆槽上浆，将上浆后的所述高碳丝丝束在150℃温度条件下干燥。
  2. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，每台所述预氧化炉的预氧化温度为200℃～300℃，每台所述预氧化炉的加热区域的控温精度在±2℃以内。
  3. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述低温碳化炉每个所述两级气封室的所述一级气封室通过风机连接至低温炉废气处理系统，以将所述一级气封室与所述二级气封室之间的压力差维持在1Pa～10Pa。
  4. 根据权利要求3所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，位于所述低温碳化炉的炉头的所述二级气封室包括加热装置，所述加热装置的加热温度为150℃～400℃。
  5. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述低温碳化炉包括6～8个第一加热温区，每个所述第一加热温区的碳化温度300℃～1000℃，每个所述第一加热温区的升温速率约40℃/min～100℃/min。
  6. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述低温碳化炉的炉尾设有第一水冷系统，以控制从所述低温碳化炉牵引出的所述低碳丝丝束的温度不超过150℃。
  7. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述丝束除湿装置设置在所述高温碳化炉的炉口处，所述丝束除湿装置和所述高温碳化炉的炉口之间具有5mm～50mm的间隙。
  8. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述丝束除湿装置自所述高温碳化炉的中间向所述高温碳化炉的两端吹扫热风，热风温度为110℃～150℃之间，热风风速不超过5m/s。
  9. 根据权利要求1或5所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述的高温碳化炉包括4～8个第二加热温区，每个所述第二加热温区的碳化温度1000℃～1600℃，每个所述第二加热温区的升温速率为100℃/min～150℃/min。
  10. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，采用电解质对所述高碳丝丝束进行表面处理，所述电解质为铵盐类电解质。
  11. 根据权利要求10所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述电解质包括碳酸氢铵、磷酸二氢铵和硫酸铵中的至少一种。
  12. 根据权利要求1所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述上浆槽中容置上浆剂，通过所述上浆剂浸润所述高碳丝丝束对所述高碳丝丝束上浆。
  13. 根据权利要求12所述的低缺陷聚丙烯腈基碳纤维制备方法，其中，所述上浆剂包括环氧树脂，所述上浆剂的浓度为0.5％～1.5％。
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CN114892313B (zh) * 2022-06-14 2023-06-27 山西钢科碳材料有限公司 一种将聚丙烯腈纤维制成碳纤维过程中的上架操作方法
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