CN112176458B - Preparation method of asphalt-based carbon fiber - Google Patents
Preparation method of asphalt-based carbon fiber Download PDFInfo
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- CN112176458B CN112176458B CN202011015179.XA CN202011015179A CN112176458B CN 112176458 B CN112176458 B CN 112176458B CN 202011015179 A CN202011015179 A CN 202011015179A CN 112176458 B CN112176458 B CN 112176458B
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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
- D01F9/145—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from pitch or distillation residues
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/12—Stretch-spinning methods
- D01D5/14—Stretch-spinning methods with flowing liquid or gaseous stretching media, e.g. solution-blowing
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/12—Stretch-spinning methods
- D01D5/16—Stretch-spinning methods using rollers, or like mechanical devices, e.g. snubbing pins
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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
- D01F9/32—Apparatus therefor
- D01F9/322—Apparatus therefor for manufacturing filaments from pitch
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Abstract
The invention belongs to the field of carbon fiber production and preparation, and particularly relates to a preparation method of high-quality asphalt-based carbon fiber. The preparation method of the pitch-based carbon fiber comprises the following steps: step 1, drafting spinning; step 2, pre-oxidation; and 3, carbonizing. The preparation method provided by the invention utilizes the on-line viscometer to control the viscosity of the spinning resin, thereby keeping the spinning resin in the optimal spinning state; micro air flow guiding is additionally added in the drawing spinning, and then the problems that the diameter of the original yarn is too thick and the fiber yarn is easy to break and difficult to lead out in the spinning are solved by a non-winding roller drawing method; in the pre-oxidation treatment process, the energy conversion rate is improved by adopting an infrared heating mode and a hot air circulating heating mode, the production cost is effectively reduced, and the temperature control is more accurate by adopting a thermal resistor and infrared temperature measurement; the auxiliary oxidant is added into the pre-oxidation furnace, so that the pre-oxidation time is shortened, the pre-oxidation effect is improved, and various problems of fiber skin-core structure, overoxidation, insufficient oxidation and the like which are frequently generated in the pre-oxidation process are solved.
Description
Technical Field
The invention belongs to the field of carbon fiber production and preparation, and particularly relates to a preparation method of high-quality asphalt-based carbon fiber through melt spinning, pre-oxidation and carbonization.
Background
The pitch-based carbon fiber is a high-strength and high-modulus fibrous high polymer material with carbon content of more than 90%, and other elements except carbon are almost completely removed, so that only flaky graphite microcrystals are left to be stacked along the axial direction of the fiber. Therefore, the carbon fiber has the strong tensile resistance of the carbon material, and the soft processability of the fiber material has the characteristics of low density, high strength, high temperature resistance, high modulus, corrosion resistance, low resistance, high heat conduction, low thermal expansion, radiation resistance, good chemical stability and the like. Particularly, mesophase pitch-based carbon fibers have a series of excellent properties such as high modulus, high strength, low density, good heat conductivity, good heat resistance, corrosion resistance, creep resistance, electromagnetic shielding and the like, and particularly, the outstanding high-strength high-modulus, high-conductivity and heat conductivity makes up the defects of other fibers in some high-end fields, so that the mesophase pitch-based carbon fibers have wide application prospects in the fields of aerospace, industrial robots, wind power generation, high-end buildings, light-weight materials of tracks and vehicles, integrated circuit substrates, high-energy-density electronic instrument radiating fins, high-pressure storage tanks, industrial roll shafts and the like, the technology for producing carbon fibers by using pitch developed in Japan as yet since 1964, many countries successively enter the research and development field of pitch-based carbon fibers, and a few enterprises master the pitch-based carbon fiber production technology, products have high performance, but the yield of the pitch-based carbon fibers is inferior to that of PAN-based carbon fibers in the field of global carbon fibers, the extremely high modulus and thermal conductivity of the pitch-based carbon fiber are not comparable to those of other fibers. In addition, the general pitch-based carbon fiber is applied to the carbon fiber in the solar photoelectric field, particularly as the carbon fiber is applied to a high-temperature growth furnace of polycrystalline silicon and monocrystalline silicon in a solar panel, and particularly the pitch-based carbon fiber heat-insulating material has excellent heat-insulating property and non-substitutability in the use of the high-temperature furnace. The pitch-based carbon fiber has the advantages of excellent performance and high cost.
However, the traditional mesophase pitch-based carbon fiber process is complex, and the mesophase pitch-based carbon fiber can be further produced by pre-oxidation or pre-carbonization, so that the energy consumption and the production cost are high.
Disclosure of Invention
The invention aims to provide a preparation method of pitch-based carbon fiber, which has simple process, low energy consumption and low production cost. The pitch-based carbon fiber provided by the invention is a carbon fiber obtained by taking a substance rich in polycyclic aromatic hydrocarbons in high-temperature pitch as a raw material and carrying out polymerization, spinning, pre-oxidation and carbonization treatment. The preparation method utilizes the preparation method of the pitch-based carbon fiber high-quality filament and staple by drafting spinning, pre-oxidation and carbonization. The equipment and the process are improved and optimized according to the characteristics of isotropic and anisotropic spinnable asphalt resin, and the viscosity of the spinning resin is controlled by using an on-line viscometer so as to keep the spinning state at the best; micro air flow guiding is additionally added in the drawing spinning, and then the problems that the diameter of a raw filament is too thick and a fiber filament is easy to break and is difficult to lead out in the spinning are solved through a non-winding roller drawing method; in the pre-oxidation treatment process, an infrared heating mode and a hot air circulating heating mode are adopted, so that the energy conversion rate is improved, the production cost is effectively reduced, and the temperature control is more accurate by adopting a thermal resistor and infrared temperature measurement; an auxiliary oxidant is added into the pre-oxidation furnace, so that the pre-oxidation time is shortened, the pre-oxidation effect is improved, and the problems of fiber skin-core structure, overoxidation, insufficient oxidation and the like which are frequently generated in the pre-oxidation process are solved; the semi-mesh belt conveying semi-conductor roller conveying is adopted in the pre-oxidation process, so that fiber damage caused by the fact that the fibers do not reach the strength and the roller is arranged is prevented; the temperature control in the carbonization adopts a thermocouple temperature measurement carbonization mode, and a low-temperature section new electromagnetic induction heating mode and a high-temperature section resistance heating mode are adopted, so that the heating efficiency of the carbonization furnace is improved, the cost is saved, and the performance of the carbon fiber is also improved.
In order to achieve the above purpose, the invention adopts the following technical scheme.
A preparation method of pitch-based carbon fiber filaments comprises the following specific steps.
Step 1, drawing spinning: the method comprises the steps of selecting spinnable asphalt resin to be melted and mixed through a strong stirring type melt machine, enabling the melted material to enter a gear pump through a pipeline and be pumped into a spinning cavity, extruding spinning through a spinning plate, controlling the viscosity and the temperature of the spinning through an online viscosity meter of the spinning resin, then carrying out stretch spinning through a non-winding type stretching roller barrel, adding micro airflow guide in the stretch spinning, and stretching through a non-winding type stretching roller barrel by a stretching roller.
The spinnable pitch resin is isotropic spinnable pitch resin or anisotropic spinnable pitch resin (mesophase pitch).
The indexes of spinnable asphalt resin are that the coking value is more than 75%, and the content of the interphase of the anisotropic asphalt resin is more than 60%.
The melting temperature is 15-35 ℃ higher than the softening point, and the stirring speed is 80-350 r/min.
The spinning viscosity is controlled to be 6-35 pa · s, the spinning temperature is controlled to be 20-50 ℃ higher than the softening point, and the spinning pressure is 2.5-4.5 mpa.
The rotation speed of the drawing roller is 580-780 r/min.
The air flow speed is 30-50 m/s.
The rotating speed of the drafting roller is 580-780 r/min, and the negative pressure suction pressure of the drafting roller is-2 to-45 kPa and the positive pressure doffing pressure of the drafting roller is 4-80 kPa.
Step 2, pre-oxidation: the fiber is conveyed by an arrangement accumulation type mesh belt in 40-60% of the time in a pre-oxidation furnace conveying mode, and is conveyed by a guide roller in 60-40% of the time; adding a trace amount of atomized oxidation auxiliary agent into the furnace chamber; the heating adopts an infrared heating air circulation mode; temperature control adopts thermal resistance and infrared temperature measurement; the pre-oxidation treatment temperature is set according to the softening point of the protofilament spinnable asphalt; in order to improve the physical performance of the fiber and enable the arrangement of molecular structures in the fiber to be more orderly, proper tension is added to the fiber at a conveying guide roller.
The flow rate of the atomization oxidation auxiliary agent is 100-800 ml/min.
The pre-oxidation treatment temperature is set to be 100-220 ℃ lower than the softening point of the spinnable asphalt resin at the initial temperature and 8-140 ℃ higher than the softening point of the spinnable asphalt.
The tension is 3-40mpa/mm 2 。
The pre-oxidation time is 1.5-8 h.
Step 3, carbonization: in the carbonization treatment mode, a muffle furnace is conveyed by adopting an inert gas protection continuous guide rail, the carbonization furnace is heated by adopting a new electromagnetic induction heating mode and an original resistance heating mode, the resistivity change is monitored by an online resistance measuring instrument, and the temperature of the carbonization furnace is controlled by resistivity data; adding protective gas nitrogen in the high-temperature carbonization; the appropriate tension is added to the fiber at the delivery guide rolls.
The initial temperature of the carbonization furnace is more than 800 ℃, and the resistivity is controlled to be 1.5-30 x 10 -3 Ωcm。
The nitrogen amount is 100-260 m 3 H, purity 99.99%.
The fiber drafting tension is 80-400mpa/mm 2 。
The carbonization time is 8-30 min.
Compared with the prior art, the invention has the following technical effects.
The preparation method of the pitch-based carbon fiber provided by the invention has the advantages that the production continuity and stability are improved by drawing spinning, the precursor is very fragile and easy to damage due to the characteristic that spinnable pitch resin is in a glassy state when being cured in spinning, the damage to the precursor caused in secondary yarn guiding of a winding roller is avoided by drawing spinning in the spinning by adopting the drawing spinning of the invention, the spinning is controlled by measuring the viscosity of the spinning resin, and the problem that the uniformity of the yarn diameter is influenced due to the unstable viscosity is effectively controlled. The addition of the auxiliary hot air flow effectively improves the extensible length in the temperature-sensitive high-spinning resin spinning, improves the spinning efficiency and effect, and also effectively improves the effective wire drawing length of the high-viscosity mesophase pitch, and the hot air flow guides the wire drawing, particularly the automatic wire drawing of stopping production and then starting, and effectively improves the automation degree. The various modes have the advantages that the yarn diameter of the spun filament is very uniform due to uniform drafting stress of each yarn, the standard deviation of the yarn diameter is only 0.4um which is 1/6 of other spinning yarns, and the comprehensive performance of the carbon fiber is also greatly improved. In the spinning process, under the action of the drafting force, the molecules of the asphalt are oriented and arranged along the axial direction of the fiber, so that the performance of the carbon fiber is obviously improved.
The pre-oxidation method in the preparation method of the pitch-based carbon fiber solves the problems that the pitch protofilament is easy to damage and easily generates a sheath-core structure in the pre-oxidation process, the peroxidation and oxidation are insufficient, the treatment time is too long and the like, effectively improves the fiber quality and reduces the energy consumption.
According to the preparation method of the asphalt-based carbon fiber, the muffle furnace is conveyed by the inert gas protection continuous guide rail in the carbonization treatment mode, the new electromagnetic induction heating mode and the original resistance heating mode are adopted for heating the carbonization furnace, the advantages of the new electromagnetic induction heating mode are mainly reflected in the aspects of energy consumption and heating speed, the new electromagnetic induction heating efficiency is improved by 20-50%, the conversion can reach more than 70-90%, the energy is saved by 30-40%, and the efficiency and the production cost can be effectively improved in large-scale production.
Drawings
FIG. 1 is a flow chart of the pitch-based carbon fiber preparation method of the present invention, wherein G-01 is a dissolver, G-02 is a gear pump, M-01 is a viscometer, J-01 is a spinning chamber, M-02 is a drafting roller, M-03 is a conveying mesh belt, B-01 is a pre-oxidation furnace, B-02 is a carbonization furnace, M-04 is a conveying guide roller, M-05 is a conveying guide roller, and M-06 is a resistance measuring instrument.
Detailed Description
The technical solutions of the present invention will be described below with reference to specific embodiments, and the described embodiments are only a part of embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The flow chart of the pitch-based carbon fiber preparation method of the present invention is shown in fig. 1. A preparation method of pitch-based carbon fiber filaments comprises the following specific steps.
Step 1, drawing spinning: the method comprises the steps of selecting spinnable asphalt resin to be melted and mixed through a strong stirring type material melting machine (G-01), enabling the melted material to enter a gear pump (G-02) through a pipeline to be injected into a spinning cavity (J-01), extruding spinning through a spinning plate, controlling the viscosity and temperature of the spinning through a spinning resin on-line viscosity meter (M-01), then performing stretch spinning through a non-winding type stretching roller barrel (M-02), additionally adding micro airflow for guiding in the stretch spinning, and stretching through the non-winding type stretching roller barrel by a stretching roller.
The spinnable pitch resin is isotropic spinnable pitch resin or anisotropic spinnable pitch resin (mesophase pitch).
The indexes of spinnable asphalt resin are that the coking value is more than 75%, and the content of the interphase of the anisotropic asphalt resin is more than 60%.
The melting temperature is 15-35 ℃ higher than the softening point, and the stirring speed is 80-350 r/min.
The spinning viscosity is controlled to be 10-20 pa.s, the spinning temperature is controlled to be 20-50 ℃ higher than the softening point, and the spinning pressure is 2.5-4.5 mpa.
The rotation speed of the drawing roller is 580-780 r/min.
The air flow speed is 30-50 m/s.
The rotating speed of the drafting roller is 580-780 r/min, and the negative pressure suction pressure of the drafting roller is-2 to-45 kPa and the positive pressure doffing pressure of the drafting roller is 4-80 kPa.
Step 2, pre-oxidation: the fiber is conveyed by an arrangement accumulation type mesh belt (M-03) in 40-60% of the time in a conveying mode of a pre-oxidation furnace, and is conveyed by a guide roller in 60-40% of the time; adding a trace amount of atomized oxidation auxiliary agent into the furnace chamber; the heating adopts an infrared heating air circulation mode; the temperature control is more accurate by adopting thermal resistance and infrared temperature measurement; the pre-oxidation treatment temperature is set according to the softening point of the protofilament spinnable asphalt; the molecular structure in the fiber is arranged more orderly by improving the physical property of the fiber, and proper tension is added to the fiber at a conveying guide roller (M-04).
The flow rate of the atomization oxidation auxiliary agent is 100-800 ml/min.
The pre-oxidation treatment temperature is set to be 100-220 ℃ lower than the spinning temperature at the initial temperature, and 8-140 ℃ higher than the spinning temperature at the final temperature.
The tension is 3-40mpa/mm 2 。
The pre-oxidation time is 1.5-8 h.
Step 3, carbonization: in the carbonization treatment mode, a muffle furnace is conveyed by adopting an inert gas protection continuous guide rail, the carbonization furnace adopts two modes of new electromagnetic induction heating and original resistance heating, the change of the resistivity is monitored by an online measuring resistance instrument (M-06), and the temperature of the carbonization furnace is controlled by resistivity data; adding protective gas nitrogen in the high-temperature carbonization; the appropriate tension is added to the fibers at the transport guide rolls (M-05).
The initial temperature of the carbonization furnace is more than 800 ℃, and the resistivity is controlled to be 1.5-30 x 10 -3 Ωcm。
The nitrogen amount is 100-260 m 3 H, purity 99.99%.
The fiber drafting tension is 80-400mpa/mm 2 。
The carbonization time is 8-30 min.
Example 1 pitch-based carbon fiber preparation method process study experiment.
A preparation method of pitch-based carbon fiber filaments comprises the following specific steps.
Step 1, drawing and spinning.
In order to prevent secondary damage of fibers in the pre-oxidation yarn guiding process, drawing is changed into a positive and negative pressure roller winding-free drawing method, the rotating speed of a drawing roller is 680-720 r/min, and the negative pressure suction pressure of the drawing roller is-36-40 kPa and the positive pressure yarn removal pressure is 48-75 kPa; in order to improve the uniformity of the materials, a non-stirring material melting machine is changed into a strong-stirring material melting machine, and the temperature of the melting material is controlled to be higher than 20-26 ℃ by taking the softening point as the reference; adding an online spinning viscosity detector in spinning control, controlling the spinning viscosity to be 13 +/-2 pa.s through temperature control, and controlling the spinning temperature to be higher than 28-34 ℃ by taking the softening point as the reference; auxiliary hot air is added for improving the drawable length of spinning wire drawing, the temperature of the spinning air is 32-36 ℃ higher based on the spinning temperature, and the air speed is 38-44 m/s.
And 2, a pre-oxidation furnace.
The semi-mesh belt conveying semi-conductor roller conveying is adopted in the pre-oxidation process, the conveying time is 40% -60% of the time, the semi-mesh belt conveying semi-conductor roller conveying is adopted, the semi-mesh belt conveying is carried out by using the arrangement accumulation type mesh belt, and the semi-mesh belt conveying is carried out by using the guide roller 60% -40% of the time, so that the method effectively controls the fiber damage caused by the upper roller when the fiber does not reach the strength; in order to improve the heat efficiency, the heating mode is changed into an infrared heating air circulation; the temperature control mode adopts infrared temperature measurement to more accurately measure the fiber temperature; the pre-oxidation temperature control is more suitable for different materials and fluctuation changes of the materials, the temperature control is changed to be interlocked with the spinning temperature, the initial temperature is 220-280 ℃ lower than the spinning temperature, and the final temperature is 10-18 ℃ higher than the spinning temperature; in order to improve the pre-oxidation efficiency, the atomized oxidant is added, and the addition amount is 600 ml/min; the pre-oxidation time was 120 min.
And 3, carbonizing.
The temperature measurement and control of the thermocouple is changed into the temperature measurement and control of the infrared thermometer, so that the temperature of the material can be directly detected, and the control is more accurate; the resistance heating is changed into medium-frequency induction heating, so that the heat energy conversion rate is higher, the heating speed is high, and the regional fluctuation is small; an online resistivity monitor is added, the temperature of the carbonization furnace is controlled by the monitor in a linkage way, and the resistivity is controlled to be 2 +/-0.3 x 10 -3 Ωcm。
Comparative example 1.
Step 1, drawing spinning, which specifically comprises the following operations.
1. Selecting materials: anisotropic (mesophase) spinning pitch resin: the softening point is 302 +/-5 ℃, the content of mesophase is 88 percent, and the coking value is more than 85 percent.
2. Melting: through the single-screw material melting machine, the temperature of the melting material is controlled to be 320-330 ℃.
3. Spinning: the spinning temperature is 330-350 ℃, the spinning speed is 680r/min (60m/min), and the spinning pressure is 1.6 mpa.
And 2, pre-oxidizing, specifically operating as follows.
1. Heating: a resistance heater is provided to heat the air.
2. Temperature control: temperature control adopts thermal resistance to measure temperature; the initial temperature is controlled to be 110-128 ℃, and the final temperature is controlled to be 312-340 ℃.
3. Tension force: fiber drafting tension of 3 → 36mpa/mm 2 。
4. Time consumption: pre-oxidation time 206 min.
And 3, carbonizing.
1. Heating: a resistance heater is selected.
2. Temperature control: the temperature is controlled by a thermocouple; the initial temperature is controlled to be 500-800 ℃, and the final temperature and high pressure softening point is 1000-1400 ℃.
3. Tension force: fiber draw tension 96 → 380mpa/mm 2 。
4. The nitrogen amount is 140-220 m 3 /h。
5. Time consumption: pre-oxidation time 20 min.
Example 1 and comparative example 1 the results of the process comparisons relating to the pitch-based carbon fiber preparation methods are shown in tables 1-4.
Table 1. results of comparing the drawn spinning process of example 1 with the drawn spinning process of comparative example 1.
Table 2. results of comparing the pre-oxidation process of example 1 with the pre-oxidation process of comparative example 1.
| Item | The weight of the fiber is increased% | Pre-oxidation time min | Percentage of fiber breakage% | Coefficient of power consumption |
| Comparative example 1 | 10～13.6 | 206 | 35 | 1 |
| Example 1 | 11.2～12.5 | 120 | 4 | 0.7 |
TABLE 3 carbonization process of example 1 and comparative example 1.
| Item | Carbon content% | Resistivity 10 -3 Ωcm | Coefficient of power consumption |
| Comparative example 1 | 93 | 42 | 1 |
| Example 1 | 96 | 5 | 0.65 |
Table 4. carbon fiber prepared in example 1 and comparative example 1 test comparative results.
Example 2.
A preparation method of pitch-based carbon fiber filaments comprises the following specific steps.
Step 1, drawing and spinning.
In order to prevent secondary damage of fibers caused in the pre-oxidation yarn guiding process, drawing is changed into a drawing method without winding a positive and negative pressure roller, the rotating speed of the drawing roller is 680-720 r/min, and the negative pressure suction pressure of the drawing roller is-36 to-40 kPa, and the positive pressure yarn removing pressure is 48-75 kPa; in order to improve the uniformity of materials, a non-stirring material melting machine is changed into a strong-stirring material melting machine, and the temperature of the melting material is controlled to be higher than 24-53 ℃ by taking the softening point as the reference; the spinning control is to carry out linkage control on the spinning temperature and an online spinning viscosity detector, the spinning temperature is controlled through the spinning viscosity, the viscosity is controlled to be 13 +/-2 pa.s, and the spinning reference temperature takes the basic experiment temperature as the reference temperature; auxiliary hot air is added for improving the drawable length of spinning wire drawing, the temperature of the spinning air is 34 ℃ higher by taking the spinning temperature as a reference, and the air speed is 42 m/s.
And 2, a pre-oxidation furnace.
The semi-mesh belt conveying semi-conductor roller conveying is adopted in the pre-oxidation process, the conveying time is 40% -60% of the time, the arranging and accumulating mesh belt conveying is adopted, and the guide roller conveying is 60% -40% of the time, so that the method effectively controls the fiber damage caused by the upper roller when the fiber does not reach the strength; in order to improve the heat efficiency, the heating mode is changed into an infrared heating air circulation mode; the temperature control mode adopts infrared temperature measurement to more accurately measure the fiber temperature; the pre-oxidation temperature control is more suitable for different materials and fluctuation changes of the materials, the temperature control is changed to be interlocked with the spinning temperature, the initial temperature is 220-280 ℃ lower than the spinning temperature, and the final temperature is 10-18 ℃ higher than the spinning temperature; in order to improve the pre-oxidation efficiency, the atomized oxidant is added, and the addition amount is 600 ml/min; the pre-oxidation time was 129 min.
And 3, carbonizing.
The temperature measurement and control of the thermocouple is changed into the temperature measurement and control of the infrared thermometer, so that the temperature of the material can be directly detected, and the control is more accurate; the resistance heating is changed into medium-frequency induction heating, so that the heat energy conversion rate is higher, the heating speed is high, and the regional fluctuation is small; an online resistivity monitor is added, the temperature of the carbonization furnace is controlled by the monitor in a linkage way, and the resistivity is controlled to be 2 +/-0.3 x 10 -3 Ωcm。
Comparative example 2.
Step 1, drawing spinning.
1. Selecting materials: anisotropic (mesophase) spinning pitch resin: the softening point is 291 +/-5 ℃, the content of mesophase is 85 percent, and the coking value is more than 82 percent.
2. Melting: through single screw rod melting machine, the melt temperature control is in 309 ~ 328 ℃.
3. Spinning: the spinning temperature is 329-341 ℃, the spinning speed is 680r/min (60m/min), and the spinning pressure is 1.6 mpa.
And 2, pre-oxidizing.
1. Heating: a resistance heater is provided to heat the air.
2. Temperature control: the temperature is controlled by adopting a thermal resistor to measure the temperature; the initial temperature is controlled to be 102-118 ℃, and the final temperature is controlled to be 306-338 ℃.
3. Tension force: fiber drafting tension of 3 → 36mpa/mm 2 。
4. Time consumption: pre-oxidation time 226 min.
And 3, carbonizing.
1. Heating: a resistance heater is selected.
2. Temperature control: the temperature is controlled by a thermocouple; the initial temperature is controlled to be 500-800 ℃, and the final temperature and high pressure softening point is 1000-1400 ℃.
3. Tension force: fiber drafting tension 96 → 380mpa/mm 2 。
4. The nitrogen amount is 140-220 m 3 /h。
5. Time consumption: pre-oxidation time 20 min.
The results of comparing the processes involved in the methods of preparing pitch-based carbon fibers in example 2 and comparative example 2 are shown in tables 5 to 8.
Table 5. results of comparing the draw spinning process of example 2 with the draw spinning process of comparative example 2.
Table 6. results of comparing the pre-oxidation process of example 2 with the pre-oxidation process of comparative example 2.
| Item | The weight of the fiber is increased% | Pre-oxidation time min | Percentage of fiber breakage% | Coefficient of power consumption |
| Comparative example 2 | 9.9～13.3 | 226 | 37 | 1 |
| Example 2 | 11.0～12.4 | 129 | 4 | 0.74 |
TABLE 7 carbonization process of example 2 and comparative example 2.
| Item | Carbon content% | Resistivity 10 -3 Ωcm | Coefficient of power consumption |
| Comparative example 2 | 92 | 44.1 | 1 |
| Example 2 | 96 | 5.2 | 0.68 |
Table 8. carbon fibers prepared in example 2 and comparative example 2 were examined for comparison results.
Example 3.
A preparation method of pitch-based carbon fiber filaments comprises the following specific steps.
Step 1, drawing and spinning.
In order to prevent secondary damage of fibers caused in the pre-oxidation yarn guiding process, drawing is changed into a drawing method without winding a positive and negative pressure roller, the rotating speed of the drawing roller is 680-720 r/min, and the negative pressure suction pressure of the drawing roller is-36 to-40 kPa, and the positive pressure yarn removing pressure is 48-75 kPa; in order to improve the uniformity of the materials, a non-stirring material melting machine is changed into a strong stirring material melting machine, and the temperature of the melting materials is controlled to be higher than 20-26 ℃ by taking the softening point as the reference; the spinning control is to carry out linkage control on the spinning temperature and an online spinning viscosity detector, the spinning temperature is controlled through the spinning viscosity, the viscosity is controlled to be 13 +/-2 pa.s, and the spinning reference temperature takes the basic experiment temperature as the reference temperature; auxiliary hot air is added for improving the drawable length of spinning wire drawing, the temperature of the spinning air is 32-36 ℃ higher based on the spinning temperature, and the air speed is 38-44 m/s.
And 2, a pre-oxidation furnace.
The semi-mesh belt conveying semi-conductor roller conveying is adopted in the pre-oxidation process, the conveying time is 40% -60% of the time, the semi-mesh belt conveying semi-conductor roller conveying is adopted, the conveying time is 60% -40% of the time, the semi-mesh belt conveying semi-conductor roller conveying is adopted, and the conveying roller conveying is adopted, so that the method effectively controls the fiber damage caused by the roller when the fiber does not reach the strength; in order to improve the heat efficiency, the heating mode is changed into an infrared heating air circulation mode; the temperature control mode adopts infrared temperature measurement to more accurately measure the fiber temperature; the pre-oxidation temperature control is more suitable for different materials and fluctuation changes of the materials, the temperature control is changed to be interlocked with the spinning temperature, the initial temperature is 220-280 ℃ lower than the spinning temperature, and the final temperature is 10-18 ℃ higher than the spinning temperature; in order to improve the pre-oxidation efficiency, the atomized oxidant is added, and the addition amount is 600 ml/min; the pre-oxidation time was 129 min.
And 3, carbonizing.
The temperature measurement and control of the thermocouple is changed into the temperature measurement and control of the infrared thermometer, so that the temperature of the material can be directly detected, and the control is more accurate; the resistance heating is changed into medium-frequency induction heating, so that the heat energy conversion rate is higher, the heating speed is high, and the area fluctuation is small; an on-line resistivity monitor connected with the on-line resistivity monitoring instrumentThe temperature of the carbonization furnace is controlled by a lock, and the resistivity is controlled to be 2 +/-0.3 x 10 -3 Ωcm。
Comparative example 3.
Step 1, drawing and spinning.
1. Selecting materials: isotropic spin pitch resin: the softening point is 282 +/-5 ℃ and the coking value is more than 80 percent.
2. Melting: through the single-screw material melting machine, the temperature of the melting material is controlled to be 301-319 ℃.
3. Spinning: the spinning temperature is 308-330 ℃, the spinning speed is 680r/min (60m/min), and the spinning pressure is 1.6 mpa.
And 2, pre-oxidizing.
1. Heating: a resistance heater is provided to heat the air.
2. Temperature control: the temperature is controlled by adopting a thermal resistor to measure the temperature; the initial temperature is controlled to be 105-122 ℃, and the final temperature and high pressure softening point is 308-339 ℃.
3. Tension force: fiber drafting tension of 3 → 36mpa/mm 2 。
4. Time consumption: pre-oxidation time 226 min.
And 3, carbonizing.
1. Heating: a resistance heater is selected.
2. Temperature control: the temperature is controlled by a thermocouple; the initial temperature is controlled to be 500-800 ℃, and the final temperature and high pressure softening point is 1000-1400 ℃.
3. Tension force: fiber drafting tension 96 → 380mpa/mm 2 。
4. The nitrogen amount is 140-220 m 3 /h。
5. Time consumption: pre-oxidation time 20 min.
Example 3 and comparative example 3 the results of the process comparisons relating to the pitch-based carbon fiber preparation methods are shown in tables 9-12.
Table 9. results of comparing the drawn spinning process of example 3 with the drawn spinning process of comparative example 3.
TABLE 10 results of the pre-oxidation process of example 3 versus the pre-oxidation process of comparative example 3.
| Item | The weight of the fiber is increased% | Pre-oxidation time min | Percentage of fiber damage% | Coefficient of power consumption |
| Comparative example 3 | 9.7～13.0 | 226 | 37 | 1 |
| Example 3 | 11.1～12.2 | 129 | 4 | 0.74 |
Table 11 carbonization process of example 3 and carbonization of comparative example 3 were compared to obtain results.
| Item | Carbon content% | Resistivity 10 -3 Ωcm | Coefficient of power consumption |
| Comparative example 3 | 92 | 44.6 | 1 |
| Example 3 | 96 | 4.9 | 0.66 |
Table 12. carbon fibers prepared in example 3 and comparative example 3 were examined for comparison results.
Example 4.
A preparation method of pitch-based carbon fiber filaments comprises the following specific steps.
Step 1, drawing and spinning.
In order to prevent secondary damage of fibers caused in the pre-oxidation yarn guiding process, drawing is changed into a drawing method without winding a positive and negative pressure roller, the rotating speed of the drawing roller is 680-720 r/min, and the negative pressure suction pressure of the drawing roller is-36 to-40 kPa, and the positive pressure yarn removing pressure is 48-75 kPa; in order to improve the uniformity of the materials, a non-stirring material melting machine is changed into a strong-stirring material melting machine, and the temperature of the melting material is controlled to be higher than 20-26 ℃ by taking the softening point as the reference; the spinning control is to carry out linkage control on the spinning temperature and an online spinning viscosity detector, the spinning temperature is controlled through the spinning viscosity, the viscosity is controlled to be 13 +/-2 pa.s, and the spinning reference temperature takes the basic experiment temperature as the reference temperature; auxiliary hot air is added for improving the drawable length of spinning wire drawing, the temperature of the spinning air is 32-36 ℃ higher based on the spinning temperature, and the air speed is 38-44 m/s.
And step 2, a pre-oxidation furnace.
The semi-mesh belt conveying semi-conductor roller conveying is adopted in the pre-oxidation process, the conveying time is 40% -60% of the time, the semi-mesh belt conveying semi-conductor roller conveying is adopted, the conveying time is 60% -40% of the time, the semi-mesh belt conveying semi-conductor roller conveying is adopted, and the conveying roller conveying is adopted, so that the method effectively controls the fiber damage caused by the roller when the fiber does not reach the strength; in order to improve the heat efficiency, the heating mode is changed into an infrared heating air circulation; the temperature control mode adopts infrared temperature measurement to more accurately measure the fiber temperature; the pre-oxidation temperature control is more suitable for different materials and fluctuation changes of the materials, the temperature control is changed to be interlocked with the spinning temperature, the initial temperature is 220-280 ℃ lower than the spinning temperature, and the final temperature is 10-18 ℃ higher than the spinning temperature; in order to improve the pre-oxidation efficiency, the atomized oxidant is added, and the addition amount is 600 ml/min; the pre-oxidation time was 129 min.
And 3, carbonizing.
The temperature measurement and control of the thermocouple is changed into the temperature measurement and control of the infrared thermometer, so that the temperature of the material can be directly detected, and the control is more accurate; the resistance heating is changed into medium-frequency induction heating, so that the heat energy conversion rate is higher, the heating speed is high, and the regional fluctuation is small; an online resistivity monitor is added, the temperature of the carbonization furnace is controlled by the monitor in a linkage way, and the resistivity is controlled to be 2 +/-0.3 x 10 -3 Ωcm。
Comparative example 4.
Step 1, drawing and spinning.
1. And selecting materials: isotropic spin pitch resin: the softening point is 273 +/-5 ℃ and the coking value is more than 78 percent.
2. Melting: through the single-screw material melting machine, the temperature of the melting material is controlled to be 392-310 ℃.
3. Spinning: the spinning temperature is 300-321 ℃, the spinning speed is 680r/min (60m/min), and the spinning pressure is 1.6 mpa.
And step 2, pre-oxidation.
1. Heating: a resistance heater is selected.
2. Temperature control: the temperature is controlled by a thermocouple; the initial temperature is controlled to be 500-800 ℃, and the final temperature and high pressure softening point is 1000-1400 ℃.
3. Tension force: fiber drafting tension 96 → 380mpa/mm 2 。
4. The nitrogen amount is 140-220 m 3 /h。
5. Time consumption: pre-oxidation time 20 min.
And 3, carbonizing.
1. Heating: a resistance heater is provided to heat the air.
2. Temperature control: the temperature is controlled by adopting a thermal resistor to measure the temperature; the initial temperature is controlled to be 105-122 ℃, and the final temperature and high pressure softening point is 308-339 ℃.
3. Tension force: fiber drafting tension of 3 → 36mpa/mm 2 。
4. Time consumption: pre-oxidation time 226 min.
Example 4 and comparative example 4 the results of the process comparisons relating to the pitch-based carbon fiber preparation methods are shown in tables 13-16.
Table 13. results of comparing the drawn spinning process of example 4 with the drawn spinning process of comparative example 4.
Table 14 results of comparing the pre-oxidation process of example 4 with the pre-oxidation process of comparative example 4.
| Item | The weight of the fiber is increased% | Pre-oxidation time min | Percentage of fiber damage% | Coefficient of power consumption |
| Comparative example 4 | 9.8～13.0 | 226 | 39 | 1 |
| Example 4 | 11.0～12.2 | 129 | 4 | 0.76 |
TABLE 15 carbonization process of example 4 and comparative example 4.
| Item | Carbon content% | Resistivity 10 -3 Ωcm | Coefficient of power consumption |
| Comparative example 4 | 92 | 43 | 1 |
| Example 4 | 96 | 5.0 | 0.68 |
Table 16. carbon fibers prepared in example 3 and comparative example 3 were examined for comparison results.
Compared with the comparative example, in the drawing spinning process in the comparative example, the viscosity is very unstable in the spinning process due to large deviation of the softening point, so that the deviation of the filament diameter is large, and the filament breakage rate is high; the winding type spinning and wire drawing has extremely high fiber damage in the wire guiding process due to the fact that the precursor fiber is very fragile. The damage rate of the guide roller conveying fiber is very high in the pre-oxidation process due to the problems of the pre-oxidation of the comparative example; resistance heating energy conversion and low thermal efficiency; the temperature measurement of the thermal resistor has large limitation and can not accurately detect the temperature change of the fiber, so that the pre-oxidation degree is not accurately controlled to influence the performance of the fiber; the pre-oxidation time is long, and the manufacturing cost is increased. The comparative example resistor has low heating energy conversion and large zone temperature fluctuation; the actual temperature of the material cannot be detected due to inaccurate temperature measurement of the couple. The preparation method provided by the invention utilizes the on-line viscometer to control the viscosity of the spinning resin, thereby keeping the spinning resin in the optimal spinning state; micro air flow guiding is additionally added in the drawing spinning, and then the problems that the diameter of the original yarn is too thick and the fiber yarn is easy to break and difficult to lead out in the spinning are solved by a non-winding roller drawing method; in the pre-oxidation treatment process, the energy conversion rate is improved by adopting an infrared heating mode and a hot air circulating heating mode, the production cost is effectively reduced, and the temperature control is more accurate by adopting a thermal resistor and infrared temperature measurement; the pro-oxidant is added into the pre-oxidation furnace, so that the pre-oxidation time is shortened, the pre-oxidation effect is improved, and various problems of fiber skin-core structure, overoxidation, insufficient oxidation and the like which are frequently generated in the pre-oxidation process are solved; the semi-mesh belt conveying semi-conductor roller conveying is adopted in the pre-oxidation process, so that fiber damage caused by the fact that the fibers do not reach the strength and the roller is arranged is prevented; during carbonization, the temperature control adopts a thermocouple to measure temperature, and carbonization adopts two modes of low-temperature section new electromagnetic induction heating and high-temperature section resistance heating, so that the heating efficiency of the carbonization furnace is improved, the cost is saved, and the performance of carbon fibers is also improved.
Claims (8)
1. A preparation method of pitch-based carbon fiber filaments comprises the following specific steps:
step 1, drawing spinning: selecting spinnable asphalt resin to be melted and mixed by a strong stirring type melting machine, wherein the spinnable asphalt resin is various sameness spinnable asphalt resin or various dissimilarity spinnable asphalt resin, the spinnable asphalt resin has the indexes that the coking value is more than 75 percent, the content of the intermediate phase of the various dissimilarity asphalt resin is more than 60 percent, the melted material enters a spinning cavity through a pipeline and is pumped into a spinning cavity through a gear pump, the spinning viscosity and the temperature are extruded and spun through a spinning plate, the spinning viscosity and the temperature are controlled through a spinning resin online viscometer, the spinning viscosity is controlled to be 6-35 pa.s, the spinning temperature is controlled to be 20-50 ℃ higher than the softening point, the spinning pressure is 2.5-4.5 mpa, then the spinning is stretched and spun through a non-winding type stretching roller barrel, the rotating speed of the stretching roller is 580-780 r/min, the negative pressure of the stretching roller is-2 to-45 kPa, the positive pressure of the stretching roller is 4-80 kPa, micro air flow guiding is additionally added in the stretching and spinning, the drafting roller adopts a non-winding type drafting roller for drafting;
step 2, pre-oxidation: the fiber is conveyed by an arrangement accumulation type mesh belt in 40-60% of the time in a pre-oxidation furnace conveying mode, and is conveyed by a guide roller in 60-40% of the time; adding a trace amount of atomized oxidation auxiliary agent into the furnace chamber; the heating adopts an infrared heating air circulation mode; temperature control adopts thermal resistance and infrared temperature measurement; the pre-oxidation treatment temperature is set according to the softening point of the protofilament spinnable asphalt; in order to improve the physical properties of the fibers and enable molecular structures in the fibers to be arranged more orderly, proper tension is added to the fibers at a conveying guide roller, and the tension is 3-40 mpa/mm;
step 3, carbonization: the muffle furnace is conveyed by adopting an inert gas protection continuous guide rail in a carbonization treatment mode, a new electromagnetic induction heating mode and an original resistance heating mode are adopted for heating the carbonization furnace, the initial temperature of the carbonization furnace is higher than 800 ℃, the change of the resistivity is monitored by an online resistance measuring instrument, and the resistivity is controlled to be 1.5-30 x 10 -3 Omega cm, through resistanceControlling the temperature of the carbonization furnace by using the rate data; adding protective gas nitrogen in the high-temperature carbonization; the proper tension is added to the fiber at the conveying guide roller, and the fiber drafting tension is 80-400 mpa/mm.
2. The method according to claim 1, wherein the melting temperature in step 1 is 15 to 35 ℃ higher than the softening point, and the stirring speed is 80 to 350 r/min.
3. The method according to claim 1, wherein the micro-airflow velocity in step 1 is 30 to 50 m/s.
4. The method of claim 1, wherein the flow rate of the atomized oxidation assistant in step 1 is 100 to 800 ml/min.
5. The method according to claim 1, wherein the pre-oxidation treatment temperature in the step 2 is set to an initial temperature of 100 to 220 ℃ below the softening point of the spinnable pitch resin and a final temperature of 8 to 140 ℃ above the softening point of the spinnable pitch resin.
6. The preparation method according to claim 1, wherein the pre-oxidation time in the step 2 is 1.5 to 8 hours.
7. The method according to claim 1, wherein the nitrogen is harvested at 100-260 m/h according to step 3 and has a purity of 99.99%.
8. The method according to claim 1, wherein the carbonization time in step 3 is 8 to 30 min.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4005183A (en) * | 1972-03-30 | 1977-01-25 | Union Carbide Corporation | High modulus, high strength carbon fibers produced from mesophase pitch |
| CN102560744A (en) * | 2011-12-21 | 2012-07-11 | 鞍山塞诺达碳纤维有限公司 | Method for preparing universal pitch-based carbon fiber |
| CN103122503A (en) * | 2013-01-28 | 2013-05-29 | 江苏国正新材料科技有限公司 | Preparation method of high-strength and high-modulus pitch-based fiber |
| CN108221089A (en) * | 2017-12-26 | 2018-06-29 | 宜兴市天宇世纪高新科技有限公司 | A kind of preparation method of asphalt base carbon fiber |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4005183A (en) * | 1972-03-30 | 1977-01-25 | Union Carbide Corporation | High modulus, high strength carbon fibers produced from mesophase pitch |
| CN102560744A (en) * | 2011-12-21 | 2012-07-11 | 鞍山塞诺达碳纤维有限公司 | Method for preparing universal pitch-based carbon fiber |
| CN103122503A (en) * | 2013-01-28 | 2013-05-29 | 江苏国正新材料科技有限公司 | Preparation method of high-strength and high-modulus pitch-based fiber |
| CN108221089A (en) * | 2017-12-26 | 2018-06-29 | 宜兴市天宇世纪高新科技有限公司 | A kind of preparation method of asphalt base carbon fiber |
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