CN116024679A - High-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, and preparation method and application thereof - Google Patents
High-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, and a preparation method and application thereof, and mainly solves the problems of more precursor filaments after steam drafting and low strength, modulus and elongation of carbon fibers in the prior art. According to the method for manufacturing the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, wet spinning is adopted, and the fiber after drying densification is subjected to steam drafting test under the conditions of steam pressure of 0.3MPa and drafting multiple of 2.5 times, so that the technical scheme that the tension born by each fiber is 0.5-1.5 cN is adopted, the problems in the prior art are better solved, and the method can be used in industrial production of the polyacrylonitrile carbon fiber precursor.
Description
Technical Field
The invention belongs to the technical field of carbon fibers, and particularly relates to a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, and a preparation method and application thereof.
Background
Polyacrylonitrile (PAN) based carbon fiber has many excellent properties such as high strength, light weight, low density, high rigidity, heat resistance, corrosion resistance, wear resistance, fatigue resistance, electric conduction, heat conduction, biocompatibility and the like, is widely applied to the aerospace fields such as missiles, rockets, satellites and the like, and the general industrial fields such as automobile manufacturing, wind power generation, electric power loose civil construction, medical appliances and the like, and is an important strategic material and industrial material.
The structure of the material determines its properties. The modulus and strength of the carbon fiber are closely related to the preferential orientation of graphite-like crystals in the carbon fiber along the fiber axis, the pore structure in the fiber and the like, and the change and formation of the structures are closely related to the acquisition of spinning solution, the preparation of precursor fibers and the subsequent pre-oxidation and carbonization processes. The structure and defects of the precursor are transferred into the carbon fiber along with the preoxidation and carbonization processes, so that the structure and the performance of the carbon fiber are irreversibly affected. The high-quality carbon fiber precursor has the characteristics of few surface defects, few pore structures, compact structure, good stretchability, high heat resistance and the like.
The precursor for preparing the carbon fiber is a plurality of viscose fiber, asphalt and PAN fiber which are only produced in a large-scale industrialized way, wherein the PAN-based carbon fiber has the characteristics of higher carbon yield, excellent mechanical property, mature process and the like, and becomes a main product of the carbon fiber, and more than 90% of the carbon fiber in the market is prepared from the PAN fiber at present. In the preparation process of PAN fiber, the spinning process can be divided into wet spinning and dry-jet wet spinning. Compared with dry-jet wet spinning, the wet spinning process is more mature, the spinning process is stable and easy to control, residual solvents in the fibers are easy to remove, and the prepared carbon fibers are easier to combine with composite materials, so that the method is an important method for preparing high-strength high-modulus high-toughness carbon fiber precursors. In the wet spinning process, dimethyl sulfoxide is used as a solvent to prepare the polyacrylonitrile-based carbon fiber precursor, so that the method has the characteristics of low toxicity, high solubility of the polyacrylonitrile copolymer in the solvent and the like, and is also an important solvent system for preparing the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor.
Steam drafting is an important step in the process of preparing polyacrylonitrile-based carbon fiber precursor by wet spinning. Patent JP1983214526A, JP1988159526A, CN111088543A discloses a preparation method of polyacrylonitrile-based carbon fiber precursor, wet spinning is adopted, and only the tension of nascent fiber, steam drawn fiber and pre-oxidized fiber is disclosed, and the relationship between the tension of high intrinsic viscosity fiber and the process, which is suitable in the steam drawing process, is not disclosed. In the process of wet spinning steam drafting, the influencing factors of the steam drafting process are numerous, and the steam pressure and temperature in the steam drafting cavity, the drafting multiple and the residence time of the fiber in the drafting cavity can influence the quality of the carbon fiber precursor, thereby influencing the quality of the final carbon fiber. In the high-pressure steam drafting stage, any process condition change leads to unstable tension in the drafting process, so that the friction effect among carbon fiber precursor tows is obviously increased, more filaments are generated by the precursor, and finally the strength, modulus and elongation of the obtained carbon fiber are deteriorated.
Disclosure of Invention
The invention mainly solves the technical problems of more filaments after steam drafting and low strength, modulus and elongation of carbon fibers in the prior art. The invention solves the technical problems well by adopting the manufacturing method of the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, and has the advantages of less precursor filaments, good carbon fiber strength, modulus and elongation in the spinning process.
The invention aims to provide a preparation method of a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, which comprises the steps of solidifying and forming a polyacrylonitrile precursor, solidifying and drawing, hot water drawing, washing, oiling, drying and densification, steam drawing and steam heat setting to obtain the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, wherein after drying and densification treatment, the tension born by each fiber under the conditions that the steam pressure is 0.3MPa and the drawing multiple is 2.5 times is 0.5-1.5 cN.
The preparation method comprises the following steps:
the intrinsic viscosity of the polyacrylonitrile stock solution is 3.0-5.0 dL/g, preferably 3.5-4.5 dL/g.
The solidification and drafting comprises at least three times, wherein the temperature of each solidification and drafting is 20-80 ℃, and the drafting ratio is 1-3; preferably, the temperature of each solidification draft is 30-70 ℃, and the draft ratio is 1-2.
The hot water drawing comprises at least 4 channels; the temperature of the hot water drawing is 90-100 ℃, preferably 95-99 ℃. The total draft ratio of the hot water draft is more than or equal to 4 times, and the 4 th hot water draft ratio is more than or equal to 1.3 times; preferably, the total draft ratio of the hot water draft is more than or equal to 5 times, and the 4 th hot water draft ratio is 1.5-2.5.
The oiling, drying and densification are carried out at least two stages; the drying densification temperature is 90-150 ℃, no drafting is applied, and preferably the drying densification temperature is 100-140 ℃.
The pressure of the steam drafting is 0.3-0.7 MPa, and the drafting ratio is more than or equal to 2.5; preferably, the pressure of the steam draft is 0.3-0.5 MPa, and the draft ratio is 2.5-3.5; the spinning speed in the steam drafting process is 20-80 m/min, preferably 25-55 m/min.
The second purpose of the invention is to provide a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, which is prepared by the preparation method. The linear density of the carbon fiber precursor is 0.6-1.0 dtex, the strength is 7.0-10.5 cN/dtex, the modulus is 150-210 cN/dtex, and the elongation is 7.5-9.5%.
The invention aims at providing the carbon fiber, which is prepared from the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor obtained by the preparation method or the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor.
In the above technical solution, other aspects of the preparation method of the polyacrylonitrile-based precursor are not particularly limited, and the polyacrylonitrile-based precursor may be prepared from a polyacrylonitrile spinning solution commonly used in the art through a spinning process commonly used in the art, and the polyacrylonitrile spinning solution and the spinning process are not particularly limited, and the polyacrylonitrile copolymer used in the application may be prepared from a comonomer commonly used in the art, for example, but not limited to, the polyacrylonitrile comonomer is a vinyl-containing monomer, and the comonomer is preferably one or more of acrylic acid esters, vinyl esters, acrylamides, sulfonates, and ammonium salts.
During vapor drawing, the structure of the fiber (including crystalline, oriented, amorphous, and porous structures) is affected by conditions such as vapor draw pressure, fold, residence time, and velocity. Under the tensile experimental evaluation conditions of specific steam pressure and specific draft multiple (the steam pressure is 0.3MPa and the draft multiple is 2.5 times), the fiber can be ensured to form a perfect crystallization orientation structure, and the offline drying densified fiber can be evaluated in a wider spinning speed and residence time range. In the process of preparing the precursor, the fiber in the tension numerical range can be obtained by controlling the conditions of steam drafting pressure, drafting ratio, spinning speed, drying densification and the like, and the precursor obtained by the method can be subjected to the processes of pre-oxidation, low-temperature carbonization, high-temperature carbonization, graphitization treatment and the like to obtain the high-strength high-modulus high-toughness carbon fiber. In the preparation process of the precursor, the invention adopts the proper fiber to carry out steam stretching, so that the generation of the filament in the precursor can be effectively reduced, and the prepared carbon fiber has the characteristics of high strength, high modulus and high toughness.
Compared with the prior art, the invention has the following advantages:
firstly, the tension of the high-intrinsic-viscosity fiber in the steam drafting process under lower steam pressure is controlled, so that whether more filaments are generated in the precursor fiber or not due to overlarge tension change is avoided;
secondly, the invention avoids the deterioration of the strength, modulus and elongation of the carbon fiber caused by any change of process conditions by controlling a plurality of influencing factors (such as steam pressure and temperature, draft multiple and residence time) of the fiber in the steam drafting process.
Detailed Description
The present invention is described in detail below with reference to specific embodiments, and it should be noted that the following embodiments are only for further description of the present invention and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adjustments of the present invention by those skilled in the art from the present disclosure are still within the scope of the present invention.
The test instruments and test conditions used in the examples are as follows:
the tension value born by each fiber in the steam drafting process is obtained by dividing the tension of the tows in the steam drafting cavity which is held and walked by the hand-held tensiometer by the number of the tows, measuring 10 times each time, and taking a tie value.
The linear density of the fiber is obtained by cutting off a tow 30cm in front of the last drawing roller after a steam drawing cavity on line through a length fixing device, then placing the fiber and the length fixing device in an oven for drying so as to avoid the change of the fiber length caused by the drying process of the fiber, dividing the dried fiber weight (g) by the total length of the fiber (g is 1 m), measuring 10 times each time, and taking an average value.
The mechanical properties of the carbon fiber precursor are measured by GB/T14337-2008.
The mechanical properties of the carbon fiber are measured by GB/T3362-2017.
And in the steam drafting process, the filaments of the filament bundles are obtained by counting the number of filaments for 5 hours through an online camera.
[ example 1 ]
1. Preparing a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, adopting a wet spinning method, wherein the intrinsic viscosity of a spinning solution is 3.5dL/g, the solid content is 18%, accurately metering and filtering the spinning solution by a metering pump, extruding the spinning solution by a spinneret plate with 6000 holes and 60 mu m aperture, solidifying the spinning solution in a first solidifying bath of which the solidifying bath is a dimethyl sulfoxide aqueous solution, solidifying the spinning solution at 26 ℃ and 52% concentration, and then carrying out three-stage solidifying and drafting at 30 ℃ and 40 ℃ and 50 ℃ respectively, wherein the drafting ratio is 1.0, 1.1 and 1.2 respectively; then four-stage hot water drafting at 95deg.C, 96deg.C, 97deg.C and 99deg.C with drafting ratios of 1.38, 1.40, 1.48 and 1.50 respectively; after oiling, carrying out two-stage drying densification treatment at 110 ℃ and 120 ℃ respectively, testing the dried and densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried and densified fiber when the tension born by each fiber is 0.5 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.3MPa and the drafting multiplying power of 2.5 times and the spinning speed of 25 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 1.0dtex, the strength and the modulus are respectively 7.5cN/dtex and 155cN/dtex, and the elongation is 9.5%.
2. Preparing high-strength high-modulus high-toughness carbon fibers, pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fibers, wherein the pre-oxidized total draft ratio is 0.95; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.97 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the high-strength high-modulus high-toughness carbon fiber.
And counting the last roller of steam drafting through an online camera, wherein the number of filaments in the fiber per 5 hours at the last outlet is 20, the tensile strength of the carbon fiber is 5.5GPa, the modulus is 373GPa, and the elongation is 1.54%.
[ example 2 ]
1. Preparing a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, adopting a wet spinning method, wherein the intrinsic viscosity of a spinning solution is 3.9dL/g, the solid content is 18%, accurately metering and filtering the spinning solution by a metering pump, extruding the spinning solution by a spinneret plate with 6000 holes and 60 mu m aperture, solidifying the spinning solution in a first solidifying bath of which the solidifying bath is a dimethyl sulfoxide aqueous solution, solidifying the spinning solution at 26 ℃ and 52% concentration, and then carrying out three-stage solidifying drafting at 50 ℃ and 60 ℃ and 70 ℃ respectively, wherein the drafting ratio is 1.01, 1.05 and 1.10 respectively; then four-stage hot water drafting at 97deg.C, 98deg.C and 99deg.C with drafting ratios of 1.35, 1.50, 1.75 and 2.50 respectively; after oiling, carrying out two-stage drying densification treatment, wherein the temperature is 125 ℃ and 135 ℃, testing the dried and densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried and densified fiber when the tension born by each fiber is 1.5 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.38MPa and the drafting multiplying power of 3.4 times and the spinning speed of 55 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 0.65dtex, the strength and the modulus are respectively 10.1cN/dtex and 205cN/dtex, and the elongation is 7.7%.
2. Preparing high-strength high-modulus high-toughness carbon fibers, pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fibers, wherein the pre-oxidized total draft ratio is 0.96; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.97 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the high-strength high-modulus high-toughness carbon fiber.
And counting the last roller of steam drafting through an online camera, wherein the number of filaments in the fiber per 5 hours at the last outlet is 25, the tensile strength of the carbon fiber is 5.7GPa, the modulus is 378GPa, and the elongation is 1.47%.
[ example 3 ]
1. Preparing a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, adopting a wet spinning method, wherein the intrinsic viscosity of a spinning solution is 3.8dL/g, the solid content is 18%, accurately metering and filtering the spinning solution by a metering pump, extruding the spinning solution by a spinneret plate with 6000 holes and 60 mu m aperture, solidifying the spinning solution in a first solidifying bath of which the solidifying bath is a dimethyl sulfoxide aqueous solution, solidifying the spinning solution at 26 ℃ and 52% concentration, and then carrying out three-stage solidifying drafting at 40 ℃ and 50 ℃ and 60 ℃ respectively, wherein the drafting ratio is 1.05, 1.12 and 1.25 respectively; then four-stage hot water drafting at 96 deg.C, 97 deg.C and 99 deg.C with drafting ratios of 1.28, 1.43, 1.76 and 2.00 respectively; performing two-stage drying densification treatment after oiling, wherein the temperature is 115 ℃ and 125 ℃, testing the dried densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried densified fiber when the tension born by each fiber is 1.0 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.33MPa and the drafting multiplying power of 3.3 times and the spinning speed of 45 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 0.78dtex, the strength and the modulus are 9.9cN/dtex and 196cN/dtex respectively, and the elongation is 8.2%.
2. Preparing high-strength high-modulus high-toughness carbon fibers, pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fibers, wherein the pre-oxidized total draft ratio is 0.95; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.95 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the high-strength high-modulus high-toughness carbon fiber.
The last roller of steam drafting is counted by an online camera, the number of filaments in the fiber per 5 hours at the last outlet is 23, the tensile strength of the carbon fiber is 5.6GPa, the modulus is 376GPa, and the elongation is 1.50%.
[ example 4 ]
1. Preparing a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, adopting a wet spinning method, wherein the intrinsic viscosity of a spinning solution is 3.9dL/g, the solid content is 18%, accurately metering and filtering the spinning solution by a metering pump, extruding the spinning solution by a spinneret plate with 6000 holes and a pore diameter of 60 mu m, solidifying the spinning solution in a first solidifying bath of which the solidifying bath is a dimethyl sulfoxide aqueous solution, wherein the solidifying temperature is 26 ℃, the concentration is 52%, and then carrying out three-stage solidifying and drafting at the temperature of 45 ℃ and the temperature of 65 ℃ respectively, wherein the drafting ratio is 1.02, 1.15 and 1.20 respectively; then four-stage hot water drafting at 95deg.C, 98deg.C, 99deg.C and drafting ratios of 1.30, 1.45, 1.80 and 2.30 respectively; after oiling, carrying out two-stage drying densification treatment, wherein the temperature is 120 ℃ and 130 ℃, testing the dried and densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried and densified fiber when the tension born by each fiber is 1.1 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.35MPa and the drafting multiplying power of 3.1 times and the spinning speed of 50 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 0.71dtex, the strength and the modulus are 9.95cN/dtex and 202cN/dtex respectively, and the elongation is 8.0%.
2. Preparing high-strength high-modulus high-toughness carbon fibers, pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fibers, wherein the pre-oxidized total draft ratio is 0.95; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.96 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the high-strength high-modulus high-toughness carbon fiber.
The last roller is counted by an online camera to count the number of filaments in the fiber every 5 hours at the last outlet, the tensile strength of the carbon fiber is 5.66GPa, the modulus is 377GPa, and the elongation is 1.49%.
[ example 5 ]
1. Preparing a high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, adopting a wet spinning method, wherein the intrinsic viscosity of a spinning solution is 3.7dL/g, the solid content is 18%, accurately metering and filtering the spinning solution by a metering pump, extruding the spinning solution by a spinneret plate with 6000 holes and a pore diameter of 60 mu m, solidifying the spinning solution in a first solidifying bath of which the solidifying bath is a dimethyl sulfoxide aqueous solution, wherein the solidifying temperature is 26 ℃, the concentration is 52%, and then carrying out three-stage solidifying and drafting at the temperature of 35 ℃, the temperature of 45 ℃ and the temperature of 55 ℃ respectively, wherein the drafting ratio is 1.05, 1.15 and 1.25 respectively; then four-stage hot water drafting at 96 deg.C, 97 deg.C and 99 deg.C with drafting ratios of 1.20, 1.45, 1.75 and 2.10 respectively; after oiling, carrying out two-stage drying densification treatment, wherein the temperature is 115 ℃ and 125 ℃, testing the dried and densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried and densified fiber when the tension born by each fiber is 0.9 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.32MPa and the drafting multiplying power of 3.2 times and the spinning speed of 35 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 0.81dtex, the strength and the modulus are 9.91cN/dtex and 186cN/dtex respectively, and the elongation is 8.8%.
2. Preparing high-strength high-modulus high-toughness carbon fibers, pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fibers, wherein the pre-oxidized total draft ratio is 0.95; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.94 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the high-strength high-modulus high-toughness carbon fiber.
The last roller of steam drafting is counted by an online camera, the number of filaments in the fiber per 5 hours at the last outlet is 22, the tensile strength of the carbon fiber is 5.60GPa, the modulus is 375GPa, and the elongation is 1.52%.
[ comparative example 1 ]
1. Preparing polyacrylonitrile carbon fiber precursor by adopting a wet spinning method, wherein the intrinsic viscosity of the spinning solution is 3.5dL/g, the solid content is 18%, the spinning solution is accurately measured and filtered by a metering pump, then is extruded by a spinneret plate with 6000 holes and 60 mu m aperture, enters into a coagulation bath to be coagulated by a first coagulation bath of dimethyl sulfoxide aqueous solution, the coagulation temperature is 26 ℃, the concentration is 52%, and then is subjected to three-stage coagulation drafting, the temperature is 30 ℃, the temperature is 40 ℃, the temperature is 50 ℃, and the drafting ratio is 1.0, 1.1 and 1.2 respectively; then four-stage hot water drafting at 95deg.C, 96deg.C, 97deg.C and 99deg.C with drafting ratios of 1.35, 1.4, 1.45 and 1.48 respectively; after oiling, carrying out two-stage drying densification treatment, wherein the temperature is 120 ℃ and 130 ℃, testing the dried and densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried and densified fiber when the tension born by each fiber is 0.4 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.31MPa and the drafting multiplying power of 2.4 times and the spinning speed of 30 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 1.15dtex, the strength and the modulus are respectively 6.90cN/dtex and 140cN/dtex, and the elongation is 11.8%.
2. Preparing carbon fiber, namely pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fiber, wherein the total pre-oxidized draft ratio is 0.95; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.96 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the carbon fiber.
The last roller of steam drafting is counted by an online camera, the number of filaments in the fiber per 5 hours at the last outlet is 28, the tensile strength of the carbon fiber is 4.90GPa, the modulus is 345GPa, and the elongation is 1.85%.
[ comparative example 2 ]
1. Preparing polyacrylonitrile carbon fiber precursor by adopting a wet spinning method, wherein the intrinsic viscosity of the spinning solution is 3.8dL/g, the solid content is 18%, the spinning solution is accurately measured and filtered by a metering pump, then is extruded by a spinneret plate with 6000 holes and 60 mu m aperture, enters into a coagulation bath to be coagulated by a first coagulation bath of dimethyl sulfoxide aqueous solution, the coagulation temperature is 26 ℃, the concentration is 52%, and then is subjected to three-stage coagulation drafting, the temperature is 50 ℃, the temperature is 60 ℃, the temperature is 70 ℃, and the drafting ratio is 1.02, 1.10 and 1.20 respectively; then four-stage hot water drafting at 98deg.C, 98deg.C and 99deg.C with drafting ratios of 1.25, 1.85, 2.25 and 2.55 respectively; after oiling, carrying out two-stage drying densification treatment, wherein the temperature is 125 ℃ and 135 ℃, testing the dried and densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried and densified fiber when the tension born by each fiber is 1.55 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.35MPa and the drafting multiplying power of 3.6 times and the spinning speed of 55 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 0.7dtex, the strength and the modulus are 9.96cN/dtex and 203cN/dtex respectively, and the elongation is 8.1%.
2. Preparing carbon fiber, namely pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fiber, wherein the total pre-oxidized draft ratio is 0.96; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.97 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the carbon fiber.
The last roller of steam drafting is counted by an online camera, the number of filaments in the fiber per 5 hours at the last outlet is 35, the tensile strength of the carbon fiber is 5.50GPa, the modulus is 369GPa, and the elongation is 1.39%.
[ comparative example 3 ]
1. Preparing polyacrylonitrile carbon fiber precursor by adopting a wet spinning method, wherein the intrinsic viscosity of the spinning solution is 3.6dL/g, the solid content is 18%, the spinning solution is accurately measured and filtered by a metering pump, then is extruded by a spinneret plate with 6000 holes and 60 mu m aperture, enters into a coagulation bath to be coagulated by a first coagulation bath of dimethyl sulfoxide aqueous solution, the coagulation temperature is 26 ℃, the concentration is 52%, and then is subjected to three-stage coagulation drafting, the temperature is 40 ℃, the temperature is 50 ℃, the temperature is 60 ℃, and the drafting ratio is 1.01, 1.05 and 1.15 respectively; then four-stage hot water drafting at 96 deg.c, 97 deg.c, 98 deg.c and 99 deg.c in drafting ratio of 1.2, 1.6, 1.8 and 2.4; after oiling, carrying out two-stage drying densification treatment, wherein the temperature is 155 ℃ and 160 ℃, testing the dried densified fiber under the conditions of steam pressure of 0.3MPa, drawing multiplying power of 2.5 times and spinning speed of 25m/min, and obtaining the dried densified fiber when the tension born by each fiber is 1.7 cN;
the obtained dry densified fiber is subjected to steam drafting under the steam pressure of 0.32MPa and the drafting multiplying power of 3.1 times and the spinning speed of 50 m/min; finally, the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor is obtained through secondary oiling, secondary drying at 120 ℃ and filament collection, the linear density of the precursor is 0.74dtex, the strength and the modulus are respectively 7.5cN/dtex and 181cN/dtex, and the elongation is 9.1%.
2. Preparing carbon fiber, namely pre-oxidizing the precursor obtained in the step 1 at 180-260 ℃ to obtain pre-oxidized fiber, wherein the total pre-oxidized draft ratio is 0.95; then low-temperature carbonization and high-temperature carbonization are carried out at 300-750 ℃ and 800-1500 ℃, and the draft ratio is 0.97 times; and then graphitizing at 2800 ℃, and finally carrying out surface treatment, water washing, sizing, drying at 120 ℃ and filament collection to obtain the carbon fiber.
The last roller of steam drafting is counted by an online camera, the number of filaments in the fiber per 5 hours at the last outlet is 33, the tensile strength of the carbon fiber is 5.0GPa, the modulus is 348GPa, and the elongation is 1.77%.
According to the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber prepared by adopting the technical scheme, the number of filaments of the fiber is 22 at least every 5 hours in the steam drafting process through the online camera statistics, the tensile strength of the prepared carbon fiber can reach 5.7GPa, the modulus can reach 379GPa, the elongation can reach 1.54%, and a better technical effect is achieved.
Claims (11)
1. The preparation method of the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor comprises the steps of solidifying and forming a polyacrylonitrile stock solution, solidifying and drawing, hot water drawing, washing, oiling, drying and densification, steam drawing and steam heat setting to obtain the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor, wherein the tension born by each fiber under the conditions that the steam pressure is 0.3MPa and the drawing multiple is 2.5 times is 0.5-1.5 cN after the drying and densification treatment.
2. The method according to claim 1, wherein,
the intrinsic viscosity of the polyacrylonitrile stock solution is 3.0-5.0 dL/g, preferably 3.5-4.5 dL/g.
3. The method according to claim 1, wherein,
the solidification draft includes at least three passes.
4. The method according to claim 1, wherein,
in the solidification and drafting, the temperature of each solidification and drafting is 20-80 ℃ and the drafting ratio is 1-3; preferably, the temperature of each solidification draft is 30-70 ℃, and the draft ratio is 1-2.
5. The method according to claim 1, wherein,
the hot water drawing comprises at least 4 channels; and/or the number of the groups of groups,
the temperature of the hot water drawing is 90-100 ℃, preferably 95-99 ℃.
6. The method according to claim 5, wherein,
the total draft ratio of the hot water draft is more than or equal to 4 times, and the 4 th hot water draft ratio is more than or equal to 1.3 times; preferably, the total draft ratio of the hot water draft is more than or equal to 5 times, and the 4 th hot water draft ratio is 1.5-2.5.
7. The method according to claim 1, wherein,
the oiling, drying and densification are carried out at least two stages; and/or the number of the groups of groups,
the drying densification temperature is 90-150 ℃, no drafting is applied, and preferably the drying densification temperature is 100-140 ℃.
8. The method according to claim 1, wherein,
the pressure of the steam drafting is 0.3-0.7 MPa, and the drafting ratio is more than or equal to 2.5; preferably, the pressure of the steam draft is 0.3-0.5 MPa, and the draft ratio is 2.5-3.5; and/or the number of the groups of groups,
the spinning speed in the steam drafting process is 20-80 m/min, preferably 25-55 m/min.
9. A high strength, high modulus, high tenacity polyacrylonitrile carbon fiber precursor prepared by the method of any one of claims 1 to 8.
10. The polyacrylonitrile carbon fiber precursor according to claim 9 wherein,
the linear density of the carbon fiber precursor is 0.6-1.0 dtex, the strength is 7.0-10.5 cN/dtex, the modulus is 150-210 cN/dtex, and the elongation is 7.5-9.5%.
11. A carbon fiber produced from the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor obtained by the production method according to any one of claims 1 to 8 or the high-strength high-modulus high-toughness polyacrylonitrile carbon fiber precursor according to claim 9 or 10.
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