CN116949605A - Preparation method of carbon fiber based on electron beam irradiation - Google Patents

Preparation method of carbon fiber based on electron beam irradiation Download PDF

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Publication number
CN116949605A
CN116949605A CN202310899340.1A CN202310899340A CN116949605A CN 116949605 A CN116949605 A CN 116949605A CN 202310899340 A CN202310899340 A CN 202310899340A CN 116949605 A CN116949605 A CN 116949605A
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irradiation
carbon fiber
temperature
electron beam
tow
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徐学宏
张文晶
费楚然
温得浩
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Cgn High Tech Nuclear Materials Technology Suzhou Co ltd
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Cgn High Tech Nuclear Materials Technology Suzhou Co ltd
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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
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M10/00—Physical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. ultrasonic, corona discharge, irradiation, electric currents, or magnetic fields; Physical treatment combined with treatment with chemical compounds or elements
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
    • D06M2101/16—Synthetic fibres, other than mineral fibres
    • D06M2101/18—Synthetic fibres consisting of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M2101/26—Polymers or copolymers of unsaturated carboxylic acids or derivatives thereof
    • D06M2101/28—Acrylonitrile; Methacrylonitrile

Abstract

A preparation method of carbon fiber based on electron beam irradiation comprises the following steps: winding large-tow polyacrylonitrile fibers onto two parallel guide rollers to form spiral coils, so as to form a plurality of parallel wires; simultaneously irradiating a plurality of parallel wires through an irradiation window of an electron accelerator, and simultaneously starting traction equipment to carry out traction on large-tow polyacrylonitrile fibers, so that each parallel wire repeatedly passes through the irradiation window of the electron accelerator, and carrying out intermittent periodic electron beam irradiation under air atmosphere to obtain an irradiation modified PAN precursor; continuously connecting or transferring the irradiation modified PAN precursor to a carbon fiber production line, and carrying out rapid pre-oxidation by a multi-temperature-zone pre-oxidation furnace to obtain a pre-oxidized fiber; and (3) sequentially carrying out low-temperature carbonization and high-temperature carbonization treatment on the pre-oxidized fiber in a nitrogen atmosphere to obtain the high-performance large-fiber-bundle carbon fiber, wherein the number of monofilaments of the high-performance large-fiber-bundle carbon fiber is greater than or equal to 24K. Compared with the prior art, the method can successfully and effectively introduce the electron beam irradiation technology into the production process of the polyacrylonitrile-based carbon fiber.

Description

Preparation method of carbon fiber based on electron beam irradiation
Technical Field
The invention relates to the technical field of carbon fibers, in particular to a carbon fiber preparation method based on electron beam irradiation.
Background
The carbon fiber is generally prepared from precursor precursors through the technological processes of pre-oxidation, carbonization, graphitization, surface treatment/sizing and the like, has the characteristics of low density, high strength, high modulus, high temperature resistance, corrosion resistance, fatigue resistance and the like, and is widely applied to the fields of aerospace, wind power blades, pressure vessels, transportation, sports equipment and the like. Wherein, the Polyacrylonitrile (PAN) based carbon fiber has good structural and functional characteristics, and the yield is highest, accounting for about 90 percent of the total amount of the carbon fiber.
Pre-oxidation is an important step after the front opening in the carbon fiber production process, and plays a key role in the structure and performance of the final carbon fiber. In order to ensure that the filaments retain the fiber morphology during carbonization and prevent melt fracture, a pre-oxidation treatment is required to convert the linear molecular chains into heat-resistant ladder structures. The preoxidation process of PAN filaments is a complex chemical and structural transformation process, mainly involving cyclization, dehydrogenation, oxidation, etc. reactions, and giving off a large amount of heat. The preoxidation process is a severe exothermic process, if not well controlled, can cause local overheating, leading to fiber melting, bonding, breakage and even ignition, and the problem of heat release concentration is particularly pronounced in the production process of large-tow carbon fibers.
In order to control the exothermic behavior of PAN fibers in the pre-oxidation process, the traditional carbon fiber industrial production is provided with a multi-stage pre-oxidation furnace, and a slow heating mode of gradient temperature rise is mainly adopted, so that the pre-oxidation process consumes longer time and more energy. At present, the pre-oxidation time is as long as 60-120min, and is about 80-90% of the total production time of the carbon fiber, which is a main factor affecting the production efficiency of the carbon fiber. Accordingly, researchers have been working to shorten the pre-oxidation time to reduce the carbon fiber manufacturing cost.
The electron beam irradiation processing is an innovative processing method of the polymer material. PAN fiber generates a large amount of free radicals after electron beam irradiation treatment, cross-linking reaction is initiated by the recombination of the free radicals among molecular chains, cyclization reaction is generated by the addition of the free radicals of the molecular chains and cyano groups, and oxidation reaction is also generated between active free radicals and oxygen. In the prior art, the PAN precursor is modified by adopting electron beam irradiation, so that the pre-oxidation efficiency can be effectively improved, and the heat release quantity is reduced.
Patent CN 101798747B mentions a method for modifying polyacrylonitrile fiber by electron beam irradiation, wherein PAN precursor is put in a tray horizontally, and passes through electron beam back and forth along with track movement, the cyclization heat release amount of the irradiation modified PAN fiber is reduced, the pre-oxidation speed is accelerated, and the production cost of PAN-based carbon fiber is reduced.
Patent CN 115323529A discloses a system and a method for improving preoxidation carbonization efficiency of polyacrylonitrile-based carbon fiber precursor, which adopts electron beam irradiation to treat polyacrylonitrile fiber, realizes continuous treatment of PAN precursor irradiation and preoxidation carbonization, and effectively shortens preoxidation time.
The patents CN 108396548A, CN 108396549A and CN 111088560A all relate to large-tow polyacrylonitrile fibers treated by electron beam irradiation, and then preoxidized or thermally stabilized to obtain large-tow polyacrylonitrile preoxidized fibers, and further carbonized to obtain large-tow carbon fibers, wherein the tow specifications are mainly 46K, 72K and 48K.
However, patent CN 101798747B only relates to 3K small tow precursors, the fiber is not drawn during intermittent irradiation, and the effect of electron beam irradiation on the final carbon fiber properties is not investigated. The patent CN 115323529A mainly aims at 3K small-tow precursor, and does not mention the matching of irradiation modification, transmission device under electron beam, irradiation traction speed and carbonization filament running speed of large-tow precursor. The tensile strength of the carbon fiber reported by the patents CN 108396548A, CN 108396549A and CN 111088560A is not more than 3300MPa, and cannot reach the T300 level (tensile strength 3530 MPa), and the electron beam irradiation modification effect is poor.
Therefore, it is necessary to study electron beam irradiation technology and pre-oxidative carbonization technology of large-tow filaments.
Disclosure of Invention
The invention provides a preparation method of carbon fiber based on electron beam irradiation, and aims to solve the problems of long time consumption, high energy consumption, poor homogeneity and the like of polyacrylonitrile precursor in a preoxidation process in the prior art.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a preparation method of carbon fiber based on electron beam irradiation comprises the following steps:
winding large-tow polyacrylonitrile fibers onto two parallel guide rollers under the action of traction force to form a spiral coil, wherein the coil forms a plurality of parallel filaments in a horizontal spreading state between the two guide rollers;
the irradiation window of the electron accelerator is closely attached to the upper part of each parallel wire at intervals, and the irradiation window simultaneously covers a plurality of parallel wires;
wherein the number of monofilaments of the large-tow polyacrylonitrile fiber is greater than or equal to 24K;
starting an electron accelerator to work, and simultaneously starting traction equipment to carry out traction on the large-tow polyacrylonitrile fibers, so that each parallel fiber repeatedly passes through an irradiation window of the electron accelerator, carrying out intermittent periodic electron beam irradiation treatment in an air atmosphere, wherein the irradiation time of a single period is less than 1s, and obtaining an irradiation modified PAN precursor;
step three, continuously connecting or transferring the irradiation modified PAN precursor to a carbon fiber production line, and performing rapid pre-oxidation through a multi-temperature-zone pre-oxidation furnace at a set wire running speed to obtain an irradiation modified PAN pre-oxidized fiber;
and fourthly, sequentially carrying out low-temperature carbonization and high-temperature carbonization treatment on the irradiation modified PAN pre-oxidized fiber in a nitrogen atmosphere to obtain high-performance large-tow carbon fiber, wherein the number of monofilaments of the large-tow carbon fiber is greater than or equal to 24K.
According to a further technical scheme, the number of the large-tow polyacrylonitrile fibers and the number of the large-tow carbon monofilaments are 24K, 25K, 48K and 50K. The price of the large-tow carbon fiber is lower than that of the small-tow carbon fiber, and the large-tow carbon fiber has the advantage of low cost and is widely applied to the industrial field.
In the first step, the distance between the guide rollers at two sides is 2-4 m, and the number of turns of the coil is 10-100.
In the second step, the electron beam intensity of the irradiation treatment is 10-80 mA, the traction speed is 10-300 m/min, and the irradiation dose is 50-1000 kGy. And controlling the irradiation dose in the second step by adjusting the number of coils, the electron beam intensity and the traction speed. Specifically, the irradiation dose is proportional to the number of windings, proportional to the electron beam current intensity, and inversely proportional to the traction speed.
In a further technical scheme, in the second step, the energy of the electron accelerator is 0.6-4 MeV. The electron beam with the energy can penetrate large-tow polyacrylonitrile fibers, and irradiation uniformity is ensured.
In the second step, the irradiation window is rectangular, the width is 2-8 cm, and the width direction of the irradiation window is parallel to the axial direction of the large-tow polyacrylonitrile fiber. The length of the rectangle can completely cover the large-tow polyacrylonitrile fiber, and the irradiation effectiveness is ensured.
In the second step, the irradiation time of the intermittent periodic electron beam irradiation treatment in a single period is the width of the irradiation window divided by the traction speed; the cumulative irradiation time is the width of the irradiation window multiplied by the number of windings divided by the traction speed. The irradiation time in a single period is far less than 1s, so that the damage of electron beam irradiation to the large-tow polyacrylonitrile fiber can be avoided. The accumulated irradiation time can ensure that the electron beam irradiation technology fully plays a positive role in modifying the large-tow polyacrylonitrile fiber.
In the third step, the wire running speed is 10-30 m/min, and when the irradiation modified PAN precursor is continuously connected to the carbon fiber production line, the wire running speed is the same as the traction speed.
In the third step, the multi-temperature-zone pre-oxidation furnace comprises 4-6 temperature zones and adopts a gradient heating mode. The number of the body temperature areas can be adjusted and set according to the actual process requirements.
In the third step, the temperature of the rapid pre-oxidation is 220-260 ℃ and the time is 15-40 min; wherein the temperature of the initial temperature zone is 220-230 ℃ and the temperature of the final temperature zone is 250-260 ℃. The rapid pre-oxidation process obviously shortens the pre-oxidation time and reduces the pre-oxidation temperature, so that the energy consumption can be effectively reduced.
In the fourth step, the low-temperature carbonization temperature is 300-700 ℃ and the low-temperature carbonization time is 50-160 s; the high-temperature carbonization temperature is 1000-1500 ℃ and the time is 40-140 s.
According to a further technical scheme, the high-performance large-tow carbon fiber prepared by the method can reach the level of T300 and above, the tensile strength is more than or equal to 4200MPa, and the tensile strength discrete coefficient is less than or equal to 3%.
The working principle and the advantages of the invention are as follows:
according to the invention, the polyacrylonitrile fiber is subjected to intermittent periodic electron beam irradiation treatment, so that the irradiation time of a single period is controlled within 1s and is far smaller than the non-irradiation time, and the damage of electron beam irradiation to the structure and performance of the polyacrylonitrile fiber is avoided; through repeated rapid irradiation, the polyacrylonitrile fiber is subjected to proper crosslinking, cyclization and oxidation reaction, has a certain cyclization degree and oxygen content, and meets the requirement of subsequent rapid pre-oxidation.
According to the invention, the electron beam irradiation process of the polyacrylonitrile fiber is researched, and the irradiation dose is controlled by adjusting the number of turns, the electron beam intensity and the traction speed, so that the PAN precursor subjected to irradiation modification has good structure and performance; through optimizing the preoxidation carbonization process parameters, the aims of shortening the preoxidation time, reducing the energy consumption, improving the homogeneity and the like are fulfilled on the premise of ensuring the high performance of the carbon fiber.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention adopts intermittent periodic electron beam irradiation technology to carry out multiple rapid irradiation treatment on large-tow polyacrylonitrile fibers, can reasonably control single irradiation energy and accumulated irradiation dose, trigger PAN macromolecular chains to generate proper crosslinking, cyclization and oxidation reaction, form a certain trapezoid reticular structure, simultaneously prevent macromolecular chains from breaking caused by excessive irradiation, and avoid structural damage and performance damage of the PAN fibers caused by electron beam irradiation.
2. The irradiation modified PAN precursor provided by the invention contains higher concentration of free radicals, so that the activation energy of cyclization reaction can be reduced, the reaction speed is increased in the pre-oxidation process, the heat release amount is reduced, the pre-oxidation temperature is reduced, the concentrated heat release of large-filament precursor is alleviated, and the carbon yield is improved. The preoxidation carbonization process adopts a faster wire moving speed, reduces the effective length or the number of temperature areas of a preoxidation furnace, shortens the preoxidation time of large-tow precursor wires to 15-40 min, and prepares preoxidized wires with the density of 1.30-1.34 g/cm 3 And reduces carbonization residence time, and practically improves the production efficiency of the carbon fiber.
3. The preparation method provided by the invention can greatly reduce energy consumption, is beneficial to reducing the manufacturing cost of large-tow carbon fibers by more than 10%. In addition, the invention obtains the large-tow carbon fiber with the grade of T300 and above, the tensile strength is more than or equal to 4200MPa, and the cost performance of the product is excellent.
4. According to the invention, the oxygen element is introduced into the molecular chain of the polyacrylonitrile fiber through electron beam irradiation treatment, so that the oxygen element is diffused more fully in the pre-oxidation process, the pre-oxidation homogeneity is improved, the sheath-core structure is improved, and the large-tow carbon fiber with small discrete coefficient is produced, wherein the discrete coefficient of tensile strength, tensile modulus and elongation at break is not more than 3%.
Compared with the prior art, the method can successfully and effectively introduce the electron beam irradiation technology into the production process of the polyacrylonitrile-based carbon fiber.
Drawings
FIG. 1 is a schematic diagram of the irradiation of example 1 of the present invention.
In the above figures: 1. large tow polyacrylonitrile fibers; 2. a guide roller; 3. an electron accelerator; 4. and irradiating the window.
Description of the embodiments
The invention is further described below with reference to the accompanying drawings and examples:
the following detailed description will clearly illustrate the present invention, and it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made in the technology taught herein without departing from the spirit and scope of the present invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the terms "comprising," "including," "having," and the like are intended to be open-ended terms, meaning including, but not limited to.
The term (terms) as used herein generally has the ordinary meaning of each term as used in this field, in this disclosure, and in the special context, unless otherwise noted. Certain terms used to describe the present disclosure are discussed below, or elsewhere in this specification, to provide additional guidance to those skilled in the art in connection with the description herein.
Examples
The preparation method of the carbon fiber based on electron beam irradiation provided by the embodiment comprises the following steps:
(1) Continuously spirally winding 24K large-tow polyacrylonitrile fibers 1 (24K, 24000 monofilaments/bundles) of a bench plastic group for 50 circles along guide rollers 2 on two sides of a distance of 3m under the action of traction, repeatedly passing through an irradiation window 4 of an electron accelerator 3 in a horizontal spreading state at a traction speed of 120m/min, carrying out intermittent periodic electron beam irradiation treatment in an air atmosphere, wherein the width direction of the irradiation window is 160cm multiplied by 4cm, the electron beam energy is 1MeV, the electron beam current is 34mA, and the irradiation dose is controlled to be 180kGy to obtain irradiation modified PAN precursor;
(2) Transferring the prepared irradiation modified PAN precursor to a kiloton carbon fiber production line, performing rapid pre-oxidation by adopting a pre-oxidation furnace with six temperature areas at a filament running speed of 15m/min, wherein the pre-oxidation temperature is 220 ℃, 230 ℃, 238 ℃, 245 ℃, 250 ℃, 255 ℃ and the pre-oxidation time is 36min, and the pre-oxidation filament density is 1.322g/cm 3 And then carbonizing in nitrogen atmosphere, wherein the low-temperature carbonization temperature is 350-680 ℃ and the time is 90s, and the high-temperature carbonization temperature is 1050-1400 ℃ and the time is 70s, so as to obtain the 24K large-tow carbon fiber based on electron beam irradiation.
Through detection, the tensile strength of the 24K large-tow carbon fiber based on electron beam irradiation is 4758MPa, and the tensile strength discrete coefficient is 2.23%; the tensile modulus is 276GPa, and the tensile modulus discrete coefficient is 1.37%; the elongation at break was 1.61%, and the elongation at break dispersion coefficient was 1.76%.
Examples
The preparation method of the carbon fiber based on electron beam irradiation provided by the embodiment comprises the following steps:
(1) Continuously spirally winding 25K large-tow polyacrylonitrile fibers (25K, 25000 monofilaments/bundles) of Jilin chemical fibers for 75 circles along guide rollers at two sides with a distance of 3.5m under the action of traction force, repeatedly passing through an irradiation window of an electron accelerator in a horizontal spreading state at a traction speed of 250m/min, carrying out intermittent periodic electron beam irradiation treatment in an air atmosphere, wherein the width direction of the irradiation window is 180cm multiplied by 5cm, the electron beam energy is 1.2MeV, the electron beam current is 50mA, and the irradiation dose is controlled to 240kGy to obtain irradiation modified PAN precursor;
(2) Transferring the prepared irradiation modified PAN precursor to a kiloton carbon fiber production line, performing rapid pre-oxidation by adopting a 18m/min wire moving speed through a four-temperature-zone pre-oxidation furnace, wherein the pre-oxidation temperature is 225 ℃, 234 ℃, 244 ℃ and 250 ℃ in sequence, the pre-oxidation time is 25min, and the pre-oxidation wire density is 1.328g/cm 3 And then carbonizing in nitrogen atmosphere, wherein the low-temperature carbonization temperature is 380-700 ℃ and the time is 100s, and the high-temperature carbonization temperature is 1100-1450 ℃ and the time is 80s, so as to obtain the 25K large-tow carbon fiber based on electron beam irradiation.
Through detection, the tensile strength of the 25K large-tow carbon fiber based on electron beam irradiation is 4573MPa, and the tensile strength discrete coefficient is 2.41%; the tensile modulus is 248GPa, and the tensile modulus discrete coefficient is 0.95%; the elongation at break was 1.77%, and the elongation at break dispersion coefficient was 1.92%.
Examples
The preparation method of the carbon fiber based on electron beam irradiation provided by the embodiment comprises the following steps:
(1) Continuously spirally winding 50K large-tow polyacrylonitrile fibers (50K, i.e. 50000 monofilaments/bundles) of Jilin chemical fibers for 38 circles along guide rollers at two sides of a distance of 3m under the action of traction force, repeatedly passing through an irradiation window of an electron accelerator in a horizontal spreading state at a traction speed of 150m/min, carrying out intermittent periodic electron beam irradiation treatment in an air atmosphere, wherein the width direction of the irradiation window is 150cm multiplied by 6cm, the electron beam energy is 2MeV, the electron beam current is 75mA, and the irradiation dose is controlled to be 360kGy, so that an irradiation modified PAN precursor is obtained;
(2) Transferring the prepared irradiation modified PAN precursor to a kiloton carbon fiber production line, carrying out rapid pre-oxidation by adopting a wire moving speed of 12m/min and a four-temperature-zone pre-oxidation furnace, wherein the pre-oxidation temperature is 220 ℃, 230 ℃, 240 ℃, 250 ℃ and the pre-oxidation time is 33min, and the pre-oxidation wire density is 1.331g/cm 3 And then carbonizing in nitrogen atmosphere, wherein the low-temperature carbonization temperature is 380-700 ℃, the time is 130s, the high-temperature carbonization temperature is 1100-1500 ℃, and the time is 100s, so that the 50K large-tow carbon fiber based on electron beam irradiation is obtained.
Through detection, the tensile strength of the 50K large-tow carbon fiber based on electron beam irradiation is 4395MPa, and the tensile strength discrete coefficient is 2.65%; a tensile modulus of 244GPa, a tensile modulus discrete coefficient of 1.12%; the elongation at break was 1.74%, and the elongation at break dispersion coefficient was 1.87%.
Examples
The preparation method of the carbon fiber based on electron beam irradiation provided by the embodiment comprises the following steps:
(1) Continuously spirally winding 48K large-tow polyacrylonitrile fibers (48K, i.e. 48000 monofilaments/bundles) on both sides of a distance of 2.5m under the action of traction force for 20 circles, repeatedly passing through an irradiation window of an electron accelerator in a horizontal spreading state at a traction speed of 30m/min, carrying out intermittent periodic electron beam irradiation treatment in an air atmosphere, wherein the width direction of the irradiation window is 150cm multiplied by 6cm and is parallel to the direction of the fibers, the electron beam energy is 2.4MeV, the electron beam current is 30mA, and the irradiation dose is controlled to be 380kGy to obtain irradiation modified PAN precursor;
(2) Continuously feeding the prepared irradiation modified PAN precursor into a kiloton carbon fiber production line, rapidly pre-oxidizing at 222 ℃, 230 ℃, 239 ℃, 247 ℃ and 253 ℃ by adopting a wire feeding speed of 30m/min through a five-temperature-zone pre-oxidizing furnace,the pre-oxidation time is 20min, and the density of the pre-oxidized fiber is 1.315g/cm 3 And then carbonizing in nitrogen atmosphere, wherein the low-temperature carbonization temperature is 350-700 ℃, the time is 120s, the high-temperature carbonization temperature is 1050-1500 ℃ and the time is 90s, and the 48K large-tow carbon fiber based on electron beam irradiation is obtained.
Through detection, the tensile strength of the 48K large-tow carbon fiber based on electron beam irradiation is 4311MPa, and the tensile strength discrete coefficient is 2.78%; the tensile modulus is 240GPa, and the tensile modulus discrete coefficient is 1.44%; the elongation at break was 1.72%, and the elongation at break dispersion coefficient was 2.04%.
Comparative example 1:
the preparation method of the carbon fiber provided by the comparative example comprises the following steps:
(1) Transferring 24K large-tow polyacrylonitrile fibers (24K, 24000 monofilaments/bundles) of bench plastic groups onto a kiloton carbon fiber production line, performing rapid pre-oxidation at a filament speed of 15m/min by a six-temperature-zone pre-oxidation furnace, wherein the pre-oxidation temperature is 220 ℃, 230 ℃, 238 ℃, 245 ℃, 250 ℃, 255 ℃, the pre-oxidation time is 36min, and the pre-oxidation filament density is 1.282g/cm 3 And then carbonizing in nitrogen atmosphere, wherein the low-temperature carbonization temperature is 350-680 ℃ for 90s, and the high-temperature carbonization temperature is 1050-1400 ℃ for 70s, so as to obtain the 24K large-tow carbon fiber.
The difference between this comparative example and example 1 is that: the 24K large tow polyacrylonitrile fiber of the bench plastic group was not subjected to electron beam irradiation treatment, and carbon fiber preparation conditions and process parameters were the same as in example 1.
The detection shows that the tensile strength of the 24K large-tow carbon fiber is 3365MPa, and the discrete coefficient of the tensile strength is 4.48%; a tensile modulus of 228GPa and a tensile modulus discrete coefficient of 2.76%; the elongation at break was 1.48%, and the elongation at break dispersion coefficient was 3.92%.
As can be seen from the comparative analysis of example 1 and comparative example 1, the mechanical properties of the large-tow carbon fiber prepared under the same preoxidation carbonization process condition are better after the large-tow polyacrylonitrile precursor is subjected to electron beam irradiation treatment, namely, the mechanical properties of the carbon fiber can be improved by adopting an electron beam irradiation technology.
Comparative example 2:
the carbon fiber preparation method based on electron beam irradiation provided in this comparative example is different from example 2 in that the traction speed is 100m/min, the electron beam current is 100mA, the irradiation dose is 1200kGy, and other preparation methods and process parameters are the same as those of example 2.
Through detection, the tensile strength of the 25K large-tow carbon fiber based on electron beam irradiation is 3247MPa, and the tensile strength discrete coefficient is 4.12%; a tensile modulus of 221GPa and a tensile modulus discrete coefficient of 2.67%; the elongation at break was 1.47%, and the elongation at break dispersion coefficient was 4.43%.
As can be seen from the comparative analysis of example 2 and comparative example 2, an excessive irradiation dose during the electron beam irradiation treatment causes a decrease in mechanical properties of the large-tow carbon fiber, and thus it is necessary to control the irradiation dose within a reasonable range.
The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.

Claims (10)

1. A preparation method of carbon fiber based on electron beam irradiation is characterized by comprising the following steps: comprising the following steps:
winding large-tow polyacrylonitrile fibers onto two parallel guide rollers under the action of traction force to form a spiral coil, wherein the coil forms a plurality of parallel filaments in a horizontal spreading state between the two guide rollers;
the irradiation window of the electron accelerator is closely attached to the upper part of each parallel wire at intervals, and the irradiation window simultaneously covers a plurality of parallel wires;
wherein the number of monofilaments of the large-tow polyacrylonitrile fiber is greater than or equal to 24K;
starting an electron accelerator to work, and simultaneously starting traction equipment to carry out traction on the large-tow polyacrylonitrile fibers, so that each parallel fiber repeatedly passes through an irradiation window of the electron accelerator, carrying out intermittent periodic electron beam irradiation treatment in an air atmosphere, wherein the irradiation time of a single period is less than 1s, and obtaining an irradiation modified PAN precursor;
step three, continuously connecting or transferring the irradiation modified PAN precursor to a carbon fiber production line, and performing rapid pre-oxidation through a multi-temperature-zone pre-oxidation furnace at a set wire running speed to obtain an irradiation modified PAN pre-oxidized fiber;
and fourthly, sequentially carrying out low-temperature carbonization and high-temperature carbonization treatment on the irradiation modified PAN pre-oxidized fiber in a nitrogen atmosphere to obtain high-performance large-tow carbon fiber, wherein the number of monofilaments of the large-tow carbon fiber is greater than or equal to 24K.
2. The method for producing a carbon fiber according to claim 1, wherein: in the first step, the distance between the guide rollers at two sides is 2-4 m; the number of turns of the coil is 10-100.
3. The method for producing a carbon fiber according to claim 2, wherein: in the second step, the intensity of the electron beam current of the irradiation treatment is 10-80 mA, the traction speed is 10-300 m/min, and the irradiation dose is 50-1000 kGy.
4. The method for producing a carbon fiber according to claim 1, wherein: in the second step, the energy of the electron accelerator is 0.6-4 MeV.
5. The method for producing a carbon fiber according to claim 1, wherein: in the second step, the irradiation window is rectangular, the width is 2-8 cm, and the width direction of the irradiation window is parallel to the axial direction of the large-tow polyacrylonitrile fiber.
6. The method for producing a carbon fiber according to claim 1, wherein: in the second step, the irradiation time of the intermittent periodic electron beam irradiation treatment in a single period is the width of the irradiation window divided by the traction speed; the cumulative irradiation time is the width of the irradiation window multiplied by the number of windings divided by the traction speed.
7. The method for producing a carbon fiber according to claim 1, wherein: in the third step, the wire running speed is 10-30 m/min, and when the irradiation modified PAN precursor is continuously connected into the carbon fiber production line, the wire running speed is the same as the traction speed.
8. The method for producing a carbon fiber according to claim 1, wherein: in the third step, the multi-temperature-zone pre-oxidation furnace comprises 4-6 temperature zones, and a gradient heating mode is adopted.
9. The method for producing a carbon fiber according to claim 1, wherein: in the third step, the temperature of the rapid pre-oxidation is 220-260 ℃ and the time is 15-40 min; wherein the temperature of the initial temperature zone is 220-230 ℃ and the temperature of the final temperature zone is 250-260 ℃.
10. The method for producing a carbon fiber according to claim 1, wherein: in the fourth step, the low-temperature carbonization temperature is 300-700 ℃ and the time is 50-160 s; the high-temperature carbonization temperature is 1000-1500 ℃ and the time is 40-140 s.
CN202310899340.1A 2023-07-21 2023-07-21 Preparation method of carbon fiber based on electron beam irradiation Pending CN116949605A (en)

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