A preparation method and application of high-strength and high-modulus carbon fiber precursor

Abstract

The present invention relates to a method for preparing a high-strength and high-modulus carbon fiber precursor, which mainly solves the problem that the carbon fiber in the prior art is easy to fluff and has low fiber modulus during graphitization treatment. The preparation method provided by the present invention includes a step of hot water drawing, wherein the hot water drawing comprises at least two stages, and the last stage of hot water drawing gradually heats up to a temperature T; the fiber has a groove tension at the last stage of hot water drawing temperature T of 0.7 to 1.1 times the tension after leaving the groove, and the fiber has a groove tension at the last stage of drawing groove temperature T of 0.3 to 0.5 times the groove tension at the last stage of groove temperature T-20°C, which solves the problem well, has the characteristics of not easy to fluff and high fiber modulus during graphitization treatment, and can be used in the industrial production of high-strength and high-modulus carbon fiber precursor.

Description

Technical Field

[0001] The invention belongs to the field of carbon fiber precursor preparation, and specifically relates to a preparation method and application of high-strength and high-modulus carbon fiber precursor. Background Art

[0002] Carbon fiber is an inorganic polymer fiber with more than 90% carbon fiber. It has the characteristics of high strength, high modulus, acid and alkali resistance, corrosion resistance, etc. It is widely used in aerospace, transportation rail, new energy and other fields. It is an important material basis for the development of the national economy.

[0003] Carbon fiber can be divided into polyacrylonitrile-based, asphalt-based and viscose-based according to the source of raw materials. Polyacrylonitrile-based carbon fiber has the advantages of good comprehensive mechanical properties and easy access to raw materials. Its production capacity accounts for more than 95% of the total carbon fiber production capacity and is the main component of carbon fiber.

[0004] Carbon fiber can be divided into general type, high-strength medium model, high model and high-strength high model according to mechanical properties, and can be divided into large tow (single bundle of carbon fiber contains 48,000 or more carbon fibers) and small tow according to the number of tows. High-strength and high-model carbon fiber, that is, high-strength and high-modulus carbon fiber, refers to carbon fiber with a modulus greater than 350GPa and a strength greater than 3.5GPa, which is widely used in aerospace and high-end civilian fields.

[0005] The preparation of high-strength and high-modulus polyacrylonitrile-based carbon fibers mainly includes three processes: stock solution preparation, precursor preparation, and oxidation carbonization. The preparation of the polymerization stock solution is divided into a one-step method and a two-step method. The one-step method uses homogeneous solution polymerization, and the solvent can be an organic solvent or an inorganic solvent; the two-step method uses heterogeneous solution polymerization to obtain a polymer, which is then separated, dried, and dissolved in a solvent to obtain. Among them, the one-step method has the advantages of high solid content and high economy and has been widely used. Polyacrylonitrile fibers can be divided into wet spinning and dry-jet wet spinning according to the spinning method. Among them, the fibers prepared by wet spinning have a clear groove structure, and the prepared carbon fibers have a clear groove surface structure, and have a good "carbon fiber-resin" bonding ability when used as a composite material. Usually, the precursors of high-strength and high-modulus carbon fibers are all made by wet spinning.

[0006] There are many solvent systems for preparing polyacrylonitrile precursor by one-step wet spinning. Currently, the sodium thiocyanate system and dimethyl sulfoxide system have been put into industrial production. Among them, dimethyl sulfoxide is used as a solvent to prepare polyacrylonitrile-based carbon fiber precursor. It has the characteristics of low toxicity and high solubility of polyacrylonitrile copolymer in the solvent. It is an important method for preparing polyacrylonitrile fiber by wet spinning.

[0007] One-step wet spinning of dimethyl sulfoxide stock solution usually includes coagulation, washing, hot water drawing, oiling, drying and densification, steam drawing, steam heat setting and collection. In the spinning process, the whole process involves drawing, which is an important driving force for the change of fiber crystal microstructure. There are three main stages of drawing in the spinning process, the initial drawing in the coagulation process, the first-level drawing in hot water and the second-level drawing in the steam drawing machine. Fiber fine denier is the basis for the preparation of high-strength and high-modulus carbon fiber precursor. Hot water drawing and steam drawing in the three stages are the main ways to achieve fine denier of precursor.

[0008] Hot water drawing usually uses a multi-stage series drawing device. As the drawing process increases, the fiber fineness decreases. However, in order to maintain the fiber structure and further increase the orientation of the fiber, moderate tension is gradually applied during the process. As the number of drawing stages increases, the tension on the fiber gradually increases. The uniaxial drawing force during hot water drawing causes the fiber fibrils to deform and the micropores in the fiber to change. The uniaxial drawing force during hot water drawing is an important parameter for measuring the drawing process. When the tension is too large, some molecular chains of the fiber will break, making it impossible for the fiber to be drawn by steam; when the tension is too small, the fiber orientation is insufficient, and the filaments will appear white and wet after drying and densification. High-strength and high-modulus carbon fiber precursors have higher requirements in the preparation process.

[0009] Japanese patents JP1983214526A and JP2004076208A disclose a method for preparing a polyacrylonitrile-based carbon fiber precursor, which adopts a wet spinning method. The patent only discloses the tension of the nascent fiber, and does not disclose the reasonable ratio range of the tension in the bath and outside the bath. Chinese patent CN111088531A discloses a method for preparing a high-strength medium-modulus polyacrylonitrile-based carbon fiber precursor. The technical problem solved is that the high-strength medium-modulus carbon fiber precursor is prone to produce hair, and the prepared high-strength medium-modulus carbon fiber has poor mechanical properties. The prepared carbon fiber modulus is less than 350GPa. Compared with high-strength medium-modulus carbon fiber, the amount of hair in the graphitization treatment of high-strength and high-modulus carbon fiber is relatively large, which is easy to cause production shutdown. How to solve the hair problem in the preparation process of high-strength and high-modulus carbon fiber is a core key issue. However, none of the above patents have proposed a solution. Summary of the invention

[0010] The present invention aims to solve the problems in the prior art that carbon fibers are prone to fuzzing and have low fiber modulus during graphitization treatment, and provides a method for preparing high-strength and high-modulus carbon fiber precursor. The method adopts at least two-stage hot water drawing and controls the tension of the fibers during the hot water drawing process to prepare the high-strength and high-modulus carbon fiber precursor. The carbon fibers prepared by using the carbon fiber precursor as raw materials are not prone to fuzzing during graphitization treatment and have high fiber modulus.

[0011] One of the purposes of the present invention is to provide a method for preparing high-strength and high-modulus carbon fiber precursor, comprising wet spinning, coagulation drawing, and hot water drawing, wherein the hot water drawing comprises at least two stages, and the last stage of hot water drawing gradually heats up to a temperature T; the fiber tension in the tank at the last stage of hot water drawing temperature T is 0.7 to 1.1 times the tension after leaving the tank, and the fiber tension leaving the tank at the last stage of drawing tank temperature T is 0.3 to 0.5 times the tension leaving the tank at the last stage of drawing tank temperature T-20°C;

[0012] Preferably,

[0013] In the last stage of hot water drawing, the fiber tension in the tank at the last stage of hot water drawing temperature T is 0.8 to 1.0 times the tension after leaving the tank, and the fiber tension leaving the tank at the last stage of drawing tank temperature T is 0.3 to 0.4 times the tension leaving the tank at the last stage of drawing tank temperature T-20°C;

[0014] The fiber's tension when leaving the last drafting tank at a temperature of T is controlled by spraying hot water or supersaturated steam, etc. Preferably, the temperature of the sprayed hot water or supersaturated steam is 60-80°C; the fiber's tension when leaving the last drafting tank at a temperature of T-20°C is the tension directly measured after the fiber leaves the tank at T-20°C, that is, the tension when leaving the tank without additional temperature control in air at room temperature;

[0015] The hot water drawing is 2 to 4 levels;

[0016] The temperature T of the last stage of hot water drawing is 80-95°C;

[0017] The last stage hot water drawing ratio is 1.5 to 3.0.

[0018] More specifically, the preparation method provided by the present invention comprises extruding the spinning solution through a spinneret, forming in a coagulation bath, coagulation drawing, hot water drawing, water washing, oiling once, drying and densification, steam drawing, and collecting to obtain the high-strength and high-modulus carbon fiber precursor.

[0019] In the above preparation method,

[0020] The spinneret extrusion can be operated using commonly used process conditions. Preferably, the number of holes in the spinneret is 1000 to 6000 holes; the spinneret extrusion temperature is 30 to 60° C., preferably 50 to 60° C.;

[0021] The coagulation bath molding is a commonly used technical process in the art. Preferably, the medium of the coagulation bath is a mixed solvent of water and a polar aprotic solvent, and the polar aprotic solvent is preferably at least one selected from dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide; the process kit such as the medium concentration in the coagulation bath, the coagulation bath temperature, and the coagulation draw ratio can be set according to the selected medium according to the commonly used process in the art.

[0022] In the preparation method provided by the present invention, the hot water drawing comprises at least two stages, preferably 2 to 4 stages. The hot water drawing before the last stage can adopt the hot water drawing conditions in the prior art, such as a drawing temperature of 60 to 95°C and a drawing ratio of 1.2 to 2; the last stage of hot water drawing gradually heats up to a temperature T, preferably from room temperature to T, with a heating rate of 2 to 6°C / min, a temperature T of the last stage of hot water drawing of 80 to 95°C, and a hot water drawing ratio of 1.5 to 3.0.

[0023] Wherein, during the last stage of hot water drawing, the fiber tension in the tank at temperature T is 0.7 to 1.1 times the tension after leaving the tank, and the fiber tension leaving the tank at the last stage of drawing tank temperature T is 0.3 to 0.5 times the tension leaving the tank at the last stage of tank temperature T-20°C; preferably, the fiber tension in the tank at temperature T is 0.8 to 1.0 times the tension after leaving the tank, and the fiber tension leaving the tank at the last stage of drawing tank temperature T is 0.3 to 0.4 times the tension leaving the tank at the last stage of tank temperature T-20°C;

[0024] The temperature T of the last stage of hot water drawing in the hot water drawing is 80-95°C;

[0025] The last hot water drawing ratio in the hot water drawing is 1.5 to 3.0;

[0026] In the hot water drawing, the fiber tension at the last drawing tank temperature T is controlled by spraying hot water or supersaturated steam. Preferably, the temperature of the spraying hot water or supersaturated steam is 60-80°C.

[0027] In the preparation method provided by the present invention:

[0028] The water washing temperature is 50-70°C, and the draft ratio is 1.0-1.05;

[0029] The oiling temperature is 15-25°C, preferably 15-20°C;

[0030] The drying and densification is performed in at least 2 steps;

[0031] The drying and densification temperature is 100-160°C;

[0032] The drafting ratio of the steam drafting is 2.0 to 3.0.

[0033] The second object of the present invention is to provide a high-strength and high-modulus carbon fiber prepared from the above-mentioned high-strength and high-modulus carbon fiber precursor.

[0034] The third object of the present invention is to provide a method for preparing the above-mentioned high-strength and high-modulus carbon fiber, comprising pre-oxidizing, carbonizing, graphitizing and post-treating the high-strength and high-modulus carbon fiber precursor obtained by steam drawing to obtain the high-strength and high-modulus carbon fiber.

[0035] Wherein, the pre-oxidation temperature is 180-260°C, and the pre-oxidation draft ratio is 0.95-1.1;

[0036] The carbonization includes low-temperature carbonization and high-temperature carbonization; wherein the low-temperature carbonization temperature is 300-750°C, and the low-temperature carbonization draw ratio is 1.05-1.15, preferably 1.05-1.1; the high-temperature carbonization temperature is 800-1500°C, and the high-temperature carbonization draw ratio is 0.95-1.05, preferably 0.97-1.02;

[0037] The graphitization temperature is 2200-3000°C, preferably 2500-2800°C;

[0038] The post-treatment includes surface treatment, washing, sizing, drying and collecting, wherein the surface treatment, washing, sizing, drying and other processes are all completed by the commonly used processes in the art.

[0039] During the hot water drawing process, the tow is immersed in hot water and is drawn out by the drawing machine after drawing. After the tow is drawn out, it will travel in the air for a period of time, the temperature will decrease, the fiber will shrink, the tension will increase, and excessive tension can cause the molecular chain inside the fiber to break. Therefore, it is necessary to reasonably control the ratio of the tension of the tow in the drawing tank to the tension of the tow after the tow leaves the tank to avoid excessive changes in the tension value and damage to the fiber. In the multi-stage hot water drawing process, the last stage of hot water drawing is the last stage of fiber drawing, and usually the drawing multiple is the largest. It plays a vital role in the formation of subsequent fiber structure and whether subsequent drawing can be carried out. Therefore, it is particularly important to control the ratio of fiber tension in the hot water tank during the last hot water drawing process and after leaving the hot water tank, which can improve the process stability and fiber modulus of preparing high-strength and high-modulus fibers using the above-mentioned raw silk after hot water drawing.

[0040] In the hot water drawing process, the present invention controls the temperature of the last stage of hot water drawing to gradually rise, and tests the fiber's groove tension when the temperature reaches T-20°C, and then tests the fiber's groove tension at temperature T, and adjusts the groove tension by means of spraying hot water, supersaturated water vapor or adjusting the drawing ratio, so that the fiber's groove tension at the last stage of hot water drawing temperature T is 0.7 to 1.1 times the tension after the groove, and the fiber's groove tension at the last stage of drawing groove temperature T is 0.3 to 0.5 times the groove tension at the last stage of groove temperature T-20°C. The fiber obtained by the above process is subjected to subsequent treatment processes such as water washing, oiling, drying and densification, and steam drawing to obtain the high-strength and high-modulus carbon fiber precursor.

[0041] In the preparation method provided by the present invention, the last hot water drawing has a significant effect on the graphitization treatment process in the preparation of high-strength and high-modulus carbon fiber using high-strength and high-modulus carbon fiber precursor as raw material, which can alleviate the generation of hair in the process while taking into account the high modulus characteristics of the prepared high-strength and high-modulus carbon fiber.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention avoids the damage of the fiber microstructure caused by excessive tension change by controlling the tension in the last hot water drawing tank to the ratio range of the tension after the fiber leaves the tank;

[0044] 2. The present invention controls the range of the tension value of the fiber after leaving the drawing tank at the temperature T in the drawing tank and the tension value of the fiber leaving the tank at the temperature T-20°C in the tank, thereby avoiding excessive changes in the tension value and causing damage to the inside of the fiber;

[0045] 3. The present invention also selects a tension control method after the fiber leaves the groove: spraying hot water or supersaturated steam, and determining its appropriate temperature range, thereby avoiding energy consumption and deorientation caused by excessively high temperature or poor tension adjustment effect at low temperature. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0047] The test instruments and test conditions used in the examples are as follows:

[0048] The tension of the yarn bundle in the hot water drawing tank is obtained by measuring the tension of the yarn bundle traveling in the last level hot water drawing bath with a handheld tension meter, measuring 10 times each time and taking the average value; the tension value of the yarn bundle after leaving the tank is obtained by measuring the tension of the yarn bundle traveling between the two rollers at the outlet of the hot water drawing tank with a handheld tension meter, measuring 10 times each time and taking the average value.

[0049] The filaments of the tow during the graphitization process were obtained by counting the number of filaments per hour using an online camera.

[0050] The carbon fiber modulus is measured using GB / T 3362-2017.

[0051] The sources of the raw materials used in the examples are as follows:

[0052] Preparation of spinning solution:

[0053] The distilled acrylonitrile (AN) and itaconic acid (IA) were added into a reactor in a ratio of 99.4:0.6, with a solid content of 20%, azobisisobutyronitrile (AIBN) accounting for 0.4wt% of the comonomer, and dimethyl sulfoxide (DMSO) as a solvent, and reacted at a constant temperature of 59°C for 20 hours under nitrogen protection to obtain a binary acrylonitrile copolymer spinning solution. Then, the spinning solution was decompressed to remove residual monomers and bubbles, and then filtered through a 5μm filter material to obtain an acrylonitrile copolymer spinning solution.

[0054] Other raw materials in the examples are all commercially available products.

[0055] [Example 1]

[0056] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, the stock solution (spinning stock solution solid content 22%) is ejected, the spinning temperature is 60°C, the spinning speed is 10 m / min, and then the solidification is carried out through the first coagulation bath with the coagulation bath medium being a dimethyl sulfoxide aqueous solution, and then the three-stage coagulation drawing temperature is 60°C; 3-stage hot water drawing is adopted, and the drawing temperatures are 70°C, 80°C, and 90°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, and the third hot water drawing is gradually heated from room temperature to 90°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 2.2 times; when the temperature of the third hot water drawing reaches 70°C, it is directly measured The tension of the fiber at room temperature after leaving the tank; when the temperature of the third hot water drawing reaches 90℃, 76℃ hot water is rinsed on the fiber after the fiber leaves the third hot water drawing tank; it is measured that the tension in the third hot water drawing tank at 90℃ is 0.8 times the tension of the fiber after leaving the tank, and the tension value of the fiber when leaving the third drawing tank at 90℃ is 0.3 times the tension value of the fiber leaving the tank at 70℃; the washing temperature is gradually increased from 60℃ to 75℃, and the total drawing ratio is 1.02; after oiling at 20℃, it is dried and densified, and the drying and densification adopts 2 levels, with temperatures of 120℃ and 130℃ respectively; saturated steam is used, the steam pressure is 0.3MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0057] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature carbonization at 300-750°C and a draft ratio of 1.07; perform high-temperature carbonization at 800-1500°C and a draft ratio of 0.985; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0058] According to statistics from online cameras, the average number of hair fibers in the graphitization furnace outlet per hour is 10, the carbon fiber modulus is 550 GPa, and the tensile strength is 4.16 GPa.

[0059] [Example 2]

[0060] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, the stock solution is sprayed out, the spinning temperature is 60°C, the spinning speed is 10 m / min, and then coagulated in the first coagulation bath with a coagulation bath medium of dimethyl sulfoxide aqueous solution, and then subjected to three-stage coagulation drawing, all at a temperature of 60°C; 3-stage hot water drawing is used, and the drawing temperatures are 70°C, 80°C, and 90°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, and the third hot water drawing is gradually heated from room temperature to 90°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 2.2 times; when the temperature of the third hot water drawing reaches 70°C, the fiber leaving the slot is directly measured the tension at room temperature after the third hot water drawing; when the temperature of the third hot water drawing reaches 90℃, after the fiber leaves the third hot water drawing tank, 80℃ hot water is rinsed on the fiber; it is measured that the tension in the third hot water drawing tank at 90℃ is 1.0 times the tension of the fiber after leaving the tank, and the fiber leaving the tank tension value at 90℃ in the third drawing tank is 0.3 times the fiber leaving the tank tension value at 70℃; the water washing temperature is gradually increased from 60℃ to 75℃, and the total drawing ratio is 1.02; after oiling at 20℃, it is dried and densified, and the drying and densification adopts 2 levels, with temperatures of 120℃ and 130℃ respectively; saturated steam is used, the steam pressure is 0.3MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0061] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature and high-temperature carbonization at 300-750°C and 800-1500°C, respectively; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0062] According to statistics from online cameras, the average number of filaments in the fibers at the exit of the graphitization furnace per hour is 8, the carbon fiber modulus is 548 GPa, and the tensile strength is 4.18 GPa.

[0063] [Example 3]

[0064] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, the stock solution is sprayed out, the spinning temperature is 60°C, the spinning speed is 10 m / min, and then coagulated in the first coagulation bath with a coagulation bath medium of dimethyl sulfoxide aqueous solution, and then subjected to three-stage coagulation drawing, the temperature of which is 60°C; 3-stage hot water drawing is adopted, and the drawing temperatures are 70°C, 80°C, and 85°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, and the third hot water drawing is gradually heated from room temperature to 85°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 1.9 times; when the temperature of the third hot water drawing reaches 65°C, the fiber is directly measured after leaving the slot tension at room temperature; when the temperature of the third hot water drawing reaches 85°C, after the fiber leaves the third hot water drawing tank, 80°C hot water is rinsed on the fiber; it is measured that the in-tank tension of the third hot water drawing tank at 85°C is 1.1 times the tension of the fiber after leaving the tank, and the fiber leaving the tank tension value at 85°C in the third drawing tank is 0.5 times the fiber leaving the tank tension value at 65°C; the washing temperature is gradually increased from 60°C to 75°C, and the total drawing ratio is 1.02; after oiling at 20°C, drying and densification treatment is carried out, and the drying and densification adopts 2 levels, and the temperatures are 120°C and 130°C respectively; saturated steam is used, the steam pressure is 0.3MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0065] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature and high-temperature carbonization at 300-750°C and 800-1500°C, respectively; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0066] According to statistics from online cameras, the average number of filaments in the fibers at the exit of the graphitization furnace per hour is 6, the carbon fiber modulus is 540 GPa, and the tensile strength is 4.2 GPa.

[0067] [Example 4]

[0068] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, the stock solution is sprayed out, the spinning temperature is 60°C, the spinning speed is 10 m / min, and then coagulated in the first coagulation bath with a coagulation bath medium of dimethyl sulfoxide aqueous solution, and then subjected to three-stage coagulation drawing, the temperature of which is 60°C; 3-stage hot water drawing is adopted, and the drawing temperatures are 70°C, 80°C, and 87°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, and the third hot water drawing is gradually heated from room temperature to 87°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 2.1 times; when the temperature of the third hot water drawing reaches 67°C, the fiber is directly measured to be in the room temperature after leaving the slot. the tension at temperature; when the temperature of the third hot water drawing reaches 87°C, after the fiber leaves the third hot water drawing tank, 70°C hot water is rinsed on the fiber; it is measured that the in-tank tension of the third hot water drawing tank at 87°C is 0.9 times the tension of the fiber after leaving the tank, and the fiber leaving the tank tension value at 87°C in the third drawing tank is 0.35 times the fiber leaving the tank tension value at 67°C; the washing temperature is gradually increased from 60°C to 75°C, and the total drawing ratio is 1.02; after oiling at 20°C, drying and densification treatment is carried out, and the drying and densification adopts 2 levels, and the temperatures are 120°C and 130°C respectively; saturated steam is used, the steam pressure is 0.3MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0069] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature and high-temperature carbonization at 300-750°C and 800-1500°C, respectively; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0070] According to statistics from online cameras, the average number of filaments in the fibers at the exit of the graphitization furnace per hour is 12, the carbon fiber modulus is 560 GPa, and the tensile strength is 4.07 GPa.

[0071] [Example 5]

[0072] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, spraying out the stock solution, spinning temperature of 60°C, spinning speed of 10 m / min, and then coagulating in the first coagulation bath with a coagulation bath medium of dimethyl sulfoxide aqueous solution, and then undergoing three-stage coagulation drawing, all at a temperature of 60°C; using 3-stage hot water drawing, the drawing temperatures are 70°C, 80°C, and 87°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, and the third hot water drawing gradually heats up from room temperature to 87°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 2.1 times; when the temperature of the third hot water drawing reaches 67°C, the tension of the fiber at room temperature after leaving the tank is directly measured; when When the temperature of the third hot water drawing reaches 87°C, after the fiber leaves the third hot water drawing tank, saturated water vapor at 67°C is introduced into the closed hot water drawing roller cover; the measured tension in the third hot water drawing tank at 87°C is 0.95 times the tension of the fiber after leaving the tank, and the fiber leaving the tank tension value at 87°C in the third drawing tank is 0.35 times the fiber leaving the tank tension value at 67°C; the washing temperature is gradually increased from 60°C to 75°C, and the total drawing ratio is 1.02; after oiling at 20°C, drying and densification treatment is carried out, and the drying and densification adopts 2 levels, and the temperatures are 120°C and 130°C respectively; saturated steam is used, the steam pressure is 0.4MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0073] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature and high-temperature carbonization at 300-750°C and 800-1500°C, respectively; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0074] According to statistics from online cameras, the average number of hair fibers in the graphitization furnace outlet per hour is 15, the carbon fiber modulus is 540 GPa, and the tensile strength is 4.19 GPa.

[0075] [Comparative Example 1]

[0076] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, the stock solution is ejected, the spinning temperature is 60°C, the spinning speed is 10 m / min, and then coagulated in the first coagulation bath with a coagulation bath medium of dimethyl sulfoxide aqueous solution, and then subjected to three-stage coagulation drawing, all at a temperature of 60°C; 3-stage hot water drawing, the drawing temperatures are 70°C, 80°C, and 90°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, the third hot water drawing gradually heats up from room temperature to 90°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 2.2 times; when the temperature of the third hot water drawing reaches 7 The tension of the fiber at room temperature after leaving the trough is directly measured at 0℃; when the temperature of the third hot water drawing reaches 90℃, the tension in the third hot water drawing trough at 90℃ is measured to be 0.5 times the tension of the fiber after leaving the trough, and the fiber leaving the trough tension value at 90℃ in the third drawing trough is 0.25 times the fiber leaving the trough tension value at 70℃; the washing temperature is gradually increased from 60℃ to 75℃, and the total drawing ratio is 1.02; after oiling at 20℃, it is dried and densified, and the drying and densification adopts 2 levels, with temperatures of 120℃ and 130℃ respectively; saturated steam is used, the steam pressure is 0.3MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0077] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature and high-temperature carbonization at 300-750°C and 800-1500°C, respectively; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0078] According to statistics from online cameras, the average number of hair fibers in the graphitization furnace outlet per hour is 20, the carbon fiber modulus is 480 GPa, and the tensile strength is 4.05 GPa.

[0079] [Comparative Example 2]

[0080] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, the stock solution is sprayed out, the spinning temperature is 60°C, the spinning speed is 10 m / min, and then coagulated in the first coagulation bath with a coagulation bath medium of dimethyl sulfoxide aqueous solution, and then subjected to three-stage coagulation drawing, the temperature is 60°C; 3-stage hot water drawing is adopted, the drawing temperatures are 70°C, 80°C, and 90°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, the third hot water drawing is gradually heated from room temperature to 90°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 2.2 times; when the temperature of the third hot water drawing reaches 70°C, the fiber is directly measured after leaving the groove. the tension at temperature; when the temperature of the third hot water drawing reaches 90℃, after the fiber leaves the third hot water drawing tank, 90℃ hot water is rinsed on the fiber; it is measured that the tension in the third hot water drawing tank at 90℃ is 1.2 times the tension of the fiber after leaving the tank, and the fiber leaving the tank tension value at 90℃ in the third drawing tank is 0.35 times the fiber leaving the tank tension value at 75℃; the washing temperature is gradually increased from 60℃ to 75℃, and the total drawing ratio is 1.02; after oiling at 20℃, it is dried and densified, and the drying and densification adopts 2 levels, with temperatures of 120℃ and 130℃ respectively; saturated steam is used, the steam pressure is 0.3MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0081] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature and high-temperature carbonization at 300-750°C and 800-1500°C, respectively; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0082] According to statistics from online cameras, the average number of hair fibers in the graphitization furnace outlet per hour is 17, the carbon fiber modulus is 490 GPa, and the tensile strength is 3.97 GPa.

[0083] [Comparative Example 3]

[0084] 1. Preparation of high-strength and high-modulus carbon fiber precursor, using a 6000-hole spinneret with a spinneret aperture of 58 μm, spraying out the stock solution, spinning temperature of 60°C, spinning speed of 10 m / min, and then coagulating in the first coagulation bath with a coagulation bath medium of dimethyl sulfoxide aqueous solution, and then undergoing three-stage coagulation drawing, all at a temperature of 60°C; using 3-stage hot water drawing, the drawing temperatures are 70°C, 75°C, and 80°C, respectively, wherein the drawing ratios of the first and second hot water drawing are 1.2 and 1.3, respectively, and the third hot water drawing gradually heats up to 80°C, the heating rate is 5°C / min, and the third hot water drawing ratio is 2.1 times; when the temperature of the third hot water drawing reaches 60°C, the tension of the fiber at room temperature after leaving the tank is directly measured; when When the temperature of the third hot water drawing reaches 80°C, after the fiber leaves the third hot water drawing tank, saturated water vapor at 95°C is introduced into the closed hot water drawing roller cover; it is measured that the tension in the third hot water drawing tank at 80°C is 1.3 times the tension of the fiber after leaving the tank, and the fiber leaving the tank tension value at 80°C in the third drawing tank is 0.6 times the fiber leaving the tank tension value at 67°C; the washing temperature is gradually increased from 60°C to 75°C, and the total drawing ratio is 1.02; after oiling at 20°C, drying and densification treatment is carried out, and the drying and densification adopts 2 levels, and the temperatures are 120°C and 130°C respectively; saturated steam is used, the steam pressure is 0.3MPa, and the steam drawing ratio is 2.9 times, and high-strength and high-modulus carbon fiber precursor is obtained after drawing.

[0085] 2. Preparation of high-strength and high-modulus carbon fiber: pre-oxidize the raw silk obtained in step 1 at 180-260°C, with a total pre-oxidation draft ratio of 1.08 times to obtain pre-oxidized fiber; then perform low-temperature and high-temperature carbonization at 300-750°C and 800-1500°C, respectively; then perform graphitization at 2800°C, and finally obtain high-strength and high-modulus carbon fiber after surface treatment, water washing, sizing, drying and wire collection.

[0086] According to statistics from online cameras, the average number of filaments in the fibers at the exit of the graphitization furnace per hour is 25, the carbon fiber modulus is 470 GPa, and the tensile strength is 4.1 GPa.

[0087] It can be seen from the carbon fibers obtained from the above embodiments and comparative examples that the carbon fibers obtained by adopting the technical solution of the present invention have a minimum of 6 hair fibers per hour at the graphitization furnace outlet through online camera statistics, and the carbon fiber modulus can reach 560 GPa, achieving good technical results.

Claims

1. A method for preparing high-strength and high-modulus carbon fiber precursor, comprising wet spinning, coagulation drawing, and hot water drawing, wherein the hot water drawing comprises at least two stages, and the last stage of hot water drawing gradually heats up to a temperature T; the fiber tension in the tank at the last stage of hot water drawing temperature T is 0.7 to 1.1 times the tension after leaving the tank, and the fiber tension leaving the tank at the last stage of drawing tank temperature T is 0.3 to 0.5 times the tension leaving the tank at the last stage of tank temperature T-20°C; the fiber tension leaving the tank at the last stage of drawing tank temperature T is controlled by spraying hot water or supersaturated water vapor.

2. The preparation method according to claim 1, characterized in that: In the last stage of hot water drawing, the fiber tension in the tank at the last stage of hot water drawing temperature T is 0.8-1.0 times the tension after leaving the tank, and the fiber tension leaving the tank at the last stage of drawing tank temperature T is 0.3-0.4 times the tension leaving the tank at the last stage of tank temperature T-20°C.

3. The preparation method according to claim 1, characterized in that: The hot water drawing is level 2 to 4; and / or, The temperature T of the last stage of hot water drawing is 80-95°C; and / or, The last stage hot water drawing ratio is 1.5-3.

0.

4. The preparation method according to claim 1, characterized in that: The temperature of the sprayed hot water or supersaturated steam is 60-80°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The preparation method specifically comprises extruding the spinning solution through a spinneret, forming in a coagulation bath, coagulation drawing, hot water drawing, water washing, oiling once, drying and densification, steam drawing, and collecting to obtain the high-strength and high-modulus carbon fiber precursor.

6. The preparation method according to claim 5, characterized in that: The number of holes of the spinneret is 1000 to 6000; and / or, The spinneret extrusion temperature is 30-60°C.

7. The preparation method according to claim 6, characterized in that: The spinneret extrusion temperature is 50-60°C.

8. The preparation method according to claim 5, characterized in that: The medium of the coagulation bath is a mixed solvent of water and a polar aprotic solvent.

9. The preparation method according to claim 8, characterized in that: The polar aprotic solvent is selected from at least one of dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide.

10. The preparation method according to claim 5, characterized in that: The water washing temperature is 50-70°C, and the draft ratio is 1.0-1.05; and / or, The oiling temperature is 15-25°C; and / or, The drying and densification is performed in at least 2 steps; and / or, The drying and densification temperature is 100-160°C; and / or, The drafting ratio of the steam drafting is 2.0-3.

0.

11. The preparation method according to claim 10, characterized in that: The oiling temperature is 15-20°C.

12. A high-strength and high-modulus carbon fiber prepared from high-strength and high-modulus carbon fiber precursor, wherein the high-strength and high-modulus carbon fiber precursor is prepared by the preparation method of the high-strength and high-modulus carbon fiber precursor according to any one of claims 1 to 11.

13. A method for preparing the high-strength and high-modulus carbon fiber according to claim 12, comprising pre-oxidizing, carbonizing, graphitizing and post-treating the high-strength and high-modulus carbon fiber precursor obtained by steam drawing to obtain the high-strength and high-modulus carbon fiber.

14. The preparation method according to claim 13, characterized in that: The pre-oxidation temperature is 180-260° C., and the pre-oxidation draft ratio is 0.95-1.1; and / or, The carbonization includes low temperature carbonization and high temperature carbonization; and / or, The graphitization temperature is 2200-3000°C; and / or, The post-treatment includes surface treatment, washing, sizing, drying and silk collection.

15. The preparation method according to claim 14, characterized in that: The low-temperature carbonization temperature is 300-750°C; and / or, The low temperature carbonization draw ratio is 1.05-1.15; and / or, The high temperature carbonization temperature is 800-1500°C; and / or, The high temperature carbonization draw ratio is 0.95-1.05; and / or, The graphitization temperature is 2500-2800°C.

16. The preparation method according to claim 15, characterized in that: The low temperature carbonization draw ratio is 1.05-1.1; and / or, The high temperature carbonization drawing ratio is 0.97-1.02.