High air permeability pitch-based carbon fiber raw paper and preparation process thereof

Abstract

The present application relates to special papermaking, carbon fiber composite material preparation technical field, especially to a kind of high air permeability pitch-based carbon fiber base paper and its preparation process, its preparation method includes the following steps: step 1, using dilute hydrochloric acid to clean pitch-based carbon fiber A;Fibroplasty is obtained to aramid fiber, and aramid pulp B is obtained;Step 2, pitch-based carbon fiber, aramid pulp is formed into carbon fiber paper by wet method;Step 3, pitch-based carbon fiber paper is impregnated with phenol formaldehyde resin, dried, finished, and pitch-based carbon fiber base paper is prepared.The present application proposes a new method for preparing carbon fiber base paper with high air permeability by acid cleaning carbon fiber, fibroplasty aramid fiber, hybrid pulp wet forming, resin impregnation strengthening and hot pressing finishing, which solves the problem of difficult to balance strength, flexibility, high conductivity and high air permeability by aramid pulp auxiliary interweaving and low concentration resin strengthening, and provides a kind of high air permeability carbon fiber base paper and its preparation process.

Description

TECHNICAL FIELD

[0001] The application belongs to the cross technical field of special papermaking and carbon fiber base material preparation, and particularly relates to high-air-permeability pitch-based carbon fiber raw paper and a preparation process thereof. BACKGROUND

[0002] Among numerous new energy, fuel cells have high energy conversion efficiency, low pollution, low noise and strong adaptability, and thus have attracted extensive attention. At present, fuel cells are mainly divided into alkaline fuel cells, proton exchange membrane fuel cells, solid oxide fuel cells and phosphoric acid fuel cells, among which, proton exchange membrane fuel cells use hydrogen, methanol and other fuels, and are favored by the market. The proton exchange membrane fuel cell is mainly composed of a bipolar plate, a gas diffusion layer and a proton exchange membrane. The diffusion layer not only supports the catalyst, but also is an important carrier for fuel gas diffusion, water and heat conduction and current collection. However, due to the existence of chemical corrosion, there are not many materials that can be used as the gas diffusion layer of the fuel cell. Carbon paper is a material that has been successfully commercialized by international companies such as Japan's Toray and Germany's SGL, and has high commercial potential and value.

[0003] The carbon paper is obtained by carbonization, graphitization and hydrophobic treatment of carbon fiber raw paper, and the structure and performance of the carbon fiber raw paper determine the quality of the final carbon. However, carbon fibers have strong inertness and high brittleness, and it is difficult to prepare carbon fiber raw paper with high flexibility, high conductivity and high air permeability. In order to obtain carbon fiber raw paper with high air permeability, scientists have used polyethylene glycol and phenolic resin to glue carbon fibers, and then cured them at high temperature to obtain carbon fiber raw paper. For example, the patent US20180069245 of Mitsubishi Corporation in Japan glues carbon fibers with 15% polyvinyl alcohol to obtain flexible carbon fiber paper. The patent US2006214320 of Tse-Hao obtains carbon paper with a deflection of 1.5-4.8 mm by mixing with cellulose and impregnating with phenolic resin. Thereafter, the patent US6489051 of Mikio et al. prepares carbon paper by using vinyl acetate, epoxy resin and melamine resin, but there are problems of insufficient air permeability and introduction of impurities. For a long time, due to the late start of domestic carbon fibers, the manufacturing technology of carbon fiber paper has been relatively backward. SUMMARY

[0004] In view of the problem that the air permeability, strength, conductivity and flexibility of traditional carbon fiber raw paper are difficult to be considered simultaneously, the application provides high-air-permeability pitch-based carbon fiber raw paper and a preparation process thereof. The carbon fiber raw paper is prepared by taking pitch-based carbon fiber as a skeleton, taking aramid pulp as an auxiliary forming fiber and using low-concentration phenolic resin impregnation as a strengthening agent, so as to solve the contradiction between the conductivity, strength, flexibility and air permeability of the carbon fiber paper.

[0005] The application is realized by the following technical scheme:

[0006] A high-air-permeability pitch-based carbon fiber base paper and a preparation process thereof, comprising the following steps:

[0007] Step 1, pitch-based carbon fiber is soaked in dilute hydrochloric acid solution, and then ultrasonic cleaning, drying time to obtain pitch-based carbon fiber A;

[0008] The waste aramid fabric is separated by twisting, beating and refining to obtain aramid pulp B with high specific surface area, high terminal bifurcation and high interweaving force;

[0009] Step 2: first, the aramid pulp B is defibrated in water, then pitch-based carbon fiber A and PEO dispersion liquid are added for defibration again, and then pitch-based carbon fiber paper C is prepared by forming and drying treatment;

[0010] Step 3: pitch-based carbon fiber paper C is immersed in phenolic resin dispersion solution, and then dried and hot-pressed to obtain pitch-based carbon fiber base paper with high air permeability.

[0011] Preferably, in step 1, the pitch-based carbon fiber has the following requirements: length of 3-8 mm, diameter of 7-8 μm, resistivity of 1.5-2.0 μΩ·m, tensile strength of 2.2-2.4 Gpa, and elongation at break of 0.25%-0.26%; the concentration of dilute hydrochloric acid is 1-2%, the ultrasonic treatment time is 5-10 min, and the drying temperature is 100-105℃ for 15-25 min.

[0012] Preferably, in step 1, the waste aramid fabric is para-aramid fiber, mainly from discarded body armor and woven fabric production scraps.

[0013] Preferably, in step 1, the feeding time during twisting is 40-50 kg / h, the beating time during beating is 3-5 h, the refining time during refining is 0.5-1.0 h, and the specific surface area of aramid pulp B is 10-12 m 2 / g.

[0014] Preferably, in step 2, the ratio of aramid pulp B to water is 1.0-1.2 g: 2 L, and the defibration speed is 5000-6000 rpm.

[0015] Preferably, in step 2, the dry mass ratio of pitch-based carbon fiber A to aramid pulp B is 6-5:4, the concentration of PEO dispersion liquid is 0.5 g / L, the volume is 5-10 mL, and the defibration speed is 20,000-25,000 rpm.

[0016] Preferably, in step 2, the drying temperature is 110-120℃, and the drying time is 10-15 min.

[0017] Preferably, in step 3, the phenolic resin dispersion solution is industrial-grade ethanol with a mass fraction of 0.8 wt%-1.0 wt%, and the impregnation time is 5-10 min.

[0018] Preferably, in step 3, the drying temperature is 60-70 DEG C, and the drying time is 20-30 min; the hot-pressing temperature is 150-180 DEG C, the hot-pressing time is 5-8 min, and the hot-pressing pressure is 6-10 MPa.

[0019] An asphalt-based carbon fiber base paper prepared by the process.

[0020] Compared with the prior art, the process has the following beneficial effects:

[0021] First, the process for preparing the high-air-permeability asphalt-based carbon fiber base paper uses asphalt-based carbon fiber as the framework, aramid pulp as the auxiliary forming fiber, and low-concentration phenolic resin impregnation as the reinforcing agent to prepare the carbon fiber base paper with high air permeability, thereby solving the contradiction between the conductivity, strength, flexibility, and air permeability of the carbon fiber paper. Compared with the disclosed process scheme, the raw material components are optimized and limited: on the one hand, aramid pulp fiber is introduced to improve the paper formation uniformity and promote fiber interweaving, and on the other hand, low-concentration phenolic resin impregnation is used to avoid the blocking of the pores. In this structure, the introduced aramid pulp molecular structure is alternately composed of benzene rings and amide bonds, and the molecular structure has a high carbon content, which is beneficial to obtaining a paper with higher conductivity after carbonization. At the same time, since the aramid pulp has good dispersibility after floc formation, the paper formation uniformity of the carbon fiber base paper can also be improved.

[0022] The introduced aramid pulp has good flexibility and adhesion, which can improve the flexibility and strength of the paper after paper formation, make up for the brittleness and interface inertia of the carbon fiber, form a rich conductive network after carbonization, and be beneficial to the improvement of the comprehensive conductive performance of the paper, thereby solving the contradiction between the strength, flexibility, and conductivity of the carbon fiber. In addition, the proportion of the aramid pulp is obtained through long-term process optimization. If the aramid pulp content is too high, the resin impregnation is not conducive, and the pore structure of the paper is easily blocked. If the aramid pulp content is too low, the paper formation uniformity is not obviously improved, and the flexibility is insufficient.

[0023] Further, on the basis of the introduction of aramid pulp, the interweaving points between the carbon fibers, the carbon fibers and the aramid pulp, and the aramid pulp are adhered and reinforced through the ultra-low-concentration phenolic resin impregnation. The concentration of the phenolic resin is the result of process optimization. At the ultra-low concentration, the contact deficiency of the fibers is supplemented, the construction of the conductive network after carbonization is facilitated, the strength is completely achieved, the stress is transmitted during the stretching process, and the realization of the performance of the paper is ensured.

[0024] Further, the preferred aramid pulp in the application contains abundant amino groups, which has good compatibility and self-binding force with phenolic resin, ensuring high efficiency at low concentration. The principle is that the aramid pulp tip groups can form extensive hydrogen bond combination with the resin, and the phenolic resin curing can crosslink the aramid pulp, so that the two are combined by chemical and physical interaction, which is not available in other public patent applications. The realization of this principle belongs to one of the unique technical points of the application.

[0025] Further, the pulp disintegration revolution number, fiber adding sequence, drying temperature, hot pressing finishing temperature and hot pressing finishing pressure in the application are the results of process optimization. For example, the pulp disintegration revolution number ensures no breakage under high dispersion, the drying temperature guarantees energy saving under high efficiency, and the finishing temperature ensures no rheological plugging under phenolic resin curing, which are the results of long-term process optimization. The technical effect lies in improving the paper quality and saving energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figure is the flow chart of the preparation process of the high-air-permeability pitch-based carbon fiber base paper of the application.

[0027] Figure 2 The figure is the SEM image of the cross section of the carbon fiber paper of Example 3.

[0028] As can be more clearly seen in the figure, the carbon fibers and aramid pulp form an interwoven network with gas channels in the middle, indicating the reason for high air permeability.

[0029] Figure 3 The figure is the SEM image of the surface of the carbon fiber paper of Example 4.

[0030] As can be seen in the figure, the carbon fibers and aramid pulp are interwoven, and there are abundant pores. DETAILED DESCRIPTION

[0031] The application will be further described in detail below in combination with specific examples, which are an explanation of the application rather than a limitation.

[0032] The application discloses a high-air-permeability pitch-based carbon fiber base paper and a preparation process thereof, which comprises the following steps:

[0033] Step 1, pitch-based carbon fibers are soaked in a dilute hydrochloric acid solution, then ultrasonic cleaning, drying to obtain pitch-based carbon fiber A; Specifically: select the length of 3-8 mm, diameter of 7-8 μm, resistivity 1.5-2.0 μΩ·m, tensile strength 2.2-2.4 Gpa, elongation at break 0.25%-0.26% of pitch-based carbon fiber, add it to the concentration of 1-2% dilute hydrochloric acid solution, and ultrasonic cleaning treatment for 5-10 min, dry at 100-105 ℃ for 15-25 min, obtain pitch-based carbon fiber A;

[0034] The waste aramid fabric composed of retired body armor and woven fabric production scraps is separated into a high specific surface area, high tip bifurcation, and high interweaving force aramid pulp B by twisting, beating, and refining;

[0035] Among them, the twisting is carried out by a twisting machine, the model of the twisting machine is TMF250, the feeding time of the twisting machine is 40-50 kg / h; the beating is carried out by a beater, the model of the beater is a tank beater 220, the beating time is 3-5 h; the refining machine model is 380, the refining time is 0.5-1.0 h; the specific surface area of the aramid pulp B is 10-12 m 2 / g.

[0036] Step 2: The aramid pulp B is now defibrated with water in a ratio of (1.0-1.2) g: 2 L, and the rotation speed during defibration is (4500-5000) rpm;

[0037] Then, according to the dry mass ratio of pitch-based carbon fiber A to aramid pulp B (6-5):4, pitch-based carbon fiber A is added, and then 5-10 mL of PEO dispersion solution with a concentration of 0.5 g / L is added, and then defibrated at 20000-25000 rpm to obtain a hybrid pulp;

[0038] The hybrid pulp is papered by a paper sheet former, and the paper is dried at 110-120 ℃ for 10-15 min to obtain pitch-based carbon fiber paper C.

[0039] Step 3: The pitch-based carbon fiber paper C is immersed in a phenolic resin dispersion solution (industrial grade ethanol) with a mass fraction of 0.8 wt%-1.0 wt% for 5-10 min;

[0040] Then the pitch-based carbon fiber paper C is dried at 60-70 ℃ for 20-30 min to obtain dry pitch-based carbon fiber paper D;

[0041] Then the dry pitch-based carbon fiber paper D is hot pressed and finished using a flat vulcanizing machine at a temperature of 150-180 ℃, a time of 5-8 min, and a pressure of 6-10 MPa to obtain a pitch-based carbon fiber base paper with high air permeability.

[0042] The preparation process of the high-air-permeability pitch-based carbon fiber base paper first uses dilute hydrochloric acid to clean pitch-based carbon fiber A; aramid fiber is separated into a feather duster to obtain aramid pulp B; then pitch-based carbon fiber and aramid pulp are formed into carbon fiber paper by a wet method; finally, the pitch-based carbon fiber paper is impregnated with phenolic resin, dried, and finished to obtain the pitch-based carbon fiber base paper. The new method for preparing the carbon fiber base paper with high air permeability is achieved by acid cleaning of carbon fiber, separation of aramid fiber into a feather duster, hybrid pulp wet forming, resin impregnation strengthening, and hot pressing finishing. The method solves the problem of difficult to balance strength, flexibility, high conductivity, and high air permeability by auxiliary interweaving of aramid pulp and low-concentration resin strengthening, and provides a high-air-permeability carbon fiber base paper and a preparation process thereof.

[0043] The defibrator, paper sheet former, dryer, and hot press used in the process scheme are all uniform and conventional equipment, and the solvent is tap water and ethanol, and the process link is environmentally friendly, which lays a good foundation for industrialization and scaling of the present application and has high market competition advantage.

[0044] The present application also discloses a pitch-based carbon fiber base paper prepared by the preparation process of the high-air-permeability pitch-based carbon fiber base paper.

[0045] Example 1

[0046] Step 1: pitch-based carbon fiber with a length of 3 mm, a diameter of 7 μm, an electrical resistivity of 1.5 μΩ·m, a tensile strength of 2.2 Gpa, and an elongation at break of 0.25% is selected, immersed in a dilute hydrochloric acid solution with a concentration of 2%, and ultrasonically cleaned for 10 min to obtain pitch-based carbon fiber A after drying;

[0047] The waste aramid fabric is separated into a feather duster by a twisting machine, a beater, a refiner, and other equipment to obtain aramid pulp B with a specific surface area of 10 m 2 / g;

[0048] The feeding time of the twisting machine is 40 kg / h, the beating time is 3 h, and the refiner time is 0.5 h.

[0049] Step 2: the aramid pulp B is defibrated in water at 6000 rpm according to the mass of the aramid pulp B to the volume of water ratio of 1.0 g: 2 L;

[0050] Pitch-based carbon fiber A is added according to the dry mass ratio of pitch-based carbon fiber A to aramid pulp B of 6:4, and 5 mL of PEO solution with a concentration of 0.5 g / L is added, and then defibrated at 20000 rpm to uniformly disperse to obtain hybrid pulp;

[0051] The hybrid pulp is papered by a paper sheet former, and the paper is dried at 110℃ for 10min to obtain pitch-based carbon fiber paper C.

[0052] Step 3: pitch-based carbon fiber paper C is immersed in a phenolic resin dispersion solution with a mass fraction of 0.8wt% for 5min, and then dried at a temperature of 60℃ for 20min to obtain dry pitch-based carbon fiber paper D;

[0053] The dry pitch-based carbon fiber paper D is hot-pressed for finishing by a flat vulcanizing machine at 150℃ for 5min under a pressure of 6MPa to obtain pitch-based carbon fiber base paper with high air permeability.

[0054] The carbon fiber base paper prepared by the preparation process of the pitch-based carbon fiber base paper with high air permeability in this embodiment has a basis weight of 85g / m 2 , a thickness of 0.153mm, an air permeability of 8104 mL / min, a tensile strength of 21.29 MPa, and a square resistance of 18.06Ω / sq, and has high air permeability; in addition, the process flow is stable, the operability is strong, the comprehensive cost is controllable, and the process has good social and economic benefits.

[0055] Example 2

[0056] Step 1: pitch-based carbon fibers with a length of 8mm, a diameter of 8μm, an electrical resistivity of 2.0 μΩ·m, a tensile strength of 2.4Gpa, and an elongation at break of 0.26% are selected, immersed in a dilute hydrochloric acid solution with a concentration of 1.5%, and ultrasonically cleaned for 8min to obtain pitch-based carbon fibers A after drying;

[0057] The waste aramid fabric is separated by a wire twisting machine, a beater, a refiner and other equipment to obtain aramid pulp B with a specific surface area of 12 m 2 / g; wherein the feeding time of the wire twisting machine is 50kg / h, the beating time is 3-5h, and the refining time is 1.0h.

[0058] Step 2: the aramid pulp B is defibrated in water at 5000rpm according to a mass of aramid pulp B to a volume of water ratio of 1.2g: 2L;

[0059] Pitch-based carbon fibers A are added according to a dry mass ratio of 5:4 of pitch-based carbon fibers A to aramid pulp B, and 10mL of PEO dispersion solution with a concentration of 0.5g / L is added, and then defibrated at 25000rpm to obtain a hybrid pulp.

[0060] The hybrid pulp is papered by a paper sheet former, and the paper is dried at 110℃ for 10min to obtain pitch-based carbon fiber paper C.

[0061] Step 3: The pitch-based carbon fiber paper C was impregnated in a phenolic resin dispersion solution with a mass fraction of 1.0wt% for 10min, and then dried at a temperature of 70℃ for 30min to obtain dry pitch-based carbon fiber paper D;

[0062] The dry pitch-based carbon fiber paper D was hot-pressed for finishing by using a flat vulcanizing machine at a temperature of 180℃ for 8min under a pressure of 10MPa to obtain a pitch-based carbon fiber base paper with high air permeability.

[0063] The carbon fiber base paper prepared by the preparation process of the pitch-based carbon fiber base paper with high air permeability in the embodiment has a basis weight of 90g / m 2 , a thickness of 0.160mm, an air permeability of 7057 mL / min, a tensile strength of 20.31 MPa, and a square resistance of 16.52Ω / sq, and has high air permeability characteristics; in addition, the process flow is stable, the operability is strong, the comprehensive cost is controllable, and good social and economic benefits are obtained.

[0064] Example 3

[0065] Step 1: pitch-based carbon fibers with a length of 5mm, a diameter of 7μm, an electrical resistivity of 1.7 μΩ·m, a tensile strength of 2.3Gpa, and an elongation at break of 0.25% were selected, and were soaked in a dilute hydrochloric acid solution with a concentration of 1% and ultrasonically cleaned for 6min, and then dried to obtain pitch-based carbon fibers A;

[0066] The waste aramid fabric was separated by a wire twisting machine, a beater, a refiner and other equipment to obtain aramid pulp B with a specific surface area of 11 m 2 / g;

[0067] The feeding time of the wire twisting machine was 45kg / h, the beating time was 4h, and the refining time was 0.75h.

[0068] Step 2: The aramid pulp B was defibrated in water at 5700 rpm according to a mass of aramid pulp B to a volume of water ratio of 1.1g: 2L;

[0069] Pitch-based carbon fibers A were added according to a dry mass ratio of pitch-based carbon fibers A to aramid pulp B of 5.5:4, and 7mL of a PEO dispersion solution with a concentration of 0.5g / L was added, and then defibrated at 23000rpm to obtain a hybrid pulp;

[0070] The hybrid pulp was papered by a paper sheet former, and the paper was dried after being formed to obtain pitch-based carbon fiber paper C, wherein the drying temperature of the dryer was 115℃, and the time was 13min.

[0071] Step 3: The pitch-based carbon fiber paper C was immersed in a phenolic resin dispersion solution with a mass fraction of 0.9wt% for 7min, and then dried at a temperature of 65℃ for 25min to obtain dry pitch-based carbon fiber paper D;

[0072] The dry pitch-based carbon fiber paper D was hot-pressed for finishing by using a flat vulcanizing machine at a temperature of 165℃, a time of 7min, and a pressure of 8MPa to obtain a pitch-based carbon fiber base paper with high air permeability.

[0073] The carbon fiber base paper prepared by the pitch-based carbon fiber base paper preparation process in this embodiment has a basis weight of 70g / m 2 , a thickness of 0.142mm, an air permeability of 7548 mL / min, a tensile strength of 23.43 MPa, and a square resistance of 15.34Ω / sq, and has high air permeability characteristics, as shown in Figure 2 , the surface carbon fibers and aramid pulp form an interwoven network with gas channels in between, which further indicates the reason for high air permeability.

[0074] Example 4

[0075] Step 1: Pitch-based carbon fibers with a length of 5mm, a diameter of 7μm, an electrical resistivity of 1.5 μΩ·m, a tensile strength of 2.2Gpa, and an elongation at break of 0.25% were selected, immersed in a dilute hydrochloric acid solution with a concentration of 2%, and ultrasonically cleaned for 5min, and then dried to obtain pitch-based carbon fibers A;

[0076] The waste aramid fabric was separated by a silk rubbing machine, a beater, a refiner, and other equipment to obtain aramid pulp B with a specific surface area of 11 m 2 / g; wherein the feeding time of the silk rubbing machine was 42kg / h, the beating time was 3.5h, and the refining time was 0.8h.

[0077] Step 2: The aramid pulp B was defibrated in water at 5500rpm according to a mass of aramid pulp B to a volume of water ratio of 1.0g: 2L; the pitch-based carbon fibers A were added according to a dry mass ratio of pitch-based carbon fibers A to aramid pulp B of 5.5:4, and 8mL of PEO dispersion solution with a concentration of 0.5 g / L was added, and then defibrated at 23000rpm to uniformly disperse to obtain a hybrid pulp;

[0078] The hybrid pulp was papered by a paper sheet former, and the paper was dried after being formed to obtain pitch-based carbon fiber paper C, wherein the drying temperature of the dryer was 115℃, and the time was 14min.

[0079] Step 3: The pitch-based carbon fiber paper C was immersed in a phenolic resin dispersion solution with a mass fraction of 0.9wt% for 8min, and then dried at a temperature of 65℃ for 25min to obtain dry pitch-based carbon fiber paper D;

[0080] The dry pitch-based carbon fiber paper D is hot-pressed for finishing by using a flat vulcanizing machine at 165℃, for 6min, and under a pressure of 7MPa, to obtain a pitch-based carbon fiber base paper with high air permeability.

[0081] The carbon fiber base paper prepared by the preparation process of the high air permeability pitch-based carbon fiber base paper in this embodiment has a basis weight of 80g / m 2 , a thickness of 0.149mm, an air permeability of 7821 mL / min, a tensile strength of 25.21 MPa, and a square resistance of 17.53Ω / sq, and has high air permeability characteristics, and Figure 3 , the surface carbon fibers are interwoven with aramid pulp, and there are abundant pores.

[0082] Example 5

[0083] Step 1: pitch-based carbon fibers with a length of 7mm, a diameter of 8μm, an electrical resistivity of 1.9 μΩ·m, a tensile strength of 2.3Gpa, and an elongation at break of 0.25% are selected, soaked in a dilute hydrochloric acid solution with a concentration of 1%, and ultrasonically cleaned for 10min, and dried to obtain pitch-based carbon fibers A;

[0084] The waste aramid fabric is separated by a thread separating machine, a beater, a refiner, and the like, to obtain aramid pulp B with a specific surface area of 11 m 2 / g; wherein the feeding time of the thread separating machine is 45kg / h, the beating time is 3.5h, and the refining time is 0.9h.

[0085] Step 2: the aramid pulp B is defibrated in water at 5700rpm according to a mass of aramid pulp B to a volume of water ratio of 1.1g: 2L.

[0086] Pitch-based carbon fibers A are added again according to a dry mass ratio of pitch-based carbon fibers A to aramid pulp B of 5.4:4, and a PEO dispersion solution with a concentration of 0.5 g / L is added by 6mL, and then defibrated at 22000rpm to uniformly disperse to obtain a hybrid pulp;

[0087] The hybrid pulp is papered by a paper sheet former, and the paper sheet is dried after being formed to obtain pitch-based carbon fiber paper C, wherein the drying temperature of the dryer is 117℃, and the time is 13min.

[0088] Step 5: the pitch-based carbon fiber paper C is immersed in a phenolic resin dispersion solution with a mass fraction of 0.85wt% for 8min, and then dried at a temperature of 67℃ for 27min to obtain dry pitch-based carbon fiber paper D;

[0089] Finally, the dried asphalt-based carbon fiber paper D is hot-pressed for finishing on a flat vulcanizing machine at 165 DEG C for 6 min under a pressure of 8 MPa to obtain an asphalt-based carbon fiber base paper with high air permeability.

[0090] The carbon fiber base paper prepared by the high air permeability asphalt-based carbon fiber base paper preparation process in the embodiment has a basis weight of 80 g / m 2 , a thickness of 0.147 mm, an air permeability of 7953 mL / min, a tensile strength of 26.64 MPa, and a square resistance of 16.89 Ω / sq, and has high air permeability; in addition, the process flow is stable, the operability is strong, the comprehensive cost is controllable, and the process has good social and economic benefits.

[0091] Table 1 Technical parameters of carbon fiber base paper prepared in Examples 1-5

[0092]

[0093] Table 1 is the technical parameters of the carbon fiber base paper prepared in the examples. According to the data analysis, the air permeability of the carbon fiber base paper prepared by the process provided by the present application can reach the range of 7548-8104 mL / min, which is a relatively high level, which is due to the full interweaving of the asphalt-based carbon fiber and aramid pulp, but the result of retaining high porosity; the tensile strength of the carbon fiber base paper in the examples is more than 20 MPa, reaching a relatively high strength, which is due to the hydrogen bond combination between aramid pulp, strong interweaving force on the one hand, and the contact points between carbon fiber and aramid pulp are solidified by phenolic resin impregnation on the other hand.

[0094] The above only describes the preferred embodiments of the present application, and does not use any limitation on the technical solutions of the present application. Those skilled in the art should understand that the technical solutions can be modified and replaced in several simple ways without departing from the spirit and principles of the present application, and these modifications and replacements also belong to the protection scope covered by the claims.

Claims

1. A process for the production of high air permeability pitch-based carbon fiber precursor, characterized in that, It comprises the following steps: Step 1, pitch-based carbon fiber is soaked in dilute hydrochloric acid solution, and then ultrasonic cleaning, drying to obtain pitch-based carbon fiber A; the relevant requirements of pitch-based carbon fiber are as follows: length of 3-8 mm, diameter of 7-8 μm, resistivity of 1.5-2.0 μΩ·m, tensile strength of 2.2-2.4 Gpa, elongation at break of 0.25%-0.26%; The waste aramid fabric is separated into a high specific surface area, high terminal bifurcation and high interweaving force aramid pulp B through twisting, beating and refining. 2 / g; Step 2: first, aramid pulp B is defibrated in water, then pitch-based carbon fiber A and PEO dispersion liquid are added for defibration again, and then pitch-based carbon fiber paper C is prepared through forming and drying treatment; the dry mass ratio of pitch-based carbon fiber A to aramid pulp B is 6-5:4, the concentration of PEO dispersion liquid is 0.5 g / L, and the volume is 5-10 mL; Step 3: pitch-based carbon fiber paper C is immersed in phenolic resin dispersion solution, and then dried and hot-pressed to obtain pitch-based carbon fiber base paper with high air permeability; The phenolic resin dispersion solution is industrial grade ethanol with a mass fraction of 0.8 wt%-1.0 wt%, and the immersion time is 5-10 min; During hot pressing, the temperature is 150-180℃, the time is 5-8 min, and the pressure is 6-10 MPa.

2. The process for preparing a high air permeability pitch-based carbon fiber precursor paper according to claim 1, characterized in that, In step 1, the concentration of dilute hydrochloric acid is 1-2%, the ultrasonic treatment time is 5-10 min, and the drying temperature is 100-105℃, and the time is 15-25 min.

3. The process for preparing high air permeability pitch-based carbon fiber precursor paper according to claim 1, characterized in that, In step 1, the waste aramid fabric is para-aramid fiber, mainly from discarded body armor and woven fabric production scraps.

4. The process for preparing high air permeability pitch-based carbon fiber precursor paper according to claim 1, characterized in that, In step 1, the feeding time of the wire rolling machine is 40-50 kg / h, the beating time of the beater is 3-5 h, and the grinding time of the grinding machine is 0.5-1.0 h.

5. A high air permeability pitch-based carbon fiber precursor paper production process according to claim 1, characterized in that, In step 2, the ratio of aramid pulp B to water is 1.0-1.2 g:2 L, and the defibration speed is 5000-6000 rpm.

6. A process for the preparation of high air permeability pitch-based carbon fiber precursor according to claim 1, characterized in that, In step 2, during the second defibration, the defibration speed is 20000-25000 rpm.

7. The process for preparing high air permeability pitch-based carbon fiber precursor paper according to claim 1, characterized in that, In step 2, during drying, the temperature is 110-120℃, and the time is 10-15 min.

8. The process for preparing high air permeability pitch-based carbon fiber precursor paper according to claim 1, characterized in that, In step 3, during drying, the temperature is 60-70℃, and the time is 20-30 min.

9. A pitch-based carbon fiber base paper prepared by the process of any one of claims 1-8.

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