阅读说明：本技术 一种碳纤维纸及其制备方法 (Carbon fiber paper and preparation method thereof ) 是由 汪训国 于 2021-07-21 设计创作，主要内容包括：本发明公开了一种碳纤维纸及其制备方法,本发明制备方法按以下步骤：(1)对短切聚丙烯腈碳纤维进行亲水表面处理；(2)将步骤(1)处理后的短切聚丙烯腈碳纤维置于水中分散、抄纸制成碳纤维原纸；(3)将碳纤维原纸浸渍热固性酚醛树脂乙醇溶液,后经过烘干、热压、固化、碳化制成初级碳纤维纸；(4)采用氢气为刻蚀剂,在800-1000℃下对初级碳纸表面进行刻蚀；(5)以小分子烃类化合物为反应碳源气体,在900-1100℃下在碳纸表面沉积一段时间,得到碳纸；(6)将碳纸在2200-2700℃下石墨化一段时间,得到所述的碳纤维纸。本发明制得的碳纤维纸可以满足高性能燃料电池、高温过滤、高性能复合等领域对高强度的需求。(The invention discloses carbon fiber paper and a preparation method thereof, wherein the preparation method comprises the following steps: (1) carrying out hydrophilic surface treatment on the short-cut polyacrylonitrile carbon fiber; (2) dispersing the chopped polyacrylonitrile carbon fibers treated in the step (1) in water, and making paper into carbon fiber base paper; (3) impregnating carbon fiber base paper with a thermosetting phenolic resin ethanol solution, and then drying, hot-pressing, curing and carbonizing to prepare primary carbon fiber paper; (4) adopting hydrogen as an etching agent to etch the surface of the primary carbon paper at the temperature of 800-; (5) depositing on the surface of the carbon paper for a period of time at 900-1100 ℃ by taking a micromolecular hydrocarbon compound as a reaction carbon source gas to obtain the carbon paper; (6) graphitizing the carbon paper at the temperature of 2200 ℃ and 2700 ℃ for a period of time to obtain the carbon fiber paper. The carbon fiber paper prepared by the method can meet the requirements of the fields of high-performance fuel cells, high-temperature filtration, high-performance compounding and the like on high strength.)

1. The preparation method of the carbon fiber paper is characterized by comprising the following steps of:

(1) carrying out hydrophilic surface treatment on the short-cut polyacrylonitrile carbon fiber;

(2) dispersing the chopped polyacrylonitrile carbon fibers treated in the step (1) in water, and making paper into carbon fiber base paper;

(3) impregnating carbon fiber base paper with a thermosetting phenolic resin ethanol solution, drying, and then carrying out hot pressing, curing and carbonization to prepare primary carbon fiber paper;

(4) adopting hydrogen as an etching agent to etch the surface of the primary carbon paper at the temperature of 800-;

(5) depositing on the surface of the carbon paper for a period of time at 900-1100 ℃ by taking a micromolecular hydrocarbon compound as a reaction carbon source gas to obtain the carbon paper;

(6) graphitizing the carbon paper at the temperature of 2200 ℃ and 2700 ℃ for a period of time to obtain the carbon fiber paper.

2. The method for preparing carbon fiber paper as claimed in claim 1, wherein in the step (1), the length of the chopped polyacrylonitrile carbon fiber is between 3 and 8 mm.

3. The method for preparing the carbon fiber paper as claimed in claim 1 or 2, wherein in the step (1), the chopped polyacrylonitrile carbon fiber hydrophilic surface treatment is carried out by soaking in 3-10M NaOH at normal temperature or in more than 14M concentrated nitric acid, and after soaking, the carbon fiber paper is cleaned by clear water and then dried.

4. The method for preparing the carbon fiber paper as claimed in claim 3, wherein in the step (1), the soaking treatment with NaOH at normal temperature is carried out for 20-40 minutes, or the soaking treatment with concentrated nitric acid is carried out for 10-30 minutes.

5. The method for preparing carbon fiber paper as claimed in claim 1, wherein the dispersant used in the step (2) is polyethylene oxide.

6. The method for preparing carbon fiber paper as claimed in claim 1, wherein in the step (3), the hot pressing process is 0.2-2MPa and the temperature is 120-180 ℃; curing for a period of time at normal pressure and 200 ℃ after hot pressing; the carbonization process after curing is carried out for a period of time at 1000 ℃ in an inert atmosphere.

7. The method for preparing carbon fiber paper as claimed in claim 1, wherein in the step (4), argon is used as a conditioning gas during the etching process.

8. The method for preparing carbon fiber paper as claimed in claim 1, wherein in the step (5), the small-molecule hydrocarbon compound is selected from methane or propylene.

9. A carbon fiber paper characterized by being produced by the production method according to any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of carbon fiber application, and particularly relates to high-strength carbon fiber paper and a preparation method thereof.

Background

The carbon fiber paper is a composite product of carbon fibers, and is a paper-shaped product prepared by chopping and dispersing the carbon fibers, adopting a conventional paper making process, and then carrying out impregnation, curing, carbonization and graphitization processes. The carbon paper is widely applied to the fields of fuel cell diffusion layers and supporting elements, high-temperature filtration, carbon paper reinforcing agents and the like.

Strength is one of the most fundamental performance parameters in the use of carbon paper. The performance of the carbon paper prepared by adopting a wet process mainly depends on the strength of the carbon fiber and the strength of the carbon paper after the carbon paper is carbonized by the impregnated binder, wherein the function of the binder is a decisive factor. Since carbon paper acts as a diffusion and structural support, the user expects the higher the mechanical properties of the carbon paper the better. The properties of carbon papers prepared based on the aforementioned processes have reached the limits of the process. In order to further improve the mechanical properties, the improvement or introduction of new ideas and processes on the basis of the conventional process is needed.

Improvements to conventional processes typically improve the performance of carbon paper by adding graphite powder, carbon black, etc. during the impregnation of the binder resin. For example, in the text of ' influence of graphite powder on performance of carbon paper for PEMFC ', published by beili et al in 2012, pages 393 and 399 of the journal of novel carbon materials ', the influence of a graphite powder adding method on performance of carbon paper is studied, and a good effect is obtained. However, the binder used is still a resin, and the improvement of properties such as strength is limited. In order to greatly improve the performance of the carbon paper, Chinese patent application No. 200910044785.1 discloses a method and a device for improving the performance of the carbon paper based on a differential pressure method rapid CVI coating. However, the patent application does not consider the bonding force between different precursor carbons (carbon and chemical deposition carbon in conventional carbon paper), the interface bonding force of the carbons with different structures is limited, and the performance improvement degree is limited.

Carbon paper products are composites of carbon fibers and non-fibrous carbon, and the key factor determining the performance of the composite is the interfacial bonding force. The carbon paper surface carbon deposition process prepared by the conventional method has the defects that the bonding force between carbon in the carbon fiber and carbon converted by resin and the deposited carbon is not ideal, the surface of carbon formed at the early stage is smooth, and the carbon expands and contracts asynchronously under heating in the deposition and graphitization processes, so that microcracks are formed on the interface, and the improvement of the mechanical property and the comprehensive property of the carbon paper is not facilitated. There are many methods for improving the interface strength of the carbon fiber and other materials, and the interface of the composite material can be improved by forming grooves on the surface of the carbon fiber through surface treatment or depositing carbon nanotubes on the surface.

Disclosure of Invention

Based on the above situation in the prior art, the invention aims to improve the mechanical property of the carbon fiber paper, and provides the carbon fiber paper with firm combination of deposited carbon and the carbon fiber paper and the preparation method thereof by combining a graphene etching means. According to the invention, a porous graphene structure is etched on the surface of a primary carbon paper substrate prepared by a conventional method, then the carbon paper is further enhanced in strength by chemical vapor deposition, deposited carbon takes graphene pores as strengthening points, the deposited carbon grows in the graphene pores at the initial stage, the deposited carbon grows in the gaps of the carbon paper at the later stage, the deposited carbon and the carbon paper form a riveting structure, and the deposited carbon and the original carbon of the carbon paper are firmly combined, so that the mechanical property of the carbon paper is greatly improved; and the ideal graphite structure of the graphene edge can induce graphitization by deposited carbon, and the conductivity and performance of the carbon paper are also improved to a certain extent. Tests prove that the carbon paper prepared by the invention has the tensile strength of more than 30MPa, the resistivity of less than 6.0m omega cm and the thermal conductivity of more than 18.0W/m.K.

In order to achieve the technical purpose, the invention is realized by the following technical scheme.

A preparation method of carbon fiber paper is provided, which is prepared by the following steps:

(1) carrying out hydrophilic surface treatment on the short-cut polyacrylonitrile carbon fiber;

(2) dispersing the chopped polyacrylonitrile carbon fibers treated in the step (1) in water, and making paper into carbon fiber base paper;

(3) impregnating carbon fiber base paper with a thermosetting phenolic resin ethanol solution, and then drying, hot-pressing, curing and carbonizing to prepare primary carbon fiber paper;

(4) adopting hydrogen as an etching agent to etch the surface of the primary carbon paper at the temperature of 800-;

(5) using micromolecular hydrocarbon compounds such as methane, propylene and the like as reaction carbon source gas, and depositing on the surface of the carbon paper for a period of time at the temperature of 900-1100 ℃ to obtain enhanced carbon paper;

(6) graphitizing the carbon paper at the temperature of 2200 ℃ and 2700 ℃ for a period of time to adjust the performance parameters of the carbon paper, and obtaining the carbon fiber paper.

Further, in the step (1), the length of the chopped polyacrylonitrile carbon fiber is between 3 and 8 mm.

Further, in the step (1), the surface of the chopped polyacrylonitrile carbon fiber is subjected to hydrophilic treatment by soaking in 3-10M NaOH at normal temperature (preferably for 20-40 minutes) or in more than 14M concentrated nitric acid (preferably for 10-30 minutes), and after soaking, the chopped polyacrylonitrile carbon fiber is washed by clean water and then dried.

Further, in the step (2), polyethylene oxide is used as the dispersant in the dispersion process. The papermaking method in the step can adopt a conventional wet papermaking process.

Further, in the step (3), the hot pressing process is 0.2-2MPa and the temperature is 120-; curing at 200 ℃ under normal pressure (preferably 1 hour) after hot pressing (preferably 30 minutes); the carbonization process after the curing is 1000 ℃ treatment in an inert atmosphere (preferably 1 hour).

Further, in the step (4), during the etching process, argon is used as a conditioning gas.

Further, in the step (4), etching is carried out on the surface of the primary carbon paper for 10-50 minutes.

Further, in the step (5), the deposition time on the surface of the carbon paper is 10-30 minutes.

Further, in step (6), the graphitization time was 30 minutes.

The invention also discloses the carbon fiber paper prepared by the preparation method.

The invention has the following beneficial effects:

the invention provides high-strength carbon fiber paper and a preparation method thereof, and the mechanical property of the carbon paper is greatly improved due to the fact that a riveting structure formed by etching a graphene pore structure and deposited carbon is formed; the induced graphitization of the marginal structure of the graphene enables the electric conduction and heat conduction performance of the carbon paper to be maintained and improved.

The carbon fiber paper prepared by the method can meet the requirements of the fields of high-performance fuel cells, high-temperature filtration, high-performance compounding and the like on high strength.

Detailed Description

The present invention is described in further detail below by way of preferred examples, which will enable those skilled in the art to more fully understand the present invention, but which are not intended to limit the invention in any way.

Example 1

This example is a comparative example.

Taking 5mm short-cut polyacrylonitrile carbon fibers, soaking the carbon fibers in 6M NaOH solution for 20min at normal temperature, then cleaning the carbon fibers with clear water, and drying the carbon fibers to obtain the short-cut carbon fiber raw materials for preparing the carbon fiber paper; dispersing the chopped carbon fiber raw material in water by using polyoxyethylene as a dispersing agent, papermaking to obtain carbon fiber base paper, impregnating the base paper by adopting a phenolic resin ethanol solution, drying, and carrying out hot pressing for 30min at 150 ℃ under 0.8 MPa; curing the hot-pressed carbon fiber paper at 200 ℃ for 1 hour, and then putting the carbon fiber paper into a carbonization furnace in an inert atmosphere for carbonization treatment at 1000 ℃ for 1 hour to obtain primary carbon paper; then, using methane as deposition gas to deposit the carbon paper for 20min at 1000 ℃, thereby obtaining carbon fiber paper; further graphitizing for 30 minutes at 2500 ℃. The performance parameters of the obtained carbon fiber paper are as follows: the tensile strength is 24.3MPa, the thermal conductivity is 16.4W/m.K, and the resistivity is 6.3m omega.cm.

Example 2

Taking 5mm short-cut polyacrylonitrile carbon fibers, soaking the carbon fibers in 6M NaOH solution for 20min at normal temperature, then cleaning the carbon fibers with clear water, and drying the carbon fibers to obtain the short-cut carbon fiber raw materials for preparing the carbon fiber paper; dispersing the chopped carbon fiber raw material in water by using polyoxyethylene as a dispersing agent, papermaking to obtain carbon fiber base paper, impregnating the base paper by using a thermosetting phenolic resin ethanol solution, drying, and hot-pressing at 150 ℃ and 0.8MPa for 30 min; curing the hot-pressed carbon fiber paper at 200 ℃ for 1 hour, and then putting the carbon fiber paper into a carbonization furnace in an inert atmosphere for carbonization treatment at 1000 ℃ for 1 hour to obtain primary carbon paper; then, etching the surface of the carbon paper for 20 minutes at 900 ℃ by taking hydrogen as an etchant and argon as a regulating gas; further depositing the carbon paper for 20min at 1000 ℃ by taking methane as deposition gas, thereby obtaining carbon fiber paper; and graphitized for 30 minutes at 2500 ℃. The performance parameters of the carbon fiber paper obtained by the embodiment are as follows: the tensile strength is 35.6MPa, the thermal conductivity is 18.4W/m.K, and the resistivity is 5.6m omega.cm.

Example 3

Taking 3mm short-cut polyacrylonitrile carbon fibers, soaking the carbon fibers in a 14M concentrated nitric acid solution for 10min at normal temperature, and then cleaning and drying the carbon fibers by using clear water to obtain a short-cut carbon fiber raw material for preparing carbon fiber paper; dispersing the chopped carbon fiber raw material in water by using polyoxyethylene as a dispersing agent, papermaking to obtain carbon fiber base paper, impregnating the base paper by using a thermosetting phenolic resin ethanol solution, drying, and hot-pressing at 150 ℃ and 2MPa for 30 min; curing the hot-pressed carbon fiber paper at 200 ℃ for 1 hour, and then putting the carbon fiber paper into a carbonization furnace in an inert atmosphere for carbonization treatment at 1000 ℃ for 1 hour to obtain primary carbon paper; then, etching the surface of the carbon paper for 30 minutes at 1000 ℃ by taking hydrogen as an etchant and argon as a regulating gas; further depositing carbon paper for 30min at 900 ℃ by taking propylene as deposition gas, thereby obtaining carbon fiber paper; further graphitizing at 2200 ℃ for 30 minutes. The performance parameters of the carbon fiber paper obtained by the embodiment are as follows: tensile strength 39.3MPa, thermal conductivity 19.9W/m.K, resistivity 5.7m omega.cm.

Example 4

Taking 4mm short-cut polyacrylonitrile carbon fibers, soaking in a 14M concentrated nitric acid solution at normal temperature for 30min, then cleaning with clear water, and drying to obtain the short-cut carbon fiber raw material for preparing the carbon fiber paper; dispersing the chopped carbon fiber raw material in water by using polyoxyethylene as a dispersing agent, papermaking to obtain carbon fiber base paper, impregnating the base paper by using a thermosetting phenolic resin ethanol solution, drying, and hot-pressing at 160 ℃ and 1.3MPa for 30 min; curing the hot-pressed carbon fiber paper at 200 ℃ for 1 hour, and then putting the carbon fiber paper into a carbonization furnace in an inert atmosphere for carbonization treatment at 1000 ℃ for 1 hour to obtain primary carbon paper; then, etching the surface of the carbon paper for 10 minutes at 800 ℃ by taking hydrogen as an etchant and argon as a regulating gas; further depositing the carbon paper for 10min at 900 ℃ by taking propylene as a deposition gas, thereby obtaining carbon fiber paper; further graphitizing for 30 minutes at 2500 ℃. The performance parameters of the carbon fiber paper obtained by the embodiment are as follows: the tensile strength is 36.2MPa, the thermal conductivity is 18.5W/m.K, and the resistivity is 5.9m omega.cm.

Example 5

Soaking 8mm short-cut polyacrylonitrile carbon fibers in 6M NaOH solution at normal temperature for 40min, then cleaning with clear water, and drying to obtain the short-cut carbon fiber raw material for preparing the carbon fiber paper; dispersing the chopped carbon fiber raw material in water by using polyoxyethylene as a dispersing agent, papermaking to obtain carbon fiber base paper, impregnating the base paper by using a thermosetting phenolic resin ethanol solution, drying, and hot-pressing at 180 ℃ and 0.2MPa for 30 min; curing the hot-pressed carbon fiber paper at 200 ℃ for 1 hour, and then putting the carbon fiber paper into a carbonization furnace in an inert atmosphere for carbonization treatment at 1000 ℃ for 1 hour to obtain primary carbon paper; then, etching the surface of the carbon paper for 50 minutes at 1000 ℃ by taking hydrogen as an etchant and argon as a regulating gas; further depositing carbon paper for 30min at 950 ℃ by taking methane as deposition gas, thereby obtaining carbon fiber paper; further graphitizing at 2700 ℃ for 30 minutes. The performance parameters of the carbon fiber paper obtained by the embodiment are as follows: the tensile strength is 37.9MPa, the thermal conductivity is 20.2W/m.K, and the resistivity is 5.6m omega.cm.

According to the preferred embodiment and the comparative proportion, the porous graphene structure is etched on the surface of the primary carbon paper by adopting hydrogen, so that the mechanical property of the carbon paper after chemical vapor deposition is greatly improved, and the heat conduction and the electric conductivity are also improved. The carbon fiber paper prepared by the method belongs to a high-strength product.

According to the method for forming the graphene holes with the diameter of 20-40 nanometers and the depth of 5-10 nanometers by etching the surface of the carbon fiber with hydrogen, carbon compounded by subsequent chemical vapor deposition grows in the holes like tree planting, so that several kinds of carbon can be effectively riveted together, and the interface bonding capability of the carbon fiber composite material can be remarkably improved. Moreover, the graphene-like structure at the edge of the graphene pore has an induced graphitization effect on a subsequent new graphite structure of carbon (such as deposited carbon), and is very favorable for the electric conduction and heat conduction performance of the carbon paper.

Although the preferred embodiments of the present invention have been described, the present invention is not limited to the above-mentioned embodiments, which are only illustrative and not restrictive, and those skilled in the art can make various modifications without departing from the spirit and scope of the present invention, which falls within the protection scope of the present invention.