A method for preparing carbon fiber paper

Abstract

The present application relates to a method for preparing carbon fiber paper, and relates to the technical field of carbon fiber paper. A paper blank is prepared, and a reinforcing fiber is formed into a gram weight of 10-30 g / cm 2 The fiber net is combined with the carbon fiber and the fiber net to obtain a combined net; curing, impregnating the combined net with a resin solution, drying, hot pressing and curing to obtain carbon paper impregnated and cured paper; heat treatment, placing the impregnated and cured paper in a carbonization furnace and a graphitization furnace in turn for heat treatment to obtain a finished carbon fiber paper. The present application has the advantage of high mechanical strength.

Description

Technical Field

[0001] The present application relates to the technical field of carbon fiber paper, and in particular to a method for preparing carbon fiber paper. Background Art

[0002] Fuel cells are a clean, efficient green energy device that uses renewable energy such as hydrogen and methane to replace conventional fossil fuels. They are considered to be the most promising environmentally friendly energy. Fuel cells can be divided into alkaline fuel cells, phosphoric acid fuel cells, solid oxide fuel cells and proton exchange membrane fuel cells according to the type of electrolyte. Among them, proton exchange membrane fuel cells (PEMFC) have the advantages of fast start-up speed, low operating temperature and long service life, and are widely used in transportation, power plants, portable mobile power sources and other fields. The core components of PEMFC are: bipolar plates, flow channels, cathode / anode gas diffusion layers, cathode / anode catalyst layers and proton exchange membranes. At present, except for gas diffusion layer materials, other components of PEMFC have been domestically produced. The gas diffusion layer requires materials with high conductivity, high porosity, high strength, corrosion resistance and other characteristics. Carbon paper is currently recognized as a good gas diffusion layer matrix material.

[0003] Carbon fiber paper, also known as carbon paper, is a functional paper with a certain fiber content. Its conventional preparation method is to mix chopped fibers and a binder through a wet molding technology, and obtain a functional paper that can be used for the gas diffusion layer of a fuel cell through processes such as resin impregnation, hot pressing and curing, carbonization, and graphitization. Carbon paper has a porous structure because chopped carbon fibers overlap each other to form a conductive network skeleton, which can meet the functional requirements of PEMFC such as transmitting reaction gases and discharging reaction water. However, when carbon paper is prepared using wet molding technology, since chopped carbon fibers (3-15mm) cannot be effectively bent and filamented during papermaking, the carbon paper only relies on the mechanical interlocking of the binder and a small amount of fibers, and its mechanical strength is low. Summary of the invention

[0004] In view of the shortcomings of the prior art, one of the purposes of the present application is to provide a method for preparing carbon fiber paper, which has the advantage of high mechanical strength.

[0005] The above-mentioned purpose of the present application is achieved through the following technical solutions:

[0006] A method for preparing carbon fiber paper, comprising preparing a paper blank, forming a reinforcing fiber into a paper having a gram weight of 10-30 g / cm 2 The fiber web is prepared by combining the carbon fiber and the fiber web to obtain a combined web; curing, impregnating the combined web with a resin solution, and then drying and hot-pressing and curing to obtain carbon paper impregnated and cured paper; heat treatment, placing the impregnated and cured paper in a carbonization furnace and a graphitization furnace in turn for heat treatment to obtain a finished carbon fiber paper.

[0007] In a preferred example, the present application can be further configured as follows: the fiber web is disposed on a metal filter screen of a papermaking machine, and when the papermaking machine makes paper with carbon fibers, the carbon fibers and the fiber web are combined.

[0008] In a preferred example, the present application can be further configured as follows: the length of the carbon fiber is 3-12 mm, and the diameter is 5-8 μm.

[0009] In a preferred example, the present application can be further configured as follows: the reinforcing fiber is pre-oxidized fiber.

[0010] In a preferred example, the present application can be further configured as follows: the pre-oxidized yarn is one or more of polyacrylonitrile-based, asphalt-based, and viscose-based fibers.

[0011] In a preferred example, the present application can be further configured as follows: the length of the reinforcing fiber is 50-80 mm.

[0012] In a preferred example, the present application can be further configured as follows: the resin in the resin solution is selected from one or more of phenolic resin, epoxy resin, furan resin, and unsaturated polyester resin, and the solubility of the resin solution is 5wt%-25wt%.

[0013] In a preferred example, the present application can be further configured as follows: the carbonization treatment temperature is 800°C-1600°C, the carbonization treatment heating rate is 5-50°C / min, and the insulation time is 0.5-2h.

[0014] In a preferred example, the present application can be further configured as follows: the graphitization treatment temperature is 1900-2400°C, the graphitization treatment heating rate is 10-100°C / min, and the insulation time is 0.5-1.5h.

[0015] In a preferred example, the present application can be further configured as follows: the temperature of hot pressing curing is 140-200°C, the pressure is 1-15MPa, and the time is 20-60min.

[0016] This application has the following advantages:

[0017] 1. The pre-oxidized wire mesh reinforces the chopped carbon fiber paper blank and improves the mechanical strength of the carbon paper.

[0018] 2. The pre-oxidized filaments are long and bendable, providing more overlapping points and connecting lines for the conductive network skeleton of the carbon paper, thus improving the electrical and thermal conductivity of the carbon paper.

[0019] 3. The method of using pre-oxidized wire mesh to enhance the strength of carbon paper is simple to operate, convenient for industrial production, and beneficial to the mass preparation and application of high-performance, low-cost carbon paper for fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the preparation process of the carbon fiber paper of the present application.

[0021] Figure 2 It is a microstructure diagram of the carbon fiber paper of the present application. DETAILED DESCRIPTION

[0022] The present application is further described in detail below in conjunction with the accompanying drawings.

[0023] Reference Figure 1 and Figure 2 , is a method for preparing carbon fiber paper disclosed in the present application, preparing a paper blank, forming a reinforcing fiber with a gram weight of 10-30g / cm 2 The fiber web is prepared by combining the carbon fiber and the fiber web to obtain a combined web; curing, impregnating the combined web with a resin solution, and then drying and hot-pressing and curing to obtain carbon paper impregnated and cured paper; heat treatment, placing the impregnated and cured paper in a carbonization furnace and a graphitization furnace in turn for heat treatment to obtain a finished carbon fiber paper.

[0024] More specifically, (1) the carbon fiber filaments are cut into a certain length using a fiber chopper, and then the carbon fiber is placed in a high-temperature furnace and heat treated at 600°C for 1 hour in an air atmosphere to remove the sizing agent (such as epoxy resin) on the surface of the carbon fiber. At the same time, hydrophilic oxygen-containing functional groups such as hydroxyl and carboxyl are introduced onto the fiber surface to improve the hydrophilicity of the fiber.

[0025] (2) Add the pretreated carbon fiber into water and a dispersant, stir and disperse, add a certain amount of polyvinyl alcohol after stirring for a period of time, and continue stirring for a certain period of time to obtain a carbon fiber papermaking slurry.

[0026] (3) A fiber mesh (pre-oxidized wire mesh) is laid on the metal filter of the papermaking machine, and then the carbon fiber papermaking slurry is poured into the papermaking machine, and the paper is drained to obtain a combined mesh (carbon fiber paper blank reinforced with a pre-oxidized wire mesh).

[0027] (4) The combined web (wet paper blank) is placed in an oven to dry out the moisture, and then impregnated with a thermosetting resin solution of a certain concentration (prepared by dissolving the resin in an ethanol solution). After impregnation, the web is placed in an oven to dry out the solvent (i.e., the ethanol in the resin solution), and the resin is allowed to enter a semi-cured state, thereby obtaining carbon fiber impregnated paper.

[0028] (5) Put the carbon fiber impregnated paper into a hot press, set the hot pressing temperature, pressure and time of the hot press, and obtain the carbon fiber impregnated cured paper after the resin is cured.

[0029] (6) placing the carbon fiber impregnated paper into a carbonization furnace for carbonization treatment, and then placing the carbon paper into a graphitization furnace for graphitization treatment to obtain a finished carbon paper.

[0030] In step (1), the length of the chopped carbon fibers is 3-12 mm, and the fiber diameter is 5-8 μm.

[0031] The dispersant in step (2) includes but is not limited to polyethylene oxide, polyacrylamide, sodium carboxymethyl cellulose, etc.

[0032] In step (2), the proportion of the dispersant is 0.0025wt%-0.01wt%, and the proportion of the polyvinyl alcohol is 0.05wt%-0.1wt%.

[0033] In step (2), the first stirring time is 5-10 minutes, and the second stirring time is 3-6 minutes.

[0034] The pre-oxidized wire mesh mat in step (3) is a fiber mesh mat obtained by mechanically combing one or more of polyacrylonitrile-based, asphalt-based, and viscose-based fibers using a carding machine.

[0035] The length of the pre-oxidized silk fibers in the pre-oxidized silk screen in step (3) is 50-80 mm.

[0036] The weight of the pre-oxidized wire mesh in step (3) is 10-30 g / cm 2 .

[0037] The resin in step (4) is selected from one or more of phenolic resin, epoxy resin, furan resin and unsaturated polyester resin.

[0038] The concentration of the resin solution in step (4) is 5wt%-25wt%.

[0039] In step (4), the drying temperature is 60-100° C. and the drying time is 20-60 min.

[0040] In step (5), the temperature of hot pressing curing is 140-200° C., the pressure is 1-15 MPa, and the time is 20-60 min.

[0041] In step (6), the carbonization furnace includes a single carbonization furnace and a continuous carbonization furnace, and the carbonization gas atmosphere is nitrogen. The graphitization furnace includes a single graphitization furnace and a continuous graphitization furnace, and the graphitization gas atmosphere is nitrogen.

[0042] In step (6), the carbonization treatment temperature is 800°C-1600°C, preferably 1200°C-1400°C, the carbonization treatment heating rate is 5-50°C / min, and the insulation time is 0.5-2h.

[0043] In step (6), the graphitization treatment temperature is 1900-2400°C, preferably 2200°C, the graphitization treatment heating rate is 10-100°C / min, and the insulation time is 0.5-1.5h.

[0044] Embodiment 1:

[0045] (1) The carbon fiber filaments were cut into 6 mm lengths using a fiber chopper, and then placed in a high-temperature furnace for heat treatment at 600 °C for 1 h in an air atmosphere to remove the sizing agent on the surface of the carbon fiber and introduce oxygen-containing functional groups on the fiber surface to improve the hydrophilicity of the fiber.

[0046] (2) 4.32 g of pretreated carbon fiber was added to 12 L of water, and 0.32 g of dispersant polyethylene oxide was added at the same time, and the mixture was stirred and dispersed. After stirring for 5 min, a certain amount of 8 g of polyvinyl alcohol was added, and stirring was continued for 5 min to obtain carbon fiber papermaking slurry.

[0047] (3) On a papermaking area of ​​30 cm 2 The metal filter is covered with a weight of 10g / cm 2 Pre-oxidize the wire mesh tire, then pour the carbon fiber papermaking slurry into the papermaking machine, drain the water and make paper to obtain the carbon fiber paper blank reinforced by the pre-oxidized wire mesh tire.

[0048] (4) The wet paper blank is placed in an oven at 100° C. and baked for 30 minutes to dry out the moisture, and then impregnated with a 10 wt% phenolic resin ethanol solution. After impregnation, the paper blank is placed in an oven at 90° C. and baked for 30 minutes to dry out the solvent and allow the resin to enter a semi-cured state, thereby obtaining carbon fiber impregnated paper.

[0049] (5) The carbon fiber impregnated paper is placed on a hot press at 160°C, 3MPa, and 30min. After the resin is cured and formed, the carbon fiber impregnated cured paper is obtained.

[0050] (6) placing the carbon fiber impregnated paper into a continuous carbonization furnace for carbonization treatment at a temperature of 1600° C. After carbonization, placing the carbon paper into a graphitization furnace for graphitization treatment at a temperature of 2200° C. to obtain a finished carbon paper.

[0051] Embodiment 2:

[0052] (1) The carbon fiber filaments were cut into 6 mm lengths using a fiber chopper, and then the carbon fiber was placed in a high temperature furnace and heat treated at 600 °C for 1 h in an air atmosphere.

[0053] (2) 4.32 g of pretreated carbon fiber was added to 12 L of water, and 0.32 g of dispersant polyethylene oxide was added at the same time, and the mixture was stirred and dispersed. After stirring for 5 min, a certain amount of 8 g of polyvinyl alcohol was added, and stirring was continued for 5 min to obtain carbon fiber papermaking slurry.

[0054] (3) On a papermaking area of ​​30 cm 2 The metal filter is covered with a weight of 20g / cm 2Pre-oxidize the wire mesh tire, then pour the carbon fiber papermaking slurry into the papermaking machine, drain the water and make paper to obtain the carbon fiber paper blank reinforced by the pre-oxidized wire mesh tire.

[0055] (4) The wet paper blank is placed in an oven at 100° C. and baked for 30 minutes to dry out the moisture, and then impregnated with a 10 wt% phenolic resin ethanol solution. After impregnation, the paper blank is placed in an oven at 90° C. and baked for 30 minutes to dry out the solvent and allow the resin to enter a semi-cured state, thereby obtaining carbon fiber impregnated paper.

[0056] (5) The carbon fiber impregnated paper is placed on a hot press at 160°C, 3MPa, and 30min. After the resin is cured and formed, the carbon fiber impregnated cured paper is obtained.

[0057] (6) placing the carbon fiber impregnated paper into a continuous carbonization furnace for carbonization treatment at a temperature of 1600° C. After carbonization, placing the carbon paper into a graphitization furnace for graphitization treatment at a temperature of 2200° C. to obtain a finished carbon paper.

[0058] Embodiment 3:

[0059] (1) The carbon fiber filaments were cut into 6 mm lengths using a fiber chopper, and then the carbon fiber was placed in a high temperature furnace and heat treated at 600 °C for 1 h in an air atmosphere.

[0060] (2) 4.32 g of pretreated carbon fiber was added to 12 L of water, and 0.32 g of dispersant polyethylene oxide was added at the same time, and the mixture was stirred and dispersed. After stirring for 5 min, a certain amount of 8 g of polyvinyl alcohol was added, and stirring was continued for 5 min to obtain carbon fiber papermaking slurry.

[0061] (3) On a papermaking area of ​​30 cm 2 The metal filter is covered with a weight of 30g / cm 2 Pre-oxidize the wire mesh tire, then pour the carbon fiber papermaking slurry into the papermaking machine, drain the water and make paper to obtain the carbon fiber paper blank reinforced by the pre-oxidized wire mesh tire.

[0062] (4) The wet paper blank is placed in an oven at 100° C. and baked for 30 minutes to dry out the moisture, and then impregnated with a 10 wt% phenolic resin ethanol solution. After impregnation, the paper blank is placed in an oven at 90° C. and baked for 30 minutes to dry out the solvent and allow the resin to enter a semi-cured state, thereby obtaining carbon fiber impregnated paper.

[0063] (5) The carbon fiber impregnated paper is placed on a hot press at 160°C, 3MPa, and 30min. After the resin is cured and formed, the carbon fiber impregnated cured paper is obtained.

[0064] (6) placing the carbon fiber impregnated paper into a continuous carbonization furnace for carbonization treatment at a temperature of 1600° C. After carbonization, placing the carbon paper into a graphitization furnace for graphitization treatment at a temperature of 2200° C. to obtain a finished carbon paper.

[0065] The following table shows some properties of carbon paper prepared in three examples:

[0066]

[0067] The implementation principle of this embodiment is: the short-cut carbon fiber paper blank is reinforced by pre-oxidized wire mesh, thereby improving the mechanical strength of the carbon paper.

[0068] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing carbon fiber paper, characterized in that: Prepare the paper blank and form the reinforcing fiber into a gram weight of 10-30g / cm 2 The fiber web is formed, the carbon fiber and the fiber web are combined to obtain a combined web; curing, the combined web is impregnated with a resin solution, and then dried and hot-pressed to obtain a carbon paper impregnated and cured paper; Heat treatment, the impregnated and cured paper is sequentially placed in a carbonization furnace and a graphitization furnace for heat treatment to obtain a finished carbon fiber paper; the fiber mesh is arranged on a metal filter screen of a papermaking machine, and when the papermaking machine makes paper with the carbon fiber, the carbon fiber and the fiber mesh are combined; the reinforcing fiber is a pre-oxidized fiber.

2. The method for preparing carbon fiber paper according to claim 1, characterized in that: The length of the carbon fiber is 3-12 mm and the diameter is 5-8 μm.

3. The method for preparing carbon fiber paper according to claim 1, characterized in that: The pre-oxidized yarn is one or more of polyacrylonitrile-based, asphalt-based and viscose-based fibers.

4. The method for preparing carbon fiber paper according to claim 1, characterized in that: The length of the reinforcing fiber is 50-80 mm.

5. The method for preparing carbon fiber paper according to claim 1, characterized in that: The resin in the resin solution is selected from one or more of phenolic resin, epoxy resin, furan resin, and unsaturated polyester resin, and the solubility of the resin solution is 5wt%-25wt%.

6. The method for preparing carbon fiber paper according to claim 1, characterized in that: The carbonization treatment temperature is 800°C-1600°C, the carbonization treatment heating rate is 5-50°C / min, and the insulation time is 0.5-2h.

7. The method for preparing carbon fiber paper according to claim 1, characterized in that: The graphitization treatment temperature is 1900-2400°C, the graphitization treatment heating rate is 10-100°C / min, and the insulation time is 0.5-1.5h.

8. The method for preparing carbon fiber paper according to claim 1, characterized in that: The temperature of hot pressing curing is 140-200°C, the pressure is 1-15MPa, and the time is 20-60min.

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