Method for preparing carbon fiber insulation felt through spraying-needling

Abstract

The invention provides a method for preparing a carbon fiber insulation felt by spraying-needling, which comprises the following steps: taking carbon fiber pre-oxidized fiber as a raw material, paving the raw material into a fiber layer net blank, spraying a spraying liquid containing a binder and a lubricant on the surface of the fiber layer net blank, stacking multiple layers of fiber layer net blanks in an up-and-down staggered manner, then performing needling molding, and finally performing carbonization-high-temperature treatment, thereby obtaining the carbon fiber insulation felt. The carbon fiber insulation felt is obtained. Wherein the surfaces of the carbon fiber pre-oxidized fibers have hydrophilic functional groups, so that the spraying liquid can better wet the fiber layer net blank; the lubricant in the spraying liquid can reduce the damage to the carbon fiber pre-oxidized fiber during needling; the multiple sprayed fiber layer net blanks are stacked in an up-down staggered mode and formed through needling, the lap joint strength between the fiber layer net blanks can be effectively improved, and the overall strength of the heat preservation felt is improved. The carbon fiber insulation felt prepared by the method has the advantages of low density, low heat conductivity coefficient and good comprehensive mechanical property, and can be used as a heat insulation material in high-temperature furnaces such as a crystalline silicon high-temperature furnace and a vapor deposition furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber felt manufacturing, and in particular relates to a method for preparing carbon fiber thermal insulation felt by spraying and needling. Background Art

[0002] With the advancement of science and technology, the demand for thermal insulation materials in many fields of the national economy, such as military, national defense, metallurgy, and chemical industry, has grown rapidly, and higher requirements have been put forward for the performance standards of thermal insulation materials; lightweight carbon fiber felt has the advantages of low thermal conductivity, low thermal expansion coefficient, high purity, good mechanical properties, and high temperature resistance, and is widely used in high-temperature equipment such as solar silicon furnaces and semiconductor crystal growth furnaces.

[0003] At present, the preparation of carbon fiber insulation felt mainly relies on pre-oxidized filaments or carbon filaments, which are completed through non-woven technology. In this process, some challenges and problems arise: (1) Due to the inertness and hydrophobicity of the carbon fiber surface, it is difficult to be well infiltrated by the adhesive, resulting in insufficient contact between the adhesive and the carbon fiber, thereby reducing the bonding between the carbon fibers in the carbon fiber insulation felt, causing the bonding joint to easily debond or break when subjected to force, thereby reducing the overall strength of the carbon fiber insulation felt; (2) When the carbon fiber insulation felt is carbonized, the bonding between the carbon fibers is poor due to the large difference in carbonization shrinkage between the adhesive and the carbon fiber; (3) Due to the brittleness of the carbon fiber, it is easy to cause fiber breakage during needle punching, affecting the performance of the carbon fiber insulation felt; and a large amount of debris will be generated, polluting the heat field; (4) The soft carbon felt insulation material commonly used in high-temperature vacuum furnaces is usually prepared by stacking and bonding multiple layers of thin felt together through a multi-layer bonding method. However, this soft carbon felt is prone to cracking and delamination during use, which affects its service life. (5) The interior of the needle-punched preform contains many pores of different sizes. During the resin impregnation and curing process, the resin distribution is poorly uniform. This uneven filling phenomenon causes the density of the final product to be uneven.

[0004] Therefore, how to prepare a carbon fiber thermal insulation felt with good thermal insulation, high strength and long service life is a problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for preparing carbon fiber thermal insulation felt by spraying-needling, which has simple process, convenient operation and is suitable for industrial production. The material prepared by the method has the characteristics of low density, low thermal conductivity and high mechanical strength, so it can be widely used in thermal insulation of high temperature furnaces such as crystalline silicon high temperature furnaces, vapor deposition furnaces, etc.

[0006] A method for preparing carbon fiber thermal insulation felt by spraying and needling, comprising the following steps:

[0007] (1) using a carding machine and an air-laying machine to lay the short-cut carbon fiber preoxidized yarn into a fiber layer web embryo;

[0008] (2) mixing a binder, an organic solvent, and a lubricant to obtain a spray liquid, heating the mixture, and then spraying the heated spray liquid evenly onto the fiber layer web embryo through a porous nozzle;

[0009] (3) stacking a plurality of sprayed fiber layer webs with their boundaries as reference, and then performing needle punching reinforcement to obtain a carbon fiber pre-oxidized felt;

[0010] (4) The carbon fiber pre-oxidized felt is flattened and dried, and then carbonized and subjected to high temperature treatment to obtain the carbon fiber thermal insulation felt.

[0011] In the above step (1):

[0012] Preferably, the carbon fiber preoxidized yarn is prepared by preoxidizing the carbon fiber precursor in a preoxidation furnace under air atmosphere at 300-400° C. for 2-3 hours.

[0013] During the pre-oxidation process, the air flow rate can be selected to be 10 L / min.

[0014] Preferably, the carbon fiber preoxidized yarn is one of polyacrylonitrile-based carbon fiber preoxidized yarn, viscose-based carbon fiber preoxidized yarn, and asphalt-based carbon fiber preoxidized yarn, and more preferably, polyacrylonitrile-based carbon fiber preoxidized yarn.

[0015] Preferably, the length of the chopped carbon fiber pre-oxidized filaments is 30 to 50 mm.

[0016] In the above step (2):

[0017] After the binder, organic solvent and lubricant are uniformly mixed, preferably further stirred to prepare a spraying liquid. The stirring time is 25 to 30 minutes.

[0018] Preferably, the binder is one of phenolic resin, epoxy resin, urea-formaldehyde resin and acrylic resin, and more preferably phenolic resin.

[0019] Preferably, the organic solvent is ethanol, and more preferably anhydrous ethanol.

[0020] Preferably, the lubricant is one of polyethylene glycol and glycerol, and more preferably polyethylene glycol.

[0021] Preferably, in the spraying liquid, the mass ratio of the binder, the organic solvent, and the lubricant is (20-50): (30-60): (2-15). More preferably, it is (25-40): (40-50): (5-10). Even more preferably, it is (35-40): (43-47): (5-8).

[0022] Preferably, the heating temperature of the spraying liquid is 50 to 80°C.

[0023] As a preferred embodiment, the spraying amount of the spraying liquid on the fiber layer web is 2 to 6 g / m 2 More preferably, it is 4 to 6 g / m 2 More preferably, it is 4.5 to 5.5 g / m 2 .

[0024] In the above step (3):

[0025] When the fiber layer webs are stacked in an up-down staggered manner, the staggered angle can be selected as required, and the multiple fiber layer webs are sequentially staggered clockwise or counterclockwise from bottom to top.

[0026] In the above step (4):

[0027] Preferably, the drying temperature of the carbon fiber pre-oxidized felt after flattening is 120-150°C, and the drying time is 1-3 hours. More preferably, the drying temperature is 120-130°C, and the drying time is 2-3 hours. More preferably, the drying temperature is 120°C, and the drying time is 3 hours.

[0028] Preferably, the carbonization-high temperature treatment is carried out under the protection of an inert gas, which may be nitrogen or argon.

[0029] Preferably, the specific process of carbonization-high temperature treatment is:

[0030] The dried carbon fiber pre-oxidized felt is first kept at a temperature of 200-300°C for 3-5h, then heated to 700-800°C for 2-4h, then heated to 1000-1200°C for 4-6h, then heated to 1800-2000°C for 4-6h, and finally naturally cooled to room temperature.

[0031] As a specific preference, the process of carbonization-high temperature treatment is:

[0032] Under the protection of inert gas, the dried carbon fiber pre-oxidation felt was first kept at 200°C for 3 hours, then heated to 700°C for 3 hours, then heated to 1000°C for 4 hours, then heated to 1800°C for 4 hours, and finally naturally cooled to room temperature.

[0033] The method for preparing carbon fiber thermal insulation felt by spraying and needling of the present invention is that carbon fiber preoxidized filaments are used as raw materials and laid into fiber layer web embryos, and a spraying liquid containing a binder and a lubricant is sprayed on the surface of the fiber layer web embryos at the same time, and multiple layers of fiber layer web embryos are stacked up and down and then needle-punched into shape, and finally carbonized and treated at high temperature to obtain carbon fiber thermal insulation felt. Among them, the surface of the carbon fiber preoxidized filaments has hydrophilic functional groups, so that the spraying liquid can better wet the fiber layer web embryos; the lubricant in the spraying liquid can reduce the damage to the carbon fiber preoxidized filaments during needle-punching; multiple sprayed fiber layer web embryos are stacked up and down and needle-punched into shape, which can effectively improve the overlap strength between the fiber layer web embryos and improve the overall strength of the thermal insulation felt. The carbon fiber thermal insulation felt prepared by the method of the present invention has low density, low thermal conductivity, and good comprehensive mechanical properties. It can be used as a thermal insulation material in high-temperature furnaces such as crystalline silicon high-temperature furnaces and vapor deposition furnaces.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) In the method for preparing carbon fiber thermal insulation felt by spraying and needling of the present invention, the selected carbon fiber pre-oxidized filaments have abundant functional groups (carboxyl, hydroxyl, etc.) on the surface and have a certain hydrophilicity, so that the spray liquid has good wettability on the surface; because the binder and the carbon fiber pre-oxidized filaments must undergo a carbonization process, the carbon layer structure formed by the carbonaceous binder is closely connected with the edge of the carbon fiber, which can significantly improve the mechanical properties of the system and is conducive to achieving a better combination of the fiber and the binder.

[0036] (2) The method of preparing carbon fiber thermal insulation felt by spraying-needling punching of the present invention has obvious advantages in process efficiency, and the spraying process can make the binder achieve rapid and uniform distribution, thereby shortening the production cycle and improving production efficiency; it can achieve precise material application, reduce material waste, and will not be limited by the shape of the material; in addition, the lubricant is added to the spray liquid, which can reduce the friction and damage between the needle and the carbon fiber pre-oxidized filament during the needling process, reduce the breakage of the fiber during the needling and the generation of a large amount of debris, and obtain a relatively pure carbon fiber felt.

[0037] (3) The method for preparing carbon fiber thermal insulation felt by spraying and needling of the present invention is to obtain carbon fiber preoxidized felt by stacking carbon fiber preoxidized fiber layer webs in an offset manner up and down and then reinforcing them by needling, so as to ensure that the carbon fiber preoxidized fiber layer webs have sufficient lap strength and the layers are not easily cracked.

[0038] The method for preparing carbon fiber thermal insulation felt by spraying-needling can produce thermal insulation materials with low density, low thermal conductivity, small heat capacity and high mechanical properties, and the method is simple to operate and has high process stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a process flow chart of Example 1 of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] In the following examples, polyacrylonitrile-based carbon fiber preoxidized yarns are prepared by the following steps:

[0042] The polyacrylonitrile-based precursor was prepared by pre-oxidation at 350°C for 2.5 hours in a pre-oxidation furnace under an air (intake volume 10 L / min) atmosphere.

[0043] Example 1

[0044] like Figure 1 As shown, a method for preparing carbon fiber thermal insulation felt by spraying and needling comprises the following steps:

[0045] Step 1: lay polyacrylonitrile-based carbon fiber preoxidized yarn with a length of 30 mm through a carding machine and an air-laying machine to form a polyacrylonitrile-based carbon fiber preoxidized fiber layer web embryo; and cut the fiber layer web embryo into the same size;

[0046] Step 2: Evenly mix phenolic resin, anhydrous ethanol and polyethylene glycol in a mass ratio of 40:45:5, and stir for 30 minutes to obtain a spraying liquid;

[0047] Step 3: Heat the spraying liquid prepared in step 2 to 60°C, and spray it evenly on the surface of the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web prepared in step 1 through a porous nozzle to ensure that the spraying liquid completely covers the surface of each polyacrylonitrile-based carbon fiber pre-oxidized fiber; wherein the spraying amount of the spraying liquid on the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web after spraying is 5.5g / m 2 ;

[0048] Step 4: The polyacrylonitrile-based carbon fiber pre-oxidized fiber layer webs sprayed in step 3 are stacked together by rotating 60° clockwise with the border of the webs as the reference, and are needle-punched and reinforced by a needle punching machine to obtain a 2.5 cm thick carbon fiber pre-oxidized felt;

[0049] Step 5: Place the carbon fiber pre-oxidized felt obtained in step 4 into a press to flatten it, and dry it in an oven at 120° C. for 3 hours;

[0050] Step six, under the protection of inert gas (nitrogen), keep the carbon fiber pre-oxidation felt after the drying treatment in step five at 200°C for 3 hours, then heat it to 700°C and keep it for 3 hours, then heat it to 1000°C and keep it for 4 hours, then heat it to 1800°C and keep it for 4 hours, and finally cool it naturally to room temperature to obtain the insulation material for high temperature furnace, i.e., carbon fiber insulation felt.

[0051] Example 2

[0052] A method for preparing carbon fiber thermal insulation felt by spraying and needling, comprising the following steps:

[0053] Step 1: lay polyacrylonitrile-based carbon fiber preoxidized yarn with a length of 40 mm through a carding machine and an air-laying machine to form a polyacrylonitrile-based carbon fiber preoxidized fiber layer web embryo; and cut the fiber layer web embryo into the same size;

[0054] Step 2: Evenly mix phenolic resin, anhydrous ethanol and polyethylene glycol in a mass ratio of 35:45:6, and stir for 30 minutes to obtain a spraying liquid;

[0055] Step 3: Heat the spraying liquid prepared in step 2 to 60°C, and spray it evenly on the surface of the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web prepared in step 1 through a porous nozzle to ensure that the spraying liquid completely covers the surface of each polyacrylonitrile-based carbon fiber pre-oxidized fiber; wherein the spraying amount of the spraying liquid on the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web after spraying is 5g / m 2 ;

[0056] Step 4: The polyacrylonitrile-based carbon fiber pre-oxidized fiber layer webs sprayed in step 3 are stacked together by rotating 90° clockwise with the border of the webs as the reference, and are needle-punched and reinforced by a needle punching machine to obtain a 2.5 cm thick carbon fiber pre-oxidized felt;

[0057] Step 5: Place the carbon fiber pre-oxidized felt obtained in step 4 into a press to flatten it, and dry it in an oven at 120° C. for 3 hours;

[0058] Step six, under the protection of inert gas (nitrogen), keep the carbon fiber pre-oxidation felt after the drying treatment in step five at 200°C for 3 hours, then heat it to 700°C and keep it for 3 hours, then heat it to 1000°C and keep it for 4 hours, then heat it to 1800°C and keep it for 4 hours, and finally cool it naturally to room temperature to obtain the insulation material for high temperature furnace, i.e., carbon fiber insulation felt.

[0059] Example 3

[0060] A method for preparing carbon fiber thermal insulation felt by spraying and needling, comprising the following steps:

[0061] Step 1: lay polyacrylonitrile-based carbon fiber preoxidized yarn with a length of 50 mm through a carding machine and an air-laying machine to form a polyacrylonitrile-based carbon fiber preoxidized fiber layer web embryo; and cut the fiber layer web embryo into the same size;

[0062] Step 2: Evenly mix phenolic resin, anhydrous ethanol and polyethylene glycol in a mass ratio of 35:45:8, and stir for 30 minutes to obtain a spraying liquid;

[0063] Step 3: Heat the spraying liquid prepared in step 2 to 70°C, and spray it evenly on the surface of the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web prepared in step 1 through a porous nozzle to ensure that the spraying liquid completely covers the surface of each polyacrylonitrile-based carbon fiber pre-oxidized fiber. The spraying amount of the spraying liquid on the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web after spraying is 4.5g / m 2 ;

[0064] Step 4: The polyacrylonitrile-based carbon fiber pre-oxidized fiber layer webs sprayed in step 3 are stacked together by rotating 120° clockwise with the border of the webs as the reference, and are needle-punched and reinforced by a needle punching machine to obtain a 2.5 cm thick carbon fiber pre-oxidized felt;

[0065] Step 5: Place the carbon fiber pre-oxidized felt obtained in step 4 into a press to flatten it, and dry it in an oven at 120° C. for 3 hours;

[0066] Step six, under the protection of inert gas (nitrogen), keep the carbon fiber pre-oxidized felt after the drying treatment in step five at 200°C for 3 hours, then heat it to 700°C and keep it for 3 hours, then heat it to 1000°C and keep it for 4 hours, then heat it to 2000°C and keep it for 4 hours, and finally cool it naturally to room temperature to obtain the insulation material for high temperature furnace, i.e., carbon fiber insulation felt.

[0067] Example 4

[0068] A method for preparing carbon fiber thermal insulation felt by spraying and needling, comprising the following steps:

[0069] Step 1: lay polyacrylonitrile-based carbon fiber preoxidized yarn with a length of 50 mm through a carding machine and an air-laying machine to form a polyacrylonitrile-based carbon fiber preoxidized fiber layer web embryo; and cut the fiber layer web embryo into the same size;

[0070] Step 2: Evenly mix phenolic resin, anhydrous ethanol and polyethylene glycol in a mass ratio of 40:45:8, and stir for 30 minutes to obtain a spraying liquid;

[0071] Step 3: Heat the spraying liquid prepared in step 2 to 80°C, and spray it evenly on the surface of the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web prepared in step 1 through a porous nozzle to ensure that the spraying liquid completely covers the surface of each polyacrylonitrile-based carbon fiber pre-oxidized fiber. The spraying amount of the spraying liquid on the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer web after spraying is 4.5g / m 2 ;

[0072] Step 4: The polyacrylonitrile-based carbon fiber pre-oxidized fiber layer webs sprayed in step 3 are stacked together by rotating 150° clockwise with the border of the webs as the reference, and are needle-punched and reinforced by a needle punching machine to obtain a 2.5 cm thick carbon fiber pre-oxidized felt;

[0073] Step 5: Place the carbon fiber pre-oxidized felt obtained in step 4 into a press to flatten it, and dry it in an oven at 120° C. for 3 hours;

[0074] Step six, under the protection of inert gas (nitrogen), keep the carbon fiber pre-oxidized felt after the drying treatment in step five at 200°C for 3 hours, then heat it to 700°C and keep it for 3 hours, then heat it to 1000°C and keep it for 4 hours, then heat it to 2000°C and keep it for 4 hours, and finally cool it naturally to room temperature to obtain the insulation material for high temperature furnace, i.e., carbon fiber insulation felt.

[0075] Comparative Example 1

[0076] The carbon fiber thermal insulation felt is prepared according to the preparation process of Example 1, with the only difference being that in step 4, the polyacrylonitrile-based carbon fiber pre-oxidized fiber layer mesh embryos are neatly arranged and stacked up and down based on the boundary of the mesh embryo, and are reinforced by needle punching using a needle punching machine.

[0077] Comparative Example 2

[0078] The carbon fiber thermal insulation felt is prepared according to the preparation process of Example 1, except that the preparation of the spraying liquid in steps 2 and 3 and the spraying treatment of the fiber layer web are omitted.

[0079] Performance Testing:

[0080] The density, thermal conductivity and compressive strength of the carbon fiber thermal insulation felts prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were tested respectively. The results are shown in Table 1.

[0081] Among them, the thermal conductivity of carbon fiber insulation felt was tested using Hot Disk TPS2500s heat flow instrument;

[0082] The compressive strength of carbon fiber insulation felt is tested by CTM2500 universal material testing machine. The size of the test sample is 10*10*10mm. 3 , the test rate is 3mm / min.

[0083] Table 1 Performance data of carbon fiber thermal insulation felts obtained in Examples 1 to 4 and Comparative Examples 1 and 2 It can be seen from the data in Table 1 that the carbon fiber thermal insulation felts prepared in Examples 1 to 4 have low density and thermal conductivity, high compressive strength, and good thermal insulation performance and mechanical properties. Comparing the performance data of Example 1 and Comparative Example 1, it can be seen that compared with the neat stacking of the fiber layer mesh embryos, the stacking of the fiber layer mesh embryos up and down with the boundary as the reference and then needle-punching reinforcement can significantly improve the thermal insulation performance and compressive strength of the carbon fiber thermal insulation felt. In addition, comparing the performance data of Example 1 and Comparative Example 2, it can be seen that the use of the spray liquid can effectively improve the compressive strength of the carbon fiber thermal insulation felt, improve its mechanical properties, and ensure its thermal insulation performance.

[0084] It can be seen from Table 1 that the present invention selects carbon fiber preoxidized filaments and binders to undergo synchronous carbonization to make the binder and fiber more tightly bonded; and the binder is evenly distributed by spraying, thereby reducing fiber damage and ash generation during the needling process; and the carbon fiber preoxidized fiber layer webs are stacked and arranged in an offset manner up and down for needling reinforcement, thereby reducing the possibility of cracking between carbon fiber felt layers and improving the mechanical properties of the insulation felt. The high-temperature furnace-suitable carbon fiber insulation felt prepared by the method of the present invention has significant advantages, such as low density, low thermal conductivity, high purity and good mechanical properties. Therefore, this material is very suitable as a thermal insulation material in high-temperature equipment such as crystalline silicon high-temperature furnaces, vapor deposition furnaces, and has broad application prospects.

[0085] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing carbon fiber thermal insulation felt by spraying-needling, characterized in that: The following steps are involved: (1) using a carding machine and an air-laying machine to lay the short-cut carbon fiber preoxidized yarn into a fiber layer web embryo; (2) mixing a binder, an organic solvent, and a lubricant to obtain a spray liquid, heating the mixture, and then spraying the heated spray liquid evenly onto the fiber layer web embryo through a porous nozzle; (3) stacking a plurality of sprayed fiber layer webs with their boundaries as reference, and then performing needle punching reinforcement to obtain a carbon fiber pre-oxidized felt; (4) The carbon fiber pre-oxidized felt is flattened and dried, and then carbonized and subjected to high temperature treatment to obtain the carbon fiber thermal insulation felt.

2. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (1), the carbon fiber preoxidized yarn is one of polyacrylonitrile-based carbon fiber preoxidized yarn, viscose-based carbon fiber preoxidized yarn, and asphalt-based carbon fiber preoxidized yarn; The length of the chopped carbon fiber pre-oxidized filaments is 30 to 50 mm.

3. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (1), the carbon fiber preoxidized yarn is prepared by preoxidizing the carbon fiber precursor in a preoxidation furnace under air atmosphere at 300-400° C. for 2-3 hours.

4. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (2), the binder is one of phenolic resin, epoxy resin, urea-formaldehyde resin, and acrylic resin; The organic solvent is ethanol; The lubricant is one of polyethylene glycol and glycerol.

5. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (2), in the spraying liquid, the mass ratio of the binder, the organic solvent and the lubricant is (20-50):(30-60):(2-15).

6. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (2), the heating temperature of the spraying liquid is 50 to 80°C.

7. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (2), the spraying amount of the spraying liquid on the fiber layer web is 2 to 6 g / m 2 .

8. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (4), the drying temperature of the carbon fiber pre-oxidized felt after flattening is 120-150° C., and the drying time is 1-3 hours.

9. The method for preparing carbon fiber thermal insulation felt by spraying-needling according to claim 1, characterized in that: In step (4), the carbonization-high temperature treatment is carried out under the protection of an inert gas.

10. The method for preparing carbon fiber thermal insulation felt by spraying and needling according to claim 1, characterized in that: In step (4), the specific process of carbonization-high temperature treatment is: The dried carbon fiber pre-oxidized felt is first kept at a temperature of 200-300°C for 3-5h, then heated to 700-800°C for 2-4h, then heated to 1000-1200°C for 4-6h, then heated to 1800-2000°C for 4-6h, and finally naturally cooled to room temperature.

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