High-filling-power carbon-carbon heat preservation hard felt and preparation method thereof

Abstract

The invention provides a high-filling-power carbon-carbon heat-preservation hard felt and a preparation method thereof, and relates to the technical field of carbon fiber heat-preservation felts.The preparation method comprises the following steps that (a) double-face glue spraying is conducted on a shaped carbon fiber net through double-net clamping type glue spraying equipment, then residual glue on the carbon fiber net is removed to control the glue content, and the carbon fiber net is obtained; then part of the solvent on the carbon fiber net is dried and removed through a radiation type drying device, then the remaining solvent on the carbon fiber net is dried and removed through a hot air penetrating type drying oven, meanwhile, the glue is subjected to cross-linking curing, and a reinforced carbon fiber net is obtained; (b) the reinforced carbon fiber net is sequentially subjected to layering hot pressing and carbonization treatment, and the carbon-carbon heat preservation hard felt is obtained. The carbon-carbon heat-preservation hard felt solves the technical problem that an existing carbon-carbon heat-preservation hard felt is poor in heat-preservation performance due to the fact that the number of heat transfer channels is large, and the technical effects that the heat transfer channels are greatly reduced, the porosity is improved, the heat conductivity coefficient is effectively reduced, and therefore the heat-preservation performance of the carbon-carbon heat-preservation hard felt is improved are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber thermal insulation felt, in particular to a high-fluff carbon-carbon thermal insulation hard felt and a preparation method thereof. Background Art

[0002] At present, the general density of carbon-carbon thermal insulation felt is 0.18g / cm 3 -0.21g / cm 3 The thermal conductivity is between 0.2-0.4; the thermal insulation performance of carbon-carbon thermal insulation felt is mainly reflected in the thermal conductivity. The lower the thermal conductivity, the better the thermal insulation performance. There are two main ways to reduce the thermal conductivity of carbon-carbon thermal insulation felt: one is to reduce the density of carbon-carbon thermal insulation felt, and the other is to reduce the heat transfer channel of carbon-carbon thermal insulation felt.

[0003] Existing carbon-carbon thermal insulation hard felt is mostly made of pre-oxidized integral felt, and its reinforcement method is through integral needle punching molding, resulting in a large number of fibers distributed in the Z direction inside the carbon-carbon thermal insulation hard felt, thereby increasing the heat transfer channel inside the carbon-carbon thermal insulation hard felt and affecting the actual thermal insulation performance of the carbon-carbon thermal insulation hard felt.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for preparing a high-fluff carbon-carbon thermal insulation hard felt, which can solve the technical problem that the existing carbon-carbon thermal insulation hard felt has poor thermal insulation performance due to the large number of heat transfer channels.

[0006] The second object of the present invention is to provide a high-fluff carbon-carbon thermal insulation hard felt with low thermal conductivity and excellent thermal insulation performance.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, a method for preparing a high-loft carbon-carbon thermal insulation hard felt comprises the following steps:

[0009] (a) The shaped carbon fiber mesh is firstly coated with glue on both sides by a double-net clamping glue coating device, and then the residual glue on the carbon fiber mesh is removed to control the glue content, and then the carbon fiber mesh is dried by a radiation drying device to remove part of the solvent on the carbon fiber mesh, and then the carbon fiber mesh is dried by a hot air penetration oven to remove the residual solvent on the carbon fiber mesh, and the glue is cross-linked and cured to obtain a reinforced carbon fiber mesh;

[0010] (b) The reinforced carbon fiber mesh obtained in step (a) is subjected to layering, hot pressing and carbonization treatment in sequence to obtain the carbon-carbon thermal insulation hard felt.

[0011] Furthermore, the double-net clamping glue spraying equipment sprays glue on the upper and lower surfaces of the shaped carbon fiber net through a hanger-type solution dispensing device and a turning mechanism;

[0012] The shaped carbon fiber net is fed into the double-net clamping glue spraying equipment through the transmission pressure roller under the action of the front and rear conveying rollers with a speed ratio of no more than 5%.

[0013] Furthermore, the resin used for the glue pouring includes phenolic resin.

[0014] Furthermore, the method of removing the residual glue on the carbon fiber net includes removing the residual glue by a vacuum liquid suction device.

[0015] Furthermore, the temperature of the radiation drying device is 60°C-80°C.

[0016] Furthermore, the temperature program of the hot air penetration oven is to increase the temperature from 80°C to 180°C, keep the temperature, and then decrease the temperature to 60°C.

[0017] Furthermore, the shaping method includes hot blanching;

[0018] The temperature of the hot blanching and shaping is 180°C-220°C.

[0019] In a second aspect, a carbon-carbon thermal insulation hard felt is prepared by any of the preparation methods described above.

[0020] Furthermore, the density of the carbon-carbon thermal insulation felt is 0.08 g / cm 3 -0.16g / cm 3 ;

[0021] The porosity of the carbon-carbon thermal insulation felt is 91.12%-95.56%;

[0022] The fluffiness of the carbon-carbon thermal insulation felt is 6.25 cm 3 / g-12.5cm 3 / g.

[0023] Furthermore, the thermal conductivity of the carbon-carbon thermal insulation felt is 0.05-0.1.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The preparation method of the high-loft carbon-carbon thermal insulation hard felt provided by the present invention realizes the high loft and high porosity of the carbon fiber mesh tire through a specific composite reinforcement process; specifically, firstly, a double-net clamping glue-spraying device is used to spray glue (glue refers to resin solution) on the shaped carbon fiber mesh, which can perform double-sided quantitative glue spraying on the carbon fiber mesh under extremely low tension, thereby avoiding the phenomenon of uneven dispersion of the resin solution in the thick fiber mesh, and then remove the residual glue on the carbon fiber mesh to control the glue content on the fiber mesh, thereby controlling the weight and density of the final product, and then adopting a radiation drying device for pre-drying to remove part of the solvent on the carbon fiber mesh. The radiation drying device can realize rapid and uniform drying of the resin solution in the fiber mesh, and quickly remove part of the solvent to reduce the migration of the resin solution, thereby maintaining the resin on the fiber. The carbon fiber mesh is evenly distributed in the fiber mesh, and then a hot air penetration oven is used to completely dry the carbon fiber mesh, and at the same time, it is heated to a sufficient temperature to completely cross-link and cure the glue (resin). The hot air penetration oven is used to completely dry and remove the residual solvent on the fiber mesh. The hot air penetrates the fiber mesh as a whole, so that the fibers can be further loosened. At the same time, the temperature of the hot air can make the resin remaining at the fiber interlacing points cross-link and cure, thereby achieving the reinforcement effect of the overall carbon fiber mesh. In short, with the coordinated cooperation of each step, the obtained carbon fiber mesh (mesh tire) has high fluffiness and high porosity, as well as certain strength and certain durability. In the subsequent lamination hot pressing stage, by controlling the compression ratio and the ratio of phenolic resin to the fiber mesh, the carbon-carbon thermal insulation hard felt product can have low density, high porosity and high thermal insulation performance.

[0026] The high-fluff carbon-carbon thermal insulation hard felt provided by the invention has low density, high porosity and low thermal conductivity, and thus has excellent thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A first cross-sectional view of a hanger-type solution dispensing device provided in accordance with an embodiment of the present invention;

[0029] Figure 2 A second cross-sectional view of a hanger-type solution dispensing device provided in accordance with an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of a composite reinforcement process provided in one embodiment of the present invention;

[0031] Figure 4 A schematic diagram of a first resin solution spraying zone provided for one embodiment of the present invention.

[0032] Icons: 1-resin solution access pipeline; 2-gas inlet; 3-solution channel; 100-net laying device; 200-transmission leather curtain; 300-hot ironing roller; 400-first resin solution glue spraying area; 401-metal support roller; 402-first transmission pressure roller; 403-hanger type solution distribution device; 404-clamping curtain; 500-transmission roller; 600-second resin solution glue spraying area; 601-second transmission pressure roller; 700-vacuum liquid suction device; 800-radiation drying device; 900-hot air penetration oven. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] According to a first aspect of the present invention, there is provided a method for preparing a high-loft carbon-carbon thermal insulation hard felt, comprising the following steps:

[0035] (a) The shaped carbon fiber mesh is firstly coated with glue on both sides by a double-net clamping glue coating device, and then the residual glue on the carbon fiber mesh is removed to control the glue content, and then the carbon fiber mesh is dried by a radiation drying device to remove part of the solvent on the carbon fiber mesh, and then the carbon fiber mesh is dried by a hot air penetration oven to remove the residual solvent on the carbon fiber mesh, and the glue is cross-linked and cured to obtain a reinforced carbon fiber mesh;

[0036] (b) The reinforced carbon fiber mesh obtained in step (a) is subjected to layering, hot pressing and carbonization treatment in sequence to obtain a carbon-carbon thermal insulation hard felt.

[0037] The preparation method of the high-loft carbon-carbon thermal insulation hard felt provided by the present invention realizes the high loft and high porosity of the carbon fiber mesh tire through a specific composite reinforcement process; specifically, firstly, a double-net clamping glue-spraying device is used to spray glue (glue refers to resin solution) on the shaped carbon fiber mesh, which can perform double-sided quantitative glue spraying on the carbon fiber mesh under extremely low tension, thereby avoiding the phenomenon of uneven dispersion of the resin solution in the thick fiber mesh, and then remove the residual glue on the carbon fiber mesh to control the glue content on the fiber mesh, thereby controlling the weight and density of the final product, and then adopting a radiation drying device for pre-drying to remove part of the solvent on the carbon fiber mesh. The radiation drying device can realize rapid and uniform drying of the resin solution in the fiber mesh, and quickly remove part of the solvent to reduce the migration of the resin solution, thereby maintaining the resin on the fiber. The carbon fiber mesh is evenly distributed in the fiber mesh, and then a hot air penetration oven is used to completely dry the carbon fiber mesh, and at the same time, it is heated to a sufficient temperature to completely cross-link and cure the glue (resin). The hot air penetration oven is used to completely dry and remove the residual solvent on the fiber mesh. The hot air penetrates the fiber mesh as a whole, so that the fibers can be further loosened. At the same time, the temperature of the hot air can make the resin remaining at the fiber interlacing points cross-link and cure, thereby achieving the reinforcement effect of the overall carbon fiber mesh. In short, with the coordinated cooperation of each step, the obtained carbon fiber mesh (mesh tire) has high fluffiness and high porosity, as well as certain strength and certain durability. In the subsequent lamination hot pressing stage, by controlling the compression ratio and the ratio of phenolic resin to the fiber mesh, the carbon-carbon thermal insulation hard felt product can have low density, high porosity and high thermal insulation performance.

[0038] In a preferred embodiment, the double-net clamping glue spraying equipment sprays glue on the upper and lower surfaces of the shaped carbon fiber net through a hanger-type solution dispensing device and a turning mechanism.

[0039] The double-net clamping glue spraying equipment uses a hanger-type solution distribution device and a flipping mechanism to apply the resin solution to the upper and lower surfaces of the fiber net, which helps to avoid uneven dispersion of the resin solution in a thick fiber net.

[0040] In the present invention, the shaped carbon fiber net is fed into the double-net clamping glue spraying device through the transmission pressure roller under the action of the front and rear conveying rollers with a speed ratio of no more than 5%.

[0041] The shaped carbon fiber web is sent into the glue spraying equipment with a hanger-type solution distribution device through the transmission pressure roller under the extremely low tension brought by the speed ratio of the front and rear conveying rollers not exceeding 5% (the tension is controlled by the transmission speed difference, and the speed difference is maintained at 0-5%).

[0042] The structure of the hanger type solution dispensing device is shown in Figure 1 and Figure 2, including a resin solution access pipe 1, a gas inlet 2 and a solution channel 3. The resin solution enters the distribution device through the resin solution access pipe 1, and the gas enters the distribution device through the gas inlet 2. The resin solution is evenly pressed into each horizontally adjacent solution channel 3 by the gas pressure generated by the gas in the distribution device. Under the action of gravity, the resin solution is poured onto the surface of the carbon fiber mesh in the form of a liquid flow, thereby achieving the purpose of glue pouring.

[0043] In a preferred embodiment, the resin used for the glue spraying includes but is not limited to phenolic resin.

[0044] In a preferred embodiment, the method of removing the residual glue on the carbon fiber mesh includes but is not limited to removing the residual glue by a vacuum suction device.

[0045] Removing excess glue through a vacuum suction device is more conducive to further controlling the resin content on the carbon fiber mesh and the weight and density of the final product.

[0046] In the present invention, the radiation drying device heats the inner and outer layers of the carbon fiber mesh simultaneously by infrared radiation, thereby achieving rapid and uniform drying, which is beneficial to reducing the migration of the resin solution.

[0047] In a preferred embodiment, the temperature of the radiation drying device can be 60°C-80°C, and typical but non-limiting temperatures are, for example, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, and 80°C, which is more conducive to quickly and evenly drying the resin solution and reducing the migration of the resin solution, so that the resin is evenly distributed in the fiber web.

[0048] In a preferred embodiment, the temperature program of the hot air penetration oven can be raised from 80°C to 180°C, kept warm, and then lowered to 60°C.

[0049] The temperature of the hot air penetration oven can be gradually increased from 80°C to 180°C and maintained for a period of time, and then the temperature is gradually reduced to 60°C. This drying stage can not only completely dry the carbon fiber mesh to remove the solvent, but also when the temperature rises to 110°C, the phenolic resin begins to solidify, and the phenolic resin molecules cross-link with each other, thereby completing the reinforcement of the fiber mesh.

[0050] In the present invention, the method of shaping the carbon fiber mesh includes but is not limited to hot stamping; wherein the hot stamping temperature can be 180°C-220°C, and its typical but non-limiting temperatures are, for example, 180°C, 190°C, 200°C, 210°C, and 220°C, which is more conducive to further improving the shaping effect of the carbon fiber mesh.

[0051] A typical preparation method of a high-loft carbon-carbon thermal insulation hard felt, the process is shown in Figure 3 , including the following steps:

[0052] Chopped carbon fiber: Use mixed chopped carbon filaments with a length of 40mm-120mm. The mass proportion of chopped carbon filaments with a chopped length less than 60mm should be less than 50%, and the mass proportion of chopped carbon filaments with a chopped length greater than 100mm should not be less than 10%. Chopped carbon filaments with a length of 70mm-80mm are preferred.

[0053] It should be noted that the present invention uses short-cut carbon filaments of different lengths for mixing, which can give the fiber mesh, mesh tire and its carbon-carbon thermal insulation hard felt sufficient strength, processability and durability, and to a certain extent, the carbon filaments with a fiber length of less than 60 mm can be replaced with carbon fiber preforms and soft felt edge materials that have been broken and opened, which is conducive to reducing production costs;

[0054] Loosening: Put the chopped carbon filaments of different lengths into a stirring container and achieve preliminary mixing of the chopped carbon filaments of different lengths through mechanical stirring;

[0055] The mixed carbon filaments that have been preliminarily mixed are poured onto the transmission curtain of the bag opener, and then fed into the multi-roller opener through the metal impurity remover to open and mix the chopped carbon filaments;

[0056] Air-laid web: After the fibers are opened by a multi-roller opener, they are sent into a cotton box by a high-speed airflow. The opened fiber clusters are then lifted upward by a conveying nail curtain to the cotton-distributing roller and the cotton-dropping roller.

[0057] The fiber mass is homogenized and measured by the cotton roller, and then stripped by the cotton drop roller and transferred to the vibration plate. The vibration of the vibration plate drives the fiber mass to fall and evenly stack on the conveying leather curtain to form a continuous fiber mass.

[0058] After being precisely measured, the continuous fiber mass is fed into the high-speed cylinder by the feeding roller. The cylinder combs the fiber mass at high speed to form a fiber web. The fiber web is adsorbed by the air-permeable curtain with negative pressure and stripped from the high-speed cylinder to form a highly disordered, isotropic, continuous and strong carbon fiber web.

[0059] The carbon fiber net is fed into the reciprocating net laying machine through the conveyor curtain;

[0060] Composite reinforcement: The carbon fiber mesh passes through the feeding curtain, annular curtain, reciprocating curtain and output clamping roller of the reciprocating paving machine (paving device 100) in sequence, and is reciprocated and stacked in a "Z" shape according to the parameter setting value. By setting the process parameters of the paving layer number and paving width of the paving machine, the thickness, surface density and density are increased to the requirements of the product design, and the maximum surface weight can reach 3000g / m 2 ;

[0061] It should be noted that the present invention adopts a combination of air-laid and reciprocating web laying machine. On the basis of the isotropic mechanical strength of the air-laid carbon fiber net, the reciprocating web laying machine is used in conjunction to further reciprocate and stack the formed fiber net, which is beneficial to increase the thickness, surface density and tensile strength of the fiber net, and can further reduce the difference in mechanical properties of the fiber net in the longitudinal and transverse directions, thereby improving the uniformity of the distribution of carbon fiber monofilaments, and achieving the purpose of uniform composite strength of the web and uniform density of carbon-carbon thermal insulation hard felt; the present invention can produce web products with extremely high surface density through air-laid form, and the surface density can reach up to 3000g / m 2 , optimizes the processing procedures from carbon fiber mesh tire to finished product, which is conducive to reducing production costs;

[0062] The folded carbon fiber mesh is fed into a pair of hot rolling rollers 300 through a transmission leather curtain 200. The hot rolling roller spacing is set according to the product thickness. The carbon fiber mesh is hot-rolled and shaped at 180°C-220°C. The output speed is set to 100%-110% of the carbon fiber mesh feeding speed. The required thickness of the product is preliminarily controlled and the carbon fiber mesh is transported backward.

[0063] After the hot stamping and shaping, the carbon fiber web is sent to the first resin solution glue spraying area 400 with a hanger-type solution dispensing device 403 through the first transmission roller 402 under the action of the front and rear conveying rollers with a speed ratio of no more than 5% (i.e., under the action of extremely low tension). Figure 4 ;

[0064] The viscosity of the phenolic resin solution is prepared to 500cp-1000cp by using solvent and fast-curing phenolic resin (the mass ratio of the solvent to the phenolic resin is 1:2). The phenolic resin solution is uniformly pressed into the solution channels 3 of each horizontally adjacent 100mm of the solution distribution device under the action of air pressure (0.05Mpa-0.2Mpa) in the hanger-type solution distribution device 403. Under the action of gravity, the phenolic resin solution is poured onto the surface of the carbon fiber mesh in the form of a liquid flow, thereby achieving one-time glue pouring;

[0065] The carbon fiber web that has been coated with glue once is lifted upward and turned 180 degrees horizontally under the drive of the traction roller, the clamping curtain 404 and the smaller speed ratio of the front and rear traction rollers, and is sent to the second resin solution coating area 600 through the transmission roller 500 for secondary coating;

[0066] The second resin solution glue spraying area 600 has the same configuration as the first resin solution glue spraying area, but the overall position of the hanger-type solution dispensing device in the second resin solution glue spraying area 600 is relatively offset by 50 mm along the product width direction;

[0067] It should be noted that the adjacent distance, air pressure and relative offset distance of the solution channels inside the hanger-type solution dispensing device can be adjusted accordingly according to factors such as the actual product width, thickness and surface weight; at the same time, metal support rollers 401 coated with polytetrafluoroethylene can be used in the glue spraying area to support the carbon fiber mesh;

[0068] The carbon fiber web after the second glue coating (i.e. double-sided glue coating) is held by the clamping curtain and driven forward by the second transmission roller 601, so that the surface of the fiber web is smoothed by the fibers brought out by the transmission, and the phenolic resin solution is accelerated to flow and transported forward to the vacuum liquid suction device 700;

[0069] After the carbon fiber mesh passes through the vacuum suction device 700 to remove the residual glue, it is then dried; the drying process consists of two parts: pre-drying and main drying;

[0070] The pre-drying part uses a radiation drying device 800 to remove some solvents on the carbon fiber net, and heats the inner and outer layers of the carbon fiber net simultaneously in the form of infrared radiation to reduce the migration of the phenolic resin solution. The temperature of this stage is set to 60°C-80°C;

[0071] The main drying part uses a hot air penetration oven 900 to dry to remove the remaining solvent on the carbon fiber mesh. The temperature program at this stage is to gradually increase from 80°C to 180°C and maintain it for a period of time, and then gradually cool down to 60°C. This can not only completely dry the carbon fiber mesh, but also when the temperature rises to 110°C, the (fast curing) phenolic resin begins to cure, and the phenolic resin molecules cross-link with each other to achieve the reinforcement of the entire carbon fiber mesh;

[0072] Cutting and preparation: Cut the reinforced carbon fiber mesh according to the blank specifications of the product, and prepare the number of mesh sheets required for carbon-carbon thermal insulation felt based on weight and thickness;

[0073] Laying and hot pressing: Spray phenolic resin on the cut carbon fiber mesh (mesh tire) in sequence according to the order requirements. After spraying evenly on the surface of each mesh tire, the mesh tires are stacked and sent to the hot press for hot pressing. The mesh tires are hot pressed at a small compression ratio to achieve bonding between the mesh tires and complete the production of the cured felt.

[0074] Carbonization treatment: The cured felt is placed in a carbonization furnace for carbonization treatment, so that the phenolic resin in the cured felt is carbonized in a high temperature environment;

[0075] After carbonization, the cured felt becomes carbon felt;

[0076] High temperature treatment: The carbon felt is placed in a high temperature furnace at 2300°C for high temperature treatment to obtain carbon-carbon thermal insulation hard felt.

[0077] In summary, the present invention uses a phenolic resin solution, a double-net clamping glue coating equipment, a radiation drying device and a hot air penetration oven in combination, which not only gives the net tire a certain strength, but also retains the high fluffiness, high porosity and high specific surface area of ​​the net tire, and can make the net tire thickness reach more than 20 mm; the preparation process of the present invention reduces the needling process in the preparation of traditional carbon-carbon thermal insulation hard felt, improves product production efficiency, realizes quantitative control of resin usage, and reduces production costs; since there is no need to perform the needling compounding step, the number of carbon filaments distributed in the Z direction in the carbon-carbon thermal insulation hard felt is reduced, so that the heat transfer channel is greatly reduced, thereby improving the thermal insulation performance of the carbon-carbon thermal insulation hard felt.

[0078] In summary, with the coordinated cooperation of various steps and their parameters, the preparation method of the present invention can produce a density as low as 0.08g / cm 3 The carbon-carbon thermal insulation hard felt can increase the porosity in the carbon-carbon thermal insulation hard felt, effectively reduce the thermal conductivity of the carbon-carbon thermal insulation hard felt, and thus can significantly improve the thermal insulation performance of the carbon-carbon thermal insulation hard felt.

[0079] According to a second aspect of the present invention, there is provided a carbon-carbon thermal insulation hard felt prepared by any of the preparation methods described above.

[0080] The high-fluff carbon-carbon thermal insulation hard felt provided by the invention has low density, high porosity and low thermal conductivity, and thus has excellent thermal insulation performance.

[0081] In the present invention, the density of the carbon-carbon thermal insulation felt can be 0.08 g / cm 3 -0.16g / cm 3 ; The porosity of carbon-carbon thermal insulation felt can be 91.12%-95.56%; The fluffiness of carbon-carbon thermal insulation felt can be 6.25cm 3 / g-12.5cm 3 / g.

[0082] In a preferred embodiment, the thermal conductivity of the carbon-carbon thermal insulation felt may be 0.05-0.1.

[0083] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0084] Example 1

[0085] A method for preparing a high-loft carbon-carbon thermal insulation hard felt comprises the following steps:

[0086] (a) Chopped carbon fiber: Use chopped carbon filaments with a length of 40 mm to 120 mm, the mass proportion of chopped carbon filaments with a chopped length of less than 60 mm is less than 50%, and the mass proportion of chopped carbon filaments with a chopped length of more than 100 mm is not less than 10%;

[0087] (b) opening: placing the chopped carbon filaments of different lengths into a stirring container, and performing preliminary mixing of the chopped carbon filaments of different lengths by mechanical stirring;

[0088] The carbon filaments that have been preliminarily mixed are poured onto the transmission curtain of the bag opener, and after being processed by the metal impurity remover, they are fed into the multi-roller opener to open and mix the chopped carbon filaments;

[0089] (c) Air-laid web: The fibers are opened by a multi-roller opener and then sent into a cotton box by a high-speed airflow. The opened fiber clusters are then lifted upward by a conveying nail curtain to the cotton-distributing roller and the cotton-dropping roller;

[0090] The fiber mass is homogenized and measured by the cotton roller, and then stripped by the cotton drop roller and transferred to the vibration plate. The vibration of the vibration plate drives the fiber mass to fall and evenly stack on the conveying leather curtain to form a continuous fiber mass.

[0091] After being precisely measured, the continuous fiber mass is fed into the high-speed cylinder by the feeding roller. The cylinder combs the fiber mass at high speed to form a fiber web. The fiber web is adsorbed by the air-permeable curtain with negative pressure and stripped from the high-speed cylinder to form a highly disordered, isotropic, continuous and strong carbon fiber web.

[0092] The carbon fiber net is fed into the reciprocating net laying machine through the conveyor curtain;

[0093] (d) Composite reinforcement: The carbon fiber mesh passes through the feeding curtain, the annular curtain, the reciprocating curtain and the output clamping roller of the reciprocating web laying machine (web laying device 100) in sequence, and is reciprocated and stacked in a "Z" shape according to the parameter setting values. By setting the process parameters of the web laying machine for the number of web laying layers and the web laying width, the thickness, surface density and density are increased to the requirements of the product design;

[0094] The folded carbon fiber web is fed into a pair of hot rolling rollers 300 through a transmission leather curtain 200. The hot rolling roller spacing is set according to the product thickness. The carbon fiber web is hot-stamped at 200°C. The output speed is set to 105% of the carbon fiber web feeding speed. The required thickness of the product is preliminarily controlled and the carbon fiber web is transported backward.

[0095] After hot stamping, the carbon fiber web is sent to the first resin solution glue spraying area 400 with a hanger-type solution dispensing device 403 through the first transmission pressure roller 402 under the action of the speed ratio of the front and rear conveying rollers not exceeding 5% (i.e., under the action of extremely low tension);

[0096] The viscosity of the phenolic resin solution is adjusted to 800cp by using solvent and fast-curing phenolic resin (the mass ratio of the solvent to the phenolic resin is 1:2). The phenolic resin solution is uniformly pressed into the solution channels 3 of each horizontally adjacent 100mm of the solution distribution device under the action of air pressure (0.1Mpa) in the hanger-type solution distribution device 403. Under the action of gravity, the phenolic resin solution is poured onto the surface of the carbon fiber mesh in the form of a liquid flow, thereby achieving one-time glue pouring;

[0097] The carbon fiber web that has been coated with glue once is lifted upward and turned 180 degrees horizontally under the drive of the traction roller, the clamping curtain 404 and the smaller speed ratio of the front and rear traction rollers, and is sent to the second resin solution coating area 600 through the transmission roller 500 for secondary coating;

[0098] The second resin solution glue spraying area 600 has the same configuration as the first resin solution glue spraying area, but the overall position of the hanger-type solution dispensing device in the second resin solution glue spraying area 600 is relatively offset by 50 mm along the product width direction;

[0099] In the glue spraying area, a metal support roller 401 with a polytetrafluoroethylene coating on the surface is used to support the carbon fiber mesh;

[0100] The carbon fiber web after the second glue coating (i.e. double-sided glue coating) is held by the clamping curtain and driven forward by the second transmission roller 601, so that the surface of the fiber web is smoothed by the fibers brought out by the transmission, and the phenolic resin solution is accelerated to flow and transported forward to the vacuum liquid suction device 700;

[0101] After the carbon fiber mesh passes through the vacuum suction device 700 to remove the residual glue, it is then dried; the drying process consists of two parts: pre-drying and main drying;

[0102] The pre-drying part uses a radiation drying device 800 to remove some solvents on the carbon fiber net, and heats the inner and outer layers of the carbon fiber net simultaneously in the form of infrared radiation to reduce the migration of the phenolic resin solution. The temperature of this stage is set to 70°C.

[0103] The main drying part uses a hot air penetration oven 900 to dry to remove the remaining solvent on the carbon fiber mesh. The temperature program at this stage is to gradually increase from 80°C to 180°C and maintain it for a period of time, and then gradually cool down to 60°C. This can not only completely dry the carbon fiber mesh, but also when the temperature rises to 110°C, the (fast curing) phenolic resin begins to cure, and the phenolic resin molecules cross-link with each other to achieve the reinforcement of the entire carbon fiber mesh;

[0104] (e) Cutting and preparing materials: Cut the reinforced carbon fiber mesh according to the blank specifications of the product, and prepare the number of mesh sheets required for the carbon-carbon thermal insulation felt based on weight and thickness;

[0105] (f) Laying and hot pressing: spraying phenolic resin on the cut carbon fiber mesh (mesh tire) in sequence according to the order requirements, evenly spraying the phenolic resin on the surface of each mesh tire, and then stacking the mesh tires and sending them into a hot press for hot pressing treatment. The mesh tires are hot pressed at a small compression ratio to achieve bonding between the mesh tires, thus completing the production of the cured felt;

[0106] (g) Carbonization treatment: placing the cured felt in a carbonization furnace for carbonization treatment, so that the phenolic resin in the cured felt is carbonized in a high temperature environment;

[0107] After carbonization, the cured felt becomes carbon felt;

[0108] (h) High temperature treatment: The carbon felt is placed in a high temperature furnace at 2300°C for high temperature treatment to obtain a carbon-carbon thermal insulation hard felt.

[0109] Example 2

[0110] The difference between this embodiment and embodiment 1 is that in this embodiment, the hanger-type solution dispensing device is replaced with an immersion glue tank;

[0111] The remaining steps and process parameters are the same as those in Example 1 to obtain a carbon-carbon thermal insulation hard felt.

[0112] Compared with Example 1, the defect of this embodiment is that the impregnation glue pool adopts a saturated impregnation method, which uses a lot of resin and has a high production cost. At the same time, it is also impossible to accurately control the resin content in the product.

[0113] Example 3

[0114] The difference between this embodiment and embodiment 1 is that in this embodiment, the phenolic resin is replaced with asphalt in the glue spraying area;

[0115] The remaining steps and process parameters are the same as those in Example 1 to obtain a carbon-carbon thermal insulation hard felt.

[0116] Compared with Example 1, the defects of this embodiment are that due to the poor fluidity of asphalt, the glue spraying equipment needs to be heated, and it is easy to cause uneven distribution of asphalt after glue spraying; at the same time, the asphalt has a poor wetting effect on the carbon fiber mesh, and the product is easy to stratify after glue spraying; in addition, the impurity content in the asphalt is high, resulting in a high ash content in the product.

[0117] Example 4

[0118] The difference between this embodiment and embodiment 1 is that in this embodiment, the vacuum liquid suction device is replaced by a liquid squeezing roller;

[0119] The remaining steps and process parameters are the same as those in Example 1 to obtain a carbon-carbon thermal insulation hard felt.

[0120] Compared with Example 1, the defect of this embodiment is that, in order to obtain a better residual glue removal effect, a certain roller pressure is required, which may easily cause changes in product thickness; at the same time, during the residual glue removal process, the product surface may be easily wrinkled due to the influence of the roller pressure; in addition, the surface of the liquid squeezing roller may easily adhere to the fiber web containing resin, resulting in fluffing on the product surface.

[0121] Comparative Example 1

[0122] The difference between this comparative example and Example 1 is that in this comparative example, the radiation drying device is replaced by a contact metal drying cylinder;

[0123] The remaining steps and process parameters are the same as those in Example 1 to obtain a carbon-carbon thermal insulation hard felt.

[0124] Compared with Example 1, the defects of this comparative example are that the resin will migrate, resulting in uneven resin distribution, leading to production abnormalities in subsequent production and processing; there is a certain curvature on the surface of the drying drum, which can easily cause damage to the internal structure of the fiber web; and wrinkles are easily generated on the product surface.

[0125] Comparative Example 2

[0126] The difference between this comparative example and Example 1 is that in this comparative example, the step of removing the residual glue on the carbon fiber mesh is not performed, that is, the carbon fiber mesh after the secondary glue coating is directly dried;

[0127] The remaining steps and process parameters are the same as those in Example 1 to obtain a carbon-carbon thermal insulation hard felt.

[0128] Compared with Example 1, the defect of this comparative example is that it not only reduces the drying efficiency, but also easily causes resin migration during the drying process, resulting in uneven resin distribution and affecting the yield rate of subsequent processing; at the same time, since the resin content in the mesh is too high, there is a lot of residual carbon in the hard felt after carbonization, which will lead to an increase in the overall product density, which not only increases the production cost, but also reduces the thermal insulation performance of the product.

[0129] Comparative Example 3

[0130] The difference between this comparative example and Example 1 is that no radiation drying device is used in this comparative example, that is, the carbon fiber web is directly passed through a hot air penetration oven to completely dry the solvent after removing the residual glue;

[0131] The remaining steps and process parameters are the same as those in Example 1 to obtain a carbon-carbon thermal insulation hard felt.

[0132] Compared with Example 1, the defect of this comparative example is that, due to the high resin content in the mesh, resin migration is likely to occur during direct drying, resulting in uneven resin distribution, and board explosion is likely to occur during the curing process. Abnormal stratification is likely to occur after carbonization, resulting in reduced production yield.

[0133] Comparative Example 4

[0134] The difference between this comparative example and Example 1 is that in this comparative example, the hot air penetration oven is replaced by a jet convection oven;

[0135] The remaining steps and process parameters are the same as those in Example 1 to obtain a carbon-carbon thermal insulation hard felt.

[0136] Compared with Example 1, the defects of this comparative example are that the jet convection oven adopts a single-layer or multi-layer flat-width drying room, and the migration of the resin during the drying process is relatively large; at the same time, the jet convection oven has a relatively low drying efficiency for thick fiber webs, affecting production efficiency; in addition, the jet convection oven has relatively poor drying uniformity, which can easily cause inconsistent drying effects on the fiber web, excessive drying of the outer layer, and failure of the inner layer to meet the process requirements.

[0137] In summary, the preparation method of the present invention uses a phenolic resin solution, a double-net clamping glue coating equipment, a radiation drying device and a hot air penetration oven in combination, which not only gives the net tire a certain strength, but also retains the high fluffiness, high porosity and high specific surface area of ​​the net tire, and can make the net tire thickness reach more than 20 mm; the present invention can not only effectively improve the product production efficiency, but also can quantitatively control the amount of resin used, which is beneficial to reduce production costs, and at the same time can reduce the number of carbon filaments distributed in the Z direction through the carbon-carbon thermal insulation hard felt, so that the heat transfer channel is greatly reduced, and the thermal insulation performance of the carbon-carbon thermal insulation hard felt is effectively improved.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-loft carbon-carbon thermal insulation hard felt, characterized in that: The following steps are involved: (a) The shaped carbon fiber mesh is firstly coated with glue on both sides by a double-net clamping glue coating device, and then the residual glue on the carbon fiber mesh is removed to control the glue content, and then the carbon fiber mesh is dried by a radiation drying device to remove part of the solvent on the carbon fiber mesh, and then the carbon fiber mesh is dried by a hot air penetration oven to remove the residual solvent on the carbon fiber mesh, and the glue is cross-linked and cured to obtain a reinforced carbon fiber mesh; (b) The reinforced carbon fiber mesh obtained in step (a) is subjected to layering, hot pressing and carbonization treatment in sequence to obtain the carbon-carbon thermal insulation hard felt.

2. The preparation method according to claim 1, characterized in that: The double-net clamping glue spraying equipment sprays glue on the upper and lower surfaces of the shaped carbon fiber net through a hanger-type solution dispensing device and a turning mechanism; The shaped carbon fiber net is fed into the double-net clamping glue spraying equipment through the transmission pressure roller under the action of the front and rear conveying rollers with a speed ratio of no more than 5%.

3. The preparation method according to claim 1, characterized in that: The resin used for the glue pouring includes phenolic resin.

4. The preparation method according to any one of claims 1 to 3, characterized in that The method of removing the residual glue on the carbon fiber net includes removing the residual glue by a vacuum liquid suction device.

5. The preparation method according to any one of claims 1 to 3, characterized in that: The temperature of the radiation drying device is 60°C-80°C.

6. The preparation method according to claim 5, characterized in that: The temperature program of the hot air penetration oven is to increase the temperature from 80°C to 180°C, keep the temperature, and then decrease the temperature to 60°C.

7. The preparation method according to claim 1, characterized in that: The shaping method includes hot blanching; The temperature of the hot blanching and shaping is 180°C-220°C.

8. A carbon-carbon thermal insulation hard felt prepared by the preparation method according to any one of claims 1 to 7.

9. The carbon-carbon thermal insulation hard felt according to claim 8, characterized in that: The density of the carbon-carbon thermal insulation felt is 0.08 g / cm 3 -0.16g / cm 3 ; The porosity of the carbon-carbon thermal insulation felt is 91.12%-95.56%; The fluffiness of the carbon-carbon thermal insulation felt is 6.25 cm 3 / g-12.5cm 3 / g.

10. The carbon-carbon thermal insulation hard felt according to claim 9, characterized in that: The thermal conductivity of the carbon-carbon thermal insulation hard felt is 0.05-0.1.

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