CN115636684A - Preparation method of carbon fiber heat-preservation hard felt - Google Patents
Preparation method of carbon fiber heat-preservation hard felt Download PDFInfo
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- CN115636684A CN115636684A CN202211251964.4A CN202211251964A CN115636684A CN 115636684 A CN115636684 A CN 115636684A CN 202211251964 A CN202211251964 A CN 202211251964A CN 115636684 A CN115636684 A CN 115636684A
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Abstract
The invention provides a preparation method of a carbon fiber heat-preservation hard felt, which comprises the following steps: fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber; chopping the pre-oxidized fiber, mixing with a dispersant, and dispersing in a liquid medium to obtain a dispersion liquid; or chopping the pre-oxidized fiber, mixing with a binder and a dispersant, and dispersing in a liquid medium to obtain a dispersion liquid; filtering out liquid in the dispersion liquid, drying, pressurizing, solidifying and then carrying out heat treatment to obtain the dispersion liquid; the pressure of the pressure curing is not less than 0.1MPa and not more than 1MPa.
Description
Technical Field
The invention relates to the field of rigid carbon fiber materials and preparation methods thereof, in particular to a preparation method of a carbon fiber heat-preservation hard felt.
Background
The low-density rigid carbon fiber material is a low-density carbon/carbon composite material obtained by taking carbon fibers as a framework and precursors with high carbon residue rates such as resin, asphalt and the like as adhesives and carbonizing at high temperature. The composite material is an excellent thermal insulation material due to the characteristics of low density, high porosity, low thermal conductivity, good high-temperature stability and the like. The carbon fiber heat-insulating hard felt is a low-density rigid carbon fiber material. It is not only suitable for manufacturing a substrate of a light heat-insulating and ablation-resistant heat-protecting material, but also widely used as a heat-insulating material for high-temperature equipment in a vacuum or non-oxidizing atmosphere, as typified by a single crystal growth furnace, an epitaxial growth furnace, and the like. In addition, the activated carbon fiber heat preservation hard felt can also be made into filtering and adsorbing materials such as molecular sieves and the like.
The common low-density carbon fiber heat-preservation hard felt can be mainly divided into two categories of laminating, curing and molding and wet-process compression molding. The lamination, solidification and molding mainly utilizes the soft carbon felt dipping and molding process. However, the carbon fiber hard felt manufactured by the impregnation die pressing process has the defects of high energy consumption, low interlaminar strength of the carbon fiber hard felt, easiness in cracking, short service life, high binder content, poor oxidation resistance and the like. The wet compression molding is mainly to prepare the chopped carbon fibers, the binder, the dispersant and the like into uniformly dispersed slurry, and the uniformly dispersed slurry is obtained by drying, curing, carbonizing and other processes of the obtained blank by using a vacuum filtration or filter pressing molding method. The carbon fiber hard felt obtained by the method has the advantages of good integrity, difficult layering, large density adjustable range and strong designability. The uniform dispersion of the chopped carbon fibers and the strong bonding between the fibers is critical to achieving high performance product quality. The poor dispersibility of carbon fibers in a solution system is mainly caused by small diameter, large surface area and easy aggregation of the carbon fibers, and meanwhile, the dispersion performance of the carbon fibers is influenced by few surface active groups and low surface activity of the carbon fibers. Therefore, an organic solvent and a binder having compatibility with the organic solvent may be added to the system. However, the method of adding the organic solvent has a relatively single effect, has certain harm or hidden danger to the environment and the safety, and easily causes certain influence on the uniformity of the strength and the heat insulation performance of the product due to the gravity action of a liquid bonding system during carbonization.
In view of the above, a new technical solution is needed to solve the above technical problems.
Disclosure of Invention
The invention aims to provide a low-density rigid carbon fiber material, which adopts isotropic pitch-based pre-oxidized fiber as raw material fiber, and abundant surface functional groups of the fiber are beneficial to realizing uniform dispersion of the fiber in space, so that a heat-insulating pitch-based carbon fiber felt with adjustable thickness and density can be obtained; the method has the advantages of simple preparation process, safety, environmental protection, excellent heat insulation effect, strong designability, stable quality and high cost performance, and can meet the requirement of large-scale production.
In order to achieve the purpose, the invention adopts the following technical means:
a preparation method of a carbon fiber heat-preservation hard felt comprises the following steps:
fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber;
chopping the pre-oxidized fiber, mixing with a dispersant, and dispersing in a liquid medium to obtain a dispersion liquid; or alternatively
Chopping the pre-oxidized fiber, mixing the chopped pre-oxidized fiber with a binder and a dispersant, and dispersing the mixture in a liquid medium to obtain a dispersion liquid;
filtering out liquid in the dispersion liquid, drying, pressurizing, solidifying and then carrying out heat treatment to obtain the dispersion liquid;
the pressure of the pressure curing is not less than 0.1MPa and not more than 1MPa.
The outer diameter of the asphalt fiber is 7-60 mu m;
the length of the asphalt fiber after being chopped is 0.5-10 mm;
the pitch fibers are isotropic pitch fibers.
The mass ratio of the binder to the pre-oxidized fibers in the dispersion is 0.25-1: 1;
the mass ratio of the dispersing agent to the pre-oxidized fiber is 0-0.05: 1;
the mass ratio of the liquid medium to the pre-oxidized fiber is 20-100: 1.
the dispersant comprises at least one of methylcellulose, sodium carboxymethylcellulose, ethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, polyacrylamide or polyvinyl alcohol.
The binder is selected from one of phenolic resin, asphalt, furan resin, urea resin, epoxy resin, vinyl ester resin, polyethylene, polypropylene, ethylene-propylene copolymer, polyamide, polystyrene or acrylic resin;
the binder meets Dv50 epsilon (1,10); and is
The binder satisfies Dv97 e (7,36) for the binder; and is
The binder satisfies Dv97/Dv50 of less than 7.
The temperature of the pressure curing is 150-280 ℃;
the time of the pressurization curing is 0.5 to 2 hours.
The temperature of the heat treatment is 1000-2800 ℃;
the heating rate of the heat treatment is 0.1-50 ℃/min.
The density of the carbon fiber heat-preservation hard felt is 0.1-0.3 g/cm 3 ；
The thermal conductivity of the carbon fiber heat-preservation hard felt is less than or equal to 0.3W/(m.K).
Compared with the prior art, the invention has the following technical effects:
the invention adopts non-carbonized isotropic pitch-based pre-oxidized fiber as a raw material, and the abundant functional groups (carboxyl, hydroxyl and the like) on the surface of the fiber have certain hydrophilicity, so that the fiber has better dispersibility in water or polar solvents, and the fiber is beneficial to realizing uniform dispersion of the fiber in space.
The method provided by the invention realizes the material density and the layered distribution degree by adjusting the pressure, and can obtain the carbon fiber felt with adjustable thickness and density, which is beneficial to meeting different application requirements.
According to the invention, the strength, heat preservation and uniformity of the low-density carbon/carbon composite material heat preservation material are further improved and the comprehensive performance is improved by adjusting the proportion of the isotropic pitch-based pre-oxidized fiber dispersion liquid and the conditions of mould pressing, curing and carbonization of the isotropic pitch-based pre-oxidized fiber dispersion liquid.
The preparation technology of the rigid carbon fiber heat-preservation hard felt provided by the invention has the advantages of simple process, safety, environmental protection, excellent heat insulation effect, strong designability, stable quality and high cost performance, and can meet the requirement of large-scale production.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly described below.
FIG. 1 shows an infrared spectrum of pitch-based carbon fibers, pitch-based pre-oxidized fibers, and pitch fiber strands;
figure 2 shows a schematic sampling of a carbon fiber felt test sample.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention and are not to be construed as limiting the present invention.
The invention provides a preparation method of a carbon fiber heat-preservation hard felt, which comprises the following steps:
fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber; chopping the pre-oxidized fiber, mixing with a dispersant, and dispersing in a liquid medium to obtain a dispersion liquid; or chopping the pre-oxidized fiber, mixing with a binder and a dispersant, and dispersing in a liquid medium to obtain a dispersion liquid; filtering out liquid in the dispersion liquid, drying, pressurizing, solidifying and then carrying out heat treatment to obtain the product.
The carbon fiber heat-preservation hard felt is prepared by adopting the pitch pre-oxidized fiber as a raw material, and the performance of the prepared carbon fiber heat-preservation hard felt can be improved. The pre-oxidized fiber is carbonized by heating the pre-oxidized fiber to 1400-1600 ℃ in vacuum or high purity inert atmosphere to remove non-carbon elements such as C, H, N in the pre-oxidized fiber. The pre-oxidized fiber can generate a series of complex physical and chemical changes in the carbonization process, dehydration and dehydrogenation reactions occur among molecules, the main chain, the side chain and the terminal group are decomposed, and H is removed by releasing 2 O、NH 3 、CO、CO 2 、N 2 Etc. and the diameter and density of the fiber will be significant during carbonizationAnd (4) changing. As can be seen from fig. 1, the functional groups of the pre-oxidized fibers are relatively close to the binder pitch feedstock, whereas the carbonized fibers have been gradually freed of non-carbon atoms and functional groups, the surface turned inert.
In order to make the fiber and the binder well adhere, compared with the carbon fiber, the pre-oxidized fiber adopted by the invention has more functional groups to participate in the reaction, and the surface functional groups can form a stable adhesion effect with the binder, so that the strength of the prepared carbon fiber heat-insulating hard felt can be increased. In addition, due to the abundant functional groups on the surface of the pre-oxidized fiber, the dispersion effect in the solvent is greatly improved, the dispersion of the fiber is improved, and the uniformity of the prepared carbon fiber heat-preservation hard felt is also greatly improved.
The uniformity of a filter cake obtained by adopting the wet forming of the chopped preoxidized fiber is obviously improved. Compared with carbon fiber products, the main problem is that the filter cake undergoes a larger shrinkage process in the subsequent carbonization process due to the removed fibers of non-carbon elements and small molecular components, and it is noted that in the invention, the binder already consolidates the fibers to form a stable felt body, and in the subsequent carbonization shrinkage, the shrinkage of the fibers is limited by the shrinkage of the binder and other fibers, so that the shrinkage of the whole product is not consistent with the change of preoxidized fibers and traditional preoxidized felts (without binder), and is relatively slower. Therefore, the relatively slow process results in less shrinkage, thereby facilitating the uniform preparation of the carbon fiber insulation hard felt.
Compared with the inherent idea of preparing the carbon fiber heat-preservation hard felt by taking the finished carbon fiber as the raw material in the field, the method selects the pre-oxidized fiber as the initial raw material fiber, applies the carbon fiber preparation process in the process of preparing the carbon fiber heat-preservation hard felt, and realizes the carbonization of the fiber and the felt formation of the fiber.
Specifically, the pressure for press curing is 0.1MPa or more and 1MPa or less. Too much pressure may result in an excessive bulk density of the product or in a risk of breaking the fibres due to too much pressure, and too little pressure may result in a less than intimate contact between the fibres and thus in a less than optimal mechanical performance of the product.
Specifically, the outer diameter of the asphalt fiber is 7-60 μm; larger fiber diameters do not easily allow for complete pre-oxidation thereof; the smaller fiber diameter is easy to cause fiber transition oxidation to lose extra carbon element in the subsequent carbonization process so as to form defects, thereby influencing the mechanical property of the carbon fiber felt;
specifically, the length of the asphalt fiber after being chopped is 0.5-10 mm; too short fibers can reduce the mechanical properties of the carbon fiber felt, and too long fibers are not favorable for fiber dispersion.
Specifically, the pitch fibers are isotropic pitch fibers. The small size and disordered arrangement of the crystallite structure in the isotropic pitch fibers is more favorable for heat preservation (the material has small self thermal conductivity)
Specifically, the mass ratio of the binder to the pre-oxidized fibers in the dispersion is 0.25-1: 1; the poor bonding effect is easily caused by too little mass ratio of the bonding agent, so that the mechanical property of the product is influenced; the mass ratio of the binder is too large, so that the dispersion of the binder is uneven, the cracked carbon of the binder is agglomerated, and the heat preservation performance and the uniformity of the product are reduced.
Specifically, the mass ratio of the dispersing agent to the pre-oxidized fiber is 0-0.05: 1; a small amount of dispersant may aid in the dispersion of the fibers and binder, and too much dispersant may result in a significant increase in the viscosity of the system and may be detrimental to the subsequent filtration process.
Specifically, the mass ratio of the liquid medium to the pre-oxidized fiber is 20-100: 1. when the liquid medium accounts for too little, the dispersion of the fibers and the binder is not facilitated, and when the liquid medium accounts for too much, the production efficiency is reduced, so that the production cost is indirectly improved.
Specifically, the dispersing agent comprises at least one of methylcellulose, sodium carboxymethylcellulose, ethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, polyacrylamide or polyvinyl alcohol. The addition of the dispersing agent can improve the surface tension among the binder, the fiber and the liquid medium, is beneficial to forming a uniform dispersion system among the binder, the fiber and the liquid medium, enables the binder and the fiber not to be easily settled and agglomerated, and provides a sufficient time window for a filtering process after dispersion. Preferably, the dispersant promotes dispersion of the carbon fibers.
Specifically, the binder is selected from phenolic resin, asphalt, furan resin, urea resin, epoxy resin, vinyl ester resin, or one of polyethylene, polypropylene, ethylene-propylene copolymer, polyamide, polystyrene or acrylic resin; the adhesive is easy to crush by airflow crushing equipment, and the carbon bonding point formed after carbonization of the adhesive has strong bonding strength, so that the fibers are tightly bonded, and the mechanical property of the carbon fiber felt is improved.
Specifically, the binder meets Dv50 epsilon (1,10); and the binder satisfies Dv97 e (7,36) for the binder; and, the binder satisfies Dv97/Dv50 of less than 7. The Dv50 is a parameter for characterizing the particle size distribution of the particles, i.e. the particle size corresponding to 50% of the volume distribution, whereas the Dv50 of the particle size of the binder used according to the invention falls within the range of 1 to 10 μm. Accordingly, dv97 falls between 7 and 36 μm. The particle size of the binder in the above range can provide a relatively good effect. Too large a particle size results in too small a number of particles of the binder in a certain mass of the binder, which is not favorable for forming a homogeneous system to result in poor binding effect, and too small a particle size is not favorable for uniform dispersion of the binder.
Specifically, the temperature of the pressure curing is 150-280 ℃; too low a temperature does not melt or cure the binder, and too high a temperature tends to cause the binder to cure too quickly to fully crosslink or begin to degrade.
Specifically, the time of the pressure curing is 0.5-2 h. Too short a curing time may result in insufficient curing of the binder or insufficient melt flow to the fiber lap to wet the interface between the fibers, and too long a curing time may result in unnecessary energy and time consumption and potentially poor performance due to excessive crosslinking.
Specifically, the temperature of the heat treatment is 1000-2800 ℃; the purpose of the heat treatment is to remove non-carbon elements in the binder, the fibers and the dispersing agent, more non-carbon elements are left when the temperature is too low, and the heat conductivity coefficient of the carbon fiber felt is increased when the temperature is too high, so that the carbon fiber felt is not favorable for being used as a heat preservation felt.
Specifically, the heating rate of the heat treatment is 0.1-50 ℃/min. The production efficiency is reduced and the energy consumption cost is increased due to the excessively low heating rate; too fast a temperature rise rate easily causes a failure of the heating equipment, indirectly increasing the production cost.
Specifically, the density of the carbon fiber heat-preservation hard felt is 0.1-0.3 g/cm 3 ；
Specifically, the thermal conductivity of the carbon fiber heat-preservation hard felt is less than or equal to 0.3W/(m.K).
The present invention is further illustrated by the following specific examples.
Example 1
1. 50g of isotropic pitch-based pre-oxidized fibers having a diameter of 19 μm and a length of 0.5mm were put into a 3L beaker containing 1000g of deionized water; then 12.5g of isotropic pitch powder having a particle size Dv50 of 4.9 μm and a particle size Dv97 of 12.9 μm was charged; then 2.5g of PVP dispersant is added; dispersing for 60min under the stirring action of 400rpm to obtain uniform slurry;
2. pouring the slurry into a mold i for suction filtration to obtain a filter cake, and drying the filter cake in a drying oven at 80 ℃ for 12 hours;
3. putting the mould i containing the fiber filter cake into a hot press, applying pressure of 0.1Mpa from the top of the mould, heating the mould, namely carrying out first heat treatment, heating to 280 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 0.5h, bonding the asphalt powder binder at the lap joint of the fibers after melting and flowing, naturally cooling the mould, solidifying the molten asphalt, and demoulding to obtain an asphalt fiber felt;
4. and (3) carrying out high-temperature heat treatment, namely secondary heat treatment on the asphalt fiber felt, and heating to 2200 ℃ at the heating rate of 0.5 ℃/min to obtain the carbon fiber felt.
Example 2
1. 50g of isotropic pitch-based pre-oxidized fibers having a diameter of 32 μm and a length of 5mm were put into a 10L beaker containing 5000g of deionized water; then 12.5g of isotropic pitch powder having a particle size Dv50 of 3.2 μm and a Dv97 of 12.1 μm was charged; adding 1g of PEG dispersant; dispersing for 60min under the stirring action of 600rpm to obtain uniform slurry;
2. pouring the slurry into a mold i for suction filtration to obtain a filter cake, and drying the filter cake in a drying oven at 80 ℃ for 12 hours;
3. putting the mould i containing the fiber filter cake into a hot press, applying pressure of 0.5Mpa from the top of the mould, heating the mould, namely carrying out first heat treatment, heating to 280 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 0.5h, bonding the isotropic asphalt powder adhesive at the lap joint of the fibers after melting and flowing, naturally cooling the mould, solidifying the molten asphalt, and demoulding to obtain an asphalt fiber felt;
4. and (3) carrying out high-temperature heat treatment, namely secondary heat treatment on the asphalt fiber felt, and heating to 1100 ℃ at the heating rate of 0.1 ℃/min to obtain the carbon fiber felt.
Example 3
1. 50g of isotropic pitch-based pre-oxidized fibers having a diameter of 11 μm and a length of 10mm were put into a 5L beaker containing 2500g of deionized water; then 25g of phenolic resin powder with a particle size Dv50 of 2.8 μm and a Dv97 of 11.2 μm was added; adding 0.5g of PAM dispersant; dispersing for 120min under the stirring action of 500rpm to obtain uniform slurry;
2. pouring the slurry into a mold i for suction filtration to obtain a filter cake, and drying the filter cake for 10 hours in a drying oven at 90 ℃;
3. putting the mould i containing the fiber filter cake into a hot press, applying pressure of 0.5Mpa from the top of the mould, heating the mould, namely carrying out first heat treatment, heating to 150 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2h, bonding and solidifying the phenolic resin powder adhesive at the lap joint of the fibers after the phenolic resin powder adhesive is melted and flows, and demoulding after the mould is naturally cooled to obtain an asphalt fiber felt;
4. and (3) carrying out high-temperature heat treatment, namely secondary heat treatment on the asphalt fiber felt, and heating to 2800 ℃ at the heating rate of 20 ℃/min to obtain the carbon fiber felt.
Example 4
1. 50g of isotropic pitch-based pre-oxidized fibers having a diameter of 28 μm and a length of 3mm were put into a 5L beaker containing 2500g of deionized water; then 25g of phenolic resin powder is put in, the particle size Dv50 of the phenolic resin powder is 6.9 μm, and the particle size Dv97 is 21.4 μm; then 0.5g of CTAB dispersant is added; dispersing for 180min under the stirring action of 400rpm to obtain uniform slurry;
2. pouring the slurry into a mold i for suction filtration to obtain a filter cake, and drying the filter cake for 10 hours in a drying oven at 90 ℃;
3. putting the mould i containing the fiber filter cake into a hot press, applying pressure of 0.2Mpa from the top of the mould, heating the mould, namely carrying out first heat treatment, heating to 150 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2h, bonding and solidifying the phenolic resin powder adhesive at the lap joint of the fibers after the phenolic resin powder adhesive is melted and flows, and demoulding after the mould is naturally cooled to obtain an asphalt fiber felt;
4. and (3) carrying out high-temperature heat treatment, namely secondary heat treatment on the asphalt fiber felt, and heating to 2800 ℃ at the heating rate of 30 ℃/min to obtain the carbon fiber felt.
Example 5
1. 50g of isotropic pitch-based pre-oxidized fibers having a diameter of 60 μm and a length of 1mm were put into a 10L beaker containing 5000g of deionized water; then 50g of phenolic resin powder is put into the reactor, wherein the particle size Dv50 of the phenolic resin powder is 9.8 mu m, and the particle size Dv97 is 35.2 mu m; adding 0.5g of PAM dispersant; dispersing for 180min under the stirring action of 400rpm to obtain uniform slurry;
2. pouring the slurry into a mold i for suction filtration to obtain a filter cake, and drying the filter cake for 10 hours in a drying oven at 90 ℃;
3. putting the mould i containing the fiber filter cake into a hot press, applying pressure of 0.2Mpa from the top of the mould, heating the mould, namely carrying out first heat treatment, heating to 280 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 0.5h, bonding the isotropic asphalt powder adhesive at the lap joint of the fibers after melting and flowing, naturally cooling the mould, solidifying the molten asphalt, and demoulding to obtain an asphalt fiber felt;
4. and (3) carrying out high-temperature heat treatment, namely secondary heat treatment on the asphalt fiber felt, and heating to 2600 ℃ at a heating rate of 50 ℃/min to obtain the carbon fiber felt.
Example 6
1. 50g of isotropic pitch-based pre-oxidized fibers having a diameter of 7 μm and a length of 10mm were put into a 3L beaker containing 1500g of deionized water; then 20g of phenolic resin powder is put in, the particle size Dv50 of the phenolic resin powder is 1.3 μm, and the particle size Dv97 is 9.1 μm; then 2.5g of PVP dispersant is added; dispersing for 60min under the stirring action of 600rpm to obtain uniform slurry;
2. pouring the slurry into a mold i for suction filtration to obtain a filter cake, and drying the filter cake for 6 hours in a drying oven at 100 ℃;
3. putting the mould i containing the fiber filter cake into a hot press, applying 1Mpa pressure from the top of the mould, heating the mould, namely carrying out first heat treatment, heating to 150 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2h, bonding and solidifying the phenolic resin powder binder at the lap joint of the fibers after the phenolic resin powder binder is melted and flows, and demoulding after the mould is naturally cooled to obtain an asphalt fiber felt;
4. and (3) carrying out high-temperature heat treatment, namely secondary heat treatment on the asphalt fiber felt, and heating to 2800 ℃ at the heating rate of 50 ℃/min to obtain the carbon fiber felt.
Example 7
The difference between this example and example 1 is that no PVP dispersant was added in step 1, and the rest of the procedure was the same as example 1;
comparative example 1
The present comparative example differs from example 1 in that the fibers used in step 1 are isotropic pitch-based fibers that are not fully pre-oxidized, and the rest of the procedure is the same as example 1;
comparative example 2
The difference between this comparative example and example 1 is that the fibers used in step 1 are mesophase pitch-based pre-oxidized fibers and the rest of the procedure is the same as in example 1;
comparative example 3
This comparative example differs from example 1 in that the fibers used in step 1 are isotropic pitch-based carbon fibers, and the rest of the procedure is the same as in example 1;
comparative example 4
The difference between this comparative example and comparative example 3 is that no PVP dispersant was added in step 1, and the remaining steps were the same as in comparative example 3;
the carbon fiber mats provided in examples 1 to 7 and comparative examples 1 to 4 were subjected to tests including:
1. the sampling mode is shown in figure 2, the testing quantity of each sample is not less than 7, so that the average value and the standard deviation of the testing result are calculated and obtained, and the uniformity of the sample is judged by obtaining the standard deviation through sampling and testing different parts of the prepared sample;
2. calculating the density of the carbon fiber felt according to the ratio of the mass to the volume of the carbon fiber felt, measuring the mass by an analytical balance, and calculating the volume after measuring the size by a micrometer;
3. testing the heat conductivity coefficient of the carbon fiber felt in the Z direction by adopting a Hot Disk TPS2500s heat flow meter, wherein the diameter is 25mm, and the thickness is 2mm;
4. testing the compressive strength of the carbon fiber felt in the Z direction by using a CTM2500 universal material testing machine, wherein the size of a test sample is 10 x 10mm 3 The testing speed is 1mm/min;
the test results are shown in Table 1
From the data results shown in examples 1-7, it can be seen that the use of a reasonably low heat treatment temperature, a short fiber length, and a low molding pressure is beneficial to both satisfying the rigidity of the carbon fiber felt and highlighting the heat insulation performance of the carbon fiber felt, and the standard deviation of the data shows that the sample prepared by the present invention has high sample uniformity; furthermore, it is clear from the data that an increase in the molding pressure can significantly increase the bulk density of the carbon fiber felt.
From the data shown in examples 1 and 7, it can be seen that the addition of the dispersant is beneficial to the uniformity of the carbon fiber mat produced;
from the data of example 1 and comparative example 1, it can be seen that the selection of incompletely pre-oxidized isotropic pitch-based pre-oxidized fibers as the starting material is not conducive to the preparation of low density carbon fiber mats;
as can be seen from the data of example 1 and comparative example 2, when the mesophase pitch-based pre-oxidized fiber is used as the raw material, the carbon fiber felt shows a high thermal conductivity, which is not favorable for preparing the carbon fiber felt with excellent heat insulation performance;
as can be seen from the data of the example 1 and the comparative example 3, compared with the pitch-based carbon fiber, the isotropic pitch-based pre-oxidized fiber is adopted as the raw material, which is obviously beneficial to the uniformity of the prepared carbon fiber felt;
from the data of example 7 and comparative example 3, it can be seen that when isotropic pitch-based pre-oxidized fibers are selected as the raw material, the uniformity of the prepared carbon fiber felt is still better than that of the carbon fiber felt prepared by using pitch carbon fibers and a dispersant even if the dispersant is not added for assisting dispersion;
from the data of example 7 and comparative example 4, it can be seen that the carbon fiber mats prepared using isotropic pitch-based pre-oxidized fibers as the starting material are significantly more uniform than those prepared using pitch carbon fibers as the starting material when no dispersant is used.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (9)
1. The preparation method of the carbon fiber heat-preservation hard felt is characterized by comprising the following steps:
fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber;
chopping the pre-oxidized fiber, mixing with a dispersant, and dispersing in a liquid medium to obtain a dispersion liquid; or
Chopping the pre-oxidized fiber, mixing the chopped pre-oxidized fiber with a binder and a dispersant, and dispersing the mixture in a liquid medium to obtain a dispersion liquid;
filtering out liquid in the dispersion liquid, drying, pressurizing, solidifying and then carrying out heat treatment to obtain the dispersion liquid;
the pressure of the pressure curing is not less than 0.1MPa and not more than 1MPa.
2. The method for preparing the carbon fiber heat-preservation hard felt according to claim 1, characterized by comprising the following steps:
the outer diameter of the asphalt fiber is 7-60 mu m;
the length of the asphalt fiber after being chopped is 0.5-10 mm;
the pitch fibers are isotropic pitch fibers.
3. The method for preparing the carbon fiber heat-preservation hard felt according to claim 1, characterized by comprising the following steps:
the mass ratio of the binder to the pre-oxidized fibers in the dispersion is 0.25-1: 1;
the mass ratio of the dispersing agent to the pre-oxidized fiber is 0-0.05: 1;
the mass ratio of the liquid medium to the pre-oxidized fiber is 20-100: 1.
4. the method for preparing the carbon fiber heat-preservation hard felt according to claim 1, characterized by comprising the following steps:
the dispersant comprises at least one of methylcellulose, sodium carboxymethylcellulose, ethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, polyacrylamide or polyvinyl alcohol.
5. The method for preparing the carbon fiber heat-preservation hard felt according to claim 1, characterized by comprising the following steps:
the binder is selected from one of phenolic resin, asphalt, furan resin, urea resin, epoxy resin, vinyl ester resin, polyethylene, polypropylene, ethylene-propylene copolymer, polyamide, polystyrene or acrylic resin.
6. The method for preparing the carbon fiber heat-preservation hard felt according to claim 1, characterized by comprising the following steps:
the binder meets Dv50 epsilon (1,10); and is
The binder satisfies Dv97 e (7,36) for the binder; and is provided with
The binder satisfies Dv97/Dv50 of less than 7.
7. The method for preparing the carbon fiber heat-preservation hard felt according to claim 1, characterized by comprising the following steps:
the temperature of the pressure curing is 150-280 ℃;
the time of the pressurization curing is 0.5 to 2 hours.
8. The preparation method of the carbon fiber heat-preservation hard felt according to claim 1, characterized by comprising the following steps:
the temperature of the heat treatment is 1000-2800 ℃;
the heating rate of the heat treatment is 0.1-50 ℃/min.
9. The method for preparing the carbon fiber heat-insulating hard felt according to any one of claims 1 to 8, characterized in that:
the density of the carbon fiber heat-preservation hard felt is 0.1-0.3 g/cm 3 ；
The thermal conductivity of the carbon fiber heat-preservation hard felt is less than or equal to 0.3W/(m.K).
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| CN202211251964.4A CN115636684B (en) | 2022-10-13 | 2022-10-13 | Preparation method of carbon fiber heat-insulating hard felt |
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| CN101628816A (en) * | 2008-07-17 | 2010-01-20 | 鞍山塞诺达碳纤维有限公司 | Method for manufacturing high-density rigid carbon-fiber heat-insulation material |
| US20120219778A1 (en) * | 2009-10-06 | 2012-08-30 | Sgl Carbon Se | Composite material containing soft carbon fiber felt and hard carbon fiber felt |
| CN104230368A (en) * | 2014-09-26 | 2014-12-24 | 辽宁奥亿达新材料有限公司 | Pitch-based carbon fiber nonwoven felt insulation board and manufacturing method thereof |
| CN104276805A (en) * | 2013-07-03 | 2015-01-14 | 辽源市亿达碳业有限公司 | Preparation method of hard carbon felt |
| CN106044742A (en) * | 2016-05-30 | 2016-10-26 | 湖南大学 | Method for preparing pitch-based carbon fiber self-bonding network material |
| CN113584940A (en) * | 2021-06-24 | 2021-11-02 | 浙江超探碳纤维科技有限公司 | Preparation method of carbon fiber paper |
| CN114164557A (en) * | 2021-12-30 | 2022-03-11 | 湖南东映特碳沥青材料有限公司 | Carbon fiber hard felt and preparation method thereof |
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| CN101628816A (en) * | 2008-07-17 | 2010-01-20 | 鞍山塞诺达碳纤维有限公司 | Method for manufacturing high-density rigid carbon-fiber heat-insulation material |
| US20120219778A1 (en) * | 2009-10-06 | 2012-08-30 | Sgl Carbon Se | Composite material containing soft carbon fiber felt and hard carbon fiber felt |
| CN104276805A (en) * | 2013-07-03 | 2015-01-14 | 辽源市亿达碳业有限公司 | Preparation method of hard carbon felt |
| CN104230368A (en) * | 2014-09-26 | 2014-12-24 | 辽宁奥亿达新材料有限公司 | Pitch-based carbon fiber nonwoven felt insulation board and manufacturing method thereof |
| CN106044742A (en) * | 2016-05-30 | 2016-10-26 | 湖南大学 | Method for preparing pitch-based carbon fiber self-bonding network material |
| CN113584940A (en) * | 2021-06-24 | 2021-11-02 | 浙江超探碳纤维科技有限公司 | Preparation method of carbon fiber paper |
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