A heat-insulating aerogel aramid thermal insulation felt and its preparation method

Abstract

The present invention relates to the technical field of thermal insulation materials, and particularly relates to a thermal insulation aerogel aramid heat insulation felt and a preparation method thereof. The preparation method is as follows: 2,3-pyrazinedicarboxylic anhydride is added to the reaction system for polymerizing and preparing meta-aramid polymer for reaction to obtain a spinning dope, fibers are prepared by wet spinning, and then the fibers are made into meta-aramid aerogel filaments; the meta-aramid aerogel filaments are subjected to cutting treatment to obtain short-cut meta-aramid aerogel, and then the short-cut meta-aramid aerogel is treated with talcum powder; the short-cut meta-aramid aerogel treated with talcum powder and meta-aramid fibers are jointly treated by a carding and combing machine to make them evenly mixed, and then the thermal insulation aerogel aramid heat insulation felt is obtained through needling treatment. The heat insulation felt of the present invention has high heat insulation and low thermal conductivity performance, solves problems such as powder falling of conventional heat insulation felt compounded with silica, and moreover, the heat insulation felt has good strength performance and flame retardant performance.

Description

Technical Field

[0001] The present invention relates to a thermal insulation aerogel aramid heat insulation felt and a preparation method thereof, belonging to the technical field of thermal insulation materials. Background Art

[0002] The heat insulation felt is a flexible heat insulation material based on fiber materials and made through a specific process, and is widely used in industrial equipment, construction, aerospace, automobiles and other fields. With the rapid development of technologies in various fields, the performance requirements for thermal insulation materials are also getting higher and higher.

[0003] Existing aerogel thermal insulation felts are generally in the form of silica composites, and there are serious powder shedding problems, making it difficult to be applied in the wearable field. For example, the patent application with the publication number CN112709075A discloses a heat insulation felt modified by high-strength aerogel, including a silica-aluminum fiber felt substrate, a polyamide nanofiber / carbon nanotube composite gel coating and a silica aerogel-modified fluorocarbon resin coating sequentially arranged on the silica-aluminum fiber felt substrate; in the polyamide nanofiber / carbon nanotube fiber composite gel coating, the silica aerogel-modified fluorocarbon resin coating includes polymer-modified nano-silica aerogel, fluorocarbon resin and additives. This method uses the silica composite method. In addition, conventional thermal insulation felts are PET felts, with poor flame retardant effects and difficult to be applied in high-temperature protection fields such as degreasing furnaces, high-temperature carbonization furnaces, low-temperature carbonization furnaces, CVD furnaces, and CVI furnaces.

[0004] Meta-aramid is a high-performance fiber with high temperature resistance and inherent flame retardancy, and is widely used in aerospace, personal protection, high-temperature filtration and other fields. In the new thermal insulation field, aramid products have problems such as poor thermal insulation effect and inability to be widely applied. In addition, during the preparation process of aramid thermal insulation felts, there will also be problems such as large static electricity and inability to loosen. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a thermal insulation aerogel aramid heat insulation felt and a preparation method thereof, which have high thermal insulation and low thermal conductivity, and solve problems such as powder shedding in conventional heat insulation felts compounded with silica; at the same time, the meta-aramid aerogel felt has an inherent flame retardant effect and can be widely applied in high-temperature fire protection fields. In addition, the preparation method also solves the problem that the meta-aramid aerogel felt cannot be continuously produced due to large static electricity during the preparation process.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: A preparation method of a thermal insulation aerogel aramid heat insulation felt, and the preparation method is:

[0007] S1. Add 2,3-pyrazinedicarboxylic anhydride to the reaction system for polymerizing meta-aramid polymer to obtain a spinning dope. Prepare fibers by wet spinning, and then make the fibers into meta-aramid aerogel filaments;

[0008] S2. Cut the meta-aramid aerogel filaments to obtain short-cut meta-aramid aerogel, and then treat the short-cut meta-aramid aerogel with talcum powder;

[0009] S3. Treat the short-cut meta-aramid aerogel treated with talcum powder and meta-aramid fibers together using opening and carding machines to make them evenly mixed, and then obtain the heat-insulating aerogel aramid thermal insulation felt through needling treatment.

[0010] Further, in step S1, during the condensation polymerization of m-phenylenediamine and isophthaloyl chloride, add 2,3-pyrazinedicarboxylic anhydride to prepare meta-aramid polymer. The addition amount of the 2,3-pyrazinedicarboxylic anhydride is 0.1 - 0.5% of the molar amount of m-phenylenediamine. After the reaction ends, neutralize to obtain a spinning dope. The viscosity of the spinning dope at 25 °C is 1000 - 1500 Po.

[0011] Further, during the wet spinning process, use two-stage coagulation baths for treatment. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 10 - 15%, the length of the first-stage coagulation bath is 0.3 - 0.5 m, and the temperature is 50 - 60 °C;

[0012] The second-stage coagulation bath is a mixed solution of DMAC, water and calcium chloride. The mass concentration of calcium chloride is 0.5 - 2%, the mass concentration of DMAC is 80 - 85%, the length of the second-stage coagulation bath is 8 - 10 m, and the temperature is 5 - 10 °C.

[0013] Further, the length of the short-cut meta-aramid aerogel is 20 - 100 mm, and the addition amount of the talcum powder is 0.5 - 1 wt% of the mass of the short-cut meta-aramid aerogel.

[0014] Further, the mass ratio of the short-cut meta-aramid aerogel to the meta-aramid fiber is 1:(0.2 - 0.4).

[0015] Further, during the opening process, first use the short-cut meta-aramid aerogel, and then gradually add the meta-aramid fiber. The opening speed of the short-cut meta-aramid aerogel is 8 - 10 m / min, and the opening speed of the meta-aramid fiber is 2 - 4 m / min; the opening pressure is 0.1 - 0.5 Mpa.

[0016] Further, during the carding process, use nitrogen for purging, and the nitrogen flow rate is 0.2 - 0.5 m 3 / min.

[0017] Further, in step S3, the environmental humidity is controlled to be 60%-65%, the needling thickness is 3-8 mm, and the needling density is 100-150 needles / cm 2 .

[0018] The present invention also discloses a heat-insulating aerogel aramid heat-insulating felt, which is prepared according to the preparation method described in the present invention.

[0019] Further, the grammage of the heat-insulating aerogel aramid heat-insulating felt is 150-200 g / m 2 , the thermal conductivity is 0.005-0.015 W / m·K, and the strength of the aerogel felt fabric is 110-150 MPa.

[0020] The beneficial effects of the present invention are as follows:

[0021] The heat-insulating felt described in the present invention has high heat-insulating and low thermal-conductivity properties, solves problems such as powder falling of conventional heat-insulating felt compounded with silica, and moreover, the heat-insulating felt has good strength properties. At the same time, the heat-insulating felt described in the present invention has good flame-retardant properties and can be widely applied to the field of high-temperature fire prevention.

[0022] In the preparation method of the heat-insulating felt described in the present invention, by adding 2,3-pyrazinedicarboxylic anhydride during the preparation process of the meta-aramid polymer, the strength properties of the meta-aramid aerogel fibers can be improved, which is more conducive to application in the heat-insulating felt, and reduces the damage of the internal pores of the meta-aramid aerogel fibers during the processing and manufacturing of the heat-insulating felt, thereby affecting the heat-insulating performance of the heat-insulating felt; then, in coordination with a suitable proportion of conventional meta-aramid fibers, the prepared heat-insulating felt can maintain good strength properties while having good heat-insulating and flame-retardant properties.

[0023] In the preparation method of the heat-insulating felt described in the present invention, by using an appropriate amount of talc powder to treat the meta-aramid aerogel and coordinating with a suitable environmental humidity, it can solve the problem that the meta-aramid aerogel fibers affect the smooth processing and preparation of the heat-insulating felt due to electrostatic action, and at the same time avoid the problems of powder falling and obvious damage to the strength properties of the heat-insulating felt, thereby obtaining a heat-insulating felt with more excellent performance.

[0024] In addition, in the preparation method of the heat-insulating felt described in the present invention, by adopting appropriate opening and carding conditions, the conventional meta-aramid fibers and the short-cut meta-aramid aerogel are evenly distributed, and at the same time, the damage to the aerogel structure during the preparation process is avoided. At the same time, in coordination with appropriate needling conditions, a heat-insulating felt with high strength and high heat insulation is obtained. Specific embodiments

[0025] The following is a detailed description of the specific embodiments of the present invention. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used are only for describing specific embodiments and are not intended to limit the present invention.

[0027] A preparation method of a thermal insulation aerogel aramid heat insulation felt, and the preparation method is as follows:

[0028] S1. Add 2,3-pyrazinedicarboxylic anhydride to the reaction system for polymerizing meta-aramid polymer, react to obtain a spinning dope, prepare fibers by wet spinning, and then stretch, wash, crimp, and freeze-dry the fibers to obtain meta-aramid aerogel filaments;

[0029] S2. Cut the meta-aramid aerogel filaments to obtain short-cut meta-aramid aerogel, and then treat the short-cut meta-aramid aerogel with talcum powder;

[0030] S3. Treat the short-cut meta-aramid aerogel treated with talcum powder and meta-aramid fibers together with a carding and combing machine to make them evenly mixed, and then obtain the thermal insulation aerogel aramid heat insulation felt through needling treatment.

[0031] Specifically, in step S1, m-phenylenediamine and 2,3-pyrazinedicarboxylic anhydride are dissolved in a corresponding solvent, and then m-phthaloyl chloride is added for condensation polymerization to prepare a meta-aramid polymer. The addition amount of the 2,3-pyrazinedicarboxylic anhydride is 0.1-0.5% of the molar amount of m-phenylenediamine. After the reaction, neutralization is carried out to obtain a spinning dope, and the viscosity of the spinning dope at 25°C is 1000-1500 Po.

[0032] More specifically, the molar ratio of m-phenylenediamine to m-phthaloyl chloride is 1:(0.99-1.00). The solvent used in the condensation polymerization reaction process is DMAC, DMF, DMSO or NMP, and the reaction temperature is 10-20°C; when carrying out neutralization treatment, the neutralizing reagent added is calcium hydroxide or sodium hydroxide.

[0033] Specifically, two-stage coagulation baths are used in the wet spinning process. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 10-15%, the length of the first-stage coagulation bath is 0.3-0.5 m, and the temperature is 50-60°C;

[0034] The second coagulation bath is a mixed solution of DMAC, water and calcium chloride. The mass concentration of calcium chloride is 0.5 - 2%, the mass concentration of DMAC is 80 - 85%, the length of the second coagulation bath is 8 - 10 m, and the temperature is 5 - 10 °C.

[0035] The first coagulation bath can enable the fiber to form a dense skin-core structure so that internal pores are formed in the fiber. The second coagulation bath can enable the calcium chloride (chloride salt) inside the fiber to be slowly exchanged with the coagulation bath, forming a complete chloride salt leaving channel inside the fiber, ensuring that more dense pores are formed in the fiber.

[0036] More specifically, in the embodiments of the present invention, the specific conditions for stretching, water washing, crimping and freeze-drying of the meta-aramid aerogel tow are as follows: the draw ratio is 1.45 - 1.50, the water washing temperature is 30 - 35 °C, and freeze-drying is carried out in a gradient freeze-drying manner, that is, freeze-drying at -20 °C for 4 hours, freeze-drying at 0 °C for 4 hours, and freeze-drying at 10 °C for 48 hours to obtain the meta-aramid aerogel tow.

[0037] More specifically, for the meta-aramid aerogel tow, the fiber fineness is 1 - 10 D, and the CV% of the fiber fineness ≤ 5%.

[0038] Specifically, the length of the chopped meta-aramid aerogel is 20 - 100 mm, and the addition amount of the talcum powder is 0.5 - 1 wt% of the mass of the chopped meta-aramid aerogel.

[0039] More specifically, the talcum powder is conventional nano-scale talcum powder or silane-modified talcum powder.

[0040] More preferably, the talcum powder is silane-modified talcum powder, specifically nano-scale talcum powder with a particle size < 1 μm. The silane-modified talcum powder is obtained by self-preparation. The specific preparation method is as follows: calcine the talcum powder (300 °C) to remove water; dissolve the silane coupling agent (KH-550) in an ethanol / water mixed solvent (weight ratio of 1:1) to obtain a silane solution; then add the calcined talcum powder to the silane solution and stir and react at 80 °C for 2 h, where the silane coupling agent is 3% of the mass of the talcum powder. After the reaction, centrifuge and dry to obtain the silane-modified talcum powder.

[0041] Using silane-modified talcum powder is more conducive to uniform dispersion in the chopped meta-aramid aerogel, and has a high binding degree with meta-aramid, which is beneficial to solving the problem of large static electricity and inability to continuously produce during the production of thermal insulation felts.

[0042] Specifically, the mass ratio of the chopped meta-aramid aerogel to the meta-aramid fiber (Taimeda N602) is 1:(0.2 - 0.4).

[0043] Specifically, during the opening process, short-cut meta-aramid aerogel is first used, and then the meta-aramid fiber is gradually added. The opening speed of the short-cut meta-aramid aerogel is 8-10 m / min, and the opening speed of the meta-aramid fiber is 2-4 m / min; the opening pressure is 0.1-0.5 Mpa.

[0044] Specifically, during the carding process, nitrogen is used for purging, and the nitrogen flow rate is 0.2-0.5 m 3 / min.

[0045] Specifically, in step S3, the environmental humidity is controlled to be 60%-65%, the needling thickness is 3-8 mm, and the needling density is 100-150 needles / cm 2 . Under the conditions of this needling thickness and needling density, the pore structure of the meta-aramid aerogel can be damaged less, and the problem of strength reduction of the thermal insulation felt caused by the high softness of the meta-aramid aerogel can be reduced, so as to obtain a thermal insulation felt with high strength and high heat preservation performance.

[0046] A thermal insulation aerogel aramid felt, which is prepared according to the preparation method described in the present invention.

[0047] Specifically, the grammage of the thermal insulation aerogel aramid felt is 150-200 g / m 2 , the thermal conductivity is 0.005-0.015 W / m·K, and the strength of the aerogel felt fabric is 110-150 MPa.

[0048] Example 1

[0049] S1. m-Phenylenediamine, isophthaloyl chloride and 2,3-pyrazinedicarboxylic anhydride are subjected to a polymerization reaction in DMAC, wherein the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:0.99, and the addition amount of 2,3-pyrazinedicarboxylic anhydride is 0.3% of the molar number of m-phenylenediamine. After the reaction is completed, sodium hydroxide is added for neutralization to obtain a spinning dope. The viscosity of the spinning dope is 1052 Po. Fibers are prepared by wet spinning, and then the fibers are stretched, washed, crimped and freeze-dried to form the meta-aramid aerogel fiber bundle;

[0050] Among them, during the wet spinning process, two-stage coagulation baths are used for treatment. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 10%, the length of the first-stage coagulation bath is 0.3 m, and the temperature is 50 °C;

[0051] The second-stage coagulation bath is a mixed solution of DMAC, water and calcium chloride. The mass concentration of calcium chloride is 0.5%, the mass concentration of DMAC is 80%, the length of the second-stage coagulation bath is 8 m, and the temperature is 5 °C.

[0052] S2. Cut the meta-aramid aerogel tow into short meta-aramid aerogel, and then treat the short meta-aramid aerogel with talcum powder; the talcum powder is conventional nano-scale talcum powder, and the addition amount of talcum powder is 0.5 wt% of the mass of the short meta-aramid aerogel.

[0053] S3. Treat the short meta-aramid aerogel treated with talcum powder and meta-aramid fiber together using a carding and combing machine to make them evenly mixed, and then obtain the thermal insulation aerogel aramid thermal insulation felt through needling treatment;

[0054] Among them, the mass ratio of the short meta-aramid aerogel to the meta-aramid fiber is 1:0.2. In the carding process, the short meta-aramid aerogel is used first, and then the meta-aramid fiber is gradually added. The carding speed of the short meta-aramid aerogel is 10 m / min, and the carding speed of the meta-aramid fiber is 4 m / min; the carding pressure is 0.1 Mpa; during the combing process, nitrogen is used for purging, and the nitrogen flow rate is 0.2 m 3 / min; control the environmental humidity to 60%, the needling thickness to 3 mm, and the needling density to 150 needles / cm 2 .

[0055] Example 2

[0056] S1. m-Phenylenediamine, isophthaloyl chloride and 2,3-pyrazinedicarboxylic anhydride are polymerized in DMF. The molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:0.992, and the addition amount of 2,3-pyrazinedicarboxylic anhydride is 0.1% of the molar number of m-phenylenediamine. After the reaction, sodium hydroxide is added for neutralization to obtain a spinning dope. The viscosity of the spinning dope is 1132 Po. Fibers are prepared by wet spinning, and then the fibers are stretched, washed, crimped, and freeze-dried to make the meta-aramid aerogel tow;

[0057] Among them, during the wet spinning process, two-stage coagulation baths are used for treatment. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 11%, the length of the first-stage coagulation bath is 0.35 m, and the temperature is 53 °C;

[0058] The second-stage coagulation bath is a mixed solution of DMAC, water and calcium chloride. The mass concentration of calcium chloride is 1.0%, the mass concentration of DMAC is 81%, the length of the second-stage coagulation bath is 8.5 m, and the temperature is 6 °C.

[0059] S2. Cut the meta-aramid aerogel tow into short meta-aramid aerogel, and then treat the short meta-aramid aerogel with talcum powder; the talcum powder is conventional nano-scale talcum powder, and the addition amount of talcum powder is 1 wt% of the mass of the short meta-aramid aerogel.

[0060] S3. Use the opened and carded short-cut meta-aramid aerogel after being treated with talcum powder and meta-aramid fiber together by using opening and carding machines to make them evenly mixed, and then obtain the heat-insulating aerogel aramid thermal insulation felt through needling treatment;

[0061] Among them, the mass ratio of the short-cut meta-aramid aerogel to the meta-aramid fiber is 1:0.25. During the opening process, first use the short-cut meta-aramid aerogel, and then gradually add the meta-aramid fiber. The opening speed of the short-cut meta-aramid aerogel is 8 m / min, and the opening speed of the meta-aramid fiber is 2 m / min; the opening pressure is 0.2 Mpa; during the carding process, nitrogen is used for purging, and the nitrogen flow rate is 0.5 m 3 / min; control the environmental humidity to be 61%, the needling thickness to be 5 mm, and the needling density to be 130 needles / cm 2 .

[0062] Example 3

[0063] S1. m-Phenylenediamine, isophthaloyl chloride and 2,3-pyrazinedicarboxylic anhydride are subjected to a polymerization reaction in DMSO. Among them, the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:0.994, and the addition amount of 2,3-pyrazinedicarboxylic anhydride is 0.5% of the molar number of m-phenylenediamine. After the reaction ends, sodium hydroxide is added for neutralization to obtain a spinning dope. The viscosity of the spinning dope is 1465 Po. Fibers are prepared by wet spinning, and then the fibers are stretched, washed, crimped, and freeze-dried to make the meta-aramid aerogel filament bundle;

[0064] Among them, during the wet spinning process, two-stage coagulation baths are used for treatment. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 12%, the length of the first-stage coagulation bath is 0.4 m, and the temperature is 535 °C;

[0065] The second-stage coagulation bath is a mixed solution of DMAC, water and calcium chloride. The mass concentration of calcium chloride is 1.5%, the mass concentration of DMAC is 82%, the length of the second-stage coagulation bath is 9.5 m, and the temperature is 8 °C.

[0066] S2. Cut the meta-aramid aerogel filament bundle to obtain short-cut meta-aramid aerogel, and then use talcum powder to treat the short-cut meta-aramid aerogel; the talcum powder is conventional nano-scale talcum powder, and the addition amount of talcum powder is 0.8 wt% of the mass of the short-cut meta-aramid aerogel.

[0067] S3. Use the opened and carded short-cut meta-aramid aerogel after being treated with talcum powder and meta-aramid fiber together by using opening and carding machines to make them evenly mixed, and then obtain the heat-insulating aerogel aramid thermal insulation felt through needling treatment;

[0068] Among them, the mass ratio of the chopped meta-aramid aerogel to the meta-aramid fiber is 1:0.3. During the opening process, the chopped meta-aramid aerogel is used first, and then the meta-aramid fiber is gradually added. The opening speed of the chopped meta-aramid aerogel is 9 m / min, and the opening speed of the meta-aramid fiber is 3 m / min; the opening pressure is 0.3 Mpa; during the carding process, nitrogen is used for purging, and the nitrogen flow rate is 0.3 m 3 / min; the environmental humidity is controlled at 62%, the needling thickness is 7 mm, and the needling density is 120 needles / cm 2 .

[0069] Example 4

[0070] S1. m-Phenylenediamine, isophthaloyl chloride and 2,3-pyrazinedicarboxylic anhydride are subjected to a polymerization reaction in DMF. Among them, the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:0.996, and the addition amount of 2,3-pyrazinedicarboxylic anhydride is 0.2% of the molar number of m-phenylenediamine. After the reaction is completed, sodium hydroxide is added for neutralization to obtain a spinning dope. The viscosity of the spinning dope is 1311 Po. Fibers are prepared by wet spinning, and then the fibers are stretched, washed, crimped, and freeze-dried to make the meta-aramid aerogel tow;

[0071] Among them, during the wet spinning process, two-stage coagulation baths are used for treatment. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 13%, the length of the first-stage coagulation bath is 0.45 m, and the temperature is 57 °C;

[0072] The second-stage coagulation bath is a mixed solution of DMAC, water and calcium chloride. The mass concentration of calcium chloride is 1.8%, the mass concentration of DMAC is 84%, the length of the second-stage coagulation bath is 9 m, and the temperature is 9 °C.

[0073] S2. The meta-aramid aerogel tow is cut to obtain chopped meta-aramid aerogel, and then the chopped meta-aramid aerogel is treated with talcum powder; the talcum powder is conventional nano-scale talcum powder, and the addition amount of talcum powder is 0.7 wt% of the mass of the chopped meta-aramid aerogel.

[0074] S3. The chopped meta-aramid aerogel treated with talcum powder and the meta-aramid fiber are jointly processed by an opening and carding machine to make them evenly mixed, and then the heat-insulating aerogel aramid thermal insulation felt is obtained through needling treatment;

[0075] Among them, the mass ratio of the chopped meta-aramid aerogel to the meta-aramid fiber is 1:0.35. During the opening process, the chopped meta-aramid aerogel is used first, and then the meta-aramid fiber is gradually added. The opening speed of the chopped meta-aramid aerogel is 10 m / min, and the opening speed of the meta-aramid fiber is 4 m / min; the opening pressure is 0.4 Mpa; during the carding process, nitrogen is used for purging, and the nitrogen flow rate is 0.5 m 3 / min; the environmental humidity is controlled to be 63%, the needling thickness is 9 mm, and the needling density is 110 needles / cm 2 .

[0076] Example 5

[0077] S1. m-Phenylenediamine, isophthaloyl chloride and 2,3-pyrazinedicarboxylic anhydride are subjected to a polymerization reaction in DMAC, where the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:0.998, and the addition amount of 2,3-pyrazinedicarboxylic anhydride is 0.4% of the molar amount of m-phenylenediamine. After the reaction is completed, sodium hydroxide is added for neutralization to obtain a spinning dope. The viscosity of the spinning dope is 1285 Po. Fibers are prepared by wet spinning, and then the fibers are stretched, washed, crimped, and freeze-dried to obtain the meta-aramid aerogel tow;

[0078] Among them, during the wet spinning process, two-stage coagulation baths are used for treatment. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 15%, the length of the first-stage coagulation bath is 0.5 m, and the temperature is 60°C;

[0079] The second-stage coagulation bath is a mixed solution of DMAC, water and calcium chloride, the mass concentration of calcium chloride is 2%, the mass concentration of DMAC is 85%, the length of the second-stage coagulation bath is 10 m, and the temperature is 10°C.

[0080] S2. The meta-aramid aerogel tow is cut to obtain chopped meta-aramid aerogel, and then the chopped meta-aramid aerogel is treated with talcum powder; the talcum powder is conventional nano-scale talcum powder, and the addition amount of talcum powder is 0.6 wt% of the mass of the chopped meta-aramid aerogel.

[0081] S3. The chopped meta-aramid aerogel treated with talcum powder and the meta-aramid fiber are jointly processed by opening and carding machines to make them evenly mixed, and then the thermal insulation aerogel aramid thermal insulation felt is obtained through needling treatment;

[0082] Among them, the mass ratio of the chopped meta-aramid aerogel to the meta-aramid fiber is 1:0.4. During the opening process, the chopped meta-aramid aerogel is used first, and then the meta-aramid fiber is gradually added. The opening speed of the chopped meta-aramid aerogel is 10 m / min, and the opening speed of the meta-aramid fiber is 4 m / min; the opening pressure is 0.5 Mpa; during the carding process, nitrogen is used for purging, and the nitrogen flow rate is 0.5 m 3 / min; the environmental humidity is controlled at 65%, the needling thickness is 10 mm, and the needling density is 100 needles / cm 2 .

[0083] Example 6

[0084] S1. m-Phenylenediamine, isophthaloyl chloride and 2,3-pyrazinedicarboxylic anhydride are subjected to a polymerization reaction in DMAC. The molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:0.99, and the addition amount of 2,3-pyrazinedicarboxylic anhydride is 0.3% of the molar amount of m-phenylenediamine. After the reaction is completed, sodium hydroxide is added for neutralization to obtain a spinning dope. The viscosity of the spinning dope is 1052 Po. Fibers are prepared by wet spinning, and then the fibers are stretched, washed, crimped, and freeze-dried to obtain the meta-aramid aerogel fiber bundle;

[0085] Among them, during the wet spinning process, two-stage coagulation baths are used for treatment. The first-stage coagulation bath is a mixed solution of DMAC and water, the mass concentration of DMAC is 10%, the length of the first-stage coagulation bath is 0.3 m, and the temperature is 50 °C;

[0086] The second-stage coagulation bath is a mixed solution of DMAC, water and calcium chloride. The mass concentration of calcium chloride is 0.5%, the mass concentration of DMAC is 80%, the length of the second-stage coagulation bath is 8 m, and the temperature is 5 °C.

[0087] S2. The meta-aramid aerogel fiber bundle is cut to obtain chopped meta-aramid aerogel, and then the chopped meta-aramid aerogel is treated with talcum powder; the talcum powder is silane-modified talcum powder, and the addition amount of talcum powder is 0.5 wt% of the mass of the chopped meta-aramid aerogel.

[0088] S3. The chopped meta-aramid aerogel treated with talcum powder and the meta-aramid fiber are jointly processed by an opening and carding machine to make them evenly mixed, and then the heat-insulating aerogel aramid thermal insulation felt is obtained through needling treatment;

[0089] Among them, the mass ratio of the chopped meta-aramid aerogel to the meta-aramid fiber is 1:0.2. During the opening process, the chopped meta-aramid aerogel is used first, and then the meta-aramid fiber is gradually added. The opening speed of the chopped meta-aramid aerogel is 10 m / min, and the opening speed of the meta-aramid fiber is 4 m / min; the opening pressure is 0.1 Mpa; during the carding process, nitrogen is used for purging, and the nitrogen flow rate is 0.2 m 3 / min; the environmental humidity is controlled at 60%, the needling thickness is 3 mm, and the needling density is 150 needles / cm 2 .

[0090] Comparative Example 1

[0091] The heat insulation felt was prepared by the same method as in Example 1, except that: 2,3-pyrazinedicarboxylic anhydride was not added in step S1 of this Comparative Example 1.

[0092] Comparative Example 2

[0093] The spinning dope was prepared by the same method as in Example 1, except that: the dosage ratio of 2,3-pyrazinedicarboxylic anhydride was increased in this Comparative Example 2, and the addition amount of 2,3-pyrazinedicarboxylic anhydride in this Comparative Example 2 was 1% of the molar amount of m-phenylenediamine. During the preparation process, it was found that serious explosive polymerization occurred in the system, and a spinning dope suitable for the spinning process could not be prepared.

[0094] Comparative Example 3

[0095] The heat insulation felt was prepared by the same method as in Example 1, except that: in step S1 of this Comparative Example 3, during the wet spinning process, only one-stage coagulation bath treatment was adopted, and there was no first-stage coagulation bath in this Comparative Example 3, and only the second-stage coagulation bath was carried out.

[0096] Comparative Example 4

[0097] The heat insulation felt was prepared by the same method as in Example 1, except that: in step S2 of this Comparative Example 4, talcum powder was not used to treat the chopped meta-aramid aerogel. During the opening and carding processes, the electrostatic effect of the chopped meta-aramid aerogel was relatively strong, and the smooth preparation of the heat insulation felt could not be achieved.

[0098] Comparative Example 5

[0099] The heat insulation felt was prepared by the same method as in Example 1, except that: the dosage of talcum powder was increased in this Comparative Example 5, and the addition amount of talcum powder in this Comparative Example 5 was 1.5 wt% of the mass of the chopped meta-aramid aerogel.

[0100] Comparative Example 6

[0101] The heat insulation felt was prepared by the same method as in Example 1, except that in step S3 of Comparative Example 6, nitrogen purging was not carried out during the carding process.

[0102] Comparative Example 7

[0103] The heat insulation felt was prepared by the same method as in Example 1, except that in step S3 of Comparative Example 7, the chopped meta-aramid aerogel and meta-aramid fiber were mixed to form mixed fibers, and then the mixed fibers were opened together at an opening speed of 10 m / min.

[0104] Comparative Example 8

[0105] The heat insulation felt was prepared by the same method as in Example 1, except that in step S3 of Comparative Example 8, the opening speed of the chopped meta-aramid aerogel was increased, and the opening speed of the chopped meta-aramid aerogel in Comparative Example 8 was 12 m / min.

[0106] Comparative Example 9

[0107] The heat insulation felt was prepared by the same method as in Example 1, except that in step S4 of Comparative Example 9, the needling thickness was increased, and the needling thickness in Comparative Example 9 was 10 mm.

[0108] The heat insulation felts prepared in the above examples and comparative examples were subjected to performance tests. The specific test results are shown in Table 1 below. The test methods involved are: the thermal conductivity test was carried out according to the method of GB / T 11048-2008, and the limiting oxygen index test was carried out according to GB5454-85.

[0109] Table 1 Performance test results of heat insulation felt

[0110]

[0111] It can be seen from the above table data that the heat insulation felts prepared by the preparation method described in the present invention in Examples 1-6 have good heat insulation performance, strength performance, and good flame retardant performance, and can be applied in some high-temperature environment fields. Moreover, all the materials are meta-aramid, which is more conducive to subsequent recycling and reuse. In addition, it can be seen from the data comparison between Example 1 and Example 6 that when using silane-modified talc powder, it is more conducive to maintaining the heat insulation performance and strength performance of the heat insulation felt.

[0112] It can be seen from the data comparison between Comparative Example 1 and Example 1 that if 2,3-pyrazinedicarboxylic anhydride is not added in step S1, the strength performance of the thermal insulation felt will decrease. When 2,3-pyrazinedicarboxylic anhydride is added during the polymerization process, the amine group and the anhydride can undergo a ring-opening reaction, and pyrazine reacts with acyl chloride to form a cross-linked structure, improving the strength of the meta-aramid aerogel fiber bundle. This is beneficial for the thermal insulation felt to have good strength. In addition, due to the high strength of the meta-aramid aerogel fiber bundle, the damage to the aerogel structure during the processing of the thermal insulation felt can be reduced, thereby obtaining a thermal insulation felt with excellent strength performance and thermal insulation performance.

[0113] It can be seen from the data of Comparative Example 2 that if the addition amount of 2,3-pyrazinedicarboxylic anhydride is too much, it will lead to explosive polymerization. Therefore, using the amount of 2,3-pyrazinedicarboxylic anhydride defined in the present invention is more conducive to the smooth production of high-quality meta-aramid aerogel.

[0114] It can be seen from the data comparison between Comparative Example 3 and Example 1 that if only one-stage coagulation bath treatment is carried out during the processing of the meta-aramid aerogel fiber bundle, the strength performance of the meta-aramid aerogel fiber bundle will be greatly reduced, ultimately resulting in a decrease in the strength performance of the thermal insulation felt. In addition, due to the low strength of the meta-aramid aerogel fiber bundle, the pore structure of the aerogel is extremely vulnerable to damage during the processing of the thermal insulation felt, also leading to a decrease in the thermal insulation effect of the thermal insulation felt.

[0115] It can be seen from the data comparison between Comparative Example 4 and Example 1 that if talcum powder is not used in step S2, the electrostatic interaction of the meta-aramid is very large, and the processing of the thermal insulation felt cannot be achieved.

[0116] It can be seen from the data comparison between Comparative Example 5 and Example 1 that if the usage amount of talcum powder in step S2 is too much, the talcum powder is likely to agglomerate in the chopped meta-aramid aerogel, causing powder dropping problems in the thermal insulation felt and overall affecting the product quality of the thermal insulation felt.

[0117] It can be seen from the data comparison between Comparative Example 6 and Example 1 that if nitrogen purging is not carried out during the carding process, it is not conducive to the uniform combination between the chopped meta-aramid aerogel and the meta-aramid fiber, ultimately affecting the comprehensive performance of the thermal insulation felt.

[0118] It can be seen from the data comparison between Comparative Example 7 and Example 1 that if the chopped meta-aramid aerogel and the meta-aramid fiber are directly opened after being mixed to form a mixed fiber in step S3, it is not conducive to the uniform combination between the chopped meta-aramid aerogel and the meta-aramid fiber, ultimately also affecting the comprehensive performance of the thermal insulation felt.

[0119] It can be seen from the data comparison between Comparative Example 8 and Example 1 that if the opening speed of the chopped meta-aramid aerogel is increased, the heat insulation performance of the heat insulation felt will decrease. Because an inappropriate opening speed will cause damage to the aerogel structure of the chopped meta-aramid aerogel during the opening process, and it is not conducive to the uniform combination of the chopped meta-aramid aerogel and the meta-aramid fiber. Therefore, adopting the opening conditions defined in the present invention is more conducive to obtaining a heat insulation felt product with excellent comprehensive performance.

[0120] It can be seen from the data comparison between Comparative Example 9 and Example 1 that if the needling thickness is increased in step S4, the heat insulation performance of the heat insulation felt will decrease. Because when the needling thickness increases, it is very likely to affect the pore structure of the aerogel, ultimately resulting in a decrease in the heat insulation performance.

[0121] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, all possible combinations of the various technical features in the above-described embodiments are not exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0122] For those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. A method for preparing a thermal insulation aerogel aramid insulation felt, characterized in that: The preparation method is: S1. Adding 2,3-pyrazine dianhydride to a reaction system for preparing meta-aramid polymer by polymerization to react to obtain a spinning solution, preparing fibers by wet spinning, and then stretching, washing, curling, and freeze-drying the fibers to prepare meta-aramid aerogel tows; S2, cutting the meta-aramid aerogel tow to obtain a chopped meta-aramid aerogel tow, and then treating the chopped meta-aramid aerogel tow with talcum powder; S3, treating the talcum powder treated short-cut meta-aramid aerogel tow and the meta-aramid fiber together using an opening and carding machine to make them evenly mixed, and then subjecting them to a needle punching treatment to obtain the thermal insulation aerogel aramid insulation felt; In step S1, 2,3-pyrazine dianhydride is added during the condensation polymerization of m-phenylenediamine and isophthaloyl chloride to prepare a m-aramid polymer, wherein the amount of 2,3-pyrazine dianhydride added is 0.1-0.5% of the molar number of m-phenylenediamine, and after the reaction is completed, the spinning solution is obtained by neutralization; Two coagulation baths are used in the wet spinning process. The first coagulation bath is a mixed solution of DMAC and water, with a DMAC mass concentration of 10-15%. The length of the first coagulation bath is 0.3-0.5 m, and the temperature is 50-60°C. The second coagulation bath is a mixed solution of DMAC, water and calcium chloride, the mass concentration of calcium chloride is 0.5-2%, the mass concentration of DMAC is 80-85%, the length of the second coagulation bath is 8-10m, and the temperature is 5-10℃.

2. The method for preparing the thermal insulation aerogel aramid insulation felt according to claim 1, characterized in that: The viscosity of the spinning solution at 25° C. is 1000-1500 Po.

3. The method for preparing the thermal insulation aerogel aramid insulation felt according to claim 1, characterized in that: The length of the short-cut meta-aramid aerogel bundle is 20-100 mm, and the amount of talcum powder added is 0.5-1 wt % of the mass of the short-cut meta-aramid aerogel bundle.

4. The method for preparing the thermal insulation aerogel aramid insulation felt according to claim 1, characterized in that: The mass ratio of the short-cut meta-aramid aerogel tow to the meta-aramid fiber is 1:(0.2-0.4).

5. The method for preparing the thermal insulation aerogel aramid insulation felt according to claim 1, characterized in that: In the opening process, short-cut meta-aramid aerogel tows are first used, and then the meta-aramid fibers are gradually added. The opening speed of the short-cut meta-aramid aerogel tows is 8-10 m / min, and the opening speed of the meta-aramid fibers is 2-4 m / min; the opening pressure is 0.1-0.5 MPa.

6. The method for preparing the thermal insulation aerogel aramid insulation felt according to claim 1, characterized in that: During the carding process, nitrogen is used for purging, and the nitrogen flow rate is 0.2-0.5 m 3 / min.

7. The method for preparing the thermal insulation aerogel aramid insulation felt according to claim 1, characterized in that: In step S3, the ambient humidity is controlled to be 60%-65%, the acupuncture thickness is 3-8 mm, and the acupuncture density is 100-150 needles / cm 2 .

8. A thermal insulation aerogel aramid insulation felt, characterized in that: The thermal insulation aerogel aramid insulation felt is prepared according to the preparation method according to any one of claims 1-7.

9. The thermal insulation aerogel aramid insulation felt according to claim 8, characterized in that: The thermal insulation aerogel aramid insulation felt has a gram weight of 150-200 g / m 2 , thermal conductivity is 0.005-0.015 W / m·K, and the strength of aerogel felt is 110-150MPa.

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