阅读说明：本技术 一种聚酰亚胺气凝胶纤维及其制备和应用 (Polyimide aerogel fiber and preparation and application thereof ) 是由 张清华 李猛猛 赵昕 董杰 张培炎 甘锋 郑森森 于 2020-06-17 设计创作，主要内容包括：本发明涉及一种聚酰亚胺气凝胶纤维及其制备和应用,所述纤维以含二元酐、二元胺为原料,通过湿法纺丝、冷冻干燥,获得。本发明方法操作简单,工艺环保,有利于大规模生产。该方法制备的聚酰亚胺气凝胶纤维材料,强度高,耐热性好,同时具有优异的隔热保温特性,可广泛应用于制备各种保温隔热领域。(The invention relates to a polyimide aerogel fiber, and preparation and application thereof. The method has simple operation and environment-friendly process, and is beneficial to large-scale production. The polyimide aerogel fiber material prepared by the method has high strength, good heat resistance and excellent heat insulation property, and can be widely applied to the preparation of various heat insulation fields.)

1. The polyimide aerogel fiber is characterized by being obtained by taking dicarboxylic anhydride and diamine as raw materials through wet spinning and freeze drying.

2. The fiber of claim 1, wherein the dibasic anhydride is one or more of 4,4' - (hexafluoroisopropylidene) diphthalic anhydride 6FDA, 3,3',4,4' -benzophenonetetracarboxylic dianhydride BTDA, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride A-ODPA; the diamine is one or more of 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl TFMB, 4-diaminodiphenyl ether ODA, 2- (4-aminophenyl) -5-aminobenzimidazole BIA and 3, 5-diaminobenzoic acid DABA diamine.

3. The fiber of claim 1, wherein the polyimide aerogel fiber is of a dense structure, wherein the skin layer of the fiber is of a dense structure, and the inside of the fiber is of a spatial network structure; the diameter of the fiber is 20 to 500 μm.

4. A method of preparing a polyimide aerogel fiber, comprising:

(1) dissolving equimolar dibasic anhydride and diamine in a polar aprotic solvent, carrying out ice-bath reaction, and raising the reaction temperature to 10-200 ℃ for reaction for 4-6 h to obtain a spinning stock solution;

(2) and (2) carrying out wet spinning on the spinning solution obtained in the step (1), and then carrying out aging and freeze drying in water to obtain the polyimide aerogel fiber.

5. The preparation method according to claim 4, wherein the dibasic anhydride in the step (1) is one or more selected from 4,4' - (hexafluoroisopropylidene) diphthalic anhydride 6FDA, 3,3',4,4' -benzophenonetetracarboxylic dianhydride BTDA, and 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride A-ODPA; the diamine is one or more of 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl TFMB, 4-diaminodiphenyl ether ODA, 2- (4-aminophenyl) -5-aminobenzimidazole BIA and 3, 5-diaminobenzoic acid DABA diamine; the polar aprotic solvent is N-methylpyrrolidone NMP and/or imidazolidinone DMI.

6. The preparation method according to claim 4, wherein the dibasic anhydride and the diamine in the step (1) account for 8-12% of the total mass of the system.

7. The preparation method according to claim 4, wherein the coagulation bath for wet spinning in the step (2) is water, the temperature of the coagulation bath is 0-100 ℃, the spinning speed is 1-10 m/min, and the winding speed is 1-15 m/min; and the aging is carried out in water for 24-96 h.

8. The preparation method according to claim 4, wherein the freeze-drying temperature in the step (2) is-40 to-80 ℃, the pressure is 0.1Pa to 40Pa, and the time is 24h to 96 h; and performing hot drawing after the freeze drying, wherein the hot drawing temperature is 380-450 ℃, and the winding speed is 0.1-2 m/min.

9. A polyimide aerogel fiber prepared by the method of claim 4.

10. Use of the polyimide aerogel fiber of claim 1.

Technical Field

The invention belongs to the field of organic aerogel fibers and preparation thereof, and particularly relates to a polyimide aerogel fiber and preparation and application thereof.

Background

The aerogel is a continuous network-shaped porous material with low density, high specific surface area, high porosity and low thermal conductivity, has a unique three-dimensional network-shaped porous structure, has obvious application advantages in the fields of heat insulation protection, electromagnetic shielding, sound absorption and shock absorption, catalyst carriers and the like, and is considered as a substitute for a traditional foam material. At present, the types of aerogels are rich and varied, mainly comprising silicon dioxide, cellulose, carbon material aerogel and the like, and the chemical structure and the microstructure of the aerogel have important influence on the physical and chemical properties of the aerogel. The polyimide aerogel material has wide application prospect in the fields of aerospace, heat insulation protection, catalyst carriers and the like due to the characteristics of light weight, flexibility, high strength, high modulus, irradiation resistance and unique high and low temperature resistance. However, the prior polyimide aerogel materials are mainly block or film materials, and have low bending degree, poor toughness and poor knitting ability, so that the application of the polyimide aerogel materials in the aspects of precise and complex structures, thermal protection clothes and the like is limited. Compared with polyimide films or blocks, the polyimide aerogel fibers have excellent flexibility and good weaving property, and are more convenient to apply to different fields. However, in the conventional preparation process of polyimide aerogel, a cross-linking agent is mostly added in the gelling process to rapidly cross-link and form a polymer to form a gel structure, so that the polymer stock solution loses fluidity, and gel fibers cannot be formed by continuous processing. Meanwhile, when the aerogel is obtained by drying the aerogel fiber, the aerogel fiber is easy to shrink and poor in dimensional stability, and meanwhile, due to the porous structure of the aerogel fiber, the mechanical property of the aerogel fiber is poor, so that the mechanical requirement of weaving is difficult to meet, and the high mechanical property of the aerogel fiber is guaranteed while the porous property of the aerogel fiber is guaranteed, so that the scientific problem to be solved urgently is solved.

CN 110372907A discloses a nanofiber reinforced polyimide aerogel material and a preparation method thereof, which comprises adding micromolecule triethylamine into a polyamic acid solution to make polyamic acid into organic salt, then chopping polyimide nanofibers to be used as nano-fillers, and then preparing the nanofiber reinforced polyimide aerogel material by a freeze-drying technology. The method has complex preparation process. In the preparation process, triethylamine micromolecules are added, so that the triethylamine micromolecules are difficult to completely remove, defects exist in the prepared aerogel easily, and meanwhile, the environment pollution is easily caused. The other opposite side nano fiber is difficult to be uniformly dispersed in the dispersing process, and the partial aggregation of the nano fiber easily causes defects to the prepared aerogel material. The invention directly adopts a wet spinning process, and the soluble polyimide is directly spun without adding micromolecules or other filling phases which are easy to aggregate in the process. Meanwhile, in the spinning process, water is used as a coagulating bath, so that the method is environment-friendly and pollution-free, and can be used for continuously, massively and rapidly preparing the polyimide aerogel fiber material.

Disclosure of Invention

The invention aims to solve the technical problem of providing a polyimide aerogel fiber, and preparation and application thereof, and fills the blank of organic aerogel fibers. The polyimide aerogel fiber with a sparse-dense structure is prepared by directly using soluble polyimide containing carboxyl as a spinning solution through a wet spinning process and a freeze drying technology.

The polyimide aerogel fiber is obtained by taking dicarboxylic anhydride and diamine as raw materials through wet spinning and freeze drying.

The binary anhydride is one or more of 4,4' - (hexafluoroisopropylidene) diphthalic anhydride 6FDA, 3,3',4,4' -benzophenonetetracarboxylic dianhydride BTDA and 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride A-ODPA; the diamine is one or more of 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl TFMB, 4-diaminodiphenyl ether ODA, 2- (4-aminophenyl) -5-aminobenzimidazole BIA and 3, 5-diaminobenzoic acid DABA diamine.

The polyimide aerogel fiber is of a dense structure, wherein the skin layer of the fiber is of a dense structure, in the wet spinning process, when a spinning solution enters a coagulating bath (namely water) from a spinning nozzle, a rapid double diffusion phenomenon occurs, a solvent in the fiber rapidly diffuses, so that the skin of the fiber forms a dense skin layer structure, the solvent in the fiber is bound by the skin layer to be mutually dissolved with the water in the fiber, and the solute (polyimide) and the solvent (namely the water and the solvent) are separated from each other, so that a spatial mesh structure is formed in the fiber; the diameter of the fiber is 20 to 500 μm.

The skin layer of the polyimide fiber is of a compact structure, so that the fiber is guaranteed to have high mechanical property, and the interior of the polyimide fiber is of a sparse structure and is of a reticular porous structure.

The preparation method of the polyimide aerogel fiber comprises the following steps:

(1) dissolving equimolar dibasic anhydride and diamine in a polar aprotic solvent, reacting for 6-48 h in an ice bath, raising the reaction temperature to 10-200 ℃ and reacting for 4-6 h to obtain a spinning stock solution;

(2) and (2) carrying out wet spinning, aging and freeze drying on the spinning solution obtained in the step (1) to obtain the sparse-dense-structure high-strength polyimide aerogel fiber.

The preferred mode of the above preparation method is as follows:

the dibasic anhydride in the step (1) is one or more of 4,4' - (hexafluoro-isopropylidene) diphthalic anhydride 6FDA, 3,3',4,4' -benzophenonetetracarboxylic dianhydride BTDA and 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride A-ODPA; the diamine is one or more of 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl TFMB, 4-diaminodiphenyl ether ODA, 2- (4-aminophenyl) -5-aminobenzimidazole BIA and 3, 5-diaminobenzoic acid DABA diamine; the polar aprotic solvent is N-methylpyrrolidone NMP and/or imidazolidinone DMI.

In the step (1), the dibasic anhydride and the diamine account for 8-12% of the total mass of the system.

The coagulation bath for wet spinning in the step (2) is water, the temperature of the coagulation bath is 0-100 ℃, the spinning speed is 1-10 m/min, and the winding speed is 1-15 m/min; and (3) aging the fiber in water for 24-96 hours after aging to wet spinning.

The freeze-drying temperature in the step (2) is-40 to-80 ℃, the pressure is 0.1Pa to 40Pa, and the time is 24h to 96 h.

And performing hot drawing and high-temperature hot drawing processes after freeze drying to orient molecular chains in the fibers and achieve chemical crosslinking, so that the mechanical property of the fibers is improved, and the high-strength and high-modulus polyimide aerogel fibers are obtained.

And performing hot drawing after the freeze drying, wherein the hot drawing temperature is 380-450 ℃, and the winding speed is 0.1-2 m/min.

The invention provides a polyimide aerogel fiber prepared by the method.

The invention provides an application of the polyimide aerogel fiber, such as the field of heat preservation and heat insulation.

The invention provides a preparation method of a high-strength high-modulus polyimide aerogel fiber, which is characterized in that soluble polyimide is used as a spinning solution, a wet spinning process and a freeze drying technology are directly used for preparing the polyimide aerogel fiber with a sparse-dense structure, a dense skin layer is used as a mechanical support, and a loose net structure is arranged inside the polyimide aerogel fiber. Then, the molecular chain of the fiber is oriented and crosslinked at the same time by a hot drawing process, thereby improving the mechanical property of the fiber.

Advantageous effects

(1) The invention uses soluble polyimide as spinning solution, and avoids the secondary thermal imidization or chemical imidization process of preparing polyimide material from polyamic acid.

(2) The method has the advantages of simple process and environment-friendly spinning process, and is suitable for large-scale continuous preparation of the polyimide aerogel fiber.

(3) According to the invention, the polyimide aerogel fiber with a sparse-dense structure is prepared directly through a wet spinning process and a freeze drying technology, a dense skin layer is used as a mechanical support, a loose net structure is arranged inside the polyimide aerogel fiber, molecular chains in the fiber are oriented and crosslinked through hot drafting, and the porous structure of the polyimide aerogel fiber is ensured while the mechanical property of the polyimide aerogel fiber is self-satisfied.

(4) The invention directly adopts a wet spinning process, and the method is simple and effective and is convenient for continuous large-scale production of the polyimide aerogel fiber.

(5) The polyimide aerogel fiber material prepared by the method disclosed by the invention is high in strength, good in heat resistance, and excellent in heat insulation property, and can be widely applied to the preparation of various heat insulation fields.

Drawings

FIG. 1 is SEM photographs of the polyimide aerogel fiber of example 2 at different magnifications of (a), (b), and (c);

FIG. 2 shows the chemical structures of polyimide in examples (a) and (b) showing the chemical structures of polyimide in a cross-linked structure;

fig. 3 is a digital photograph of the polyimide aerogel fiber (a) and its fabric (b) prepared in example 4.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The test method comprises the following steps:

1. fiber linear density, tensile strength and Young's modulus

And testing the mechanical property of the prepared fiber by an XQ-1 monofilament strength tester, and setting the stretching speed to be 10 mm/min.

2. Glass transition temperature

Adopting TA Q20 DMA for testing, wherein the temperature rise rate is 5 ℃/min under the nitrogen atmosphere, and the test temperature range is 25-500 ℃;

3. initial decomposition temperature

Adopting Netzsch TG 209F3 TGA for testing, wherein the temperature rise rate is 10 ℃/min and the test temperature range is 40-900 ℃ in a nitrogen atmosphere;

4. coefficient of thermal conductivity

And testing by using a Hot disk TPS 2500S thermal conductivity meter under an air atmosphere. 5. Density of

The density test was carried out by weighing. And rho is m/V, wherein m is the mass of the fiber, and the volume is obtained by calculating the morphology and the length of the fiber.