阅读说明：本技术 一种高强高模聚吡咙纤维及其制备方法 (High-strength and high-modulus polypyrrolone fiber and preparation method thereof ) 是由 侯豪情 王科遇 黄强 朱咏梅 于 2021-05-28 设计创作，主要内容包括：本申请涉及聚吡咙材料技术领域,具体涉及到一种高强高模聚吡咙纤维及其制备方法。所述聚吡咙纳米纤维的直径为8～15μm。本方案采用了含两个隐形氨基(乙酰氨基)的四氨基联苯(4,4’-二乙酰氨基-3,3’-二氨基联苯)为单体先合成聚酰亚胺的前聚体(聚乙酰氨基酰胺酸),然后将其通过湿法纺丝的方式制备成初生丝,并在空气气氛中亚胺化(300-350℃的高温)形成聚乙酰氨基酰亚胺(聚吡咙的前聚体),再在空气气氛中高温吡咙化(450-500℃的高温)形成高性能聚吡咙聚合物。此外,有效避免了由于聚氨基酰胺酸中的自由氨基活泼,使得该前聚体聚合物不够稳定,容易产生凝胶,使溶液的流动性受到严重影响,以至于不能顺利纺丝等问题的出现。(The application relates to the technical field of polypyrrolone materials, in particular to a high-strength high-modulus polypyrrolone fiber and a preparation method thereof. The diameter of the polypyrrolone nanofiber is 8-15 microns. The technical scheme includes that tetraaminobiphenyl (4,4 '-diacetamido-3, 3' -diaminobiphenyl) containing two invisible amino groups (acetamido) is adopted as a monomer, a polyimide precursor (polyacetylaminoamic acid) is synthesized firstly, then the polyimide precursor is prepared into nascent silk in a wet spinning mode, imidization is carried out in the air atmosphere (high temperature of 300-. In addition, the problems that the prepolymer polymer is not stable enough and is easy to generate gel due to the activity of free amino in the polyaminoamic acid, so that the flowability of the solution is seriously influenced, and the smooth spinning cannot be realized are effectively avoided.)

1. A high-strength high-modulus polypyrrolone fiber, wherein the polypyrrolone compound of the polypyrrolone fiber has the following structure:

the diameter of the polypyrrolone nanofiber is 8-15 microns.

2. The high strength high modulus polypyrrolone fiber according to claim 1, wherein said polypyrrolone fiber has a tensile strength of not less than 1.8 GPa.

3. The high strength high modulus polypyrrolone fiber according to claim 1 or 2, characterized in that the tensile modulus of the polypyrrolone fiber is not less than 80 GPa.

4. The preparation method of the high-strength high-modulus polypyrrolone fiber according to any one of claims 1 to 3, characterized by comprising the following steps:

(1) preparation of raw material monomers: dissolving acetic anhydride in an organic solvent A to obtain a reaction material A, adding the reaction material A into a solution B of an organic solvent for substituting diphenyldiamine, and reacting at a reaction temperature of not higher than 5 ℃ for 2-6 hours to obtain an intermediate crude product; adding calcium oxide into the intermediate crude product for precipitation, filtering and concentrating to obtain a crude product; then recrystallizing the crude product to obtain the raw material monomer;

(2) synthesis of intermediate polyacetylaminoacid: adding the raw material monomer into a reactor, and carrying out condensation reaction with binary acid anhydride in a spinning solvent to obtain a poly (acetylamino-amide) acid solution;

(3) and (3) wet spinning: chemically imidizing the poly-acetamino-amic acid solution at 40-60 ℃ to obtain a semi-chemically imidized poly-acetamino-amic acid solution, filtering, extruding the solution through a spinneret plate at high pressure, coagulating the solution in a coagulating bath, washing and drying to obtain primary silk;

(4) gathering and umbering: and (3) carrying out thermal imidization and drafting on the primary yarn at 280 ℃, then carrying out heating drafting and polypyrrolization at 450-500 ℃, and carrying out post-treatment to obtain the high-strength high-modulus polypyrrolone fiber.

5. The method of claim 4, wherein the acetic anhydride and triethylamine are added in the chemical imidization step in the step (3).

6. The method of claim 4, wherein the coagulant in the coagulation bath in step (3) comprises an aqueous solution of NMP.

7. The method for preparing a high-strength high-modulus polypyrrolone fiber according to claim 6, wherein the coagulant further comprises a spinning solvent in an amount of 5-15 wt%.

8. The preparation method of the high-strength high-modulus polypyrrolone fiber according to the claim 4 to 7, wherein the substituted biphenyldiamine in the step (1) has the following structure:

wherein the substituent R₁And a substituent R₂Each independently is a hydrogen atom or an acetamido group; preferably, the substituent R₁And a substituent R₂Is an acetylamino group.

9. The method of claim 8, wherein the dicarboxylic anhydride in step (2) is selected from one or more of biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, naphthalene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, diphenyl sulfone dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride, and triphenyldiphenyl ether dianhydride.

10. The method for preparing high-strength high-modulus polypyrrolone fiber according to claim 8, wherein the chemical imidization in step (3) is performed for 5-7 hours; preferably, the solution is in a transparent state during the chemical imidization.

Technical Field

The application relates to the technical field of polypyrrolone materials, in particular to a high-strength high-modulus polypyrrolone fiber and a preparation method thereof.

Background

The polypyrrolone is a rigid trapezoidal or semi-trapezoidal polyaromatic heterocyclic macromolecular polymer, has good high temperature resistance and oxidation resistance, and the decomposition temperature of part of polypyrrolone exceeds 700 ℃. The polymer fiber is not only a high-temperature resistant flame-retardant fiber, but also a high-strength high-modulus high-performance fiber. Since the sixties of the last century, the polymers have been widely studied and are generally polymerized in high-boiling solvents such as polyphosphoric acid at high temperatures. Since polypyrrolones are neither melted nor dissolved in common organic solvents, their processability is greatly limited and their application development is greatly hindered. In addition, the traditional preparation method of polypyrrolone crude fiber or film is to dissolve the polypyrrolone crude fiber or film in ultra-strong protonic acid such as methanesulfonic acid, chlorosulfonic acid and the like for processing, and the solvents have strong toxicity and high boiling point, are difficult to remove cleanly from the prepared fiber or film material, and are easy to cause environmental pollution. Therefore, it is necessary to change the synthesis path of polypyrrolone and to perform a two-step synthesis method similar to the preparation of polyimide by synthesizing a pre-polymer of high molecular weight polypyrrolone soluble in common organic solvents, preparing a pre-polymer fiber (or nanofiber) or a pre-polymer film from the pre-polymer solution, and then conducting the polypyrrolone fiber (or nanofiber) or polypyrrolone film through the pre-polymer solution.

Disclosure of Invention

In view of the above technical problems, a first aspect of the present invention provides a high-strength high-modulus polypyrrolone fiber, wherein the polypyrrolone compound of the polypyrrolone fiber has the following structure:

the diameter of the polypyrrolone nanofiber is 8-15 microns.

As a preferable technical scheme of the invention, the tensile strength of the polypyrrolone fiber is not less than 1.8 GPa.

As a preferable technical scheme of the invention, the tensile modulus of the polypyrrolone fiber is not less than 80 GPa.

The second aspect of the present invention provides a method for preparing a high-strength high-modulus polypyrrolone fiber as described above, which comprises the following steps:

(1) preparation of raw material monomers: dissolving acetic anhydride in an organic solvent A to obtain a reaction material A, adding the reaction material A into a solution B of an organic solvent for substituting diphenyldiamine, and reacting at a reaction temperature of not higher than 5 ℃ for 2-6 hours to obtain an intermediate crude product; adding calcium oxide into the intermediate crude product for precipitation, filtering and concentrating to obtain a crude product; then recrystallizing the crude product to obtain the raw material monomer;

(2) synthesis of intermediate polyacetylaminoacid: adding the raw material monomer into a reactor, and carrying out condensation reaction with binary acid anhydride in a spinning solvent to obtain a poly (acetylamino-amide) acid solution;

(3) and (3) wet spinning: chemically imidizing the poly-acetamino-amic acid solution at 40-60 ℃ to obtain a semi-chemically imidized poly-acetamino-amic acid solution, filtering, extruding the solution through a spinneret plate at high pressure, coagulating the solution in a coagulating bath, washing and drying to obtain primary silk;

(4) gathering and umbering: and (3) carrying out thermal imidization and drafting on the primary yarn at 280 ℃, then carrying out heating drafting and polypyrrolization at 450-500 ℃, and carrying out post-treatment to obtain the high-strength high-modulus polypyrrolone fiber.

As a preferred technical scheme of the invention, the required amount of acetic anhydride and triethylamine is added in the step (3) in the process of carrying out chemical imidization.

In a preferred embodiment of the present invention, the coagulant in the coagulation bath in step (3) comprises an aqueous solution of NMP.

As a preferable technical scheme of the invention, the coagulant further comprises the spinning solvent, and the content of the spinning solvent is 5-15 wt%.

In a preferred embodiment of the present invention, the substituted biphenyldiamine in step (1) has the following structure:

wherein the substituent R₁And a substituent R₂Each independently is a hydrogen atom or an acetamido group; preferably, the substituent R₁And a substituent R₂Is an acetylamino group.

In a preferred embodiment of the present invention, the dibasic acid anhydride in step (2) is one or more selected from the group consisting of biphenyl tetracarboxylic acid dianhydride, pyromellitic acid dianhydride, naphthalene tetracarboxylic acid dianhydride, benzophenone tetracarboxylic acid dianhydride, diphenyl sulfone dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic acid dianhydride, and triphenyldiphenyl ether dianhydride.

As a preferred technical scheme of the invention, the chemical imidization process in the step (3) is carried out for 5-7 hours; preferably, the solution is in a transparent state during the chemical imidization.

Has the advantages that: the scheme adopts tetraaminobiphenyl (4,4 '-diacetamido-3, 3' -diaminobiphenyl) containing two invisible amino groups (acetamido) as a monomer to synthesize a polyimide prepolymer (polyacetylaminoamic acid), the polyimide prepolymer is imidized (at the high temperature of 300-350 ℃) in the air atmosphere to form polyacetylaminoimide (polypyrrolone prepolymer), and then is subjected to high-temperature imidation (at the high temperature of 450-500 ℃) in the air atmosphere to form a high-performance polypyrrolone polymer. Compared with the scheme that 3,3',4, 4' -tetramino biphenyl is directly adopted as a monomer to synthesize polypyrrolone, the scheme has the advantages that: imidization and imidation are carried out at high temperature in an air atmosphere without destroying the chemical structure of the polymer, because the acetamido group is more resistant to high temperature and air oxidation than the amino group. If 3,3',4, 4' -tetraaminobiphenyl is directly used as a monomer to synthesize polyaminoamic acid (polyimide precursor), and is imidized in high-temperature air, amino groups can be oxidized into nitrogen-oxygen compounds, and the nitrogen-oxygen compounds cannot react with carbonyl on an imide ring in the subsequent imidation reaction to form a polypyrrolone structure containing carbon-nitrogen double bonds, so that the polypyrrolone compound cannot be obtained. In addition, the free amino groups in the polyaminoamic acid are so reactive that the prepolymer polymer is not stable enough and is liable to gel, which seriously affects the flowability of the solution and prevents smooth spinning.

Detailed Description

The technical features of the technical solutions provided by the present invention will be further clearly and completely described below with reference to the specific embodiments, and it should be apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The words "preferred", "preferably", "more preferred", and the like, in the present invention, refer to embodiments of the invention that may provide certain benefits, under certain circumstances. However, other embodiments may be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

It should be understood that other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

A first aspect of the present invention provides a high-strength high-modulus polypyrrolone fiber, wherein a polypyrrolone compound of the polypyrrolone fiber has the following structure:

the diameter of the polypyrrolone nanofiber is 8-15 microns, and the diameter of the polypyrrolone nanofiber can be 8-10 microns, 10-12 microns, 12-15 microns, 8 microns, 9 microns, 10 microns, 11 microns, 12 microns, 13 microns, 14 microns and 15 microns.

In some embodiments, the polypyrrolone fiber has a tensile strength of not less than 1.8 GPa; further preferably, the polypyrrolone fiber has a tensile strength of not less than 2.0 Gpa; further preferably, the polypyrrolone fiber has a tensile modulus of not less than 80 Gpa; further preferably, the polypyrrolone fiber has a tensile modulus of not less than 100 Gpa; further preferred polypyrrolone fibers have a glass transition temperature of 350 to 500 ℃. The tensile strength and tensile modulus of the fiber are obtained by adopting a Shanghai Zhongchen superfine fiber monofilament tensile tester JQ03B, and can be tested according to the ISO 11566-.

The second aspect of the present invention provides a method for preparing a high-strength high-modulus polypyrrolone fiber as described above, which comprises the following steps:

(1) preparation of raw material monomers: dissolving acetic anhydride in an organic solvent A to obtain a reaction material A, adding the reaction material A into a solution B of an organic solvent for substituting diphenyldiamine, and reacting at a reaction temperature of not higher than 5 ℃ for 2-6 hours to obtain an intermediate crude product; adding calcium oxide into the intermediate crude product for precipitation, filtering and concentrating to obtain a crude product; then recrystallizing the crude product to obtain the raw material monomer;

(2) synthesis of intermediate polyacetylaminoacid: adding the raw material monomer into a reactor, and carrying out condensation reaction with binary acid anhydride in a spinning solvent to obtain a poly (acetylamino-amide) acid solution;

(3) and (3) wet spinning: chemically imidizing the poly-acetamino-amic acid solution at 40-60 ℃ to obtain a semi-chemically imidized poly-acetamino-amic acid solution, filtering, extruding the solution through a spinneret plate at high pressure, coagulating the solution in a coagulating bath, washing and drying to obtain primary silk;

(4) gathering and umbering: and (3) carrying out thermal imidization and drafting on the primary yarn at 280 ℃, then carrying out heating drafting and polypyrrolization at 450-500 ℃, and carrying out post-treatment to obtain the high-strength high-modulus polypyrrolone fiber.

In some embodiments, the substituted biphenyldiamine of step (1) has the structure:

wherein the substituent R₁And a substituent R₂Each independently is a hydrogen atom or an acetamido group; preferably, the substituent R₁And a substituent R₂Is an acetylamino group. The amino group in the polyacetylaminoimide monomer of the invention may be the same substituent R on any of the 2-position, 3-position or 4-position carbon atoms₁And a substituent R₂Or on any of the carbon atoms in positions 2,3 and 4. Preferably, the substituent R₁And a substituent R₂Each independently a hydrogen atom or an acetamido group. Wherein the substituent R₁And a substituent R₂The substituents may be the same or different.

Further, the substituent R₁And a substituent R₂The same; preferably, the substituent R₁And a substituent R₂Is an acetylamino group; further preferably, the amino group in the polyacetylaminoimide monomer is substituted with the carbon atom at position 3, and the acetamido group is substituted with the carbon atom at position 4, having the chemical name 3,3 '-diamino-4, 4' -diacetylaminobiphenyl, having the structure:

preparation of raw material monomers: in some embodiments, the 3,3' -diamino-4, 4' -diacetoxybiphenyl is obtained by reacting 3,3' -diaminobenzidine with acetic anhydride at low temperature. Because the 3,3 '-diaminobenzidine structure contains four amino groups, and the activity of each amino group is different, the reaction needs to be carried out at low temperature, and the acetic anhydride is ensured to react with the high-activity diamino at the 4.4' -position only to form the 3,3 '-diamino-4, 4' -diacetoxybiphenyl. In some embodiments, the temperature of the reaction is no greater than 5 degrees celsius; preferably, the reaction temperature is not higher than 0 ℃; further, the reaction temperature is-5-0 ℃. In addition, in order to avoid the reaction of acetic anhydride with all amino groups on the 3,3 '-diaminobenzidine and generate unnecessary byproducts, the adding speed of the acetic anhydride is further controlled, and the content of the acetic anhydride in the system is ensured to be kept less than the content of the 3,3' -diaminobenzidine in the reaction process.

In some embodiments, the above reaction is carried out in a liquid phase; preferably, 3 '-diaminobenzidine is dissolved in an organic solvent B to prepare a solution with the weight percent of 10-20%, acetic anhydride is prepared into a solution with the weight percent of 5-15% by adopting the organic solvent A, and the solution of acetic anhydride is added into the solution of 3,3' -diaminobenzidine for reaction. In some preferred embodiments, the dropping speed of the reactant A into the organic solvent B solution of substituted biphenyldiamine is 1-3 mL/min.

In the present invention, the specific types of the organic solvent a and the organic solvent B are not particularly limited, and various organic solvents capable of dissolving acetic anhydride, which are well known to those skilled in the art, may be selected, including but not limited to tetrahydrofuran, ethylene glycol dimethyl ether, methyl carbonate, dimethyl sulfoxide, DMF, DMAc, and the like. In some preferred embodiments, the organic solvent a and the organic solvent B are the same; further preferably, the organic solvent a and the organic solvent B are tetrahydrofuran.

Since acetic acid is produced as a by-product in the above reaction, an appropriate amount of calcium oxide is added to the reaction product to precipitate calcium acetate from acetic anhydride in the system, unreacted acetic anhydride in the system is removed by filtration, and then the filtrate is concentrated by rotary evaporation or the like to remove the solvent therein to obtain a crude product. The amount of the calcium oxide is not particularly limited, and can be determined according to actual conditions, and in some preferred embodiments, the content of the calcium oxide is 0.3-0.8 times of the molar amount of the acetic anhydride; further preferably, the content of the calcium oxide is 0.5 times of the molar amount of the acetic anhydride. In the invention, the coarse product obtained by calcium oxide precipitation and filtration is recrystallized to further purify the coarse product. The recrystallization step is not particularly limited in the present invention, and may be performed according to a manner known to those skilled in the art. In some preferred embodiments, the solvent used for recrystallization is a mixed solvent of ethanol and tetrahydrofuran; preferably, the volume ratio of ethanol to tetrahydrofuran is 1: 1.

The intermediate of the invention, namely the poly-acetamido-amic acid, is prepared by condensing the raw material monomer prepared in the step 1 and dibasic acid anhydride. The specific type of anhydride reacted with the polyamidoamide monomer is not particularly limited in this application, and various types of dibasic anhydrides known to those skilled in the art can be used. The molar ratio of the raw material monomer to the dibasic acid anhydride in the above reaction is 1: (0.8-1.2), preferably the molar ratio is 1: 1. In some embodiments, the condensation reaction temperature is 5 to 15 ℃. Stirring the reaction raw materials under the reaction conditions, wherein the stirring speed is 150-250 r/min, and reacting for 4-9 hours to obtain a viscous intermediate poly (acetamido amic acid) (PAAA) solution with a solid content of 8-20 wt% (preferably 10-20 wt%).

In some embodiments, the dibasic acid anhydride in step (2) is selected from one or more of biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, naphthalene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, diphenyl sulfone dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride, and triphenyldiphenyl ether dianhydride.

The specific type of the spinning solvent used in the condensation reaction in the present invention is not particularly limited, and various solvents known to those skilled in the art may be used, including but not limited to DMF and DMAc.

The intermediate polyacetylaminoacid solution prepared by the above steps of the present invention is further subjected to wet spinning to prepare the fiber of the present invention.

In some embodiments, the desired amounts of acetic anhydride and triethylamine are added during the chemical imidization in step (3). In the present invention, acetic anhydride and triethylamine are added to the intermediate polyaminoamic acid solution, and a partial chemical imidization treatment is performed to form a solvent-soluble polyaminoimide-amic acid solution, and then a solution of the polyaminoimide-amic acid in a spinning solvent (DMAc) is wet-spun.

In some embodiments, the acetic anhydride is added in an amount of 0.5 to 1.0 times the moles of prepolymer (polyamidoamide acid) unit structure (or moles of dianhydride residue) (with the theoretical maximum addition being twice the molar amount of the polyamidoamide acid). Further, the adding molar weight of the triethylamine is 1-1.4 times of that of the acetic anhydride; further, the chemical imidization process is carried out for 5-7 hours; preferably, the solution is in a transparent state during the chemical imidization. The transparent state is judged by a person skilled in the art in a subjective mode, the transparency of the system is adjusted by changing the content of acetic anhydride and triethylamine, and if the content of acetic acid or non-solvents such as acetic anhydride and triethylamine in the system is too high, the solution is subjected to phase separation and becomes turbid, and the spinning result is influenced. And filtering the solution by a 1-3 micron filter screen after partial chemical imidization before extruding the solution into a coagulation bath.

The filtered spinning solution is extruded by a spinneret plate (12K, 24K, 48K and the like) under high pressure and enters a coagulating bath for coagulation, and the formed fiber is washed in a fiber washing pool, dried in a drying chamber at 60-100 ℃ and thermally drawn at 350 ℃ by 300-350 ℃ to form the high-strength and high-temperature-resistant (polyacetylamimide fiber) with the diameter of 10-15 microns.

The spinning solution in the invention forms bidirectional diffusion between the solvent and the coagulant in the coagulation bath under the action of the coagulant, so that the spinning solvent in the spinning solution is diffused into the coagulation bath, the coagulant component in the coagulation bath partially replaces the spinning solvent in the formed fiber, and the spinning solvent is removed in the subsequent washing and drying operations to obtain the final formed fiber.

In some embodiments, the coagulating agent in the coagulating bath in step (3) comprises an aqueous solution of NMP.

Further preferably, the coagulant further comprises the spinning solvent, and the content of the spinning solvent is 5-15 wt%; preferably 15 wt%.

More preferably, the coagulant is composed of 10-20 wt% of a spinning solvent, 8-12 wt% of NMP (N-methylpyrrolidone), 0.05-0.15 wt% of a surfactant and the balance of water.

The specific type of the surfactant is not particularly limited in the present invention, and various surfactants known to those skilled in the art may be selected, including but not limited to nonionic surfactants, anionic surfactants including but not limited to 360 penetrating agents.

In some embodiments, the chemical imidization process of step (3) is performed for 5 to 7 hours; preferably, the solution is in a transparent state during the chemical imidization.

In the invention, imidization (high temperature of 300-330 ℃) in air atmosphere forms polyacetylaminoimide (a polypyrrolone prepolymer), then high-temperature imidation (high temperature of 430-300 ℃) in air atmosphere is carried out, nitrogen elements in acetamido in a polymer structure react with carbonyl in an imide ring under high-temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and a high-performance polypyrrolone polymer is formed; further annealing at 450-500 ℃ for 15-30 minutes.

In the application, tetramino biphenyl (4,4 '-diacetamido-3, 3' -diaminobiphenyl) containing two invisible amino groups (acetamido) is adopted as a monomer to synthesize a polyimide prepolymer (polyacetylaminoamic acid), the polyimide prepolymer is imidized (at the high temperature of 300-330 ℃) in the air atmosphere to form polyacetylaminoimide (polypyrrolone prepolymer), and then is subjected to high-temperature pyrazinization (at the high temperature of 430-300 ℃) in the air atmosphere to form a high-performance polypyrrolone polymer. Compared with the scheme that 3,3',4, 4' -tetramino biphenyl is directly adopted as a monomer to synthesize polypyrrolone, the scheme has the advantages that: imidization and imidation are carried out at high temperature in an air atmosphere without destroying the chemical structure of the polymer, because the acetamido group is more resistant to high temperature and air oxidation than the amino group. If 3,3',4, 4' -tetraaminobiphenyl is directly used as a monomer to synthesize polyaminoamic acid (polyimide precursor), and is imidized in high-temperature air, amino groups can be oxidized into nitrogen-oxygen compounds, and the nitrogen-oxygen compounds cannot react with carbonyl on an imide ring in the subsequent imidation reaction to form a polypyrrolone structure containing carbon-nitrogen double bonds, so that the polypyrrolone compound cannot be obtained. In addition, the free amino groups in the polyaminoamic acid are so reactive that the prepolymer polymer is not stable enough and is liable to gel, which seriously affects the flowability of the solution and prevents smooth spinning.

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

The reaction equation is shown in the following schematic structure:

example 1:

(1) preparation of raw materials: placing 100g (466.7mmol) of 3,3' -diaminobenzidine into a reactor, adding 567 g of THF (tetrahydrofuran) to dissolve the 3,3' -diaminobenzidine to prepare a 15% solution, then dropwise adding 952.9 g (2 x 466.7mmol of acetic anhydride (M-102.09) and 95.29 g) of 10% acetic anhydride THF solution into the 3,3' -diaminobenzidine (M-214.27) THF solution at the speed of 3-5g/min, controlling the reaction temperature to be in the range of-5-0 ℃ for 4 hours, then adding 22.6g (466.7mmol) of dry calcium oxide (M-56.077), reacting with acetic acid to form calcium acetate precipitate, and precipitating from the THF solution; calcium acetate in the system was removed by filtration, and the filtrate was concentrated by rotary evaporation to give 136 g (theoretical yield 139.2 g) of a crude product of 3,3 '-diamino-4, 4' -diacetoxybiphenyl (M ═ 298.27); the crude 3,3 '-diamino-4, 4' -diacetoxybiphenyl product was added with an ethanol/THF solvent in a volume ratio of 1/1, and recrystallization was carried out to obtain 131 g of 3,3 '-diamino-4, 4' -diacetoxybiphenyl product having a purity of 99%, with a final yield of 94%.

(2) Synthesis of intermediate polyacetylaminoacid: the method comprises the steps of carrying out condensation polymerization reaction on 3,3 '-diamino-4, 4' -diacetamido biphenyl and pyromellitic dianhydride monomers serving as raw materials, controlling the molar ratio of diamine to dianhydride to be 1:1 and the solid content of the solution to be 15 wt% by taking DMAc as a solvent, and carrying out condensation polymerization for 8 hours at the temperature of 10-15 ℃ to form a viscous polyacetylamide acid solution.

(3) The chemical imidization is carried out for 6 hours at 50 ℃ by adding acetic anhydride with unit structure molar weight and triethylamine with 1.2 times molar weight into the polyacetylaminoacid, a semi-chemical imidized polyacetylaminoimide-amic acid solution is formed, the solution is extruded into a coagulating bath (10% of NMP, 15% of DMAc, 0.1% of surfactant (360% of penetrating agent) and 75% of deionized water) through a spinneret plate (12K) under high pressure, a silk washing pool (deionized water washing), a drying chamber at 80 ℃, thermal imidization and drafting at 280 ℃ are carried out, heating and drafting are carried out at 480 ℃, nitrogen elements in acetamido react with carbonyl in an imide ring under high-temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and high-performance fibers with polypyrrolone structure are formed.

Example 2:

(1) preparation of raw materials: placing 100g (466.7mmol) of 3,3' -diaminobenzidine into a reactor, adding 567 g of THF (tetrahydrofuran) to dissolve the 3,3' -diaminobenzidine to prepare a 15% solution, then dropwise adding 952.9 g (2 x 466.7mmol of acetic anhydride (M-102.09) and 95.29 g) of 10% acetic anhydride THF solution into the 3,3' -diaminobenzidine (M-214.27) THF solution at the speed of 3-5g/min, controlling the reaction temperature to be in the range of-5-0 ℃ for 4 hours, then adding 22.6g (466.7mmol) of dry calcium oxide (M-56.077), reacting with acetic acid to form calcium acetate precipitate, and precipitating from the THF solution; calcium acetate in the system was removed by filtration, and the filtrate was concentrated by rotary evaporation to give 136 g (theoretical yield 139.2 g) of a crude product of 3,3 '-diamino-4, 4' -diacetoxybiphenyl (M ═ 298.27); the crude 3,3 '-diamino-4, 4' -diacetoxybiphenyl product was added with an ethanol/THF solvent in a volume ratio of 1/1, and recrystallization was carried out to obtain 131 g of 3,3 '-diamino-4, 4' -diacetoxybiphenyl product having a purity of 99%, with a final yield of 94%.

(2) Synthesis of intermediate polyacetylaminoacid: the method comprises the steps of carrying out condensation polymerization reaction on 3,3 '-diamino-4, 4' -diacetamido biphenyl and biphenyl tetracarboxylic dianhydride monomers serving as raw materials, controlling the molar ratio of diamine to dianhydride to be 1:1 and the solid content of the solution to be 15 wt% by taking DMAc as a solvent, and carrying out condensation polymerization for 8 hours at the temperature of 10-15 ℃ to form a viscous polyacetylamide acid solution.

(3) The chemical imidization is carried out for 6 hours at 50 ℃ by adding acetic anhydride with unit structure molar weight and triethylamine with 1.2 times molar weight into the polyacetylaminoacid, a semi-chemical imidized polyacetylaminoimide-amic acid solution is formed, the solution is extruded into a coagulating bath (10% of NMP, 15% of DMAc, 0.1% of surfactant (360% of penetrating agent) and 75% of deionized water) through a spinneret plate (24K) under high pressure, a silk washing pool (deionized water washing), a drying chamber at 80 ℃, thermal imidization and drafting at 280 ℃ are carried out, heating and drafting are carried out at 480 ℃, nitrogen elements in acetamido react with carbonyl in an imide ring under high temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and high-performance fibers with polypyrrolone structure are formed.

Example 3:

(1) preparation of raw materials: placing 100g (466.7mmol) of 3,3' -diaminobenzidine into a reactor, adding 567 g of THF (tetrahydrofuran) to dissolve the 3,3' -diaminobenzidine to prepare a 15% solution, then dropwise adding 952.9 g (2 x 466.7mmol of acetic anhydride (M-102.09) and 95.29 g) of 10% acetic anhydride THF solution into the 3,3' -diaminobenzidine (M-214.27) THF solution at the speed of 3-5g/min, controlling the reaction temperature to be in the range of-5-0 ℃ for 4 hours, then adding 22.6g (466.7mmol) of dry calcium oxide (M-56.077), reacting with acetic acid to form calcium acetate precipitate, and precipitating from the THF solution; calcium acetate in the system was removed by filtration, and the filtrate was concentrated by rotary evaporation to give 136 g (theoretical yield 139.2 g) of a crude product of 3,3 '-diamino-4, 4' -diacetoxybiphenyl (M ═ 298.27); the crude 3,3 '-diamino-4, 4' -diacetoxybiphenyl product was added with an ethanol/THF solvent in a volume ratio of 1/1, and recrystallization was carried out to obtain 131 g of 3,3 '-diamino-4, 4' -diacetoxybiphenyl product having a purity of 99%, with a final yield of 94%.

(2) Synthesis of intermediate polyacetylaminoacid: the method comprises the steps of carrying out condensation polymerization reaction on 3,3 '-diamino-4, 4' -diacetoxybiphenyl and benzophenone tetracarboxylic dianhydride monomers serving as raw materials, controlling the molar ratio of diamine to dianhydride to be 1:1 and the solid content of the solution to be 15 wt% by taking DMAc as a solvent, and carrying out condensation polymerization for 8 hours at the temperature of 10-15 ℃ to form a viscous polyacetylamide acid solution.

(3) The chemical imidization is carried out for 6 hours at 50 ℃ by adding acetic anhydride with unit structure molar weight and triethylamine with 1.2 times molar weight into the polyacetylaminoacid, a semi-chemical imidized polyacetylaminoimide-amic acid solution is formed, the solution is extruded into a coagulating bath (10% of NMP, 15% of DMAc, 0.1% of surfactant (360% of penetrating agent) and 75% of deionized water) through a spinneret plate (48K) under high pressure, a silk washing pool (deionized water washing), a drying chamber at 80 ℃, thermal imidization and drafting at 280 ℃ are carried out, heating and drafting are carried out at 480 ℃, nitrogen elements in acetamido react with carbonyl in an imide ring under high-temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and high-performance fibers with polypyrrolone structure are formed.

Example 4:

(1) preparation of raw materials: placing 100g (466.7mmol) of 3,3' -diaminobenzidine into a reactor, adding 567 g of THF (tetrahydrofuran) to dissolve the 3,3' -diaminobenzidine to prepare a 15% solution, then dropwise adding 952.9 g (2 x 466.7mmol of acetic anhydride (M-102.09) and 95.29 g) of 10% acetic anhydride THF solution into the 3,3' -diaminobenzidine (M-214.27) THF solution at the speed of 3-5g/min, controlling the reaction temperature to be in the range of-5-0 ℃ for 4 hours, then adding 22.6g (466.7mmol) of dry calcium oxide (M-56.077), reacting with acetic acid to form calcium acetate precipitate, and precipitating from the THF solution; calcium acetate in the system was removed by filtration, and the filtrate was concentrated by rotary evaporation to give 136 g (theoretical yield 139.2 g) of a crude product of 3,3 '-diamino-4, 4' -diacetoxybiphenyl (M ═ 298.27); the crude 3,3 '-diamino-4, 4' -diacetoxybiphenyl product was added with an ethanol/THF solvent in a volume ratio of 1/1, and recrystallization was carried out to obtain 131 g of 3,3 '-diamino-4, 4' -diacetoxybiphenyl product having a purity of 99%, with a final yield of 94%.

(2) Synthesis of intermediate polyacetylaminoacid: the preparation method comprises the steps of carrying out condensation polymerization reaction on 3,3 '-diamino-4, 4' -diacetoxybiphenyl and 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride monomers serving as raw materials, controlling the molar ratio of diamine to dianhydride to be 1:1 and the solid content of the solution to be 15 wt.% by taking DMAc as a solvent, and carrying out condensation polymerization for 8 hours at the temperature of 10-15 ℃ to form a viscous polyacetylamide acid solution.

(3) The chemical imidization is carried out for 6 hours at 50 ℃ by adding acetic anhydride with unit structure molar weight and triethylamine with 1.2 times molar weight into the polyacetylaminoacid, a semi-chemical imidized polyacetylaminoimide-amic acid solution is formed, the solution is extruded into a coagulating bath (10% of NMP, 15% of DMAc, 0.1% of surfactant (360% of penetrating agent) and 75% of deionized water) through a spinneret plate (12K) under high pressure, a silk washing pool (deionized water washing), a drying chamber at 80 ℃, thermal imidization and drafting at 280 ℃ are carried out, heating and drafting are carried out at 480 ℃, nitrogen elements in acetamido react with carbonyl in an imide ring under high-temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and high-performance fibers with polypyrrolone structure are formed.

Example 5:

(1) preparation of raw materials: placing 100g (466.7mmol) of 3,3' -diaminobenzidine into a reactor, adding 567 g of THF (tetrahydrofuran) to dissolve the 3,3' -diaminobenzidine to prepare a 15% solution, then dropwise adding 952.9 g (2 x 466.7mmol of acetic anhydride (M-102.09) and 95.29 g) of 10% acetic anhydride THF solution into the 3,3' -diaminobenzidine (M-214.27) THF solution at the speed of 3-5g/min, controlling the reaction temperature to be in the range of-5-0 ℃ for 4 hours, then adding 22.6g (466.7mmol) of dry calcium oxide (M-56.077), reacting with acetic acid to form calcium acetate precipitate, and precipitating from the THF solution; calcium acetate in the system was removed by filtration, and the filtrate was concentrated by rotary evaporation to give 136 g (theoretical yield 139.2 g) of a crude product of 3,3 '-diamino-4, 4' -diacetoxybiphenyl (M ═ 298.27); the crude 3,3 '-diamino-4, 4' -diacetoxybiphenyl product was added with an ethanol/THF solvent in a volume ratio of 1/1, and recrystallization was carried out to obtain 131 g of 3,3 '-diamino-4, 4' -diacetoxybiphenyl product having a purity of 99%, with a final yield of 94%.

(2) Synthesis of intermediate polyacetylaminoacid: the method comprises the steps of carrying out condensation polymerization reaction on 3,3 '-diamino-4, 4' -diacetamido biphenyl and naphthalene tetracarboxylic dianhydride monomers serving as raw materials, controlling the molar ratio of diamine to dianhydride to be 1:1 and the solid content of the solution to be 15 wt% by taking DMAc as a solvent, and carrying out condensation polymerization for 8 hours at the temperature of 10-15 ℃ to form a viscous polyacetylamide acid solution.

(3) The chemical imidization is carried out for 6 hours at 50 ℃ by adding acetic anhydride with unit structure molar weight and triethylamine with 1.2 times molar weight into the polyacetylaminoacid, a semi-chemical imidized polyacetylaminoimide-amic acid solution is formed, the solution is extruded into a coagulating bath (10% of NMP, 15% of DMAc, 0.1% of surfactant (360% of penetrating agent) and 75% of deionized water) through a spinneret plate (12K) under high pressure, a silk washing pool (deionized water washing), a drying chamber at 80 ℃, thermal imidization and drafting at 280 ℃ are carried out, heating and drafting are carried out at 480 ℃, nitrogen elements in acetamido react with carbonyl in an imide ring under high-temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and high-performance fibers with polypyrrolone structure are formed.

Example 6:

(1) preparation of raw materials: placing 100g (466.7mmol) of 3,3' -diaminobenzidine into a reactor, adding 567 g of THF (tetrahydrofuran) to dissolve the 3,3' -diaminobenzidine to prepare a 15% solution, then dropwise adding 952.9 g (2 x 466.7mmol of acetic anhydride (M-102.09) and 95.29 g) of 10% acetic anhydride THF solution into the 3,3' -diaminobenzidine (M-214.27) THF solution at the speed of 3-5g/min, controlling the reaction temperature to be in the range of-5-0 ℃ for 4 hours, then adding 22.6g (466.7mmol) of dry calcium oxide (M-56.077), reacting with acetic acid to form calcium acetate precipitate, and precipitating from the THF solution; calcium acetate in the system was removed by filtration, and the filtrate was concentrated by rotary evaporation to give 136 g (theoretical yield 139.2 g) of a crude product of 3,3 '-diamino-4, 4' -diacetoxybiphenyl (M ═ 298.27); the crude 3,3 '-diamino-4, 4' -diacetoxybiphenyl product was added with an ethanol/THF solvent in a volume ratio of 1/1, and recrystallization was carried out to obtain 131 g of 3,3 '-diamino-4, 4' -diacetoxybiphenyl product having a purity of 99%, with a final yield of 94%.

(2) Synthesis of intermediate polyacetylaminoacid: the method comprises the steps of carrying out condensation polymerization reaction on 3,3 '-diamino-4, 4' -diacetamido biphenyl and triphenyl diphenyl ether dianhydride monomers serving as raw materials, controlling the molar ratio of diamine to dianhydride to be 1:1 and the solid content of the solution to be 15 wt.% by taking DMAc as a solvent, and carrying out condensation polymerization for 8 hours at the temperature of 10-15 ℃ to form a viscous polyacetylamide acid solution.

(3) The chemical imidization is carried out for 6 hours at 50 ℃ by adding acetic anhydride with unit structure molar weight and triethylamine with 1.2 times molar weight into the polyacetylaminoacid, a semi-chemical imidized polyacetylaminoimide-amic acid solution is formed, the solution is extruded into a coagulating bath (10% of NMP, 15% of DMAc, 0.1% of surfactant (360% of penetrating agent) and 75% of deionized water) through a spinneret plate (12K) under high pressure, a silk washing pool (deionized water washing), a drying chamber at 80 ℃, thermal imidization and drafting at 280 ℃ are carried out, heating and drafting are carried out at 480 ℃, nitrogen elements in acetamido react with carbonyl in an imide ring under high-temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and high-performance fibers with polypyrrolone structure are formed.

Example 7:

(1) preparation of raw materials: placing 100g (466.7mmol) of 3,3' -diaminobenzidine into a reactor, adding 567 g of THF (tetrahydrofuran) to dissolve the 3,3' -diaminobenzidine to prepare a 15% solution, then dropwise adding 952.9 g (2 x 466.7mmol of acetic anhydride (M-102.09) and 95.29 g) of 10% acetic anhydride THF solution into the 3,3' -diaminobenzidine (M-214.27) THF solution at the speed of 3-5g/min, controlling the reaction temperature to be in the range of-5-0 ℃ for 4 hours, then adding 22.6g (466.7mmol) of dry calcium oxide (M-56.077), reacting with acetic acid to form calcium acetate precipitate, and precipitating from the THF solution; calcium acetate in the system was removed by filtration, and the filtrate was concentrated by rotary evaporation to give 136 g (theoretical yield 139.2 g) of a crude product of 3,3 '-diamino-4, 4' -diacetoxybiphenyl (M ═ 298.27); the crude 3,3 '-diamino-4, 4' -diacetoxybiphenyl product was added with an ethanol/THF solvent in a volume ratio of 1/1, and recrystallization was carried out to obtain 131 g of 3,3 '-diamino-4, 4' -diacetoxybiphenyl product having a purity of 99%, with a final yield of 94%.

(2) Synthesis of intermediate polyacetylaminoacid: the method comprises the steps of carrying out condensation polymerization reaction on 3,3 '-diamino-4, 4' -diacetamido biphenyl and diphenyl sulfone dianhydride monomers serving as raw materials, controlling the molar ratio of diamine to dianhydride to be 1:1 and the solid content of the solution to be 15 wt.% by taking DMAc as a solvent, and carrying out condensation polymerization for 8 hours at the temperature of 10-15 ℃ to form a viscous polyacetylamide acid solution.

(3) The chemical imidization is carried out for 6 hours at 50 ℃ by adding acetic anhydride with unit structure molar weight and triethylamine with 1.2 times molar weight into the polyacetylaminoacid, a semi-chemical imidized polyacetylaminoimide-amic acid solution is formed, the solution is extruded into a coagulating bath (10% of NMP, 15% of DMAc, 0.1% of surfactant (360% of penetrating agent) and 75% of deionized water) through a spinneret plate (12K) under high pressure, a silk washing pool (deionized water washing), a drying chamber at 80 ℃, thermal imidization and drafting at 280 ℃ are carried out, heating and drafting are carried out at 480 ℃, nitrogen elements in acetamido react with carbonyl in an imide ring under high-temperature tension to form carbon-nitrogen double bonds, acetic acid molecules are removed, and high-performance fibers with polypyrrolone structure are formed.

Performance testing

The applicant carried out tests on the fiber diameter, the mechanical strength and the like of the experimental samples in the above examples, specifically as follows:

1. fiber diameter testing: the average diameter of randomly intercepted fibers (μm) in the various groups of samples was measured mainly under a microscope.

2. Glass transition temperature test: the samples of the above examples were tested for their glass transition temperature T by DMA_g。

3. And (3) testing the decomposition temperature: the samples of the above examples were tested by TGA for their thermal decomposition temperatures, which is the temperature T at which the thermal weight loss reaches 5 wt%_d/_5％。

4. Tensile strength: the tensile strength of the fiber is tested by adopting a Shanghai Zhongchen superfine fiber monofilament tensile tester JQ03B to obtain parameters such as tensile strength (GPa), modulus (GPa) and elongation (%).

The results of the above performance tests are shown in table 1 below.

TABLE 1

	Diameter of fiber	Tg/℃	Td/℃	Tensile strength	Elongation percentage	Modulus of elasticity
							Example 1	12-15	/	700-720	2.0-2.4	2.0-4.0	220-250
Example 2	10-12	480-500	715-735	2.5-30	4.0-6.0	150-180
							Example 3	10-12	400-430	680-700	1.8-2.2	4.0-6.0	110-150
Example 4	8-10	380-400	660-680	2.0-2.5	6.0-8.0	100-130
							Example 5	12-15	/	730-750	3.0-3.5	3.0-5.0	250-280
Example 6	8-10	350-370	630-650	2.1-2.7	8.0-10.0	80-100
							Example 7	10-12	410-430	650-670	1.8-2.4	4.0-6.0	160-180

Comparative example

14.8615 g (69.36mmol) of 3,3 '-diaminobenzidine is placed in a reactor, 180 g of DMAc is added to dissolve the 3,3' -diaminobenzidine to prepare a solution with the concentration of 7.5 percent, the reactor is placed in a cold bath, the temperature of a reaction system is controlled between minus 5 ℃ and 0 ℃, 15.1385g (69.36mmol) of pyromellitic dianhydride (PMDA) powder is added into the reaction system, and the reaction is carried out for 4 hours under mechanical stirring to form a 15 percent DMAc solution of polyaminoamic acid. 14.1622g (138.72mmol) of acetic anhydride was added to the solution, and after stirring for 4 hours, the temperature of the solution was raised to 50 ℃ and 7.0811g (69.36mmol) of acetic anhydride and 8.4219g (83.23mmol) of triethylamine were added thereto, and the reaction was stirred for 6 hours, whereby the solution was partially gelled, had a certain fluidity, but had no or low viscosity. When the solution is filtered by a 2 micron filter screen, the gel-like semisolid fluid with certain fluidity and low viscosity can hardly permeate the 2 micron filter screen, and clean high-viscosity spinning fluid with fluidity required for spinning of a wet spinneret plate can not be obtained by a filtering method. The reason for the failure is that the acetic anhydride used to react with the free amino groups of the polyaminoamic acid does not react completely and may participate in the subsequent imidization reaction, increasing the imidization level to more than 50%, resulting in a polymer that is poorly soluble; on the other hand, unreacted free amino groups may participate in the exchange reaction with amide groups on adjacent polymer molecules, resulting in the formation of a partially crosslinked structure, so that the solution of the polyacetylaminoimide or amic acid is gelled or partially gelled, resulting in clogging of the filter screen and failure to filter.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in other forms, and any person skilled in the art may modify or change the technical content disclosed above into an equivalent embodiment with equivalent changes, but all those simple modifications, equivalent changes and modifications made on the above embodiment according to the technical spirit of the present invention still belong to the protection scope of the present invention.