A method for preparing polyimide fibers of different colors based on in-situ coloring

Abstract

The present invention relates to the technical field of polyimide fibers, and more particularly to a method for preparing polyimide fibers of different colors based on in-situ coloring. The method comprises subjecting a perylene tetracarboxylic dianhydride compound or perylene diimide to a condensation reaction with a diamine monomer and a dianhydride monomer to obtain a polyamic acid solution; adding acetic anhydride and pyridine to the polyamic acid solution to carry out a chemical ring closure reaction to obtain a polyimide solution; and wet spinning the obtained polyimide solution to produce colored polyimide fibers. The present invention utilizes the above-mentioned method for preparing polyimide fibers of different colors based on in-situ coloring, which is simple and environmentally friendly. The obtained polyimide fibers of different colors have high color fastness and excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polyimide fibers, in particular to a method for preparing polyimide fibers of different colors based on in-situ coloring. Background Art

[0002] Polyimide fiber is a type of high-performance fiber material with imide rings as its main structural feature. It has excellent mechanical properties, excellent thermal stability, chemical corrosion resistance, and flame retardancy, and is widely used in high-temperature protection, aerospace, electronic communications and other fields. However, its excellent properties bring challenges to the dyeing and finishing of polyimide fibers. The main reasons include: (1) the polyimide molecular chain lacks polar groups, the fiber surface is passivated, and conventional dyes are difficult to bind through chemical bonds or physical adsorption; (2) the fiber molecular chain contains a large number of aromatic rings and imide rings, forming a strong conjugated structure, which makes the fiber dark yellow to golden yellow. The base color is difficult to cover during dyeing, making it difficult to control the target color; (3) the high temperature and strong acid and alkali conditions required by traditional dyeing processes can easily destroy the molecular structure of polyimide, affecting the fiber performance.

[0003] With the continuous deepening of polyimide fiber research and the maturity of production technology, the market demand for colored polyimide fibers is also increasing. Currently, the main methods for dyeing polyimide fibers include solution dyeing, fiber surface modification, supercritical carbon dioxide dyeing, and carrier dyeing. However, the existing dyeing methods produce relatively monotonous colored yarns and may adversely affect fiber properties. Therefore, a new polyimide fiber dyeing method is urgently needed. Summary of the Invention

[0004] The present invention aims to provide a method for preparing polyimide fibers of different colors based on in-situ coloring. The process is simple and environmentally friendly. The prepared polyimide fibers of different colors have high color fastness and excellent mechanical properties.

[0005] To achieve the above object, the present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0006] S1. Polycondensing a perylenetetracarboxylic dianhydride compound or perylene diimide with a diamine monomer and a dianhydride monomer at -5-5°C for 4-6 hours to obtain a polyamic acid solution; the molar ratio of perylenetetracarboxylic dianhydride or perylene diimide to the diamine monomer and the dianhydride monomer is (0.01-1):(0.01-1):(0.01-1.3);

[0007] S2. Add acetic anhydride and pyridine to the polyamic acid solution of S1 to carry out a chemical ring-closure reaction, and stir the reaction at 25-35° C. for 8-16 hours to obtain a polyimide solution; the volume ratio of acetic anhydride and pyridine to the polyamic acid solution is (1-5): (1-5): 20;

[0008] S3. The polyimide solution obtained in S2 is wet-spinned to prepare polyimide fibers of different colors.

[0009] Preferably, the perylene diimide in S1 is prepared by the following steps:

[0010] S1.1. Mix a perylene tetracarboxylic dianhydride compound with zinc acetate, imidazole, and a diamine compound, and react with stirring at 120-160°C for 5-7 hours to obtain an intermediate product; the molar ratio of the perylene tetracarboxylic dianhydride compound to the diamine compound and zinc acetate is 1:(1-10):(0.5-1), and the mass ratio of the perylene tetracarboxylic dianhydride compound to the imidazole is 1:(4-20);

[0011] S1.2. The intermediate product of S1.1 is cooled and dissolved in tetrahydrofuran, then transferred to a hydrochloric acid-methanol mixed solution for precipitation. The precipitate is collected by filtration, washed with water and methanol, and then vacuum-dried to obtain a powdery product, i.e., perylene diimide.

[0012] Preferably, the perylene tetracarboxylic dianhydride compounds in S1 and S1.1 include one of 3,4,9,10-perylene tetracarboxylic dianhydride, tetrachloroperylene anhydride, 1,6,7,12-tetrabromoperylene anhydride, 1-bromoperylene-3,4,9,10-tetracarboxylic dianhydride, 1,2,5,6,7,8,11,12-octabromoperylene anhydride, perylenedipyran-1,3,8,10-tetrahydronaphthalene, 5,6-dibromo, and 1,7-dibromo-3,4,9,10-perylene tetracarboxylic dianhydride.

[0013] Preferably, in S1.1, the diamine compound includes one of ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-diaminopentane, 1,6-hexanediamine, 1,7-diaminoheptane, 1,8-octanediamine, 1,9-nonanediamine, decanediamine, 1,11-undecanamine, 1,12-diaminododecane, p-phenylenediamine, and benzidine.

[0014] Preferably, in S1, the diamine monomer includes one of 2,2'-bis(trifluoromethyl)diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,4,6-trimethyl-1,3-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, 2,2'-bis(trifluoromethyl)-4,4'-diaminophenyl ether, 1,3-bis(4-aminophenoxy)benzene, 2-(4-aminophenyl)-5-aminobenzimidazole, 2-(4-aminophenyl)-5-aminobenzoxazole, 3,3'-dihydroxybenzidine, and 4,4'-bis(3-aminophenoxy)biphenyl.

[0015] Preferably, in S1, the dianhydride monomer includes one of 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 1,3-dimethyl-cyclobutanetetracarboxylic dianhydride, hexafluoro dianhydride, 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 4,4'-biphenyl ether dianhydride, bisphenol A type diether dianhydride, 3,3,4,4-diphenyl sulfone tetracarboxylic dianhydride, and 1,4,5,8-naphthalenetetracarboxylic anhydride.

[0016] Preferably, in S3, the coagulation bath in the wet spinning process consists of N-methylpyrrolidone and deionized water in a volume ratio of 2-8:2-8.

[0017] Mechanism of the present invention:

[0018] The amino group (nucleophile) in the diamine monomer or the introduced perylene diimide attacks the carbonyl carbon of the dianhydride monomer or the introduced perylene tetracarboxylic anhydride, forming an unstable tetrahedral intermediate. The dianhydride group in the tetrahedral intermediate then undergoes ring opening, cleaving the CO bond and generating a carboxylate anion and an amide bond. The carboxylate anion then undergoes proton transfer to form a carboxyl group. The perylene diimide or perylene tetracarboxylic anhydride then embeds into the polymer chain via the amide bond and is stabilized by proton transfer, ultimately forming a linear polyamic acid (PAA) chain. At this point, the perylene structure acts as a chromophore and is covalently anchored to the polymer backbone. This reaction must be carried out at low temperatures (-5–5°C) in a polar aprotic solvent (such as NMP or DMF) to suppress the side reaction of dehydration ring closure of the polyamic acid to form polyimide. The resulting polyamic acid is a key precursor for the synthesis of high-performance polyimides. Therefore, the entire process is essentially a nucleophilic addition of the amino group to the anhydride, initiating ring opening and ultimately forming a linear polymer with both amide and carboxyl groups.

[0019] Finally, under the action of acetic anhydride and pyridine, the carboxylic acid group (-COOH) and the amide group (-NH-CO-) in the polyamic acid molecule undergo a dehydration ring-closure reaction to form polyimide.

[0020] Beneficial effects of the present invention:

[0021] (1) The present invention adopts the above-mentioned method for preparing polyimide fibers of different colors based on in-situ coloring. Through in-situ coloring, only a small amount of molecules need to be linked to the polymer molecules to achieve dyeing, without adding any auxiliaries. Compared with the dyeing process, it has the advantages of simple process, low production cost and less impact on the environment;

[0022] (2) The present invention adopts the above-mentioned method for preparing polyimide fibers of different colors based on in-situ coloring. The condensed aromatic hydrocarbon structure of the perylene compound forms a strong interaction with the polyimide molecular chain, synergizing its excellent dyeability to achieve stable anchoring of the dye, thereby effectively inhibiting the migration and shedding of the dye during the dyeing process, and making it have higher color fastness;

[0023] (3) The present invention adopts the above-mentioned method for preparing polyimide fibers of different colors based on in-situ coloring. The rigid molecular skeleton of the perylene compound can effectively enhance the interaction between polymer chains and simultaneously improve the mechanical properties of the polyimide fiber.

[0024] The technical solution of the present invention is further described in detail below through examples. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the following embodiments. Unless otherwise defined, technical or scientific terms used herein shall have the same meanings as those commonly understood by persons of ordinary skill in the art to which the present invention pertains. The above-mentioned features or features described in the specific examples of the present invention may be combined in any manner. These specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention.

[0026] Example 1

[0027] The present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0028] S1. Add 1.0 mmol of 3,4,9,10-perylenetetracarboxylic dianhydride, 1 mmol of ethylenediamine, and 0.5 mmol of zinc acetate to 1.6 g of imidazole solution, stir and dissolve evenly, and react at 120°C for 7 h to obtain an intermediate product; cool the intermediate product and dissolve it in 100 mL of tetrahydrofuran, then transfer it to a hydrochloric acid-methanol mixed solution (the concentration of hydrochloric acid is 2 mol / L) for precipitation, collect the precipitate by filtration, wash it with water and methanol, and dry it in a vacuum oven at 80°C to obtain a powdery product, i.e., perylene diimide.

[0029] S2. Add the perylene diimide and 2,2'-bis(trifluoromethyl)diaminobiphenyl obtained in S1 to 20 mL of N,N-dimethylacetamide (DMAc) solvent, stir and dissolve uniformly, add 4,4'-(hexafluoroisopropylene)diphthalic anhydride at -5°C, and react for 4 hours to obtain a polyamic acid solution. The molar ratio of perylene diimide to 2,2'-bis(trifluoromethyl)diaminobiphenyl to 4,4'-(hexafluoroisopropylene)diphthalic anhydride is 1:0.01:1.

[0030] S3. 1 mL of acetic anhydride solution and 1 mL of pyridine solution were respectively added to the polyamic acid solution in S2 to carry out a chemical ring-closure reaction, and the mixture was stirred at 25° C. for 8 h to obtain a polyimide solution.

[0031] S4. The polyimide solution obtained in S3 is deaerated and filtered, and then pumped into a coagulation bath through a spinneret by a syringe pump. After washing and drawing, purple-red polyimide fibers are obtained. The coagulation bath consists of N-methylpyrrolidone and deionized water in a volume ratio of 2:8.

[0032] The obtained purple-red polyimide colored yarn.

[0033] Example 2

[0034] The present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0035] S1. Add 1.0 mmol of 3,4,9,10-perylenetetracarboxylic dianhydride, 5 mmol of ethylenediamine, and 0.75 mmol of zinc acetate to 4.8 g of imidazole solution, stir and dissolve evenly, and react at 140°C for 6 h to obtain an intermediate product; cool the intermediate product and dissolve it in 100 mL of tetrahydrofuran, then transfer it to a hydrochloric acid-methanol mixed solution (the concentration of hydrochloric acid is 2 mol / L) for precipitation, collect the precipitate by filtration, wash it with water and methanol, and dry it in a vacuum oven at 80°C to obtain a powdery product, i.e., perylene diimide.

[0036] S2. Add the perylene diimide and 2,2'-bis(trifluoromethyl)diaminobiphenyl obtained in S1 to 20 mL of N,N-dimethylacetamide (DMAc) solvent, stir and dissolve uniformly, add 4,4'-(hexafluoroisopropylene)diphthalic anhydride at 0°C, and react for 5 hours to obtain a polyamic acid solution. The molar ratio of perylene diimide to 2,2'-bis(trifluoromethyl)diaminobiphenyl to 4,4'-(hexafluoroisopropylene)diphthalic anhydride is 0.5:0.5:1.

[0037] S3. 3 mL of acetic anhydride solution and 3 mL of pyridine solution were respectively added to the polyamic acid solution in S2 to carry out a chemical ring-closure reaction, and the mixture was stirred at 30° C. for 12 h to obtain a polyimide solution.

[0038] S4. The polyimide solution obtained in S3 is deaerated and filtered, and then pumped into a coagulation bath through a spinneret by a syringe pump. After washing and drawing, purple-red polyimide fibers are obtained. The coagulation bath consists of N-methylpyrrolidone and deionized water in a volume ratio of 2:8.

[0039] The obtained purple-red polyimide colored yarn.

[0040] Example 3

[0041] The present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0042] S1. Add 1.0 mmol of 3,4,9,10-perylenetetracarboxylic dianhydride, 10 mmol of ethylenediamine, and 1.0 mmol of zinc acetate to 8 g of imidazole solution, stir and dissolve evenly, and react at 160°C for 5 h to obtain an intermediate product; cool the intermediate product and dissolve it in 100 mL of tetrahydrofuran, then transfer it to a hydrochloric acid-methanol mixed solution (the concentration of hydrochloric acid is 2 mol / L) for precipitation, collect the precipitate by filtration, wash it with water and methanol, and dry it in a vacuum oven at 80°C to obtain a powdery product, i.e., perylene diimide.

[0043] S2. Add the perylene diimide and 2,2'-bis(trifluoromethyl)diaminobiphenyl obtained in S1 to 20 mL of N,N-dimethylacetamide (DMAc) solvent, stir and dissolve uniformly, add 4,4'-(hexafluoroisopropylene)diphthalic anhydride at 5°C, and react for 6 hours to obtain a polyamic acid solution. The molar ratio of perylene diimide to 2,2'-bis(trifluoromethyl)diaminobiphenyl to 4,4'-(hexafluoroisopropylene)diphthalic anhydride is 0.01:1:1.3.

[0044] S3. 5 mL of acetic anhydride solution and 5 mL of pyridine solution were respectively added to the polyamic acid solution in S2 to carry out a chemical ring-closure reaction, and the mixture was stirred at 35° C. for 16 h to obtain a polyimide solution.

[0045] S4. The polyimide solution obtained in S3 is deaerated and filtered, and then pumped into a coagulation bath through a spinneret by a syringe pump. After washing and drawing, purple-red polyimide fibers are obtained. The coagulation bath consists of N-methylpyrrolidone and deionized water in a volume ratio of 2:8.

[0046] The obtained purple-red polyimide colored yarn.

[0047] Example 4

[0048] The present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0049] S1. Add 1.0 mmol of 3,4,9,10-perylenetetracarboxylic dianhydride, 3 mmol of ethylenediamine, and 0.75 mmol of zinc acetate to 4 g of imidazole solution, stir and dissolve evenly, and react at 120°C for 6 h to obtain an intermediate product; cool the intermediate product and dissolve it in 100 mL of tetrahydrofuran, then transfer it to a hydrochloric acid-methanol mixed solution (the concentration of hydrochloric acid is 2 mol / L) for precipitation, collect the precipitate by filtration, wash it with water and methanol, and dry it in a vacuum oven at 80°C to obtain a powdery product, i.e., perylene diimide.

[0050] S2. Add the perylene diimide and 2,2'-bis(trifluoromethyl)diaminobiphenyl obtained in S1 to 20 mL of N,N-dimethylacetamide (DMAc) solvent, stir and dissolve uniformly, add 4,4'-(hexafluoroisopropylene)diphthalic anhydride at 0°C, and react for 5 hours to obtain a polyamic acid solution. The molar ratio of perylene diimide to 2,2'-bis(trifluoromethyl)diaminobiphenyl to 4,4'-(hexafluoroisopropylene)diphthalic anhydride is 0.1:1:1.2.

[0051] S3. 1 mL of acetic anhydride solution and 1 mL of pyridine solution were respectively added to the polyamic acid solution in S2 to carry out a chemical ring-closure reaction, and the mixture was stirred at 30° C. for 12 h to obtain a polyimide solution.

[0052] S4. The polyimide solution obtained in S3 is deaerated and filtered, and then pumped into a coagulation bath through a spinneret by a syringe pump. After washing and drawing, purple-red polyimide fibers are obtained. The coagulation bath consists of N-methylpyrrolidone and deionized water in a volume ratio of 2:8.

[0053] The obtained purple-red polyimide colored yarn has the following physical and mechanical properties: strength 35.958 MPa, elongation 21.804%.

[0054] Example 5

[0055] The present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0056] S1. Add 1 mmol of tetrachloroperylene anhydride, 3 mmol of 1,6-hexanediamine and 0.5 mmol of zinc acetate to 5 g of imidazole solution, stir and dissolve evenly, and react at 160°C for 5 hours to obtain an intermediate product; cool the intermediate product and dissolve it in 100 mL of hydrofuran, then transfer it to a hydrochloric acid-methanol mixed solution (the concentration of hydrochloric acid is 2 mol / L) for precipitation, collect the precipitate by filtration, wash it with water and methanol, and dry it in a vacuum oven at 80°C to obtain a powdery product, i.e., perylene diimide.

[0057] S2. Add the perylene diimide and 2,2'-bis(trifluoromethyl)diaminobiphenyl obtained in S1 to 20 mL of N,N-dimethylacetamide (DMAc) solvent, stir and dissolve uniformly, add 4,4'-(hexafluoroisopropylene)diphthalic anhydride at 0°C, and react for 5 hours to obtain a polyamic acid solution. The molar ratio of perylene diimide to 2,2'-bis(trifluoromethyl)diaminobiphenyl to 4,4'-(hexafluoroisopropylene)diphthalic anhydride is 0.5:0.5:1.03.

[0058] S3. Add 1 mL of acetic anhydride solution and 1 mL of pyridine solution to the polyamic acid solution in S2 to carry out a chemical ring-closure reaction, and stir at room temperature for 12 hours to obtain a polyimide solution.

[0059] S4. The polyimide solution obtained in S3 is deaerated and filtered, and then pumped into a coagulation bath through a spinneret by a syringe pump. After washing and drawing, purple polyimide fibers are obtained. The coagulation bath consists of N-methylpyrrolidone and deionized water in a volume ratio of 8:2.

[0060] The physical and mechanical properties of the obtained purple polyimide colored yarn are as follows: strength 29.0672 MPa, elongation 57.414%.

[0061] Example 6

[0062] The present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0063] S1. Add 2,2'-bis(trifluoromethyl)diaminobiphenyl to 20 mL of N,N-dimethylacetamide (DMAc) solvent and stir to dissolve evenly. Then add 4,4'-(hexafluoroisopropylene)diphthalic anhydride and 3,4,9,10-perylenetetracarboxylic dianhydride at 0°C and react for 5 hours to obtain a polyamic acid solution. The molar ratio of 3,4,9,10-perylenetetracarboxylic dianhydride to 2,2'-bis(trifluoromethyl)diaminobiphenyl and 4,4'-(hexafluoroisopropylene)diphthalic anhydride is 0.05:1:1.

[0064] S2. Add 2 mL of acetic anhydride and 2 mL of pyridine to the polyamic acid solution of S1 to carry out a chemical ring-closure reaction, and stir at 30° C. for 12 h to obtain a polyimide solution.

[0065] S3. After degassing and filtering the polyimide solution obtained in S2, the solution is pumped into a coagulation bath through a spinneret by a syringe pump. After washing and drawing, rose-red polyimide fibers are obtained. The coagulation bath consists of N-methylpyrrolidone and deionized water in a volume ratio of 2:8.

[0066] The obtained rose-red polyimide colored yarn has the following physical and mechanical properties: strength 42.4047 MPa, elongation 100.829%; color fastness: friction color fastness 3 / 4-5 (dry rubbing / wet rubbing) level.

[0067] Example 7

[0068] The present invention provides a method for preparing polyimide fibers of different colors based on in-situ coloring, comprising the following steps:

[0069] S1. Add 2,2'-bis(trifluoromethyl)diaminobiphenyl to 19 mL of N,N-dimethylacetamide (DMAc) solvent and stir to dissolve. Then add 4,4'-(hexafluoroisopropylene)diphthalic anhydride and tetrachloroperylene anhydride at 0°C and react for 5 hours to obtain a polyamic acid solution. The molar ratio of tetrachloroperylene anhydride to 2,2'-bis(trifluoromethyl)diaminobiphenyl and 4,4'-(hexafluoroisopropylene)diphthalic anhydride is 0.01:1:1.

[0070] S2. Add 1 mL of acetic anhydride and 1 mL of pyridine to the polyamic acid solution of S1 to carry out a chemical ring-closure reaction, and stir at 25° C. for 12 h to obtain a polyimide solution.

[0071] S3. The polyimide solution obtained in S2 is deaerated and filtered, and then pumped into a coagulation bath through a spinneret by a syringe pump. After washing and drawing, orange polyimide fibers are obtained. The coagulation bath consists of N-methylpyrrolidone and deionized water in a volume ratio of 2:8.

[0072] The obtained orange polyimide colored yarn has the following physical and mechanical properties: strength 41.4967 MPa, elongation 37.382%; color fastness: color fastness to friction 3-4 / 4-5 (dry friction / wet friction) level.

[0073] Example 8

[0074] Taking Example 1 as a benchmark, the difference from Example 1 is that the 3,4,9,10-perylenetetracarboxylic dianhydride in S1 is replaced with tetrachloroperylene anhydride to prepare a black-purple polyimide fiber.

[0075] Example 9

[0076] Taking Example 1 as a benchmark, the difference from Example 1 is that 3,4,9,10-perylenetetracarboxylic dianhydride in S1 is replaced with 1,6,7,12-tetrabromoperylene anhydride to prepare colored polyimide fibers.

[0077] Example 10

[0078] Taking Example 1 as a benchmark, the difference from Example 1 is that 3,4,9,10-perylenetetracarboxylic dianhydride in S1 is replaced by 1-bromoperylene-3,4,9,10-tetracarboxylic dianhydride to prepare colored polyimide fibers.

[0079] Example 11

[0080] Taking Example 1 as a benchmark, the difference from Example 1 is that 3,4,9,10-perylenetetracarboxylic dianhydride in S1 is replaced with 1,2,5,6,7,8,11,12-octabromoperylene anhydride to prepare colored polyimide fibers.

[0081] Example 12

[0082] Taking Example 1 as a benchmark, the difference from Example 1 is that the 3,4,9,10-perylenetetracarboxylic dianhydride in S1 is replaced with perylenedipyran-1,3,8,10-tetrahydronaphthalene, 5,6-dibromide to prepare colored polyimide fibers.

[0083] Example 13

[0084] Taking Example 1 as a benchmark, the difference from Example 1 is that the 3,4,9,10-perylenetetracarboxylic dianhydride in S1 is replaced with 1,7-dibromo-3,4,9,10-perylenetetracarboxylic dianhydride to prepare colored polyimide fibers.

[0085] Example 14

[0086] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with 1,3-propylenediamine to prepare colored polyimide fibers.

[0087] Example 15

[0088] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with 1,4-butanediamine to obtain colored polyimide fibers.

[0089] Example 16

[0090] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with 1,5-diaminopentane to obtain colored polyimide fibers.

[0091] Example 17

[0092] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with 1,6-hexamethylenediamine to obtain pink polyimide fiber.

[0093] Example 18

[0094] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced by 1,7-diaminoheptane to obtain colored polyimide fibers.

[0095] Example 19

[0096] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with 1,8-octanediamine to prepare colored polyimide fibers.

[0097] Example 20

[0098] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with 1,9-nonanediamine to prepare colored polyimide fibers.

[0099] Example 21

[0100] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with decanediamine to obtain colored polyimide fibers.

[0101] Example 22

[0102] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced by 1,11-undecanamine to obtain colored polyimide fibers.

[0103] Example 23

[0104] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced with 1,12-diaminododecane to obtain colored polyimide fibers.

[0105] Example 24

[0106] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced by p-phenylenediamine to obtain colored polyimide fibers.

[0107] Example 25

[0108] Taking Example 1 as a benchmark, the difference from Example 1 is that the ethylenediamine in S1 is replaced by benzidine to obtain colored polyimide fibers.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing polyimide fibers of different colors based on in-situ coloring, characterized in that: The following steps are involved: S1. Polycondensing a perylenetetracarboxylic dianhydride compound or perylene diimide with a diamine monomer and a dianhydride monomer at -5-5°C for 4-6 hours to obtain a polyamic acid solution; the molar ratio of perylenetetracarboxylic dianhydride or perylene diimide to the diamine monomer and the dianhydride monomer is (0.01-1):(0.01-1):(0.01-1.3); Perylene diimide is prepared from perylene tetracarboxylic dianhydride compounds, and the perylene tetracarboxylic dianhydride compounds include one of 3,4,9,10-perylene tetracarboxylic dianhydride, tetrachloroperylene anhydride, 1,6,7,12-tetrabromoperylene anhydride, 1-bromoperylene-3,4,9,10-tetracarboxylic dianhydride, 1,2,5,6,7,8,11,12-octabromoperylene anhydride, perylenedipyran-1,3,8,10-tetrahydronaphthalene, 5,6-dibromo, and 1,7-dibromo-3,4,9,10-perylene tetracarboxylic dianhydride; S2. Add acetic anhydride and pyridine to the polyamic acid solution of S1 to carry out a chemical ring-closure reaction, and stir the reaction at 25-35° C. for 8-16 hours to obtain a polyimide solution; the volume ratio of acetic anhydride and pyridine to the polyamic acid solution is (1-5): (1-5): 20; S3. The polyimide solution obtained in S2 is wet-spinned to prepare polyimide fibers of different colors.

2. The method for preparing polyimide fibers of different colors based on in-situ coloring according to claim 1, characterized in that: The perylene diimide in S1 is prepared by the following steps: S1.

1. Mix a perylene tetracarboxylic dianhydride compound with zinc acetate, imidazole, and a diamine compound, and react with stirring at 120-160°C for 5-7 hours to obtain an intermediate product; the molar ratio of the perylene tetracarboxylic dianhydride compound to the diamine compound and zinc acetate is 1:(1-10):(0.5-1), and the mass ratio of the perylene tetracarboxylic dianhydride compound to the imidazole is 1:(4-20); S1.

2. The intermediate product of S1.1 is cooled and dissolved in tetrahydrofuran, then transferred to a hydrochloric acid-methanol mixed solution for precipitation. The precipitate is collected by filtration, washed with water and methanol, and then vacuum-dried to obtain a powdery product, i.e., perylene diimide.

3. The method for preparing polyimide fibers of different colors based on in-situ coloring according to claim 2, characterized in that: In S1.1, the diamine compound includes one of ethylenediamine, 1,3-propylenediamine, 1,4-butanediamine, 1,5-diaminopentane, 1,6-hexanediamine, 1,7-diaminoheptane, 1,8-octanediamine, 1,9-nonanediamine, decanediamine, 1,11-undecanamine, 1,12-diaminododecane, p-phenylenediamine, and benzidine.

4. The method for preparing polyimide fibers of different colors based on in-situ coloring according to claim 1, characterized in that: In S1, the diamine monomer includes one of 2,2'-bis(trifluoromethyl)diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,4,6-trimethyl-1,3-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, 2,2'-bis(trifluoromethyl)-4,4'-diaminophenyl ether, 1,3-bis(4-aminophenoxy)benzene, 2-(4-aminophenyl)-5-aminobenzimidazole, 2-(4-aminophenyl)-5-aminobenzoxazole, 3,3'-dihydroxybenzidine, and 4,4'-bis(3-aminophenoxy)biphenyl.

5. The method for preparing polyimide fibers of different colors based on in-situ coloring according to claim 1, characterized in that: In S1, the dianhydride monomer includes one of 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 1,3-dimethyl-cyclobutanetetracarboxylic dianhydride, hexafluoro dianhydride, 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 4,4'-biphenyl ether dianhydride, bisphenol A type diether dianhydride, 3,3,4,4-diphenyl sulfone tetracarboxylic dianhydride, and 1,4,5,8-naphthalenetetracarboxylic anhydride.

6. The method for preparing polyimide fibers of different colors based on in-situ coloring according to claim 1, characterized in that: In S3, the coagulation bath in the wet spinning process consists of N-methylpyrrolidone and deionized water in a volume ratio of 2-8:2-8.