Preparation method of alkali-resistant polyimide fiber and alkali-resistant polyimide fiber

Abstract

The object of the present invention is to provide a method for preparing an alkali-resistant polyimide fiber and the alkali-resistant polyimide fiber, and the steps thereof include: (1) providing a polyimide fiber; (2) dispersing graphene in a solvent to obtain a graphene dispersion; (3) adding the polyimide fiber and an aromatic amine into the graphene dispersion, stirring and completely dissolving the aromatic amine to obtain an aromatic amine / fiber mixture; (4) adding an oxidant into the aromatic amine / fiber mixture, stirring and heating to 50-150 °C, and then keeping warm for 0.5-3 h to obtain an alkali-resistant fiber mixture; (5) taking out the fibers in the alkali-resistant fiber mixture and drying at 100-350 °C for 0.5-3 h to obtain the alkali-resistant polyimide fiber. The present invention uses graphene and an aromatic amine to attach graphene to the surface of the polyimide fiber through an oxidation polymerization method, thereby enhancing the alkali resistance of the polyimide fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of polyimide materials, and particularly to a preparation method of alkali-resistant polyimide fibers and alkali-resistant polyimide fibers. Background Art

[0002] Polyimide fibers have excellent properties such as flame retardancy and self-extinguishing, resistance to high and low temperatures, radiation resistance, stability to most chemical substances, high strength and high modulus, and are widely used in fields such as high-temperature flue gas dust removal and filtration, flame retardancy, heat insulation and heat preservation. However, the imide ring structure of polyimide has poor alkali resistance and cannot stably exist in an alkaline environment, resulting in a problem of decreased mechanical properties of polyimide fibers in an alkaline environment, which limits the further use of polyimide fibers. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of alkali-resistant polyimide fibers and alkali-resistant polyimide fibers, and graphene and aromatic amine are attached to the surface of polyimide fibers through an oxidative polymerization method, thereby enhancing the alkali resistance of polyimide fibers.

[0004] To meet the above technical purpose and its related technical purposes, the present invention provides a preparation method of alkali-resistant polyimide fibers, and the steps thereof include:

[0005] (1) Provide a polyimide fiber;

[0006] (2) Disperse graphene in a solvent to obtain a graphene dispersion;

[0007] (3) Add the polyimide fiber and aromatic amine to the graphene dispersion, stir and completely dissolve the aromatic amine to obtain an aromatic amine / fiber mixture;

[0008] (4) Add an oxidant to the aromatic amine / fiber mixture, stir and heat to 50 - 150 °C, and then keep warm for 0.5 - 3 h to obtain an alkali-resistant fiber mixture;

[0009] (5) Take out the fibers in the alkali-resistant fiber mixture and dry them at 100 - 350 °C for 0.5 - 3 h to obtain the alkali-resistant polyimide fibers.

[0010] In an example of the preparation method of the alkali-resistant polyimide fibers of the present invention, the graphene is selected from one or more of graphene oxide, nitrogen-doped graphene, sulfur-doped graphene, and fluorine-doped graphene.

[0011] In an example of the preparation method of the alkali-resistant polyimide fibers of the present invention, the graphene is graphene oxide.

[0012] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the solvent is selected from one or more of water, alcohol, amide, ether, and ketone.

[0013] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the solvent is water.

[0014] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the aromatic amine is selected from one or more of aniline, phenylenediamine, aminophenol, dopamine, and aminobenzoic acid.

[0015] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the aromatic amine is aminophenol.

[0016] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the oxidant is selected from one of hydrogen peroxide, permanganate, hypochlorite, chlorate, perchlorate, and nitrate.

[0017] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the oxidant is hydrogen peroxide.

[0018] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the polyimide fiber is selected from one of P84, Zhenlun, Jialun, Yilun, and nano-polyimide fiber.

[0019] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amounts of each substance are as follows: 1 part by mass of graphene, 100 - 1000 parts by mass of solvent, 0.1 - 10 parts by mass of aromatic amine, 0.05 - 50 parts by mass of oxidant, and 10 - 200 parts by mass of polyimide fiber.

[0020] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amount of the solvent is 500 - 800 parts by mass.

[0021] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amount of the solvent is 500 parts by mass.

[0022] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amount of the aromatic amine is 1 - 5 parts by mass.

[0023] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amount of the aromatic amine is 1 part by mass.

[0024] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amount of the oxidant is 2 - 30 parts by mass.

[0025] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amount of the oxidant is 2 parts by mass.

[0026] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the dosage of the polyimide fiber is 50 to 150 parts by mass.

[0027] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the dosage of the polyimide fiber is 50 parts by mass.

[0028] The present invention also provides an alkali-resistant polyimide fiber prepared by the preparation method of the alkali-resistant polyimide fiber.

[0029] The preparation method of the alkali-resistant polyimide fiber and the alkali-resistant polyimide fiber of the present invention use graphene and aromatic amine to modify the polyimide fiber. By means of oxidative polymerization, the aromatic amine is used to attach the structurally dense graphene to the surface of the polyimide fiber, and the graphene is used to block the erosion of the polyimide fiber by alkaline substances, thereby improving the alkali resistance of the modified polyimide fiber. At the same time, the modified polyimide fiber still maintains its original fiber state and does not affect subsequent processing and application. Specific Embodiments

[0030] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following examples and the features in the examples can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for the purpose of describing specific specific implementation manners, rather than for limiting the protection scope of the present invention. The test methods without specific conditions noted in the following examples are generally carried out under conventional conditions or according to the conditions recommended by each manufacturer.

[0031] When the embodiments give a numerical range, it should be understood that unless otherwise specified in the present invention, any value at both ends of each numerical range and any value between the two ends can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention, based on the understanding of those skilled in the art of the prior art and the description of the present invention, can also use any methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention to implement the present invention.

[0032] The present invention provides a preparation method of an alkali-resistant polyimide fiber, and its steps include:

[0033] (1) Provide a polyimide fiber;

[0034] (2) Disperse graphene in a solvent to obtain a graphene dispersion;

[0035] (3) Add the polyimide fiber and aromatic amine to the graphene dispersion, stir and completely dissolve the aromatic amine to obtain an aromatic amine / fiber mixture.

[0036] (4) Add an oxidizing agent to the aromatic amine / fiber mixture, stir and heat to 50 - 150 °C, then keep warm for 0.5 - 3 h to obtain an alkali-resistant fiber mixture.

[0037] (5) Take out the fibers in the alkali-resistant fiber mixture and dry them at 100 - 350 °C for 0.5 - 3 h to obtain the alkali-resistant polyimide fiber.

[0038] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the graphene is selected from one or more of graphene oxide, nitrogen-doped graphene, sulfur-doped graphene, and fluorine-doped graphene. Among them, the graphene is preferably graphene oxide.

[0039] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the solvent is selected from one or more of water, alcohol, amide, ether, and ketone. Among them, the solvent is preferably water.

[0040] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the aromatic amine is selected from one or more of aniline, phenylenediamine, aminophenol, dopamine, and aminobenzoic acid. Among them, the aromatic amine is preferably aminophenol.

[0041] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the oxidizing agent is selected from one of hydrogen peroxide, permanganate, hypochlorite, chlorate, perchlorate, and nitrate. Among them, the oxidizing agent is preferably hydrogen peroxide.

[0042] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the polyimide fiber is selected from one of P84, Zhenlun, Jialun, Yilun, and nano-polyimide fiber.

[0043] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amounts of each substance are as follows: 1 part by mass of graphene, 100 - 1000 parts by mass of solvent, 0.1 - 10 parts by mass of aromatic amine, 0.05 - 50 parts by mass of oxidizing agent, and 10 - 200 parts by mass of polyimide fiber.

[0044] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the amount of the solvent is 500 - 800 parts by mass, the amount of the aromatic amine is 1 - 5 parts by mass, the amount of the oxidizing agent is 2 - 30 parts by mass, and the amount of the polyimide fiber is 50 - 150 parts by mass.

[0045] In an example of the preparation method of the alkali-resistant polyimide fiber of the present invention, the dosage of the solvent is 500 parts by mass, the dosage of the aromatic amine is 1 part by mass, the dosage of the oxidant is 2 parts by mass, and the dosage of the polyimide fiber is 50 parts by mass.

[0046] The present invention also provides an alkali-resistant polyimide fiber prepared by the preparation method of the alkali-resistant polyimide fiber.

[0047] The present invention modifies polyimide fibers with graphene and aromatic amines. Graphene has a dense layered honeycomb structure, which endows graphene with very good chemical stability and barrier properties. Due to the similarity of chemical structures, aromatic amines have good affinity for both graphene and polyimide fibers. By means of oxidative polymerization, aromatic amines can be effectively used to attach graphene to the surface of polyimide fibers, and graphene is used to block the erosion of alkaline substances on polyimide fibers, thereby improving the alkali resistance of the modified polyimide fibers. At the same time, the modified polyimide fibers still maintain their original fiber state, without affecting subsequent processing and applications.

[0048] It should be noted that the method described in the present invention can not only modify polyimide fibers, but also modify materials based on polyimide fibers, such as fiber woven fabrics, non-woven fabrics, ropes, etc. The alkali resistance of these materials can be improved by the method described in the present invention. The process of the present invention is simple and can be directly implemented on existing commercial polyimide fibers, such as P84, Zhenlun, Jialun, Yilun, nano-polyimide fibers, etc., and it is easy to realize large-scale industrial production.

[0049] The present invention is described below through multiple examples. The experimental methods used in the examples are all conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0050] Example 1

[0051] A preparation method of an alkali-resistant polyimide fiber is as follows:

[0052] Put 1 g of graphene oxide into 500 g of water. After uniform dispersion, add 50 g of polyimide fiber and 1 g of p-aminophenol and stir continuously. After the p-aminophenol is completely dissolved, add 5 g of hydrogen peroxide, heat to 75 °C, keep warm for 1 h, and stir continuously during this period. Then take out the fiber, wash the surface impurities, and put it into an oven at 250 °C for drying for 1 h to obtain the alkali-resistant polyimide fiber.

[0053] Example 2

[0054] A preparation method of an alkali-resistant polyimide fiber is as follows:

[0055] Place 1 g of nitrogen-doped graphene in 1000 g of isopropanol. After uniform dispersion, add 100 g of polyimide fiber and 5 g of p-phenylenediamine, and continuously stir. After p-phenylenediamine is completely dissolved, add 25 g of hydrogen peroxide. Heat to 50 °C and keep warm for 3 h, with continuous stirring during this period. Then take out the fiber, wash the surface impurities, and place it in an oven at 150 °C for drying for 3 h to obtain the alkali-resistant polyimide fiber.

[0056] Example 3

[0057] A preparation method of alkali-resistant polyimide fiber is as follows:

[0058] Place 2 g of fluorine-doped graphene in a mixed solvent of 50 g of water and 150 g of dimethylacetamide. After uniform dispersion, add 20 g of polyimide fiber, 0.5 g of o-phenylenediamine and 0.5 g of o-aminophenol, and continuously stir. After o-phenylenediamine and o-aminophenol are completely dissolved, add 1 g of lithium perchlorate. Heat to 95 °C and keep warm for 2 h, with continuous stirring during this period. Then take out the fiber, wash the surface impurities, and place it in an oven at 350 °C for drying for 0.5 h to obtain the alkali-resistant polyimide fiber.

[0059] Example 4

[0060] A preparation method of alkali-resistant polyimide fiber is as follows:

[0061] Place 1 g of sulfur-doped graphene in 1000 g of N-methylpyrrolidone. After uniform dispersion, add 100 g of polyimide fiber and 0.2 g of dopamine. After dopamine is completely dissolved, add 0.1 g of sodium nitrate. Heat to 150 °C and keep warm for 3 h, with continuous stirring during this period. Then take out the fiber, wash the surface impurities, and place it in an oven at 200 °C for drying for 2 h to obtain the alkali-resistant polyimide fiber.

[0062] Example 5

[0063] A preparation method of alkali-resistant polyimide fiber is as follows:

[0064] Place 1 g of graphene oxide in 100 g of water. After uniform dispersion, add 10 g of polyimide fiber and 0.1 g of aminophenol, and continuously stir. After aminophenol is completely dissolved, add 0.05 g of hydrogen peroxide. Heat to 150 °C and keep warm for 0.5 h, with continuous stirring during this period. Then take out the fiber, wash the surface impurities, and place it in an oven at 100 °C for drying for 3 h to obtain the alkali-resistant polyimide fiber.

[0065] Example 6

[0066] A preparation method of alkali-resistant polyimide fiber is as follows:

[0067] Put 1 g of graphene oxide into 1000 g of water. After uniform dispersion, add 200 g of polyimide fiber and 10 g of aminophenol and stir continuously. After the aminophenol is completely dissolved, add 50 g of hydrogen peroxide, heat to 150 °C, keep warm for 3 h, and stir continuously during this period. Then take out the fiber, wash the surface impurities, and put it into an oven at 200 °C to dry for 2 h to obtain the alkali-resistant polyimide fiber.

[0068] Example 7

[0069] A preparation method of alkali-resistant polyimide fiber is as follows:

[0070] Put 1 g of graphene oxide into 800 g of water. After uniform dispersion, add 150 g of polyimide fiber and 8 g of aminophenol and stir continuously. After the aminophenol is completely dissolved, add 30 g of hydrogen peroxide, heat to 150 °C, keep warm for 3 h, and stir continuously during this period. Then take out the fiber, wash the surface impurities, and put it into an oven at 200 °C to dry for 2 h to obtain the alkali-resistant polyimide fiber.

[0071] Example 8

[0072] Put 1 g of graphene oxide into 500 g of water. After uniform dispersion, add 50 g of P84 fiber and 1 g of p-aminophenol and stir continuously. After the p-aminophenol is completely dissolved, add 5 g of hydrogen peroxide, heat to 75 °C, keep warm for 1 h, and stir continuously during this period. Then take out the fiber, wash the surface impurities, and put it into an oven at 250 °C to dry for 1 h to obtain the alkali-resistant polyimide fiber.

[0073] Example 9

[0074] Put 1 g of graphene oxide into 500 g of water. After uniform dispersion, add 50 g of Zenlon fiber and 1 g of p-aminophenol and stir continuously. After the p-aminophenol is completely dissolved, add 5 g of hydrogen peroxide, heat to 75 °C, keep warm for 1 h, and stir continuously during this period. Then take out the fiber, wash the surface impurities, and put it into an oven at 250 °C to dry for 1 h to obtain the alkali-resistant polyimide fiber.

[0075] Example 10

[0076] Put 1 g of graphene oxide and 1 g of nitrogen-doped graphene oxide into 1000 g of water. After uniform dispersion, add 200 g of polyimide fiber and 10 g of aminophenol and stir continuously. After the aminophenol is completely dissolved, add 50 g of hydrogen peroxide, heat to 150 °C, keep warm for 3 h, and stir continuously during this period. Then take out the fiber, wash the surface impurities, and put it into an oven at 200 °C to dry for 2 h to obtain the alkali-resistant polyimide fiber.

[0077] Performance test

[0078] The test method refers to the Test Method for Tensile Properties of Chemical Fibre Staple Fibres (GB / T 14337 - 2008). Among them, after the same time of alkali corrosion, the higher the value of the breaking strength (cN / dtex) of the fibre, the better the alkali resistance of the fibre.

[0079] Take 1 g each of the alkali - resistant polyimide fibres prepared in Examples 1 - 9 and the original polyimide fibres, put them into 50 ml of 1 mol / L sodium hydroxide aqueous solution at 80 °C, take out the fibres after 1 minute, 3 minutes, and 5 minutes respectively, and measure the change in their breaking strength. The test results are shown in the following table.

[0080]

[0081] It can be seen from the above table that the original polyimide fibres have poor alkali resistance. After being soaked in the sodium hydroxide solution for 3 minutes, the breaking strength decreases significantly, and the breaking strength is 0 after being soaked for 5 minutes. While the alkali resistance of the alkali - resistant polyimide fibres prepared in Examples 1 - 7 and Example 10 has been significantly improved compared with the original polyimide fibres. After being soaked in the sodium hydroxide solution for 3 minutes and 5 minutes, the decrease in their breaking strength is very small, indicating that the alkali - resistant polyimide fibres prepared by the method described in the present invention have good alkali resistance. Examples 8 and 9 use P84 fibres and Zhenlun fibres respectively to prepare alkali - resistant polyimide fibres, and their alkali resistance has been significantly improved compared with the original P84 fibres and original Zhenlun fibres.

[0082] In summary, the preparation method of the alkali - resistant polyimide fibres and the alkali - resistant polyimide fibres of the present invention use graphene and aromatic amines to modify the polyimide fibres. By means of oxidative polymerization, the aromatic amines are used to attach the densely structured graphene to the surface of the polyimide fibres, and the graphene is used to block the erosion of alkaline substances on the polyimide fibres, thereby improving the alkali resistance of the modified polyimide fibres. At the same time, the modified polyimide fibres still maintain their original fibre state and do not affect subsequent processing and applications.

[0083] The above - mentioned examples are only illustrative of the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above - mentioned examples without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation method of alkali-resistant polyimide fiber, characterized in that the steps include: Disperse graphene in a solvent to obtain a graphene dispersion; Add polyimide fiber and aromatic amine to the graphene dispersion, stir and completely dissolve the aromatic amine to obtain an aromatic amine / fiber mixture; Add an oxidant to the aromatic amine / fiber mixture, stir and heat to 50 - 150 °C, then keep warm for 0.5 - 3 h to obtain an alkali-resistant fiber mixture; Take out the fibers in the alkali-resistant fiber mixture and dry them at 100 - 350 °C for 0.5 - 3 h to obtain the alkali-resistant polyimide fiber; The alkali-resistant polyimide fiber attaches graphene to the surface of the polyimide fiber by using aromatic amine, and uses graphene to block the erosion of alkaline substances on the polyimide fiber, while improving the alkali resistance of the polyimide fiber and maintaining the original fiber state.

2. The preparation method of alkali-resistant polyimide fiber according to claim 1, characterized in that the graphene is selected from one or more of graphene oxide, nitrogen-doped graphene, sulfur-doped graphene, and fluorine-doped graphene.

3. The preparation method of alkali-resistant polyimide fiber according to claim 2, characterized in that the graphene is graphene oxide.

4. The preparation method of alkali-resistant polyimide fiber according to claim 1, characterized in that the solvent is selected from one or more of water, alcohol, amide, ether, and ketone.

5. The preparation method of alkali-resistant polyimide fiber according to claim 1, characterized in that the aromatic amine is selected from one or more of aniline, phenylenediamine, aminophenol, dopamine, and aminobenzoic acid.

6. The preparation method of alkali-resistant polyimide fiber according to claim 5, characterized in that the aromatic amine is aminophenol.

7. The preparation method of alkali-resistant polyimide fiber according to claim 1, characterized in that the oxidant is selected from one of hydrogen peroxide, permanganate, hypochlorite, chlorate, perchlorate, and nitrate.

8. The preparation method of alkali-resistant polyimide fiber according to claim 1, characterized in that the amounts of each substance are respectively: 1 part by mass of graphene, 100 - 1000 parts by mass of solvent, 0.1 - 10 parts by mass of aromatic amine, 0.05 - 50 parts by mass of oxidant, and 10 - 200 parts by mass of polyimide fiber.

9. The preparation method of alkali-resistant polyimide fiber according to claim 8, characterized in that the amount of the solvent is 500 parts by mass, the amount of the aromatic amine is 1 part by mass, the amount of the oxidant is 2 parts by mass, and the amount of the polyimide fiber is 50 parts by mass.

10. An alkali-resistant polyimide fiber prepared by the preparation method of alkali-resistant polyimide fiber according to any one of claims 1 to 9.

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