Fiber aramid fiber with strong chemical corrosion resistance and preparation process thereof

Abstract

The invention provides a fiber aramid fiber with strong chemical corrosion resistance and a preparation process thereof, and relates to the field of fiber materials.The preparation process comprises the following steps that raw materials are prepared; performing low-temperature solution polycondensation reaction; preparing a spinning solution; carrying out dry-wet spinning; the method has the beneficial effects that the fiber aramid fiber has extremely high tolerance to common chemical corrosion media such as strong acid, strong alkali and organic solvents, and after the fiber aramid fiber is soaked in strong oxidizing acid such as concentrated sulfuric acid and concentrated nitric acid for 100 hours, the strength retention rate of the fiber is still 90% or above; and the strength retention rate can reach more than 85% after the material is soaked in sodium hydroxide, potassium hydroxide and other strong alkali solutions for the same time.

Description

Technical Field

[0001] The present invention relates to the field of fiber materials, and particularly to a fiber aramid with strong chemical corrosion resistance and its preparation process. Background Art

[0002] As a high-performance fiber material, aramid fiber has excellent properties such as high strength, high modulus, and high temperature resistance, and has been widely used in many fields such as aerospace, national defense, and the automotive industry. However, in some special environments, such as the chemical industry and the marine field, materials need to have stronger chemical corrosion resistance to ensure their long-term stable use performance. Existing aramid fibers still have certain limitations in resisting some strongly corrosive chemical substances and cannot fully meet the use requirements in these special environments. Summary of the Invention

[0003] The purpose of the present invention is to provide a fiber aramid with strong chemical corrosion resistance and its preparation process, which enhances the stability and durability in a chemical corrosion environment.

[0004] In order to achieve the above-mentioned invention purpose, the technical solution adopted by the present invention is: a fiber aramid with strong chemical corrosion resistance and its preparation process, including the following steps: Step 1, raw material preparation: Select p-phenylenediamine and terephthaloyl chloride with a purity of more than 99.9% as the main raw materials, prepare an appropriate amount of a modifier containing fluorine atoms and N-methylpyrrolidone (NMP) as the reaction medium;

[0005] Step 2, low-temperature solution polycondensation reaction: Dissolve p-phenylenediamine in NMP to prepare a solution with a concentration of 5-10 wt%, and slowly drop the NMP solution of terephthaloyl chloride in a low-temperature environment of 0-5 °C, and at the same time add a modifier containing fluorine atoms, and carry out a polycondensation reaction for 2-4 hours under stirring conditions, and control the pH value of the reaction system at 7-8 during the reaction process;

[0006] Step 3, spinning solution preparation: Filter the polymer solution obtained from the polycondensation reaction, and then adjust the solution concentration to 15-20 wt% by vacuum distillation to obtain a spinning solution;

[0007] Step 4, wet-dry spinning: Extrude the spinning solution through a spinneret to form a thin stream, and the thin stream first passes through an air layer of 5-10 cm, and then enters a sodium chloride coagulation bath with a concentration of 5-10 wt% for coagulation and forming;

[0008] Step 5, post-treatment: Wash the formed fiber with water, then carry out a stretching treatment of 3-5 times, and finally heat-treat at 300-350 °C for 1-2 hours.

[0009] As an improvement, the modifier containing fluorine atoms is perfluorooctanoic anhydride.

[0010] As an improvement, the pH value of the reaction system is adjusted by adding triethylamine.

[0011] The beneficial effects of the present invention are as follows: The fiber aramid of the present invention has extremely strong tolerance to common chemical corrosion media such as strong acids, strong bases, and organic solvents. After being immersed in strong oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid for 100 hours, the strength retention rate of the fiber is still above 90%; after being immersed in strong base solutions such as sodium hydroxide and potassium hydroxide for the same time, the strength retention rate can also reach above 85%. Description of the Drawings

[0012] Figure 1 It is a framework diagram of a fiber aramid with strong chemical corrosion resistance and its preparation process of the present invention. Detailed Embodiments

[0013] In order to make the content of the present invention easier to be clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0014] As Figure 1 shown, a fiber aramid with strong chemical corrosion resistance and its preparation process include the following steps: Step 1, raw material preparation: Select p-phenylenediamine and terephthaloyl chloride with a purity of more than 99.9% as the main raw materials, prepare an appropriate amount of a modifier containing fluorine atoms and N-methylpyrrolidone (NMP) as the reaction medium;

[0015] Step 2, low-temperature solution polycondensation reaction: Dissolve p-phenylenediamine in NMP to prepare a solution with a concentration of 5-10 wt%, and slowly drop the NMP solution of terephthaloyl chloride in a low-temperature environment of 0-5 °C, and at the same time add a modifier containing fluorine atoms, and carry out a polycondensation reaction for 2-4 hours under stirring conditions, and control the pH value of the reaction system at 7-8 during the reaction process;

[0016] Step 3, spinning solution preparation: Filter the polymer solution obtained from the polycondensation reaction, and then adjust the solution concentration to 15-20 wt% by vacuum distillation to obtain a spinning solution;

[0017] Step 4, wet-dry spinning: Extrude the spinning solution through a spinneret to form a thin stream, the thin stream first passes through an air layer of 5-10 cm, and then enters a sodium chloride coagulation bath with a concentration of 5-10 wt% to solidify and form;

[0018] Step 5, post-treatment: Wash the formed fiber with water, then carry out a stretching treatment of 3-5 times, and finally heat-treat at 300-350 °C for 1-2 hours.

[0019] The modifier containing fluorine atoms is perfluorooctanoic anhydride.

[0020] Adjust the pH value of the reaction system by adding triethylamine.

[0021] In the actual use process of the present invention, high-purity p-phenylenediamine and terephthaloyl chloride are selected as the main raw materials to ensure that the purity of the raw materials reaches more than 99.9%. At the same time, an appropriate amount of modifier containing fluorine atoms, such as perfluorooctanoic anhydride, etc., is prepared. In addition, a suitable organic solvent, such as N-methylpyrrolidone (NMP), is selected as the reaction medium. Dissolve p-phenylenediamine in NMP to prepare a solution with a concentration of 5-10 wt%. In a low-temperature environment, generally control the temperature at 0-5 °C, and slowly drop the NMP solution of terephthaloyl chloride. At the same time, add an appropriate amount of modifier containing fluorine atoms, and carry out a polycondensation reaction under stirring conditions. The reaction time is 2-4 hours. During the reaction process, strictly control the pH value of the reaction system between 7 and 8, and adjust the pH value by adding an appropriate amount of alkaline substance, such as triethylamine. Filter the polymer solution obtained from the polycondensation reaction to remove possible impurities therein. Then, by means of vacuum distillation, remove part of the organic solvent in the solution and adjust the concentration of the polymer solution to 15-20 wt% to obtain a spinning solution. Extrude the spinning solution through a spinneret to form a fine stream. The fine stream first passes through an air layer with a length of 5-10 cm, and then enters a coagulation bath. The coagulation bath uses an inorganic salt solution with a certain concentration, such as sodium chloride solution, with a concentration of 5-10 wt%. In the coagulation bath, the fiber quickly solidifies and forms. Wash the formed fiber with water to remove the residual solvent and impurities on the surface, and then carry out a stretching treatment with a stretching ratio of 3-5 times to improve the orientation degree and strength of the fiber. Finally, carry out a heat treatment in a high-temperature environment. The heat treatment temperature is 300-350 °C and the time is 1-2 hours to further improve the crystal structure and performance of the fiber.

[0022] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fiber aramid with strong chemical corrosion resistance and its preparation process, characterized in that, It includes the following steps: Step 1, raw material preparation: Select p-phenylenediamine and terephthaloyl chloride with a purity of over 99.9% as the main raw materials, prepare an appropriate amount of a modifier containing fluorine atoms and N-methylpyrrolidone (NMP) as the reaction medium; Step 2, low-temperature solution polycondensation reaction: Dissolve p-phenylenediamine in NMP to prepare a solution with a concentration of 5-10 wt%, and slowly drop the NMP solution of terephthaloyl chloride in a low-temperature environment of 0-5 °C, and at the same time add a modifier containing fluorine atoms, and carry out a polycondensation reaction for 2-4 hours under stirring conditions, and control the pH value of the reaction system at 7-8 during the reaction; Step 3, spinning solution preparation: Filter the polymer solution obtained from the polycondensation reaction, and then adjust the solution concentration to 15-20 wt% by vacuum distillation to obtain a spinning solution; Step 4, wet-dry spinning: Extrude the spinning solution through a spinneret to form a thin stream, the thin stream first passes through an air layer of 5-10 cm, and then enters a sodium chloride coagulation bath with a concentration of 5-10 wt% to solidify and form; Step 5, post-treatment: Wash the formed fibers with water, then carry out a stretching treatment of 3-5 times, and finally heat-treat at 300-350 °C for 1-2 hours.

2. The fiber aramid with strong chemical corrosion resistance and its preparation process according to claim 1, characterized in that, The modifier containing fluorine atoms is perfluorooctanoic anhydride.

3. A fiber aramid with strong chemical corrosion resistance and its preparation process according to claim 1, characterized in that, Adjust the pH value of the reaction system by adding triethylamine.

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