A high-strength para-aramid fiber and its preparation method

Abstract

The present invention discloses a high-strength para-aramid fiber and a preparation method thereof, comprising: performing a low-temperature polymerization reaction under nitrogen protection using graphene oxide, anhydrous lithium chloride, p-phenylenediamine, and terephthaloyl chloride as raw materials, mixing the obtained solid product with sulfuric acid to obtain a spinning solution; spinning the spinning solution using a dry-jet wet spinning method, and obtaining a para-aramid fiber through the process steps of a coagulation bath, water washing, alkali washing, drying, and winding; immersing the para-aramid fiber in an acetone solution of isopropyl tri(dioctyl pyrophosphate) titanate, ultrasonically treating it, washing it, vacuum drying it, and then performing a high-temperature constant-tension treatment to obtain the high-strength para-aramid fiber. The present invention introduces graphene oxide into the para-aramid fiber, simultaneously performs an impregnation modification treatment on the para-aramid fiber using an acetone solution of isopropyl tri(dioctyl pyrophosphate) titanate, and then performs a high-temperature constant-tension treatment, thereby further improving the mechanical properties of the para-aramid fiber.

Description

Technical Field

[0001] The present invention belongs to the technical field of aramid fiber materials, and in particular relates to a high-strength para-aramid fiber and a preparation method thereof. Background Art

[0002] Aramid fibers are mainly divided into three types: meta-aramid, para-aramid and heterocyclic aramid. Para-aramid, namely poly(p-phenylene terephthalamide) (PPTA), is a fully para-polyaramid formed by the condensation polymerization of para-phenylenediamine and terephthaloyl chloride. Thanks to the conjugation of a large number of benzene rings and amide groups, the PPTA molecular chain segments are difficult to rotate internally and present a rod-like structure. The macromolecular chain shows a high degree of order, which perfectly meets the straight chain structure of high-performance fibers. Para-aramid is widely used in optical fiber reinforcement, safety protection, rubber reinforcement and anti-friction fields. However, with the progress of society, the above-mentioned application fields have put forward higher requirements on the mechanical properties of para-aramid fibers. Due to the internal defects of para-aramid fibers themselves, their mechanical properties cannot meet the use requirements. Therefore, it is of great significance to develop a preparation method for high-strength para-aramid fibers. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these objects and other advantages of the present invention, a method for preparing high-strength para-aramid fiber is provided, comprising the following steps:

[0005] Step 1: Under nitrogen protection, dissolve graphene oxide and anhydrous lithium chloride in anhydrous N-methylpyrrolidone, cool to 5-15°C, add p-phenylenediamine, stir until completely dissolved, cool to -10-0°C, add terephthaloyl chloride, stir for 20-40 minutes, warm to room temperature, and continue stirring for 1-3 hours. The obtained solid product is washed with deionized water until neutral, vacuum dried, crushed, mixed with sulfuric acid, degassed, and filtered to obtain a spinning solution;

[0006] Step 2: Using the obtained spinning solution to spin by dry-jet wet spinning, through the process steps of coagulation bath, water washing, alkali washing, drying and winding, to obtain para-aramid fiber;

[0007] Step 3: Immerse the para-aramid fiber obtained in step 2 in an acetone solution of isopropyl tri(dioctyl pyrophosphate) titanate, perform ultrasonic treatment, wash with acetone and deionized water in sequence, vacuum dry, and perform high-temperature constant tension treatment to obtain high-strength para-aramid fiber.

[0008] Preferably, in step 1, the number of graphene oxide layers is 1 to 3, and the particle size is 100 nm to 1 μm.

[0009] Preferably, in step 1, the mass ratio of graphene oxide, anhydrous lithium chloride and anhydrous N-methylpyrrolidone is 0.05-0.2:4-6:80-200.

[0010] Preferably, in step 1, the mass ratio of graphene oxide to p-phenylenediamine is 0.05-0.2:3.

[0011] Preferably, in step 1, the molar ratio of p-phenylenediamine to terephthaloyl chloride is 1:1 to 1.02.

[0012] Preferably, in step 1, the concentration of sulfuric acid is 98-100 wt %; and the mass ratio of the solid product to sulfuric acid is 1:3-6.

[0013] Preferably, in the step 2, the specific process parameters of spinning are: the coagulation bath temperature is 3°C, the coagulation liquid used is a 2-8wt% sulfuric acid aqueous solution, the draft ratio is 4-8, washed with 5-15°C deionized water, alkaline washed with a calcium hydroxide solution with a pH of 8-10, the drying temperature is 100-200°C, and the spinning speed is 200-400m / min.

[0014] Preferably, in step 3, the ultrasonic treatment is performed at a power of 200 to 400 W, a frequency of 60 to 80 kHz, and a time of 1 to 3 hours.

[0015] Preferably, in the step 3, the concentration of isopropyl tri(dioctyl pyrophosphate) titanate in the acetone solution of isopropyl tri(dioctyl pyrophosphate) titanate is 1 to 6 wt %.

[0016] Preferably, in step three, the high temperature constant tension treatment is specifically: treatment in a nitrogen atmosphere at 300-350° C. and a tension of 1.0-1.2 cN / dtex for 3-5 minutes.

[0017] Preferably, in the step 1, modified graphene oxide is used to replace graphene oxide; the preparation method of the modified graphene is: dispersing graphene oxide into anhydrous ethanol, adding polyvinyl pyrrolidone K20 and polyethylene glycol diamine (M w =2000), ultrasonically treating at 20-50° C., 100-400 W, 40-60 kHz for 0.5-2 h to obtain a dispersion; adding calcium chloride to the dispersion, maintaining stirring, heating to 50-70° C., keeping the temperature for 0.5-2 h, standing for 10-24 h, evaporating the solvent, and vacuum drying to obtain modified graphene oxide; wherein the mass volume ratio of graphene oxide, polyvinyl pyrrolidone K20, polyethylene glycol diamine, calcium chloride and anhydrous ethanol is 1 g:0.1-0.3 g:0.1-0.5 g:0.05-0.2 g:30-60 mL.

[0018] A high-strength para-aramid fiber prepared by the preparation method described above.

[0019] The present invention includes at least the following beneficial effects: the present invention introduces graphene oxide with extremely high mechanical strength into para-aramid fiber through in-situ polymerization, which can fill its internal defects and improve its mechanical properties; at the same time, the present invention uses an acetone solution of isopropyl tri(dioctyl pyrophosphate) titanate to perform an impregnation modification treatment on the obtained para-aramid fiber, and then performs a high-temperature constant tension treatment to induce molecular chain rearrangement and crystallization, promote bonding and cross-linking, and the graphene oxide contains rich oxygen-containing groups such as carboxyl groups, and has a synergistic effect with isopropyl tri(dioctyl pyrophosphate) titanate, thereby further improving the mechanical properties of the para-aramid; in addition, the present invention uses polyvinyl pyrrolidone, polyethylene glycol diamine and calcium chloride to perform surface modification treatment on the graphene oxide, further improving its dispersibility and uniformity in the system, increasing active sites, facilitating its cross-linking with the para-aramid, enhancing the synergistic coordination with isopropyl tri(dioctyl pyrophosphate) titanate, and further improving the mechanical properties of the para-aramid. The high-strength para-aramid fiber prepared by the invention has a tensile strength of ≥26 cN / dtex and an elongation at break of 3.7% to 4.0%.

[0020] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0021] The present invention is described in further detail below so that those skilled in the art can implement the invention with reference to the description.

[0022] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0023] In the following examples, the graphene oxide used has 1 to 3 layers and a particle size of 100 nm to 1 μm.

[0024] Example 1

[0025] A method for preparing high-strength para-aramid fiber comprises the following steps:

[0026] Step 1. Under nitrogen protection, 1 g of graphene oxide and 50 g of anhydrous lithium chloride were added to 1000 g of anhydrous N-methylpyrrolidone, stirred evenly, cooled to 10 ° C, added 30 g of p-phenylenediamine, stirred until completely dissolved, cooled to -5 ° C, added 57 g of terephthaloyl chloride, stirred at -5 ° C for 30 minutes, warmed to room temperature, and continued to stir for 2 hours. The obtained solid product was washed with deionized water until neutral, vacuum dried, and crushed, and then mixed with 98 wt% sulfuric acid at a mass ratio of 1:4, degassed, and filtered to obtain a spinning solution;

[0027] Step 2: The obtained spinning solution is subjected to dry-jet wet spinning, and the fiber is subjected to the process steps of coagulation bath, water washing, alkali washing, drying and winding to obtain para-aramid fiber; wherein the specific process parameters are: coagulation bath temperature of 3°C, coagulation liquid used is 5wt% sulfuric acid aqueous solution, draft ratio of 6, 10°C deionized water washing, pH 9 calcium hydroxide solution alkali washing, drying temperature of 150°C, and spinning speed of 300m / min;

[0028] Step 3: Immerse the para-aramid fiber obtained in step 2 in an acetone solution containing 4 wt% isopropyl tri(dioctyl pyrophosphate) titanate, ultrasonically treat it at 300 W and 70 kHz for 2 h, wash it with acetone and deionized water in sequence, vacuum dry it, and treat it in nitrogen at 350° C. and a tension of 1.2 cN / dtex for 3 min to obtain a high-strength para-aramid fiber. The tensile strength of the fiber is 26.22 cN / dtex and the elongation at break is 3.9% when tested according to GB / T14344-2008.

[0029] Example 2

[0030] A method for preparing high-strength para-aramid fiber comprises the following steps:

[0031] Step 1. Under nitrogen protection, 2 g of graphene oxide and 50 g of anhydrous lithium chloride were added to 1000 g of anhydrous N-methylpyrrolidone, stirred evenly, cooled to 10 ° C, added 30 g of p-phenylenediamine, stirred until completely dissolved, cooled to -5 ° C, added 57 g of terephthaloyl chloride, stirred at -5 ° C for 30 minutes, warmed to room temperature, and continued to stir for 2 hours. The obtained solid product was washed with deionized water until neutral, vacuum dried, and crushed, and then mixed with 98 wt% sulfuric acid at a mass ratio of 1:4, degassed, and filtered to obtain a spinning solution;

[0032] Step 2: The obtained spinning solution is subjected to dry-jet wet spinning, and the fiber is subjected to the process steps of coagulation bath, water washing, alkali washing, drying and winding to obtain para-aramid fiber; wherein the specific process parameters are: coagulation bath temperature of 3°C, coagulation liquid used is 5wt% sulfuric acid aqueous solution, draft ratio of 6, 10°C deionized water washing, pH 9 calcium hydroxide solution alkali washing, drying temperature of 150°C, and spinning speed of 300m / min;

[0033] Step 3: Immerse the para-aramid fiber obtained in step 2 in an acetone solution containing 1 wt% isopropyl tri(dioctyl pyrophosphate) titanate, ultrasonically treat it at 300 W and 70 kHz for 2 h, wash it with acetone and deionized water in sequence, vacuum dry it, and treat it in nitrogen at 300°C and a tension of 1.0 cN / dtex for 5 min to obtain a high-strength para-aramid fiber with a tensile strength of 26.00 cN / dtex and an elongation at break of 3.8%.

[0034] Example 3

[0035] A method for preparing high-strength para-aramid fiber comprises the following steps:

[0036] Step 1. Under nitrogen protection, 0.5 g of graphene oxide and 50 g of anhydrous lithium chloride were added to 1000 g of anhydrous N-methylpyrrolidone, stirred evenly, cooled to 10 ° C, added 30 g of p-phenylenediamine, stirred until completely dissolved, cooled to -5 ° C, added 57 g of terephthaloyl chloride, stirred at -5 ° C for 30 minutes, warmed to room temperature, and continued to stir for 2 hours. The obtained solid product was washed with deionized water until neutral, vacuum dried, and crushed, and then mixed with 98 wt% sulfuric acid at a mass ratio of 1:4, degassed, and filtered to obtain a spinning solution;

[0037] Step 2: The obtained spinning solution is subjected to dry-jet wet spinning, and the fiber is subjected to the process steps of coagulation bath, water washing, alkali washing, drying and winding to obtain para-aramid fiber; wherein the specific process parameters are: coagulation bath temperature of 3°C, coagulation liquid used is 5wt% sulfuric acid aqueous solution, draft ratio of 6, 10°C deionized water washing, pH 9 calcium hydroxide solution alkali washing, drying temperature of 150°C, and spinning speed of 300m / min;

[0038] Step 3: Immerse the para-aramid fiber obtained in step 2 in an acetone solution containing 6 wt% isopropyl tri(dioctyl pyrophosphate) titanate, ultrasonically treat it at 300 W and 70 kHz for 2 h, wash it with acetone and deionized water in sequence, vacuum dry it, and treat it in nitrogen at 350°C and a tension of 1.2 cN / dtex for 3 min to obtain a high-strength para-aramid fiber with a tensile strength of 26.15 cN / dtex and an elongation at break of 3.7%.

[0039] Example 4

[0040] In this embodiment, modified graphene oxide is used instead of graphene oxide, and the remaining steps are the same as those in Example 1 to obtain a high-strength para-aramid fiber with a tensile strength of 27.95 cN / dtex and an elongation at break of 4.0%.

[0041] The preparation method of modified graphene is as follows: 10g of graphene oxide is dispersed in 500mL of anhydrous ethanol, 2g of polyvinylpyrrolidone K20 and 2g of polyethylene glycol diamine (M W =2000), ultrasonically treated at 40°C, 300W, and 50kHz for 1 hour to obtain a dispersion; 1 g of calcium chloride was added to the dispersion, and the mixture was stirred, heated to 60°C, kept warm for 1 hour, allowed to stand for 12 hours, and the solvent was evaporated at 40°C, and vacuum dried at 60°C to obtain modified graphene oxide.

[0042] Example 5

[0043] In this embodiment, modified graphene oxide is used instead of graphene oxide, and the remaining steps are the same as those in Example 1 to obtain a high-strength para-aramid fiber with a tensile strength of 27.30 cN / dtex and an elongation at break of 3.9%.

[0044] The preparation method of modified graphene is as follows: 10g of graphene oxide is dispersed in 500mL of anhydrous ethanol, 2g of polyvinylpyrrolidone K20 and 2g of polyethylene glycol diamine (M W =2000), ultrasonically treated at 40°C, 300W, and 50kHz for 1 hour to obtain a dispersion; while maintaining stirring, the dispersion was heated to 60°C, kept warm for 1 hour, allowed to stand for 12 hours, the solvent was evaporated at 40°C, and vacuum dried at 60°C to obtain modified graphene oxide.

[0045] Comparative Example 1

[0046] In this comparative example, graphene oxide was not added, and the remaining steps were the same as those in Example 1. The obtained high-strength para-aramid fiber had a tensile strength of 24.03 cN / dtex and an elongation at break of 3.7%.

[0047] Comparative Example 2

[0048] In this comparative example, isopropyl tris(dioctyl pyrophosphate) titanate was not used for treatment, and the remaining steps were the same as those in Example 1, specifically:

[0049] Step 1. Under nitrogen protection, 1 g of graphene oxide and 50 g of anhydrous lithium chloride were added to 1000 g of anhydrous N-methylpyrrolidone, stirred evenly, cooled to 10 ° C, added 30 g of p-phenylenediamine, stirred until completely dissolved, cooled to -5 ° C, added 57 g of terephthaloyl chloride, stirred at -5 ° C for 30 minutes, warmed to room temperature, and continued to stir for 2 hours. The obtained solid product was washed with deionized water until neutral, vacuum dried, and crushed, and then mixed with 98 wt% sulfuric acid at a mass ratio of 1:4, degassed, and filtered to obtain a spinning solution;

[0050] Step 2: The obtained spinning solution is subjected to dry-jet wet spinning, and the fiber is subjected to the process steps of coagulation bath, water washing, alkali washing, drying and winding to obtain para-aramid fiber; wherein the specific process parameters are: coagulation bath temperature of 3°C, coagulation liquid used is 5wt% sulfuric acid aqueous solution, draft ratio of 6, 10°C deionized water washing, pH 9 calcium hydroxide solution alkali washing, drying temperature of 150°C, and spinning speed of 300m / min;

[0051] Step 3: Immerse the para-aramid fiber obtained in step 2 in acetone, ultrasonically treat it at 300W and 70kHz for 2h, wash it with acetone and deionized water in sequence, vacuum dry it, and treat it in nitrogen at 350°C and a tension of 1.2cN / dtex for 3min to obtain a high-strength para-aramid fiber with a tensile strength of 24.36cN / dtex and an elongation at break of 3.6%.

[0052] Comparative Example 3

[0053] In this comparative example, a 4 wt % isopropyl tri(dioctyl pyrophosphate) titanate ethanol solution was used instead of a 4 wt % isopropyl tri(dioctyl pyrophosphate) titanate acetone solution. The remaining steps were the same as in Example 1 to obtain a high-strength para-aramid fiber having a tensile strength of 25.40 cN / dtex and an elongation at break of 3.8%.

[0054] Comparative Example 4

[0055] This comparative example does not undergo high-temperature constant tension treatment, and the remaining steps are the same as those in Example 1, specifically:

[0056] Step 1. Under nitrogen protection, 1 g of graphene oxide and 50 g of anhydrous lithium chloride were added to 1000 g of anhydrous N-methylpyrrolidone, stirred evenly, cooled to 10 ° C, added 30 g of p-phenylenediamine, stirred until completely dissolved, cooled to -5 ° C, added 57 g of terephthaloyl chloride, stirred at -5 ° C for 30 minutes, warmed to room temperature, and continued to stir for 2 hours. The obtained solid product was washed with deionized water until neutral, vacuum dried, and crushed, and then mixed with 98 wt% sulfuric acid at a mass ratio of 1:4, degassed, and filtered to obtain a spinning solution;

[0057] Step 2: The obtained spinning solution is subjected to dry-jet wet spinning, and the fiber is subjected to the process steps of coagulation bath, water washing, alkali washing, drying and winding to obtain para-aramid fiber; wherein the specific process parameters are: coagulation bath temperature of 3°C, coagulation liquid used is 5wt% sulfuric acid aqueous solution, draft ratio of 6, 10°C deionized water washing, pH 9 calcium hydroxide solution alkali washing, drying temperature of 150°C, and spinning speed of 300m / min;

[0058] Step 3: Immerse the para-aramid fiber obtained in step 2 in an acetone solution containing 4 wt% isopropyl tri(dioctyl pyrophosphate) titanate, ultrasonically treat it at 300 W and 70 kHz for 2 h, wash it with acetone and deionized water in sequence, and vacuum dry it to obtain a high-strength para-aramid fiber with a tensile strength of 24.81 cN / dtex and an elongation at break of 3.7%.

[0059] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for preparing high-strength para-aramid fiber, characterized in that: The following steps are involved: Step 1: Under nitrogen protection, dissolve graphene oxide and anhydrous lithium chloride in anhydrous N-methylpyrrolidone, cool to 5-15°C, add p-phenylenediamine, stir until completely dissolved, cool to -10-0°C, add terephthaloyl chloride, stir for 20-40 minutes, warm to room temperature, and continue stirring for 1-3 hours. The obtained solid product is washed with deionized water until neutral, vacuum dried, crushed, mixed with sulfuric acid, degassed, and filtered to obtain a spinning solution; Step 2: Using the obtained spinning solution to spin by dry-jet wet spinning, through the process steps of coagulation bath, water washing, alkali washing, drying and winding, to obtain para-aramid fiber; Step 3: Immerse the para-aramid fiber obtained in step 2 in an acetone solution of isopropyl tri(dioctyl pyrophosphate) titanate, perform ultrasonic treatment, wash with acetone and deionized water in sequence, vacuum dry, and perform high-temperature constant tension treatment to obtain high-strength para-aramid fiber; In the step 1, before using the graphene oxide, the graphene oxide is modified: the graphene oxide is dispersed in anhydrous ethanol, polyvinyl pyrrolidone K20 and polyethylene glycol diamine are added, and ultrasonic treatment is performed at 20-50° C., 100-400 W, and 40-60 kHz for 0.5-2 hours to obtain a dispersion; calcium chloride is added to the dispersion, and the mixture is stirred, heated to 50-70° C., kept warm for 0.5-2 hours, allowed to stand for 10-24 hours, the solvent is evaporated and vacuum dried to obtain modified graphene oxide; wherein the mass volume ratio of graphene oxide, polyvinyl pyrrolidone K20, polyethylene glycol diamine, calcium chloride and anhydrous ethanol is 1g:0.1-0.3g:0.1-0.5g:0.05-0.2g:30-60mL.

2. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 1, the number of graphene oxide layers is 1 to 3, and the particle size is 100 nm to 1 μm; the mass ratio of graphene oxide, anhydrous lithium chloride and anhydrous N-methylpyrrolidone is 0.05 to 0.2:4 to 6:80 to 200.

3. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 1, the mass ratio of graphene oxide to p-phenylenediamine is 0.05-0.2:

3.

4. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 1, the molar ratio of p-phenylenediamine to terephthaloyl chloride is 1:1-1.

02.

5. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 1, the concentration of sulfuric acid is 98-100 wt %; and the mass ratio of the solid product to the sulfuric acid is 1:3-6.

6. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 2, the specific process parameters of the spinning are: the coagulation bath temperature is 3°C, the coagulation liquid used is a 2-8wt% sulfuric acid aqueous solution, the draft ratio is 4-8, the deionized water washing is 5-15°C, the calcium hydroxide solution alkaline washing is with a pH of 8-10, the drying temperature is 100-200°C, and the spinning speed is 200-400 m / min.

7. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 3, the power of the ultrasonic treatment is 200-400 W, the frequency is 60-80 kHz, and the time is 1-3 h.

8. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 3, the concentration of isopropyl tris(dioctyl pyrophosphate) titanate in the acetone solution of isopropyl tris(dioctyl pyrophosphate) titanate is 1-6 wt %.

9. The method for preparing high-strength para-aramid fiber according to claim 1, wherein: In the step 3, the high temperature constant tension treatment is specifically: treating in a nitrogen atmosphere at 300-350° C. and a tension of 1.0-1.2 cN / dtex for 3-5 minutes.

10. A high-strength para-aramid fiber prepared by the preparation method according to any one of claims 1 to 9.