A graphene-modified polyamide 6 composite fiber and preparation method thereof

Abstract

This invention relates to the field of composite fiber technology, specifically to a graphene-modified polyamide 6 composite fiber and its preparation method. The composite fiber of this application is obtained by adding chlorinated modified graphene to polyamide 6, followed by compounding and molding. The preparation method of the chlorinated modified graphene includes the following steps: coating graphene oxide with silica; subjecting the silica-coated graphene oxide to acylchlorination treatment, then grafting L-glutamic acid; modifying the grafted graphene with 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin to obtain modified graphene; and chlorinating the modified graphene with sodium hypochlorite to obtain chlorinated modified graphene. The composite fiber of this application has advantages such as high tensile strength and good antibacterial effect.

Description

Technical Field

[0001] The present invention relates to the technical field of composite fibers, and in particular to a graphene-modified polyamide 6 composite fiber and a preparation method thereof. Background Art

[0002] Polyamide 6 fiber is made by ring-opening polymerization of caprolactam and then spinning. It has excellent performance, high strength, good wear resistance, good chemical corrosion resistance, and good washability and wearability. However, since polyamide 6 itself does not have the ability to kill bacteria, it is easy for bacteria to grow on the fiber surface, causing humans to suffer from diseases. Therefore, it is of great significance to prepare polyamide 6 composite fibers with multiple functionalities such as antibacterial and UV resistance.

[0003] Graphene has extremely excellent mechanical properties and structural rigidity, and has excellent tensile strength. Graphene is also a very good antibacterial material. Graphene can be used to modify polyamide 6 to produce composite fibers with antibacterial and good tensile strength. The patent with application number CN2019102145385 introduces a colored polyamide 6 fiber and its production method, which uses graphene polyamide 6 to replace part or all of polyamide 6, and uses the adsorption of graphene in the molecular chain to solve the problem of poor color fastness of colored polyamide 6. Although the twin-screw co-extrusion method slightly improves the uniformity of the composite material, due to the large specific surface area of ​​graphene and the π-π effect between the sheets, it is difficult to disperse evenly in the polyamide 6 matrix. Summary of the invention

[0004] In order to improve the dispersibility of graphene in polyamide 6 and improve the antibacterial performance of the composite material, the present invention provides a graphene-modified polyamide 6 composite fiber and a preparation method thereof.

[0005] To solve the above problems, this application adopts the following technical solutions:

[0006] A method for preparing a graphene-modified polyamide 6 composite fiber comprises the following steps: adding chlorinated modified graphene to polyamide 6, compounding and molding, and preparing the graphene-modified polyamide 6 composite fiber;

[0007] The preparation method of the chlorinated modified graphene comprises the following steps:

[0008] S1: coating graphene oxide with silicon dioxide to obtain graphene oxide coated with silicon dioxide;

[0009] S2: treating the silicon dioxide-coated graphene oxide with acyl chloride, and then grafting L-glutamic acid to obtain grafted graphene;

[0010] S3: using 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin to modify the grafted graphene to obtain modified graphene, and chlorinating the modified graphene to obtain chlorinated modified graphene.

[0011] Furthermore, the mass ratio of the polyamide 6 to the chlorinated modified graphene is 100:(0.05-0.2).

[0012] Furthermore, the specific steps of S1 are as follows: uniformly mix the silane coupling agent and ethanol, drop dilute hydrochloric acid, adjust the pH value to 3.8-4.2, let stand, add graphene oxide, ultrasonically disperse, and react at 70-80°C; after drying, add tetraethyl orthosilicate, ammonia water, ethanol, and deionized water, and react at 20-26°C for 18-20h to obtain graphene coated with silicon dioxide, and the mass ratio of the silane coupling agent, graphene oxide and tetraethyl orthosilicate is (4-6):0.1:(1.5-3).

[0013] Furthermore, the silane coupling agent is a vinyl silane coupling agent.

[0014] Furthermore, the specific steps of S2 are as follows:

[0015] S2-1: adding graphene coated with silicon dioxide, thionyl chloride and pyridine, heating at 60-70° C. to react, performing atmospheric distillation after the reaction, washing and filtering, and drying to obtain chlorinated graphene;

[0016] S2-2: Add chlorinated graphene, N,N-dimethylacetamide, L-glutamic acid, and pyridine to react, wash and filter, and then dry to obtain grafted graphene, wherein the usage ratio of the chlorinated graphene to the L-glutamic acid is 1: (1 to 2.5).

[0017] Furthermore, the specific steps of S3 are as follows:

[0018] S3-1: adding the grafted graphene, 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin, water, and ethanol, dispersing them by ultrasound, and then reacting them at 70-80° C. for 6-8 hours, washing and drying the solid, and obtaining modified graphene;

[0019] S3-2: Add sodium hypochlorite aqueous solution to modify graphene, react it at room temperature, wash and dry the solid to obtain chlorinated modified graphene.

[0020] Furthermore, the preparation method of the 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin comprises the following steps:

[0021] Add 5,5-dimethylhydantoin, sodium hydroxide and ethanol to prepare hydantoin sodium salt; carry out substitution reaction with 3-chloropropyltriethoxysilane in N,N-dimethylformamide solvent to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer; add water and ethanol to 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer, adjust pH value to 4.5-5.5, react at 70-80°C for 4-5h, evaporate to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin.

[0022] Furthermore, the compounding and molding specifically includes: shear mixing, granulation, melt extrusion to obtain masterbatch, drying for 10 to 16 hours, and melt spinning.

[0023] A graphene-modified polyamide 6 composite fiber is prepared by the above method.

[0024] Compared with the prior art, this application has the following beneficial effects:

[0025] 1. Graphene oxide was modified with a vinyl silane coupling agent, and silica microspheres were uniformly coated on its surface to prepare silica-coated modified graphene, which made it difficult for graphene to agglomerate in polyamide 6, improved the interfacial force, facilitated the acquisition of graphene-modified polyamide 6 composite fibers with good dispersion, and improved the breaking strength of the composite fibers.

[0026] 2. The silica-coated graphene oxide is treated with chlorination, and the monoacid is converted into a diacid by grafting L-glutamic acid, which increases the reactive sites of graphene and allows more sites to react with 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin, thereby enhancing the antibacterial properties, making the modified graphene better dispersed in polyamide 6 and more tightly combined with polyamide 6, thereby improving the breaking strength of the composite fiber.

[0027] 3. Adding 5,5-dimethyl-3-(3'-triethoxysilylpropyl) hydantoin to modify graphene maintains the lamellar structure of graphene oxide, increases the specific surface area of ​​the modified graphene, enhances the adsorption capacity, and can restrain the free movement of bacteria; and the surface of the modified graphene is electronegative, under the electric field force, the cell membrane is ruptured due to uneven charge distribution, causing the bacteria to overflow and die; the lamellar structure of the modified graphene will damage the bacteria, and at the same time, the modified graphene is chlorinated, and the oxidized chloride ions are released into the cells, oxidizing the active groups in the bacteria, inhibiting the metabolism of the bacteria, causing the death of the bacteria, and enhancing the antibacterial effect of the composite fiber. DETAILED DESCRIPTION

[0028] The present application is further described below in conjunction with specific embodiments.

[0029] The graphene oxide in Examples 1-3 of the present application is selected from Changzhou Sixth Element Materials Technology Co., Ltd., model SE2430W-N; self-made graphene oxide is selected in Examples 4 and 5 of the present application.

[0030] In the present application, the vinyl silane coupling agent selected is silane coupling agent CG-171, CG-172, CG-151, and other vinyl silane coupling agents may also be selected; silane coupling agent CG-171, silane coupling agent CG-172, and silane coupling agent CG-151 are all selected from Jiangxi Chenguang New Materials Co., Ltd.

[0031] Example 1

[0032] A graphene-modified polyamide 6 composite fiber is prepared by the following method:

[0033] Step 1: Mix 5g of silane coupling agent CG-171 and 60mL of ethanol, add dilute hydrochloric acid, adjust the pH value to 4, let stand for 10min, add 100mg of graphene oxide, ultrasonically treat for 1.5h, react at 75°C for 3.5h, and centrifuge to dry; add 2g of tetraethyl orthosilicate, 15mL of 28% ammonia water, 20mL of ethanol, and 50mL of deionized water, mix well, and react at 23°C for 19h to obtain graphene coated with silica.

[0034] Step 2: ① Heat 100 mg of graphene coated with silica, 5 mL of thionyl chloride and 0.11 mL of pyridine at 65 ° C, stir for 22 hours, distill at atmospheric pressure, wash three times with tetrahydrofuran, and centrifuge; vacuum dry at 26 ° C for 11 hours to obtain chlorinated graphene; ② Take 100 mg of chlorinated graphene and put it into a three-necked flask, add 30 mL of N, N-dimethylacetamide, add 0.1 g of L-glutamic acid, add 0.11 mL of pyridine, stir magnetically at 60 ° C for 11 hours, filter and separate, wash three times with N, N-dimethylacetamide and distilled water respectively, filter, and vacuum freeze-dry at -55 ° C for 22 hours to obtain grafted graphene.

[0035] Step 3: ① Take 1.2 g 5,5-dimethylhydantoin, 2 g sodium hydroxide, and 100 mL ethanol, stir at room temperature for 2.5 h, evaporate, and vacuum dry at 45 ° C to obtain sodium hydantoin salt; add 15 mL N, N-dimethylformamide, 6 ml L 3-Chloropropyltriethoxysilane, react at 95°C for 15h, filter and distill to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer; ② Add 20mL water and 40mL ethanol, adjust the pH value to 5, react at 75°C for 4.5h, evaporate and cool to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin; ③ Add 100mg grafted graphene, add 80mL water and 40mL ethanol, ultrasonicate for 35min, react at 75°C for 7h, centrifuge, remove the supernatant, wash, centrifuge and dry at 45°C to obtain modified graphene; (5) Add 80mL sodium hypochlorite aqueous solution and 150mg modified graphene, stir at room temperature for 2.5h, centrifuge to remove the supernatant, wash three times with deionized water, and dry at 45°C to obtain chlorinated modified graphene.

[0036] Step 4: Add chlorinated modified graphene to polyamide 6 dried at 95°C for 23 hours, mix evenly, shear mix, granulate, and melt extrude to obtain masterbatch; dry for 13 hours, melt spin, and obtain graphene-modified polyamide 6 composite fiber. The mass ratio of polyamide 6 to chlorinated modified graphene is 100:0.1.

[0037] Example 2

[0038] A graphene-modified polyamide 6 composite fiber is prepared by the following method:

[0039] Step 1: Mix 4g of silane coupling agent CG-171 and 60mL of ethanol, add dilute hydrochloric acid, adjust the pH value to 3.8, let stand for 10min, add 100mg of graphene oxide, ultrasonically treat for 1h, react at 70°C for 3h, and centrifuge to dry; add 1.5g of tetraethyl orthosilicate, 15mL of 28% ammonia water, 20mL of ethanol, and 50mL of deionized water, mix well, and react at 20°C for 18h to obtain graphene coated with silica.

[0040] Step 2: ① Heat 100 mg of graphene coated with silica, 6 mL of thionyl chloride and 0.13 mL of pyridine at 60 ° C, stir for 20 hours, distill at atmospheric pressure, wash three times with tetrahydrofuran, and centrifuge; vacuum dry at 25 ° C for 10 hours to obtain chlorinated graphene; ② Take 100 mg of chlorinated graphene and put it into a three-necked flask, add 30 mL of N, N-dimethylacetamide, add 0.18 g of L-glutamic acid, add 0.13 mL of pyridine, stir magnetically at 60 ° C for 11 hours, filter and separate, wash three times with N, N-dimethylacetamide and distilled water respectively, filter, and vacuum freeze-dry at -60 ° C for 20 hours to obtain grafted graphene.

[0041] Step 3: ① Take 1g 5,5-dimethylhydantoin, 2g sodium hydroxide, and 100mL ethanol, stir at room temperature for 2h, evaporate, and vacuum dry at 45°C to obtain sodium hydantoin salt; add 15mL N,N-dimethylformamide, 6mL 3-Chloropropyltriethoxysilane, react at 90°C for 14h, filter and distill to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer; ② Add 20mL water and 40mL ethanol, adjust the pH value to 4.5, react at 70°C for 4h, evaporate and cool to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin; ③ Add 100mg grafted graphene, add 80mL water and 40mL ethanol, ultrasonicate for 30min, react at 70°C for 6h, centrifuge, remove the supernatant, wash, centrifuge and dry at 40°C to obtain modified graphene; (5) Add 80mL sodium hypochlorite aqueous solution and 150mg modified graphene, stir at room temperature for 2h, centrifuge to remove the supernatant, wash three times with deionized water, and dry at 40°C to obtain chlorinated modified graphene.

[0042] Step 4: Add chlorinated modified graphene to polyamide 6 dried at 90°C for 23 hours, mix evenly, shear mix, granulate, and melt extrude to obtain masterbatch; dry for 10 hours, melt spin, and obtain graphene-modified polyamide 6 composite fiber. The mass ratio of polyamide 6 to chlorinated modified graphene is 100:0.08.

[0043] Example 3

[0044] A graphene-modified polyamide 6 composite fiber is prepared by the following method:

[0045] Step 1: Mix 6g of silane coupling agent CG-172 and 60mL of ethanol, add dilute hydrochloric acid, adjust the pH value to 4.1, let stand for 10min, add 100mg of graphene oxide, ultrasonically treat for 2h, react at 80°C for 4h, and centrifuge to dry; add 3g of tetraethyl orthosilicate, 15mL of 28% ammonia water, 20mL of ethanol, and 50mL of deionized water, mix well, and react at 26°C for 20h to obtain graphene coated with silica.

[0046] Step 2: ① Heat 100 mg of graphene coated with silica, 7 mL of thionyl chloride and 0.11 mL of pyridine at 70 ° C, stir for 24 hours, distill at atmospheric pressure, wash three times with tetrahydrofuran, and centrifuge; vacuum dry at 27 ° C for 12 hours to obtain chlorinated graphene; ② Take 100 mg of chlorinated graphene and put it into a three-necked flask, add 30 mL of N, N-dimethylacetamide, add 0.25 g of L-glutamic acid, add 0.12 mL of pyridine, stir magnetically at 70 ° C for 12 hours, filter and separate, wash three times with N, N-dimethylacetamide and distilled water respectively, filter, and vacuum freeze-dry at -60 ° C for 24 hours to obtain grafted graphene.

[0047] Step 3: ① Take 1.5 g 5,5-dimethylhydantoin, 2 g sodium hydroxide, and 100 mL ethanol, stir at room temperature for 3 h, evaporate, and vacuum dry at 50 ° C to obtain sodium hydantoin salt; add 15 mL N, N-dimethylformamide, 7 ml L 3-Chloropropyltriethoxysilane, react at 100°C for 16 hours, filter and distill to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer; ② Add 20mL water and 40mL ethanol, adjust the pH value to 5.5, react at 80°C for 5 hours, evaporate and cool to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin; ③ Add 100mg grafted graphene, add 80mL water and 40mL ethanol, ultrasonicate for 40min, react at 80°C for 8h, centrifuge, remove the supernatant, wash, centrifuge and dry at 50°C to obtain modified graphene; (5) Add 80mL sodium hypochlorite aqueous solution and 150mg modified graphene, stir at room temperature for 3h, centrifuge to remove the supernatant, wash three times with deionized water, and dry at 50°C to obtain chlorinated modified graphene.

[0048] Step 4: Add chlorinated modified graphene to polyamide 6 dried at 95°C for 23 hours, mix evenly, shear mix, granulate, and melt extrude to obtain masterbatch; dry for 10 hours, melt spin, and obtain graphene-modified polyamide 6 composite fiber. The mass ratio of polyamide 6 to chlorinated modified graphene is 100:0.12.

[0049] Example 4

[0050] A graphene-modified polyamide 6 composite fiber is prepared by the following method:

[0051] Step 1: Add 50 mL of concentrated sulfuric acid, heat to 93 ° C, add 7 g of potassium thiosulfate and 7 g of phosphorus pentoxide, stir for 25 minutes, cool to 75 ° C, add 90 g of 325 mesh graphite, react at a constant temperature for 4.5 hours, add deionized water, wash, filter, and dry at 55 ° C for 13 hours to obtain pre-oxidized graphite.

[0052] Step 2: Put the product of step 1 into concentrated sulfuric acid (300 mL) at 0°C, stir evenly, add 42 g potassium permanganate, stir for 25 min, heat at 35°C for 2.5 h, add 500 mL deionized water in an ice bath, stir for 2.5 h, add 1000 mL water, 30 mL hydrogen peroxide, let stand for 22 h, add 1200 mL hydrochloric acid solution, let stand for 22 h, then remove the supernatant, remove impurities, ultrasonicate, freeze, and dry to obtain graphene oxide.

[0053] Step 3: Mix 6g of silane coupling agent CG-172 and 60mL of ethanol, add dilute hydrochloric acid, adjust the pH to 4.2, let stand for 10min, add 100mg of graphene oxide, ultrasonically treat for 1.5h, react at 75°C for 3.5h, and centrifuge to dry; add 1.5g of tetraethyl orthosilicate, 15mL of 28% ammonia water, 20mL of ethanol, and 50mL of deionized water, mix well, and react at 23°C for 19h to obtain graphene coated with silica.

[0054] Step 4: ① Heat 100 mg of graphene coated with silica, 5 mL of thionyl chloride and 0.11 mL of pyridine at 65 ° C, stir for 22 hours, distill at atmospheric pressure, wash three times with tetrahydrofuran, and centrifuge; vacuum dry at 26 ° C for 11 hours to obtain chlorinated graphene; ② Take 100 mg of chlorinated graphene and put it into a three-necked flask, add 30 mL of N, N-dimethylacetamide, add 0.15 g of L-glutamic acid, add 0.11 mL of pyridine, stir magnetically at 60 ° C for 11 hours, filter and separate, wash three times with N, N-dimethylacetamide and distilled water respectively, filter, and vacuum freeze-dry at -55 ° C for 22 hours to obtain grafted graphene.

[0055] Step 5: ① Take 1.2 g 5,5-dimethylhydantoin, 2 g sodium hydroxide, and 100 mL ethanol, stir at room temperature for 2.5 h, evaporate, and vacuum dry at 45 ° C to obtain sodium hydantoin salt; add 15 mL N, N-dimethylformamide, 7 ml L 3-Chloropropyltriethoxysilane, react at 95°C for 15h, filter and distill to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer; ② Add 20mL water and 40mL ethanol, adjust the pH value to 5, react at 75°C for 4.5h, evaporate and cool to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin; ③ Add 100mg grafted graphene, add 80mL water and 40mL ethanol, ultrasonicate for 35min, react at 75°C for 7h, centrifuge, remove the supernatant, wash, centrifuge and dry at 45°C to obtain modified graphene; (5) Add 80mL sodium hypochlorite aqueous solution and 150mg modified graphene, stir at room temperature for 2.5h, centrifuge to remove the supernatant, wash three times with deionized water, and dry at 45°C to obtain chlorinated modified graphene.

[0056] Step 6: Add chlorinated modified graphene to polyamide 6 dried at 95°C for 23 hours, mix evenly, shear mix, granulate, and melt extrude to obtain masterbatch; dry for 13 hours, melt spin, and obtain graphene-modified polyamide 6 composite fiber. The mass ratio of polyamide 6 to chlorinated modified graphene is 100:0.05.

[0057] Example 5

[0058] A graphene-modified polyamide 6 composite fiber is prepared by the following method:

[0059] Step 1: Add 50 mL of concentrated sulfuric acid, heat to 93 ° C, add 7 g of potassium thiosulfate and 7 g of phosphorus pentoxide, stir for 25 minutes, cool to 75 ° C, add 90 g of 325 mesh graphite, react at a constant temperature for 4.5 hours, add deionized water, wash, filter, and dry at 55 ° C for 13 hours to obtain pre-oxidized graphite.

[0060] Step 2: Put the product of step 1 into concentrated sulfuric acid (300 mL) at 0°C, stir evenly, add 42 g potassium permanganate, stir for 25 min, heat at 35°C for 2.5 h, add 500 ml deionized water in an ice bath, stir for 2.5 h, add 1000 mL water, 30 mL hydrogen peroxide, let stand for 22 h, add 1200 mL hydrochloric acid solution, let stand for 22 h, then remove the supernatant, remove impurities, ultrasonicate, freeze, and dry to obtain graphene oxide.

[0061] Step 3: Mix 4g of silane coupling agent CG-151 and 60mL of ethanol, add dilute hydrochloric acid, adjust the pH value to 4, let stand for 10min, add 100mg of graphene oxide, ultrasonically treat for 1.5h, react at 75°C for 3.5h, and centrifuge to dry; add 3g of tetraethyl orthosilicate, 15mL of 28% ammonia water, 20mL of ethanol, and 50mL of deionized water, mix well, and react at 23°C for 19h to obtain graphene coated with silica.

[0062] Step 4: ① Heat 100 mg of graphene coated with silica, 6 mL of thionyl chloride and 0.12 mL of pyridine at 65 ° C, stir for 22 hours, distill at atmospheric pressure, wash three times with tetrahydrofuran, and centrifuge; vacuum dry at 26 ° C for 11 hours to obtain chlorinated graphene; ② Take 100 mg of chlorinated graphene and put it into a three-necked flask, add 30 mL of N, N-dimethylacetamide, add 0.2 g of L-glutamic acid, add 0.11 mL of pyridine, stir magnetically at 60 ° C for 11 hours, filter and separate, wash three times with N, N-dimethylacetamide and distilled water respectively, filter, and vacuum freeze-dry at -55 ° C for 22 hours to obtain grafted graphene.

[0063] Step 5: ① Take 1.3 g 5,5-dimethylhydantoin, 2 g sodium hydroxide, and 100 mL ethanol, stir at room temperature for 2.5 h, evaporate, and vacuum dry at 45 ° C to obtain sodium hydantoin salt; add 15 mL N, N-dimethylformamide, 6 ml L 3-Chloropropyltriethoxysilane, react at 95°C for 15h, filter and distill to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer; ② Add 20mL water and 40mL ethanol, adjust the pH value to 5, react at 75°C for 4.5h, evaporate and cool to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin; ③ Add 100mg grafted graphene, add 80mL water and 40mL ethanol, ultrasonicate for 35min, react at 75°C for 7h, centrifuge, remove the supernatant, wash, centrifuge and dry at 45°C to obtain modified graphene; (5) Add 80mL sodium hypochlorite aqueous solution and 150mg modified graphene, stir at room temperature for 2.5h, centrifuge to remove the supernatant, wash three times with deionized water, and dry at 45°C to obtain chlorinated modified graphene.

[0064] Step 6: Add chlorinated modified graphene to polyamide 6 dried at 95°C for 23 hours, mix evenly, shear mix, granulate, and melt extrude to obtain masterbatch; dry for 13 hours, melt spin, and obtain graphene-modified polyamide 6 composite fiber. The mass ratio of polyamide 6 to chlorinated modified graphene is 100:0.2.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that the graphene coated with silicon dioxide in step 2 is replaced by graphene oxide, that is, the surface of the graphene oxide is not coated with silicon dioxide microspheres, and the rest is the same as Example 1.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that the graphene grafted in step three is replaced by an equal amount of the silica-coated graphene obtained in step one, that is, L-glutamic acid is not grafted onto the graphene, and the rest is the same as Example 1.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that the chlorinated graphene in step 4 is replaced by an equal amount of the grafted graphene obtained in step 2, that is, the graphene is not modified with 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin, and the rest is the same as Example 1.

[0071] The mechanical properties of the graphene-modified polyamide 6 composite fibers obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were tested. The samples were tested according to GB / T14344-2008 to obtain the breaking strength and breaking elongation. The results are shown in Table 1.

[0072] The graphene-modified polyamide 6 composite fibers prepared by Examples 1 to 5 and Comparative Examples 1 to 3 were tested for antibacterial performance according to GB / T20944.3-2008, and Escherichia coli was selected as the test bacteria. The antibacterial performance test results are shown in Table 1.

[0073] Table 1 Test results of graphene-modified polyamide 6 composite fibers in the examples and comparative examples

[0074]

[0075]

[0076] Compared with Comparative Example 1, the breaking strength and breaking elongation of the graphene-modified polyamide 6 composite fibers obtained in Examples 1-5 are significantly improved, indicating that the coating of silica on the graphene surface makes the graphene evenly dispersed in the polyamide 6, thereby increasing the interfacial force and improving the mechanical properties of the graphene-modified polyamide 6 composite fibers.

[0077] Compared with Comparative Example 2, the antibacterial property of the graphene-modified polyamide 6 composite fibers obtained in Examples 1-5 is improved, indicating that the graphene is grafted with L-glutamic acid, which increases the number of graphene reaction active sites and enhances the antibacterial property of the composite fibers.

[0078] Compared with Comparative Example 3, the antibacterial property of the graphene-modified polyamide 6 composite fiber obtained in Examples 1-5 is significantly improved. It can be seen that after the graphene is modified with 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin and chlorinated, the specific surface area of ​​the graphene becomes larger, the adsorption capacity is enhanced, and the free movement of bacteria can be bound; at the same time, the graphene can be chlorinated to release oxidized chloride ions into the cells, oxidize the active groups in the bacteria, inhibit the metabolism of the bacteria, and cause the death of the bacteria, thereby enhancing the antibacterial effect of the composite fiber, so that the antibacterial rate can reach 99%.

[0079] The above specific implementation methods are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing a graphene-modified polyamide 6 composite fiber, characterized in that: The following steps are involved: Adding chlorinated modified graphene to polyamide 6, compounding and molding, and obtaining graphene-modified polyamide 6 composite fibers; The preparation method of the chlorinated modified graphene comprises the following steps: S1: coating graphene oxide with silicon dioxide to obtain graphene oxide coated with silicon dioxide; S2: treating the silicon dioxide-coated graphene oxide with acyl chloride, and then grafting L-glutamic acid to obtain grafted graphene; S3: using 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin to modify the grafted graphene to obtain modified graphene, and chlorinating the modified graphene to obtain chlorinated modified graphene; The specific steps of S2 are as follows: S2-1: adding graphene coated with silicon dioxide, thionyl chloride and pyridine, heating at 60-70° C. to react, performing atmospheric distillation after the reaction, washing and filtering, and drying to obtain chlorinated graphene; S2-2: Add chlorinated graphene, N,N-dimethylacetamide, L-glutamic acid, and pyridine to react, wash and filter, and then dry to obtain grafted graphene, wherein the mass ratio between the chlorinated graphene and the L-glutamic acid is 1: (1 to 2.5).

2. The method for preparing a graphene-modified polyamide 6 composite fiber according to claim 1, characterized in that: The mass ratio of the polyamide 6 to the chlorinated modified graphene is 100:(0.05-0.2).

3. The method for preparing a graphene-modified polyamide 6 composite fiber according to claim 1, characterized in that: The specific steps of S1 are as follows: The silane coupling agent and ethanol are mixed evenly, diluted hydrochloric acid is added dropwise, the pH value is adjusted to 3.8-4.2, the mixture is allowed to stand, graphene oxide is added, and after ultrasonic dispersion, the mixture is placed at 70-80° C. for reaction; after drying, tetraethyl orthosilicate, ammonia water, ethanol, and deionized water are added, and the mixture is reacted at 20-26° C. for 18-20 hours to obtain graphene oxide coated with silicon dioxide, wherein the mass ratio of the silane coupling agent, graphene oxide, and tetraethyl orthosilicate is (4-6):0.1:(1.5-3).

4. The method for preparing a graphene-modified polyamide 6 composite fiber according to claim 3, characterized in that: The silane coupling agent is a vinyl silane coupling agent.

5. The method for preparing a graphene-modified polyamide 6 composite fiber according to claim 1, characterized in that: The specific steps of S3 are as follows: S3-1: adding the grafted graphene, 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin, water and ethanol, dispersing them by ultrasound, and then reacting them at 70-80° C. for 6-8 hours, washing and drying the solid to obtain modified graphene; S3-2: Add sodium hypochlorite aqueous solution to modify graphene, react it at room temperature, wash and dry the solid to obtain chlorinated modified graphene.

6. The method for preparing a graphene-modified polyamide 6 composite fiber according to claim 5, characterized in that: The preparation method of the 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin comprises the following steps: Add 5,5-dimethylhydantoin, sodium hydroxide and ethanol to prepare hydantoin sodium salt; carry out substitution reaction with 3-chloropropyltriethoxysilane in N,N-dimethylformamide solvent to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer; add water and ethanol to the 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin monomer, adjust the pH value to 4.5-5.5, react at 70-80°C for 4-5h, evaporate to obtain 5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin.

7. The method for preparing a graphene-modified polyamide 6 composite fiber according to claim 1, characterized in that: The compounding and molding specifically includes: shear mixing, granulation, melt extrusion to obtain master batches, drying for 10 to 16 hours, and melt spinning.

8. Graphene-modified polyamide 6 composite fiber prepared according to the preparation method according to any one of claims 1 to 7.

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