Preparation method of ultra-high molecular weight polyamide 6 fiber

Abstract

The invention relates to the technical field of polymer preparation, and particularly discloses a preparation method of an ultra-high molecular weight polyamide 6 fiber, which comprises the following steps: carrying out cold stretching on a primary gel fiber, extracting, naturally airing, carrying out hot stretching for 1-2 times, and carrying out heat setting at 160 DEG C to obtain the ultra-high molecular weight polyamide 6 fiber. According to the device, N-ethyl o / p-toluene sulfonamide is adopted as a good solvent of ultra-high molecular weight polyamide 6, a traditional polyamide 6 complexing and dissolving method is not adopted, under the condition that a decomplexing technology is not needed, the ultra-high molecular weight polyamide 6 gel fiber is endowed with high stretchability, formation of a high orientation structure of the fiber is facilitated, and the tensile strength of the ultra-high molecular weight polyamide 6 gel fiber is improved. The prepared fiber has the strength of 5.98-7.11 cN / dtex and the modulus of 232.70-420.54 cN / dtex, and can be used in the field of industrial textiles such as tire cords, conveyor belts, conveyor belts, fishing nets, ropes and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer preparation technology, and more specifically, to a method for preparing ultra-high molecular weight polyamide 6 fibers. Background Technology

[0002] Currently, polyamide fibers refer to a class of synthetic fibers whose molecular backbone is linked by amide bonds, including aliphatic polyamides and aromatic polyamides. Aliphatic polyamide fibers, also known as nylon in my country, are the earliest industrially produced synthetic fibers in the world. Although there are many types of polyamide fibers, polyamide 6 and nylon 66 are still the most prevalent, accounting for over 95% of polyamide fiber production. Polyamide 6 is a linear long-chain macromolecule composed of many repeating structural units linked by amide bonds, exhibiting a fully extended planar tortuous structure in crystals. Adjacent amide groups between molecular chains can form hydrogen bonds in a directional manner, resulting in tight intermolecular bonding and endowing the fiber with excellent mechanical properties. The most prominent advantage of polyamide 6 fiber is its superior abrasion resistance, ranking first among similar fibers. Secondly, it possesses excellent elasticity, with an elastic recovery rate comparable to wool. It is also lightweight; among commercially available synthetic fibers, its density is only higher than polypropylene and lower than polyester. Therefore, polyamide 6 can be processed into fine, soft, and smooth fibers for weaving into beautiful and durable fabrics. Furthermore, like polyester, it is corrosion-resistant, insect-proof, and mildew-proof. The disadvantages of polyamide 6 fiber, besides poor light resistance, include poor shape retention compared to polyester, resulting in less crisp fabrics. In industrial applications, polyamide 6 fiber is mainly used to make tire cords, conveyor belts, fishing nets, and ropes. However, due to its low modulus, polyamide 6 is prone to deformation during use. Therefore, improving the strength and modulus of polyamide 6 fiber will help broaden its application areas, necessitating improvement. Thus, a method for preparing ultra-high molecular weight polyamide 6 fiber is proposed. Summary of the Invention

[0003] In view of the above-mentioned technical problems in related technologies, the present invention provides a method for preparing ultra-high molecular weight polyamide 6 fiber, which can solve the above problems.

[0004] To achieve the above-mentioned technical objectives, the technical solution of the present invention is implemented as follows: A method for preparing ultra-high molecular weight polyamide 6 fiber includes the following steps: S1: Add an appropriate amount of caprolactam to the reactor, heat to 90℃ to melt for 5 minutes, evacuate for 20 minutes, add a certain amount of sodium hydroxide as a catalyst, continue to stir under vacuum for 40 minutes, then add an appropriate amount of inert aliphatic hydrocarbon as a dispersant and isocyanate as an activator, and continue to react under stirring at 130℃~150℃ for 60 minutes~100 minutes to obtain ultra-high molecular weight polyamide 6, filter, dry and grind for later use.

[0005] S2: Take an appropriate amount of ultra-high molecular weight polyamide 6 and extract it in boiling water for 2 hours to allow low molecular weight substances to diffuse out of the raw material and dissolve in hot water, thereby reducing the oligomer content and meeting the requirements for spinning. After the ultra-high molecular weight polyamide 6 is extracted by boiling water, let it air dry naturally and then place it in a vacuum drum oven at 120°C for 10 hours to dry it until its moisture content drops to below 0.06%. S3: Add an appropriate amount of N-ethyl o- / p-toluenesulfonamide, dried ultra-high molecular weight polyamide 6 and an appropriate amount of antioxidant to the dissolving vessel. Under the protection of nitrogen, stir and heat to 100℃ and stabilize for 4 hours to allow the ultra-high molecular weight polyamide 6 to fully swell. Gradually heat to 210℃ to form a macroscopically uniform and stable gel solution. Let the gel solution stand to degas for 0.5 hours to obtain an ultra-high molecular weight polyamide 6 gel spinning solution with a mass fraction of 20%~35%. S4: After the ultra-high molecular weight polyamide 6 gel spinning solution is extruded through the spinning assembly, it is sequentially cooled in an air bath and a coagulation bath at 10~20℃ to obtain nascent gel fibers. At room temperature, the nascent gel fibers are stretched 8~12 times and then extracted in anhydrous ethanol for 10h to remove N-ethyl o- / p-toluenesulfonamide. S5: The extracted nascent gel fiber is air-dried naturally, then placed on a contact-type hot roller stretching and setting machine at 120~140℃ for another stretching of 1~2 times, and then heat-set at 160℃ to obtain ultra-high molecular weight polyamide 6 fiber.

[0006] Furthermore, the ultra-high molecular weight polyamide 6 in step S1 is obtained by anionic slurry polymerization, with a relative viscosity of 20~28, and the oligomer content is reduced to 1.5%~2% after boiling water extraction.

[0007] Furthermore, the antioxidant in step S3 is 1076 antioxidant, and the amount of antioxidant added is 0.05% of the mass of ultra-high molecular weight polyamide 6.

[0008] Furthermore, in step S4, the length of the air bath is 10~20cm, the diameter of the spinneret of the spinning assembly is 0.2~0.3mm, and the aspect ratio is 10~20. The aspect ratio is the ratio of the length of the spinneret to the diameter of the spinneret.

[0009] The beneficial effects of this invention are as follows: This invention uses N-ethyl-o- / p-toluenesulfonamide as a good solvent for ultra-high molecular weight polyamide 6, instead of the traditional polyamide 6 complexation and dissolution method. Under the condition that no decomplexation process is required, ultra-high molecular weight polyamide 6 gel fibers are endowed with high stretchability, which is conducive to the formation of highly oriented fiber structure. The prepared fibers have a strength of 5.98-7.11 cN / dtex and a modulus of 232.70-420.54 cN / dtex, and can be used in industrial textile fields such as tire cord, conveyor belt, transport belt, fishing net, rope and cable. Detailed Implementation

[0010] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art are within the scope of protection of the present invention.

[0011] As shown below, a method for preparing ultra-high molecular weight polyamide 6 fiber is disclosed according to the present invention, comprising:

[0012] Example 1: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The extracted ultra-high molecular weight polyamide 6 was then air-dried naturally and then dried in a vacuum drum oven at 120°C for 10 hours until its moisture content was reduced to below 0.06%. 800g of N-ethyl o- / p-toluenesulfonamide, 200g of extracted and dried ultra-high molecular weight polyamide 6, and 0.1g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to allow the ultra-high molecular weight polyamide 6 to fully swell. The temperature was then gradually raised to 210°C. A macroscopically uniform spinning solution was prepared. After the gel solution was allowed to stand for degassing for 0.5 hours, it was extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. Nascent gel fibers were then wound up. The nascent gel fibers were cold-stretched 8-12 times at room temperature and then extracted in anhydrous ethanol for 10 hours to remove N-ethyl o- / p-toluenesulfonamide. The extracted nascent gel fibers were air-dried and then stretched again 1-2 times at 120-140°C. Heat setting was then completed at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0013] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 20%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 8 times; hot stretching temperature: 120℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0014] Example 2: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The extracted ultra-high molecular weight polyamide 6 was then air-dried naturally and placed in a vacuum drum oven at 120°C for 10 hours to reduce its moisture content to below 0.06%. 750g of N-ethyl o- / p-toluenesulfonamide, 250g of extracted and dried ultra-high molecular weight polyamide 6, and 0.125g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to allow the ultra-high molecular weight polyamide 6 to fully swell. The temperature was then gradually raised to 210°C. A macroscopically uniform spinning solution was prepared. After the gel solution was allowed to stand for degassing for 0.5 hours, the gel solution was extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. Nascent gel fibers were then wound up. The nascent gel fibers were cold-stretched 8-12 times at room temperature and then extracted in anhydrous ethanol for 10 hours to remove N-ethyl-o- and p-toluenesulfonamides. The extracted nascent gel fibers were air-dried and then stretched again 1-2 times at 120-140°C. Heat setting was then completed at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0015] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 25%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 8 times; hot stretching temperature: 120℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0016] Example 3: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The ultra-high molecular weight polyamide 6 after boiling water extraction was naturally air-dried, and then placed in a vacuum drum oven at 120°C for 10 hours to dry its moisture content to below 0.06%. 700g of N-ethyl o- / p-toluenesulfonamide, 300g of extracted and dried ultra-high molecular weight polyamide 6, and 0.15g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to swell. The temperature was then gradually raised to 210°C to prepare a macroscopically homogeneous solution. After the spinning solution is allowed to stand for 0.5 hours to degas, the gel solution is extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. The resulting nascent gel fibers are then wound up and cold-stretched 8-12 times at room temperature. They are then extracted in anhydrous ethanol for 10 hours to remove N-ethyl o- / p-toluenesulfonamide. The extracted nascent gel fibers are then air-dried and stretched again 1-2 times at 120-140°C. Finally, they are heat-set at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0017] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 30%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 8 times; hot stretching temperature: 120℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0018] Example 4: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The ultra-high molecular weight polyamide 6 after boiling water extraction was naturally air-dried, and then placed in a vacuum drum oven at 120°C for 10 hours to dry its moisture content to below 0.06%. 650g of N-ethyl o- / p-toluenesulfonamide, 350g of extracted and dried ultra-high molecular weight polyamide 6, and 0.175g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to swell. The temperature was then gradually raised to 210°C to prepare a macroscopically homogeneous solution. After the spinning solution is allowed to stand for 0.5 hours to degas, the gel solution is extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. The resulting nascent gel fibers are then wound up and cold-stretched 8-12 times at room temperature. They are then extracted in anhydrous ethanol for 10 hours to remove N-ethyl o- / p-toluenesulfonamide. The extracted nascent gel fibers are then air-dried and stretched again 1-2 times at 120-140°C. Finally, they are heat-set at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0019] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 35%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 8 times; hot stretching temperature: 120℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0020] Example 5: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The ultra-high molecular weight polyamide 6 after boiling water extraction was naturally air-dried, and then placed in a vacuum drum oven at 120°C for 10 hours to reduce its moisture content to below 0.06%. 700g of N-ethyl o- / p-toluenesulfonamide, 300g of extracted and dried ultra-high molecular weight polyamide 6, and 0.15g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to swell. The temperature was then gradually raised to 210°C to form a macroscopically homogeneous solution. After the spinning solution is allowed to stand for 0.5 hours to degas, the gel solution is extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. The resulting nascent gel fibers are then wound up and cold-stretched 8-12 times at room temperature. They are then extracted in anhydrous ethanol for 10 hours to remove N-ethyl o- / p-toluenesulfonamide. The extracted nascent gel fibers are then air-dried and stretched again 1-2 times at 120-140°C. Finally, they are heat-set at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0021] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 35%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 8 times; hot stretching temperature: 120℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0022] Example 6: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The ultra-high molecular weight polyamide 6 after boiling water extraction was naturally air-dried, and then placed in a vacuum drum oven at 120°C for 10 hours to dry its moisture content to below 0.06%. 700g of N-ethyl o- / p-toluenesulfonamide, 300g of extracted and dried ultra-high molecular weight polyamide 6, and 0.15g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to swell. The temperature was then gradually raised to 210°C to prepare a macroscopically uniform spinning solution. After the filament solution is allowed to stand for 0.5 hours to degas, the gel solution is extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. The resulting nascent gel fibers are then wound up and cold-stretched 8-12 times at room temperature. They are then extracted in anhydrous ethanol for 10 hours to remove N-ethyl o- / p-toluenesulfonamide. The extracted nascent gel fibers are then air-dried and stretched again 1-2 times at 120-140°C. Finally, they are heat-set at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0023] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 30%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 10 times; hot stretching temperature: 120℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0024] Example 7: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The ultra-high molecular weight polyamide 6 after boiling water extraction was naturally air-dried, and then placed in a vacuum drum oven at 120°C for 10 hours to dry its moisture content to below 0.06%. 700g of N-ethyl o- / p-toluenesulfonamide, 300g of extracted and dried ultra-high molecular weight polyamide 6, and 0.15g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to swell. The temperature was then gradually raised to 210°C to form a macroscopically homogeneous solution. After the spinning solution is allowed to stand for 0.5 hours to degas, the gel solution is extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. The resulting nascent gel fibers are then wound up and cold-stretched 8-12 times at room temperature. They are then extracted in anhydrous ethanol for 10 hours to remove N-ethyl o- / p-toluenesulfonamide. The extracted nascent gel fibers are then air-dried and stretched again 1-2 times at 120-140°C. Finally, they are heat-set at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0025] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 30%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 10 times; hot stretching temperature: 130℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0026] Example 8: An appropriate amount of ultra-high molecular weight polyamide 6 was extracted in boiling water for 2 hours. The ultra-high molecular weight polyamide 6 after boiling water extraction was naturally air-dried, and then placed in a vacuum drum oven at 120°C for 10 hours to dry its moisture content to below 0.06%. 700g of N-ethyl o- / p-toluenesulfonamide, 300g of extracted and dried ultra-high molecular weight polyamide 6, and 0.15g of antioxidant 1076 were added to a dissolving vessel. The temperature was slowly raised to 100°C and stirred for 4 hours to swell. The temperature was then gradually raised to 210°C to form a macroscopically homogeneous solution. After the spinning solution is allowed to stand for 0.5 hours to degas, the gel solution is extruded through the spinneret and then rapidly cooled in an air bath and a coagulation bath at 10-20°C. The resulting nascent gel fibers are then wound up and cold-stretched 8-12 times at room temperature. They are then extracted in anhydrous ethanol for 10 hours to remove N-ethyl o- / p-toluenesulfonamide. The extracted nascent gel fibers are then air-dried and stretched again 1-2 times at 120-140°C. Finally, they are heat-set at 160°C to obtain ultra-high molecular weight polyamide 6 fibers.

[0027] The fiber forming process parameters are as follows: Ultra-high molecular weight polyamide 6 mass fraction: 30%; gel spinning speed: 20m / min; spinning temperature: 210℃; spinning pressure: 0.4MPa; coagulation bath temperature: 10℃; cold stretching ratio: 10 times; hot stretching temperature: 140℃; hot stretching ratio: 1.2 times; heat setting temperature: 160℃.

[0028] The measured results of the strength and modulus of the ultra-high molecular weight polyamide 6 fiber described in the examples are listed in Table 1. As can be seen from the measured data in Table 1, the breaking strength of the ultra-high molecular weight polyamide 6 fiber prepared by the method of this invention is much higher than that of conventional nylon fiber (3.53-5.29 cN / dtex), and it has practical application value.

[0029] Table 1 Strength and modulus of ultra-high molecular weight polyamide 6 fiber The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing ultra-high molecular weight polyamide 6 fiber, characterized in that, Includes the following steps: S1: Take an appropriate amount of ultra-high molecular weight polyamide 6 and extract it in boiling water for 2 hours. After extraction in boiling water, the ultra-high molecular weight polyamide 6 is naturally dried and then placed in a vacuum drum oven at 120°C for 10 hours to reduce its moisture content to below 0.06%. S2: Add an appropriate amount of N-ethyl o- / p-toluenesulfonamide, dried ultra-high molecular weight polyamide 6 and an appropriate amount of antioxidant to the dissolving vessel. Under the protection of nitrogen, stir and heat to 100℃ and stabilize for 4 hours to allow the ultra-high molecular weight polyamide 6 to fully swell. Gradually heat to 210℃ to form a macroscopically uniform and stable gel solution. Let the gel solution stand to degas for 0.5 hours to obtain an ultra-high molecular weight polyamide 6 gel spinning solution with a mass fraction of 20%~35%. S3: After the ultra-high molecular weight polyamide 6 gel spinning solution is extruded through the spinning assembly, it is sequentially cooled in an air bath and a coagulation bath at 10~20℃, and then wound to obtain nascent gel fibers. At room temperature, the nascent gel fibers are stretched 8~12 times, and then extracted in anhydrous ethanol for 10h to remove N-ethyl o- / p-toluenesulfonamide. S4: The extracted nascent gel fiber is air-dried naturally, then stretched again by 1 to 2 times at 120~140℃, and heat-set at 160℃ to obtain ultra-high molecular weight polyamide 6 fiber.

2. The method for preparing ultra-high molecular weight polyamide 6 fiber according to claim 1, characterized in that, The ultra-high molecular weight polyamide 6 in step S1 is obtained by anionic slurry polymerization, with a relative viscosity of 12~28. After boiling water extraction, the oligomer content is reduced to 1.5%~2%.

3. The method for preparing ultra-high molecular weight polyamide 6 fiber according to claim 1, characterized in that, The antioxidant in step S2 is 1076 antioxidant, and the amount of antioxidant added is 0.05% of the mass of ultra-high molecular weight polyamide 6.

4. The method for preparing ultra-high molecular weight polyamide 6 fiber according to claim 1, characterized in that, The length of the air bath in step S3 is 10~20cm, the diameter of the spinneret hole of the spinning assembly is 0.2~0.3mm, and the aspect ratio is 10~20. The aspect ratio is the ratio of the length of the spinneret hole to the diameter of the spinneret hole.

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