Preparation method of melt direct spinning far infrared polyamide fiber

Abstract

The invention relates to the technical field of functional fibers, and discloses a melt direct spinning far infrared polyamide fiber preparation method, which comprises: (1) coating SiO2 on the surface of zinc-aluminum hydrotalcite by using a sol-gel method, and calcining to obtain far infrared powder; (2) carrying out surface modification on the far-infrared powder by adopting a surface modifier to obtain modified far-infrared powder; (3) mixing and dispersing the modified far infrared powder and a caprolactam solution, mixing the mixed solution with water and an end-capping reagent, and carrying out a ring-opening reaction; and (4) carrying out condensation polymerization, simultaneously removing small molecules, and directly conveying the removed melt to a spinning line for spinning to obtain the far-infrared polyamide fiber. According to the invention, SiO2 is coated on the surface of hydrotalcite, so that the far infrared absorption range is widened, and the far infrared emissivity of the fiber is improved; and an in-situ polymerization method is adopted, so that the dispersity of the modified far infrared powder is greatly improved, and the spinning stability is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of functional fibers, in particular to a method for preparing melt-direct-spun far-infrared polyamide fibers. Background Art

[0002] Polyamide is a high-strength material that can be used in the fields of fibers and engineering plastics. Polyamide fiber (nylon) is a high-performance synthetic fiber with excellent skin-friendly, strong and wear-resistant properties. Therefore, it is widely used in civilian fibers and industrial fabrics. With the development of economic conditions and the improvement of people's living standards, the requirements for textiles are gradually focused on functionality and aesthetics. Traditional cold-proof and warm clothing is mostly heavy and bloated, with poor aesthetics and comfort. Therefore, the development of efficient and warm textiles has broad market prospects.

[0003] For example, the Chinese patent with publication number CN102776600A discloses a method for preparing high-efficiency infrared polyamide fiber, which adopts the coprecipitation method to prepare magnesium aluminum hydrotalcite, and obtains bimetallic oxide (MMO) by calcination. 2% MMO and polyamide slices are blended and granulated, and a melt spinning process is adopted to obtain far-infrared polyamide fiber. The hydrotalcite prepared by the coprecipitation method has a large particle size, which will affect the mechanical properties of the fiber; the patent introduces far-infrared powder by blending, but blending will make the far-infrared powder have poor dispersion in the polyamide matrix, resulting in spinning instability and performance degradation. The Chinese patent with publication number CN115385573A discloses a method for preparing graphene nylon fiber, which mixes organically modified graphene and nylon slices to obtain graphene nylon slices, and obtains a graphene nylon fiber by melt spinning, so that the nylon fiber has far-infrared performance. However, graphene itself is black, which will affect or limit the dyeing effect of the functional fiber, and it is difficult to obtain all-white and bright-colored textiles. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing melt-spun far-infrared polyamide fibers, wherein the hydrotalcite prepared by the hydrothermal method has a small particle size and reduces fiber breakage. 2Coated on the surface of hydrotalcite, the far-infrared absorption range is widened and the far-infrared emissivity of the fiber is increased. Different from the blending method, the present invention adopts the method of direct addition in the in-situ polymerization process, so that the far-infrared functional powder is more evenly distributed in the melt, and the effect can be achieved with less addition. In addition, traditional polyamide fibers all adopt the chip intermittent spinning process, which needs to go through the polymerization-granulation-extraction-drying-melt blending spinning process. The melt granulation and remelting temperature rise process will have a reverse reaction, generate new small molecules, cause the molecular weight distribution to change, and reduce the spinnability. Not only that, the extraction and drying process requires a lot of energy consumption, which increases the production cost of polyamide fibers. The present invention adopts the melt direct spinning process of polyamide fibers, the melt quality is more stable, the far-infrared functional powder is more evenly dispersed, and the obtained functional fiber performance is better. At the same time, the production process can be greatly simplified, and the fiber production cost can be further reduced.

[0005] The purpose of the present invention is achieved through the following technical solutions: The present invention provides a method for preparing melt-spun far-infrared polyamide fibers, comprising the following steps: (1) SiO was prepared by sol-gel method. 2 Coated on the surface of zinc-aluminum hydrotalcite, and then calcined to obtain far-infrared powder; (2) using a surface modifier to modify the surface of the far-infrared powder to obtain a modified far-infrared powder; (3) mixing and dispersing the modified far-infrared powder and the caprolactam solution, and then mixing the mixture with water and a capping agent to perform a ring-opening reaction; (4) a polycondensation reaction is carried out and small molecules are removed at the same time. After removal, the melt is directly transported to a spinning line for spinning to obtain far-infrared polyamide fibers.

[0006] The present invention adopts a hydrothermal synthesis method to prepare zinc-aluminum hydrotalcite, and controls the particle size at the nanometer level by adjusting the hydrothermal temperature and pH value, thereby avoiding fiber breakage or spinneret blockage caused by excessive particle size. 2 The far-infrared powder is uniformly coated on the surface of zinc-aluminum hydrotalcite and calcined to obtain a far-infrared powder with stronger absorption characteristics in the far-infrared region. The powder is then surface-organically modified and dispersed in molten caprolactam by in-situ polymerization. After high-speed mechanical stirring, water and end-capping agents are added to carry out ring-opening and polycondensation reactions. After removing small molecules, a melt that can be directly spun is obtained. The melt is transported to the spinning process to obtain far-infrared polyamide fibers. This method achieves the synergistic effect of the infrared absorption band through chemical coating, while ensuring the spinnability and functionality of the fiber.

[0007] Far infrared mainly releases heat through radiation, and its wavelength is in the range of 4 to 25 μm, with the strongest radiation energy released near the 9 μm wavelength. 2It has a higher absorption peak at 9μm, which is within the range of the strongest absorption wavelength of the human body. 2 It is nearly transparent in the visible light range and is suitable for the preparation of far-infrared textiles. The material obtained by calcining zinc-aluminum hydrotalcite has a significant far-infrared absorption peak in the range of 6.5 to 25 μm, while SiO 2 There is a strong absorption peak at 9 μm. Simple blending is difficult to effectively broaden the absorption range. 2 Coating on the surface of zinc-aluminum hydrotalcite can achieve two-phase interface coupling and superimpose absorption bands, thereby broadening the far-infrared absorption range and improving the far-infrared emissivity of the fiber.

[0008] Preferably, the zinc-aluminum hydrotalcite is prepared by a hydrothermal synthesis method.

[0009] Preferably, the preparation of the zinc-aluminum hydrotalcite specifically comprises the following steps: ZnCl 2 The solution was stirred and Al(NO 3 ) 3 9H 2 O solution, Na 2 CO 3 solution and NaOH solution, wherein the pH value of the mixed solution is 9-14; the mixed solution is subjected to a hydrothermal synthesis reaction to obtain zinc-aluminum hydrotalcite.

[0010] Preferably, the ZnCl 2 Solution and Al(NO 3 ) 3 9H 2 The amount of O solution added is such that the zinc-aluminum molar ratio is 2-4:1; and the hydrothermal synthesis reaction is hydrothermal crystallization at 100-200° C. for 3-10 hours.

[0011] Preferably, step (1) specifically comprises the following steps: mixing anhydrous ethanol and water, dispersing zinc-aluminum hydrotalcite therein, adjusting the pH to 7-12 to obtain an ethanol-water-zinc-aluminum hydrotalcite mixed solution, adding tetraethyl orthosilicate dropwise therein under stirring conditions at 30-60° C., stirring until it becomes a gel, and then vacuum drying and calcining to obtain a far-infrared powder.

[0012] Preferably, the volume ratio of anhydrous ethanol to water is 2 to 5:1; the mass ratio of the ethanol-water mixed solution obtained by mixing anhydrous ethanol and water to the zinc-aluminum hydrotalcite is 10 to 50:1; the zinc-aluminum molar ratio of the zinc-aluminum hydrotalcite is 2 to 4:1; the amount of ethyl orthosilicate added is SiO 2 The molar ratio of zinc-aluminum hydrotalcite is 2 to 4:1.

[0013] Preferably, the vacuum drying is performed at 50-100° C. for 8-12 h; and the calcination is performed at 300-1000° C. for 2-7 h.

[0014] Calcination causes zinc-aluminum hydrotalcite to lose interlayer water, SiO 2 The particles form nanocrystals.

[0015] Preferably, step (2) specifically comprises the following steps: adding the far-infrared powder into an organic solvent and stirring to obtain a dispersion; stirring and refluxing the dispersion, adding a surface modifier and continuing to stir, and after the reaction is completed, post-treating to obtain a modified far-infrared powder.

[0016] Preferably, the surface modifier is a silane coupling agent; the amount of the surface modifier added is 1 to 5 wt% of the infrared powder; the stirring reflux temperature is 23 to 90° C., and the stirring time is 1 to 5 hours.

[0017] Preferably, in step (3), the amount of the modified far-infrared powder added is 1 to 5 wt% of caprolactam, more preferably, the amount of the modified far-infrared powder added is 3 to 5 wt% of caprolactam; relative to caprolactam, the amount of water added is 1 to 5 wt%, and the amount of the capping agent added is 0.1 to 0.5 wt%.

[0018] Preferably, in step (3), the copolymer component is added together with water and a capping agent to the mixed solution to carry out a ring-opening reaction; the amount of the copolymer component added is 15 to 30 wt % relative to caprolactam; more preferably, the amount of the copolymer component added is 15 to 25 wt %.

[0019] Preferably, in step (3), the copolymer component is one or more of polyamide salt, caprolactone, polycaprolactone and polyester. The polyamide salt is -CO(CH 2 ) a CONH(CH 2 ) b NH- or NH 2 (CH 2 ) y COOH, wherein the value of a is 0-10, the value of b is 1-10, and the value of y is 4-12.

[0020] Preferably, in step (3), the end-capping agent is one or more of adipic acid, acetic acid, terephthalic acid and phthalic acid.

[0021] Preferably, in step (3), the temperature of the ring-opening reaction is 210-250° C., and the reaction pressure is controlled at 0.5-2.5 MPa; the reaction is terminated when the following conditions are met: the number average molecular weight of the obtained melt is 5000-30000.

[0022] Preferably, in step (4), the temperature of the polycondensation reaction is 210-270° C., and the reaction pressure is controlled at -0.1-3 MPa; the reaction is terminated when the following conditions are met: the number average molecular weight of the obtained product is 15,000-50,000, the extractable content is <4%, and the melt relative viscosity is 2.0-4.0.

[0023] Preferably, in step (4), the spinning temperature is 230-270°C.

[0024] Preferably, in step (4), the filament bundle obtained by spinning is side-blown, and the side-blowing temperature is 20-30° C., the air humidity is 60-80%, and the wind speed is 0.3-0.7 m / s.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The hydrotalcite prepared by the hydrothermal method in the present invention has a small particle size, which avoids the problem of fiber breakage or spinneret blockage caused by excessive particle size; SiO 2 Coating on the surface of hydrotalcite will broaden the far-infrared absorption range and improve the far-infrared emissivity of the fiber; (2) The present invention adopts an in-situ polymerization method to introduce the modified far-infrared powder into the polymerization system, so that its dispersibility in the polyamide matrix is ​​greatly improved, the spinning stability is improved, and the function is long-lasting and washable; (3) Most of the traditional far-infrared powders are dark in color, which will affect the dyeing effect of the fiber. The functional powder of the present invention is white, which will not affect the dyeing effect of the functional fiber; (4) The present invention adopts a polyamide melt direct spinning process. The modified melt is directly spun to ensure the relative stability of the polymer molecular weight, thereby improving the spinnability and reducing the production cost of the fiber. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described below with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0027] The preparation of melt-spun far-infrared polyamide fiber in the present invention comprises the following steps: (1) Preparation of zinc-aluminum hydrotalcite: ZnCl 2 The solution was stirred and Al(NO 3 ) 3 9H 2 O solution, Na 2 CO 3solution and NaOH solution, the pH value of the mixed solution is 9-14, the molar ratio of zinc to aluminum is 2-4:1, the above solution is stirred for 0.5-3 hours, and then a hydrothermal synthesis reaction is carried out, and crystallization is carried out at a temperature of 100-200°C for 3-10 hours. After the hydrothermal reaction is completed, the solution is washed three times, filtered, dried, and ground to obtain zinc-aluminum hydrotalcite.

[0028] (2) preparing far-infrared powder: anhydrous ethanol and deionized water are mixed in a volume ratio of 2 to 5:1, zinc-aluminum hydrotalcite is dispersed therein, the pH is adjusted to 7 to 12, and the mass ratio of the ethanol-water mixed solution to the zinc-aluminum hydrotalcite is 10 to 50:1, to obtain an ethanol-water-zinc-aluminum hydrotalcite mixed solution; and tetraethyl orthosilicate (TEOS) is slowly added dropwise to the ethanol-water-zinc-aluminum hydrotalcite mixed solution under stirring at 30 to 60° C., so that SiO 2 The molar ratio of zinc-aluminum hydrotalcite is 2-4:1, and the mixture is stirred until it is in gel form. The wet gel is vacuum dried at 50-100°C for 8-12 hours, and then calcined at 300-1000°C and kept warm for 2-7 hours to obtain far-infrared powder.

[0029] (3) Preparation of modified far-infrared powder: placing the far-infrared powder in an isopropanol solution, stirring for 0.5 to 2 hours to obtain a dispersion; stirring and refluxing the dispersion at 23 to 90° C., adding 0.1 to 6 wt % of a surface modifier relative to the far-infrared powder, stirring for 1 to 5 hours, and cooling to room temperature to obtain a suspension; filtering and washing the suspension, and drying it at 50 to 80° C. for 8 to 12 hours to obtain a modified far-infrared powder.

[0030] (4) Ring opening: The modified far-infrared powder is mixed with the caprolactam solution in a batching tank, the amount of far-infrared powder added is 1-5wt% relative to the caprolactam, and the shear stirring treatment is 0.5-2h, so that the powder is evenly dispersed in the caprolactam solution; then 15-30wt% of the copolymer component (optional addition) relative to the caprolactam, 1-5wt% of water and 0.1-0.5wt% of the end-capping agent are added, the mixing temperature is 80-140°C, and the mixing is stirred for 10-60min. The obtained mixture is heated to carry out a ring-opening reaction, the ring-opening temperature is 210-250°C, the reaction pressure is controlled at 0.5-2.5MPa, the reaction is terminated, and the number average molecular weight of the obtained melt is 5000-30000.

[0031] (5) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 210 to 270° C. The reaction pressure is controlled at -0.1 to 3 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 15,000 to 50,000, the extractable content is less than 4%, and the melt relative viscosity is 2.0 to 4.0.

[0032] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 230-270°C, a side-blowing temperature of 20-30°C, an air humidity of 60-80%, and a wind speed of 0.3-0.7 m / s to obtain far-infrared polyamide fibers.

[0033] In a specific embodiment of the present invention, the surface modifier is a silane coupling agent.

[0034] In a specific embodiment of the present invention, the copolymer component is one or more of polyamide salt, caprolactone and / or its polymer, polyester polycondensate. Polyamide salt is -CO(CH 2 ) a CONH(CH 2 ) b NH- or NH 2 (CH 2 ) y COOH, wherein the value of a is 0-10, the value of b is 1-10, and the value of y is 4-12.

[0035] In a specific embodiment of the present invention, the end-capping agent is one or more of adipic acid, acetic acid, terephthalic acid, and phthalic acid.

[0036] Example 1 (1) Preparation of zinc-aluminum hydrotalcite: ZnCl 2 The solution was stirred and Al(NO 3 ) 3 9H 2 O solution, Na 2 CO 3 solution and NaOH solution, the pH value of the mixed solution is 12, the molar ratio of zinc to aluminum is 2:1, the above solution is stirred for 0.5h, and then a hydrothermal synthesis reaction is carried out, and crystallization is carried out at a temperature of 160°C for 6h. After the hydrothermal reaction is completed, the solution is washed three times, filtered, dried, and ground to obtain zinc-aluminum hydrotalcite.

[0037] (2) Preparation of far-infrared powder: Anhydrous ethanol and deionized water were mixed in a volume ratio of 4:1, zinc-aluminum hydrotalcite was dispersed therein, the mass ratio of ethanol-water mixed solution to zinc-aluminum hydrotalcite was 16.5:1, and the pH was adjusted to 9 to obtain an ethanol-water-zinc-aluminum hydrotalcite mixed solution; TEOS was slowly added dropwise under stirring at 35°C to make SiO 2 The molar ratio of zinc-aluminum hydrotalcite is 2:1, and the mixture is stirred until it becomes gel-like. The wet gel is dried at 80℃ in vacuum for 12h, and then calcined at 700℃ for 4h to obtain far-infrared powder.

[0038] (3) Preparation of modified far-infrared powder: The far-infrared powder is placed in an isopropanol solution and stirred for 0.5 h to obtain a dispersion; the dispersion is stirred and refluxed at 35° C., 3 wt % of an aminosilane coupling agent (KH550) relative to the far-infrared powder is added, stirred for 1 h, and cooled to room temperature to obtain a suspension; the suspension is filtered and washed, and then dried at 80° C. for 8 h to obtain a modified far-infrared powder.

[0039] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 1wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 15wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19280.

[0040] (5) Polycondensation: The ring-opened mixture was fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure was controlled at 1.2 MPa. Small molecules were removed under negative pressure to terminate the reaction. The number average molecular weight of the obtained product was 32360, the extractable content was <4%, and the melt relative viscosity was 2.18.

[0041] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0042] Example 2 The difference from Example 1 is that the added amount of the modified far-infrared powder is 3 wt % relative to the caprolactam.

[0043] Steps (1)-(3) are the same as in Example 1.

[0044] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 3wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 15wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, the reaction is terminated, and the number average molecular weight of the obtained melt is 19000.

[0045] (5) Polycondensation: The ring-opened mixture was fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure was controlled at 1.2 MPa. Small molecules were removed under negative pressure to terminate the reaction. The number average molecular weight of the obtained product was 33652, the extractable content was <4%, and the melt relative viscosity was 2.20.

[0046] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0047] Example 3 The difference from Example 1 is that the added amount of the modified far-infrared powder is 5 wt % relative to the caprolactam.

[0048] Steps (1)-(3) are the same as in Example 1.

[0049] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 5wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 15wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19576.

[0050] (5) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure to terminate the reaction. The number average molecular weight of the obtained product is 37520, the extractable content is less than 4%, and the relative viscosity of the melt is 2.5.

[0051] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0052] Example 4 The difference from Example 2 is that the added amount of polyamide 66 salt is 30 wt % relative to caprolactam.

[0053] Steps (1)-(3) are the same as in Example 1.

[0054] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 3wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 30wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19352.

[0055] (5) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 32872, the extractable content is less than 4%, and the melt relative viscosity is 2.2.

[0056] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0057] Example 5 The difference from Example 2 is that no polyamide 66 salt is added.

[0058] Steps (1)-(3) are the same as in Example 1.

[0059] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 3wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19765.

[0060] (5) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 35420, the extractable content is less than 4%, and the relative viscosity of the melt is 2.4.

[0061] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0062] Example 6 The difference from Example 2 is that the molar ratio of zinc to aluminum is 4:1, and no polyamide 66 salt is added.

[0063] (1) Preparation of zinc-aluminum hydrotalcite: ZnCl 2 The solution was stirred and Al(NO 3 ) 3 9H 2 O solution, Na 2 CO 3 solution and NaOH solution, the pH value of the mixed solution is 12, the molar ratio of zinc to aluminum is 4:1, the above solution is stirred for 0.5h, and then a hydrothermal synthesis reaction is carried out, and crystallization is carried out at a temperature of 160°C for 6h. After the hydrothermal reaction is completed, the solution is washed three times, filtered, dried, and ground to obtain zinc-aluminum hydrotalcite.

[0064] (2) Preparation of far-infrared powder: Anhydrous ethanol and deionized water were mixed in a volume ratio of 4:1, zinc-aluminum hydrotalcite was dispersed therein, the mass ratio of ethanol-water mixed solution to zinc-aluminum hydrotalcite was 16.5:1, and the pH was adjusted to 9 to obtain an ethanol-water-zinc-aluminum hydrotalcite mixed solution; TEOS was slowly added dropwise under stirring at 35°C to make SiO 2 The molar ratio of zinc-aluminum hydrotalcite is 2:1, and the mixture is stirred until it becomes gel-like. The wet gel is dried at 80℃ in vacuum for 12h, and then calcined at 700℃ for 4h to obtain far-infrared powder.

[0065] (3) Preparation of modified far-infrared powder: The far-infrared powder is placed in an isopropanol solution and stirred for 0.5 h to obtain a dispersion; the dispersion is stirred and refluxed at 35° C., 3 wt % of an aminosilane coupling agent (KH550) relative to the far-infrared powder is added, stirred for 1 h, and cooled to room temperature to obtain a suspension; the suspension is filtered and washed, and then dried at 80° C. for 8 h to obtain a modified far-infrared powder.

[0066] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 3wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19357.

[0067] (5) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure to terminate the reaction. The number average molecular weight of the obtained product is 34780, the extractable content is less than 4%, and the melt relative viscosity is 2.3.

[0068] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0069] Comparative Example 1 The difference from Example 1 is that no modified far-infrared powder is added.

[0070] (1) Ring opening: Add the caprolactam solution into a batching tank, then add 15 wt% of polyamide 66 salt, 2.5 wt% of water and 0.3 wt% of terephthalic acid relative to the caprolactam, the mixing temperature is 120°C, and the mixture is stirred for 60 minutes. The obtained mixture is heated to carry out a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2 MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19274.

[0071] (2) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 32873, the extractable content is less than 4%, and the melt relative viscosity is 2.2.

[0072] (3) Spinning: The removed melt is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain polyamide fibers.

[0073] Comparative Example 2 The difference from Example 2 is that unmodified far-infrared powder is added.

[0074] Steps (1)-(2) are the same as in Example 1.

[0075] (3) Ring opening: Far infrared powder and caprolactam solution are mixed in a batching tank, the amount of far infrared powder added is 3wt% relative to caprolactam, and shear stirring is performed for 0.5h; then 15wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid are added relative to caprolactam, the mixing temperature is 120°C, and stirring is performed for 60min. The obtained mixture is heated for ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19783.

[0076] (4) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 34760, the extractable content is less than 4%, and the melt relative viscosity is 2.3.

[0077] (5) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260°C, a side-blowing temperature of 30°C, an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0078] Comparative Example 3 The difference from Example 1 is that the modified far-infrared powder and polyamide 66 salt are not added.

[0079] (1) Ring opening: Add the caprolactam solution into a batching tank, then add 2.5 wt% of water and 0.3 wt% of terephthalic acid relative to the caprolactam, the mixing temperature is 120°C, and the mixture is stirred for 60 minutes. The resulting mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2 MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 18923.

[0080] (2) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 36752, the extractable content is less than 4%, and the melt relative viscosity is 2.4.

[0081] (3) Spinning: The removed melt is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain polyamide fibers.

[0082] Comparative Example 4 The difference from Example 2 is that small molecules are not removed during the polycondensation reaction.

[0083] Steps (1)-(3) are the same as in Example 1.

[0084] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 3wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 15wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19826.

[0085] (5) Polycondensation: The ring-opened mixture was fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure was controlled at 1.2 MPa. The small molecules were not removed and the reaction was terminated. The number average molecular weight of the obtained product was 31872, the extractable content was >9%, and the relative viscosity of the melt was 2.1.

[0086] (6) Spinning: The melt is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0087] Comparative Example 5 The difference from Example 2 is that the far-infrared powder only contains zinc-aluminum hydrotalcite.

[0088] (1) Preparation of zinc-aluminum hydrotalcite: ZnCl 2 The solution was stirred and Al(NO 3 ) 3 9H 2 O solution, Na 2 CO 3 solution and NaOH solution, the pH value of the mixed solution is 12, the molar ratio of zinc to aluminum is 2:1, the above solution is stirred for 0.5h, and then a hydrothermal synthesis reaction is carried out, and crystallization is carried out at a temperature of 160°C for 6h. After the hydrothermal reaction is completed, the solution is washed three times, filtered, dried, and ground to obtain zinc-aluminum hydrotalcite.

[0089] (2) Preparation of far-infrared powder: calcining the obtained zinc-aluminum hydrotalcite at 700°C and keeping it at this temperature for 4 hours.

[0090] (3) Modified far-infrared powder: The far-infrared powder is placed in an isopropanol solution and stirred for 0.5 h to obtain a dispersion; the dispersion is stirred and refluxed at 35° C., 3 wt % of an aminosilane coupling agent (KH550) is added, stirred for 1 h, and cooled to room temperature to obtain a suspension; the suspension is filtered and washed, and then dried at 80° C. for 8 h to obtain a modified far-infrared powder.

[0091] (4) Ring opening: The modified far-infrared powder was mixed with the caprolactam solution in a batching tank, the addition amount was 3wt% of the caprolactam, and the shear stirring treatment was performed for 0.5h; then polyamide 66 salt accounting for 15wt% of the caprolactam, 2.5wt% of water and 0.3wt% of terephthalic acid were added, the mixing temperature was 120°C, and the mixing was stirred for 60min. The obtained mixture was heated for ring opening reaction, the ring opening temperature was 220°C, the reaction pressure was controlled at 1.2MPa, and the reaction was terminated. The number average molecular weight of the obtained melt was 19373.

[0092] (5) Polycondensation: The ring-opened mixture was fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure was controlled at 1.2 MPa. The small molecules were not removed and the reaction was terminated. The number average molecular weight of the obtained product was 34172, the extractable content was less than 4%, and the relative viscosity of the melt was 2.2.

[0093] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0094] Comparative Example 6 The difference from Example 2 is that the far-infrared powder contains only SiO 2 .

[0095] Preparation of far-infrared powder: Anhydrous ethanol and deionized water were mixed in a volume ratio of 4:1, and the pH was adjusted to 9 to obtain an ethanol-water mixture; TEOS was slowly added dropwise to the ethanol-water mixture under stirring at 35°C and stirred until it became a gel. The wet gel was dried at 80°C in a vacuum for 12 hours, and then calcined at 700°C for 4 hours to obtain SiO 2 Powder.

[0096] (2) Preparation of modified far-infrared powder: SiO 2 The powder was placed in an isopropanol solution and stirred for 0.5 h to obtain a dispersion. The dispersion was stirred and refluxed at 35 °C and a relative amount of SiO 2 3 wt% of aminosilane coupling agent (KH550) was added to the powder, stirred for 1 hour, and then cooled to room temperature to obtain a suspension; the suspension was filtered, washed, and dried at 80° C. for 8 hours to obtain a modified far-infrared powder.

[0097] (3) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 3wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 15wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19532.

[0098] (4) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 33782, the extractable content is less than 4%, and the melt relative viscosity is 2.2.

[0099] (5) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260°C, a side-blowing temperature of 30°C, an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0100] Comparative Example 7 The difference from Example 2 is that the far infrared powder is zinc aluminum hydrotalcite and SiO 2 Blending.

[0101] (1) Preparation of zinc-aluminum hydrotalcite: ZnCl 2 The solution was stirred and Al(NO 3 ) 3 9H 2 O solution, Na 2 CO 3 solution and NaOH solution, the pH value of the mixed solution is 12, the molar ratio of zinc to aluminum is 2:1, the above solution is stirred for 0.5h, and then a hydrothermal synthesis reaction is carried out, and crystallization is carried out at a temperature of 160°C for 6h. After the hydrothermal reaction is completed, the solution is washed three times, filtered, dried, and ground to obtain zinc-aluminum hydrotalcite, which is then calcined at 700°C and kept warm for 4h.

[0102] (3) Preparation of silica powder: Anhydrous ethanol and deionized water were mixed in a volume ratio of 4:1, and the pH was adjusted to 9 to obtain an ethanol-water mixture; TEOS was slowly added dropwise to the ethanol-water mixture under stirring at 35°C and stirred until it became a gel. The wet gel was dried at 80°C in vacuum for 12 hours, and then calcined at 700°C for 4 hours to obtain SiO 2 Powder.

[0103] (3) Modified far-infrared powder: zinc-aluminum hydrotalcite and SiO 2The powder is placed in an isopropanol solution to make SiO 2 The mass ratio of zinc-aluminum hydrotalcite is 2:1, and after stirring for 0.5h, a dispersion is obtained; the dispersion is stirred and refluxed at 35°C, 3wt% of aminosilane coupling agent (KH550) is added, and after stirring for 1h, it is cooled to room temperature to obtain a suspension; the suspension is filtered and washed, and then dried at 80°C for 8h to obtain a modified far-infrared powder.

[0104] (4) Ring opening: The modified far-infrared powder was mixed with the caprolactam solution in a batching tank, the addition amount was 3wt% of the caprolactam, and the shear stirring treatment was performed for 0.5h; then polyamide 66 salt, 15wt% of the caprolactam, 2.5wt% of water and 0.3wt% of terephthalic acid were added, the mixing temperature was 120°C, and the mixing was stirred for 60min. The obtained mixture was heated for ring opening reaction, the ring opening temperature was 220°C, the reaction pressure was controlled at 1.2MPa, and the reaction was terminated. The number average molecular weight of the obtained melt was 19620.

[0105] (5) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 32524, the extractable content is less than 4%, and the relative viscosity of the melt is 2.2.

[0106] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0107] Comparative Example 8 The difference from Example 2 is that the SiO 2 Too much wrapping.

[0108] (1) Preparation of zinc-aluminum hydrotalcite: ZnCl 2 The solution was stirred and Al(NO 3 ) 3 9H 2 O solution, Na 2 CO 3 solution and NaOH solution, the pH value of the mixed solution is 12, the molar ratio of zinc to aluminum is 2:1, the above solution is stirred for 0.5h, and then a hydrothermal synthesis reaction is carried out, and crystallization is carried out at a temperature of 160°C for 6h. After the hydrothermal reaction is completed, the solution is washed three times, filtered, dried, and ground to obtain zinc-aluminum hydrotalcite.

[0109] (2) Preparation of far-infrared powder: Anhydrous ethanol and deionized water were mixed in a volume ratio of 4:1, zinc-aluminum hydrotalcite was dispersed therein, the mass ratio of ethanol-water mixed solution to zinc-aluminum hydrotalcite was 16.5:1, and the pH was adjusted to 9 to obtain an ethanol-water-zinc-aluminum hydrotalcite mixed solution; TEOS was slowly added dropwise under stirring at 35°C to make SiO 2 The molar ratio of zinc-aluminum hydrotalcite is 5:1, and the mixture is stirred until it becomes gel-like. The wet gel is dried at 80℃ in vacuum for 12h, and then calcined at 700℃ and kept at this temperature for 4h to obtain far-infrared powder.

[0110] (3) Preparation of modified far-infrared powder: The far-infrared powder is placed in an isopropanol solution and stirred for 0.5 h to obtain a dispersion; the dispersion is stirred and refluxed at 35° C., 3 wt % of an aminosilane coupling agent (KH550) relative to the far-infrared powder is added, stirred for 1 h, and cooled to room temperature to obtain a suspension; the suspension is filtered and washed, and then dried at 80° C. for 8 h to obtain a modified far-infrared powder.

[0111] (4) Ring opening: The modified far-infrared powder and the caprolactam solution are mixed in a batching tank, the amount of the modified far-infrared powder added is 3wt% relative to the caprolactam, and the shear stirring treatment is 0.5h; then 15wt% of polyamide 66 salt, 2.5wt% of water and 0.3wt% of terephthalic acid relative to the caprolactam are added, the mixing temperature is 120°C, and the mixing is stirred for 60min. The obtained mixture is heated to perform a ring opening reaction, the ring opening temperature is 220°C, the reaction pressure is controlled at 1.2MPa, and the reaction is terminated. The number average molecular weight of the obtained melt is 19672.

[0112] (5) Polycondensation: The ring-opened mixture is fed into a polycondensation reactor to carry out a polycondensation reaction at a temperature of 230° C. The reaction pressure is controlled at 1.2 MPa. Small molecules are removed under negative pressure conditions to terminate the reaction. The number average molecular weight of the obtained product is 36937, the extractable content is less than 4%, and the melt relative viscosity is 2.3.

[0113] (6) Spinning: The melt after removal is directly transported to a spinning box for spinning at a spinning temperature of 260° C., a side-blowing temperature of 30° C., an air humidity of 60%, and a wind speed of 0.7 m / s to obtain far-infrared polyamide fibers.

[0114] Table 1 As shown in Table 1, the present invention adopts in-situ polymerization to add far-infrared powder, and the prepared polyamide fiber has good far-infrared performance. As shown in Examples 1-3, the more far-infrared powder is added, the polyamide fiber will obtain better far-infrared performance, but adding too much far-infrared powder will be unfavorable for the mechanical properties of polyamide fiber. As shown in Examples 2, 4 and 5, after adding copolymer components (polyamide 66 salt), the crystallinity decreases and causes the strength to decrease, but the elongation at break increases, making the fiber softer. In addition, adding too much copolymer components (polyamide 66 salt) not only causes the strength to decrease significantly, but also causes the far-infrared performance to be affected. As shown in Examples 2, 5 and 6, the larger the zinc-aluminum molar ratio, that is, the larger the molar ratio of zinc, the larger the particle size of hydrotalcite increases, which can reduce far-infrared emissivity and mechanical properties.

[0115] It can be seen from Comparative Examples 1 and 3 that without adding far-infrared powder for treatment, the far-infrared emissivity of the fiber is low, and the related textiles cannot play a warming role. It can be seen from Comparative Example 2 that without modifying the surface of the far-infrared powder, the interfacial force between the far-infrared powder and the polyamide phase becomes weak, and the compatibility and dispersibility in the polyamide matrix are poor, so the far-infrared performance and mechanical properties of the polyamide fiber are also affected. It can be seen from Comparative Example 4 that the polyamide melt is not subjected to the removal of small molecules, the extractable content is high, and spinning is impossible. It can be seen from Comparative Examples 5-8 that only zinc-aluminum hydrotalcite or SiO 2 The far-infrared emissivity of the powder is lower than that of SiO 2 Far infrared powder coated on zinc aluminum hydrotalcite, and zinc aluminum hydrotalcite and SiO 2 Simple physical blending will lead to weak interfacial bonding, resulting in the absorption peaks only showing independent superposition rather than synergistic broadening. Therefore, the far-infrared performance of polyamide fiber is still low. 2 Too much coating will result in only reflecting SiO 2 The infrared absorption peak of polyamide fiber will be reduced, and the far-infrared performance of polyamide fiber will also deteriorate.

[0116] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing melt-spun far-infrared polyamide fiber, characterized in that: The steps include: (1) SiO2 is coated on the surface of zinc-aluminum hydrotalcite by a sol-gel method, and then calcined to obtain far-infrared powder; (2) using a surface modifier to modify the surface of the far-infrared powder to obtain a modified far-infrared powder; (3) mixing and dispersing the modified far-infrared powder and the caprolactam solution, and then mixing the mixture with water and a capping agent to carry out a ring-opening reaction; (4) A polycondensation reaction is carried out and small molecules are removed at the same time. After removal, the melt is directly transported to the spinning line for spinning to obtain far-infrared polyamide fibers.

2. The method for preparing melt-spun far-infrared polyamide fiber according to claim 1, characterized in that: Step (1) specifically comprises the following steps: mixing anhydrous ethanol and water, dispersing zinc-aluminum hydrotalcite therein, adjusting the pH to 7-12 to obtain an ethanol-water-zinc-aluminum hydrotalcite mixed solution, adding tetraethyl orthosilicate dropwise thereto under stirring at 30-60° C., stirring until it is in a gel state, and then vacuum drying and calcining to obtain a far-infrared powder.

3. The method for preparing melt-spun far-infrared polyamide fiber according to claim 2, characterized in that: The volume ratio of anhydrous ethanol to water is 2-5:1; the mass ratio of the ethanol-water mixed liquid obtained by mixing anhydrous ethanol and water to the zinc-aluminum hydrotalcite is 10-50:1; the zinc-aluminum molar ratio of the zinc-aluminum hydrotalcite is 2-4:1; and the amount of ethyl orthosilicate added is such that the molar ratio of SiO2 to the zinc-aluminum hydrotalcite in the ethanol-water-zinc-aluminum hydrotalcite mixed liquid is 2-4:

1.

4. The method for preparing melt-spun far-infrared polyamide fiber according to claim 2 or 3, characterized in that: The vacuum drying is performed at 50-100° C. for 8-12 hours; and the calcination is performed at 300-1000° C. for 2-7 hours.

5. The method for preparing melt-spun far-infrared polyamide fiber according to claim 1, characterized in that: In step (2), the surface modifier is a silane coupling agent; the amount of the surface modifier added is 1-5wt% of the infrared powder.

6. The method for preparing melt-spun far-infrared polyamide fiber according to claim 1, characterized in that: In step (3), the amount of the modified far-infrared powder added is 1-5wt% of caprolactam; relative to caprolactam, the amount of water added is 1-5wt%, and the amount of the end-capping agent added is 0.1-0.5wt%.

7. The method for preparing melt-spun far-infrared polyamide fiber according to claim 1, 5 or 6, characterized in that: In step (3), a copolymer component is added together with water and a capping agent to mix with the mixed solution to carry out a ring-opening reaction; the copolymer component is one or more of polyamide salt, caprolactone, polycaprolactone and polyester.

8. The method for preparing melt-spun far-infrared polyamide fiber according to claim 1, characterized in that: In step (3), the temperature of the ring-opening reaction is 210-250° C., and the reaction pressure is controlled at 0.5-2.5 MPa; the reaction is terminated when the following conditions are met: the number average molecular weight of the obtained melt is 5000-30000.

9. The method for preparing melt-spun far-infrared polyamide fiber according to claim 1 or 8, characterized in that: In step (4), the temperature of the polycondensation reaction is 210-270° C., and the reaction pressure is controlled at -0.1-3 MPa; the reaction is terminated when the following conditions are met: the number average molecular weight of the obtained product is 15,000-50,000, the extractable content is <4%, and the relative viscosity of the melt is 2.0-4.

0.

10. The method for preparing melt-spun far-infrared polyamide fiber according to claim 1 or 8, characterized in that: In step (4), the spinning temperature is 230-270°C.

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