Far-infrared heating para-aramid fiber and preparation method thereof

Abstract

The present invention relates to the field of fiber technology, and in particular to a far-infrared heating para-aramid fiber and a preparation method thereof. The preparation method comprises the following steps: preparing Mg-Al LDHs by a co-precipitation method using MgCl2·6H2O and ALCl3·9H2O, then calcining and grinding at high temperature to obtain a metal oxide Mg-AL MMO; reacting the Mg-AL MMO with Na2CO3, washing, and drying to obtain RLDH; uniformly mixing the RLDH with an ultraviolet-absorbing metal oxide and silicon oxide to obtain a composite powder; organically modifying the composite powder with a silane coupling agent to obtain a far-infrared nano-additive; uniformly mixing the far-infrared nano-additive with PPTA, and uniformly dispersing the mixture in concentrated sulfuric acid to obtain a modified spinning solution; and obtaining the far-infrared heating para-aramid fiber by a dry-jet wet spinning process. The para-aramid fiber has a far-infrared heating function and can broaden the application range of the para-aramid fiber.

Description

Technical Field

[0001] The invention relates to far-infrared heating para-aramid fiber and a preparation method thereof, belonging to the technical field of fibers. Background Art

[0002] With the continuous development of the textile industry and the continuous improvement of people's living standards, the demand for textile performance is also increasing. In particular, in the fields of healthcare, sportswear, outdoor equipment, etc., there is a strong demand for textiles with functions such as warmth retention, moisture absorption and perspiration removal, and antibacterial and deodorizing properties. Among them, infrared light absorbing heat-generating fibers, as a type of functional fiber with significant warmth retention properties, have attracted extensive attention and research due to their unique properties.

[0003] Infrared-absorbing heating fibers are a type of fiber material that absorbs infrared light and converts it into heat, providing warmth. While traditional thermal insulation materials primarily store and reflect heat, infrared-absorbing heating fibers directly absorb infrared light and convert it into heat, providing a more efficient and direct way to keep warm.

[0004] The full name of para-aramid fiber is polyphenylene phthalate. It is known as one of the world's three major high-performance fibers along with carbon fiber and ultra-high molecular weight polyethylene fiber. It has low relative density, high strength, high modulus, high temperature resistance, corrosion resistance, and insulation. It is widely used in military, aerospace, electronics, transportation, construction, medical and other fields.

[0005] At present, the infrared light absorbing heating fibers on the market are mainly targeted at fibers such as nylon, acrylic polymers and polyester. There is relatively little research on para-aramid far-infrared thermal fibers. The raw polymer viscosity of para-aramid fibers is relatively large. When far-infrared additives are introduced into para-aramid fibers, it is easy to disperse unevenly, resulting in substandard performance of para-aramid fibers. Therefore, para-aramid fibers are not easy to be far-infrared modified.

[0006] With the continuous advancement of technology and the diversification of consumer needs, the market demand for far-infrared heating fibers will continue to grow. Para-aramid fibers are widely used in various fields. Therefore, research and development of para-aramid fibers with far-infrared heating properties not only has important academic value but also has broad market prospects and application potential. Based on this, the present invention provides a method for preparing far-infrared heating para-aramid fibers. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention provides a far-infrared heating para-aramid fiber and a preparation method thereof. The para-aramid fiber has a far-infrared heating function, which enables the para-aramid fabric to have heat preservation and antibacterial and deodorizing effects, thereby broadening the application scope of the para-aramid fiber and improving the market application rate of the para-aramid.

[0008] The technical solution of the present invention to solve the above technical problems is as follows: a preparation method of far-infrared heating para-aramid fiber, the preparation method is:

[0009] Mg-Al LDHs were prepared by co-precipitation of S1, MgCl2·6H2O, and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was reacted with Na2CO3, washed, and dried to obtain RLDH. The RLDH was then uniformly mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified with a silane coupling agent to obtain a far-infrared nano-additive.

[0010] S2. After mixing the far-infrared nano additive and PPTA, the mixture is evenly dispersed in concentrated sulfuric acid to obtain a modified spinning solution, and the far-infrared heating para-aramid fiber is obtained by a dry-jet wet spinning process.

[0011] Furthermore, in step S1, the molar ratio of MgCl2·6H2O to ALCl3·9H2O is 0.9:(0.9-1.2).

[0012] Furthermore, in step S1, the high-temperature calcination temperature is 450-600°C.

[0013] Furthermore, in step S1, the ultraviolet absorbing metal oxide is at least one of zinc oxide and zirconium oxide; and the mass ratio of the RLDH, ultraviolet absorbing metal oxide and silicon oxide is (0.5-1):1:0.2.

[0014] Furthermore, in step S1, the silane coupling agent is KH-570 silane coupling agent;

[0015] The mass ratio of the silane coupling agent to the composite powder is 3:(3.5-4.5).

[0016] Furthermore, in step S1, the particle size of the far-infrared nano additive is not greater than 5 nm.

[0017] Furthermore, in step S2, the mass ratio of the far-infrared nano additive to PPTA is 1:(45-50).

[0018] Furthermore, in step S2, the far-infrared nano additive is mixed with PPTA to obtain far-infrared PPTA powder, and the mass ratio of the far-infrared PPTA powder to the concentrated sulfuric acid is 1:(4.0-4.5);

[0019] The temperature condition when the far-infrared PPTA powder is uniformly dispersed in the concentrated sulfuric acid is 90-92°C.

[0020] Furthermore, in step S2, the modified spinning solution is degassed and then ejected through a spinneret into a coagulation bath, and then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber;

[0021] The drying and setting temperature is 300-350°C.

[0022] The present invention also discloses a far-infrared heating para-aramid fiber, which is prepared according to the preparation method of the present invention;

[0023] The far-infrared temperature rise of the far-infrared heat-generating para-aramid fiber is not less than 2.0° C., and the far-infrared emissivity is not less than 0.83%.

[0024] The beneficial effects of the present invention are:

[0025] The preparation method of the present invention adopts advanced co-precipitation method, high-temperature calcination, silane coupling agent modification and other processes, which ensure the high quality and uniform dispersion of far-infrared nano additives, and improve production efficiency and product quality; the para-aramid fiber of the present invention has a far-infrared heating function, enhances the heat shrinkage and temperature tolerance of the fiber, and makes the para-aramid fabric have heat preservation and antibacterial and deodorizing effects, which can broaden the application scope of the para-aramid fiber and improve the market application rate of the para-aramid fiber; the far-infrared temperature rise of the far-infrared heating para-aramid fiber of the present invention is not less than 2.0°C, and the far-infrared emissivity is not less than 0.83%. The use of the far-infrared heating para-aramid fiber of the present invention can significantly improve the heat resistance and strength of the fabric.

[0026] In the preparation method of the present invention, Mg-ALLDHs are prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O, followed by high-temperature calcination and grinding to obtain metal oxide Mg-AL MMO. Mg-AL MMO is reacted with Na2CO3, and then washed and dried to obtain RLDH. The RLDH is uniformly mixed with ultraviolet absorbing metal oxide and silicon oxide to obtain composite powder, and the composite powder is organically modified using a silane coupling agent to obtain a far-infrared nano additive. The appropriate dosage ratio of MgCl2·6H2O and ALCl3·9H2O, as well as the subsequent modification of the appropriate amount of silane coupling agent, make the prepared far-infrared nano-additive more conducive to uniform mixing with PPTA and also facilitate uniform dispersion in the spinning solution; in addition, in the preparation method, the temperature control when the far-infrared PPTA powder is uniformly dispersed in the concentrated sulfuric acid, as well as the control of the drying and shaping temperature during the spinning process, ensure that the final far-infrared heating para-aramid fiber has excellent far-infrared heating performance while maintaining high strength and modulus properties, with its strength reaching above 22.5 cN / dtex and its modulus not less than 100 GPa. DETAILED DESCRIPTION

[0027] The present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used are only for describing specific embodiments and are not intended to limit the present invention.

[0029] A preparation method of far-infrared heating para-aramid fiber, the preparation method comprising:

[0030] Mg-Al LDHs were prepared by co-precipitation of S1, MgCl2·6H2O, and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was reacted with Na2CO3, washed, and dried to obtain RLDH. The RLDH was then uniformly mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified with a silane coupling agent to obtain a far-infrared nano-additive.

[0031] S2. After mixing the far-infrared nano additive and PPTA, the mixture is evenly dispersed in concentrated sulfuric acid to obtain a modified spinning solution, and the far-infrared heating para-aramid fiber is obtained by a dry-jet wet spinning process.

[0032] More specifically, in step S1, the co-precipitation method is as follows: after uniformly mixing MgCl2·6H2O and ALCl3·9H2O, slowly dropwise adding a 10% sodium carbonate aqueous solution to the system under stirring, controlling the temperature within the system to 75°C, wherein the molar ratio of sodium carbonate to the total amount of MgCl2·6H2O and ALCl3·9H2O is 0.9:(0.9-1.2). After the dropwise addition is complete, the constant temperature is maintained for 2.5 hours. Mg-Al LDHs are then filtered, washed, and dried to obtain the mixture.

[0033] More specifically, Mg-Al MMO (mixed metal oxide) and Na2CO3 aqueous solution mainly undergo precipitation reaction and ion exchange reaction. Mg-Al MMO will have a small amount of Mg in the aqueous solution. 2+ 、Al 3+ Dissolution. CO3 in Na2CO3 aqueous solution 2- Will be with Mg 2+ Combined to form MgCO3 precipitate,

[0034] The reaction principle of Mg-AL MMO and Na2CO3 is that MgO and Al2O3 are partially hydrated in water to form metal hydroxides. 2+ 、Al 3+ (or AlO2 - ) and CO3 in solution 2- The specific operation method is as follows: Mg-Al MMO is added to a Na2CO3 aqueous solution (the mass concentration of the Na2CO3 aqueous solution is 10%) and stirred at 75°C for at least 24 hours. The mixture is then filtered, washed with water, washed with alcohol (washed with ethanol), and dried to obtain RLDH (the moisture content does not exceed 0.001%).

[0035] More specifically, the specific operation method for organically modifying the composite powder using a silane coupling agent to obtain a far-infrared nano additive is as follows: a mixed solution of ethanol and water is prepared in a volume ratio of 1:9, a certain amount of composite powder and silane coupling agent are weighed (relative to the mass of the composite powder), and the composite powder is added to the prepared mixed solution of ethanol and water. The mixture is ultrasonically treated using an ultrasonic dispersion device to uniformly disperse the composite powder in the mixed solution for 20 minutes, and the pre-weighed silane coupling agent is slowly added. The ultrasonic treatment is continued for 10 minutes to ensure that the silane coupling agent and the composite powder are fully contacted and mixed. The above mixture is transferred to a constant temperature magnetic stirrer and stirred at 75°C for 1.5 hours. After the reaction is completed, the mixture is filtered and washed with ethanol several times to remove unreacted coupling agent and other impurities. The washed powder is dried in a vacuum drying oven at 75°C for 24 hours to obtain the modified far-infrared nano additive.

[0036] Specifically, in step S1, the molar ratio of MgCl2·6H2O to ALCl3·9H2O is 0.9:(0.9-1.2).

[0037] Preferably, in step S1, the molar ratio of MgCl2·6H2O to ALCl3·9H2O is 0.9:1.

[0038] Specifically, in step S1, the high-temperature calcination temperature is 450-600°C.

[0039] Preferably, in step S1, the temperature of the high-temperature calcination is 500°C.

[0040] Specifically, in step S1, the ultraviolet absorbing metal oxide is at least one of zinc oxide and zirconium oxide; and the mass ratio of the RLDH, ultraviolet absorbing metal oxide and silicon oxide is (0.5-1):1:0.2.

[0041] Preferably, the mass ratio of the RLDH, ultraviolet absorbing metal oxide and silicon oxide is 0.6:1:0.2; the mixing of RLDH with ultraviolet absorbing metal oxide and silicon oxide can broaden the infrared radiation band of the far-infrared nano additive.

[0042] Specifically, in step S1, the silane coupling agent is KH-570 silane coupling agent; the composite powder is organically modified using the KH-570 silane coupling agent to obtain highly dispersed far-infrared nano-scale powder.

[0043] The mass ratio of the silane coupling agent to the composite powder is 3:(3.5-4.5).

[0044] Preferably, the mass ratio of the silane coupling agent to the composite powder is 3:4.

[0045] Specifically, in step S1, the particle size of the far-infrared nano additive is not greater than 5 nm.

[0046] Specifically, in step S2, the mass ratio of the far-infrared nano additive to PPTA is 1:(45-50).

[0047] Preferably, in step S2, the mass ratio of the far-infrared nano additive to PPTA is 1:49.

[0048] More specifically, in step S2, the far-infrared nano additive and the PPTA powder are mixed, including: adding the far-infrared nano additive and PPTA into a blender and blending them evenly to obtain far-infrared PPTA powder. During the blending process, nitrogen protection is required to prevent air from entering.

[0049] Specifically, in step S2, the far-infrared nano additive is mixed with PPTA to obtain far-infrared PPTA powder, and the mass ratio of the far-infrared PPTA powder to the concentrated sulfuric acid is 1:(4.0-4.5);

[0050] Preferably, the mass ratio of the far-infrared PPTA powder to the concentrated sulfuric acid is 1:4.2.

[0051] The temperature condition when the far-infrared PPTA powder is uniformly dispersed in the concentrated sulfuric acid is 90-92°C.

[0052] More specifically, in step S2, the specific operation method of uniformly dispersing the far-infrared PPTA powder in concentrated sulfuric acid to obtain the modified spinning solution is as follows: adding the far-infrared PPTA powder and concentrated sulfuric acid in proportion to a screw dissolver for dispersion to obtain the modified spinning solution. During the dispersion process, the temperature of each zone in the screw dissolver and the box temperature are 90°C in the first zone, 91°C in the second zone, 91°C in the third zone, 91°C in the fourth zone, 91°C in the fifth zone, and 92°C in the sixth zone.

[0053] More specifically, the PPTA used in the embodiment of the present invention is poly(p-phenylene terephthalamide) with a density of 1.45 g / cm 3 ; The concentrated sulfuric acid used in the embodiment of the present invention is concentrated sulfuric acid with a mass concentration of not less than 99%.

[0054] Specifically, in step S2, the modified spinning solution is degassed and then ejected through a spinneret into a coagulation bath, and then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber;

[0055] The drying and setting temperature is 300-350°C.

[0056] More specifically, the coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; and the draft ratio is 6-8.

[0057] The present invention also discloses a far-infrared heating para-aramid fiber, which is prepared according to the preparation method of the present invention;

[0058] The far-infrared temperature rise of the far-infrared heat-generating para-aramid fiber is not less than 2.0° C., and the far-infrared emissivity is not less than 0.83%.

[0059] Example 1

[0060] S1. Preparation of far-infrared nano-additives:

[0061] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zinc oxide and silicon oxide to obtain a composite powder. This composite powder was then organically modified using KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0062] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:0.9;

[0063] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0064] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0065] The mass ratio of silane coupling agent to composite powder is 3:4;

[0066] S2. Preparation of far-infrared heating para-aramid fiber:

[0067] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0068] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0069] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0070] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0071] The drying and setting temperature is 320°C.

[0072] Example 2

[0073] S1. Preparation of far-infrared nano-additives:

[0074] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zirconium oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified with KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0075] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0076] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0077] The mass ratio of RLDH, zirconia, and silica is 0.5:1:0.2;

[0078] The mass ratio of silane coupling agent to composite powder is 3:3.5;

[0079] S2. Preparation of far-infrared heating para-aramid fiber:

[0080] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0081] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:50;

[0082] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0083] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0084] The drying and setting temperature is 300°C.

[0085] Example 3

[0086] S1. Preparation of far-infrared nano-additives:

[0087] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zirconium oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified with KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0088] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.2;

[0089] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0090] The mass ratio of RLDH, zirconia, and silicon oxide is 1:1:0.2;

[0091] The mass ratio of silane coupling agent to composite powder is 3:4.5;

[0092] S2. Preparation of far-infrared heating para-aramid fiber:

[0093] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0094] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:45;

[0095] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0096] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0097] The drying and setting temperature is 350°C.

[0098] Example 4

[0099] S1. Preparation of far-infrared nano-additives:

[0100] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zinc oxide and silicon oxide to obtain a composite powder. This composite powder was then organically modified using KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0101] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0102] The high temperature calcination temperature is 450℃ and the calcination time is 5min;

[0103] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0104] The mass ratio of silane coupling agent to composite powder is 3:4;

[0105] S2. Preparation of far-infrared heating para-aramid fiber:

[0106] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0107] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0108] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0109] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0110] The drying and setting temperature is 330°C.

[0111] Example 5

[0112] S1. Preparation of far-infrared nano-additives:

[0113] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zinc oxide and silicon oxide to obtain a composite powder. This composite powder was then organically modified using KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0114] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0115] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0116] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0117] The mass ratio of silane coupling agent to composite powder is 3:4;

[0118] S2. Preparation of far-infrared heating para-aramid fiber:

[0119] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0120] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0121] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0122] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0123] The drying and setting temperature is 330°C.

[0124] Example 6

[0125] S1. Preparation of far-infrared nano-additives:

[0126] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zirconium oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified with KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0127] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0128] The high temperature calcination temperature is 600℃ and the calcination time is 5min;

[0129] The mass ratio of RLDH, zirconia, and silicon oxide is 0.6:1:0.2;

[0130] The mass ratio of silane coupling agent to composite powder is 3:4;

[0131] S2. Preparation of far-infrared heating para-aramid fiber:

[0132] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0133] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0134] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.0;

[0135] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0136] The drying and setting temperature is 340°C.

[0137] Example 7

[0138] S1. Preparation of far-infrared nano-additives:

[0139] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zirconium oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified with KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0140] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0141] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0142] The mass ratio of RLDH, zirconia, and silicon oxide is 0.8:1:0.2;

[0143] The mass ratio of silane coupling agent to composite powder is 3:4;

[0144] S2. Preparation of far-infrared heating para-aramid fiber:

[0145] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0146] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0147] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.5;

[0148] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0149] The drying and setting temperature is 340°C.

[0150] Comparative Example 1

[0151] Unmodified PPTA was used to spin para-aramid fibers. The specific preparation process is as follows:

[0152] PPTA and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones in the screw dissolver and the box body were 85°C, 85°C, 85°C, 85°C, 85°C, and 85°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0153] Among them, the mass ratio of PPTA to concentrated sulfuric acid is 1:4.2;

[0154] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0155] The drying and setting temperature is 280°C.

[0156] Comparative Example 2

[0157] Far-infrared heat-generating para-aramid fiber was prepared by the same method as in Example 5, except that Mg-AL MMO in this comparative example 2 was not stirred in the sodium carbonate solution. The specific preparation process is as follows:

[0158] S1. Preparation of far-infrared nano-additives:

[0159] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O, followed by high-temperature calcination and grinding to obtain the metal oxide Mg-AL MMO. Mg-ALMMO was then mixed with zinc oxide and silicon oxide to obtain a composite powder, which was then organically modified with KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0160] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0161] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0162] The mass ratio of Mg-AL MMO, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0163] The mass ratio of silane coupling agent to composite powder is 3:4;

[0164] S2. Preparation of far-infrared heating para-aramid fiber:

[0165] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0166] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0167] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0168] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0169] The drying and setting temperature is 330°C.

[0170] Comparative Example 3

[0171] Far-infrared heat-generating para-aramid fiber was prepared by the same method as in Example 5, except that no silane coupling agent was added for organic modification in step S1 of this comparative example 3. The specific preparation process is as follows:

[0172] S1. Preparation of far-infrared nano-additives:

[0173] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. Mg-AL MMO was then calcined and ground to obtain the metal oxide. Mg-AL MMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then uniformly mixed with zinc oxide and silicon oxide to obtain a composite powder.

[0174] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0175] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0176] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0177] S2. Preparation of far-infrared heating para-aramid fiber:

[0178] The composite powder and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0179] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0180] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0181] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0182] The drying and setting temperature is 330°C.

[0183] Comparative Example 4

[0184] Far-infrared heat-generating para-aramid fiber was prepared using the same method as in Example 5, except that the amount of MgCl2·6H2O was reduced in step S1 of this comparative example 4, and the molar ratio of MgCl2·6H2O to ALCl3·9H2O was 0.5:1. The specific preparation process is as follows:

[0185] S1. Preparation of far-infrared nano-additives:

[0186] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified using a KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0187] The molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.5:1.0;

[0188] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0189] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0190] The mass ratio of silane coupling agent to composite powder is 3:4;

[0191] S2. Preparation of far-infrared heating para-aramid fiber:

[0192] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0193] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0194] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0195] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0196] The drying and setting temperature is 330°C.

[0197] Comparative Example 5

[0198] Far-infrared heat-generating para-aramid fiber was prepared using the same method as in Example 5, except that the amount of MgCl2·6H2O was increased in step S1 of this comparative example 5, and the molar ratio of MgCl2·6H2O to ALCl3·9H2O was 1.2:1. The specific preparation process is as follows:

[0199] S1. Preparation of far-infrared nano-additives:

[0200] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified using a KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0201] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 1.2:1.0;

[0202] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0203] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0204] The mass ratio of silane coupling agent to composite powder is 3:4;

[0205] S2. Preparation of far-infrared heating para-aramid fiber:

[0206] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0207] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0208] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0209] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0210] The drying and setting temperature is 330°C.

[0211] Comparative Example 6

[0212] The far-infrared heat-generating para-aramid fiber was prepared by the same method as in Example 5, except that, in step S2 of this comparative example 6, the dispersion temperature of the far-infrared PPTA powder and concentrated sulfuric acid in the screw dissolver was reduced. The specific preparation process is as follows:

[0213] S1. Preparation of far-infrared nano-additives:

[0214] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified using a KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0215] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0216] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0217] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0218] The mass ratio of silane coupling agent to composite powder is 3:4;

[0219] S2. Preparation of far-infrared heating para-aramid fiber:

[0220] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 60°C, 61°C, 61°C, 61°C, 61°C, and 62°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0221] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0222] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0223] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0224] The drying and setting temperature is 330°C.

[0225] Comparative Example 7

[0226] The far-infrared heat-generating para-aramid fiber was prepared by the same method as in Example 5, except that, in step S2 of this comparative example 7, the addition ratio of the far-infrared nano additive was increased. The specific preparation process is as follows:

[0227] S1. Preparation of far-infrared nano-additives:

[0228] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified using a KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0229] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0230] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0231] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0232] The mass ratio of silane coupling agent to composite powder is 3:4;

[0233] S2. Preparation of far-infrared heating para-aramid fiber:

[0234] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0235] Among them, the mass ratio of far-infrared nano additives to PPTA is 2:49;

[0236] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0237] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0238] The drying and setting temperature is 330°C.

[0239] Comparative Example 8

[0240] The same method as in Example 5 was used to prepare far-infrared heat-generating para-aramid fiber, except that in step S2 of this comparative example 8, the drying and setting temperature was 280°C, which was different from the drying and setting temperature of conventional para-aramid fiber. The specific preparation process was as follows:

[0241] S1. Preparation of far-infrared nano-additives:

[0242] Mg-Al LDHs were prepared by co-precipitation of MgCl2·6H2O and ALCl3·9H2O. The metal oxide Mg-AL MMO was then calcined and ground at high temperature. The Mg-ALMMO was stirred in a Na2CO3 solution for 24 hours, filtered, washed, and dried (100°C) to obtain RLDH. The RLDH was then mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified using a KH-570 silane coupling agent to obtain a far-infrared nano-additive.

[0243] Among them, the molar ratio of MgCl2·6H2O and ALCl3·9H2O is 0.9:1.0;

[0244] The high temperature calcination temperature is 500℃ and the calcination time is 5min;

[0245] The mass ratio of RLDH, zinc oxide, and silicon oxide is 0.6:1:0.2;

[0246] The mass ratio of silane coupling agent to composite powder is 3:4;

[0247] S2. Preparation of far-infrared heating para-aramid fiber:

[0248] Far-infrared nano-additives and PPTA were added to a blender and uniformly blended to obtain far-infrared PPTA powder. The far-infrared PPTA powder and concentrated sulfuric acid were added to a screw dissolver for dispersion to obtain a modified spinning solution. During the dispersion process, the temperatures of the various zones within the screw dissolver and the box body were 90°C, 91°C, 91°C, 91°C, 91°C, and 92°C, respectively. The modified spinning solution was deaerated and then ejected through a spinneret into a coagulation bath. The solution was then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber.

[0249] Among them, the mass ratio of far-infrared nano additives to PPTA is 1:49;

[0250] The mass ratio of far-infrared PPTA powder to concentrated sulfuric acid is 1:4.2;

[0251] The coagulation bath is a dilute sulfuric acid aqueous solution with a sulfuric acid mass concentration of 2%; the draft ratio is 6;

[0252] The drying and setting temperature is 280°C.

[0253] The para-aramid fibers obtained in the above examples and comparative examples were subjected to performance tests. The specific test results are shown in Table 1 below. The test methods involved in the test process are:

[0254] Far infrared heating performance: GB / T 37631-2019 "Chemical fibers—Test method for thermal decomposition temperature";

[0255] Strength and modulus properties: Q / 0601 THX004-2025 "Para-aramid filament".

[0256] Table 1 Performance test results

[0257]

[0258] Examples 1-7 show far-infrared heating para-aramid fibers produced using the preparation method of the present invention. Comparison of the performance test results with the conventional para-aramid fibers of Comparative Example 1 demonstrates that the far-infrared nano-additives prepared in the present invention contain specific metal oxides (such as zinc oxide and zirconium oxide) treated in an alkaline sodium carbonate solution and organically modified with a silane coupling agent. This creates more active sites on the metal oxide surface, enabling more efficient absorption and emission of far-infrared radiation, further enhancing the fiber's far-infrared performance. The addition of the far-infrared nano-additives not only imparts far-infrared heating properties to the fibers but also positively impacts their mechanical properties. The metal oxides and composite powders in the nano-additives possess high hardness and strength, acting as reinforcing phases within the fibers. When subjected to external forces, these reinforcing phases effectively disperse stress and prevent crack propagation, thereby improving the fiber's strength and modulus. During the preparation of far-infrared heating para-aramid fibers, controlling spinning process parameters (such as the temperature within the screw dissolver, the draft ratio, and the drying and setting temperature) can achieve more regular molecular chain alignment within the fibers and enhance crystallinity. This optimized fiber structure helps improve the mechanical properties of the fiber, increasing its strength and modulus. The far-infrared heating para-aramid fiber produced using the preparation method of the present invention exhibits stable performance and effectively improves the heating performance of the para-aramid fiber, with a far-infrared temperature rise of no less than 2.0°C and a far-infrared emissivity of 0.83%, meeting the requirements for heating fibers. Furthermore, the far-infrared heating para-aramid fiber produced using the preparation method of the present invention also maintains excellent strength and modulus properties.

[0259] From the comparison of the experimental results of Comparative Example 2 and Example 5, it can be seen that: if Mg-AL MMO is not stirred in the sodium carbonate solution in step S1, the far-infrared heating performance of the far-infrared heating para-aramid fiber is significantly reduced, because the sodium carbonate solution treatment can significantly change the surface properties and crystal structure of Mg-AL MMO. The alkaline environment of the sodium carbonate solution promotes the formation of more active sites on the surface of Mg-AL MMO, and these sites can more effectively absorb and emit far-infrared rays. At the same time, the sodium carbonate solution treatment optimizes the crystal structure of Mg-AL MMO, making its absorption and emission efficiency in the far-infrared band higher. Without this treatment step, the far-infrared performance of Mg-AL MMO cannot be improved, resulting in a significant reduction in the far-infrared temperature rise and emissivity of the final fiber, which cannot meet the requirements of high-performance far-infrared heating fibers.

[0260] From the experimental results of Comparative Example 3 and Example 5, it can be seen that: if silane coupling agent is not added to carry out organic modification treatment in step S1, the intensity, modulus and far-infrared heating performance of far-infrared heating para-aramid fiber are obviously reduced, because the organic modification of silane coupling agent can significantly improve the compatibility and interfacial bonding strength between nano additive and para-aramid fiber matrix. In Example 5, the nano additive modified by silane coupling agent is evenly dispersed in the fiber, avoids agglomeration, and makes far-infrared performance stable. At the same time, good interfacial bonding strength enables nano additive to disperse stress more effectively in the fiber, stops crack propagation, thereby improving the intensity and modulus of fiber. While organic modification is not carried out in Comparative Example 3, nano additive is unevenly dispersed, and interfacial bonding is weak, causing far-infrared performance and mechanical properties to decline.

[0261] From the comparison of the experimental results of Comparative Example 4, Comparative Example 5 and Example 5, it can be seen that if the usage ratio of MgCl2·6H2O is reduced or increased, the performance of the far-infrared heating para-aramid fiber will be reduced. Because the molar ratio of MgCl2·6H2O and ALCl3·9H2O has an important influence on the structure and properties of Mg-Al LDHs, too much or too little will deteriorate the dispersibility of the nano-additive in the fiber, and it will be impossible to form an effective far-infrared radiation source and mechanical reinforcement phase, thereby leading to a decrease in the far-infrared heating performance and mechanical properties of the fiber. Therefore, the usage ratio of MgCl2·6H2O and ALCl3·9H2O defined in the present invention is more conducive to obtaining far-infrared heating para-aramid fiber with excellent performance.

[0262] From the comparison of the experimental results of Comparative Example 6 and Example 5, it can be seen that if the dispersion temperature of the far-infrared PPTA powder and concentrated sulfuric acid in the screw dissolver is lowered, the strength performance, modulus performance and far-infrared heating performance of the far-infrared heating para-aramid fiber will be significantly reduced. Because the viscosity of the para-aramid spinning solution is relatively high, lowering the dispersion temperature is not conducive to the uniform dispersion of the far-infrared PPTA powder, which ultimately leads to a decrease in the performance of the far-infrared heating para-aramid fiber.

[0263] From the comparison of the experimental results of Comparative Example 7 and Example 5, it can be seen that if the addition ratio of the far-infrared nano-additive is increased, the strength and modulus properties of the far-infrared heating para-aramid fiber will be significantly reduced, and the performance requirements of the para-aramid fiber cannot be met. Therefore, the use of the far-infrared nano-additive dosage ratio specified in the present invention is more conducive to obtaining far-infrared heating para-aramid fiber with excellent comprehensive performance.

[0264] Comparing the experimental results of Comparative Example 8 and Example 5 shows that lowering the drying and setting temperature significantly reduces the strength and modulus properties of the far-infrared heat-generating para-aramid fiber. This is because the higher drying and setting temperature (330°C) allows the molecular chains within the fiber to fully stretch and rearrange, forming a more regular crystalline structure, thereby improving the fiber's strength and modulus. Lowering the drying and setting temperature to 280°C results in inadequate stretching and rearrangement of the molecular chains, resulting in lower crystallinity and a decrease in fiber strength and modulus. Furthermore, lower setting temperatures may not completely remove stress from the fiber, making it more susceptible to deformation and breakage during subsequent use, further impacting its mechanical properties.

[0265] The technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0266] For those skilled in the art, several variations and improvements may be made without departing from the scope of the present invention, which all fall within the scope of protection of the present invention. The scope of protection of the present invention shall be based on the appended claims.

Claims

1. A method for preparing far-infrared heating para-aramid fiber, characterized in that: The preparation method is: Mg-Al LDHs were prepared by co-precipitation of S1, MgCl2·6H2O, and AlCl3·9H2O. The metal oxide Mg-Al MMO was then calcined and ground at high temperature. The Mg-Al MMO was reacted with Na2CO3, washed, and dried to obtain RLDH. The RLDH was then uniformly mixed with a UV-absorbing metal oxide and silicon oxide to obtain a composite powder. The composite powder was then organically modified with a silane coupling agent to obtain a far-infrared nano-additive. The molar ratio of MgCl2·6H2O to AlCl3·9H2O is 0.9:(0.9-1.2); the particle size of the far-infrared nano additive is not greater than 5nm; S2, mixing the far-infrared nano additive with PPTA, and uniformly dispersing the mixture in concentrated sulfuric acid to obtain a modified spinning solution, and using a dry-jet wet spinning process to obtain far-infrared heating para-aramid fiber; The far-infrared nano additive is mixed with PPTA to obtain far-infrared PPTA powder, and the temperature condition when the far-infrared PPTA powder is uniformly dispersed in the concentrated sulfuric acid is 90-92° C.; The modified spinning solution is degassed and then ejected through a spinneret into a coagulation bath, and then drawn, washed, dried, shaped, and wound to obtain the far-infrared heat-generating para-aramid fiber. The drying and setting temperature is 300-350°C; In step S2, the mass ratio of the far-infrared nano additive to PPTA is 1:(45-50).

2. The method for preparing far-infrared heating para-aramid fiber according to claim 1, characterized in that: In step S1, the high-temperature calcination temperature is 450-600°C.

3. The method for preparing far-infrared heating para-aramid fiber according to claim 1, characterized in that: In step S1, the ultraviolet absorbing metal oxide is at least one of zinc oxide and zirconium oxide; and the mass ratio of the RLDH, ultraviolet absorbing metal oxide and silicon oxide is (0.5-1):1:0.

2.

4. The method for preparing far-infrared heating para-aramid fiber according to claim 1, characterized in that: In step S1, the silane coupling agent is KH-570 silane coupling agent; The mass ratio of the silane coupling agent to the composite powder is 3:(3.5-4.5).

5. The method for preparing far-infrared heating para-aramid fiber according to claim 1, characterized in that: In step S2, the mass ratio of the far-infrared PPTA powder to the concentrated sulfuric acid is 1:(4.0-4.5).

6. A far-infrared heating para-aramid fiber, characterized in that: The far-infrared heating para-aramid fiber is prepared according to the preparation method according to any one of claims 1 to 5; The far-infrared temperature rise of the far-infrared heat-generating para-aramid fiber is not less than 2.0° C., and the far-infrared emissivity is not less than 0.83%.

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