Metaposition aramid cool fiber and preparation method thereof

Abstract

This invention relates to the field of functional fiber materials technology, specifically to a meta-aramid cooling fiber and its preparation method. The preparation method involves: dissolving branched polyethyleneimine in an acetate buffer solution, adding a nano-scale cooling material for modification, and then obtaining the modified aminated cooling material through solid-liquid separation; thoroughly homogenizing the modified aminated cooling material in an organic solvent, then adding it to a meta-aramid polymerization solution capped with acyl chloride for reaction to obtain a modified cooling meta-aramid solution; and spinning the modified cooling meta-aramid solution using a dry-jet wet spinning process to obtain the meta-aramid cooling fiber. This invention effectively combines meta-aramid with the modified cooling material in a specific manner, which can effectively increase the cooling factor of the fiber fabric, improve wearing comfort, and maintain the mechanical strength of the fiber.

Description

Technical Field

[0001] This invention relates to a meta-aramid cooling fiber and its preparation method, belonging to the field of functional fiber materials technology. Background Technology

[0002] Meta-aramid fibers are widely used in fire-fighting suits, arc flash protection suits, racing suits, and special industrial protective clothing due to their excellent flame retardancy, thermal stability, and electrical insulation. However, meta-aramid fibers are hydrophobic fibers, and their molecular chain structure (aromatic rings and amide bonds) makes them very incompatible with water molecules (whether in gaseous or liquid states). This results in fabrics with poor moisture absorption and wicking capabilities, poor moisture transfer, and low evaporative heat dissipation efficiency.

[0003] To address this issue, the cooling properties of fiber materials are improved through modification. Currently, there are two main methods for preparing meta-aramid cooling fibers: The first is in-situ polymer modification, which involves compounding inorganic cooling materials (such as jade powder, mica powder, alumina, and boron nitride) with the aramid polymerization solution during the dosing stage, and then spinning them through a spinning system to prepare meta-aramid fibers with cooling properties. While this method improves the cooling properties of the meta-aramid fibers, it suffers from problems such as uneven doping of the cooling materials leading to decreased fiber performance and poor cooling stability. The second method is fiber surface finishing, which involves coating the fiber surface with an organic cooling material (such as polyethanol or other phase change materials) to give the fiber a cooling effect. However, the cooling fibers prepared by this method have low interfacial bonding energy between the meta-aramid fiber surface and the cooling coating, leading to a significant decrease in the cooling effect as the cooling coating peels off during subsequent fiber processing and use.

[0004] In the prior art, patent application CN117339502A discloses a method for improving the cooling effect of fabrics by using cooling microcapsules. This method effectively solves the problem of poor wash resistance caused by the water solubility of the cooling material xylitol, controlling the decay rate of the cooling factor after 20 washes to within 15%. However, this method has the problem of increased processing costs and difficulty in large-scale production during industrialization, making it difficult to apply on a large scale in the preparation of meta-aramid fibers. In addition, patent application CN117026406A discloses a method for preparing durable cooling fibers, which modifies lamellar mica and aluminum nitride with a silane coupling agent and then blends and spins them with organic polymers. In this process, the inorganic cooling material can form hydrogen bonds with the organic polymer after treatment with the silane coupling agent, which can increase the retention rate of the cooling material in the fiber system. However, no stronger chemical bond structure is formed between the two, so there are limitations in improving the cooling stability of the fiber.

[0005] In summary, under current technology, it is difficult to achieve a stable and large-scale production process for meta-aramid cooling fibers. Furthermore, there are problems such as the gradual decline in the cooling performance of meta-aramid fabrics during long-term washing and use, low utilization rate of the intrinsic properties of cooling materials, and the impact of poor dispersion of cooling materials in the fiber system on the basic properties of the fiber. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a meta-aramid cooling fiber and its preparation method. The cooling material exists stably in the fiber system, enhancing the cooling effect of the meta-aramid fiber. This solves the problems of reduced cooling factor and unstable performance of meta-aramid cooling fiber, while ensuring that the meta-aramid fiber maintains good strength properties.

[0007] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing meta-aramid cooling fiber, wherein the preparation method is as follows:

[0008] Preparation of aminated cooling material: Branched polyethyleneimine was dissolved in acetate buffer, and then nano-scale cooling material was added for modification. After solid-liquid separation and drying, the modified aminated cooling material was obtained.

[0009] Preparation of modified cooling meta-aramid stock solution: After the aminated cooling material is fully homogenized in an organic solvent, it is added to the acyl chloride-terminated meta-aramid polymerization stock solution and reacted to obtain the modified cooling meta-aramid stock solution.

[0010] The modified cooling meta-aramid solution was spun using a dry-jet wet spinning process to obtain the meta-aramid cooling fiber.

[0011] Furthermore, the nanoscale cooling material is selected from at least one of nanoscale jade powder, mica powder, and shell powder.

[0012] Furthermore, the mass ratio of the branched polyethyleneimine to the nanoscale cooling material is 1:(2-4).

[0013] Furthermore, the preparation method of the acyl chloride-terminated meta-aramid polymerization stock solution is as follows: after the polymerization reaction of m-phenylenediamine and isophthaloyl chloride in an organic solvent, neutralization is carried out to obtain the acyl chloride-terminated meta-aramid polymerization stock solution; wherein the molar amount of isophthaloyl chloride is greater than the molar amount of m-phenylenediamine.

[0014] Furthermore, the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:(1-1.15); the mass ratio of the total mass of m-phenylenediamine and isophthaloyl chloride to the mass of the organic solvent is 1:(4-7).

[0015] Furthermore, the viscosity of the acyl chloride-terminated meta-aramid polymerization solution is 4500-5500 Po; the weight-average molecular weight of the polymer in the acyl chloride-terminated meta-aramid polymerization solution is 40-50 W.

[0016] Furthermore, in preparing the modified cooling meta-aramid stock solution, the mass ratio of the polymer to the aminated cooling material in the acyl chloride-terminated meta-aramid polymer stock solution is 1:(0.002-0.004); the reaction temperature is 75-85℃, and the reaction time is 0.5-1.5h.

[0017] Further, the organic solvent is at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0018] Furthermore, in the dry-jet wet spinning process, the pump supply rate is 15-20 r / min, the spinning speed is 55-75 m / min, the air layer height is 30-40 mm, and the coagulation bath temperature is 60-80℃.

[0019] The present invention also discloses a meta-aramid cooling fiber, wherein the meta-aramid cooling fiber is prepared by the preparation method described in the present invention.

[0020] The beneficial effects of this invention are:

[0021] The preparation method described in this invention modifies the cooling material by amination, resulting in a large number of free amino groups on its surface. This provides ample reaction sites, forming chemical bonds that improve the stability and uniformity of the cooling material within the fiber system. Simultaneously, the introduction of amino groups increases the fiber's hydrophilicity and enhances its moisture absorption and wicking capabilities. Meta-aramid fibers are then composited with the amination-modified cooling material using a dry-jet wet spinning process. This spinning process differs from wet spinning; the presence of an air layer during spinning creates a dense skin layer on the fiber surface, effectively suppressing the loss of free cooling material during fiber preparation. The resulting meta-aramid cooling fibers exhibit a strength exceeding 4.0 cN / dtex, a breaking elongation exceeding 30%, a limiting oxygen index >28, a cooling factor of 0.32, and no change in fiber luster. These fibers can be used as cooling protective fabrics in complex environments such as high temperatures, strong alkalis, and strong acids.

[0022] In the preparation method described in this invention, amide bonds are formed by the condensation reaction between the active amino groups on the surface of the cooling material and the acyl chloride groups in the polymer chain. By forming chemical bonds, the previous van der Waals forces are replaced, which improves the stability of the bonding between composite materials and increases the stability of the cooling material in the fiber system.

[0023] In the preparation method described in this invention, the hydrogel film formed on the fiber surface in the humid air layer through the dry-jet wet spinning process effectively prevents the partial release of cooling materials from the fiber during the forming process, improves the retention rate of cooling materials in the fiber system, and ensures the stability of the fiber's cooling performance.

[0024] The meta-aramid cooling fiber of this invention has a stable cooling material in the fiber, and the cooling factor of the fiber can still be maintained above 0.3 after 20 washes.

[0025] The meta-aramid cooling fiber described in this invention exhibits long-lasting cooling properties without compromising other fiber properties. Amino-modified cooling materials are one way to enhance the cooling performance of meta-aramid. Aminated cooling materials not only increase the hydrophilicity of the fiber, but also allow the active amino groups to react with the acyl chloride groups in the polymer chain to form chemical bonds, thereby enhancing the stability of the material in the fiber system. At the same time, the dry-jet wet spinning process effectively prevents molding defects caused by the precipitation of cooling materials during fiber forming, which greatly improves the retention rate of cooling materials in the fiber system and enhances the stability of the fiber's cooling performance. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0028] A method for preparing meta-aramid cooling fiber, wherein the preparation method comprises:

[0029] Preparation of aminated cooling material: Branched polyethyleneimine was dissolved in acetate buffer, and then nano-scale cooling material was added for modification. After solid-liquid separation and drying, the modified aminated cooling material was obtained.

[0030] Preparation of modified cooling meta-aramid stock solution: After the aminated cooling material is fully homogenized in an organic solvent, it is added to the acyl chloride-terminated meta-aramid polymerization stock solution and reacted to obtain the modified cooling meta-aramid stock solution.

[0031] The modified cooling meta-aramid solution was spun using a dry-jet wet spinning process to obtain the meta-aramid cooling fiber.

[0032] Specifically, the nano-scale cooling material is selected from at least one of nano-scale jade powder, mica powder, and shell powder.

[0033] Specifically, the mass ratio of the branched polyethyleneimine to the nanoscale cooling material is 1:(2-4).

[0034] Specifically, the preparation method of the acyl chloride-terminated meta-aramid polymerization stock solution is as follows: after the polymerization reaction of m-phenylenediamine and isophthaloyl chloride in an organic solvent, neutralization is performed (calcium hydroxide is used for neutralization to obtain a pH of 6-7) to obtain the acyl chloride-terminated meta-aramid polymerization stock solution; wherein the molar amount of isophthaloyl chloride is greater than the molar amount of m-phenylenediamine.

[0035] Specifically, the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:(1-1.15); the mass ratio of the total mass of m-phenylenediamine and isophthaloyl chloride to the mass of the organic solvent is 1:(4-7).

[0036] Specifically, the viscosity of the acyl chloride-terminated meta-aramid polymerization solution is 4500-5500 Po (25°C); the weight-average molecular weight of the polymer in the acyl chloride-terminated meta-aramid polymerization solution is 40-50 W.

[0037] Specifically, when preparing the modified cooling meta-aramid stock solution, the mass ratio of the polymer to the aminated cooling material in the acyl chloride-terminated meta-aramid polymerization stock solution is 1:(0.002-0.004); the reaction temperature is 75-85℃, and the reaction time is 0.5-1.5h.

[0038] Preferably, the reaction temperature is 80°C and the reaction time is 1 hour.

[0039] Specifically, the organic solvent is at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0040] More specifically, the process of fully homogenizing the aminated cooling material in an organic solvent is as follows: the aminated cooling material and the organic solvent are subjected to high-speed shear mixing, and then dispersed by high-pressure explosion nanomaterial dispersion technology (pressure of 3500 psi, time of 1.5 h) to fully homogenize the aminated cooling material in the organic solvent system, resulting in a mixture of aminated cooling material and organic solvent.

[0041] Specifically, in the dry-jet wet spinning process, the pump supply rate is 15-20 r / min, the spinning speed is 55-75 m / min, the air layer height is 30-40 mm, and the coagulation bath temperature is 60-80℃.

[0042] More specifically, the branched polyethyleneimine used in the embodiments of the present invention is: BPEI-20000 (Mw~20,000) from Wuhan Fuxinyuan Technology Co., Ltd., with a purity of 99%; the acetate buffer is: A106847 from Shanghai Aladdin Biochemical Technology Co., Ltd., 0.1M.

[0043] A meta-aramid cooling fiber, wherein the meta-aramid cooling fiber is prepared by the preparation method described in this invention.

[0044] Example 1

[0045] Preparation of a meta-aramid cooling fiber:

[0046] S1. Preparation of acyl chloride-terminated meta-aramid polymerization solution:

[0047] The meta-aramid polymerization solution was prepared by polymerizing m-phenylenediamine and isophthaloyl chloride in N,N-dimethylacetamide. The molar ratio of m-phenylenediamine to isophthaloyl chloride was 1:1.15, and the mass ratio of the total mass of m-phenylenediamine and isophthaloyl chloride to the mass of the organic solvent was 1:5. The reaction temperature was 5°C. After the reaction, the pH was adjusted to 6 using calcium hydroxide to obtain the meta-aramid polymerization solution. The viscosity of the meta-aramid polymerization solution was 4600 Po.

[0048] S2. Preparation of aminated cooling materials:

[0049] Branched polyethyleneimine was dissolved in 0.1M acetate buffer and magnetically stirred until completely dissolved to obtain a modified solution. Nanoscale jade powder was added to the modified solution and stirred for 15 hours for modification treatment. After the reaction was completed, the product was centrifuged and washed 5 times. Finally, the product was vacuum dried at 60℃ for 18 hours to obtain aminated jade powder material.

[0050] The mass ratio of branched polyethyleneimine to acetate buffer is 10:1; the mass ratio of branched polyethyleneimine to nano-sized jade powder is 1:3.

[0051] S3. The aminated jade powder composite material is mixed with N,N-dimethylacetamide (DMAC) under high-speed shear, and then dispersed by high-pressure explosion nanomaterial dispersion technology to make the aminated jade powder fully homogenized in the DMAC solvent system. The resulting aminated jade powder material and DMAC homogenized mixture are then obtained.

[0052] The mass ratio of amino-modified jade powder to DMAC is 1:20.

[0053] S4. Preparation of modified cool-feeling meta-aramid stock solution:

[0054] The mixture from step S3 is mixed with the acyl chloride-terminated meta-aramid polymerization stock solution prepared in step S1 and then reacted; the mass ratio of the polymer to the aminated cooling material in the acyl chloride-terminated meta-aramid polymerization stock solution is 1:0.002; the reaction temperature is 85℃ and the reaction time is 1h to obtain the modified cooling meta-aramid stock solution.

[0055] S5. Preparation of meta-aramid cooling fiber: The modified cooling meta-aramid dope is spun using a dry-jet wet spinning process to obtain the meta-aramid cooling fiber. During the spinning process, the pump supply rate is 15 r / min; the spinning speed is 55 m / min; the air layer height is 30 mm; the air layer humidity is 60%; and the coagulation bath temperature is 60℃.

[0056] Example 2

[0057] Preparation of a meta-aramid cooling fiber:

[0058] S1. Preparation of acyl chloride-terminated meta-aramid polymerization solution:

[0059] The meta-aramid polymerization solution was prepared by polymerizing m-phenylenediamine and isophthaloyl chloride in N,N-dimethylacetamide. The molar ratio of m-phenylenediamine to isophthaloyl chloride was 1:1.15, and the mass ratio of the total mass of m-phenylenediamine and isophthaloyl chloride to the mass of the organic solvent was 1:4. The reaction temperature was 5°C. After the reaction, the pH was adjusted to 6.5 with calcium hydroxide to obtain the meta-aramid polymerization solution. The viscosity of the meta-aramid polymerization solution was 5000 Po.

[0060] S2. Preparation of aminated cooling materials:

[0061] Branched polyethyleneimine was dissolved in 0.1M acetate buffer and magnetically stirred until completely dissolved to obtain a modified solution. Nanoscale mica powder was added to the modified solution and stirred for 15 hours for modification treatment. After the reaction was completed, the product was centrifuged and washed 5 times. Finally, the product was vacuum dried at 60℃ for 18 hours to obtain aminated jade powder material.

[0062] The mass ratio of branched polyethyleneimine to acetate buffer is 10:1; the mass ratio of branched polyethyleneimine to nano-sized mica powder is 1:4.

[0063] S3. The aminated mica powder material is mixed with N,N-dimethylacetamide (DMAC) under high-speed shear, and then dispersed by high-pressure explosion nanomaterial dispersion technology to make the aminated mica powder material fully homogenized in the DMAC solvent system. The resulting homogenized mixture of aminated mica powder material and DMAC is then obtained.

[0064] The mass ratio of aminated mica powder to DMAC is 1:20.

[0065] S4. Preparation of modified cool-feeling meta-aramid stock solution:

[0066] The mixture from step S3 is mixed with the acyl chloride-terminated meta-aramid polymerization stock solution prepared in step S1 and then reacted; the mass ratio of the polymer to the aminated cooling material in the acyl chloride-terminated meta-aramid polymerization stock solution is 1:0.003; the reaction temperature is 85℃ and the reaction time is 1h to obtain the modified cooling meta-aramid stock solution.

[0067] S5. Preparation of meta-aramid cooling fiber: The modified cooling meta-aramid dope is spun using a dry-jet wet spinning process to obtain the meta-aramid cooling fiber. During the spinning process, the pump supply rate is 17 r / min; the spinning speed is 62 m / min; the air layer height is 35 mm; the air layer humidity is 70%; and the coagulation bath temperature is 70℃.

[0068] Example 3

[0069] Preparation of a meta-aramid cooling fiber:

[0070] S1. Preparation of acyl chloride-terminated meta-aramid polymerization solution:

[0071] The meta-aramid polymerization solution was prepared by polymerizing m-phenylenediamine and isophthaloyl chloride in N,N-dimethylacetamide. The molar ratio of m-phenylenediamine to isophthaloyl chloride was 1:1.15, and the mass ratio of the total mass of m-phenylenediamine and isophthaloyl chloride to the mass of the organic solvent was 1:7. The reaction temperature was 5°C. After the reaction, the pH was adjusted to 6 using calcium hydroxide to obtain the meta-aramid polymerization solution. The viscosity of the meta-aramid polymerization solution was 4600 Po.

[0072] S2. Preparation of aminated cooling materials:

[0073] Branched polyethyleneimine was dissolved in acetate buffer (concentration 0.1M) and magnetically stirred until completely dissolved to obtain a modified solution. Nanoscale shell powder was added to the modified solution and stirred for 15 hours for modification treatment. After the reaction was completed, the product was centrifuged and washed 5 times. Finally, the product was vacuum dried at 60℃ for 18 hours to obtain aminated shell powder material.

[0074] The mass ratio of branched polyethyleneimine to acetate buffer is 10:1; the mass ratio of branched polyethyleneimine to nano-sized seashell powder is 1:4.

[0075] S3. The aminated shell powder material is mixed with N,N-dimethylacetamide (DMAC) under high-speed shear, and then dispersed by high-pressure explosion nanomaterial dispersion technology to make the aminated shell powder material fully homogenized in the DMAC solvent system. The resulting homogenized mixture of aminated shell powder material and DMAC is then obtained.

[0076] The mass ratio of aminated shell powder to DMAC is 1:20.

[0077] S4. Preparation of modified cool-feeling meta-aramid stock solution:

[0078] The mixture from step S3 is mixed with the acyl chloride-terminated meta-aramid polymerization stock solution prepared in step S1 and then reacted; the mass ratio of the polymer to the aminated cooling material in the acyl chloride-terminated meta-aramid polymerization stock solution is 1:0.0025; the reaction temperature is 85℃ and the reaction time is 1h to obtain the modified cooling meta-aramid stock solution.

[0079] S5. Preparation of meta-aramid cooling fiber: The modified cooling meta-aramid dope is spun using a dry-jet wet spinning process to obtain the meta-aramid cooling fiber. During the spinning process, the pump supply rate is 20 r / min; the spinning speed is 73 m / min; the air layer height is 40 mm; the air layer humidity is 80%; and the coagulation bath temperature is 75℃.

[0080] Comparative Example 1

[0081] Meta-aramid cooling fibers were prepared using the same method as in Example 1, except that in step S1, the molar ratio of m-phenylenediamine to isophthaloyl chloride was 1:0.998, meaning the prepared meta-aramid polymerization solution was amino-terminated. The specific process of step S1 was as follows: m-phenylenediamine and isophthaloyl chloride were polymerized in N,N-dimethylacetamide to obtain the meta-aramid polymerization solution; wherein the molar ratio of m-phenylenediamine to isophthaloyl chloride was 1:0.998, the reaction temperature was 5°C, and after the reaction, the pH was adjusted to 6 using calcium hydroxide to obtain the meta-aramid polymerization solution; the viscosity of the meta-aramid polymerization solution was 4600 Po. All other steps remained the same as in Example 1.

[0082] Comparative Example 2

[0083] Meta-aramid cooling fibers were prepared using the same method as in Example 1, except that: aminated jade powder material was not prepared, i.e., step S2 was not performed. The specific process of step S3 was as follows: jade powder and N,N-dimethylacetamide (DMAC) were subjected to high-speed shear mixing, and then dispersed by high-pressure explosion nanomaterial dispersion technology to ensure that the jade powder was fully homogenized in the DMAC solvent system. The resulting homogenized mixture of jade powder and DMAC was then obtained. The remaining steps were the same as in Example 1.

[0084] Comparative Example 3

[0085] Meta-aramid cooling fibers were prepared using the same method as in Example 1, except that the reaction temperature in step S4 was adjusted from 85°C to 50°C. The specific process of step S4 was as follows: the mixture from step S3 was mixed with the acyl chloride-terminated meta-aramid polymerization solution prepared in step S1 and then reacted; the mass ratio of polymer to modified cooling material was 1:0.002; the reaction temperature was 50°C and the reaction time was 1 hour to obtain the modified cooling meta-aramid solution; the remaining steps were the same as in Example 1.

[0086] Comparative Example 4

[0087] Meta-aramid cooling fibers were prepared using the same method as in Example 1, except that the dry-jet wet spinning process in step S5 was replaced with a wet spinning process. The specific process of step S5 is as follows: the modified cooling meta-aramid dope is spun using a wet spinning process to obtain the meta-aramid cooling fibers. During the spinning process, the pump supply rate is 20 r / min; the spinning speed is 20 m / min; and the coagulation bath temperature is 15℃.

[0088] Blank example

[0089] Acyl chloride-terminated meta-aramid polymerization solution was prepared using the same method as step S1 in Example 1, and then aramid fibers were prepared by spinning using the same method as step S5 in Example 1.

[0090] The performance of the aramid fibers prepared in Examples 1-3, Comparative Examples 1-4, and the blank example was tested. The specific test data are shown in Table 1 below, and the relevant test methods are as follows:

[0091] (1) Cooling performance test method: The test was conducted according to the national standard GB / T 35263-2017.

[0092] (2) Cooling stability test method: 10cm×10cm cooling fiber fabric was stirred and washed in 1kg of 20℃ deionized water for 10 minutes. The washing process was repeated 20 times under the same conditions. After drying, the cooling performance of each modified fabric was tested again.

[0093] (3) Test method for fiber breaking strength: The test shall be conducted in accordance with the test method of GB / T 14337-2008.

[0094] (4) Flame retardant performance test method: The test shall be conducted in accordance with the test method of GB / T2406.

[0095] (5) Gloss test method: Place the meta-aramid cool-feel fiber sample on the gloss tester, and then start the tester to perform the test. The tester will emit a beam of light to illuminate the sample surface, and then the sensor on the instrument will detect the reflection of the light to obtain the gloss value of the sample.

[0096] (6) The fiber fabric weaving method used in the above test process: First, take 1kg of 1.5D 51mm fiber to prepare yarn. The yarn count is 32s / 2 and the twist coefficient is 350-400. The batch warping machine is used with a speed of 85m / min and the warp tension fluctuation is ≤±5%. After completion, a high-pressure sizing agent is used for sizing (the sizing agent is: Zhejiang Chuanhua Co., Ltd. PVA-2099 modified composite sizing agent; the sizing rate is 10%). The machine speed is 85m / min and the drying barrel temperature is 100℃ to obtain various modified yarns. Finally, a rapier loom is used for weaving. The machine speed is 120r / min and the warp tension fluctuation is ≤±5%. The twill weave is used with a warp density of 268 threads / 10cm and a weft density of 216 threads / 10cm to prepare various fiber fabrics.

[0097] Table 1 Performance Test Data

[0098]

[0099] As can be seen from the data in Table 1, the meta-aramid cooling fibers prepared by the method of this invention in Examples 1-3 have excellent cooling properties. Furthermore, the strength of the meta-fiber remains above 4.0 cN / dtex, the elongation at break remains above 30%, the limiting oxygen index is greater than 28, and the fiber gloss is slightly lower than that of conventional fibers. This is because the addition of the cooling composite material has a matting effect on the fiber. This fabric can be used as a cooling protective fabric in complex environments such as high temperature, strong alkali, and strong acid. The effective cooling composite material exists stably in the fiber, and the cooling coefficient of the fiber fabric can still be maintained at 0.2 J / (cm²) after 20 washes. 2 • s) or above, meeting the market requirements for Grade A cooling fabrics (cooling coefficient ≥ 0.2 J / (cm²) 2 ·s)).

[0100] A comparison of the data from Comparative Example 1 and Example 1 shows that if there are more amino functional groups than acyl chloride functional groups during the preparation process, the polymer chain will ultimately have amino groups at both ends. In subsequent preparation processes, the aminated cooling material, lacking acyl chloride groups, is difficult to react with the molecular chain to form strong chemical bonds. This leads to poor dispersibility and stability of the cooling material in the original solution system, directly affecting the uniformity of the fiber forming process and the retention rate of the cooling material, resulting in a significant decrease in the fiber's mechanical and cooling properties.

[0101] A comparison of the data from Comparative Example 2 and Example 1 shows that adding unaminated cooling material directly to the meta-aramid polymerization solution not only leads to a decrease in the mechanical properties of the fiber, but also significantly reduces the water resistance of the meta-aramid's cooling properties, with the cooling effect decreasing significantly with increasing washing cycles. In the preparation method described in this invention, the cooling material is aminated, and under certain conditions, it undergoes a condensation reaction with molecular chains terminally bearing acyl chloride groups to form a stable and uniform composite structure. This allows for a uniform and stable bond between the cooling material and the meta-aramid fiber matrix material, resulting in fibers with no significant changes in mechanical properties and no significant reduction in cooling effect after multiple washes.

[0102] The data comparison between Comparative Example 3 and Example 1 shows that if the aminated cooling material and the meta-aramid polymerization solution do not reach the reaction temperature, it is difficult for them to form effective amide bonds. This will lead to the failure of amination and acyl chloride. Because of the lack of amide bonds to capture the cooling material, the cooling material cannot exist uniformly and stably in the meta-aramid system. At the same time, the addition of uneven cooling material affects the fiber forming process, resulting in a decrease in fiber mechanical properties. Furthermore, the cooling performance decreases with the increase of washing cycles.

[0103] The data comparison between Comparative Example 4 and Example 1 shows that since the amination rate and bonding rate with polymer chains of the cooling material cannot reach 100%, the dry-jet wet spinning process can effectively prevent the release of unbonded cooling materials into the coagulation bath in the early stage of fiber forming, thereby achieving a higher retention rate of cooling materials inside the fiber and water washing stability, and improving the cooling performance of the fiber.

[0104] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0105] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for preparing meta-aramid cooling fiber, characterized in that, The preparation method is as follows: Preparation of aminated cooling material: Branched polyethyleneimine was dissolved in acetate buffer, and then nano-scale cooling material was added for modification. After solid-liquid separation and drying, the modified aminated cooling material was obtained. Preparation of modified cooling meta-aramid stock solution: After the aminated cooling material is fully homogenized in an organic solvent, it is added to the acyl chloride-terminated meta-aramid polymerization stock solution and reacted to obtain the modified cooling meta-aramid stock solution. The modified cooling meta-aramid solution was spun using a dry-jet wet spinning process to obtain the meta-aramid cooling fiber. The preparation method of the acyl chloride-terminated meta-aramid polymerization stock solution is as follows: m-phenylenediamine and isophthaloyl chloride are polymerized in an organic solvent at a reaction temperature of 5°C. After the reaction, the pH is adjusted to 6 with calcium hydroxide to obtain the acyl chloride-terminated meta-aramid polymerization stock solution; the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1:1.

15. When preparing the modified cooling meta-aramid dope, the mass ratio of the polymer to the aminated cooling material in the acyl chloride-terminated meta-aramid polymerization dope is 1:(0.002-0.004); the reaction temperature is 75-85℃, and the reaction time is 0.5-1.5h.

2. The method for preparing a meta-aramid cooling fiber according to claim 1, characterized in that, The nano-scale cooling material is selected from at least one of nano-scale jade powder, mica powder, and shell powder.

3. The method for preparing a meta-aramid cooling fiber according to claim 1, characterized in that, The mass ratio of the branched polyethyleneimine to the nanoscale cooling material is 1:(2-4).

4. The method for preparing a meta-aramid cooling fiber according to claim 1, characterized in that, The mass ratio of the total mass of m-phenylenediamine and isophthaloyl chloride to the mass of the organic solvent is 1:(4-7).

5. The method for preparing a meta-aramid cooling fiber according to claim 1, characterized in that, The viscosity of the acyl chloride-terminated meta-aramid polymerization solution is 4500-5500 Po; the weight-average molecular weight of the polymer in the acyl chloride-terminated meta-aramid polymerization solution is 40-50 W.

6. The method for preparing a meta-aramid cooling fiber according to claim 1, characterized in that, The organic solvent is at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

7. The method for preparing a meta-aramid cooling fiber according to claim 1, characterized in that, In the dry-jet wet spinning process, the pump supply rate is 15-20 r / min, the spinning speed is 55-75 m / min, the air layer height is 30-40 mm, and the coagulation bath temperature is 60-80℃.

8. A meta-aramid cooling fiber, characterized in that, The meta-aramid cooling fiber is prepared by the preparation method described in any one of claims 1-7.

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