A kind of anti-ultraviolet aramid fiber and preparation method thereof

Abstract

The present invention belongs to the field of functional fiber technology and relates to a UV-resistant aramid fiber and its preparation method. During preparation, a KZW polymer solution and a MAF polymer solution are uniformly mixed as a spinning solution, and then wet-dry spinning is performed to produce the UV-resistant aramid fiber. The UV-resistant aramid fiber has a fineness of 1 to 5 dtex and a density of 1.4 to 1.6 g / cm³. The UV-resistant aramid fiber has a UPF value of 60 to 100 and a UV transmittance of 1% to 3%. After 100 hours of UV irradiation, the UV-resistant aramid fiber has a breaking strength retention rate of 97 to 99% and an elongation retention rate of 95.8 to 98.6%. The UV-resistant aramid fiber of the present invention not only has UV aging resistance but also synergistically enhances its interfacial bonding strength, thermal stability, and durability. The preparation method is simple and easy to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of functional fibers and relates to an anti-ultraviolet aramid fiber and a preparation method thereof. Background Art

[0002] Aramid (aromatic polyamide fiber) boasts broad application prospects in aerospace, defense, and rail transportation due to its high strength, high modulus, lightweight, heat-resistant, and impact- and wear-resistant properties. However, aramid is a photosensitive organic fiber. Its molecular chains contain numerous chromophores (amide bonds and benzene rings), which readily absorb UV radiation, triggering amide bond breakage. This accelerates the oxidative degradation of the polymer chains, disrupting their regular structure and impairing the fiber's mechanical properties. Therefore, selecting appropriate UV-resistant agents and designing effective UV-resistant modification methods to enhance the fiber's resistance to UV aging and extend its service life are key areas of research in aramid modification.

[0003] At present, the modification methods for aramid anti-UV aging mainly focus on the following two methods: one is to directly apply a UV absorber or shielding agent coating on the fiber surface. However, the coating has a low stability (easy to fall off), resulting in a short time of UV resistance; the other is to add an anti-UV aging agent to the spinning solution to prepare UV aging-resistant fiber. However, this method shortens the life of the fiber and the anti-UV agent is not stable and easy to lose.

[0004] For example, Reference 1 (Study on the Anti-UV Aging of Aromatic Polyamide Fabrics [J]. Synthetic Fibers, 2011, 40(3):1-4) discloses a diimide emulsion coating that has a strong absorption effect on ultraviolet light in the 320~330nm band. Although the aramid fabric modified by this coating has a certain UV stability, and the strength retention rate can reach 87% after 100h of UV radiation, the UV stability still needs to be improved.

[0005] Reference 2 (Nanoporous SiO2 grafted aramid fibers with low thermal conductivity[J]. Composites Science and Technology, 2017, 146: 91-98) introduced nitro groups into the fiber surface through nitration reaction, and then used γ-(2.3-epoxypropoxy)propyltrimethoxysilane for reduction and grafting reaction to cover the surface of aramid fibers with mesoporous and hyperbranched network structures, thereby improving the surface roughness and surface polarity of the aramid fibers. However, this resulted in a serious reduction in the mechanical properties of the aramid fibers.

[0006] Reference 3 (Effect of ANF / TiO2 mechanochemical composite on the UV aging resistance of aramid nanocomposite paper [J]. China Papermaking, 2022, 41(11):37-44) Based on the principle of mechanochemical composite, ultrasonic blending or ball milling composite method was used to realize the composite of aramid nanofibers and nano-TiO2 to prepare aramid fiber materials with excellent UV resistance. However, due to the doping of foreign matter, the strength of the material was damaged, and the UV resistance decreased with the loss of TiO2 over time.

[0007] Therefore, it is of great significance to study an anti-ultraviolet aramid fiber and a preparation method thereof to solve the problems existing in the prior art. Summary of the Invention

[0008] The purpose of the present invention is to solve the problems existing in the prior art and provide an anti-ultraviolet aramid fiber and a preparation method thereof.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing an anti-ultraviolet aramid fiber comprises mixing a KZW polymer solution and a MAF polymer solution uniformly to form a spinning solution, and performing dry-wet spinning to prepare the anti-ultraviolet aramid fiber;

[0011] The structural formula of KZW polymer is , number average molecular weight is 2000~10000;

[0012] The structural formula of MAF polymer is , the number average molecular weight is 20,000~80,000.

[0013] As the preferred technical solution:

[0014] In the above-mentioned method for preparing an ultraviolet-resistant aramid fiber, the molar ratio of the KZW polymer to the MAF polymer is 0.02-0.2:1.

[0015] As described above, a method for preparing a UV-resistant aramid fiber comprises the following steps for preparing a KZW polymer solution: first, reacting quinoline-2,7-diamine with a halogen element (X2) to generate a KZW monomer; then, under the protection of an inert gas, adding DMAc and LiCl to a reactor, adding the KZW monomer under stirring, cooling the reaction mixture from room temperature to -8 to 0°C after the KZW monomer is completely dissolved, adding isophthaloyl chloride in batches (the purpose of adding isophthaloyl chloride in batches is to prevent a rapid increase in temperature due to the exothermic reaction), then heating the reaction mixture to 20 to 40°C and maintaining the reaction temperature for 4 to 12 hours; finally, adding LiOH to the reaction mixture for neutralization to obtain a KZW polymer solution.

[0016] In the preparation method of the UV-resistant aramid fiber described above, the molar ratio of quinoline-2,7-diamine to the halogen element is 1:1.05-1.25, and the molar ratio of KZW monomer, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.3-1.6:400-4000:4-8:6-10.

[0017] In the above-mentioned method for preparing an ultraviolet-resistant aramid fiber, the halogen element is F2, Cl2, Br2 or I2.

[0018] The preparation method of the anti-ultraviolet aramid fiber as described above comprises the following steps of preparing a MAF polymer: under inert gas protection, adding DMAc and LiCl into a reaction kettle, adding m-phenylenediamine under stirring, cooling the reaction mixture from room temperature to -8-0°C after the m-phenylenediamine is completely dissolved, adding isophthaloyl chloride in batches, then heating the reaction mixture to 20-40°C and maintaining the temperature for 15-45 minutes. After the reaction is completed, LiOH is added to the system for neutralization to obtain a MAF polymer solution.

[0019] In the above-mentioned method for preparing an ultraviolet-resistant aramid fiber, the molar ratio of m-phenylenediamine, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.1-1.3:400-4000:4-8:6-10.

[0020] The preparation method of the UV-resistant aramid fiber as described above, wherein the dry and wet spinning process sequentially includes the steps of spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting and winding;

[0021] The dry-wet spinning process parameters are as follows:

[0022] The spinning solution temperature is 20°C;

[0023] The metering pump speed is 3~9r / min, the spinning speed is 6~18m / min, and the spinneret specification is φ0.04mm×200~800 holes (i.e. the spinneret hole diameter is 0.04mm and the number of holes is 200~800 holes);

[0024] After spinning, the fibers first enter an air bath and then a coagulation bath for stretching. The air bath height is 8-16 mm, the coagulation bath temperature is 20-30°C, and the coagulation bath is a 35-60 wt% DMAc aqueous solution.

[0025] The water washing temperature is 40~80℃;

[0026] Drying temperature is 100~110℃;

[0027] The dry heat stretching temperature is 270~350℃, and the dry heat stretching ratio is 2~6 times;

[0028] The heat setting temperature is 250~380℃, and the heat setting time is 30~180s.

[0029] The present invention also provides an anti-ultraviolet aramid fiber prepared by the method described in any one of the above items, wherein the anti-ultraviolet aramid fiber has a fineness of 1 to 5 dtex and a density of 1.4 to 1.6 g / cm³;

[0030] The UPF value of UV-resistant aramid fiber is 60~100, and the UV transmittance is 1%~3%;

[0031] After 100 hours of UV irradiation, the breaking strength retention rate of the UV-resistant aramid fiber was 97~99%, and the breaking elongation retention rate was 95.8~98.6%.

[0032] As the preferred technical solution:

[0033] The UV-resistant aramid fiber as described above has a breaking strength of 5.2-6.8 GPa, an initial modulus of 60-70 GPa, an elongation at break of 20-28%, an initial decomposition temperature of 520-560° C., and a carbon residue rate of 65-78% at 800° C.

[0034] Principle of the invention:

[0035] This invention introduces quinoline-2,7-diamine molecules through polymerization to form a KZW polymer. This KZW polymer is then added in trace amounts to a meta-aramid polymer system as an additive component (similar to a masterbatch), imparting UV resistance to the system. Because the KZW polymer structure is similar to meta-aramid and highly compatible, it has minimal impact on the inherent mechanical and thermal properties of the meta-aramid system compared to traditional methods such as direct addition of UV inhibitors or copolymerization of UV monomers. The resulting product exhibits superior UV resistance and interfacial properties.

[0036] The pyridine ring in the molecular structure of quinoline-2,7-diamine increases the symmetry and aromaticity of the polymer, which can enhance the hydrogen bond density between polymer molecular chains, thereby increasing the thermal and chemical stability of the UV-resistant aramid fiber; in addition, the hydrogen bonds in the molecule are easily broken after being exposed to ultraviolet radiation (the large conjugated structure of the quinoline structure and the amino-electron-donating group enable the π electrons in the molecule to jump to higher energy levels when exposed to ultraviolet light), and the electron cloud density is transferred to the N atom to form an unstable tautomer, and then the absorbed ultraviolet light energy is converted into heat energy to restore to the original stable hydrogen bond ground state, thereby improving the UV resistance of the UV-resistant aramid fiber. Beneficial effects

[0037] (1) The anti-ultraviolet aramid fiber of the present invention has excellent anti-ultraviolet performance. After being irradiated with ultraviolet light for 100 hours, the breaking strength retention rate of the anti-ultraviolet aramid fiber is 97-99%, and the breaking elongation retention rate is 95.8-98.6%.

[0038] (2) The preparation method of the UV-resistant aramid fiber of the present invention can improve the anti-UV aging ability of the aromatic polyamide fiber while synergistically enhancing its interfacial bonding strength, thermal stability and durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of MAF polymer synthesis;

[0040] Figure 2 Schematic diagram of KZW monomer synthesis;

[0041] Figure 3 Schematic diagram of KZW polymer synthesis;

[0042] Figure 4 For Example 5 The hydrogen spectrum ( 1 H NMR), the abscissa represents the displacement in PPM;

[0043] Figure 5 For Example 5 The carbon spectrum ( 13 C NMR);

[0044] Figure 6 For Example 2 The hydrogen spectrum ( 1 H NMR);

[0045] Figure 7 shows the second embodiment The carbon spectrum ( 13 C NMR);

[0046] FIG8 is a diagram of Example 3 The hydrogen spectrum ( 1 H NMR);

[0047] Figure 9 For Example 3 The carbon spectrum ( 13 C NMR);

[0048] Figure 10 For Example 4 The hydrogen spectrum ( 1 H NMR);

[0049] Figure 11 For Example 4 The carbon spectrum ( 13 C NMR);

[0050] Figure 12 For Example 5 The hydrogen spectrum ( 1 H NMR);

[0051] Figure 13 For Example 2 The hydrogen spectrum ( 1 H NMR);

[0052] Figure 14 For Example 3 The hydrogen spectrum ( 1 H NMR);

[0053] Figure 15 For Example 4 The hydrogen spectrum ( 1 H NMR). DETAILED DESCRIPTION

[0054] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0055] The test methods involved in the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0056] Number average molecular weight: Tested in accordance with GB / T 21863-2008 "Gel Permeation Chromatography (GPC) for Determination of Average Molecular Weight and Molecular Weight Distribution of Polymers".

[0057] UPF value: Tested in accordance with GB / T 18830-2009 “Evaluation of UV Protection Performance of Textiles”.

[0058] Ultraviolet transmittance, i.e. T(UVA): tested in accordance with GB / T 18830-2009 “Textiles — Evaluation of UV protection properties”.

[0059] Breaking strength, elongation at break, initial modulus: tested in accordance with GB / T 19975-2005.

[0060] Retention rate of breaking strength and elongation at break: The UV-resistant aramid fiber was irradiated with a 30 W UV lamp at a distance of 100 mm from the sample. After irradiation for 100 h, the fiber was taken out and its mechanical properties were measured.

[0061] Thermal stability test: A 4 mg sample of pre-dried UV-resistant aramid fiber was tested at 30-900°C using a NETZSCH TG 209 F1 thermogravimetric analyzer. The heating rate and flow rate of the protective N2 gas were set at 20°C / min and 40 mL / min, respectively. The initial decomposition temperature and the residual carbon rate at 800°C were determined.

[0062] The sources of some of the substances of the present invention are as follows:

[0063] m-Phenylenediamine: CAS: 108-45-2;

[0064] Isophthaloyl chloride: CAS: 99-63-8;

[0065] Quinoline-2,7-diamine: CAS: 114058-72-9.

[0066] Example 1

[0067] A method for preparing UV-resistant aramid fiber, comprising the following steps:

[0068] (1) Preparation of KZW polymer solution:

[0069] (1.1) If Figure 2 As shown, quinoline-2,7-diamine is reacted with F2 to form KZW monomer;

[0070] The molar ratio of quinoline-2,7-diamine to F2 is 1:1.05;

[0071] (1.2) If Figure 3 As shown, under the protection of inert gas, DMAc and LiCl were added to the reactor, and KZW monomer was added under stirring. After the KZW monomer was completely dissolved, the temperature was lowered to -8°C, and isophthaloyl chloride was added in batches. Then, the temperature was raised to 20°C and kept for reaction for 12 hours.

[0072] (1.3) LiOH is added to the reaction system for neutralization to obtain a KZW polymer solution;

[0073] The molar ratio of KZW monomer, isophthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.3:400:4:6;

[0074] The structural formula of KZW polymer is , the number average molecular weight is 2000;

[0075] (2) Preparation of MAF polymer:

[0076] like Figure 1 As shown, under the protection of inert gas, DMAc and LiCl were added to a reactor, and m-phenylenediamine was added under stirring. After the m-phenylenediamine was completely dissolved, the temperature was lowered to -8°C, and isophthaloyl chloride was added in batches. The temperature was then raised to 20°C and kept warm to continue the reaction for 45 minutes. After the reaction was completed, LiOH was added to the system for neutralization to obtain a MAF polymer solution.

[0077] The molar ratio of m-phenylenediamine, isophthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.1:400:4:6;

[0078] The structural formula of MAF polymer is , the number average molecular weight is 20000;

[0079] (3) the KZW polymer solution of step (1) and the MAF polymer solution of step (2) are uniformly mixed as a spinning solution, and dry-wet spinning is performed, and the UV-resistant aramid fiber is obtained by the steps of spinning, stretching, washing with water at 40°C, drying at 100°C, dry heat stretching, oiling, heat setting and winding;

[0080] The molar ratio of KZW polymer to MAF polymer is 0.02:1;

[0081] The dry-wet spinning process parameters are as follows:

[0082] The spinning solution temperature was 20°C; the metering pump speed was 3 r / min, the spinneret speed was 6 m / min, and the spinneret specifications were φ0.04 mm × 200 holes;

[0083] After spinning, the fibers first enter an air bath and then a coagulation bath for stretching. The air bath height is 8 mm, the coagulation bath temperature is 20°C, the coagulation bath is a 35 wt% DMAc aqueous solution, and the stretching ratio is 2 times.

[0084] The dry heat stretching temperature is 270℃ and the dry heat stretching ratio is 6 times;

[0085] The oiling rate is 0.05wt%;

[0086] The heat setting temperature is 250°C and the heat setting time is 180s;

[0087] The winding speed is 200m / min.

[0088] The final UV-resistant aramid fiber has a fineness of 1 dtex and a density of 1.4 g / cm³. The UPF value of the UV-resistant aramid fiber is 60, and the UV transmittance is 1%. The breaking strength of the UV-resistant aramid fiber is 5.2 GPa, the initial modulus is 60 GPa, the elongation at break is 20%, the initial decomposition temperature is 520°C, and the residual carbon rate at 800°C is 65%. After 100 hours of UV irradiation, the breaking strength retention rate of the UV-resistant aramid fiber is 97%, and the elongation at break retention rate is 95.8%.

[0089] Example 2

[0090] A method for preparing UV-resistant aramid fiber, comprising the following steps:

[0091] (1) Preparation of KZW polymer solution:

[0092] (1.1) Quinoline-2,7-diamine is reacted with Cl2 to generate KZW monomer. The hydrogen and carbon spectra of KZW monomer are as follows: Figure 6 and Figure 7 As shown;

[0093] The molar ratio of quinoline-2,7-diamine to Cl2 is 1:1.1;

[0094] (1.2) Under inert gas, add DMAc and LiCl to a reactor. Add KZW monomer while stirring. Once KZW monomer is completely dissolved, cool to -6°C. Add isophthaloyl chloride in batches. Then, raise the temperature to 30°C and maintain the reaction for 8 h.

[0095] (1.3) LiOH is added to the reaction system for neutralization to obtain a KZW polymer solution;

[0096] The molar ratio of KZW monomer, isophthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.4:1300:5:7;

[0097] like Figure 13 As shown, the structural formula of KZW polymer is , the number average molecular weight is 4000;

[0098] (2) Preparation of MAF polymer:

[0099] Under inert gas protection, DMAc and LiCl were added to a reactor, and m-phenylenediamine was added under stirring. After m-phenylenediamine was completely dissolved, the temperature was lowered to -6°C, and isophthaloyl chloride was added in batches. The temperature was then raised to 30°C and kept warm for 30 minutes. After the reaction was completed, LiOH was added to the system for neutralization to obtain a MAF polymer solution.

[0100] The molar ratio of m-phenylenediamine, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.15:1300:5:7;

[0101] The structural formula of MAF polymer is , the number average molecular weight is 37000;

[0102] (3) the KZW polymer solution of step (1) and the MAF polymer solution of step (2) are uniformly mixed as a spinning solution, and dry-wet spinning is performed, and the UV-resistant aramid fiber is obtained by the steps of spinning, stretching, washing with water at 50°C, drying at 102°C, dry heat stretching, oiling, heat setting and winding;

[0103] The molar ratio of KZW polymer to MAF polymer is 0.08:1;

[0104] The dry-wet spinning process parameters are as follows:

[0105] The spinning solution temperature was 20°C; the metering pump speed was 6 r / min, the spinneret speed was 12 m / min, and the spinneret specifications were φ0.04 mm × 400 holes;

[0106] After spinning, the fibers first enter an air bath and then a coagulation bath for stretching. The air bath height is 10 mm, the coagulation bath temperature is 22°C, the coagulation bath is a 41 wt% DMAc aqueous solution, and the stretching ratio is 3 times.

[0107] The dry heat stretching temperature is 300℃ and the dry heat stretching ratio is 4 times;

[0108] The oiling rate is 0.06wt%;

[0109] The heat setting temperature is 280°C and the heat setting time is 120s;

[0110] The winding speed is 250m / min.

[0111] The final UV-resistant aramid fiber has a fineness of 2dtex and a density of 1.45g / cm³; the UPF value of the UV-resistant aramid fiber is 70, and the UV transmittance is 1.5%; the breaking strength of the UV-resistant aramid fiber is 5.5GPa, the initial modulus is 63GPa, the elongation at break is 22%, the initial decomposition temperature is 530℃, and the residual carbon rate at 800℃ is 69%; after 100h of UV irradiation, the breaking strength retention rate of the UV-resistant aramid fiber is 97.5%, and the elongation at break retention rate is 96.5%.

[0112] Example 3

[0113] A method for preparing UV-resistant aramid fiber, comprising the following steps:

[0114] (1) Preparation of KZW polymer solution:

[0115] (1.1) Quinoline-2,7-diamine reacts with Br2 to generate KZW monomer. The hydrogen and carbon spectra of KZW monomer are as follows: Figure 8 and Figure 9 As shown;

[0116] The molar ratio of quinoline-2,7-diamine to Br2 is 1:1.25;

[0117] (1.2) Under inert gas, add DMAc and LiCl to a reactor. Add KZW monomer while stirring. After the KZW monomer is completely dissolved, cool to 0°C. Add isophthaloyl chloride in batches. Then, raise the temperature to 40°C and keep the reaction for 4 hours.

[0118] (1.3) LiOH is added to the reaction system for neutralization to obtain a KZW polymer solution;

[0119] The molar ratio of KZW monomer, isophthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.5:2200:6:8;

[0120] like Figure 14 As shown, the structural formula of KZW polymer is , the number average molecular weight is 6000;

[0121] (2) Preparation of MAF polymer:

[0122] Under inert gas protection, DMAc and LiCl were added to a reactor, and m-phenylenediamine was added under stirring. After m-phenylenediamine was completely dissolved, the temperature was lowered to 0°C, and isophthaloyl chloride was added in batches. The temperature was then raised to 40°C and kept warm for 15 minutes. After the reaction was completed, LiOH was added to the system for neutralization to obtain a MAF polymer solution.

[0123] The molar ratio of m-phenylenediamine, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.2:2200:6:8;

[0124] The structural formula of MAF polymer is , the number average molecular weight is 50000;

[0125] (3) the KZW polymer solution of step (1) and the MAF polymer solution of step (2) are uniformly mixed as a spinning solution, and dry-wet spinning is performed, and the UV-resistant aramid fiber is obtained by the steps of spinning, stretching, washing with water at 60°C, drying at 105°C, dry heat stretching, oiling, heat setting and winding;

[0126] The molar ratio of KZW polymer to MAF polymer is 0.11:1;

[0127] The dry-wet spinning process parameters are as follows:

[0128] The spinning solution temperature was 20°C; the metering pump speed was 9 r / min, the spinneret speed was 18 m / min, and the spinneret specifications were φ0.04 mm × 500 holes;

[0129] After spinning, the fibers first enter an air bath and then a coagulation bath for stretching. The air bath height is 12 mm, the coagulation bath temperature is 25°C, the coagulation bath is a 48 wt% DMAc aqueous solution, and the stretching ratio is 4 times.

[0130] The dry heat stretching temperature is 320℃ and the dry heat stretching ratio is 3 times;

[0131] The oiling rate is 0.07wt%;

[0132] The heat setting temperature is 300°C and the heat setting time is 90s;

[0133] The winding speed is 300m / min.

[0134] The final UV-resistant aramid fiber has a fineness of 3dtex and a density of 1.5g / cm³; the UPF value of the UV-resistant aramid fiber is 80, and the UV transmittance is 2%; the breaking strength of the UV-resistant aramid fiber is 6GPa, the initial modulus is 65GPa, the elongation at break is 24%, the initial decomposition temperature is 540℃, and the residual carbon rate at 800℃ is 72%; after 100h of UV irradiation, the breaking strength retention rate of the UV-resistant aramid fiber is 98%, and the elongation at break retention rate is 97.2%.

[0135] Example 4

[0136] A method for preparing UV-resistant aramid fiber, comprising the following steps:

[0137] (1) Preparation of KZW polymer solution:

[0138] (1.1) Quinoline-2,7-diamine is reacted with I2 to form KZW monomer. The hydrogen and carbon spectra of KZW monomer are as follows: Figure 10 and Figure 11 As shown;

[0139] Wherein, the molar ratio of quinoline-2,7-diamine to I2 is 1:1.15;

[0140] (1.2) Under inert gas, add DMAc and LiCl to a reactor. Add KZW monomer while stirring. Once KZW monomer is completely dissolved, cool to -5°C. Add isophthaloyl chloride in batches. Then, raise the temperature to 25°C and keep the reaction warm for 10 h.

[0141] (1.3) LiOH is added to the reaction system for neutralization to obtain a KZW polymer solution;

[0142] The molar ratio of KZW monomer, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.55:3100:7:9;

[0143] like Figure 15 As shown, the structural formula of KZW polymer is , the number average molecular weight is 8000;

[0144] (2) Preparation of MAF polymer:

[0145] Under inert gas protection, DMAc and LiCl were added to a reactor, and m-phenylenediamine was added under stirring. After m-phenylenediamine was completely dissolved, the temperature was lowered to -4°C, and isophthaloyl chloride was added in batches. The temperature was then raised to 25°C and kept warm for 40 minutes. After the reaction was completed, LiOH was added to the system for neutralization to obtain a MAF polymer solution.

[0146] The molar ratio of m-phenylenediamine, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.25:3100:7:9;

[0147] The structural formula of MAF polymer is , the number average molecular weight is 68000;

[0148] (3) the KZW polymer solution of step (1) and the MAF polymer solution of step (2) are uniformly mixed as a spinning solution, and dry-wet spinning is performed, and the UV-resistant aramid fiber is obtained by the steps of spinning, stretching, washing with water at 70°C, drying at 108°C, dry heat stretching, oiling, heat setting and winding;

[0149] The molar ratio of KZW polymer to MAF polymer is 0.16:1;

[0150] The dry-wet spinning process parameters are as follows:

[0151] The spinning solution temperature was 20°C; the metering pump speed was 4 r / min, the spinneret speed was 10 m / min, and the spinneret specifications were φ0.04 mm × 600 holes;

[0152] After spinning, the fibers first enter an air bath and then a coagulation bath for stretching. The air bath height is 15 mm, the coagulation bath temperature is 28°C, the coagulation bath is a 54 wt% DMAc aqueous solution, and the stretching ratio is 5 times.

[0153] The dry heat stretching temperature is 350℃ and the dry heat stretching ratio is 2 times;

[0154] The oiling rate is 0.09wt%;

[0155] The heat setting temperature is 350°C and the heat setting time is 60s;

[0156] The winding speed is 350m / min.

[0157] The final UV-resistant aramid fiber has a fineness of 4 dtex and a density of 1.55 g / cm³. The UPF value of the UV-resistant aramid fiber is 90, and the UV transmittance is 2.5%. The breaking strength of the UV-resistant aramid fiber is 6.3 GPa, the initial modulus is 67 GPa, the elongation at break is 26%, the initial decomposition temperature is 550°C, and the residual carbon rate at 800°C is 75%. After 100 hours of UV irradiation, the breaking strength retention rate of the UV-resistant aramid fiber is 98.5%, and the elongation at break retention rate is 97.9%.

[0158] Example 5

[0159] A method for preparing UV-resistant aramid fiber, comprising the following steps:

[0160] (1) Preparation of KZW polymer solution:

[0161] (1.1) Quinoline-2,7-diamine is reacted with F2 to form KZW monomer; the hydrogen spectrum and carbon spectrum of KZW monomer are as follows: Figure 5 and Figure 5 As shown;

[0162] The molar ratio of quinoline-2,7-diamine to F2 is 1:1.2;

[0163] (1.2) Under inert gas, add DMAc and LiCl to a reactor. Add KZW monomer while stirring. Once KZW monomer is completely dissolved, cool to -2°C. Add isophthaloyl chloride in batches. Then, raise the temperature to 35°C and maintain the reaction for 6 h.

[0164] (1.3) LiOH is added to the reaction system for neutralization to obtain a KZW polymer solution;

[0165] The molar ratio of KZW monomer, isophthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.6:4000:8:10;

[0166] like Figure 12 As shown, the structural formula of KZW polymer is , the number average molecular weight is 10000;

[0167] (2) Preparation of MAF polymer:

[0168] Under inert gas protection, DMAc and LiCl were added to a reactor, and m-phenylenediamine was added under stirring. After m-phenylenediamine was completely dissolved, the temperature was lowered to -2°C, and isophthaloyl chloride was added in batches. The temperature was then raised to 35°C and kept warm for 20 minutes. After the reaction was completed, LiOH was added to the system for neutralization to obtain a MAF polymer solution.

[0169] The molar ratio of m-phenylenediamine, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.3:4000:8:10;

[0170] The structural formula of MAF polymer is , the number average molecular weight is 80000;

[0171] (3) the KZW polymer solution of step (1) and the MAF polymer solution of step (2) are uniformly mixed as a spinning solution, and dry-wet spinning is performed, and the UV-resistant aramid fiber is obtained by the steps of spinning, stretching, washing with water at 80°C, drying at 110°C, dry heat stretching, oiling, heat setting and winding;

[0172] The molar ratio of KZW polymer to MAF polymer is 0.2:1;

[0173] The dry-wet spinning process parameters are as follows:

[0174] The spinning solution temperature was 20°C; the metering pump speed was 8 r / min, the spinneret speed was 15 m / min, and the spinneret specifications were φ0.04 mm × 800 holes;

[0175] After spinning, the fibers first enter an air bath and then a coagulation bath for stretching. The air bath height is 16 mm, the coagulation bath temperature is 30°C, the coagulation bath is a 60 wt% DMAc aqueous solution, and the stretching ratio is 6 times.

[0176] The dry heat stretching temperature is 280℃ and the dry heat stretching ratio is 5 times;

[0177] The oiling rate is 0.1wt%;

[0178] The heat setting temperature is 380°C and the heat setting time is 30s;

[0179] The winding speed is 400m / min.

[0180] The final UV-resistant aramid fiber has a fineness of 5dtex and a density of 1.6g / cm³; the UPF value of the UV-resistant aramid fiber is 100, and the UV transmittance is 3%; the breaking strength of the UV-resistant aramid fiber is 6.8GPa, the initial modulus is 70GPa, the elongation at break is 28%, the initial decomposition temperature is 560℃, and the residual carbon rate at 800℃ is 78%; after 100h of UV irradiation, the breaking strength retention rate of the UV-resistant aramid fiber is 99%, and the elongation at break retention rate is 98.6%.

Claims

1. A method for preparing UV-resistant aramid fiber, characterized by: The KZW polymer solution and the MAF polymer solution were mixed evenly as spinning solution, and the UV-resistant aramid fiber was prepared by dry-wet spinning. The structural formula of KZW polymer is The number average molecular weight is 2000-10000; the structural formula of MAF polymer is Number average molecular weight is 20,000 to 80,000; X is F, Cl, Br, or I; The molar ratio of KZW polymer to MAF polymer is 0.02 to 0.2:

1.

2. The method for preparing an ultraviolet-resistant aramid fiber according to claim 1, characterized in that: The preparation process of KZW polymer solution is as follows: first, quinoline-2,7-diamine is reacted with a halogen element to generate a KZW monomer; then, under the protection of an inert gas, DMAc and LiCl are added to a reactor, and the KZW monomer is added under stirring. After the KZW monomer is completely dissolved, the temperature is lowered to -8 to 0°C, isophthaloyl chloride is added in batches, and then the temperature is raised to 20 to 40°C and kept for reaction for 4 to 12 hours; finally, LiOH is added to the reacted system for neutralization to obtain a KZW polymer solution.

3. The method for preparing an ultraviolet-resistant aramid fiber according to claim 2, characterized in that: The molar ratio of quinoline-2,7-diamine to the halogen element is 1:1.05-1.25, and the molar ratio of KZW monomer, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.3-1.6:400-4000:4-8:6-10.

4. The method for preparing an ultraviolet-resistant aramid fiber according to claim 2, characterized in that: The halogen element is F2, Cl2, Br2 or I2.

5. The method for preparing an ultraviolet-resistant aramid fiber according to claim 1, characterized in that: The preparation process of MAF polymer is as follows: under the protection of inert gas, DMAc and LiCl are added to the reactor, and m-phenylenediamine is added under stirring. After the m-phenylenediamine is completely dissolved, the temperature is lowered to -8 to 0°C, and isophthaloyl chloride is added in batches. Then, the temperature is raised to 20 to 40°C and kept warm for 15 to 45 minutes. After the reaction is completed, LiOH is added to the system for neutralization to obtain a MAF polymer solution.

6. The method for preparing an ultraviolet-resistant aramid fiber according to claim 5, characterized in that: The molar ratio of m-phenylenediamine, isophthaloyl chloride, DMAc, LiCl and LiOH is 1:1.1-1.3:400-4000:4-8:6-10.

7. The method for preparing an ultraviolet-resistant aramid fiber according to claim 1, characterized in that: The wet and dry spinning process includes the following steps: spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting and winding. The dry-wet spinning process parameters are as follows: The spinning solution temperature is 20°C; The metering pump speed is 3-9r / min, the spinning speed is 6-18m / min, and the spinneret specifications are hole; After spinning, the yarn first enters an air bath and then a coagulation bath for stretching. The air bath height is 8 to 16 mm, the coagulation bath temperature is 20 to 30°C, and the coagulation bath is a DMAc aqueous solution with a concentration of 35 to 60 wt%; The water washing temperature is 40-80℃; Drying temperature is 100-110℃; The dry heat stretching temperature is 270-350°C, and the dry heat stretching ratio is 2-6 times; The heat setting temperature is 250-380°C, and the heat setting time is 30-180s.

8. An anti-ultraviolet aramid fiber prepared by the method according to any one of claims 1 to 7, characterized in that: The fineness of UV-resistant aramid fiber is 1-5 dtex and the density is 1.4-1.6 g / cm 3 ; The UPF value of UV-resistant aramid fiber is 60-100, and the UV transmittance is 1%-3%; After being irradiated with ultraviolet light for 100 hours, the breaking strength retention rate of the ultraviolet-resistant aramid fiber is 97-99%, and the breaking elongation retention rate is 95.8-98.6%.

9. The anti-ultraviolet aramid fiber according to claim 8, characterized in that: The breaking strength of the anti-ultraviolet aramid fiber is 5.2-6.8GPa, the initial modulus is 60-70GPa, the breaking elongation is 20-28%, the initial decomposition temperature is 520-560°C, and the residual carbon rate at 800°C is 65-78%.

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