阅读说明：本技术 一种高模量对位芳纶纤维的制备方法 (Preparation method of high-modulus para-aramid fiber ) 是由 唐凯 侯春蕾 季先恒 于宏广 杨文华 于 2020-05-21 设计创作，主要内容包括：本发明提供一种高模量对位芳纶纤维的制备方法,它采用低温缩聚的方法先制备特性黏度为7.5～8.5dL/g的聚对苯二甲酰对苯二胺(PPTA)聚合体；利用高浓度硫酸将聚合体溶解制备纺丝原液,通过干喷湿纺的方法获得纤维丝束,然后通过洗涤、中和、洗涤、干燥、上油、卷绕等工序获得高模量对位芳纶纤维,该PPTA纤维的模量为850～1000g/D,特性黏度为7.0～8.0dL/g。采用本方法制备的高模量对位芳纶纤维具有高强度、高模量、降解小、高晶度光泽、毛丝少、力学性能优越,干燥时间短,能耗低,干燥设备国产化替代进口,突破了干燥设备的技术封锁,加速了行业发展进度。(The invention provides a preparation method of high-modulus para-aramid fiber, which comprises the steps of firstly preparing a poly-p-phenylene terephthalamide (PPTA) polymer with the intrinsic viscosity of 7.5-8.5D L/g by adopting a low-temperature polycondensation method, dissolving the polymer by utilizing high-concentration sulfuric acid to prepare spinning solution, obtaining a fiber tow by a dry-jet wet spinning method, and then obtaining the high-modulus para-aramid fiber by the procedures of washing, neutralizing, washing, drying, oiling, winding and the like, wherein the modulus of the PPTA fiber is 850-1000 g/D, the intrinsic viscosity is 7.0-8.0D L/g.)

1. The invention provides a preparation method of high-modulus para-aramid fiber, which comprises the following steps:

(1) preparation of the polymer: p-phenylenediamine (PPD) was dissolved in N-methylpyrrolidone/calcium chloride (NMP/CaCl) in a blending tank under nitrogen protection₂) Stirring and mixing the mixture in a solvent uniformly, transferring the mixture to a reactor, controlling the temperature in a jacket of the reactor to be-5-0 ℃ by using a condensing agent, adding TPC in twice, wherein the molar ratio of TPC to PPD is 1.001-1.002: 1, adding 30-50% of TPC for reaction for 8-15 seconds for the first time, then cooling to-5-0 ℃, adding the rest TPC for reaction for 30min for the second time, transferring the reaction mixture to a neutralization tank, adding 8-15% of NaOH solution for neutralization to neutrality, washing the mixture for 8-10 times by using deionized water in a grading manner, and drying the mixture by using steam at 120-160 ℃ to obtain PPTA with the water content of less than 100ppm and the intrinsic viscosity of 7.5-8.5 d L/g;

(2) preparing a spinning stock solution, namely mixing and stirring PPTA with the intrinsic viscosity of 7.5-8.5 d L/g and sulfuric acid with the concentration of 100 +/-0.2% in a multistage partition jacket at the temperature of 80-100 ℃ under the sealing of nitrogen, and then filtering to prepare the spinning stock solution with the mass concentration of 19.8-22%;

(3) dry-jet wet spinning: extruding a spinning stock solution through a gear pump, spraying the spinning stock solution out of a spinneret plate, enabling tows to pass through an air layer with the thickness of 2-7 mm, rapidly drawing the stock solution trickle at the speed of the drawing ratio of 4-10, enabling the spun filaments to enter a coagulating bath with the temperature of 0-5 ℃ to be frozen, coagulated and formed, enabling the sulfuric acid concentration in the coagulating bath to be 0-10%, washing the tows with water, neutralizing with calcium hydroxide, washing with water again, and then drying, oiling and winding;

(4) multistage drying technology: drying the washed tows at 100-200 ℃, controlling the tension within the range of 0-1 cN/dtex, controlling the drying time to be 2-6 seconds and the water content to be 7-10%, then heating the tows on a high-temperature heating roller at 350-450 ℃, controlling the heat setting time to be 0.5-1 second, controlling the fiber tension within the range of 1-4 cN/dtex in the heat setting process, and obtaining the para-aramid high-modulus product with the modulus of 850-1000 g/D.

2. The preparation method of high modulus para-aramid fiber according to claim 1, characterized in that: in the multistage drying technology, the heating roller is dried in two stages, the primary drying temperature is 100-200 ℃, and the secondary drying temperature is 350-450 ℃.

3. The preparation method of high modulus para-aramid fiber according to claim 1, characterized in that: the winding speed in the dry-jet wet spinning process is 150-300 m/min.

Technical Field

The invention relates to the technical field of polymer material synthesis, in particular to a preparation method of high-modulus para-aramid fiber.

Background

The high-modulus para-aramid fiber is a high-performance fiber material and is prepared by adding PPD and TPC in NMP/CaCl₂Carrying out low-temperature polycondensation in a solvent system, generating HCl in the reaction process, needing alkali metal salt for neutralization, washing the synthesized PPTA resin by water usually to remove residual solvent and salt, and drying to remove water; dissolving PPTA in sulfuric acid to prepare a liquid crystal solution, and obtaining a fiber tow by a dry-jet wet spinning technology; and (3) carrying out water washing, neutralization and water washing on the fiber tows to remove sulfuric acid in the fibers, and carrying out high-temperature setting to obtain the high-modulus fibers. Due to the excellent mechanical property, the high-strength high-toughness high-tenacity composite material is an important basic material which is widely applied to important fields such as safety protection, tires, rubber products, outdoor optical cables and advanced composite materials.

CN102383218A discloses a high-strength high-modulus para-aramid fiber, wherein a third monomer 2, 5-diamino Yy-phenyl (Y is CN, NO) is added in the polymerization process₂One of them), 3, 4-diaminodiphenyl ether, a third monomer, was added by the company of imperial japan, 2- (4-aminophenyl) -5(6) -aminobenzimidazole, a third monomer, was introduced by the company of camore russia for copolymerization, and the obtained polymer syrup could be directly wet-spun, with the advantages that: improves the solubility of the polymer in a solvent system, saves the technological links of water washing, drying and sulfuric acid dissolution in the production process of the polymer, reduces the corrosion of the device, and adopts the related technology ofUS4,075,172, US4,342,715, US4,525,384, Russian patents RU2,074,182 and RU2,130,980 and the like, but in the production of high-modulus para-aramid fibers by introducing a third monomer, the production and manufacturing technology has the problems of high cost, high solvent recovery difficulty, high environmental protection pressure and the like.

CN102154727A discloses a high-strength poly-p-phenylene terephthamide fiber and a preparation method thereof, which discloses that the modulus of the poly-p-phenylene terephthamide fiber is 350-650 g/D, and CN102251306B application discloses a high-modulus poly-p-phenylene terephthamide fiber and a preparation method thereof, which discloses an on-line heat treatment mode in a drying process and an off-line heat treatment mode after drying, wherein the on-line treatment process comprises the following steps: drying the neutralized wet yarn at 120-140 ℃ by using a drum dryer, heating to 200-240 ℃ at the drying rear section, wherein the tension is 1-10 g/D, drying for 1-60 seconds to obtain the dry yarn modulus of 600-800 g/D, then drying the dry yarn by using 2-8 heat cylinders, wherein the tension is 1-10 g/D, and drying for 1-60 seconds to obtain the 800-1000 g/D high-modulus poly-p-phenylene terephthalamide fiber at 400-500 ℃ by using 2-8 heat cylinders.

Aiming at the problems of the high-modulus poly-p-phenylene terephthamide fiber process at present, a method for producing the high-modulus para-aramid fiber is needed to be researched and developed, which overcomes the defects of low modulus, reduced polymer degradation degree, shortened high-temperature drying time, reduced damage of continuous high temperature to a fiber microstructure, enhanced mechanical property of the high-modulus para-aramid fiber, accelerated progress of localization substitution of key equipment for import and reduced cost, and solves the problems of high cost caused by introduction of a third monomer, low modulus of a traditional dry-jet wet spinning method, reduced fiber strength caused by long drying time, more broken filaments, low economic benefit and the like. The invention adopts low-temperature polycondensation, dry-jet wet spinning and multi-stage drying technologies, optimizes equipment transformation and can solve the problems of PPTA degradation, low modulus, long drying time, more broken filaments and the like.

Disclosure of Invention

The invention aims to provide a preparation method of high-modulus para-aramid fiber, which adopts low-temperature polycondensation, dry-jet wet spinning and multi-stage drying technologies, optimizes equipment transformation, can solve the problems of PPTA degradation, low modulus, long drying time, more broken filaments and the like, and can realize efficient, stable and high-quality continuous production of the high-modulus para-aramid fiber.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a preparation method of high-modulus para-aramid fiber comprises the following steps:

(1) preparation of the polymer: p-phenylenediamine (PPD) was dissolved in N-methylpyrrolidone/calcium chloride (NMP/CaCl) in a blending tank under nitrogen protection₂) Stirring and mixing the mixture in a solvent uniformly, transferring the mixture to a reactor, controlling the temperature in a jacket of the reactor to be-5-0 ℃ by using a condensing agent, adding TPC in twice, wherein the molar ratio of TPC to PPD is 1.001-1.002: 1, adding 30-50% of TPC for reaction for 8-15 seconds for the first time, then cooling to-5-0 ℃, adding the rest TPC for reaction for 30min for the second time, transferring the reaction mixture to a neutralization tank, adding 8-15% of NaOH solution for neutralization to neutrality, washing the mixture for 8-10 times by using deionized water in a grading manner, and drying the mixture by using steam at 120-160 ℃ to obtain PPTA with the water content of less than 100ppm and the intrinsic viscosity of 7.5-8.5 d L/g;

(2) preparing a spinning stock solution, namely mixing and stirring PPTA with the intrinsic viscosity of 7.5-8.5 d L/g and sulfuric acid with the concentration of 100 +/-0.2% in a multistage partition jacket at the temperature of 80-100 ℃ under the sealing of nitrogen, and then filtering to prepare the spinning stock solution with the mass concentration of 19.8-22%;

(3) dry-jet wet spinning: extruding a spinning stock solution through a gear pump, spraying the spinning stock solution out of a spinneret plate, enabling tows to pass through an air layer with the thickness of 2-7 mm, rapidly drawing the stock solution trickle at the speed of the drawing ratio of 4-10, enabling the spun filaments to enter a coagulating bath with the temperature of 0-5 ℃ to be frozen, coagulated and formed, enabling the sulfuric acid concentration in the coagulating bath to be 0-10%, washing the tows with water, neutralizing with calcium hydroxide, washing with water again, and then drying, oiling and winding;

(4) multistage drying technology: drying the washed tows at 100-200 ℃, controlling the tension within the range of 0-1 cN/dtex, controlling the drying time to be 2-6 seconds and the water content to be 7-10%, then heating the tows on a high-temperature heating roller at 350-450 ℃, controlling the heat setting time to be 0.5-1 second, controlling the fiber tension within the range of 1-4 cN/dtex in the heat setting process, and obtaining the para-aramid high-modulus product with the modulus of 850-1000 g/D.

As an improvement, the heating roller in the multistage drying technology is divided into two stages for drying, the primary drying temperature is 100-200 ℃, and the secondary drying temperature is 350-450 ℃.

As an improvement, the winding speed in the dry-jet wet spinning process is 150-300 m/min.

The invention has the following advantages: (1) the high-modulus para-aramid fiber has high production continuity; (2) the preparation process of the spinning solution reduces the degradation degree of the polymer; (3) the air layer height, the drafting ratio and the coagulating bath temperature are effectively controlled in the dry-jet wet spinning process, so that the high strength and high modulus performance of the fiber are maintained; (4) the drying efficiency of fibre moisture has been improved to the hierarchical drying technique, has shortened drying time, reduces the structural defect that the stoving in-process fibre produced, improves the fibre performance to the combination of hierarchical drying technique and home-made high temperature forming roller can reduce the energy consumption to a certain extent, reaches energy-conserving purpose, reduces product cost.

Drawings

FIG. 1 is a process flow diagram of a preparation method of high modulus para-aramid fiber.

FIG. 2 is a schematic diagram of a heat setting process flow in a preparation method of high modulus para-aramid fiber.

Detailed Description

The invention is described in further detail below with reference to the figures and examples.

The following examples are the heat setting process flow of the preparation method of the high modulus para-aramid fiber, and refer to the attached drawings 1 and 2.