CN116949586A - Production process for improving meta-aramid fiber breaking strength and heat resistance - Google Patents
Production process for improving meta-aramid fiber breaking strength and heat resistance Download PDFInfo
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- CN116949586A CN116949586A CN202310892158.3A CN202310892158A CN116949586A CN 116949586 A CN116949586 A CN 116949586A CN 202310892158 A CN202310892158 A CN 202310892158A CN 116949586 A CN116949586 A CN 116949586A
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- 229920006231 aramid fiber Polymers 0.000 title claims abstract description 76
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 238000009987 spinning Methods 0.000 claims abstract description 38
- 238000001816 cooling Methods 0.000 claims abstract description 34
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000000243 solution Substances 0.000 claims abstract description 29
- 239000004760 aramid Substances 0.000 claims abstract description 19
- 229920003235 aromatic polyamide Polymers 0.000 claims abstract description 19
- 239000011347 resin Substances 0.000 claims abstract description 18
- 229920005989 resin Polymers 0.000 claims abstract description 18
- YCGKJPVUGMBDDS-UHFFFAOYSA-N 3-(6-azabicyclo[3.1.1]hepta-1(7),2,4-triene-6-carbonyl)benzamide Chemical compound NC(=O)C1=CC=CC(C(=O)N2C=3C=C2C=CC=3)=C1 YCGKJPVUGMBDDS-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000007872 degassing Methods 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 11
- 239000006184 cosolvent Substances 0.000 claims abstract description 10
- 230000001112 coagulating effect Effects 0.000 claims abstract description 9
- 239000011259 mixed solution Substances 0.000 claims abstract description 6
- 238000007598 dipping method Methods 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 25
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 6
- 230000015271 coagulation Effects 0.000 claims description 5
- 238000005345 coagulation Methods 0.000 claims description 5
- ZMXDDKWLCZADIW-UHFFFAOYSA-N dimethylformamide Substances CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 4
- 229920000889 poly(m-phenylene isophthalamide) Polymers 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 abstract description 33
- 239000000835 fiber Substances 0.000 description 43
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 23
- 229910001628 calcium chloride Inorganic materials 0.000 description 23
- 239000001110 calcium chloride Substances 0.000 description 23
- 239000007864 aqueous solution Substances 0.000 description 8
- 238000007711 solidification Methods 0.000 description 8
- 230000008023 solidification Effects 0.000 description 8
- 238000002166 wet spinning Methods 0.000 description 7
- 230000001276 controlling effect Effects 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 230000001681 protective effect Effects 0.000 description 4
- 238000009864 tensile test Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 1
- 230000010485 coping Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012681 fiber drawing Methods 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229920006253 high performance fiber Polymers 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
- D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides
- D01F6/605—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides from aromatic polyamides
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D1/00—Treatment of filament-forming or like material
- D01D1/02—Preparation of spinning solutions
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
- D01D10/02—Heat treatment
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
- D01D10/06—Washing or drying
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/12—Stretch-spinning methods
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
- Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear
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- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Artificial Filaments (AREA)
Abstract
The invention relates to a production process for improving the breaking strength and heat resistance of meta-aramid fiber, which comprises the steps of dissolving poly-m-phenylene isophthalamide resin in sulfuric acid and an organic cosolvent for degassing, spinning the obtained meta-aramid spinning solution, drying, and then dipping in H 2 SO 4 And CaCl 2 Collecting the mixed solution in a coagulating bath to obtain the as-spun meta-aramid fiber; the pre-spun meta-aramid fiber is first 10-100 mm +.Prestretching at a min rate, cooling to room temperature after keeping a stretched state, cooling to room temperature after heat treatment for 0.5-6 h at 150-200 ℃, then mainly stretching at a rate of 10-100 mm/min at 200-300 ℃, cooling to room temperature after keeping a stretched state, and solidifying for 0.5-6 h at 200-300 ℃ under the stretched state.
Description
Technical Field
The invention belongs to the field of meta-aramid fiber manufacturing, and particularly relates to a production process for improving the breaking strength and heat resistance of meta-aramid fiber.
Background
The meta-aramid fiber is a high-performance fiber material with high strength, high modulus and excellent heat resistance, and has wide application prospect in the fields of aerospace, electrical insulation, protective materials and the like. In the process of preparing high performance meta-aramid fiber, the drawing process is a critical process step.
Current meta-aramid fiber drawing processes generally include two main steps: pretension and main stretch. Prestretching refers to slightly stretching the fiber at a lower temperature to reduce shrinkage and deformation of the fiber while increasing its degree of orientation and crystallinity. The main draw is to draw the fiber to a greater extent at elevated temperatures to further enhance the strength and modulus of the fiber.
However, the above stretching process has some problems. First, the fibers are prone to uneven strain and thermal decomposition due to the difficulty in controlling the drawing temperature and speed. Secondly, the surface quality of the fiber is easily polluted and damaged in the stretching process, and the quality and performance of the fiber are reduced. In addition, current drawing processes have certain limitations in controlling the fineness and crystallinity of the fibers.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a production process for improving the breaking strength and heat resistance of meta-aramid fiber, which ensures that the meta-aramid fiber is uniformly stretched and improves the breaking strength, surface quality and heat resistance of the fiber.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
a production process for improving the breaking strength and heat resistance of meta-aramid fiber comprises the following steps:
s1, dissolving poly m-phenylene isophthalamide resin in sulfuric acid and a cosolvent, wherein the cosolvent is one or more of N-methylpyrrolidone, N '-dimethylformamide and N, N' -dimethylacetamide, and then degassing to obtain meta-aramid spinning solution;
s2, spraying meta-aramid spinning solution, drying, and soaking in H 2 SO 4 And CaCl 2 Collecting the mixed solution in a coagulating bath to obtain the as-spun meta-aramid fiber;
s3, stretching and orienting the as-spun meta-aramid fiber according to the following process to improve the breaking strength and heat resistance of the meta-aramid fiber:
pre-stretching at a speed of 10-100 mm/min at 150-200 ℃, cooling to room temperature after keeping a stretched state, heat-treating at 150-200 ℃ for 0.5-6 h, cooling to room temperature, main-stretching at a speed of 10-100 mm/min at 200-300 ℃, cooling to room temperature after keeping a stretched state, and finally solidifying at 200-300 ℃ for 0.5-6 h under a stretched state.
Preferably, the ratio of the poly (m-phenylene isophthalamide) resin, sulfuric acid and the cosolvent in S1 is (1 to 3) kg: (1.9-2.5) L: (4.3-4.7) L.
Preferably, the degassing treatment in S1 is carried out at a vacuum level of 0.08 to 0.12MPa for 1 to 3 hours.
Preferably, the spinning described in S2 is performed at a rate of 10 to 200 mL/min.
Preferably, the drying in S2 is carried out at 100-120 ℃ for 120-180 min.
Preferably, S2 is H 2 SO 4 And CaCl 2 The mass percentage of the mixed solution is 45-60%, H 2 SO 4 And CaCl 2 Is 1:1 by volume.
Further, the temperature of the coagulating bath is 20-30 ℃, and the dipping operation is performed in the coagulating bath for 60-120 min.
Preferably, both the pre-stretching and the main stretching in S3 are performed at a relative humidity of 30% to 40%.
Further, the stretching multiple of the pre-stretching in the step S3 is 2-4 times, and the stretching multiple of the main stretching is 2-5 times.
Further, after the pre-stretching and the main stretching described in S3 are completed, the time for maintaining the stretched state is 0.5 to 6 hours.
Compared with the prior art, the invention has the following beneficial technical effects:
according to the production process for improving the breaking strength and heat resistance of meta-aramid fiber, the organic cosolvent is added into the sulfuric acid to reduce the influence of the sulfuric acid on a fiber matrix, and the spinnability, the stretchability, the fineness and the crystallinity control capability of the fiber are improved, so that fiber molecules are better arranged and oriented in the spinning and stretching processes. H 2 SO 4 And CaCl 2 The method is beneficial to solidification and solidification of the fiber, realizes uniform stretching of the meta-aramid fiber and optimization of the surface quality of the fiber by optimizing the stretching temperature and controlling the stretching speed, and realizes higher orientation degree, thereby obviously improving the strength and modulus of the fiber, wherein the fiber fineness is 4D, the traditional meta-aramid fiber is 1D, and the heat treatment and solidification play an important role in solidification and stabilization of the fiber, so that the meta-aramid fiber can bear larger mechanical load in the fields of aerospace, electrical insulation, protective materials and the like, and provides more reliable performance. The meta-aramid fiber can keep the mechanical property and structural stability in a high-temperature environment, so that the meta-aramid fiber becomes an ideal choice in the fields of aerospace, automobile engineering, protective materials and the like, and can cope with extreme temperature and severe working conditions.
Drawings
FIG. 1 is an XRD spectrum of meta-aramid fiber obtained in example 1 of the present invention.
FIG. 2 is an SEM image of meta-aramid fiber obtained in example 1 of the present invention.
FIG. 3 is a thermogravimetric curve of meta-aramid fiber obtained in example 1 of the present invention.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to specific examples and drawings, which are given by way of illustration and not limitation.
The invention relates to a production process for improving the breaking strength and heat resistance of meta-aramid fiber, which specifically comprises the following steps:
step 1: dissolving the poly m-phenylene isophthalamide resin by using a mixed solvent, and carrying out degassing treatment after complete dissolution to obtain meta-aramid spinning solution;
firstly, 1.9 to 2.5L of concentrated sulfuric acid is used as a main solvent to be mixed with 4.3 to 4.7L of cosolvent (one or more of N-methylpyrrolidone, N '-dimethylformamide and N, N' -dimethylacetamide), so as to ensure the suitability of the solvent. Then, 1-3 kg of the poly (m-phenylene isophthalamide) resin is gradually added into the solvent, and the poly (m-phenylene isophthalamide) resin is promoted to be completely dissolved by a mechanical stirring mode, so that a viscous solution with the mass percent of 10-30% is formed. In order to remove internal gas in the solution, the solution is placed under a vacuum degree of 0.08-0.12 MPa for degassing treatment for 1-3 h.
The purpose of this process is to ensure homogeneity and stability of the solution. By mixing the main solvent and the co-solvent, the properties of the solvent can be adjusted to improve the spinnability and stretchability of the fiber, and to improve the quality and stability of the fiber. Meanwhile, the poly m-phenylene isophthalamide resin is completely dissolved, so that the uniform distribution of the components of the fiber can be ensured, and the situation of caking or non-uniformity in the fiber is avoided. Finally, through degassing treatment, bubbles and gas in the solution can be removed, the possibility of air holes or defects in the fiber preparation process is reduced, and a foundation is laid for obtaining high-performance meta-aramid fiber.
Step 2: pouring meta-aramid spinning solution into a wet spinning machine, spraying at a speed of 10-200 mL/min through a spinneret plate with 20-100 holes (the hole diameters are 0.08mm, the efficiency of 100 holes is higher than that of 20 holes, and the spinneret plates with different specifications are required to be replaced in the wet spinning machine in specific operation), collecting the spun fiber, drying at 100-120 ℃ for 120-180 min, and then passing through sulfuric acid (H) 2 SO 4 ) And calcium chloride (CaCl) 2 ) Coagulating bath 60% to ultra high at 20-30 ℃ composed of mixed water solution120min (i.e. immersed in H 2 SO 4 And CaCl 2 The volume ratio of the mixed aqueous solution is 1:1, and the mixed aqueous solution is 45-60% by mass and is collected by a roller to obtain the as-spun meta-aramid fiber;
by controlling the spinning rate, precise control and regulation of the spinning process can be achieved to achieve the desired fiber morphology and properties. H 2 SO 4 And CaCl 2 The solidification and solidification of the fiber are facilitated, and the structure of the fiber yarn is stabilized by contacting with the mixed solution, so that the fiber yarn has ideal orientation degree and mechanical property. The function of the roller is to wind the filaments in order to form a disposable fiber bundle. This step facilitates subsequent handling and processing of the fibers, which lays a foundation for achieving final product preparation.
The process can effectively improve the preparation efficiency and quality stability of the meta-aramid fiber, and can obtain the high-quality meta-aramid fiber with excellent performance by precisely controlling the spinning rate and optimizing the formula of the coagulating solution. Meanwhile, the application of the roller collecting step is helpful for ensuring the uniformity and the treatability of the fibers, and provides convenience for the subsequent process.
Step 3: stretching and orienting the as-spun meta-aramid fiber, specifically, pre-stretching for 2-4 times at the temperature of 150-200 ℃ at the speed of 10-100 mm/min and the relative humidity of 30-40%, keeping the stretched state for 0.5-6 h, stopping heating, cooling to room temperature, heating to the temperature of 150-200 ℃ again for 0.5-6 h, cooling to the room temperature, primarily stretching for 2-5 times at the temperature of 200-300 ℃ at the speed of 10-100 mm/min and the relative humidity of 30-40%, keeping the stretched state for 0.5-6 h, stopping heating, cooling to the room temperature, heating to the stretched state again for 200-300 ℃ for 0.5-6 h, and cooling to the room temperature;
the process and the corresponding parameters can be well controlled and regulated in the fiber preparation process to obtain meta-aramid fiber so as to strengthen the strength and modulus of the fiber. Through reasonable temperature, stretching speed, stretching proportion and air relative humidity control, optimization of fiber structure and improvement of performance can be realized. At the same time, the proper time and cooling process of the heat treatment stage also play an important role in the solidification and stabilization of the fibers.
Example 1:
concentrated sulfuric acid (2.5L) and N-methyl pyrrolidone (4.3L) are blended and stirred uniformly, then 1kg of poly m-phenylene isophthalamide resin is added, and the mixture is stirred until the poly m-phenylene isophthalamide resin is completely dissolved; and then the solution is placed under the vacuum degree of 0.1MPa for degassing treatment for 2 hours, so as to obtain the meta-aramid spinning solution.
Pouring meta-aramid spinning solution into a wet spinning machine, spinning at a rate of 100mL/min by using a 20-hole spinneret, collecting and drying at 100deg.C for 180min, and passing through sulfuric acid (H) 2 SO 4 ) And calcium chloride (CaCl) 2 ) Coagulation bath at 25deg.C for 100min (H) 2 SO 4 And CaCl 2 The volume ratio of the raw spinning meta-aramid fiber is 1:1, and the mass percentage of the mixed aqueous solution is 45 percent) and then is collected by a roller, so as to obtain the raw spinning meta-aramid fiber.
Pre-stretching the pre-spun meta-aramid fiber in a tensile testing machine at 150 ℃ at a speed of 10mm/min and relative humidity of 40%, and stopping heating after the pre-stretched meta-aramid fiber is stretched to 2 times and kept in a stretched state for 0.5 h; cooling to room temperature, then heating to 200 ℃ again for heat treatment for 0.5h, cooling to room temperature, heating to 200 ℃, stretching to 2 times at a speed of 10mm/min under 40% relative humidity, keeping the stretched state for 0.5h, stopping heating, cooling to room temperature, heating to 200 ℃ again in the stretched state for solidification treatment for 6h, cooling to room temperature, and taking down the fiber to obtain the meta-aramid fiber.
Example 2:
concentrated sulfuric acid (2.5L) and N-methyl pyrrolidone (4.3L) are blended and stirred uniformly, then 1kg of poly m-phenylene isophthalamide resin is added, and the mixture is stirred until the poly m-phenylene isophthalamide resin is completely dissolved; and then the solution is placed under the vacuum degree of 0.12MPa for degassing treatment for 2 hours, so as to obtain the meta-aramid spinning solution.
Pouring meta-aramid spinning solution into a wet spinning machine, spinning at a rate of 200mL/min by using a 100-hole spinneret, collecting and drying at 120deg.C for 120min, and passing through sulfuric acid (H) 2 SO 4 ) And calcium chloride (CaCl) 2 ) Coagulation bath at 20deg.C for 90min (H) 2 SO 4 And CaCl 2 The volume ratio of the raw spinning meta-aramid fiber is 1:1, and the mass percentage of the mixed aqueous solution is 50 percent) and then is collected by a roller, so as to obtain the raw spinning meta-aramid fiber.
Pre-stretching the pre-spun meta-aramid fiber in a tensile testing machine at 200 ℃ at a speed of 100mm/min and relative humidity of 30%, and stopping heating after the pre-stretched meta-aramid fiber is stretched to 4 times and kept in a stretched state for 6 hours; cooling to room temperature, then heating to 300 ℃ again, heat-treating for 6 hours, cooling to room temperature, heating to 300 ℃, stretching to 5 times at a speed of 10mm/min under 30% relative humidity, keeping the stretched state for 6 hours, stopping heating, cooling to room temperature, heating to 210 ℃ again in the stretched state, solidifying for 5 hours, cooling to room temperature, and taking down the fiber to obtain the meta-aramid fiber.
Example 3:
blending concentrated sulfuric acid (1.9L) and N-methyl pyrrolidone (3.4L) and uniformly stirring, then adding 3kg of poly m-phenylene isophthalamide resin, and stirring until the mixture is completely dissolved; and then the solution is placed under the vacuum degree of 0.11MPa for degassing treatment for 2 hours, so as to obtain the meta-aramid spinning solution.
Pouring meta-aramid spinning solution into a wet spinning machine, spinning at a rate of 200mL/min by using a 20-hole spinneret, collecting and drying at 110deg.C for 150min, and passing through sulfuric acid (H) 2 SO 4 ) And calcium chloride (CaCl) 2 ) Coagulation bath at 30deg.C for 60min (H) 2 SO 4 And CaCl 2 The volume ratio of the raw spinning meta-aramid fiber is 1:1, and the mass percentage of the mixed aqueous solution is 60 percent) and then is collected by a roller, so as to obtain the raw spinning meta-aramid fiber.
Pre-stretching the pre-spun meta-aramid fiber in a tensile testing machine at 150 ℃ at a speed of 10mm/min and a relative humidity of 32%, and stopping heating after the pre-stretched meta-aramid fiber is stretched to 2 times and kept in a stretched state for 0.5 h; cooling to room temperature, then heating to 200 ℃ again, heat-treating for 0.5h, cooling to room temperature, heating to 200 ℃, stretching to 2 times at a speed of 10mm/min under the relative humidity of 32%, keeping the stretched state for 0.5h, stopping heating, cooling to room temperature, heating to 260 ℃ again in the stretched state, solidifying for 3h, cooling to room temperature, and taking down the fiber to obtain the meta-aramid fiber.
Example 4:
concentrated sulfuric acid (2.5L) and N, N' -dimethylformamide (4.6L) are blended and stirred uniformly, and then 1kg of poly m-phenylene isophthalamide resin is added and stirred until the poly m-phenylene isophthalamide resin is completely dissolved; and then the solution is placed under the vacuum degree of 0.08MPa for degassing treatment for 2 hours, and the meta-aramid spinning solution is obtained.
Pouring meta-aramid spinning solution into a wet spinning machine, spinning at a rate of 200mL/min by using a 20-hole spinneret, collecting and drying at 110deg.C for 160min, and passing through sulfuric acid (H) 2 SO 4 ) And calcium chloride (CaCl) 2 ) Coagulating bath at 28deg.C for 120min (H) 2 SO 4 And CaCl 2 The volume ratio of the raw spinning meta-aramid fiber is 1:1, and the mass percentage of the mixed aqueous solution is 55 percent) and then is collected by a roller, so as to obtain the raw spinning meta-aramid fiber.
Pre-stretching the pre-spun meta-aramid fiber in a tensile testing machine at 150 ℃ at a speed of 10mm/min and relative humidity of 36%, and stopping heating after the pre-stretched meta-aramid fiber is stretched to 2 times and kept in a stretched state for 0.5 h; cooling to room temperature, then heating to 200 ℃ again, heat-treating for 0.5h, cooling to room temperature, heating to 200 ℃, stretching to 2 times at a speed of 10mm/min under the relative humidity of 36% and keeping the stretched state for 0.5h, stopping heating, cooling to room temperature, heating to 300 ℃ again in the stretched state, solidifying for 0.5h, cooling to room temperature, and taking down the fiber to obtain the meta-aramid fiber.
Example 5:
concentrated sulfuric acid (2.5L) and N, N' -dimethylacetamide (4.7L) are blended and stirred uniformly, and then 1kg of poly m-phenylene isophthalamide resin is added and stirred until the poly m-phenylene isophthalamide resin is completely dissolved; and then the solution is placed under the vacuum degree of 0.09MPa for degassing treatment for 2 hours, so as to obtain the meta-aramid spinning solution.
Pouring meta-aramid spinning solution into a wet spinning machine, spinning at a rate of 200mL/min by using a 20-hole spinneret, collecting and drying at 115 ℃ for 140min, and passing through sulfuric acid (H) 2 SO 4 ) And calcium chloride (CaCl) 2 ) Coagulating bath at 28deg.C for 120min (H) 2 SO 4 And CaCl 2 The volume ratio of the raw material to the mixed aqueous solution is 1:1, and the mixed aqueous solution is 50 percent by mass and is collected by a roller to obtain the as-spun meta-aramid fiberDimension.
Pre-stretching the pre-spun meta-aramid fiber in a pre-stretching tester at the temperature of 150 ℃ at the speed of 10mm/min and the relative humidity of 38%, and stopping heating after the pre-stretched meta-aramid fiber is stretched to 2 times and kept in a stretched state for 0.5 h; cooling to room temperature, then heating to 200 ℃ again, heat-treating for 0.5h, cooling to room temperature, heating to 200 ℃, stretching to 2 times at a speed of 10mm/min under the relative humidity of 38%, keeping the stretched state for 0.5h, stopping heating, cooling to room temperature, heating to 220 ℃ again in the stretched state, solidifying for 1.5h, cooling to room temperature, and taking down the fiber to obtain the meta-aramid fiber.
FIG. 1 is an XRD spectrum of a meta-aramid fiber, and peaks occurring in the diffraction angle range of 20-30 deg. correspond to the crystalline structure of the meta-aramid fiber.
As can be seen from the SEM image of FIG. 2, the meta-aramid fiber obtained by the invention has the advantages of complete structure, smooth surface, uniform diameter, certain pre-orientation, and parallel arrangement of the fibers, thereby effectively increasing the mechanical properties of the fiber.
Fig. 3 is a thermal decomposition curve of the meta-aramid fiber obtained in the present invention, and it can be seen that the meta-aramid fiber starts to decompose when the temperature reaches 400 degrees celsius, and remains 50% when the temperature reaches 700 degrees celsius. This also demonstrates the excellent heat resistance of meta-aramid, which makes it an ideal choice in the fields of aerospace, automotive engineering, protective materials, etc., capable of coping with extreme temperatures and severe operating conditions.
The mechanical properties of the meta-aramid fiber of the invention were tested to obtain the results shown in Table 1. TABLE 1 intermediate aramid fiber break strength and initial modulus of up to 5.52cN/dtex, respectively -1 And 108.11cN/dtex -1 Compared with the current spun fiber mainly drawn by pre-stretching and main stretching, the spinning fiber is respectively improved by 44.5 percent and 29.3 percent.
TABLE 1 mechanical Properties of meta-aramid fiber
| Breaking strength/(cN dtex) -1 ) | Initial modulus/(cN dtex) -1 ) |
| 5.52 | 108.11 |
Claims (10)
1. The production process for improving the breaking strength and the heat resistance of meta-aramid fiber is characterized by comprising the following steps of:
s1, dissolving poly m-phenylene isophthalamide resin in sulfuric acid and a cosolvent, wherein the cosolvent is one or more of N-methylpyrrolidone, N '-dimethylformamide and N, N' -dimethylacetamide, and then degassing to obtain meta-aramid spinning solution;
s2, spraying meta-aramid spinning solution, drying, and soaking in H 2 SO 4 And CaCl 2 Collecting the mixed solution in a coagulating bath to obtain the as-spun meta-aramid fiber;
s3, stretching and orienting the as-spun meta-aramid fiber according to the following process to improve the breaking strength and heat resistance of the meta-aramid fiber:
pre-stretching at a speed of 10-100 mm/min at 150-200 ℃, cooling to room temperature after keeping a stretched state, heat-treating at 150-200 ℃ for 0.5-6 h, cooling to room temperature, main-stretching at a speed of 10-100 mm/min at 200-300 ℃, cooling to room temperature after keeping a stretched state, and finally solidifying at 200-300 ℃ for 0.5-6 h under a stretched state.
2. The process for producing an improved meta-aramid fiber having improved breaking strength and heat resistance according to claim 1, wherein the ratio of the poly (m-phenylene isophthalamide) resin, sulfuric acid and co-solvent in S1 is (1 to 3) kg: (1.9-2.5) L: (4.3-4.7) L.
3. The process for improving the breaking strength and heat resistance of meta-aramid fiber according to claim 1, wherein the degassing treatment in S1 is performed at a vacuum degree of 0.08 to 0.12MPa for 1 to 3 hours.
4. The process for improving the breaking strength and heat resistance of meta-aramid fiber as claimed in claim 1, wherein the spinning in S2 is performed at a rate of 10 to 200 mL/min.
5. The process for improving the breaking strength and the heat resistance of meta-aramid fiber according to claim 1, wherein the drying of S2 is performed at 100-120 ℃ for 120-180 min.
6. The process for improving the breaking strength and heat resistance of meta-aramid fiber according to claim 1, wherein S2 is H 2 SO 4 And CaCl 2 The mass percentage of the mixed solution is 45-60%, H 2 SO 4 And CaCl 2 Is 1:1 by volume.
7. The process for improving the breaking strength and heat resistance of meta-aramid fiber according to claim 6, wherein the temperature of the coagulation bath is 20-30 ℃ and the dipping operation is performed in the coagulation bath for 60-120 min.
8. The process for improving the breaking strength and heat resistance of meta-aramid fiber according to claim 1, wherein the pre-stretching and the main stretching in S3 are performed under the condition that the relative humidity is 30% to 40%.
9. The process for improving the breaking strength and heat resistance of meta-aramid fiber according to claim 8, wherein the stretching ratio of the pre-stretching in S3 is 2 to 4 times and the stretching ratio of the main stretching is 2 to 5 times.
10. The process for improving the breaking strength and heat resistance of meta-aramid fiber as claimed in claim 9, wherein the time for maintaining the stretched state after the pre-stretching and the main stretching in S3 are completed is 0.5 to 6 hours.
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