A high-speed spinning process suitable for a variety of polyaramid fibers

Abstract

The application discloses a high-speed spinning process suitable for various aramid fibers, which comprises the following steps: spinning dope is spun through a spinneret, enters a coagulation bath after an air interval of 5-50 mm, is subjected to plasticization and coagulation, washing, drying, heat treatment and oiling, and is wound to obtain aramid fiber, the spinning dope is a mixture of aromatic polyamide with a specific viscosity of 1.2-7.0, an amide solvent and a cosolvent, the concentration of the aromatic polyamide in the spinning dope is 5-25%wt, and the concentration of the cosolvent is 1-7.5%wt; the concentration of the amide solvent in the coagulation bath is 30-60%wt; the concentration of the amide solvent in the plasticization coagulation bath is 20-30%wt; and the spinning speed of the aramid fiber is at least 45-600 m / min, so that aramid fiber with better and more stable performance can be obtained, the spinning process is suitable for various aramid fibers, the spinning speed of different aramid fibers is improved, and high-efficiency spinning production is realized.

Description

TECHNICAL FIELD

[0001] The application relates to a high-speed spinning process suitable for various polyaramid fibers, in particular to a dry-wet spinning process suitable for various polyaramid fibers, and belongs to the technical field of high-performance fiber spinning. BACKGROUND

[0002] The aromatic polyamide fiber is a high-tech material with excellent mechanical and thermal properties, and is widely used in the fields of national defense and military industry and optical cable rubber. The material prepared by using the aromatic polyamide fiber can be used in the protection field, such as a cutting-resistant and temperature-resistant glove, a cutting-resistant and temperature-resistant fabric and a temperature-resistant and high-strength sewing thread, and has a wide application prospect. In the prior art, the fiber materials such as aramid III, meta-aramid and arnosulfon are usually prepared by using a wet spinning process. Since the front-end spinning speed is low (10-15 m / min), the efficiency is low, the mechanical property is poor, the economic cost is relatively high, and the large-scale production is not facilitated.

[0003] In order to improve the related problems in the wet spinning of the aromatic polyamide fiber, the patent application with the publication number CN106283254A discloses a method for preparing meta-aramid filaments by using a dry-wet spinning process. The process steps include spinning solution preparation, spinning, coagulation, hot water drawing, washing, oil immersion, drying, hot drawing, heat setting, oiling and winding. In the actual production process, the spinning speed of the meta-aramid filaments prepared by using the method is at least increased by 2.5 times or more than the wet spinning technology, and the prepared meta-aramid filaments have a smooth surface, few holes and good mechanical properties. For example, the breaking strengths of the meta-aramid filaments prepared in the examples 1-3 of the patent are 4.5 cn / dtex, 4.8 cn / dtex and 5.1 cn / dtex respectively. The patent application with the publication number CN104278338A further discloses a gel spinning method for manufacturing aramid III fiber. The method also adopts the dry-wet spinning process, and specifically adopts the processes of spinning, a first coagulation bath, a second coagulation bath (plasticizing and drawing), washing, oiling, drying and heat setting to prepare the finished fiber. The method can be used for improving the stability of the spinning process and the quality of the fiber product by controlling the intrinsic viscosity of the spinning solution polymer and the configuration of the organic solvent in the coagulation liquid. The gel spinning speed can reach 30-100 m / min, and the strength of the aramid III fiber gel filament reaches 5.8 GPa.

[0004] From the above, in order to solve the problems of low efficiency and poor mechanical properties of the finished fiber in the wet spinning process, a dry-wet spinning process is used to propose a special spinning method for different types of aramid fiber materials. For example, in the meta-aramid spinning, the spinning speed and fiber breaking strength can be appropriately improved by specific dry-wet spinning parameter control. In the spinning of aramid III fiber, the spinning speed and mechanical properties can be improved by matching the viscosity of the spinning dope, the configuration of the coagulation bath and the specific dry-wet spinning parameter control. However, with the continuous development of the aramid fiber spinning industry, it is usually required that a set of spinning production equipment can take into account the efficient production of multiple varieties of aramid fiber, and realize the high spinning of different aramid fibers. On this basis, it is necessary to improve the mechanical properties of different varieties of aramid fiber. The above-mentioned patent is only a special dry-wet spinning process for meta-aramid and aramid III, and the mechanical properties still need to be improved, and it is not suitable for the spinning process of other aramid fibers. Therefore, it is necessary to research and develop a dry-wet high-speed spinning process suitable for multiple varieties of aramid fiber. SUMMARY

[0005] The present application aims to solve the problems of low spinning speed and low efficiency in the existing aramid wet spinning technology, and provides a high-speed spinning process suitable for multiple varieties of polyaramid fiber. The new dry-wet process can produce aramid fiber with better and more stable performance, and is suitable for multiple varieties of aramid fiber, and can improve the spinning speed of different varieties of aramid fiber, and realize high-efficiency spinning generation.

[0006] The present application is realized by the following technical scheme: a high-speed spinning process suitable for multiple varieties of polyaramid fiber, the spinning dope is spun through the spinneret, then enters the coagulation bath after an air interval of 5-50 mm, and then is plasticized and coagulated, washed, dried, heat treated and oiled to obtain aramid fiber,

[0007] The spinning dope is a mixture of aromatic polyamide with a specific viscosity of 1.2-7.0, amide solvent and cosolvent, the concentration of aromatic polyamide in the spinning dope is 5-25%wt, the concentration of cosolvent is 1-7.5%wt, and the concentration of amide solvent is 67.5-94%wt;

[0008] The concentration of amide solvent in the coagulation bath is 30-60%wt;

[0009] The concentration of amide solvent in the plastic coagulation bath is 20-30%wt;

[0010] The take-up speed of the aramid fiber is at least 45-600 m / min;

[0011] The breaking strength variation coefficient of the aramid fiber is 1-3%.

[0012] Further, the temperature of the spinning dope is 40-140℃.

[0013] The temperature of the amide solvent used in the coagulation bath is 20-50℃, the draw ratio of the coagulation bath is 1.0-5.0, and the take-off speed is ≥30 m / min.

[0014] The temperature of the amide solvent used in the plasticizing coagulation bath is 20-50℃, and the draw ratio of the plasticizing coagulation bath is 1.0-4.0.

[0015] The temperature of the heat treatment is 260-550℃, the residence time is 3-120 s, and the draw ratio of the heat treatment is 1.0-11.0.

[0016] To better achieve the present application, the aromatic polyamide is poly-m-phenylene isophthalamide (meta-aramid), poly-p-phenylene terephthalamide co 3, 4'-diaminodiphenyl ether (aramid), poly-p-phenylene terephthalamide co 2-(4-aminophenyl)-5-aminobenzimidazole (aramid III), or polyphenylsulfone terephthalamide (sulfar).

[0017] The amide solvent is at least one of N-methylpyrrolidone, N, N-dimethylacetamide, and dimethylformamide.

[0018] The cosolvent is at least one of CaCl2 and LiCl.

[0019] The present application has the following advantages compared with the existing wet process:

[0020] (1) To solve the problem of low spinning speed and poor efficiency in the wet spinning process, the existing technology proposes to use dry-wet spinning for aramid fibers, but due to the differences in performance and spinning requirements of different spinning wheel varieties, the existing dry-wet spinning process is often only suitable for spinning wheel fiber spinning of specific varieties, for example: the dry-wet spinning process of meta-aramid disclosed in CN106283254A and the dry-wet spinning process of aramid III disclosed in CN104278338A. Therefore, the present application provides a new dry-wet spinning process for spinning wheel fibers, which can not only be suitable for spinning of multiple varieties of spinning wheel fibers, but also can produce spinning wheel fibers with better performance, so as to improve the spinning speed of different varieties of aramid fibers and realize high-efficiency spinning.

[0021] (2) The dry-wet spinning process provided by the present application can be used for the preparation of multiple varieties of spinning wheel fibers with different performance and spinning requirements. By using specific concentration of amide solvent or solvent, reasonable control of temperature, and control of draw ratio in different sections of the dry-wet spinning process, the target spinning wheel fibers meeting the required index system can be obtained in the preparation process of different varieties of spinning wheel fibers, and at the same time, the spinning speed is high.

[0022] (3) The method of the present application can produce a spinning wheel fiber with excellent performance, specifically embodied in: high mechanical properties, for example; breaking strength of 2.7-31.2 cN / dtex, elastic modulus of 110-817 cN / dtex, elongation of 3.5-27%; excellent filament properties, for example: breaking strength variation coefficient of 1-3%.

[0023] In summary, the present application provides a method suitable for various aromatic polyamide stock solutions for dry-wet spinning to produce different varieties of spinning wheel fibers, which can stably and efficiently produce spinning wheel fibers with excellent mechanical properties and filament properties, solving the problem of low spinning speed in wet spinning process, and the disadvantage that the existing dry-wet spinning process can only be used for single variety of spinning wheel fibers. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in conjunction with examples, but the embodiments of the present application are not limited thereto.

[0025] Example 1:

[0026] A 25%wt solid content poly-m-phenylene isophthalamide (meta-aramid) polymer spinning NMP stock solution (CaCl2 concentration of 3.3%wt, NMP concentration of 71.7%wt, polymer intrinsic viscosity of 2.1) is extruded through a 10,000 hole spinning plate maintained at 110°C, passes through a 15mm air layer, enters a 50°C 50%wt NMP coagulation bath at a speed of 35m / min, and the draw ratio in the bath is 1.3; then enters the plasticizing coagulation section, the coagulation bath is a 25%wt NMP coagulation bath, the temperature is 35°C, and the draw ratio is 1.5; then enters the washing and drying steps; finally enters the heat treatment heating roller, the heat treatment draw ratio is 2.4, the temperature is 340°C, and the residence time is 3s; after exiting the heat treatment channel, it is oiled and wound up, the filament fineness is 2.2dtex, and the yarn speed is 126m / min.

[0027] Example 2:

[0028] A 17%wt solids concentration of polyphenylsulfone terephthalamide (aramid) polymer dope (CaCl2 concentration of 3.5%wt, NMP concentration of 79.5%wt, polymer intrinsic viscosity of 1.7) is extruded through a 10,000 hole spinneret at 100°C, through a 10mm air gap, into a 20°C 60%wt NMP coagulant bath at a rate of 40m / min with a draw ratio of 1.1 in the bath; followed by a plasticization coagulation section with a 25%wt NMP coagulant bath at a temperature of 35°C with a draw ratio of 1.5; followed by a water wash, 160°C drying step; and finally a heat treatment tunnel with a heat treatment draw ratio of 2.0 at a temperature of 370°C for a residence time of 30s; followed by oiling and take-up after the heat treatment tunnel with a filament size of 2.2dtex at a take-up speed of 132m / min.

[0029] Example 3:

[0030] A 5%wt solids concentration of poly(p-phenyleneterephthalamide) co-2-(4-aminophenyl)-5-aminobenzimidazole (Aramid III) polymer dope (CaCl2 concentration of 3.5%wt, NMP concentration of 91.5%wt, polymer intrinsic viscosity of 6.7) is extruded through a 200 hole spinneret at 95°C, through a 10mm air gap, into a 50°C 60%wt NMP coagulant bath at a rate of 30m / min with a draw ratio of 1.0 in the bath; followed by a plasticization coagulation section with a 25%wt NMP coagulant bath at a temperature of 35°C with a draw ratio of 1.7; followed by a water wash, 160°C drying step; and finally a heat treatment tunnel with a heat treatment draw ratio of 1.5 at a temperature of 380°C for a residence time of 35s; followed by oiling and take-up after the heat treatment tunnel with a filament size of 2.2dtex at a take-up speed of 76.5m / min.

[0031] Example 4:

[0032] A 6%wt solid content poly(p-phenyleneterephthalamide co-2-(4-aminophenyl)-5- aminobenzimidazole (Aramid III) polymer dope in DMAC (LiCl concentration of 3.5%wt, NMP concentration of 90.5%wt, polymer intrinsic viscosity of 6.5) is extruded through a 200 hole spin plate maintained at 40°C, passed through a 10mm air gap, into a 20°C 60%wt DMAC coagulation bath at an exit bath speed of 35m / min with a draw ratio in the bath of 1.0; followed by a plasticization coagulation section with a 25%wt DMAC coagulation bath at a temperature of 35°C with a draw ratio of 1.8; followed by a water wash, 160°C drying step; and finally a heat treatment tunnel with a heat treatment draw ratio of 1.3 at a temperature of 380°C for a residence time of 35s; followed by oiling and take up after the heat treatment tunnel with a filament size of 2.2dtex at a take up speed of 81.9m / min.

[0033] Example 5:

[0034] A 6%wt solid content poly(p-phenyleneterephthalamide co-3,4'-diaminophenyl ether (Aramid 4A) polymer dope in NMP (CaCl2 concentration of 2.1%wt, NMP concentration of 91.9%wt, polymer intrinsic viscosity of 4.1) is extruded through a 400 hole spin plate maintained at 105°C, passed through a 10mm air gap, into a 20°C 50%wt NMP coagulation bath at an exit bath speed of 35m / min with a draw ratio in the bath of 1.1; followed by a plasticization coagulation section with a 30%wt NMP coagulation bath at a temperature of 40°C with a draw ratio of 1.5; followed by a water wash, 160°C drying step; and finally a heat treatment tunnel with a heat treatment draw ratio of 10 at a temperature of 500°C for a residence time of 10s; followed by oiling and take up after the heat treatment tunnel with a filament size of 1.67dtex at a take up speed of 525m / min.

[0035] Example 6:

[0036] ​A 7%wt solid content poly(p-phenyleneterephthalamide co 3, 4' -diaminodiphenyl ether) (Aramid fiber) polymer spinning NMP dope (LiCl concentration of 3.5%wt, NMP concentration of 89.5%wt, polymer intrinsic viscosity of 4.3) was extruded through a 400 hole spinning plate kept at 70°C, passed through a 10mm air gap, into a 20°C 50%wt DMAC coagulation bath at a rate of 35m / min with a draw ratio of 1.2 in the bath; followed by a plasticization coagulation section with a 30%wt DMAC coagulation bath at a temperature of 40°C with a draw ratio of 1.3; followed by a water wash, 160°C drying step; and finally a heat treatment tunnel with a heat treatment draw ratio of 10 at a temperature of 500°C for a residence time of 10s; oiled and wound after exiting the heat treatment tunnel with a filament size of 1.67dtex at a take-up speed of 455m / min.

[0037] The aramid fibers spun in the above examples 1 to 6 (meta-aramid fiber, aramide fiber, aramid fiber III, aramid fiber III, aramide fiber, aramide fiber in turn) were subjected to mechanical property testing, as shown in Table 1 below.

[0038] Table 1 Performance data table of aramid fibers described in examples 1 to 6

[0039]

[0040] Comparative example 1:

[0041] A 17%wt solid content poly(m-phenyleneterephthalamide) (meta-aramid) polymer spinning NMP dope (CaCl2 concentration of 3.3%wt, NMP concentration of 79.5%wt, polymer intrinsic viscosity of 1.7) was extruded through a 10,000 hole spinning plate kept at 110°C, into a 50°C 50%wt NMP coagulation bath at a rate of 10m / min with a draw ratio of -1.3 in the bath, followed by a plasticization coagulation section with a 25%wt NMP coagulation bath at a temperature of 35°C with a draw ratio of 1.8; followed by a water wash, 160°C drying step; and finally a heat treatment heated roller with a heat treatment draw ratio of 2.4 at a temperature of 340°C for a residence time of 3s; oiled and wound after exiting the heat treatment tunnel with a filament size of 2.2dtex at a take-up speed of 43.2m / min.

[0042] Comparative example 2:

[0043] According to the method of CN106283254A:

[0044] A dope with 20%wt solid content of poly-m-phenylene isophthamide (MPD) polymer, 3.3%wt CaCl2, and 73.97%wt DMAC was heated to 100℃, and then filtered with filters with filtration accuracy of 20μm and 10μm, respectively, and left to stand for 12 hours to remove bubbles to obtain a spinning dope. The spinning dope was extruded through a spinning plate with 10,000 holes at room temperature, entered an air gap with a distance of 15mm, and then entered a coagulation bath with 5%wt DMAC at 20℃ at a speed of 10m / min, and then entered a drawing bath with hot water at 80℃ at a drawing ratio of 2.2, and then washed with water, dried at 150℃, and finally entered a heat treatment roller at a heat treatment drawing ratio of 2.2 and a temperature of 375℃ for 2s. After exiting the heat treatment channel, the yarn was oiled and wound up. The filament fineness of the yarn was 2.2dtex, and the winding speed was 48.4m / min.

[0045] The process parameters and mechanical properties of the above Example 1 and Comparative Examples 1 and 2 were compared, as shown in Table 2 below.

[0046] Table 2 Comparison of process parameters and mechanical properties of Example 1 and Comparative Examples 1 and 2

[0047]

[0048] As can be seen from Table 2 above, the method of the present application can be used to prepare MPD fiber filaments with excellent mechanical properties, and the spinning speed can reach 126m / min, which can realize high-efficiency and stable production of MPD fiber filaments. At the same time, the solid content of the spinning dope is higher, and the production cost of the fiber can be reduced.

[0049] Comparative Example 1 is a wet spinning process, i.e., the air gap between the spinneret and the coagulation bath is cancelled. By adjusting the related process parameters of the wet spinning process, such as the speed of the negative stretching out of the bath, the drawing ratio of the coagulation bath, and the plasticizing coagulation drawing ratio, the final spinning speed is only 43.2m / min, and the overall mechanical property index system of the prepared MPD fiber filaments is also different, mainly in that the breaking strength and the elastic modulus of the fiber filaments are decreased.

[0050] Comparative Example 2 is a method according to CN106283254A. The main difference from the present application is that the filtration and foaming of the spinning dope, the drawing ratio and temperature of the coagulation bath, the plasticizing coagulation temperature, the plasticizing coagulation liquid, the heat treatment temperature, and the heat treatment residence time, etc. The speed of the out of the bath is low, and the production is unstable if it is too high. Therefore, the spinning speed obtained by this process is only 48.4m / min, and the overall mechanical property index system of the final MPD fiber filaments is different.

[0051] Comparative Example 3:

[0052] A 12%wt solid content polyphenylsulfone terephthalamide (PSA) polymer spinning DMAC dope (LiCl concentration of 1.5%wt, DMAC concentration of 86.5%wt, polymer intrinsic viscosity of 1.5) was extruded through a 10,000 hole spinning plate kept at 40℃, entered a 20℃ 60%wt NMP coagulation bath at a speed of 10m / min, the bath draw ratio was -1.2, then entered a plasticizing coagulation section, the coagulation bath was a 25%wt NMP coagulation bath, the temperature was 35℃, the draw ratio was 1.6; then entered a water washing and 160℃ drying step; finally entered a heat treatment channel, the heat treatment draw ratio was 1.7, the temperature was 370℃, the residence time was 30s; after exiting the heat treatment channel, the yarn was oiled and wound up, the filament fineness was 2.2dtex, and the yarn speed was 27.2m / min.

[0053] The process parameters and mechanical properties of the above-mentioned Example 2 and Comparative Example 3 were compared, as shown in Table 3 below.

[0054] Table 3 Comparison of process parameters and mechanical properties of Example 1 and Comparative Example 3

[0055]

[0056] As can be seen from Table 3 above, the method of the present application can be used to prepare arsulfonamide fiber filaments with excellent mechanical properties, and the spinning speed can reach 132m / min, which can realize high-efficiency and stable production of arsulfonamide fiber filaments, at the same time, the solid content of the spinning dope is higher, and the fiber production cost can also be reduced.

[0057] Comparative Example 3 is a wet spinning process, i.e., the air gap between the jet and the coagulation bath is cancelled, by adjusting the related process parameters of the wet spinning process, such as the bath exit speed, the coagulation bath draw ratio and the plasticizing coagulation draw ratio, wherein the wet bath needs a lower negative draw exit speed, therefore, the final spinning speed is only 27.2m / min, and the overall mechanical property index system of the arsulfonamide fiber filaments prepared is also different, mainly in that the breaking strength and elastic modulus of the fiber filaments are both decreased.

[0058] Comparative Example 4:

[0059] A 4%wt solid content poly-p-phenyleneterephthalamide co-2-(4-aminophenyl)-5-aminobenzimidazole (aramid III) polymer dope solution (LiCl concentration of 3.5%wt, DMAC concentration of 92.5%wt, polymer intrinsic viscosity of 6.4) was extruded through a 200-hole spinning plate at 30℃, entered a 20℃ 50%wt DMAC coagulation bath at a speed of 11m / min, the draw ratio in the bath was -1.2; then entered a plasticizing coagulation section, the coagulation bath was a 25%wt DMAC coagulation bath, the temperature was 35℃, the draw ratio was 1.9; then entered a water washing and 160℃ drying step; finally entered a heat treatment channel, the heat treatment draw ratio was 1.2, the temperature was 380℃, the residence time was 35s; after exiting the heat treatment channel, the filament was oiled and wound up, the single filament fineness was 2.2dtex, and the winding speed was 25m / min.

[0060] Comparative Example 5:

[0061] According to the method of CN104278338A:

[0062] A polymer dope solution with an intrinsic viscosity of 9.0 was extruded through a 200-hole spinning plate at 30℃, passed through a 19mm air layer, entered a 20℃ 13%wt DMAC coagulation bath at a speed of 10m / min, the draw ratio in the bath was -0.9; then entered a plasticizing coagulation section, the coagulation bath was a 25%wt DMAC solution, the temperature was 30℃, the draw ratio was 1.36; then entered a water washing and 160℃ drying step, finally entered a heat treatment channel, the heat treatment draw ratio was 1.5, the temperature was 430℃, the residence time was 30s; after exiting the heat treatment channel, the filament was oiled and wound up, the single filament fineness was 3.0dtex, and the winding speed was 20.4m / min.

[0063] The process parameters and mechanical properties of the above-mentioned Example 3, Example 4 and Comparative Examples 4 and 5 were compared, as shown in Table 4 below.

[0064] Table 4 Comparison of process parameters and mechanical properties of Examples 3-4 and Comparative Examples 4-5

[0065]

[0066] As can be seen from Table 4 above, the method of the present application can be used to prepare aramid III fiber filaments with excellent mechanical properties, and the spinning speed can reach more than 76.5m / min, enabling high-efficiency and stable production of aramid III fiber filaments, at the same time, the solid content of the spinning dope solution is higher, and the cost of fiber production can be reduced.

[0067] Comparative Example 4 is a wet spinning process, i.e., the air gap between the spinneret and the coagulation bath is cancelled. By adjusting the related process parameters of the wet spinning process, such as the out-bath speed, the coagulation bath draft ratio and the plasticization coagulation draft ratio, the out-bath speed needs to be lower due to the negative stretching of the wet water bath, and thus the final spinning speed is only 25 m / min. The overall mechanical property index system of the aramid III fiber filament prepared is also different, mainly in that the breaking strength and the elastic modulus of the fiber filament are decreased.

[0068] Comparative Example 5 is prepared by the method of CN104278338A. The main difference from the present application is that the solvent system of the spinning dope, the intrinsic viscosity of the polymer, and the draft ratio and temperature of the coagulation bath, the plasticization coagulation temperature, the plasticization coagulation liquid, the heat treatment temperature, the heat treatment residence time, etc. The longer water bath needs to be stretched negatively, so the out-bath speed is low, and thus the spinning speed obtained by this process is only 20.4 m / min. The overall mechanical property index system of the aramid III fiber filament obtained is different.

[0069] Comparative Example 6:

[0070] A 5%wt solid content poly-p-phenyleneterephthalamide co-3, 4'-diaminodiphenyl ether (aramid fiber) polymer spinning DMAC dope (LiCl concentration of 3.5%wt, DMAC concentration of 91.5%wt, polymer intrinsic viscosity of 3.7) is extruded through a 400-hole spinning plate at 70℃, enters a 20℃ 50%wt DMAC coagulation bath at an out-bath speed of 11 m / min, and the bath draft ratio is -1.2; then enters the plasticization coagulation section, the coagulation bath is a 30%wt DMAC coagulation bath, the temperature is 40℃, and the draft ratio is 1.3; then enters the water washing and 160℃ drying steps; finally enters the heat treatment channel, the heat treatment draft ratio is 10, the temperature is 500℃, and the residence time is 10s; after exiting the heat treatment channel, it is oiled and wound up, the single filament fineness is 1.67dtex, and the yarn speed is 143 m / min.

[0071] The process parameters and mechanical properties of the above-mentioned Example 5, Example 6 and Comparative Example 6 are compared as shown in Table 5 below.

[0072] Table 5 Comparison of process parameters and mechanical properties of Example 5-6 and Comparative Example 6

[0073]

[0074] As can be seen from Table 5 above, the method of the present application can be used to prepare aramid fiber filaments with excellent mechanical properties, and the spinning speed can reach more than 455 m / min, which can realize the high-efficiency and stable production of aramid fiber filaments. At the same time, the solid content of the spinning dope is higher, and the cost of fiber production can also be reduced.

[0075] Comparative Example 6 is a wet spinning process, i.e. the air gap between the spinning nozzle and the coagulation bath is cancelled, by adjusting the related process parameters of the wet spinning process, such as the out-bath speed, the coagulation bath draft ratio and the plasticization coagulation draft ratio, wherein the wet water bath needs a lower negative draft out-bath speed, thus the final spinning speed is only 143 m / min, and the overall mechanical property index system of the prepared arnyl fiber filament is also different, mainly in that the breaking strength and the elastic modulus of the fiber filament are both decreased.

[0076] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change made on the basis of the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A high-speed spinning process suitable for various types of polyaramid fibers, characterized in that: Includes the following steps: S1. A mixture of aromatic polyamide, amide solvent and co-solvent with an intrinsic viscosity of 4.1 to 6.7 is used as the spinning solution, wherein the concentration of aromatic polyamide in the spinning solution is 5 to 25% wt and the concentration of co-solvent is 2.1 to 3.5% wt. S2. The spinning solution is spun through a spinneret and then enters a coagulation bath after passing through an air gap of 10-15 mm. In the coagulation bath, an amide solvent with a concentration of 50-60%wt is used. The temperature of the amide solvent is 20°C. The draw ratio of the coagulation bath is 1.0-1.3, and the outlet speed is ≥30m / min. S3. Then, the process proceeds to the plasticizing and coagulation stage. In the plasticizing and coagulation bath, an amide solvent with a concentration of 25-30%wt is used. The temperature of the amide solvent is 35-40°C, and the draw ratio of the plasticizing and coagulation bath is 1.3-1.

8. S4. After washing, drying, heat treatment, oiling, and winding, polyaramid fiber is obtained. The heat treatment temperature is 370–500℃, the residence time is 3–35 s, and the draw ratio is 1.3–10. The take-up speed of the polyaramid fiber is 76.5–455 m / min. The mechanical properties of the polyaramid fiber meet the following requirements: The fracture strength is 2.7–31.2 cN / dtex. The elastic modulus is 110–817 cN / dtex. Elongation rate is 3.5%–27%. The coefficient of variation for fracture strength is 1.45–2.54%.

2. The high-speed spinning process applicable to various types of polyaramid fibers according to claim 1, characterized in that: The temperature of the spinning solution is 40–140°C.

3. The high-speed spinning process applicable to various types of polyaramid fibers according to claim 1, characterized in that: The aromatic polyamide is poly(m-phenylene isophthalamide), poly(p-phenylene terephthalamide) co-3,4'-diaminodiphenyl ether, poly(p-phenylene terephthalamide) co-2-(4-aminophenyl)-5-aminobenzimidazole, or poly(phenyl sulfone) terephthalamide.

4. The high-speed spinning process applicable to various types of polyaramid fibers according to claim 1, characterized in that: The amide solvent is at least one of N-methylpyrrolidone, N,N-dimethylacetamide, and dimethylformamide.

5. The high-speed spinning process applicable to various types of polyaramid fibers according to claim 1, characterized in that: The co-solvent is at least one of CaCl2 and LiCl.

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