Production and processing technology of high-performance aramid fiber

Abstract

The invention relates to the technical field of aramid fiber production, in particular to a high-performance aramid fiber production and processing technology which comprises the following steps: dissolving phenylenediamine in an amide polar organic solvent to obtain a m-phenylenediamine organic solution, and adding m-phthaloyl dichloride to carry out pre-polycondensation reaction and polycondensation reaction; adding an alkaline solution into the polycondensate to carry out neutralization reaction; filtering to obtain a spinning solution; the spinning solution is extruded through a spinning nozzle and enters a coagulating bath, stretching, washing and drying are conducted after coagulating forming, then heat setting is conducted through a mold temperature controller, and the temperature of circulating hot fluid and a mold at all moments in the mold temperature controller in the heat setting process is collected; obtaining a current temperature regulation coefficient in the heat setting process; adjusting control parameters in a PID control algorithm, and performing temperature regulation and control on the current moment in the heat setting process by using the PID control algorithm; after heat setting is completed, the aramid fiber is obtained. The physical performance of the aramid fiber is improved.

Description

Technical Field

[0001] This application relates to the technical field of aramid production, and specifically relates to a production and processing process for high-performance aramid fibers. Background Art

[0002] Aramid fiber is a synthetic fiber composed of polyamides with a benzene ring structure. It has excellent physical properties such as very high tensile strength, high temperature resistance, corrosion resistance, and wear resistance, and is widely used in multiple fields.

[0003] In the traditional production and processing of aramid fibers, fixed heat setting process parameters are usually used to control the properties of the fibers. However, the fixed temperature used in the traditional process cannot adapt to the complex heat exchange dynamics during production, resulting in the fibers not obtaining uniform and stable heat treatment during the heat setting stage, affecting the tensile strength and modulus of the fibers, and reducing their physical properties. Secondly, the traditional process fails to fully consider the influence of environmental factors on the heat setting process, that is, temperature fluctuations may lead to inconsistencies in fiber properties, thereby affecting the overall quality and physical properties of the final aramid fibers. Summary of the Invention

[0004] In order to solve the above technical problems, this application provides a production and processing process for high-performance aramid fibers to solve the existing problems.

[0005] The production and processing process for high-performance aramid fibers of this application adopts the following technical solutions:

[0006] An embodiment of this application provides a production and processing process for high-performance aramid fibers, and this process includes the following steps:

[0007] Dissolve phenylenediamine in an amide polar organic solvent to obtain an m-phenylenediamine organic solution, and cool it down;

[0008] Add isophthaloyl chloride to the cooled m-phenylenediamine organic solution for pre-polycondensation reaction;

[0009] After the pre-polycondensation reaction, add isophthaloyl chloride again for polycondensation reaction to obtain a polycondensate;

[0010] Add an alkaline solution to the polycondensate for neutralization reaction; filter the neutralization reaction product to obtain a spinning solution;

[0011] Extrude the spinning solution through a spinneret into a coagulation bath, and obtain nascent fibers after coagulation and shaping;

[0012] Stretch, wash, and dry the nascent fibers, and then use a mold temperature controller for heat setting, and collect the temperatures of the circulating heat fluid and the mold at each moment in the mold temperature controller during the heat setting process;

[0013] Analyze the fitting deviation before and after fitting of each extreme point of the temperature of the circulating hot fluid at all times during the heat setting process, and obtain the separation coefficient between each extreme point before fitting and each extreme point after fitting;

[0014] Based on the separation coefficient, determine the extreme points before fitting corresponding to each extreme point after fitting, and use the extreme points before fitting corresponding to each extreme point after fitting to divide all times during the heat setting process to obtain each time period;

[0015] Analyze the difference change between the temperature of the circulating hot fluid and the temperature of the mold at all times within each time period, as well as the numerical distribution of the difference, to obtain the heat interaction interference degree of each time period; through the distribution range of the difference of all time periods, combined with the heat interaction interference degree, obtain the current temperature regulation coefficient during the heat setting process;

[0016] Based on the temperature regulation coefficient, adjust the control parameters in the PID control algorithm, and use the PID control algorithm to regulate the temperature at the current moment during the heat setting process;

[0017] Aramid fibers are obtained after heat setting.

[0018] In one embodiment, the amide polar organic solvent includes: N,N-dimethylformamide, N,N-dimethylacetamide; the mass ratio of the phenylenediamine to the amide polar organic solvent is 1:7-8.

[0019] In one embodiment, the temperature reduction is to -20 to -15 °C; the molar ratio of m-phenylenediamine to isophthaloyl chloride in the prepolycondensation reaction is 1:0.8; the time of the prepolycondensation reaction is 40 to 60 min, and the temperature is -20 to -10 °C.

[0020] In one embodiment, the molar ratio of phenylenediamine to isophthaloyl chloride when adding isophthaloyl chloride again is 1:0.2; the time of the polycondensation reaction is 45 to 60 min, and the temperature is -4 to 4 °C.

[0021] In one embodiment, adding an alkaline solution to the polycondensate for neutralization reaction includes:

[0022] The alkaline solution includes sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution; the temperature of the neutralization reaction is 55 to 80 °C, and the time is 5 to 10 min.

[0023] In one embodiment, the temperature of the drying is 100 to 200 °C; the time of the heat setting is 60 to 100 min.

[0024] In one embodiment, the determination of the separation coefficient includes:

[0025] Obtain each extreme point in the fitting curve of the temperature of the circulating hot fluid at all moments during the heat setting process, denoted as the first extreme point; obtain each extreme point of the temperature of the circulating hot fluid at all moments during the heat setting process, denoted as the second extreme point;

[0026] Calculate the time interval and temperature difference between any first extreme point and any second extreme point; the separation coefficient between any first extreme point and any second extreme point is: the fusion result of the time interval and the temperature difference.

[0027] In one embodiment, the determination of each time period includes:

[0028] For each first extreme point, obtain the second extreme point with the smallest separation coefficient from it as the corresponding point of each first extreme point, and use the moments of all the corresponding points as segmentation points to obtain each time period.

[0029] In one embodiment, the determination of the thermal interaction interference degree includes:

[0030] Calculate the difference between the temperature of the circulating hot fluid and the temperature of the mold at each moment within each time period, denoted as the first difference; calculate the average value of all the first differences within each time period, and count the difference between the number of the first differences less than the average value and the number greater than the average value within each time period, denoted as the second difference;

[0031] Calculate the difference between the first difference of each moment and its adjacent moment within each time period, denoted as the third difference, and the thermal interaction interference degree is the fusion result of the second difference of each time period and the average value of all the third differences.

[0032] In one embodiment, the determination of the temperature regulation coefficient includes:

[0033] Calculate the average value of all the first differences of each time period, calculate the ratio of the range to the average value of the average values of all time periods during the heat setting process, and the temperature regulation coefficient is the fusion result of the ratio and the thermal interaction interference degree of all time periods during the heat setting process;

[0034] The adjustment method of the control parameter is:

[0035] In the formula, D is the current differential parameter of the PID control algorithm, D' is the historical differential parameter before the current moment of the PID control algorithm, K is the current temperature regulation coefficient during the heat setting process, Z is the preset threshold, exp() is the exponential function with the natural constant as the base, P is the current proportional parameter of the PID control algorithm, and P' is the historical proportional parameter before the current moment of the PID control algorithm.

[0036] This application has at least the following beneficial effects:

[0037] In this application, the temperature of the circulating hot fluid at each moment in the mold temperature control machine and the temperature of the mold are collected during the heat setting process of aramid fiber production; the fitting deviation before and after fitting the extreme value points of the temperature of the circulating hot fluid at all moments during the heat setting process is analyzed to obtain the separation coefficient between the extreme value points before fitting and the extreme value points after fitting; the separation coefficient reflects the distance relationship between the extreme value points before fitting and the extreme value points after fitting, which helps to screen out the extreme value points that conform to the trend change of the temperature of the circulating hot fluid from the extreme value points before fitting; based on the separation coefficient, the extreme value points before fitting corresponding to the extreme value points after fitting are determined, and all moments during the heat setting process are segmented using the extreme value points before fitting corresponding to the extreme value points after fitting to obtain each time period; the division of each time period reflects the start time and end time of the influence of external environmental factors on the temperature of the heat setting process, which is convenient for more accurately analyzing the influence degree of external environmental factors on the temperature of the heat setting process; the difference change between the temperature of the circulating hot fluid and the temperature of the mold at all moments within each time period, as well as the numerical distribution of the difference, are analyzed to obtain the heat interaction interference degree of each time period; the heat interaction interference degree reflects the degree of difference change between the temperature of the circulating hot fluid and the temperature of the mold within each time period, which reflects the degree of temperature interference of external environmental factors on heat setting and improves the reliability of heat setting temperature control; through the distribution range of the differences in all time periods, combined with the heat interaction interference degree, the current temperature regulation coefficient during the heat setting process is obtained; the temperature regulation coefficient reflects the temperature change trend of heat setting before the current moment, which reflects the necessity of temperature regulation for heat setting and improves the accuracy of subsequent heat setting temperature regulation; based on the temperature regulation coefficient, the control parameters in the PID control algorithm are adjusted, and the PID control algorithm is used to regulate the temperature at the current moment during the heat setting process; this improves the accuracy and stability of heat setting temperature control and improves the physical properties and overall quality of the finally produced aramid fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings required for use in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0039] Figure 1 It is a process flow chart of a production and processing technology for a high-performance aramid fiber provided by this application;

[0040] Figure 2 It is a schematic diagram of the fitting curve of the setting fluid temperature sequence;

[0041] Figure 3 Temperature control flowchart for heat setting of aramid fibers. Specific embodiments

[0042] To further elaborate on the technical means and effects adopted by this application to achieve the intended invention purpose, the following will, in conjunction with the accompanying drawings and preferred embodiments, elaborate in detail on a production and processing technology for high-performance aramid fibers proposed according to this application, its specific embodiments, structures, features, and effects. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs.

[0044] The following will specifically describe the specific solution of a production and processing technology for high-performance aramid fibers provided by this application in conjunction with the accompanying drawings.

[0045] Example 1

[0046] Please refer to Figure 1 , which shows the process flow chart of a production and processing technology for high-performance aramid fibers provided in Example 1 of this application. This technology includes the following steps:

[0047] (1) Dissolve phenylenediamine in an amide-based polar organic solvent to obtain an organic solution of m-phenylenediamine, and cool it down.

[0048] In this example, phenylenediamine is dissolved in N,N-dimethylformamide to obtain an organic solution of m-phenylenediamine. Among them, the mass ratio of phenylenediamine to N,N-dimethylformamide is 1:7. Cool the organic solution of m-phenylenediamine to -20°C.

[0049] (2) Add isophthaloyl chloride to the cooled organic solution of m-phenylenediamine for a pre-polycondensation reaction.

[0050] In this example, isophthaloyl chloride is added to the cooled organic solution of m-phenylenediamine. Among them, the molar ratio of m-phenylenediamine to isophthaloyl chloride in the organic solution of m-phenylenediamine is 1:0.8. The time for the pre-polycondensation reaction is 40 min, and the temperature is -20°C.

[0051] (3) After the pre-polycondensation reaction, add isophthaloyl chloride again for a polycondensation reaction to obtain a polycondensate.

[0052] After the prepolycondensation reaction is completed, isophthaloyl chloride is added again to the organic solution of m-phenylenediamine to which isophthaloyl chloride has been added. During the process of adding isophthaloyl chloride again, the molar ratio of m-phenylenediamine to isophthaloyl chloride is ensured to be 1:0.2. The time for the polycondensation reaction is 45 min and the temperature is -4°C.

[0053] (4) Add an alkaline solution to the polycondensate for a neutralization reaction; filter the neutralization reaction product to obtain a spinning solution.

[0054] Add a sodium hydroxide solution to the polycondensate for a neutralization reaction. The temperature of the neutralization reaction is 55°C and the time is 5 min. The slurry after the neutralization reaction is filtered and washed through a filter to remove residual solvents, inorganic salts and other impurities to obtain a spinning solution.

[0055] (5) Extrude the spinning solution through a spinneret into a coagulation bath, and obtain a nascent fiber after solidification and shaping.

[0056] Extrude the spinning solution through the micropores in the spinneret to form fine filaments. The extruded fine filaments immediately enter the coagulation bath and solidify to form nascent fibers.

[0057] (6) Stretch, wash and dry the nascent fiber, and then perform heat setting using a mold temperature controller.

[0058] After obtaining the nascent fiber from the coagulation bath, stretch it to enhance its strength and toughness, and then wash the stretched nascent fiber to remove residual solvents and coagulants. The washing is carried out with clean water; after washing, drying is performed using a drying device, and the drying temperature is 100°C. The dried nascent fiber is subjected to heat setting using a mold temperature controller. Among them, the temperature range for heat setting is controlled at 340 - 420°C and the time is 60 min.

[0059] Since during the production of traditional aramid fibers, a fixed temperature is usually adopted during the heat setting process using a mold temperature controller, resulting in the fibers being unable to obtain uniform and stable heat treatment during the heat setting stage, affecting the tensile strength and modulus of the fibers and reducing their physical properties. Secondly, due to changes in the external environmental temperature or uneven heat transfer, the temperature during the heat setting process will fluctuate, affecting the overall quality of the fiber properties. Therefore, to ensure the accuracy and stability of the temperature during the heat setting process, the temperature during the heat setting process is regulated. Specifically:

[0060] Step S001, collect the temperature of the circulating heat fluid at each moment in the mold temperature controller and the temperature of the mold during the heat setting process.

[0061] When heat setting aramid fibers, the aramid fibers enter a mold temperature controller through a conveying device. The mold temperature controller indirectly adjusts the mold temperature by controlling the temperature of the hot fluid. In this embodiment, a temperature sensor is installed inside the mold temperature controller. The temperature sensor respectively collects the temperature of the circulating hot fluid in the mold temperature controller and the temperature of the mold. The acquisition frequency of the temperature sensor is 100 Hz, which can be set by the implementer according to the actual situation and is not limited in this embodiment. The collected temperatures of the circulating hot fluid and the mold are arranged in the order of acquisition time to obtain the temperature sequence of the setting fluid and the temperature sequence of the setting mold during the heat setting of aramid fibers.

[0062] Step S002: Analyze the fitting deviation before and after fitting of each extreme point of the temperature of the circulating hot fluid at all times during the heat setting process to obtain the separation coefficient between each extreme point before fitting and each extreme point after fitting.

[0063] When measuring the heat setting temperature of aramid fibers with a temperature sensor, for the temperature of the mold, since it is directly measured, the measured temperature accuracy is relatively high. For the measurement of the temperature of the hot fluid inside the mold temperature controller, the temperature of the hot fluid is regulated by the temperature of the mold. During the heat setting process, the temperature of the hot fluid is affected not only by the mold temperature but also by the surrounding environment. At the same time, since the state of the hot fluid is a moving form, when heat setting aramid fibers, heat exchange occurs between the aramid fibers and the hot fluid before and after the aramid fibers enter the hot fluid, resulting in certain fluctuations in the temperature of the hot fluid measured by the temperature sensor.

[0064] When heat setting aramid fibers, heat exchange occurs between the aramid fibers and the hot fluid. The temperature fluctuation of the hot fluid is usually relatively small, while when affected by the outside, the temperature fluctuation of the hot fluid is relatively large. If there are fluctuations in the temperature of the hot fluid, a large number of extreme points will appear in the temperature sequence of the setting fluid. The extreme points formed by the heat exchange between the aramid fibers and the hot fluid have relatively small local fluctuations and have little impact on the change trend of the temperature sequence of the setting fluid. The extreme points formed by the influence of external factors have relatively large local fluctuations and have a greater impact on the change trend of the temperature sequence of the setting fluid.

[0065] To identify the extreme points formed by heat exchange and those formed by environmental impacts in the fixed-form fluid temperature sequence, first, the fixed-form fluid temperature sequence is used as the input of the Locally Weighted Regression (LWR) algorithm, and the output is the fitted curve of the fixed-form fluid temperature sequence. Then, the extreme points in the fitted curve are calculated through an extreme point detection algorithm, denoted as the first extreme points. The locally weighted regression algorithm and the extreme point detection algorithm are existing well-known technologies, and the specific processes will not be elaborated here. Denote the elements in the fixed-form fluid temperature sequence as the original data, and the obtained fitted curve as the fitted data. The schematic diagram of the fitted curve of the fixed-form fluid temperature sequence is as shown in Figure 2 shown, Figure 2 where the abscissa is time and the ordinate is temperature.

[0066] Secondly, each extreme point in the fixed-form fluid temperature sequence is obtained through the extreme point detection algorithm, denoted as the second extreme points. The closer the first extreme points and the second extreme points are to each other, the more the second extreme points can reflect the trend of the fixed-form fluid temperature sequence, indicating that the second extreme points are more likely to be the high or low temperature points affected by environmental factors.

[0067] Based on the above analysis, in this embodiment, the separation coefficients between each first extreme point and each second extreme point are calculated. Specifically: calculate the time interval and temperature difference between any first extreme point and any second extreme point; the separation coefficient between any first extreme point and any second extreme point is: the fusion result of the time interval and the temperature difference.

[0068] It should be noted that the difference is the degree of difference between two variables, and can be specifically calculated by methods such as difference, absolute value of difference, square of difference, etc.; fusion means combining multiple variables, and can be specifically calculated by methods such as addition, multiplication, addition-multiplication mixture, etc.

[0069] In this embodiment, the calculation method of the separation coefficient between each first extreme point and each second extreme point is as follows:

[0070] FG i,j =|(L i -WL j )×(T i -WT j )|; In the formula, FG i,j is the separation coefficient between the i-th first extreme point and the j-th second extreme point, L i is the moment corresponding to the i-th first extreme point, WL j is the moment corresponding to the j-th second extreme point, T i is the temperature value corresponding to the i-th first extreme point, WT jis the temperature value corresponding to the j-th second extreme point.

[0071] It should be understood that the smaller the separation coefficient between the first extreme point and the second extreme point, the more likely the second extreme point is a high or low temperature point affected by environmental factors, indicating that the change in the fluid temperature at this moment is more significant. The change trend of the fluid temperature caused by environmental influence can be divided through the separation coefficient.

[0072] Step S003: Based on the separation coefficient, determine the pre-fitting extreme points corresponding to each extreme point after fitting. Use the pre-fitting extreme points corresponding to each extreme point after fitting to divide all moments during the heat setting process to obtain each time period.

[0073] For each first extreme point, obtain the second extreme point with the smallest separation coefficient from it. Thus, each first extreme point corresponds to a second extreme point as the corresponding point of each first extreme point. Use the moments of all the above corresponding points before the current moment during the heat setting process as the segmentation points to divide all the moments before the current moment during the heat setting process to obtain each segmented time period.

[0074] Step S004: Analyze the difference change between the temperature of the circulating hot fluid and the temperature of the mold at all moments within each time period, as well as the numerical distribution of the difference, to obtain the heat interaction interference degree of each time period; through the distribution range of the differences of all time periods, combined with the heat interaction interference degree, obtain the current temperature control coefficient during the heat setting process.

[0075] For each time period, the greater the difference change between the temperature of the circulating hot fluid and the temperature of the mold, the greater the influence of environmental factors on the temperature of the circulating hot fluid during the heat setting of aramid fibers. In an ideal state, the difference between the temperature of the mold and the temperature of the circulating hot fluid at different moments should be the same, indicating that the heat exchange between the circulating hot fluid and the environment as well as aramid fibers is fixed. As long as the stability of the mold temperature is ensured, stable heat setting conditions can be achieved for aramid fibers, making the performance of aramid fibers better.

[0076] Based on the above analysis, calculate the heat interaction interference degree of each time period. Specifically: Calculate the difference between the temperature of the circulating hot fluid and the temperature of the mold at each moment within each time period, denoted as the first difference; calculate the average value of all the first differences within each time period, and count the difference between the number of the first differences less than the average value and the number greater than the average value within each time period, denoted as the second difference;

[0077] Calculate the difference between the first differences of each moment and its adjacent moment within each time period, denoted as the third difference. The heat interaction interference degree is the fusion result of the second difference of each time period and the average value of all the third differences.

[0078] In this embodiment, the absolute value of the difference between the temperature of the circulating hot fluid and the temperature of the mold at each moment within each time period is the first difference. The calculation method of the thermal interaction interference degree of each time period is as follows:

[0079] In the formula, D k is the thermal interaction interference degree in the k-th time period during the heat setting process, g k is the number of the first differences in the k-th time period during the heat setting process that are less than the average value of all the first differences in this time period, l k is the number of the first differences in the k-th time period during the heat setting process that are greater than the average value of all the first differences in this time period, J k,x is the x-th first difference in the k-th time period during the heat setting process, J k,x-1 is the (x - 1)-th first difference in the k-th time period during the heat setting process, S k is the number of the first differences in the k-th time period during the heat setting process, where the first differences are arranged in chronological order. Denote |g k - l k | as the second difference, and |J k,x - J k,x-1 | as the third difference.

[0080] It should be understood that the greater the thermal interaction interference degree, the more significant the change in the difference between the temperature of the circulating hot fluid and the temperature of the mold within this time period, which indicates that the total amount of thermal interaction between the temperature of the circulating hot fluid and the environment is greater, and the greater the possibility that the temperature of the circulating hot fluid is affected by environmental factors. In this case, the temperature fluctuation is more driven by external environmental changes rather than the temperature oscillation inside the mold temperature controller. To reduce the influence of environmental factors on the heat setting temperature of aramid fibers, it is more necessary to regulate the heat setting temperature of the mold temperature controller.

[0081] Based on the thermal interaction interference degrees of all time periods before the current moment during the heat setting process and the distribution range of the first differences, calculate the current temperature regulation coefficient during the heat setting process. The specific calculation method is as follows:

[0082] In the formula, K is the current temperature regulation coefficient during the heat setting process, calculate the average value of all the first differences in each time period before the current moment during the heat setting process, fU1 is the range of all the average values before the current moment during the heat setting process, fW1 is the average value of all the average values before the current moment during the heat setting process, fW2 is the average value of the thermal interaction interference degrees of all time periods before the current moment during the heat setting process, and Norm() is the normalization function.

[0083] It should be understood that the larger the temperature regulation coefficient is, the greater the difference between the first differences in different time periods is, indicating that the temperature of the circulating hot fluid is more likely to be affected by the environment. In this case, the temperature fluctuation is more driven by the external environmental changes rather than the temperature oscillation inside the mold temperature controller. Therefore, it is necessary to improve the response efficiency of the temperature control inside the mold temperature controller to adapt to the environmental changes more quickly and reduce the influence of temperature fluctuation on the aramid fiber shaping process.

[0084] Step S005: Adjust the control parameters in the PID control algorithm based on the temperature regulation coefficient, and use the PID control algorithm to regulate the temperature at the current moment during the heat setting process.

[0085] During the heat setting process of aramid fibers by the mold temperature controller, the temperature adjustment of the circulating hot fluid is carried out through the PID (Proportion Integral Differential) control algorithm in the mold temperature controller. When the current temperature regulation coefficient during the aramid fiber shaping process is larger, the proportional parameter of the PID control algorithm should be enhanced to enhance the response speed of the PID control algorithm. When the current temperature regulation coefficient during the aramid fiber shaping process is smaller, the differential parameter of the PID control algorithm should be enhanced to suppress the temperature oscillation during the heat setting process.

[0086] Thus, the control parameters of the PID control algorithm in the mold temperature controller are adjusted, and the specific calculation method is as follows:

[0087] In the formula, D is the current differential parameter of the PID control algorithm, D' is the historical differential parameter before the current moment of the PID control algorithm, K is the current temperature regulation coefficient during the heat setting process, Z is the preset threshold, Z = 0.6 in this embodiment, and the implementer can set it according to the actual situation, which is not limited in this embodiment; exp() is the exponential function with the natural constant as the base, P is the current proportional parameter of the PID control algorithm, and P' is the historical proportional parameter before the current moment of the PID control algorithm.

[0088] It should be noted that for the proportional parameter, differential parameter, and integral parameter of the PID control algorithm at the initial moment, the proportional parameter takes a value of 2, the differential parameter takes a value of 0.5, and the integral parameter takes a value of 0.1 in this embodiment. The implementer can set them according to the actual situation, which is not limited in this embodiment. In this embodiment, the proportional parameter and differential parameter of the PID control algorithm are adjusted in real time, and the integral parameter is not adjusted.

[0089] It should be understood that the larger the temperature regulation coefficient is, the more significant the influence of environmental factors on the temperature of the circulating heat fluid during the heat setting process. In this case, the temperature fluctuation is more caused by the external environmental change. Therefore, it is necessary to increase the proportional parameter of the PID control algorithm to improve the response speed of temperature control, enabling it to adapt to environmental changes faster, reducing the influence of temperature fluctuation on the aramid fiber setting process, and thus ensuring the stability of fiber properties. On the contrary, when the temperature regulation coefficient is smaller, it indicates that the temperature fluctuation is mainly caused by the temperature oscillation inside the mold temperature controller rather than the external environment. At this time, it is necessary to increase the differential parameter of the PID control algorithm to suppress the temperature oscillation, improve the stability of temperature control, and ensure the accuracy of temperature control.

[0090] Use the PID control algorithm after adjusting the control parameters to adjust the temperature during the heat setting process in real time. Among them, the PID control algorithm is a well-known existing technology, and this embodiment will not elaborate on it in detail here; the temperature control flow chart of the heat setting of aramid fiber is as Figure 3 shown.

[0091] (7) Obtain aramid fiber after heat setting is completed.

[0092] Embodiment 2

[0093] Please refer to Figure 1 , which shows the step flow chart of a production and processing process of a high-performance aramid fiber provided by Embodiment 2 of the present application. This process includes the following steps:

[0094] (1) Dissolve phenylenediamine in an amide-based polar organic solvent to obtain an m-phenylenediamine organic solution, and cool it down.

[0095] In this embodiment, phenylenediamine is dissolved in N,N-dimethylformamide to obtain an m-phenylenediamine organic solution. Among them, the mass ratio of phenylenediamine to N,N-dimethylformamide is 1:7.5. Cool the m-phenylenediamine organic solution to -18°C.

[0096] (2) Add isophthaloyl chloride to the cooled m-phenylenediamine organic solution for a pre-polycondensation reaction.

[0097] In this embodiment, isophthaloyl chloride is added to the cooled m-phenylenediamine organic solution. Among them, the molar ratio of m-phenylenediamine to isophthaloyl chloride in the m-phenylenediamine organic solution is 1:0.8, the time for the pre-polycondensation reaction is 50 min, and the temperature is -15°C.

[0098] (3) Add isophthaloyl chloride again after the pre-polycondensation reaction for a polycondensation reaction to obtain a polycondensate.

[0099] After the prepolycondensation reaction is completed, isophthaloyl chloride is added again to the organic solution of m-phenylenediamine to which isophthaloyl chloride has been added. During the process of adding isophthaloyl chloride again, the molar ratio of m-phenylenediamine to isophthaloyl chloride is ensured to be 1:0.2. The time for the polycondensation reaction is 50 min and the temperature is 0 °C.

[0100] (4) Add an alkaline solution to the polycondensate for a neutralization reaction; filter the product of the neutralization reaction to obtain a spinning solution.

[0101] Add a calcium hydroxide solution to the polycondensate for a neutralization reaction. The temperature of the neutralization reaction is 70 °C and the time is 8 min. The slurry after the neutralization reaction is filtered and washed through a filter to remove residual solvents, inorganic salts and other impurities to obtain a spinning solution.

[0102] (5) Extrude the spinning solution through a spinneret into a coagulation bath, and as-spun fibers are obtained after solidification and shaping.

[0103] Extrude the spinning solution through the micropores in the spinneret to form fine filaments. The extruded fine filaments immediately enter the coagulation bath and are solidified to form as-spun fibers.

[0104] (6) Stretch, wash and dry the as-spun fibers, and then perform heat setting using a mold temperature controller for 80 min. The temperature control during the heat setting process adopts exactly the same steps as in Example 1 of this application.

[0105] After obtaining the as-spun fibers from the coagulation bath, stretch them to enhance their strength and toughness, and then wash the stretched as-spun fibers to remove residual solvents and coagulants. The washing is performed with clear water; after washing, drying is performed using a drying device at a temperature of 150 °C.

[0106] (7) Aramid fibers are obtained after heat setting is completed.

[0107] Example 3

[0108] Please refer to Figure 1 , which shows a process flow chart of a production and processing process of a high-performance aramid fiber provided in Example 3 of this application. The process includes the following steps:

[0109] (1) Dissolve phenylenediamine in an amide polar organic solvent to obtain an organic solution of m-phenylenediamine, and cool it down.

[0110] In this example, phenylenediamine is dissolved in N,N-dimethylacetamide to obtain an organic solution of m-phenylenediamine. Among them, the mass ratio of phenylenediamine to N,N-dimethylformamide is 1:8. Cool the organic solution of m-phenylenediamine to -15 °C.

[0111] (2) Add isophthaloyl chloride to the cooled organic solution of m-phenylenediamine for pre-polycondensation reaction.

[0112] In this example, isophthaloyl chloride was added to the cooled organic solution of m-phenylenediamine. Among them, the molar ratio of m-phenylenediamine to isophthaloyl chloride in the organic solution of m-phenylenediamine was 1:0.8, the time for pre-polycondensation reaction was 60 min, and the temperature was -10 °C.

[0113] (3) After the pre-polycondensation reaction, add isophthaloyl chloride again for polycondensation reaction to obtain a polycondensate.

[0114] After the pre-polycondensation reaction was completed, isophthaloyl chloride was added again to the organic solution of m-phenylenediamine to which isophthaloyl chloride had been added. Among them, during the process of adding isophthaloyl chloride again, the molar ratio of m-phenylenediamine to isophthaloyl chloride was ensured to be 1:0.2. The time for polycondensation reaction was 60 min, and the temperature was 4 °C.

[0115] (4) Add an alkaline solution to the polycondensate for neutralization reaction; filter the neutralization reaction product to obtain a spinning solution.

[0116] Add potassium hydroxide solution to the polycondensate for neutralization reaction. The temperature of the neutralization reaction was 80 °C, and the time was 10 min. The slurry after the neutralization reaction was filtered and washed through a filter to remove residual solvents, inorganic salts, and other impurities to obtain a spinning solution.

[0117] (5) Extrude the spinning solution through a spinneret into a coagulation bath, and obtain a nascent fiber after solidification molding.

[0118] Extrude the spinning solution through the micropores in the spinneret to form fine filaments. The extruded fine filaments immediately enter the coagulation bath and solidify to form nascent fibers.

[0119] (6) Stretch, wash, and dry the nascent fiber, and then perform heat setting using a mold temperature controller. The time for heat setting was 100 min. The temperature control during the heat setting process adopted exactly the same steps as in Example 1 of this application.

[0120] After obtaining the nascent fiber from the coagulation bath, stretch it to enhance its strength and toughness, and then wash the stretched nascent fiber to remove residual solvents and coagulants. The washing was carried out with clean water; after washing, it was dried using a drying device, and the drying temperature was 200 °C.

[0121] (7) Obtain aramid fiber after heat setting.

[0122] Comparative Example 1

[0123] During the heat setting process of aramid fiber production, the temperature is maintained at 400 °C, and the rest is carried out according to the same process steps and parameters as in Example 1 of this application to obtain the prepared aramid fiber.

[0124] Comparative Example 2

[0125] During the heat setting process of aramid fiber production, the temperature is maintained at 400 °C, and the rest is carried out according to the same process steps and parameters as in Example 2 of this application to obtain the prepared aramid fiber.

[0126] Comparative Example 3

[0127] During the heat setting process of aramid fiber production, the temperature is maintained at 400 °C, and the rest is carried out according to the same process steps and parameters as in Example 3 of this application to obtain the prepared aramid fiber.

[0128] For the aramid fibers prepared in the examples and comparative examples of this application, their physical properties were tested, and the test results are shown in Table 1.

[0129] Table 1 Schematic diagram of the physical properties of aramid fiber

[0130]

[0131] As can be seen from Table 1, by regulating the temperature in real time during the heat setting process of aramid fiber, the present application significantly improves the breaking strength, elongation at break and elastic modulus of aramid fiber, and high-performance aramid fiber is obtained.

[0132] It should be noted that: the above-mentioned sequence of the embodiments of the present application is only for description and does not represent the advantages and disadvantages of the embodiments. And the above describes specific embodiments of this specification. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0133] Each embodiment in this specification is described in a progressive manner. The same or similar parts between each embodiment can be referred to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

[0134] The above-described embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them; modifying the technical solutions recorded in the foregoing embodiments or equivalently replacing some of the technical features does not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of each embodiment of the present application, and should all be included within the protection scope of the present application.

Claims

1. A production and processing technology for high-performance aramid fiber, characterized in that: The process includes the following steps: Dissolving phenylenediamine in an amide polar organic solvent to obtain an m-phenylenediamine organic solution, and cooling the solution; Adding isophthaloyl chloride to the cooled m-phenylenediamine organic solution to carry out a pre-polycondensation reaction; After the pre-polycondensation reaction, isophthaloyl chloride is added again for polycondensation reaction to obtain a polycondensate; adding an alkaline solution to the polycondensate for neutralization reaction; filtering the neutralization reaction product to obtain a spinning solution; The spinning solution is extruded through a spinneret into a coagulation bath, and after coagulation and forming, a primary fiber is obtained; The spun fibers are stretched, washed, and dried, and then heat-set using a mold temperature controller. The temperature of the circulating hot fluid in the mold temperature controller and the temperature of the mold are collected at each moment during the heat-setting process. Analyze the fitting deviations of each extreme point of the temperature of the circulating hot fluid at all times during the heat setting process before and after fitting, and obtain the separation coefficients between each extreme point before fitting and each extreme point after fitting; Determine the extreme value points before fitting corresponding to each extreme value point after fitting based on the phase separation coefficient, and use the extreme value points before fitting corresponding to each extreme value point after fitting to divide all moments in the heat setting process to obtain each time period; Analyze the difference between the temperature of the circulating hot fluid and the temperature of the mold at all times in each time period, as well as the numerical distribution of the difference, to obtain the thermal interaction interference degree of each time period; obtain the current temperature control coefficient in the heat setting process through the distribution range of the difference in all time periods and the thermal interaction interference degree; Adjust the control parameters in the PID control algorithm based on the temperature control coefficient, and use the PID control algorithm to control the temperature at the current moment in the heat setting process; After heat setting, aramid fiber is obtained.

2. The production and processing technology of a high-performance aramid fiber according to claim 1, characterized in that: The amide polar organic solvent includes: N, N-dimethylformamide and N, N-dimethylacetamide; the mass ratio of the phenyldiammonium to the amide polar organic solvent is 1:7-8.

3. The production and processing technology of a high-performance aramid fiber according to claim 1, characterized in that: The temperature is lowered to -20 to -15°C; the molar ratio of the intermediate phenylenediamine to isophthaloyl chloride in the pre-polycondensation reaction is 1:0.8; the pre-polycondensation reaction time is 40 to 60 minutes, and the temperature is -20 to -10°C.

4. The production and processing technology of high-performance aramid fiber according to claim 1, characterized in that: The molar ratio of phenylenediamine to isophthaloyl chloride is 1:0.2 when isophthaloyl chloride is added again; the time for the polycondensation reaction is 45 to 60 minutes, and the temperature is -4 to 4°C.

5. The production and processing technology of high-performance aramid fiber according to claim 1, characterized in that: The step of adding an alkaline solution to the polycondensate for neutralization reaction comprises: The alkaline solution includes sodium hydroxide solution, calcium hydroxide solution and potassium hydroxide solution; the temperature of the neutralization reaction is 55-80° C. and the time is 5-10 minutes.

6. The production and processing technology of high-performance aramid fiber according to claim 1, characterized in that: The drying temperature is 100-200° C.; the heat setting time is 60-100 minutes.

7. The production and processing technology of high-performance aramid fiber according to claim 1, characterized in that: The determination of the phase separation coefficient includes: Obtain each extreme point in the fitting curve of the temperature of the circulating hot fluid at all times during the heat setting process, which is recorded as the first extreme point; obtain each extreme point in the temperature of the circulating hot fluid at all times during the heat setting process, which is recorded as the second extreme point; The time interval and the temperature difference between any first extreme point and any second extreme point are calculated; the separation coefficient between any first extreme point and any second extreme point is: the fusion result of the time interval and the temperature difference.

8. The production and processing process of high-performance aramid fiber according to claim 7, characterized in that: The determination of each time period includes: For each first extreme point, the second extreme point with the smallest separation coefficient is obtained as the corresponding point of each first extreme point, and the time of all the corresponding points is used as the segmentation point to obtain each time period.

9. The production and processing process of a high-performance aramid fiber according to claim 1, characterized in that: The determination of the thermal interaction interference degree includes: Calculate the difference between the temperature of the circulating hot fluid and the temperature of the mold at each moment in each time period, and record it as the first difference; calculate the mean of all the first differences in each time period, and count the difference between the number of the first differences less than the mean and the number greater than the mean in each time period, and record it as the second difference; The difference between the first difference of each moment in each time period and its adjacent moment is calculated and recorded as the third difference. The thermal interaction interference degree is the fusion result of the second difference of each time period and the average of all the third differences.

10. The production and processing process of high-performance aramid fiber according to claim 9, characterized in that: The determination of the temperature control coefficient includes: Calculate the average value of all the first differences in each time period, calculate the ratio of the range to the mean of the average value in all time periods during the heat setting process, and the temperature control coefficient is the fusion result of the ratio and the thermal interaction interference degree in all time periods during the heat setting process; The control parameters are adjusted as follows: Where D is the current differential parameter of the PID control algorithm, D' is the historical differential parameter of the PID control algorithm before the current moment, K is the current temperature control coefficient in the heat setting process, Z is the preset threshold, exp() is an exponential function with a natural constant as the base, P is the current proportional parameter of the PID control algorithm, and P' is the historical proportional parameter of the PID control algorithm before the current moment.

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