A method for preparing antibacterial, heat-retaining, fire-retardant polyimide yarn

Abstract

The present invention provides a method for preparing an antibacterial, heat-insulating, fire-resistant and flame-retardant polyimide yarn, comprising the steps of pre-spinning treatment, carding, drawing, spinning and winding of polyimide fibers. Pre-spinning treatment is to improve the antistatic properties of the fiber and further reduce its spinning difficulty. The spinning yarn prepared by the present invention has high strength, antibacterial properties, and has high temperature resistance, flame retardancy, insulation, radiation resistance and corrosion resistance. After further yarn performance testing, the spinning yarn has a CV value of 12.44%, fine sections are 138 / km to 80 / km, thick sections are 101 / km to 50 / km, cotton knots are 9 / km to 21 / km, hairiness H value is 3.7, fine yarn breaking strength is 25.08cN / tex, strong CV value is 23.65%, and elongation at break is 9.4%. The quality of the polyimide yarn in this state meets the weaving requirements and can be produced in large quantities.

Description

Technical Field

[0001] The invention relates to the technical field of functional yarn preparation, and in particular to a method for preparing antibacterial, warm-keeping, fire-proof and flame-retardant polyimide yarn. Background Art

[0002] The very stable aromatic heterocyclic structure in the polyimide molecule makes it show excellent properties that other polymer materials cannot match, especially its high temperature and low temperature resistance. Its thermal decomposition temperature can reach 600℃, which is one of the polymers with the highest thermal stability so far. Due to the existence of the imide ring structure characteristics, polyimide fiber has good mechanical properties, high temperature resistance, flame retardancy, insulation, radiation resistance, antibacterial and corrosion resistance. It can be made into textiles for various special occasions. Due to its high and low temperature resistance, flame retardancy, no melting drop, self-extinguishing and excellent thermal insulation, polyimide fiber thermal insulation protective clothing is comfortable to wear, has good skin adaptability, is permanently flame retardant, and has stable dimensions, good safety and long service life. Compared with other fibers, due to the low thermal conductivity of the material itself, it is also an excellent thermal insulation material.

[0003] Therefore, as a polymer material, it has become an indispensable material in many fields. Polyimide fibers are fluffy, have poor cohesion of limiters, and poor spinnability. They need to go through multiple process adjustments before they can be industrialized. Lianyungang Aoshen New Materials Co., Ltd. adopts the dry spinning technology of Donghua University and has also formed the industrialization of polyimide. Due to the particularity of the physical properties of polyimide, it is easy to wrap around the rubber roller during the spinning stage. In order to ensure good spinning process and spinning quality, polyimide must be pre-treated in the pre-spinning stage. In order to better utilize the excellent performance of polyimide fibers, we optimized the design of the spinning process and carried out trial spinning and product development of polyimide fibers.

[0004] To this end, we disclose a method for preparing antibacterial, heat-insulating, fire-resistant and flame-retardant polyimide yarn. Summary of the invention

[0005] The invention aims to provide a method for preparing antibacterial, heat-retaining, fire-resistant and flame-retardant polyimide yarn.

[0006] To achieve the above object, the present invention proposes the following technical solutions:

[0007] A method for preparing antibacterial, heat-retaining, fire-retardant polyimide yarn comprises the following steps:

[0008] (1) Raw material preparation: The length of the polyimide fiber is 35-38 mm, the linear density is 1.60-1.67 dtex, the density is 1.40-1.54 g / m3, the breaking strength is 3.0-3.2 GPa, and the elongation is 1.50-2.15%;

[0009] (2) Pre-spinning pretreatment: spraying a modified non-ionic antistatic agent solution onto the polyimide fiber at a temperature of 25-28° C. and a relative humidity of 65-70%, and storing the fiber under such conditions for more than 24 hours;

[0010] (3) Spinning design. Polyimide spinning design includes the following steps:

[0011] a. Carding process: The fiber is fed into the opener, and after opening, it is sent to the feeding box through the pipeline. The feeding box controls the feeding speed and feeds the fiber continuously and evenly into the carding machine to be spun into carded sliver;

[0012] b. Drawing process: feeding the raw sliver obtained in step a into the drawing frame, using a three-step drawing process;

[0013] c. Spinning process: the fiber strips obtained in step b are spun into fine yarn through a roving frame and a spinning frame respectively;

[0014] d. Winding process: spinning the spun yarn obtained in step c into bobbins through a bobbin winding machine;

[0015] e. Shaping process: the bobbin yarn of step d is subjected to doubling, steaming and double twisting in sequence to obtain double twisted yarn.

[0016] On the basis of the above scheme and as a preferred scheme of the above scheme, the polyimide fiber has a length of 38 mm, a linear density of 1.67 dtex, and a density of 1.44 g / m 3 , breaking strength is 3.1GPa and elongation is 2%.

[0017] On the basis of the above scheme and as a preferred scheme of the above scheme, the carding related parameters of the spinning design step a are: cylinder speed 326r / min, licker-in speed 789r / min, cover speed 326mm / min, doffer speed 31.4r / min, large pressure roller stripping speed 179.37m / min; carding drafting process parameters: stripping roller to doffer 1.0092 times, lower roller to stripping roller 1.12 times, upper roller to lower roller 1.0 times, large pressure roller to doffer 1.58 times, large pressure roller to lower pressure roller 1.24 times, small pressure roller to large pressure roller 1.12 times, small pressure roller to doffer 1.981 times, mechanical drafting 74.6 times.

[0018] On the basis of the above scheme and as a preferred scheme of the above scheme, the spinning design step b adopts three-pass drawing, each of which has 8 strands, the roller spacing is 10mm×16mm, and the mechanical drafting efficiency is 0.98.

[0019] On the basis of the above scheme and as a preferred scheme of the above scheme, the drawing process parameters of each pass of the spinning design step b are:

[0020] Head and weight, 21.5g / 5m, mechanical draft ratio is 8.258, calculated draft ratio is 7.963;

[0021] Second, the basis weight is 20.8g / 5m, the mechanical draft ratio is 8.191, and the calculated draft ratio is 8.269;

[0022] Three-in-one, the basis weight is 19.5g / 5m, the mechanical stretching ratio is 8.444, and the calculated stretching ratio is 8.533.

[0023] On the basis of the above scheme and as a preferred scheme of the above scheme, in the spinning design step c, the main process parameters of the roving are configured as follows: roving dry weight 3.5g / 10m, mechanical draft 11.24 times, calculated draft 11.143 times, drafting efficiency 0.98, rear zone draft 1.21 times; roving twist 32.6 twists / 10cm, twist coefficient 61, spindle speed 800r / min; jaw gauge 6.5mm, roller diameter 28mm×28mm×25mm×28mm, roller pressure 120N×200N×150N×150N, front roller speed 262r / min;

[0024] In the spinning process, EJM128K spinning frame is used to produce polyimide yarn. The main process parameters of the spinning are: mechanical draft 56.45 times, calculated draft 47.3 times, drafting efficiency 0.95, back zone draft 1.32 times, twist coefficient 331, spinning twist 86 twists / 10cm; spindle speed 13500r / min, front roller speed 200r / min, roller pressure 160N×100N×140N, roller gauge 21mm×37mm, jaw gauge 3.0mm; PG1 steel ring (inner diameter 42mm) and BS type 3 / 0 wire ring are used.

[0025] On the basis of the above scheme and as a preferred scheme of the above scheme, the polyimide fiber yarn has a CV value of 12.44%, 138 to 80 thin sections / km, 101 to 50 thick sections / km, and 9 to 21 neps / km.

[0026] On the basis of the above scheme and as a preferred scheme of the above scheme, the modified non-ionic antistatic agent solution is composed of the following substances in parts by weight: 50-100 parts of dimethyl terephthalate, 30-40 parts of PEG-400, 30-40 parts of PEG-600, 30-40 parts of ethylene glycol, 20-40 parts of adipic acid, 20-40 parts of zinc oxide, 20-30 parts of a mixture of antimony trioxide and triphenyl phosphite, and the remainder is water; wherein the molar ratio of PEG-400 to PEG-600 is 1:2, and the mass ratio of antimony trioxide to triphenyl phosphite is 1:1.

[0027] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0028] The invention discloses a method for preparing an antibacterial, heat-insulating, fire-proof and flame-retardant polyimide yarn. First, the polyimide fiber is subjected to a pre-spinning treatment to improve its antistatic performance, and then the yarn is spun through the processes of carding, drawing, spinning and winding. The spinning yarn has high strength, antibacterial properties, and has high temperature resistance, flame retardancy, insulation, radiation resistance and corrosion resistance. After further yarn performance testing, the hairiness H value is 3.7, the spun yarn breaking strength is 25.08 cN / tex, the strength CV value is 23.65%, and the breaking elongation is 9.4%. The quality of the polyimide yarn in this state meets the weaving requirements and can be produced in large quantities.

[0029] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered part of the present subject matter disclosure to the extent such concepts are not mutually inconsistent.

[0030] The foregoing and other aspects, embodiments and features of the present invention will be more fully understood from the following description. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or will be learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0032] Figure 1 It is a process flow chart of the present invention;

[0033] Figure 2 is the chemical reaction equation of the modified nonionic antistatic agent of the present invention;

[0034] Figure 3 The present invention is a clothing fabric woven from yarns in different shaping processes. Figure 3 The left picture shows a yarn knitted product that is twisted twice and then steamed. Figure 3 The picture on the right shows a woven product made by steaming the yarn and then twisting it twice. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0036] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] Based on the development of science and technology and the continuous improvement of textile requirements, the demand for polyimide fibers continues to rise, and its spinning process is constantly optimized and improved. Polyimide fibers have the advantages of antibacterial and fire retardant, and it is extremely urgent to solve the problem of continuous optimization of polyimide spinning process and mass production.

[0038] Specifically, the present invention discloses a method for preparing an antibacterial, heat-insulating, fire-retardant polyimide yarn, comprising the following steps:

[0039] (1) Raw material preparation: The length of the polyimide fiber is 35-38 mm, the linear density is 1.60-1.67 dtex, the density is 1.40-1.54 g / m3, the breaking strength is 3.0-3.2 GPa, and the elongation is 1.50-2.15%;

[0040] (2) Pre-spinning pretreatment: spraying a modified non-ionic antistatic agent solution onto the polyimide fiber at a temperature of 25-28° C. and a relative humidity of 65-70%, and storing the fiber under such conditions for more than 24 hours;

[0041] (3) Spinning design. Polyimide spinning design includes the following steps:

[0042] a. Carding process: The fiber is fed into the opener, and after opening, it is sent to the feeding box through the pipeline. The feeding box controls the feeding speed and feeds the fiber continuously and evenly into the carding machine to be spun into carded sliver;

[0043] b. Drawing process: feeding the raw sliver obtained in step a into the drawing frame, using a three-step drawing process;

[0044] c. Spinning process: the fiber strips obtained in step b are spun into fine yarn through a roving frame and a spinning frame respectively;

[0045] d. Winding process: spinning the spun yarn obtained in step c into bobbins through a bobbin winding machine;

[0046] e. Shaping process: the bobbin yarn of step d is subjected to doubling, steaming and double twisting in sequence to obtain double twisted yarn.

[0047] Specifically, the polyimide fiber is selected from the cotton-type polyimide fiber of Changchun Gaoqi Polyimide Material Co., Ltd., with a length of 38 mm, a linear density of 1.67 dtex, and a density of 1.44 g / m 3 , breaking strength is 3.1GPa, elongation is 2%. Polyimide is fluffy and soft, with poor cohesion between fibers, low moisture regain, and poor antistatic ability. The fibers are easy to fly and float during operation, and it is more difficult to gather into a net. Therefore, it is necessary to pre-treat the fibers with antistatic agent. Specifically, a modified non-ionic antistatic agent solution is sprayed on the polyimide fibers.

[0048] The modified nonionic antistatic agent solution is composed of the following materials in parts by weight: 50-100 parts of dimethyl terephthalate, 30-40 parts of PEG-400, 30-40 parts of PEG-600, 30-40 parts of ethylene glycol, 20-40 parts of adipic acid, 20-40 parts of zinc oxide, 20-30 parts of a mixture of antimony trioxide and triphenyl phosphite, and the balance is water; wherein the molar ratio of PEG-400 to PEG-600 is 1:2, and the mass ratio of antimony trioxide to triphenyl phosphite is 1:1. In the present invention, the preparation of the modified nonionic antistatic agent solution includes four parts: preparation of polyethylene glycol derivatives, ester exchange, polycondensation and solution preparation. The preparation of the polyethylene glycol derivative is to place a mixture of PEG-400 and PEG-600 in a molar ratio of 1:2, adipic acid, and zinc oxide in a molar ratio of 1:2:1 in a reaction vessel, heat to 140°C under a nitrogen protection environment, and then increase the temperature to 160°C at a heating rate of 1°C per minute; then start to reduce the pressure, and finally increase the temperature to 200°C at the same rate, keep the reaction in this state for 4 hours, and obtain the polyethylene glycol derivative, whose chemical formula is as follows:

[0049] HO(CH2CH2O) m OC(CH2)4COOZnOOC(CH2)4COOH

[0050] During the reaction, the mixture of PEG-400 and PEG-600 can easily undergo oxidation reaction at high temperature, so the reaction system is protected by nitrogen. In addition, water is generated in the reaction, so water is removed by decompression. Zinc oxide is used because it has good antistatic properties, antibacterial and anti-ultraviolet advantages, and can also play a catalytic role in the subsequent polycondensation reaction. Moreover, zinc oxide is white and does not affect the color of the textile.

[0051] Further, the transesterification process is as follows Figure 2 As shown, dimethyl terephthalate, a mixture of PEG-400 and PEG-600, and ethylene glycol are heated to melt, a catalyst zinc acetate is added, the temperature is raised to 165°C under nitrogen protection, and the reaction is performed for 3 hours. Further, polyethylene glycol derivatives, antimony trioxide and triphenyl phosphite are added to the transesterification reaction system, and the mixture is heated to 240°C under nitrogen protection, and then the vacuum pump is turned on until the distillate no longer increases and the polycondensation reaction is completed. Finally, the product is prepared into a solution, and the ratio of the antistatic agent to water is preferably 1:100, and then sprayed on the polyimide fiber. The nonionic antistatic agent of the present invention is mainly adsorbed on the fiber surface to form a water-absorbing molecular layer, which serves as a hygroscopic and conductive medium, while improving the hygroscopicity of the yarn, reducing its surface resistivity, thereby improving the antistatic performance.

[0052] Furthermore, in the polyimide spinning process, the problems that are prone to occur in the combing process are: abnormal fiber transfer, net falling under the belly of the doffer, and the cotton net triangle area cannot be formed into strips. Therefore, the cotton is combed by a fixed light weight, slow speed, and tight spacing. The relevant parameters of the cotton combing in the spinning design step a are: cylinder speed 326r / min, licker-in speed 789r / min, cover speed 326mm / min, doffer speed 31.4r / min, and large pressure roller stripping speed 179.37m / min; cotton combing drafting process parameters: cotton stripping roller to doffer 1.0092 times, lower roller to cotton stripping roller 1.12 times, upper roller to lower roller 1.0 times, large pressure roller to doffer 1.58 times, large pressure roller to lower pressure roller 1.24 times, small pressure roller to large pressure roller 1.12 times, small pressure roller to doffer 1.981 times, mechanical drafting 74.6 times. Such a carding process can enhance the carding effect of polyimide fibers, improve the straightness of the fibers, and ensure the excellent performance of the card clothing.

[0053] Furthermore, the spinning design step b adopts three drawing passes, each drawing pass has 8 strands, the roller spacing is 10mm×16mm, and the mechanical drafting efficiency is 0.98. The process parameters of each drawing pass are:

[0054] Head and weight, 21.5g / 5m, mechanical draft ratio is 8.258, calculated draft ratio is 7.963;

[0055] Second, the basis weight is 20.8g / 5m, the mechanical draft ratio is 8.191, and the calculated draft ratio is 8.269;

[0056] Three-in-one, the basis weight is 19.5g / 5m, the mechanical stretching ratio is 8.444, and the calculated stretching ratio is 8.533.

[0057] This ensures the uniform distribution of fibers in the yarn and improves the straightening and parallelism of the fibers.

[0058] Furthermore, due to the low moisture regain and high static electricity of polyimide fiber, polyimide is easy to wrap around the rubber roller, and even the roving will become loose and rotten when the twist is low. Therefore, in the roving process, the pressure of the rubber roller should be appropriately increased and the jaw spacing should be reduced. Therefore, in the spinning design step c, the main process parameters of the roving are configured as follows: roving dry weight 3.5g / 10m, mechanical draft 11.24 times, calculated draft 11.143 times, drafting efficiency 0.98, rear zone draft 1.21 times; roving twist 32.6 twists / 10cm, twist coefficient 61, spindle speed 800r / min; jaw spacing 6.5mm, roller diameter 28mm×28mm×25mm×28mm, roller pressure 120N×200N×150N×150N, front roller speed 262r / min. In addition, the surface of polyimide fiber is relatively smooth, so the twist coefficient of roving should be appropriately increased to increase the cohesion between fibers and reduce the deterioration of roving evenness due to unexpected elongation. In order to meet the antistatic requirements, the humidity in the workshop can also be controlled at 60%-65%, which can also improve the evenness level of roving.

[0059] Furthermore, the spinning process is carried out in accordance with the principle of "large gauge, medium twist, heavy pressure, medium-thick rubber roller, medium speed, small back-zone draft, small jaw, and suitable temperature and humidity". The spun yarn prepared by the present invention has a public count of 20Nm-80Nm. In the spinning process, the EJM128K spinning frame is used to produce polyimide yarn. The main process parameters of the spinning are: mechanical draft 56.45 times, calculated draft 47.3 times, drafting efficiency 0.95, back-zone draft 1.32 times, twist coefficient 331, spun yarn twist 86 twists / 10cm; spindle speed 13500r / min, front roller speed 200r / min, roller pressure 160N×100N×140N, roller gauge 21mm×37mm, jaw gauge 3.0mm; PG1 steel collar (inner diameter 42mm) and BS type 3 / 0 wire ring are used. The polyimide fiber yarn prepared by the invention has a CV value of 12.44%, thin sections of 138 to 80 pieces / km, thick sections of 101 to 50 pieces / km, and neps of 9 to 21 pieces / km.

[0060] Furthermore, the polyimide yarn is sequentially subjected to the processes of winding, doubling, steaming, and doubly twisting to obtain a doubly twisted yarn. Due to the uniqueness of polyimide fibers, they need to be subjected to a steaming process and then double twisting to obtain polyimide yarn with a good shaping effect. Among them, the steaming process includes "preheating the body-vacuum-heating", specifically, the temperature of the steaming machine is controlled at 60-120°C, kept warm for 6-8 hours, and then vacuumed to lower the boiling point of water to produce the required low-temperature saturated steam. Finally, the steamed yarn is naturally dried before proceeding to the next double twisting process. The body is preheated during the steaming process because water stains on the yarn are a common problem in special preheating systems. Therefore, it is necessary to preheat the steam yarn. Further, such as Figure 3 As shown, Figure 3 The clothing fabric is woven from yarns in different shaping processes of the present invention. Figure 3 The left one is a yarn knitted product that is twisted twice and then steamed. Figure 3 The right side shows a yarn knitted product after steaming the yarn and then twisting it twice. It can be seen that the yarn prepared by the conventional process of twisting the yarn twice before steaming and shaping has obvious depressions and unevenness in the clothing fabric woven therefrom, and is very likely to produce defective products. However, the polyimide yarn prepared by the shaping process of the present invention has a good shaping effect, and the textile woven therefrom has no obvious depression and is extremely flat.

[0061] The above polyimide yarn was subjected to relevant performance tests, taking the spun yarn count of 60Nm as an example, the relevant data of the yarn product obtained are shown in the following table:

[0062] Table 1 Yarn product parameters

[0063]

[0064] From the above experimental results, it can be seen that the CV value of the polyimide fiber yarn is 12.44%, -40% fines are 138 pieces / km, -50% fines are 80 pieces / km, +35% thick sections are 101 pieces / km, +50% thick sections are 50 pieces / km, +140% cotton knots are 21 pieces / km, and +200% cotton knots are 9 pieces / km. After further yarn performance testing, the hairiness H value is 3.7, the yarn breaking strength is 25.08cN / tex, the strength CV value is 23.65%, and the elongation at break is 9.4%. The quality of the polyimide yarn in this state meets the weaving requirements and can be produced in large quantities.

[0065] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing antibacterial, heat-insulating, fire-retardant polyimide yarn, characterized in that: The following steps are involved: (1) Raw material preparation: The length of polyimide fiber is 35-38 mm, the linear density is 1.60-1.67 dtex, and the density is 1.40-1.54 g / m 3 , breaking strength is 3.0-3.2GPa, elongation is 1.50-2.15%; (2) Pre-spinning pretreatment: spraying a modified non-ionic antistatic agent solution onto the polyimide fiber at a temperature of 25-28° C. and a relative humidity of 65-70%, and storing the fiber under such conditions for more than 24 hours; (3) Spinning design. Polyimide spinning design includes the following steps: a. Carding process: The fiber is fed into the opener, and after opening, it is sent to the feeding box through the pipeline. The feeding box controls the feeding speed and feeds the fiber continuously and evenly into the carding machine to be spun into carded sliver; b. Drawing process: feeding the raw sliver obtained in step a into the drawing frame, using a three-step drawing process; c. Spinning process: the fiber strips obtained in step b are spun into fine yarn through a roving frame and a spinning frame respectively; d. Winding process: spinning the spun yarn obtained in step c into bobbins through a bobbin winding machine; e. Shaping process: the bobbin yarn of step d is subjected to doubling, steaming and double twisting in sequence to obtain double twisted yarn; The yarn steaming process includes "preheating the machine - vacuum - heating", specifically, the temperature of the yarn steamer is controlled at 60-120℃, kept warm for 6-8 hours, and then vacuumed to lower the boiling point of water to produce the required low-temperature saturated steam; the textiles woven from polyimide yarns prepared by the shaping process have high flatness.

2. The method for preparing an antibacterial, heat-retaining, fire-retardant polyimide yarn according to claim 1, characterized in that: The polyimide fiber has a length of 38 mm, a linear density of 1.67 dtex, and a density of 1.44 g / m 3 , breaking strength is 3.1GPa and elongation is 2%.

3. The method for preparing an antibacterial, heat-retaining, fire-retardant polyimide yarn according to claim 1, characterized in that: The carding related parameters of spinning design step a are: cylinder speed 326r / min, licker-in speed 789r / min, cover speed 326mm / min, doffer speed 31.4r / min, large pressure roller sliver output speed 179.37m / min; carding drafting process parameters: stripping roller to doffer 1.0092 times, lower roller to stripping roller 1.12 times, upper roller to lower roller 1.0 times, large pressure roller to doffer 1.58 times, large pressure roller to lower pressure roller 1.24 times, small pressure roller to large pressure roller 1.12 times, small pressure roller to doffer 1.981 times, mechanical draft 74.6 times.

4. The method for preparing an antibacterial, heat-retaining, fire-retardant polyimide yarn according to claim 1, characterized in that: The spinning design step b adopts three-pass drawing, each of which has 8 yarns, the roller spacing is 10mm×16mm, and the mechanical drafting efficiency is 0.

98.

5. The method for preparing an antibacterial, heat-retaining, fire-retardant polyimide yarn according to claim 4, characterized in that: The drawing process parameters of each pass in spinning design step b are: Head and weight, 21.5g / 5m, mechanical draft ratio is 8.258, calculated draft ratio is 7.963; Second, the basis weight is 20.8g / 5m, the mechanical draft ratio is 8.191, and the calculated draft ratio is 8.269; Three-in-one, the basis weight is 19.5g / 5m, the mechanical stretching ratio is 8.444, and the calculated stretching ratio is 8.

533.

6. The method for preparing an antibacterial, heat-retaining, fire-retardant polyimide yarn according to claim 1, characterized in that: In the spinning design step c, the main process parameters of the roving are configured as follows: roving dry weight 3.5g / 10m, mechanical draft 11.24 times, calculated draft 11.143 times, drafting efficiency 0.98, back zone draft 1.21 times; roving twist 32.6 twists / 10cm, twist coefficient 61, spindle speed 800r / min; jaw gauge 6.5mm, roller diameter 28mm×28mm×25mm×28mm, roller pressure 120N×200N×150N×150N, front roller speed 262r / min; In the spinning process, EJM128K spinning frame is used to produce polyimide yarn. The main process parameters of the spinning are as follows: mechanical draft 56.45 times, calculated draft 47.3 times, drafting efficiency 0.95, back zone draft 1.32 times, twist coefficient 331, spinning twist 86 twists / 10cm; spindle speed 13500r / min, front roller speed 200r / min, roller pressure 160N×100N×140N, roller gauge 21mm×37mm, jaw gauge 3.0mm; PG1 steel ring and BS type 3 / 0 steel wire ring are used; the inner diameter of the PG1 steel ring is 42mm.

7. The method for preparing an antibacterial, heat-retaining, fire-retardant polyimide yarn according to claim 1, characterized in that: The polyimide fiber yarn has a CV value of 12.44%, thin sections are 138 to 80 per km, thick sections are 101 to 50 per km, and neps are 9 to 21 per km.

8. The method for preparing an antibacterial, heat-retaining, fire-retardant polyimide yarn according to claim 1, characterized in that: The modified nonionic antistatic agent solution is composed of the following substances in parts by weight: 50-100 parts of dimethyl terephthalate, 30-40 parts of PEG-400, 30-40 parts of PEG-600, 30-40 parts of ethylene glycol, 20-40 parts of adipic acid, 20-40 parts of zinc oxide, 20-30 parts of a mixture of antimony trioxide and triphenyl phosphite, and the balance is water; wherein the molar ratio of PEG-400 to PEG-600 is 1:2, and the mass ratio of antimony trioxide to triphenyl phosphite is 1:1.

Images