Superfine denier polyester filament yarn and preparation method thereof

Abstract

The invention relates to the technical field of textile, and particularly discloses a superfine denier polyester filament yarn and a preparation method thereof. The preparation method of the superfine denier polyester filament yarn comprises the following process steps: S1, crystallizing and drying: polyester fiber slices are added into a drying system for crystallizing and drying, the drying temperature is not higher than 160 DEG C, and the water content of the crystallized and dried polyester slices is not higher than 0.005%; s2, melt spinning: the crystallized and dried polyester fiber slices are conveyed to a screw extruder to be extruded and melted, and the extrusion temperature is not higher than 295 DEG C; s3, cooling and forming: blowing and cooling the spun yarns in an annular blowing manner; s4, drafting and shaping: drafting and shaping the cooled spun yarns; s5, after-finishing, wherein the superfine denier polyester filament yarn is obtained after the after-finishing. The superfine denier polyester filament yarn obtained through the preparation method is not prone to breakage in the production process and has a good antibacterial effect.

Description

Technical Field

[0001] This application relates to the field of textile technology, and more specifically, it relates to an ultra-fine denier polyester filament and a preparation method thereof. Background Art

[0002] With the continuous development of social economy, people's material living standards have also been continuously improved. People are no longer satisfied with the existing demand for textiles, but have more demands on the functions and characteristics of textiles. This requires the development of more products to meet people's different living needs.

[0003] Among them, among many products, ultra-fine denier fibers are finer than conventional fibers. Compared with conventional fibers, they have a softer touch. Compared with natural fibers that are prone to wrinkling and artificial fibers that are prone to airtightness, ultra-fine denier fibers can better overcome these defects. Therefore, ultra-fine denier fibers came into being. For example, ultra-fine denier polyester, ultra-fine denier polyester has soft handfeel, good heat preservation performance, moisture absorption and air permeability and other characteristics, and is widely used in life; however, due to the extremely fine total fineness of ultra-fine denier polyester filaments, they are prone to filament breakage during the production process, which brings problems to the efficient production process of ultra-fine denier polyester filaments. Therefore, there is an urgent need for a preparation method of ultra-fine denier polyester filaments to solve the problem of easy filament breakage of ultra-fine denier polyester filaments during the production process. Summary of the Invention

[0004] In order to improve the problem of easy filament breakage of ultra-fine denier polyester filaments during the production process, this application provides an ultra-fine denier polyester filament and a preparation method thereof.

[0005] The ultra-fine denier polyester filament and the preparation method provided by this application adopt the following technical solutions: A preparation method of an ultra-fine denier polyester filament, comprising the following technological steps: S1, crystallization and drying, adding polyester fiber chips into a drying system for crystallization and drying, the drying temperature is not higher than 160°C, and the water content of the polyester chips after crystallization and drying is not higher than 0.005%; S2, melt spinning, conveying the polyester fiber chips after crystallization and drying to a screw extruder for extrusion and melting, wherein the extrusion temperature is not higher than 295°C; S3, cooling and forming, blowing air to cool the spun yarn, wherein the blowing air cooling method adopts annular blowing; S4, drawing and setting, drawing and setting the cooled spun yarn; S5, post-finishing, obtaining the ultra-fine denier polyester filament after post-finishing.

[0006] Since polyester fiber chips usually contain a certain amount of moisture, usually around 0.3%, the moisture in the chips will cause the polyester fiber to hydrolyze during the melt spinning process, resulting in a decrease in the molecular weight of the polyester fiber, which in turn may affect the spinning process and may cause broken fibers during the spinning process. Through the crystallization and drying step, the crystallinity and softening point of the polyester fiber chips are improved, avoiding blockage during the melt spinning process and reducing the probability of broken fibers during the spinning process.

[0007] During the melt spinning process, if the extrusion temperature is too high, the viscosity of the polyester fiber chips melt will be too high, which will in turn affect the fluidity of the melt, making it more likely for filaments to break and filaments to appear during the spinning process, and will also affect the final breaking strength of the polyester filaments. By controlling the melt extrusion temperature to no more than 295°C, the fluidity of the melt is ensured while reducing the probability of excessive viscosity of the polyester fiber chips and filament breakage.

[0008] When using the conventional side-blowing cooling method, on the one hand, it is difficult to ensure uniform cooling of the inner and outer layers of the spinning bundle, which may lead to uneven tensile stress during the spinning process, and then easily lead to broken fibers; on the other hand, the side-blowing method is also prone to produce certain stress on the spinning when used for ultra-fine denier fibers, which may aggravate the problem of spinning breakage; the use of annular blowing can minimize the problem of uneven tensile stress and breakage of the spinning bundle.

[0009] After the above process steps, the spinning bundle can have good breaking strength during the spinning process and after forming, thereby greatly reducing the occurrence of broken wires in the production process, and is also conducive to the direct post-finishing process of the spinning bundle.

[0010] Preferably, the step S5 includes performing softening and antibacterial finishing on the spun bundle, which is composed of the following process steps: The spinning bundle is immersed in a softening finishing liquid, and the spun bundle is immersed and rolled until the liquid carrying rate is more than 70%, and then allowed to stand at 70-90°C for 40-60 minutes, wherein the softening finishing liquid includes amino silicone oil, sodium lauryl sulfate, and isopropyl alcohol; The spun yarn bundle after softening is immersed in the antibacterial finishing liquid, and after dipping and rolling, it is allowed to stand in a nitrogen environment at 60-70°C for 4-6 hours, and then the spun yarn bundle is cleaned and dried with anhydrous ethanol; The antibacterial finishing liquid includes isopropyl alcohol, epoxypropyl dodecyl dimethyl ammonium chloride and chitosan.

[0011] After the spinning bundle undergoes the above steps of crystallization drying, melt extrusion, cooling forming, and drawing and setting, the spinning bundle can have good breaking strength. By controlling the moisture content and crystallinity of the polyester fiber chips, the temperature and fluidity during melt extrusion, the cooling rate inside the spinning bundle during cooling, and the drawing tension, etc., although the filament diameter of the spinning bundle is small, it can still have good breaking strength, so that the spinning bundle can directly undergo padding and finishing without worrying about a large number of broken filaments occurring during the padding and finishing process. At the same time, due to the large specific surface area of the superfine denier polyester fiber spinning bundle, it can also have a better contact area with the softening finishing liquid and the antibacterial finishing liquid, thus greatly improving the effects of softening finishing and antibacterial finishing.

[0012] Among them, amino silicone oil is used as a softener, and together with sodium dodecyl sulfate (which can make the amino silicone oil better disperse and adsorb on the superfine denier polyester spinning bundle) and isopropyl alcohol, it can better contact the spinning bundle and conduct softening finishing, thereby endowing the superfine denier polyester spinning bundle with a relatively soft hand feeling. And after softening finishing, antibacterial finishing is directly carried out. First of all, chitosan has a certain antibacterial function. By binding to the surface of the polyester spinning bundle after softening finishing through groups such as amino groups on chitosan, chitosan can also exist on the polyester spinning bundle in a certain adsorption and attachment manner, and then endow the superfine denier polyester spinning bundle with certain antibacterial properties.

[0013] In addition, by using the fact that glycidyl dodecyldimethylammonium chloride and amino silicone oil can undergo a quaternization reaction, a certain amount of quaternary ammonium salts are generated on the surface of the superfine denier polyester spinning bundle. While endowing the superfine denier polyester spinning bundle with certain antibacterial properties, it can also form a certain network structure on the surface of the superfine denier polyester spinning bundle, and to a certain extent, it can also improve the breaking strength and elongation rate of the superfine denier polyester spinning bundle, which is beneficial for the subsequent processing and finishing of the superfine denier polyester filament and reduces the probability of broken filaments occurring.

[0014] It should be noted that glycidyl dodecyldimethylammonium chloride can be obtained through commercial channels or can be prepared by reacting N, N-dimethyldodecylamine and epichlorohydrin.

[0015] Preferably, in the step S1, the drying temperature is set to 140 - 155 °C, the wind pressure during drying is 0.03 - 0.10 MPa, and the crystallization drying time is 2 - 5 h.

[0016] Generally speaking, the higher the crystallization drying, the shorter the required drying time. However, if the drying temperature is too high, the viscosity of the polyester fiber slices may increase, which may make it easy for the polyester fiber slices to stick together, thereby affecting the crystallinity of the polyester fiber slices. It may also cause the polyester fiber to break easily during the melt spinning process. Polyester fiber slices usually have a high proportion of amorphous structure. The crystallization of the polyester fiber slices is improved through the crystallization drying process (the increase in crystallinity means the increase in the proportion of directional arrangement structure), and its softening point will also be improved to a certain extent. Ultimately, during the melt spinning process, the polyester fiber slices can reduce the probability of broken wires and improve the breaking strength of polyester filaments.

[0017] Preferably, in step S2, the polyester fiber chips enter the spinning box during the melt extrusion process, wherein the spinning box body temperature is higher than the melt extrusion temperature, the box body temperature is controlled at 290-300°C, and the melt extrusion temperature is 275-293°C.

[0018] Preferably, the spinning box body comprises a first spinning zone and a second spinning zone, wherein the box body temperature of the first spinning zone is higher than the box body temperature of the second spinning zone, wherein the box body temperature of the second spinning zone is 290-295°C.

[0019] If the melt extrusion temperature is too high, the viscosity of the polyester fiber chip melt will be too high, which will in turn affect the fluidity of the melt, making it more likely for filaments to break and filaments to appear during the spinning process, and will also affect the breaking strength of the final polyester filament. By controlling the melt extrusion temperature to 275-293°C, the polyester fiber chip melt can reduce the tension during spinning (through the spinneret hole, etc.) while ensuring fluidity and uniformity, thereby reducing the chance of filament breakage during the spinning process.

[0020] At the same time, the temperature of the spinning box is higher than the melt extrusion temperature, and the purpose of setting the first spinning zone and the second spinning zone is to allow the melt to have a relatively suitable cooling time after extrusion. The temperature gradient of the first spinning zone and the second spinning zone is also for slow cooling to avoid rapid cooling of the melt after extrusion. The reason for the analysis may be that after the melt is quickly cooled, too many and disordered tiny crystal nuclei may be generated, which may cause the spinning tension to be affected during the spinning process, resulting in spinning breakage. Through the above technical solution, the cooling rate of the melt can be slowed down, so that a suitable number of crystal nuclei can be generated inside the fiber during the spinning process, which is conducive to reducing the influence of the tension on it during the spinning process.

[0021] Preferably, in the step S3, the wind pressure of the annular blowing is 20 - 25 MPa, the blowing temperature is 20 - 25 °C, the humidity of the blowing is controlled at 60 - 75%, and the direction of the annular blowing is parallel to the spinning movement direction.

[0022] Due to the relatively large specific surface area of the superfine denier fiber, it is easier to dissipate heat. If the cooling wind pressure is too high and the cooling speed is too fast, it is extremely easy to cause a large temperature gradient inside and outside the superfine denier fiber, resulting in uneven tensile stress during the spinning process and prone to filament breakage; after passing through the first spinning zone and the second spinning zone in step S2, although the temperature of the spinning cooling can be delayed, the spinning tension and breakage can be effectively reduced; however, if the conventional side blowing cooling method is used, on the one hand, it is difficult to ensure uniform cooling of the inner and outer layers of the spinning bundle, resulting in uneven tensile stress during the spinning process and prone to filament breakage; on the other hand, when the side blowing method is used for superfine denier fibers, it is also easy to generate certain stress on the spinning, which may exacerbate the problem of spinning breakage.

[0023] When using annular blowing and controlling the wind pressure at 20 - 25 MPa, the blowing temperature at 20 - 25 °C, the humidity of the blowing at 60 - 75%, and the direction of the annular blowing parallel to the spinning movement direction, we find that the spinning is relatively stable during the cooling process, which can significantly reduce the filament breakage. At the same time, under such a cooling method, the unevenness rate of the spun yarn formed is also relatively low, and it has a good elongation at break.

[0024] Preferably, in the step S4, the draw ratio is 2 - 2.5, the draw temperature is controlled at 80 - 90 °C, and the setting temperature is controlled at 120 - 130 °C.

[0025] As a relatively crucial step in superfine denier polyester spinning, the draw temperature and draw ratio will further affect the unevenness rate of the spun yarn. In this application, by controlling the draw ratio at 2 - 2.5 and the draw temperature at 80 - 90 °C, the spinning bundle can run relatively smoothly, and at the same time, it has an appropriate residence time for annular blowing cooling, so that the unevenness rate of the finally formed spun yarn is relatively low, which is beneficial to reducing the probability of filament breakage during the subsequent processing and production process; if the draw ratio is too high, it will lead to too large draw tension. Even if annular blowing is used during the cooling process to make the internal crystalline region distribution of the spinning bundle relatively uniform, it is still impossible to avoid the situation of the spinning bundle shaking due to the influence of the draw tension, resulting in filament breakage of the spinning bundle; if the draw temperature is too low, it will lead to poor molecular mobility of the polyester fiber, which is not conducive to uniform draw extension and will also result in filament breakage.

[0026] In addition, in this application, by controlling the setting temperature to be 120 - 130 °C, it is possible to better eliminate the applications remaining inside the spun bundle during processes such as drawing, so that the structure of the spun bundle has better breaking strength and stability. If the setting temperature is too high, it will cause the crystallinity of the fiber to further increase, which is not conducive to the subsequent finishing process.

[0027] This application provides an ultrafine denier polyester filament, which is prepared by the preparation method of the above-mentioned ultrafine denier polyester filament.

[0028] In summary, this application has the following beneficial effects: 1. By controlling the water content and crystallinity of the raw material of the polyester fiber chips, the temperature and fluidity during melt extrusion, the cooling rate and drawing tension inside the spun bundle during cooling, etc., in this application, although the linear diameter of the spun bundle is small, it still has good breaking strength, so that the spun bundle can directly undergo padding finishing without worrying about a large number of broken filaments occurring during the padding finishing process. At the same time, due to the relatively large specific surface area of the ultrafine denier polyester fiber spun bundle, it can also have a better contact area with the softening finishing liquid and antibacterial finishing liquid, thus greatly improving the effects of softening finishing and antibacterial finishing.

[0029] 2. In this application, groups such as amino groups on chitosan are combined with the surface of the polyester spun bundle after softening finishing, and using the fact that glycidyl dodecyldimethylammonium chloride and amino silicone oil can undergo quaternization reaction, a certain number of quaternary ammonium salts are generated on the surface of the ultrafine denier polyester spun bundle. While endowing the ultrafine denier polyester spun bundle with certain antibacterial properties, it can also form a certain network structure on the surface of the ultrafine denier polyester spun bundle, which can also improve the breaking strength and elongation rate of the ultrafine denier polyester spun bundle to a certain extent, facilitating the subsequent processing and finishing of the ultrafine denier polyester filament and reducing the probability of broken filaments. Detailed implementation manners

[0030] The following further elaborates on this application in conjunction with examples. Examples

[0031] Example 1, a preparation method of an ultrafine denier polyester filament, includes the following technological steps: S1, crystallization and drying. Add polyester fiber chips to the drying system for crystallization and drying. Set the drying temperature to 140 °C, the wind pressure during drying to 0.03 MPa, the crystallization and drying time to 5 h, and the water content of the polyester chips after crystallization and drying to 0.003%; S2. Melt spinning: The crystallized and dried polyester fiber chips are conveyed to a screw extruder for extrusion and melting. During the melting and extrusion process, the polyester fiber chips enter the spinning box, where the temperature of the spinning box body is higher than the melting and extrusion temperature, and the melting and extrusion temperature is 275 °C. The spinning box body includes a first spinning zone and a second spinning zone, where the temperature of the box body in the first spinning zone is higher than that in the second spinning zone. The temperature of the box body in the first spinning zone is 295 °C, and the temperature of the box body in the second spinning zone is 290 °C. S3. Cooling and forming: The spun fiber is cooled by blowing air. The blowing air cooling method uses annular blowing. The air pressure of the annular blowing is 2 MPa, the blowing temperature is 20 °C, the humidity of the blowing air is controlled at 60%, and the direction of the annular blowing is parallel to the movement direction of the spun fiber. S4. Drawing and setting: The cooled spun fiber is drawn and set. The draw ratio is 2, the drawing temperature is controlled at 80 °C, and the setting temperature is controlled at 120 °C. S5. Post-treatment: The spun fiber bundle is immersed in a softening finishing solution, padded once and rolled to a liquid pickup rate of more than 70%, and left standing in an environment at 70 °C for 60 min. The softening finishing solution includes amino silicone oil, sodium dodecyl sulfate, and isopropanol. The spun fiber bundle after softening finishing is immersed in an antibacterial finishing solution. The antibacterial finishing solution includes isopropanol, epoxypropyl dodecyldimethyl ammonium chloride, and chitosan. After padding once and rolling, it is left standing in a nitrogen environment at 60 °C. After standing for 6 h, the spun fiber bundle is washed and dried with absolute ethanol to obtain the ultrafine denier polyester filament.

[0032] Example 2. A method for preparing ultrafine denier polyester filament, comprising the following process steps: S1. Crystallization and drying: The polyester fiber chips are added to a drying system for crystallization and drying. The drying temperature is set at 155 °C, the air pressure during drying is 0.10 MPa, the crystallization and drying time is 2 h, and the water content of the polyester chips after crystallization and drying is 0.002%. S2. Melt spinning: The crystallized and dried polyester fiber chips are conveyed to a screw extruder for extrusion and melting. During the melting and extrusion process, the polyester fiber chips enter the spinning box, where the temperature of the spinning box body is higher than the melting and extrusion temperature, and the melting and extrusion temperature is 293 °C. The spinning box body includes a first spinning zone and a second spinning zone, where the temperature of the box body in the first spinning zone is higher than that in the second spinning zone. The temperature of the box body in the first spinning zone is 300 °C, and the temperature of the box body in the second spinning zone is 295 °C. S3. Cooling and forming: The spun fiber is cooled by blowing air. The blowing air cooling method uses annular blowing. The air pressure of the annular blowing is 25 MPa, the blowing temperature is 25 °C, the humidity of the blowing air is controlled at 75%, and the direction of the annular blowing is parallel to the movement direction of the spun fiber. S4, Drawing and setting: Draw and set the cooled spun fiber. The draw ratio is 2.5, the draw temperature is controlled at 90 °C, and the setting temperature is controlled at 130 °C; S5, Post-treatment: Immerse the fiber bundle in a softening finishing solution, dip and roll it once until the liquid pickup rate is over 70%, and let it stand in an environment at 90 °C for 40 min. The softening finishing solution includes amino silicone oil, sodium dodecyl sulfate, and isopropanol; Immerse the fiber bundle after softening finishing in an antibacterial finishing solution. The antibacterial finishing solution includes isopropanol, epoxypropyl dodecyldimethyl ammonium chloride, and chitosan. After dipping and rolling it once, let it stand in a nitrogen environment at 70 °C. After standing for 4 h, wash and dry the fiber bundle with absolute ethanol to obtain the ultrafine denier polyester filament.

[0033] Example 3: A method for preparing ultrafine denier polyester filament, comprising the following process steps: S1, Crystallization and drying: Add polyester fiber chips to a drying system for crystallization and drying. The drying temperature is set at 145 °C, the air pressure during drying is 0.08 MPa, the crystallization and drying time is 3 h, and the water content of the polyester chips after crystallization and drying is 0.0025%; S2, Melt spinning: Convey the polyester fiber chips after crystallization and drying to a screw extruder for extrusion and melting. The polyester fiber chips enter the spinning box during the melting and extrusion process. The temperature of the spinning box body is higher than the melting and extrusion temperature, and the melting and extrusion temperature is 285 °C; The spinning box body includes a first spinning zone and a second spinning zone. The temperature of the box body in the first spinning zone is higher than that in the second spinning zone. The temperature of the box body in the first spinning zone is 295 °C, and the temperature of the box body in the second spinning zone is 290 °C; S3, Cooling and forming: Blow air to cool the spun fiber. The air blowing cooling method uses annular air blowing. The air pressure of the annular air blowing is 22 MPa, the blowing temperature is 22 °C, the humidity of the blowing is controlled at 70%, and the direction of the annular air blowing is parallel to the moving direction of the spun fiber; S4, Drawing and setting: Draw and set the cooled spun fiber. The draw ratio is 2.3, the draw temperature is controlled at 85 °C, and the setting temperature is controlled at 125 °C; S5, Post-treatment: Immerse the fiber bundle in a softening finishing solution, dip and roll it once until the liquid pickup rate is over 70%, and let it stand in an environment at 85 °C for 50 min. The softening finishing solution includes amino silicone oil, sodium dodecyl sulfate, and isopropanol; Immerse the fiber bundle after softening finishing in an antibacterial finishing solution. The antibacterial finishing solution includes isopropanol, epoxypropyl dodecyldimethyl ammonium chloride, and chitosan. After dipping and rolling it once, let it stand in a nitrogen environment at 65 °C. After standing for 5 h, wash and dry the fiber bundle with absolute ethanol to obtain the ultrafine denier polyester filament.

[0034] Example 4, a preparation method of superfine denier polyester filament, comprising the following process steps: S1, crystallization and drying: adding polyester fiber chips into a drying system for crystallization and drying, setting the drying temperature at 145°C, the air pressure during drying at 0.08 MPa, the crystallization and drying time at 3 h, and the water content of the polyester chips after crystallization and drying at 0.0025%; S2, melt spinning: conveying the crystallized and dried polyester fiber chips to a screw extruder for extrusion and melting. During the melt extrusion process, the polyester fiber chips enter the spinning box, where the temperature of the spinning box body is higher than the melt extrusion temperature, and the melt extrusion temperature is 285°C. The spinning box body includes a first spinning zone and a second spinning zone, where the temperature of the first spinning zone is higher than that of the second spinning zone. The temperature of the first spinning zone is 295°C, and the temperature of the second spinning zone is 290°C; S3, cooling and forming: blowing air to cool the spun yarn. The blowing air cooling method adopts annular blowing, the air pressure of the annular blowing is 22 MPa, the blowing temperature is 22°C, the humidity of the blowing air is controlled at 70%, and the direction of the annular blowing is parallel to the movement direction of the spun yarn; S4, drawing and setting: drawing and setting the cooled spun yarn, with a draw ratio of 2.3, controlling the drawing temperature at 85°C, and controlling the setting temperature at 125°C; S5, post-treatment: immersing the spun yarn bundle in a softening finishing solution, padding once and squeezing to a liquor pickup rate of more than 70%, and standing in an 85°C environment for 50 min. The softening finishing solution includes amino silicone oil, sodium dodecyl sulfate, and isopropanol; Immersing the spun yarn bundle after softening finishing in an antibacterial finishing solution, where the antibacterial finishing solution includes isopropanol and chitosan. After padding once, standing in a nitrogen environment at 65°C. After standing for 5 h, cleaning and drying the spun yarn bundle with absolute ethanol to obtain the superfine denier polyester filament.

[0035] Example 5, a preparation method of superfine denier polyester filament, comprising the following process steps: S1, crystallization and drying: adding polyester fiber chips into a drying system for crystallization and drying, setting the drying temperature at 145°C, the air pressure during drying at 0.08 MPa, the crystallization and drying time at 3 h, and the water content of the polyester chips after crystallization and drying at 0.0025%; S2. Melt spinning: The crystallized and dried polyester fiber chips are conveyed to a screw extruder for extrusion and melting. During the melting and extrusion process, the polyester fiber chips enter the spinning box, where the temperature of the spinning box body is higher than the melting extrusion temperature, and the melting extrusion temperature is 285°C. The spinning box body includes a first spinning area and a second spinning area, where the temperature of the box body in the first spinning area is higher than that in the second spinning area. The temperature of the box body in the first spinning area is 295°C, and the temperature of the box body in the second spinning area is 290°C. S3. Cooling and forming: The spun filaments are cooled by blowing air. The blowing air cooling method uses annular blowing. The air pressure of the annular blowing is 22 MPa, the blowing temperature is 22°C, the humidity of the blowing air is controlled at 70%, and the direction of the annular blowing is parallel to the moving direction of the spun filaments. S4. Drawing and setting: The cooled spun filaments are drawn and set. The draw ratio is 2.3, the drawing temperature is controlled at 85°C, and the setting temperature is controlled at 125°C. S5. Post-finishing: The spun filament bundle is immersed in a softening finishing solution, padded once and rolled to a liquid pickup rate of more than 70%, and left standing in an 85°C environment for 50 min. The softening finishing solution includes amino silicone oil, sodium dodecyl sulfate, and isopropanol. The spun filament bundle is cleaned and dried with absolute ethanol to obtain the ultrafine denier polyester filament.

[0036] Comparative example Comparative example 1 The difference between Comparative example 1 and Example 3 is that the blowing air cooling method in Comparative example 1 uses annular blowing.

[0037] Comparative example 2 The difference between Comparative example 2 and Example 3 is that the crystallization and drying temperature in Comparative example 2 is 170°C, the drying time is 20 min, and the water content after crystallization and drying is 0.05%.

[0038] Comparative example 3 The difference between Comparative example 3 and Example 3 is that the blowing air cooling method in Comparative example 3 uses annular blowing, the crystallization and drying temperature is 170°C, the drying time is 20 min, the water content after crystallization and drying is 0.05%, and post-finishing is not carried out. After the spun filament bundle is drawn and set, it is cooled and dried to obtain the ultrafine denier polyester filament.

[0039] Performance detection test 1.1 Tensile strength Samples of the ultrafine denier polyester filaments obtained from Examples 1 - 5 and Comparative examples 1 - 3 with a length of 1 m are taken, and their mass is weighed on an electronic balance to calculate the linear density. Samples of 50 mm are clamped in the upper and lower holders of a tensile tester, and stretched according to the set linear density and stretching speed until the sample filaments break. The electronic single yarn strength tester automatically prints out the tensile strength. The results are shown in Table 1. 1.2 Antibacterial property - Bacteriostatic rate The antibacterial property test was carried out with reference to GB / T 20944.3 - 2008 Textiles - Evaluation of antibacterial properties - Part 3: Oscillation method. The superfine denier polyester filaments prepared in Examples 1 - 5 and Comparative Examples 1 - 3 were made into superfine denier polyester fabrics and tested according to the above - mentioned test method. Among them, the bacteriostatic rates of Example 5 and Comparative Example 3 were relatively low and almost had no antibacterial effect. The remaining results are shown in Table 1.

[0040] Table 1

[0041] Combining Examples 1 - 5 and Comparative Examples 1 - 3 and referring to Table 1, it can be seen that the preparation process of the superfine denier polyester filaments of the present application can significantly improve the breaking strength of the superfine denier polyester filaments, so that the superfine denier polyester filaments can minimize the occurrence of broken filaments during the production and processing process, thereby improving the production efficiency; at the same time, the superfine denier polyester filaments after post - finishing also have a good bacteriostatic rate.

[0042] In addition, we found that the post - finishing process of the present application can further improve the breaking strength of the superfine denier polyester filaments. This may be because during the post - finishing process, a certain amount of quaternary ammonium salts are generated on the surface of the superfine denier polyester spinning bundle. While endowing the superfine denier polyester spinning bundle with certain antibacterial properties, it can also form a certain network structure on the surface of the superfine denier polyester spinning bundle, which can also improve the breaking strength and elongation rate of the superfine denier polyester spinning bundle to a certain extent.

[0043] This specific embodiment is only an interpretation of the present application and is not a limitation to the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing ultra-fine denier polyester filament, characterized in that: The process steps include: S1, crystallization drying, adding the polyester fiber chips into the drying system for crystallization drying, the drying temperature is not higher than 160°C, and the moisture content of the polyester chips after crystallization drying is not higher than 0.005%; S2, melt spinning, conveying the crystallized and dried polyester fiber slices to a screw extruder for extrusion melting, wherein the extrusion temperature is not higher than 295°C; S3, cooling and forming, blowing cooling is performed on the spinning, wherein the blowing cooling method adopts an annular blowing method; S4, stretching and shaping, stretching and shaping the spun yarn after cooling; S5, post-finishing, after which the ultra-fine denier polyester filaments are obtained.

2. The method for preparing ultra-fine denier polyester filament according to claim 1, characterized in that: The step S5 includes performing softening and antibacterial finishing on the spun yarn, which is composed of the following process steps: The spinning bundle is immersed in a softening finishing liquid, and the spun bundle is immersed and rolled until the liquid carrying rate is more than 70%, and then allowed to stand at 70-90°C for 40-60 minutes, wherein the softening finishing liquid includes amino silicone oil, sodium lauryl sulfate, and isopropyl alcohol; The spun yarn bundle after softening is immersed in the antibacterial finishing liquid, and after dipping and rolling, it is placed in a nitrogen environment at 60-70°C for 4-6 hours, and then the spun yarn bundle is cleaned and dried with anhydrous ethanol; The antibacterial finishing liquid includes isopropyl alcohol, epoxypropyl dodecyl dimethyl ammonium chloride and chitosan.

3. The method for preparing ultra-fine denier polyester filament according to claim 1, characterized in that: In step S1, the drying temperature is set to 140-155° C., the wind pressure during drying is 0.03-0.10 MPa, and the crystallization drying time is 2-5 hours.

4. The method for preparing ultra-fine denier polyester filament according to claim 1, characterized in that: In the step S2, the polyester fiber slices enter the spinning box during the melt extrusion process, wherein the spinning box body temperature is higher than the melt extrusion temperature, the box body temperature is controlled to be 290-300°C, and the melt extrusion temperature is 275-293°C.

5. The method for preparing ultra-fine denier polyester filament according to claim 4, characterized in that: The spinning box body comprises a first spinning zone and a second spinning zone, wherein the box body temperature of the first spinning zone is higher than the box body temperature of the second spinning zone, wherein the box body temperature of the second spinning zone is 290-295°C.

6. The method for preparing ultra-fine denier polyester filament according to claim 1, characterized in that: In the step S3, the wind pressure of the annular blowing is 20-25 MPa, the blowing temperature is 20-25° C., the blowing humidity is controlled to be 60-75%, and the direction of the annular blowing is parallel to the spinning movement direction.

7. The method for preparing ultra-fine denier polyester filament according to claim 1, characterized in that: In step S4, the drawing ratio is 2-2.5, the drawing temperature is controlled at 80-90°C, and the setting temperature is controlled at 120-130°C.

8. An ultra-fine denier polyester filament prepared by the method for preparing ultra-fine denier polyester filament according to any one of claims 1 to 7.

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