Polylactic acid fiber with round wave surface special-shaped section and spinneret plate of polylactic acid fiber

Abstract

The invention provides a polylactic acid fiber with a round wave surface special-shaped section and a spinneret plate thereof, and relates to the technical field of polylactic acid fiber spinning. The polylactic acid fiber with the round wave surface special-shaped section comprises a fiber body, and the spinneret plate of the polylactic acid fiber with the round wave surface special-shaped section comprises a first cooling air supply device, a second cooling air supply device, a first plate body, a second plate body, a third plate body, a fourth plate body and a fifth plate body. According to the invention, the softness, bulkiness and wet permeability of the fiber are improved through the multiple groups of round wave bodies, and the ratio of the radius of the round wave bodies to the radius of the central body is restrained, so that the overall shape change of the cross section is not large during the production of drawn yarns, and the central body can still keep higher strength after being drawn; and wrapping type air blowing cooling is performed on the spun filaments, so that the cooling strength uniformity of the filament bundles is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of polylactic acid fiber spinning, in particular to a polylactic acid fiber with a round wave surface and a special-shaped cross-section and a spinneret thereof. Background Art

[0002] With the rapid development of the chemical fiber industry, polyester fiber is more and more widely used in clothing chemical fiber products. my country's polyester consumption has reached 60 million tons. The greenhouse gas emitted by polyester throughout its life cycle has a negative impact on the earth's climate change. In addition, polyester waste cannot be degraded, polluting water sources and land resources, which has become a threat to human survival. The use of degradable bio-based fiber polylactic acid to replace polyester is becoming a trend; in addition, most of the existing polylactic acid fibers have a circular cross-sectional shape. The textiles made of fibers with a circular cross-sectional shape have the problems of poor fluffiness, insufficient softness, and poor moisture conductivity. For this reason, there are also technical proposals for a variety of special-shaped cross-sectional polylactic acid fibers such as M-shaped, trilobal and quadrilobal to improve the above circular cross-sectional shape. The shortcomings of the surface polylactic acid fiber, but when the polylactic acid fiber with the improved cross-section is used to produce ultrafine fiber drawn yarn, the cross-sectional shape is greatly deformed after stretching, and it is difficult to maintain the original cross-sectional shape, and the central part is very fragile after stretching, and it is easy to break the yarn during processing. In addition, in the existing melt spinning devices, ring blowing or side blowing is generally used to blow and cool the primary yarn ejected from the spinneret, and there is a problem of uneven cooling intensity, which is mainly manifested in that the cooling intensity near the air outlet is much higher than that far away from the air outlet, resulting in uneven temperature in the same cross-section, and there is a large difference between the windward side and the leeward side, which in turn affects the quality of the finished yarn bundle. Therefore, it is necessary to develop a polylactic acid fiber with a circular wave surface special cross-section and a spinneret thereof, in order to solve the above problems. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a polylactic acid fiber with a circular wave-shaped cross-section and a spinneret thereof, which solves the problems of the prior art polylactic acid fiber having large cross-sectional deformation after stretching, difficulty in maintaining the original cross-sectional shape, and very brittle central portion after stretching, as well as the problem of uneven cooling intensity in the prior fiber spinning.

[0004] (II) Technical solution To achieve the above purpose, the present invention is implemented by the following technical scheme: a polylactic acid fiber with a circular wave surface profile cross-section, comprising a fiber body, the fiber body consisting of a central body and a plurality of groups of circular wave bodies, the central body cross-section is circular, the circular wave body cross-section is semicircular, and the plurality of groups of circular wave bodies are arranged on the circumferential outer wall of the central body in a circularly evenly divided shape with the central body axis as the center, and the fiber body production method comprises the following steps: S1, using polylactic acid as a raw material, slicing the polylactic acid and drying it; S2, the dried polylactic acid slices are melted by a screw extruder and then fed into a spinning manifold through a metering pump, and then the filaments are ejected through a spinneret, and finally cooled, oiled, and wound to obtain polylactic acid primary filaments with round wave-shaped cross-sections; S3, the polylactic acid primary filaments with round wave surface and special-shaped cross-section are subjected to the steps of stretching, shaping, curling, drying and winding to obtain polylactic acid fibers with round wave surface and special-shaped cross-section.

[0005] Preferably, the semicircular radius of the circular wave body is one fifth of the circular radius of the central body.

[0006] A spinneret for polylactic acid fibers with a circular wave surface profiled cross section, used for producing the polylactic acid fibers with the circular wave surface profiled cross section, the spinneret comprising a first cooling air providing device, a second cooling air providing device, a first plate body, a second plate body, a third plate body, a fourth plate body and a fifth plate body, wherein the first plate body, the second plate body, the third plate body, the fourth plate body and the fifth plate body are sequentially arranged from top to bottom, the outer wall of the first plate body is provided with a plurality of groups of fixing ears, the inner walls of the plurality of groups of the fixing ears are all provided with bolt through holes which penetrate vertically, and the first plate body The upper wall is provided with a connecting seat, and a liquid conducting cavity which is connected with the upper wall of the connecting seat is provided inside the connecting seat, and a liquid conducting ring groove is provided on the inner lower wall of the liquid conducting cavity, and a plurality of groups of liquid conducting holes are provided on the inner lower wall of the liquid conducting ring groove, and the plurality of groups of liquid conducting holes are equally distributed in a circle with the axis of the first plate body as the center, and the lower ends of the plurality of groups of liquid conducting holes are connected with the lower wall of the first plate body, and the inner wall of the second plate body is fixedly connected with a plurality of groups of spinnerets in a vertically through-through shape, and the plurality of groups of spinnerets are respectively opposite to the plurality of groups of liquid conducting holes horizontally up and down, and the inner wall of the spinneret is provided with spinneret holes which are vertically through-through , a heat insulation structure for heat insulation is arranged between the third plate body and the second plate body, a second air guide ring groove is arranged on the upper wall of the fifth plate body, and a plurality of second blowing pipes are fixedly connected to the lower inner wall of the second air guide ring groove, a first air guide ring groove is arranged on the upper wall of the fourth plate body, and a plurality of first blowing pipes are fixedly connected to the lower inner wall of the first air guide ring groove, and the lower ends of the plurality of first blowing pipes all pass through the inner wall of the fourth plate body and extend into the interior of the plurality of second blowing pipes respectively, a plurality of insulation pipes are fixedly connected to the inner wall of the third plate body, and the lower ends of the plurality of insulation pipes all pass through The plurality of first blowing pipes are respectively inserted into the plurality of first blowing pipes through the inner wall of the third plate body, the lower ends of the second blowing pipe, the first blowing pipe and the insulation pipe are flush with the lower wall of the fifth plate body, the plurality of insulation pipes are respectively opposite to the plurality of spinnerets, the insulation pipe inner wall is provided with a wire outlet hole which passes through from top to bottom, the temperature of the cooling air provided by the first cooling air providing device is between the cooling air provided by the second cooling air providing device and the spinning temperature of the spinneret hole, the wind speed of the cooling air provided by the first cooling air providing device is lower than the wind speed of the cooling air provided by the second cooling air providing device.

[0007] Preferably, the thermal insulation structure is a thermal insulation pad, which is fixedly connected between the third plate body and the second plate body, and the inner wall of the thermal insulation pad is provided with multiple groups of through holes, which are respectively located between multiple groups of spinnerets and multiple groups of thermal insulation tubes.

[0008] Preferably, the first plate body, the second plate body, the third plate body, the fourth plate body and the fifth plate body are positioned by four groups of positioning pins.

[0009] Preferably, the upper size of the spinneret hole is larger than the lower size, and the spinneret hole consists of a central hole which is circular when projected from above and multiple groups of semicircular holes which are semicircular when projected from above, and the multiple groups of semicircular holes are arranged on the outside of the central hole in a circle with the center of the central hole as equal parts of the circumference.

[0010] Preferably, the inner wall of the first blowing pipe is provided with a first blowing hole which passes through from top to bottom, and the inner wall of the first blowing hole and near the lower end of the first blowing pipe is provided with a first narrowing portion, a first blowing cavity is formed between the inner wall of the first blowing hole and the corresponding outer wall of the insulation tube, and a first pressurized cavity is formed between the inner wall of the first narrowing portion and the corresponding outer wall of the insulation tube.

[0011] Preferably, the inner wall of the second blowing pipe is provided with a second blowing hole which passes through from top to bottom, and the inner wall of the second blowing hole and near the lower end of the second blowing pipe is provided with a second narrowing portion, a second blowing cavity is formed between the inner wall of the second blowing hole and the corresponding outer wall of the first blowing pipe, and a second pressurized cavity is formed between the inner wall of the second narrowing portion and the corresponding outer wall of the first blowing pipe.

[0012] Preferably, the fourth plate body is provided with a plurality of groups of first joints on the circumferential outer wall, and the ends of the plurality of groups of first joints away from the fourth plate body are respectively connected to the first cooling air providing device through a plurality of groups of pipes, and the fourth plate body is provided with a plurality of groups of first straight air guide grooves on the upper wall, and the extension lines of one end of the plurality of first straight air guide grooves in the length direction intersect with the center line of the fourth plate body, and the end of the first straight air guide groove close to the circumferential outer wall of the fourth plate body is connected with the first joint through the first air inlet hole, and the end of the first straight air guide groove away from the first air inlet hole is connected with the first air guide ring groove.

[0013] Preferably, the fifth plate body is provided with a plurality of groups of second joints on the circumferential outer wall, and the ends of the plurality of groups of second joints away from the fifth plate body are respectively connected to the second cooling air providing device through a plurality of groups of pipes, and the fifth plate body is provided with a plurality of groups of second straight air guide grooves on the upper wall, and the extension lines of one end of the plurality of second straight air guide grooves in the length direction intersect with the center line of the fifth plate body, and the end of the second straight air guide groove close to the circumferential outer wall of the fifth plate body is connected with the second joint through the second air inlet hole, and the end of the second straight air guide groove away from the second air inlet hole is connected with the second air guide ring groove.

[0014] (III) Beneficial effects The present invention provides a polylactic acid fiber with a circular wave surface and a special-shaped cross-section and a spinneret thereof, which has the following beneficial effects: 1. Compared with the prior art, the polylactic acid fiber with a circular wave surface profiled cross-section has a plurality of groups of semicircular circular wave bodies arranged on the outer wall of the central body with a circular cross-section, so that the fiber cross-section forms a circular wave surface profiled cross-section. The softness, fluffiness and moisture conductivity of the fiber are improved by the plurality of groups of circular wave bodies. By constraining the ratio of the radius of the circular wave body to the radius of the central body, the overall shape of the cross-section does not change much during the production of stretched yarns and the central body can still maintain a high strength after stretching, so as to meet the production of ultrafine fiber stretched yarns.

[0015] 2. Compared with the prior art, the polylactic acid fiber with a circular wave surface profiled cross-section and its spinneret, while ejecting the primary filaments through the spinneret holes, the cooling air provided by the first cooling air providing device and the second cooling air providing device are blown out along the outlet direction of the primary filaments through the first blowing chamber and the second blowing chamber respectively, forming two concentric annular cooling air curtains, which perform wrap-type blowing cooling on the primary filaments. The different temperatures and wind speeds of the two air curtains can realize gradual cooling of the primary filaments, effectively improve the uniformity of the cooling intensity of the filament bundles, and improve the quality of the finished filament bundles. At the same time, it also completely solves the entanglement problem of the filament bundles caused by the traditional blowing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a partial cross-sectional schematic diagram of the connection structure of the first plate body, the second plate body, the third plate body, the fourth plate body and the fifth plate body of the present invention; Figure 3 For the present invention Figure 2 A partial enlarged view of the middle A; Figure 4 For the present invention Figure 2 A partial enlarged view of point B in the middle; Figure 5 For the present invention Figure 2 A partial enlarged view of point C in the middle; Figure 6 It is a schematic diagram of the top structure of the spinneret and the spinneret hole of the present invention; Figure 7 It is a partial cross-sectional view of the internal structure of the first blowing pipe of the present invention; Figure 8 It is a partial cross-sectional view of the internal structure of the second blowing pipe of the present invention; Fig. 9 This is a schematic diagram of the top structure of the fourth plate body of the present invention; Fig.10 This is a schematic diagram of the top structure of the fifth plate body of the present invention; Fig.11 It is a schematic diagram of the local structure of the fiber body of the present invention.

[0017] Among them, 1, the first plate; 101, the fixing ear; 2, the second plate; 3, the third plate; 4, the fourth plate; 5, the fifth plate; 6, the connecting seat; 7, the liquid guide cavity; 8, the liquid guide ring groove; 9, the liquid guide hole; 10, the positioning pin; 11, the heat insulation pad; 12, the first joint; 13, the second joint; 14, the first air guide straight groove; 15, the first air inlet hole; 16, the second air guide straight groove; 17, the second air inlet hole; 18, the spinneret; 1 9. Spinneret hole; 1901. Center hole; 1902. Semicircular hole; 20. Insulation tube; 2001. Wire outlet hole; 21. Fiber body; 2101. Center body; 2102. Circular wave body; 22. First blowing tube; 2201. First blowing hole; 2202. First narrowing part; 23. Second blowing tube; 2301. Second blowing hole; 2302. Second narrowing part; 24. First air guide ring groove; 25. Second air guide ring groove. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the 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.

[0019] Example: like Fig.11 As shown, the embodiment of the present invention provides a polylactic acid fiber with a circular wave surface profile cross-section, including a fiber body 21, the fiber body 21 is composed of a central body 2101 and a plurality of groups of circular wave bodies 2102, the cross-section of the central body 2101 is circular, the cross-section of the circular wave bodies 2102 is semicircular, and the plurality of groups of circular wave bodies 2102 are all arranged on the outer wall of the central body 2101 in a circular shape with the axis of the central body 2101 as the center, and the production method of the fiber body 21 comprises the following steps: S1, using polylactic acid as a raw material, slicing the polylactic acid and drying it; S2, the dried polylactic acid slices are melted by a screw extruder and then fed into a spinning manifold through a metering pump, and then the filaments are ejected through a spinneret, and finally cooled, oiled, and wound to obtain polylactic acid primary filaments with round wave-shaped cross-sections; S3, the polylactic acid primary filaments with round wave surface and special-shaped cross-section are subjected to the steps of stretching, shaping, curling, drying and winding to obtain polylactic acid fibers with round wave surface and special-shaped cross-section.

[0020] The semicircular radius of the circular wave body 2102 is one fifth of the circular radius of the central body 2101. Arranging multiple groups of circular wave bodies 2102 on the outer wall of the central body 2101 can effectively improve the fluffiness and softness of the fiber body 21. By constraining the ratio of the radius of the circular wave body 2102 to the radius of the central body 2101, the overall shape of the cross-section does not change much during the production of stretched yarns and the central body 2101 can still maintain a relatively high strength after stretching, thereby meeting the production of ultrafine fiber stretched yarns.

[0021] like Figures 1 to 10 As shown, the embodiment of the present invention also provides a spinneret for polylactic acid fibers with a circular wave surface profiled cross-section, which is used to produce the polylactic acid fibers with the circular wave surface profiled cross-section. The spinneret includes a first cooling air providing device, a second cooling air providing device, a first plate body 1, a second plate body 2, a third plate body 3, a fourth plate body 4 and a fifth plate body 5. The first plate body 1, the second plate body 2, the third plate body 3, the fourth plate body 4 and the fifth plate body 5 are sequentially distributed from top to bottom. The outer wall of the first plate body 1 is provided with multiple groups of fixing ears 101, and the inner walls of the multiple groups of fixing ears 101 are all provided with bolt through holes that penetrate up and down. The first plate body 1, the second plate body 2, the third plate body 3, the fourth plate body 4 and the fifth plate body 5 are positioned by four groups of positioning pins 10. After positioning by the four groups of positioning pins 10, assembly can ensure that the parts on each plate body can be aligned up and down without misalignment. The spinneret is fixedly connected to the spinning box by inserting bolts into the bolt through holes of the fixing ears 101; In order to allow the polylactic acid melt to smoothly enter the spinneret, a connecting seat 6 is provided on the upper wall of the first plate body 1, and a liquid guide cavity 7 which is connected to the upper wall of the connecting seat 6 is provided inside the connecting seat 6, and a liquid guide ring groove 8 is provided on the inner lower wall of the liquid guide cavity 7, and a plurality of groups of liquid guide holes 9 are provided on the inner lower wall of the liquid guide ring groove 8, and the plurality of groups of liquid guide holes 9 are equally distributed in a circle with the axis of the first plate body 1 as the center, and the lower ends of the plurality of groups of liquid guide holes 9 are connected to the lower wall of the first plate body 1, and the inner wall of the second plate body 2 is fixedly connected with a plurality of groups of spinnerets 18 in an up-and-down through-shape, and the plurality of groups of spinnerets 18 are respectively opposite to the plurality of groups of liquid guide holes 9 horizontally up and down, and the inner wall of the spinneret 18 is provided with spinneret holes 19 which are connected up and down, and the polylactic acid melt respectively enters a group of spinneret holes 19 through the plurality of groups of liquid guide holes 9, and a diversion effect is formed by the plurality of groups of liquid guide holes 9, and when the pressure of the upstream metering pump is consistent, the melt fraction diverted through the liquid guide cavity 7 and the liquid guide hole 9 is kept consistent; In order to prevent the first cooling air providing device from lowering the temperature of the second plate body 2 when supplying cooling air to the fourth plate body 4, a heat insulation structure for heat insulation is provided between the third plate body 3 and the second plate body 2, and the heat insulation structure is a heat insulation pad 11, and the heat insulation pad 11 is fixedly connected between the third plate body 3 and the second plate body 2. The inner wall of the heat insulation pad 11 is provided with a plurality of groups of through holes, and the plurality of groups of through holes are respectively located between the plurality of groups of spinnerets 18 and the plurality of groups of insulation tubes 20. The third plate body 3 and the second plate body 2 are separated by the heat insulation pad 11, so as to prevent the internal temperature of the second plate body 2 from being affected by the temperature of the third plate body 3 and other plates below the third plate body 3, and to maintain the internal melt temperature of the spinneret 18 to enable smooth spinning; In order to form a polylactic acid fiber with a circular wave surface profiled cross section, the upper size of the spinneret hole 19 is larger than the lower size, and the spinneret hole 19 is composed of a central hole 1901 which is circular in top view projection and multiple groups of semicircular holes 1902 which are semicircular in top view projection. The multiple groups of semicircular holes 1902 are arranged on the outside of the central hole 1901 in a circle-shaped shape with the center of the central hole 1901 being equally divided into circles. The spinneret hole 19 formed by the central hole 1901 and the multiple groups of semicircular holes 1902 allows the melt to form a circular wave surface profiled cross section after being ejected from the spinneret hole 19. The upper size of the spinneret hole 19 is larger than the lower size, so that the pressure of the melt increases when passing through the spinneret hole 19, and the upstream pump pressure remains unchanged, which effectively improves the spinning quality; In order to form the first cooling air curtain outside the spun silk, a first air guide ring groove 24 is provided on the upper wall of the fourth plate body 4, and a plurality of first blowing pipes 22 are fixedly connected to the inner lower wall of the first air guide ring groove 24, and the lower ends of the plurality of first blowing pipes 22 all penetrate the inner wall of the fourth plate body 4 and extend into the interior of the plurality of second blowing pipes 23 respectively, and a first blowing hole 2201 which runs through the inner wall of the first blowing hole 2201 is provided in an upper and lower manner, and a first narrowing portion 2202 is provided on the inner wall of the first blowing hole 2201 and near the lower end of the first blowing pipe 22, a first blowing cavity is formed between the inner wall of the first blowing hole 2201 and the corresponding outer wall of the insulation tube 20, and a first pressurized cavity is formed between the inner wall of the first narrowing portion 2202 and the corresponding outer wall of the insulation tube 20, and a plurality of first joints 12 are provided on the circumferential outer wall of the fourth plate body 4, and the ends of the plurality of first joints 12 away from the fourth plate body 4 are respectively connected to the first cooling air providing device through a plurality of pipes. The fourth plate body 4 is connected, and a plurality of groups of first air-guiding straight grooves 14 are arranged on the upper wall. The extension lines of one end of the plurality of first air-guiding straight grooves 14 in the length direction intersect with the center line of the fourth plate body 4. One end of the first air-guiding straight groove 14 close to the circumferential outer wall of the fourth plate body 4 is connected with the first joint 12 through the first air inlet hole 15. One end of the first air-guiding straight groove 14 away from the first air inlet hole 15 is connected with the first air-guiding annular groove 24. The cooling air supplied by the first cooling air providing device enters the first air-guiding annular groove 24 through the first joint 12, the first air inlet hole 15 and the first air-guiding straight groove 14. The plurality of cooling airs delivered by the plurality of first joints 12 converge inside the first air-guiding annular groove 24. After convergence, they are blown toward the spinning direction of the primary silk through the first blowing chamber and are pressurized through the first pressurizing chamber. The pressurized cooling air forms an annular cooling air curtain around the primary silk to cool the primary silk. The cooling intensity is consistent in the same cross section of the silk bundle. In order to form a second cooling air curtain outside the spun silk, a second air guide ring groove 25 is provided on the upper wall of the fifth plate body 5, and a plurality of second blowing pipes 23 are fixedly connected to the inner lower wall of the second air guide ring groove 25. The inner wall of the second blowing pipe 23 is provided with a second blowing hole 2301 which runs through from top to bottom, and a second narrowing portion 2302 is provided on the inner wall of the second blowing hole 2301 and near the lower end of the second blowing pipe 23. A second blowing cavity is formed between the inner wall of the second blowing hole 2301 and the corresponding outer wall of the first blowing pipe 22, and a second pressurized cavity is formed between the inner wall of the second narrowing portion 2302 and the corresponding outer wall of the first blowing pipe 22. A plurality of second joints 13 are provided on the circumferential outer wall of the fifth plate body 5, and the ends of the plurality of second joints 13 away from the fifth plate body 5 are respectively connected to the second cooling air providing device through a plurality of pipes. A second air-guiding straight groove 16 is formed, and the extension lines of one end of the plurality of second air-guiding straight grooves 16 in the length direction intersect with the center line of the fifth plate body 5. One end of the second air-guiding straight groove 16 close to the circumferential outer wall of the fifth plate body 5 is connected with the second joint 13 through the second air inlet hole 17, and one end of the second air-guiding straight groove 16 away from the second air inlet hole 17 is connected with the second air-guiding annular groove 25. The cooling air supplied by the second cooling air providing device enters the second air-guiding annular groove 25 through the second joint 13, the second air inlet hole 17, and the second air-guiding straight groove 16. The plurality of cooling airs fed by the plurality of second joints 13 converge inside the second air-guiding annular groove 25, and after convergence, they are blown toward the spinning direction of the primary silk through the second blowing chamber, and are pressurized through the second pressurizing chamber. The pressurized cooling air regenerates a cooling air curtain around the first cooling air curtain formed in the first pressurizing chamber, thereby effectively improving the cooling effect. In order to gradually cool down the nascent filaments ejected from the spinneret 19, the temperature of the cooling air provided by the first cooling air providing device is between the cooling air provided by the second cooling air providing device and the spinning temperature of the spinneret 19, the wind speed of the cooling air provided by the first cooling air providing device is lower than the wind speed of the cooling air provided by the second cooling air providing device, the temperature of a cooling air close to the nascent filament bundle is between the cooling air provided by the second cooling air providing device and the spinning temperature of the spinneret 19, but its wind speed is relatively low, and the nascent filaments are only cooled down when they are ejected from the spinneret 19, and then further cooled down through the peripheral cooling air curtain. This setting can avoid strong cold air blowing directly on the nascent filaments to cause local stress concentration, and effectively improve the cooling quality of the filament bundle; In order to prevent the cooling wind from affecting the temperature of the spinneret 18, multiple groups of heat-insulating tubes 20 are fixedly connected to the inner wall of the third plate body 3. The lower ends of the multiple groups of heat-insulating tubes 20 all penetrate the inner wall of the third plate body 3 and extend into the multiple groups of first blowing tubes 22 respectively. The lower ends of the second blowing tubes 23, the first blowing tubes 22 and the heat-insulating tubes 20 are all flush with the lower wall of the fifth plate body 5. The multiple groups of heat-insulating tubes 20 are respectively opposite to the multiple groups of spinnerets 18 up and down. The inner wall of the heat-insulating tube 20 is provided with a wire outlet hole 2001 which is through from top to bottom. After the filament bundle is ejected from the spinneret hole 19, it moves downward along the wire outlet hole 2001. The cooling wind blows downward along the outer wall of the heat-insulating tube 20, which will not reduce the temperature of the spinneret 18. Working principle: After positioning through four groups of positioning pins 10 and then assembling, it can ensure that the parts on each plate can be aligned up and down without misalignment. The spinneret is fixedly connected to the spinning box by inserting bolts into the bolt holes of the fixing ears 101. The polylactic acid melt enters a group of spinneret holes 19 through multiple groups of liquid guide holes 9 respectively, and a diversion effect is formed through multiple groups of liquid guide holes 9. When the pressure of the upstream metering pump is consistent, the melt components diverted through the liquid guide cavity 7 and the liquid guide holes 9 remain consistent. The third plate body 3 and the second plate body 2 are separated by the thermal insulation pad 11 to prevent the internal temperature of the second plate body 2 from being affected by the temperature of the third plate body 3 and other plates below the third plate body 3. , keeping the melt temperature inside the spinneret 18 to enable smooth spinning, the spinneret hole 19 formed by the central hole 1901 and the multiple groups of semicircular holes 1902 allows the melt to form a circular wave surface after being ejected from the spinneret hole 19. The upper opening size of the spinneret hole 19 is larger than the lower opening size, so that the pressure of the melt increases when passing through the spinneret hole 19. Under the condition that the upstream pump pressure remains unchanged, the spinning quality is effectively improved. The cooling air supplied by the first cooling air providing device enters the first air guide ring groove 24 through the first joint 12, the first air inlet hole 15, and the first air guide straight groove 14. The multiple cooling airs sent in by the multiple groups of first joints 12 converge inside the first air guide ring groove 24, and converge The cooling air supplied by the second cooling air providing device enters the second air guide annular groove 25 through the second joint 13, the second air inlet 17, and the second air guide straight groove 16. The multiple cooling airs delivered by the multiple groups of second joints 13 converge inside the second air guide annular groove 25. After convergence, the multiple cooling airs are blown toward the spinning direction of the primary silk through the second blowing chamber and are pressurized by the second pressurizing chamber. The pressurized cooling air forms an annular cooling air curtain at the periphery of the primary silk to cool down the primary silk. The cooling intensity is consistent within the same cross section of the silk bundle. The cooling air supplied by the second cooling air providing device enters the second air guide annular groove 25 through the second joint 13, the second air inlet 17, and the second air guide straight groove 16. The multiple cooling airs delivered by the multiple groups of second joints 13 converge inside the second air guide annular groove 25. After convergence, the multiple cooling airs are blown toward the spinning direction of the primary silk through the second blowing chamber and are pressurized by the second pressurizing chamber. The pressurized cooling air forms an annular cooling air curtain in the first pressurizing chamber. A cooling air curtain is generated outside the first cooling air curtain, which effectively improves the cooling effect. The temperature of the cooling air close to the nascent filament bundle is between the cooling air provided by the second cooling air providing device and the spinning temperature of the spinneret hole 19, but its wind speed is relatively small. The nascent filaments are only cooled when they are ejected from the spinneret hole 19, and are subsequently cooled further through the peripheral cooling air curtain. This arrangement can avoid strong cold air blowing directly on the nascent filaments to cause local stress concentration, thereby effectively improving the cooling quality of the filament bundle. After the filament bundle is ejected from the spinneret hole 19, it moves downward along the filament outlet hole 2001, and the cooling air blows downward along the outer wall of the insulation tube 20, which will not reduce the temperature of the spinneret 18.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A polylactic acid fiber with a circular wave surface and a special-shaped cross-section, characterized in that: The fiber body (21) comprises a fiber body (21), wherein the fiber body (21) comprises a central body (2101) and a plurality of groups of circular wave bodies (2102), wherein the central body (2101) has a circular cross section, and the circular wave bodies (2102) have a semicircular cross section, and the plurality of groups of circular wave bodies (2102) are arranged on the outer wall of the central body (2101) in a circular shape with the axis of the central body (2101) as the center. The production method of the fiber body (21) comprises the following steps: S1, using polylactic acid as a raw material, slicing the polylactic acid and drying it; S2, the dried polylactic acid slices are melted by a screw extruder and then fed into a spinning manifold through a metering pump, and then the filaments are ejected through a spinneret, and finally cooled, oiled, and wound to obtain polylactic acid primary filaments with round wave-shaped cross-sections; S3, the polylactic acid primary filaments with round wave surface and special-shaped cross-section are subjected to the steps of stretching, shaping, curling, drying and winding to obtain polylactic acid fibers with round wave surface and special-shaped cross-section.

2. The polylactic acid fiber with a circular wave surface profile cross section according to claim 1, characterized in that: The semicircular radius of the circular wave body (2102) is one fifth of the circular radius of the central body (2101).

3. A spinneret for polylactic acid fibers with round wave profiled cross-section, used for producing polylactic acid fibers with round wave profiled cross-section as claimed in any one of claims 1 to 2, characterized in that: The spinneret comprises a first cooling air providing device, a second cooling air providing device, a first plate body (1), a second plate body (2), a third plate body (3), a fourth plate body (4) and a fifth plate body (5), wherein the first plate body (1), the second plate body (2), the third plate body (3), the fourth plate body (4) and the fifth plate body (5) are arranged in sequence from top to bottom, a plurality of groups of fixing ears (101) are arranged on the outer wall of the first plate body (1), and bolt holes penetrating from top to bottom are arranged on the inner walls of the plurality of groups of fixing ears (101), a connecting seat (6) is arranged on the upper wall of the first plate body (1), and a bolt hole penetrating from the upper wall of the connecting seat (6) is arranged inside the connecting seat (6). The liquid conducting cavity (7) is connected to the second plate body (2), the inner lower wall of the liquid conducting cavity (7) is provided with a liquid conducting annular groove (8), the inner lower wall of the liquid conducting annular groove (8) is provided with a plurality of groups of liquid conducting holes (9), the plurality of groups of liquid conducting holes (9) are equally distributed in a circle with the axis of the first plate body (1) as the center, the lower ends of the plurality of groups of liquid conducting holes (9) are connected to the lower wall of the first plate body (1), the inner wall of the second plate body (2) is connected to a plurality of groups of spinnerets (18) in a vertically connected state, the plurality of groups of spinnerets (18) are respectively opposite to the plurality of groups of liquid conducting holes (9) horizontally and vertically, the inner wall of the spinneret (18) is provided with spinneret holes (19) which are connected vertically, and the third plate body (3) and the second plate body (2) are connected to each other. A heat insulation structure for heat insulation is provided between the upper wall of the fifth plate body (5), a second air guide ring groove (25) is provided on the upper wall of the second air guide ring groove (25), and a plurality of second blowing pipes (23) are fixedly connected to the inner lower wall of the second air guide ring groove (25); a first air guide ring groove (24) is provided on the upper wall of the fourth plate body (4), and a plurality of first blowing pipes (22) are fixedly connected to the inner lower wall of the first air guide ring groove (24), and the lower ends of the plurality of first blowing pipes (22) all pass through the inner wall of the fourth plate body (4) and extend into the interior of the plurality of second blowing pipes (23) respectively; a plurality of heat insulation pipes (20) are fixedly connected to the inner wall of the third plate body (3), and the lower ends of the plurality of heat insulation pipes (20) all pass through the inner wall of the third plate body (3); The inner wall of the plate body (3) extends into the interior of multiple groups of first blowing pipes (22), the lower ends of the second blowing pipe (23), the first blowing pipe (22) and the lower ends of the insulation pipe (20) are all flush with the lower wall of the fifth plate body (5), the multiple groups of insulation pipes (20) are respectively opposite to the multiple groups of spinnerets (18) in upper and lower positions, the inner wall of the insulation pipe (20) is provided with a wire outlet hole (2001) which passes through from top to bottom, the temperature of the cooling air provided by the first cooling air providing device is between the cooling air provided by the second cooling air providing device and the spinning temperature of the spinneret hole (19), and the wind speed of the cooling air provided by the first cooling air providing device is lower than the wind speed of the cooling air provided by the second cooling air providing device.

4. The spinneret of the polylactic acid fiber with a circular wave surface and a special-shaped cross section according to claim 3, characterized in that: The thermal insulation structure is a thermal insulation pad (11), the thermal insulation pad (11) is fixedly connected between the third plate body (3) and the second plate body (2), the inner wall of the thermal insulation pad (11) is provided with a plurality of groups of through holes, and the plurality of groups of through holes are respectively located between the plurality of groups of spinnerets (18) and the plurality of groups of thermal insulation tubes (20).

5. The spinneret of the polylactic acid fiber with round wave surface profile cross section according to claim 4, characterized in that: The first plate body (1), the second plate body (2), the third plate body (3), the fourth plate body (4) and the fifth plate body (5) are positioned by means of four groups of positioning pins (10).

6. The spinneret of polylactic acid fiber with round wave surface profile cross section according to claim 5, characterized in that: The upper opening of the spinneret hole (19) is larger than the lower opening. The spinneret hole (19) is composed of a central hole (1901) which is circular in plan view and a plurality of groups of semicircular holes (1902) which are semicircular in plan view. The plurality of groups of semicircular holes (1902) are arranged outside the central hole (1901) in a circular shape with the center of the central hole (1901) being equally divided.

7. The spinneret of polylactic acid fiber with round wave surface and special cross section according to claim 6, characterized in that: The inner wall of the first blowing tube (22) is provided with a first blowing hole (2201) which passes through from top to bottom, and the inner wall of the first blowing hole (2201) and near the lower end of the first blowing tube (22) is provided with a first narrowing portion (2202), a first blowing cavity is formed between the inner wall of the first blowing hole (2201) and the outer wall of the corresponding insulation tube (20), and a first pressurized cavity is formed between the inner wall of the first narrowing portion (2202) and the outer wall of the corresponding insulation tube (20).

8. The spinneret of polylactic acid fiber with round wave surface and special cross section according to claim 7, characterized in that: The inner wall of the second blowing pipe (23) is provided with a second blowing hole (2301) which passes through from top to bottom, and the inner wall of the second blowing hole (2301) and close to the lower end of the second blowing pipe (23) is provided with a second narrowing portion (2302), a second blowing cavity is formed between the inner wall of the second blowing hole (2301) and the outer wall of the corresponding first blowing pipe (22), and a second pressurized cavity is formed between the inner wall of the second narrowing portion (2302) and the outer wall of the corresponding first blowing pipe (22).

9. The spinneret of polylactic acid fiber with round wave surface and special cross section according to claim 8, characterized in that: The circumferential outer wall of the fourth plate body (4) is provided with a plurality of groups of first joints (12), and the ends of the plurality of groups of first joints (12) away from the fourth plate body (4) are respectively connected to the first cooling air providing device through a plurality of groups of pipes. The upper wall of the fourth plate body (4) is provided with a plurality of groups of first air guide straight grooves (14), and the extension lines of one end of the plurality of groups of first air guide straight grooves (14) in the length direction intersect with the center line of the fourth plate body (4). The end of the first air guide straight groove (14) close to the circumferential outer wall of the fourth plate body (4) is connected to the first joint (12) through the first air inlet hole (15), and the end of the first air guide straight groove (14) away from the first air inlet hole (15) is connected to the first air guide ring groove (24).

10. The spinneret of polylactic acid fiber with round wave surface profile cross section according to claim 9, characterized in that: The fifth plate body (5) is provided with a plurality of groups of second joints (13) on the circumferential outer wall, and the ends of the plurality of groups of second joints (13) away from the fifth plate body (5) are respectively connected to the second cooling air providing device through a plurality of groups of pipes. The fifth plate body (5) is provided with a plurality of groups of second straight air guide grooves (16) on the upper wall, and the extension lines of one end of the plurality of second straight air guide grooves (16) in the length direction intersect with the center line of the fifth plate body (5). The end of the second straight air guide groove (16) close to the circumferential outer wall of the fifth plate body (5) is connected to the second joint (13) through the second air inlet hole (17), and the end of the second straight air guide groove (16) away from the second air inlet hole (17) is connected to the second air guide ring groove (25).

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