A polylactic acid fiber with a circular wave surface and a special-shaped cross-section and its spinneret

Abstract

The present invention provides a polylactic acid fiber with a circular wave-shaped special cross-section and a spinneret thereof, relating to the technical field of polylactic acid fiber spinning. The polylactic acid fiber with a circular wave-shaped special cross-section includes a fiber body. The spinneret of the polylactic acid fiber with a circular wave-shaped special cross-section includes 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. In the present invention, the softness, bulkiness, and moisture conductivity of the fiber are improved by multiple groups of circular wave bodies. By restricting the ratio of the radius of the circular wave body to the radius of the central body, the overall cross-sectional shape changes little during the production of drawn filaments, and the central body can still maintain a high strength after stretching. Through two concentric annular cooling air curtains, the nascent filaments are blown and cooled in a wrapped manner, effectively improving the uniformity of the cooling intensity of the filament bundle.

Description

Technical Field

[0001] The present invention relates to the technical field of polylactic acid fiber spinning, and particularly to a polylactic acid fiber with a circular wave-shaped special cross-section and a spinneret plate therefor. Background Art

[0002] With the rapid development of the chemical fiber industry, in clothing chemical fiber products, the application of polyester fiber is becoming more and more extensive. In China, the polyester consumption reaches 60 million tons. The greenhouse gases emitted during the entire life cycle of polyester have a negative impact on the earth's climate change, and polyester waste cannot be degraded, polluting water sources and land resources. It has become a threat to human survival. Using the degradable biobased 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. Textiles made of such fibers with a circular cross-sectional shape have problems such as poor fluffiness, insufficient softness, and poor moisture conductivity. For this reason, there are also technologies that propose various special cross-section polylactic acid fibers such as the rice-shaped, three-leaf-shaped, and four-leaf-shaped to improve the deficiencies of the above-mentioned circular cross-section polylactic acid fibers. However, when the above-mentioned improved cross-section polylactic acid fibers are used to produce ultra-fine fiber drawn filaments, the cross-sectional shape after stretching deforms greatly, and it is difficult to maintain the original cross-sectional shape. Moreover, the central part is very fragile after stretching and is prone to wire breakage during processing. In addition, in the existing melt spinning devices, ring blowing or side blowing is generally used to blow and cool the nascent filaments ejected from the spinneret plate, and there are problems of uneven cooling intensity, mainly manifested as the cooling intensity near the air outlet is much higher than that far from the air outlet, resulting in uneven temperature within the same cross-section and a large difference between the windward side and the leeward side, thereby affecting the quality of the filament bundle finished product. Therefore, it is necessary to develop a polylactic acid fiber with a circular wave-shaped special cross-section and a spinneret plate therefor in order to solve the above problems. Summary of the Invention

[0003] Technical Problems to be Solved

[0004] In view of the deficiencies of the prior art, the present invention provides a polylactic acid fiber with a circular wave-shaped special cross-section and a spinneret plate therefor, which solves the problems that the cross-sectional shape of the existing polylactic acid fiber deforms greatly after stretching, is difficult to maintain the original cross-sectional shape, and the central part is very fragile after stretching, as well as the problem of uneven cooling intensity existing in the existing fiber spinning.

[0005] Technical Solutions

[0006] To achieve the above object, the present invention is realized through the following technical solutions: A polylactic acid fiber with a circular wave-shaped special cross-section includes a fiber body. The fiber body is composed of a central body and multiple groups of circular wave bodies. The cross-section of the central body is circular, and the cross-section of the circular wave body is semi-circular. Multiple groups of the circular wave bodies are arranged on the circumferential outer wall of the central body in a circumferential equidistant manner with the axis of the central body as the center. The production method of the fiber body includes the following steps:

[0007] S1, using polylactic acid as a raw material, slicing the polylactic acid and drying it;

[0008] 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;

[0009] S3, the polylactic acid primary filaments with round wave surface and special 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 cross-section.

[0010] Preferably, the semicircular radius of the circular wave body is one fifth of the circular radius of the central body.

[0011] 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 connection seat, the connection seat is provided with a liquid guide cavity which is connected with the upper wall of the connection seat, the inner lower wall of the liquid guide cavity is provided with a liquid guide ring groove, the inner lower wall of the liquid guide ring groove is provided with multiple groups of liquid guide holes, the multiple groups of liquid guide holes are equally distributed in a circle with the axis of the first plate body as the center, the lower ends of the multiple groups of liquid guide holes are connected with the lower wall of the first plate body, the inner wall of the second plate body is connected with multiple groups of spinnerets in a vertically connected shape, the multiple groups of spinnerets are respectively opposite to the multiple groups of liquid guide holes, and the inner wall of the spinneret is provided with spinneret holes which are connected up and down. A heat insulating structure for heat insulation is provided between the third plate body and the second plate body, a second air guide ring groove is provided 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 provided 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 inner wall of the third plate body extends into the interior of multiple groups of first blowing pipes respectively, the lower ends of the second blowing pipe, the first blowing pipe and the insulation pipe are all flush with the lower wall of the fifth plate body, the multiple groups of insulation pipes are respectively opposite to the multiple groups of spinnerets, the inner wall of the insulation pipe is provided with wire outlet holes which pass 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, and the cooling wind speed provided by the first cooling air providing device is lower than the cooling wind speed provided by the second cooling wind providing device.

[0012] Preferably, the heat insulation structure is a heat insulation pad, which is fixedly connected between the third plate body and the second plate body. A plurality of through holes are arranged on the inner wall of the heat insulation pad, and the plurality of through holes are respectively located between a plurality of spinnerets and a plurality of heat insulation tubes.

[0013] 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 positioning pins.

[0014] Preferably, the upper opening size of the spinneret hole is larger than the lower opening size. The spinneret hole is composed of a central hole with a circular top view projection and a plurality of semi-circular holes with a semi-circular top view projection. The plurality of semi-circular holes are arranged in a circumferential equidistant manner with the center of the central hole as the center of the circle on the outside of the central hole.

[0015] Preferably, the inner wall of the first air blowing pipe is provided with a first air blowing hole that penetrates up and down. A first narrowing part is arranged on the inner side wall of the first air blowing hole and close to the lower end of the first air blowing pipe. A first air blowing cavity is formed between the inner side wall of the first air blowing hole and the outer wall of the corresponding heat insulation tube, and a first pressurizing cavity is formed between the inner side wall of the first narrowing part and the outer wall of the corresponding heat insulation tube.

[0016] Preferably, the inner wall of the second air blowing pipe is provided with a second air blowing hole that penetrates up and down. A second narrowing part is arranged on the inner side wall of the second air blowing hole and close to the lower end of the second air blowing pipe. A second air blowing cavity is formed between the inner side wall of the second air blowing hole and the outer wall of the corresponding first air blowing pipe, and a second pressurizing cavity is formed between the inner side wall of the second narrowing part and the outer wall of the corresponding first air blowing pipe.

[0017] Preferably, a plurality of first joints are arranged on the circumferential outer wall of the fourth plate body. One ends of the plurality of first joints far away from the fourth plate body are respectively connected with a first cooling air supply device through a plurality of pipelines. A plurality of first air guiding straight grooves are arranged on the upper wall of the fourth plate body. The extension lines of one ends of the plurality of first air guiding straight grooves in the length direction all intersect with the center line of the fourth plate body. One end of the first air guiding straight groove close to the circumferential outer wall of the fourth plate body is communicated with the first joint through a first air inlet hole, and the end of the first air guiding straight groove far away from the first air inlet hole is communicated with a first air guiding ring groove.

[0018] Preferably, a plurality of second joints are arranged on the circumferential outer wall of the fifth plate body. One ends of the plurality of second joints far away from the fifth plate body are respectively connected with a second cooling air supply device through a plurality of pipelines. A plurality of second air guiding straight grooves are arranged on the upper wall of the fifth plate body. The extension lines of one ends of the plurality of second air guiding straight grooves in the length direction all intersect with the center line of the fifth plate body. One end of the second air guiding straight groove close to the circumferential outer wall of the fifth plate body is communicated with the second joint through a second air inlet hole, and the end of the second air guiding straight groove far away from the second air inlet hole is communicated with a second air guiding ring groove.

[0019] Beneficial effects

[0020] The present invention provides a polylactic acid fiber with a circular wave-shaped special cross-section and a spinneret plate thereof, having the following beneficial effects:

[0021] Compared with the prior art, for the polylactic acid fiber with a circular wave-shaped special cross-section, multiple groups of semi-circular circular wave bodies are arranged on the outer wall of the central body of the circular cross-section, so that the fiber cross-section forms a circular wave-shaped special cross-section. The softness, fluffiness and moisture conductivity of the fiber are improved through the multiple groups of circular wave bodies. By restricting the ratio of the radius of the circular wave body to the radius of the central body, the overall shape of the cross-section changes little during the production of drawn filaments and the central body can still maintain a high strength after drawing, so as to meet the production of ultra-fine fiber drawn filaments.

[0022] Compared with the prior art, for the polylactic acid fiber with a circular wave-shaped special cross-section and its spinneret plate, while the nascent filament is ejected through the spinneret holes, the cooling air provided by the first cooling air supply device and the second cooling air supply device is blown out along the filament ejection direction through the first blowing cavity and the second blowing cavity respectively, forming two concentric annular cooling air curtains to wrap and blow-cool the nascent filament. Through the different temperatures and wind speeds of the two air curtains, the gradual cooling of the nascent filament is realized, effectively improving the uniformity of the cooling intensity of the filament bundle and enhancing the quality of the filament bundle product. At the same time, the problem of filament bundle entanglement caused by the traditional blowing method is also completely avoided. Brief description of the drawings

[0023] Figure 1 is a schematic structural diagram of the present invention;

[0024] Figure 2 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;

[0025] Figure 3 is of the present invention Figure 2 partial enlarged view at A in;

[0026] Figure 4 is of the present invention Figure 2 partial enlarged view at B in;

[0027] Figure 5 is of the present invention Figure 2 partial enlarged view at C in;

[0028] Figure 6 is a schematic top view structure diagram of the spinneret head and spinneret holes of the present invention;

[0029] Figure 7 is a partial cross-sectional view of the internal structure of the first air blowing pipe of the present invention;

[0030] Figure 8 is a partial cross-sectional view of the internal structure of the second air blowing pipe of the present invention;

[0031] Figure 9 Schematic diagram of the top view structure of the fourth plate body of the present invention;

[0032] Figure 10 Schematic diagram of the top view structure of the fifth plate body of the present invention;

[0033] Figure 11 Schematic diagram of the partial structure of the fiber body of the present invention.

[0034] Among them, 1, the first plate body; 101, the fixing ear; 2, the second plate body; 3, the third plate body; 4, the fourth plate body; 5, the fifth plate body; 6, the connecting seat; 7, the liquid guiding cavity; 8, the liquid guiding ring groove; 9, the liquid guiding hole; 10, the positioning pin; 11, the heat insulation pad; 12, the first joint; 13, the second joint; 14, the first air guiding straight groove; 15, the first air inlet hole; 16, the second air guiding straight groove; 17, the second air inlet hole; 18, the spinneret; 19, the spinneret hole; 1901, the central hole; 1902, the semi-circular hole; 20, the heat insulation tube; 2001, the wire outlet hole; 21, the fiber body; 2101, the central body; 2102, the circular wave body; 22, the first air blowing pipe; 2201, the first air blowing hole; 2202, the first narrowing part; 23, the second air blowing pipe; 2301, the second air blowing hole; 2302, the second narrowing part; 24, the first air guiding ring groove; 25, the second air guiding ring groove. Specific embodiments

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] Embodiment:

[0037] As Figure 11 shown, the embodiment of the present invention provides a polylactic acid fiber with a circular wave surface special-shaped cross-section, including a fiber body 21. The fiber body 21 is composed of a central body 2101 and multiple groups of circular wave bodies 2102. The cross-section of the central body 2101 is circular, and the cross-section of the circular wave body 2102 is semi-circular. Multiple groups of circular wave bodies 2102 are arranged in a circumferential equidistant manner on the circumferential outer wall of the central body 2101 with the axis of the central body 2101 as the center. The production method of the fiber body 21 includes the following steps:

[0038] S1. Using polylactic acid as a raw material, slicing and drying the polylactic acid;

[0039] S2. After the dried polylactic acid chips are melted by a screw extruder, they are sent into a spinning box through a metering pump, then the filament bundle is ejected through a spinneret plate, and finally, through the processes of cooling, oiling, and winding, the primary polylactic acid filaments with a circular wave-shaped special cross-section are obtained.

[0040] S3. The primary polylactic acid filaments with a circular wave-shaped special cross-section are subjected to stretching, shaping, crimping, drying, and winding processes to obtain polylactic acid fibers with a circular wave-shaped special cross-section.

[0041] The radius of the semi-circle of the circular wave body 2102 is one-fifth of the radius of the circle of the central body 2101. A plurality of groups of circular wave bodies 2102 are arranged on the outer wall of the central body 2101, which can effectively improve the fluffiness and softness of the fiber body 21. By restricting 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 changes little during the production of the drawn filament, and the central body 2101 can still maintain a high strength after stretching, so as to meet the production of ultra-fine fiber drawn filaments.

[0042] As Figures 1 to 10 shown, the embodiment of the present invention also provides a spinneret plate for polylactic acid fibers with a circular wave-shaped special cross-section, which is used to produce the above-mentioned polylactic acid fibers with a circular wave-shaped special cross-section. The spinneret plate includes a first cooling air supply device, a second cooling air supply 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. A plurality of groups of fixing ears 101 are arranged on the outer wall of the first plate body 1, and bolt through-holes that penetrate up and down are arranged on the inner walls of the plurality of groups of fixing ears 101. 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 being positioned by the four groups of positioning pins 10 and then assembled, it can ensure that the parts on each plate body can be aligned up and down without misalignment. The spinneret plate is fixedly connected to the spinning box by inserting bolts into the bolt through-holes of the fixing ears 101;

[0043] In order to enable the polylactic acid melt to smoothly enter the spinneret plate, a connecting seat 6 is arranged on the upper wall of the first plate body 1. A liquid guide cavity 7 that penetrates the upper wall of the connecting seat 6 is arranged inside the connecting seat 6. A liquid guide ring groove 8 is arranged on the inner lower wall of the liquid guide cavity 7. A plurality of groups of liquid guide holes 9 are arranged on the inner lower wall of the liquid guide ring groove 8. The plurality of groups of liquid guide holes 9 are evenly distributed in a circumferential equidistant manner with the axis of the first plate body 1 as the center. The lower ends of the plurality of groups of liquid guide holes 9 all penetrate the lower wall of the first plate body 1. A plurality of groups of spinneret heads 18 are fixedly connected to the inner wall of the second plate body 2 in a vertically penetrating manner. The plurality of groups of spinneret heads 18 are respectively opposite to the plurality of groups of liquid guide holes 9 up and down. A spinneret hole 19 that penetrates up and down is arranged on the inner wall of the spinneret head 18. The polylactic acid melt enters a group of spinneret holes 19 respectively through the plurality of groups of liquid guide holes 9. Through the shunting effect of the plurality of groups of liquid guide holes 9, when the pressure of the upstream metering pump is the same, the melt components shunted through the liquid guide cavity 7 and the liquid guide holes 9 are kept consistent;

[0044] In order to prevent the temperature of the second plate body 2 from being reduced when the first cooling air supply device supplies 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. The heat insulation structure is a heat insulation pad 11. The heat insulation pad 11 is fixedly connected between the third plate body 3 and the second plate body 2. A plurality of groups of through holes are provided on the inner wall of the heat insulation pad 11. The plurality of groups of through holes are respectively located between the plurality of spinnerets 18 and the plurality of heat insulation pipes 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 plate bodies below the third plate body 3, and keep the temperature of the melt inside the spinneret 18 capable of smooth spinning;

[0045] In order to form a polylactic acid fiber with a circular wave surface special-shaped cross section, the upper opening size of the spinneret hole 19 is larger than the lower opening size. The spinneret hole 19 is composed of a central hole 1901 with a circular top view projection and a plurality of semi-circular holes 1902 with a semi-circular top view projection. The plurality of semi-circular holes 1902 are all arranged in a circumferential equidistant manner with the center of the central hole 1901 as the center of the circle on the outside of the central hole 1901. The spinneret hole 19 formed by the central hole 1901 and the plurality of semi-circular holes 1902 enables the melt to form a special-shaped cross section with a circular wave surface after being ejected from the spinneret hole 19. The larger upper opening size and the smaller lower opening size of the spinneret hole 19 increase the pressure of the melt when passing through the spinneret hole 19, and effectively improve the spinning quality under the condition that the pressure of the upstream pump remains unchanged;

[0046] In order to form a first cooling air curtain outside the nascent filament, a first air guiding annular groove 24 is provided on the upper wall of the fourth plate body 4. A plurality of first air blowing pipes 22 are fixedly connected to the inner lower wall of the first air guiding annular groove 24. The lower ends of the plurality of first air blowing pipes 22 all penetrate through the inner wall of the fourth plate body 4 and extend into the interiors of a plurality of second air blowing pipes 23 respectively. A first air blowing hole 2201 that runs through from top to bottom is provided on the inner wall of the first air blowing pipe 22. A first narrowing portion 2202 is provided on the inner side wall of the first air blowing hole 2201 and close to the lower end of the first air blowing pipe 22. A first air blowing cavity is formed between the inner side wall of the first air blowing hole 2201 and the outer wall of the corresponding heat insulation pipe 20. A first pressurizing cavity is formed between the inner side wall of the first narrowing portion 2202 and the outer wall of the corresponding heat insulation pipe 20. A plurality of first connectors 12 are provided on the circumferential outer wall of the fourth plate body 4. One ends of the plurality of first connectors 12 far away from the fourth plate body 4 are respectively connected to a first cooling air supply device through a plurality of pipes. A plurality of first air guiding straight grooves 14 are provided on the upper wall of the fourth plate body 4. The extension lines of one ends in the length direction of the plurality of first air guiding straight grooves 14 all intersect with the central 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 communicated with the first connector 12 through a first air inlet hole 15. One end of the first air guiding straight groove 14 far away from the first air inlet hole 15 is communicated with the first air guiding annular groove 24. The cooling air supplied by the first cooling air supply device enters the first air guiding annular groove 24 through the first connector 12, the first air inlet hole 15, and the first air guiding straight groove 14. The multiple strands of cooling air sent by the plurality of first connectors 12 converge inside the first air guiding annular groove 24. After convergence, it blows towards the spinning direction of the nascent filament through the first air blowing cavity and is pressurized through the first pressurizing cavity. The pressurized cooling air forms an annular cooling air curtain around the nascent filament to cool down the nascent filament, and the cooling intensity is consistent within the same cross-section of the filament bundle;

[0047] In order to form a second cooling air curtain outside the nascent filament, a second air guiding annular groove 25 is provided on the upper wall of the fifth plate body 5. A plurality of groups of second air blowing pipes 23 are fixedly connected to the inner lower wall of the second air guiding annular groove 25. A second air blowing hole 2301 that penetrates up and down is provided on the inner wall of the second air blowing pipe 23. A second narrowing portion 2302 is provided on the inner side wall of the second air blowing hole 2301 and near the lower end position of the second air blowing pipe 23. A second air blowing cavity is formed between the inner side wall of the second air blowing hole 2301 and the outer wall of the corresponding first air blowing pipe 22. A second pressurizing cavity is formed between the inner side wall of the second narrowing portion 2302 and the outer wall of the corresponding first air blowing pipe 22. A plurality of groups of second connectors 13 are provided on the circumferential outer wall of the fifth plate body 5. One ends of the plurality of groups of second connectors 13 far away from the fifth plate body 5 are respectively connected to a second cooling air supply device through a plurality of pipes. A plurality of groups of second air guiding straight grooves 16 are provided on the upper wall of the fifth plate body 5. The extension lines of one ends in the length direction of the plurality of groups of second air guiding straight grooves 16 all 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 communicates with the second connector 13 through a second air inlet hole 17. One end of the second air guiding straight groove 16 far away from the second air inlet hole 17 communicates with the second air guiding annular groove 25. The cooling air supplied by the second cooling air supply device enters the second air guiding annular groove 25 through the second connector 13, the second air inlet hole 17, and the second air guiding straight groove 16. The multi-strand cooling air sent by the plurality of groups of second connectors 13 converges inside the second air guiding annular groove 25. After convergence, it blows in the spinning direction of the nascent filament through the second air blowing cavity and is pressurized through the second pressurizing cavity. The pressurized cooling air regenerates a cooling air curtain outside the first cooling air curtain formed by the first pressurizing cavity, effectively improving the cooling effect;

[0048] In order to perform gradient cooling on the nascent filament ejected from the spinneret hole 19, the temperature of the cooling air supplied by the first cooling air supply device is between the temperature of the cooling air supplied by the second cooling air supply device and the spinning temperature of the spinneret hole 19. The wind speed of the cooling air supplied by the first cooling air supply device is less than the wind speed of the cooling air supplied by the second cooling air supply device. The temperature of a cooling air curtain close to the nascent filament bundle is between the temperature of the cooling air supplied by the second cooling air supply device and the spinning temperature of the spinneret hole 19. However, its wind speed is small, and it only cools the nascent filament when it is ejected from the spinneret hole 19. Subsequently, continuous cooling is performed through the outer cooling air curtain. Through this setting, it is possible to avoid local stress concentration caused by strong cold air directly blowing on the nascent filament, effectively improving the cooling quality of the filament bundle;

[0049] To avoid the cooling air from affecting the temperature of the spinneret 18, a plurality of heat-insulating tubes 20 are fixedly connected to the inner wall of the third plate body 3. The lower ends of the plurality of heat-insulating tubes 20 penetrate through the inner wall of the third plate body 3 and extend into a plurality of first air blowing tubes 22 respectively. The lower ends of the second air blowing tube 23, the lower ends of the first air blowing tubes 22, and the lower ends of the heat-insulating tubes 20 are flush with the lower wall of the fifth plate body 5. The plurality of heat-insulating tubes 20 are respectively opposite to the plurality of spinnerets 18 up and down. The inner wall of the heat-insulating tube 20 is provided with a wire outlet hole 2001 that runs through up and down. After the filament bundle is ejected from the spinneret hole 19, it moves downward along the wire outlet hole 2001, and the cooling air blows downward along the outer wall of the heat-insulating tube 20, without reducing the temperature of the spinneret 18;

[0050] Working principle: After positioning with four groups of positioning pins 10 and then assembling, it can ensure that the parts on each plate body can be aligned up and down without dislocation. The spinneret plate is fixedly connected to the spinning box by inserting bolts into the bolt through-holes of the fixed ears 101. The polylactic acid melt enters a group of spinneret holes 19 through multiple groups of liquid guide holes 9 respectively. Through the multiple groups of liquid guide holes 9, a shunting effect is formed. Under the condition that the upstream metering pump pressure is the same, the melt components shunted through the liquid guide cavity 7 and the liquid guide holes 9 are kept consistent. The third plate body 3 and the second plate body 2 are separated by the heat insulation pad 11 to avoid the internal temperature of the second plate body 2 being affected by the temperature of the third plate body 3 and other plate bodies below the third plate body 3, so as to keep the melt temperature inside the spinneret 18 and enable smooth spinning. The spinneret holes 19 formed by the central hole 1901 and multiple groups of semi-circular holes 1902 enable the melt to form a special-shaped cross-section with a circular wave surface after being ejected from the spinneret holes 19. The upper opening size of the spinneret holes 19 is larger than the lower opening size, which increases the pressure of the melt when passing through the spinneret holes 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 supply 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 strands of cooling air sent by multiple groups of first joints 12 converge inside the first air guide ring groove 24. After convergence, it blows towards the spinning direction of the nascent filament through the first air blowing cavity and is pressurized through the first pressurizing cavity. The pressurized cooling air forms an annular cooling air curtain around the nascent filament to cool down the nascent filament. The cooling intensity within the same cross-section of the filament bundle is consistent. The cooling air supplied by the second cooling air supply device enters the second air guide ring groove 25 through the second joint 13, the second air inlet hole 17, and the second air guide straight groove 16. The multiple strands of cooling air sent by multiple groups of second joints 13 converge inside the second air guide ring groove 25. After convergence, it blows towards the spinning direction of the nascent filament through the second air blowing cavity and is pressurized through the second pressurizing cavity. The pressurized cooling air regenerates a cooling air curtain outside the first cooling air curtain formed by the first pressurizing cavity, effectively improving the cooling effect. The temperature of a cooling air close to the nascent filament bundle is between the cooling air supplied by the second cooling air supply device and the spinning temperature of the spinneret holes 19, but its wind speed is small, and it only cools the nascent filament when it is ejected from the spinneret holes 19, and then continues to cool through the outer cooling air curtain. Through this setting, it can avoid the strong cold air directly blowing on the nascent filament and causing local stress concentration, effectively improving the cooling quality of the filament bundle. After the filament bundle is ejected from the spinneret holes 19, it moves downward along the wire outlet hole 2001, and the cooling air blows downward along the outer wall of the heat insulation pipe 20 without reducing the temperature of the spinneret 18.

[0051] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A spinneret for polylactic acid fiber with a circular wave surface and a special-shaped cross-section, characterized in that: The spinneret comprises 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, a plurality of groups of fixing ears are arranged on the outer wall of the first plate body, and bolt through holes which penetrate up and down are arranged on the inner walls of the plurality of groups of fixing ears, a connecting seat is arranged on the upper wall of the first plate body, and a liquid guide which penetrates the upper wall of the connecting seat is arranged inside the connecting seat The inner lower wall of the liquid-conducting cavity is provided with a liquid-conducting annular groove, and the inner lower wall of the liquid-conducting annular groove is provided with a plurality of groups of liquid-conducting holes, 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 all connected with the lower wall of the first plate body, and the inner wall of the second plate body is 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 in the upper and lower parts, and the inner wall of the spinneret is provided with spinneret holes that are connected up and down, and a heat-insulating hole is provided between the third plate body and the second plate body. The heat insulation structure is as follows: the upper wall of the fifth plate body is provided with a second air guide ring groove, and the inner lower wall of the second air guide ring groove is fixedly connected to multiple groups of second blowing pipes; the upper wall of the fourth plate body is provided with a first air guide ring groove, and the inner lower wall of the first air guide ring groove is fixedly connected to multiple groups of first blowing pipes, and the lower ends of the multiple groups of the first blowing pipes all penetrate the inner wall of the fourth plate body and extend into the interior of the multiple groups of second blowing pipes respectively; the inner wall of the third plate body is fixedly connected to multiple groups of insulation pipes, and the lower ends of the multiple groups of the insulation pipes all penetrate the inner wall of the third plate body and extend respectively Enter into multiple groups of first blowing pipes, the lower ends of the second blowing pipe, the first blowing pipe and the insulation pipe are all flush with the lower wall of the fifth plate, the multiple groups of insulation pipes are respectively opposite to the multiple groups of spinnerets, the inner wall of the insulation pipe is provided with a vertically through-going wire outlet hole, 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, 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.

2. The spinneret of the polylactic acid fiber with a circular wave surface and a special-shaped cross-section according to claim 1, characterized in that: The thermal insulation structure is a thermal insulation pad, which is fixedly connected between the third plate body and the second plate body. The inner wall of the thermal insulation pad is provided with multiple groups of through holes, and the multiple groups of through holes are respectively located between the multiple groups of spinnerets and the multiple groups of thermal insulation tubes.

3. The spinneret of the polylactic acid fiber with a circular wave surface and a special-shaped cross-section according to claim 2, characterized in that: 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.

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 upper opening of the spinneret is larger than the lower opening. The spinneret 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. 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.

5. The spinneret of the polylactic acid fiber with round wave surface profile cross section according to claim 4, characterized in that: 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.

6. The spinneret of polylactic acid fiber with round wave surface profile cross section according to claim 5, characterized in that: 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.

7. The spinneret of polylactic acid fiber with round wave surface and special cross section according to claim 6, characterized in that: The fourth plate body is provided with a plurality of first joints on the circumferential outer wall, and the ends of the plurality of first joints away from the fourth plate body are connected to the first cooling air providing device through a plurality of pipes respectively; the fourth plate body is provided with a plurality of first straight air guide grooves on the upper wall, and the extension lines of the ends of the plurality of first straight air guide grooves in the length direction intersect with the center line of the fourth plate body; the ends of the first straight air guide grooves close to the circumferential outer wall of the fourth plate body are connected with the first joint through the first air inlet hole, and the ends of the first straight air guide grooves away from the first air inlet hole are connected with the first air guide ring groove.

8. The spinneret of polylactic acid fiber with round wave surface and special cross section according to claim 7, characterized in that: 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 connected to the second cooling air providing device through a plurality of groups of pipes respectively; 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; 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.

9. A polylactic acid fiber with a round wave surface profiled cross section, wherein the polylactic acid fiber with a round wave surface profiled cross section is produced using a spinneret for a polylactic acid fiber with a round wave surface profiled cross section as claimed in any one of claims 1 to 8, characterized in that: The fiber body comprises a central body and a plurality of groups of circular wave bodies, wherein the central body has a circular cross section, the circular wave bodies have a semicircular cross section, and the plurality of groups of circular wave bodies are arranged on the outer wall of the central body in a circular shape with the central body axis as the center. 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 spun yarn with a round wave surface profiled cross section is subjected to the steps of stretching, shaping, curling, drying and winding to obtain a polylactic acid fiber with a round wave surface profiled cross section; The semicircular radius of the circular wave body is one fifth of the central circular radius.

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