A coiled composite elastic fiber, preparation method and spinning assembly

Abstract

The present invention discloses a coiled composite elastic fiber, a preparation method and a spinning assembly, relating to the technical field of composite fibers. After the first polyester fiber-forming high polymer and the second polyester fiber-forming high polymer are respectively melted, a bi-component composite spinning assembly is used for composite spinning. The two components with different heat shrinkage properties respectively pass through their respective independent spinneret guide holes, and finally are bonded and compounded in a reverse tangential manner to form a rotating coiled composite fiber. By adopting a composite spinning assembly and a spinneret plate that are left-right reverse tangential on the composite circumference, the melt is in a tangential rotation state after compounding, which can reduce the effect of the bend angle and prevent the filament from adhering to the spinneret plate. The preparation process of the present invention is simple and the process is convenient. The obtained coiled composite elastic fiber has excellent crimping performance, shape retention performance and wicking and sweat discharge functions. After weaving, it has a plump handfeel, is smooth and delicate, and can meet the requirements of weaving and knitting.

Description

Technical Field

[0001] The present invention relates to the technical field of composite fibers, and particularly relates to a kinked composite elastic fiber, a preparation method, a spinning assembly, and an application of the bionic fiber on a fabric. Background Art

[0002] The conventional process for causing crimp in chemical fiber staple fibers is to subject the fiber bundle to mechanical extrusion in a crimper box under high temperature and humidification (oil spraying) conditions to generate crimp. In this way, planar zigzag crimp is obtained, with poor crimp elasticity and difficult-to-maintain crimp shape. Later, when studying the microscopic structural morphology of wool, it was found that the cross-section of wool fibers has a bicomponent structure, and the properties and arrangements of the fibrils, crystalline regions, and amorphous regions in the two components are different, resulting in shrinkage differences and forcing the wool to form helical crimp. Inspired by this, researchers designed a novel composite spinning process to develop side-by-side bicomponent composite fibers, enabling them to generate helical three-dimensional crimp after heat shrinkage. This technology has been widely applied to PET-PTT composite crimped fibers.

[0003] In addition, under single-screw spinning conditions, by changing the spinning process and adopting an asymmetric cooling method for the nascent filament to cause differences in skin-core heat shrinkage, three-dimensional crimped fibers can also be prepared. Such crimped fibers have a memory effect and persistent crimp morphology. For example, when the fibers are damp, the number of crimps decreases, but they can be restored after drying. The three-dimensional crimped fibers have stronger bulkiness and warmth retention, more comfortable handfeel, and also improve the cohesion during fiber processing and the dimensional stability of the fabric.

[0004] Compared with conventional fibers, side-by-side composite elastic fibers not only have excellent three-dimensional crimp elasticity but also excellent bulkiness and soft handfeel, and have been greatly developed.

[0005] Although the above technical improvements have improved the wearing comfort of chemical fibers, they are still much inferior to cotton fibers, especially the moisture absorption performance has not been improved. Compared with cotton fibers, it is a structure with natural twists and hollow grooves due to the different growth speeds during different growth periods of plants.

[0006] The longitudinal morphological characteristics of cotton fibers are flat, and they are all in the form of bundle-like small fibers inclined to the fiber axis in a spiral shape and form rotations along the fiber length direction. The cross-section of cotton fibers consists of many concentric layers, mainly including a primary layer, a secondary layer, and a lumen. Among them, different layers have different thicknesses, forming natural continuous radial thickness and twist changes. The comprehensive performance of cotton fiber fabrics, in addition to their cellulose composition, is more importantly their continuous radial thickness and the changing structure of twists. And bionically imitating the structure of cotton fibers with chemical fibers has been the goal that those skilled in the art have been striving to achieve. Summary of the Invention

[0007] The object of the present invention is to solve the above technical problems, and provide a coiled composite elastic fiber, a preparation method and a spinning assembly, so as to realize the biomimetic structure of chemical fibers.

[0008] In order to achieve the above technical object and meet the above technical requirements, the technical solution adopted by the present invention is: a preparation method of a coiled composite elastic fiber, characterized by comprising the following steps:

[0009] Step 1: Two compatible but different in heat shrinkage fiber-forming polyesters, namely a first polyester fiber-forming polymer and a second polyester fiber-forming polymer, are melted respectively to obtain a first melt A and a second melt B; the melting temperature of the polyester fiber-forming polymer is determined according to the melting point and viscosity of each polyester fiber-forming polymer. Generally, the melting temperature is more than 30 °C higher than the melting point of the polyester fiber-forming polymer. For the polyester fiber-forming polymer with high viscosity, in order to improve fluidity, the melting temperature can be increased by another 3-8 °C.

[0010] Step 2: The first melt A and the second melt B obtained in Step 1 are subjected to composite spinning using a bicomponent composite spinning assembly; the first melt A and the second melt B are fed into the feed plate of the composite spinning assembly at a mass ratio of 4:6 to 6:4, enter the first melt A inlet and the second melt B inlet on the spinneret plate through their respective melt channels, and respectively pass through their respective inclined spinning guide holes, tapered holes and spinning micropores, and finally are compounded at the melt compounding circumference; when compounding, the two melts are tangentially in opposite directions on the left and right at the melt compounding circumference, and the intersecting part accounts for 1 / 4 - 3 / 4 of the total melt amount, and the obtained fiber is in a coiled and rotating state axially;

[0011] The bicomponent composite spinning assembly includes an assembly housing, and inside the assembly housing, a feed plate, a gasket, a sand pool, a filter screen, an upper distribution plate, a lower distribution plate and a spinneret plate are sequentially arranged along the melt flow direction. Two melt channels are arranged on the feed plate. 4-8 sink holes are evenly opened in each melt distribution channel on the upper distribution plate to send the melt to the annular distribution channel on the lower distribution plate. On each melt annular distribution channel of the lower distribution plate, a pair of sink holes with the same number as the composite spinning holes are opened, and the pair of sink holes are correspondingly connected to the first melt A inlet and the second melt B inlet on the spinneret plate. The first melt A inlet is connected to the inclined spinning guide hole assembly A, and the second melt B inlet is connected to the inclined spinning guide hole assembly B. The planar projections of the spinning guide hole assembly A and the spinning guide hole assembly B on the spinneret plate are in opposite directions on the left and right at the melt compounding circumference, and the included angle α between the spinning guide hole assembly A, the spinning guide hole assembly B and the front view projection of the spinneret plate is 60° - 120°, and the diameter of the melt compounding circumference is 1-2 times the diameter of the spinning micropores;

[0012] Step 3: The nascent fibers obtained by compounding in Step 2 are successively subjected to ring blowing cooling and oiling, and then wound after the tension is adjusted by a pair of godet wheels to obtain pre-drawn crimped elastic fibers (POY), and permanent crimped elastic fibers are obtained after being drawn by a texturing machine.

[0013] Preferably: The spinneret guide hole assembly A includes an axially symmetric spinneret guide hole A, a tapered hole A, and a spinneret micro-hole A connected in sequence. The central axes of the spinneret guide hole A, the tapered hole A, and the spinneret micro-hole A are on a straight line. The spinneret guide hole assembly B includes an axially symmetric spinneret guide hole B, a tapered hole B, and a spinneret micro-hole B connected in sequence. The central axes of the spinneret guide hole B, the tapered hole B, and the spinneret micro-hole B are on a straight line.

[0014] Preferably: The melt compounding circle is arranged inside the spinneret plate, and the distance from the lower plane of the spinneret plate is 0.2 - 0.5 mm.

[0015] Preferably: The melt compounding circle is arranged on the lower plane of the spinneret plate.

[0016] Preferably: The melt compounding circle is arranged outside the spinneret plate, and the distance from the lower plane of the spinneret plate is 0.2 - 0.5 mm.

[0017] A crimped composite elastic fiber is obtained by the above preparation method, and is composed of a first polyester fiber-forming high polymer and a second polyester fiber-forming high polymer with different heat shrinkage properties, and the fiber axis is in a crimped and rotating state; it has a groove structure, and the width of the groove is 1 / 2 - 1 / 4 of the fiber diameter; the mass ratio of the first polyester fiber-forming high polymer to the second polyester fiber-forming high polymer is 1:1, and the viscosity difference between the first polyester fiber-forming high polymer and the second polyester fiber-forming high polymer is more than 0.3 dl / g.

[0018] The application of a crimped composite elastic fiber in a fabric includes being made into a fiber aggregate alone, such as woven into a fabric for underwear, shirts, sportswear, home clothing, etc., and can also be used in combination with other fibers to make a blended woven fabric.

[0019] The present invention uses a double-channel composite spinneret plate. The distribution plate is provided with melt channels for component A and component B. The spinneret plate is respectively provided with melt inlets and spinneret guide hole assemblies for component A and component B. The spinneret guide holes, tapered holes, and spinneret micro-holes of the two-component melt are on a straight line. The spinneret guide hole assembly A and the spinneret guide hole assembly B are arranged in a non-axially symmetric and inclined manner and do not communicate with each other. Below the spinneret guide holes and tapered holes are two spinneret micro-holes with the same or different diameters, and their projections are tangent to each other left and right on the compounding circle. After the two-component melt flows through their respective spinneret guide holes, tapered holes, and spinneret micro-holes and sprays out, they converge and bond along the compounding circle to form a rotating crimped composite fiber.

[0020] After studying the morphology of the coiled composite fiber, the present invention surprisingly discovers that such rotating coiled composite fiber will form a continuous rotating groove structure during the asymmetric cooling process, and this groove structure has obvious capillary core absorption effect.

[0021] The surface of the as-spun filament obtained by the present invention has a continuous and coiled groove structure, which can further improve the crimp performance of the composite elastic fiber.

[0022] Compared with the traditional structure, the beneficial effects of the present invention are as follows:

[0023] 1. The structure of the present invention is novel and reasonable in design. Two sets of non-connecting oblique melt channels are adopted, and two components with different heat shrinkage properties respectively pass through their respective independent spinneret orifices, and finally bond and composite in a reverse tangential manner to form a rotating coiled composite fiber. The bonding and composite position can be set at three positions, namely, inside the spinneret plate, on the lower plane of the spinneret plate, and below the lower plane of the spinneret plate according to the different melt viscosities to achieve the best rotating composite effect.

[0024] 2. The present invention adopts a composite circumferential design, and the melt is in a tangential rotating state after composite, which can reduce the effect of the bend angle and prevent the filament from adhering to the spinneret plate. When spinning elastic composite fiber by using different melt viscosities, due to the large difference in the viscosities of the two melts, when the two melts are directly composite, the melt is prone to occur the elbow angle phenomenon when exiting the spinneret plate, and the filament adheres to the spinneret plate, resulting in the adhesion of the filament bundle and affecting the quality of the filament. In severe cases, continuous spinning cannot be carried out. The problem is solved.

[0025] 3. The preparation method provided by the present invention has simple process and convenient process flow. The prepared coiled composite elastic fiber has excellent crimp performance, shape retention performance and core absorption and sweat discharge functions. After weaving, it has a plump hand feeling, is smooth and delicate, and can meet the requirements of weaving and knitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the spinning assembly of the present invention;

[0027] Figure 2 It is a top view structural diagram of the spinneret plate of the present invention;

[0028] Figure 3 It is a plane projection diagram of the oblique spinneret orifice assembly of the present invention;

[0029] Figure 4 It is one of the relative position projection diagrams of the composite spinneret of the present invention;

[0030] Figure 5 It is two of the relative position projection diagrams of the composite spinneret of the present invention;

[0031] Figure 6 It is three of the relative position projection diagrams of the composite spinneret of the present invention;

[0032] In the figure: 1. Component housing; 2. Feed plate; 3. Gasket; 4. Sand pool; 5. Filter screen; 6. Upper distribution plate; 7. Lower distribution plate; 8. Spinneret plate; 9. First melt A feed port; 10. Second melt B feed port; 11. Melt composite circumference; 12. Spinning guide hole A; 13. Tapered hole A; 14. Spinning micropore A. Specific embodiments

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] A method for preparing a coiled composite elastic fiber includes polyethylene terephthalate (PTT) as the first polyester fiber-forming high polymer and polyethylene terephthalate (PET) as the second polyester fiber-forming high polymer, wherein the viscosity of PTT is 1.05 dL / g and the viscosity of PET is 0.64 dL / g; it also includes a viscosity-increased polyethylene terephthalate (PET) as the first polyester fiber-forming high polymer and an un-viscosity-increased polyethylene terephthalate (PET) as the second polyester fiber-forming high polymer, wherein the viscosity of the viscosity-increased PET is 0.95 dL / g and the viscosity of PET is 0.64 dL / g;

[0035] It also includes a modified polyethylene terephthalate as the first polyester fiber-forming high polymer and an unmodified polyethylene terephthalate as the second polyester fiber-forming high polymer. The modified polyethylene terephthalate is modified by a thermoplastic elastomer, wherein the mass percentage of the thermoplastic elastomer is 1-10%, preferably 2-8%, more preferably 2.5-6%, and its modified viscosity is 0.95-1.15 dL / g.

[0036] The preparation method of the thermoplastic elastomer-modified polyethylene terephthalate preferably includes melting and blending a thermoplastic elastomer (TPEE) and polyethylene terephthalate (PET) and then extruding to obtain the thermoplastic elastomer-modified polyethylene terephthalate. The melting and blending is carried out in a twin-screw extruder, and the temperature of the melting and blending extrusion is preferably 245-285 °C, more preferably 255-275 °C.

[0037] The first polyester fiber-forming high polymer chips and the second polyester fiber-forming high polymer chips are respectively melted to obtain a first melt A and a second melt B. In the present invention, the moisture content of the chips is less than 50 ppm, preferably less than 30 ppm; there are no special requirements for the source of the PET or PTT in the present invention, and commercially available products can be used.

[0038] The present invention requires pretreatment of the fiber-forming polymer chips, and the pretreatment includes drying. The drying temperature is preferably 160-170°C, and the drying time is preferably 10-15h, more preferably 11-13h. The present invention has no special requirements for the specific implementation process of the drying.

[0039] The pretreatment of the fiber-forming polymer chips in the present invention further includes pre-crystallization, which can improve the crystallinity of PET and facilitate the subsequent smooth spinning.

[0040] In the present invention, when the first polyester fiber-forming polymer is PTT, the melting includes: passing the first polyester fiber-forming polymer through four temperature zones in sequence. The temperature of the first temperature zone is 235-245°C, the temperature of the second temperature zone is 255-265°C, the temperature of the third temperature zone is 255-265°C, and the temperature of the fourth temperature zone is 255-265°C.

[0041] In the present invention, when the first polyester fiber-forming polymer is a thermoplastic elastomer-modified polyethylene terephthalate, the melting includes: passing the first polyester fiber-forming polymer through four temperature zones in sequence. The temperature of the first temperature zone is 255-265°C, the temperature of the second temperature zone is 280-290°C, the temperature of the third temperature zone is 280-290°C, and the temperature of the fourth temperature zone is 282-292°C.

[0042] The melting of the second polyester fiber-forming polymer includes: passing the second polyester fiber-forming polymer through four temperature zones in sequence. The temperature of the first temperature zone is 255-265°C, the temperature of the second temperature zone is 285-295°C, the temperature of the third temperature zone is 288-298°C, and the temperature of the fourth temperature zone is 288-298°C.

[0043] The temperature of the spinning box is 290-295°C.

[0044] In a specific embodiment of the present invention, the melting of the first polyester fiber-forming polymer and the second polyester fiber-forming polymer is preferably carried out in a screw extruder for melting and extrusion. After obtaining the two molten polyester fiber-forming polymers, the molten polyester fiber-forming polymers are subjected to composite spinning through a bicomponent composite spinning assembly to obtain coiled composite elastic fibers.

[0045] The composite spinning preferably includes the following steps: successively carrying out spinning, cooling, oiling, and winding on the molten polyester fiber-forming polymer, and further carrying out texturing processing to obtain fibers that can be used for weaving.

[0046] The present invention provides a bicomponent composite spinning assembly used in the composite spinning of the above preparation method, such as Figure 1As described above, the two-component composite spinning assembly includes an assembly housing 1. Inside the assembly housing 1, a feed plate 2, a gasket 3, a sand pool 4, a filter screen 5, an upper distribution plate 6, a lower distribution plate 7, and a spinneret plate 8 are sequentially arranged along the melt flow direction. Two melt channels are provided on the feed plate 2. On the upper distribution plate 6, 4 - 8 sink holes are evenly opened in each melt distribution channel, and the melt is sent to the annular distribution channel on the lower distribution plate 7. On the lower distribution plate 7, a pair of sink holes with the same number as the composite spinneret holes are opened on each melt annular distribution channel. The pair of sink holes are correspondingly connected to the first melt A feed port 9 and the second melt B feed port 10 on the spinneret plate 8. The first melt A feed port 9 is connected to the inclined spinneret guide hole assembly A, and the second melt B feed port 10 is connected to the inclined spinneret guide hole assembly B.

[0047] The spinneret guide hole assembly A includes an axially symmetric spinneret guide hole A12, a tapered hole A13, and a spinneret micro-hole A14 connected in sequence. The centerlines of the spinneret guide hole A12, the tapered hole A13, and the spinneret micro-hole A14 are on a straight line. The spinneret guide hole assembly B includes a spinneret guide hole B, a tapered hole B, and a spinneret micro-hole B connected in sequence. The centerlines of the spinneret guide hole B, the tapered hole B, and the spinneret micro-hole B are on a straight line.

[0048] As Figure 2 , Figure 3 shown, the first melt A and the second melt B respectively pass through their respective inclined spinneret guide holes, tapered holes, and spinneret micro-holes, and finally are compounded at the melt compounding circumference 11. When compounding, the two melts are tangential to each other in a left-right reverse manner on the melt compounding circumference 11, and the intersecting part accounts for 1 / 4 - 3 / 4 of the total melt volume.

[0049] As Figure 4 , Figure 5 , Figure 6 shown, the spinneret guide hole assembly A and the spinneret guide hole assembly B are two groups of inclined melt channels that do not communicate with each other. The plane projections of the spinneret guide hole assembly A and the spinneret guide hole assembly B on the spinneret plate 8 are arranged in a left-right reverse manner on the melt compounding circumference. The spinneret guide hole assembly A and the spinneret guide hole assembly B form an angle of 60° - 120° in the front view projection of the spinneret plate 8, so as to generate a circumferential component force on the composite melt. With the help of the viscosity of the melt and further cooling, rotation is generated. The diameter of the melt compounding circumference 11 is 1 - 2 times the diameter of the spinneret micro-hole.

[0050] In an embodiment of the present invention, the melt compounding circumference 11 is arranged inside the spinneret plate 8, and the distance from the lower plane of the spinneret plate 8 is 0.2 - 0.5 mm.

[0051] In an embodiment of the present invention, the melt compounding circumference 11 is arranged on the lower plane of the spinneret plate 8.

[0052] In an embodiment of the present invention, the melt composite circumference 11 is disposed outside the spinneret 8, and the distance from the lower plane of the spinneret is 0.2 - 0.5 mm.

[0053] The crimped composite elastic fiber obtained by the preparation method using the above technical solution is composed of a first polyester fiber-forming polymer and a second polyester fiber-forming polymer with different heat shrinkage properties, and is in a crimped and rotating state axially; it has a groove structure, and the width of the groove is 1 / 2 - 1 / 4 of the fiber diameter. The mass ratio of the first polyester fiber-forming polymer to the second polyester fiber-forming polymer is 1:1, and the viscosity difference between the first polyester fiber-forming polymer and the second polyester fiber-forming polymer is above 0.3 dl / g.

[0054] Two melts are fed into the spinneret 8 of the composite spinning assembly according to a mass ratio of 1:1 to obtain the nascent fiber. The nascent fiber is successively subjected to ring blowing cooling, oiling, and winding after adjusting the tension through a pair of godet wheels to obtain a pre-drawn crimped elastic fiber (POY), and a permanently crimped elastic fiber is obtained after being drawn by a texturing machine. The fiber indexes are: breaking strength 2.5 - 3.8 cN / dtex, breaking elongation 15 - 35%, crimp ratio 20 - 35%, crimp recovery rate 30%, and crimp elasticity rate 80 - 95%.

[0055] Example 1: The following melt composite method is adopted Figure 4 where the diameter of the melt composite circumference is 0.35 mm, the height is 0.25 mm, the diameter of the spinneret micropores is 0.2 mm, and the length is 0.4 mm; the projection angle of the melt channel is 90°. The melt A component uses modified PET chips with a viscosity of 0.95 dl / g, and the melt B component uses conventional PET chips with a viscosity of 0.64 dl / g.

[0056] The modified PET chips are pre-crystallized at 120 °C for 1 h and dried at 165 °C for 12 h, with a moisture content < 30 ppm; the conventional PET is dried at 175 °C for 12 h, with a moisture content < 25 ppm. The modified PET chips are melted by a screw machine, and the melting temperature is: zone 1: 258 ± 1 °C, zone 2: 288 ± 1 °C, zone 3: 285 ± 1 °C, zone 4: 285 ± 1 °C to obtain molten modified PET; the conventional PET is melted by a screw machine, and the melting temperature is: zone 1: 262 ± 1 °C, zone 2: 293 ± 1 °C, zone 3: 293 ± 1 °C, zone 4: 292 ± 1 °C to obtain molten PET, and the box temperature is 293 ± 1 °C. Two melts are fed into the spinneret of the composite spinning assembly according to a mass ratio of 1:1 to obtain the nascent fiber. The nascent fiber is successively subjected to ring blowing cooling, oiling, and winding after adjusting the tension through a pair of godet wheels to obtain a pre-drawn crimped elastic fiber (POY), and a permanently crimped elastic fiber is obtained after being drawn by a texturing machine.

[0057] Breaking strength: 3.1 cN / dtex, elongation at break: 18%, crimp ratio: 24.5%, crimp recovery: 22.3%, elastic modulus of crimp: 89.5%.

[0058] Example 2: Using the melt compounding method as Figure 6 described, where the diameter of the melt compounding circumference is 0.35 mm, height -0.25 mm, diameter of the spinneret micropores is 0.2 mm, length is 0.4 mm; the projection angle of the melt channel is 115°. Component A of the melt uses PTT chips with a melting point of 227 °C and an intrinsic viscosity of 0.9 - 1.3 dL / g; component B of the melt uses conventional PET chips with a melting point of 262 °C and a viscosity of 0.5 - 0.7 dl / g. The spinning process conditions are as follows:

[0059]

[0060] The obtained POY yarn is drawn by a texturing machine to obtain an elastic fiber with permanent kinks.

[0061] Breaking strength: 3.5 cN / dtex, elongation at break: 21%, crimp ratio: 23.5%, crimp recovery: 24.3%, elastic modulus of crimp: 88.7%.

[0062] The above embodiments of the present invention are merely examples clearly illustrating the present invention and are not used to limit the protection scope of the present invention. All equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention shall be defined by each claim.

Claims

1. A method for preparing a twisted composite elastic fiber, characterized in that: The twisted composite elastic fiber is composed of two compatible fiber-forming polymers with different heat shrinkage, namely a first polyester fiber-forming polymer and a second polyester fiber-forming polymer. The fiber axis is in a twisted rotating state. The preparation method thereof comprises the following steps: Step 1: Melting the first polyester fiber-forming polymer and the second polyester fiber-forming polymer respectively to obtain a first melt A and a second melt B; Melting the first polyester fiber-forming polymer comprises: sequentially passing the first polyester fiber-forming polymer through four temperature zones, the temperature of the first temperature zone is 255-265°C, the temperature of the second temperature zone is 280-290°C, the temperature of the third temperature zone is 280-290°C, and the temperature of the fourth temperature zone is 282-292°C; Melting the second polyester fiber-forming polymer comprises: sequentially passing the second polyester fiber-forming polymer through four temperature zones, the temperature of the first temperature zone is 255-265°C, the temperature of the second temperature zone is 285-295°C, the temperature of the third temperature zone is 288-298°C, and the temperature of the fourth temperature zone is 288-298°C; Step 2: The first melt A and the second melt B obtained in step 1 are subjected to composite spinning using a two-component composite spinning assembly, wherein the two-component composite spinning assembly comprises an assembly housing (1), wherein a feed plate (2), a sealing gasket (3), a sand pool (4), a filter screen (5), an upper distribution plate (6), a lower distribution plate (7) and a spinneret (8) are sequentially arranged in the assembly housing (1) along the melt flow direction, wherein two types of melt channels are arranged on the feed plate (2), and each type of melt distribution channel on the upper distribution plate (6) is evenly provided with 4-8 countersunk holes, so as to deliver the melt to the annular distribution channel on the lower distribution plate (7), and each type of melt annular distribution channel on the lower distribution plate (7) is provided with a pair of countersunk holes having the same number as the composite spinneret holes, and the pair of countersunk holes are correspondingly connected to a first melt A feed port (9) and a second melt B feed port (10) on the spinneret (8), and the first melt A feed port (9) is connected to an oblique spinneret guide hole. The spinneret assembly A is connected to the second melt B feed port (10) and is connected to the oblique spinneret guide hole assembly B; the spinneret guide hole assembly A comprises a spinneret guide hole A (12), a conical hole A (13), and a spinneret microhole A (14) which are connected in sequence and are axially symmetrical, wherein the center lines of the spinneret guide hole A (12), the conical hole A (13), and the spinneret microhole A (14) are in a straight line, and the spinneret guide hole assembly B comprises a spinneret guide hole B, a conical hole A (13), and a spinneret microhole A (14) which are connected in sequence and are axially symmetrical. The spinneret guide hole B, the spinneret microhole B, the center lines of the spinneret guide hole B, the conical hole B, and the spinneret microhole B are on a straight line; the plane projections of the spinneret guide hole assembly A, the spinneret guide hole assembly B, and the spinneret plate (8) are in opposite directions on the melt composite circumference (11); the main projection angle α of the spinneret guide hole assembly A, the spinneret guide hole assembly B, and the spinneret plate (8) is 60°-120°, and the diameter of the melt composite circumference (11) is 1-2 times the diameter of the spinneret microhole; The first melt A and the second melt B are respectively introduced into the feed plate of the composite spinning assembly in a mass ratio of 4:6 to 6:4, enter the first melt A inlet and the second melt B inlet of the spinneret through their respective melt channels, and pass through their respective oblique spinneret guide holes, tapered holes and spinneret microholes, and finally compound at the melt compounding circumference; during compounding, the two melts are tangent to each other in opposite directions on the melt compounding circumference, and the intersecting part accounts for 1 / 4-3 / 4 of the total amount of the melts, and the obtained fiber is in a state of twisting and rotating in the axial direction; Step 3: The spun fiber obtained in step 2 is subjected to ring-blowing cooling and oiling in sequence, and is wound after adjusting the tension through a pair of guide wire discs to obtain pre-stretched twisted elastic fiber (POY), which is then stretched by a texturing machine to obtain a permanent twisted elastic fiber.

2. The method for preparing the twisted composite elastic fiber according to claim 1, characterized in that: The melt compounding circle (11) is arranged inside the spinneret (8) and is 0.2-0.5 mm away from the lower plane of the spinneret.

3. The method for preparing the twisted composite elastic fiber according to claim 1, characterized in that: The melt compounding circle (11) is arranged on the lower plane of the spinneret (8).

4. The method for preparing the twisted composite elastic fiber according to claim 1, characterized in that: The melt compounding circle (11) is arranged outside the spinneret (8) and is 0.2-0.5 mm away from the lower plane of the spinneret.

5. A twisted composite elastic fiber, characterized in that: The twisted composite elastic fiber is prepared by the preparation method according to any one of claims 1 to 4, and has a groove structure, and the width of the groove is 1 / 2-1 / 4 of the fiber diameter; the mass ratio of the first polyester fiber-forming polymer to the second polyester fiber-forming polymer is 1:1, and the viscosity difference between the first polyester fiber-forming polymer and the second polyester fiber-forming polymer is above 0.3dl / g.

6. An application of a twisted composite elastic fiber, characterized in that: The twisted composite elastic fiber described in claim 5 is applied to fabrics.

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