SIDE-BY-SIDE SELF-CRIMPING ELASTIC FIBER AND PREPARATION METHOD THEREFOR

Abstract

A type of side-by-side self-crimping elastic fiber and preparation method thereof are disclosed. The preparation method includes distributing compatible or partially compatible first fiber-forming polymer melts and second fiber-forming polymer melts, then the fiber is extruded from first spinneret holes and second spinneret holes on the same spinneret. The first fiber-forming polymer melts and the second fiber-forming polymer melts flow into the first spinneret holes through first and second distribution holes, and flow into the second spinneret holes through third and fourth distribution holes, wherein the four distribution holes are cylindrical holes of equal height, the ratio of the diameter of the first distribution holes to the diameter of the second distribution holes is (1.10-1.20):1, and the ratio of the diameter of the third distribution holes to the diameter of the fourth distribution holes is 1:(1.10-1.20).

Claims

1. A method for preparing a side-by-side self-crimping elastic fiber, comprising: distributing a first fiber-forming polymer melt and a second fiber-forming polymer melt according to a specific spinning process, then extracting from first spinneret holes and second spinneret holes on a same spinneret to obtain the side-by-side self-crimping elastic fiber; wherein a distribution is to distribute the first fiber-forming polymer melt through first distribution holes while distribute the second fiber-forming polymer melt through second distribution holes into the first spinneret holes, and distribute the first fiber-forming polymer melt through third distribution holes while distribute the second fiber-forming polymer melt through fourth distribution holes into the second spinneret holes; wherein the first fiber-forming polymer melt and the second fiber-forming polymer melt are compatible or partially compatible; at entrances of the first distribution holes, the second distribution holes, the third distribution holes, and the fourth distribution holes, wherein an apparent viscosity of the second fiber-forming polymer melt differs from an apparent viscosity of the first fiber-forming polymer melt by no more than 5%; wherein the first distribution holes and the second distribution holes are equally-high cylindrical holes with a diameter ratio of (1.10-1.20):1, and the third distribution holes and the fourth distribution holes are equally-high cylindrical holes with a diameter ratio of 1:(1.10-1.20); wherein the specific spinning process is a POY process, an FDY process, a POY-DTY process, or a POY-DT process, wherein the POY process, the FDY process, and the POY-DT process are followed by a relaxation heat treatment of the side-by-side self-crimping elastic fiber.

2. The method of claim 1, wherein a ratio of a mass of the second fiber-forming polymer melt to a mass of the first fiber-forming polymer melt is 50:50.

3. The method of claim 1, wherein each of the first spinneret holes or each of the second spinneret holes is a circular, oval, or “8”-shaped spinneret hole.

4. The method of claim 1, wherein all the first spinneret holes and the second spinneret holes are distributed in concentric circles, and the spinneret holes on a same circle are all the first spinneret holes or all the second spinneret holes.

5. The method of claim 1, wherein the first fiber-forming polymer melt and the second fiber-forming polymer melt are of same materials with different viscosities, or of different materials; wherein materials of the first fiber-forming polymer melt and the second fiber-forming polymer melt are selected from a polyester homopolymer, a polyester copolymer, a polyester modified product, a polyamide homopolymer, a polyamide copolymer, and a polyamide modified product.

6. The method of claim 1, wherein each of the first spinneret holes comprises a first guide hole, a first transition hole, and a first capillary micropore connected sequentially, each of the second spinneret holes comprises a second guide hole, a second transition hole, and a second capillary micropore connected sequentially, the first guide hole is connected with the first distribution holes and the second distribution holes at the same time, and the second guide hole is connected with the third distribution holes and the fourth distribution holes at the same time; wherein the first distribution holes, the second distribution holes, the third distribution holes, and the fourth distribution holes are located on a distribution plate in a third spinning box III, the second fiber-forming polymer melt is transported through a first spinning box to the second distribution holes and the fourth distribution holes, while the first fiber-forming polymer melt is transported through a second spinning box to the first distribution holes and the third distribution holes.

7. The method of claim 1, wherein the relaxation heat treatment has a temperature of 90-120° C., and a time of 20-30 min.

8. A side-by-side self-crimping elastic fiber prepared by the method of claim 1, comprising multiple second fiber-forming polymer/first fiber-forming polymer side-by-side composite monofilaments, and in a same bundle of fibers, wherein a first part of the second fiber-forming polymer/first fiber-forming polymer side-by-side composite monofilaments have a mass ratio of the first fiber-forming polymer melt to the second fiber-forming polymer melt of 3:2 to 2:1, and a second part of the second fiber-forming polymer/first fiber-forming polymer side-by-side composite monofilaments have a mass ratio of the first fiber-forming polymer melt to the second fiber-forming polymer melt of 2:3 to 1:2.

9. The side-by-side self-crimping elastic fiber of claim 8, wherein during a preparation of the side-by-side self-crimping elastic fiber, a ratio of a mass of the second fiber-forming polymer melt to a mass of the first fiber-forming polymer melt is 50:50.

10. The side-by-side self-crimping elastic fiber of claim 8, wherein each of the first spinneret holes or each of the second spinneret holes is a circular, oval, or “8”-shaped spinneret hole.

11. The side-by-side self-crimping elastic fiber of claim 8, wherein all the first spinneret holes and the second spinneret holes are distributed in concentric circles, and the spinneret holes on a same circle are all the first spinneret holes or all the second spinneret holes.

12. The side-by-side self-crimping elastic fiber of claim 8, wherein the first fiber-forming polymer melt and the second fiber-forming polymer melt are of same materials with different viscosities, or of different materials; wherein materials of the first fiber-forming polymer melt and the second fiber-forming polymer melt are selected from a polyester homopolymer, a polyester copolymer, a polyester modified product, a polyamide homopolymer, a polyamide copolymer, and a polyamide modified product.

13. The side-by-side self-crimping elastic fiber of claim 8, wherein each of the first spinneret holes comprises a first guide hole, a first transition hole, and a first capillary micropore connected sequentially, each of the second spinneret holes comprises a second guide hole, a second transition hole, and a second capillary micropore connected sequentially, the first guide hole is connected with the first distribution holes and the second distribution holes at the same time, and the second guide hole is connected with the third distribution holes and the fourth distribution holes at the same time; wherein the first distribution holes, the second distribution holes, the third distribution holes, and the fourth distribution holes are located on a distribution plate in a third spinning box III, the second fiber-forming polymer melt is transported through a first spinning box to the second distribution holes and the fourth distribution holes, while the first fiber-forming polymer melt is transported through a second spinning box to the first distribution holes and the third distribution holes.

14. The side-by-side self-crimping elastic fiber of claim 8, wherein the relaxation heat treatment has a temperature of 90-120° C., and a time of 20-30 min.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0035] FIGURE is a schematic diagram of the melt distribution of the present invention; wherein A, B, C and D are mutually independent distribution holes, and E and F are mutually independent guide holes.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Based on above mentioned method, the following embodiments are carried out for further demonstration in the present invention. It is to be understood that these embodiments are only intended to illustrate the invention and are not intended to limit the scope of the invention. In addition, it should be understood that after reading the contents described in the present invention, those technical personnel in this field can make various changes or modifications to the invention, and these equivalent forms also fall within the scope of the claims attached to the application.

[0037] The crimp shrinkage and crimp stability in the present invention are obtained by testing the tow by using GB6506-2001 “Synthetic fiber-Test method for crimp contraction properties of textured filament yarns”;

[0038] The text methods of the shrinkage elongation (reflecting the degree of elasticity and crimp of textured filament yarns, wherein the fibers are subjected to a light load and then to a heavy load, and the ratio of the difference in length to the curl length is calculated for both loads) and the crimp elastic recovery rate are as follows:

[0039] Firstly, cut two fiber samples of about 50 cm in length, put them into 100° C. hot water for 30 minutes, take them out and dry them naturally, next intercept a sample of about 30 cm in length, wherein fix one end and load another end with a load of 0.0018 cN/dtex for 30 seconds, and mark it at 20 cm, that is, the initial length li of the sample; then load another end with a load of 0.09 cN/dtex for 30 seconds, and measure the position of the marked point, which is the length l.sub.2 of the sample under heavier load; finally remove the load and let the sample retract for 2 minutes, next add a load of 0.0018 cN/dtex for 30 seconds and measure the position of the marked point, which is the recovery length 13; the shrinkage elongation (CE) and the crimp elastic recovery rate (SR) are calculated as follows:

CE=(l.sub.2−l.sub.1)/l.sub.1;

SR=(l.sub.2−l.sub.3)/(l.sub.2−l.sub.1).

Example 1

[0040] A method for preparing a side-by-side self-crimping elastic fiber, according to an FDY process, wherein a PET melt (intrinsic viscosity of 0.6 dL/g) and a PA6 melt (intrinsic viscosity of 2.2 dL/g) in a mass ratio of 50:50 are distributed and extruded from circular spinneret holes m and circular spinneret holes n on the same spinneret to obtain a fully drawn yarn, wherein the side-by-side self-crimping elastic fiber is prepared after the relaxation heat treatment;

[0041] wherein the PA6 melt and the PET melt each contains 5wt % of the PET-PA6 copolymer melt; wherein the preparation process of the PET-PA6 copolymer is as follows: the PET with a number average molecular weight of 2000 and the PA6 with a number average molecular weight of 2000 are mixed at a mass ratio of 1:1, then carrying out the polycondensation reaction at a temperature of 273° C. and a vacuum degree of 45 Pa for 60 min;

[0042] wherein the distribution is to distribute the PA6 melt through distribution holes A while distribute the PET melt through distribution holes B into spinneret holes m; and distribute the PA6 melt through distribution holes C while distribute the PET melt through distribution holes D into spinneret holes n; at the entrance of distribution holes A, B, C and D, wherein the apparent viscosity of the PET melt differs from that of the PA6 melt by 5%;

[0043] wherein the distribution holes A and B are equally-high cylindrical holes with a diameter ratio of 1.10:1, and the distribution holes C and D are equally-high cylindrical holes with a diameter ratio of 1:1.10;

[0044] wherein all the spinneret holes are distributed in concentric circles, and the spinneret holes on the same circle are all m or all n;

[0045] as shown in the figure, wherein the spinneret hole m comprises a guide hole E, a transition hole and a capillary micropore connected sequentially, the spinneret hole n comprises a guide hole F, a transition hole and a capillary micropore connected sequentially, the guide hole E is connected with a distribution hole A and a distribution hole B at the same time, and the guide hole F is connected with a distribution hole C and a distribution hole D at the same time; wherein the distribution holes A, B, C and D are located on the distribution plate in the spinning box III, the PET melt is transported through a spinning box I to the distribution hole B and the distribution hole D, while the PA6 melt is transported through a spinning box II to the distribution hole A and the distribution hole C;

[0046] wherein the temperature of the spinning box I is 285° C., the temperature of the spinning box II is 270° C., and the temperature of the spinning box III is 282° C.;

[0047] wherein the FDY process involves technological parameters: a cooling temperature of 25° C., an interlacing pressure of 0.2 MPa, a godet roller 1 speed of 1600 m/min, a godet roller 1 temperature of 80° C., a godet roller 2 speed of 2760 m/min, a godet roller 2 temperature of 140 ° C., and a winding speed of 2710 m/min; wherein the relaxation heat treatment has a temperature of 104° C., and a time of 30 minutes;

[0048] wherein the prepared side-by-side self-crimping elastic fiber is composed of multiple PA6/PET side-by-side composite monofilaments; wherein the monofilament crimping directions of the side-by-side self-crimping elastic fiber are randomly distributed; wherein the side-by-side self-crimping elastic fiber comprises mechanical performance indices: a crimp shrinkage of 52%, a crimp stability of 80%, a shrinkage elongation of 88%, a crimp elastic recovery rate of 93%, a breaking strength of ≥2.5 cN/dtex, an elongation at break of 50.5%, and a total fineness of 100 dtex.

[0049] The prepared side-by-side self-crimping elastic fiber is made into the knitted fabric, which is tested for strip unevenness, and the test result is that the D value of the knitted fabric made of the side-by-side self-crimping elastic fiber is 0.57%; this indicates that the prepared side-by-side self-crimping elastic fiber in the present invention does not have the problem of “stripe unevenness”.

Example 2

[0050] A method for preparing a side-by-side self-crimping elastic fiber, according to an FDY process, wherein a PET melt (intrinsic viscosity of 0.63 dL/g) and a PA6 melt (intrinsic viscosity of 2 dL/g) in a mass ratio of 50:50 are distributed and extruded from oval spinneret holes m and “8”-shaped spinneret holes n on the same spinneret to obtain a fully drawn yarn, wherein the side-by-side self-crimping elastic fiber is prepared after the relaxation heat treatment;

[0051] wherein the PA6 melt and the PET melt each contains 5wt % of the PET-PA6 copolymer melt; wherein the preparation process of the PET-PA6 copolymer is as follows: the PET with a number average molecular weight of 2500 and the PA6 with a number average molecular weight of 2500 are mixed at a mass ratio of 1:1, then carrying out the polycondensation reaction at a temperature of 275° C. and a vacuum degree of 45 Pa for 55 min;

[0052] wherein the distribution is to distribute the PA6 melt through distribution holes A while distribute the PET melt through distribution holes B into spinneret holes m; and distribute the PA6 melt through distribution holes C while distribute the PET melt through distribution holes D into spinneret holes n; at the entrance of distribution holes A, B, C and D, wherein the apparent viscosity of the PET melt differs from that of the PA6 melt by 2.8%;

[0053] wherein the distribution holes A and B are equally-high cylindrical holes with a diameter ratio of 1.18:1, and the distribution holes C and D are equally-high cylindrical holes with a diameter ratio of 1:1.18;

[0054] wherein all the spinneret holes are distributed in concentric circles, and the spinneret holes on the same circle are all m or all n;

[0055] wherein the spinneret hole m comprises a guide hole E, a transition hole and a capillary micropore connected sequentially, the spinneret hole n comprises a guide hole F, a transition hole and a capillary micropore connected sequentially, the guide hole E is connected with a distribution hole A and a distribution hole B at the same time, and the guide hole F is connected with a distribution hole C and a distribution hole D at the same time; wherein the distribution holes A, B, C and D are located on the distribution plate in the spinning box III, the PET melt is transported through a spinning box Ito the distribution hole B and the distribution hole D, while the PA6 melt is transported through a spinning box II to the distribution hole A and the distribution hole C;

[0056] wherein the temperature of the spinning box I is 283° C., the temperature of the spinning box II is 265° C., and the temperature of the spinning box III is 282° C.;

[0057] wherein the FDY process involves technological parameters: a cooling temperature of 23° C., an interlacing pressure of 0.24 MPa, a godet roller 1 speed of 1550 m/min, a godet roller 1 temperature of 80° C., a godet roller 2 speed of 2800 m/min, a godet roller 2 temperature of 144 ° C., and a winding speed of 2670 m/min; wherein the relaxation heat treatment has a temperature of 90° C., and a time of 24 minutes;

[0058] wherein the prepared side-by-side self-crimping elastic fiber is composed of multiple PA6/PET side-by-side composite monofilaments; wherein the monofilament crimping directions of the side-by-side self-crimping elastic fiber are randomly distributed; wherein the side-by-side self-crimping elastic fiber comprises mechanical performance indices: a crimp shrinkage of 51.5%, a crimp stability of 77.3%, a shrinkage elongation of 87.9%, a crimp elastic recovery rate of 92.8%, a breaking strength of ≥2.5 cN/dtex, an elongation at break of 57%, and a total fineness of 95 dtex.

[0059] The prepared side-by-side self-crimping elastic fiber is made into the knitted fabric, which is tested for strip unevenness, and the test result is that the D value of the knitted fabric made of the side-by-side self-crimping elastic fiber is 0.24%; this indicates that the prepared side-by-side self-crimping elastic fiber in the present invention does not have the problem of “stripe unevenness”.

Example 3

[0060] A method for preparing a side-by-side self-crimping elastic fiber, according to a POY-DT process, wherein a PET melt (intrinsic viscosity of 0.55 dL/g) and a PBT melt (intrinsic viscosity of 1.1 dL/g) in a mass ratio of 50:50 are distributed and extruded from circular spinneret holes m and oval spinneret holes n on the same spinneret to obtain a POY-DT yarn, wherein the side-by-side self-crimping elastic fiber is prepared after the relaxation heat treatment;

[0061] wherein the distribution is to distribute the PBT melt through distribution holes A while distribute the PET melt through distribution holes B into spinneret holes m; and distribute the PBT melt through distribution holes C while distribute the PET melt through distribution holes D into spinneret holes n; at the entrance of distribution holes A, B, C and D, wherein the apparent viscosity of the PET melt differs from that of the PBT melt by 4.9%;

[0062] wherein the distribution holes A and B are equally-high cylindrical holes with a diameter ratio of 1.15:1, and the distribution holes C and D are equally-high cylindrical holes with a diameter ratio of 1:1.15;

[0063] wherein all the spinneret holes are distributed in concentric circles, and the spinneret holes on the same circle are all m or all n;

[0064] wherein the spinneret hole m comprises a guide hole E, a transition hole and a capillary micropore connected sequentially, the spinneret hole n comprises a guide hole F, a transition hole and a capillary micropore connected sequentially, the guide hole E is connected with a distribution hole A and a distribution hole B at the same time, and the guide hole F is connected with a distribution hole C and a distribution hole D at the same time; wherein the distribution holes A, B, C and D are located on the distribution plate in the spinning box III, the PET melt is transported through a spinning box Ito the distribution hole B and the distribution hole D, while the PBT melt is transported through a spinning box II to the distribution hole A and the distribution hole C;

[0065] wherein the temperature of the spinning box I is 280° C., the temperature of the spinning box II is 260° C., and the temperature of the spinning box III is 276° C.;

[0066] wherein the POY-DT process involves technological parameters: a cooling temperature of 23° C., a winding speed of 2800 m/min, a setting temperature of 133° C., a stretching temperature of 95° C., and a stretching multiplier of 1.8;

[0067] wherein the relaxation heat treatment has a temperature of 90° C., and a time of 30 minutes;

[0068] wherein the prepared side-by-side self-crimping elastic fiber is composed of multiple PBT/PET side-by-side composite monofilaments; wherein the monofilament crimping directions of the side-by-side self-crimping elastic fiber are randomly distributed; wherein the side-by-side self-crimping elastic fiber comprises mechanical performance indices: a crimp shrinkage of 66%, a crimp stability of 92.3%, a shrinkage elongation of 114%, a crimp elastic recovery rate of 80%, a breaking strength of 3.07 cN/dtex, an elongation at break of 47%, and a total fineness of 80 dtex.

Example 4

[0069] A method for preparing a side-by-side self-crimping elastic fiber, according to a POY process, wherein a PTT melt (intrinsic viscosity of 0.9 dL/g) and a PBT melt (intrinsic viscosity of 1.21 dL/g) in a mass ratio of 50:50 are distributed and extruded from circular spinneret holes m and circular spinneret holes n on the same spinneret to obtain the side-by-side self-crimping elastic fiber;

[0070] wherein the distribution is to distribute the PBT melt through distribution holes A while distribute the PTT melt through distribution holes B into spinneret holes m; and distribute the PBT melt through distribution holes C while distribute the PTT melt through distribution holes D into spinneret holes n; at the entrance of distribution holes A, B, C and D, wherein the apparent viscosity of the PTT melt differs from that of the PBT melt by 5%;

[0071] wherein the distribution holes A and B are equally-high cylindrical holes with a diameter ratio of 1.1:1, and the distribution holes C and D are equally-high cylindrical holes with a diameter ratio of 1:1.1;

[0072] wherein the spinneret hole m comprises a guide hole E, a transition hole and a capillary micropore connected sequentially, the spinneret hole n comprises a guide hole F, a transition hole and a capillary micropore connected sequentially, the guide hole E is connected with a distribution hole A and a distribution hole B at the same time, and the guide hole F is connected with a distribution hole C and a distribution hole D at the same time; wherein the distribution holes A, B, C and D are located on the distribution plate in the spinning box III, the PTT melt is transported through a spinning box Ito the distribution hole B and the distribution hole D, while the PBT melt is transported through a spinning box II to the distribution hole A and the distribution hole C;

[0073] wherein the temperature of the spinning box I is 255° C., the temperature of the spinning box II is 266° C., and the temperature of the spinning box III is 265° C.;

[0074] wherein all the spinneret holes are distributed in concentric circles, and the spinneret holes on the same circle are all m or all n;

[0075] wherein the POY process involves technological parameters: a cooling temperature of 24° C., and a winding speed of 2660 m/min;

[0076] wherein the prepared side-by-side self-crimping elastic fiber is composed of multiple PBT/PTT side-by-side composite monofilaments; wherein the monofilament crimping directions of the DT yarn made from side-by-side self-crimping elastic fiber are randomly distributed; wherein the side-by-side self-crimping elastic fiber comprises mechanical performance indices: a crimp shrinkage of 70%, a crimp stability of 93.3%, a shrinkage elongation of 113%, a crimp elastic recovery rate of 85%, a breaking strength of 2.29 cN/dtex, an elongation at break of 125%, a monofilament fineness of 0.5dtex, and a total fineness of 110 dtex.

Example 5

[0077] A method for preparing a side-by-side self-crimping elastic fiber, according to a POY-DT process, wherein a PET melt (intrinsic viscosity of 0.52 dL/g) and a PBT melt (intrinsic viscosity of 1.14 dL/g) in a mass ratio of 50:50 are distributed and extruded from circular spinneret holes m and circular spinneret holes n on the same spinneret to obtain a POY-DT yarn, wherein the side-by-side self-crimping elastic fiber is prepared after the relaxation heat treatment;

[0078] wherein the distribution is to distribute the PBT melt through distribution holes A while distribute the PET melt through distribution holes B into spinneret holes m; and distribute the PBT melt through distribution holes C while distribute the PET melt through distribution holes D into spinneret holes n; at the entrance of distribution holes A, B, C and D, wherein the apparent viscosity of the PET melt differs from that of the PBT melt by 5%;

[0079] wherein the distribution holes A and B are equally-high cylindrical holes with a diameter ratio of 1.17:1, and the distribution holes C and D are equally-high cylindrical holes with a diameter ratio of 1:1.17;

[0080] wherein all the spinneret holes are distributed in concentric circles, and the spinneret holes on the same circle are all m or all n;

[0081] wherein the spinneret hole m comprises a guide hole E, a transition hole and a capillary micropore connected sequentially, the spinneret hole n comprises a guide hole F, a transition hole and a capillary micropore connected sequentially, the guide hole E is connected with a distribution hole A and a distribution hole B at the same time, and the guide hole F is connected with a distribution hole C and a distribution hole D at the same time; wherein the distribution holes A, B, C and D are located on the distribution plate in the spinning box III, the PET melt is transported through a spinning box Ito the distribution hole B and the distribution hole D, while the PBT melt is transported through a spinning box II to the distribution hole A and the distribution hole C;

[0082] wherein the temperature of the spinning box I is 279° C., the temperature of the spinning box II is 261° C., and the temperature of the spinning box III is 277° C.;

[0083] wherein the POY-DT process involves technological parameters: a cooling temperature of 25° C., a winding speed of 3100 m/min, a setting temperature of 134° C., a stretching temperature of 89° C., and a stretching multiplier of 1.7;

[0084] wherein the relaxation heat treatment has a temperature of 98° C., and a time of 27 minutes;

[0085] wherein the prepared side-by-side self-crimping elastic fiber is composed of multiple PBT/PET side-by-side composite monofilaments; wherein the monofilament crimping directions of the side-by-side self-crimping elastic fiber are randomly distributed; wherein the side-by-side self-crimping elastic fiber comprises mechanical performance indices: a crimp shrinkage of 67%, a crimp stability of 92.6%, a shrinkage elongation of 114%, a crimp elastic recovery rate of 80%, a breaking strength of 3.02 cN/dtex, an elongation at break of 51%, and a total fineness of 140 dtex.

Example 6

[0086] A method for preparing a side-by-side self-crimping elastic fiber, according to a POY-DT process, wherein a PET melt (intrinsic viscosity of 0.51 dL/g) and a PBT melt (intrinsic viscosity of 1.14 dL/g) in a mass ratio of 50:50 are distributed and extruded from circular spinneret holes m and circular spinneret holes n on the same spinneret to obtain a POY-DT yarn, wherein the side-by-side self-crimping elastic fiber is prepared after the relaxation heat treatment;

[0087] wherein the distribution is to distribute the PBT melt through distribution holes A while distribute the PET melt through distribution holes B into spinneret holes m; and distribute the PBT melt through distribution holes C while distribute the PET melt through distribution holes D into spinneret holes n; at the entrance of distribution holes A, B, C and D, wherein the apparent viscosity of the PET melt differs from that of the PBT melt by 4.4%;

[0088] wherein the distribution holes A and B are equally-high cylindrical holes with a diameter ratio of 1.18:1, and the distribution holes C and D are equally-high cylindrical holes with a diameter ratio of 1:1.18;

[0089] wherein all the spinneret holes are distributed in concentric circles, and the spinneret holes on the same circle are all m or all n;

[0090] wherein the spinneret hole m comprises a guide hole E, a transition hole and a capillary micropore connected sequentially, the spinneret hole n comprises a guide hole F, a transition hole and a capillary micropore connected sequentially, the guide hole E is connected with a distribution hole A and a distribution hole B at the same time, and the guide hole F is connected with a distribution hole C and a distribution hole D at the same time; wherein the distribution holes A, B, C and D are located on the distribution plate in the spinning box III, the PET melt is transported through a spinning box Ito the distribution hole B and the distribution hole D, while the PBT melt is transported through a spinning box II to the distribution hole A and the distribution hole C;

[0091] wherein the temperature of the spinning box I is 279° C., the temperature of the spinning box II is 260° C., and the temperature of the spinning box III is 274° C.;

[0092] wherein the POY-DT process involves technological parameters: a cooling temperature of 25° C., a winding speed of 2840 m/min, a setting temperature of 135° C., a stretching temperature of 95° C., and a stretching multiplier of 1.7;

[0093] wherein the relaxation heat treatment has a temperature of 101° C., and a time of 26 minutes;

[0094] wherein the prepared side-by-side self-crimping elastic fiber is composed of multiple PBT/PET side-by-side composite monofilaments; wherein the monofilament crimping directions of the side-by-side self-crimping elastic fiber are randomly distributed; wherein the side-by-side self-crimping elastic fiber comprises mechanical performance indices: a crimp shrinkage of 68%, a crimp stability of 92.9%, a shrinkage elongation of 115%, a crimp elastic recovery rate of 82%, a breaking strength of 3.04 cN/dtex, an elongation at break of 49%, and a total fineness of 90 dtex.