High-resilience modified pet polyester fiber and preparation method therefor

Abstract

A method for preparing high-resilience modified PET polyester fibers. The method comprises the following steps: mixing PET polyester fibers, a cross-linking agent and an auxiliary agent to obtain a mixture; and melting and spinning the mixture to obtain the modified PET polyester fibers. The PET polyester fibers are subjected to melt extrusion modification by introducing the cross-linking agent, and modified PET polyester fiber filaments with a hollow and spiral structure, high resilience and controllable elasticity are formed. The modified PET polyester fibers can be obtained using inexpensive and readily available PET polyester fibers, which is economical and does not require complex processing.

Description

Highly resilient modified PET polyester fiber and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of polyester fiber preparation, in particular to a modified PET polyester fiber with high resilience and a preparation method thereof. Background Art

[0002] Elastic fiber fabrics typically offer excellent shape retention and wrinkle resistance, making them comfortable to wear and popular with consumers. Spandex, a classic and traditional stretch fiber filament, is widely used in clothing fabrics due to its excellent elasticity, primarily in the manufacture of tights, sportswear, jockstraps, and shoe soles. However, it has been criticized for its difficulty in coloring, complex processing, dimensional instability resulting from its high elasticity, and aging due to long-term light exposure.

[0003] To address these issues, new mechanically elastic composite fibers have emerged in recent years, with T400 and T800 fabrics being the most representative. T400 is a composite of PET (ethylene terephthalate) and PTT (propylene terephthalate). T400 boasts a high resilience rate, exceeding 95% after 500 repeated stretches. Its excellent moisture-wicking properties have made it a highly sought-after material upon its release. Its core raw material, PTT, was originally developed by DuPont. One of the polymer monomers, PTT, is converted from corn sugar into glycerol through a green process. While this bio-based, non-petrochemical-based raw material is environmentally friendly, the high-temperature polycondensation with terephthalic acid to form PTT fiber presents significant production challenges. T800 fabric is a composite of PET (polyethylene terephthalate) and PBT (butylene terephthalate). The PBT polymer's microstructure is a double helix, resulting in greater elasticity and a superior cotton feel. The PBT fiber polymerization process is more mature than that of PPT fiber. When the T400 market was in tight supply and demand, T800 fabric, due to its lower price and softer feel, gradually gained market acceptance.

[0004] As the PET polyester fiber of producing one of T400, T800 composite fiber fabric, then be formed by ethylene glycol and terephthalic acid polycondensation, be that thermal stability is the highest in PET, PTT, three kinds of synthetic polyester fibers of PBT, melting point and decomposition temperature height, strength loss is few under high temperature, in 150 ° of air, long-time heating does not change color, intensity decline is only 15-30%, and other fiber PTT, PBT then stability is slightly low, therefore may there is thermal stability problem during with PET blending thermal processing.In addition, the softening point temperature of PET fiber is very high 230-240 ℃, and the dyeing and finishing setting temperature made is higher, usually dyeing under 130 ℃ of high temperature, and PTT, PBT fibers then only need lesser temps 110 ℃ or so, cause T400, T800 composite fiber dyeing temperature window less, to improving setting effect very unfavorable.In addition, because PTT, PBT fiber price height, composite fiber processing technology complexity, limited the development of T400, T800 fabric. Summary of the Invention

[0005] In view of the above-mentioned shortcomings, the present invention provides a modified PET polyester fiber with high resilience and a preparation method thereof. By introducing a cross-linking agent to melt-extrude and modify the PET polyester fiber, a modified PET fiber filament with high resilience and controllable elasticity having a hollow, spiral structure is formed.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a modified PET polyester fiber with high resilience comprises the following steps:

[0008] mixing PET polyester fiber, a cross-linking agent and an auxiliary agent to obtain a mixture;

[0009] The mixture is melted and spun to obtain modified PET polyester fibers.

[0010] According to one aspect of the present invention, the cross-linking agent comprises a small molecule heterocyclic compound A with a meta heterocyclic structure and / or a small molecule heterocyclic compound B with a para heterocyclic structure, and the chemical structure of the small molecule heterocyclic compound A with a meta heterocyclic structure is:

[0011] The chemical structural formula of the small molecule heterocyclic compound B of the para-heterocyclic structure is , wherein R is a mono-, di- or tri-substituted substituent on the benzene ring.

[0012] According to one aspect of the present invention, the substituent is a saturated fatty short carbon chain CnH2n+1, where n is 0-5.

[0013] According to one aspect of the present invention, the substituent is an organic functional group or a polar functional group.

[0014] According to one aspect of the present invention, the total weight percentage of the small molecule heterocyclic compound A with a meta-heterocyclic structure and the small molecule heterocyclic compound B with a para-heterocyclic structure is 0.1-1%.

[0015] According to one aspect of the present invention, the PET polyester fiber has a viscosity of 0.70-1.60 dl / g and a terminal hydroxyl group of 15-40 mol / t.

[0016] According to one aspect of the present invention, the auxiliary agent includes any one or a combination of an antioxidant, a matting agent, and a primary tackifier.

[0017] According to one aspect of the present invention, the primary tackifier is any one or a combination of anhydride, epoxy, and pentaerythritol.

[0018] According to one aspect of the present invention, the matting agent is titanium dioxide.

[0019] According to one aspect of the present invention, the antioxidant is 1076 or a phosphate antioxidant.

[0020] According to one aspect of the present invention, the antioxidant is added in an amount of 0.1-0.5%.

[0021] According to one aspect of the present invention, the melting and spinning process includes plasticizing raw material particles through a twin-screw extruder to induce a cross-linking reaction, melting the raw material, feeding it into a spinning area, and then feeding it into a spinning assembly in a fixed quantity through a spinning pump. After filtering, the raw material is extruded and formed through a spinneret. The spinneret has four holes and a diameter of 0.12 mm.

[0022] According to one aspect of the present invention, the feed port temperature of the twin-screw extruder is set to 260-300°C.

[0023] According to one aspect of the present invention, the extrusion molding further includes cooling, stretching, and winding.

[0024] Advantages of the present invention: A method for preparing a modified PET polyester fiber with high resilience, wherein the PET polyester fiber is melt-extruded and modified by introducing a small molecule polyester cross-linking agent, and the ratio of a small molecule heterocyclic compound A with a meta-heterocyclic structure and a small molecule heterocyclic compound B with a para-heterocyclic structure is adjusted to simulate the composite fiber molding of PET and PTT, thereby forming a highly elastic and elastically controllable modified PET fiber filament with a hollow, spiral structure, which is easy to wash and quick to dry. Due to the addition of amide bonds and the cavity formed by the entanglement of the fiber microstructure, the sweat absorption and dyeing ability of the modified PET fiber are simultaneously improved. Compared with T400 fiber and T800 fiber, the modified PET polyester fiber of the present invention uses cheap and readily available PET polyester chips, does not require complex processes, and is economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] FIG1 is a schematic structural diagram of the modified PET polyester fiber with high resilience according to the present invention;

[0027] FIG2 is a graph showing the test data of samples of Examples 1-8 of the present invention through a universal tensile testing machine;

[0028] FIG3 is an infrared spectrum test diagram of samples of Examples 1-8 of the present invention;

[0029] FIG4 is a DSC graph of the sample of Example 1 of the present invention;

[0030] Figure 5 is the H-NMR spectrum and C-NMR spectrum of the small molecule heterocyclic compound A with a meta-heterocyclic structure;

[0031] Figure 6 shows the H-NMR spectrum and C-NMR spectrum of the small molecule heterocyclic compound B with a para-heterocyclic structure. Implementation Method

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] A method for preparing a modified PET polyester fiber with high resilience comprises the following steps:

[0034] Raw material preparation: PET polyester fiber chips, antioxidant, main viscosity enhancer, cross-linking agent, etc. are weighed and mixed in a certain proportion using a vector scale, crushed into fine powder using a grinder, mixed thoroughly according to the proportion, and dried in a vacuum oven to a moisture content of 100 ppm before use.

[0035] Melting: The dried PET mixed formula is fed into a twin-screw extruder with the feed port set at 280°C. It is rapidly mixed and plasticized under high temperature and high pressure conditions, causing a cross-linking reaction. After melting in the twin-screw extruder, it is fed into the spinning part.

[0036] Filtration: The melt passes through a filter to remove impurities.

[0037] Stabilization: The temperature is set to 260°C, and the melt pump stably provides a certain melt flow rate and pressure.

[0038] Spinning: The molten modified PET is quantitatively fed into the spinning assembly through a spinning pump and extruded through the micropores in the stainless spinneret nozzle, with 4 holes and a diameter of 0.12 mm, to form filaments.

[0039] Cooling: The fibers pass through a cooling chamber to rapidly cool and solidify.

[0040] Drafting: The drawing device is used to stretch the fiber to adjust its diameter and physical properties.

[0041] Winding: The drawn PET fiber is wound onto a reel, ready for subsequent processing or product manufacturing.

[0042] In practical applications, the cross-linking agent includes a small molecule heterocyclic compound A with a meta-heterocyclic structure and / or a small molecule heterocyclic compound B with a para-heterocyclic structure. The chemical structure of the small molecule heterocyclic compound A with a meta-heterocyclic structure is: The chemical structural formula of the small molecule heterocyclic compound B of the para-heterocyclic structure is , wherein R is a mono-, di- or tri-substituted substituent on the benzene ring.

[0043] Specifically, R can be a short saturated fatty carbon chain, CnH2n+1, where n is 0-5. R can be a simple organic functional group, such as a halogen atom, such as F, Cl, Br, or I. R can also be a polar functional group, such as -OH, -NH2, -SO3, or -CN. The H NMR spectra and C NMR spectra of small molecule heterocyclic compound A with a meta-heterocyclic structure and small molecule heterocyclic compound B with a para-heterocyclic structure are shown in Figures 5 and 6, respectively.

[0044] In practical applications, the total weight percentage of the meta-heterocyclic small molecule heterocyclic compound A and the para-heterocyclic small molecule heterocyclic compound B is 0.1-1%. Preferably, the total weight percentage of the meta-heterocyclic small molecule heterocyclic compound A and the para-heterocyclic small molecule heterocyclic compound B is 0.4-0.8%. At high temperatures, the crosslinking agent can quickly chemically react with the carboxyl groups of the PET polyester fiber, thereby achieving chemical crosslinking. The reaction process is as follows:

[0045]

[0046] Specifically, after the PET polyester fiber is modified by the small molecule heterocyclic compound A with a meta-heterocyclic structure, the microstructure of the obtained PET fiber polymer (1) is a curved, coiled molecular structure, similar to the helical coiled polymer molecule of PTT. The PET polyester fiber is modified by the small molecule heterocyclic compound B with a para-heterocyclic structure to obtain a thickened PET linear fiber (2), which can also increase the crystallinity and rigidity. The modified PET also introduces an amide bond, which not only increases the rebound rate, but also increases the shear strength of the fiber due to the formation of hydrogen bonds with adjacent PET linear fibers (2). The PET fiber polymer (1) and the PET linear fibers (2) are spun into a high-rebound modified PET polyester fiber with a helical structure, the structural schematic of which is shown in Figure 1.

[0047] The highly elastic spun PET fiber has a moisture absorption rate of 0.4-0.8%, resulting in virtually identical dry and wet strength, easy washing, and quick drying. The addition of amide bonds and the cavities formed by the entangled fiber microstructure enhance both the moisture absorption and dyeing properties of the modified PET fiber. my country ranks first in the world in PET polyester fiber production, offering stable product quality and a relatively low price. PET polyester fiber exhibits excellent heat-setting properties, excellent heat and light resistance, and stable shape under a wide range of operating conditions. The preparation method of the present invention does not require complex processing, resulting in high economic efficiency.

[0048] In practical applications, the viscosity of the PET polyester fiber is 0.70-1.60 dl / g, and the terminal hydroxyl group is 15-40 mol / t. Preferably, the viscosity of the PET polyester fiber is 0.86-1.40 dl / g, and the terminal hydroxyl group is 18-22 mol / t.

[0049] In practical applications, the auxiliary agent includes any one or a combination of an antioxidant, a matting agent, and a primary viscosity enhancer. Specifically, the primary viscosity enhancer is any one or a combination of an acid anhydride, epoxy, and pentaerythritol. The matting agent is titanium dioxide.

[0050] In practical applications, the antioxidant is 1076 or a phosphate antioxidant, and the added amount of the antioxidant is 0.1-0.5%. Example 1

[0051] 99.2 parts of PET micropowder, with an intrinsic viscosity of 0.86 dl / g and a terminal carboxyl content of 18 mol / t, 0.1 parts of antioxidant 1076, 0.3 parts of pyromellitic anhydride, and 0.4 parts of a small molecule heterocyclic compound A with a meta-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The spinning time from feeding to filament formation was 20 minutes. Example 2

[0052] 99.0 parts of PET micropowder with an intrinsic viscosity of 0.86 dl / g and a terminal carboxyl content of 18 mol / t, 0.1 parts of antioxidant 1076, 0.2 parts of pyromellitic anhydride, 0.2 parts of epoxy tackifier 1820ACPET produced by DuPont, and 0.5 parts of a small molecule heterocyclic compound A with a meta-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The spinning time from feeding to filament formation was 20 minutes. Example 3

[0053] 99.0 parts of PET micropowder with an intrinsic viscosity of 0.86 dl / g and a terminal carboxyl content of 18 mol / t, 0.1 parts of antioxidant 1076, 0.2 parts of pyromellitic anhydride, 0.2 parts of epoxy tackifier 1820ACPET produced by DuPont, and 0.5 parts of a small molecule heterocyclic compound A with a meta-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The spinning time from feeding to filament formation was 10 minutes. Example 4

[0054] 99.0 parts of PET micropowder with an intrinsic viscosity of 0.86 dl / g and a terminal carboxyl content of 18 mol / t, 0.1 parts of antioxidant 1076, 0.2 parts of pyromellitic anhydride, 0.2 parts of epoxy tackifier 1820ACPET produced by DuPont, and 0.5 parts of a small molecule heterocyclic compound A with a meta-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The spinning time from feeding to filament formation was 5 minutes. Example 5

[0055] 99.5 parts of PET micropowder with an intrinsic viscosity of 1.2 dl / g and a terminal carboxyl content of 35 mol / t, 0.1 parts of antioxidant 1076, and 0.4 parts of a small molecule heterocyclic compound A with a meta-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The duration from feeding to filament formation was 20 minutes. Example 6

[0056] 99.0 parts of PET micropowder, with an intrinsic viscosity of 0.86 dl / g and a terminal carboxyl content of 18 mol / t, 0.1 parts of antioxidant 1076, 0.2 parts of pyromellitic anhydride, 0.2 parts of epoxy tackifier 1820ACPET produced by DuPont, 0.4 parts of small molecule heterocyclic compound A with a meta-heterocyclic structure, and 0.1 parts of small molecule heterocyclic compound B with a para-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The duration from feeding to filament formation was 20 minutes. Example 7

[0057] 99.0 parts of PET micropowder with an intrinsic viscosity of 0.86 dl / g and a terminal carboxyl content of 18 mol / t, 0.1 parts of antioxidant 1076, 0.2 parts of pyromellitic anhydride, 0.2 parts of epoxy tackifier 1820ACPET produced by DuPont, and 0.5 parts of a small molecule heterocyclic compound A with a meta-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The spinning time from feeding to filament formation was 25 minutes. Example 8

[0058] 89.9 parts of PET micropowder, with an intrinsic viscosity of 0.86 dl / g and a terminal carboxyl content of 18 mol / t, 0.1 parts of antioxidant 1076, 0.2 parts of pyromellitic anhydride, 0.2 parts of epoxy tackifier 1820ACPET produced by DuPont, 0.4 parts of small molecule heterocyclic compound A with a meta-heterocyclic structure, and 0.2 parts of small molecule heterocyclic compound B with a para-heterocyclic structure were thoroughly stirred and mixed, and then fed into a melt-spinning test machine for spinning. The duration from feeding to filament formation was 20 minutes.

[0059] The modified PET polyester fibers with high resilience prepared in Examples 1 to 8 were labeled Ep-1, Ep-2, Ep-3, Ep-4, Ep-5, Ep-6, Ep-7, and Ep-8, respectively, and then subjected to IV and other tests.

[0060] IV testing:

[0061] Ep-1, Ep-2, Ep-3, Ep-4, Ep-5, Ep-6, Ep-7, and Ep-8 were subjected to IV testing. The results are shown in Table 1:

[0062] Table 1

[0063] As shown in Table 1, the introduction of a crosslinking agent, melt extrusion modification of PET fibers, and subsequent composite fiber formation can increase the IV value of the modified PET fibers and effectively alter their viscosity. This, in turn, helps improve the durability and stability of the modified PET fibers, making them less susceptible to environmental factors such as UV rays and humidity. Furthermore, the modified PET fibers possess excellent moisture absorption and breathability, resulting in a longer service life and more stable performance.

[0064] Staining experiment:

[0065] The dyeing transition temperatures of samples Ep-6-8 are 75-85°C, approximately 5°C lower than those of PET fibers. The critical dyeing temperatures (dyeing temperatures at 10% and 90% relative dye uptake) for low-temperature disperse dyes are 80-115°C, and for high-temperature disperse dyes, 85-130°C. The optimal dyeing temperatures are 125°C for low-temperature disperse dyes and 130°C for high-temperature disperse dyes. Compared to dyeing with ordinary PET filament, the color yield is 30%-50% higher. Reduction cleaning can be performed during the dyeing process with 2g / L soda ash and 0.25g / L thiourea oxide at 80°C for 10 minutes to improve color fastness, achieving color fastness ratings above Grade 4. This indicates that the dyeing ability of modified PET fibers is enhanced by the addition of flexible amide bonds after crosslinking with a crosslinker.

[0066] Fiber rebound rate measurement:

[0067] Instrument used: ACTS-T300 fully automatic tensile testing machine

[0068] Measurement steps:

[0069] 1. Sample preparation: Cut 10 cm long samples of Ep-1, Ep-2, Ep-3, Ep-4, Ep-5, Ep-6, Ep-7, and Ep-8 fibers, and prepare 10 cm long pure PET samples.

[0070] 2. Clamp the sample: Clamp both ends of the above fiber sample in the clamps of the tensile testing machine, ensure that the sample remains in the correct position during the test, and measure the tensile rebound rate:

[0071] Tensile rebound rate (%) = [(rebound length-initial length) / initial length] × 100%.

[0072] The fiber sample was subjected to 50 parallel tensile tests, and the average value of the results was taken. The tensile resilience test results are shown in Table 2 below:

[0073] Table 2

[0074] As can be seen from Table 2, the tensile resilience of pure PET is 22.33%, while the tensile resilience of the modified PET polyester fiber of the present application is significantly higher than that of pure PET. By introducing a crosslinking agent and performing melt extrusion modification of the PET fiber, and then performing composite fiber molding, we can significantly improve the tensile resilience of the modified PET fiber filament and enhance its resilience. Furthermore, as shown in Examples 2 and 6, the addition of a small molecule heterocyclic compound A with a meta-heterocyclic structure can improve the tensile resilience of the modified PET polyester fiber. The main reason is that compound A enhances the degree of polymerization of PET through crosslinking. As shown in Examples 6 and 8, the tensile resilience of the modified PET polyester fiber can be affected by adjusting the ratio of the small molecule heterocyclic compound B with a para-heterocyclic structure and the small molecule heterocyclic compound A with a meta-heterocyclic structure. Here, the small molecule heterocyclic compound B with a para-heterocyclic structure and the small molecule heterocyclic compound A with a meta-heterocyclic structure not only increase the degree of polymerization of PET polyester by increasing viscosity, but also the irregular entanglement within the molecule plays a very important role in improving toughness. Therefore, the performance of the fiber can be precisely adjusted according to specific application requirements.

[0075] Fiber elongation measurement:

[0076] Ep-1, Ep-2, Ep-3, Ep-4, Ep-5, Ep-6, Ep-7, and Ep-8 were used to make injection molding splines with a size of 1 cm*0.5 cm*10 cm. These splines were tested on a universal tensile testing machine, and the relationship between test force (MPa) and displacement (mm) was obtained, as shown in Figure 2.

[0077] As shown in Figure 2, Ep-1 and Ep-2 have lower strength and less deformation capacity in the plastic phase, potentially leading to fracture or deformation when subjected to high stress. Ep-4 has a higher elastic modulus and possesses higher rigidity and strength, but exhibits lower deformation capacity in the plastic phase, likely due to its short reaction time. Ep-3, Ep-5, Ep-6, Ep-7, and Ep-8 have higher elastic moduli and are less susceptible to deformation when subjected to external forces. At the same time, they exhibit greater deformation capacity in the plastic phase, allowing them to withstand higher stresses and undergo some deformation.

[0078] Infrared spectrum detection:

[0079] The infrared spectrum of Ep-1, Ep-2, Ep-3, Ep-4, Ep-5, Ep-6, Ep-7 and Ep-8 was detected by infrared detection system, and the infrared spectrum was shown in Figure 3. As can be seen from Figure 3, it is polyester fiber fabric, and the wavelength range of 1650-1750 cm -1 The characteristic peak of amide bond appeared in the wavelength band, which shows that the modified PET polyester fibers in Examples 1-8 were successfully prepared.

[0080] DSC test:

[0081] DSC testing of Ep-1 fiber revealed a thermal analysis. Figure 4 shows the DSC results. This analysis reveals that the introduction of a crosslinker, the subsequent melt extrusion of PET fibers, and the subsequent composite fiber formation resulted in some changes in the thermal properties of Ep-1. Compared to pure PET, the modified Ep-1 fiber exhibited a slight decrease in melting point.

[0082] Advantages of the present invention: A method for preparing a modified PET polyester fiber with high resilience, wherein the PET polyester fiber is melt-extruded and modified by introducing a small molecule polyester cross-linking agent, and the ratio of a small molecule heterocyclic compound A with a meta-heterocyclic structure and a small molecule heterocyclic compound B with a para-heterocyclic structure is adjusted to simulate the composite fiber molding of PET and PTT, thereby forming a highly elastic and elastically controllable modified PET fiber filament with a hollow, spiral structure, which is easy to wash and quick to dry. Due to the addition of amide bonds and the cavity formed by the entanglement of the fiber microstructure, the sweat absorption and dyeing ability of the modified PET fiber are simultaneously improved. Compared with T400 fiber and T800 fiber, the modified PET polyester fiber of the present invention uses cheap and readily available PET polyester chips, does not require complex processes, and is economical.

[0083] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A preparation method of a modified PET polyester fiber with high resilience, characterized in that, It includes the following steps: Mix PET polyester fiber, crosslinking agent and additives to obtain a mixture; Melt and spin the mixture to obtain modified PET polyester fiber.

2. The preparation method of a modified PET polyester fiber with high resilience according to claim 1, characterized in that, The crosslinking agent includes a small molecule heterocyclic compound A with a meta-heterocyclic structure and / or a small molecule heterocyclic compound B with a para-heterocyclic structure. The chemical structural formula of the small molecule heterocyclic compound A with a meta-heterocyclic structure is , and the chemical structural formula of the small molecule heterocyclic compound B with a para-heterocyclic structure is: , where R is a substituent of mono-substituted, di-substituted or tri-substituted benzene ring.

3. The preparation method of a modified PET polyester fiber with high resilience according to claim 2, characterized in that, The substituent is a saturated fatty short carbon chain CnH2n+1, where n is 0-5.

4. The preparation method of a modified PET polyester fiber with high resilience according to claim 2, characterized in that, The substituent is an organic functional group or a polar functional group.

5. The preparation method of a modified PET polyester fiber with high resilience according to claim 2, characterized in that, The total weight percentage of the addition of the small molecule heterocyclic compound A with a meta heterocyclic structure and the small molecule heterocyclic compound B with a para heterocyclic structure is 0.1-1%.

6. The preparation method of a modified PET polyester fiber with high resilience according to claim 1, characterized in that, The viscosity of the PET polyester fiber is 0.70-1.60 dl / g, and the terminal hydroxyl group is 15-40 mol / t.

7. The preparation method of a modified PET polyester fiber with high resilience according to claim 1, characterized in that, The additives include any one or a combination of antioxidant, delustering agent, and main viscosity increasing agent.

8. The preparation method of a modified PET polyester fiber with high resilience according to claim 7, characterized in that, The main viscosity increasing agent is any one or a combination of acid anhydride, epoxy, and pentaerythritol.

9. The preparation method of a modified PET polyester fiber with high resilience according to claim 7, characterized in that, The delustering agent is titanium dioxide.

10. The preparation method of a modified PET polyester fiber with high resilience according to claim 7, characterized in that, The antioxidant is 1076 or a phosphoric acid ester antioxidant.

11. The preparation method of a modified PET polyester fiber with high resilience according to claim 1, characterized in that, The melting and spinning include plasticizing raw material particles through a twin-screw extruder, undergoing a crosslinking reaction, melting and then feeding them into the spinning section, quantitatively feeding them into the spinning assembly through a spinning pump, and extruding and forming through a spinneret after filtration.

12. The preparation method of a modified PET polyester fiber with high resilience according to claim 11, characterized in that, The feeding port temperature of the twin-screw extruder is set at 260-300°C.

13. The preparation method of a modified PET polyester fiber with high resilience according to claim 1, characterized in that, After the melting and spinning, it also includes cooling, drawing, and winding.

14. A modified PET polyester fiber with high resilience prepared by the preparation method according to any one of claims 1-13.

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