A kind of high recovery spandex fiber and preparation method thereof

Abstract

The invention discloses a high-recovery spandex fiber and a preparation method thereof, and belongs to the technical field of elastic fibers. The spandex fiber of the present invention uses polytetrahydrofuran and MDI to prepare a prepolymer solution, and the prepolymer solution is reacted with a chain extender mixed solution to form a polyurethane urea solution, and high-resilience spandex is obtained by dry spinning of the polyurethane urea solution; wherein the chain extender mixed solution contains diethanolamine, p-phenylenediamine, diethylenetriamine, and also contains 2,6-diaminopyridine and / or 2,5-bis(aminomethyl)furans. The present invention can improve the performance of the obtained spandex fiber, improve the elongation at break and the elastic recovery rate of the fiber, and can improve the hygroscopic properties of the obtained spandex fiber, so as to improve the comfort of the fabric obtained by using the spandex fiber.

Description

Technical Field

[0001] The invention belongs to the technical field of elastic fibers, and in particular relates to a high-recovery spandex fiber and a preparation method thereof. Background Art

[0002] Spandex is a highly elastic textile fiber with the advantages of high strength, light specific gravity, and large elastic recovery rate at room temperature. It is generally used to weave elastic fabrics and is widely used in the traditional clothing industry. It is currently also gradually used in medical, fire protection, communications and other fields, and has broad application prospects.

[0003] Spandex is mainly used in webbing. After the weaving process, the webbing needs high-temperature setting treatment. After the setting, the webbing of ordinary spandex will lose its high rebound effect and the elastic recovery rate will be significantly reduced. To solve this problem, the traditional method is mainly to enhance the resilience of spandex yarn by adjusting the number of holes in the coarse denier yarn and the spinning tunnel process. On the one hand, the number of spandex strands is increased under the same fiber density; on the other hand, the temperature of the spinning tunnel is increased to improve the breaking strength index of spandex yarn, but the improvement space is limited, and the improvement is even less obvious after heat setting. Summary of the invention

[0004] The object of the present invention is to provide a high-recovery spandex fiber and a preparation method thereof, which can improve the performance of the resulting spandex fiber, improve the breaking elongation and elastic recovery rate of the fiber, and improve the moisture absorption performance of the resulting spandex fiber, thereby improving the comfort of the fabric obtained by using the spandex fiber.

[0005] According to one aspect of the present invention, a chain extender mixed solution for preparing spandex fiber is provided, wherein DMAc is used as a solvent and diethanolamine (DEA), p-phenylenediamine (PDA), ethylenediamine (EDA) and diethylenetriamine (DETA) are dissolved therein.

[0006] Preferably, in the above chain extender mixed solution, the mass ratio of DEA, PDA, EDA and DETA is 1:3-8:5-15:5-15; the mass ratio of EDA to DMAc is 1 g:15-30 mL.

[0007] By adopting the above technical scheme, DETA is added to the conventional spandex production amine formula (DEA+PDA+EDA). The trace addition of this amine can increase the cross-linking between the macromolecules of the spandex stock polymer, thereby helping to increase the molecular weight of the soft segment in the resulting spandex fiber and increase the number of hydrogen bonds, which helps to improve the resilience of the spandex fiber.

[0008] Furthermore, the chain extender mixed solution also contains 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan.

[0009] Preferably, in the above chain extender mixed solution, the mass ratio of EDA to 2,6-diaminopyridine and 2,5-di(aminomethyl)furan is 1:0.5-3:0.5-3.

[0010] The addition of 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan introduces pyridine and / or furan groups into the chain extender mixed solution. During the reaction with the prepolymer solution used to prepare spandex, the presence of these heterocyclic groups helps to increase the molecular cross-linking degree, thereby improving the tensile properties and elastic recovery rate of the resulting spandex fiber, improving the softness of the resulting fabric, and ensuring comfort.

[0011] In addition, the presence of pyridine and / or furan groups can also help improve the surface structure of the resulting spandex fiber, thereby increasing the surface roughness of the spandex fiber. The presence of pyridine and / or furan groups can also help form hydrogen bonds, thereby improving their binding properties with water molecules, thereby improving the hygroscopic properties of the resulting fabric and ensuring comfort.

[0012] According to one aspect of the present invention, a high-resilience spandex fiber is provided. A prepolymer solution is prepared by using polytetrahydrofuran and MDI, and the prepolymer solution is reacted with a chain extender mixed solution to form a polyurethane urea solution. The high-resilience spandex is obtained by dry spinning the polyurethane urea solution. The chain extender mixed solution uses DMAc as a solvent and dissolves diethanolamine (DEA), p-phenylenediamine (PDA), ethylenediamine (EDA) and diethylenetriamine (DETA).

[0013] Furthermore, the chain extender mixed solution also contains 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan.

[0014] According to one aspect of the present invention, there is provided a method for preparing a high recovery spandex fiber, comprising the following steps:

[0015] S1. reacting polytetrahydrofuran and MDI at 70-90°C for 90-180 minutes to obtain blocked polytetrahydrofuran; and then mixing and dissolving with a solvent to form a prepolymer solution;

[0016] S2. Add MDI to the prepolymer solution obtained in S1, stir evenly, and cool to 5-15° C. to form a polymer solution;

[0017] S3. The chain extender mixed solution was rapidly added to the polymer solution obtained in S2 while stirring to react to form a polyurethane urea solution;

[0018] S4. The polyurethane urea solution obtained in S3 is extruded through a spinneret and dry-spun in a tunnel to form high-resilience spandex.

[0019] By adopting the above technical solution and adjusting the addition ratio of the main raw materials PTMEG and MDI, the NCO group content in the spandex fiber obtained by the reaction can be increased.

[0020] The preparation method of the chain extender mixed solution in S3 includes dissolving diethanolamine, p-phenylenediamine and diethylenetriamine in DMAc to form a chain extender mixed solution.

[0021] In addition, the above technical solution adds DETA to the conventional spandex production amine formula (DEA+PDA+EDA). The trace addition of this amine can increase the cross-linking between the macromolecules of the spandex stock polymer and increase the number of hydrogen bonds, which helps to improve the resilience of the spandex fiber.

[0022] Furthermore, 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan are added to the chain extender mixed solution.

[0023] Furthermore, in step S1, the solvent is DMAc.

[0024] Furthermore, in step S1, the mass ratio of PTMEG (polytetrahydrofuran) to MDI is 5-10:1. The mass volume ratio of MDI to DMAc is 1 g:5-15 mL.

[0025] The amount of MDI used in step S2 is 2-10% of the amount of MDI used in step S1.

[0026] The amount of DMAc in the chain extender mixed solution is 10-25% of the amount of DMAc in step S1.

[0027] In the chain extender mixed solution, the mass ratio of DEA, PDA and EDA is 1:3-8:7-15; the mass volume ratio of EDA and DMAc is 1g:15-30mL; and the mass ratio of EDA and DETA is 1:0.5-3.

[0028] In step S4, before dry spinning, TiO2, Tinuvin 622, Tinuvin 328, TSA-011 and TSA-245 are added to the polyurethane urea solution obtained in step S3 and mixed evenly.

[0029] Preferably, the mass ratio of TiO2, Tinuvin622, Tinuvin328, TSA-011 and TSA-245 is 1:2-3:0.5-2:0.5-2:0.5-2; in step S5, the mass ratio of the total amount of TiO2, Tinuvin622, Tinuvin328, TSA-011 and TSA-245 to the mass ratio of PTMEG in step S1 is 1:50-80.

[0030] Furthermore, a chain extender mixed solution is provided, which uses DMAc as a solvent, dissolves DEA, PDA, EDA, DETA, and 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan, and also adds 3,3'-diaminobenzidine.

[0031] Preferably, in the above chain extender mixed solution, the mass ratio of EDA to 3,3'-diaminobenzidine is 1:0.5-3.

[0032] The addition of 3,3'-diaminobenzidine, due to its multi-amino structure, makes it possible for various components in the chain extender mixed solution to generate branched structures during the reaction process. When used in combination with many short-chain amines, it also helps to improve the molecular cross-linking degree of the resulting spandex fiber, further ensuring the tensile properties of the resulting spandex fiber.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. A chain extender mixed solution for preparing spandex fiber is provided. DETA is added to the conventional spandex production amine formula. The trace addition of this amine can increase the cross-linking between the macromolecules of the spandex stock solution polymer, thereby helping to increase the molecular weight of the soft segment in the resulting spandex fiber, and increase the number of hydrogen bonds, which helps to improve the resilience of the spandex fiber.

[0035] 2. Adding 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan to the chain extender mixed solution can further improve the tensile properties and resilience of the resulting spandex fiber, and the addition of 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan also helps to improve the moisture regain of the resulting spandex fiber. This may be because the introduction of pyridine and / or furan groups into the chain extender mixed solution increases the surface roughness of the spandex fiber, forming more grooves and holes, thereby making the spandex fiber more soluble in combination with water molecules, and the presence of pyridine and / or furan groups also contributes to the formation of hydrogen bonds, further improving the water absorption and water lock properties of the fabric obtained using the spandex fiber.

[0036] 3. Further adding 3,3'-diaminobenzidine to the chain extender mixed solution and using it in combination with a number of short-chain amines can help improve the molecular crosslinking degree of the resulting spandex fiber, further ensure the tensile properties of the resulting spandex fiber, and improve the mechanical properties of the resulting spandex fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a SEM image of the high recovery spandex fiber obtained according to Example 2 of the present invention. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described in detail below in conjunction with specific implementation methods and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] Example 1

[0040] Preparation method of high recovery spandex fiber

[0041] S1. PTMEG and MDI are reacted at 85°C for 120 min to obtain a capped PTMEG, which is a prepolymer; the prepolymer is mixed and dissolved with a solvent DMAc to form a prepolymer solution;

[0042] S2. Add MDI to the prepolymer solution obtained in S1, stir evenly, and cool to 10° C. to form a polymer solution;

[0043] S3. Preparing a mixed solution of a chain extender, dissolving DEA, PDA, EDA and DETA in DMAc to form a mixed solution of a chain extender;

[0044] S4. The chain extender mixed solution obtained by S3 was rapidly added to the polymer solution obtained by S2 while stirring to react to form a polyurethane urea solution;

[0045] S5. TiO2, Tinuvin622, Tinuvin328, TSA-011 and TSA-245 are added to the polyurethane urea solution obtained in S4 and mixed evenly, and the mixture is extruded through a spinneret and dry-spun in a tunnel to form high-resilience spandex.

[0046] Wherein, in step S1, the mass ratio of PTMEG to MDI is 8:1. The mass volume ratio of MDI to DMAc is 1 g:10 mL.

[0047] The amount of MDI used in step S2 is 3% of the amount of MDI used in step S1.

[0048] The amount of DMAc used in step S3 is 15% of the amount of DMAc used in step S1.

[0049] In step S3, the mass ratio of DEA, PDA, EDA, and DETA is 1:5:10:10; and the mass volume ratio of EDA to DMAc is 1 g:20 mL.

[0050] In step S5, the mass ratio of TiO2, Tinuvin622, Tinuvin328, TSA-011 and TSA-245 is 1:2:1:1:1; in step S5, the mass ratio of the total amount of TiO2, Tinuvin622, Tinuvin328, TSA-011 and TSA-245 to the mass ratio of PTMEG in step S1 is 1:60.

[0051] Example 2

[0052] Compared with Example 1, this embodiment is different in that:

[0053] In step S3, when preparing the chain extender mixed solution, 2,6-diaminopyridine and 2,5-di(aminomethyl)furan are added to the DMAc solution of DEA, PDA, EDA, and DETA. The mass ratio of EDA to 2,6-diaminopyridine and 2,5-di(aminomethyl)furan is 1:1:1. The other steps and conditions are the same.

[0054] The SEM image of the spandex fiber obtained in this example is shown in Figure 1 As can be seen from the figure, the surface of the spandex fiber obtained in this example is relatively rough, with many irregularly scattered hole structures, and there are many discontinuous grooves along the fiber axis. These grooves are of different depths, making the surface of the spandex fiber not flat and smooth.

[0055] Example 3

[0056] Compared with Example 1, this embodiment is different in that:

[0057] In step S3, when preparing the chain extender mixed solution, 2,6-diaminopyridine and 2,5-di(aminomethyl)furan are added to the DMAc solution of DEA, PDA, EDA, and DETA. The mass ratio of EDA to 2,6-diaminopyridine and 2,5-di(aminomethyl)furan is 1:1.5:1.5. The other steps and conditions are the same.

[0058] Example 4

[0059] Compared with Example 1, this embodiment is different in that:

[0060] In step S3, when preparing the chain extender mixed solution, 2,6-diaminopyridine and 2,5-di(aminomethyl)furan are added to the DMAc solution of DEA, PDA, EDA, and DETA. The mass ratio of EDA to 2,6-diaminopyridine and 2,5-di(aminomethyl)furan is 1:2:2. The other steps and conditions are the same.

[0061] Example 5

[0062] Compared with Example 1, this embodiment is different in that:

[0063] In step S3, when preparing the chain extender mixed solution, 2,6-diaminopyridine and 2,5-di(aminomethyl)furan are added to the DMAc solution of DEA, PDA, EDA, and DETA, and 3,3'-diaminobenzidine is also added. The mass ratio of EDA to 2,6-diaminopyridine, 2,5-di(aminomethyl)furan and 3,3'-diaminobenzidine is 1:1:1:1. The other steps and conditions are the same.

[0064] Example 6

[0065] Compared with Example 1, this embodiment is different in that:

[0066] In step S3, when preparing the chain extender mixed solution, 2,6-diaminopyridine and 2,5-di(aminomethyl)furan are added to the DMAc solution of DEA, PDA, EDA, and DETA, and 3,3'-diaminobenzidine is also added. The mass ratio of EDA to 2,6-diaminopyridine, 2,5-di(aminomethyl)furan 3,3'-diaminobenzidine is 1:1:1:1.5. The other steps and conditions are the same.

[0067] Comparative Example 1

[0068] Compared with Example 2, this comparative example is different in that:

[0069] In step S3, 2,5-di(aminomethyl)furan is replaced by an equal mass of 2,6-diaminopyridine. The other steps and conditions are the same.

[0070] Comparative Example 2

[0071] Compared with Example 2, this comparative example is different in that:

[0072] In step S3, 2,6-diaminopyridine is replaced by an equal mass of 2,5-di(aminomethyl)furan. The other steps and conditions are the same.

[0073] Test example

[0074] Moisture regain test

[0075] The moisture regain of the spandex fibers obtained in Examples 1-6 and Comparative Examples 1-2 was tested in a ventilated oven (the moisture regain is the percentage of the difference between the wet weight and the dry weight of the sample to be tested relative to the dry weight). Test method: Under a temperature of 20°C and a relative humidity of 65%, the spandex fibers were weighed to obtain the actual weight of the spandex fibers; then the spandex fibers were placed in an oven at 45°C, and the weight was tested every 20 minutes. After the value stabilized, the dry weight of the spandex fibers was recorded. The spandex fibers obtained in each example and comparative example were weighed three times and the average value was calculated to calculate the moisture regain. The results are shown in Table 1.

[0076] Table 1 Moisture regain of spandex fibers obtained in various examples and comparative examples

[0077]

[0078] Referring to the data in Table 1, the moisture regain of the spandex fibers prepared in Examples 2-6 and Comparative Examples 1-2 is improved relative to that in Example 1, which shows that in the process of preparing spandex fibers, the addition of 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan to the chain extender mixed solution can significantly improve the moisture regain of the spandex fibers obtained. This may be because the surface of the spandex fibers prepared by adding 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan is rougher than that in Example 1, and the presence of structures such as grooves and holes on the fiber surface helps to improve the binding with water molecules, thereby showing better moisture absorption performance.

[0079] Specifically, relative to Example 1, the moisture regains of the spandex fibers prepared in Examples 2-6 and Comparative Examples 1-2 were increased by 16.6%, 19.6%, 23.5%, 31.4%, 36.3%, 8.8% and 12.7%, respectively.

[0080] The moisture regain of the spandex fiber obtained in Example 2-4 shows an increasing trend, which shows that increasing the amount of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan in the chain extender mixed solution for preparing the spandex fiber is helpful to improve the moisture regain of the obtained spandex fiber.

[0081] The moisture regain of the spandex fiber obtained in Example 2 is higher than that in Comparative Example 1 and Comparative Example 2. It can be seen that the combined addition of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan in the chain extender mixed solution for preparing the spandex fiber has a better effect on the moisture regain of the spandex fiber than the addition of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan alone.

[0082] The moisture regains of the spandex fibers obtained in Examples 5-6 increased by 12.6% and 16.8% respectively compared with those in Example 2. It can be seen that the continued addition of 3,3'-diaminobenzidine to the chain extender mixed solution containing 2,6-diaminopyridine and 2,5-di(aminomethyl)furan can further improve the moisture regain of the resulting spandex fibers.

[0083] Tensile properties test

[0084] At a temperature of 20°C and a relative humidity of 65%, the spandex fibers obtained in Examples 1-6 and Comparative Examples 1-2 were subjected to a tensile breaking test. The fiber clamping length was 100 mm, the pre-tension was 0.4 cN, the stretching rate was set to 500 mm / min, and each example was tested 10 times. The elongation at break is shown in Table 2.

[0085] Table 2 Elongation at break of spandex fibers obtained in various examples and comparative examples

[0086]

[0087] Referring to the data in Table 2, the elongation at break of the spandex fibers prepared in Examples 2-6 and Comparative Examples 1-2 is improved relative to that in Example 1, which shows that in the process of preparing the spandex fibers, the addition of 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan to the chain extender mixed solution can significantly improve the elongation at break of the spandex fibers obtained. This may be because, relative to Example 1, the molecular crosslinking degree of the spandex fibers prepared by adding 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan is improved, and the molecular weight of the soft segment part in the molecular structure is increased.

[0088] Specifically, relative to Example 1, the elongation at break of the spandex fibers prepared in Examples 2-6 and Comparative Examples 1-2 were increased by 45.8%, 48.9%, 53.2%, 68.8%, 74.3%, 36.2% and 38.2%, respectively.

[0089] The elongation at break of the spandex fiber obtained in Example 2-4 shows an increasing trend, which shows that increasing the amount of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan in the chain extender mixed solution for preparing the spandex fiber is helpful to improve the elongation at break of the obtained spandex fiber.

[0090] The elongation at break of the spandex fiber obtained in Example 2 is higher than that in Comparative Example 1 and Comparative Example 2. It can be seen that the combined addition of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan in the chain extender mixed solution for preparing the spandex fiber has a better effect on the elongation at break of the spandex fiber than the addition of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan alone.

[0091] The moisture regain of the spandex fibers obtained in Examples 5-6 increased by 12.6% and 16.8% respectively compared with that in Example 2. It can be seen that the addition of 3,3'-diaminobenzidine to the chain extender mixed solution containing 2,6-diaminopyridine and 2,5-di(aminomethyl)furan can further improve the elongation at break of the spandex fibers obtained. It can be seen that the addition of 3,3'-diaminobenzidine can improve the tensile properties of the spandex fibers obtained, which helps to improve the wear resistance of the spandex fabric obtained.

[0092] Preparation of core-spun yarn

[0093] A twisting machine was used with a pre-drafting multiple of 3.80, a covering twist of 600 t / m, and a curling rate of 20 m / min. The spandex fibers obtained in Examples 1-6 and Comparative Examples 1-2 were used as core yarns, and UHMWPE (ultra-high molecular weight polyethylene) continuous filaments were used as sheath yarns. 100D UHMWPE continuous filaments were covered with 105D spandex filaments and twisted to form yarns to obtain different core-spun yarns.

[0094] Elasticity test of core-spun yarn

[0095] With reference to FZ / T 01034-2008 "Test Method for Tensile Elasticity of Textile Woven Fabrics", the elastic recovery rate of the core-spun yarn was tested by the constant load repeated stretching method. The clamping length was set to 100 mm, the initial position was 50 mm, and the pre-tension was (0.3±0.003) cN. Stretch to 0.2 N load at a speed of 500 mm / min, hold for 5 s, then return to the initial position of 50 mm at a constant speed, hold for 5 s, and cycle 3 times. The elastic recovery rates of the core-spun yarns obtained in Examples 1-6 and Comparative Examples 1-2 are shown in Table 3.

[0096] Table 3 Elastic recovery rate of the core-spun yarn obtained in each embodiment and comparative example

[0097]

[0098] Referring to the data in Table 3, the elastic recovery rate of the core-spun yarn prepared by Examples 2-6 and Comparative Examples 1-2 is improved relative to that of Example 1. It can be seen that in the process of preparing spandex fiber, adding 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan to the chain extender mixed solution can significantly improve the elastic recovery rate of the core-spun yarn prepared by using the obtained spandex fiber. This may be because the spandex fiber prepared by adding 2,6-diaminopyridine and / or 2,5-di(aminomethyl)furan has better tensile properties than that of Example 1.

[0099] Specifically, relative to Example 1, the elastic recovery rates of the spandex fibers prepared in Examples 2-6 and Comparative Examples 1-2 were increased by 6.8%, 7.2%, 7.9%, 8.7%, 9.0%, 3.9% and 4.9%, respectively.

[0100] The elastic recovery rate of the spandex fiber obtained in Example 2-4 shows an increasing trend, which shows that the increase in the amount of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan in the chain extender mixed solution for preparing the spandex fiber is helpful to improve the elastic recovery rate of the core-spun yarn prepared from the obtained spandex fiber.

[0101] The elastic recovery rate of the spandex fiber obtained in Example 2 is higher than that in Comparative Example 1 and Comparative Example 2. It can be seen that the combined addition of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan in the chain extender mixed solution for preparing spandex fibers has a better effect on the elastic recovery rate of the core-spun yarn prepared from spandex fibers than the addition of 2,6-diaminopyridine and 2,5-di(aminomethyl)furan alone.

[0102] The moisture regains of the spandex fibers obtained in Examples 5-6 increased by 12.6% and 16.8% respectively compared with that in Example 2. It can be seen that the continued addition of 3,3'-diaminobenzidine to the chain extender mixed solution containing 2,6-diaminopyridine and 2,5-di(aminomethyl)furan can further improve the elastic recovery rate of the core-spun yarn prepared from the resulting spandex fibers.

[0103] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here.

[0104] The above-described embodiments provide a detailed description of the technical solution of the present invention. It should be understood that the above-described embodiments are only specific embodiments of the present invention and are not intended to limit the present invention. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for preparing high-recovery spandex fiber, characterized in that: The following steps are involved: S1. reacting polytetrahydrofuran and MDI at 70-90°C for 90-180 minutes to obtain blocked polytetrahydrofuran; and then mixing and dissolving with a solvent to form a prepolymer solution; S2. Add MDI to the prepolymer solution obtained in S1, stir evenly, and cool to 5-15° C. to form a polymer solution; S3. The chain extender mixed solution was rapidly added to the polymer solution obtained in S2 while stirring to react to form a polyurethane urea solution; S4. The polyurethane urea solution obtained in S3 is extruded through a spinneret and dry-spun in a tunnel to form a high resilience spandex; In step S3, the chain extender mixed solution contains diethanolamine, p-phenylenediamine, diethylenetriamine and ethylenediamine, and also contains 2,6-diaminopyridine, 2,5-di(aminomethyl)furan and 3,3'-diaminobenzidine; In the chain extender mixed solution, the mass ratio of diethanolamine, p-phenylenediamine, ethylenediamine, and diethylenetriamine is 1:3-8:5-15:5-15; the mass volume ratio of ethylenediamine to DMAc is 1 g:15-30 mL; the mass ratio of ethylenediamine to 2,6-diaminopyridine and 2,5-di(aminomethyl)furan is 1:0.5-3:0.5-3, and the mass ratio of ethylenediamine to 3,3'-diaminobenzidine is 1:0.5-3; The solvent in step S1 is DMAc; the solvent in the chain extender mixed solution is DMAc.

2. The method for preparing high recovery spandex fiber according to claim 1, characterized in that: In step S1, the mass ratio of polytetrahydrofuran to MDI is 5-10:1; the mass ratio of MDI to DMAc is 1:6-12; The amount of MDI used in step S2 is 2-10% of the amount of MDI used in step S1; The amount of DMAc in the chain extender mixed solution is 10-25% of the amount of DMAc in step S1.

3. The method for preparing high recovery spandex fiber according to claim 1, characterized in that: In step S4, before dry spinning, TiO2, Tinuvin 622, Tinuvin 328, TSA-011 and TSA-245 are added to the polyurethane urea solution obtained in step S3 and mixed evenly.

4. The high recovery spandex fiber prepared by the method according to any one of claims 1 to 3.

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