Spun yarn with high cohesion and good unwinding property and its preparation method

Abstract

This invention relates to a spandex fiber with good unwinding properties and high cohesion, and its preparation method. The spandex fiber comprises a mixture of polyurethane-urea and a lubricant, wherein the lubricant mixture includes a lubricant and a dispersant; the lubricant includes organic lubricants and inorganic lubricants, and the dispersant includes poly(α-cyanoacrylate). Furthermore, the spandex fiber also contains a crosslinking stabilizer and / or functional additives. The preparation method is as follows: a polymeric polyol and a polyisocyanate are reacted to obtain a polyurethane prepolymer; the obtained polyurethane prepolymer is dissolved in a solvent to obtain a polyurethane prepolymer solution; the obtained polyurethane prepolymer solution, a diamine chain extender, and an amine chain terminator are reacted to obtain a polyurethane-urea solution; the polyurethane-urea solution, the lubricant mixture, the crosslinking stabilizer, and the functional additives are used to prepare a raw material in the presence of a solvent, which is then dry-spun to obtain the spandex fiber. This spandex fiber exhibits excellent unwinding properties, high cohesion, high resilience, and high elongation.

Description

Technical Field

[0001] This invention relates to a spandex fiber with good unwinding properties and high cohesion, and its preparation method, belonging to the technical field of polyurethane elastic fiber manufacturing. Background Technology

[0002] Spandex is short for polyurethane fiber. Thanks to its high elasticity, high elongation, and high recovery rate, the comfort of fabrics made from spandex is significantly improved. Spandex is generally composed of multiple filaments, with spandex fibers of 140D and above widely used in elastic fabrics such as webbing, diaper waistbands, and elastic bands. With the development of productivity, the demand for higher production efficiency has placed higher requirements on the performance of spandex products. Poor unwinding of spandex, and fiber breakage due to friction between fibers, metals, and plastics under high-speed conditions, are the two main challenges that need to be addressed during the high-speed unwinding process of these spandex products.

[0003] Several patents have been reported on methods to improve the cohesion and unwinding properties of spandex fibers. Patent CN103339303A enhances the adhesion between filaments in multifilament fibers by adding 0.01–10 wt% of dialkyl sulfosuccinate. Patent CN107641847A enhances adhesion by adding 0.1–20 wt% of liquid polyamide. Patent CN103109005A prepares spandex fibers by adding cellulose acetate butyrate, cellulose acetate propionate, and mixtures thereof as a soluble anti-adhesive composition, and at least one calcium stearate, magnesium stearate, organic stearate, silicone oil, mineral oil, and mixtures thereof. Patent CN108221076A improves the unwinding properties of spandex in diapers by adding polyhedral oligomeric silsesquioxane (POSS). Patent CN106978650A introduces polystyrene polymers with a number average molecular weight of 20,000 to 500,000 into the spinning solution of polyurethane urea to prevent irregular bulging and tension peaks during unwinding and to enhance adhesion properties with hot melt adhesives.

[0004] It can be seen that the current methods mainly focus on improving unwinding smoothness or the adhesion between fibers. These methods have some shortcomings, including but not limited to: (1) the improvement of unwinding smoothness and the improvement of adhesion between fibers are difficult to reconcile; (2) the unwinding improvement effect of a single organic or inorganic lubricant is limited; (3) inorganic additives such as matting agents have poor compatibility with polyurethane organic matrix, which can easily lead to powdering or frictional fiber separation; (4) additives may reduce the resilience of spandex fibers. Summary of the Invention

[0005] Technical problem: The purpose of this invention is to prepare a spandex fiber with good unwinding properties and high cohesion, and a method for preparing the same. The spandex product combines unwinding and cohesion properties, while maintaining the high resilience and high elongation properties of the spandex fiber in this application.

[0006] Technical solution: The present invention provides a spandex with good unwinding properties and high cohesion, comprising a polyurethane-urea mixture and a lubricant mixture, wherein the lubricant mixture comprises a lubricant and a dispersant;

[0007] The lubricant includes organic lubricants and inorganic lubricants; the organic lubricant includes at least one of hydroxyethyl ethylene bis-stearamide, lauryl amide, and erucamide; the inorganic lubricant includes at least one of hydrotalcite and mica powder; the organic lubricant accounts for 0.01 to 5 wt% of the total mass of spandex, and the inorganic lubricant accounts for 0.1 to 5 wt% of the total mass of spandex.

[0008] The dispersant comprises poly(α-cyanoacrylate), with the following unit structure:

[0009]

[0010] Where R is the carbon skeleton with 1 to 8 carbon atoms;

[0011] The poly(α-cyanoacrylate) has a number-average molecular weight of 6000–60000 g / mol;

[0012] The poly(α-cyanoacrylate) accounts for 0.1 to 20 wt% of the total mass of the spandex.

[0013] The spandex also contains crosslinking stabilizers and / or functional auxiliaries. The crosslinking stabilizers include one or a mixture of inositol triphosphate and inositol hexaphosphate, and the crosslinking stabilizers account for 0.01 to 5 wt% of the total mass of the spandex. The functional auxiliaries include one or more of antioxidants, UV stabilizers, UV anti-yellowing agents, matting agents, dyeing auxiliaries, and chlorine-resistant auxiliaries.

[0014] The polyurethane-urea comprises the reaction product of polymeric polyol, polyisocyanate, diamine chain extender and amine chain terminator;

[0015] The polymer polyol includes any one or a combination of at least two of polytetramethylene ether diol, polyethylene glycol, or polypropylene glycol; the number average molecular weight of the polymer polyol is 1000 to 4000.

[0016] The polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate;

[0017] The diamine chain extender comprises diamines having 2 to 30 carbon atoms, and further comprises any one or a combination of at least two of ethylenediamine, propylenediamine, butanediamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexamethylenediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, or hexamethylenediamine.

[0018] The amine chain terminator comprises a monoamine having 2 to 20 carbon atoms, including any one or a combination of at least two of the following: diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, diethylamine, dipropylamine, cyclohexylamine, or ethanolamine.

[0019] The present invention provides a method for preparing spandex with good unwinding properties and high cohesion, comprising:

[0020] Step 1. The polymer polyol and polyisocyanate are reacted to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer is dissolved in a solvent to obtain a polyurethane prepolymer solution. The molar ratio of polyisocyanate to polymer polyol is (1.80~2.20):1.

[0021] Step 2. React the obtained polyurethane prepolymer solution, diamine chain extender and amine chain terminator to obtain polyurethane-urea solution; wherein the molar ratio of diamine chain extender and amine chain terminator is (15.0~25.0):1;

[0022] The molar ratio of NCO in the polyurethane prepolymer to the amine groups in the diamine chain extender and amine chain terminator is 1:(1.01~1.10);

[0023] Step 3. Prepare the raw material by using polyurethane-urea solution, lubricant mixture, crosslinking stabilizer and functional additives in the presence of solvent, and obtain the spandex fiber by dry spinning;

[0024] The spandex fiber has a denier of ≥140D and contains 10 to 40 monofilaments.

[0025] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0026] This invention adds a lubricant mixture containing poly(α-cyanoacrylate) as a dispersion to spandex, which can significantly improve the cohesion between monofilaments in spandex and efficiently combine organic lubricants to improve the unwinding effect of spandex. The addition of a crosslinking stabilizer can effectively avoid the poor compatibility between the additives and polyurethane when other powdered functional additives are added, solve the problems of easy precipitation and friction powdering of functional additives, and further reduce the surface friction coefficient of the filament bundle. Detailed Implementation

[0027] The spandex with good unwinding properties and high cohesion comprises a polyurethane-urea mixture and a lubricant mixture, wherein the lubricant mixture comprises a lubricant and a dispersant;

[0028] The lubricant includes organic lubricants and inorganic lubricants; the organic lubricant includes at least one of hydroxyethyl ethylene bis-stearamide, laurylamide, and erucamide; the inorganic lubricant includes at least one of hydrotalcite and mica powder.

[0029] Furthermore, the organic lubricant accounts for 0.01 to 5 wt% of the total mass of spandex, and the inorganic lubricant accounts for 0.1 to 5 wt% of the total mass of spandex;

[0030] The dispersant comprises poly(α-cyanoacrylate), with the following unit structure:

[0031]

[0032] Where R is the carbon skeleton with 1 to 8 carbon atoms;

[0033] The poly(α-cyanoacrylate) has a number-average molecular weight of 6000–60000 g / mol;

[0034] Furthermore, the poly(α-cyanoacrylate) accounts for 0.1 to 20 wt% of the total mass of the spandex.

[0035] Furthermore, the spandex also contains a crosslinking stabilizer, which includes one or a mixture of inositol triphosphate and inositol hexaphosphate, and the crosslinking stabilizer accounts for 0.01 to 5 wt% of the total mass of the spandex.

[0036] Other functional additives commonly used in the field of spandex can be optionally added to the spandex, as long as they do not degrade the performance of the product, including one or more of antioxidants, UV stabilizers, anti-yellowing agents, matting agents, dyeing auxiliaries, and chlorine-resistant auxiliaries;

[0037] Preferably, the crosslinking stabilizer is mixed with the additives and then added to the spandex.

[0038] The polyurethane-urea comprises the reaction product of polymeric polyol, polyisocyanate, diamine chain extender and amine chain terminator;

[0039] The polymer polyols include any one or a combination of at least two of polytetramethylene ether diol, polyethylene glycol or polypropylene glycol, and are more preferably polytetramethylene ether diol;

[0040] The number-average molecular weight of the polymer polyol is 1000-4000;

[0041] The polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate, and is more preferably diphenylmethane diisocyanate.

[0042] Diamine chain extenders include diamines having 2 to 30 carbon atoms, and further include any one or a combination of at least two of the following: ethylenediamine, propylenediamine, butanediamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexanediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, or hexamethylenediamine.

[0043] The amine chain terminator comprises a monoamine having 2 to 20 carbon atoms, and is more preferably any one or a combination of at least two of the following: diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, diethylamine, dipropylamine, cyclohexylamine, or ethanolamine.

[0044] The polyurethane-urea is prepared by the following method, which includes the following steps:

[0045] 1) The polymer polyol and polyisocyanate are reacted to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer is dissolved in a solvent to obtain a polyurethane prepolymer solution.

[0046] 2) The obtained polyurethane prepolymer solution, diamine chain extender and amine chain terminator are reacted to obtain a solution containing polyurethane-urea.

[0047] Preferably, in step 1), the molar ratio of polyisocyanate to polymeric polyol is (1.80–2.20):1;

[0048] In step 2), the molar ratio of diamine chain extender to amine chain terminator is (15.0–25.0):1.

[0049] Preferably, in step 2), the molar ratio of NCO in the polyurethane prepolymer to the amine groups in the diamine chain extender and amine chain terminator is 1:(1.01~1.10).

[0050] The solvent is N,N-dimethylformamide and / or N,N-dimethylacetamide. In some embodiments of the present invention, the solvent includes N,N-dimethylacetamide (DMAc).

[0051] In some embodiments of the present invention, the reaction temperature of step 1) is 70–95°C;

[0052] The reaction temperature in step 2) is 0–10°C.

[0053] There are no specific requirements for the reaction time; just ensure that all raw materials react completely.

[0054] The method for preparing spandex with good unwinding properties and high cohesion includes: spinning the aforementioned polyurethane-urea, lubricant mixture, optional crosslinking stabilizer, and optional other functional additives in the presence of a solvent to obtain the spandex fiber;

[0055] The spinning process described is dry spinning;

[0056] The dry spinning process includes the steps of spraying, stretching, and drying.

[0057] Furthermore, in some embodiments of the present invention, the spinning temperature is above 150°C; and the temperature after spinning is below 50°C.

[0058] In some embodiments of the present invention, a solution containing polyurethane-urea, a solution containing a lubricant mixture, and a solution containing optional other functional additives and optional crosslinking stabilizers can be prepared separately, and then mixed to obtain a spinning solution, which can be dry-spun to obtain spandex fibers.

[0059] The lubricant-containing mixture solution is obtained by fully dispersing poly(α-cyanoacrylate), organic lubricant, and inorganic lubricant into a solvent through ultrasonic stirring;

[0060] The solution containing optional other functional additives and optional crosslinking stabilizers is obtained by dispersing at least one of the following additives, including antioxidants, UV stabilizers, UV stabilizers, anti-yellowing agents, matting agents, dyeing auxiliaries, and chlorine-resistant auxiliaries, into a solvent, and then adding a crosslinking stabilizer and stirring thoroughly.

[0061] If the other functional additives are in solid state, they can be ground to obtain a particle size D95 of 2-10 μm;

[0062] Furthermore, in some embodiments of the present invention, the solution containing optional other functional additives and optional crosslinking stabilizers is obtained by fully dispersing at least one of the following additives—antioxidant, UV stabilizer, UV stabilizer, anti-yellowing agent, matting agent, dyeing auxiliary agent, and chlorine-resistant auxiliary agent—into a solvent through cyclic grinding, and then adding a crosslinking stabilizer and stirring thoroughly. The particle size D95 of the dispersed particles in the solution is 2–10 μm.

[0063] The spinning solution has a mass percentage of 30% to 40% and a constant temperature viscosity of 3000 to 10000 poise at 40°C.

[0064] Furthermore, the spinning solution is subjected to a curing treatment before spinning, and the curing temperature is 30-45℃.

[0065] The spandex fiber has a denier of ≥140D and contains 10 to 40 monofilaments.

[0066] The following embodiments are used to describe the production process of the present invention in detail, but these embodiments should not be construed as limiting the present invention in any way.

[0067] Preparation of polyurethane-urea solution: Polytetramethylene ether diol (number average molecular weight 1800) was added to a reaction vessel, stirred and heated to 50°C, and diphenylmethane diisocyanate was added to react, resulting in a polyurethane prepolymer with isocyanate (-NCO) end-capped. Ethylenediamine and diethylamine were prepared into a 5% (w / w) mixed amine solution with DMAc, and the solution was reacted with the prepolymer to carry out a chain extension reaction. DMAc was added to obtain a 35% (w / w) polyurethane-urea solution.

[0068] Polyurethane-urea solution 1: The molar ratio of diphenylmethane diisocyanate to polytetramethylene ether diol is 1.85:1, and the molar ratio of ethylenediamine and diethylamine is 20:1;

[0069] Polyurethane-urea solution 2: The molar ratio of diphenylmethane diisocyanate to polytetramethylene ether diol is 1.95:1, and the molar ratio of ethylenediamine and diethylamine is 18:1.

[0070] Preparation of a lubricant-containing mixture solution: The lubricant and dispersant were ultrasonically stirred and dispersed in DMAc to obtain a lubricant-containing mixture solution with a mass content of 35%;

[0071] Dispersant 1 is poly(α-cyanoacrylate) 1, with the following unit structure:

[0072]

[0073] Where R is ethyl, and the average number-average molecular weight is 20,000;

[0074] Dispersant 2 is poly(α-cyanoacrylate) 2, with the following unit structure:

[0075]

[0076] Where R is n-butyl and the average number-average molecular weight is 20,000;

[0077] Dispersant 3 is polypropylene with an average number-average molecular weight of 20,000.

[0078] Preparation of solutions containing other functional additives and crosslinking stabilizers: The functional additives are fully dispersed in DMAc through cyclic grinding. In the embodiments and comparative examples of this invention, the types and amounts of functional additives are kept consistent: the antioxidant is antioxidant 245 (triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]), with a mass percentage of 0.5%; the UV stabilizer is Solvay's product M535, with a mass percentage of 0.5%; the matting agent is titanium dioxide, with a mass percentage of 0.5%; and the anti-yellowing agent is HN-150 (bis(N,N-dimethylhydrazine amino-4-phenyl)methane), with a mass percentage of 0.5%. The above mass percentages are all calculated based on the total mass of the prepared spandex fibers, and the total mass percentage of the functional additives is 2%.

[0079] Add a crosslinking stabilizer to the above mixed solution and mix thoroughly to obtain a solution containing other functional additives and crosslinking stabilizer with a mass content of 30%.

[0080] Preparation of spandex fiber: Polyurethane-urea solution, solution containing lubricant mixture, solution containing other functional additives and crosslinking stabilizer are mixed and cured at 50°C for 25 hours, and then dry spinning is carried out to obtain spandex fiber, wherein the spinning temperature is 260°C.

[0081] The spinning raw materials and prepared spandex fibers of Examples 1 to 4 are shown in Table 1 below:

[0082] Table 1:

[0083]

[0084]

[0085] Example 5

[0086] The difference between the spinning raw material in Example 5 and that in Example 1 is that no organic lubricant is added, and an equal mass of inorganic lubricant hydrotalcite is used to replace the original organic lubricant. The viscosity of the spinning solution, the denier of the spandex fiber, and the number of spandex monofilaments of the prepared spandex fiber 5 are the same as those of spandex fiber 1.

[0087] Example 6

[0088] The difference between the spinning raw material in Example 6 and that in Example 1 is that no inorganic lubricant is added, and an equal mass of organic lubricant hydroxyethyl ethylene bis-stearamide is used to replace the original inorganic lubricant. The spinning solution viscosity, spandex denier, and spandex monofilament number of the prepared spandex fiber 6 are the same as those of spandex fiber 1.

[0089] Example 7

[0090] The difference between the spinning raw material in Example 7 and that in Example 1 is that the same mass of dispersant 3 is used to replace dispersant 1 in Example 1. The viscosity of the spinning solution, the denier of the spandex fiber, and the number of spandex monofilaments of the prepared spandex fiber 7 are the same as those of the spandex fiber 1.

[0091] Example 8

[0092] The difference between the spinning raw material in Example 8 and that in Example 2 is that no crosslinking stabilizer is added. The viscosity of the spinning solution, the denier of the spandex, and the number of spandex monofilaments of the prepared spandex fiber 8 are the same as those of spandex fiber 2.

[0093] Example 9

[0094] The difference between the spinning raw material in Example 9 and that in Example 2 is that the same mass of polyethyleneimine is used to replace the inositol triphosphate in Example 1. The spinning solution viscosity, spandex denier, and spandex monofilament number of the prepared spandex fiber 9 are the same as those of spandex fiber 2.

[0095] Comparative Example 1

[0096] The difference between the spinning raw material in Example 1 and that in Example 1 is that no crosslinking dispersant is added. The viscosity of the spinning solution, the denier of the spandex, and the number of spandex monofilaments of the comparative spandex fiber 1 are the same as those of the spandex fiber 2.

[0097] The spandex fibers prepared in the above embodiments and comparative examples were subjected to the following performance tests, and the test results are compared in Table 2 below:

[0098] SS300 / DS / DE test method: adopts FZ / T 50006-2013 "Test method for tensile properties of spandex filament";

[0099] Elastic recovery rate RER310: This represents the elastic recovery rate of the sample after being repeatedly stretched 5 times to 300%, according to F1 / Z50007-2012 "Test for Elasticity of Spandex Filament";

[0100] Unwinding property: Characterizes the ease with which spandex yarn is unwound. It represents the draw ratio when the spandex yarn adheres to the surface of the yarn roll in the unwound state. The larger the value, the worse the unwinding property, and vice versa.

[0101] Unwinding property: Characterizes the ease with which spandex yarn is unwound. It represents the draw ratio when the spandex yarn adheres to the surface of the yarn roll in the unwound state. The larger the value, the worse the unwinding property, and vice versa.

[0102] Coefficient of friction between wires: The ratio of the frictional force between wires to the perpendicular force acting on one of their surfaces. It reflects the roughness of the contacting surfaces and is independent of the size of the contact area. The larger the value, the greater the roughness, and vice versa.

[0103] Cohesion: The force resisted by the fibers in contact with each other in the filament bundle when they move relative to each other. The larger the value, the stronger the cohesion, and vice versa. The test method for cohesion performance of spandex filaments is adopted according to FZ / T 50039-2018.

[0104] Table 2:

[0105]

Claims

1. A type of spandex with good unwinding properties and high cohesion, characterized in that... The spandex comprises a polyurethane-urea mixture and a lubricant mixture, wherein the lubricant mixture comprises a lubricant and a dispersant; The lubricants mentioned include organic lubricants and inorganic lubricants; The dispersant comprises poly(α-cyanoacrylate), with the following unit structure: Where R is the carbon skeleton with 1 to 8 carbon atoms; The spandex also contains a crosslinking stabilizer, which includes one or a mixture of inositol triphosphate and inositol hexaphosphate.

2. The spandex with good unwinding properties and high cohesion according to claim 1, characterized in that, The organic lubricant includes at least one of hydroxyethyl ethylene bis-stearamide, lauryl amide, and erucamide; the inorganic lubricant includes at least one of hydrotalcite and mica powder; the organic lubricant accounts for 0.01 to 5 wt% of the total mass of spandex, and the inorganic lubricant accounts for 0.1 to 5 wt% of the total mass of spandex.

3. The spandex with good unwinding properties and high cohesion according to claim 1, characterized in that, The poly(α-cyanoacrylate) has a number-average molecular weight of 6,000 to 60,000 g / mol; the poly(α-cyanoacrylate) accounts for 0.1 to 20 wt% of the total mass of the spandex.

4. The spandex with good unwinding properties and high cohesion according to claim 1, characterized in that, The spandex also contains functional additives, including one or more of antioxidants, UV stabilizers, anti-yellowing agents, matting agents, dyeing auxiliaries, and chlorine-resistant auxiliaries. The crosslinking stabilizer accounts for 0.01 to 5 wt% of the total mass of the spandex.

5. The spandex with good unwinding properties and high cohesion according to claim 1, characterized in that, The polyurethane-urea comprises the reaction product of polymeric polyol, polyisocyanate, diamine chain extender, and amine chain terminator.

6. The spandex with good unwinding properties and high cohesion according to claim 5, characterized in that, The polymer polyol includes any one or a combination of at least two of polytetramethylene ether diol, polyethylene glycol, or polypropylene glycol; the number average molecular weight of the polymer polyol is 1000 to 4000.

7. The spandex with good unwinding properties and high cohesion according to claim 5, characterized in that, The polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, or dicyclohexylmethane diisocyanate.

8. The spandex with good unwinding properties and high cohesion according to claim 5, characterized in that, The diamine chain extender includes diamines with 2 to 30 carbon atoms.

9. A spandex with good unwinding properties and high cohesion according to claim 8, characterized in that, The diamine having 2 to 30 carbon atoms includes any one or a combination of at least two of the following: ethylenediamine, propylenediamine, butanediamine, pentanediamine, methylpentanediamine, methylpropylenediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, or hexamethylenediamine.

10. A spandex with good unwinding properties and high cohesion according to claim 5, characterized in that, The amine chain terminator includes monoamines with 2 to 20 carbon atoms.

11. The spandex with good unwinding properties and high cohesion according to claim 10, characterized in that, The monoamine having 2 to 20 carbon atoms includes any one or a combination of at least two of the following: diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, dipropylamine, cyclohexylamine, or ethanolamine.

12. A method for preparing spandex with good unwinding properties and high cohesion as described in any one of claims 1 to 11, characterized in that, The preparation method includes: Step 1. The polymer polyol and polyisocyanate are reacted to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer is dissolved in a solvent to obtain a polyurethane prepolymer solution. The molar ratio of polyisocyanate to polymer polyol is (1.80~2.20):

1. Step 2. React the obtained polyurethane prepolymer solution, diamine chain extender, and amine chain terminator to obtain a polyurethane-urea solution; wherein the molar ratio of diamine chain extender to amine chain terminator is (15.0~25.0):1; the molar ratio of NCO in polyurethane prepolymer to amine groups in diamine chain extender and amine chain terminator is 1:(1.01~1.10); Step 3. Prepare the raw material by using polyurethane-urea solution, lubricant mixture, crosslinking stabilizer and functional additives in the presence of solvent, and obtain the spandex fiber by dry spinning; The spandex fiber has a denier of ≥140D and contains 10 to 40 monofilaments.

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