An spandex fiber, a preparation method thereof, and a textile prepared therefrom

Abstract

The present invention belongs to the field of spinning and relates to the manufacture of chemical fibers, particularly to a spandex fiber and its preparation method. This invention addresses the poor mechanical properties and heat resistance of conventional spandex. By copolymerizing an aromatic diol with an isocyanate, followed by chain extension, the rigidity of the molecular chain is significantly enhanced. The resulting polyurethane exhibits a certain degree of birefringence in both solution and molten states, facilitating high molecular chain orientation during molding. Further, through solution or melt spinning, spandex fibers with excellent mechanical properties and heat resistance are obtained, meeting the application requirements of high-temperature printing and dyeing and high-end fields.

Description

Technical Field

[0001] The invention belongs to the field of spinning and relates to the manufacture of chemical fibers, in particular to a spandex fiber and a preparation method thereof and the prepared textile. Background Art

[0002] Spandex possesses unparalleled elasticity compared to other synthetic fibers, with an elongation at break of up to 800% and an elastic recovery rate exceeding 95%. It is widely used in textiles, clothing, healthcare, sports, defense, and military industries. Even a small amount can impart excellent elasticity, comfort, and shape retention to textiles, making it an indispensable fiber material for high-end textiles. Patent publication number CN101849048A discloses a type of spandex that improves its heat-setting efficiency by modifying its structure. This involves the use of asymmetric isocyanates or symmetrical isocyanates with steric hindrance. However, while this improves heat-setting efficiency, the mechanical strength and heat resistance of the spandex decrease to varying degrees.

[0003] Conventional spandex polymers are prepared by stepwise polymerization and chain extension of polyaliphatic polydiols and aromatic diisocyanates. The presence of a large amount of aliphatic diols in the molecular chain results in poor mechanical properties and heat resistance of conventional spandex. Patent publication number CN109487361A discloses a spandex fiber with excellent heat resistance and low-temperature settability and a preparation method. A prepolymer is prepared by reacting a polyol with an isocyanate, and the prepolymer is subjected to secondary polymerization with a chain extender to obtain a polyurethane urea polymer stock solution. Various additives are added to the stock solution, stirred uniformly, and then spun to obtain the spandex fiber. However, the thermal decomposition temperature is low, below 230°C, which cannot meet the requirements of subsequent high-temperature printing and dyeing and high-end applications of spandex. Summary of the Invention

[0004] In order to solve the technical problems encountered in increasing the pyrolysis temperature of spandex fiber and improving the flame retardant properties and mechanical properties of spandex, the present invention provides a spandex fiber and a preparation method and application thereof.

[0005] The technical solution of the present invention is achieved as follows:

[0006] A method for preparing spandex fiber comprises the following steps:

[0007] (1) Prepolymerization: Aromatic diol and diisocyanate are dissolved in a polar amine solution at a molar ratio of 1:(1.5-2.1) and a catalyst, and then placed in a prepolymerization reactor. The mixture is stirred at high speed at 80-110°C for 80-100 minutes to prepare prepolymer A. Polyglycol and diisocyanate are dissolved in a polar amine solution at a molar ratio of 1:(1.2-2), and then placed in a prepolymerization reactor. The mixture is stirred at high speed at 80-110°C for 60-90 minutes to prepare prepolymer B. Prepolymers A and B are mixed at a mass ratio of 3:7-9:1 and then transported to a final polymerization reactor.

[0008] (2) Polymerization: dissolving and dispersing the chain extender and the auxiliary agent in a polar amine solution, adding the solution to the final polymerization reactor by multi-point injection, chain extending the prepolymer, and obtaining a polyurethane urea solution with a weight average molecular weight greater than 80,000;

[0009] (3) Spinning: The polyurethane urea solution is matured to obtain a spinning solution, which is then transported to the spinning manifold through a metering pump and extruded through a spinneret. The filaments are solidified in the spinning tunnel and wound to obtain high-performance spandex yarns. Alternatively, the polyurethane urea solution is precipitated in an ethanol solution, filtered and dried, and then melt-spun to prepare high-performance spandex yarns.

[0010] The aromatic diol is a combination of one or two of the following structures:

[0011]

[0012] Where n is a positive integer from 2 to 12.

[0013] The diisocyanate is any one of 4,4'-methylenebis(phenyl isocyanate), toluene-2,4-diisocyanate, toluene-2,5-diisocyanate, 2,2'-dimethylbiphenyl isocyanate, and azophenyl diisocyanate;

[0014] The polyglycol is any one of polyethylene glycol, polypropylene glycol, and polytetramethylene glycol;

[0015] The catalyst is any one of stannous octoate, dibutyltin dilaurate, and dibutyltin sulfide, and the amount used is 0.01-0.5wt% of the total weight of the monomers.

[0016] The polar amine solution is N,N-dimethylformamide or N,N-dimethylacetamide;

[0017] The chain extender is a diamine or a diol, wherein the diamine is one of ethylenediamine, propylenediamine and butanediamine; and the diol is any one of butanediol and polyethylene glycol with a molecular weight of ≤600.

[0018] The auxiliary agents are light stabilizers, pigments, antioxidants and antibacterial agents, and the dosage is 0.1-2 wt% of the total mass of the spinning solution.

[0019] The viscosity of the spinning solution is 20-80 Pa.s, the number of spinnerets is 60-100, the temperature of the hot air or hot nitrogen in the spinning tunnel is 230-280°C, the gas flow rate is 0.1-1m / s, and the winding speed is 600-1000m / min.

[0020] The melt spinning is carried out in a screw spinning machine, the spinning temperature is 250-280° C., and the winding speed is 800-1500 m / min.

[0021] The spandex fiber prepared by the method has a breaking strength greater than 2.0 cN / dtex, a breaking elongation of 100-700%, a fineness of 5-40D, a thermal decomposition temperature greater than 280° C., and a limiting oxygen index greater than 28%.

[0022] Textiles prepared based on the above spandex fibers.

[0023] The present invention has the following beneficial effects:

[0024] The present invention copolymerizes aromatic diols, polydiols and isocyanate respectively, and then performs chain extension, which can give spandex a molecular chain structure that is both rigid and flexible, improve the acting force and rigidity of the molecular chains, enhance the degree of microphase separation, and reduce the hydrogen bond density of the spandex. The prepared polyurethane has a certain birefringence phenomenon in solution and molten states, and exhibits flow behavior similar to that of liquid crystal molecules, which is conducive to the high orientation of molecular chains in molding processing (dry method and melt spinning), thereby obtaining spandex fibers with excellent mechanical properties and heat resistance. The defects of conventional spandex such as low mechanical properties, poor heat resistance and weather resistance caused by containing a large amount of flexible aliphatic polydiol structures are greatly improved, and the quality of the spandex fibers is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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] Figure 1 2 is a comparison chart of the thermogravimetric curves of spandex in Example 1 and the comparative example.

[0027] Figure 2 This is a microscope image of the apparent morphology of the spandex in Example 1 (magnification 1000x).

[0028] Figure 3 This is the birefringence phenomenon of the spandex spinning solution in Example 1 (magnification 500x).

[0029] Figure 4 2 is a comparison chart of spandex viscosity between Example 2 and the comparative example.

[0030] Figure 5 This is the GPC curve of spandex in Example 1. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used are commercially available reagents and materials unless otherwise specified.

[0033] Example 1

[0034] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0035] (1) Biphenylene glycol and 4,4'-methylenebis(phenyl isocyanate) in a molar ratio of 1:1.5 and catalysts stannous octoate and N,N-dimethylformamide were added to a prepolymerization reactor, with the amount of stannous octoate being 0.1% of the total weight of the monomers. The mixture was stirred at 80°C for 80 minutes to prepare a prepolymer A with a mass fraction of 25%. Polyethylene glycol and 4,4'-methylenebis(phenyl isocyanate) in a molar ratio of 1:1.2 and N,N-dimethylformamide were added to a prepolymerization reactor, and the mixture was stirred at 80°C for 60 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B were transported to a final polymerization reactor at a mass ratio of 9:1.

[0036] (2) dissolving and dispersing the chain extenders ethylenediamine and butanediol (in a ratio of 1:9) and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the amount of the auxiliary agent is 0.1 wt%), and adding them to the final polymerization reactor for chain extension. The amount of the chain extender is 15 wt% of the total mass of the polyurethane urea solution. The chain extension reaction is carried out at 90° C. for 30 min to obtain a polyurethane urea solution with a weight average molecular weight of 82,000.

[0037] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 45 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 60, and the filaments are solidified in a spinning tunnel filled with nitrogen at 280°C. The gas flow rate is 0.1 m / s and the winding speed is 600 m / min. High-performance spandex filaments with a strength of 2.5 cN / dtex, an elongation at break of 140%, and a limiting oxygen index of 28.7% are obtained.

[0038] The apparent morphology of the spandex prepared in this embodiment is as follows Figure 2 As shown by Figure 2 It can be seen that the fiber fineness is relatively uniform and the surface is relatively smooth;

[0039] The spinning solution in this embodiment was observed under a polarizing microscope, and the results were as follows: Figure 3 As shown by Figure 3 It can be seen that birefringence can be observed, indicating that the molecular chain has strong rigidity and high order.

[0040] The molecular weight of the spandex prepared in this embodiment was tested, and the results were as follows: Figure 5 As shown by Figure 5 It can be seen that the weight-average molecular weight of the prepared polyurethane urea is 82,100, which has a relatively high molecular weight, and is beneficial to the improvement of its spinning and fiber properties.

[0041] Example 2

[0042] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0043] (1) 4-Hydroxyphenyl-4-hydroxybenzoate and toluene-2,4-diisocyanate in a molar ratio of 1:1.6 and catalysts dibutyltin dilaurate and N,N-dimethylacetamide were added to a prepolymerization reactor, with the amount of dibutyltin dilaurate being 0.5% of the total weight of the monomers. The mixture was stirred at 90°C for 100 minutes to prepare a prepolymer A with a mass fraction of 25%. Polypropylene glycol and toluene-2,4-diisocyanate in a molar ratio of 1:2 and N,N-dimethylformamide were added to the prepolymerization reactor, and the mixture was stirred at 110°C for 90 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B were mixed in a mass ratio of 3:7 and transported to a final polymerization reactor.

[0044] (2) dissolving and dispersing the chain extender propylene diamine and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the amount of the auxiliary agent is 0.8 wt%), and adding the chain extender to the final polymerization reactor for chain extension. The amount of the chain extender is 5 wt% of the total mass of the polyurethane urea solution. The chain extension reaction is carried out at 40° C. for 60 min to obtain a polyurethane urea solution with a weight average molecular weight of 80,000.

[0045] (3) The polyurethane urea solution was precipitated in an ethanol solution, filtered and dried, and then melt-spun to prepare high-performance spandex yarn at a spinning temperature of 250°C and a winding speed of 700 / min, resulting in high-performance spandex yarn with a strength of 2.3 / dtex, an elongation at break of 160%, and a limiting oxygen index of 28.5%.

[0046] Example 3

[0047] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0048] (1) Biphenyldiphenol and toluene-2,4-diisocyanate in a molar ratio of 1:1.5 and catalysts dibutyltin dilaurate and N,N-dimethylformamide are added to a prepolymerization reactor, the amount of dibutyltin dilaurate is 0.05% of the total weight of the monomers, and the mixture is stirred at 80°C for 100 minutes to prepare a prepolymer A with a mass fraction of 25%. Polyethylene glycol and toluene-2,4-diisocyanate in a molar ratio of 1:1.5 and N,N-dimethylformamide are added to the prepolymerization reactor, and the mixture is stirred at 80°C for 60 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B are mixed in a mass ratio of 7:3 and transported to a final polymerization reactor;

[0049] (2) dissolving and dispersing the chain extender butanediamine and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the amount of the auxiliary agent is 0.1 wt%), and adding the chain extender to the final polymerization reactor for chain extension. The amount of the chain extender is 10 wt% of the total mass of the polyurethane urea solution. The chain extension reaction is carried out at 90° C. for 60 min to obtain a polyurethane urea solution with a weight average molecular weight of 81,000.

[0050] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 47 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 70, and the filaments are solidified in a spinning tunnel filled with nitrogen at 230°C. The gas flow rate is 0.1m / s and the winding speed is 800m / min. High-performance spandex filaments with a strength of 2.32cN / dtex, an elongation at break of 155%, and a limiting oxygen index of 30% are obtained.

[0051] Example 4

[0052] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0053] (1) 4-Hydroxyphenyl-4-hydroxybenzoate, biphenol and toluene-2,5-diisocyanate in a molar ratio of 1:1.7, along with catalysts dibutyltin dilaurate and N,N-dimethylacetamide, are added to a prepolymerization reactor, with the amount of dibutyltin dilaurate being 0.3% of the total weight of the monomers. The mixture is stirred at high speed at 110°C for 80 minutes to prepare a prepolymer A with a mass fraction of 25%. Polytetramethylene ether glycol and toluene-2,5-diisocyanate in a molar ratio of 1:2 and N,N-dimethylformamide are added to a prepolymerization reactor, and the mixture is stirred at high speed at 80°C for 60 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B are mixed in a mass ratio of 9:1 and transported to a final polymerization reactor;

[0054] (2) The chain extender ethylenediamine butanediol (dosage ratio of 7:1) and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent are dissolved and dispersed in a polar amine solution (the amount of the auxiliary agent is 1.5 wt%), and added to the final polymerization reactor for chain extension. The amount of the chain extender is 25 wt% of the total mass of the polyurethane urea solution. The chain extension reaction conditions are: reaction at 40°C for 30 minutes, and a polyurethane urea solution with a weight average molecular weight of 86,000 is obtained;

[0055] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 55 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 70, and the filaments are solidified in a spinning tunnel filled with nitrogen at 280°C. The gas flow rate is 1 m / s and the winding speed is 900 m / min. High-performance spandex filaments with a strength of 3 cN / dtex, an elongation at break of 120%, and a limiting oxygen index of 30.7% are obtained.

[0056] Example 5

[0057] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0058] (1) 4,4'-bis(6-hydroxyethoxy)biphenyl and 4-hydroxyphenyl-4-hydroxybenzoate and 4,4'-methylenebis(phenyl isocyanate) were added into a prepolymerization reactor in a molar ratio of 1:1.7, along with catalysts stannous octoate and N,N-dimethylformamide. The amount of stannous octoate was 0.1% of the total weight of the monomers. The mixture was stirred at high speed at 100°C for 90 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor A with a mass fraction of 25%. Polypropylene glycol and toluene-2,4-diisocyanate were added into a prepolymerization reactor in a molar ratio of 1:2 and N,N-dimethylformamide. The mixture was stirred at high speed at 80°C for 60 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B were mixed in a mass ratio of 3:7;

[0059] (2) dissolving and dispersing the chain extenders propylene diamine and butanediol (in a ratio of 1:8) and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the auxiliary agent dosage is 2 wt%), and adding them to the final polymerization reactor for chain extension. The chain extender dosage is 10 wt% of the total mass of the polyurethane urea solution. The chain extension reaction conditions are 50 min at 60°C to obtain a polyurethane urea solution with a weight average molecular weight of 80,000.

[0060] (3) The polyurethane urea solution was precipitated in an ethanol solution, filtered and dried, and then melt-spun to prepare high-performance spandex yarn at a spinning temperature of 280°C and a winding speed of 600 m / min, resulting in high-performance spandex yarn with a strength of 2.1 cN / dtex, an elongation at break of 500%, and a limiting oxygen index of 29%.

[0061] Example 6

[0062] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0063] (1) 4,4'-bis(6-hydroxypropaneoxy)biphenyl and toluene-2,5-diisocyanate in a molar ratio of 1:1.5 and catalysts dibutyltin dilaurate and N,N-dimethylacetamide are added to a prepolymerization reactor, dibutyltin dilaurate accounts for 0.3% of the total weight of the monomers, and the mixture is stirred at 95°C for 100 minutes to prepare a prepolymer, which is then transported to a final polymerization reactor A with a mass fraction of 25%. Polytetramethylene glycol and toluene-2,4-diisocyanate in a molar ratio of 1:2 and N,N-dimethylformamide are added to the prepolymerization reactor, and the mixture is stirred at 110°C for 90 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B are mixed in a mass ratio of 4:6;

[0064] (2) dissolving and dispersing the chain extenders ethylenediamine and butanediol (in a ratio of 1:8) and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the amount of the auxiliary agent is 0.1 wt%), and adding them to the final polymerization reactor for chain extension. The amount of the chain extender is 15 wt% of the total mass of the polyurethane urea solution. The chain extension reaction is carried out at 90° C. for 30 min to obtain a polyurethane urea solution with a weight average molecular weight of 81,000.

[0065] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 39 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 60, and the filaments are solidified in a spinning tunnel filled with nitrogen at 250°C. The gas flow rate is 0.8 m / s and the winding speed is 750 m / min. High-performance spandex filaments with a strength of 2.45 cN / dtex, an elongation at break of 165%, and a limiting oxygen index of 29.5% are obtained.

[0066] Example 7

[0067] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0068] (1) 4,4'-bis(6-hydroxybutoxy)biphenyl and 4-hydroxyphenyl-4-hydroxybenzoate and 2,2'-dimethylbiphenyl isocyanate in a molar ratio of 1:1.9, together with catalysts stannous octoate and N,N-dimethylformamide, are put into a prepolymerization reactor, with the amount of stannous octoate being 0.3% of the total weight of the monomers. The mixture is stirred at high speed at 100°C for 90 minutes to prepare a prepolymer, which is then transported to a final polymerization reactor A with a mass fraction of 25%. Polypropylene glycol and 2,2'-dimethylbiphenyl isocyanate in a molar ratio of 1:1.5 and N,N-dimethylformamide are put into a prepolymerization reactor, and stirred at high speed at 110°C for 90 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymer A and B are mixed in a mass ratio of 6:4;

[0069] (2) dissolving and dispersing the chain extender propylene diamine and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the amount of the auxiliary agent is 0.5 wt%), and adding the chain extender to the final polymerization reactor for chain extension. The amount of the chain extender is 5 wt% of the total mass of the polyurethane urea solution. The chain extension reaction conditions are as follows: reacting at 40° C. for 60 min to obtain a polyurethane urea solution with a weight average molecular weight of 86,000.

[0070] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 57 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 55, and the filaments are solidified in a spinning tunnel filled with nitrogen at 280°C. The gas flow rate is 0.1 m / s and the winding speed is 950 m / min. High-performance spandex filaments with a strength of 3 cN / dtex, an elongation at break of 110%, and a limiting oxygen index of 31.5% are obtained.

[0071] Example 8

[0072] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0073] (1) 4,4'-bis(2-hydroxypentyloxy)biphenyl and 2,2'-dimethylbiphenyl isocyanate in a molar ratio of 1:1.9 and catalysts stannous octoate and N,N-dimethylformamide are added to a prepolymerization reactor, the amount of stannous octoate is 0.3% of the total weight of the monomers, and the mixture is stirred at 80°C for 80 minutes to prepare a prepolymer, which is then transported to a final polymerization reactor A with a mass fraction of 25%. Polytetramethylene glycol and 2,2'-dimethylbiphenyl isocyanate in a molar ratio of 1:2 and N,N-dimethylformamide are added to the prepolymerization reactor, and the mixture is stirred at 100°C for 60 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B are mixed at a mass ratio of 9:1;

[0074] (2) dissolving and dispersing the chain extender propylene diamine and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the auxiliary agent dosage is 0.1 wt%), and adding the chain extender to the final polymerization reactor for chain extension. The chain extender dosage is 25 wt% of the total mass of the polyurethane urea solution. The chain extension reaction conditions are 90° C. for 60 min to obtain a polyurethane urea solution with a weight average molecular weight of 86,000.

[0075] (3) The polyurethane urea solution was precipitated in an ethanol solution, filtered and dried, and then melt-spun to prepare high-performance spandex yarn at a spinning temperature of 265°C and a winding speed of 900 m / min, resulting in high-performance spandex yarn with a strength of 2.95 cN / dtex, an elongation at break of 140%, and a limiting oxygen index of 29.8%.

[0076] Example 9

[0077] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0078] (1) 4,4'-bis(2-hydroxydodecyloxy)biphenyl and biphenol and 2,2'-dimethylbiphenyl isocyanate in a molar ratio of 1:2.1, along with catalysts dibutyltin sulfide and N,N-dimethylformamide, are added to a prepolymerization reactor, with the amount of dibutyltin sulfide being 0.45% of the total mass of the monomers. The mixture is stirred at high speed at 110°C for 80 minutes to prepare a prepolymer A with a mass fraction of 25%. Polypropylene glycol and azobenzene diisocyanate in a molar ratio of 1:1.5 and N,N-dimethylformamide are added to the prepolymerization reactor, and the mixture is stirred at high speed at 80°C for 90 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B are mixed in a mass ratio of 1:9 and transported to a final polymerization reactor;

[0079] (2) dissolving and dispersing the chain extender propylene diamine and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the amount of the auxiliary agent is 1.5 wt%), and adding the chain extender to the final polymerization reactor for chain extension. The amount of the chain extender is 20 wt% of the total mass of the polyurethane urea solution. The chain extension reaction conditions are as follows: reacting at 90° C. for 30 min to obtain a polyurethane urea solution with a weight average molecular weight of 80,000.

[0080] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 43 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 65, and the filaments are solidified in a spinning tunnel filled with nitrogen at 280°C. The gas flow rate is 0.8 m / s and the winding speed is 650 m / min. High-performance spandex filaments with a strength of 2.4 cN / dtex, an elongation at break of 170%, and a limiting oxygen index of 29.7% are obtained.

[0081] Example 10

[0082] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0083] (1) 4-Hydroxyphenyl-4-hydroxybenzoate, biphenyl diphenol and toluene-2,5-diisocyanate are added to the prepolymerization reactor in a molar ratio of 1:1.5, along with catalysts stannous octoate and N,N-dimethylformamide. The amount of stannous octoate is 0.5% of the total weight of the monomers. The mixture is stirred at high speed at 110°C for 100 minutes to prepare a prepolymer, which is then transported to the final polymerization reactor A. The mass fraction of the prepolymer is 25%. Polypropylene glycol and 2,2'-dimethylbiphenyl isocyanate are added to the prepolymerization reactor in a molar ratio of 1:1.5 and N,N-dimethylformamide. The mixture is stirred at high speed at 60°C for 90 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymer A and B are mixed in a mass ratio of 2:8;

[0084] (2) dissolving and dispersing the chain extender propylene diamine and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the auxiliary agent dosage is 1 wt%), and adding them to the final polymerization reactor for chain extension. The chain extender dosage is 5 wt% of the total mass of the polyurethane urea solution. The chain extension reaction conditions are: reacting at 40° C. for 30 min, and obtaining a polyurethane urea solution with a weight average molecular weight of 83,000.

[0085] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 47 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 65, and the filaments are solidified in a spinning tunnel filled with nitrogen at 280°C. The gas flow rate is 0.8 m / s and the winding speed is 850 m / min. High-performance spandex filaments with a strength of 2.6 cN / dtex, an elongation at break of 140%, and a limiting oxygen index of 29.85% are obtained.

[0086] Example 11

[0087] A method for preparing spandex fiber according to this embodiment includes the following steps:

[0088] (1) 4-Hydroxyphenyl-4-hydroxybenzoate and 4,4'-bis(2-hydroxypentyloxy)biphenyl and toluene-2,5-diisocyanate in a molar ratio of 1:2.1 and catalysts dibutyltin dilaurate and N,N-dimethylacetamide are added to a prepolymerization reactor, the amount of dibutyltin dilaurate is 0.5% of the total weight of the monomers, and the mixture is stirred at 95°C for 90 minutes to prepare a prepolymer, which is transported to the final polymerization reactor A with a mass fraction of 25%. Polypropylene glycol and toluene-2,5-diisocyanate in a molar ratio of 1:2 and N,N-dimethylformamide are added to the prepolymerization reactor, and the mixture is stirred at 110°C for 90 minutes to prepare a prepolymer B with a mass fraction of 30%. Prepolymers A and B are mixed in a mass ratio of 1:9;

[0089] (2) dissolving and dispersing the chain extender propylene diamine and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the amount of the auxiliary agent is 2 wt%), and adding the chain extender to the final polymerization reactor for chain extension. The amount of the chain extender is 25 wt% of the total mass of the polyurethane urea solution. The chain extension reaction is carried out at 40° C. for 30 min to obtain a polyurethane urea solution with a weight average molecular weight of 81,000.

[0090] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 43 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 65, and the filaments are solidified in a spinning tunnel filled with nitrogen at 280°C. The gas flow rate is 0.8 m / s and the winding speed is 700 m / min. High-performance spandex filaments with a strength of 2.35 cN / dtex, an elongation at break of 170%, and a limiting oxygen index of 30% are obtained.

[0091] Comparative Example

[0092] The preparation method of a spandex fiber of this comparative example comprises the following steps:

[0093] (1) Polytetramethylene ether diol and 4,4'-methylenebis(phenyl isocyanate) were added into a prepolymerization reactor in a molar ratio of 1:1.5, and stirred at high speed at 90°C for 80 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor;

[0094] (2) dissolving and dispersing the chain extender ethylenediamine and butanediol (in a ratio of 1:9) and the auxiliary agents light stabilizer, pigment, antioxidant, and antibacterial agent in a polar amine solution (the auxiliary agent dosage is 0.1 wt%), and adding them into the final polymerization reactor through a three-position injection method to chain extend the prepolymer to obtain a polyurethane urea solution with a weight average molecular weight of 50,000;

[0095] (3) The polyurethane urea solution is matured to obtain a spinning solution with a viscosity of 1-3 Pa.s, which is transported to a spinning manifold through a metering pump and extruded through a spinneret. The number of spinnerets is 60, and the filaments are solidified in a spinning tunnel filled with nitrogen at 280°C. The gas flow rate is 0.1 m / s and the winding speed is 600 m / min. Spandex filaments with a strength of 1.2 cN / dtex, an elongation at break of 760%, and a limiting oxygen index of 24% are obtained.

[0096] Implementation effect analysis

[0097] In the comparative example, the molecular structure and chain extension method of conventional spandex are used. Since its molecular chain does not contain aromatic diol compounds, its elongation at break is greater than 700%, its elasticity is high, but its breaking strength is only 1.2 cN / dtex, its limiting oxygen index is only 24%, and it does not have flame retardant properties.

[0098] In Example 1 of the present invention, aromatic diols are introduced through molecular structure design to improve the rigidity of the molecular chain, so that it can be processed by dry spinning and melt spinning. While greatly improving the mechanical properties of the spandex fiber (>2.0 cN / dtex), the heat resistance is also effectively improved. Figure 1 As shown by Figure 1 It can be seen that the spandex fiber of Example 1 has high thermal stability (thermal decomposition temperature 303° C.) and excellent flame retardancy (limiting oxygen index 28.7%), thereby obtaining a high-performance spandex fiber.

[0099] The spandex spinning solutions prepared in Example 2 and the comparative example were subjected to rheological viscosity tests using a flat plate rotational rheometer at a shear rate range of 0.1-100 / s and a test temperature of 35°C. The results are shown in FIG. Figure 4 As shown by Figure 4 It can be seen that Example 1 has a higher viscosity and the viscosity decreases with the increase of shear rate, and has the rheological property of shear thinning, while the viscosity of the comparative spandex stock solution is lower and more stable (not sensitive to changes in shear rate); this shows that the spandex molecular chain of Example 1 has greater rigidity and higher molecular weight, and has excellent molding and processing performance.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing spandex fiber, characterized in that: The steps are: (1) Aromatic diol, diisocyanate and catalyst are dissolved in polar amine solution and reacted by high-speed stirring to obtain prepolymer A. (2) Dissolve the polyglycol and diisocyanate in a polar amine solution and perform reaction II with high-speed stirring to obtain prepolymer B; (3) Prepolymer A and prepolymer B are mixed and placed in a reactor, and then a polar amine solution containing a chain extender and an auxiliary agent is added to obtain a polyurethane urea solution through a chain extension reaction; (4) High-performance spandex yarn is produced by dry spinning or melt spinning of polyurethane urea solution; In step (1), the aromatic diol is selected from one or two of the following structures: 、 、 、 Where n is a positive integer from 2 to 12; The diisocyanate is any one of 4,4'-methylenebis(phenyl isocyanate), toluene-2,4-diisocyanate, toluene-2,5-diisocyanate, 2,2'-dimethyldiphenyl isocyanate and azophenyl diisocyanate; the catalyst is any one of stannous octoate, dibutyltin dilaurate and dibutyltin sulfide; and the polar amine solution is N,N-dimethylformamide or N,N-dimethylacetamide.

2. The method for preparing spandex fiber according to claim 1, wherein: The molar ratio of the aromatic diol to the diisocyanate is 1:1.5-2.1; the amount of catalyst added is 0.01-0.5wt% of the total weight of the monomers; the reaction temperature of the high-speed stirring reaction I is 80-110°C and the time is 80-100 minutes.

3. The method for preparing spandex fiber according to claim 2, wherein: The polyglycol in step (2) is any one of polyethylene glycol, polypropylene glycol and polytetramethylene glycol; the polyglycol and diisocyanate are in a molar ratio of 1:1.2-2; the reaction temperature of high-speed stirring reaction II is 80-110°C and the reaction time is 60-90 minutes.

4. The method for preparing spandex fiber according to claim 3, wherein: In step (3), the chain extender is a diamine or a diol, wherein the diamine is any one of ethylenediamine, propylenediamine and butanediamine; the diol is any one of butanediol and polyethylene glycol with a molecular weight of ≤600; and the auxiliary agent is one or more of a light stabilizer, a pigment, an antioxidant and an antibacterial agent.

5. The method for preparing spandex fiber according to claim 4, wherein: The mass ratio of the prepolymer A to the prepolymer B is 3:7-9:1; the amount of the chain extender is 5-25wt% of the total mass of the polyurethane urea solution; the amount of the auxiliary agent is 0.1-2wt% of the total mass of the polyurethane urea solution; and the chain extension reaction is carried out at 40-90°C for 30-60 minutes.

6. The method for preparing spandex fiber according to claim 5, characterized in that: The dry spinning conditions are as follows: the viscosity of the matured polyurethane urea solution is 20-80 Pa.s, the number of spinnerets is 60-100, the temperature of the hot air or hot nitrogen in the spinning tunnel is 230-280°C, the gas flow rate is 0.1-1 m / s, and the winding speed is 600-1000 m / min; the melt spinning conditions are as follows: the spinning temperature is 250-280°C and the winding speed is 800-1500 m / min.

7. A spandex fiber prepared by the method according to any one of claims 1 to 6, characterized in that: The spandex fiber has a breaking strength greater than 2.0 cN / dtex, a breaking elongation of 100-700%, a fineness of 5-40D, a thermal decomposition temperature greater than 280° C., and a limiting oxygen index greater than 28%.

8. Textiles prepared based on the spandex fiber according to claim 7.

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