High-performance flame-retardant spandex fiber and preparation method thereof

Abstract

The invention provides a high-performance flame-retardant spandex fiber and a preparation method thereof, belongs to the technical field of chemical fiber manufacturing, and aims to solve the technical problem of poor flame retardance of flame-retardant polyurethane. The preparation method comprises the following steps: mixing polydihydric alcohol and diisocyanate, and carrying out prepolymerization reaction to obtain a prepolymer; dissolving a phosphorus-containing dihydroxyl compound, a nitrogen-containing dihydroxyl compound and a catalyst in a polar amine solution to prepare a mixed solution, mixing the mixed solution with the prepolymer, and performing polymerization reaction to obtain low-molecular-weight polyurethane containing phosphorus in a molecular chain; the preparation method comprises the following steps: mixing low-molecular-weight polyurethane with a chain extender, and carrying out chain extension reaction to obtain a phosphorus-containing polyurethane urea solution; and curing the phosphorus-containing polyurethane urea solution, and spinning to obtain the high-performance flame-retardant spandex. By utilizing the cross-linking characteristic of a nitrogen-containing element at a high temperature and the phosphorus-nitrogen synergistic flame-retardant advantage, the problems that a flame retardant in the conventional technology is poor in compatibility with spandex macromolecules and easy to fall off are solved, the acting force of a molecular chain is also improved, and the viscosity of a spandex spinning stock solution is improved, so that the spandex spinning stock solution can meet the requirement of high-speed dry spinning; the spandex is endowed with excellent flame retardant property, mechanical property and controllable elasticity, the preparation efficiency of the spandex is improved, and the cost is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical fiber manufacturing, and in particular relates to a high-performance flame-retardant spandex fiber and a preparation method thereof. Background Art

[0002] Spandex has an elasticity that is unmatched by other synthetic fibers, with an elongation at break of up to 800% and an elastic recovery rate of over 95%. It is widely used in textiles and clothing, medical and health care, sports, and national defense and military industries. A small amount of it can give textiles excellent elasticity, comfort, and shape retention. It is an indispensable fiber material for high-end textiles and plays an important role in the national economy and national defense construction.

[0003] Conventional spandex polymers are prepared by stepwise polymerization and chain extension of aliphatic polydiols and aromatic diisocyanates. The presence of a large amount of aliphatic diols in the molecular chain makes conventional spandex have poor flame retardancy and heat resistance, which cannot meet the application of spandex in high-end fields. In order to improve the flame retardancy of spandex, small molecule flame retardants are usually added during the polymerization or spinning of spandex, but there are defects such as poor compatibility between flame retardants and spandex macromolecules, high addition of flame retardants, easy shedding, and affecting spinnability and mechanical properties.

[0004] For example, patent publication number CN103361974A introduces a method for preparing flame-retardant spandex fiber, which uses a flame retardant prepared from triethyl phosphate, methanol and octabromoether solution, soaks the spandex fabric in the prepared flame retardant solution, heats it to 50°C and soaks it for a certain period of time, and then takes it out to dry. The fabric has high flame retardant properties. However, the flame retardant properties of the spandex fabric prepared by this method still have many shortcomings, because the flame retardant is attached to the surface of the fiber. After multiple washings, the flame retardant falls off, and the flame retardant properties of the fiber are also weakened. In addition, the spandex product with flame retardant attached to the surface will also feel astringent and hard. It is not conducive to long-term use and commercial production.

[0005] Patent Publication No. CN114672897A introduces a method for preparing antistatic flame-retardant spandex fiber. The antistatic flame-retardant spandex masterbatch is obtained by adding spandex slices, nonionic antistatic agent, anionic surfactant, and phosphate flame retardant into a high-speed mixer for high-speed dispersion and mixing, and then melt spinning is performed to obtain antistatic and high-strength flame-retardant spandex fiber. However, this method uses spandex slices, nonionic antistatic agent, anionic surfactant, and phosphate flame retardant to mix together by melting, so that the breaking strength of the fiber prepared by this method is only 0.93cN / dtex~0.98cN / dtex, and the elongation at break is 450%~500%. The addition of flame retardant will lead to a significant decrease in the breaking strength and elongation at break. In addition, the limiting oxygen index is 27~30%, and the improvement is also small. Due to the use of melt spinning, the fiber fineness is large, and fine denier spandex yarn cannot be prepared, and optimization and improvement are still needed.

[0006] Patent CN103590138A discloses a method for preparing a flame-retardant polyurethane elastic fiber, which ensures permanent flame retardancy by copolymerizing with a phosphorus flame retardant; blending with a small amount of halogen-free phosphonate flame retardants, melamine flame retardants, aluminum oxide flame retardants and other flame retardant additives to further ensure excellent flame retardant properties and reduce burning dripping to prepare excellent spinning solution and subsequent dry spinning. In this patent, the prepared fiber has permanent flame retardancy by copolymerizing the phosphorus flame retardant into the polyurethane molecular chain. However, the flame retardancy of the fiber is poor by copolymerization alone, and additional flame retardants still need to be added to the system to meet the requirements. Summary of the invention

[0007] In view of the technical problem of poor flame retardancy of flame retardant spandex, the present invention proposes a high-performance flame retardant spandex fiber and a preparation method thereof, which utilizes the cross-linking characteristics of nitrogen-containing units at high temperatures and the synergistic flame retardancy of phosphorus and nitrogen, not only solving the problems of poor compatibility and easy shedding of conventional flame retardants with spandex macromolecules, but also improving the force of the molecular chains and the viscosity of the spandex spinning solution, so that it can meet the requirements of high-speed dry spinning, giving the spandex excellent flame retardant properties, mechanical properties and controllable elasticity, improving the efficiency of spandex preparation, and greatly reducing costs.

[0008] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] A high-performance flame-retardant spandex fiber and a preparation method thereof. The details are as follows:

[0010] (1) Prepolymerization: Polyglycol and diisocyanate are placed in a prepolymerization reactor and stirred at high speed to obtain a prepolymer.

[0011] The polyglycol is a polyether glycol or polyester glycol with a molecular weight of 1000-3000;

[0012] The polyether diol is one of polytetrahydrofuran ether diol, polyethylene glycol and polypropylene glycol;

[0013] The polyester diol is one of polybutylene succinate diol, polybutylene adipate diol and polybutylene sebacate diol.

[0014] (2) Polymerization: The phosphorus-containing dihydroxy compound and the catalyst are dissolved in a polar amine solution, transported to a final polymerization reactor, and reacted with the prepolymer to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender and the auxiliary agent are dissolved and dispersed in the polar amine solution, and added to the final polymerization reactor by multi-point injection to extend the chain of the prepolymer containing phosphorus to obtain a phosphorus-containing polyurethane urea solution.

[0015] The phosphorus-containing dihydroxy compound is one of the following structures:

[0016]

[0017] The nitrogen-containing dihydroxy compound is one of the following structures:

[0018]

[0019] The molar ratio of phosphorus-containing and nitrogen-containing dihydroxy compounds is 1:9-9:1, and the molar ratio of the total amount of the two to the polyglycol is 1:9-5:5;

[0020] The catalyst is one of stannous octoate, dibutyltin dilaurate and dibutyltin sulfide, and the amount used is 0.01-0.5wt% of the total weight of the monomer;

[0021] The chain extender is a mixture of diamine and diol, the dosage ratio of the two is 1:9-9:1, and the dosage is 20-50 mol% of the diisocyanate, and the feed is injected through the 3-5 feed ports; wherein the diamine is one of the following structures;

[0022]

[0023] The diol is one of the following structures.

[0024]

[0025] The auxiliary agents are light stabilizers, antioxidants and antibacterial agents, and the dosage is 0.1-3wt% of the total mass of the spinning solution.

[0026] The polar amine solution is N,N-dimethylformamide or N,N-dimethylacetamide, and its usage is 3-5 times of the total mass of the dihydroxy compound.

[0027] (3) Spinning: The phosphorus-containing polyurethane urea solution is matured to obtain a spinning solution, which is then transported to a 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 flame-retardant spandex filaments.

[0028] The viscosity of the spinning solution is 20-50 Pa.s, the number of spinneret holes is 60-300, 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 600-1500m / min.

[0029] The high-performance flame-retardant spandex fiber has a weight average molecular weight greater than 90,000, a breaking strength greater than 1.3 cN / dtex, and a limiting oxygen index greater than 30%.

[0030] Beneficial effects of the present invention: The present invention copolymerizes aromatic phosphorus- and nitrogen-containing dihydroxy compounds with polyglycols and isocyanates, and uses phosphorus-containing diols for chain extension, wherein the chain extension reaction temperature is 40-80°C and the time is 30-90 minutes. Phosphorus-containing spandex spinning stock solution with a phosphorus content greater than 1.4wt% can be prepared by continuous polymerization, and high-performance flame-retardant spandex fibers can be prepared by dry spinning. Through molecular structure design, phosphorus-containing units, azo (-N=N-) and Schiff base (-N=CH-) are introduced into the spandex macromolecular chain. The cross-linking characteristics of azo and Schiff base units at high temperature and the synergistic flame retardant advantages of phosphorus and nitrogen are utilized to not only solve the problems of poor compatibility and easy shedding between conventional flame retardants and spandex macromolecules, but also increase the force of the molecular chain and the viscosity of the spandex spinning solution. In addition, the chain extender is added by multi-position injection, so that the chain extender can be quickly dispersed into the prepolymer solution, which improves the uniformity of the chain extension reaction and obtains a high molecular weight and high uniformity spinning solution, so that it can meet the requirements of high-speed dry spinning, and finally gives the spandex excellent flame retardant properties, mechanical properties and controllable elasticity, and makes the fineness 5-40D adjustable and controllable, thereby improving the spandex preparation efficiency and greatly reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0032] Figure 1 2 are the thermal gravimetric loss curves of the spandex in Example 1 and Comparative Example 1.

[0033] Figure 2This is a microscope image of the apparent morphology of the spandex in Example 1 (magnification 1000x).

[0034] Figure 3 This is the GPC curve of the flame retardant spandex in Example 1.

[0035] Figure 4 The rheological curves of Example 1 and Comparative Example 1 are shown.

[0036] Figure 5 This is the strength curve in Example 1.

[0037] Figure 6 This is a cone combustion picture of Example 1. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0041] Polytetramethylene ether diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor at a molar ratio of 1:1.8, and reacted at 90°C with high-speed stirring for 80 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, a phosphorus-containing dihydroxy compound DOPO-HQ and a nitrogen-containing dihydroxy compound NBP6 were dissolved in an N,N-dimethylformamide solution (DMF) at a molar ratio of 9:1, and the amount of DMF was 3 times that of the dihydroxy compound, and 0.01wt% of a catalyst stannous octoate was added, and transported to a final polymerization reactor (the total amount of DOPO-HQ and NBP6 was 1 / 2 of the polytetramethylene ether diol), and reacted with the prepolymer at 60°C for 10 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, a chain extender ethylenediamine and N,N-dihydroxyethyl- Diethyl phosphate (DEPHA) (dosage ratio of 1:9) and auxiliary light stabilizer 119, antioxidant 1076, and antibacterial agent quaternary ammonium salt are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 0.1wt%), and added to the final polymerization reactor by a 3-position injection method, and the prepolymer containing phosphorus element is reacted at 40°C for 60 minutes to extend the chain, and obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 119,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 26Pa.s, which is transported to a spinning box through a metering pump and extruded through a spinneret, with a spinneret number of 60, and the filaments are solidified in a spinning tunnel filled with 280°C nitrogen, with a gas flow rate of 0.1m / s and a winding speed of 600m / min, to obtain a high-performance flame-retardant spandex yarn with a strength of 1.81cN / dtex, a breaking elongation of 250%, and a limiting oxygen index of 34.2%. The thermal weight loss curve of the obtained spandex is as follows Figure 1 As shown, it can be seen that the initial thermal decomposition temperature and the residual carbon content at 650°C of the spandex fiber prepared in Example 1 are 326°C and 14.96%, respectively, which are 63°C and 10.69% higher than those of the comparative example fiber; Figure 2 This is a morphology diagram of the spandex fiber in Example 1, showing that the fiber fineness is uniform and the surface is relatively smooth; Figure 3 is the GPC curve of the spandex fiber in Example 1, and its weight average molecular weight is 119,000; Figure 4 This is the rheological curve of the spandex spinning solution in Example 1. It can be seen that compared with the control example, the spandex spinning solution in Example 1 has a higher viscosity, indicating that its molecular chain has greater rigidity and force, and has a higher molecular weight, which is beneficial to the improvement of the performance of the spandex fiber. Figure 5 This is the stress-strain curve of the spandex fiber of Example 1. The fiber has a fineness of 10D, a breaking strength of 19.9 cN, and a strength of 1.81 cN / dtex, and has excellent mechanical properties. Figure 6This is a photo of the spandex fiber of Example 1 after hot pressing and then undergoing a cone burning test. It can be seen that the fiber has a compact carbon layer structure after burning, indicating excellent flame retardancy.

[0042] Example 2

[0043] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0044] Polyethylene glycol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:1.9, and reacted at 80°C with high-speed stirring for 85 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound MH-PPOA and the nitrogen-containing dihydroxy compound NBP6 were dissolved in N,N-dimethylacetamide solution (DMAC) in a molar ratio of 8:2, the amount of DMAC was 5 times that of the dihydroxy compound, and 0.05wt% of the catalyst dibutyltin dilaurate was added, and transported to a final polymerization reactor (the total amount of MH-PPOA and NBP6 was 1 / 4 of that of polyethylene glycol), and reacted with the prepolymer at 55°C for 15 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender propylenediamine, N,N-dihydroxyethyl-diethylamine, and the amount of ... Phosphate ester (DEPHA) (dosage ratio of 9:1) and auxiliary light stabilizer 622, antioxidant 168, and antibacterial agent quaternary ammonium salt are dissolved and dispersed in polar amine solution (the dosage of the auxiliary is 0.5wt%), and added into the final polymerization reactor by 3-position injection, and the prepolymer containing phosphorus element is extended by reaction at 50℃ for 60min to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 128,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 30Pa.s, which is transported to the spinning box through a metering pump and extruded by spinneret, with the number of spinneret holes being 80. The filaments are solidified in a spinning tunnel filled with 275℃ nitrogen, with a gas flow rate of 0.2m / s and a winding speed of 700m / min, to obtain high-performance flame-retardant spandex with a strength of 1.83cN / dtex, a breaking elongation of 330%, and a limiting oxygen index of 31.5%.

[0045] Example 3

[0046] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0047] Polypropylene glycol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor at a molar ratio of 1:2.0, and reacted at 70°C with high-speed stirring for 90 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound DOPO-HQ and the nitrogen-containing dihydroxy compound HPIMP were dissolved in an N,N-dimethylformamide solution (DMF) at a molar ratio of 7:3, the amount of DMF was 4 times that of the dihydroxy compound, and 0.1wt% of the catalyst dibutyltin sulfide was added, and transported to a final polymerization reactor (the total amount of DOPO-HQ and HPIMP was 3 / 7 of that of polypropylene glycol), and reacted with the prepolymer at 50°C for 20 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender butanediamine, N,N-dihydroxyethyl-diethylamine, and the amount of the chain extender was 30mol% of the diisocyanate. Phosphate (DEPHA) (dosage ratio of 2:8) and auxiliary light stabilizer 622, antioxidant 168, and antibacterial agent quaternary ammonium salt are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 1wt%), and added to the final polymerization reactor through a 5-position injection method, and the prepolymer containing phosphorus element is extended at 80°C for 30 minutes to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 131,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 33Pa.s, which is transported to the spinning box through a metering pump and extruded through a spinneret, with a spinneret number of 100, and the filaments are solidified in a spinning tunnel filled with 235°C nitrogen, with a gas flow rate of 0.9m / s and a winding speed of 800m / min, to obtain a high-performance flame-retardant spandex yarn with a strength of 1.76cN / dtex, an elongation at break of 360%, and a limiting oxygen index of 31.1%.

[0048] Example 4

[0049] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0050] The polybutylene succinate diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:2.1, and reacted at 65°C with high-speed stirring for 95 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound MH-PPOA and the nitrogen-containing dihydroxy compound HPIMP were dissolved in N,N-dimethylacetamide solution (DMAC) in a molar ratio of 6:4, the amount of DMAC was 3.5 times that of the dihydroxy compound, and 0.15wt% of the catalyst stannous octoate was added, and transported to a final polymerization reactor (the total amount of MH-PPOA and HPIMP was 2 / 3 of the polybutylene succinate diol), and reacted with the prepolymer at 45°C for 25 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender cyclohexanediamine and N,N-diisocyanate with a substance mass of 40mol% were added. Hydroxyethyl-diethyl phosphate (DEPHA) (dosage ratio of 8:2) and auxiliary light stabilizer 292, antioxidant 1010, and antibacterial chitosan were dissolved and dispersed in a polar amine solution (the dosage of the auxiliary was 1.5wt%), and added to the final polymerization reactor by 5-position injection. The prepolymer containing phosphorus element was reacted at 60°C for 70 minutes to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 135,000. Finally, the phosphorus-containing After aging, the polyurethane urea solution is obtained to obtain a spinning solution with a viscosity of 36 Pa.s, which is transported to the spinning box through a metering pump and extruded through a spinneret. The number of spinneret holes is 120. The filaments are solidified in a spinning tunnel filled with 255°C nitrogen. The gas flow rate is 0.8m / s and the winding speed is 900m / min. High-performance flame-retardant spandex yarns with a strength of 1.66cN / dtex, a breaking elongation of 390% and a limiting oxygen index of 32.5% are obtained.

[0051] Example 5

[0052] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0053] The polybutylene adipate diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:2.2, and reacted at 60°C with high-speed stirring for 100 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound DOPO-HQ and the nitrogen-containing dihydroxy compound NBP6 were dissolved in N,N-dimethylformamide solution (DMF) in a molar ratio of 5:5, the amount of DMF was 4.5 times that of the dihydroxy compound, and 0.2wt% of the catalyst dibutyltin dilaurate was added, and transported to a final polymerization reactor (the total amount of DOPO-HQ and NBP6 was equal to that of the polybutylene adipate diol), and reacted with the prepolymer at 40°C for 30 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender p-phenylenediamine and N,N-diisocyanate with a substance mass of 45mol% were added. Hydroxyethyl-diethyl phosphate (DEPHA) (dosage ratio of 3:7) and auxiliary light stabilizer 119, antioxidant 168, and antibacterial agent chitosan are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 2wt%), and added to the final polymerization reactor by a 3-position injection method, and the prepolymer containing phosphorus element is reacted at 70°C for 60 minutes to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 115,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 39Pa.s, which is transported to a spinning box through a metering pump and extruded by spinneret. The number of spinneret holes is 140, and the filaments are solidified in a spinning tunnel filled with 245°C nitrogen. The gas flow rate is 0.3m / s and the winding speed is 1000m / min. High-performance flame-retardant spandex with a strength of 1.59cN / dtex, an elongation at break of 440%, and a limiting oxygen index of 33.2% are obtained.

[0054] Example 6

[0055] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0056] The polybutylene sebacate diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:2.3, and reacted at 75°C with high-speed stirring for 82 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound MH-PPOA and the nitrogen-containing dihydroxy compound NBP6 were dissolved in N,N-dimethylacetamide solution (DMAC) in a molar ratio of 4:6, the amount of DMAC was 3 times that of the dihydroxy compound, and 0.25wt% of the catalyst dibutyltin sulfide was added, and transported to a final polymerization reactor (the total amount of MH-PPOA and NBP6 was 2 / 3 of the polybutylene sebacate diol), and reacted with the prepolymer at 35°C for 25 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender ethylenediamine and N,N-dihydroxyethylene with a substance mass of 50mol% of diisocyanate were added to form a polyurethane. DEPHA (dosage ratio of 7:3) and auxiliary light stabilizer 622, antioxidant 1010, and antibacterial agent zinc oxide are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 2.5wt%), and added to the final polymerization reactor by a 3-position injection method, and the prepolymer containing phosphorus element is extended by reacting at 50°C for 90min to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 136,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 40Pa.s, which is transported to the spinning box through a metering pump and extruded by spinneret, with a spinneret hole number of 160, and the filaments are solidified in a spinning tunnel filled with 270°C nitrogen, with a gas flow rate of 0.7m / s and a winding speed of 1100m / min, to obtain a high-performance flame-retardant spandex yarn with a strength of 1.55cN / dtex, a breaking elongation of 485%, and a limiting oxygen index of 33.5%.

[0057] Example 7

[0058] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0059] The polytetramethylene ether diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor at a molar ratio of 1:2.4, and reacted at 85°C with high-speed stirring for 87 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound MH-PPOA and the nitrogen-containing dihydroxy compound HPIMP were dissolved in N,N-dimethylacetamide solution (DMF) at a molar ratio of 3:7, the amount of DMF was 4 times that of the dihydroxy compound, and 0.3wt% of the catalyst stannous octoate was added, and transported to a final polymerization reactor (the total amount of MH-PPOA and HPIMP was equal to that of the polytetramethylene ether diol), and reacted with the prepolymer at 30°C for 30 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender propylene diamine and N,N-dihydroxyethyl-diisocyanate with a substance mass of 40mol% were added. Ethyl phosphate (DEPHA) (dosage ratio of 4:6) and auxiliary light stabilizer 292, antioxidant 1076, and antibacterial agent quaternary ammonium salt are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 2.7wt%), and added to the final polymerization reactor by a 3-position injection method, and the prepolymer containing phosphorus element is reacted at 70°C for 30 minutes to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 134,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 38Pa.s, which is transported to the spinning box through a metering pump and extruded by spinneret, with the number of spinneret holes being 300. The filaments are solidified in a spinning tunnel filled with 230°C nitrogen, with a gas flow rate of 1m / s and a winding speed of 1500m / min, to obtain high-performance flame-retardant spandex with a strength of 1.49cN / dtex, an elongation at break of 640%, and a limiting oxygen index of 33.9%.

[0060] Example 8

[0061] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0062] Polyethylene glycol and 4,4'-methylenebis(phenyl isocyanate) were added into a prepolymerization reactor in a molar ratio of 1:2.5, and reacted at 60°C with high-speed stirring for 100 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, a phosphorus-containing dihydroxy compound DOPO-HQ and a nitrogen-containing dihydroxy compound NBP6 were dissolved in an N,N-dimethylformamide solution (DMAC) in a molar ratio of 2:8, the amount of DMAC being 5 times that of the dihydroxy compound, and 0.35wt% of the catalyst dibutyltin dilaurate was added, and transported to a final polymerization reactor (the total amount of DOPO-HQ and NBP6 being 3 / 7 of that of polyethylene glycol), and reacted with the prepolymer at 30°C for 25 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, a chain extender of butanediamine and N,N-dihydroxyethyl with a substance mass of 35mol% of diisocyanate was added; -Diethyl phosphate (dosage ratio of 5:5) and auxiliary light stabilizer 622, antioxidant 1076, and antibacterial agent chitosan are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 3wt%), and are added to the final polymerization reactor by a 4-position injection method. The prepolymer containing phosphorus element is reacted at 50°C for 90 minutes to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 142,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 50Pa.s, which is transported to a spinning box through a metering pump and extruded through a spinneret. The number of spinneret holes is 180, and the filaments are solidified in a spinning tunnel filled with 265°C nitrogen. The gas flow rate is 0.4m / s and the winding speed is 1400m / min. High-performance flame-retardant spandex with a strength of 1.45cN / dtex, a breaking elongation of 660%, and a limiting oxygen index of 32.5% are obtained.

[0063] Example 9

[0064] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0065] Polypropylene glycol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor at a molar ratio of 1:2.15, and reacted at 55°C with high-speed stirring for 90 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, a phosphorus-containing dihydroxy compound MH-PPOA and a nitrogen-containing dihydroxy compound HPIMP were dissolved in an N,N-dimethylformamide solution (DMF) at a molar ratio of 1:9, the amount of DMF was 4.5 times that of the dihydroxy compound, and 0.4wt% of the catalyst dibutyltin sulfide was added, and transported to a final polymerization reactor (the total amount of MH-PPOA and HPIMP was 1 / 4 of that of polypropylene glycol), and reacted with the prepolymer at 35°C for 20 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, a chain extender cyclohexanediamine, N,N-dihydroxyethyl-diethylamine, and a substance mass of 20mol% of diisocyanate were added to form a polyurethane. Phosphate (DEPHA) (dosage ratio of 6:4) and auxiliary light stabilizer 292, antioxidant 168, and antibacterial agent zinc oxide are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 2.2wt%), and added to the final polymerization reactor by a 3-position injection method, and the prepolymer containing phosphorus element is extended by reacting at 70°C for 40min to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 132,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 35Pa.s, which is transported to the spinning box through a metering pump and extruded by spinneret, with a spinneret number of 200, and the filaments are solidified in a spinning tunnel filled with 260°C nitrogen, with a gas flow rate of 0.6m / s and a winding speed of 1300m / min, to obtain a high-performance flame-retardant spandex yarn with a strength of 1.40cN / dtex, a breaking elongation of 700%, and a limiting oxygen index of 34.2%.

[0066] Example 10

[0067] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0068] The polybutylene succinate diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:2.45, and reacted at 80°C with high-speed stirring for 95 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound DOPO-HQ and the nitrogen-containing dihydroxy compound NBP6 were dissolved in N,N-dimethylacetamide solution (DMAC) in a molar ratio of 1:9, the amount of DMAC was 3.5 times that of the dihydroxy compound, and 0.45wt% of the catalyst stannous octoate was added, and transported to a final polymerization reactor (the total amount of DOPO-HQ and NBP6 was 1 / 4 of the polybutylene succinate diol), and reacted with the prepolymer at 40°C for 15 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender p-phenylenediamine and N,N-dihydroxy with a substance mass of 50mol% of diisocyanate were added to form a polyurethane having a molecular weight of 1.5-1.0. Ethyl-diethyl phosphate (DEPHA) (dosage ratio of 7:3) and auxiliary light stabilizer 622, antioxidant 1010, and antibacterial agent quaternary ammonium salt were dissolved and dispersed in a polar amine solution (the dosage of the auxiliary was 1.7wt%), and added to the final polymerization reactor by a 3-position injection method. The prepolymer containing phosphorus element was reacted at 60°C for 50min to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 139,000. Finally, the phosphorus-containing polyurethane After aging, the ammonia urea solution is obtained to obtain a spinning solution with a viscosity of 48 Pa.s, which is transported to the spinning box through a metering pump and extruded through a spinneret. The number of spinneret holes is 220. The filaments are solidified in a spinning tunnel filled with 240°C nitrogen. The gas flow rate is 0.5m / s and the winding speed is 1250m / min. High-performance flame-retardant spandex yarns with a strength of 1.45cN / dtex, a breaking elongation of 660% and a limiting oxygen index of 30.5% are obtained.

[0069] Embodiment 11

[0070] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0071] Polybutylene adipate diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor at a molar ratio of 1:2.35, and reacted at 70°C with high-speed stirring for 92 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, a phosphorus-containing dihydroxy compound DOPO-HQ and a nitrogen-containing dihydroxy compound NBP6 were dissolved in an N,N-dimethylacetamide solution (DMF) at a molar ratio of 9:1, and the amount of DMF was 3 times that of the dihydroxy compound, and 0.5wt% of the catalyst dibutyltin dilaurate was added, and transported to a final polymerization reactor (the total amount of DOPO-HQ and NBP6 was 3 / 7 of that of polybutylene adipate diol), and reacted with the prepolymer at 45°C for 10 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, a chain extender ethylenediamine and N,N-dihydroxy with a substance mass of 22.5mol% of diisocyanate were added to the prepolymer; Ethyl-diethyl phosphate (DEPHA) (dosage ratio of 3:7) and auxiliary light stabilizer 292, antioxidant 168, and antibacterial agent quaternary ammonium salt were dissolved and dispersed in a polar amine solution (the dosage of the auxiliary was 1.2wt%), and added to the final polymerization reactor by 5-position injection. The prepolymer containing phosphorus element was reacted at 90°C for 30 minutes to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 136,000. Finally, the phosphorus-containing polyurethane After aging, the ester-urea solution obtains a spinning solution with a viscosity of 45 Pa.s, which is transported to the spinning box through a metering pump and extruded through a spinneret. The number of spinneret holes is 240. The filaments are solidified in a spinning tunnel filled with 245°C nitrogen. The gas flow rate is 0.15m / s, and the winding speed is 1350m / min. High-performance flame-retardant spandex yarns with a strength of 1.75cN / dtex, a breaking elongation of 210%, and a limiting oxygen index of 34.6% are obtained.

[0072] Example 12

[0073] A high-performance flame-retardant spandex fiber and a preparation method thereof according to the present embodiment, the steps are as follows:

[0074] The polybutylene sebacate diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:2.25, and reacted at 60°C with high-speed stirring for 95 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the phosphorus-containing dihydroxy compound MH-PPOA and the nitrogen-containing dihydroxy compound HPIMP were dissolved in N,N-dimethylformamide solution (DMAC) in a molar ratio of 5:5, the amount of DMAC was 4.5 times that of the dihydroxy compound, and 0.5wt% of the catalyst dibutyltin sulfide was added, and transported to a final polymerization reactor (the total amount of DOPO-HQ and HPIMP was 2 / 3 of the polybutylene sebacate diol), and reacted with the prepolymer at 50°C for 15 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender propylene diamine and N,N-dihydroxy propylene glycol with a substance mass of 40mol% of diisocyanate were added to form a polyurethane prepolymer; Ethyl-diethyl phosphate (DEPHA) (dosage ratio of 4:6) and auxiliary light stabilizer 622, antioxidant 1010, and antibacterial agent zinc oxide were dissolved and dispersed in a polar amine solution (the dosage of the auxiliary was 0.7wt%), and added to the final polymerization reactor by a 3-position injection method. The prepolymer containing phosphorus element was reacted at 60°C for 40 minutes to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 131,000; finally, the phosphorus-containing polyurethane After aging, the ester-urea solution obtains a spinning solution with a viscosity of 34.5 Pa.s, which is transported to the spinning box through a metering pump and extruded through a spinneret. The number of spinneret holes is 260. The filaments are solidified in a spinning tunnel filled with 250°C nitrogen. The gas flow rate is 0.55m / s, and the winding speed is 1450m / min. High-performance flame-retardant spandex yarns with a strength of 1.6cN / dtex, a breaking elongation of 480%, and a limiting oxygen index of 34.8% are obtained.

[0075] Comparative Example 1

[0076] Polytetramethylene ether diol and 4,4'-methylenebis(phenyl isocyanate) were added into a prepolymerization reactor in a molar ratio of 1:1.5, and reacted at 90°C with high-speed stirring for 80 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the chain extender ethylenediamine, N,N-dihydroxyethyl-diethyl phosphate (DEPHA) (dosage ratio of 1:9) and the auxiliary agents light stabilizer 119, antioxidant 1067, and antibacterial agent quaternary ammonium salt were dissolved and dispersed in a polar amine N,N-dimethylformamide solution (DMF) solution (DMF dosage was 3 times that of polytetramethylene ether diol, and the auxiliary agent was 1:1.5). The dosage is 0.1wt%), and in a final polymerization reactor, the prepolymer is chain extended to obtain a polyurethane urea solution with a weight average molecular weight of 62,000; finally, the polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 3-5Pa.s, which is transported to a spinning box 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 280°C nitrogen. The gas flow rate is 0.1m / s, and the winding speed is 600m / min, so as to obtain a spandex filament with a strength of 1.2cN / dtex, a breaking elongation of 560%, and a limiting oxygen index of 19.7%.

[0077] In Comparative Example 1, the molecular structure and chain extension method of conventional spandex are used. Since the molecular chain does not contain an aromatic phosphorus-nitrogen diol compound, its elongation at break is greater than 500%, its elasticity is high, but its breaking strength is only 1.2 cN / dtex, and its limiting oxygen index is only 19.27%, which does not have flame retardant properties. In the present invention, through molecular structure design, aromatic phosphorus-containing flame retardant primitives are introduced, and while the limiting oxygen index of spandex fiber is greatly improved (29-35%), the mechanical properties are effectively improved (1.4-1.9 cN / dtex), and high-performance flame retardant spandex fiber is obtained.

[0078] Comparative Example 2

[0079] Polytetramethylene ether diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:1.5, and reacted at 90°C with high-speed stirring for 80 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, a phosphorus-containing dihydroxy compound DOPO-HQ was dissolved in an N,N-dimethylformamide solution (DMF), the amount of DMF being 3.5 times that of the dihydroxy compound, and 0.01wt% of a catalyst stannous octoate was added, and transported to a final polymerization reactor (the amount of DOPO-HQ was 1 / 4 of that of polytetramethylene ether diol), and reacted with the prepolymer at 60°C for 10 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, a chain extender ethylenediamine and N,N-dihydroxyethyl-diethyl phosphate (DEPH) with a substance mass of 20mol% of diisocyanate were added to the prepolymer. A) (dosage ratio of 1:9) and auxiliary agents light stabilizer 119, antioxidant 1067, and antibacterial agent quaternary ammonium salt are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary agent is 0.1wt%), and are added to the final polymerization reactor through a 3-position injection method, and the prepolymer containing the phosphorus element is reacted at 40°C for 60 minutes to extend the chain to obtain a phosphorus-containing polyurethane urea solution with a weight average molecular weight of 99,000; finally, the phosphorus-containing polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 20Pa.s, which is transported to a spinning box through a metering pump and extruded through a spinneret, with a spinneret hole number of 60, and the filaments are solidified in a spinning tunnel filled with 280°C nitrogen, with a gas flow rate of 0.1m / s and a winding speed of 600m / min, to obtain a flame-retardant spandex yarn with a strength of 1.42cN / dtex, a breaking elongation of 450%, and a limiting oxygen index of 27.2%.

[0080] Comparative Example 3

[0081] Polytetramethylene ether diol and 4,4'-methylenebis(phenyl isocyanate) were put into a prepolymerization reactor in a molar ratio of 1:1.5, and reacted at 90°C with high-speed stirring for 80 minutes to prepare a prepolymer, which was then transported to a final polymerization reactor; secondly, the nitrogen-containing dihydroxy compound HPIMP was dissolved in N,N-dimethylformamide solution (DMF), the amount of DMF was 3.5 times that of the dihydroxy compound, and 0.01wt% of the catalyst stannous octoate was added, and transported to a final polymerization reactor (the amount of DOPO-HQ was 1 / 4 of the polytetramethylene ether diol), and reacted with the prepolymer at 60°C for 10 minutes to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; secondly, the chain extender ethylenediamine and N,N-dihydroxyethyl-diethyl phosphate ( DEPHA) (dosage ratio of 1:9) and auxiliary light stabilizer 119, antioxidant 1067, and antibacterial agent quaternary ammonium salt are dissolved and dispersed in a polar amine solution (the dosage of the auxiliary is 0.1wt%), and added to the final polymerization reactor through a 3-position injection method, and the prepolymer is extended by reacting at 40°C for 60min to obtain a polyurethane urea solution with a weight average molecular weight of 872,000; finally, the polyurethane urea solution is aged to obtain a spinning solution with a viscosity of 12Pa.s, which is transported to a spinning box through a metering pump and extruded through a spinneret, with 60 spinneret holes, and the filaments are solidified in a spinning tunnel filled with 280°C nitrogen, with a gas flow rate of 0.1m / s and a winding speed of 600m / min, to obtain a flame-retardant spandex yarn with a strength of 1.36cN / dtex, a breaking elongation of 526%, and a limiting oxygen index of 22.6%.

[0082] In Comparative Examples 2 and 3, phosphorus-containing dihydroxy compounds DOPO-HQ and nitrogen-containing dihydroxy compounds are introduced into the molecular chain, respectively. It can be seen that compared with conventional spandex (Comparative Example 1), the introduction of phosphorus-containing and nitrogen-containing dihydroxy compounds can improve the flame retardancy and mechanical properties of spandex fibers, but the effect is not obvious, far inferior to the performance of spandex fibers in Example 1. The simultaneous introduction of phosphorus-containing and nitrogen-containing dihydroxy compounds can make full use of the high-temperature crosslinking of C=N and N=N bonds and the synergistic flame retardant properties of P, N, and can effectively enhance the inter-molecular chain interaction and flame retardant properties, achieving both mechanical properties and flame retardant properties.

[0083] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-performance flame-retardant spandex fiber, characterized in that: The following steps are involved: (1) mixing a polyglycol and a diisocyanate and subjecting them to a prepolymerization reaction to obtain a prepolymer; (2) dissolving a phosphorus-containing dihydroxy compound, a nitrogen-containing dihydroxy compound and a catalyst in a polar amine solution to prepare a mixed solution, mixing the mixed solution with a prepolymer and then performing a polymerization reaction to obtain a low molecular weight polyurethane containing phosphorus in the molecular chain; (3) mixing the low molecular weight polyurethane with a chain extender and performing a chain extension reaction to obtain a phosphorus-containing polyurethane urea solution; (4) The phosphorus-containing polyurethane urea solution is spun after being aged to obtain high-performance flame-retardant spandex yarn.

2. The method for preparing high-performance flame-retardant spandex fiber according to claim 1, characterized in that: The polyglycol is a polyether glycol or polyester glycol with a molecular weight of 1000-3000; the polyether glycol is one of polytetramethylene glycol, polyethylene glycol and polypropylene glycol; the polyester glycol is one of polybutylene succinate glycol, polybutylene adipate glycol and polybutylene sebacate glycol.

3. The method for preparing high-performance flame-retardant spandex fiber according to claim 2, characterized in that: The molar ratio of the polyglycol to the diisocyanate is 1:(1.8-2.5); the temperature of the prepolymerization reaction is 60-90° C., and the time is 80-100 min.

4. The method for preparing high-performance flame-retardant spandex fiber according to claim 3, characterized in that: The phosphorus-containing dihydroxy compound is one of the following structures: The nitrogen-containing dihydroxy compound is one of the following structures: The molar ratio of the phosphorus-containing dihydroxy compound to the nitrogen-containing dihydroxy compound is (1:9)-(9:1), and the molar ratio of the total amount of the two to the polyglycol is (1:9)-(5:5).

5. The method for preparing high-performance flame-retardant spandex fiber according to claim 1, characterized in that: The polymerization reaction temperature is 30-60° C. and the reaction time is 10-30 min.

6. The method for preparing high-performance flame-retardant spandex fiber according to claim 5, characterized in that: The catalyst is stannous octoate, dibutyltin dilaurate or dibutyltin sulfide, and its dosage is 0.01-0.5wt% of the total mass of the phosphorus-containing dihydroxy compound and the nitrogen-containing dihydroxy compound; the polar amine solution is N,N-dimethylformamide or N,N-dimethylacetamide, and its dosage is 3-5 times of the total mass of the phosphorus-containing dihydroxy compound.

7. The method for preparing high-performance flame-retardant spandex fiber according to claim 1, characterized in that: The chain extender includes a diamine and a diol, and the amount thereof is 20-50 mol% of the diisocyanate; the molar ratio of the diamine to the diol is (1:9)-(9:1); the diamine is one of ethylenediamine, propylenediamine, butanediamine, cyclohexanediamine and p-phenylenediamine; and the diol is N,N-dihydroxyethyl-diethyl phosphate.

8. The method for preparing high-performance flame-retardant spandex fiber according to claim 7, characterized in that: The temperature of the chain extension reaction is 40-80° C. and the time is 30-90 min.

9. The method for preparing high-performance flame-retardant spandex fiber according to any one of claims 1 to 8, characterized in that: The phosphorus-containing polyurethane urea solution in step (3) is further added with an auxiliary agent, the amount of which is 0.1-3wt% of the total mass of the phosphorus-containing polyurethane urea solution; the auxiliary agent includes any one or more of a light stabilizer, an antioxidant, and an antibacterial agent.

10. The high-performance flame-retardant spandex fiber prepared by the method according to any one of claims 1 to 9, characterized in that: The weight average molecular weight is greater than 90,000, the breaking strength is greater than 1.3 cN / dtex, and the limiting oxygen index is greater than 30%.

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