Highly elastic polyurethane flame resistant fiber, method of making and use on stretch electrical cord

Abstract

The application relates to the technical field of fibers, and discloses a high-elasticity polyurethane flame-retardant fiber, a preparation method and application in stretchable electric wires. The preparation method comprises the following steps: using 1,1,3,3-tetramethyldisiloxane as a bridging agent through a silicon-hydrogen addition reaction to connect allyl-modified DOPO and allyl phenoxy cyclotriphosphazene, so as to prepare a flame retardant containing three flame-retardant elements of phosphorus, nitrogen and silicon; preparing a polyurethane urea solution through a method of adding 4,4-diphenyl methane diisocyanate in batches, and introducing the flame retardant; mixing the polyurethane urea solution with an antioxidant, a dyeing aid and a matting agent, and carrying out dry spinning to obtain the high-elasticity polyurethane flame-retardant fiber. The polyurethane fiber has excellent flame-retardant performance and heat resistance, and has good mechanical properties and rebounding capacity, and can be applied to stretchable electric wires.

Description

Technical Field

[0001] This invention relates to the field of fiber technology, specifically to a highly elastic polyurethane flame-retardant fiber, its preparation method, and its application in telescopic wires. Background Technology

[0002] Polyurethane elastic fiber, commonly known as spandex, is a multi-block copolymer with alternating soft and hard segments. Its unique structure gives it high resilience and low modulus. Industrially produced spandex can be divided into melt-spun spandex and dry-spun spandex according to the processing technology, with dry-spun spandex exhibiting superior performance. Traditional electrical wires use resin sheaths, which are prone to loosening and tangling in dynamic environments. The excellent elasticity of spandex fibers provides a basis for controllable stretching and contraction in electrical wires.

[0003] Although polyurethane fibers possess various excellent properties, their flammability, with a limiting oxygen index of only 17%, severely impacts the flame-retardant properties of flame-retardant materials, thus limiting their application. Currently, the main methods for preparing flame-retardant fibers include copolymer flame-retardant modification, blend flame-retardant modification, composite spinning modification, graft flame-retardant modification, and fabric finishing. The flame-retardant mechanisms of flame retardants are mainly classified into gas-phase flame retardancy, condensed-phase flame retardancy, and synergistic flame-retardant mechanisms. Existing technologies utilize polyols, isocyanates, or chain extenders containing flame-retardant elements to introduce these elements into the polyurethane molecular structure through reaction, achieving inherent flame retardancy in polyurethane fibers. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-elasticity polyurethane flame-retardant fiber, a preparation method, and its application in retractable wires. This polyurethane fiber has excellent flame-retardant and heat-resistant properties, as well as good mechanical properties and resilience, and can be used in retractable wires.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing highly elastic polyurethane flame-retardant fiber includes the following steps:

[0007] Step (1): Mix and dissolve hexachlorocyclotriphosphazene, acetone, and potassium carbonate catalyst, add acetone solution of 2-allylphenol, react, and after the reaction is complete, purify to obtain allylphenoxycyclotriphosphazene.

[0008] Step (2): Heat DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) until it melts, add allyl glycidyl ether and triphenylphosphine catalyst, react, and after the reaction is completed, cool to obtain allyl modified DOPO.

[0009] Mixing allyl phenoxy cyclotriphosphazene, cast catalyst, tetrahydrofuran, heating, adding 1,1,3,3-tetramethyl disiloxane dropwise, after adding, reacting, after the reaction, adding allyl modified DOPO, continuing to react, after the reaction, rotary evaporation, obtaining the flame retardant;

[0010] Step (3), reacting polytetrahydrofuran ether glycol and the first 4,4-diphenyl methane diisocyanate, after the reaction, obtaining the prepolymer; mixing and dissolving the prepolymer and dimethylacetamide, adding the second 4,4-diphenyl methane diisocyanate and mixing uniformly, adding the flame retardant, continuing to react, after the reaction, cooling, adding the chain extender, reacting again, after the reaction, obtaining the polyurethane urea solution;

[0011] Step (4), mixing the polyurethane urea solution with the antioxidant, the dyeing aid and the matting agent, dry spinning, obtaining the high-elasticity polyurethane flame-retardant fiber.

[0012] Preferably, in the step (1), the molar ratio of hexachlorocyclotriphosphazene and 2-allyl phenol is 1:6.5-7; the 2-allyl phenol acetone solution is prepared by mixing 2-allyl phenol and acetone with a mass ratio of 1:5-6; the mass ratio of hexachlorocyclotriphosphazene, acetone and catalyst potassium carbonate is 17-18:180-200:82-83.

[0013] Preferably, in the step (1), the reaction condition is: reacting at 40-50℃ for 12-15h.

[0014] Preferably, in the step (1), the purification operation includes: after the reaction, cooling to room temperature, suction filtration, taking the filtrate, removing the solvent acetone by distillation under reduced pressure, dissolving the reaction crude product with toluene, sequentially adding 5wt% sodium hydroxide aqueous solution, 2wt% hydrochloric acid aqueous solution, washing with water until neutral, after the washing, adding anhydrous sodium sulfate for drying, filtering, taking the filtrate, removing the solvent by distillation under reduced pressure.

[0015] Preferably, in the step (2), the molar ratio of DOPO and allyl glycidyl ether is 1:1-1.1; the addition amount of the catalyst triphenylphosphine is 0.5-0.8wt% of the mass sum of DOPO and allyl glycidyl ether; in the preparation of allyl modified DOPO, the preparation reaction condition is: reacting at 130℃ for 10-12h in a nitrogen atmosphere.

[0016] Preferably, in the step (2), the mass ratio of allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl modified DOPO, Karstedt catalyst, tetrahydrofuran is 93-95:82-84.5:192-208:3-3.5:3500-4000; in the preparation of the flame retardant, the reaction condition is: reacting at a temperature of 60-70℃ for 2-2.5h; the continuous reaction condition is: continuously reacting at a temperature of 65-75℃ for 3-4h.

[0017] Preferably, in the step (3), the mass ratio of polytetrahydrofuran ether diol, the first 4,4-diphenyl methane diisocyanate, the second 4,4-diphenyl methane diisocyanate, the chain extender, the flame retardant is 340:75-80:23-25:80-90:50-60.

[0018] The chain extender is ethylenediamine, propylenediamine, diethylamine, dimethylacetamide mixed and dissolved in a mass ratio of 5-5.1:3:0.5-0.6:90-100.

[0019] Preferably, in the step (3), the reaction condition is: reacting at a temperature of 80-85℃ for 2-2.5h; the continuous reaction condition is: continuously reacting at a temperature of 70-75℃ for 0.5h; the re-reaction condition is: re-reacting at a temperature of 10℃ for 0.5-1h.

[0020] Preferably, in the step (3), the solid content of the polyurethane urea solution is 30-40wt%.

[0021] Preferably, in the step (4), the mass ratio of the polyurethane urea solution, the antioxidant, the yellow inhibitor, the matting agent is 1000:0.02-0.03:0.01-0.02:0.008-0.01; the spinning speed of the dry spinning is 800-900m / min, and the spinning drum atmosphere temperature is 250-270℃.

[0022] Preferably, the high-elasticity polyurethane flame-retardant fiber is prepared by the preparation method of the high-elasticity polyurethane flame-retardant fiber.

[0023] Preferably, the high-elasticity polyurethane flame-retardant fiber is applied to the stretchable electric wire.

[0024] Compared with the prior art, the high-elasticity polyurethane flame-retardant fiber has the following beneficial effects:

[0025] The high-elasticity polyurethane flame-retardant fiber is prepared by introducing the flame retardant into the polyurethane urea spinning solution and adopting the preparation method of twice adding isocyanate, so that the flame-retardant property and the heat resistance of the polyurethane fiber are improved, and the mechanical property and the rebounding capacity of the polyurethane fiber are also improved.

[0026] The present application uses hexachlorocyclotriphosphazene and 2-allyl phenol as raw materials to prepare allyl phenoxy cyclotriphosphazene with carbon-carbon double bond functional groups; then through ring-opening reaction of DOPO and allyl glycidyl ether under the condition of a catalyst, allyl modified DOPO with carbon-carbon double bond and hydroxyl functional groups is prepared; through silicon hydride addition reaction of carbon-carbon double bond and Si-H bond under the condition of a platinum catalyst, 1,1,3,3-tetramethyldisiloxane is used as a bridging agent to connect allyl modified DOPO and allyl phenoxy cyclotriphosphazene, and a flame retardant with phosphorus, nitrogen and silicon three kinds of flame-retardant elements is prepared, and because the hydroxyl functional groups exist in the flame retardant, the flame-retardant structure can be grafted and copolymerized in the polymer through participating in the polymerization reaction of polyurethane urea prepolymer, so that the flame retardance and flame retardant durability of the material are improved.

[0027] In addition, the flame retardant contains rigid structures such as cyclotriphosphazene and benzene rings, and the introduction of the rigid structures into the polyurethane urea matrix material can improve the mechanical properties and heat resistance of the material; at the same time, the flame retardant can react with diisocyanate through multiple hydroxyl groups, the functionality of the reaction is increased, and a network structure is formed in the polyurethane urea matrix material with the flame retardant as the center, so that the mechanical properties and elastic properties of the fiber are improved.

[0028] In the preparation of the polyurethane urea spinning solution, the method of adding isocyanate twice is adopted, so that the free isocyanate added for the second time is easy to form a hard segment area with good crystallization performance in the chain extension process, so that the crystallization performance of the fiber is improved, cross-linking is generated at the same time, and the rebound ability of the fiber is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a reaction schematic diagram of synthesis of allyl phenoxy cyclotriphosphazene in the present application;

[0030] Figure 2 is a reaction schematic diagram of synthesis of allyl modified DOPO in the present application;

[0031] Figure 3 is a reaction schematic diagram of synthesis of the flame retardant in the present application;

[0032] Figure 4 is a limit oxygen index column chart of examples 1-5 and comparative examples 1-2 in performance testing in the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0034] Example 1

[0035] The embodiment discloses a preparation method of high-elasticity polyurethane flame-retardant fiber, comprising the following steps:

[0036] Step (1), six chloro-cyclotriphosphazene, acetone and catalyst potassium carbonate are mixed and dissolved in a mass ratio of 17:180:82, 2-allyl phenol acetone solution is added at 30 DEG C, and the reaction is carried out at 40 DEG C for 15 h; after the reaction is completed, the temperature is cooled to room temperature, filtration is carried out, the filtrate is taken, the solvent acetone is removed by distillation under reduced pressure, the reaction crude product is dissolved in toluene, 5wt% sodium hydroxide aqueous solution and 2wt% hydrochloric acid aqueous solution are added in sequence, and the washing is carried out until neutral; after the washing is completed, anhydrous sodium sulfate is added for drying, filtration is carried out, the filtrate is taken, and the solvent is removed by distillation under reduced pressure to obtain allyl phenoxy cyclotriphosphazene;

[0037] In the embodiment, the molar ratio of six chloro-cyclotriphosphazene to 2-allyl phenol is 1:6.5; the 2-allyl phenol acetone solution is prepared by mixing 2-allyl phenol and acetone in a mass ratio of 1:5;

[0038] Step (2), DOPO is melted by being heated to 130 DEG C, allyl glycidyl ether and catalyst triphenyl phosphine are added, the reaction is carried out at 130 DEG C for 12 h in a nitrogen atmosphere, and after the reaction is completed, the temperature is cooled to room temperature to obtain allyl modified DOPO;

[0039] In the embodiment, the molar ratio of DOPO to allyl glycidyl ether is 1:1.1; the catalyst triphenyl phosphine is added in an amount of 0.7wt% of the mass sum of DOPO and allyl glycidyl ether;

[0040] The allyl phenoxy cyclotriphosphazene, Karstedt catalyst and tetrahydrofuran are mixed, the temperature is increased to 60 DEG C, 1,1,3,3-tetramethyldisiloxane is added dropwise, the dropwise adding time is 1 h, after the dropwise adding is completed, the reaction is carried out at 60 DEG C for 2.5 h, after the reaction is completed, the allyl modified DOPO is added, and the reaction is continuously carried out at 65 DEG C for 4 h; after the reaction is completed, the solvent is removed by rotary evaporation to obtain a flame retardant;

[0041] In the embodiment, the mass ratio of allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl modified DOPO, Karstedt catalyst and tetrahydrofuran is 93:82:192:3:3500;

[0042] Step (3), the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate is reacted at 80℃ for 2.5h, after the reaction is completed, a prepolymer is obtained; the prepolymer is mixed and dissolved with dimethylacetamide, the second 4, 4-diphenyl methane diisocyanate is added and mixed uniformly, the flame retardant is added, and the reaction is continued at 70℃ for 0.5h, after the reaction is completed, the temperature is lowered to 10℃, the chain extender is added, and the reaction is carried out again for 0.5h, after the reaction is completed, a polyurethane urea solution with a solid content of 35wt% is obtained;

[0043] The mass ratio of the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate, the second 4, 4-diphenyl methane diisocyanate, the chain extender and the flame retardant is 340:75:23:90:50;

[0044] The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide at a mass ratio of 5:3:0.6:90;

[0045] Step (4), the polyurethane urea solution is mixed with the antioxidant, the yellowing inhibitor, the matting agent at a mass ratio of 1000:0.02:0.01:0.008, dry spinning is carried out, and a high-elasticity polyurethane flame-retardant fiber is obtained;

[0046] The spinning speed of the dry spinning is 800m / min, and the atmosphere temperature of the spinning drum is 250℃.

[0047] Example 2

[0048] The embodiment discloses a preparation method of a high-elasticity polyurethane flame-retardant fiber.

[0049] Step (1), hexachlorocyclotriphosphazene, acetone and a catalyst potassium carbonate are mixed and dissolved at a mass ratio of 17.5:190:82.5, an acetone solution of 2-allylphenol is added at 30℃, the reaction is carried out at 45℃ for 13h, after the reaction is completed, the temperature is cooled to room temperature, filtration is carried out, the filtrate is taken, the solvent acetone is removed by distillation under reduced pressure, a reaction crude product is obtained, the reaction crude product is dissolved with toluene, 5wt% sodium hydroxide aqueous solution and 2wt% hydrochloric acid aqueous solution are added in sequence, washing with water is carried out until neutralization, after the washing is completed, anhydrous sodium sulfate is added for drying, filtration is carried out, the filtrate is taken, and the solvent is removed by distillation under reduced pressure, and allylphenoxy cyclotriphosphazene is obtained;

[0050] The molar ratio of the hexachlorocyclotriphosphazene and the 2-allylphenol is 1:6.5; the acetone solution of the 2-allylphenol is prepared by mixing 2-allylphenol and acetone at a mass ratio of 1:5;

[0051] Step (2), melt DOPO at 130℃, add allyl glycidyl ether and catalyst triphenylphosphine, react for 12h under nitrogen atmosphere at 130℃, after the reaction, cool to room temperature, to obtain allyl modified DOPO;

[0052] The molar ratio of DOPO and allyl glycidyl ether is 1:1.1; the amount of catalyst triphenylphosphine added is 0.7wt% of the mass sum of DOPO and allyl glycidyl ether;

[0053] Mix allyl phenoxy cyclotriphosphazene, Karstedt catalyst and tetrahydrofuran, heat to 60℃, drop 1,1,3,3-tetramethyldisiloxane, drop for 1h, after the drop is completed, react for 2.5h at 60℃, after the reaction, add allyl modified DOPO, continue to react for 3.5h at 70℃, after the reaction, remove the solvent by rotary evaporation, to obtain the flame retardant;

[0054] The mass ratio of allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl modified DOPO, Karstedt catalyst and tetrahydrofuran is 93.5:82.5:196:3.1:3600;

[0055] Step (3), react polytetrahydrofuran ether glycol and the first 4,4-diphenyl methane diisocyanate at 80℃ for 2.5h, after the reaction, obtain the prepolymer; mix and dissolve the prepolymer and dimethylacetamide, add the second 4,4-diphenyl methane diisocyanate and mix uniformly, add the flame retardant, continue to react for 0.5h at 70℃, after the reaction, cool to 10℃, add the chain extender, react for 0.5h again, after the reaction, obtain the polyurethane urea solution with solid content of 35wt%;

[0056] The mass ratio of polytetrahydrofuran ether glycol, the first 4,4-diphenyl methane diisocyanate, the second 4,4-diphenyl methane diisocyanate, the chain extender and the flame retardant is 340:76:23.5:87:53;

[0057] The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide in a mass ratio of 5.05:3:0.55:90;

[0058] Step (4), mix the polyurethane urea solution, antioxidant, yellowing inhibitor and matting agent in a mass ratio of 1000:0.02:0.01:0.008, dry spinning, to obtain the high-elasticity polyurethane flame-retardant fiber;

[0059] The spinning speed of dry spinning is 800m / min, and the atmosphere temperature of the spinning drum is 250℃.

[0060] Example 3

[0061] The embodiment discloses a preparation method of high-elastic polyurethane flame-retardant fiber, comprising the following steps:

[0062] Step (1), six chloro-cyclotriphosphazene, acetone and catalyst potassium carbonate are mixed and dissolved in a mass ratio of 17.5:190:82.5, an acetone solution of 2-allyl phenol is added at a temperature of 30 DEG C, and the reaction is carried out at a temperature of 45 DEG C for 13 hours; after the reaction is completed, the temperature is cooled to room temperature, filtration is carried out, the filtrate is taken, the solvent acetone is removed by distillation under reduced pressure, the reaction crude product is dissolved in toluene, 5wt% sodium hydroxide aqueous solution and 2wt% hydrochloric acid aqueous solution are added in sequence, and the washing is carried out until the washing liquid is neutral; after the washing is completed, anhydrous sodium sulfate is added for drying, filtration is carried out, the filtrate is taken, and the solvent is removed by distillation under reduced pressure to obtain allyl phenoxy cyclotriphosphazene;

[0063] In the embodiment, the molar ratio of six chloro-cyclotriphosphazene to 2-allyl phenol is 1:6.8; the acetone solution of 2-allyl phenol is prepared by mixing 2-allyl phenol and acetone in a mass ratio of 1:5;

[0064] Step (2), DOPO is melted by being heated to 130 DEG C, allyl glycidyl ether and catalyst triphenylphosphine are added, the reaction is carried out at a temperature of 130 DEG C for 12 hours in a nitrogen atmosphere, and after the reaction is completed, the temperature is cooled to room temperature to obtain allyl-modified DOPO;

[0065] In the embodiment, the molar ratio of DOPO to allyl glycidyl ether is 1:1.1; the catalyst triphenylphosphine is added in an amount of 0.7wt% of the total mass of DOPO and allyl glycidyl ether;

[0066] The allyl phenoxy cyclotriphosphazene, Karstedt catalyst and tetrahydrofuran are mixed, the temperature is increased to 60 DEG C, 1,1,3,3-tetramethyldisiloxane is added dropwise, the dropwise adding is carried out for 1 hour, after the dropwise adding is completed, the reaction is carried out at a temperature of 65 DEG C for 2.3 hours, after the reaction is completed, the allyl-modified DOPO is added, and the reaction is continuously carried out at a temperature of 70 DEG C for 3.5 hours; after the reaction is completed, the solvent is removed by rotary evaporation to obtain a flame retardant;

[0067] In the embodiment, the mass ratio of the allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl-modified DOPO, Karstedt catalyst and tetrahydrofuran is 94:83:200:3.3:3800;

[0068] Step (3), the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate is reacted at 83℃ for 2.3h, after the reaction is completed, a prepolymer is obtained; the prepolymer is mixed and dissolved with dimethylacetamide, the second 4, 4-diphenyl methane diisocyanate is added and mixed uniformly, the flame retardant is added, and the reaction is continued at 72℃ for 0.5h, after the reaction is completed, the temperature is lowered to 10℃, the chain extender is added, and the reaction is carried out again for 0.8h, after the reaction is completed, a polyurethane urea solution with a solid content of 35wt% is obtained;

[0069] The mass ratio of the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate, the second 4, 4-diphenyl methane diisocyanate, the chain extender and the flame retardant is 340:78:24:85:55;

[0070] The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide at a mass ratio of 5.05:3:0.55:90;

[0071] Step (4), the polyurethane urea solution is mixed with the antioxidant, the yellowing inhibitor, the matting agent at a mass ratio of 1000:0.02:0.01:0.008, dry spinning is carried out, and a high-elasticity polyurethane flame-retardant fiber is obtained.

[0072] The spinning speed of the dry spinning is 850m / min, and the atmosphere temperature of the spinning drum is 250℃.

[0073] Example 4

[0074] The embodiment discloses a preparation method of a high-elasticity polyurethane flame-retardant fiber.

[0075] Step (1), hexachlorocyclotriphosphazene, acetone and a catalyst potassium carbonate are mixed and dissolved at a mass ratio of 18:190:83, an acetone solution of 2-allylphenol is added at 30℃, the reaction is carried out at 45℃ for 13h, after the reaction is completed, the temperature is lowered to room temperature, filtration is carried out, the filtrate is taken, the solvent acetone is removed by distillation under reduced pressure, a reaction crude product is obtained, the reaction crude product is dissolved with toluene, 5wt% sodium hydroxide aqueous solution and 2wt% hydrochloric acid aqueous solution are added in sequence, washing is carried out with water until neutralization, after the washing is completed, anhydrous sodium sulfate is added for drying, filtration is carried out, the filtrate is taken, and the solvent is removed by distillation under reduced pressure, and allylphenoxy cyclotriphosphazene is obtained.

[0076] The molar ratio of the hexachlorocyclotriphosphazene and the 2-allylphenol is 1:7; the acetone solution of the 2-allylphenol is prepared by mixing and dissolving 2-allylphenol and acetone at a mass ratio of 1:6;

[0077] Step (2), melt DOPO at 130℃, add allyl glycidyl ether and catalyst triphenylphosphine, react for 12h under nitrogen atmosphere at 130℃, after the reaction, cool to room temperature, to obtain allyl modified DOPO;

[0078] The molar ratio of DOPO and allyl glycidyl ether is 1:1.1; the amount of catalyst triphenylphosphine added is 0.7wt% of the mass sum of DOPO and allyl glycidyl ether;

[0079] Mix allyl phenoxy cyclotriphosphazene, Karstedt catalyst and tetrahydrofuran, heat to 60℃, drop 1,1,3,3-tetramethyldisiloxane, drop for 1h, after drop completion, react for 2h at 70℃, after the reaction, add allyl modified DOPO, continue to react for 3h at 75℃, after the reaction, remove the solvent by rotary evaporation, to obtain the flame retardant;

[0080] The mass ratio of allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl modified DOPO, Karstedt catalyst and tetrahydrofuran is 94.5:84:204:3.4:3800;

[0081] Step (3), react polytetrahydrofuran ether diol and the first 4,4-diphenyl methane diisocyanate at 85℃ for 2h, after the reaction, obtain the prepolymer; mix and dissolve the prepolymer and dimethylacetamide, mix uniformly with the second 4,4-diphenyl methane diisocyanate, add the flame retardant, continue to react for 0.5h at 75℃, after the reaction, cool to 10℃, add the chain extender, react for 1h again, after the reaction, obtain the polyurethane urea solution with solid content of 35wt%;

[0082] The mass ratio of polytetrahydrofuran ether diol, the first 4,4-diphenyl methane diisocyanate, the second 4,4-diphenyl methane diisocyanate, the chain extender and the flame retardant is 340:79:24.5:82:58;

[0083] The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide in a mass ratio of 5.1:3:0.6:90;

[0084] Step (4), mix the polyurethane urea solution with antioxidant, yellowing inhibitor and matting agent in a mass ratio of 1000:0.02:0.01:0.008, dry spinning, to obtain the high-elasticity polyurethane flame-retardant fiber;

[0085] The spinning speed of dry spinning is 900m / min, and the atmosphere temperature of the spinning drum is 250℃.

[0086] Example 5

[0087] The embodiment discloses a preparation method of high-elasticity polyurethane flame-retardant fiber, comprising the following steps:

[0088] Step (1), six chloro-cyclotriphosphazene, acetone and catalyst potassium carbonate are mixed and dissolved in a mass ratio of 18:200:83, 2-allyl phenol acetone solution is added at 30 DEG C, and the reaction is carried out at 50 DEG C for 12 hours; after the reaction is completed, the temperature is cooled to room temperature, filtration is carried out, the filtrate is taken, the solvent acetone is removed by distillation under reduced pressure, the reaction crude product is dissolved in toluene, 5wt% sodium hydroxide aqueous solution and 2wt% hydrochloric acid aqueous solution are added in sequence, and the washing is carried out until neutral; after the washing is completed, anhydrous sodium sulfate is added for drying, filtration is carried out, the filtrate is taken, and the solvent is removed by distillation under reduced pressure to obtain allyl phenoxy cyclotriphosphazene;

[0089] In the formula, the molar ratio of six chloro-cyclotriphosphazene to 2-allyl phenol is 1:7; the 2-allyl phenol acetone solution is prepared by mixing 2-allyl phenol and acetone in a mass ratio of 1:6;

[0090] Step (2), DOPO is melted by being heated to 130 DEG C, allyl glycidyl ether and catalyst triphenyl phosphine are added, the reaction is carried out at 130 DEG C for 12 hours in a nitrogen atmosphere, and after the reaction is completed, the temperature is cooled to room temperature to obtain allyl modified DOPO;

[0091] In the formula, the molar ratio of DOPO to allyl glycidyl ether is 1:1.1; the catalyst triphenyl phosphine is added in an amount of 0.7wt% of the mass sum of DOPO and allyl glycidyl ether;

[0092] The allyl phenoxy cyclotriphosphazene, Karstedt catalyst and tetrahydrofuran are mixed, the temperature is increased to 60 DEG C, 1,1,3,3-tetramethyldisiloxane is added dropwise, the dropwise adding time is 1 hour, after the dropwise adding is completed, the reaction is carried out at 70 DEG C for 2 hours, after the reaction is completed, the allyl modified DOPO is added, and the reaction is continuously carried out at 75 DEG C for 3 hours; after the reaction is completed, the solvent is removed by rotary evaporation to obtain a flame retardant;

[0093] In the formula, the mass ratio of allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl modified DOPO, Karstedt catalyst and tetrahydrofuran is 95:84.5:208:3.5:4000;

[0094] Step (3), the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate is reacted at 85℃ for 2h, after the reaction is completed, a prepolymer is obtained; the prepolymer is mixed and dissolved with dimethylacetamide, the second 4, 4-diphenyl methane diisocyanate is added and mixed uniformly, the flame retardant is added, and the reaction is continued at 75℃ for 0.5h, after the reaction is completed, the temperature is lowered to 10℃, the chain extender is added, and the reaction is carried out again for 1h, after the reaction is completed, a polyurethane urea solution with a solid content of 35wt% is obtained;

[0095] The mass ratio of the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate, the second 4, 4-diphenyl methane diisocyanate, the chain extender and the flame retardant is 340:80:25:80:60;

[0096] The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide at a mass ratio of 5.1:3:0.5:90;

[0097] Step (4), the polyurethane urea solution is mixed with the antioxidant, the yellowing inhibitor, the matting agent at a mass ratio of 1000:0.02:0.01:0.008, dry spinning is carried out, and a high-elasticity polyurethane flame-retardant fiber is obtained.

[0098] The spinning speed of the dry spinning is 900m / min, and the atmosphere temperature of the spinning drum is 250℃.

[0099] Comparative Example 1

[0100] The present comparative example discloses a preparation method of a polyurethane fiber, comprising the following steps:

[0101] Step (1), hexachlorocyclotriphosphazene, acetone and a catalyst potassium carbonate are mixed and dissolved at a mass ratio of 17:180:82, an acetone solution of 2-allyl phenol is added at 30℃, the reaction is carried out at 40℃ for 15h, after the reaction is completed, the temperature is cooled to room temperature, filtration is carried out, the filtrate is taken, the solvent acetone is removed by distillation under reduced pressure, a reaction crude product is obtained, the reaction crude product is dissolved with toluene, 5wt% sodium hydroxide aqueous solution and 2wt% hydrochloric acid aqueous solution are added in sequence, washing with water is carried out until neutral, after the washing is completed, anhydrous sodium sulfate is added for drying, filtration is carried out, the filtrate is taken, and the solvent is removed by distillation under reduced pressure, and allyl phenoxy cyclotriphosphazene is obtained;

[0102] The molar ratio of the hexachlorocyclotriphosphazene and the 2-allyl phenol is 1:6.5; the acetone solution of the 2-allyl phenol is prepared by mixing 2-allyl phenol and acetone at a mass ratio of 1:5;

[0103] Step (2), the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate is reacted at 80 DEG C for 2.5h, after the reaction is completed, the prepolymer is obtained; the prepolymer is dissolved in dimethylacetamide, the second 4, 4-diphenyl methane diisocyanate is added and mixed uniformly, the allyl phenoxy cyclotriphosphazene is added, and the reaction is continued at 70 DEG C for 0.5h, after the reaction is completed, the temperature is lowered to 10 DEG C, the chain extender is added, and the reaction is carried out again for 0.5h, after the reaction is completed, the polyurethane urea solution with a solid content of 35wt% is obtained;

[0104] The mass ratio of the polytetrahydrofuran ether glycol, the first 4, 4-diphenyl methane diisocyanate, the second 4, 4-diphenyl methane diisocyanate, the chain extender and the allyl phenoxy cyclotriphosphazene is 340:75:23:90:50;

[0105] The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide in a mass ratio of 5:3:0.6:90;

[0106] Step (4), the polyurethane urea solution is mixed with the antioxidant, the yellowing inhibitor, the matting agent in a mass ratio of 1000:0.02:0.01:0.008, and dry spinning is carried out to obtain the polyurethane fiber;

[0107] The spinning speed of the dry spinning is 800m / min, and the atmosphere temperature of the spinning drum is 250 DEG C.

[0108] Comparative Example 2

[0109] The present comparative example discloses a preparation method of a polyurethane fiber, comprising the following steps:

[0110] Step (1), hexachlorocyclotriphosphazene, acetone and catalyst potassium carbonate are mixed and dissolved in a mass ratio of 17:180:82, 2-allyl phenol acetone solution is added at 30 DEG C, the reaction is carried out at 40 DEG C for 15h, after the reaction is completed, the temperature is cooled to room temperature, filtration is carried out, the filtrate is taken, the solvent acetone is removed by distillation under reduced pressure, the reaction crude product is obtained, the reaction crude product is dissolved in toluene, 5wt% sodium hydroxide aqueous solution, 2wt% hydrochloric acid aqueous solution and water are added in sequence, washing is carried out until neutral, after the washing is completed, anhydrous sodium sulfate is added for drying, filtration is carried out, the filtrate is taken, and the solvent is removed by distillation under reduced pressure to obtain the allyl phenoxy cyclotriphosphazene;

[0111] The molar ratio of the hexachlorocyclotriphosphazene and the 2-allyl phenol is 1:6.5; the 2-allyl phenol acetone solution is prepared by mixing 2-allyl phenol and acetone in a mass ratio of 1:5;

[0112] Step (2), melt DOPO at 130℃, add allyl glycidyl ether and catalyst triphenylphosphine, react for 12h under nitrogen atmosphere at 130℃, after the reaction, cool to room temperature, to obtain allyl modified DOPO;

[0113] The molar ratio of DOPO and allyl glycidyl ether is 1:1.1; the catalyst triphenylphosphine is added in an amount of 0.7wt% of the mass sum of DOPO and allyl glycidyl ether;

[0114] Mix allyl phenoxy cyclotriphosphazene, Karstedt catalyst and tetrahydrofuran, heat to 60℃, drop 1,1,3,3-tetramethyldisiloxane, drop for 1h, after drop completion, react for 2.5h at 60℃, after the reaction, add allyl modified DOPO, continue to react for 4h at 65℃, after the reaction, remove the solvent by rotary evaporation, to obtain the flame retardant;

[0115] The mass ratio of allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl modified DOPO, Karstedt catalyst and tetrahydrofuran is 93:82:192:3:3500;

[0116] Step (3), react polytetrahydrofuran ether glycol and 4,4-diphenyl methane diisocyanate at 80℃ for 2.5h, after the reaction, obtain the prepolymer; mix and dissolve the prepolymer and dimethylacetamide, add the flame retardant, continue to react for 0.5h at 70℃, after the reaction, cool to 10℃, add the chain extender, react for 0.5h again, after the reaction, obtain the polyurethane urea solution with solid content of 35wt%;

[0117] The mass ratio of polytetrahydrofuran ether glycol, 4,4-diphenyl methane diisocyanate, chain extender and flame retardant is 340:98:90:50;

[0118] The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide in a mass ratio of 5:3:0.6:90;

[0119] Step (4), mix the polyurethane urea solution with antioxidant, yellowing inhibitor and matting agent in a mass ratio of 1000:0.02:0.01:0.008, dry spinning, to obtain the polyurethane fiber;

[0120] The spinning speed of dry spinning is 800m / min, and the atmosphere temperature of the spinning drum is 250℃.

[0121] In the above examples and comparative examples, the Mn of polytetrahydrofuran ether diol is 1800; the specification of the Karstedt catalyst is 1000 ppm; the antioxidant is BASF light stabilizer 622; the yellowing inhibitor is TSA011; and the matting agent is nano titanium dioxide with a particle size of 0.35-0.5 μm.

[0122] Test examples

[0123] The polyurethane fibers prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to mechanical property, heat resistance and flame retardant property tests. The specific test results are shown in Table 1:

[0124] Table 1

[0125]

[0126] The detection of each index in Table 1 was carried out according to the following standards: the breaking strength was determined according to GB / T 14344-2008 “Chemical fibers - Filament tensile property test method”; the test method for the resilience rate was as follows: the polyurethane fibers prepared in Examples 1-5 and Comparative Examples 1-2 were stretched to 300% of the original length, fixed for 20 min, and then subjected to resilience performance test according to FZ / T 50007-2012 “Spandex filament elasticity test method”; the heat resistance was represented by the breaking strength retention rate, and was tested under dry heat conditions according to FZ / T 50033-2016 “Spandex filament heat resistance test method”; and the limiting oxygen index was tested according to GB / T 5454 “Textiles - Determination of burning behavior - Method of testing in an oxygen index apparatus”.

[0127] As can be seen from the test results in Table 1, the polyurethane fibers prepared in the present application have excellent flame retardant property and heat resistance, and good mechanical property and resilience.

[0128] In order to improve the comprehensive performance of the polyurethane fibers, 1,1,3,3-tetramethyldisiloxane is used as a bridging agent to connect the allyl modified DOPO and the allyl phenoxy cyclotriphosphazene, so as to prepare a flame retardant containing three flame-retardant elements of phosphorus, nitrogen and silicon, and because the hydroxyl functional groups exist in the flame retardant, the flame-retardant structure can be grafted and copolymerized in the polymer through participating in the polymerization of the polyurethane urea prepolymer, so as to improve the flame retardance and flame retardant durability of the material.

[0129] In addition, the flame retardant contains rigid structures such as cyclotriphosphazene and benzene ring, and the introduction of the rigid structures into the polyurethane urea matrix material can improve the mechanical property and heat resistance of the material; at the same time, the flame retardant can react with diisocyanate through the multiple hydroxyl groups, so as to increase the functionality of the reaction, and form a network structure in the polyurethane urea matrix material with the flame retardant center, thereby improving the mechanical property and elastic property of the fiber.

[0130] The present application uses the method of adding isocyanate twice when preparing polyurethane urea spinning solution, so that the free isocyanate added second time can easily form hard segment area with good crystallization property in chain extension process, thereby improving the crystallization property of the fiber, and crosslinking is produced at the same time, improving the resilience of the fiber. At the same time in the dry spandex forming process, the molecular chain orientation is promoted, so that the polyurethane material molecular chain can be more regularly arranged, and the thermal stability of the fiber material in macroscopic is improved.

[0131] The flame retardant of Comparative Example 1 uses allyl phenoxy cyclotriphosphazene, and the effect of allyl modified DOPO and 1,1,3,3-tetramethyl disiloxane on improving the flame retardant property is lacking, so the flame retardant property of Comparative Example 1 is not as good as that of the examples.

[0132] In the preparation of polyurethane fiber in Comparative Example 2, 4,4-diphenyl methane diisocyanate is added once, and the method of adding isocyanate twice can make it easily form hard segment area with good crystallization property in chain extension process, thereby improving the crystallization property of the fiber, and crosslinking is produced at the same time, improving the resilience of the fiber, so the breaking strength and resilience of Comparative Example 2 are not as good as those of the examples.

[0133] Although the embodiments of the present application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A process for the production of high-elasticity polyurethane flame- retardant fibers, characterized in that, The method comprises the following steps: Step (1), mixing allyl phenoxy cyclotriphosphazene, cast catalyst, tetrahydrofuran, heating, adding 1,1,3,3-tetramethyldisiloxane dropwise, after the dropwise addition is completed, reacting, after the reaction is completed, adding allyl modified DOPO, continuing to react, after the reaction is completed, rotary evaporation, to obtain a flame retardant; Step (2), reacting polytetrahydrofuran ether glycol and the first 4,4-diphenyl methane diisocyanate to obtain a prepolymer; dissolving the prepolymer and dimethylacetamide, adding the second 4,4-diphenyl methane diisocyanate and mixing uniformly, adding the flame retardant, continuing to react, after the reaction is completed, cooling, adding a chain extender, reacting again, after the reaction is completed, to obtain a polyurethane urea solution; Step (3), mixing the polyurethane urea solution with an antioxidant, a dyeing aid and a matting agent, dry spinning to obtain a high-elasticity polyurethane flame-retardant fiber.

2. The process for the production of high-elasticity polyurethane flame- retardant fibers according to claim 1, characterized in that, The allyl phenoxy cyclotriphosphazene in the step (1) is prepared by the following steps: Mixing and dissolving hexachlorocyclotriphosphazene, acetone and a catalyst potassium carbonate, adding a 2-allyl phenol acetone solution, reacting, after the reaction is completed, purifying to obtain the allyl phenoxy cyclotriphosphazene; The molar ratio of the hexachlorocyclotriphosphazene and the 2-allyl phenol is 1:6.5-7; the 2-allyl phenol acetone solution is prepared by mixing 2-allyl phenol and acetone at a mass ratio of 1:5-6; the mass ratio of the hexachlorocyclotriphosphazene, acetone and the catalyst potassium carbonate is 17-18:180-200:82-83; the reaction condition is that the reaction is carried out at a temperature of 40-50℃ for 12-15h.

3. The process for the production of high elasticity polyurethane flame retardant fiber according to claim 1, characterized in that, The allyl modified DOPO in the step (1) is prepared by the following steps: Melting DOPO, adding allyl glycidyl ether and a catalyst triphenylphosphine, reacting, after the reaction is completed, cooling to obtain the allyl modified DOPO; The molar ratio of the DOPO and the allyl glycidyl ether is 1:1-1.1; the catalyst triphenylphosphine is added in an amount of 0.5-0.8wt% of the mass sum of the DOPO and the allyl glycidyl ether; the reaction condition is that the reaction is carried out at a temperature of 130℃ for 10-12h in a nitrogen atmosphere.

4. The process for the production of high elasticity polyurethane flame retardant fiber according to claim 1, characterized in that, In the step (1), the mass ratio of the allyl phenoxy cyclotriphosphazene, 1,1,3,3-tetramethyldisiloxane, allyl modified DOPO, cast catalyst and tetrahydrofuran is 93-95:82-84.5:192-208:3-3.5:3500-4000; in the preparation of the flame retardant, the reaction condition is that the reaction is carried out at a temperature of 60-70℃ for 2-2.5h; the continuing reaction condition is that the reaction is continued at a temperature of 65-75℃ for 3-4h.

5. The process for the production of high elasticity polyurethane flame retardant fiber according to claim 1, characterized in that, In the step (2), the mass ratio of the polytetrahydrofuran ether glycol, the first 4,4-diphenyl methane diisocyanate, the second 4,4-diphenyl methane diisocyanate, the chain extender and the flame retardant is 340:75-80:23-25:80-90:50-60. The chain extender is prepared by mixing and dissolving ethylenediamine, propylenediamine, diethylamine and dimethylacetamide in a mass ratio of 5-5.1:3:0.5-0.6:90-100.

6. The process for the production of high elasticity polyurethane flame retardant fiber according to claim 1, characterized in that, In the step (2), the reaction condition is that the reaction is carried out at 80-85 ℃ for 2-2.5 h, the continuous reaction condition is that the reaction is continuously carried out at 70-75 ℃ for 0.5 h, and the re-reaction condition is that the re-reaction is carried out at 10 ℃ for 0.5-1 h.

7. The process for the production of high elasticity polyurethane flame retardant fiber according to claim 1, characterized in that, In the step (2), the solid content of the polyurethane urea solution is 30-40 wt%.

8. The process for the production of high elasticity polyurethane flame retardant fiber according to claim 1, characterized in that, In the step (3), the mass ratio of the polyurethane urea solution, the antioxidant, the yellowing inhibitor, and the matting agent is 1000:0.02-0.03:0.01-0.02:0.008-0.01, and the spinning speed of the dry spinning is 800-900 m / min, and the spinning drum atmosphere temperature is 250-270 ℃.

9. A high-elasticity polyurethane flame-retardant fiber prepared by the preparation method of the high-elasticity polyurethane flame-retardant fiber according to any one of claims 1-8.

10. Application of the high-elasticity polyurethane flame-retardant fiber according to claim 9 to stretchable electric wires.

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