Washable flame-retardant textile and preparation method thereof

Abstract

The invention discloses a washable flame-retardant textile and a preparation method thereof, and belongs to the technical field of functional textile production. According to the invention, tetrakis hydroxymethyl phosphonium sulfate, urea, a compound containing amino acid and water are used as a flame retardant system to treat the textile. Wherein hydroxymethyl in the tetrakis (hydroxymethyl) phosphonium sulfate reacts with amino in the urea to form a tetrakis (hydroxymethyl) phosphonium sulfate-urea prepolymer; carrying out self polycondensation on the tetrakis hydroxymethyl phosphonium sulfate-urea prepolymer, and meanwhile, further reacting residual unreacted hydroxymethyl in the tetrakis hydroxymethyl phosphonium sulfate with hydroxyl in fibers in the textile to form a water-insoluble cross-linked polymer; an amino acid-containing compound (such as non-toxic and harmless biomass bone glue) is adopted for reaction, and amino in the amino acid-containing compound reacts with hydroxymethyl. Finally, the flame-retardant textile is good in flame-retardant effect and washable, and environmental pollution, potential safety hazards and the like are effectively prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of flame-retardant textiles and its preparation method, especially a kind of washable flame-retardant textiles and its preparation method, belong to functional textile production technical field. BACKGROUND Textiles are made of cotton, hemp, silk, wool and other fibers, or polyester, polyamide and other synthetic fibers after textile processing, which are mostly composed of C, H, O elements, and have the disadvantage of being highly flammable. Once a fire occurs, it burns fiercely and easily causes the spread of fire, causing serious fire safety accidents. Therefore, how to improve the flame retardant performance of textiles and their products is a technical problem that needs to be solved.

[0002] To solve this technical problem, the prior art generally uses water-soluble flame retardants, which are impregnated and then dried, or directly coated on the fiber textiles to achieve the purpose of improving the flame retardant performance. Among them, the impregnation method has good flame retardant effect, but it is not resistant to washing; for the coating method, the flame retardant can form a protective film on the surface of the textile, preventing the spread of fire and heat conduction, thereby achieving the effect of flame retardation, but it is mainly suitable for fiber textile products, and the surface friction during use or washing easily causes the flame retardant to fall off, and the flame retardant effect cannot last long.

[0003] Currently, the proban method is a relatively successful method for flame-retardant cotton textiles, and the main component of the flame retardant is tetrahydroxy methyl phosphorus chloride-urea primary condensate (THPC-Urea). After the cotton textile is impregnated with THPC-Urea, it is smoked with ammonia to cross-link the flame retardant inside the fiber, and then oxidized with hydrogen peroxide, washed, and dried to obtain a flame-retardant textile. For example, CN115710819A discloses "Intermittent processing method of flame-retardant cellulose staple fiber and obtained flame-retardant cellulose staple fiber", in which the fiber is first treated with an alkali-containing swelling liquid, then dehydrated; then a tetrahydroxy methyl phosphorus compound aqueous solution is applied, and then dehydrated; then cross-linked and solidified by ammonia smoking; finally, oxidized with hydrogen peroxide, washed, and dried to obtain regenerated cellulose staple fiber. However, there are still some deficiencies, including: cross-linking and solidification by ammonia smoking requires a high level of equipment due to the use of ammonia gas; it easily releases ammonia gas, causing significant environmental pollution; and there is a safety hazard.

[0004] In addition, although the prior art "CN101560225A Preparation method of tetrahydroxy methyl phosphorus sulfate-urea primary condensate", "CN106400485A Preparation method of durable flame retardant for cotton fabric" and the like disclose "tetrahydroxy methyl phosphorus sulfate-urea" (prepolymer / primary condensate) as a washable flame retardant, they do not explain how to apply it to textiles, thus cannot guarantee the washability of the obtained flame-retardant textiles, and the CN106400485A uses the ammonia smoking method.

[0005] Therefore, improving the washability of flame-retardant textiles and avoiding the harm caused by ammonia fumigation are urgent technical problems that need to be solved. Summary of the Invention

[0006] To address the problems of poor flame retardant effect, poor water resistance, and environmental pollution and safety hazards caused by ammonia fumigation in existing flame retardant textiles, a water-resistant flame retardant textile and its preparation method are proposed. To achieve the above technical objectives, the following technical solution is proposed: The primary objective of this technical solution is to provide: a flame retardant system comprising tetramethylolphosphine sulfate, urea, an amino acid-containing compound, and water; The mass ratio of tetrahydroxymethylphosphoric acid, urea and water is 100:18 to 54:375, and the mass fraction of the amino acid-containing compound is 8 to 12%.

[0007] The second objective of this technical solution is to provide: a washable flame-retardant textile, which is prepared by using textiles made of viscose fiber as raw material, impregnating the textiles in tetramethylol phosphate-urea prepolymer, curing them by a step-by-step heating method, and then treating them with an amino acid-containing compound; Among them, textiles made from viscose fibers are regenerated fibers (i.e., viscose fibers containing a large amount of cellulose) made from wood pulp, which are various textiles that are spun, spun and / or woven; or, cotton products containing a large amount of hydroxyl groups. The finished product indicators of flame-retardant textiles include: after washing 20 times and drying at 105℃ for 1 hour, they cannot be ignited (according to the national standard GB / T 14644-2014 Determination of burning rate in the 45° direction of the burning performance of textiles).

[0008] The third objective of this technical solution is to provide a method for preparing a washable flame-retardant textile, comprising the following steps: S1: Preparation of tetrahydroxymethylphosphine sulfate-urea prepolymer In a mass ratio of 100:18 to 54:375, tetramethylol phosphate, urea, and water are mixed and circulated using a circulating pump for 8 to 12 minutes to dissolve the mixture. Then, the temperature is raised to 70 to 80°C using steam, and the heating is stopped. The reaction continues for 2 to 3 hours using the heat released from the reaction of tetramethylol phosphate and urea, during which the temperature is controlled not to exceed 85°C. After the reaction is completed, the mixture is cooled to below 30°C to obtain a tetramethylol phosphate-urea prepolymer solution. The specific mass ratio ensures that the prepolymer forms cross-links during subsequent curing. If there is too much or too little urea, although a cured product can be formed, the cross-linking will be insufficient, resulting in poor water resistance. The temperature must be controlled not to exceed 85℃ to stop the reaction before the gel point. If the temperature is too high, the prepolymer reaction will be uncontrolled, resulting in explosive polymerization to form an insoluble and infusible gel; if the temperature is too low, a large amount of urea will not participate in the reaction and will remain in the system. At the same time, the degree of cross-linking of the system will be insufficient, resulting in poor washability of the final flame-retardant textile product. The reaction formulas involved are as follows: ; S2: Impregnation and adsorption With a mass-to-volume ratio of 1:15-25, textiles are immersed in a tetrahydroxymethylphosphoric acid-urea prepolymer solution and circulated using a circulating pump for 110-130 minutes without heating. Then, the textiles are removed and centrifuged to dehydrate and dry, with the liquid content controlled at 80-100%, to obtain textiles with adsorbed flame-retardant prepolymer. The process involves the self-condensation of tetramethylolphosphine sulfate-urea prepolymer and its reaction with hydroxyl groups on textiles. Specifically, this includes the further reaction of residual active groups -NH2 and -CH2OH in the tetramethylolphosphine sulfate-urea prepolymer at higher temperatures to form crosslinks; and the reaction of some -CH2OH groups with active hydrogen in textiles to graft phosphorus-containing prepolymers onto them. The relevant reaction formulas (self-condensation of the prepolymer and reaction with hydroxyl groups on textiles) are as follows: ; S3: Thermosetting The textiles containing the obtained adsorbed flame-retardant prepolymer were cured in a blower-type drying oven at 85–140°C for 4–6 hours. After the temperature naturally dropped to room temperature, the textiles were removed to obtain crude flame-retardant textiles. In the curing process, a stepped temperature increase method is used for curing: Maintain at 85–95℃ for 1.5–2.5 hours; Maintain at 95–105℃ for 0.8–1.2 hours; Maintain at 105–115℃ for 0.8–1.2 hours; Maintain at 115–125℃ for 0.8–1.2 hours; Maintain at 125–135℃ for 0.3–0.7 hours; Among them, the step-heating curing method ensures that the prepolymer can be fully cross-linked and cured, while also allowing it to fully react with the hydroxyl groups on the textiles, thereby improving the flame retardant properties of the final textile product. S4: Post-processing Add 8-12% by mass of an amino acid-containing compound to the crude flame-retardant textile product, heat to 85-95℃, and react for 1.5-2.5 hours; remove and centrifuge to dehydrate; finally, dry in a forced-air drying oven at 100-110℃ to obtain the flame-retardant textile product. Among them, the amino acid-containing compounds are bone glue or whey protein. These compounds provide nitrogen (N) to improve flame retardancy and, on the other hand, block the -CH2OH groups, reacting with the remaining hydroxyl groups to reduce the harm to the skin and even the human body caused by residual -CH2OH from the flame retardant material (-CH2OH is similar to formaldehyde and may be harmful to the skin and even the human body; using amino acid-containing compounds can eliminate this harm; furthermore, amino acid-containing compounds have a similar structure to human proteins, resulting in good skin affinity). The involved reaction formulas (prepolymer self-condensation and the reaction of residual -CH2OH with amino acid-containing compounds) are as follows: .

[0009] The principles involved in this technical solution include: First, the hydroxymethyl group in tetramethylolpropionate (TMP) reacts with the amino group in urea to form a TMP-urea prepolymer. Second, the TMP-urea prepolymer undergoes self-condensation, while the unreacted hydroxymethyl group in TMP further reacts with the hydroxyl groups in textiles to form a water-insoluble cross-linked polymer. Finally, to further eliminate unreacted hydroxymethyl groups and increase the degree of cross-linking, compounds containing amino acids (such as non-toxic and harmless biomass collagen and whey protein) are used for the reaction. Among them, collagen / whey protein contains a large number of amino acids, and the amino groups can react with the hydroxymethyl groups.

[0010] The beneficial technical effects of adopting this technical solution are as follows: I. In this invention, a water-soluble prepolymer is mainly formed by combining a phosphorus-containing reactive chemical substance—tetramethylolphosphine sulfate—with another chemical substance—urea. The prepolymer has low viscosity, allowing it to penetrate the textile interior and ensuring uniform distribution of the flame retardant. Simultaneously, the prepolymer can undergo its own cross-linking and curing reaction, and can also react with the textile to form stable chemical bonds. The presence of these chemical bonds makes the flame-retardant properties of the textile more durable and less easily lost due to washing or other cleaning methods. This is significantly superior to existing flame-retardant coating methods and solves the problem of flame retardancy loss after washing. Second, all chemical substances used in the reaction process of this invention are environmentally friendly materials. In particular, no ammonia fumigation is used in the post-processing steps, therefore they are non-toxic and harmless, posing no irritation or harm to the human body or the environment. This is in stark contrast to traditional chemical modification methods that use flame retardants containing harmful substances, thus demonstrating significant environmental advantages.

[0011] Third, in this invention, amino acids or bone glue and whey protein containing amino acid units are used, which can eliminate the damage of residual -CH2OH to the skin and even the human body. At the same time, these substances are similar to human protein structures, have good skin affinity, and a better skin feel. In addition, compounds containing amino acids provide nitrogen, which improves flame retardancy. Attached Figure Description

[0012] Figure 1 The infrared spectra of the flame-retardant viscose fiber cloth, the flame-retardant viscose fiber cloth washed 20 times, and the viscose fiber cloth involved in Example 6 are shown. Figure 2 The thermogravimetric curves of the flame-retardant viscose fiber cloth, the flame-retardant viscose fiber cloth washed 20 times, and the viscose fiber cloth involved in Example 6 are shown. Figure 3 To illustrate the explosive polymerization of tetrahydroxymethylphosphonic acid (HPCS), urea, and water in Example 1 at excessively high temperatures, resulting in a white solid that is insoluble in water; Figure 4 To illustrate the prepolymers of tetramethylol phosphate sulfate and urea at different mass ratios in Example 2, after thermosetting and soaking in water, the following images are provided: (a) HPCS:Urea = 100:8; (b) HPCS:Urea = 100:18; (c) HPCS:Urea = 100:32; (d) HPCS:Urea = 100:54; (e) HPCS:Urea = 100:64. Figure 5 To discuss the tetramethylolphosphine sulfate-urea prepolymer in Example 3, the following images are shown after heat curing and soaking in water under different curing conditions: (a) 90℃ for 2 h, 100℃ for 1 h, 110℃ for 1 h, 120℃ for 1 h, and 130℃ for 0.5 h; (b) 90℃ for 1 h, 120℃ for 1 h, and 130℃ for 0.5 h; (c) 100℃ for 1 h, 120℃ for 1 h, and 130℃ for 0.5 h; (d) 120℃ for 2 h and 130℃ for 1 h; (e) 130℃ for 3 h. Figure 6 To discuss the comparison of viscose fiber cloth (untreated), flame-retardant viscose fiber cloth, and flame-retardant viscose fiber cloth washed 20 times in Example 5 before and after combustion, where A represents viscose fiber cloth (untreated), B represents flame-retardant viscose fiber cloth, and C represents flame-retardant viscose fiber cloth washed 20 times. Figure 7 Electron scan images of viscose fiber cloth (untreated), flame-retardant viscose fiber cloth, flame-retardant viscose fiber cloth washed 20 times, and flame-retardant viscose fiber cloth after burning are presented for discussion in Example 5. Figure 8 The energy dispersive spectroscopy (EDS) spectra of viscose fiber cloth (untreated), flame-retardant viscose fiber cloth, flame-retardant viscose fiber cloth washed 20 times, and flame-retardant viscose fiber cloth after burning are discussed in Example 5. Figure 9 This is the flame retardant performance test report (I) for the flame retardant textiles in Example 5. Figure 10 This is the flame retardant performance test report (II) for the flame retardant textiles in Example 5. Figure 11 This is the flame retardant performance test report (III) for the flame retardant textiles in Example 5. Figure 12 This is the flame retardant performance test report (I) for the flame retardant textiles in Example 6. Figure 13 This is the flame retardant performance test report (II) for the flame retardant textiles in Example 6. Figure 14 This is the flame retardant performance test report (III) for the flame retardant textiles in Example 6. Detailed Implementation

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0014] Firstly, in the field of textile technology, this invention provides a method for improving the flame retardant properties of viscose fibers, viscose fiber textiles, and other viscose fiber products. This solves the problems of existing technologies where the flame retardant properties of textiles are not washable and the manufacturing process causes significant environmental pollution and safety hazards. This method not only improves the flame retardant properties of textiles, but also provides a long-lasting effect, maintaining good flame retardant properties even after multiple washes. This will greatly improve the safety of textile products and meet consumers' demand for high-quality textile products. Secondly, in the field of flame-retardant materials, this invention provides a method for preparing flame-retardant textiles adapted to a flame-retardant system. This method not only possesses excellent flame-retardant properties but also produces no environmental pollution, meeting current environmental protection requirements. The flame-retardant system involved can be widely applied to various materials requiring flame-retardant properties, such as building materials and vehicle interior materials. This will greatly promote the application of flame-retardant materials in various fields, meeting society's demand for efficient and environmentally friendly flame-retardant materials. In summary, this invention has broad application prospects and significant market demand, and is expected to play an important role in the fields of textile technology, fiber materials, and flame-retardant materials.

[0015] This will be illustrated with the following example.

[0016] Example 1 This embodiment provides: a flame retardant system comprising tetramethylolphosphine sulfate, urea, an amino acid-containing compound, and water; The mass ratio of tetramethylolphosphine sulfate, urea and water is 100:18 to 54:375. The mass fraction of the amino acid-containing compound is 8–12%.

[0017] Example 2 This embodiment provides: a washable flame-retardant textile, which is made from textiles prepared from viscose fibers. The textiles are impregnated in tetramethylolphosphine sulfate-urea prepolymer and cured by a step-by-step heating method; then, it is prepared by treatment with an amino acid-containing compound. The finished product indicators of the flame-retardant textiles include: after being washed 20 times and dried at 105°C for 1 hour, they cannot be ignited (according to the national standard GB / T 14644-2014 Determination of the burning rate of textiles in the 45° direction).

[0018] Example 3 This embodiment provides a method for preparing a washable flame-retardant textile, comprising the following steps: S1: Preparation of tetrahydroxymethylphosphine sulfate-urea prepolymer Tetramethylolphosphine sulfate, urea, and water were mixed at a mass ratio of 100:18:375 and circulated for 10 minutes using a circulating pump to dissolve the mixture. Then, the temperature was raised to 72°C using steam, and the heating was stopped. The reaction was carried out for 2 hours using the heat released from the reaction of tetramethylolphosphine sulfate and urea, during which the temperature was controlled not to exceed 85°C. After the reaction was completed, the mixture was cooled to below 30°C to obtain a tetramethylolphosphine sulfate-urea prepolymer solution. S2: Impregnation and adsorption With a mass-to-volume ratio of 1:15, textiles are immersed in a tetrahydroxymethyl phosphate-urea prepolymer solution and circulated for 110 minutes using a circulating pump without heating. Then, the textiles are removed and centrifuged to remove water and dry, with the liquid content controlled at 80-100%, to obtain textiles with adsorbed flame-retardant prepolymer. S3: Thermosetting The product was cured at 85°C for 4 hours using a forced-air drying oven. After the temperature naturally dropped to room temperature, it was taken out to obtain the crude flame-retardant textile product. In the curing process, a stepped temperature increase method is used for curing: 85℃, maintain for 1.5 hours; 95℃, maintain for 0.8 hours; 105℃, hold for 0.8 hours; 115℃, maintain for 0.8 hours; 125℃, hold for 0.3 hours; S4: Post-processing An amino acid-containing compound with a mass fraction of 8% was added to the crude flame-retardant textile product, the temperature was raised to 85°C, and the reaction was carried out for 1.5 hours. The product was then removed, centrifuged and dehydrated using a centrifuge, and finally dried in a forced-air drying oven at 100°C to obtain the flame-retardant textile product.

[0019] Example 4 This embodiment provides a method for preparing a washable flame-retardant textile, comprising the following steps: S1: Preparation of tetrahydroxymethylphosphine sulfate-urea prepolymer Tetramethylolphosphine sulfate, urea, and water were mixed at a mass ratio of 100:54:375 and circulated for 12 minutes using a circulating pump to dissolve the mixture. Then, the temperature was raised to 78°C using steam, and the heating was stopped. The reaction was carried out for 3 hours using the heat released from the reaction of tetramethylolphosphine sulfate and urea, during which the temperature was controlled not to exceed 85°C. After the reaction was completed, the mixture was cooled to below 30°C to obtain a tetramethylolphosphine sulfate-urea prepolymer solution. S2: Impregnation and adsorption With a mass-to-volume ratio of 1:25, textiles are immersed in a tetrahydroxymethylphosphoric acid-urea prepolymer solution and circulated for 130 minutes using a circulating pump without heating. Then, the textiles are removed and centrifuged to dehydrate and dry, with the liquid content controlled at 80-100%, to obtain textiles with adsorbed flame-retardant prepolymer. S3: Thermosetting The product was cured at 140℃ for 6 hours using a forced-air drying oven. After the temperature naturally dropped to room temperature, it was taken out to obtain the crude flame-retardant textile product. In the curing process, a stepped temperature increase method is used for curing: 95℃, maintain for 2.5 hours; 105℃, maintain for 1.2 hours; 115℃, maintain for 1.2 hours; 125℃, maintain for 1.2 hours; 135℃, hold for 0.7 hours; S4: Post-processing A compound containing amino acids with a mass fraction of 12% was added to the crude flame-retardant textile product, the temperature was raised to 95°C, and the reaction was carried out for 2.5 hours. The product was then removed, centrifuged and dehydrated using a centrifuge, and finally dried in a blower-type drying oven at 110°C to obtain the flame-retardant textile product.

[0020] Example 5 This embodiment provides a method for preparing a washable flame-retardant textile, comprising the following steps: S1: Preparation of tetrahydroxymethylphosphine sulfate-urea prepolymer Tetramethylolphosphine sulfate, urea, and water were mixed in a mass ratio of 100:35:375 and circulated for 8 minutes using a circulating pump to dissolve the mixture. Then, the temperature was raised to 75°C using steam, and the heating was stopped. The reaction was carried out for 2.5 hours using the heat released from the reaction of tetramethylolphosphine sulfate and urea, during which the temperature was controlled not to exceed 85°C. After the reaction was completed, the mixture was cooled to below 30°C to obtain a tetramethylolphosphine sulfate-urea prepolymer solution. S2: Impregnation and adsorption With a mass-to-volume ratio of 1:20, textiles (specifically fabrics) are immersed in a tetrahydroxymethyl phosphate-urea prepolymer solution and circulated for 120 minutes using a circulating pump without heating. Then, the textiles are removed and centrifuged to dehydrate and dry, with the liquid content controlled at 80-100%, to obtain textiles with adsorbed flame-retardant prepolymer. S3: Thermosetting The product was cured at 110℃ for 5 hours using a forced-air drying oven. After the temperature naturally dropped to room temperature, it was taken out to obtain the crude flame-retardant textile product. In the curing process, a stepped temperature increase method is used for curing: 90℃, keep for 2 hours; 100℃, keep for 1 hour; 110℃, keep for 1 hour; 120℃, keep for 1 hour; 130℃, maintain for 0.5 hours; S4: Post-processing A compound containing amino acids with a mass fraction of 10% was added to the crude flame-retardant textile product, the temperature was raised to 90℃, and the reaction was carried out for 2 hours. The product was then removed, centrifuged and dehydrated using a centrifuge, and finally dried in a forced-air drying oven at 105℃ to obtain the flame-retardant textile product, denoted as MZ-A.

[0021] The flame retardant performance of MZ-A was tested according to the national standard GB / T 14644-2014, and the results are as follows: Figures 9-11 As shown.

[0022] Example 6 This embodiment provides a method for preparing a water-resistant, flame-retardant viscose fiber fabric, comprising the following steps: I. Preparation of flame-retardant prepolymer: In a dyeing vat, add tetramethylol phosphate, urea, and water in a mass ratio of 100:36:375. Start the circulation pump for 10 minutes to dissolve the urea and mix it evenly. Then, turn on the steam heating switch and gradually raise the temperature to 75°C. Stop heating and let the reaction proceed for 3 hours, relying on the heat released by the reaction of tetramethylol phosphate and urea. During this period, the temperature should not exceed 85°C. After the reaction is complete, cool to below 30°C to obtain the flame-retardant prepolymer. II. Impregnation and adsorption of flame-retardant prepolymer on viscose fiber cloth: Add viscose fiber cloth to a dyeing vat containing flame-retardant prepolymer, control the liquor ratio at 20:1, start the circulation pump and circulate for 120 minutes without heating; then, remove the viscose fiber cloth, dehydrate it using a centrifuge, and control the liquid carry-over rate to 80-100%; 3. Heat curing of viscose fiber cloth with adsorbed flame retardant prepolymer: Place the dehydrated flame retardant prepolymer in a forced-air drying oven and cure it using a stepped heating method: keep it at 90℃ for 2 hours, at 100℃ for 1 hour, at 110℃ for 1 hour, at 120℃ for 1 hour, and at 130℃ for 0.5 hours; turn off the power and wait for the temperature to drop naturally to room temperature before taking out the coarse flame retardant viscose fiber cloth. IV. Post-processing of flame-retardant viscose fiber cloth: Place the flame-retardant viscose fiber cloth in a dyeing vat, add an amino acid aqueous solution (concentration of 10%, for example, according to a bath ratio of 20:1, 20 parts amino acid aqueous solution: 1 part viscose fiber cloth), heat to 90℃, and react for 2 hours; remove, dehydrate and spin dry using a centrifuge, spread out, and place in a forced-air drying oven to dry at 100℃ to obtain flame-retardant viscose fiber cloth, denoted as MZ-B.

[0023] test 1) The obtained flame-retardant viscose fiber cloth was subjected to a water washing test: The flame-retardant viscose fiber cloth was placed in a washing machine and washed 20 times with ordinary laundry detergent (such as Blue Moon) in the standard washing mode. After each wash, the viscose fiber cloth was placed in a constant temperature drying oven and dried at 80℃ for 2 hours to obtain flame-retardant treated and then washed viscose fiber cloth. Then, the viscose fiber fabric after washing was tested using GB / T5455-1997 "Vertical Method for Testing the Burning Performance of Textiles". It was found that the limiting oxygen index (%) of the flame-retardant viscose fiber fabric after 20 washes was 32.8; the limiting oxygen index (%) of the blank control (untreated viscose fiber fabric) was 19.2. 2) Infrared spectroscopy and thermogravimetric analysis were performed on flame-retardant viscose fiber cloth that had been washed 20 times, flame-retardant viscose fiber cloth (unwashed), and viscose fiber cloth (untreated and unwashed). The results are as follows: Figures 1-2 As shown, the thermogravimetric curve is the curve showing the change in residual weight of viscose fiber cloth with temperature as the temperature rises from room temperature to 700℃ under a nitrogen atmosphere.

[0024] It can be known that: Figure 1 In the middle, viscose fiber cloth at 1560cm -1 No infrared response peak was observed at this location. Both the flame-retardant viscose fiber cloth and the flame-retardant viscose fiber cloth showed a peak value of 1560 cm⁻¹ after 20 washes. -1 The presence of an infrared response peak indicates that the flame-retardant viscose fiber cloth still contains flame retardant after 20 washes, meaning that the flame-retardant viscose fiber cloth has water-resistant properties. Figure 2In the study, the residual carbon content of viscose fiber cloth at 690℃ was 5.95%, close to 0%, meaning it was almost completely decomposed; while the residual carbon content of flame-retardant viscose fiber cloth was 29.25%. After 20 washes, the residual carbon content of flame-retardant viscose fiber cloth decreased slightly, but still remained at 25.45%.

[0025] 3) The flame retardant performance of MZ-B was tested according to the national standard GB / T 14644-2014, and the results are as follows: Figures 12-14 As shown.

[0026] Discussion of Example 1 Based on Example 6, the reaction temperature (which should not exceed 85°C) during the preparation of tetrahydroxymethyl phosphate-urea prepolymer is discussed.

[0027] During small-scale testing, it was found that when the temperature of tetrahydroxymethylphosphonic acid (HPCS), urea, and water was too high (reaction temperature exceeding 85℃), the reaction became uncontrolled, resulting in explosive polymerization and the formation of a white solid insoluble in water (such as...). Figure 3 As shown in the figure, it can no longer be used to process textiles, etc.

[0028] Therefore, the design involves first preparing a tetramethylolpropionate (TMP)-urea prepolymer from tetramethylolpropionate (TMP) and urea, and then treating textiles with this prepolymer. Next, under compatible conditions, the TMP-urea prepolymer is induced to form a water-insoluble solid that adheres to the fibers of the textile, resulting in a washable, flame-retardant textile. This eliminates the need for ammonia fumigation to achieve cross-linking, reducing environmental hazards and atmospheric pollution.

[0029] Discussion of Example 2 Based on Example 6, the ratio of tetramethylol phosphate sulfate to urea in the preparation process of the urea prepolymer is discussed.

[0030] To ensure that the flame-retardant textiles retain good flame-retardant properties even after multiple washes, the mass ratio of tetramethylolphosphine sulfate to urea was controlled at 100:18-54. Based on the water resistance performance of blank thermosetting prepolymer samples (viscose fiber cloth), a suitable ratio was selected. The principle is that the better the water resistance of the prepolymer after thermosetting (soaking in water for 48 hours, changing the water 3 times during this period; then drying, and measuring the percentage of the remaining weight relative to the original prepolymer), that is, the higher the residual percentage after soaking in water, the better the water resistance of the flame-retardant viscose fiber cloth under this ratio. The results are as follows Figure 4 As shown in Table 1.

[0031] Table 1 shows the weight changes of prepolymers obtained with different ratios of HPCS and Urea after thermosetting and immersion in water.

[0032] It can be seen that when the amount of urea is small, although the surface of the thermosetting product is relatively smooth, the water resistance is poor, the residual percentage of the thermosetting product is only 80.52%, and the product is relatively soft. As the amount of urea increases, the roughness of the thermosetting product increases, the hardness of the thermosetting product increases, and the residual percentage of the thermosetting product increases. However, when the amount of urea is too large, there are more leaching substances, and the pores of the thermosetting product increase significantly after soaking in water.

[0033] Discussion of Example 3 Based on Example 6, the temperature during the thermosetting process is discussed.

[0034] Five sets of stepped heating methods were used for curing, and the results are as follows: Figure 5 As shown in Table 2.

[0035] Five sets of stepped heating methods: (a) Keep at 90℃ for 2 hours, 100℃ for 1 hour, 110℃ for 1 hour, 120℃ for 1 hour, and 130℃ for 0.5 hours; (b) Keep at 90℃ for 1 hour, at 120℃ for 1 hour, and at 130℃ for 0.5 hours; (c) Keep at 100℃ for 1 hour, at 120℃ for 1 hour, and at 130℃ for 0.5 hours; (d) Keep at 120℃ for 2 hours, then keep at 130℃ for 1 hour; (e) Keep at 130℃ for 3 hours; Table 2 shows the weight changes of the prepolymer after thermosetting and immersion in water under different heating conditions.

[0036] It can be seen that temperatures below 100℃ are conducive to the full reaction of hydroxymethyl and amino groups, while temperatures above 100℃ are mainly in the post-curing stage. The longer the baking time below 100℃, the better it is for the oligomers to gradually form high molecular weight polymers and achieve sufficient cross-linking. If the low-temperature time is too short or the temperature is directly raised to above 100℃, the hydroxymethyl and amino groups will not have enough time to react fully and will decompose spontaneously. In particular, urea will be thermally decomposed and consumed, resulting in insufficient cross-linking and poor water resistance. Figure 5 It can also be seen that when the temperature is directly raised to above 100℃, the number of pores increases significantly. This is due to the release of low-molecular-weight substances, and the flame retardant effect also deteriorates accordingly.

[0037] Discussion of Example 4 Based on Example 6, the addition of amino acid-containing compounds during the post-processing is discussed.

[0038] In the coarse product of flame-retardant viscose fiber cloth, residual unreacted hydroxymethyl groups still possess reactivity. To eliminate their influence, compounds containing amino acids are specifically selected for the reaction. Preferably, bone glue provides the amino acids or amino acid units, i.e., bone glue is used as the reactant. Bone glue is derived from animal bones, contains a large amount of protein (composed of amino acids), is non-toxic and harmless, and is similar to human protein, thus having good skin affinity and a better skin feel.

[0039] In the post-processing: 10% by mass of bone glue aqueous solution was added to the crude flame-retardant viscose fiber cloth, the temperature was raised to 90℃, and the reaction was carried out for 2 hours; the cloth was taken out and centrifuged to dehydrate and dry; finally, it was dried at 100℃ in a blower-type drying oven to obtain flame-retardant viscose fiber cloth.

[0040] The effect of post-treatment was evaluated by determining the residual hydroxymethyl content in flame-retardant viscose fiber fabric before and after treatment. The determination of hydroxymethyl content was carried out in accordance with GB 5545-85 "Determination of Hydroxymethyl Formaldehyde Content in Resin Finishing Agents"; It can be seen that: the hydroxymethyl content in the flame-retardant viscose fiber cloth before treatment was 1100mg / Kg; the hydroxymethyl content in the flame-retardant viscose fiber cloth after treatment was reduced to 86mg / Kg; and the surface of the flame-retardant viscose fiber cloth after treatment was smoother and more delicate to the touch.

[0041] Discussion of Example 5 Based on Example 6, the states of the viscose fiber cloth before and after flame retardant treatment, the flame retardant viscose fiber cloth before and after combustion, and the flame retardant viscose fiber cloth before and after washing are discussed to further illustrate the present invention.

[0042] The combustion treatment methods involved include: 1. The samples of viscose fiber cloth (blank control, without flame retardant treatment), flame retardant viscose fiber cloth and flame retardant viscose fiber cloth washed 20 times were all cut into strips with a size of 50mm×150mm. 2. Clip the cloth strip sample to the iron beam with a book clip, let it hang naturally, and test its combustion performance in the air; 3. Light the cotton cloth from the bottom with a burning alcohol lamp, start timing, remove the alcohol lamp after 5 seconds of burning, observe the burning phenomenon and test the burning distance; The comparison of viscose fiber cloth, flame-retardant viscose fiber cloth, and flame-retardant viscose fiber cloth after 20 washes before and after combustion is shown below. Figure 6 As shown, it was found that: viscose fiber cloth burns rapidly and is basically completely burned; flame-retardant viscose fiber cloth extinguishes immediately upon removal from the flame, showing a significant flame-retardant effect; the flame-retardant effect of viscose fiber cloth washed 20 times is slightly lower, and the burning distance becomes longer, but it still has the characteristic of extinguishing immediately upon removal from the flame. I. The flame-retardant viscose fiber cloth obtained in Example 6, the viscose fiber cloth, the flame-retardant viscose fiber cloth washed 20 times, and the flame-retardant viscose fiber cloth after combustion were all subjected to electron scanning (field emission scanning electron microscope (SEM); Thermo Fisher Apreo 2C, energy dispersive spectroscopy OXFORD ULTIM Max65). The results are as follows: Figure 7 As shown; It can be seen that the fibers in viscose fiber cloth are relatively loose; the fibers in flame-retardant viscose fiber cloth and flame-retardant viscose fiber cloth washed 20 times are relatively tight, and there are some solid substances on the surface, which are the flame-retardant materials that are adhered; the fibrous morphology of the flame-retardant viscose fiber cloth after burning is still clearly visible, and there are a large number of bubble-like solid substances. This is because the flame-retardant material decomposes and carbonizes during combustion, preventing further combustion.

[0043] II. The flame-retardant viscose fiber cloth obtained in Example 6, the viscose fiber cloth, the flame-retardant viscose fiber cloth washed 20 times, and the flame-retardant viscose fiber cloth after combustion were subjected to energy dispersive spectroscopy (EDS) tests to determine the nitrogen and phosphorus elements in the flame-retardant cotton cloth (Field Emission Scanning Electron Microscope (SEM); Thermo Fisher Apreo 2C, Energy Dispersive Spectrometer OXFORD ULTIM Max65). The results are as follows: Figure 8 As shown in Table 3; Table 3 Results of elemental content determination

[0044] It can be seen that the weight percentages of nitrogen (N) and phosphorus (P) in viscose fiber fabric are 0%; the N and P contents in flame-retardant viscose fiber fabric are 2.56% and 4.00%, respectively; after 20 washes, the N content slightly increases and the P content slightly decreases; after combustion, the N and P contents both increase, reaching 4.98% and 7.86%, respectively, while the carbon content increases compared to flame-retardant cotton fabric. This indicates that the addition of flame-retardant materials can dehydrate and carbonize the fibers in viscose fiber fabric, covering the fiber surface and preventing further combustion.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A flame retardant system characterized in that, tetramethylolmethane phosphonic acid sulfate, urea, an amino acid-containing compound, and water; The mass ratio of the tetramethylolmethane phosphonic acid sulfate, the urea, and the water is 100:18-54:

375.

2. The flame retardant system according to claim 1, characterized in that The mass fraction of the amino acid-containing compound is 8-12%.

3. A wash durable flame resistant textile characterized in that, The flame-retardant textile is prepared by dipping a textile prepared from viscose fibers in a tetramethylolmethane phosphonic acid sulfate-urea prepolymer, and curing the textile in a stepwise heating mode; and then treating the textile with an amino acid-containing compound. After being washed with water for 20 times and dried at 105°C for 1h, the flame-retardant textile cannot be ignited.

4. A process for the preparation of a wash durable flame resistant textile characterized in that, The method comprises the following steps: Impregnation and adsorption: the textile is dipped in a tetramethylolmethane phosphonic acid sulfate-urea prepolymer solution at a mass-to-volume ratio of 1:15-25; and then the textile is dehydrated to obtain the textile adsorbed with the flame-retardant prepolymer at a belt liquid rate of 80-100%; Heat curing: the textile adsorbed with the flame-retardant prepolymer is cured at 85-140°C for 4-6h to obtain a crude flame-retardant textile; and the curing is performed in a stepwise heating mode: 85-95°C, for 1.5-2.5h; 95-105°C, for 0.8-1.2h; 105-115°C, for 0.8-1.2h; 115-125°C, for 0.8-1.2h; 125-135°C, for 0.3-0.7h; Post-treatment: the crude flame-retardant textile is added with the amino acid-containing compound at a mass fraction of 8-12%, and heated to 85-95°C for 1.5-2.5h; and then the textile is dehydrated and dried to obtain the flame-retardant textile.

5. A process for the preparation of a wash durable flame resistant textile according to claim 4, characterized in that, The method for preparing the tetramethylolmethane phosphonic acid sulfate-urea prepolymer solution comprises: tetramethylolmethane phosphonic acid sulfate, urea, and water are mixed at a mass ratio of 100:18-54:375, and dissolved; after being heated to 70-80°C, the mixture is reacted for 2-3h, during which the temperature is controlled to be not higher than 85°C; after the reaction is completed, the mixture is cooled to below 30°C to obtain the tetramethylolmethane phosphonic acid sulfate-urea prepolymer solution.

6. A process for the preparation of a wash durable flame resistant textile according to claim 5, characterized in that, During the dissolving, a circulating pump is used to circulate for 8-12min.

7. The method of making a wash durable flame resistant textile according to claim 4, wherein, The textile is a textile prepared from viscose fibers.

8. The method of making a wash durable flame resistant textile according to claim 4, wherein, During the dipping, a circulating pump is used to circulate for 110-130min.

9. The method of making a wash durable flame resistant textile according to claim 4, wherein, The amino acid-containing compound is bone glue or whey protein.

10. A process for the preparation of a wash durable flame resistant textile according to claim 4, characterized in that, During the heat curing, a forced-air drying oven is used for the curing; and during the post-treatment, a forced-air drying oven is used for the drying.

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