Flame-retardant regenerated cellulose fiber for environment-friendly and efficient clothing and preparation method of flame-retardant regenerated cellulose fiber

Abstract

The invention provides a flame-retardant regenerated cellulose fiber for environment-friendly and efficient clothing and a preparation method of the flame-retardant regenerated cellulose fiber, and relates to the field of regenerated cellulose fibers. The preparation method of the flame-retardant regenerated cellulose fiber for the environment-friendly and efficient clothing comprises the following steps: preparing an efficient flame retardant dispersing system, preparing a blended spinning stock solution, spinning and forming, and performing post-treatment. According to the environment-friendly and efficient flame-retardant regenerated cellulose fiber for clothing and the preparation method thereof, the flame-retardant performance of the flame-retardant regenerated cellulose fiber for clothing can be improved, the phosphorus content and the sulfur content of the flame-retardant regenerated cellulose fiber for clothing are reduced, the environment-friendly performance of the flame-retardant regenerated cellulose fiber for clothing is improved, the biological irritation is reduced, and the safety of clothing is improved; the mechanical property, the whiteness and the comfort of the flame-retardant regenerated cellulose fiber for clothing are further improved.

Description

Technical Field

[0001] The invention relates to the field of regenerated cellulose fibers, and in particular to an environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber and a preparation method thereof. Background Art

[0002] With the continuous expansion of the application fields of textile products, fires caused by the burning of fibers and their products have become one of the major disasters in modern society, seriously threatening people's lives and property safety. In the face of this serious social problem, people have paid more and more attention to the development of flame-retardant fibers and their textiles to effectively prevent the occurrence of fires. Many scientific research institutions and companies at home and abroad have carried out a lot of research work. The European Union, the United States, Japan and many other countries have passed strict laws and regulations, requiring the use of flame-retardant fibers or textiles in certain specific places, and the application scope and requirements of flame-retardant fibers and their textiles are becoming increasingly stringent.

[0003] Regenerated cellulose fiber is a biomass fiber made from cellulose. It has excellent moisture absorption, breathability and wearing comfort, and is widely used in clothing, home textiles and other fields. Among them, viscose fiber has the largest output, and the global annual output of viscose fiber will reach 6.5 million tons in 2023. With the gradual improvement of people's requirements for quality of life and the continuous demand for green, low-carbon and sustainable development in the fiber field under the background of "dual carbon", people have an increasing demand for the comfort, spinning performance and environmental protection of regenerated cellulose fiber. Therefore, the continued development of a fiber that meets multiple requirements such as flame retardancy, comfort and environmental protection has become a problem that needs to be solved.

[0004] In this context, flame-retardant fibers and their textiles have received more and more attention. Flame-retardant fibers and their textiles mainly play a protective role. When encountering open flames or high-temperature substances, they can play an isolating and protective role to prevent the spread of fire. Finland's Kemira Company (now Sateri Company), Weifang Xinlong and other companies have successively developed inorganic flame-retardant viscose fibers based on silicates, which have the advantages of low cost, high heat resistance, and low smoke toxicity; however, the flame retardant efficiency of silicon-based flame retardants is low, and the amount required to be added is large, resulting in poor mechanical strength of flame-retardant regenerated cellulose fiber products. It is only suitable for non-woven materials and fillers, and cannot be used in the field of clothing textiles.

[0005] In industrial production, the application prospects of flame-retardant textiles are very broad. In addition to playing an irreplaceable role in industrial textiles, building interior decoration, and transportation interior decoration, they also play an important role in protective clothing and other clothing fields. Organic phosphorus flame retardants have high flame retardant efficiency and require less addition. They can be used to develop high-quality flame-retardant regenerated cellulose fibers. For example, Germany's Hoechest, Japan's Asahi Chemical, and Switzerland's Clariant have successively developed a series of phosphorus-based flame-retardant regenerated cellulose fibers. Among them, dithiodipyrophosphate (DDPS) is the mainstream flame retardant for phosphorus-based flame-retardant regenerated cellulose fibers. It was first developed by Swiss Sandoz (i.e. Clariant). The Lenzing FR fiber produced by Austrian Lenzing has excellent performance and meets the requirements for wearing. It is widely recognized by users, but its comprehensive production cost is high, resulting in a high final selling price. At the same time, in order to obtain better flame retardant properties, the phosphorus content and sulfur content of existing ingestible flame retardant regenerated cellulose fibers using organic phosphorus flame retardants are still relatively high. On the one hand, it has environmental pollution problems such as water pollution and air pollution, is not environmentally friendly, and has high biological irritation; on the other hand, it will lead to a decrease in other properties of the regenerated cellulose fibers (such as mechanical properties, whiteness, and comfort).

[0006] Thus, an environmentally friendly and efficient oral flame-retardant regenerated cellulose fiber and a preparation method thereof are provided, which can improve the flame retardant properties of the oral flame-retardant regenerated cellulose fiber while reducing the phosphorus content and sulfur content of the oral flame-retardant regenerated cellulose fiber, thereby improving its environmental performance, reducing biological irritation, improving the safety of oral flame-retardant regenerated cellulose fiber, and further improving the mechanical properties, whiteness and comfort of the oral flame-retardant regenerated cellulose fiber. This has important technical significance and research value, and is also of great significance for improving the market competitiveness of oral flame-retardant regenerated cellulose fibers and promoting the application and promotion of oral flame-retardant regenerated cellulose fibers. Summary of the invention

[0007] In view of the deficiencies of existing products and technologies, the present invention provides an environmentally friendly and efficient edible flame-retardant regenerated cellulose fiber, which can reduce the phosphorus content and sulfur content of the edible flame-retardant regenerated cellulose fiber while improving the flame-retardant properties of the edible flame-retardant regenerated cellulose fiber, thereby improving its environmental performance, reducing biological irritation, improving the safety of consumption, and further improving the mechanical properties, whiteness and comfort of the edible flame-retardant regenerated cellulose fiber; the present invention also provides a method for preparing an environmentally friendly and efficient edible flame-retardant regenerated cellulose fiber.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing environmentally friendly and highly efficient flame-retardant regenerated cellulose fibers, comprising the following steps: preparing a highly efficient flame retardant dispersion system, preparing a blended spinning solution, spinning and forming, and post-processing; The method for preparing a high-efficiency flame retardant dispersion system comprises the following steps: preparing a flame retardant synergist and co-dispersing the synergistic agent; The method for preparing the flame retardant synergist comprises: contacting melamine with a formaldehyde solution to obtain a hydroxymethyl melamine solution; contacting a tetramethyl piperidine derivative with the hydroxymethyl melamine solution to obtain a solid, separating the solid and drying it to obtain the flame retardant synergist; The synergistic dispersion method comprises: mixing a flame retardant synergist with dithiopyrophosphate to obtain a composite flame retardant system; grinding the composite flame retardant system, an auxiliary agent and deionized water uniformly to obtain a high-efficiency flame retardant system; treating the high-efficiency flame retardant system with a coupling agent to obtain a high-efficiency flame retardant dispersion system; The method for preparing the blended spinning solution is to add a high-efficiency flame retardant dispersion system into the regenerated cellulose spinning solution to obtain the blended spinning solution; The spinning method comprises spinning with a blended spinning solution to obtain a formed filament bundle; The formed tow is post-processed to obtain environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber.

[0009] Preferably, in the preparation of the flame retardant synergist, the formaldehyde solution is a formaldehyde solution with a concentration of 37 wt %, or a mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %; The molar ratio of melamine to total formaldehyde in the formaldehyde solution is 1:2.5-3.5.

[0010] Preferably, in the preparation of the flame retardant synergist, the tetramethylpiperidine derivative is tetramethylpiperidinamine or tetramethylpiperidinol; The molar ratio of the tetramethylpiperidine derivative to the methylolmelamine in the methylolmelamine solution is 1:1-2.

[0011] Furthermore, in the preparation of the flame retardant synergist, the pH value of the environment in which melamine and formaldehyde solution are contacted and reacted is 7.5-9.0, the contact reaction temperature is 75-85° C., and the contact reaction time is 50-80 min.

[0012] Preferably, in the mixed solution of the paraformaldehyde and the formaldehyde solution with a concentration of 37 wt %, the weight ratio of the paraformaldehyde to the formaldehyde solution is 1:2-2.5.

[0013] Furthermore, in the preparation of the flame retardant synergist, the pH value of the environment in which the tetramethylpiperidine derivative is contacted with the hydroxymethylmelamine solution is 4-6, the contact reaction temperature is 60-80° C., and the contact reaction time is 60-80 min.

[0014] Preferably, in the synergistic dispersion, the weight ratio of the flame retardant synergist to the dithiopyrophosphate is 1-2:1; The mass fraction of the composite flame retardant system in deionized water is 30-40%; During the grinding process, the grinding was controlled to a particle size D90 < 1.350 um.

[0015] Furthermore, in the collaborative dispersion, the auxiliary agents include dispersants, wetting agents, and defoaming agents; The amount of the dispersant added is 15-20% of the weight of the composite flame retardant system; The amount of the wetting agent added is 3-6% of the weight of the composite flame retardant system; The added amount of the defoamer is 2-5% of the weight of the composite flame retardant system.

[0016] Preferably, in the coordinated dispersion, the grinding speed is controlled to be 3000-3500 r / min, and the grinding temperature is maintained at 18-20° C. during the grinding process.

[0017] Preferably, in the collaborative dispersion, the dispersant is at least one of the following: sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, polyvinyl pyrrolidone, sodium methylene bisnaphthalene sulfonate, sodium carboxymethyl cellulose, sodium hexametaphosphate; The wetting agent is at least one of the following: diethylene glycol, pull-opening powder BX; The defoaming agent is at least one of the following: polyoxypropylene glycerol ether, polyoxypropylene polyoxyethylene glycerol ether, and polydimethylsiloxane.

[0018] Preferably, in the synergistic dispersion, the coupling agent is added in an amount of 6-10% by weight of the high-efficiency flame retardant system; The coupling agent is a silane coupling agent or a titanate coupling agent; The silane coupling agent is at least one of the following: silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH570; the titanate coupling agent is at least one of the following: titanate coupling agent TC-27, titanate coupling agent TC-WT.

[0019] Furthermore, in the collaborative dispersion, the coupling agent treats the high-efficiency flame retardant system at a temperature of 50-60° C. and a treatment time of 30-50 min.

[0020] Preferably, in the preparation of the blended spinning solution, the cellulose alpha content of the regenerated cellulose spinning solution is 8.90-9.21wt%; The added weight of the high-efficiency flame retardant dispersion system is 17.5-20% of the weight of type A cellulose in the regenerated cellulose spinning solution.

[0021] Furthermore, zinc acetate is also added to the blended spinning solution; The added weight of sodium zincate is 0.05-0.1% of the weight of type A cellulose in the regenerated cellulose spinning solution.

[0022] Preferably, in the preparation of the blended spinning solution, the components and properties of the regenerated cellulose spinning solution are as follows: the content of type A cellulose is 8.90-9.21wt%, the content of sodium hydroxide is 5.51-5.82wt%, the falling ball viscosity is 70-81s, the degree of maturity (10% NH4Cl value) is 25-32mL, and the degree of viscose esterification is 65-78.

[0023] Furthermore, a denaturant is added to the preparation of the blended spinning solution; The added weight of the denaturant is 2.5-4.0% of the weight of type A cellulose in the regenerated cellulose spinning solution; the weight ratio of urea, polyethylene glycol (PEG-1500) and polyoxyethylene alkylphenol ether in the denaturant is 1:1-2:2-3.

[0024] Furthermore, in the spinning process, a blended spinning solution is used for spinning to obtain a nascent filament bundle; the nascent filament bundle enters a first molding bath and is stretched once, then enters a second molding bath and is stretched twice, and then enters a third molding bath and is stretched three times to obtain a formed filament bundle.

[0025] Preferably, the first molding bath includes: 90-100 g / L sulfuric acid, 260-280 g / L sodium sulfate, 28.0-40.0 g / L zinc sulfate, and the solvent is water; the temperature of the first molding bath is 42-45°C, and the drafting rate is -40% to -20%; The second molding bath is an air bath, the relative humidity is controlled at 75-85%, the temperature of the second molding bath is 70-85℃, and the second drafting rate is 60-90%; The third molding bath includes: sulfuric acid 20-25g / L, zinc sulfate <2g / L, and the solvent is water; the temperature of the third molding bath is 96-99°C, and the three-pass drawing rate is 10-15%.

[0026] Furthermore, the post-treatment method is that the formed tow is cut, web-formed, washed once, desulfurized, washed twice, acid-washed, washed three times, washed four times, bleached, oiled, opened, and dried to obtain environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber.

[0027] Furthermore, in the web forming, high temperature steam is used to agitate the web laying, the web forming steam pressure is 0.15-0.25 MPa, and the web forming liquid temperature is 95-99°C.

[0028] Furthermore, in the desulfurization, the desulfurization bath used includes: Na2SO3 7.0-10.0g / L, the solvent is water; the desulfurization bath temperature is 70-80°C.

[0029] Furthermore, in the bleaching, the bleaching bath used is a hydrogen peroxide solution with a hydrogen peroxide concentration of 1.0-1.5 g / L; the bleaching temperature is 55-60° C. and the pH value is 8.0-9.0.

[0030] Furthermore, in the oiling, the oiling bath used is a mixed bath solution of an oil agent and a weak acid; the oil agent content in the oiling bath is 6.0-10.5 g / L, and the weak acid content is 4.0-8.0 g / L; the oiling temperature is 55-65°C, and the pH value is 6.0-6.5; after oiling, the fiber oil content is controlled to be 0.41-0.65%, and the fiber pH is 6.7-6.9.

[0031] Preferably, the weak acid is lactic acid or citric acid.

[0032] Furthermore, in the drying, three-stage steam drying is adopted; the drying temperature of the first stage is 110-120°C, the drying temperature of the second stage is 115-130°C, and the drying temperature of the third stage is 105-90°C. After drying, the moisture regain of the fiber is controlled within the range of 10-13%.

[0033] The invention discloses an environmentally friendly and highly effective flame-retardant edible regenerated cellulose fiber, which is prepared by the above-mentioned preparation method.

[0034] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for preparing the environmentally friendly and highly efficient flame-retardant edible regenerated cellulose fiber of the present invention comprises the following steps: preparing a flame retardant synergist with a specific high nitrogen content, and then combining the flame retardant synergist with dithiopyrophosphate to prepare a high-efficiency flame retardant system, and then treating the flame retardant system with a coupling agent to combine the flame retardant elements (such as silicon and phosphorus) in the flame retardant to prepare a high-efficiency flame retardant dispersion system with multi-element synergy (phosphorus, nitrogen, silicon, etc.) and multi-mechanism joint flame retardancy (condensed phase flame retardancy, gas phase flame retardancy, and physical endothermic properties). Then, the high-efficiency flame retardant dispersion system is used in the preparation of a blended spinning stock solution, and after spinning and post-treatment, an environmentally friendly and highly efficient flame-retardant edible regenerated cellulose fiber is prepared. The method can improve the flame retardant properties of the edible flame-retardant regenerated cellulose fiber while reducing the phosphorus content and sulfur content of the edible flame-retardant regenerated cellulose fiber, thereby improving its environmental performance, reducing biological irritation, and improving the safety of wearing. The method can further improve the mechanical properties, whiteness and comfort of the edible flame-retardant regenerated cellulose fiber, thereby further improving the market competitiveness of the edible flame-retardant regenerated cellulose fiber and promoting the application and promotion of the edible flame-retardant regenerated cellulose fiber.

[0035] (2) The environmentally friendly and efficient flame-retardant regenerated cellulose fiber of the present invention has excellent flame-retardant properties as well as good environmental protection and physical and mechanical properties. The phosphorus content of the environmentally friendly and efficient flame-retardant regenerated cellulose fiber is ≤1.45%, and the sulfur content of the fiber is ≤1.53% (inductively coupled plasma test method). Compared with Lenzing FR fiber and existing similar products, the phosphorus content is reduced by more than 47.08%, and the sulfur content is reduced by more than 45.36%. The limiting oxygen index of the fiber is ≥30.5% (FZ / T50016-2011). Compared with the best level of existing similar products, the limiting oxygen index is increased by more than 2.69%. At the same time, the dry breaking strength of the fiber is ≥2.21 cN / dtex, the dry breaking elongation is ≥19.2%, the wet breaking strength is ≥1.13 cN / dtex (GB / T14337-2022), and the whiteness is ≥80. 9% (FZ / T50013-2008); and the free formaldehyde content in the fiber is low (≤75mg / kg) (GB / T2921.1-2009), the irritation to the skin is low (the average of the highest skin irritation reaction score is ≤0.5) (GB / T21604-2022), and the safety is high; the environmentally friendly and efficient wearable flame-retardant regenerated cellulose fiber combines functionality, comfort and practicality, has better environmental protection and flame retardant effect, and has a wide range of applications. It can be used in home textiles, clothing, especially flame retardant protective clothing.

[0036] (3) The preparation method of the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber of the present invention is to prepare a flame retardant synergist with a specific high nitrogen content, and then prepare a high-efficiency flame retardant system by combining the flame retardant synergist with dithiopyrophosphate, and then treat it with a coupling agent, and combine the flame retardant elements (such as silicon, phosphorus, etc.) in the flame retardant to prepare a high-efficiency flame retardant dispersion system with multi-element synergy (phosphorus, nitrogen, silicon, etc.) and multi-mechanism joint flame retardancy (condensed phase flame retardancy, gas phase flame retardancy, and physical endothermic properties, etc.), which together give the prepared fiber good flame retardant properties. The inventor has found through research that according to the characteristics of the prepared high-efficiency flame retardant system, the high-efficiency flame retardant system is treated with a coupling agent, which not only makes the dispersibility and dispersion stability of the effective ingredients of the high-efficiency flame retardant system more excellent, but also enables the cellulose and the high-efficiency flame retardant system to have a better effect during the fiber forming process. At the same time, it can also effectively reduce the content of elements such as P and S in the fiber and improve environmental protection.

[0037] (4) The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber of the present invention comprises the following steps: in the preparation of the blended spinning solution, sodium zincate is added by pre-spinning injection to further slow down the fiber forming and improve the mechanical properties of the fiber; three forming baths and three drawing steps are used in the spinning forming process; wherein the first forming bath is low acid, high zinc and low sodium to delay the forming treatment of the spinning solution, and is combined with negative drawing to make the filament bundle have a higher degree of esterification when leaving the first forming bath; the second forming bath is a high humidity hot air bath, and the forming bath components brought out by the filament bundle are further formed under high humidity, and the drawing force is increased to make the fiber have a higher orientation and strength; at the same time, the temperature of the second forming bath is relatively high, which is convenient for connection with the third forming bath; the third forming bath is plasticized and drawn at a relatively high temperature, and the drawing is relatively small, so that the fiber partially shrinks, further improving the fiber performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a morphological diagram of the high-efficiency flame retardant dispersion system prepared in Example 1 of the present invention.

[0039] Figure 2 The particle size, i.e., the particle size distribution diagram, of the high-efficiency flame retardant dispersion system prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0041] The invention provides a method for preparing an environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber for consumption, comprising the following steps: preparing a highly efficient flame retardant dispersion system, preparing a blended spinning solution, spinning and forming, and post-processing.

[0042] The preparation of the high-efficiency flame retardant dispersion system comprises the following steps: preparing a flame retardant synergist and co-dispersing.

[0043] The method for preparing the flame retardant synergist comprises the following steps: preparing a hydroxymethyl melamine solution and a reaction preparation.

[0044] The method for preparing the hydroxymethyl melamine solution is to weigh melamine and formaldehyde solution and add them to a volume of 2m 3 The mixture is stirred and mixed evenly at a speed of 300-500 r / min. The pH value is adjusted to 7.5-9.0 with a triethanolamine solution or a NaOH solution. The mixture in the reaction kettle is heated to 75-85° C., and the mixture is stirred and reacted for 50-80 minutes under heat preservation to obtain a transparent solution of hydroxymethyl melamine, i.e., a hydroxymethyl melamine solution.

[0045] In the preparation of the hydroxymethyl melamine solution, the formaldehyde solution is a formaldehyde solution with a concentration of 37 wt %, or a mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %; in the mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %, the weight ratio of paraformaldehyde to the formaldehyde solution is 1:2; The molar ratio of melamine to total formaldehyde in the formaldehyde solution is 1:2.5-3.5.

[0046] The method of the reaction preparation is to add a tetramethylpiperidine derivative to a hydroxymethylmelamine solution, adjust the mixed solution to acidity (pH=4-6) under vigorous stirring (stirring speed 1000-1500r / min), keep the mixture stirred at 60-80°C until the solution becomes a white turbid liquid, and continue the reaction for 60-80 minutes; filter, wash with water, adjust the pH to 7.5-9 with a sodium hydroxide solution, and obtain a large amount of white solid products. The solid products are dried and solidified at 90-105°C to obtain a flame retardant synergist. The flame retardant synergist contains a large amount of N element, which can effectively synergize with the subsequent flame retardant to achieve flame retardancy.

[0047] In the reaction preparation, the tetramethylpiperidine derivative is tetramethylpiperidinamine or tetramethylpiperidinol; The molar ratio of the tetramethylpiperidine derivative to the methylolmelamine in the methylolmelamine solution is 1:1-2.

[0048] The synergistic dispersion comprises the following steps: preparing a high-efficiency flame retardant system and preparing a high-efficiency flame retardant dispersion system.

[0049] The method for preparing the high-efficiency flame retardant system comprises: uniformly mixing a flame retardant synergist and a flame retardant dithiopyrophosphate at a weight ratio of 1-2:1 to obtain a composite flame retardant system; adding the composite flame retardant system into deionized water, controlling the mass fraction of the composite flame retardant to be 30-40wt%, and continuously adding a dispersant (the amount added is 15-20% of the weight of the composite flame retardant system), a wetting agent (the amount added is 3-6% of the weight of the composite flame retardant system), and a defoaming agent (the amount added is 2-5% of the weight of the composite flame retardant system), stirring and mixing evenly, and then adding the mixture into a sand mill for grinding, controlling the grinding speed to be 3000-3500r / min, and maintaining the grinding temperature at 18-20°C during the grinding process; and continuously testing the particle size during the grinding process until the particle size D90 is less than 1.350um to obtain the high-efficiency flame retardant system.

[0050] In the system for preparing the high-efficiency flame retardant, the dispersant is at least one of the following: sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, polyvinyl pyrrolidone, sodium methylene bisnaphthalene sulfonate, sodium carboxymethyl cellulose, sodium hexametaphosphate; The wetting agent is at least one of the following: diethylene glycol, pull-opening powder BX; The defoaming agent is at least one of the following: polyoxypropylene glycerol ether, polyoxypropylene polyoxyethylene glycerol ether, and polydimethylsiloxane.

[0051] The method for preparing the high-efficiency flame retardant dispersion system is to add a coupling agent to the high-efficiency flame retardant system for surface modification, control the amount of the coupling agent added to be 6-10% of the weight of the high-efficiency flame retardant system, and then stir and mix for 30-50 minutes at a temperature of 50-60°C to obtain the final high-efficiency flame retardant dispersion system. The morphology of the high-efficiency flame retardant dispersion system is as follows Figure 1 The particle size and its particle size distribution are shown in Figure 2 shown.

[0052] In the preparation of the high-efficiency flame retardant dispersion system, the coupling agent is a silane coupling agent or a titanate coupling agent; the silane coupling agent is at least one of the following: silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH570; the titanate coupling agent is at least one of the following: titanate coupling agent TC-27, titanate coupling agent TC-WT. By using the coupling agent, the dispersibility and dispersion stability of the high-efficiency flame retardant dispersion system are improved, and the subsequent interaction with cellulose is enhanced.

[0053] The method for preparing the blended spinning solution is to use cellulose pulp as a raw material to prepare a regenerated cellulose spinning solution, first add a denaturant to the regenerated cellulose spinning solution, and then add a high-efficiency flame retardant dispersion system and sodium zincate to the regenerated cellulose spinning solution by pre-spinning injection to obtain the blended spinning solution.

[0054] In the preparation of the blended spinning solution, the components and properties of the regenerated cellulose spinning solution are as follows: the content of type A cellulose is 8.90-9.21wt%, the content of sodium hydroxide is 5.51-5.82wt%, the falling ball viscosity is 70-81s, the maturity (10% NH4Cl value) is 25-32mL, and the viscose esterification degree is 65-78.

[0055] The added weight of the denaturant is 2.5-4.0% relative to the weight of type A cellulose in the regenerated cellulose spinning solution. The denaturant is a compound of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether; the weight ratio of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether in the denaturant is 1:1:3. Adding a denaturant to the preparation of the blended spinning solution, the coordination of the denaturant components can not only delay the fiber forming, but also improve the tensile properties of the fiber; the urea therein can not only act as a denaturant, but also has the effect of swelling the fiber, which can increase the diffusion distance of the components of the first molding bath for subsequent spinning molding and delay the molding; and combined with the use of other denaturant components, the molding can be further delayed.

[0056] The added weight of the high-efficiency flame retardant dispersion system is 17.5-20% of the weight of the type A cellulose in the regenerated cellulose spinning solution.

[0057] The added weight of the sodium zincate is 0.05-0.1% relative to the weight of type A cellulose in the regenerated cellulose spinning solution.

[0058] The spinning forming method is to use a blended spinning solution for spinning, and the nascent filament bundle enters a first forming bath and is drawn once, then enters a second forming bath and is drawn twice, and then enters a third forming bath and is drawn three times to obtain a formed filament bundle.

[0059] In the spinning process, the solvent of the first forming bath is water, including: 90-100 g / L sulfuric acid, 260-280 g / L sodium sulfate, 28.0-40.0 g / L zinc sulfate; the temperature of the first forming bath is 42-45°C, and the drafting rate is -40% to -20%; The second molding bath is an air bath, the relative humidity is controlled at 75-85%, the temperature of the second molding bath is 70~85℃, and the second drafting (inter-disk drafting) rate is 60-90%; The solvent of the third molding bath is water, including: sulfuric acid 20-25g / L, zinc sulfate <2g / L; the temperature of the third molding bath is 96-99°C, and the three-pass drawing rate is 10-15%.

[0060] The post-treatment method is as follows: the formed tow is cut, web-formed, washed once, desulfurized, washed twice, acid-washed, washed three times, washed four times, bleached, oiled, opened, and dried to obtain environmentally friendly and highly efficient flame-retardant regenerated cellulose fibers.

[0061] In the post-processing, high-temperature steam is used to agitate the web during web formation, the web forming steam pressure is 0.15-0.25 MPa, and the web forming liquid temperature is 95-99° C. The solvent of the desulfurization bath used in desulfurization is water, including: Na2SO37.0-10.0g / L; the desulfurization bath temperature is 70-80℃; The bleaching bath used in bleaching is a hydrogen peroxide solution with a hydrogen peroxide concentration of 1.0-1.5 g / L; the bleaching temperature is 55-60°C and the pH value is 8.0-9.0.

[0062] In the post-treatment, the oiling bath used in the oiling adopts a mixed bath solution (oil agent + weak acid); the oil agent concentration in the oiling bath is 6.0-10.5g / L, the weak acid concentration is 4.0-8.0g / L, the oiling temperature is 55-65℃, and the pH value is 6.0-6.5; the weak acid used is lactic acid or citric acid; after oiling, the oil content of the fiber is controlled to be 0.41-0.65%, and the fiber pH is 6.7-6.9. Since a large amount of granular substances are added during the fiber spinning process, the concentration of the oil bath is increased in the oiling process, the amount of oil agent is increased, and the feel of the fiber is improved; and the fiber is given weak acidity through oiling to match the pH value of the human body and meet the health and safety needs of the human body.

[0063] The drying process adopts three-stage steam drying. The first stage drying temperature is 110-120℃, the second stage drying temperature is 115-130℃, and the third stage drying temperature is 105-90℃. After drying, the fiber regain is controlled at 10-13%.

[0064] The present invention also provides an environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber prepared by the above-mentioned preparation method.

[0065] Example 1 This embodiment provides an environmentally friendly and efficient method for preparing flame-retardant regenerated cellulose fibers for consumption, which is specifically as follows: 1. Preparation of high-efficiency flame retardant dispersion system 1) Preparation of flame retardant synergist ① Preparation of hydroxymethyl melamine solution Weigh melamine and formaldehyde solution and add to a volume of 2m 3 The mixture was stirred and mixed evenly at a speed of 300 r / min. The pH value was adjusted to 7.5 with a NaOH solution. The mixture in the reaction kettle was heated to 85° C. and stirred for 50 minutes to obtain a transparent solution of hydroxymethyl melamine, i.e., a hydroxymethyl melamine solution.

[0066] The formaldehyde solution is a mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %. In the mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %, the weight ratio of paraformaldehyde to the formaldehyde solution is 1:2.

[0067] The molar ratio of melamine to total formaldehyde in the formaldehyde solution is 1:2.5.

[0068] ②Reaction preparation A tetramethylpiperidine derivative is added to a hydroxymethylmelamine solution, and the mixed solution is adjusted to acidity (pH=4) under vigorous stirring (stirring speed 1000r / min), and the mixture is stirred and reacted at 70°C until the solution becomes a white turbid liquid, and the reaction is continued for 80 minutes; after filtering and washing with water, the pH is adjusted to 7.5 with a sodium hydroxide solution to obtain a large amount of white solid product, and the solid product is dried and solidified at 90°C to obtain a flame retardant synergist.

[0069] Among them, the tetramethylpiperidine derivative is tetramethylpiperidinamine.

[0070] The molar ratio of the tetramethylpiperidine derivative to the hydroxymethylmelamine in the hydroxymethylmelamine solution is 1:1.

[0071] 2) Collaborative decentralization ①Preparation of high-efficiency flame retardant system The flame retardant synergist and the flame retardant dithiopyrophosphate are mixed evenly in a weight ratio of 1:1 to obtain a composite flame retardant system; the composite flame retardant system is added into deionized water, the mass fraction of the composite flame retardant is controlled to be 30wt%, and the dispersant (the added amount is 15% of the weight of the composite flame retardant system), the wetting agent (the added amount is 3% of the weight of the composite flame retardant system), and the defoaming agent (the added amount is 2% of the weight of the composite flame retardant system) are continued to be added, and after stirring and mixing evenly, the mixture is added into a sand mill for grinding, the grinding speed is controlled to be 3000r / min, and the grinding temperature is maintained at 20°C during the grinding process; the particle size is continuously tested during the grinding process until the particle size D90=1.293um, and a high-efficiency flame retardant system is obtained.

[0072] The dispersant is sodium dodecylbenzene sulfonate; the wetting agent is diethylene glycol; and the defoaming agent is polyoxypropylene glycerol ether.

[0073] ②Preparation of high-efficiency flame retardant dispersion system A coupling agent was added to the high-efficiency flame retardant system for surface modification, and the amount of the coupling agent added was controlled to be 10% of the weight of the high-efficiency flame retardant system, and then stirred and mixed for 50 minutes at a temperature of 50°C to obtain the final high-efficiency flame retardant dispersion system. The morphology of the high-efficiency flame retardant dispersion system prepared in this embodiment is as follows: Figure 1 The particle size and its particle size distribution are shown in Figure 2 shown.

[0074] Wherein, the coupling agent is silane coupling agent KH550.

[0075] 2. Preparation of blended spinning solution The regenerated cellulose spinning solution is prepared by using cellulose pulp as raw material. A denaturant is firstly added into the regenerated cellulose spinning solution. Then, a high-efficiency flame retardant dispersion system and sodium zincate are added into the regenerated cellulose spinning solution by pre-spinning injection to obtain a blended spinning solution.

[0076] The components and properties of the regenerated cellulose spinning solution are as follows: the content of type A cellulose is 8.90wt%, the content of sodium hydroxide is 5.51wt%, the falling ball viscosity is 70s, the degree of maturity (10% NH4Cl value) is 25mL, and the degree of viscose esterification is 65.

[0077] The added weight of the denaturant is 4.0% relative to the weight of type A cellulose in the regenerated cellulose spinning solution. The denaturant is a compound of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether; the weight ratio of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether in the denaturant is 1:1:2.

[0078] The added weight of the high-efficiency flame retardant dispersion system is 17.5% of the weight of type A cellulose in the regenerated cellulose spinning solution.

[0079] The added weight of sodium zincate is 0.1% relative to the weight of type A cellulose in the regenerated cellulose spinning solution.

[0080] 3. Spinning Spinning is carried out using a blended spinning solution. The nascent filament bundle enters the first molding bath and is drawn once, then enters the second molding bath and is drawn twice, and then enters the third molding bath and is drawn three times to obtain a molded filament bundle.

[0081] The solvent of the first molding bath is water, including: 90 g / L sulfuric acid, 260 g / L sodium sulfate, and 40.0 g / L zinc sulfate; the temperature of the first molding bath is 42° C., and the first drawing rate is -20%.

[0082] The second molding bath is an air bath, and the relative humidity is controlled to be 85%, the temperature of the second molding bath is 85°C, and the second drafting (inter-disk drafting) rate is 90%.

[0083] The solvent of the third molding bath is water, including: 20 g / L sulfuric acid, 1.65 g / L zinc sulfate; the temperature of the third molding bath is 99° C., and the three-pass drawing rate is 15%.

[0084] 4. Post-processing The formed tow is cut, web-formed, washed once, desulfurized, washed twice, acid-washed, washed three times, washed four times, bleached, oiled, opened, and dried to obtain environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber.

[0085] Among them, high-temperature steam is used to agitate the web laying, the web forming steam pressure is 0.15MPa, and the web forming liquid temperature is 95°C.

[0086] The solvent of the desulfurization bath used in desulfurization is water, including: Na2SO37.0g / L; the desulfurization bath temperature is 80℃.

[0087] The bleaching bath used in bleaching is a hydrogen peroxide solution with a hydrogen peroxide concentration of 1.0 g / L; the bleaching temperature is 60° C. and the pH value is 8.0.

[0088] The oiling bath used in oiling adopts a mixed bath solution (oil agent + weak acid); the oil agent concentration in the oiling bath is 6.0g / L, the weak acid concentration is 4.0g / L, the oiling temperature is 65°C, and the pH value is 6.5; the weak acid used is citric acid; after oiling, the fiber oil content is controlled to be 0.41%, and the fiber pH is 6.9.

[0089] The oil used in this embodiment is produced by Japan Takemoto Oil Co., Ltd., and the oil is a mixture of HONOL MGR-H and HONOL GA; the weight ratio of HONOL MGR-H to HONOL GA is 5:5.

[0090] The drying process uses three-stage steam drying, with the first stage drying temperature at 110°C, the second stage drying temperature at 115°C, and the third stage drying temperature at 105°C. After drying, the fiber moisture regain is controlled within the range of 10-13%.

[0091] This embodiment also provides an environmentally friendly, highly efficient, edible flame-retardant regenerated cellulose fiber prepared by the above method.

[0092] The environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber prepared in this embodiment has excellent flame-retardant function, good environmental protection and physical and mechanical properties. The phosphorus content of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 1.29wt%, and the sulfur content is 1.35wt%. Compared with LenzingFR fiber and existing similar products, the phosphorus content is reduced by 52.96%, and the sulfur content is reduced by 51.78%. The limiting oxygen index of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 30.5%, which is 2.69% higher than the best level of existing similar products. The environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber has a dry breaking strength of 2.56cN / dtex, a dry breaking elongation of 21.2%, a wet breaking strength of 1.41cN / dtex, and a whiteness of 85%, which meets the requirements of industry standard superior products; at the same time, the free formaldehyde in the fiber is low (41mg / kg), the irritation to the skin is low (the average score of the highest irritation reaction to the skin is 0), and the safety is high.

[0093] Example 2 This embodiment provides an environmentally friendly and efficient method for preparing flame-retardant regenerated cellulose fibers for consumption, comprising the following steps: 1. Preparation of high-efficiency flame retardant dispersion system 1) Preparation of flame retardant synergist ① Preparation of hydroxymethyl melamine solution Weigh melamine and formaldehyde solution and add to a volume of 2m 3 The mixture was stirred and mixed evenly at a speed of 410 r / min. The pH value was adjusted to 8.2 with triethanolamine solution. The mixture in the reaction kettle was heated to 81° C. and stirred for 66 minutes to obtain a transparent solution of hydroxymethyl melamine, i.e., a hydroxymethyl melamine solution.

[0094] The formaldehyde solution is a formaldehyde solution with a concentration of 37 wt %.

[0095] The molar ratio of melamine to total formaldehyde in the formaldehyde solution is 1:3.

[0096] ②Reaction preparation A tetramethylpiperidine derivative was added to a hydroxymethylmelamine solution, and the mixed solution was adjusted to acidity (pH=5.1) under vigorous stirring (stirring speed 1265r / min). The mixture was stirred and reacted at 68°C until the solution became a white turbid liquid. The reaction was continued for 72 minutes. After filtration and washing, the pH was adjusted to 8.2 with a sodium hydroxide solution to obtain a large amount of white solid product. The solid product was dried and solidified at 96°C to obtain a flame retardant synergist.

[0097] Wherein, the tetramethylpiperidine derivative is tetramethylpiperidinol.

[0098] The molar ratio of the tetramethylpiperidine derivative to the hydroxymethylmelamine in the hydroxymethylmelamine solution is 1:1.5.

[0099] 2) Collaborative decentralization ①Preparation of high-efficiency flame retardant system The flame retardant synergist and the flame retardant dithiopyrophosphate were mixed evenly in a weight ratio of 1:1 to obtain a composite flame retardant system; the composite flame retardant system was added into deionized water, the mass fraction of the composite flame retardant was controlled to be 35wt%, and the dispersant (the added amount was 17.6% of the weight of the composite flame retardant system), the wetting agent (the added amount was 4.9% of the weight of the composite flame retardant system), and the defoaming agent (the added amount was 3.6% of the weight of the composite flame retardant system) were continued to be added, and after stirring and mixing evenly, the mixture was added into a sand mill for grinding, the grinding speed was controlled to be 3255r / min, and the grinding temperature was maintained at 19°C during the grinding process; the particle size was continuously tested during the grinding process until the particle size D90=1.269um, and a high-efficiency flame retardant system was obtained.

[0100] The dispersant is sodium carboxymethyl cellulose; the wetting agent is diethylene glycol; and the defoaming agent is polyoxypropylene glycerol ether.

[0101] ②Preparation of high-efficiency flame retardant dispersion system A coupling agent was added to the high-efficiency flame retardant system for surface modification, and the amount of the coupling agent added was controlled to be 8.5% of the weight of the high-efficiency flame retardant system. Then, the mixture was stirred and reacted at a temperature of 56°C for 44 minutes to obtain the final high-efficiency flame retardant dispersion system.

[0102] Wherein, the coupling agent is silane coupling agent KH570.

[0103] 2. Preparation of blended spinning solution The regenerated cellulose spinning solution is prepared by using cellulose pulp as raw material. A denaturant is firstly added into the regenerated cellulose spinning solution. Then, a high-efficiency flame retardant dispersion system and sodium zincate are added into the regenerated cellulose spinning solution by pre-spinning injection to obtain a blended spinning solution.

[0104] The components and properties of the regenerated cellulose spinning solution are as follows: the content of type A cellulose is 9.05wt%, the content of sodium hydroxide is 5.68wt%, the falling ball viscosity is 76s, the maturity (10% NH4Cl value) is 28.5mL, and the degree of viscose esterification is 72.

[0105] The added weight of the denaturant is 3.6% of the weight of cellulose alpha in the regenerated cellulose spinning solution. The denaturant is a compound of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether; the weight ratio of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether in the denaturant is 1:2:3.

[0106] The added weight of the high-efficiency flame retardant dispersion system is 20% of the weight of the type A cellulose in the regenerated cellulose spinning solution.

[0107] The added weight of sodium zincate is 0.08% relative to the weight of type A cellulose in the regenerated cellulose spinning solution.

[0108] 3. Spinning Spinning is carried out using a blended spinning solution. The nascent filament bundle enters the first molding bath and is drawn once, then enters the second molding bath and is drawn twice, and then enters the third molding bath and is drawn three times to obtain a molded filament bundle.

[0109] The solvent of the first molding bath is water, including: 96 g / L sulfuric acid, 271 g / L sodium sulfate, and 35.2 g / L zinc sulfate; the temperature of the first molding bath is 43.5° C., and the first drawing rate is -32%.

[0110] The second molding bath is an air bath, and the relative humidity is controlled to be 81%. The temperature of the second molding bath is 78°C, and the second drafting (inter-disk drafting) rate is 76%.

[0111] The solvent of the third molding bath is water, including: 22 g / L sulfuric acid, 1.72 g / L zinc sulfate; the temperature of the third molding bath is 97.5°C, and the three-pass drawing rate is 12.6%.

[0112] 4. Post-processing The formed tow is cut, web-formed, washed once, desulfurized, washed twice, acid-washed, washed three times, washed four times, bleached, oiled, opened, and dried to obtain environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber.

[0113] Among them, high-temperature steam is used to agitate the web laying, the web forming steam pressure is 0.21MPa, and the web forming liquid temperature is 97°C.

[0114] The solvent of the desulfurization bath used in the desulfurization is water, including: Na2SO38.7g / L; the desulfurization bath temperature is 75.5℃.

[0115] The bleaching bath used in bleaching is a hydrogen peroxide solution with a hydrogen peroxide concentration of 1.23 g / L; the bleaching temperature is 58.2°C and the pH value is 8.5.

[0116] The oiling bath used in oiling adopts a mixed bath solution (oil agent + weak acid); the oil agent concentration in the oiling bath is 8.9g / L, the weak acid concentration is 6.5g / L, the oiling temperature is 61°C, and the pH value is 6.2; the weak acid used is citric acid; after oiling, the fiber oil content is controlled to be 0.55%, and the fiber pH is 6.7.

[0117] The oil used in this embodiment is produced by Japan Takemoto Oil Co., Ltd., and the oil is a mixture of HONOL MGR-H and HONOL GA; the weight ratio of HONOL MGR-H to HONOL GA is 6:4.

[0118] The drying process uses three-stage steam drying, with the first stage drying temperature at 116°C, the second stage drying temperature at 122°C, and the third stage drying temperature at 96°C. After drying, the fiber moisture regain is controlled within the range of 10-13%.

[0119] This embodiment also provides environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fibers prepared by the aforementioned preparation method.

[0120] The environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber prepared in this embodiment has excellent flame-retardant function, good environmental protection and physical and mechanical properties. The phosphorus content of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 1.45wt%, and the sulfur content is 1.53wt%. Compared with LenzingFR fiber and existing similar products, the phosphorus content is reduced by 47.08%, and the sulfur content is reduced by 45.36%. The limiting oxygen index of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 31.5%, which is 6.06% higher than the best level of existing similar products. The dry breaking strength of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 2.31cN / dtex, the dry breaking elongation is 19.9%, the wet breaking strength is 1.25cN / dtex, and the whiteness is 81.5%, which meets the requirements of industry standard superior products; at the same time, the free formaldehyde in the fiber is low (56mg / kg), the irritation to the skin is low (the average score of the highest irritation reaction to the skin is 0), and the safety is high.

[0121] Example 3 This embodiment provides an environmentally friendly and efficient method for preparing flame-retardant regenerated cellulose fibers for consumption, comprising the following steps: 1. Preparation of high-efficiency flame retardant dispersion system 1) Preparation of flame retardant synergist ① Preparation of hydroxymethyl melamine solution Weigh melamine and formaldehyde solution and add to a volume of 2m 3 The mixture was stirred and mixed evenly at a speed of 500 r / min. The pH value was adjusted to 9.0 with a NaOH solution. The mixture in the reaction kettle was heated to 85° C. and stirred for 80 minutes to obtain a transparent solution of hydroxymethyl melamine, i.e., a hydroxymethyl melamine solution.

[0122] The formaldehyde solution is a mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %. In the mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %, the weight ratio of paraformaldehyde to the formaldehyde solution is 1:2.2.

[0123] The molar ratio of melamine to total formaldehyde in the formaldehyde solution is 1:3.5.

[0124] ②Reaction preparation A tetramethylpiperidine derivative is added to a hydroxymethylmelamine solution, and the mixed solution is adjusted to acidity (pH=6) under vigorous stirring (stirring speed 1500r / min), and the mixture is stirred and reacted at 80°C until the solution becomes a white turbid liquid. The reaction is continued for 60 minutes; after filtration and washing, the pH is adjusted to 9 with a sodium hydroxide solution to obtain a large amount of white solid product, and the solid product is dried and solidified at 105°C to obtain a flame retardant synergist.

[0125] Among them, the tetramethylpiperidine derivative is tetramethylpiperidinamine.

[0126] The molar ratio of the tetramethylpiperidine derivative to the hydroxymethylmelamine in the hydroxymethylmelamine solution is 1:2.

[0127] 2) Collaborative decentralization ①Preparation of high-efficiency flame retardant system The flame retardant synergist and the flame retardant dithiopyrophosphate are mixed evenly in a weight ratio of 2:1 to obtain a composite flame retardant system; the composite flame retardant system is added into deionized water, the mass fraction of the composite flame retardant is controlled to be 40wt%, and the dispersant (the added amount is 20% of the weight of the composite flame retardant system), the wetting agent (the added amount is 6% of the weight of the composite flame retardant system), and the defoaming agent (the added amount is 5% of the weight of the composite flame retardant system) are continued to be added, and after stirring and mixing evenly, the mixture is added into a sand mill for grinding, the grinding speed is controlled to be 3500r / min, and the grinding temperature is maintained at 20°C during the grinding process; the particle size is continuously tested during the grinding process until the particle size D90=1.271um, and a high-efficiency flame retardant system is obtained.

[0128] Among them, the dispersant is sodium methylene bisnaphthalene sulfonate; the wetting agent is pull open powder BX; and the defoaming agent is polydimethylsiloxane.

[0129] ②Preparation of high-efficiency flame retardant dispersion system A coupling agent was added to the high-efficiency flame retardant system for surface modification, and the amount of the coupling agent added was controlled to be 10% of the weight of the high-efficiency flame retardant system. Then, the mixture was stirred and reacted at a temperature of 60°C for 30 minutes to obtain the final high-efficiency flame retardant dispersion system.

[0130] Wherein, the coupling agent is titanate coupling agent TC-27.

[0131] 2. Preparation of blended spinning solution The regenerated cellulose spinning solution is prepared by using cellulose pulp as raw material. A denaturant is firstly added into the regenerated cellulose spinning solution. Then, a high-efficiency flame retardant dispersion system and sodium zincate are added into the regenerated cellulose spinning solution by pre-spinning injection to obtain a blended spinning solution.

[0132] The components and properties of the regenerated cellulose spinning solution are as follows: cellulose A content is 9.21wt%, sodium hydroxide content is 5.82wt%, falling ball viscosity is 81s, maturity (10% NH4Cl value) is 32mL, and viscose esterification degree is 78.

[0133] The added weight of the denaturant is 2.5% of the weight of cellulose alpha in the regenerated cellulose spinning solution. The denaturant is a compound of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether; the weight ratio of urea, polyethylene glycol (PEG-1500), and polyoxyethylene alkylphenol ether in the denaturant is 1:1:3.

[0134] The added weight of the high-efficiency flame retardant dispersion system is 20% of the weight of the type A cellulose in the regenerated cellulose spinning solution.

[0135] The added weight of sodium zincate is 0.05% relative to the weight of type A cellulose in the regenerated cellulose spinning solution.

[0136] 3. Spinning Spinning is carried out using a blended spinning solution. The nascent filament bundle enters the first molding bath and is drawn once, then enters the second molding bath and is drawn twice, and then enters the third molding bath and is drawn three times to obtain a molded filament bundle.

[0137] The solvent of the first molding bath is water, including: 100 g / L sulfuric acid, 280 g / L sodium sulfate, and 28.0 g / L zinc sulfate; the temperature of the first molding bath is 45° C., and the first drawing rate is -40%.

[0138] The second molding bath is an air bath, and the relative humidity is controlled to be 75%, the temperature of the second molding bath is 70°C, and the second drafting (inter-disk drafting) rate is 60%.

[0139] The solvent of the third molding bath is water, including: 25 g / L sulfuric acid, 1.8 g / L zinc sulfate; the temperature of the third molding bath is 96° C., and the three-pass drawing rate is 10%.

[0140] 4. Post-processing The formed tow is cut, web-formed, washed once, desulfurized, washed twice, acid-washed, washed three times, washed four times, bleached, oiled, opened, and dried to obtain environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber.

[0141] Among them, high-temperature steam is used to agitate the web laying, the web forming steam pressure is 0.25MPa, and the web forming liquid temperature is 99°C.

[0142] The solvent of the desulfurization bath used in desulfurization is water, including: Na2SO37.0g / L; the desulfurization bath temperature is 70℃.

[0143] The bleaching bath used in bleaching is a hydrogen peroxide solution with a hydrogen peroxide concentration of 1.5 g / L; the bleaching temperature is 55° C. and the pH value is 9.0.

[0144] The oiling bath used in oiling adopts a mixed bath solution (oil agent + weak acid); the oil agent concentration in the oiling bath is 10.5g / L, the weak acid concentration is 8.0g / L, the oiling temperature is 55°C, and the pH value is 6.0; the weak acid used is lactic acid; after oiling, the fiber oil content is controlled to be 0.65%, and the fiber pH is 6.7.

[0145] The oil used in this embodiment is produced by Japan Takemoto Oil Co., Ltd., and the oil is a mixture of HONOL MGR-H and HONOL GA; the weight ratio of HONOL MGR-H to HONOL GA is 7:3.

[0146] The drying process uses three-stage steam drying, with the first stage drying temperature at 120°C, the second stage drying temperature at 130°C, and the third stage drying temperature at 105°C. After drying, the moisture regain of the fiber is controlled within the range of 10-13%.

[0147] This embodiment also provides environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fibers prepared by the aforementioned preparation method.

[0148] The environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber prepared in this embodiment has excellent flame-retardant function, good environmental protection and physical and mechanical properties. The phosphorus content of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 0.967wt%, and the sulfur content is 1.025wt%. Compared with LenzingFR fiber and existing similar products, the phosphorus content is reduced by 64.71%, and the sulfur content is reduced by 63.39%. The limiting oxygen index of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 30.9%, which is 4.04% higher than the best level of existing similar products. The dry breaking strength of the environmentally friendly, efficient and wearable flame-retardant regenerated cellulose fiber is 2.21cN / dtex, the dry breaking elongation is 19.2%, the wet breaking strength is 1.13cN / dtex, and the whiteness is 80.9%, which meets the requirements of industry standard superior products; at the same time, the free formaldehyde in the fiber is low (75mg / kg), the irritation to the skin is low (the average score of the highest irritation reaction to the skin is 0), and the safety is high.

[0149] Comparative Example 1 The only difference between this comparative example and Example 2 is that the preparation and use of the flame retardant synergist and the high-efficiency flame retardant dispersion system are omitted, and dithiopyrophosphate is used instead of the high-efficiency flame retardant dispersion system to prepare the blended spinning solution.

[0150] The phosphorus content in the fiber prepared in Comparative Example 1 is 2.92%, and the sulfur content is 3.07%, which are basically the same as those of Lenzing FR fiber and existing similar products; the limiting oxygen index of the fiber is 29.7%, which is basically the same as existing similar products; the dry breaking strength of the fiber is 2.32 cN / dtex, the dry breaking elongation is 20.1%, the wet breaking strength is 1.21 cN / dtex, and the whiteness is 80.2%.

[0151] Comparative Example 2 The only difference between this comparative example and Example 2 is that sodium zincate is not added in the step of preparing the blended spinning solution.

[0152] The phosphorus content of the fiber prepared in Comparative Example 2 is 1.44%, and the sulfur content is 1.53%. Compared with LenzingFR fiber and existing similar products, the phosphorus content and sulfur content are significantly reduced, and the environmental protection is good; the limiting oxygen index of the fiber is 31.4%, and the limiting oxygen index is increased by 5.72% compared with existing similar products; its phosphorus content, sulfur content and flame retardant properties are not significantly changed compared with Example 2. The fiber prepared in Comparative Example 2 has a dry breaking strength of 2.21 cN / dtex, a dry breaking elongation of 19.0%, a wet breaking strength of 1.12 cN / dtex, and a whiteness of 81.6%. The physical and mechanical properties of the fiber are reduced, but it can still meet the requirements of the industry standard superior products; and the free formaldehyde of the fiber is low (55 mg / kg), the irritation to the skin is low (the average score of the highest irritation reaction to the skin is 0), and the safety is high.

[0153] Unless otherwise specified, all percentages used in the present invention are by weight.

[0154] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber, characterized in that: The method comprises the following steps: preparing a high-efficiency flame retardant dispersion system, preparing a blended spinning solution, spinning and forming, and post-processing; The method for preparing a high-efficiency flame retardant dispersion system comprises the following steps: preparing a flame retardant synergist and co-dispersing the synergistic agent; The method for preparing the flame retardant synergist comprises: contacting melamine with a formaldehyde solution to obtain a hydroxymethyl melamine solution; contacting a tetramethyl piperidine derivative with the hydroxymethyl melamine solution to obtain a solid, separating the solid and drying it to obtain the flame retardant synergist; The synergistic dispersion method comprises: mixing the flame retardant synergist with dithiopyrophosphate to obtain a composite flame retardant system; grinding the composite flame retardant system, the auxiliary agent and deionized water uniformly to obtain a high-efficiency flame retardant system; The high-efficiency flame retardant system is treated with a coupling agent to obtain a high-efficiency flame retardant dispersion system; The method for preparing the blended spinning solution is to add a high-efficiency flame retardant dispersion system into the regenerated cellulose spinning solution to obtain the blended spinning solution; The spinning method comprises spinning with a blended spinning solution to obtain a formed filament bundle; The formed filament bundle is post-processed to obtain environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber.

2. The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber according to claim 1, characterized in that: In the preparation of the flame retardant synergist, the formaldehyde solution is a formaldehyde solution with a concentration of 37 wt %, or a mixed solution of paraformaldehyde and a formaldehyde solution with a concentration of 37 wt %; The molar ratio of melamine to total formaldehyde in the formaldehyde solution is 1:2.5-3.

5.

3. The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber according to claim 1, characterized in that: In the preparation of the flame retardant synergist, the tetramethylpiperidine derivative is tetramethylpiperidinamine or tetramethylpiperidinol; The molar ratio of the tetramethylpiperidine derivative to the methylolmelamine in the methylolmelamine solution is 1:1-2.

4. The method for preparing the environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber according to claim 1, characterized in that: In the synergistic dispersion, the weight ratio of the flame retardant synergist to the dithiopyrophosphate is 1-2:1; The mass fraction of the composite flame retardant system in deionized water is 30-40%; During the grinding process, the grinding was controlled to a particle size D90 < 1.350 um.

5. The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber according to claim 1, characterized in that: In the synergistic dispersion, the coupling agent is added in an amount of 6-10% by weight of the high-efficiency flame retardant system; The coupling agent is a silane coupling agent or a titanate coupling agent; The silane coupling agent is at least one of the following: silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH570; the titanate coupling agent is at least one of the following: titanate coupling agent TC-27, titanate coupling agent TC-WT.

6. The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber according to claim 1, characterized in that: In the preparation of the blended spinning solution, the cellulose A content of the regenerated cellulose spinning solution is 8.90-9.21wt%; The added weight of the high-efficiency flame retardant dispersion system is 17.5-20% of the weight of type A cellulose in the regenerated cellulose spinning solution.

7. The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber according to claim 1, characterized in that: Zinc acetate is also added to the blended spinning solution; The added weight of sodium zincate is 0.05-0.1% of the weight of type A cellulose in the regenerated cellulose spinning solution.

8. The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber according to claim 1, characterized in that: In the spinning process, a blended spinning solution is used for spinning to obtain a nascent filament bundle; the nascent filament bundle enters a first forming bath and is drawn once, then enters a second forming bath and is drawn twice, and then enters a third forming bath and is drawn three times to obtain a formed filament bundle.

9. The method for preparing the environmentally friendly and highly efficient flame-retardant regenerated cellulose fiber according to claim 8, characterized in that: The first molding bath includes: sulfuric acid 90-100g / L, sodium sulfate 260-280g / L, zinc sulfate 28.0-40.0g / L, and the solvent is water; the temperature of the first molding bath is 42-45℃, and the drafting rate is -40% to -20%; The second molding bath is an air bath, the relative humidity is controlled at 75-85%, the temperature of the second molding bath is 70-85℃, and the second drafting rate is 60-90%; The third molding bath includes: sulfuric acid 20-25g / L, zinc sulfate <2g / L, and the solvent is water; the temperature of the third molding bath is 96-99°C, and the three-pass drawing rate is 10-15%.

10. An environmentally friendly, highly efficient and edible flame-retardant regenerated cellulose fiber, characterized in that: The method is prepared by the method according to any one of claims 1 to 9.

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