Preparation method of green halogen-free flame-retardant hydrophobic lyocell fiber / fabric

Abstract

The invention discloses a preparation method of green halogen-free flame-retardant hydrophobic lyocell fiber / fabric, and relates to the technical field of multifunctional materials, and the preparation method comprises the following steps: S1, in-situ growth of nano-silica on the surface of lyocell fiber / fabric, S2, hydrophobic modification of nano-silica through dodecyl trimethoxysilane, and S3, preparation of a flame-retardant liquid; and S4, carrying out flame retardant modification through phytic acid-nicotinamide. According to the invention, nicotinamide and phytic acid are used as raw materials, a nitrogen-phosphorus synergistic flame-retardant effect of nicotinamide and phytic acid is realized, and lyocell fibers are hydrophobically modified by modified nano silicon dioxide, so that the fibers / fabrics are endowed with flame-retardant performance and hydrophobic performance at the same time, and the defects of flammability and moisture absorption of the lyocell fibers / fabrics are fundamentally overcome.

Description

Technical Field

[0001] This invention relates to the field of multifunctional materials technology, and in particular to a method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric. Background Technology

[0002] The core driving force behind the current development of flame-retardant fiber / fabric technology stems from the fundamental need for fire safety. To reduce the fire risks posed by textiles in diverse scenarios such as construction, transportation, and industry, countries worldwide have mandated the application of flame-retardant materials through regulations and standards. This policy direction has directly driven the research and industrialization of flame-retardant fiber / fabric technology.

[0003] While traditional flame retardants can achieve basic fire protection, they have significant limitations: First, they release large amounts of toxic and harmful gases during combustion, exacerbating secondary damage from fires; second, some components (such as halogenated flame retardants) are biotoxic, threatening both the environment and human health; third, these flame retardants are prone to leach from the substrate, causing flame retardant performance to decline over time and weakening the fabric's feel and mechanical properties. These technical challenges have collectively driven breakthroughs in the research and development of next-generation environmentally friendly flame-retardant fibers / fabrics.

[0004] Like cotton, viscose, and other cellulose fibers, lyocell fiber ignites rapidly when exposed to fire, posing a serious fire hazard. Its limiting oxygen index (LOI) is only 18-19%, classifying it as a flammable textile material. Insufficient flame retardancy constitutes a core safety concern in its application. On the other hand, although lyocell fiber possesses good hygroscopicity due to its molecular structure rich in hydrophilic groups (hydroxyl groups), this characteristic also leads to significant limitations in certain practical applications: its tendency to absorb moisture and cause dampness reduces fabric dimensional stability; contaminants easily combine with moisture to form stubborn stains that are difficult to remove; and in high humidity environments, moisture absorption significantly reduces wearing comfort—these problems essentially reflect its poor water resistance and insufficient waterproof performance.

[0005] Currently, there have been some sporadic explorations into flame-retardant modification or waterproofing treatment of lyocell fibers / fabrics. However, improving flame retardancy may disrupt the original hydrophilic-hydrophobic balance of the fiber, while improving waterproofing may reduce the fiber's moisture absorption and breathability. Therefore, how to simultaneously and effectively improve flame retardancy and optimize waterproofing and moisture resistance has become a key technical bottleneck restricting the widespread application of lyocell fibers in the field of high-safety, multifunctional textiles, and is also the core issue that this proposal urgently needs to address.

[0006] In recent years, industry researchers have also been attempting to endow lyocell fibers with flame-retardant or hydrophobic properties through various methods. For example, patent CN115142265B discloses a method for preparing flame-retardant lyocell fabric. Another example is patent CN109321990B, which discloses a method for preparing superhydrophobic lyocell fibers. However, these patents suffer from problems such as environmental pollution and complex processes, and none of them fundamentally solve the problem of achieving durable, environmentally friendly, and multifunctional integration of lyocell fibers while maintaining their inherent advantages. Summary of the Invention

[0007] This invention aims to provide a method for preparing green, halogen-free, flame-retardant, and hydrophobic lyocell fibers / fabrics. The method involves post-treatment of the lyocell fibers / fabrics, first by growing nano-silica in situ on the surface of the fibers / fabrics, and then by hydrophobically modifying the nano-silica with dodecyltrimethoxysilane to obtain hydrophobic lyocell fibers / fabrics. Finally, flame-retardant modification is performed using phytic acid-nicotinamide to obtain flame-retardant and hydrophobic lyocell fibers / fabrics. This method achieves the synergistic flame-retardant effect of nitrogen and phosphorus from nicotinamide and phytic acid, as well as the hydrophobic modification of the lyocell fibers with modified nano-silica, thereby simultaneously endowing the fibers / fabrics with both flame-retardant and hydrophobic properties, fundamentally solving the shortcomings of lyocell fibers / fabrics being flammable and hygroscopic.

[0008] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A method for preparing a green, halogen-free, flame-retardant, hydrophobic lyocell fiber / fabric includes the following steps: S1. Take ammonia water and anhydrous ethanol and stir them evenly. Add tetraethyl silicate and stir to react. After the reaction is complete, place the Lyocell fiber / fabric in the solution to immerse it. After immersion, take out the Lyocell fiber / fabric and dry it to obtain sample one. S2. Add dodecyltrimethoxysilane to anhydrous ethanol, then add glacial acetic acid to control pH=3~5. After the reaction is complete, place sample one from step S1 into the solution for immersion. After immersion, take it out and dry it to obtain sample two. S3. Take phytic acid and nicotinamide and stir them to generate a flame retardant. Mix the flame retardant with pure water to make a flame retardant liquid. S4. After immersing the second sample from step S2 in the flame retardant liquid, remove it, dry it, and cure it to obtain green halogen-free flame retardant hydrophobic Lyocell fiber or fabric.

[0009] In step S1, the volume ratio of ammonia to anhydrous ethanol is 0.04:1 to 0.06:1.

[0010] In step S1, the volume ratio of tetraethyl silicate to anhydrous ethanol is 0.04:1 to 0.06:1.

[0011] In step S1, the liquid-to-material ratio for impregnating lyocell fibers / fabric is 1:20~1:30 g / mL.

[0012] In step S1, the immersion temperature is 45℃~55℃.

[0013] In step S1, the soaking time is 1.5h to 2h.

[0014] In step S2, the volume ratio of dodecyltrimethoxysilane to anhydrous ethanol is 0.040:1 to 0.060:1.

[0015] In step S2, the immersion temperature is 45℃~55℃.

[0016] In step S2, the soaking time is 1.5h to 2h.

[0017] In step S2, the drying conditions are 80~100℃ for 10~15 minutes.

[0018] In step S2, the material-to-liquid ratio for sample one immersion is 1:10g / mL to 1:30g / mL.

[0019] In step S3, the mass ratio of phytic acid to nicotinamide is 3:1. In step S3, the reaction conditions for phytic acid and nicotinamide are: temperature 85~95℃, time 2~4h.

[0020] In step S3, the concentration of the flame retardant liquid is 150~200g / L.

[0021] In step S4, the immersion temperature is 45℃~55℃.

[0022] In step S4, the soaking time is 1 hour to 1.5 hours.

[0023] In step S4, the drying conditions are 60-80℃ for 10-15 minutes.

[0024] In step S4, the curing conditions are 110~130℃ for 3~5 minutes.

[0025] In step S4, the material-to-liquid ratio for sample two immersion is 1:10g / mL to 1:30g / mL.

[0026] The beneficial effects of this invention are: 1. This invention employs a post-treatment modification method for stepwise modification. First, the fiber or fabric undergoes hydrophobic modification, followed by flame-retardant modification using nicotinamide and phytic acid, imparting excellent flame-retardant and hydrophobic properties to the product. The initial hydrophobic modification does not affect the flame-retardant properties of the fiber or fabric; separate modification yields better hydrophobic and flame-retardant properties. This prevents the hydrophobic modification process from affecting the flame-retardant properties, maximizing the preservation of the original flame-retardant properties of the phytic acid-nicotinamide combination. While maintaining good flame-retardant properties, it also possesses excellent hydrophobic properties.

[0027] 2. In this invention, the core mechanism of phosphorus-nitrogen synergistic flame retardancy lies in the reaction between phosphorus and nitrogen elements. At lower temperatures, this reaction promotes fiber dehydration and carbonization, while at higher temperatures, an expandable carbon layer forms on the fiber surface. This expandable carbon layer acts as heat insulation and isolates flammable gases, thus achieving a flame-retardant effect. Nitrogen-containing nicotinamide releases non-flammable gases such as NH3 and N2 during decomposition. These gases dilute the concentration of flammable gases, thereby slowing down the combustion rate.

[0028] Phytic acid forms metal-phytate complexes with sodium ions through its metal ion chelating ability. The thermal decomposition temperature of metal-phytate complexes is typically higher than that of phytic acid itself. Sodium ions participate in the flame retardant process by stabilizing anions, providing an alkaline environment, and participating in synergistic reactions. When heated, the metal-phytate complex catalyzes the dehydration and cross-linking reactions of the polymer. Here, the metal ions play a "synergistic catalytic" role, forming a highly efficient "dehydration-char formation catalyst" together with phytic acid.

[0029] Phytic acid amine primarily works by catalytically forming carbon, creating a dense carbon layer to insulate against heat. Phytic acid-nicotinamide not only forms an expandable carbon layer that provides insulation and prevents the release of flammable gases during decomposition, but also releases non-flammable gases, such as NH3, to dilute the concentration of flammable gases, thus achieving multiple flame-retardant effects.

[0030] 3. This invention employs an in-situ deposition of silica onto the fabric, followed by long-chain silane modification of the silica, without the use of adhesives or curing agents. Aside from this, both methods achieve a superhydrophobic effect, but the methods and reagents used differ.

[0031] Adhesive-assisted bonding involves mixing a pre-synthesized nanoparticle dispersion with a polymeric adhesive, applying it to the fabric through methods such as padding or coating, and then fixing the particles to the surface after curing. The nanoparticles may be unevenly distributed, significantly impacting the fabric's feel and breathability. While initially effective, its function rapidly declines as particles detach and the adhesive layer deteriorates. The adhesive may also degrade under certain solvents, high temperatures, or ultraviolet light, leading to overall failure.

[0032] In-situ generation involves immersing fabric in a solution containing nanoparticle precursors, where nanoparticles are directly generated on the fiber surface through a chemical reaction. In-situ generation results in extremely strong bonding and durability. The nanoparticles grow on the fiber surface through chemical bonds or strong physical interactions, becoming an integral part of the fiber. It offers excellent wash and abrasion resistance. The nanoparticles are evenly, densely, and firmly distributed. It has minimal impact on the fabric's feel and breathability. It is long-lasting and chemically stable.

[0033] 4. In this invention, a scheme to improve the flame retardancy and hydrophobicity of lyocell fibers was designed to address the flammability and hydrophilicity disadvantages of lyocell fibers. This process uses phytic acid-nicotinamide as a flame retardant to enhance the flame retardant properties of lyocell fibers. Silica sol is both a flame retardant additive that works synergistically with phytic acid-nicotinamide and a key component for hydrophobic modification. By preparing the composite finishing solution in a one-step process, the fabric can achieve both hydrophobic and flame retardant functions after a single pad-drying process. The modified lyocell fibers have a water contact angle exceeding 130° and simultaneously achieve self-extinguishing upon removal of the flame.

[0034] 5. The flame-retardant mechanism of this invention is a nitrogen-phosphorus-silicon synergy. It employs phytic acid-nicotinamide as the primary flame retardant and utilizes silica sol as a flame-retardant auxiliary agent and a hydrophobic layer. During combustion, phytic acid-nicotinamide promotes early dehydration of cellulose into char, while silica sol interacts with phosphorus-based products to form a Si-OP structure with extremely high thermal stability, thereby constructing a dense and robust barrier char layer. This mechanism is based on condensed-phase flame retardancy and gas-phase flame retardancy, and isolates external flammable gases and heat by enhancing the integrity of the char layer. Attached Figure Description

[0035] Figure 1 SEM and EDS images of the Lyocell fabric obtained in Example 2 of the present invention.

[0036] Figure 2 These are SEM and EDS images of the unmodified Lyocell fabric of the present invention.

[0037] Figure 3 The images show the green halogen-free flame-retardant hydrophobic lyocell fibers and unmodified lyocell fibers prepared in Examples 1, 1, and 2 of this invention.

[0038] Figure 4 These are combustion comparison images of the green halogen-free flame-retardant hydrophobic lyocell fibers and unmodified lyocell fibers prepared in Examples 1, 1, and 2 of the present invention.

[0039] Figure 5 The contact angle diagrams are for the Lyocell fabrics obtained in Embodiment 2 and Comparative Example 3 of the present invention.

[0040] Figure 6These are comparative images of the burning of the unmodified fabric of the present invention, the Lyocell fabric prepared in Example 2, and Comparative Example 4.

[0041] Figure 7 Raman spectra of the unmodified fabric of the present invention and the carbon slag of Example 2. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0043] Example 1 This embodiment provides a method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber, including the following steps: S1. At 50℃, weigh 50mL of anhydrous ethanol and 3mL of ammonia water and add them to a beaker and stir for 30min. Then add 3mL of tetraethyl silicate and stir for 2h to form a uniform solution. At 50℃, immerse 2g of Lyocell fiber in the solution for 1.5h. Then take out the immersed Lyocell fiber and dry it to obtain sample one. S2. At room temperature, weigh 5 mL of dodecyltrimethoxysilane and add it to 95 mL of anhydrous ethanol. Then add glacial acetic acid to control the pH to 4 and stir for 2 h. At 50 °C, place sample one in 40 mL of solution and immerse for 1.5 h. Take out the lyocell fiber after immersion and dry it at 100 °C for 10 min to obtain sample two. S3. At 90℃, add 42.75g of 70% phytic acid aqueous solution to 10g of nicotinamide and stir at 90℃ for 3h to form a flame retardant (the mass ratio of phytic acid to nicotinamide is 3:1). Mix the flame retardant with pure water to make a flame retardant liquid with a concentration of 160g / L. S4. Immerse sample 2 from step S2 in 40 mL of flame retardant liquid at 50 °C for 1.5 h. Remove the impregnated Lyocell fiber and dry it at 60 °C for 15 min, then cure it at 120 °C for 3 min to obtain green halogen-free flame retardant hydrophobic Lyocell fiber.

[0044] Example 2 This embodiment provides a method for preparing a green, halogen-free, flame-retardant, hydrophobic Lyocell fabric, comprising the following steps: S1. At 45℃, weigh 50mL of anhydrous ethanol and 2mL of ammonia water and add them to a beaker and stir for 30min. Then add 2mL of tetraethyl silicate and stir for 2h to form a uniform solution. At 45℃, immerse 2g of Lyocell fabric in the solution for 2h. Then take out the immersed Lyocell fabric and dry it to obtain sample one. S2. At room temperature, weigh 4 mL of dodecyltrimethoxysilane and add it to 96 mL of anhydrous ethanol. Then add glacial acetic acid to control the pH to 3 and stir for 2 h. At 45 °C, place sample one in 20 mL of solution and immerse for 2 h. Take out the lyocell fabric after immersion and dry it at 80 °C for 15 min to obtain sample two. S3. At 95℃, add 36g of 70% phytic acid aqueous solution to 10g of nicotinamide and stir at 95℃ for 2h to form a flame retardant (the mass ratio of phytic acid to nicotinamide is 2.5:1). Mix the flame retardant with pure water to make a flame retardant liquid with a concentration of 200g / L. S4. Immerse sample 2 from step S2 in 20mL of flame retardant liquid at 45℃ for 1h. Take out the lyocell fiber after immersion and dry it at 80℃ for 10min and cure it at 130℃ for 4min to obtain green halogen-free flame retardant hydrophobic lyocell fabric.

[0045] Example 3 This embodiment provides a method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber, including the following steps: S1. At 55℃, weigh 40mL of anhydrous ethanol and 2mL of ammonia water and add them to a beaker and stir for 20min. Then add 2mL of tetraethyl silicate and stir for 2h to form a uniform solution. At 55℃, immerse 2g of Lyocell fiber in the solution for 100min. Then take out the immersed Lyocell fiber and dry it to obtain sample one. S2. At room temperature, weigh 5.5 mL of dodecyltrimethoxysilane and add it to 94.5 mL of anhydrous ethanol. Then add glacial acetic acid to control the pH to 5 and stir for 1.5 h. At 55 °C, place sample one in 60 mL of solution and immerse it for 100 min. Take out the lyocell fiber after immersion and dry it at 90 °C for 12 min to obtain sample two. S3. At 85℃, add 50g of 70% phytic acid aqueous solution to 10g of nicotinamide and stir at 85℃ for 4h to form a flame retardant (the mass ratio of phytic acid to nicotinamide is 3.5:1). Mix the flame retardant with pure water to make a flame retardant liquid with a concentration of 150g / L. S4. Immerse sample 2 from step S2 in 60 mL of flame retardant liquid at 55 °C for 100 min. Remove the lyocell fiber after immersion and dry it at 70 °C for 13 min. Then cure it at 110 °C for 5 min to obtain green halogen-free flame retardant hydrophobic lyocell fiber.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that the nano-silica particles were not loaded in step S1. All other conditions were the same as in Example 1.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that the flame-retardant modification in step S4 was not performed. All other conditions are the same as in Example 1.

[0048] Comparative Example 3 The difference between this comparative example and Example 2 is that the nano-silica particles were not loaded in step S1, while the other conditions were the same as in Example 1.

[0049] Comparative Example 4 The difference between this comparative example and Example 2 is that the flame-retardant modification in step S4 was not performed. All other conditions are the same as in Example 1.

[0050] Comparative Example 5 The difference between this comparative example and Example 1 is that the tetraethyl silicate in step S1 is replaced with nano-Al2O3, while the other conditions are the same as in Example 1.

[0051] Comparative Example 6 The difference between this comparative example and Example 1 is that the dodecyltrimethoxysilane in step S2 is replaced with KH560, while the other conditions are the same as in Example 1.

[0052] Comparative Example 7 The difference between this comparative example and Example 1 is that the flame retardant in step S3 is replaced with tea polyphenols, while the other conditions are the same as in Example 1.

[0053] Experimental Example In this experimental example, the Lyocell fibers / fabrics prepared in Examples 1-2 and Comparative Examples 1-4 were subjected to the following performance tests, and the test results are shown in Table 1.

[0054] The test items include: Raman spectroscopy was performed using an in-situ Raman spectrometer (HORIBA / LabRAM Odyssey) equipped with a 532 nm argon ion laser, in the range of 500-2500 cm⁻¹. -1 The spectral range was used to assess the degree of graphitization of the samples.

[0055] The limiting oxygen index test was conducted according to ASTM D2863-2000 standard, with a specimen size of 150 mm × 60 mm.

[0056] The surface microstructure and elemental composition of the samples and carbon slag were recorded using a Japanese high-vacuum scanning electron microscope (JSM-IT500A). SEM was performed at an accelerating voltage of 10 kV. Before SEM-EDS testing, the sample surface was treated with gold deposition in a vacuum for 1 min.

[0057] The water contact angle (WCA) of the samples was measured at 25℃ using an SDC-80 static contact angle analyzer.

[0058] Table 1. Performance parameters of Lyocell fibers / fabrics obtained in Examples 1-3 and Comparative Examples 1-7

[0059] Compared with Example 1: Comparative Example 1 has no hydrophobic function because it does not load silica nanoparticles and does not perform hydrophobic modification on the silica nanoparticles.

[0060] Compared with Example 1, Comparative Example 2 has poorer flame retardant performance because it was not modified to be flame retardant.

[0061] Compared with Example 1, Comparative Example 3 is a Lyocell fabric and does not have hydrophobic properties because it does not load silica nanoparticles and does not perform hydrophobic modification on the silica nanoparticles.

[0062] Compared with Example 1, Comparative Example 4 is made of Lyocell fabric and has poor flame retardant properties because it was not modified for flame retardancy.

[0063] Compared with Example 1, Comparative Example 5 has no hydrophobic function because it does not load silica nanoparticles and does not perform hydrophobic modification on the silica nanoparticles.

[0064] Compared with Example 1, Comparative Example 6 has no hydrophobic function because although it is loaded with silica nanoparticles, it does not perform hydrophobic modification on the silica nanoparticles.

[0065] Compared with Example 1, Comparative Example 7 has poorer flame retardant performance because the flame retardant effect of tea polyphenols in Comparative Example 7 is much lower than that of phytic acid-nicotinamide.

[0066] like Figure 1 The images shown are SEM and EDS images of the lyocell fabric prepared in Example 2 of the present invention. (b) is an SEM image of the lyocell fabric prepared in Example 2. C is the C element distribution spectrum of the lyocell fabric prepared in Example 2; O is the O element distribution spectrum of the lyocell fabric prepared in Example 2; N is the N element distribution spectrum of the lyocell fabric prepared in Example 2; P is the P element distribution spectrum of the lyocell fabric prepared in Example 2; Si is the Si element distribution spectrum of the lyocell fabric prepared in Example 2. like Figure 2The images shown are SEM and EDS images of unmodified Lyocell fabric. (a) is the SEM image of the unmodified Lyocell fabric. C represents the C element distribution spectrum of the unmodified Lyocell fabric; O represents the O element distribution spectrum of the unmodified Lyocell fabric.

[0067] from Figure 1 and Figure 2 As can be seen, the surface of the unmodified lyocell fabric is smooth and flat, without any additional adhering particles; the surface of the modified lyocell fabric of this invention exhibits a rough texture and fine particles due to the in-situ growth of nano-silica. In terms of elemental composition, the unmodified lyocell fabric only contains C and O elements, which are the intrinsic components of lyocell fiber; the modified lyocell fabric of this invention, in addition to a denser distribution of C and O elements, also contains additional N, P, and Si elements, corresponding to the phytic acid-nicotinamide (N, P) and nano-silica and silane coupling agent (Si) introduced during the modification. The surface roughening of the modified lyocell fabric of this invention, combined with the synergistic effect of Si elements, enhances hydrophobicity, effectively resisting water stains; N and P elements impart excellent flame retardancy, delaying the combustion process; the adhering nanoparticles enhance surface friction performance, ensuring stability in use and significantly optimizing the fabric's functionality.

[0068] like Figure 3 The images shown are actual photos of the green halogen-free flame-retardant hydrophobic lyocell fibers and unmodified lyocell fibers prepared in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention.

[0069] Unmodified lyocell fibers completely absorbed the water droplets. Comparative Example 1, which did not load silica nanoparticles and did not undergo hydrophobic modification of the silica nanoparticles, also completely absorbed the water droplets. Examples 1 and 2, loaded with hydrophobically modified silica nanoparticles, exhibited good hydrophobic properties.

[0070] like Figure 4 The images shown are comparative combustion images of the green halogen-free flame-retardant hydrophobic lyocell fibers and unmodified lyocell fibers prepared in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention.

[0071] Unmodified lyocell fibers were completely burned with minimal residue. Comparative Example 2 was also completely burned, but with more residue because the silica nanoparticles formed an insulating layer on the fiber surface during combustion. Both Example 1 and Comparative Example 1 were self-extinguishing after the flame source was removed.

[0072] like Figure 5 The diagram shows the contact angle of the Lyocell fabrics obtained in Example 2 and Comparative Example 4 of the present invention.

[0073] Example 2 loaded silica nanoparticles and modified them to be hydrophobic, resulting in good hydrophobic properties with a water contact angle of 130.67°. Comparative Example 3 did not load silica nanoparticles or modify them to be hydrophobic, thus exhibiting no hydrophobic properties and a water contact angle of 0°.

[0074] like Figure 6 The images shown are comparative images of the burning of Lyocell fabrics prepared in Example 2 and Comparative Example 4 of the present invention.

[0075] Unmodified lyocell fabric was completely burned with minimal residue. Comparative Example 4 was also completely burned, but with more residue because the silica nanoparticles formed a heat-insulating layer on the fiber surface during combustion. Example 2 achieved self-extinguishing after flame-retardant modification.

[0076] like Figure 7 The image shown is a Raman image of Example 2 of the present invention and the unmodified fiber residue. 1350cm 1 and 1580cm 1 The two nearby absorption peaks belong to the D band of disordered carbon and the G band of graphitic carbon, respectively. The ratio of the combined intensity of the D and G bands (ID / IG) indicates the degree of graphitization of the material. Generally, a lower ID / IG value indicates higher quality carbon. Lyocell's ID / IG value is 3.15, lower than 1.03 in Example 2, indicating that the graphitic carbon formed in Example 2 is of higher quality. Therefore, the modified fabric exhibits excellent flame retardant properties.

[0077] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric, characterized in that: Includes the following steps: S1. Take ammonia water and anhydrous ethanol and stir them evenly. Add tetraethyl silicate and stir to react. After the reaction is complete, place the Lyocell fiber / fabric in the solution to immerse it. After immersion, take out the Lyocell fiber / fabric and dry it to obtain sample one. S2. Add dodecyltrimethoxysilane to anhydrous ethanol, then add glacial acetic acid to control pH=3~5. After the reaction is complete, place sample one from step S1 into the solution for immersion. After immersion, take it out and dry it to obtain sample two. S3. Take phytic acid and nicotinamide and stir them to generate a flame retardant. Mix the flame retardant with pure water to make a flame retardant liquid. S4. After immersing the second sample from step S2 in the flame retardant liquid, remove it, dry it, and cure it to obtain green halogen-free flame retardant hydrophobic Lyocell fiber or fabric.

2. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S1, the volume ratio of ammonia to anhydrous ethanol is 0.04:1 to 0.06:

1.

3. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S1, the volume ratio of tetraethyl silicate to anhydrous ethanol is 0.04:1 to 0.06:

1.

4. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S1, the liquid-to-material ratio for impregnating the lyocell fiber / fabric is 1:20g / mL to 1:30g / mL.

5. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S1, the immersion temperature is 45℃~55℃.

6. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 5, characterized in that: In step S1, the soaking time is 1.5h to 2h.

7. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S2, the volume ratio of dodecyltrimethoxysilane to anhydrous ethanol is 0.040:1 to 0.060:

1.

8. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S2, the immersion temperature is 45℃~55℃.

9. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 8, characterized in that: In step S2, the soaking time is 1.5h to 2h.

10. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 9, characterized in that: In step S2, the material-to-liquid ratio for sample one immersion is 1:10g / mL to 1:30g / mL.

11. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S2, the drying conditions are 80℃~100℃ for 10min~15min.

12. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S3, the mass ratio of phytic acid to nicotinamide is 2.5:1 to 3.5:

1.

13. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 12, characterized in that: In step S3, the reaction conditions for phytic acid and nicotinamide are: temperature 85℃~95℃, time 2h~4h.

14. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S3, the concentration of the flame retardant liquid is 150g / L to 200g / L.

15. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S4, the immersion temperature is 45℃~55℃.

16. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 15, characterized in that: In step S4, the soaking time is 1 hour to 1.5 hours.

17. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 16, characterized in that: In step S4, the material-to-liquid ratio for sample two immersion is 1:10g / mL to 1:30g / mL.

18. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S4, the drying conditions are 60℃~80℃ for 10min~15min.

19. The method for preparing green halogen-free flame-retardant hydrophobic lyocell fiber / fabric according to claim 1, characterized in that: In step S4, the curing conditions are 110℃~130℃ for 3min~5min.

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