A lignin-based flame-retardant hydrophobic fiber material and its preparation method and application

Abstract

The present invention provides a lignin-based flame-retardant hydrophobic fiber material and its preparation method and application, belonging to the technical field of flame-retardant hydrophobic materials. The fiber material is obtained by using condensation-inhibited low-molecular-weight lignin as raw material, dissolving it in an ethanol / water system for pretreatment, centrifuging to remove precipitates, taking the supernatant, evaporating and drying to obtain a lignin pretreatment product; using γ-aminopropyltrimethoxysilane KH560 to modify polyethyleneimine PEI to obtain a modified polyethyleneimine solution; the lignin pretreatment product and the modified polyethyleneimine solution are blended, added to an iron phosphate and / or aluminum phosphate solution after blending, and then fiber paper or fiber fabric is placed in the solution for impregnation treatment, and dried at a constant temperature to obtain a flame-retardant and water-resistant fiber material. The present invention imparts flame-retardant and water-resistant properties to the fiber material through a method of structural regulation and modification of condensation-inhibited lignin rich in active groups. The process is simple, the parameters are easy to control, and the product has significant flame retardant and hydrophobic effects.

Description

Technical Field

[0001] The present invention relates to the technical field of flame-retardant and hydrophobic materials, in particular to a lignin-based fiber material with both flame-retardant and hydrophobic modification, and a preparation method and application thereof. Background Art

[0002] Generally, high-performance fiber materials are more competitive in the market, meeting consumer demands for quality, safety, and durability. Fiber materials with both hydrophobic and flame-retardant properties are more durable and can be used in outdoor construction, ships, and outdoor equipment. Their enhanced ability to adapt to harsh climates allows them to be applied in more demanding fields, such as aerospace, military, and electronic equipment. However, the compatibility of flame retardancy and hydrophobicity is a key issue. Conventional fiber materials are often hydrophobic but not flame-retardant, or vice versa.

[0003] Phosphorus-nitrogen flame retardants and fluorosilicone hydrophobic agents are used in synergistic modification. Flame retardancy is achieved by forming a char layer with the help of the phosphorus-nitrogen flame retardant, while the fluorosilicone hydrophobic agent provides excellent hydrophobicity. The chemical stability and non-interference properties of the two make them have good application prospects in fiber materials. It is challenging to achieve simultaneous effects on the same material without interfering with each other. Silicon-based flame retardants have relatively good heat resistance and hydrophobicity, and are highly compatible with organosilicon hydrophobic agents, making them suitable for use in a variety of high-performance fiber materials. However, the use of silicon-based agents poses potential hazards to human health. Therefore, environmentally friendly flame retardant and water-resistant methods are a meaningful and challenging topic.

[0004] Lignin is a naturally renewable phenolic compound. Research has found that metal ions coordinate with hydroxyl groups or phenolic hydroxyl groups in lignin to form stable compounds that enhance its stability, heat resistance, water resistance, and antioxidant properties. Lignin has a wide range of applications in environmentally friendly materials, biomedicine, cosmetics, and other fields, achieving long-lasting hydrophobicity. Furthermore, the introduction of flame retardant groups can achieve both hydrophobic and flame retardant properties. The preparation of lignin nanoparticles has developed rapidly in recent years. Using nanoparticles as carriers and simultaneously loading them with flame retardants and hydrophobic agents is a promising development strategy. However, commonly used alkali lignin and lignin sulfonates have low active hydroxyl content. While formic acid lignin, particularly formic acid lignin prepared using a condensation inhibition strategy (Chinese Patent Publication No. CN111958730A), is rich in active groups, its reaction with metal ions is too intense and difficult to control. Summary of the Invention

[0005] The technical task of the present invention is to solve the deficiencies of the prior art and provide a lignin-based flame retardant hydrophobic fiber material and a preparation method and application thereof.

[0006] The technical solution of the present invention is achieved in the following manner: a lignin-based flame-retardant hydrophobic fiber material is obtained by using a condensation-inhibited low-molecular-weight lignin as a raw material, dissolving it in an ethanol / water system for pretreatment, centrifuging to remove the precipitate, and collecting the supernatant, evaporating and drying it to obtain a lignin pretreatment product;

[0007] Polyethyleneimine (PEI) was modified with γ-aminopropyltrimethoxysilane (KH560) to obtain a modified polyethyleneimine solution.

[0008] The lignin pretreatment product and the modified polyethyleneimine solution are blended and added into an iron phosphate and / or aluminum phosphate solution, and then fiber paper or fiber fabric is immersed in the solution and dried at a constant temperature to obtain a flame retardant and water-resistant fiber material.

[0009] The acquisition of the fiber material specifically comprises the following steps:

[0010] (1) Lignin treatment: Use ethanol / water system to treat low molecular weight lignin that inhibits condensation;

[0011] (2) Preparation of modified polyethyleneimine solution: γ-aminopropyltrimethoxysilane KH560 and polyethyleneimine PEI were reacted to prepare a uniform solution;

[0012] (3) Impregnation: The pretreated lignin obtained in step (1) and the modified polyethyleneimine solution obtained in step (2) are mixed and added into an iron phosphate and / or aluminum phosphate solution, and then the fiber paper or fiber fabric is immersed in the solution and dried at a constant temperature to obtain a flame retardant and water-resistant fiber material.

[0013] In step (1):

[0014] The condensation-inhibiting low molecular weight lignin uses acetic acid lignin or formic acid lignin;

[0015] The volume fraction of ethanol in the ethanol / water system is 20%~100% v / v;

[0016] The pretreatment of the condensation-inhibiting lignin is to dissolve the condensation-inhibiting lignin in an ethanol / water solution at a concentration of 5% w / w, centrifuge at 3000 rpm for 10 minutes, remove the precipitate, take the supernatant, and evaporate to dryness.

[0017] In step (2):

[0018] The preparation conditions of the modified polyethyleneimine PEI solution are as follows: reaction temperature of 35-40°C, reaction time of 2-10 hours, molecular weight of polyethyleneimine PEI selected as 800 and 1800, and reaction mass ratio of KH560 to PEI of 1:1-1:3.

[0019] In step (3):

[0020] The concentration of [iron phosphate and / or aluminum phosphate solution] is 0.6% to 1.2% by mass;

[0021] The mass ratio of the pretreated condensation-inhibited lignin to the modified polyethyleneimine PEI solution is 1:0.5-1:2, the mass ratio of the [iron phosphate and / or aluminum phosphate solution] to the [lignin] is 0.5:1-1:2, the blending time is 4-7 hours, and the blending temperature is 30-70°C;

[0022] Immersion treatment time: 24 h; conditions: temperature 40°C, immersion stirring speed 200 rpm;

[0023] The mass concentration of lignin in the ethanol / water dispersion system is 2%~6%;

[0024] The surface diameter of the fiber paper or fiber fabric is 8~10cm.

[0025] A method for preparing a lignin-based flame-retardant hydrophobic fiber material comprises: using a condensation-inhibiting low-molecular-weight lignin as a raw material, dissolving it in an ethanol / water system for pretreatment, removing the precipitate by centrifugation, collecting the supernatant, and evaporating and drying it to obtain a lignin pretreatment product; wherein the use of the non-toxic and non-polluting ethanol / water system can screen and obtain a highly active condensation-inhibiting lignin with a uniform structure;

[0026] Polyethyleneimine (PEI) is modified with γ-aminopropyltrimethoxysilane (KH560) to obtain a modified polyethyleneimine solution. The modified polyethyleneimine solution system allows the introduction of amino-rich groups into condensation-inhibiting lignin. Furthermore, γ-aminopropyltrimethoxysilane (KH560) facilitates grafting onto the condensation-inhibiting lignin. The resulting modified polyethyleneimine solution can form a hydrophobic network through self-crosslinking and co-crosslinking, thereby maximizing the flame retardancy and hydrophobicity of the lignin.

[0027] The lignin pretreatment product and the modified polyethyleneimine solution are blended and then added to an iron phosphate and / or aluminum phosphate solution. The phosphate simultaneously modifies the lignin, introducing nitrogen, phosphorus and metal elements. With the help of the active functional groups on the surface of the lignin, it is made to have both flame retardant and water resistant properties. Fiber paper or fiber fabric is then placed in the mixture for immersion treatment and dried at a constant temperature to obtain a flame retardant and water resistant fiber material.

[0028] The application of the lignin-based flame-retardant hydrophobic fiber material in flame-retardant hydrophobic decoration materials can be dispersed or coated in indoor and outdoor decoration materials.

[0029] The application of the lignin-based flame-retardant hydrophobic fiber material in flame-retardant hydrophobic protective products can be applied to the matrix material of medical protective products and the matrix of outdoor clothing fabrics.

[0030] The preparation method of the lignin-based flame-retardant hydrophobic fiber material is applied to flame-retardant hydrophobic fiber materials, such as pulp, coating, and polymer material composition.

[0031] The beneficial effects of the present invention compared with the prior art are:

[0032] The present invention discloses a lignin-based flame-retardant and hydrophobic fiber material, a preparation method thereof, and an application thereof. The fiber material is endowed with flame-retardant and water-resistant properties by a method of structural regulation and modification of an inhibited condensation lignin rich in active groups. The process flow of the present invention is simple, the parameters are easy to control, and the prepared fiber material has excellent flame-retardant and hydrophobic properties.

[0033] In the present invention, the condensation-inhibited lignin contains more active sites and a controllably more uniform structure. Through metal chelation coordination, it can load a larger number of flame-retardant and hydrophobic functional groups. By impregnating fiber paper or fabric in a mixed solution of lignin, modified PEI, and iron phosphate / aluminum phosphate, a flame-retardant and hydrophobic fiber material can be prepared through simple mixing and deposition. This simple preparation process does not require the use of silane-based reagents and does not use fluorine-containing or environmentally polluting substances, thus demonstrating excellent practicality.

[0034] The method of the present invention modifies condensation-inhibited lignin into a flame-retardant and hydrophobic material. First, a uniformly structured lignin is obtained by treatment with an ethanol / water system. Then, a flame-retardant and hydrophobic lignin-based flame-retardant and water-repellent agent is deposited on the surface of fiber paper or fabric through a modified polyethyleneimine grafting and metal chelation method. The lignin-based flame-retardant and hydrophobic fiber material prepared using the method of the present invention exhibits significant flame-retardant and hydrophobic properties and excellent practical performance, providing technical support for the simple and environmentally friendly preparation of lignin-based flame-retardant and hydrophobic fiber materials.

[0035] In the method of the present invention:

[0036] The ethanol / water system is non-toxic and non-polluting, poses no harm or threat to human health, and can screen out highly active condensation-inhibiting lignin with uniform structure.

[0037] The modified polyethyleneimine solution system is configured to introduce amino-rich groups into lignin. At the same time, KH560 is more conducive to grafting on lignin. The resulting modified PEI can form a hydrophobic network through self-crosslinking and co-crosslinking, thereby maximizing the flame retardant and hydrophobic properties of lignin.

[0038] The pretreated lignin is blended with modified PEI, and phosphate is added to modify the lignin, introducing nitrogen, phosphorus, and metals. Lignin's surface active functional groups are then utilized to impart flame retardancy and water resistance. The self-made lignin-based flame retardant and hydrophobic agent contains more active functional groups than conventional lignin, carrying more flame retardant and hydrophobic groups, and allowing their uniform size to be controlled, resulting in a flame-retardant, hydrophobically modified fiber material.

[0039] The lignin-based flame-retardant hydrophobic fiber material of the present invention, and its preparation method and application have reasonable design, simple process, safety and reliability, convenient application, easy expansion of production, and good promotion and use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Attachment Figure 1 The comparative example of the present invention is about the condensation-inhibited lignin and Fe that have not been treated with the ethanol / water system. 3+ (a1, a2, a3), Fe 2+ (b1, b2, b3) and Al 3+ (c1, c2, c3) SEM images after chelation.

[0041] Attachment Figure 2 These are SEM images of FLP-100 (a1 and a2), FLP-60 (b1 and b2), FLP-50 (c1 and c2), FLP-40 (d1 and d2), and FLP-20 (e1 and e2) of the present invention.

[0042] Attachment Figure 3 SEM images of FLP@cotton fabric (a1-e1), FLP-100 / Fe@cotton fabric (a2-a3), FLP-60 / Fe@cotton fabric (b2-b3), FLP-50 / Fe@cotton fabric (c2-c3), FLP-40 / Fe@cotton fabric (d2-d3) and FLP-20 / Fe@cotton fabric (e2-e3) of the present invention. DETAILED DESCRIPTION

[0043] The following is a detailed description of a lignin-based flame-retardant hydrophobic fiber material, a preparation method thereof, and applications of the present invention in conjunction with embodiments.

[0044] Example 1:

[0045] (1) Lignin treatment: Weigh 1 g of poplar formic acid lignin (condensation-inhibited lignin) and dissolve it in 20 mL of anhydrous ethanol / water mixture, with the volume fractions of ethanol being 20 mL, 12 mL, 10 mL, 8 mL, and 4 mL, respectively. The specific treatment method is to dissolve the lignin in an ethanol / water solution at a concentration of 5%, preferably 50% ethanol, centrifuge at 3000 rpm for 10 min, remove the precipitate, and take the supernatant, which is evaporated to dryness to obtain the product;

[0046] (2) The reaction temperature of PEI and KH560 is 35-40°C, preferably 40°C, the reaction time is 2-10h, preferably 4h, the molecular weight of PEI is 800 and 1800, preferably 1800, and the reaction mass ratio of KH560 to PEI is 1:1-1:3, preferably 1:2. The self-crosslinking and co-crosslinking effects of KH560-PEI obtained under this process are both good;

[0047] (3) Impregnation: The ratios of lignin to modified PEI were 1:0.5, 1:1, 1:1.5, and 1:2, respectively; the ratio of aluminum phosphate or iron phosphate to lignin was 0.5:1; the lignin dispersion system was 50% ethanol / 50% water; the dispersion concentration was 5%; the surface diameter of the fiber material (paper or fabric) was 8–10 cm; the impregnation time was 6 h; the blending temperature was 50 °C; and the stirring rate was 200 rpm.

[0048] (4) The surface water contact angle of flame retardant hydrophobic fiber paper and fabric was tested using an optical contact angle meter. The syringe was controlled to drop 5 μL of water on the surface of the test sample, and the corresponding contact angle was measured respectively. The average value of three tests was taken as the test result. According to the standard GB / T 2406.2-2009, the limiting oxygen index of fiber paper and fabric samples was measured using a limiting oxygen index tester. The results are shown in Table 1.

[0049] Table 1 Effect of the ratio of lignin to modified PEI on water contact angle CA (°) and limiting oxygen index LOI

[0050] .

[0051] As shown in Table 1, the ethanol / water treatment conditions for the fixed poplar formic acid lignin, the reaction preparation conditions for PEI and KH560, the fixed ratio of aluminum phosphate or iron phosphate to lignin of 1:1, the impregnation treatment conditions of lignin impregnation concentration of 5%, time of 6 h and temperature of 50°C, after the paper or fabric was modified, when the ratio of lignin to modified PEI was 1:1, the contact angle reached the maximum value of 121.4° and 123.6°, respectively, at this time, the corresponding limiting oxygen index also reached the highest value.

[0052] Example 2:

[0053] (1) Lignin treatment: Weigh 1 g of poplar formic acid lignin (condensation-inhibited lignin) and dissolve it in 20 mL of anhydrous ethanol / water mixture, with the volume fractions of ethanol being 20 mL, 12 mL, 10 mL, 8 mL, and 4 mL, respectively. The specific treatment method is to dissolve the lignin in an ethanol / water solution at a concentration of 5%, preferably 50% ethanol, centrifuge at 3000 rpm for 10 min, remove the precipitate, and take the supernatant, which is evaporated to dryness to obtain the product;

[0054] (2) The reaction temperature of PEI and KH560 is 35-40°C, preferably 40°C, the reaction time is 2-10h, preferably 4h, the molecular weight of PEI is 800 and 1800, preferably 1800, and the reaction mass ratio of KH560 to PEI is 1:1-1:3, preferably 1:2. The self-crosslinking and co-crosslinking effects of KH560-PEI obtained under this process are both good;

[0055] (3) Impregnation: The ratio of lignin to modified PEI was 1:1, and the ratios of aluminum phosphate or iron phosphate to lignin were 1:0.5, 1:1, 1:1.5, and 1:2, respectively. The lignin dispersion system used was 50% ethanol / 50% water, the dispersion concentration was 5%, the surface diameter of the fiber material (paper or fabric) was 8-10 cm, the time was 6 h, the blending temperature was 50 °C, and the stirring rate was 200 rpm.

[0056] (4) The surface water contact angle of flame retardant hydrophobic fiber paper and fabric was tested using an optical contact angle meter. The syringe was controlled to drop 5 μL of water on the surface of the test sample, and the corresponding contact angle was measured respectively. The average value of three tests was taken as the test result. According to the standard GB / T 2406.2-2009, the limiting oxygen index of fiber paper and fabric samples was measured using a limiting oxygen index tester. The results are shown in Table 2.

[0057] Table 2 Effect of the ratio of aluminum phosphate or iron phosphate to lignin on water contact angle CA (°) and limiting oxygen index LOI

[0058] .

[0059] As shown in Table 2, the ethanol / water treatment conditions of the fixed poplar formic acid lignin, the reaction preparation conditions of the fixed PEI and KH560, the fixed ratio of lignin to modified PEI of 1:1, the impregnation treatment conditions of the lignin impregnation concentration of 5%, the time of 6 h and the temperature of 50 °C, after the paper or fabric was modified, when the ratio of aluminum phosphate or iron phosphate to lignin was 1:1, the contact angle reached the maximum value of 120.4° and 125.6°, respectively. After exceeding the ratio, the corresponding limiting oxygen index increased, but the contact angle decreased.

[0060] in:

[0061] In Example 1, the chelate form of condensed lignin with iron and aluminum ions is suppressed.

[0062] (1) Lignin was treated with an ethanol / water system. The ethanol volume concentration of the ethanol / water system was 40-60% with different volume fractions. The specific treatment method was to dissolve the lignin in an ethanol / water solution at a concentration of 5%, centrifuge at 3000 rpm for 10 min, remove the precipitate, take the supernatant, and evaporate and concentrate it.

[0063] (2) The obtained lignin was analyzed by scanning electron microscopy (SEM).

[0064] FLP represents a condensation-resistant lignin obtained by the formic acid method, and FLP-100 represents an ethanol volume fraction of 100%.

[0065] like Figure 1 As shown in Figure 3, the morphology of the treated lignin after self-assembly, it was found that FLP-50, FLP-40 and FLP-20 all had good uniform morphology.

[0066] (3) The surface of FLP-100 / Fe@cotton fabric is deposited with small particles that form a continuous layer. The roughness increases but is not enough to support water droplets to stay on the fabric for a long time ( Figure 2 a2 and a3).

[0067] FLP-60 / Fe@cotton fabric ( Figure 2 b2 and b3), FLP-50 / Fe@cotton fabric ( Figure 2 c2 and c3) and FLP-40 / Fe@cotton fabric ( Figure 2 The deposition of nearly spherical particles can be observed on d2 and d3. Compared with FLP-60 / Fe@cotton fabric and FLP-40 / Fe@cotton fabric, FLP-50 / Fe@cotton fabric has better uniformity, which is the reason why water droplets can stay on FLP-50 / Fe@cotton fabric for a longer time.

[0068] The particles deposited on FLP-20 / Fe@cotton fabric are nearly spherical but uneven ( Figure 2 e2 and e3).

[0069] Constructing a uniform, compact, and nearly spherical structure on cotton fabric is a key factor in increasing the hydrophobic stability of the cotton fabric surface.

[0070] Depend on Figure 1 It can be seen that the size of the spherical structure of the condensation-inhibited lignin after chelation with metal ions iron or aluminum without ethanol / water system treatment is uncontrollable, as reflected in the SEM images, which are of different sizes and uneven, and cannot provide strong support for its modification.

[0071] Comparative Example 1:

[0072] (1) Lignin treatment: Weigh 1 g of conventional lignin (alkali lignin, sulfate lignin, lignin sulfonate, enzymatic lignin, or groundwood lignin) and dissolve it in 20 mL of anhydrous ethanol / water mixture. The volume fractions of ethanol are 20 mL, 12 mL, 10 mL, 8 mL, and 4 mL, respectively. The specific treatment method is to dissolve the lignin in an ethanol / water solution at a concentration of 5%, preferably 50% ethanol, centrifuge at 3000 rpm for 10 min, remove the precipitate, take the supernatant, and evaporate to dryness to obtain the product.

[0073] (2) The reaction temperature of PEI and KH560 is 35-40°C, preferably 40°C, the reaction time is 2-10h, preferably 4h, the molecular weight of PEI is 800 and 1800, preferably 1800, and the reaction mass ratio of KH560 to PEI is 1:1-1:3, preferably 1:2. The self-crosslinking and co-crosslinking effects of KH560-PEI obtained under this process are both good;

[0074] (3) Impregnation: The ratios of lignin to modified PEI were 1:0.5, 1:1, 1:1.5, and 1:2, respectively; the ratio of aluminum phosphate or iron phosphate to lignin was 0.5:1; the lignin dispersion system was 50% ethanol / 50% water; the dispersion concentration was 5%; the surface diameter of the fiber material (paper or fabric) was 8–10 cm; the impregnation time was 6 h; the blending temperature was 50 °C; and the stirring rate was 200 rpm.

[0075] (4) The surface water contact angle of flame retardant hydrophobic fiber paper and fabric was tested using an optical contact angle meter. The syringe was controlled to drop 5 μL of water on the surface of the test sample, and the corresponding contact angle was measured respectively. The average value of three tests was taken as the test result. According to the standard GB / T 2406.2-2009, the limiting oxygen index of fiber paper and fabric samples was measured using a limiting oxygen index tester. The results are shown in Table 3.

[0076] Table 3 Effect of the ratio of lignin to modified PEI on water contact angle CA (°) and limiting oxygen index LOI

[0077] .

[0078] As shown in Table 3, when the ethanol / water treatment conditions of conventional lignin were fixed, the reaction preparation conditions of PEI and KH560 were fixed, the ratio of several common lignins to modified PEI was fixed at 1:1, the ratio of aluminum phosphate or iron phosphate to lignin was fixed at 1:1, and the immersion treatment conditions of lignin were 5% impregnation concentration, 6 h impregnation time and 50 °C, the contact angle values ​​and limiting oxygen index of the modified paper or fabric were significantly lower than those of poplar formic acid lignin (inhibited condensation lignin).

[0079] Comparative Example 2:

[0080] (1) Lignin treatment: Weigh 1 g of poplar formic acid lignin (condensation-inhibited lignin) and dissolve it in 20 mL of anhydrous ethanol / water mixture, with the volume fractions of ethanol being 20 mL, 12 mL, 10 mL, 8 mL, and 4 mL, respectively. The specific treatment method is to dissolve the lignin in an ethanol / water solution at a concentration of 5%, preferably 50% ethanol, centrifuge at 3000 rpm for 10 min, remove the precipitate, and take the supernatant, which is evaporated to dryness to obtain the product;

[0081] (2) Impregnation: The ratio of aluminum phosphate or iron phosphate to lignin is 0.5:1, the lignin dispersion system is 50% ethanol / 50% water, the dispersion concentration is 5%, the surface diameter of the fiber material (paper or fabric) is 8-10 cm, the time is 6 h, the blending temperature is 50 °C, and the stirring rate is 200 rpm;

[0082] (3) The surface water contact angle of flame retardant hydrophobic fiber paper and fabric was tested using an optical contact angle meter. The syringe was controlled to drop 5 μL of water on the surface of the test sample, and the corresponding contact angle was measured respectively. The average value of three tests was taken as the test result. According to the standard GB / T 2406.2-2009, the limiting oxygen index of fiber paper and fabric samples was measured using a limiting oxygen index tester. The results are shown in Table 4.

[0083] Table 4 Effect of the ratio of lignin to modified PEI on water contact angle CA (°) and limiting oxygen index LOI

[0084] .

[0085] Table 4 shows that the ethanol / water treatment conditions for the immobilized poplar formic acid lignin, the impregnation conditions for the lignin impregnation concentration of 5%, the time of 6 hours, and the temperature of 50°C, and the ratio of immobilized aluminum phosphate or iron phosphate to lignin of 1:0.5 to 1:2 after the modified paper or fabric, while the contact angle did not decrease compared to the fiber materials (paper and fabric) without the addition of modified polyethyleneimine, did significantly decrease the limiting oxygen index. This indicates that the addition of modified polyethyleneimine can enhance the flame retardancy of the modified lignin through self-crosslinking and co-crosslinking of polyethyleneimine. This is because the silicon and nitrogen contained in the modified polyethyleneimine and the phosphorus in the aluminum phosphate or iron phosphate produce a synergistic effect during the flame retardant reaction, thereby enhancing the flame retardancy.

Claims

1. A lignin-based flame retardant hydrophobic fiber material, characterized in that The fiber material is obtained by using condensation-inhibited low-molecular-weight acetic acid lignin or formic acid lignin as raw material, dissolving it in an ethanol / water system for pretreatment, centrifuging to remove precipitation, taking the supernatant, and evaporating to dryness to obtain a lignin pretreatment product; Polyethyleneimine (PEI) is modified by using γ-aminopropyltrimethoxysilane to obtain a modified polyethyleneimine solution; The lignin pretreatment product and the modified polyethyleneimine solution are blended and added into an iron phosphate and / or aluminum phosphate solution, and then fiber paper or fiber fabric is immersed in the solution and dried at a constant temperature to obtain a flame retardant and water-resistant fiber material.

2. The lignin-based flame-retardant hydrophobic fiber material according to claim 1, characterized in that: The volume fraction of ethanol in the ethanol / water system is 20% to 100% v / v; The pretreatment of the condensation-inhibiting lignin is to dissolve the condensation-inhibiting lignin in an ethanol / water solution at a concentration of 5% w / w, centrifuge at 3000 rpm for 10 minutes, remove the precipitate, take the supernatant, and evaporate to dryness.

3. The lignin-based flame-retardant hydrophobic fiber material according to claim 1, characterized in that: The preparation conditions of the modified polyethyleneimine PEI solution are as follows: reaction temperature of 35-40° C., reaction time of 2-10 h, molecular weight of polyethyleneimine PEI of 800 and 1800, and reaction mass ratio of γ-aminopropyltrimethoxysilane to PEI of 1:1-1:

3.

4. The lignin-based flame-retardant hydrophobic fiber material according to claim 1, characterized in that: The concentration of the iron phosphate and / or aluminum phosphate solution is 0.6% to 1.2% by mass; The mass ratio of the pretreated condensation-inhibited lignin to the modified polyethyleneimine PEI solution is 1:0.5-1:2, the mass ratio of the iron phosphate and / or aluminum phosphate solution to the lignin is 0.5:1-1:2, the blending time is 4-7 hours, and the blending temperature is 30-70°C; Immersion treatment time: 24 h; Conditions: temperature 40°C, immersion stirring speed 200 rpm; The mass concentration of lignin in the ethanol / water dispersion system is 2% to 6%; The surface diameter of the fiber paper or fiber fabric is 8 to 10 cm.

5. The method for preparing a lignin-based flame-retardant hydrophobic fiber material according to claim 1, characterized in that The method is: A condensation-inhibiting low-molecular-weight acetate lignin or formate lignin is used as a raw material, dissolved in an ethanol / water system for pretreatment, centrifuged to remove the precipitate, and the supernatant is collected and evaporated to dryness to obtain a lignin pretreatment product. The use of a non-toxic and pollution-free ethanol / water system can screen out highly active condensation-inhibiting lignin with uniform structure. Polyethyleneimine (PEI) is modified with γ-aminopropyltrimethoxysilane to obtain a modified polyethyleneimine solution. The modified polyethyleneimine solution system allows the introduction of amino-rich groups into condensation-inhibiting lignin. Furthermore, γ-aminopropyltrimethoxysilane is more conducive to grafting onto the condensation-inhibiting lignin. The resulting modified polyethyleneimine solution can form a hydrophobic network through self-crosslinking and co-crosslinking, thereby maximizing the flame retardancy and hydrophobicity of the lignin. The lignin pretreatment product and the modified polyethyleneimine solution are blended and then added to an iron phosphate and / or aluminum phosphate solution. The phosphate simultaneously modifies the lignin, introducing nitrogen, phosphorus and metal elements. With the help of the active functional groups on the surface of the lignin, it is made to have both flame retardant and water resistant properties. Fiber paper or fiber fabric is then placed in the mixture for immersion treatment and dried at a constant temperature to obtain a flame retardant and water resistant fiber material.

6. The method for preparing a lignin-based flame-retardant hydrophobic fiber material according to claim 5, characterized in that: (1) The volume fraction of ethanol in the ethanol / water system is 20% to 100% v / v; The pretreatment of the condensation-inhibiting lignin is to dissolve the condensation-inhibiting lignin in an ethanol / water solution at a concentration of 5% w / w, centrifuge at 3000 rpm for 10 minutes, remove the precipitate, take the supernatant, and evaporate to dryness to obtain the pretreated product; (2) The preparation conditions of the modified polyethyleneimine PEI solution are as follows: reaction temperature of 35-40°C, reaction time of 2-10 h, molecular weight of polyethyleneimine PEI of 800 and 1800, and reaction mass ratio of γ-aminopropyltrimethoxysilane to PEI of 1:1-1:3; (3) The concentration of the iron phosphate and / or aluminum phosphate solution is 0.6% to 1.2% by mass; The mass ratio of the pretreated condensation-inhibited lignin to the modified polyethyleneimine PEI solution is 1:0.5-1:2, the mass ratio of the iron phosphate and / or aluminum phosphate solution to the lignin is 0.5:1-1:2, the blending time is 4-7 hours, and the blending temperature is 30-70°C; Immersion treatment time: 24 h; Conditions: temperature 40°C, immersion stirring speed 200 rpm; The mass concentration of lignin in the ethanol / water dispersion system is 2% to 6%; The surface diameter of the fiber paper or fiber fabric is 8 to 10 cm.

7. Use of the lignin-based flame-retardant hydrophobic fiber material according to any one of claims 1 to 4 in flame-retardant hydrophobic decoration materials.

8. Use of the lignin-based flame-retardant and hydrophobic fiber material according to any one of claims 1 to 4 in flame-retardant and hydrophobic protective products.

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