Lyocell fiber nonwoven fabric and method for manufacturing the same

Abstract

The present application relates to a kind of lyocell fiber nonwoven fabric and its preparation method, it includes as follows weight parts raw material 20-30 parts cellulose pulp, 4-6 parts modified cellulose, 150-180 parts N-methyl morpholine-N-oxide solution, 1-2 parts antioxidant, 12-15 parts crosslinking impregnant, 2-4 parts sodium phosphate, 140-150 parts ethanol and 30-40 parts water, N-methyl morpholine-N-oxide solution mass fraction is 50%;By adding modified cellulose in the lyocell fiber nonwoven fabric preparation process, to change its crystallinity and orientation, and by impregnation method to its post-processing, so that cellulose molecular chain between each other crosslinking, while introducing nitrogen-phosphorus-sulfur flame retardant system, prepare lyocell fiber nonwoven fabric, so that it has good flame retardant performance and anti fibrillation capacity.

Description

Technical Field

[0001] This invention relates to the field of fiber technology, specifically to a lyocell fiber nonwoven fabric and its preparation method. Background Technology

[0002] Lyocell fiber is a new type of environmentally friendly cellulose fiber. Its preparation process usually involves dissolving the raw material, natural cellulose, in the organic solvent N-methylmorpholine-N-oxide to prepare cellulose pulp. Then, it is spun by wet and dry spinning, solidified in a system such as a low-temperature water bath, and then processed through a series of processes such as air cooling, oiling, stretching, and winding. Its preparation process is simple, the solvent is non-toxic and recyclable, and it does not cause environmental pollution problems. Moreover, its raw material is derived from natural cellulose, which is widely available. Therefore, lyocell fiber is often referred to as a "green fiber".

[0003] However, lyocell fibers and their fabrics are highly flammable and have a low limiting oxygen index, making them combustible. This major drawback severely limits the applicability of lyocell fibers in fire-sensitive locations. Furthermore, when lyocell fibers and fabrics are wet and subjected to mechanical friction, fine fibrils that split axially along the fiber surface separate, easily causing fuzz on the yarn surface. This fibrillation phenomenon negatively impacts the use of lyocell fabrics. For example, during dyeing and finishing processes, it can easily lead to defects such as creases, abrasions, and whitening; or during household washing, fibrillation can occur, affecting the fabric's appearance. Summary of the Invention

[0004] The purpose of this invention is to provide a lyocell fiber nonwoven fabric and its preparation method, which solves the problems of poor flame retardant properties and easy fibrillation of existing lyocell fiber nonwoven fabrics.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A lyocell fiber nonwoven fabric is prepared by the following steps: Step S1: Weigh the following raw materials in parts by weight: 20-30 parts cellulose pulp, 4-6 parts modified cellulose, 150-180 parts N-methylmorpholine-N-oxide solution, 1-2 parts antioxidant, 12-15 parts crosslinking impregnating agent, 2-4 parts sodium phosphate, 140-150 parts ethanol and 30-40 parts water, wherein the mass fraction of N-methylmorpholine-N-oxide solution is 50%;

[0007] Step S2: Mix cellulose pulp, modified cellulose, antioxidant and N-methylmorpholine-N-oxide solution to prepare spinning solution. Add spinning solution to spinning meltblown equipment, spin, meltblown, form web, wash to obtain unimpregnated nonwoven fabric.

[0008] Step S3: Mix crosslinking impregnating agent, sodium phosphate, ethanol and water to prepare crosslinking impregnating solution. Immerse the unimpregnated nonwoven fabric in the crosslinking impregnating solution at a temperature of 70℃ for 30-40 minutes. Then, use a rolling mill to immerse and roll the fabric twice, controlling the roll-off rate to 80%. Remove the fabric, wash it with water, pre-dry it at 80℃, and bake it at 140℃ to obtain a Lyocell fiber nonwoven fabric.

[0009] The modified cellulose is obtained through the following steps:

[0010] Step A1: Mix cellulose with deionized water and disperse ultrasonically. Add sodium periodate under light-protected conditions and a temperature of 50-60℃. Let the reaction stand for 3-4 hours, cool to room temperature, add ethylene glycol, and continue the reaction for 1-2 hours to obtain aldehyde cellulose.

[0011] The molar concentration of sodium periodate is 1.5 mol / L, and the ratio of cellulose, sodium periodate and ethylene glycol is 6-8 g: 50-60 mL: 6 mL;

[0012] In step A1, cellulose and deionized water are mixed and ultrasonically dispersed, and then reacted with sodium periodate. Due to the strong oxidizing property of sodium periodate, the secondary hydroxyl groups at the C2-C3 ortho position in the glucose units of cellulose are selectively oxidized to aldehyde groups. Ethylene glycol is then added to react with sodium periodate to terminate the reaction and obtain aldehyde cellulose.

[0013] Step A2: Mix 2-acrylamide and deionized water, and under nitrogen protection, stir at a speed of 120-150 rpm and a temperature of 60°C. Add mercaptoethylamine and ammonium persulfate and react for 8-10 h to obtain amino-terminated polyacrylamide. Mix graphene oxide, isophorone diisocyanate and N,N-dimethylformamide and ultrasonically disperse. Under nitrogen protection, stir at a speed of 240-300 rpm and a temperature of 80°C for 24 h. Add amino-terminated polyacrylamide and continue to react for 24 h to obtain grafted graphene oxide.

[0014] The ratio of 2-acrylamide, mercaptoethylamine, and ammonium persulfate is 0.1-0.15 mol: 0.01-0.015 mol: 0.005 mol; the ratio of graphene oxide, isophorone diisocyanate, and amino-terminated polyacrylamide is 2 g: 0.02-0.03 mol: 8-10 g.

[0015] In step A2, 2-acrylamide polymerizes in deionized water under the initiator ammonium persulfate and is capped by the reaction of thiol groups and double bonds to obtain amino-terminated polyacrylamide. In N,N-dimethylformamide, the hydroxyl groups in graphene oxide react with the isocyanate groups of isophorone diisocyanate to form aminomethyl ester groups, resulting in isocyanate groups on the surface of graphene oxide. These isocyanate groups then react with the amino groups in the amino-terminated polyacrylamide to form urea groups. Acrylamide is then grafted onto graphene oxide to obtain grafted graphene oxide.

[0016] Step A3: Mix trifluoroacetic acid, triethylsilane, grafted graphene oxide and acetonitrile, stir at a stirring speed of 120-150 rpm and a temperature of 110℃, add aldehyde cellulose, react for 18 h, add acetic anhydride, cool to 35℃, and continue to react for 0.5-1 h to obtain modified cellulose.

[0017] The ratio of trifluoroacetic acid, triethylsilane, grafted graphene oxide, acetonitrile, aldehyde cellulose and acetic anhydride is 60-70 mL: 50 mL: 2 g: 300 mL: 6-8 g: 30-40 mL;

[0018] In step A3, in acetonitrile, the aldehyde group in aldehyde cellulose and the amide in grafted graphene oxide undergo N-reduction alkylation reaction under the action of trifluoroacetic acid and triethylsilane. The aldehyde group first undergoes dehydration condensation with the amide to form an acetal amine, which is then reduced and hydrogenated to an amino group to obtain the cellulose graphene oxide system. Then, acetic anhydride is added, and the hydroxyl group in aldehyde cellulose undergoes acetylation reaction with acetic anhydride under the catalysis of trifluoroacetic acid to obtain modified cellulose.

[0019] The crosslinking wetting agent is prepared by the following steps:

[0020] Step B1: Mix 2-chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)aminoacetate, and tetrahydrofuran. Under nitrogen protection, with a stirring rate of 90-120 rpm and at room temperature, stir and add di-tert-butyl dicarbonate. React for 16-18 h to obtain intermediate 1. Mix intermediate 1, sodium hydrosulfide, and anhydrous ethanol. Under a stirring rate of 90-120 rpm and a temperature of 85 °C, react for 8 h to obtain intermediate 2. Mix intermediate 2 and tetrahydrofuran. Under a stirring rate of 90-120 rpm and at room temperature, add hydrogen peroxide and react for 0.5-1 h to obtain intermediate 3.

[0021] The ratio of 2-chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)aminoacetate, and di-tert-butyl dicarbonate is 0.02 mol: 0.04-0.05 mol: 0.04-0.05 mol; the ratio of intermediate 1 to sodium hydrosulfide is 0.02 mol: 1.2-1.4 g; the hydrogen peroxide concentration is 30%, and the ratio of intermediate 2 to hydrogen peroxide is 0.02 mol: 1.5-1.6 g.

[0022] In step B1, in tetrahydrofuran, the amino group of 2-chloro-4,6-diamino-1,3,5-triazine reacts with di-tert-butyl dicarbonate under the action of sodium bis(trimethylsilyl)amino to form intermediate 1 with a bis-Boc protected amino group. The chlorine in intermediate 1 reacts with sodium hydrosulfide in anhydrous ethanol to generate a mercapto group, thus obtaining intermediate 2. In tetrahydrofuran, the mercapto group in intermediate 2 undergoes condensation under the action of hydrogen peroxide to form a disulfide bond, thus obtaining intermediate 3.

[0023] Step B2: Intermediate 3, tert-butyldimethoxytrifluoromethanesulfonate and dichloromethane are mixed and reacted at room temperature for 6 hours with a stirring rate of 120-150 rpm to obtain intermediate 4. Intermediate 4, p-hydroxybenzaldehyde and tetrahydrofuran are mixed and reacted at 50°C with a stirring rate of 120-150 rpm for 4-6 hours under nitrogen protection. Then DOPO is added, the temperature is raised to 60°C and the reaction is carried out for 12 hours to obtain intermediate 5.

[0024] Intermediate 3, tert-butyldimethoxysilyl trifluoromethanesulfonate, and dichloromethane were used in a ratio of 0.01 mol: 0.01 mol: 120 mL; Intermediate 4, p-hydroxybenzaldehyde, and DOPO were used in a ratio of 0.01 mol: 0.04-0.05 mol: 0.04-0.05 mol.

[0025] In step B2, intermediate 3 is first deprotected by Boc using a system of tert-butyldimethoxytrifluoromethane and dichloromethane to form a primary amine, which then reacts with the aldehyde group in p-hydroxybenzaldehyde to form an imine bond. DOPO is then added, and the PH bond in DOPO reacts with the imine bond, causing DOPO to be grafted into intermediate 4 to obtain intermediate 5.

[0026] Step B3: Mix intermediate 5, triethylamine and tetrahydrofuran, stir at a stirring speed of 80-120 rpm at room temperature, add acryloyl chloride, and react for 12 h to obtain the crosslinking impregnating agent;

[0027] The ratio of intermediate 5, triethylamine, and acryloyl chloride is 0.01 mol: 5 g: 0.08-0.1 mol;

[0028] In step B3, during the reaction, the hydroxyl group in intermediate 5 reacts with the acyl chloride in acryloyl chloride in tetrahydrofuran to form an ester group, thus preparing a crosslinking wetting agent;

[0029] The beneficial effects of this invention are as follows: This invention discloses a lyocell fiber nonwoven fabric and its preparation method. Modified cellulose is added during the preparation of the lyocell fiber nonwoven fabric, and post-treatment is performed via impregnation to obtain a lyocell fiber nonwoven fabric with good flame retardant properties and anti-fibrillation ability. Modified cellulose is obtained by mixing polyacrylamide-grafted graphene oxide with aldehyde cellulose and linking them through chemical bonds, while simultaneously acetylifying the hydroxyl groups in the cellulose. After blending the modified cellulose with the base material, the steric hindrance effect of the acetyl groups hinders the orientation and crystallization of cellulose molecules. Furthermore, the reduction in hydroxyl groups reduces the aggregation between large cellulose molecules, thus improving the cellulose's molecular structure. The reduced crystallinity of the cellulose during the spinning and solidification process improves the molecular structure of its amorphous regions, reduces the orientation of lyocell fibers, and thus weakens the fibrillation ability of lyocell nonwoven fabrics. Simultaneously, because the modified cellulose also contains polyacrylamide-grafted graphene oxide linked by chemical bonds, it not only ensures the dispersion of graphene oxide in the matrix, but also, due to the presence of polyacrylamide segments, increases the binding force of the amorphous regions of the fiber, reduces the formation of hydrogen bonds between cellulose fibers, and disrupts the regular arrangement of cellulose crystalline units, thereby enhancing the fiber's fibrillation ability. Furthermore, due to the inherent properties of graphene oxide, it can improve the mechanical properties of lyocell fibers to a certain extent. Intermediate 3, containing disulfide bonds, was prepared by thiolation of 2-chloro-4,6-diamino-1,3,5-homogeneous triazine followed by self-condensation. After deprotection of intermediate 3 with Boc, it reacted with p-hydroxybenzaldehyde to introduce DOPO, yielding intermediate 5. Intermediate 5 then reacted with acryloyl chloride to prepare a crosslinking impregnating agent containing disulfide bonds, DOPO flame-retardant groups, and multiple double bonds, based on a triazine compound. Nonwoven fabric was immersed in the crosslinking impregnating solution. Under the action of sodium phosphate catalyst, the double bonds in the crosslinking impregnating agent reacted with the hydroxyl groups of cellulose, forming ether bonds. This crosslinking of the cellulose macromolecular chains enhanced the interaction between cellulose fibers, thereby increasing the lateral bonding of the fibers. The force inhibits fibrillation, giving Lyocell fiber nonwoven fabric excellent fibrillation resistance. Since the crosslinking impregnating agent is based on triazine compounds and contains disulfide bonds and DOPO groups, it can form a nitrogen-phosphorus-sulfur flame retardant system. When combustion occurs, the crosslinking impregnating agent decomposes upon heating to release sulfur free radicals, which effectively capture free radicals in the early stage of combustion, delay the chain reaction, promote rapid carbonization of fibers, and form a stable and dense carbon layer under the action of phosphorus. At the same time, the sulfur-containing and nitrogen-containing non-combustible gases generated by the combustion of sulfur and nitrogen can also dilute combustible gases and block combustion, thus giving Lyocell fiber nonwoven fabric good flame retardant properties. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] The modified cellulose is obtained through the following steps:

[0033] Step A1: Mix commercially available Yuheng 30μm cellulose with deionized water and ultrasonically disperse. Add sodium periodate at 50℃ in the dark and let it stand for 4 hours. Cool to room temperature, add ethylene glycol, and continue the reaction for 1 hour to obtain aldehyde cellulose.

[0034] The molar concentration of sodium periodate is 1.5 mol / L, and the ratio of cellulose, sodium periodate and ethylene glycol is 6 g: 50 mL: 6 mL.

[0035] Step A2: Mix 2-acrylamide and deionized water, and under nitrogen protection, stir at 120 rpm and 60°C, add mercaptoethylamine and ammonium persulfate, and react for 10 h to obtain amino-terminated polyacrylamide. Mix commercially available Shuobang 10μm graphene oxide, isophorone diisocyanate and N,N-dimethylformamide and ultrasonically disperse, and react under nitrogen protection, stir at 240 rpm and 80°C for 24 h. Add amino-terminated polyacrylamide and continue to react for 24 h to obtain grafted graphene oxide.

[0036] The ratio of 2-acrylamide, mercaptoethylamine, and ammonium persulfate was 0.1 mol: 0.01 mol: 0.005 mol; the ratio of graphene oxide, isophorone diisocyanate, and amino-terminated polyacrylamide was 2 g: 0.02 mol: 8 g.

[0037] Step A3: Trifluoroacetic acid, triethylsilane, grafted graphene oxide and acetonitrile are mixed and stirred at a stirring speed of 120 rpm and a temperature of 110°C. Aldehyde cellulose is added and the reaction is carried out for 18 h. Acetic anhydride is added, the temperature is lowered to 35°C, and the reaction is continued for 0.5 h to obtain modified cellulose.

[0038] The ratio of trifluoroacetic acid, triethylsilane, grafted graphene oxide, acetonitrile, aldehyde cellulose, and acetic anhydride is 60 mL: 50 mL: 2 g: 300 mL: 6 g: 30 mL.

[0039] Example 2

[0040] The modified cellulose is obtained through the following steps:

[0041] Step A1: Mix commercially available Yuheng 30μm cellulose with deionized water and ultrasonically disperse. Add sodium periodate under light-protected conditions and a temperature of 60℃. Let the reaction stand for 3 hours, cool to room temperature, add ethylene glycol, and continue the reaction for 2 hours to obtain aldehyde cellulose.

[0042] The molar concentration of sodium periodate is 1.5 mol / L, and the ratio of cellulose, sodium periodate and ethylene glycol is 8 g: 50 mL: 6 mL.

[0043] Step A2: Mix 2-acrylamide and deionized water, and under nitrogen protection, stir at 150 rpm and 60°C. Add mercaptoethylamine and ammonium persulfate and react for 8 h to obtain amino-terminated polyacrylamide. Mix commercially available Shuobang 10μm graphene oxide, isophorone diisocyanate and N,N-dimethylformamide and ultrasonically disperse. Under nitrogen protection, stir at 300 rpm and 80°C for 24 h. Add amino-terminated polyacrylamide and continue to react for 24 h to obtain grafted graphene oxide.

[0044] The ratio of 2-acrylamide, mercaptoethylamine, and ammonium persulfate was 0.15 mol: 0.01 mol: 0.005 mol; the ratio of graphene oxide, isophorone diisocyanate, and amino-terminated polyacrylamide was 2 g: 0.03 mol: 8 g.

[0045] Step A3: Trifluoroacetic acid, triethylsilane, grafted graphene oxide and acetonitrile are mixed and stirred at a stirring speed of 150 rpm and a temperature of 110 ℃. Aldehyde cellulose is added and reacted for 18 h. Acetic anhydride is added, the temperature is lowered to 35 ℃, and the reaction is continued for 1 h to obtain modified cellulose.

[0046] The ratio of trifluoroacetic acid, triethylsilane, grafted graphene oxide, acetonitrile, aldehyde cellulose, and acetic anhydride is 60 mL: 50 mL: 2 g: 300 mL: 8 g: 30 mL.

[0047] Example 3

[0048] The modified cellulose is obtained through the following steps:

[0049] Step A1: Mix commercially available Yuheng 30μm cellulose with deionized water and ultrasonically disperse. Add sodium periodate under light-protected conditions and a temperature of 60℃. Let the reaction stand for 4 hours, cool to room temperature, add ethylene glycol, and continue the reaction for 2 hours to obtain aldehyde cellulose.

[0050] The molar concentration of sodium periodate is 1.5 mol / L, and the ratio of cellulose, sodium periodate and ethylene glycol is 8 g: 60 mL: 6 mL.

[0051] Step A2: Mix 2-acrylamide and deionized water, and under nitrogen protection, stir at 150 rpm and 60°C. Add mercaptoethylamine and ammonium persulfate and react for 10 h to obtain amino-terminated polyacrylamide. Mix commercially available Shuobang 10μm graphene oxide, isophorone diisocyanate and N,N-dimethylformamide and ultrasonically disperse. Under nitrogen protection, stir at 300 rpm and 80°C for 24 h. Add amino-terminated polyacrylamide and continue to react for 24 h to obtain grafted graphene oxide.

[0052] The ratio of 2-acrylamide, mercaptoethylamine, and ammonium persulfate was 0.15 mol: 0.015 mol: 0.005 mol; the ratio of graphene oxide, isophorone diisocyanate, and amino-terminated polyacrylamide was 2 g: 0.03 mol: 10 g.

[0053] Step A3: Trifluoroacetic acid, triethylsilane, grafted graphene oxide and acetonitrile are mixed and stirred at a stirring speed of 150 rpm and a temperature of 110 ℃. Aldehyde cellulose is added and reacted for 18 h. Acetic anhydride is added, the temperature is lowered to 35 ℃, and the reaction is continued for 1 h to obtain modified cellulose.

[0054] The ratio of trifluoroacetic acid, triethylsilane, grafted graphene oxide, acetonitrile, aldehyde cellulose, and acetic anhydride is 70 mL: 50 mL: 2 g: 300 mL: 8 g: 40 mL.

[0055] Example 4

[0056] The crosslinking wetting agent is prepared by the following steps:

[0057] Step B1: 2-Chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)aminoacetate and tetrahydrofuran were mixed and stirred at 90 rpm under nitrogen protection at room temperature. Di-tert-butyl dicarbonate was added and the mixture was reacted for 18 h to obtain intermediate 1. Intermediate 1, sodium hydrosulfide and anhydrous ethanol were mixed and stirred at 90 rpm at 85 °C for 8 h to obtain intermediate 2. Intermediate 2 and tetrahydrofuran were mixed and hydrogen peroxide was added at 90 rpm at room temperature. The mixture was reacted for 1 h to obtain intermediate 3.

[0058] The molar ratio of 2-chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)aminoacetate, and di-tert-butyl dicarbonate was 0.02 mol: 0.04 mol: 0.04 mol; the molar ratio of intermediate 1 to sodium hydrosulfide was 0.02 mol: 1.2 g; the hydrogen peroxide concentration was 30%, and the molar ratio of intermediate 2 to hydrogen peroxide was 0.02 mol: 1.5 g.

[0059] Step B2: Intermediate 3, tert-butyldimethoxytrifluoromethanesulfonate and dichloromethane are mixed and reacted at room temperature for 6 hours with a stirring rate of 120 rpm to obtain intermediate 4. Intermediate 4, p-hydroxybenzaldehyde and tetrahydrofuran are mixed and reacted at 50°C with a stirring rate of 120 rpm for 6 hours under nitrogen protection. Then DOPO is added, the temperature is raised to 60°C and reacted for 12 hours to obtain intermediate 5.

[0060] Intermediate 3, tert-butyldimethoxysilyl trifluoromethanesulfonate, and dichloromethane were used in a ratio of 0.01 mol: 0.01 mol: 120 mL; Intermediate 4, p-hydroxybenzaldehyde, and DOPO were used in a ratio of 0.01 mol: 0.04 mol: 0.04 mol.

[0061] Step B3: Mix intermediate 5, triethylamine and tetrahydrofuran, stir at 80 rpm at room temperature and add acryloyl chloride, react for 12 h to obtain crosslinking impregnating agent;

[0062] The ratio of intermediate 5, triethylamine, and acryloyl chloride is 0.01 mol: 5 g: 0.08 mol.

[0063] Example 5

[0064] The crosslinking wetting agent is prepared by the following steps:

[0065] Step B1: 2-Chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)amino and tetrahydrofuran were mixed and stirred at 120 rpm under nitrogen protection at room temperature. Di-tert-butyl dicarbonate was added and the mixture was reacted for 16 h to obtain intermediate 1. Intermediate 1, sodium hydrosulfide and anhydrous ethanol were mixed and stirred at 120 rpm at 85 °C for 8 h to obtain intermediate 2. Intermediate 2 and tetrahydrofuran were mixed and stirred at 120 rpm at room temperature. Hydrogen peroxide was added and the mixture was reacted for 0.5 h to obtain intermediate 3.

[0066] The molar ratio of 2-chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)aminoacetate, and di-tert-butyl dicarbonate was 0.02 mol: 0.05 mol: 0.04 mol; the molar ratio of intermediate 1 to sodium hydrosulfide was 0.02 mol: 1.3 g; the hydrogen peroxide concentration was 30%, and the molar ratio of intermediate 2 to hydrogen peroxide was 0.02 mol: 1.5 g.

[0067] Step B2: Intermediate 3, tert-butyldimethoxytrifluoromethanesulfonate and dichloromethane are mixed and reacted at room temperature for 6 hours with a stirring rate of 150 rpm to obtain intermediate 4. Intermediate 4, p-hydroxybenzaldehyde and tetrahydrofuran are mixed and reacted at 50°C with a stirring rate of 150 rpm for 4 hours under nitrogen protection. Then DOPO is added, the temperature is raised to 60°C and the reaction is carried out for 12 hours to obtain intermediate 5.

[0068] Intermediate 3, tert-butyldimethoxysilyl trifluoromethanesulfonate, and dichloromethane were used in a ratio of 0.01 mol: 0.01 mol: 120 mL; Intermediate 4, p-hydroxybenzaldehyde, and DOPO were used in a ratio of 0.01 mol: 0.04 mol: 0.05 mol.

[0069] Step B3: Mix intermediate 5, triethylamine and tetrahydrofuran, stir at a stirring speed of 80-120 rpm at room temperature, add acryloyl chloride, and react for 12 h to obtain the crosslinking impregnating agent;

[0070] The ratio of intermediate 5, triethylamine, and acryloyl chloride is 0.01 mol: 5 g: 0.09 mol.

[0071] Example 6

[0072] The crosslinking wetting agent is prepared by the following steps:

[0073] Step B1: 2-Chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)aminoacetate and tetrahydrofuran were mixed and stirred at 120 rpm under nitrogen protection and at room temperature. Di-tert-butyl dicarbonate was added and the mixture was reacted for 18 h to obtain intermediate 1. Intermediate 1, sodium hydrosulfide and anhydrous ethanol were mixed and stirred at 120 rpm and 85 °C for 8 h to obtain intermediate 2. Intermediate 2 and tetrahydrofuran were mixed and hydrogen peroxide was added at 120 rpm and at room temperature. The mixture was reacted for 1 h to obtain intermediate 3.

[0074] The ratio of 2-chloro-4,6-diamino-1,3,5-triazine, sodium di(trimethylsilyl)aminoacetate, and di-tert-butyl dicarbonate was 0.02 mol: 0.05 mol: 0.05 mol; the ratio of intermediate 1 to sodium hydrosulfide was 0.02 mol: 1.4 g; the hydrogen peroxide concentration was 30%, and the ratio of intermediate 2 to hydrogen peroxide was 0.02 mol: 1.6 g.

[0075] Step B2: Intermediate 3, tert-butyldimethoxytrifluoromethanesulfonate and dichloromethane are mixed and reacted at room temperature with a stirring rate of 150 rpm for 6 h to obtain intermediate 4. Intermediate 4, p-hydroxybenzaldehyde and tetrahydrofuran are mixed and reacted at 50°C with a stirring rate of 150 rpm for 6 h under nitrogen protection. Then DOPO is added, the temperature is raised to 60°C and reacted for 12 h to obtain intermediate 5.

[0076] Intermediate 3, tert-butyldimethoxysilyl trifluoromethanesulfonate, and dichloromethane were used in a ratio of 0.01 mol: 0.01 mol: 120 mL; Intermediate 4, p-hydroxybenzaldehyde, and DOPO were used in a ratio of 0.01 mol: 0.05 mol: 0.05 mol.

[0077] Step B3: Mix intermediate 5, triethylamine and tetrahydrofuran, stir at 120 rpm at room temperature and add acryloyl chloride, react for 12 h to obtain crosslinking impregnating agent;

[0078] The ratio of intermediate 5, triethylamine, and acryloyl chloride is 0.01 mol: 5 g: 0.1 mol.

[0079] Example 7

[0080] A lyocell fiber nonwoven fabric is prepared by the following steps: Step S1: Weigh the following raw materials in parts by weight: 20 parts of commercially available Xidian 500 cellulose pulp, 4 parts of modified cellulose of Example 1, 150 parts of N-methylmorpholine-N-oxide solution, 1 part of 1010 antioxidant, 12 parts of crosslinking impregnating agent of Example 4, 2 parts of sodium phosphate, 140 parts of ethanol and 30 parts of water, wherein the mass fraction of N-methylmorpholine-N-oxide solution is 50%;

[0081] Step S2: Mix cellulose pulp, modified cellulose, antioxidant and N-methylmorpholine-N-oxide solution to prepare spinning solution. Add spinning solution to spinning meltblown equipment, spin, meltblown, form web, wash to obtain unimpregnated nonwoven fabric.

[0082] Step S3: Mix crosslinking impregnating agent, sodium phosphate, ethanol and water to prepare crosslinking impregnating solution. Immerse unimpregnated nonwoven fabric in crosslinking impregnating solution at 70℃ for 40 minutes. Then, use a rolling mill for two dips and two rolls, with the roll rate controlled at 80%. Remove the fabric, wash it with water, pre-dry it at 80℃, and bake it at 140℃ to obtain a Lyocell fiber nonwoven fabric.

[0083] Example 8

[0084] A lyocell fiber nonwoven fabric is prepared by the following steps: Step S1: Weigh the following raw materials in parts by weight: 30 parts of commercially available Xidian 500 cellulose pulp, 4 parts of modified cellulose of Example 2, 180 parts of N-methylmorpholine-N-oxide solution, 2 parts of 1010 antioxidant, 15 parts of crosslinking impregnating agent of Example 5, 2 parts of sodium phosphate, 150 parts of ethanol and 40 parts of water, wherein the mass fraction of N-methylmorpholine-N-oxide solution is 50%;

[0085] Step S2: Mix cellulose pulp, modified cellulose, antioxidant and N-methylmorpholine-N-oxide solution to prepare spinning solution. Add spinning solution to spinning meltblown equipment, spin, meltblown, form web, wash to obtain unimpregnated nonwoven fabric.

[0086] Step S3: Mix crosslinking impregnating agent, sodium phosphate, ethanol and water to prepare crosslinking impregnating solution. Immerse unimpregnated nonwoven fabric in crosslinking impregnating solution at 70℃ for 30 minutes. Then, use a rolling mill for two dips and two rolls, with the roll-off rate controlled at 80%. Remove the fabric, wash it with water, pre-dry it at 80℃, and bake it at 140℃ to obtain a Lyocell fiber nonwoven fabric.

[0087] Example 9

[0088] A lyocell fiber nonwoven fabric is prepared by the following steps: Step S1: Weigh the following raw materials in parts by weight: 30 parts of commercially available Xidian 500 cellulose pulp, 6 parts of modified cellulose of Example 3, 180 parts of N-methylmorpholine-N-oxide solution, 2 parts of 1010 antioxidant, 15 parts of crosslinking impregnating agent of Example 6, 4 parts of sodium phosphate, 150 parts of ethanol and 40 parts of water, wherein the mass fraction of N-methylmorpholine-N-oxide solution is 50%;

[0089] Step S2: Mix cellulose pulp, modified cellulose, antioxidant and N-methylmorpholine-N-oxide solution to prepare spinning solution. Add spinning solution to spinning meltblown equipment, spin, meltblown, form web, wash to obtain unimpregnated nonwoven fabric.

[0090] Step S3: Mix crosslinking impregnating agent, sodium phosphate, ethanol and water to prepare crosslinking impregnating solution. Immerse unimpregnated nonwoven fabric in crosslinking impregnating solution at 70℃ for 40 minutes. Then, use a rolling mill for two dips and two rolls, with the roll rate controlled at 80%. Remove the fabric, wash it with water, pre-dry it at 80℃, and bake it at 140℃ to obtain a Lyocell fiber nonwoven fabric.

[0091] Comparative Example 1

[0092] Compared with Example 9, the modified cellulose in this comparative example was replaced with commercially available Yuheng 30μm cellulose, while the other steps were the same.

[0093] Comparative Example 2

[0094] Compared with Example 9, this comparative example replaced the grafted graphene oxide in the modified cellulose preparation process with a mixture of commercially available Xintai 20 polyacrylamide and commercially available Shuobang 10μm graphene oxide, with a polyacrylamide to graphene oxide weight ratio of 5g:1g, and the other steps were the same.

[0095] Comparative Example 3

[0096] Compared with Example 9, this comparative example replaces the crosslinking wetting agent with intermediate 5 from Example 6, while the other steps are the same.

[0097] Comparative Example 4

[0098] Compared with Example 9, the crosslinking wetting agent in this comparative example is replaced with 1,3,5-triacryloyl-hexahydrotriazine, while the other steps are the same.

[0099] A lyocell fiber nonwoven fabric prepared according to Examples 7, 8, 9, Comparative Examples 1, 2, 3, and 4 was used. Referring to T / CCFA 01026-2016 and FZ / T52019-2018, it was prepared into 5mm × 200mm samples, immersed in water for 30 minutes, and the wet friction time was measured using a rotary evaporation wet friction device. The anti-fibrillation performance was judged by the length of the wet friction time. The contact angle was 45°, the friction shaft speed was 500 rpm, and the weight was 10g. The mechanical properties were tested using a universal testing machine with a tensile rate of 10mm / min and a clamping distance of 10mm. Referring to GB / T5454-1997, the limiting oxygen index was tested using an oxygen index meter. The test results are shown in the table below.

[0100]

[0101] As shown in the table, comparing Examples 7, 8, and 9 with Comparative Examples 1, 2, 3, and 4, Comparative Example 1, which replaced the modified cellulose with commercially available Yuheng 30μm cellulose, showed a significant decrease in antigen fibrillation properties and tensile strength due to the lack of grafted graphene oxide. This indicates that acetylated cellulose and graphene oxide can improve the antigen fibrillation properties and tensile strength of lyocell fiber nonwoven fabric. Comparative Example 2, which replaced the grafted graphene oxide with commercially available Xintai 20 polyacrylamide and commercially available Shuobang 10μm graphene oxide... The graphene mixture, due to the lack of chemical bonds between graphene oxide and cellulose, cannot be uniformly dispersed in the substrate, resulting in a certain decrease in its elongation at break and tensile strength. In Comparative Example 3, the crosslinking impregnating agent was replaced with intermediate 5 from Example 6. Since intermediate 5 lacks double bonds compared to the crosslinking impregnating agent, it cannot crosslink the nonwoven fabric, resulting in poor antifibrillation performance of the nonwoven fabric. In Comparative Example 4, the crosslinking impregnating agent was replaced with 1,3,5-triacryloyl-hexahydrotriazine. Due to the imperfection of the flame retardant system, the flame retardant performance of the nonwoven fabric was significantly reduced.

[0102] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0103] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A process for the production of a lyocell fiber nonwoven fabric, characterized by: It is prepared by the following steps: step S1: take the following weight parts of raw materials: 20-30 parts of cellulose pulp, 4-6 parts of modified cellulose, 150-180 parts of N-methyl morpholine-N-oxide solution, 1-2 parts of antioxidant, 12-15 parts of crosslinking infiltration agent, 2-4 parts of sodium phosphate, 140-150 parts of ethanol and 30-40 parts of water, the mass fraction of N-methyl morpholine-N-oxide solution is 50%; Step S2: mix the cellulose pulp, modified cellulose, antioxidant and N-methyl morpholine-N-oxide solution to prepare a spinning dope, add the spinning dope into a spinning melt blowing device, spin, melt blow, web, rinse to prepare an un-infiltrated non-woven fabric; Step S3: mix the crosslinking infiltration agent, sodium phosphate, ethanol and water to prepare a crosslinking infiltration solution, soak the un-infiltrated non-woven fabric in the crosslinking infiltration solution at a temperature of 70℃ for 30-40min, two-dip two-press with a calender, the rolling rate is controlled to be 80%, take out, wash with water, pre-dry at 80℃, and bake at 140℃ to prepare a lyocell fiber non-woven fabric; The modified cellulose is prepared by the following steps: Step A1: mix the cellulose with deionized water and ultrasonic dispersion, add sodium periodate under light shielding and at a temperature of 50-60℃, stand for reaction for 3-4h, reduce to room temperature, add ethylene glycol, and continue to react for 1-2h to prepare aldehyde cellulose; Step A2: mix 2-acrylamide with deionized water, stir under nitrogen protection at a stirring speed of 120-150rpm and at a temperature of 60℃, add mercaptoethylamine and ammonium persulfate, and react for 8-10h to prepare amino-terminated polyacrylamide, mix graphene oxide, isophorone diisocyanate and N,N-dimethylformamide and ultrasonic dispersion, react under nitrogen protection at a stirring speed of 240-300rpm and at a temperature of 80℃ for 24h, add the amino-terminated polyacrylamide, and continue to react for 24h to prepare grafted graphene oxide; Step A3: mix trifluoroacetic acid, triethylsilane, grafted graphene oxide and acetonitrile, stir at a stirring speed of 120-150rpm and at a temperature of 110℃, add the aldehyde cellulose, react for 18h, add acetic anhydride, reduce the temperature to 35℃, and continue to react for 0.5-1h to prepare modified cellulose; The crosslinking infiltration agent is prepared by the following steps: Step B1: mix 2-chloro-4.6-diamino-1.3.5-triazine, sodium bis(trimethylsilyl)amide and tetrahydrofuran, stir under nitrogen protection at a stirring speed of 90-120rpm and at room temperature, add di-tert-butyl dicarbonate, and react for 16-18h to prepare intermediate 1, mix the intermediate 1, sodium hydrosulfide and anhydrous ethanol, react at a stirring speed of 90-120rpm and at a temperature of 85℃ for 8h to prepare intermediate 2, mix the intermediate 2 and tetrahydrofuran, add hydrogen peroxide under stirring at a stirring speed of 90-120rpm and at room temperature for 0.5-1h to prepare intermediate 3; Step B2: intermediate 3, tert-butyldimethylsilyl trifluoromethanesulfonate and dichloromethane were mixed, and reacted at room temperature for 6 h with stirring at a stirring rate of 120-150 rpm, to obtain intermediate 4; intermediate 4, p-hydroxybenzaldehyde and tetrahydrofuran were mixed, and reacted at 50°C for 4-6 h under nitrogen protection with stirring at a stirring rate of 120-150 rpm, then DOPO was added, and the reaction was continued at 60°C for 12 h, to obtain intermediate 5; Step B3: intermediate 5, triethylamine and tetrahydrofuran were mixed, and stirred at room temperature, and acryloyl chloride was added, and the reaction was continued for 12 h, to obtain the cross-linking wetting agent.

2. A process for the production of lyocell fiber nonwoven fabric according to claim 1, characterized in that: In step A1: the molar concentration of sodium periodate was 1.5 mol / L, and the amount ratio of cellulose, sodium periodate and ethylene glycol was 6-8 g: 50-60 mL: 6 mL.

3. The method for preparing a lyocell fiber nonwoven fabric according to claim 1, characterized in that: In step A2: the amount ratio of 2-acrylamide, mercaptoethylamine and ammonium persulfate was 0.1-0.15 mol: 0.01-0.015 mol: 0.005 mol; the amount ratio of graphene oxide, isophorone diisocyanate and amino-terminated polyacrylamide was 2 g: 0.02-0.03 mol: 8-10 g.

4. The method of claim 1, wherein the lyocell fiber nonwoven fabric is prepared by the steps of: In step A3: the amount ratio of trifluoroacetic acid, triethylsilane, grafted graphene oxide, acetonitrile, aldehyde cellulose and acetic anhydride was 60-70 mL: 50 mL: 2 g: 300 mL: 6-8 g: 30-40 mL.

5. The method for preparing a lyocell fiber nonwoven fabric according to claim 1, characterized in that: In step B1: the amount ratio of 2-chloro-4.6-diamino-1.3.5-triazine, sodium bis(trimethylsilyl)amide and di-tert-butyl dicarbonate was 0.02 mol: 0.04-0.05 mol: 0.04-0.05 mol; the amount ratio of intermediate 1 and sodium hydrosulfide was 0.02 mol: 1.2-1.4 g; the mass concentration of hydrogen peroxide was 30%, and the amount ratio of intermediate 2 and hydrogen peroxide was 0.02 mol: 1.5-1.6 g.

6. The method for preparing a lyocell fiber nonwoven fabric according to claim 1, characterized in that: In step B2: the amount ratio of intermediate 3, tert-butyldimethylsilyl trifluoromethanesulfonate and dichloromethane was 0.01 mol: 0.01 mol: 120 mL; the amount ratio of intermediate 4, p-hydroxybenzaldehyde and DOPO was 0.01 mol: 0.04-0.05 mol: 0.04-0.05 mol.

7. The method for preparing a lyocell fiber nonwoven fabric according to claim 1, characterized in that: In step B3: the amount ratio of intermediate 5, triethylamine and acryloyl chloride was 0.01 mol: 5 g: 0.08-0.1 mol.

8. A lyocell fiber nonwoven fabric, characterized by: Prepared according to any one of the preparation methods in claims 1-7. Prepared according to any one of the preparation methods in claims 1-7.

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