Composite flame-retardant material containing p-nitrobenzyl alcohol and preparation method of composite flame-retardant material

Abstract

The invention relates to the technical field of flame-retardant materials, in particular to a composite flame-retardant material containing p-nitrobenzyl alcohol and a preparation method of the composite flame-retardant material. The polyurethane foaming material is prepared from the following raw materials in parts by weight: 70 to 80 parts of polyether polyol, 15 to 20 parts of modified lignin, 50 to 60 parts of hexamethylene diisocyanate, 35 to 40 parts of diphenylmethane diisocyanate, 3.5 to 5 parts of loading filler, 2 to 3 parts of isopentane foaming agent, 1.5 to 2 parts of dibutyltin dilaurate and 0.5 to 1 part of water, according to the preparation method, graphene oxide is taken as a matrix, a metal organic framework containing a microporous and mesoporous structure is taken as a carrier, p-nitrobenzyl alcohol is loaded, and a phosphorus-containing flame-retardant group is grafted, so that the problem of insufficient flame-retardant property of polyurethane foam is greatly improved; meanwhile, the lignin is modified to introduce an ultraviolet absorption group, and participates in the reaction process of the polyurethane foam, so that the problem of precipitation of a small-molecule auxiliary agent is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant materials, and in particular to a composite flame retardant material containing p-nitrobenzyl alcohol and a preparation method thereof. Background Art

[0002] Polyurethane foam is widely used in building insulation, automotive interiors, and furniture due to its light weight, thermal insulation, and high resilience. However, due to the rich content of carbamate groups and ether bonds in its molecular chain, polyurethane foam is highly flammable. To improve the flame retardancy of polyurethane foam, flame retardants are usually added to the polyurethane foam to achieve a flame retardant effect. At the same time, most polyurethane foams also face the problem of UV aging during use. Patent CN116814063B, "A flame-retardant semi-rigid polyurethane foam and its preparation method," improves the flame retardancy of polyurethane foam by adding an expanding flame retardant and a synergistic flame retardant to the polyurethane foam. Patent CN113736418B, "A modified single-component polyurethane foam sealant and its preparation method," improves the UV aging resistance of polyurethane foam by adding antioxidants and UV absorbers. However, during long-term use, small molecule additives are prone to precipitation, and UV aging leads to a decline in mechanical properties, which cannot meet market demand. Summary of the Invention

[0003] The present invention aims to provide a composite flame retardant material containing p-nitrobenzyl alcohol and a preparation method thereof. A loaded filler and modified lignin are added to a polyurethane foam material, wherein the loaded filler has graphene oxide as a matrix and a metal organic framework containing microporous and mesoporous structures as a carrier, loaded with p-nitrobenzyl alcohol and grafted with phosphorus-containing flame retardant groups, thereby greatly improving the problem of insufficient flame retardancy of the polyurethane foam. At the same time, ultraviolet absorbing groups are introduced by modifying the lignin, and the ultraviolet absorbing groups participate in the reaction process of the polyurethane foam, thereby avoiding the problem of precipitation of small molecule additives.

[0004] The object of the present invention can be achieved by the following technical solution: A method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol, comprising the following steps: Step S1: weighing the following raw materials in parts by weight: 70-80 parts of polyether polyol, 15-20 parts of modified lignin, 50-60 parts of hexamethylene diisocyanate, 35-40 parts of diphenylmethane diisocyanate, 3.5-5 parts of loaded filler, 2-3 parts of isopentane foaming agent, 1.5-2 parts of dibutyltin dilaurate and 0.5-1 part of water;

[0005] Step S2: mixing polyether polyol, modified lignin, loaded filler, isopentane foaming agent, dibutyltin dilaurate and water, stirring, adding hexamethylene diisocyanate and diphenylmethane diisocyanate, stirring, and foaming to prepare a composite flame retardant material containing p-nitrobenzyl alcohol;

[0006] The polyether polyol is HSH360;

[0007] The modified lignin is prepared by the following steps:

[0008] Step A1: Cyanuric chloride and acetone were mixed and stirred at a temperature of 2-5°C for 30 minutes. 4-Ethylsulfonylaniline and deionized water were then added. Sodium carbonate solution was added to adjust the pH to 4.5 and the reaction was carried out for 6-7 hours. 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol were then added. Sodium hydroxide solution was added to adjust the pH to 7.5. The temperature was raised to 40°C and the reaction was carried out for 2.5-3 hours. The mixture was filtered and washed alternately with ethanol and acetone, filtered, and rinsed with methanol to obtain Intermediate 1.

[0009] The mass fraction of the sodium carbonate solution is 20%, the molar concentration of the sodium hydroxide solution is 0.5 mol / L, and the amount ratio of cyanuric chloride, acetone, 4-ethylsulfonylaniline sulfate, deionized water, 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol is 1.82-1.85 g: 20-25 mL: 2.8-2.83 g: 15-20 mL: 2.25-2.3 g;

[0010] During the reaction, by controlling the reaction temperature, the amino group in 4-sulfoethylsulfonylaniline reacts with cyanuric chloride first, and then the reaction temperature is increased to continue the reaction with the phenolic hydroxyl group in 2-(2,4-dihydroxyphenyl)-2H-benzothiazole to obtain intermediate 1.

[0011]

[0012] Step A2: Alkali lignin, 1,4-dioxane, and deionized water were mixed and stirred at a stirring rate of 120-140 rpm at room temperature for 15-20 minutes, and then sodium hydroxide solution was added to adjust the pH to 9. The mixture was stirred and intermediate 1 was added. The temperature was raised to 85° C. and the reaction was continued for 6-8 hours. The mixture was rotary evaporated, washed, and dried to obtain modified lignin.

[0013] The mass fraction of the sodium hydroxide solution is 15%, and the usage ratio of alkali lignin, 1,4-dioxane, deionized water and intermediate 1 is 0.58-0.6 g: 45-50 mL: 15-18 mL: 0.065-0.068 g;

[0014] During the reaction, by controlling the reaction temperature, the chlorine in the intermediate 1 reacts with the phenolic hydroxyl group in the alkali lignin to produce modified lignin;

[0015] The alkali lignin is Maclean alkali lignin;

[0016] The loaded filler is prepared by the following steps:

[0017] Step B1: zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide are mixed, ultrasonically dispersed for 15-20 minutes, stirred at a stirring rate of 120-140 rpm at room temperature for 30 minutes, reacted in a reactor at a temperature of 120° C. for 24 hours, centrifuged, filtered, washed, and dried to obtain precursor 1; precursor 1 is mixed with hydrochloric acid solution, stirred at a stirring rate of 180-200 rpm at room temperature for 1.5-2 hours, centrifuged, filtered, washed, and dried to obtain precursor 2;

[0018] The amount ratio of zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide is 0.18-0.2g: 0.17-0.18g: 0.22-0.23g: 0.1mL: 18-20mL; the mass fraction of hydrochloric acid solution is 20%, and the amount ratio of precursor 1 and hydrochloric acid solution is 0.35-0.4g: 30-40mL;

[0019] During the reaction, zirconium tetrachloride is used as a zirconium source, zinc nitrate is used as a zinc source, and 2-aminoterephthalic acid is used as a ligand. A metal organic framework structure is formed by a solvothermal method to prepare precursor 1. The unstable structure formed by zinc ions is washed away by an acid wash method in a hydrochloric acid solution, thereby forming microporous and mesoporous structures to prepare precursor 2.

[0020] Step B2: Precursor 2, graphene oxide and tetrahydrofuran were mixed and ultrasonically dispersed for 15-20 minutes. Under nitrogen protection, the stirring rate was 180-240 rpm and the temperature was 50°C. 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde were added and reacted for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain Precursor 3. 4-Nitrophenylbenzyl alcohol, Precursor 3 and ethanol were mixed, hydrochloric acid solution was added to adjust the pH value to 4.5, ultrasonically dispersed for 15-20 minutes, stirred at a stirring rate of 120-180 rpm at room temperature for 24 hours, centrifuged, filtered, washed and dried to obtain a loaded filler.

[0021] The amount ratio of precursor 2, graphene oxide, tetrahydrofuran, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde is 0.32-0.35 g: 0.62-0.68 g: 50-55 mL: 0.34-0.36 g: 0.1-0.12 g; the molar concentration of the hydrochloric acid solution is 0.1 mol / L, and the amount ratio of p-nitrobenzyl alcohol, precursor 3 and ethanol is 0.45-0.48 g: 0.86-0.88 g: 15-20 mL;

[0022] During the reaction, under the action of paraformaldehyde, the PH bond in 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide reacts with the amino group in precursor 2. Simultaneously, the amino group in precursor 2 reacts with the oxygen-containing group on the surface of graphene oxide, so that precursor 2 is composited on the graphene oxide to produce precursor 3. Then, under acidic conditions, p-nitrobenzyl alcohol is loaded on precursor 3 through π-π stacking and hydrogen bonding to produce a loaded filler.

[0023] The graphene oxide is JCMIGO graphene oxide produced by Jiacai Technology;

[0024] The paraformaldehyde is McLean paraformaldehyde with a mass fraction of 95%;

[0025] The beneficial effects of the present invention are as follows: the present invention discloses a composite flame retardant material containing p-nitrobenzyl alcohol and a preparation method thereof. A loaded filler and modified lignin are added to a polyurethane foam material, wherein the loaded filler is based on graphene oxide and a metal organic framework containing microporous and mesoporous structures as a carrier, p-nitrobenzyl alcohol is loaded and a phosphorus-containing flame retardant group is grafted. By loading p-nitrobenzyl alcohol in the metal organic framework structure, the loss of p-nitrobenzyl alcohol during the formation of the polyurethane foam is reduced. At the same time, the NP flame retardant system is formed in cooperation with the grafted 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the triazine structure in the lignin. The lignin exerts a condensed phase carbonization effect, further improving the flame retardant properties of the polyurethane foam. Benzotriazole and triazine ultraviolet absorption groups are introduced by modifying the lignin. Since the lignin itself contains a large number of hydroxyl groups, it can participate in the reaction process of the polyurethane foam, not only avoiding the problem of precipitation of small molecule additives, but also improving the mechanical properties of the polyurethane foam to a certain extent due to the structural characteristics of the lignin itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of intermediate 1 in Example 3;

[0027] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the modified lignin in Example 3. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0029] Example 1 A method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol, comprising the following steps: Step S1: weighing the following raw materials in parts by weight: 70 parts of polyether polyol, 15 parts of modified lignin, 50 parts of hexamethylene diisocyanate, 35 parts of diphenylmethane diisocyanate, 3.5 parts of loaded filler, 2 parts of isopentane foaming agent, 1.5 parts of dibutyltin dilaurate, and 0.5 part of water;

[0030] Step S2: mixing polyether polyol, modified lignin, loaded filler, isopentane foaming agent, dibutyltin dilaurate and water, stirring, adding hexamethylene diisocyanate and diphenylmethane diisocyanate, stirring, and foaming to prepare a composite flame retardant material containing p-nitrobenzyl alcohol;

[0031] The polyether polyol is HSH360;

[0032] The modified lignin is prepared by the following steps:

[0033] Step A1: Cyanuric chloride and acetone were mixed and stirred at 2°C for 30 minutes. 4-Ethylsulfonylaniline and deionized water were then added. Sodium carbonate solution was added to adjust the pH to 4.5 and the reaction was carried out for 6 hours. 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol were then added. Sodium hydroxide solution was added to adjust the pH to 7.5. The temperature was raised to 40°C and the reaction was carried out for 2.5 hours. The mixture was filtered and washed alternately with ethanol and acetone, filtered, and rinsed with methanol to obtain Intermediate 1.

[0034] The mass fraction of sodium carbonate solution is 20%, the molar concentration of sodium hydroxide solution is 0.5 mol / L, and the amount ratio of cyanuric chloride, acetone, 4-ethylsulfonylaniline sulfate, deionized water, 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol is 1.82 g: 20 mL: 2.8 g: 15 mL: 2.25 g;

[0035] Step A2: Alkali lignin, 1,4-dioxane, and deionized water were mixed and stirred at room temperature at a stirring rate of 120 rpm for 15 minutes. Then, sodium hydroxide solution was added to adjust the pH to 9. After stirring, intermediate 1 was added and the temperature was raised to 85°C. The reaction was continued for 6 hours, and the mixture was rotary evaporated, washed, and dried to obtain modified lignin.

[0036] The mass fraction of sodium hydroxide solution is 15%, and the amount ratio of alkali lignin, 1,4-dioxane, deionized water and intermediate 1 is 0.58g:45mL:15mL:0.065g;

[0037] The alkali lignin is Maclean alkali lignin;

[0038] The loaded filler is prepared by the following steps:

[0039] Step B1: zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide were mixed, ultrasonically dispersed for 15 minutes, stirred at a stirring rate of 120 rpm at room temperature for 30 minutes, reacted in a reactor at a temperature of 120° C. for 24 hours, centrifuged, filtered, washed, and dried to obtain precursor 1; precursor 1 was mixed with hydrochloric acid solution, stirred at a stirring rate of 180 rpm at room temperature for 1.5-2 hours, centrifuged, filtered, washed, and dried to obtain precursor 2;

[0040] The amount ratio of zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide is 0.18g:0.17g:0.23g:0.1mL:20mL; the mass fraction of hydrochloric acid solution is 20%, and the amount ratio of precursor 1 and hydrochloric acid solution is 0.35g:40mL;

[0041] Step B2: Precursor 2, graphene oxide and tetrahydrofuran were mixed and ultrasonically dispersed for 15 minutes. Under nitrogen protection, a stirring rate of 240 rpm and a temperature of 50°C, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde were added, and the mixture was reacted for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain Precursor 3. 4-Nitrophenylbenzyl alcohol, Precursor 3 and ethanol were mixed, and a hydrochloric acid solution was added to adjust the pH value to 4.5. The mixture was ultrasonically dispersed for 20 minutes. The mixture was stirred at a stirring rate of 120 rpm at room temperature for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain a loaded filler.

[0042] The amount ratio of precursor 2, graphene oxide, tetrahydrofuran, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde is 0.35 g:0.62 g:50 mL:0.36 g:0.1 g; the molar concentration of the hydrochloric acid solution is 0.1 mol / L, and the amount ratio of p-nitrobenzyl alcohol, precursor 3 and ethanol is 0.45 g:0.86 g:20 mL;

[0043] The graphene oxide is JCMIGO graphene oxide produced by Jiacai Technology;

[0044] The paraformaldehyde is MacLean paraformaldehyde with a mass fraction of 95%.

[0045] Example 2 A method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol, comprising the following steps: Step S1: weighing the following raw materials in parts by weight: 70 parts of polyether polyol, 20 parts of modified lignin, 50 parts of hexamethylene diisocyanate, 40 parts of diphenylmethane diisocyanate, 3.5 parts of loaded filler, 3 parts of isopentane foaming agent, 1.5 parts of dibutyltin dilaurate, and 0.5 part of water;

[0046] Step S2: mixing polyether polyol, modified lignin, loaded filler, isopentane foaming agent, dibutyltin dilaurate and water, stirring, adding hexamethylene diisocyanate and diphenylmethane diisocyanate, stirring, and foaming to prepare a composite flame retardant material containing p-nitrobenzyl alcohol;

[0047] The polyether polyol is HSH360;

[0048] The modified lignin is prepared by the following steps:

[0049] Step A1: Cyanuric chloride and acetone were mixed and stirred at 5°C for 30 minutes. 4-Ethylsulfonylaniline and deionized water were then added. Sodium carbonate solution was added to adjust the pH to 4.5 and the reaction was carried out for 6 hours. 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol were then added. Sodium hydroxide solution was added to adjust the pH to 7.5. The temperature was raised to 40°C and the reaction was carried out for 3 hours. The mixture was filtered and washed alternately with ethanol and acetone. The mixture was filtered and washed with methanol to obtain Intermediate 1.

[0050] The mass fraction of sodium carbonate solution is 20%, the molar concentration of sodium hydroxide solution is 0.5 mol / L, and the amount ratio of cyanuric chloride, acetone, 4-ethylsulfonylaniline sulfate, deionized water, 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol is 1.82 g: 25 mL: 2.8 g: 15 mL: 2.3 g;

[0051] Step A2: Alkali lignin, 1,4-dioxane, and deionized water were mixed and stirred at room temperature at a stirring rate of 120 rpm for 20 minutes. Then, sodium hydroxide solution was added to adjust the pH to 9. After stirring, intermediate 1 was added and the temperature was raised to 85°C. The reaction was continued for 6 hours, and the mixture was rotary evaporated, washed, and dried to obtain modified lignin.

[0052] The mass fraction of sodium hydroxide solution is 15%, and the amount ratio of alkali lignin, 1,4-dioxane, deionized water and intermediate 1 is 0.6g:45mL:15mL:0.068g;

[0053] The alkali lignin is Maclean alkali lignin;

[0054] The loaded filler is prepared by the following steps:

[0055] Step B1: zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide were mixed, ultrasonically dispersed for 15 minutes, stirred at a stirring rate of 140 rpm at room temperature for 30 minutes, reacted in a reactor at a temperature of 120° C. for 24 hours, centrifuged, filtered, washed, and dried to obtain precursor 1; precursor 1 was mixed with hydrochloric acid solution, stirred at a stirring rate of 180 rpm at room temperature for 1.5 hours, centrifuged, filtered, washed, and dried to obtain precursor 2;

[0056] The amount ratio of zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide is 0.18g:0.17g:0.22g:0.1mL:18mL; the mass fraction of hydrochloric acid solution is 20%, and the amount ratio of precursor 1 and hydrochloric acid solution is 0.35g:30mL;

[0057] Step B2: Precursor 2, graphene oxide and tetrahydrofuran were mixed and ultrasonically dispersed for 15 minutes. Under nitrogen protection, a stirring rate of 180 rpm and a temperature of 50°C, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde were added, and the mixture was reacted for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain Precursor 3. 4-Nitrophenylbenzyl alcohol, Precursor 3 and ethanol were mixed, and a hydrochloric acid solution was added to adjust the pH value to 4.5. The mixture was ultrasonically dispersed for 15 minutes. The mixture was stirred at a stirring rate of 120 rpm at room temperature for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain a loaded filler.

[0058] The amount ratio of precursor 2, graphene oxide, tetrahydrofuran, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde is 0.32 g: 0.62 g: 50 mL: 0.34 g: 0.1 g; the molar concentration of the hydrochloric acid solution is 0.1 mol / L, and the amount ratio of p-nitrobenzyl alcohol, precursor 3 and ethanol is 0.45 g: 0.86 g: 15 mL;

[0059] The graphene oxide is JCMIGO graphene oxide produced by Jiacai Technology;

[0060] The paraformaldehyde is MacLean paraformaldehyde with a mass fraction of 95%.

[0061] Example 3 A method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol, comprising the following steps: Step S1: Weighing the following raw materials in parts by weight: 80 parts of polyether polyol, 20 parts of modified lignin, 60 parts of hexamethylene diisocyanate, 40 parts of diphenylmethane diisocyanate, 5 parts of loaded filler, 3 parts of isopentane foaming agent, 2 parts of dibutyltin dilaurate, and 1 part of water;

[0062] Step S2: mixing polyether polyol, modified lignin, loaded filler, isopentane foaming agent, dibutyltin dilaurate and water, stirring, adding hexamethylene diisocyanate and diphenylmethane diisocyanate, stirring, and foaming to prepare a composite flame retardant material containing p-nitrobenzyl alcohol;

[0063] The polyether polyol is HSH360;

[0064] The modified lignin is prepared by the following steps:

[0065] Step A1: Cyanuric chloride and acetone were mixed and stirred at 5°C for 30 minutes. 4-Ethylsulfonylaniline and deionized water were then added. Sodium carbonate solution was added to adjust the pH to 4.5 and the reaction was carried out for 7 hours. 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol were then added. Sodium hydroxide solution was added to adjust the pH to 7.5. The temperature was raised to 40°C and the reaction was carried out for 3 hours. The mixture was filtered and washed alternately with ethanol and acetone, filtered, and rinsed with methanol to obtain Intermediate 1.

[0066] The mass fraction of sodium carbonate solution is 20%, the molar concentration of sodium hydroxide solution is 0.5 mol / L, and the amount ratio of cyanuric chloride, acetone, 4-ethylsulfonylaniline sulfate, deionized water, 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol is 1.85 g:25 mL:2.83 g:20 mL:2.3 g;

[0067] Step A2: Alkali lignin, 1,4-dioxane, and deionized water were mixed and stirred at room temperature at a stirring rate of 140 rpm for 20 minutes. Then, sodium hydroxide solution was added to adjust the pH to 9. After stirring, intermediate 1 was added and the temperature was raised to 85°C. The reaction was continued for 8 hours, and the mixture was rotary evaporated, washed, and dried to obtain modified lignin.

[0068] The mass fraction of sodium hydroxide solution is 15%, and the amount ratio of alkali lignin, 1,4-dioxane, deionized water and intermediate 1 is 0.6g:50mL:18mL:0.068g;

[0069] The alkali lignin is Maclean alkali lignin;

[0070] The loaded filler is prepared by the following steps:

[0071] Step B1: zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide were mixed, ultrasonically dispersed for 20 minutes, stirred at a stirring rate of 140 rpm at room temperature for 30 minutes, reacted in a reactor at a temperature of 120° C. for 24 hours, centrifuged, filtered, washed, and dried to obtain precursor 1; precursor 1 was mixed with hydrochloric acid solution, stirred at a stirring rate of 200 rpm at room temperature for 2 hours, centrifuged, filtered, washed, and dried to obtain precursor 2;

[0072] The amount ratio of zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide is 0.2g:0.18g:0.23g:0.1mL:20mL; the mass fraction of hydrochloric acid solution is 20%, and the amount ratio of precursor 1 and hydrochloric acid solution is 0.4g:40mL;

[0073] Step B2: Precursor 2, graphene oxide and tetrahydrofuran were mixed and ultrasonically dispersed for 20 minutes. Under nitrogen protection, a stirring rate of 240 rpm and a temperature of 50°C, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde were added, and the mixture was reacted for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain Precursor 3. 4-Nitrophenylbenzyl alcohol, Precursor 3 and ethanol were mixed, and a hydrochloric acid solution was added to adjust the pH value to 4.5. The mixture was ultrasonically dispersed for 20 minutes. The mixture was stirred at a stirring rate of 180 rpm and room temperature for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain a loaded filler.

[0074] The amount ratio of precursor 2, graphene oxide, tetrahydrofuran, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde is 0.35 g:0.68 g:50-55 mL:0.36 g:0.12 g; the molar concentration of the hydrochloric acid solution is 0.1 mol / L, and the amount ratio of p-nitrobenzyl alcohol, precursor 3 and ethanol is 0.48 g:0.88 g:20 mL;

[0075] The graphene oxide is JCMIGO graphene oxide produced by Jiacai Technology;

[0076] The paraformaldehyde is MacLean paraformaldehyde with a mass fraction of 95%.

[0077] Comparative Example 1 Compared with Example 3, this comparative example is replaced by the modified lignin in the preparation process of the composite flame retardant material containing p-nitrobenzyl alcohol in Example 3 with a commercially available Maclean alkali lignin and UV-320 composition, and the other steps are the same, wherein the weight ratio of alkali lignin to UV-320 is 0.6g:0.005g.

[0078] Comparative Example 2 Compared with Example 3, this comparative example is replaced by a composition of graphene oxide and p-nitrobenzyl alcohol of JCMIGO, a Jiacai Technology company, in the preparation process of the composite flame retardant material containing p-nitrobenzyl alcohol in Example 3. The other steps are the same, and the amount ratio of graphene oxide to p-nitrobenzyl alcohol is 0.88 g:0.04 g.

[0079] The composite flame retardant materials containing p-nitrobenzyl alcohol prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were cut into 100 mm × 10 mm × 10 mm samples with reference to GB / T 2408-2021, and subjected to a vertical burning test. The limiting oxygen index test was performed with reference to GB / T 2406.2-2009, and the tensile strength was tested using a universal mechanical tensile machine. The sample was placed in a UV aging box and UV aged for 28 days, and then the tensile strength was tested, and the tensile strength performance retention rate was calculated. Performance retention rate = tensile strength after aging / tensile strength before aging * 100%. The test results are shown in Table 1 below:

[0080] Table 1 Test results

[0081]

[0082] It can be seen from the test results in the table shown that when Example 1, Example 2 and Example 3 are compared with Comparative Example 1 and Comparative Example 2, Comparative Example 1 replaces the modified lignin in the preparation process of the composite flame retardant material containing p-nitrobenzyl alcohol in Example 3 with a commercially available alkali lignin and UV-320 composition. Since the small molecule additive is not grafted onto the lignin, its performance after ultraviolet aging decreases; Comparative Example 2 replaces the loaded filler in the preparation process of the composite flame retardant material containing p-nitrobenzyl alcohol in Example 3 with a composition of graphene oxide and p-nitrobenzyl alcohol. Since p-nitrobenzyl alcohol is not loaded and there is a lack of phosphorus-containing groups, its flame retardant properties are greatly reduced.

[0083] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0084] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the concept of the invention, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol, characterized in that: The method comprises the following steps: Step S1: weighing the following raw materials in parts by weight: 70-80 parts of polyether polyol, 15-20 parts of modified lignin, 50-60 parts of hexamethylene diisocyanate, 35-40 parts of diphenylmethane diisocyanate, 3.5-5 parts of loaded filler, 2-3 parts of isopentane foaming agent, 1.5-2 parts of dibutyltin dilaurate and 0.5-1 part of water; Step S2: polyether polyol, modified lignin, loaded filler, isopentane foaming agent, dibutyltin dilaurate and water are mixed, stirred, and hexamethylene diisocyanate and diphenylmethane diisocyanate are added, stirred, and foamed to prepare a composite flame retardant material containing p-nitrobenzyl alcohol.

2. The method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol according to claim 1, wherein: The modified lignin is prepared by the following steps: Step A1: Cyanuric chloride and acetone were mixed and stirred at a temperature of 2-5°C for 30 minutes. 4-Ethylsulfonylaniline and deionized water were then added. Sodium carbonate solution was added to adjust the pH to 4.5 and the reaction was carried out for 6-7 hours. 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol were then added. Sodium hydroxide solution was added to adjust the pH to 7.

5. The temperature was raised to 40°C and the reaction was carried out for 2.5-3 hours. The mixture was filtered and washed alternately with ethanol and acetone, filtered, and rinsed with methanol to obtain Intermediate 1. Step A2: Alkali lignin, 1,4-dioxane, and deionized water were mixed and stirred at room temperature at a stirring rate of 120-140 rpm for 15-20 minutes. Then, sodium hydroxide solution was added to adjust the pH to 9. The mixture was stirred and intermediate 1 was added. The temperature was raised to 85° C. and the reaction was continued for 6-8 hours. The mixture was rotary evaporated, washed, and dried to obtain modified lignin.

3. The method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol according to claim 2, wherein: In step A1: the mass fraction of sodium carbonate solution is 20%, the molar concentration of sodium hydroxide solution is 0.5 mol / L, and the amount ratio of cyanuric chloride, acetone, 4-ethylsulfonylaniline sulfate, deionized water, 2-(2,4-dihydroxyphenyl)-2H-benzothiazole and methanol is 1.82-1.85 g: 20-25 mL: 2.8-2.83 g: 15-20 mL: 2.25-2.3 g.

4. The method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol according to claim 2, wherein: In step A2, the mass fraction of the sodium hydroxide solution is 15%, and the usage ratio of alkali lignin, 1,4-dioxane, deionized water and intermediate 1 is 0.58-0.6 g: 45-50 mL: 15-18 mL: 0.065-0.068 g.

5. The method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol according to claim 1, wherein: The loaded filler is prepared by the following steps: Step B1: zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide are mixed, ultrasonically dispersed for 15-20 minutes, stirred at a stirring rate of 120-140 rpm at room temperature for 30 minutes, reacted in a reactor at a temperature of 120° C. for 24 hours, centrifuged, filtered, washed, and dried to obtain precursor 1; precursor 1 is mixed with hydrochloric acid solution, stirred at a stirring rate of 180-200 rpm at room temperature for 1.5-2 hours, centrifuged, filtered, washed, and dried to obtain precursor 2; Step B2: Precursor 2, graphene oxide and tetrahydrofuran were mixed and ultrasonically dispersed for 15-20 minutes. Under nitrogen protection, a stirring rate of 180-240 rpm and a temperature of 50°C, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde were added, and the mixture was reacted for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain precursor 3. 4-Nitrophenylbenzyl alcohol, precursor 3 and ethanol were mixed, and a hydrochloric acid solution was added to adjust the pH value to 4.

5. The mixture was ultrasonically dispersed for 15-20 minutes. The mixture was stirred at a stirring rate of 120-180 rpm and room temperature for 24 hours. The mixture was centrifuged, filtered, washed and dried to obtain a loaded filler.

6. The method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol according to claim 5, characterized in that: In step B1, the ratio of zirconium tetrachloride, 2-aminoterephthalic acid, zinc nitrate, acetic acid and N,N-dimethylformamide is 0.18-0.2 g: 0.17-0.18 g: 0.22-0.23 g: 0.1 mL: 18-20 mL; the mass fraction of the hydrochloric acid solution is 20%, and the ratio of precursor 1 to the hydrochloric acid solution is 0.35-0.4 g: 30-40 mL.

7. The method for preparing a composite flame retardant material containing p-nitrobenzyl alcohol according to claim 5, characterized in that: In step B2: the amount ratio of precursor 2, graphene oxide, tetrahydrofuran, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde is 0.32-0.35 g: 0.62-0.68 g: 50-55 mL: 0.34-0.36 g: 0.1-0.12 g; the molar concentration of the hydrochloric acid solution is 0.1 mol / L, and the amount ratio of p-nitrobenzyl alcohol, precursor 3 and ethanol is 0.45-0.48 g: 0.86-0.88 g: 15-20 mL.

8. A composite flame retardant material containing p-nitrobenzyl alcohol, characterized in that: Prepared according to any one of claims 1 to 7.

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