Bio-based flame retardant, flame-retardant fabric and preparation method of flame-retardant fabric

Abstract

The invention discloses a bio-based flame retardant in the technical field of functional textile materials. The bio-based flame retardant is obtained by oxidizing sugar molecules containing phosphate radicals through an oxidizing agent. The preparation method specifically comprises the following steps: adding sodium periodate into a 1, 6-fructose diphosphate aqueous solution, reacting in a dark place for 2-24 hours, adding ethylene glycol, and reacting for 0.5-1 hour to obtain the bio-based flame retardant. Besides, the bio-based flame retardant is covalently grafted on the surface of the substrate fabric containing the amino functional group through a Schiff base reaction, so that the flame-retardant fabric can be obtained, and the prepared flame-retardant fabric has good flame retardance.

Description

Technical Field

[0001] This invention relates to the field of functional textile materials technology, specifically to a bio-based flame retardant, flame-retardant fabric, and its preparation method. Background Technology

[0002] Textiles, as indispensable materials in daily life and industrial production, are widely used in carpets, blankets, curtains, clothing, and seat covers in transportation vehicles such as airplanes and automobiles. Among these, wool / nylon blends hold an important position due to their excellent skin-friendliness, good mechanical properties, and comfortable user experience. Wool fibers themselves contain 15%–16% nitrogen, 3%–4% sulfur, and 15%–16% moisture, which endow them with certain inherent flame-retardant properties. The addition of nylon fibers further enhances the fabric's abrasion resistance and strength, making wool / nylon blends an important choice in the high-end textile market. However, the addition of nylon fibers makes the fabric highly flammable, and the "wick effect" during combustion poses a significant fire safety hazard to people's lives and property. Therefore, improving its flame-retardant properties has become a critical issue that the textile industry urgently needs to address.

[0003] To date, various halogen-free and formaldehyde-free flame retardants have been developed and applied to fabrics to reduce their flammability and the release of toxic gases. Research indicates that post-treatment, as the most effective method for fabric flame retardancy, has received widespread attention and application; examples include impregnation, layer-by-layer self-assembly (LbL), surface grafting, and sol-gel methods. These surface treatment methods offer several advantages, such as environmental friendliness, ease of operation, low energy consumption, and minimal impact on fiber properties. In recent years, various bio-based or non-toxic compounds have been applied to enhance the flame retardancy of fabrics through post-treatment technologies, including deoxyribonucleic acid (DNA), tannins, organophosphorus compounds, and transition metal ions. However, these technologies typically require loading high-quality flame retardants to meet safety standards, inevitably leading to decreased skin-friendliness and mechanical properties of the fabric. Therefore, the textile industry still urgently needs an environmentally friendly and non-toxic fabric flame retardant technology.

[0004] Chemical grafting, as a post-treatment method, is considered an effective way to construct stable functional surfaces and is widely used in the preparation of flame-retardant fabrics with excellent stability and wash resistance. Because natural fiber fabrics contain functional groups such as hydroxyl (e.g., cotton) and amino (e.g., wool or silk), chemical grafting is often used to modify these fabrics. Typically, reactions such as esterification, condensation, substitution, sol-gel, and UV grafting can form phosphorus-oxygen-carbon (POC), phosphorus-carbon-nitrogen (PCN), carbon-oxygen-carbon (COC), silicon-oxygen-carbon (Si-OC), or carbon-carbon (CC) bonds between the fabric and the flame retardant. YaJuming et al. prepared a flame-retardant cotton fabric with excellent flame retardant properties and good wash resistance by chemically grafting phosphate and melamine onto cotton fabric at 135℃ (A facilestrategy to achieve efficient flame-retardant cotton fabric with durable and restorable fire resistance, Chem. Eng. J., 430 (2022) 132854.). RenYuanlin et al. used UV-induced photografting polymerization technology to graft glycidyl methacrylate and chitosan onto polyacrylonitrile fabric, significantly improving the flame retardant properties of the fabric (Fabrication of chitosan-based intumescent flameretardant coating for improving flame retardancy of polyacrylonitrile fabric, Molecules, 24 (2019) 3749). Although these methods can achieve excellent wash resistance, the initiation of the grafting reaction often requires complex conditions, such as UV irradiation, high temperature, or organic solvent environment. Therefore, a simple and environmentally friendly grafting strategy is still urgently needed for the preparation of flame-retardant fabrics. Summary of the Invention

[0005] To address the aforementioned technological limitations, this invention provides a bio-based flame retardant, flame-retardant fabric, and its preparation method. The key feature of this invention is the utilization of the characteristic that the vicinal diol structure of sugar molecules is easily oxidized by sodium periodate to produce aldehyde groups. First, sodium periodate is used to oxidize phosphate-containing sugar molecules, and then a Schiff base reaction is used to graft these aldehydes onto the surface of a substrate fabric containing amino functional groups, constructing a stable covalent bond system. Simultaneously, the synergistic effect of the flame retardant's own components and the fabric substrate achieves highly efficient flame retardancy. This preparation process is simple, can be applied on a large scale, and uses green and renewable raw materials.

[0006] To achieve the above objectives, this application provides the following technical solution: A bio-based flame retardant, wherein the bio-based flame retardant is obtained by oxidizing phosphate-containing sugar molecules with an oxidizing agent.

[0007] As a preferred embodiment, the sugar molecule is fructose 1,6-bisphosphate.

[0008] As a preferred option, the oxidant is sodium periodate.

[0009] A method for preparing a bio-based flame retardant involves adding sodium periodate to an aqueous solution of fructose 1,6-bisphosphate and reacting it in the dark for 2–24 hours, then adding ethylene glycol and continuing the reaction for 0.5–1 hour to obtain the bio-based flame retardant.

[0010] As a preferred embodiment, the concentration of the fructose-1,6-bisphosphate aqueous solution is 0.01–0.05 mol / L, and the concentration of sodium periodate is 2 g / L.

[0011] A flame-retardant fabric grafted with a bio-based flame retardant, the flame-retardant fabric comprising a bio-based flame retardant and a base fabric containing amino functional groups, wherein the bio-based flame retardant is covalently grafted onto the surface of the base fabric via a Schiff base reaction.

[0012] As a preferred embodiment, the base fabric is a blend of wool and nylon, wherein the wool accounts for 80% to 95% of the total mass.

[0013] As a preferred embodiment, the wool accounts for 90% of the mass and the nylon accounts for 10% of the mass. A method for preparing a flame-retardant fabric includes the following steps: S1. Rinse the base fabric with ethanol and deionized water in sequence to remove surface impurities; S2. Immerse the substrate fabric treated in S1 in the bio-based flame retardant and stir and react at 35-45°C for 1.5-4 hours. S3. Rinse the reacted fabric with deionized water, and then dry it at 75-85°C for 3.5-4.5 hours to obtain flame-retardant fabric.

[0014] As a preferred option, the stirring rate in S2 is 100–300 r / min.

[0015] Preparation principle and beneficial effects of the present invention: Wool itself contains nitrogen (15%-16%), sulfur (3%-4%), and moisture (15%-16%), which give it a certain inherent flame-retardant property. In addition, wool protein contains a large number of functional groups, including hydroxyl (-OH), amino (-NH2), and carboxyl (-COOH) groups. Fructose-1,6-bisphosphate is derived from biomass fructose; after oxidation with sodium periodate, its molecular structure contains both an aldehyde group (-CHO) and a phosphate group (-PO4). 3- The aldehyde group (-CHO) undergoes a Schiff base reaction with the amino group (-NH2) in wool / nylon fabric to form a covalent bond, thereby achieving a strong grafting of the flame retardant and improving the flame retardant properties of the wool / nylon fabric. This grafting process introduces phosphorus into the wool / nylon fabric, forming a nitrogen-phosphorus synergistic flame retardant system with the nitrogen element already present in the fabric. Results show that the prepared flame-retardant fabric (W / NP) exhibits excellent flame retardant properties: compared with pure wool / nylon fabric, its limiting oxygen index (LOI) is increased by 11.3%, and its peak heat release rate (PHRR) is reduced by 53.8%. Furthermore, the prepared W / N-PP fabric retains the mechanical properties of the original wool / nylon fabric.

[0016] Compared with the prior art, the present invention has the following advantages: (1) A bio-based flame retardant with high reactivity was prepared using fructose 1,6-bisphosphate from biomass as raw material. It is highly efficient, environmentally friendly, and has a simple preparation process. (2) A covalently grafted flame retardant system was constructed by Schiff base reaction, which endowed wool / nylon fabrics with high flame retardant properties. Attached Figure Description Figure 1 shows the HRR curves of the flame-retardant wool / nylon blended fabrics prepared in Examples 1-3; Figure 2 shows the THR curves of the flame-retardant wool / nylon blended fabrics prepared in Examples 1-3; Figure 3 shows the SPR curves of the flame-retardant wool / nylon blended fabrics prepared in Examples 1-3. Figure 4 shows the TSP curves of the flame-retardant wool / nylon blended fabrics prepared in Examples 1-3. Detailed Implementation The present invention will be specifically described below through embodiments, and the technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0017] It is necessary to point out that this embodiment is only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description are also considered to fall within the scope of protection of the present invention. It should be emphasized that the substrate dimensions in the specific embodiments described herein are merely for detailing the content of the present invention and are not intended to limit the present invention.

[0018] This invention provides a flame-retardant fabric grafted with a bio-based flame retardant and a method for its preparation. The process steps and conditions of this method are as follows: Example 1 1. Rinse the fabric (W / N) sequentially with ethanol and deionized water to remove surface impurities, and then dry it in an 80℃ oven for 4 hours; 2. Prepare 400 mL of 0.05 mol / L fructose-1,6-bisphosphate aqueous solution, add 0.8 g of sodium periodate and react in the dark for 2 hours, then add 2 drops of ethylene glycol and continue the reaction for 0.5 hours. Finally, adjust the pH of the system to 8.5 using 0.1 mol / L sodium hydroxide solution. The reaction temperature is 30℃. 3. Immerse the washed base fabric in the aqueous solution prepared above and stir the reaction at 40°C for 4 hours; 4. Rinse the reacted fabric with deionized water and then dry it at 80°C for 4 hours to obtain the flame-retardant fabric, named W / N-P5.

[0019] Testing showed that the flame-retardant fabric produced had a load capacity of 10.29%, its limiting oxygen index increased from 26.5% to 27%, and its peak heat release rate increased from 347.12 kW / m³. 2 Reduced to 160.1 kW / m 2 The total heat release is 8.48 MJ / m 2 Reduced to 4.79 MJ / m 2 The smoke release rate is from 0.037 m 2 / s decreased to 0.021 m 2 / s, total smoke release from 0.57 m 2 Reduced to 0.32 m 2 .

[0020] Performance testing: (1) Load Fabrics before and after flame-retardant treatment were dried in an 80℃ oven until constant weight, and then weighed, denoted as M1 and M2 respectively. Fabric load percentage W% = (M2 - M1) / M1 (2) Limiting Oxygen Index (LOI) Test The limiting oxygen index (LOI) test is a commonly used method for testing the flame retardant properties of modern materials. It refers to the minimum oxygen concentration required for the tested material to burn stably in a nitrogen-oxygen mixture. This patent uses a JF-3 oxygen index tester according to ASTM D2863-97. The sample size is 150 mm × 10 mm × 10 mm. Each group of samples is tested three times on average, and the final result is the average value. The evaluation criteria for the test results are shown in Table 1.

[0021] Table 1 Limiting Oxygen Index Rating Table

[0022] The LOI of the flame-retardant fabric can reach up to 29.5%, reaching the level of flame-retardant material. (3) Cone Calorimeter (CC) test The CC is a combustion behavior research instrument designed based on the oxygen consumption principle. It characterizes the combustion behavior of materials by measuring combustion parameters such as time to ignition (TTI), heat release rate (HRR), total heat release (THR), smoke product rate (SPR), and total smoke production (TSP). It is currently recognized as the most ideal small combustion performance testing instrument. In this patent, the CC test of the sample was conducted using a cone calorimeter from Kunshan Modis Combustion Technology Instrument Co., Ltd., with an irradiation power of 35 kW / m 2 The sample size was 100 mm × 100 mm. Testing showed that the peak HRR of the prepared flame-retardant fabric was reduced to 160.1 kW m³. -2 The THR value decreased to 4.79 MJ / m³. -2 Compared with the untreated flame retardant W / N, the W / N ratio was reduced by 53.8% and 43.5%, respectively.

[0023] The above test results show that the bio-based flame retardant significantly improves the flame retardant properties of wool / nylon blended fabrics.

[0024] Example 2 1. Rinse the fabric (W / N) sequentially with ethanol and deionized water to remove surface impurities, and then dry it in an 80℃ oven for 4 hours; 2. Prepare 400 mL of 0.01 mol / L fructose-1,6-bisphosphate aqueous solution, add 0.8 g of sodium periodate and react in the dark for 2 hours, then add 2 drops of ethylene glycol and continue the reaction for 0.5 hours. Finally, adjust the pH of the system to 8.5 using 0.1 mol / L sodium hydroxide solution. The reaction temperature is 30℃. 3. Immerse the washed base fabric in the aqueous solution prepared above and stir the reaction at 40°C for 4 hours; 4. Rinse the reacted fabric with deionized water and then dry it at 80°C for 4 hours to obtain the flame-retardant fabric, named W / N-P1.

[0025] Testing revealed that the flame-retardant fabric exhibited a load capacity of 8.94%, an increase in limiting oxygen index from 26.5% to 28%, and a peak heat release rate from 347.12 kW / m². 2 Reduced to 267.7 kW / m 2 The total heat release is 8.48 MJ / m 2 Reduced to 7.69 MJ / m 2 The smoke release rate is from 0.037 m 2 / s decreased to 0.028 m 2 / s, total smoke release from 0.57 m 2 Reduced to 0.44 m 2 .

[0026] Example 3 1. Rinse the fabric (W / N) sequentially with ethanol and deionized water to remove surface impurities, and then dry it in an 80℃ oven for 4 hours; 2. Prepare 400 mL of 0.03 mol / L fructose-1,6-bisphosphate aqueous solution, add 0.8 g of sodium periodate and react in the dark for 2 hours, then add 2 drops of ethylene glycol and continue the reaction for 0.5 hours. Then adjust the pH of the system to 8.5 using 0.1 mol / L sodium hydroxide solution. The reaction temperature is 30℃. 3. Immerse the washed base fabric in the aqueous solution prepared above and stir the reaction at 40°C for 4 hours; 4. Rinse the reacted fabric with deionized water and then dry it at 80°C for 4 hours to obtain the flame-retardant fabric, named W / N-P3.

[0027] Testing showed that the flame-retardant fabric produced had a load capacity of 9.57%, its limiting oxygen index increased from 26.5% to 29.5%, and its peak heat release rate increased from 347.12 kW / m³. 2 Reduced to 254.39 kW / m 2 The total heat release is 8.48 MJ / m 2Reduced to 6.79 MJ / m 2 The smoke release rate is from 0.037 m 2 / s decreased to 0.024 m 2 / s, total smoke release from 0.57 m 2 Reduced to 0.37 m 2 .

[0028] It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this invention. These modifications and improvements should also be considered within the scope of protection of this invention, and will not affect the effectiveness of the invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A bio-based flame retardant, characterized in that, The bio-based flame retardant is obtained by oxidizing phosphate-containing sugar molecules with an oxidizing agent.

2. The bio-based flame retardant according to claim 1, characterized in that, The sugar molecule is fructose 1,6-bisphosphate.

3. The bio-based flame retardant according to claim 2, characterized in that, The oxidant is sodium periodate.

4. The method for preparing the bio-based flame retardant according to any one of claims 1 to 3, characterized in that, Sodium periodate was added to an aqueous solution of fructose 1,6-bisphosphate and reacted in the dark for 2–24 hours. Then ethylene glycol was added, and the reaction was continued for 0.5–1 hour to obtain the bio-based flame retardant.

5. The method for preparing the bio-based flame retardant according to claim 4, characterized in that, The concentration of the 1,6-bisphosphate fructose aqueous solution is 0.01–0.05 mol / L, and the concentration of sodium periodate is 2 g / L.

6. A flame-retardant fabric grafted with a bio-based flame retardant, characterized in that, The flame-retardant fabric comprises a bio-based flame retardant and a base fabric containing amino functional groups, wherein the bio-based flame retardant is covalently grafted onto the surface of the base fabric via a Schiff base reaction.

7. The flame-retardant fabric according to claim 6, characterized in that, The base fabric is a blend of wool and nylon, wherein the wool accounts for 80% to 95% of the total weight.

8. The flame-retardant fabric according to claim 7, characterized in that, The wool accounts for 90% of the total mass, and the nylon accounts for 10%.

9. The method for preparing the flame-retardant fabric according to any one of claims 6 to 8, characterized in that, Includes the following steps: S1. Rinse the base fabric with ethanol and deionized water in sequence to remove surface impurities; S2. Immerse the substrate fabric treated in S1 in the bio-based flame retardant and stir and react at 35-45°C for 1.5-4 hours. S3. Rinse the reacted fabric with deionized water, and then dry it at 75-85°C for 3.5-4.5 hours to obtain flame-retardant fabric.

10. The method for preparing the flame-retardant fabric according to claim 9, characterized in that, The stirring rate in S2 is 100–300 r / min.

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