Nitrogen-phosphorus flame-retardant antibacterial agent, nitrogen-phosphorus-silicon-based flame-retardant antibacterial cotton fabric and preparation method and application of nitrogen-phosphorus-silicon-based flame-retardant antibacterial cotton fabric

Abstract

The invention relates to a nitrogen-phosphorus flame-retardant antibacterial agent, a nitrogen-phosphorus-silicon-based flame-retardant antibacterial cotton fabric and a preparation method and application of the nitrogen-phosphorus flame-retardant antibacterial agent and the nitrogen-phosphorus-silicon-based flame-retardant antibacterial cotton fabric. The structural formula of the nitrogen-phosphorus flame-retardant antibacterial agent is shown in the formula (1), and the nitrogen-phosphorus flame-retardant antibacterial agent is named APDD. According to the nitrogen-phosphorus-silicon-based flame-retardant antibacterial cotton fabric, nano-silica particles are grafted to a cotton fabric through a hydrolysis reaction and a copolymerization reaction to obtain a SiO2 modified cotton fabric, and a nitrogen-phosphorus flame-retardant antibacterial agent APDD is grafted to the SiO2 modified cotton fabric under the catalytic action of dicyanodiamine to obtain the nitrogen-phosphorus-silicon-based flame-retardant antibacterial cotton fabric. The modified cotton fabric disclosed by the invention not only has excellent flame-retardant and antibacterial effects, but also is environment-friendly, low in cost and easy for large-scale industrial production, and has a wide market application prospect.

Description

Technical Field

[0001] This invention belongs to the field of fiber material modification technology, and specifically relates to a nitrogen-phosphorus flame retardant and antibacterial agent, a nitrogen-phosphorus-silicon-based flame retardant and antibacterial cotton fabric, and their preparation methods and applications. Background Technology

[0002] Cellulose textiles, as one of the most important application areas of polymer materials, are used in various fields including daily life, industry, agriculture, transportation, military, and healthcare. However, due to their limiting oxygen index (LOI) of only 18%, cellulose textiles are flammable fibers. They burn rapidly when exposed to open flames, generating high heat and large amounts of smoke, easily igniting and spreading fires. This poses a serious fire safety hazard during use, limiting their application in both residential and protective applications. Furthermore, due to their porous and hydrophilic structure, cellulose textiles are inevitably susceptible to microbial contamination during use. This not only affects fabric performance but, if pathogens are not promptly eliminated, can even threaten public safety. Therefore, developing cellulose textiles with both flame-retardant and antibacterial functions is essential.

[0003] Commonly used flame retardants in textiles include halogenated, phosphorus-based, nitrogen-based, and silicon-based flame retardants. However, in 1982, the Swiss Federal Institute of Technology discovered that incomplete combustion of halogenated flame retardants produces dioxins, which are harmful to humans and the environment. Therefore, the use of halogenated flame retardants has been gradually banned. Currently, research on flame retardants mainly focuses on nitrogen-phosphorus based retardants, often employing the Mannich reaction. The expansion and charring of phosphorus-based flame retardants has been the most extensively studied. Phosphorus is the most important flame-retardant component, while nitrogen primarily promotes flame-retardant efficiency. Silicon further enhances the strength and stability of the charred layer and forms a silicon oxide layer at high temperatures, providing better heat insulation and oxygen barrier properties. Therefore, a synergistic combination of phosphorus, nitrogen, and silicon is used to optimize the characteristics of various flame retardants, allowing them to complement each other based on the properties of the matrix material during use, maximizing their effectiveness. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a nitrogen-phosphorus flame-retardant and antibacterial agent, a nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric, and their preparation methods and applications, so as to reasonably optimize the characteristics of various flame retardants and make them complement each other based on the properties of the matrix material during use, thereby maximizing the flame-retardant effect.

[0005] This invention provides a nitrogen-phosphorus based flame retardant and antibacterial agent, the structural formula of which is:

[0006] Name it APDD.

[0007] Preferably, the nitrogen-phosphorus flame retardant and antibacterial agent is prepared by addition and esterification reactions using 1,3-diamino-2-propanol (DH), dicyandiamide (DCD), phosphorus pentoxide (P2O5), and urea as raw materials.

[0008] Preferably, the theoretical molar ratio of 1,3-diamino-2-propanol, dicyandiamide, phosphorus pentoxide, and urea is 1:2:0.5:1.

[0009] This invention provides a method for preparing a nitrogen-phosphorus-based flame retardant and antibacterial agent, comprising the following steps:

[0010] S1. Weigh out dicyandiamide and 1,3-diamino-2-propanol and dissolve them separately in deionized water. Adjust the pH of the 1,3-diamino-2-propanol solution to 4-5. Then mix the two solutions and stir the reaction at 60-80℃ for 2-4 hours.

[0011] S2. After the stirring reaction in step S1 is completed, raise the temperature to 75-85℃, add phosphorus pentoxide, and continue the reaction for 1-3 hours;

[0012] S3. After the reaction in step S2 is completed, add urea and add a reflux condenser, and heat to 125-135℃ to react for 1-2 hours;

[0013] S4. After the reaction in step S3 is completed, the solvent in the mixed solution is removed by rotary evaporation to obtain a white solid. After post-processing, a white viscous solid is obtained, which is APDD, a nitrogen-phosphorus flame retardant and antibacterial agent with a biguanide structure.

[0014] Preferably, the reagents used to adjust the pH in step S1 include, but are not limited to, 0.1-0.2 mol / L hydrochloric acid.

[0015] Preferably, the post-processing in step S4 is as follows: the white solid is washed with anhydrous ethanol, and finally dissolved in deionized water, pre-frozen, and then freeze-dried to obtain a white viscous solid.

[0016] This invention provides a nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric. The nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric is obtained by grafting nano-silica particles (SiO2) onto cotton fabric through hydrolysis and copolymerization to obtain SiO2-modified cotton fabric, and by grafting the above-mentioned nitrogen-phosphorus flame-retardant and antibacterial agent APDD with a biguanide structure onto the SiO2-modified cotton fabric under the catalysis of dicyandiamide.

[0017] This invention provides a method for preparing a nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric, comprising the following steps:

[0018] Step 1. Preparation of SiO2 modified cotton fabric

[0019] Dry cotton fabric and nano-silica particles were added to a water / ethanol mixture, and 3-(trimethoxysilyl)propyl methacrylate was added. The mixture was subjected to a hydrolysis reaction for 10-12 hours. After the hydrolysis reaction was completed, the reaction solution and cotton fabric were reacted at 65-75℃ for 2-3 hours. After the reaction was completed, the cotton fabric was removed, washed with deionized water and dried to obtain SiO2 modified cotton fabric, i.e., Co-SiO2.

[0020] Step 2. Preparation of nitrogen-phosphorus-silicon based flame-retardant and antibacterial cotton fabric

[0021] APDD modification solution was prepared, dicyandiamide was added as a catalyst, and SiO2 modified cotton fabric was soaked in APDD modification solution at 65-75℃ for 1-2 hours; then it was placed in a high temperature of 165-175℃ for 5-10 minutes, and after being taken out, washed and dried, nitrogen-phosphorus-silicon based flame-retardant and antibacterial cotton fabric, namely Co-SiO2-APDD.

[0022] Preferably, the mass ratio of the cotton fabric to the nano silica particles and 3-(trimethoxysilyl)methacrylate in step one is 2.7-3.3:0.9-1.1:0.9-1.1.

[0023] Preferably, the entire reaction process in step one requires protection from light.

[0024] Preferably, the APDD modified liquid in step two is prepared by dissolving the nitrogen-phosphorus flame retardant and antibacterial agent APDD in deionized water, with a concentration of 5-15 wt%; the ratio of the SiO2 modified cotton fabric to the APDD modified liquid bath is 1:25-1:35.

[0025] Preferably, the mass fraction of dicyandiamine in the APDD modified solution in step two is 5-10 wt%.

[0026] The present invention also provides the application of the above-mentioned nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric in intimate home textile materials and medical textile materials.

[0027] Beneficial effects

[0028] (1) The method of the present invention synthesizes a novel nitrogen-phosphorus flame retardant and antibacterial agent APDD in a one-pot process. The flame retardant contains a biguanide structure, which makes it have both flame retardant and antibacterial functions. Therefore, the modified cotton fabric prepared not only has excellent flame retardant effect, but also has excellent antibacterial effect against Escherichia coli and Staphylococcus aureus.

[0029] (2) The flame-retardant and antibacterial cotton fabric prepared by the method of the present invention has the synergistic effect of three flame-retardant elements: nitrogen, phosphorus and silicon. It is halogen-free, environmentally friendly and has low cytotoxicity.

[0030] (3) The preparation process of this invention is simple, the cost is low, and it is easy to carry out large-scale industrial production. It can be widely used in the fields of personal home textile materials and medical textile materials, and has broad market application prospects. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric (Co-SiO2-APDD) in this invention.

[0032] Figure 2 This is a synthesis route diagram of the nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric (Co-SiO2-APDD) in this invention.

[0033] Figure 3 This is a comparison of the infrared spectra (FTIR) of the nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric and the original cotton fabric in Example 2 of the present invention.

[0034] Figure 4 The images show the antibacterial effects of the nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric and the original cotton fabric in Examples 1-3 of this invention. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0036] Example 1

[0037] The preparation method of APDD, a nitrogen-phosphorus flame retardant and antibacterial agent containing a biguanide structure, in this embodiment is as follows:

[0038] Weigh 3.44 g of dicyandiamide (DCD) and 1.82 g of 1,3-diamino-2-propanol (DH), and dissolve them separately in 125 mL of deionized water. Adjust the pH of the DH solution to 4 with hydrochloric acid. Then, mix the two solutions and pour them into a three-necked flask. Stir in a constant temperature oil bath at 60 °C for 2 h. After the reaction is complete, raise the temperature of the oil bath to 75 °C, add 1.42 g of phosphorus pentoxide (P₂O₅) to the mixture, and continue the reaction for 1 h. After the reaction is complete, add a reflux condenser to the three-necked flask and add 1.26 g of urea to the mixture. Raise the temperature to 125 °C and react for 1 h. After the reaction is complete, pour the mixed solution into a 500 mL single-necked flask, evaporate the solvent using a rotary evaporator, and wash the white solid multiple times with anhydrous ethanol. Finally, dissolve it in deionized water, pre-freeze, and freeze-dry for 3 days to obtain a white viscous solid, namely APDD.

[0039] The preparation method of nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric in this embodiment includes the following steps:

[0040] Step 1. Preparation of SiO2 modified cotton fabric

[0041] 1.35 g of dried cotton fabric and 0.45 g of nano-silica particles (SiO2) were added to 100 mL of a water / ethanol mixture (V / V, 1 / 1), and 0.45 g of 3-(trimethoxysilyl)methacrylate (KH570) was added to carry out a hydrolysis reaction for 10 h. After hydrolysis, the reaction solution and cotton fabric were poured into a three-necked flask and reacted in a constant temperature water bath at 65 °C for 2 h. The reaction was carried out in the dark throughout. After the reaction was completed, the cotton fabric was taken out, washed with deionized water, and dried to obtain SiO2 modified cotton fabric, i.e., Co-SiO2.

[0042] Step 2. Preparation of nitrogen-phosphorus-silicon based flame-retardant and antibacterial cotton fabric

[0043] APDD, a nitrogen-phosphorus multifunctional flame retardant, was dissolved in deionized water to prepare a 5 wt% APDD modification solution. 5 wt% DCD was added as a catalyst. Dry SiO2-modified cotton fabric was immersed in the APDD modification solution at a bath ratio of 1:35 at 65°C for 1 hour. Subsequently, it was baked at 165°C for 5 minutes. After removal, it was washed and dried 30 times to obtain nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric (Co-SiO2-APDD).

[0044] Example 2

[0045] The preparation method of APDD, a nitrogen-phosphorus flame retardant and antibacterial agent containing a biguanide structure, in this embodiment is as follows:

[0046] 3.44 g of dicyandiamide (DCD) and 1.82 g of 1,3-diamino-2-propanol (DH) were weighed and dissolved separately in 125 mL of deionized water. The pH of the DH solution was adjusted to 4.5 with hydrochloric acid. The two solutions were then mixed and poured into a three-necked flask, and stirred in a constant temperature oil bath at 70 °C for 3 h. After the reaction was completed, the temperature of the oil bath was raised to 80 °C, and 1.42 g of phosphorus pentoxide (P₂O₅) was added to the mixture, and the reaction was continued for 2 h. After the reaction was completed, a reflux condenser was added to the three-necked flask, and 1.26 g of urea was added to the mixture. The temperature was raised to 130 °C and the reaction was continued for 1.5 h. After the reaction was completed, the mixed solution was poured into a 500 mL single-necked flask, and the solvent was evaporated using a rotary evaporator. The white solid was washed several times with anhydrous ethanol, and finally dissolved in deionized water. After pre-freezing, it was freeze-dried for 3 days to obtain a white viscous solid, namely APDD.

[0047] The preparation method of nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric in this embodiment includes the following steps:

[0048] Step 1. Preparation of SiO2 modified cotton fabric

[0049] 1.5g of dry cotton fabric and 0.5g of nano-silica particles (SiO2) were added to 100mL of a water / ethanol mixture (V / V, 1 / 1), and 0.5g of 3-(trimethoxysilyl)methacrylate (KH570) was added to carry out a hydrolysis reaction for 11h. After hydrolysis, the reaction solution and cotton fabric were poured into a three-necked flask and reacted in a constant temperature water bath at 70℃ for 2.5h. The reaction was carried out in the dark. After the reaction was completed, the cotton fabric was taken out, washed with deionized water, and dried to obtain SiO2 modified cotton fabric, i.e., Co-SiO2.

[0050] Step 2. Preparation of nitrogen-phosphorus-silicon based flame-retardant and antibacterial cotton fabric

[0051] APDD, a nitrogen-phosphorus multifunctional flame retardant, was dissolved in deionized water to prepare a 10 wt% APDD modification solution. 8 wt% DCD was added as a catalyst. Dry SiO2-modified cotton fabric was immersed in the APDD modification solution at a bath ratio of 1:30 at 70°C for 1.5 h. Subsequently, it was baked at 170°C for 8 min. After removal, it was washed and dried 30 times to obtain a nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric (Co-SiO2-APDD).

[0052] Example 3

[0053] The preparation method of APDD, a nitrogen-phosphorus flame retardant and antibacterial agent containing a biguanide structure, in this embodiment is as follows:

[0054] 3.44 g of dicyandiamide (DCD) and 1.82 g of 1,3-diamino-2-propanol (DH) were weighed and dissolved separately in 125 mL of deionized water. The pH of the DH solution was adjusted to 5 with hydrochloric acid. The two solutions were then mixed and poured into a three-necked flask, and stirred in an oil bath at 80 °C for 4 h. After the reaction was complete, the temperature of the oil bath was raised to 85 °C, and 1.42 g of phosphorus pentoxide (P₂O₅) was added to the mixture. The reaction was continued for 3 h. After the reaction was complete, a reflux condenser was added to the three-necked flask, and 1.26 g of urea was added to the mixture. The temperature was raised to 135 °C and the reaction was continued for 2 h. After the reaction was complete, the mixed solution was poured into a 500 mL single-necked flask, and the solvent was evaporated using a rotary evaporator. The white solid was washed several times with anhydrous ethanol, and finally dissolved in deionized water. After pre-freezing, it was freeze-dried for 3 days to obtain a white viscous solid, namely APDD.

[0055] The preparation method of nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric in this embodiment includes the following steps:

[0056] Step 1. Preparation of SiO2 modified cotton fabric

[0057] 1.65 g of dried cotton fabric and 0.55 g of nano-silica particles (SiO2) were added to 100 mL of a water / ethanol mixture (V / V, 1 / 1), and 0.55 g of 3-(trimethoxysilyl)propyl methacrylate (KH570) was added to carry out a hydrolysis reaction for 12 h. After hydrolysis, the reaction solution and cotton fabric were poured into a three-necked flask and reacted in a constant temperature water bath at 75 °C for 3 h. The reaction was carried out in the dark throughout. After the reaction was completed, the cotton fabric was taken out, washed with deionized water, and dried to obtain SiO2 modified cotton fabric, i.e., Co-SiO2.

[0058] Step 2. Preparation of nitrogen-phosphorus-silicon based flame-retardant and antibacterial cotton fabric

[0059] APDD, a nitrogen-phosphorus multifunctional flame retardant, was dissolved in deionized water to prepare a 15 wt% APDD modified solution. 10 wt% DCD was added as a catalyst. Dry SiO2-modified cotton fabric was immersed in the APDD modified solution at a bath ratio of 1:25 at 75°C for 2 hours. It was then baked at 175°C for 10 minutes. After removal, it was washed and dried 30 times to obtain a nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric (Co-SiO2-APDD).

[0060] Fourier Transform Infrared Spectroscopy: The chemical structures of the raw cotton fabric (Co) and the modified cotton fabric Co-SiO2-APDD prepared in Example 2 were tested using a Thermo Fisher Nicolet 6700 Fourier Transform Infrared Spectrometer. The FT-IR spectra of the raw cotton and the modified cotton fabric were compared, and the results are as follows. Figure 3 As shown, characteristic peaks of APDD appeared in all modified cotton fabrics grafted with APDD, with the peak at 930 cm⁻¹ being the most prominent. -1 and 1241cm -1 The peaks at 1638 cm⁻¹ are characteristic peaks of the PO and P=O functional groups in phosphate groups, respectively. -1 The peak at 998 cm⁻¹ represents the characteristic peak of the C=N group. -1 The peak at 800 cm⁻¹ represents the stretching vibration of the POC functional group. -1 The characteristic peaks at these locations belong to the Si-O functional groups. These characteristic peaks indicate that both APDD and SiO2 have been successfully grafted onto the cotton fabric.

[0061] Limiting oxygen index (LOI) test: According to GB / T5454-1997 "Determination of Burning Performance of Textiles - Oxygen Index Method", this test method involves placing the sample under vertical test conditions in an oxygen-nitrogen mixed gas flow to determine the minimum oxygen concentration (also known as the limiting oxygen index) required to sustain combustion. The sample is clamped in a sample holder and placed vertically inside a combustion chamber. The upper part of the sample is ignited in an upward-flowing oxygen stream, and its combustion characteristics are observed. The afterflame time, smoldering time, and damage length are compared with the specified limiting value. By testing a series of samples at different oxygen concentrations, the minimum oxygen concentration value, expressed as the percentage of oxygen required to sustain combustion, can be determined. The test results are shown in Table 1 below.

[0062] Table 1. UL94 vertical burning test data and LOI values ​​of the nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabrics and raw cotton prepared in Examples 1-3.

[0063]

[0064] As shown in Table 1, the LOI value of the original cotton fabric was only 18.0%, classifying it as a flammable material. After modification with the nitrogen-phosphorus flame retardant and antibacterial agent APDD and SiO2, the LOI value of the Co-SiO2-APDD cotton fabric showed an increasing trend, classifying it as a flame-retardant fabric. This indicates that the N / P / Si elements have a good synergistic effect in achieving flame retardancy in cotton fabrics. Furthermore, after 30 washes, the LOI value remained above 28%, demonstrating good wash durability.

[0065] Antimicrobial performance testing and conclusions: Antimicrobial performance was tested according to GB / T 20944.3-2008 "Evaluation of antimicrobial properties of textiles - Part 3: Shaking method". Staphylococcus aureus and Escherichia coli were selected as standard strains in the experiment. The plate count method was used to visually evaluate the antimicrobial properties of the modified cotton fabric Co-SiO2-APDD (Samples 1-3 in Examples 1-3 respectively) and raw cotton prepared in the examples. Figure 4 It can be observed that the control group agar plates showed relatively dense colonies, while the number of bacterial colonies in the agar plates treated with modified cotton fabric Co-SiO2-APDD was significantly reduced, or even almost disappeared, indicating that modified cotton fabric Co-SiO2-APDD has good antibacterial properties.

[0066] The preparation process of this invention is simple and environmentally friendly. It not only endows cotton fabrics with excellent flame retardant and antibacterial effects, but also improves the economic added value of the product.

[0067] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can design other equivalent embodiments with the above-mentioned technical content without departing from the scope of the technical solution of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A nitrogen-phosphorus based flame retardant and antibacterial agent, characterized in that, Its structural formula is: Name it APDD.

2. The nitrogen-phosphorus flame retardant and antibacterial agent according to claim 1, characterized in that, The nitrogen-phosphorus flame retardant and antibacterial agent is prepared by addition and esterification reactions using 1,3-diamino-2-propanol, dicyandiamide, phosphorus pentoxide and urea as raw materials.

3. The nitrogen-phosphorus flame retardant and antibacterial agent according to claim 1, characterized in that, The theoretical molar ratio of 1,3-diamino-2-propanol, dicyandiamide, phosphorus pentoxide, and urea is 1:2:0.5:

1.

4. A method for preparing a nitrogen-phosphorus based flame retardant and antibacterial agent, comprising the following steps: S1. Weigh out dicyandiamide and 1,3-diamino-2-propanol and dissolve them separately in deionized water. Adjust the pH of the 1,3-diamino-2-propanol solution to 4-5. Then mix the two solutions and stir the reaction at 60-80℃ for 2-4 hours. S2. After the stirring reaction in step S1 is completed, raise the temperature to 75-85℃, add phosphorus pentoxide, and continue the reaction for 1-3 hours; S3. After the reaction in step S2 is completed, add urea and add a reflux condenser, and heat to 125-135℃ to react for 1-2 hours; S4. After the reaction in step S3 is completed, the solvent in the mixed solution is removed by rotary evaporation to obtain a white solid. After post-processing, a white viscous solid is obtained, which is APDD, a nitrogen-phosphorus flame retardant and antibacterial agent with a biguanide structure.

5. A nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric, characterized in that, SiO2-modified cotton fabric is obtained by grafting nano-silica particles onto cotton fabric through hydrolysis and copolymerization reactions, and then grafting the nitrogen-phosphorus flame retardant and antibacterial agent APDD as described in claim 1 onto the SiO2-modified cotton fabric under the catalysis of dicyandiamide.

6. A method for preparing a nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric as described in claim 5, comprising the following steps: Step 1. Preparation of SiO2 modified cotton fabric Dry cotton fabric and nano-silica particles were added to a water / ethanol mixture, and 3-(trimethoxysilyl)propyl methacrylate was added. The mixture was subjected to a hydrolysis reaction for 10-12 hours. After the hydrolysis reaction was completed, the reaction solution and cotton fabric were reacted at 65-75℃ for 2-3 hours. After the reaction was completed, the cotton fabric was removed, washed with deionized water and dried to obtain SiO2 modified cotton fabric, i.e., Co-SiO2. Step 2. Preparation of nitrogen-phosphorus-silicon based flame-retardant and antibacterial cotton fabric APDD modification solution was prepared, dicyandiamide was added as a catalyst, and SiO2 modified cotton fabric was soaked in APDD modification solution at 65-75℃ for 1-2 hours; then it was placed in a high temperature of 165-175℃ for 5-10 minutes, and after being taken out, washed and dried, nitrogen-phosphorus-silicon based flame-retardant and antibacterial cotton fabric, namely Co-SiO2-APDD.

7. The method for preparing nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric according to claim 6, characterized in that, In step one, the mass ratio of the cotton fabric to the nano silica particles and 3-(trimethoxysilyl)propyl methacrylate is 2.7–3.3:0.9–1.1:0.9–1.

1.

8. The method for preparing nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric according to claim 6, characterized in that, The APDD modified liquid in step two is prepared by dissolving the nitrogen-phosphorus flame retardant and antibacterial agent APDD in deionized water at a concentration of 5-15 wt%; the ratio of the SiO2 modified cotton fabric to the APDD modified liquid bath is 1:25-1:

35.

9. The method for preparing nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric according to claim 6, characterized in that, The mass fraction of dicyandiamide in the APDD-modified solution in step two is 5–10 wt%.

10. The application of the nitrogen-phosphorus-silicon-based flame-retardant and antibacterial cotton fabric as described in claim 5 in intimate home textile materials and medical textile materials.

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