A flame-retardant and antibacterial polypropylene meltblown non-woven fabric and its preparation method

Abstract

The present invention relates to the technical field of flame-retardant and antibacterial materials, and particularly relates to a flame-retardant and antibacterial polypropylene melt-blown non-woven fabric and a preparation method thereof. ZIF-8 is impregnated in an aqueous AgNO3 solution, stirred at a temperature of 20-30 °C for 3-10 h, centrifuged and washed with deionized water 3-5 times to remove surface-adsorbed ions. The obtained solid product is calcined in a muffle furnace to obtain an Ag-ZnO composite; 1-8 wt% of the Ag-ZnO composite, 1-8 wt% of IFR and 90-98 wt% of PP are melt-mixed under the operation of a twin-screw extruder, sent to a spinneret through a metering pump, blown out by a blower and then laid into a web, and the Ag-ZnO / IFR / PP melt-blown non-woven fabric is collected. The polypropylene melt-blown non-woven fabric of the present invention has excellent flame-retardant and antibacterial properties. Its limiting oxygen index can be as high as 31.6%, and the vertical burning test can reach V-0 level; the antibacterial rates of this polypropylene melt-blown non-woven fabric against Escherichia coli, Staphylococcus aureus, and Candida albicans can reach more than 99%, and the antibacterial rate still reaches more than 98% after being washed 100 times, showing a long-lasting and high antibacterial efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of flame-retardant and antibacterial materials, and particularly relates to a flame-retardant and antibacterial polypropylene melt-blown non-woven fabric and a preparation method thereof. Background Art

[0002] Due to its excellent mechanical processability, mechanical properties, high heat resistance, high cost performance and recyclability, polypropylene resin is widely used in the manufacture of non-woven fabrics and applied to the fields of medical and health (medical masks, surgical gowns), labor protection and personal protection (dust masks, anti-haze masks, air purifier filters), personal hygiene products (sanitary napkins, diapers, cotton wet wipes), etc.

[0003] As a crystalline thermoplastic material, polypropylene material is widely used in various fields due to its good comprehensive performance. However, since the limiting oxygen index of polypropylene material is as low as 17-18%, it is extremely easy to burn. To solve the above defects, the industry often fills it with flame retardants for modification. In the current industry, when the flame retardant grade of modified polypropylene needs to reach the UL94V0 level, the proportion of flame retardant added is large and the cost is too high. Therefore, in the design of many products with flame retardant requirements, the UL94V2 level is usually used for evaluation and application according to the actual use requirements of the products. At present, there are mainly two methods for filling and modifying V2-grade polypropylene: bromine-antimony synergistic filling flame retardant modification and free radical-induced dripping flame retardant filling modification. For bromine-antimony synergistic flame retardant filling modification, due to the increasingly strict environmental protection requirements and cost problems, its application scope is getting smaller and smaller.

[0004] When polypropylene is used in non-woven fabric products such as civilian masks, due to the repeated contact between the human mouth and nose and the mask, the mask often needs to be discarded after being used once, which not only causes waste of products but also pollutes the environment. By adding antibacterial agents to the non-woven fabric, the generation of bacteria can be inhibited, thereby prolonging the service life of civilian masks. When the mask is sterilized and disinfected with ethanol and reused, the mask is prone to burning, causing potential safety hazards.

[0005] Therefore, it is necessary to develop a polypropylene non-woven fabric with both flame retardant and antibacterial properties. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a flame-retardant and antibacterial polypropylene melt-blown non-woven fabric and a preparation method thereof, and the polypropylene melt-blown non-woven fabric has good flame retardant performance and antibacterial performance.

[0007] The present invention solves the above technical problems through the following technical means:

[0008] The first aspect of the present invention is to provide a flame-retardant and antibacterial polypropylene meltblown non-woven fabric, which comprises the following raw materials: 90-98 wt% of polypropylene, 1-8 wt% of intumescent flame retardant, and 0-8 wt% of Ag-ZnO composite.

[0009] Combined with the first aspect, in some alternative embodiments, the Ag-ZnO composite is mainly made from raw materials ZIF-8 and AgNO3, the mass-volume ratio of ZIF-8 and the AgNO3 aqueous solution is 2:50-100 g / mL, and the concentration of the AgNO3 aqueous solution is 0.1 mol / L.

[0010] Combined with the first aspect, in some alternative embodiments, the intumescent flame retardant comprises the following raw materials: 38-43 wt% of melamine, 38-43 wt% of ammonium polyphosphate, and 18-22 wt% of pentaerythritol ester.

[0011] The second aspect of the present invention is to provide a preparation method of the above-mentioned flame-retardant and antibacterial polypropylene meltblown non-woven fabric, which comprises the following steps:

[0012] Prepare the Ag-ZnO composite. Immerse ZIF-8 in the AgNO3 aqueous solution, stir at a temperature of 20-30 °C for 3-10 h, centrifuge and wash with deionized water 3-5 times to remove surface adsorbed ions. Place the obtained solid product in a muffle furnace for calcination to obtain the Ag-ZnO composite.

[0013] Prepare the Ag-ZnO / IFR / PP meltblown non-woven fabric. After melting and mixing 1-8 wt% of the Ag-ZnO composite, 1-8 wt% of IFR, and 90-98 wt% of PP under the operation of a twin-screw extruder, send it to a spinneret through a metering pump, blow it out through a blower and lay it into a web, and collect the Ag-ZnO / IFR / PP meltblown non-woven fabric.

[0014] Combined with the second aspect, in some alternative embodiments, in the step of preparing the Ag-ZnO composite, the calcination temperature is set at 400-600 °C, and the calcination time is 2-6 h.

[0015] Combined with the second aspect, in some alternative embodiments, the concentration of the AgNO3 aqueous solution is 0.1 mol / L, and the mass-volume ratio of ZIF-8 and the AgNO3 aqueous solution is 2:50-100 g / mL.

[0016] In combination with the second aspect, in some alternative embodiments, the method for preparing ZIF-8 is as follows: Zinc acetate dihydrate is added to a solvent and stirred for 10 to 30 minutes until completely dissolved to obtain a zinc acetate solution. 2-Methylimidazole is added to deionized water and stirred for 10 to 30 minutes until completely dissolved to obtain a methylimidazole solution. Under magnetic stirring, the methylimidazole solution is added to the zinc acetate solution, and then magnetically stirred at 50 to 100 °C for 0.5 to 10.0 hours, followed by standing for 6 to 24 hours. The precipitate is collected and dried at 60 to 100 °C for 6 to 24 hours to obtain ZIF-8.

[0017] In combination with the second aspect, in some alternative embodiments, the molar volume ratio of the zinc acetate dihydrate, 2-methylimidazole, and deionized water is 30 mmol: 60 to 240 mmol: 120 to 600 mL.

[0018] In combination with the second aspect, in some alternative embodiments, the screw rotation speed of the twin-screw extruder is 5 to 30 Hz, and the screw heating temperature is 190 to 240 °C.

[0019] The flame retardant mechanism of the flame retardant and antibacterial polypropylene meltblown nonwoven fabric of the present invention is as follows: (1) Ammonium polyphosphate (APP) decomposes when heated, generating phosphoric acid and pyrophosphoric acid with strong dehydration effects, esterifying pentaerythritol ester (PER), and then dehydrating and carbonizing. The water vapor formed by the reaction and the ammonia gas decomposed from melamine (MA) cause the carbon layer to expand, forming a multi-porous carbon layer that isolates air and heat conduction, thereby achieving the purpose of flame retardancy. (2) The addition of ZnO improves the thermal stability of the flame retardant polypropylene (PP), forming a more stable and dense protective layer, thereby further improving the flame retardant effect of PP. The antibacterial mechanism of the flame retardant and antibacterial polypropylene meltblown nonwoven fabric of the present invention is as follows: (1) The Zn 2+ and continuously and stably released Ag + ions bind to negatively charged bacteria through Coulomb force, penetrate the cell membrane and enter the interior of the bacteria to denature and inactivate proteins, resulting in apoptosis of the cells; (2) ZnO is excited to generate electron-hole pairs, which react with water, O2, and OH - in the air to generate superoxide radicals (O2 - ·) and hydroxyl radicals (·OH) with strong chemical activity. O2 - · and ·OH directly attack the unsaturated double bonds and amide groups of proteins in the cell membrane and cell wall of bacteria, destroying the integrity of the bacterial cells and causing them to lyse and die.

[0020] The present invention synthesizes ZIF-8 in an aqueous phase of pure water, which is environmentally friendly, non-toxic, and does not produce other harmful products, and can be mass-produced; the flame-retardant and antibacterial polypropylene meltblown non-woven fabric of the present invention has excellent flame-retardant performance, and its limiting oxygen index can be as high as 31.6%, and the vertical burning test can reach V-0 level; the flame-retardant and antibacterial polypropylene meltblown non-woven fabric of the present invention has excellent antibacterial performance, and the antibacterial rate against Escherichia coli, Staphylococcus aureus, and Candida albicans can reach more than 99%, and the antibacterial rate still reaches more than 98% after 100 washes, showing a persistent and efficient antibacterial efficiency. The ZnO-Ag hybridization in the present invention can maintain or even promote the original antibacterial effect of nano-silver and reduce the harm caused by excessive release of Ag + ions. Description of the Drawings

[0021] Figure 1 is the vertical burning test process of the flame-retardant and antibacterial polypropylene meltblown non-woven fabric prepared in Example 1;

[0022] Figure 2 is the vertical burning test process of the flame-retardant and antibacterial polypropylene meltblown non-woven fabric prepared in Example 2;

[0023] Figure 3 is the vertical burning test process of the flame-retardant and antibacterial polypropylene meltblown non-woven fabric prepared in Example 3;

[0024] Figure 4 is the statistical chart of the limiting oxygen index LOI;

[0025] Figure 5 is the comparison chart of the antibacterial zones of pure PP and the flame-retardant and antibacterial polypropylene meltblown non-woven fabrics prepared in Examples 1-3. Detailed Embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] For those not specified in the following embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For those raw materials, equipment or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0028] In this application, ZIF-8 is synthesized in an aqueous system. Using ZIF-8 as a precursor, it is impregnated in a silver nitrate solution and then prepared into an Ag-ZnO hybrid cage through high-temperature calcination. Then, it is used as a flame retardant synergist and antibacterial agent and added to polypropylene together with IFR to obtain an Ag-ZnO / IFR / PP meltblown nonwoven fabric. Zinc oxide (ZnO) is a typical N-type semiconductor. Under light illumination, it will be excited to generate electron-hole pairs, which have a killing function on microorganisms such as bacteria, and at the same time have good human biocompatibility and rich and adjustable sizes and morphologies. In addition, ZnO can promote carbon formation in the flame retardant system, improve the thermal stability of the expanded carbon layer formed by the combustion of the composite material, and generate a denser expanded carbon layer, thereby improving the flame retardant performance of the polymer. The intumescent flame retardant (IFR) is an environmentally friendly flame retardant, mainly composed of three parts: a charring agent (carbon source), a charring catalyst (acid source), and an expanding agent (gas source). When IFR is heated, the charring agent dehydrates to form carbon under the action of the charring catalyst, and the carbide forms a fluffy, porous and closed carbon layer under the action of the gas decomposed by the expanding agent, preventing gas diffusion, thereby causing the polymer to self-extinguish.

[0029] The preparation method of the flame retardant and antibacterial polypropylene meltblown nonwoven fabric of this application includes the following steps:

[0030] Prepare ZIF-8. Add zinc acetate dihydrate to a solvent and stir for 10 - 30 min until completely dissolved to obtain a zinc acetate solution. Add 2-methylimidazole to deionized water and stir for 10 - 30 min until completely dissolved to obtain a 2-methylimidazole solution. Under magnetic stirring, add the 2-methylimidazole solution to the zinc acetate solution, then magnetically stir at 50 - 100 °C for 0.5 - 10.0 h, then let it stand for 6 - 24 h, collect the precipitate and dry it at 60 - 100 °C for 6 - 24 h to obtain ZIF-8. Among them, the molar volume ratio of zinc acetate dihydrate, 2-methylimidazole, and deionized water is 30:60 - 240:120 - 600 mmol / mmol / mL.

[0031] Prepare the Ag-ZnO composite. Immerse ZIF-8 in an aqueous AgNO3 solution, stir at a temperature of 20 - 30 °C for 3 - 10 h, centrifuge and wash with deionized water 3 - 5 times. Place the obtained solid product in a muffle furnace for calcination. The calcination temperature is set at 400 - 600 °C, and the calcination time is 2 - 6 h to obtain the Ag-ZnO composite. Among them, the concentration of the aqueous AgNO3 solution is 0.1 mol / L, and the mass-volume ratio of the ZIF-8 and the aqueous AgNO3 solution is 2:50 - 100 g / mL.

[0032] To prepare Ag-ZnO / IFR / PP meltblown nonwoven fabric, 1-8 wt% Ag-ZnO composite, 1-8 wt% IFR and 90-98 wt% PP are melt-mixed under the operation of a twin-screw extruder, then sent to a spinneret through a metering pump, and blown out by a blower and laid into a web, and the Ag-ZnO / IFR / PP meltblown nonwoven fabric is collected.

[0033] The preparation method of the flame-retardant and antibacterial polypropylene meltblown nonwoven fabric of the present application is described in detail through Examples 1-5:

[0034] Example 1

[0035] The preparation method of the flame-retardant and antibacterial polypropylene meltblown nonwoven fabric in this example is as follows:

[0036] (1) Preparation of ZIF-8: 6.59 g of zinc acetate dihydrate is added to 50 mL of a solvent and stirred for 20 min until completely dissolved, denoted as the zinc acetate solution; 19.8 g of 2-methylimidazole is added to 75 mL of deionized water and stirred for 30 min until completely dissolved, denoted as the methylimidazole solution. The methylimidazole solution is added to the zinc acetate solution under magnetic stirring. Then, it is magnetically stirred at 60 °C for 6 h and then left to stand for 12 h, and the precipitate is collected and dried at 80 °C for 8 h.

[0037] (2) Synthesis of Ag-ZnO hybrid cages: 3.0 g of ZIF-8 is impregnated in 80 mL of an aqueous AgNO3 solution (0.1 M) and stirred at 25 °C for 6 h. Then, the AgNO3-impregnated ZIF-8 is centrifuged and washed 3 times with deionized water to remove surface-adsorbed ions. Finally, the product is transferred to a muffle furnace and calcined at 500 °C for 5 h to obtain the Ag-ZnO product.

[0038] (3) Preparation of Ag-ZnO / IFR / PP meltblown nonwoven fabric: 2 wt% Ag-ZnO, 4 wt% IFR and 94 wt% PP are melt-mixed under the operation of a twin-screw extruder, then sent to a spinneret through a metering pump, and blown out by a blower and laid into a web, and the Ag-ZnO / IFR / PP flame-retardant and antibacterial meltblown nonwoven fabric is collected. In this step, the screw speed is 10 Hz, and the screw heating temperature is 190-240 °C.

[0039] The intumescent flame retardant in this example includes the following raw materials: 40 wt% melamine, 40 wt% ammonium polyphosphate, and 20 wt% pentaerythritol ester.

[0040] Example 2

[0041] (1) Synthesis of ZIF-8: 9.89 g of zinc acetate dihydrate was added to 75 mL of solvent and stirred for 20 min until completely dissolved, denoted as zinc acetate solution; 29.7 g of 2-methylimidazole was added to 225 mL of deionized water and stirred for 30 min until completely dissolved, denoted as methylimidazole solution. The methylimidazole solution was added to the zinc acetate solution under magnetic stirring. Then, it was magnetically stirred at 60 °C for 6 h and left to stand for 12 h. The precipitate was collected and dried at 80 °C for 8 h.

[0042] (2) Synthesis of Ag-ZnO hybrid cages: 4.5 g of ZIF-8 was impregnated in 120 mL of aqueous AgNO3 solution (0.1 M) and stirred at 25 °C for 6 h. Then, the AgNO3-impregnated ZIF-8 was centrifuged and washed 3 times with deionized water to remove surface-adsorbed ions. Finally, the product was transferred to a muffle furnace and calcined at 500 °C for 5 h to obtain the Ag-ZnO product.

[0043] (3) Preparation of Ag-ZnO / IFR / PP meltblown nonwoven fabric: 3 wt% of Ag-ZnO, 3 wt% of IFR, and 94 wt% of PP were melt-mixed under the operation of a twin-screw extruder and then sent to a spinneret through a metering pump. After being blown out by a blower, they were laid into a web, and the Ag-ZnO / IFR / PP flame-retardant and antibacterial meltblown nonwoven fabric was collected. In this step, the screw speed was 10 Hz, and the screw heating temperature was 190 - 240 °C.

[0044] The intumescent flame retardant of this example comprises the following raw materials: 40 wt% of melamine, 40 wt% of ammonium polyphosphate, and 20 wt% of pentaerythritol ester.

[0045] Example 3

[0046] (1) Synthesis of ZIF-8: 13.17 g of zinc acetate dihydrate was added to 100 mL of solvent and stirred for 20 min until completely dissolved, denoted as zinc acetate solution; 39.6 g of 2-methylimidazole was added to 300 mL of deionized water and stirred for 30 min until completely dissolved, denoted as methylimidazole solution. The methylimidazole solution was added to the zinc acetate solution under magnetic stirring. Then, it was magnetically stirred at 60 °C for 6 h and left to stand for 12 h. The precipitate was collected and dried at 80 °C for 8 h.

[0047] (2) Synthesis of Ag-ZnO hybrid cages: 6.0 g of ZIF-8 was impregnated in 160 mL of aqueous AgNO3 solution (0.1 M) and stirred at 25 °C for 6 h. Then, the AgNO3-impregnated ZIF-8 was centrifuged and washed 3 times with deionized water to remove surface-adsorbed ions. Finally, the product was transferred to a muffle furnace and calcined at 500 °C for 5 h to obtain the Ag-ZnO product.

[0048] (3) Preparation of Ag-ZnO / IFR / PP meltblown nonwoven fabric: 4 wt% Ag-ZnO, 2 wt% IFR, and 94 wt% PP were melt-mixed under the operation of a twin-screw extruder and then sent to a spinneret through a metering pump. After being blown out by a blower, they were laid into a web, and the Ag-ZnO / IFR / PP flame-retardant and antibacterial meltblown nonwoven fabric was collected. In this step, the screw speed was 10 Hz, and the screw heating temperature was 190 - 240 °C.

[0049] The intumescent flame retardant of this example includes the following raw materials: 40 wt% melamine, 40 wt% ammonium polyphosphate, and 20 wt% pentaerythritol ester.

[0050] Example 4

[0051] The preparation method of the flame-retardant and antibacterial polypropylene meltblown nonwoven fabric in this example is as follows:

[0052] (1) Preparation of ZIF-8: 6.59 g of zinc acetate dihydrate was added to 50 mL of a solvent and stirred for 30 min until completely dissolved, denoted as the zinc acetate solution; 19.8 g of 2-methylimidazole was added to 75 mL of deionized water and stirred for 30 min until completely dissolved, denoted as the methylimidazole solution. Under magnetic stirring, the methylimidazole solution was added to the zinc acetate solution. Then, it was magnetically stirred at 100 °C for 0.5 h and then left to stand for 6 h. The precipitate was collected and dried at 100 °C for 6 h.

[0053] (2) Synthesis of Ag-ZnO hybrid cages: 3.0 g of ZIF-8 was impregnated in 80 mL of an aqueous AgNO3 solution (0.1 M) and stirred at 30 °C for 3 h. Then, the AgNO3-impregnated ZIF-8 was centrifuged and washed 4 times with deionized water to remove surface-adsorbed ions. Finally, the product was transferred to a muffle furnace and calcined at 400 °C for 6 h to obtain the Ag-ZnO product.

[0054] (3) Preparation of Ag-ZnO / IFR / PP meltblown nonwoven fabric: 3 wt% Ag-ZnO, 7 wt% IFR, and 90 wt% PP were melt-mixed under the operation of a twin-screw extruder and then sent to a spinneret through a metering pump. After being blown out by a blower, they were laid into a web, and the Ag-ZnO / IFR / PP flame-retardant and antibacterial meltblown nonwoven fabric was collected. In this step, the screw speed was 5 Hz, and the screw heating temperature was 190 - 240 °C.

[0055] The intumescent flame retardant of this example includes the following raw materials: 38 wt% melamine, 40 wt% ammonium polyphosphate, and 22 wt% pentaerythritol ester.

[0056] Example 5

[0057] The preparation method of the flame-retardant and antibacterial polypropylene meltblown nonwoven fabric in this example is as follows:

[0058] (1) Preparation of ZIF-8: 6.59 g of zinc acetate dihydrate was added to 50 mL of solvent and stirred for 10 min until completely dissolved, denoted as zinc acetate solution; 19.8 g of 2-methylimidazole was added to 75 mL of deionized water and stirred for 10 min until completely dissolved, denoted as methylimidazole solution. Under magnetic stirring, the methylimidazole solution was added to the zinc acetate solution. Then, it was magnetically stirred at 50 °C for 10 h and left to stand for 24 h. The precipitate was collected and dried at 60 °C for 24 h.

[0059] (2) Synthesis of Ag-ZnO hybrid cages: 3.0 g of ZIF-8 was impregnated in 80 mL of aqueous AgNO3 solution (0.1 M) and stirred at 20 °C for 10 h. Then, the AgNO3-impregnated ZIF-8 was centrifuged and washed 5 times with deionized water to remove surface-adsorbed ions. Finally, the product was transferred to a muffle furnace and calcined at 600 °C for 2 h to obtain the Ag-ZnO product.

[0060] (3) Preparation of Ag-ZnO / IFR / PP meltblown nonwoven fabric: 1 wt% Ag-ZnO, 1 wt% IFR, and 98 wt% PP were melt-mixed under the operation of a twin-screw extruder and then sent to a spinneret through a metering pump. After being blown out by a blower, it was laid into a web, and the Ag-ZnO / IFR / PP flame-retardant and antibacterial meltblown nonwoven fabric was collected. In this step, the screw speed was 30 Hz, and the screw heating temperature was 190 - 240 °C.

[0061] The intumescent flame retardant of this example includes the following raw materials: 43 wt% of melamine, 38 wt% of ammonium polyphosphate, and 19 wt% of pentaerythritol ester.

[0062] Using pure polypropylene as a control group, the flame retardancy of the flame-retardant and antibacterial polypropylene meltblown nonwoven fabrics prepared in Examples 1 - 3 was tested. Considering that polypropylene shrinks when heated and it is not convenient to directly test the flame retardancy of the meltblown fabric, the polypropylene composite melt was prepared into a spline and tested according to national standards GB / T2046.2 - 2009 and GB / T2048 - 2021. The vertical burning test process is as Figures 1-3 shown, and the oxygen index test results are as Figure 4 shown. It was found that by adding 4 wt% Ag-ZnO and 2 wt% IFR, 3 wt% Ag-ZnO and 3 wt% IFR, and 4 wt% Ag-ZnO and 2 wt% to the polypropylene meltblown nonwoven fabric respectively, the limiting oxygen index (LOI) increased from 18.0% to 31.6%, 30.9%, and 28.5% respectively, and the vertical burning test (UL94) reached V-0, V-0, and V-2 grades respectively.

[0063] The antibacterial properties of the flame-retardant and antibacterial polypropylene meltblown nonwoven fabrics prepared in Examples 1 - 3 were tested, and the flat colony images are as Figure 5As shown, it was found that when the addition amount of Ag-ZnO was 2 wt%, the antibacterial rates against Escherichia coli, Staphylococcus aureus, and Candida albicans could reach over 97%; when the addition amount of Ag-ZnO was 3 wt%, the antibacterial rates against Escherichia coli, Staphylococcus aureus, and Candida albicans could reach over 98%; when the addition amount of Ag-ZnO was 4 wt%, the antibacterial rates against Escherichia coli, Staphylococcus aureus, and Candida albicans could reach over 99%, and the antibacterial rate still reached over 98% after 100 washes, showing a persistent and high antibacterial efficiency.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention. The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. A flame-retardant and antibacterial polypropylene meltblown non-woven fabric, characterized in that, It includes the following raw materials: 90-98 wt% of polypropylene, 1-8 wt% of intumescent flame retardant, and 1-8 wt% of Ag-ZnO composite; A method for preparing a flame-retardant and antibacterial polypropylene meltblown nonwoven fabric, comprising the following steps: Prepare the Ag-ZnO composite. Immerse ZIF-8 in an aqueous AgNO3 solution, stir at a temperature of 20-30 °C for 3-10 h, centrifuge and wash with deionized water 3-5 times. Place the obtained solid product in a muffle furnace for calcination to obtain the Ag-ZnO composite. The mass-volume ratio of the ZIF-8 and the aqueous AgNO3 solution is 2:50-100 g / mL, the concentration of the aqueous AgNO3 solution is 0.1 mol / L, the calcination temperature is set at 400-600 °C, and the calcination time is 2-6 h; Prepare the Ag-ZnO / IFR / PP meltblown nonwoven fabric. After melting and mixing 1-8 wt% of the Ag-ZnO composite, 1-8 wt% of IFR, and 90-98 wt% of PP under the operation of a twin-screw extruder, it is sent to a spinneret through a metering pump, blown out by a blower, and then laid into a web, and the Ag-ZnO / IFR / PP meltblown nonwoven fabric is collected; The intumescent flame retardant includes the following raw materials: 38-43 wt% of melamine, 38-43 wt% of ammonium polyphosphate, and 18-22 wt% of pentaerythritol ester.

2. The flame-retardant and antibacterial polypropylene meltblown non-woven fabric according to claim 1, characterized in that, The preparation method of the ZIF-8 is as follows: Add zinc acetate dihydrate to a solvent and stir for 10-30 min until completely dissolved to obtain a zinc acetate solution. Add 2-methylimidazole to deionized water and stir for 10-30 min until completely dissolved to obtain a methylimidazole solution. Under magnetic stirring, add the methylimidazole solution to the zinc acetate solution, and then magnetically stir at 50-100 °C for 0.5-10.0 h, then let it stand for 6-24 h, collect the precipitate and dry it at 60-100 °C for 6-24 h to obtain ZIF-8.

3. The flame-retardant and antibacterial polypropylene meltblown non-woven fabric according to claim 2, characterized in that, The molar volume ratio of the zinc acetate dihydrate, 2-methylimidazole, and deionized water is 30 mmol:60-240 mmol:120-600 mL.

4. The flame-retardant and antibacterial polypropylene meltblown non-woven fabric according to claim 3, characterized in that, The screw speed of the twin-screw extruder is 5-30 Hz, and the screw heating temperature is 190-240 °C.

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