Nanofiber composite air purification filter material and preparation method therefor

Abstract

The present invention relates to the technical field of air purification, and particularly provides a nanofiber composite air purification filter material and a preparation method therefor. The nanofiber composite air purification filter material comprises a composite structure consisting of four layers arranged from top to bottom, which are respectively a non-woven fabric, a nanofiber membrane layer, a modified melt-blown non-woven fabric and a spunbond non-woven fabric; the non-woven fabric is PET needle-punched non-woven fabric; in parts by weight, the raw materials for preparing the nanofiber membrane layer comprise: 10-20 parts of polylactic acid, 3-5 parts of a reinforcing agent, 2-4 parts of modified nanoparticles and 100-150 parts of a solvent; and the spunbond non-woven fabric is made of PET or PP. The nanofiber composite air purification filter material provided by the present invention has air-permeability, radiation resistance, and antibacterial properties, can be widely applied in the field of air purification filter materials, and has considerable commercial application value.

Description

Nanofiber composite air purification filter material and preparation method thereof Technical Field

[0001] The present invention relates to the field of air purification technology, specifically to the field of air purification filter materials, and in particular to a nanofiber composite air purification filter material and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of industry, my country's air quality problems have become increasingly serious. In particular, environmental issues characterized by PM10 and PM2.5 pollutants have attracted increasing attention. These particulate pollutants not only reduce air visibility but also seriously affect people's health. At the same time, in some indoor environments where humans engage in activities, the air is also filled with particulate matter, formaldehyde, volatile organic compounds, bacteria, pathogens and other substances, which also pose a threat to people's health. In order to purify the air more effectively, air purification technology has received widespread attention. The development of air purification filter materials, which play a major role in air purification, has also become a research hotspot for scientific researchers in recent years.

[0003] Currently, air purification filter materials, such as masks, are mainly composed of multiple layers of non-woven fabrics, but they have problems such as high resistance, low precision, and decreased filtration efficiency. Unlike non-woven fabrics, nanofiber membrane materials have the advantages of small pore size, high porosity, and adjustable structure. However, nanofiber membrane air filter materials have the disadvantages of fragile structure, poor stability, and high cost. Therefore, it is particularly important to combine non-woven fabrics with high strength and good dimensional stability with nanofiber membrane layers with high porosity to prepare new air purification filter materials. However, existing technologies still have some shortcomings that need to be addressed. For example, the nanofiber membrane layer is difficult to composite with the non-woven fabric, resulting in insufficient air permeability of the air purification filter material; the main components of non-woven fabric materials are mostly polymer materials such as PET and PP, which are prone to yellowing and aging under long-term exposure to ultraviolet radiation and other radiation; non-woven fabrics and nanofiber membrane materials themselves do not have bactericidal properties, making them insufficient in filtering bacteria in the air. In addition, during the long-term use of air purification filter materials, bacteria will be adsorbed on their surface, which can also lead to secondary infection problems.

[0004] Patent CN115897293A discloses an antibacterial air filter material and a preparation method thereof. This application loads antibacterial substances on the fiber itself, which enhances the strength of the filter material itself while having high antibacterial properties, but does not address the issue of radiation protection of air filter materials; Patent CN111203116A discloses a washable wide-width air filter composite membrane and a preparation method and application thereof. This application combines support materials and heavy ion microporous membrane materials through ultrasonic compounding, so that the air filter material has good composite mechanical strength and air permeability, but does not solve the problem of low radiation protection and antibacterial properties of air filter materials.

[0005] Therefore, there is an urgent need on the market for an air purification filter material with good air permeability, radiation protection and antibacterial properties. Summary of the Invention

[0006] In response to the problems existing in the prior art, the present invention uses ultrasonic compounding to bond a four-layer structure of non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric and spunbond non-woven fabric from top to bottom to prepare a nanofiber composite air purification filter material, which gives the air purification filter material the advantages of breathability, radiation protection and antibacterial properties.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On one hand, the present invention provides a nanofiber composite air purification filter material, comprising a four-layer composite structure from top to bottom, namely a non-woven fabric, a nanofiber membrane layer, a modified melt-blown non-woven fabric and a spunbond non-woven fabric;

[0009] The non-woven fabric is a PET needle-punched non-woven fabric;

[0010] The raw materials for preparing the nanofiber membrane layer include the following components in parts by weight: 10-20 parts of polylactic acid, 3-5 parts of reinforcing agent, 2-4 parts of modified nanoparticles, and 100-150 parts of solvent;

[0011] The material of the spunbond nonwoven fabric is PET or PP.

[0012] The applicant prepared air purification filter materials by bonding multiple layers of non-woven fabrics and nanofiber membrane layers through ultrasonic compounding. On the one hand, the applicant selected PET needle-punched non-woven fabric as the upper structure, making the air purification filter material strong, durable and low-cost; on the other hand, the applicant selected non-woven fabrics prepared by meltblowing and spunbonding processes as the lower structure, combining the advantages of high strength and good dimensional stability of spunbond non-woven filament fiber web and high fluffiness and good air permeability of meltblown non-woven ultrafine short fiber web; on the other hand, the applicant prepared a nanofiber membrane layer with polylactic acid as the main material as the middle layer. Polylactic acid has good biocompatibility and can be well combined with the multi-layer non-woven fabric structure under the action of ultrasonic compounding, thereby enhancing the adsorption of the air purification filter material to nano-scale harmful particles.

[0013] In some embodiments of the present invention, the polylactic acid in the nanofiber membrane layer is L-polylactic acid; and the reinforcing agent is a β-type nucleating agent.

[0014] Preferably, the molecular weight of the L-polylactic acid is 90,000-110,000; and the β-type nucleating agent is a rare earth β-nucleating agent.

[0015] More preferably, the model of the rare earth β-nucleating agent is WBG-II.

[0016] The present invention does not impose any special restrictions on the source of the WBG-II, which can be purchased commercially, including but not limited to Guangdong Weilinna Functional Materials Co., Ltd.

[0017] Polylactic acid is a good biodegradable material with the advantages of being environmentally friendly, breathable, lightweight, having good resilience and gloss. The applicant selected L-polylactic acid, which has a wide source of raw materials, good mechanical properties and molding processability, and selected a rare earth β-nucleating agent as the nucleating agent of polylactic acid, which can overcome the problems of poor impact performance and low heat deformation temperature of polylactic acid.

[0018] In some embodiments of the present invention, the method for preparing the modified nanoparticles comprises the following steps:

[0019] ① Add TiO2 powder to sodium hydroxide solution, place in a sealed polytetrafluoroethylene reactor after ultrasonic treatment, dry, wash, bake, and grind to obtain a precursor for use;

[0020] ② Take the precursor in step ①, add barium nitrate and deionized water, ultrasonicate, seal in a polytetrafluoroethylene reactor, heat, wash, dry, and grind to obtain nanoparticles for later use;

[0021] ③ 1-(3-aminopropyl)imidazole, tea polyphenols, isopropyl alcohol and deionized water are sequentially added to the nanoparticles obtained in step ②, and the mixture is heated, stirred, dried and ground to obtain modified nanoparticles.

[0022] Preferably, the method for preparing the modified nanoparticles comprises the following steps:

[0023] ① Add TiO2 powder to sodium hydroxide solution, ultrasonicate for 20-40 minutes, seal in a polytetrafluoroethylene reactor, dry at 200℃ for 12 hours, wash three times with anhydrous ethanol and deionized water, dry at 60℃ for 4 hours, and grind to obtain the precursor for use;

[0024] ② Take the precursor prepared in step ①, add barium nitrate and deionized water, sonicate for 30 minutes, seal in a polytetrafluoroethylene reactor, heat at 200°C for 10 hours, wash three times with anhydrous ethanol and three times with deionized water, dry at 60°C for 4 hours, and grind to obtain nanoparticles for later use;

[0025] ③ 1-(3-aminopropyl)imidazole, tea polyphenols, isopropyl alcohol and deionized water were added to the nanoparticles obtained in step ② in sequence, heated at 40-50°C, stirred for 20-40 minutes, dried at 60°C for 4 hours, and ground to obtain modified nanoparticles.

[0026] Wherein, the particle size of TiO2 powder is 20-40nm.

[0027] The present invention does not impose any special restrictions on the source of the TiO2 powder, which can be purchased commercially, including but not limited to Shanghai Aladdin Biochemical Technology Co., Ltd.

[0028] In some embodiments of the present invention, in step ③, the mass ratio of the nanoparticles obtained in step ②, 1-(3-aminopropyl)imidazole and tea polyphenols is 1:(0.3-0.5):(0.15-0.35).

[0029] Preferably, in step ③, the mass ratio of the nanoparticles obtained in step ②, 1-(3-aminopropyl)imidazole and tea polyphenols is 1:0.4:0.25.

[0030] Compared with ordinary non-woven fabrics, nanofiber membranes have smaller pores and higher filtration efficiency, especially can increase the filtration efficiency of nano-scale particles. Among them, polylactic acid, as an environmentally friendly biodegradable material, has the advantages of light weight, good air permeability, and good resilience, but it has the disadvantages of insufficient strength and insufficient antibacterial properties. The applicant modified TiO2 powder to prepare modified nanoparticles to optimize the performance of polylactic acid nanofiber membranes. On the one hand, the applicant prepared highly active BaTiO3 nanoparticles from TiO2 powder through a two-step hydrothermal method. BaTiO3 nanoparticles can be in situ embedded in the surface of polylactic acid, overcoming the problem of poor dispersion of TiO2 powder in polylactic acid, making polylactic acid nanofiber membranes have better Antibacterial properties, and the embedding of BaTiO3 nanoparticles on the surface of polylactic acid improves the overall crystallinity of the nanofiber membrane, thereby enhancing the interaction between molecules and improving the strength of the polylactic acid nanofiber membrane; on the other hand, the applicant introduced 1-(3-aminopropyl)imidazole and tea polyphenols into BaTiO3 nanoparticles. After 1-(3-aminopropyl)imidazole was introduced into polylactic acid via BaTiO3 nanoparticles, imidazole and amide groups appeared on the surface of polylactic acid. The imidazole group can enhance the radiation protection performance of the nanofiber membrane, and the amide group can form hydrogen bonds with the polylactic acid molecules, accelerate the nucleation rate of polylactic acid, save the amount of nucleating agent, and save costs. Tea polyphenols, as a natural substance, can enhance the radiation protection of the nanofiber membrane layer.

[0031] In some embodiments of the present invention, the solvent is polyethylene glycol or dichloromethane.

[0032] Preferably, the solvent is polyethylene glycol with a molecular weight of 400-600.

[0033] In some embodiments of the present invention, the method for preparing the nanofiber membrane layer comprises the following steps:

[0034] Polylactic acid, reinforcing agent and modified nanoparticles are mixed in a solvent, allowed to stand at 40-50°C for 4-6 hours, stirred to obtain a blended solution, and then subjected to electrostatic spinning to obtain a nanofiber membrane layer.

[0035] In some embodiments of the present invention, the method for preparing the modified meltblown nonwoven fabric comprises the following steps:

[0036] (1) Add concentrated hydrochloric acid and deionized water to a reaction vessel, add samarium oxide powder in batches, heat to 45-55°C, stir, filter, add ammonia water to adjust the pH to 7.5-8.5, filter, wash, filter, and dry to obtain reaction product 1 for later use;

[0037] (2) Take the reaction product 1 in step (1), add methacrylic acid, heat to 75-85°C, stir until the solution becomes clear, filter, distill under reduced pressure, cool, filter, and dry to obtain the reaction product 2 for use;

[0038] (3) mixing the reaction product 2 in step (2), polyethylene masterbatch, and polypropylene masterbatch, drying them under vacuum, and then extruding and melt-spinning them to obtain composite fibers for later use;

[0039] (4) Ferrous sulfate, deionized water, and N-isopropylacrylamide are placed in a reaction kettle, mixed, and then the composite fiber of step (3) is added, an inert gas is passed through for 8-15 minutes, heated at 65-75°C for 2-4 hours, washed under ultraviolet light, and dried to obtain a mixture for use;

[0040] (5) The mixture obtained in step (4) is subjected to a melt-blown process to obtain a modified melt-blown non-woven fabric.

[0041] Preferably, the preparation method of the modified meltblown nonwoven fabric comprises the following steps:

[0042] (1) Concentrated hydrochloric acid and deionized water were added to a reaction vessel, samarium oxide powder was added in batches, heated to 50°C, stirred for 20-40 minutes, filtered, 25 wt% ammonia water was added to adjust the pH to 8.0, filtered, washed three times with deionized water, filtered, and dried at 100°C for 12 hours to obtain reaction product 1 for later use;

[0043] (2) Take the reaction product 1 in step (1), add methacrylic acid, heat to 80°C, stir until the solution becomes clear, filter, distill under reduced pressure, cool to room temperature, filter, and dry at 100°C for 12 hours to obtain the reaction product 2 for use;

[0044] (3) The reaction product 2 in step (2), polyethylene masterbatch, and polypropylene masterbatch are mixed, dried under a vacuum environment at 100° C. for 12 hours, and then subjected to extrusion and melt spinning processes to obtain a composite fiber for standby use;

[0045] (4) Ferrous sulfate, deionized water, and N-isopropylacrylamide were placed in a reaction kettle, mixed, and then the composite fiber of step (3) was added, nitrogen was passed through for 10 minutes, heated at 70°C for 3 hours, and washed three times with deionized water under ultraviolet light of 220-260 nm. The mixture was dried at 60°C for 4 hours to obtain a mixture for use;

[0046] (5) The mixture obtained in step (4) is subjected to a melt-blown process to obtain a modified melt-blown non-woven fabric.

[0047] Among them, the molecular weight of polyethylene masterbatch is 80,000-100,000; the molecular weight of polypropylene masterbatch is 100,000-110,000.

[0048] In some embodiments of the present invention, in step (3), the mass ratio of the reaction product 2, polyethylene masterbatch and polypropylene masterbatch in step (2) is 1: (3-5): (7-9); in step (4), the mass ratio of the composite fiber in step (3) and N-isopropylacrylamide is 1: (0.15-0.25).

[0049] Preferably, in step (3), the mass ratio of the reaction product 2, polyethylene masterbatch and polypropylene masterbatch in step (2) is 1:4:8; and in step (4), the mass ratio of the composite fiber in step (3) and N-isopropylacrylamide is 1:0.2.

[0050] The present invention does not impose any special restrictions on the source of the polyethylene masterbatch, which can be purchased commercially, including but not limited to Dongguan Yili Plastic Co., Ltd.; the present invention does not impose any special restrictions on the source of the polypropylene masterbatch, which can be purchased commercially, including but not limited to Shenzhen Jindaquan Technology Co., Ltd.

[0051] Meltblown nonwoven fabric is a nonwoven material made of polymer materials through the meltblowing process. Among them, two-component meltblown nonwoven fabric is favored by people because it can make up for the shortcomings of single polymer performance. On the one hand, the applicant uses polyethylene masterbatch and polypropylene masterbatch as the main components to prepare two-component meltblown nonwoven fabric. Polypropylene has the advantages of flame retardancy and high temperature resistance, but its air permeability is poor and it is not resistant to radiation. Compared with polypropylene, the molecular chain structure of polyethylene is more dispersed and loose, so it has the characteristics of good air permeability and comfortable and soft wearing. Furthermore, after absorbing radiation, polyethylene will undergo a photocrosslinking reaction in its structure, thereby improving the radiation resistance of the meltblown nonwoven fabric. Furthermore, polyethylene uses its hydrophobic properties to prevent water droplets from staying on the surface of the nonwoven fabric, thereby achieving an anti-fog effect; on the one hand, the applicant adds radiation-resistant oxidizing agents to the meltblown nonwoven fabric. Samarium powder is prepared by modifying the samarium oxide powder. The unsaturated reactive groups in the samarium methacrylate make it easier for it to undergo an in-situ volume expansion reaction with polypropylene, so that the samarium oxide powder and the melt-blown non-woven fabric are more tightly bonded, which is beneficial to improving the radiation protection performance of the air purification filter material. On the other hand, the applicant introduces temperature-sensitive N-isopropylacrylamide into the composite fiber. As the reaction temperature increases, N-isopropylacrylamide can be transformed from hydrophilic to hydrophobic, which can effectively filter small molecular oil droplets on the surface of the non-woven fabric, and the reaction between the amide bond and the acrylic acid bond of the samarium methacrylate can promote the grafting of N-isopropylacrylamide in the composite fiber. The ferrous ions in the ferrous sulfate can also play a certain antioxidant role in the synthesis process of the melt-blown non-woven fabric, thereby enhancing the radiation protection of the air purification filter material.

[0052] Another aspect of the present invention further provides a method for preparing the nanofiber composite air purification filter material described in the above technical solution, comprising the following steps:

[0053] S1, stacking four layers of materials, including non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric and spunbond non-woven fabric, from top to bottom;

[0054] S2. The four layers of materials stacked together in step S1 are bonded and formed by ultrasonic compounding to obtain a nanofiber composite air purification filter material.

[0055] In some embodiments of the present invention, the power of the ultrasonic compounding is 400-600 kW, and the ultrasonic frequency is 90-110 Hz.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] (1) The present invention prepares a nanofiber composite air purification filter material with breathable, radiation-proof and antibacterial properties by bonding a four-layer structure of non-woven fabric, nanofiber membrane layer, modified melt-blown non-woven fabric and spunbond non-woven fabric from top to bottom through ultrasonic bonding.

[0058] (2) The present invention uses polylactic acid as the main component, adds a reinforcing agent, modified nanoparticles and a solvent to prepare and synthesize a nanofiber membrane layer, so that the nanofiber membrane layer has high strength, antibacterial and radiation protection properties.

[0059] (3) The present invention uses polypropylene and polyethylene masterbatch as the main polymer components of the two-component melt-blown non-woven fabric, adds samarium oxide powder with radiation protection and N-isopropylacrylamide with temperature sensitivity to prepare a synthetic modified melt-blown non-woven fabric, so that the modified melt-blown non-woven fabric has good air permeability, radiation protection and anti-fog properties.

[0060] (4) The air purification filter material prepared by the present invention has good air permeability, radiation protection and antibacterial properties, can be widely used in the field of air purification filter materials, and has good commercial application value. DETAILED DESCRIPTION

[0061] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0062] In the following examples, except for the modified nanoparticles and modified meltblown non-woven fabrics, the remaining compound monomers and related reagents used can be purchased from the market. Among them, PET needle-punched non-woven fabrics and PET spunbond non-woven fabrics were purchased from Jiangxi Haorui Industrial Materials Co., Ltd.; polylactic acid is L-polylactic acid with an average molecular weight of 100,000; the reinforcing agent is a rare earth β-nucleating agent, model WBG-II, purchased from Guangdong Weilinna Functional Materials Co., Ltd.; the average particle size of TiO2 powder is 30 nm, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; the average molecular weight of polyethylene masterbatch is 90,000, purchased from Dongguan Yili Plastic Co., Ltd.; the average molecular weight of polypropylene masterbatch is 105,000, purchased from Shenzhen Jindaquan Technology Co., Ltd.; polyethylene glycol is purchased from Tianjin Daixu Chemical Trading Co., Ltd., with molecular weights of 400, 500 and 600.

[0063] Preparation Example 1

[0064] The synthesis method of modified nanoparticles A comprises the following steps:

[0065] ① Add 30g TiO2 powder to 100ml 8mol / L sodium hydroxide solution, ultrasonicate for 30min, seal in a polytetrafluoroethylene reactor, dry at 200℃ for 12h, wash three times with anhydrous ethanol and deionized water, dry at 60℃ for 4h, and grind to obtain the precursor for use;

[0066] ② Take 10g of the precursor from step ①, add 22g of barium nitrate and 50ml of deionized water, sonicate for 30min, then seal in a polytetrafluoroethylene reactor, heat at 200°C for 10h, wash three times with anhydrous ethanol and three times with deionized water, dry at 60°C for 4h, and grind to obtain nanoparticles for later use;

[0067] ③ Add 8 g of 1-(3-aminopropyl)imidazole, 5 g of tea polyphenols, 15 ml of isopropanol and 40 ml of deionized water in sequence to 20 g of the nanoparticles obtained in step ②, heat at 45°C, stir for 30 min, dry at 60°C for 4 h, and grind to obtain modified nanoparticles A.

[0068] Preparation Example 2

[0069] Modified nanoparticles B were synthesized using the same method as modified nanoparticles A. The raw materials used and the content of each raw material were basically the same as those of modified nanoparticles A. The difference was that in step ③, the masses of 1-(3-aminopropyl)imidazole and tea polyphenols were replaced with 5 g and 2.4 g, respectively.

[0070] Preparation Example 3

[0071] The synthesis method of modified melt-blown nonwoven fabric A comprises the following steps:

[0072] (1) Add 50 ml of 38 wt% concentrated hydrochloric acid and 100 ml of deionized water to a reaction vessel, add 30 g of samarium oxide powder in batches, heat to 50°C, stir for 30 min, filter with suction, add 25 wt% ammonia water to adjust the pH to 8.0, filter with suction, wash three times with deionized water, filter, and dry at 100°C for 12 h to obtain reaction product 1 for use;

[0073] (2) Take 20 g of the reaction product 1 in step (1), add 40 g of methacrylic acid, heat to 80 ° C, stir until the solution becomes clear, filter, distill under reduced pressure, cool to room temperature, filter, and dry at 100 ° C for 12 h to obtain reaction product 2 for use;

[0074] (3) 10 g of the reaction product 2 in step (2), 40 g of polyethylene masterbatch, and 80 g of polypropylene masterbatch were mixed, dried at 100 ° C in a vacuum environment for 12 h, and then extruded and melt-spun to obtain a composite fiber for use;

[0075] (4) 10 g of ferrous sulfate, 100 ml of deionized water, and 8 g of N-isopropylacrylamide were placed in a reaction kettle, mixed, and then 40 g of the composite fiber prepared in step (3) was added. The mixture was passed through nitrogen for 10 min, heated at 70°C for 3 h, and washed three times with deionized water under 240 nm ultraviolet light. The mixture was dried at 60°C for 4 h to obtain a mixture for use.

[0076] (5) The mixture obtained in step (4) is subjected to a melt-blown process to obtain a modified melt-blown non-woven fabric A.

[0077] Preparation Example 4

[0078] The modified meltblown nonwoven fabric B was synthesized by the same method as the modified meltblown nonwoven fabric A. The raw materials used and the content of each raw material were basically the same as those of the modified meltblown nonwoven fabric A. The difference was that in step (3), the masses of the polyethylene masterbatch and the polypropylene masterbatch were replaced by 25 g and 65 g, respectively.

[0079] Preparation Example 5

[0080] Modified melt-blown non-woven fabric C was synthesized in the same manner as modified melt-blown non-woven fabric A. The raw materials used and the content of each raw material were basically the same as those of modified melt-blown non-woven fabric A, with the difference that in step (4), the mass of N-isopropylacrylamide was replaced by 4.5 g. Example 1

[0081] A nanofiber composite air purification filter material includes a four-layer composite structure from top to bottom, namely a non-woven fabric, a nanofiber membrane layer, a modified melt-blown non-woven fabric A and a spunbond non-woven fabric.

[0082] Among them, the thicknesses of the non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A, and spunbond non-woven fabric are 50 μm, 0.3 μm, 40 μm, and 20 μm, respectively;

[0083] The non-woven fabric is a PET needle-punched non-woven fabric;

[0084] The nanofiber membrane layer comprises the following raw materials in parts by weight: 15 parts of polylactic acid, 4 parts of reinforcing agent, 3 parts of modified nanoparticles A, and 125 parts of solvent;

[0085] The material of the spunbond nonwoven fabric is PET spunbond nonwoven fabric,

[0086] Wherein, the solvent is polyethylene glycol with a molecular weight of 500;

[0087] The method for preparing the nanofiber membrane layer comprises the following steps:

[0088] Polylactic acid, reinforcing agent and modified nanoparticles are mixed in a solvent, allowed to stand at 45°C for 5 hours, and stirred to obtain a blended solution, which is then electrospun to obtain a nanofiber membrane layer.

[0089] The preparation method of the nanofiber composite air purification filter material in this embodiment includes the following steps:

[0090] S1. Stacking the four layers of non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A and spunbond non-woven fabric together from top to bottom;

[0091] S2, bonding the four layers of materials stacked together in step S1 by ultrasonic compounding to form a nanofiber composite air purification filter material.

[0092] The power of ultrasonic compounding is 500kw and the ultrasonic frequency is 100Hz. Example 2

[0093] A nanofiber composite air purification filter material includes a four-layer composite structure from top to bottom, namely a non-woven fabric, a nanofiber membrane layer, a modified melt-blown non-woven fabric A and a spunbond non-woven fabric.

[0094] The thickness of the non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A and spunbond non-woven fabric are the same as those in Example 1;

[0095] The non-woven fabric is a PET needle-punched non-woven fabric;

[0096] The nanofiber membrane layer comprises the following raw materials in parts by weight: 10 parts of polylactic acid, 3 parts of reinforcing agent, 3 parts of modified nanoparticles A, and 100 parts of solvent;

[0097] The material of the spunbond nonwoven fabric is PET spunbond nonwoven fabric,

[0098] Wherein, the solvent is polyethylene glycol with a molecular weight of 400;

[0099] The method for preparing the nanofiber membrane layer comprises the following steps:

[0100] Polylactic acid, reinforcing agent and modified nanoparticles are mixed in a solvent, allowed to stand at 40°C for 4 hours, stirred to obtain a blend solution, and then subjected to electrostatic spinning to obtain a nanofiber membrane layer.

[0101] The preparation method of the nanofiber composite air purification filter material in this embodiment includes the following steps:

[0102] S1. Stacking the four layers of non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A and spunbond non-woven fabric together from top to bottom;

[0103] S2, bonding the four layers of materials stacked together in step S1 by ultrasonic compounding to form a nanofiber composite air purification filter material.

[0104] The power of ultrasonic compounding is 400kw and the ultrasonic frequency is 90Hz. Example 3

[0105] A nanofiber composite air purification filter material includes a four-layer composite structure from top to bottom, namely a non-woven fabric, a nanofiber membrane layer, a modified melt-blown non-woven fabric A and a spunbond non-woven fabric.

[0106] The thickness of the non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A and spunbond non-woven fabric are the same as those in Example 1;

[0107] The non-woven fabric is a PET needle-punched non-woven fabric;

[0108] The nanofiber membrane layer comprises the following raw materials in parts by weight: 20 parts of polylactic acid, 5 parts of reinforcing agent, 3 parts of modified nanoparticles A, and 150 parts of solvent;

[0109] The material of the spunbond nonwoven fabric is PET spunbond nonwoven fabric,

[0110] Among them, the solvent is polyethylene glycol with a molecular weight of 600;

[0111] The method for preparing the nanofiber membrane layer comprises the following steps:

[0112] Polylactic acid, reinforcing agent and modified nanoparticles are mixed in a solvent, allowed to stand at 50°C for 6 hours, and stirred to obtain a blended solution, which is then electrospun to obtain a nanofiber membrane layer.

[0113] The preparation method of the nanofiber composite air purification filter material in this embodiment includes the following steps:

[0114] S1. Stacking the four layers of non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A and spunbond non-woven fabric together from top to bottom;

[0115] S2, bonding the four layers of materials stacked together in step S1 by ultrasonic compounding to form a nanofiber composite air purification filter material.

[0116] The power of ultrasonic compounding is 600kw and the ultrasonic frequency is 110Hz. Example 4

[0117] A nanofiber composite air purification filter material includes a four-layer composite structure from top to bottom, namely a non-woven fabric, a nanofiber membrane layer, a modified melt-blown non-woven fabric A and a spunbond non-woven fabric.

[0118] The thickness of the non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A and spunbond non-woven fabric are the same as those in Example 1;

[0119] The non-woven fabric is a PET needle-punched non-woven fabric;

[0120] The nanofiber membrane layer comprises the following raw materials in parts by weight: 12 parts of polylactic acid, 3.5 parts of reinforcing agent, 2 parts of modified nanoparticles A, and 120 parts of solvent;

[0121] The material of the spunbond nonwoven fabric is PET spunbond nonwoven fabric,

[0122] Wherein, the solvent is polyethylene glycol with a molecular weight of 500;

[0123] The preparation method of the nanofiber membrane layer and the nanofiber composite air purification filter material in this embodiment is the same as that in Example 1. Example 5

[0124] A nanofiber composite air purification filter material includes a four-layer composite structure from top to bottom, namely a non-woven fabric, a nanofiber membrane layer, a modified melt-blown non-woven fabric A and a spunbond non-woven fabric.

[0125] The thickness of the non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric A and spunbond non-woven fabric are the same as those in Example 1;

[0126] The non-woven fabric is a PET needle-punched non-woven fabric;

[0127] The nanofiber membrane layer comprises the following raw materials in parts by weight: 18 parts of polylactic acid, 4.5 parts of reinforcing agent, 4 parts of modified nanoparticles A, and 140 parts of solvent;

[0128] The material of the spunbond nonwoven fabric is PET spunbond nonwoven fabric,

[0129] Wherein, the solvent is polyethylene glycol with a molecular weight of 500;

[0130] The preparation method of the nanofiber membrane layer and the nanofiber composite air purification filter material in this embodiment is the same as that in Example 1. Example 6

[0131] The present invention provides a nanofiber composite air purification filter material and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the modified nanoparticles B are used to replace the modified nanoparticles A in equal amounts. Example 7

[0132] The present invention provides a nanofiber composite air purification filter material and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the modified meltblown non-woven fabric B replaces the modified meltblown non-woven fabric A in equal amounts. Example 8

[0133] The present invention provides a nanofiber composite air purification filter material and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the modified meltblown non-woven fabric C replaces the modified meltblown non-woven fabric A in equal amounts.

[0134] Comparative Example 1

[0135] This comparative example provides a nanofiber composite air purification filter material and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that TiO2 powder is used instead of modified nanoparticles A.

[0136] Comparative Example 2

[0137] This comparative example provides a nanofiber composite air purification filter material and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that commercially available conventional polypropylene meltblown nonwoven fabric is used instead of modified meltblown nonwoven fabric A.

[0138] The conventional polypropylene meltblown nonwoven fabric in this comparative example was purchased from Jiangxi Haorui Industrial Materials Co., Ltd. Performance Testing

[0139] The air permeability, radiation protection and antibacterial properties of the nanofiber composite air purification filter materials of Examples 1-8 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1.

[0140] (1) Breathability

[0141] Air permeability is determined by testing the filtration efficiency (dust-proof rate) of air purification filter materials, with reference to standard GB 2626-2006.

[0142] (2) Radiation protection

[0143] The radiation resistance is judged by testing the yellowing degree. After 30 hours of exposure using a carbon rod lamp type sunlight irradiation atmospheric climate tester, the yellowing degree of the test piece is measured using a colorimeter. The yellowing value (Y I )express.

[0144] (3) Antibacterial properties

[0145] The antibacterial performance is judged by the inhibition rate. When the inhibition rate is not less than 90%, it means that the sample has an antibacterial effect; when the inhibition rate is not less than 99%, it means that the sample has a good antibacterial effect. The reference standard is QB / T4371-2012.

[0146] Table 1

[0147]

[0148] It can be seen from the data in Table 1 that the air purification filter materials in Examples 1-5 of the present invention have high air permeability, radiation protection and antibacterial properties. Among them, Example 6 changes the ratio of the main components in the modified nanoparticles, so that 1-(3-aminopropyl) imidazole and tea polyphenols cannot fully react with BaTiO3 nanoparticles, resulting in a decrease in the radiation protection and antibacterial properties of the air purification filter material, but little effect on the air permeability; Examples 7-8 respectively change the ratio of polyethylene masterbatch and polypropylene masterbatch in the modified melt-blown non-woven fabric and the reaction ratio of the composite fiber and N-isopropylacrylamide, so that the polyethylene with good air permeability cannot fully play its role and the photocrosslinking reaction after absorbing rays is insufficient or the grafting of N-isopropylacrylamide and the composite fiber is incomplete, both of which lead to a significant decrease in the air permeability and radiation protection of the air purification filter material, but little effect on the antibacterial property; Comparative Example 1 and Comparative Example 2 respectively use TiO2 powder and commercially available conventional polypropylene melt-blown non-woven fabric to replace modified nanoparticles A and modified melt-blown non-woven fabric A. Tests found that the air permeability, radiation protection and antibacterial properties of the prepared air purification filter materials all showed poor results.

[0149] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A nanofiber composite air purification filter material, characterized in that: It includes a four-layer composite structure from top to bottom, which are non-woven fabric, nanofiber membrane layer, modified melt-blown non-woven fabric and spunbond non-woven fabric; The non-woven fabric is a PET needle-punched non-woven fabric; The raw materials for preparing the nanofiber membrane layer include the following components in parts by weight: 10-20 parts of polylactic acid, 3-5 parts of reinforcing agent, 2-4 parts of modified nanoparticles, and 100-150 parts of solvent; The material of the spunbond nonwoven fabric is PET or PP.

2. The nanofiber composite air purification filter material according to claim 1, characterized in that: The polylactic acid in the nanofiber membrane layer is L-polylactic acid; and the reinforcing agent is a β-type nucleating agent.

3. The nanofiber composite air purification filter material according to claim 1, characterized in that: The preparation method of the modified nanoparticles comprises the following steps: ① Add TiO2 powder to sodium hydroxide solution, place in a sealed polytetrafluoroethylene reactor after ultrasonic treatment, dry, wash, bake, and grind to obtain a precursor for use; ② Take the precursor in step ①, add barium nitrate and deionized water, ultrasonicate, seal in a polytetrafluoroethylene reactor, heat, wash, dry, and grind to obtain nanoparticles for later use; ③ 1-(3-aminopropyl)imidazole, tea polyphenols, isopropyl alcohol and deionized water are sequentially added to the nanoparticles obtained in step ②, and the mixture is heated, stirred, dried and ground to obtain modified nanoparticles.

4. The nanofiber composite air purification filter material according to claim 3, characterized in that: In the step ③, the mass ratio of the nanoparticles obtained in step ②, 1-(3-aminopropyl)imidazole and tea polyphenols is 1:(0.3-0.5):(0.15-0.35).

5. The nanofiber composite air purification filter material according to claim 1, characterized in that: The solvent is polyethylene glycol or dichloromethane.

6. The nanofiber composite air purification filter material according to claim 1, characterized in that: The method for preparing the nanofiber membrane layer comprises the following steps: Polylactic acid, reinforcing agent and modified nanoparticles are mixed in a solvent, allowed to stand at 40-50°C for 4-6 hours, stirred to obtain a blended solution, and then subjected to electrostatic spinning to obtain a nanofiber membrane layer.

7. The nanofiber composite air purification filter material according to claim 1, characterized in that: The preparation method of the modified melt-blown nonwoven fabric comprises the following steps: (1) Add concentrated hydrochloric acid and deionized water to a reaction vessel, add samarium oxide powder in batches, heat to 45-55°C, stir, filter, add ammonia water to adjust the pH to 7.5-8.5, filter, wash, filter, and dry to obtain reaction product 1 for later use; (2) Take the reaction product 1 in step (1), add methacrylic acid, heat to 75-85°C, stir until the solution becomes clear, filter, distill under reduced pressure, cool, filter, and dry to obtain the reaction product 2 for use; (3) mixing the reaction product 2 in step (2), polyethylene masterbatch, and polypropylene masterbatch, drying them under vacuum, and then extruding and melt-spinning them to obtain composite fibers for later use; (4) Ferrous sulfate, deionized water, and N-isopropylacrylamide are placed in a reaction kettle, mixed, and then the composite fiber of step (3) is added, an inert gas is passed through for 8-15 minutes, heated at 65-75°C for 2-4 hours, washed under ultraviolet light, and dried to obtain a mixture for use; (5) The mixture obtained in step (4) is subjected to a melt-blown process to obtain a modified melt-blown non-woven fabric.

8. The nanofiber composite air purification filter material according to claim 7, characterized in that: In the step (3), the mass ratio of the reaction product 2, the polyethylene masterbatch and the polypropylene masterbatch in the step (2) is 1: (3-5): (7-9); in the step (4), the mass ratio of the composite fiber in the step (3) and N-isopropylacrylamide is 1: (0.15-0.25).

9. A method for preparing the nanofiber composite air purification filter material according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, stacking four layers of materials, including non-woven fabric, nanofiber membrane layer, modified meltblown non-woven fabric and spunbond non-woven fabric, from top to bottom; S2. The four layers of materials stacked together in step S1 are bonded and formed by ultrasonic compounding to obtain a nanofiber composite air purification filter material.

10. The method for preparing the nanofiber composite air purification filter material according to claim 9, characterized in that: The power of the ultrasonic compound is 400-600kW, and the ultrasonic frequency is 90-110Hz.

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