Multifunctional air filtering material and preparation method thereof

Abstract

The invention relates to a multifunctional air filtering material and a preparation method thereof, and belongs to the technical field of filtering materials, and the multifunctional air filtering material comprises a high-capacity layer, an antistatic layer and a filtering antibacterial layer which are sequentially arranged from top to bottom; the high-capacity layer is made of a non-woven material with a three-dimensional network structure; the antistatic layer is of a net structure comprising conductive fibers and polymer fibers; the filtering antibacterial layer comprises a PTFE porous membrane layer and an antibacterial PTFE porous membrane layer of which the pore diameters are gradually increased from top to bottom; the PTFE porous membrane layer at least comprises a layer of PTFE porous membrane; the antibacterial PTFE porous membrane layer comprises at least one layer of antibacterial PTFE porous membrane; the antibacterial PTFE porous membrane is a PTFE porous membrane in which antibacterial nanoparticles are uniformly distributed. The multifunctional air filtering material provided by the invention has the advantages of high dust holding capacity, high filtering efficiency, low wind resistance, antistatic property and antibacterial property, and can meet the use requirements of different filtering devices.

Description

Technical Field

[0001] The invention relates to the technical field of filter materials, in particular to a multifunctional air filter material and a preparation method thereof. Background Art

[0002] With the advancement of science and technology and the enhancement of environmental awareness, higher requirements are placed on filter materials, especially in environments with high dust concentration and prone to static electricity. The filter materials are not only required to have efficient filtering capabilities, but also to have good antistatic and antibacterial properties to prevent the risks of fire, explosion and microbial contamination. However, traditional glass fiber filter materials not only have the problems of low dust holding capacity, high wind resistance, low damage resistance and high landfill cost, but also have difficulty in taking into account the filtering efficiency, antistatic and antibacterial properties. Summary of the invention

[0003] In response to one or more technical problems existing in the prior art, the present invention provides a multifunctional air filter material and a preparation method thereof. The air filter material provided by the present invention has high dust holding capacity, high filtration efficiency, low wind resistance, and also has antistatic and antibacterial properties, and can meet the use requirements of different filtering devices.

[0004] The present invention provides a multifunctional air filter material in a first aspect, characterized in that the multifunctional air filter material comprises a high-capacity layer, an antistatic layer and a filtration antibacterial layer which are arranged in sequence from top to bottom; the high-capacity layer is a non-woven material with a three-dimensional mesh structure; the antistatic layer is a mesh structure comprising conductive fibers and polymer fibers; the filtration antibacterial layer comprises a PTFE porous membrane layer and an antibacterial PTFE porous membrane layer with increasing pore sizes from top to bottom; the PTFE porous membrane layer comprises at least one layer of PTFE porous membrane; the antibacterial PTFE porous membrane layer comprises at least one layer of antibacterial PTFE porous membrane; the antibacterial PTFE porous membrane is a PTFE porous membrane with antibacterial nanoparticles uniformly distributed inside.

[0005] Preferably, the porosity of the antistatic layer is less than that of the high-capacity layer; preferably, the porosity of the nonwoven material is 60-90%; the porosity of the antistatic layer is not more than 60%;

[0006] The porosity of the antibacterial filtration layer is 70-90%; and / or

[0007] The pore size of the upper surface of the filtering antibacterial layer is 0.1-0.5 μm, and the pore size of the lower surface is 2-10 μm.

[0008] Preferably, the surface density of the nonwoven material is 10 to 100 g / m 2 , mesh size is 1~25mm 2 ;

[0009] The diameter of the fibers in the nonwoven material is 0.01 to 1000 μm, preferably 0.01 to 100 μm, more preferably 0.1 to 10 μm; and / or

[0010] The polymer used in the nonwoven material is one or more of polyester (PET), polyamide, polypropylene (PP), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyethersulfone (PES), cellulose acetate (CA), mixed cellulose ester (MCE), nitrocellulose (NC), polyvinylidene fluoride (PVDF), and nylon (NV).

[0011] Preferably, the mass ratio of the conductive fibers to the polymer fibers in the antistatic layer is 0.1 to 10:1;

[0012] The surface density of the antistatic layer is 20 to 300 g / m 2 , mesh size is 1~60mm 2 ; and / or

[0013] The conductive fiber is carbon fiber, metal fiber, or polymer fiber with a conductive layer coated on the surface.

[0014] Preferably, in the antibacterial PTFE porous membrane, the antibacterial nanoparticles account for 0.1 to 3% of the mass of PTFE;

[0015] The particle size of the antibacterial nanoparticles is 10 to 200 nm; and / or

[0016] The antibacterial nanoparticles are one or more of silver, copper, zinc, silver oxide, cupric oxide, cuprous oxide, zinc oxide, silver-loaded zirconium phosphate, silver nitrate, cupric nitrate, cuprous nitrate, zinc nitrate, silver sulfate, cuprous sulfate and zinc sulfate.

[0017] In a second aspect, the present invention provides a method for preparing the multifunctional air filter material according to the first aspect, the method comprising:

[0018] Compounding the PTFE porous membrane layer and the antibacterial PTFE porous membrane layer to obtain a filtering antibacterial layer;

[0019] The high-capacity layer, the antistatic layer and the filtering antibacterial layer are compounded to obtain a multifunctional air filtering material.

[0020] Preferably, the high capacity layer is made of a polymer by non-woven forming; the non-woven forming method is spunbond or meltblown; and / or

[0021] The antistatic layer is formed by conductive fibers and polymer fibers; the forming method is carding, wet nonwoven forming or wet woven forming.

[0022] Preferably, the preparation method of the PTFE porous membrane comprises: (1) pressure-forming a mixture of PTFE powder and solvent oil to obtain a green body; based on the total mass of the PTFE powder and the solvent oil, the PTFE powder accounts for 60-90%, and the solvent oil accounts for 10-40%; (2) extruding and calendering the green body to obtain a sheet; (3) biaxially stretching the sheet to obtain a PTFE porous membrane.

[0023] Preferably, the pressure of the pressure molding is 0.1-5 MPa, and the time of the pressure molding is 10-120 s;

[0024] The area ratio of the inlet to the outlet during the extrusion molding process is 20 to 120:1;

[0025] The thickness of the sheet is 50 to 400 μm; and / or

[0026] In the biaxial stretching process, the longitudinal stretching multiple is 3 to 30 times, and the transverse stretching multiple is 15 to 60 times.

[0027] Preferably, the compounding adopts at least one of thermal compounding, adhesive compounding and ultrasonic compounding, preferably at least one of thermal compounding and adhesive compounding;

[0028] The temperature of the thermal compounding and the adhesive compounding is 100-250° C., and the pressure is 0.1-0.8 MPa.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] The present invention uses a nonwoven material with a three-dimensional mesh structure as a high-capacity layer, which not only improves the support strength of the filter material, but also has a porous structure with high porosity and strong dust holding capacity, and can capture and retain a large number of dust particles, thereby extending the service life of the filter material and reducing the replacement frequency and cost. The mesh structure made of conductive fibers and polymer fibers is used as an antistatic layer, which can effectively prevent the filter material from generating static electricity accumulation during use, reducing the risk of fire and explosion; at the same time, the antistatic network formed by the conductive fibers in the antistatic layer can also play an antibacterial role to a certain extent. The pore size of the filtration antibacterial layer increases from top to bottom, which can effectively reduce resistance. The PTFE porous membrane has a microporous structure, a small pore size and uniform distribution, which can effectively block particles in the air, so that the filter material has low wind resistance characteristics, and can achieve high-efficiency filtration. The antibacterial PTFE porous membrane has antibacterial properties, which can further significantly improve the antibacterial ability of the filter material, effectively inhibit the growth and reproduction of microorganisms such as bacteria and viruses, reduce the growth of microorganisms on the filter, and reduce the adhesion of microorganisms on the membrane surface and the accumulation of metabolites, and reduce the adhesion of dust on these metabolites, so as to ensure that while improving the antibacterial properties, the accumulation of dust on the surface of the antibacterial PTFE porous membrane is indirectly reduced, and the dust holding capacity of the filter material is increased to a certain extent, thereby increasing the service life of the filter material.

[0031] The air filter material provided by the present invention has high dust holding capacity, high filtration efficiency, low wind resistance, and has both antistatic and antibacterial properties, and can meet the use requirements of different filtering devices, such as mask filters, room cleaning filters, filters in air conditioners and ventilation equipment, cabins, indoor air filters, etc., and is particularly suitable for occasions requiring high-efficiency filtration and long-life applications, such as air purification systems, medical equipment, and industrial dust removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 It is a structural schematic diagram of the multifunctional air filter material provided by the present invention.

[0034] Figure numerals: 1 - high capacity layer; 2 - antistatic layer; 3 - filtration and antibacterial layer; 31 - PTFE porous membrane layer; 32 - antibacterial PTFE porous membrane layer. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, the present invention provides a multifunctional air filter material in a first aspect, the multifunctional air filter material comprises a high-capacity layer 1, an antistatic layer 2 and a filtration antibacterial layer 3 which are arranged in sequence from top to bottom; the high-capacity layer 1 is a non-woven material with a three-dimensional mesh structure; the antistatic layer 2 is a mesh structure comprising conductive fibers and polymer fibers; the filtration antibacterial layer 3 comprises a PTFE porous membrane layer 31 and an antibacterial PTFE porous membrane layer 32 with increasing pore sizes from top to bottom; the PTFE porous membrane layer 31 comprises at least one layer of PTFE porous membrane; the antibacterial PTFE porous membrane layer 32 comprises at least one layer of antibacterial PTFE porous membrane; the antibacterial PTFE porous membrane is a PTFE porous membrane with antibacterial nanoparticles uniformly distributed inside.

[0037] The present invention uses a nonwoven material with a three-dimensional mesh structure as a high-capacity layer, which not only improves the support strength of the filter material, but also has a porous structure with high porosity and strong dust holding capacity, and can capture and retain a large number of dust particles, thereby extending the service life of the filter material and reducing the replacement frequency and cost. The mesh structure made of conductive fibers and polymer fibers is used as an antistatic layer, which can effectively prevent the filter material from generating static electricity accumulation during use, reducing the risk of fire and explosion; at the same time, the antistatic network formed by the conductive fibers in the antistatic layer can also play an antibacterial role to a certain extent. The pore size of the filtration antibacterial layer increases from top to bottom, which can effectively reduce resistance. The PTFE porous membrane has a microporous structure, a small pore size and uniform distribution, which can effectively block particles in the air, so that the filter material has low wind resistance characteristics, and can achieve high-efficiency filtration. The antibacterial PTFE porous membrane has antibacterial properties, which can further significantly improve the antibacterial ability of the filter material, effectively inhibit the growth and reproduction of microorganisms such as bacteria and viruses, reduce the growth of microorganisms on the filter, and reduce the adhesion of microorganisms on the membrane surface and the accumulation of metabolites, and reduce the adhesion of dust on these metabolites, so as to ensure that while improving the antibacterial properties, the accumulation of dust on the surface of the antibacterial PTFE porous membrane is indirectly reduced, and the dust holding capacity of the filter material is increased to a certain extent, which can improve the dust holding capacity of the filter material to a certain extent, thereby increasing the service life of the filter material.

[0038] The air filter material provided by the present invention has high dust holding capacity, high filtration efficiency, low wind resistance, and has both antistatic and antibacterial properties, and can meet the use requirements of different filtering devices, such as mask filters, room cleaning filters, filters in air conditioners and ventilation equipment, cabins, indoor air filters, etc., and is particularly suitable for occasions requiring high-efficiency filtration and long-life applications, such as air purification systems, medical equipment, and industrial dust removal.

[0039] According to some preferred embodiments, the porosity of the antistatic layer is less than that of the high-capacity layer; preferably, the porosity of the nonwoven material of the high-capacity layer is 60-90% (for example, 60%, 65%, 70%, 75%, 80%, 85% or 90%); the porosity of the antistatic layer is not more than 60%. The antistatic layer is formed by mixing conductive fibers and polymer fibers, wherein the conductive network formed by the conductive fibers is the basis for achieving antistatic. If the porosity is too high, it is not conducive to the generation of the conductive network. Therefore, the porosity of the antistatic layer is preferably within the above range in the present invention to ensure that the filter material has excellent antistatic properties.

[0040] According to some preferred embodiments, the porosity of the antibacterial filtration layer is 70-90%.

[0041] According to some preferred embodiments, the pore size of the upper surface of the antibacterial filtration layer is 0.1-0.5 μm, and the pore size of the lower surface is 2-10 μm. The pore size of the antibacterial filtration layer of the present invention increases from top to bottom, which can effectively reduce resistance.

[0042] According to some preferred embodiments, the surface density of the nonwoven material is 10 to 100 g / m 2 , mesh size is 1~25mm 2 .

[0043] According to some preferred embodiments, the diameter of the fibers in the nonwoven material is 0.01 to 1000 μm, preferably 0.01 to 100 μm, and more preferably 0.1 to 10 μm.

[0044] According to some preferred embodiments, the polymer used in the nonwoven material is one or more of polyester (PET), polyamide, polypropylene (PP), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyethersulfone (PES), cellulose acetate (CA), mixed cellulose ester (MCE), nitrocellulose (NC), polyvinylidene fluoride (PVDF), and nylon (NV).

[0045] According to some preferred embodiments, the mass ratio of the conductive fiber to the polymer fiber in the antistatic layer is 0.1 to 10:1. The present invention controls the mass ratio of the conductive fiber to the polymer fiber within the above range to ensure that an antistatic layer with excellent antistatic properties is formed. In addition, the antistatic network formed by the conductive fibers in the antistatic layer can not only effectively prevent static electricity accumulation, but also continue to exert antibacterial effects and improve the antibacterial properties of the filter material. The inventors have found that if the amount of conductive fiber is too small, the antistatic properties of the obtained material are poor; if the amount of conductive fiber is too large, it is not conducive to the molding of the antistatic layer.

[0046] According to some preferred embodiments, the surface density of the antistatic layer is 20 to 300 g / m 2 , mesh size is 1~60mm 2 .

[0047] According to some preferred embodiments, the conductive fiber is a carbon fiber, a metal fiber, or a polymer fiber with a conductive layer coated on the surface. Preferably, the polymer fiber with a conductive layer coated on the surface is obtained by depositing a conductive layer on the surface of the polymer fiber by chemical plating; the conductive layer is a metal (such as copper, nickel, gold, etc.) layer.

[0048] The metal ions in the metal fiber or the polymer fiber coated with a conductive layer have antibacterial effects and can destroy the cell wall and cell membrane of bacteria, thereby achieving a sterilization effect; in particular, copper fiber and silver fiber are widely considered to be one of the most effective antibacterial metal fibers. When the metal fiber is used as a filter material, its antibacterial properties can effectively prevent the growth and spread of bacteria on the filter medium, so that the antistatic layer has certain antibacterial properties while playing an antistatic role. In order to take into account the antistatic properties, antibacterial properties, molding properties and costs, the conductive fiber of the present invention is preferably a polymer fiber coated with a copper conductive layer.

[0049] According to some preferred embodiments, in the antibacterial PTFE porous membrane, the antibacterial nanoparticles account for 0.1-3% (for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5% or 3%) of the mass of PTFE. The addition of antibacterial nanoparticles to the antibacterial PTFE porous membrane will have a certain effect on the pore structure of the PTFE porous membrane. When the antibacterial nanoparticles are controlled within the above range, it can be ensured that the nanoparticles are evenly distributed and will not block the pores of the antibacterial PTFE porous membrane, and will not have a significant effect on the air permeability and dust holding capacity of the membrane.

[0050] According to some preferred embodiments, the particle size of the antibacterial nanoparticles is 10 to 200 nm.

[0051] The present invention controls the dosage and particle size of the antibacterial nanoparticles within the above range to ensure that the antibacterial PTFE porous membrane with excellent antibacterial performance is obtained without affecting the molding of the antibacterial PTFE porous membrane. If the dosage of the antibacterial nanoparticles is too small, the antibacterial performance of the obtained material is poor; if the dosage and particle size of the antibacterial nanoparticles are too large, the antibacterial PTFE porous membrane cannot be molded.

[0052] According to some preferred embodiments, the antibacterial nanoparticles are one or more of silver, copper, zinc, silver oxide, cupric oxide, cuprous oxide, zinc oxide, silver-loaded zirconium phosphate, silver nitrate, cupric nitrate, cuprous nitrate, zinc nitrate, silver sulfate, cuprous sulfate and zinc sulfate. The types of the antibacterial nanoparticles of the present invention are not limited to the above range, and different antibacterial nanoparticles can be selected according to different use requirements. In addition, the antibacterial nanoparticles of the present invention not only have antibacterial effects, but also have certain antiviral effects. For example, nanosilver can interact with the surface of the virus, thereby destroying the normal life activities of the virus (such as transcription, replication of genetic material, and protein translation) or preventing the virus from contacting cells, and has certain effects on hepatitis B virus, Rift Valley fever virus, MS2 bacteriophage, SARS-CoV-2, etc.; nano copper and its oxide directly contact with viral proteins, causing structural conformational changes or inhibiting the activity of proteins; copper combines with viral nucleic acid to undergo redox reactions, generating free radicals to kill the virus, and has certain effects on SARS-CoV-2, T4 bacteriophage, herpes simplex virus-1 (HSV-1), Zika virus, infectious bronchitis virus, etc. Zinc oxide generates free radicals under photocatalysis, which can react with oxygen in the air to generate reactive oxygen, destroy the virus structure, interfere with surface antigens, and prevent virus particles from attaching to host cell receptors, thereby inactivating virus particles, and has certain effects on hepatitis E virus and hepatitis C virus, SARS-CoV-2, H1N1, HSV-1, etc.

[0053] In a second aspect, the present invention provides a method for preparing the multifunctional air filter material according to the first aspect, the method comprising:

[0054] Compounding the PTFE porous membrane layer and the antibacterial PTFE porous membrane layer to obtain a filtering antibacterial layer;

[0055] Multi-layer composite: The high-capacity layer, antistatic layer and filtration antibacterial layer are composited to obtain a multifunctional air filtration material.

[0056] According to some preferred embodiments, the high-capacity layer is made of a polymer through non-woven forming; the non-woven forming method is a spunbond method or a meltblown method.

[0057] The spunbond method uses the chemical fiber spinning method to spin, draw, and lay polymers into a web, and finally reinforce them by needle punching, hydroentanglement, hot rolling or self-bonding to form a nonwoven material. Specifically, the polymer slices are dried, melted, filtered and metered, and then continuously transported to the spinning assembly. In the spinning assembly, the polymer melt is extruded through the micropores on the spinneret to form continuous filaments. These filaments are stretched, cooled and solidified to form fibers. The fibers are laid into a web and reinforced by needle punching, hydroentanglement, hot rolling or self-bonding to form a spunbond nonwoven material.

[0058] The meltblowing method is a spinning method that uses high-speed hot air flow to quickly stretch and solidify the newly extruded polymer melt. Specifically, the polymer masterbatch is put into the extruder and melted in the extruder. The melt passes through a metering pump and reaches the meltblowing die head. In the meltblowing die head, the melt is extruded through a row of capillaries with small spacing. At the same time, a high-speed hot air flow is added to stretch the melt. The stretched melt stream quickly cools and solidifies to form fibers. The fibers are collected on a receiving device to form a meltblown nonwoven material.

[0059] According to some preferred embodiments, the antistatic layer is formed by conductive fibers and polymer fibers; the forming method is carding, wet nonwoven forming or wet woven forming.

[0060] The PTFE porous membrane of the invention is prepared by a biaxial stretching process of a mixture of PTFE powder and solvent oil; the antibacterial PTFE porous membrane is prepared by a biaxial stretching process of a mixture of PTFE powder, solvent oil and antibacterial nanoparticles.

[0061] According to some preferred embodiments, a method for preparing a PTFE porous membrane by a biaxial stretching process comprises: (1) pressure-forming a mixture of PTFE powder and solvent oil to obtain a green body; based on the total mass of the PTFE powder and the solvent oil, the PTFE powder accounts for 60-90%, and the solvent oil accounts for 10-40%; (2) extruding and calendering the green body to obtain a sheet; (3) biaxially stretching the sheet to obtain a PTFE porous membrane.

[0062] According to some specific embodiments, a method for preparing a PTFE porous membrane by a biaxial stretching process comprises: mixing PTFE powder and solvent oil, wherein the PTFE powder accounts for 60 to 90 wt % and the solvent oil accounts for 10 to 40 wt %, and placing the mixture in an oven at 10 to 60° C. for 10 to 50 hours to obtain a mixture; then placing the mixture in a plunger-type blanking machine under a pressure of 0.1 to 5 MPa for 10 to 120 s to form a cylindrical blank, and then placing the blank in a plunger-type pusher to extrude a specific shape (such as a round shape, a flat plate shape, etc.), and forming a sheet with a thickness of 50 to 400 μm after calendering by a calender; and biaxially stretching the sheet, wherein the longitudinal stretching is 3 to 30 times and the transverse stretching is 15 to 60 times to obtain a PTFE porous membrane.

[0063] According to some preferred embodiments, a method for preparing an antibacterial PTFE porous membrane by a biaxial stretching process comprises: (i) pressure-forming a mixture of PTFE powder, solvent oil and antibacterial nanoparticles to obtain a green body; based on the total mass of the PTFE powder and the solvent oil, the PTFE powder accounts for 60-90%, the solvent oil accounts for 10-40%; the antibacterial nanoparticles account for 0.1-3% of the mass of the PTFE powder; (ii) extruding and calendering the green body to obtain a sheet; and (iii) biaxially stretching the sheet to obtain an antibacterial PTFE porous membrane.

[0064] It should be noted that the difference between the antibacterial PTFE porous membrane of the present invention and the PTFE porous membrane is that antibacterial nanoparticles are added to the preparation raw materials. The preparation methods and related parameters of the two are the same, which will not be described in detail here.

[0065] According to some preferred embodiments, the pressure of the pressure molding is 0.1-5 MPa, and the time of the pressure molding is 10-120 s.

[0066] According to some preferred embodiments, the area ratio of the inlet and the outlet during the extrusion molding process is 20 to 120:1. It should be noted that the present invention can regulate the area ratio of the inlet and the outlet during the extrusion molding process according to the pore size requirements of the PTFE porous membrane to be prepared. For example, in order to ensure that the pore size of the PTFE porous membrane is 0.1 to 0.5 μm, the area ratio of the inlet and the outlet during the extrusion molding process is 60 to 120:1. In order to ensure that the pore size of the PTFE porous membrane is 2 to 10 μm, the area ratio of the inlet and the outlet during the extrusion molding process is 20 to 58:1.

[0067] According to some preferred embodiments, the thickness of the sheet is 50-400 μm.

[0068] According to some preferred embodiments, during the biaxial stretching process, the longitudinal stretching multiple is 3 to 30 times, and the transverse stretching multiple is 15 to 60 times.

[0069] According to some preferred embodiments, the compounding adopts at least one of thermal compounding, adhesive compounding and ultrasonic compounding, preferably at least one of thermal compounding and adhesive compounding.

[0070] According to some preferred embodiments, the temperature of the thermal compounding and the adhesive compounding is 100-250° C., and the pressure is 0.1-0.8 MPa.

[0071] In order to more clearly illustrate the technical solutions and advantages of the present invention, the present invention is further described below in conjunction with the examples. The present invention does not specifically limit the sources of the reagents used in the examples and comparative examples, and the reagents can be directly purchased or synthesized by themselves.

[0072] Example 1

[0073] A multifunctional air filter material, comprising a high-capacity layer, an antistatic layer and a filter antibacterial layer arranged in sequence from top to bottom; the high-capacity layer is a melt-blown PE nonwoven material with a three-dimensional mesh structure (prepared by melt-blowing method using PE as raw material, with a surface density of 10g / m 2 , mesh size is 25mm 2 , the fiber diameter is 10μm, the porosity is 90%); the antistatic layer is a mesh structure (surface density is 20g / m 2 , mesh size is 60mm 2 , porosity is 60%); the filtration antibacterial layer includes from top to bottom a layer of PTFE porous membrane (prepared by biaxial stretching process using PTFE powder and solvent oil as raw materials, with a pore size of 0.5μm and a porosity of 70%) and a layer of antibacterial PTFE porous membrane (prepared by biaxial stretching process using PTFE powder, solvent oil and antibacterial nanoparticles as raw materials; pore size is 2μm, porosity is 80%, antibacterial nanoparticles ZnO account for 3% of the mass of PTFE, and the particle size of antibacterial nanoparticles ZnO is 200nm). Among them, the PTFE porous membrane is prepared by biaxial stretching process using PTFE powder and solvent oil as raw materials; the antibacterial PTFE porous membrane is prepared by biaxial stretching process using PTFE powder, solvent oil and antibacterial nanoparticles as raw materials.

[0074] Example 2

[0075] A multifunctional air filter material, comprising a high-capacity layer, an antistatic layer and a filtering antibacterial layer which are arranged in sequence from top to bottom; the high-capacity layer is a melt-blown PET nonwoven material with a three-dimensional mesh structure (prepared by melt-blowing method using PET as raw material, with a surface density of 50g / m 2 , mesh size is 10mm 2 , the fiber diameter is 5μm, the porosity is 75%); the antistatic layer is composed of PET fibers with a surface coated with a copper conductive layer in a mass ratio of 5:1 and a mesh structure formed by a wet nonwoven forming process of PET fibers (surface density is 150g / m 2 , mesh size is 30mm 2 , porosity is 60%); the filtration antibacterial layer includes, from top to bottom, a first PTFE porous membrane (pore size is 0.5μm, porosity is 70%), a second PTFE porous membrane (pore size is 1μm, porosity is 75%), a third PTFE porous membrane (pore size is 2μm, porosity is 80%), a fourth PTFE porous membrane (pore size is 4μm, porosity is 85%) and a layer of antibacterial PTFE porous membrane (pore size is 6μm, porosity is 90%, antibacterial nanoparticles ZnO account for 1% of the PTFE mass; the particle size of the antibacterial nanoparticles ZnO is 100nm); wherein, the first PTFE porous membrane, the second PTFE porous membrane, the third PTFE porous membrane and the fourth PTFE porous membrane are prepared by a biaxial stretching process using PTFE powder and solvent oil as raw materials; the antibacterial PTFE porous membrane is prepared by a biaxial stretching process using PTFE powder, solvent oil and antibacterial nanoparticles as raw materials.

[0076] Example 3

[0077] A multifunctional air filter material, comprising a high-capacity layer, an antistatic layer and a filtration antibacterial layer arranged in sequence from top to bottom; the high-capacity layer is a spunbonded PP nonwoven material with a three-dimensional mesh structure (prepared by spunbonding method using PP as raw material, with a surface density of 100g / m 2 , mesh size is 1mm 2 The antistatic layer is composed of PP fibers with a surface coated with a copper conductive layer and a mesh structure formed by a wet nonwoven forming process (surface density of 300g / m 2 , mesh size is 1mm 2, porosity is 30%); the filtration antibacterial layer includes, from top to bottom, a first PTFE porous membrane (pore size is 0.5μm, porosity is 70%), a second PTFE porous membrane (pore size is 2μm, porosity is 75%), a third PTFE porous membrane (pore size is 5μm, porosity is 80%), a fourth PTFE porous membrane (pore size is 8μm, porosity is 85%) and a layer of antibacterial PTFE porous membrane (pore size is 10μm, porosity is 90%, antibacterial nanoparticles ZnO account for 1% of the mass of PTFE, and the particle size of the antibacterial nanoparticles ZnO is 10nm); wherein, the first PTFE porous membrane, the second PTFE porous membrane, the third PTFE porous membrane and the fourth PTFE porous membrane are prepared by a biaxial stretching process using PTFE powder and solvent oil as raw materials; the antibacterial PTFE porous membrane is prepared by a biaxial stretching process using PTFE powder, solvent oil and antibacterial nanoparticles as raw materials.

[0078] Example 4

[0079] A multifunctional air filter material, comprising a high-capacity layer, an antistatic layer and a filtration antibacterial layer arranged in sequence from top to bottom; the high-capacity layer is a spunbonded PET nonwoven material with a three-dimensional mesh structure (surface density of 50g / m 2 , mesh size is 10mm 2 , the fiber diameter is 5μm, the porosity is 75%); the antistatic layer is composed of PET fibers with a surface coated with a copper conductive layer and PET fibers with a mass ratio of 5:1 and a mesh structure formed by wet non-woven molding (surface density is 150g / m 2 , mesh size is 30mm 2 , porosity is 60%); the filtration antibacterial layer includes, from top to bottom, a first PTFE porous membrane (pore size is 0.5μm, porosity is 70%), a second PTFE porous membrane (pore size is 2μm, porosity is 75%), a third PTFE porous membrane (pore size is 5μm, porosity is 80%), a first antibacterial PTFE porous membrane (pore size is 8μm, porosity is 85%, antibacterial nanoparticles ZnO account for 1% of the mass of PTFE, and the particle size of antibacterial nanoparticles ZnO is 10nm) and a second antibacterial PTFE porous membrane (pore size is 10μm, porosity is 90%, antibacterial nanoparticles ZnO account for 1% of the mass of PTFE, and the particle size of antibacterial nanoparticles ZnO is 10nm). Among them, the first PTFE porous membrane, the second PTFE porous membrane, and the third PTFE porous membrane are prepared by a biaxial stretching process using PTFE powder and solvent oil as raw materials; the first antibacterial PTFE porous membrane and the second antibacterial PTFE porous membrane are prepared by a biaxial stretching process using PTFE powder, solvent oil and antibacterial nanoparticles as raw materials.

[0080] Comparative Example 1

[0081] It is basically the same as Example 2, except that the mass ratio of the PET fiber with the copper conductive layer coated on the surface to the PET fiber in the antistatic layer is 0.05:1.

[0082] Comparative Example 2

[0083] It is basically the same as Example 2, except that the porosity of the antistatic layer is 80%.

[0084] Comparative Example 3

[0085] The same as Example 2, except that the antistatic layer is replaced by a mesh structure formed by wet nonwoven molding of PET fibers (surface density of 150 g / m 2 , mesh size is 30mm 2 , porosity is 60%).

[0086] Comparative Example 4

[0087] It is basically the same as Example 2, with the only difference being that the filtration antibacterial layer includes from top to bottom four layers of PTFE porous membrane (pore size is 2 μm, porosity is 80%) and a layer of antibacterial PTFE porous membrane (pore size is 2 μm, porosity is 80%, antibacterial nanoparticles ZnO account for 1% of the mass of PTFE; the particle size of the antibacterial nanoparticles ZnO is 100 nm).

[0088] Comparative Example 5

[0089] It is basically the same as Example 2, except that no antibacterial particles are added to the filtration antibacterial layer, that is, the filtration antibacterial layer includes, from top to bottom, a first PTFE porous membrane (pore size of 0.5 μm, porosity of 70%), a second PTFE porous membrane (pore size of 1 μm, porosity of 75%), a third PTFE porous membrane (pore size of 2 μm, porosity of 80%), a fourth PTFE porous membrane (pore size of 4 μm, porosity of 85%) and a fifth PTFE porous membrane (pore size of 6 μm, porosity of 90%).

[0090] The specific test methods for the performance test of the multifunctional air filter materials provided in the embodiments of the present invention and the comparative examples are as follows:

[0091] Air filter paper dust holding capacity test: refer to the national standard JG / T22-1999 "General ventilation air filter performance test method".

[0092] Air filter paper filtration efficiency and filtration resistance test: refer to the national standard GB / T 6165-2021 "High-efficiency air filter performance test method efficiency and resistance".

[0093] Antibacterial performance: refer to the national standard GB / T20944-2007 "Textile Antibacterial Performance Testing Standard".

[0094] Antistatic performance: refer to the national standard GB12703.4-2010 "Evaluation of electrostatic properties of textiles Part 4: Resistivity".

[0095] Table 1. Performance data of air filter materials provided by various embodiments of the present invention and comparative examples

[0096]

[0097] It should be noted that the differences in the filtration performance, antibacterial performance and antistatic performance of the filter materials in Examples 1-4 are caused by the differences in the selection of materials and preparation processes of the various layers of the filter materials. Different materials and preparation processes can be selected according to specific needs during actual use. The present invention uses Example 2 as an example for comparison in order to better illustrate the technical solution of the present invention rather than to limit it. The surface resistance in the table is the surface resistance of the antistatic layer.

[0098] As shown in Table 1, compared with Example 2, the conductive fiber content of the antistatic layer in Comparative Example 1 is too low, and the porosity of the antistatic layer in Comparative Example 2 is too high, which will cause the antistatic ability of the filter material to deteriorate. In addition, the antistatic layers in Comparative Examples 1 and 2 cannot play an effective antibacterial role, resulting in a decrease in the antibacterial performance of the filter material. There is no conductive fiber in the antistatic layer of Comparative Example 3, the antistatic ability decreases, and the surface resistance increases. In Comparative Example 4, the pore size of the PTFE porous membrane and the antibacterial PTFE porous membrane in the antibacterial filtration layer is the same, and there is no pore size gradient, which leads to an increase in the filtration resistance of the filter material and a decrease in the filtration efficiency. In Comparative Example 5, the antibacterial filtration layer does not contain antibacterial particles, the antibacterial ability of the filter material decreases, and the dust holding capacity is also reduced to a certain extent.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multifunctional air filter material, characterized in that: The multifunctional air filtration material comprises a high-capacity layer, an antistatic layer and a filtration antibacterial layer which are arranged in sequence from top to bottom; the high-capacity layer is a non-woven material with a three-dimensional mesh structure; the antistatic layer is a mesh structure comprising conductive fibers and polymer fibers; the filtration antibacterial layer comprises a PTFE porous membrane layer and an antibacterial PTFE porous membrane layer with increasing pore sizes from top to bottom; the PTFE porous membrane layer comprises at least one layer of PTFE porous membrane; the antibacterial PTFE porous membrane layer comprises at least one layer of antibacterial PTFE porous membrane; the antibacterial PTFE porous membrane is a PTFE porous membrane with antibacterial nanoparticles uniformly distributed inside.

2. The air filter material according to claim 1, characterized in that: The porosity of the antistatic layer is less than that of the high-capacity layer; preferably, the porosity of the nonwoven material is 60-90%; the porosity of the antistatic layer is not more than 60%; The porosity of the antibacterial filtration layer is 70-90%; and / or The pore size of the upper surface of the filtering antibacterial layer is 0.1-0.5 μm, and the pore size of the lower surface is 2-10 μm.

3. The air filter material according to claim 1, characterized in that: The surface density of the nonwoven material is 10 to 100 g / m 2 , mesh size is 1~25mm 2 ; The diameter of the fibers in the nonwoven material is 0.01 to 1000 μm, preferably 0.01 to 100 μm, more preferably 0.1 to 10 μm; and / or The polymer used in the nonwoven material is one or more of polyester, polyamide, polypropylene, polyphenylene sulfide, polytetrafluoroethylene, polyether sulfone, cellulose acetate, mixed cellulose ester, nitrocellulose, polyvinylidene fluoride, and nylon.

4. The air filter material according to claim 1, characterized in that: The mass ratio of the conductive fibers to the polymer fibers in the antistatic layer is 0.1 to 10:1 ； The surface density of the antistatic layer is 20 to 300 g / m 2 , mesh size is 1~60mm 2 ; and / or The conductive fiber is carbon fiber, metal fiber, or polymer fiber with a conductive layer coated on the surface.

5. The air filter material according to claim 1, characterized in that: In the antibacterial PTFE porous membrane, the antibacterial nanoparticles account for 0.1 to 3% of the mass of PTFE; The particle size of the antibacterial nanoparticles is 10 to 200 nm; and / or The antibacterial nanoparticles are one or more of silver, copper, zinc, silver oxide, cupric oxide, cuprous oxide, zinc oxide, silver-loaded zirconium phosphate, silver nitrate, cupric nitrate, cuprous nitrate, zinc nitrate, silver sulfate, cuprous sulfate and zinc sulfate.

6. A method for preparing the multifunctional air filter material according to any one of claims 1 to 5, characterized in that: The preparation method comprises: Compounding the PTFE porous membrane layer and the antibacterial PTFE porous membrane layer to obtain a filtering antibacterial layer; the PTFE porous membrane layer comprises at least one layer of PTFE porous membrane; the antibacterial PTFE porous membrane layer comprises at least one layer of antibacterial PTFE porous membrane; The high-capacity layer, the antistatic layer and the filtering antibacterial layer are compounded to obtain a multifunctional air filtering material.

7. The preparation method according to claim 6, characterized in that: The high capacity layer is made of polymer by non-woven forming; the non-woven forming method is spunbond method or meltblown method; and / or The antistatic layer is formed by conductive fibers and polymer fibers; the forming method is carding, wet nonwoven forming or wet woven forming.

8. The preparation method according to claim 6, characterized in that: The preparation method of the PTFE porous membrane comprises: (1) subjecting a mixture of PTFE powder and solvent oil to pressure molding to obtain a green body; based on the total mass of the PTFE powder and the solvent oil, the PTFE powder accounts for 60-90% and the solvent oil accounts for 10-40%; (2) subjecting the green body to extrusion molding and calendering molding to obtain a sheet; and (3) subjecting the sheet to biaxial stretching to obtain a PTFE porous membrane.

9. The preparation method according to claim 8, characterized in that: The pressure of the pressure molding is 0.1-5 MPa, and the time of the pressure molding is 10-120 s; The area ratio of the inlet to the outlet during the extrusion molding process is 20 to 120:1; The thickness of the sheet is 50 to 400 μm; and / or In the biaxial stretching process, the longitudinal stretching multiple is 3 to 30 times, and the transverse stretching multiple is 15 to 60 times.

10. The preparation method according to claim 6, characterized in that: The compounding adopts at least one of thermal compounding, adhesive compounding and ultrasonic compounding, preferably at least one of thermal compounding and adhesive compounding; The temperature of the thermal compounding and the adhesive compounding is 100-250° C., and the pressure is 0.1-0.8 MPa.

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