Multifunctional air filtering material and preparation method thereof

Abstract

The invention provides a multifunctional air filtering material and a preparation method thereof, the filtering material sequentially comprises a hydrophobic isolation layer, a middle filtering layer and a supporting layer from a windward side to a leeward side; wherein the hydrophobic isolation layer is a polytetrafluoroethylene stretching film; the middle filtering layer is at least one of a polytetrafluoroethylene stretching film, a thermoplastic polyurethane film or a nanofiber film; the supporting layer is a modified humidity-sensitive non-woven fabric; and the aperture of the middle filter layer is smaller than that of the hydrophobic isolation layer. Compared with the traditional glass fiber air filter paper, the filter material disclosed by the invention has the advantages of high efficiency and low resistance (the pressure drop increment is less than 10%, and the filter efficiency reaches 99.995%-99.9999%), meanwhile, the stiffness is kept to be greater than 500mg under the condition that the test environment humidity is 70%, and the filter material has the advantages of high efficiency and low resistance. The requirements on high efficiency, low resistance and long service life of the filter material in complex environments such as high humidity can be effectively met, and the filter material can be widely applied to the fields of damp-proof and antibacterial filtration of operating rooms, high-end household purifiers, industrial air purification and the like.

Description

Technical Field

[0001] This invention relates to the field of air filtration materials technology, and in particular to a multifunctional air filtration material and its preparation method. Background Technology

[0002] Air filtration materials are used in medical and clean environments, industrial dust removal and exhaust gas treatment, civil air purification and personal protection. Mainstream materials include MOFs (metal-organic frameworks), PTFE membrane composite filter media, glass fiber filter media, nanofiber composite materials, PVDF membranes, etc., while high efficiency, low resistance, environmental protection and sustainability, and multifunctional integration are the core directions for their future development.

[0003] Currently, most air filtration materials primarily focus on particulate matter filtration, but their functions are relatively limited, generally lacking composite functions such as antibacterial properties, self-cleaning capabilities, and stable performance under extreme environments. For example, under conditions of high humidity or oily particles, the materials are prone to clogging, leading to decreased air permeability and increased filtration resistance. Simultaneously, the materials easily absorb water, causing localized structural collapse and significantly reducing filtration efficiency. Furthermore, use in humid air drastically shortens their lifespan, necessitating frequent material replacement and limiting their applicability and durability in complex environments.

[0004] Therefore, there is an urgent need to provide a multifunctional air filter material and its preparation method. Summary of the Invention

[0005] This invention provides a multifunctional air filter material and its preparation method, which can solve the problem of decreased filtration performance of existing air filter materials under conditions such as high humidity or oily particles.

[0006] In a first aspect, the present invention provides a multifunctional air filtration material, which, from the windward side to the leeward side, sequentially comprises a hydrophobic isolation layer, an intermediate filtration layer, and a support layer; wherein, the hydrophobic isolation layer is a polytetrafluoroethylene (PTFE) stretched membrane; the intermediate filtration layer is at least one of a PTFE stretched membrane, a thermoplastic polyurethane membrane, or a nanofiber membrane; the support layer is a modified moisture-sensitive nonwoven fabric; and the pore size of the intermediate filtration layer is smaller than that of the hydrophobic isolation layer.

[0007] Preferably, the pore size of the hydrophobic barrier layer is 5~10μm; the pore size of the intermediate filter layer is 0.1~0.6μm; and the basis weight of the support layer is 30~120g / m³. 2 .

[0008] Preferably, the modified moisture-sensitive nonwoven fabric is prepared by the following method: (1) Zirconium isopropoxide and acetylacetone are stirred and mixed to obtain a first mixed solution; the mixed solvent and nanoparticles are mixed evenly to obtain a second mixed solution; (2) Under continuous stirring, the second mixed solution is added dropwise to the first mixed solution, and a composite sol is obtained after mixing and reaction; the nonwoven fabric is immersed in the composite sol for impregnation and lifting, and the modified moisture-sensitive nonwoven fabric is obtained after drying and shaping.

[0009] Preferably, the nanoparticles are polyvinylidene fluoride nanoparticles or polytetrafluoroethylene nanoparticles, and the mixed solvent is N,N-dimethylformamide and water.

[0010] Preferably, the volume ratio of N,N-dimethylformamide to water is (7~9):1.

[0011] In step (1), the volume ratio of zirconium isopropoxide to acetylacetone is (3~4):1.

[0012] Preferably, the nanoparticle content accounts for 0.1-0.6% of the mass of the mixed solvent, by mass percentage.

[0013] Preferably, in step (2), the reaction temperature is 30~35℃ and the time is 20~30min.

[0014] Preferably, in step (2), the nonwoven fabric is at least one of PE nonwoven fabric, PET nonwoven fabric, and PE / PET core-sheath structure nonwoven fabric, with a basis weight of 30~120g / m³. 2 .

[0015] Preferably, in step (2), the nonwoven fabric is fixed on the impregnation and lifting machine, first impregnated in the composite sol at a speed of 8~10mm / s for 1~2min, and then the nonwoven fabric is lifted from the composite sol at a speed of 15~18mm / s for 1~2min. After repeating 2~3 times, a moisture-sensitive coating is formed on the nonwoven fabric.

[0016] Preferably, in step (2), the drying and shaping temperature is 35~40℃, the humidity is 60~70%, and the time is 2~3h.

[0017] Secondly, embodiments of the present invention also provide a method for preparing a multifunctional air filter material, the method comprising the following steps: S1: Polyethylene adhesive is sprayed onto one side of the modified moisture-sensitive nonwoven fabric and cured to obtain a support layer; wherein the amount of polyethylene adhesive sprayed is 5~10g / m². 2 ; S2: Place the intermediate filter layer and the hydrophobic isolation layer sequentially on the side of the support layer sprayed with polyethylene adhesive, and then use a hot press roller to composite the multi-layer material to obtain the multifunctional air filter material.

[0018] Preferably, the hot press roller includes a rubber roller and a steel roller that are parallel to each other; wherein, the hydrophobic isolation layer is in contact with the rubber roller and the support layer is in contact with the steel roller.

[0019] Preferably, the temperature of the hot press roller is 110~130℃, the pressure is 0.05~1MPa, and the combined speed is 5~30m / min.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: In this invention, the multifunctional air filter material adopts a three-layer functional structure arranged sequentially from the windward side to the leeward side. Specifically, a polytetrafluoroethylene (PTFE) stretched membrane is used as a hydrophobic isolation layer, utilizing its inherent hydrophobic properties and large pore size to achieve pre-filtration of coarse particles. The middle filter layer uses a membrane material with a finer pore size, which effectively intercepts ultrafine particles through its microporous structure, balancing air resistance while ensuring extremely high filtration efficiency. The leeward side uses a modified moisture-sensitive nonwoven fabric as a support layer, which actively manages moisture through its surface properties in high humidity environments, thereby protecting the filtration performance of the internal core material and the stability of the support structure. Thus, compared to traditional glass fiber air filter paper, the filter material in this invention maintains the advantages of high efficiency and low resistance (pressure drop increase <10%, filtration efficiency of 99.995%~99.9999%), while also achieving a stiffness of more than 500mg at 70% humidity. It can effectively meet the requirements of high efficiency, low resistance and long life in high humidity environments, and can be widely used in operating room moisture-proof and antibacterial filtration, high-end household air purifiers and industrial air purification. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a multifunctional air filter material provided in an embodiment of the present invention; In the diagram, 100 is the hydrophobic isolation layer, 200 is the intermediate filter layer, and 300 is the support layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, this embodiment of the invention provides a multifunctional air filter material, which, from the windward side to the leeward side, sequentially includes a hydrophobic isolation layer 100, an intermediate filter layer 200, and a support layer 300; wherein, the hydrophobic isolation layer 100 is a polytetrafluoroethylene (PTFE) stretched membrane; the intermediate filter layer 200 is at least one of a PTFE stretched membrane, a thermoplastic polyurethane membrane, or a nanofiber membrane; the support layer 300 is a modified moisture-sensitive nonwoven fabric; and the pore size of the intermediate filter layer is smaller than that of the hydrophobic isolation layer.

[0025] In this embodiment of the invention, the multifunctional air filter material adopts a three-layer functional structure arranged sequentially from the windward side to the leeward side. Specifically, a polytetrafluoroethylene (PTFE) stretched membrane is used as a hydrophobic isolation layer, utilizing its inherent hydrophobic properties and large pore size to achieve pre-filtration of coarse particles. The middle filter layer uses a membrane material with a finer pore size, which effectively intercepts ultrafine particles through its microporous structure, balancing air resistance while ensuring extremely high filtration efficiency. The leeward side uses a modified moisture-sensitive nonwoven fabric as a support layer, which actively manages moisture through its surface properties in high humidity environments, thereby protecting the filtration performance of the internal core material and the stability of the support structure. Thus, compared to traditional glass fiber air filter paper, the filter material in this invention maintains the advantages of high efficiency and low resistance (pressure drop increase <10%, filtration efficiency of 99.995%~99.9999%), while also achieving a stiffness of more than 500mg at 70% humidity. It can effectively meet the requirements of high efficiency, low resistance and long life in high humidity environments, and can be widely used in operating room moisture-proof and antibacterial filtration, high-end household air purifiers and industrial air purification.

[0026] According to some preferred embodiments, the pore size of the hydrophobic barrier layer is 5~10μm (e.g., 5μm, 6μm, 7μm, 8μm, 9μm or 10μm); the pore size of the intermediate filter layer is 0.1~0.6μm (e.g., 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm or 0.6μm); and the basis weight of the support layer is 30~120g / m³. 2 (For example, it can be 30g / m 2 50g / m 2 80g / m2 100g / m 2 Or 120g / m 2 ).

[0027] In this embodiment of the invention, by synergistically controlling the pore size of the hydrophobic isolation layer and the intermediate filter layer, as well as the weight of the support layer, it is beneficial to ensure that the air filter material has both good filtration performance and a long service life. The hydrophobic isolation layer, as the windward side of the air filter material (filter media), uses the aforementioned pore size to effectively intercept large particles and droplets, preventing premature clogging of the subsequent precision intermediate layer, thereby significantly extending the service life of the entire filter material. The intermediate filter layer, as the main filter layer, by strictly controlling its pore size within the aforementioned smaller range, can accurately capture ultrafine particles, ensuring the filter material has excellent filtration performance. Furthermore, it can work synergistically with the hydrophobic isolation layer to form a gradient filtration from coarse to fine, ensuring that the filter material has both excellent filtration efficiency and filtration performance. Further, the aforementioned weight of the support layer ensures that the filter material does not deform or break when subjected to airflow impact and humidity changes. Simultaneously, its modified hydrophobic properties effectively resist moisture penetration, effectively preventing structural collapse and support failure caused by moisture absorption.

[0028] According to some preferred embodiments, the modified moisture-sensitive nonwoven fabric is prepared by the following method: (1) Zirconium isopropoxide and acetylacetone are stirred and mixed to obtain a first mixed solution; the mixed solvent and nanoparticles are mixed evenly to obtain a second mixed solution; (2) Under continuous stirring, the second mixed solution is added dropwise to the first mixed solution, and after mixing and reaction, a composite sol is obtained; the nonwoven fabric is immersed in the composite sol for impregnation and lifting, and after drying and shaping, the modified moisture-sensitive nonwoven fabric is obtained.

[0029] According to some preferred embodiments, in step (1), the nanoparticles are polyvinylidene fluoride nanoparticles or polytetrafluoroethylene nanoparticles; the mixed solvent is N,N-dimethylformamide and water, and the volume ratio of N,N-dimethylformamide and water is (7~9):1.

[0030] In this embodiment of the invention, zirconium isopropoxide and acetylacetone are first used to form a mixed sol. Then, a certain type and amount of nanoparticles are introduced into the sol and ultrasonically dispersed to form a stable, non-precipitated composite sol. The composite sol is then used to coat and modify nonwoven fabric by dip-coating. During the film formation process, the composite sol can form a transparent three-dimensional network gel film coating on the surface of the nonwoven fabric fibers. The nanoparticles can significantly increase the adhesion between the coating and the substrate through the bridging effect, ensuring that the coating is stable and does not fall off in complex environments. In addition, in high humidity environments, the coating can actively manage moisture through its surface hygroscopic physical properties, effectively maintaining the stability of the support structure. At the same time, it has a certain degree of chemical inertness, which can protect the filtration performance of the internal core materials in complex environments.

[0031] According to some preferred embodiments, in step (1), the volume ratio of zirconium isopropoxide to acetylacetone is (3~4):1 by mass percentage; the content of the nanoparticles accounts for 0.1-0.6% of the mass of the mixed solvent (for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or 0.6%) by mass percentage; in step (2), the reaction temperature is 30~35℃ and the time is 20~30min.

[0032] According to some preferred embodiments, in step (2), the nonwoven fabric is at least one of PE nonwoven fabric, PET nonwoven fabric, and PE / PET core-sheath structure nonwoven fabric, with a basis weight of 30~120g / m². 2 .

[0033] In this embodiment of the invention, by synergistically designing the mass concentration of the composite sol and the basis weight of the nonwoven fabric, it is beneficial to effectively control the micropores of the nonwoven fabric while imparting excellent moisture sensitivity, avoiding excessive clogging, and maintaining good air permeability and low filtration resistance. Experiments of this invention have confirmed that if the mass concentration of the composite sol is too low, it will lead to uneven particle coverage on the surface of the nonwoven fabric, failing to form a complete moisture-sensitive coating; while if the mass concentration of the composite sol is too high, it is prone to excessive particle accumulation, clogging the inherent pore structure of the nonwoven fabric, thus adversely affecting filtration performance.

[0034] According to some preferred embodiments, in step (2), the nonwoven fabric is fixed on an impregnation and lifting machine, and first impregnated in the composite sol at a speed of 8~10mm / s (e.g., 8mm / s, 9mm / s or 10mm / s) for 1~2 minutes (e.g., 1 minute, 1.5 minutes or 2 minutes). Then, the nonwoven fabric is lifted from the composite sol and suspended in the air at a speed of 15~18mm / s (e.g., 15mm / s, 16mm / s, 17mm / s or 18mm / s) for 1~2 minutes (e.g., 1 minute, 1.5 minutes or 2 minutes). After repeating 2~3 times, a moisture-sensitive coating is formed on the nonwoven fabric. The drying and shaping temperature is 35-40℃ (e.g., 35℃, 38℃, or 40℃), the humidity is 60-70% (e.g., 60%, 62%, 65%, 68%, or 70%), and the time is 2-3 hours (e.g., 2 hours, 2.5 hours, or 3 hours).

[0035] In this embodiment of the invention, during the preparation of the modified moisture-sensitive nonwoven fabric, the nonwoven fabric is impregnated in a composite sol for impregnation and lifting. By reasonably controlling the speed of impregnation and lifting, it is beneficial to form a uniform and firm moisture-sensitive coating on the entire surface of the nonwoven fabric while preserving the open-pore structure of the nonwoven fabric to the maximum extent. This helps to ensure the material's moisture-sensitive performance, low filtration resistance, and high air permeability.

[0036] This invention also provides a method for preparing the multifunctional air filter material described in any one of the above claims, the method comprising the following steps: S1: Polyethylene adhesive is sprayed onto one side of the modified moisture-sensitive nonwoven fabric and cured to obtain a support layer; wherein the amount of polyethylene adhesive sprayed is 5~10g / m². 2 (For example, it can be 5g / m 2 6g / m 2 7g / m 2 8g / m 2 or 10g / m 2 ); S2: Place the intermediate filter layer and the hydrophobic isolation layer sequentially on the side of the support layer sprayed with polyethylene adhesive, and then use a hot press roller to composite the multi-layer material to obtain the multifunctional air filter material.

[0037] According to some preferred embodiments, the hot press roller includes a rubber roller and a steel roller that are parallel to each other; wherein, the hydrophobic isolation layer is in contact with the rubber roller, and the support layer is in contact with the steel roller; According to some preferred embodiments, the temperature of the hot press roller is 110~130℃ (e.g., 110℃, 115℃, 120℃, 125℃ or 130℃), the pressure is 0.05~1MPa (e.g., 0.05MPa, 0.1MPa, 0.5MPa, 0.8MPa or 1MPa), and the combined speed is 5~30m / min (e.g., 5m / min, 8m / min, 10m / min, 15m / min, 20m / min, 25m / min or 30m / min).

[0038] In this embodiment of the invention, one surface of the modified moisture-sensitive nonwoven fabric is sprayed with polyethylene adhesive and then cured. An intermediate filter layer and a hydrophobic barrier layer are then sequentially placed on this surface. The resulting three-layer structure is simultaneously passed between two parallel hot-rolling rollers. A rubber roller contacts the hydrophobic barrier layer, utilizing its elastic deformation to ensure uniform pressure distribution and avoid affecting the microporous structure of the hydrophobic barrier layer. A steel roller contacts the modified moisture-sensitive nonwoven fabric surface, providing stable heat conduction. Simultaneously, the pressure, roller surface temperature, and composite speed of the hot-rolling rollers are controlled to melt the polyethylene adhesive layer on the nonwoven fabric surface, ensuring a strong interfacial bond between the layers. This results in a high-efficiency air filter material that combines high-strength interlayer bonding, excellent filtration performance, and superhydrophobicity.

[0039] To more clearly illustrate the technical solution and advantages of the present invention, the following detailed description of a multifunctional air filter material and its preparation method is provided through several embodiments.

[0040] Example 1: (1) Preparation of modified moisture-sensitive nonwoven fabric: nonwoven fabric (PET nonwoven fabric, basis weight 30g / m) 2 Place them in acetone, anhydrous ethanol and deionized water in sequence and ultrasonically clean them for 10 minutes each using a 400W ultrasonic cleaner; Zirconium isopropoxide (Zr) and acetylacetone (AcAc) (volume ratio 3.5:1) were mixed to obtain a first mixed solution. N,N-dimethylformamide (DMF), deionized water, and polytetrafluoroethylene nanoparticles were mixed evenly to obtain a second mixed solution. The volume ratio of deionized water to N,N-dimethylformamide (DMF) was 9:1, and the content of polytetrafluoroethylene nanoparticles accounted for 0.5% of the mass of deionized water and N,N-dimethylformamide (DMF). (2) Under continuous stirring, the second mixed solution was added dropwise to the first mixed solution, and the reaction temperature was controlled at 30℃ for 30 min to obtain a composite sol. The cleaned nonwoven fabric was fixed on an impregnation and lifting machine. First, it was impregnated in the composite sol at a speed of 10 mm / s for 1 min, and then the nonwoven fabric was lifted from the composite sol and suspended for 1 min at a speed of 15 mm / s. The same impregnation speed and lifting and suspension speed were repeated twice. The fabric was then taken out and dried and shaped for 2 h at a temperature of 35℃ and a humidity of 65% to obtain the modified moisture-sensitive nonwoven fabric. S1: Polyethylene adhesive is sprayed onto one side of the modified moisture-sensitive nonwoven fabric and cured to obtain a support layer; wherein the amount of polyethylene adhesive sprayed is 8 g / m². 2 ; S2: Place an intermediate filter layer (PTFE stretched film with a pore size of 0.5μm) and a hydrophobic isolation layer (PTFE stretched film with a pore size of 5μm) sequentially on the side of the support layer where polyethylene adhesive is sprayed. Pass the three-layer structure formed simultaneously between two parallel hot rolling rollers. The rubber roller contacts the hydrophobic isolation layer, and the steel roller contacts the modified moisture-sensitive nonwoven fabric surface. The pressure is 1MPa, the roller surface temperature is 120℃, and the composite speed is 10m / min to obtain a multifunctional air filter material.

[0041] Example 2: (1) Preparation of modified moisture-sensitive nonwoven fabric: nonwoven fabric (PET nonwoven fabric, basis weight 120g / m) 2 Place them in acetone, anhydrous ethanol and deionized water in sequence and ultrasonically clean them for 10 minutes each using a 400W ultrasonic cleaner; Zirconium isopropoxide (Zr) and acetylacetone (AcAc) (volume ratio 3.5:1) were mixed to obtain a first mixed solution; N,N-dimethylformamide (DMF), deionized water, and polytetrafluoroethylene nanoparticles were mixed evenly to obtain a second mixed solution; wherein the volume ratio of deionized water to N,N-dimethylformamide (DMF) was 9:1, and the content of polytetrafluoroethylene nanoparticles accounted for 0.1% of the mass of deionized water and N,N-dimethylformamide (DMF); (2) Under continuous stirring, the second mixed solution was added dropwise to the first mixed solution. The reaction temperature was controlled at 30℃ and the time was 30min to obtain the composite sol. The cleaned nonwoven fabric was fixed on the impregnation and lifting machine. First, it was impregnated in the composite sol at a speed of 8mm / s for 1min. Then, the nonwoven fabric was lifted from the composite sol and suspended for 1min at a speed of 18mm / s. The same impregnation speed and lifting and suspension speed were repeated twice. The fabric was then taken out and dried and shaped for 2h at a temperature of 35℃ and a humidity of 65% to obtain the modified moisture-sensitive nonwoven fabric. S1: Polyethylene adhesive is sprayed onto one side of the modified moisture-sensitive nonwoven fabric and cured to obtain a support layer; wherein the amount of polyethylene adhesive sprayed is 5 g / m². 2 ; S2: A middle filter layer (PTFE stretched membrane with a pore size of 0.5μm) and a hydrophobic isolation layer (thermoplastic polyurethane membrane with a pore size of 8μm) are placed sequentially on the side of the support layer where polyethylene adhesive is sprayed. The three-layer structure is then passed between two parallel hot rollers. The rubber roller contacts the hydrophobic isolation layer, while the steel roller contacts the modified moisture-sensitive nonwoven fabric surface. The pressure is 0.5MPa, the roller surface temperature is 120℃, and the composite speed is 5m / min to obtain a multifunctional air filter material.

[0042] Example 3: Example 3 is basically the same as Example 1, except that: in step (1), in the composite sol, hydrophobic nanoparticles are mixed with zirconium isopropoxide (Zr) and acetylacetone (AcAc) (volume ratio 3.5:1) to obtain a first mixed solution; N,N-dimethylformamide (DMF), deionized water and polytetrafluoroethylene nanoparticles are mixed evenly to obtain a second mixed solution; wherein, the volume ratio of deionized water and N,N-dimethylformamide (DMF) is 9:1, and the content of polytetrafluoroethylene nanoparticles accounts for 0.6% of the mass of deionized water and N,N-dimethylformamide (DMF); under continuous stirring, the second mixed solution is added dropwise to the first mixed solution, the reaction temperature is controlled at 30℃, and the time is 30min to obtain the composite sol.

[0043] Example 4: Example 4 is basically the same as Example 1, except that in step (2), the cleaned nonwoven fabric is fixed on the impregnation and lifting machine. First, it is impregnated in the composite sol at a speed of 15 mm / s for 1 min, and then the nonwoven fabric is lifted from the composite sol at a speed of 10 mm / s for 1 min. The same impregnation speed and lifting and suspension speed are repeated twice. The fabric is then taken out and dried and shaped for 2 h in an environment with a temperature of 35℃ and a humidity of 65% to obtain the modified moisture-sensitive nonwoven fabric.

[0044] Example 5: Example 5 is basically the same as Example 1, except that in step S2, the temperature of the hot press roller is 130°C, the pressure is 2MPa, and the composite speed is 10m / min.

[0045] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that in step S2, there is an intermediate filter layer (polytetrafluoroethylene stretched membrane with a pore size of 0.5 μm) and a hydrophobic isolation layer (polytetrafluoroethylene stretched membrane with a pore size of 0.5 μm).

[0046] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that in step (2), the cleaned nonwoven fabric is immersed in the composite sol for 1 minute, and then taken out and dried and shaped for 2 hours in an environment with a temperature of 35°C and a humidity of 65% to obtain the modified moisture-sensitive nonwoven fabric.

[0047] Comparative Example 3 Comparative Example 3 is basically the same as Example 1, except that in step (1), the composite sol is replaced with a nanoparticle suspension. Specifically, the nanoparticles (polyvinylidene fluoride nanoparticles) are added to the solvent (N,N-dimethylformamide) and ultrasonically mixed to obtain a nanoparticle suspension with a mass concentration of 0.5%.

[0048] Comparative Example 4 Comparative Example 4 is basically the same as Example 1, except that in step S1, the support layer is ordinary nonwoven fabric (PE / PET nonwoven fabric, basis weight 120g / m²). 2 ).

[0049] Comparative Example 5 Comparative Example 5 is basically the same as Example 1, except that steps (1) and (2) are omitted. In step S1, unmodified PET nonwoven fabric with a basis weight of 30 g / m² is used. 2 As a support layer.

[0050] The performance of the multifunctional air filter material samples provided in the examples and comparative examples was tested, and the test results are shown in Table 1 below: Add corresponding performance testing standards or methods; filtration efficiency and filtration resistance are tested according to TSI3140 (salt spray method); pressure drop increase: the increase in filtration resistance of nonwoven fabric before and after superhydrophobic modification is measured under the same substrate and preparation process; stiffness is tested using a Gurley stiffness meter.

[0051] Table 1 As shown in Table 1, the multifunctional air filter material prepared by this invention maintains the advantages of high efficiency and low resistance (pressure drop increase <10%, filtration efficiency of 99.995%~99.9999%), while achieving a stiffness of more than 500mg under 70% humidity, thus effectively meeting the requirements of high efficiency, low resistance and long life of air filter materials in hydrophobic high humidity environments.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate 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, From the windward side to the leeward side, the filter material sequentially includes a hydrophobic isolation layer, an intermediate filter layer, and a support layer; wherein, the hydrophobic isolation layer is a polytetrafluoroethylene (PTFE) stretched membrane; the intermediate filter layer is at least one of a PTFE stretched membrane, a thermoplastic polyurethane membrane, or a nanofiber membrane; the support layer is a modified moisture-sensitive nonwoven fabric; the pore size of the intermediate filter layer is smaller than that of the hydrophobic isolation layer.

2. The multifunctional air filter material according to claim 1, characterized in that, The hydrophobic isolation layer has a pore size of 5~10μm; the intermediate filter layer has a pore size of 0.1~0.6μm; and the support layer has a basis weight of 30~120g / m³. 2 .

3. The multifunctional air filter material according to claim 1, characterized in that, The modified moisture-sensitive nonwoven fabric is prepared by the following method: (1) Zirconium isopropoxide and acetylacetone are stirred and mixed to obtain a first mixed solution; the mixed solvent and nanoparticles are mixed evenly to obtain a second mixed solution; (2) Under continuous stirring, the second mixed solution is added dropwise to the first mixed solution, and after mixing and reaction, a composite sol is obtained; the nonwoven fabric is immersed in the composite sol for impregnation and lifting, and after drying and shaping, the modified moisture-sensitive nonwoven fabric is obtained.

4. The multifunctional air filter material according to claim 3, characterized in that, In step (1), the nanoparticles are polyvinylidene fluoride nanoparticles or polytetrafluoroethylene nanoparticles. The mixed solvent is N,N-dimethylformamide and water; the volume ratio of N,N-dimethylformamide and water is (7~9):

1.

5. The multifunctional air filter material according to claim 3, characterized in that, In step (1), the volume ratio of zirconium isopropoxide to acetylacetone is (3~4):1; The nanoparticles comprise 0.1-0.6% of the mass of the mixed solvent, by weight percentage. Preferably, in step (2), the reaction temperature is 30~35℃ and the time is 20~30min.

6. The multifunctional air filter material according to claim 3, characterized in that, In step (2), the nonwoven fabric is at least one of PE nonwoven fabric, PET nonwoven fabric, and PE / PET core-sheath structure nonwoven fabric, with a basis weight of 30~120g / m². 2 .

7. The multifunctional air filter material according to claim 3, characterized in that, In step (2), the nonwoven fabric is fixed on the dip-lifting machine and first dipped in the composite sol at a speed of 8~10mm / s for 1~2min. Then, the nonwoven fabric is lifted from the composite sol and suspended in the air at a speed of 15~18mm / s for 1~2min. After repeating 2~3 times, a moisture-sensitive coating is formed on the nonwoven fabric.

8. The multifunctional air filter material according to claim 3, characterized in that, In step (2), the drying and shaping temperature is 35~40℃, the humidity is 60~70%, and the time is 2~3h.

9. A method for preparing a multifunctional air filter material according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: S1: Polyethylene adhesive is sprayed onto one side of the modified moisture-sensitive nonwoven fabric and cured to obtain a support layer; wherein the amount of polyethylene adhesive sprayed is 5~10g / m². 2 ; S2: Place the intermediate filter layer and the hydrophobic isolation layer sequentially on the side of the support layer sprayed with polyethylene adhesive, and then use a hot press roller to composite the multi-layer material to obtain the multifunctional air filter material.

10. The preparation method according to claim 9, characterized in that, The hot press roller includes a rubber roller and a steel roller that are parallel to each other; wherein, a hydrophobic isolation layer is in contact with the rubber roller, and a support layer is in contact with the steel roller; and / or The temperature of the hot press roller is 110~130℃, the pressure is 0.05~1MPa, and the combined speed is 5~30m / min.

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