A high-efficiency low-resistance three-dimensional microsphere structure micro-nano fiber composite air filtration material and a preparation method thereof

Abstract

The application discloses a kind of high efficiency low resistance three-dimensional microsphere structure micro-nano fiber composite air filtration material, including micro-nano fiber membrane body, and the micro-nano fiber membrane is formed by the two-dimensional close, three-dimensional loose stereoscopic skeleton structure of spinning polymer micro-nano fiber and several micro-nano balls embedded in the stereoscopic skeleton structure.It comprises the following steps: (1), the spinning raw material is dissolved in 88% solvent by mass fraction, to obtain spinning solution;(2), PVA powder and micro-nano ball particles are mixed into ethanol solution;(3), the solution prepared in step (2) is ultrasonic, to obtain microsphere spraying suspension;(4), through parallel double-nozzle air spraying spinning machine, synchronous air spraying spinning and airflow spraying are carried out, to obtain three-dimensional microsphere structure micro-nano fiber composite wet film;(5) drying.The application can make the gap between fibers more closely, quickly and effectively intercept fine particles, and can also improve porosity, effectively reduce air resistance and improve filtration efficiency.

Description

Technical Field

[0001] This invention belongs to the field of functional composite filter materials technology, and particularly relates to a high-efficiency, low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material and its preparation method. Background Technology

[0002] The purpose of air filtration is primarily to effectively capture and intercept harmful particles, gases, bacteria, and viruses in polluted gases using air filter materials, thereby purifying the air or protecting human health. Existing high-efficiency air filtration technologies mainly include electrostatic dust collection filtration, electrostatic reinforced fiber filtration, stretched membrane filtration, and fiber filtration. Among these, fiber filtration technology has become the mainstream air filtration technology due to its advantages such as good filtration performance and strong environmental adaptability. However, fiber filter materials on the market generally suffer from low filtration efficiency and excessive air resistance, making it difficult to maintain good performance in practical applications.

[0003] In recent years, nanofiber filter materials have been widely used due to their small fiber diameter and large specific surface area. However, nanofibers still suffer from the problem of dense structure. By doping with microspheres to form layered and multilayer composite structures, low-air-resistance nanofiber filters can be achieved. Currently, the main methods for producing microsphere nanofibers are electrospinning and electrostatic spraying. In recent years, air-jet spinning has emerged as a fiber production technology that uses high-speed gas instead of a high electric field. Although electrospinning has received more attention and has wider applications, it requires high voltage, raising safety concerns. Furthermore, its production rate, output, and equipment operation complexity are all inferior to air-jet spinning. The existing technologies for composite materials used in air filtration are as follows:

[0004] CN113368712A discloses a high-efficiency air filtration composite nanofiber membrane and its preparation method, belonging to the field of membrane separation technology. By doping ZIF-8 nanocrystals into PEI spinning solution and preparing composite nanofibers via electrospinning, the morphology and structure of the nanofibers change, the fiber diameter decreases, numerous nanoscale protrusions appear on the surface of the nanofibers, and the surface roughness of the fibers increases significantly. Furthermore, the addition of ZIF-8 significantly increases the specific surface area and adsorption capacity, thus significantly improving air filtration performance. It can efficiently filter and capture small particulate matter such as PM2.5 and PM10, and possesses thermal stability at 200℃ and strong hydrophobicity with a water contact angle of 136°.

[0005] CN113457477A discloses a nanofiber filter membrane, its preparation method, and its application. The nanofiber filter membrane comprises polymer fibers, electret nanoparticles attached to the surface of the polymer fibers, and ZnAc·2H₂O. ZnAc·2H₂O synergistically enhances the electret effect of the electret nanoparticles, enabling the nanofiber membrane to more efficiently capture small-diameter aerosols and exhibit low filtration resistance, thus possessing high efficiency and low resistance. Furthermore, it effectively improves the antibacterial properties of the nanofiber membrane, making it suitable for use in protective equipment such as masks and protective clothing.

[0006] CN109012218A discloses a four-layer composite micro / nanofiber air filter membrane. The four fiber layers are characterized by comprising, from bottom to top, a nonwoven fabric substrate layer, an electrospun micron-sized fiber layer, an electrospun beaded nanofiber layer, and an electrospun ultrafine nanofiber layer. The preparation method involves sequentially depositing three layers of fiber filter membranes of different sizes and morphologies on the surface of a nonwoven fabric substrate using electrospinning technology. The key feature is that the fiber diameter and pore size of each fiber membrane layer gradually decrease from bottom to top, exhibiting a gradient distribution. The air filter membrane prepared by this invention achieves a filtration efficiency of over 99.9% for 300nm sodium chloride particles at a wind speed of 5cm / s, with a pressure resistance of less than 40Pa, demonstrating excellent filtration performance and promising application prospects.

[0007] As can be seen from the aforementioned patented technologies, there are currently many types of membrane materials used for air filtration, with varying structures and manufacturing processes. Although improving the surface roughness of fibers increases the specific surface area, resulting in stronger adsorption capacity and antibacterial and hydrophobic effects, the dense structure of nanofiber membranes leads to excessive air resistance, resulting in low overall filtration efficiency and a lack of sustained filtration performance in practical applications. Therefore, how to achieve both tighter inter-fiber gaps for rapid and effective particle interception and increased porosity to effectively reduce air resistance and improve filtration efficiency has become a pressing problem for engineers in the field of air filtration materials. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the technical problem to be solved by this invention is to provide a high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filter material and its preparation method, which has a loose and three-dimensional structure that can make the gaps between fibers more compact, quickly and effectively intercept fine particles, and improve porosity, effectively reduce air resistance, and improve filtration efficiency.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a high-efficiency, low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material, comprising a micro-nanofiber membrane body, wherein the micro-nanofiber membrane is composed of a two-dimensional compact and three-dimensional loose three-dimensional skeleton structure formed by spinning polymer micro-nanofibers and a number of micro-nanospheres embedded in the three-dimensional skeleton structure. The diameter of the micro-nanofibers is 465.34-648.27 nm, the particle size of the micro-nanospheres is 0.05-15 μm, the mass ratio of micro-nanospheres to composite air filter material is 10-40%, the porosity is 89.94%-91.34%, and the air permeability is 245.36-276.43 L / (m³). 2 *s), with an air resistance of 98-108 Pa.

[0010] The aforementioned high-efficiency, low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material has nanoscale microspheres accounting for 40-60% of the total microsphere mass, and micron-scale microspheres accounting for 60-40% of the total microsphere mass.

[0011] The aforementioned high-efficiency, low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material, wherein the micro-nanospheres are hydrophilic polydisperse microspheres, and the micro-nanospheres are one or more of silica, polystyrene, polymethyl methacrylate, and titanium dioxide.

[0012] The aforementioned high-efficiency, low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material is composed of micron-sized microspheres and nano-sized microspheres, wherein the particle size of the nano-sized microspheres is 50-300 nm, and the particle size of the micron-sized microspheres is 3 μm-15 μm.

[0013] A method for preparing a three-dimensional microsphere structured micro / nanofiber composite air filter material includes the following steps:

[0014] I. Preparation of spinning solution:

[0015] (1) Dissolve the spinning raw material in a solvent with a mass fraction of 88%, and stir magnetically for 12-24 hours at room temperature until completely dissolved to obtain the spinning solution for later use;

[0016] II. Preparation of microsphere spraying suspension:

[0017] (2) Mix PVA powder and micro / nanospheres into an ethanol solution and stir thoroughly at 40°C for 4 hours;

[0018] (3) The solution obtained in step (2) is ultrasonically treated at 25°C for 1-2 hours to ensure that the PVA is completely dissolved and the micro-nanospheres are fully dispersed, so as to obtain a microsphere spraying suspension with a total microsphere mass percentage of 1-5%.

[0019] III. Air-jet spinning and spraying:

[0020] (4) The spinning solution obtained in step (1) and the microsphere spraying suspension obtained in step (2) are simultaneously air-jet spun and air-jet sprayed through a parallel dual-nozzle air-jet spinning machine to obtain a three-dimensional microsphere structure micro-nano fiber composite wet film.

[0021] (5) The three-dimensional microsphere structure micro-nanofiber composite wet film is dried at a temperature of 60°C for 3 minutes to obtain the three-dimensional microsphere structure micro-nanofiber composite air filter material.

[0022] In the preparation method of the above-mentioned high-efficiency and low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material, in step (1), the spinning raw material is one or more of polyamide 6, polyamide 66, polyurethane, polyacrylonitrile, polyimide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride or polyoxyethylene.

[0023] In the preparation method of the above-mentioned high-efficiency and low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material, in step (1), the molecular weight of the spinning raw material is 50,000-200,000, the mass percentage of the spinning raw material in the spinning solution is 8.2-10%, and the solvent is one or more of formic acid, ethanol or N,N-dimethylformamide.

[0024] The preparation method of the above-mentioned high-efficiency and low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material, in step (2), the PVA concentration in the microsphere spraying suspension is 5wt%.

[0025] The preparation method of the above-mentioned high-efficiency and low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material is as follows: In step (3), the total mass percentage of microspheres in the microsphere spraying suspension is 2.5%.

[0026] In the preparation method of the above-mentioned high-efficiency and low-resistance three-dimensional microsphere structure micro-nanofiber composite air filter material, in step (4), the inner diameter of the needle of the parallel dual-nozzle air-jet spinning machine is 500 μm, the spinning solution injection rate is 1-2 ml / h, the injection speed of the microsphere spray suspension is 1-4 mL / h, the spinning air pressure is 0.08-0.12 MPa, the spraying air pressure is 0.08-0.12 MPa, the distance from the spinneret to the receiving curtain is 35 cm, the collector winding speed is 700 r / h, the ambient temperature is 20-30℃, and the ambient humidity is 35%-60%.

[0027] The advantages of this invention—a high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filter material and its preparation method—are as follows: This invention employs a combination of airflow spraying and airflow spinning to develop a two-dimensional compact and three-dimensional loose microsphere structure. The scaffold nanofibers form a stable framework, while the microspheres increase the overall porosity of the fibers, significantly reducing pressure drop. The nanospheres are dispersed between the nanofibers, making the interfiber gaps more compact and forming a hierarchical nanostructure, which increases the capture efficiency of PM particles. This invention embeds nano / microspheres into the nanofiber framework through a one-step multi-jet airflow spinning process. By controlling the amount of microspheres and the ratio of micron-sized to nano-sized microspheres, filter materials with different filtration requirements can be flexibly adjusted. This invention simultaneously achieves good filtration performance and low air resistance, and the preparation process is simple, highly controllable, and highly efficient, possessing significant social and economic value in practical industrial applications. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the three-dimensional microsphere structure micro-nanofiber composite air filter material of the present invention;

[0029] Figure 2 Flowchart of the preparation method of the composite air filter material of the present invention;

[0030] Figure 3 This is a scanning electron microscope image of the composite air filter material prepared in Example 1 of the present invention;

[0031] Figure 4 This is a longitudinal section scanning electron microscope image of the composite air filter material prepared in Example 1 of the present invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] In this invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order. The term "multiple" means "two or more".

[0034] like Figure 1 , Figure 3 , Figure 4As shown, a high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filter material includes a micro / nanofiber membrane body. The micro / nanofiber membrane is composed of a two-dimensional compact, three-dimensional loose skeleton structure formed by spun polymer micro / nanofibers and several micro / nanospheres embedded within the skeleton structure. The micro / nanofibers have a diameter of 465.34-648.27 nm, the micro / nanospheres have a particle size of 0.05-15 μm, the micro / nanospheres account for 10-40% of the composite air filter material by mass, the porosity is 89.94%-91.34%, and the air permeability is 245.36-276.43 L / (m³). 2 *s), with an air resistance of 98-108 Pa.

[0035] The nanospheres comprise 40-60% of the total microsphere mass, while the micron-sized microspheres comprise 40-60%. The micro- and nanospheres are hydrophilic polydisperse microspheres, and are composed of one or more of the following materials: silica, polystyrene, polymethyl methacrylate, and titanium dioxide. The micro- and nanospheres consist of micron-sized and nano-sized microspheres, with the nanospheres having a particle size of 50-300 nm and the micron-sized microspheres having a particle size of 3 μm-15 μm.

[0036] like Figure 2 As shown, the preparation method of the three-dimensional microsphere structure micro / nanofiber composite air filter material of the present invention includes the following steps:

[0037] I. Preparation of spinning solution:

[0038] (1) Dissolve the spinning raw material in a solvent with a mass fraction of 88%, and stir magnetically for 12-24 hours at room temperature until completely dissolved to obtain the spinning solution for later use;

[0039] II. Preparation of microsphere spraying suspension:

[0040] (2) Mix PVA powder and micro / nanospheres into an ethanol solution and stir thoroughly at 40°C for 4 hours;

[0041] (3) The solution obtained in step (2) is ultrasonically treated at 25°C for 1-2 hours to ensure that the PVA is completely dissolved and the micro-nanospheres are fully dispersed, so as to obtain a microsphere spraying suspension with a total microsphere mass percentage of 1-5%.

[0042] III. Air-jet spinning and spraying:

[0043] (4) The spinning solution obtained in step (1) and the microsphere spraying suspension obtained in step (2) are simultaneously air-jet spun and air-jet sprayed through a parallel dual-nozzle air-jet spinning machine to obtain a three-dimensional microsphere structure micro-nano fiber composite wet film.

[0044] (5) The three-dimensional microsphere structure micro-nanofiber composite wet film is dried at a temperature of 60°C for 3 minutes to obtain the three-dimensional microsphere structure micro-nanofiber composite air filter material.

[0045] The spinning raw material is one or more of polyamide 6, polyamide 66, polyurethane, polyacrylonitrile, polyimide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride, or polyethylene oxide. The molecular weight of the spinning raw material is 50,000-200,000, and the mass percentage of the spinning raw material in the spinning solution is 8.2-10%. The solvent is one or more of formic acid, ethanol, or N,N-dimethylformamide. The PVA concentration in the microsphere spraying suspension is 5 wt%. In step (4), the inner diameter of the spinning needle 3 and the spraying needle 4 of the parallel dual-nozzle air-jet spinning machine is 500 μm. The injection rate of the spinning liquid injector 1 is 1-2 ml / h, the injection speed of the microsphere spraying suspension injector 2 is 1-4 mL / h, the spinning air pressure is 0.08-0.12 MPa, the spraying air pressure is 0.08-0.12 MPa, the distance from the spinneret to the receiving curtain 5 is 35 cm, the collector winding speed is 700 r / h, the ambient temperature is 20-30℃, and the ambient humidity is 35%-60%.

[0046] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0047] Example 1

[0048] The present invention discloses a method for preparing a three-dimensional microsphere structured micro / nanofiber composite air filter material, comprising the following steps:

[0049] (1) Nylon 6 was dissolved in an 88% formic acid aqueous solution and magnetically stirred for 12-24 hours at room temperature until completely dissolved to obtain a spinning solution. PVA powder and silica microspheres were mixed into an ethanol solution and stirred thoroughly at 40°C for 4 hours. Then, the mixture was ultrasonically treated at 25°C for 1-2 hours to ensure complete dissolution of PVA and thorough dispersion of microspheres and nanospheres to obtain a microsphere spraying suspension with a PVA concentration of 5 wt%.

[0050] The spinning solution contains 10% nylon 6 by mass.

[0051] Microsphere spraying suspension: The mass percentage of silica nanospheres is 1%, and the mass percentage of silica microspheres is 1.5%.

[0052] (2) The spinning solution was simultaneously air-jet spun and sprayed onto the microspheres using an air-jet spinning machine to obtain a three-dimensional microsphere-structured micro / nanofiber composite wet film. The spinning parameters were as follows: needle inner diameter 500 μm, spinning solution injection rate 2 ml / h, microsphere spraying suspension injection rate 4 mL / h, spinning air pressure 0.1 MPa, spraying air pressure 0.1 MPa, spinning distance 35 cm, collector winding speed 700 r / h, ambient temperature 20℃, and humidity 55%.

[0053] (3) After spinning for 9 hours, the three-dimensional microsphere structure micro-nanofiber composite wet film was dried in an oven at 60°C for 3 minutes to obtain the final three-dimensional microsphere structure micro-nanofiber composite air filter material.

[0054] In this composite air filter material, the fiber diameter is 465.34 nm and the material thickness is 159.63 μm. The nano-sized microspheres have a particle size of 50 nm, and the micron-sized microspheres have a particle size of 3 μm. The nano-sized microspheres account for 50% of the total microsphere mass, and the micron-sized microspheres account for 50% of the total microsphere mass. The micro / nanospheres constitute 10% of the composite air filter material by mass, with a porosity of 91.34% and an air permeability of 276.43 L / (m³). 2 *s), air resistance is 98Pa, and filtration efficiency is 99.93%.

[0055] Comparative Example 1

[0056] The fiber composite membrane described in this comparative example differs from that in Example 1 only in that it does not contain micro / nanospheres. Its preparation method includes the following steps:

[0057] (1) Nylon 6 is dissolved in an aqueous solution of formic acid with a mass fraction of 88% to obtain a spinning solution, wherein the mass percentage of spinning solution to nylon 6 is 10%;

[0058] (2) The spinning solution is subjected to air-jet spinning and air-jet spraying through an air-jet spinning machine. The spinning parameters are as follows: the inner diameter of the needle is 500 μm, the injection rate is 2 ml / h, the spinning air pressure is 0.1 MPa, the spinning distance is 35 cm, the collector winding speed is 700 r / h, the ambient temperature is 20℃, and the humidity is 55%.

[0059] (3) After spinning for 9 hours, the wet fiber film was dried in an oven at 60°C for 3 minutes to obtain the composite fiber air filter material.

[0060] Example 2

[0061] The preparation method of the three-dimensional microsphere structure micro / nanofiber composite air filter material in this embodiment includes the following steps:

[0062] (1) Nylon 6 and polyethylene oxide were dissolved in an 88% formic acid aqueous solution and magnetically stirred for 12-24 hours at room temperature until completely dissolved to obtain a spinning solution. PVA powder and silica microspheres were mixed into an ethanol solution and stirred thoroughly at 40°C for 4 hours. Then, the mixture was ultrasonically treated at 25°C for 1-2 hours to ensure complete dissolution of PVA and thorough dispersion of microspheres and nanospheres to obtain a microsphere spraying suspension with a PVA concentration of 5 wt%.

[0063] The spinning solution contains 8% nylon 6 and 0.3% polyethylene by mass.

[0064] Microsphere spraying suspension: The mass percentage of silica nanospheres is 0.5%, and the mass percentage of silica microspheres is 0.5%.

[0065] (2) The spinning solution was simultaneously air-jet spun and sprayed onto the microspheres using an air-jet spinning machine to obtain a three-dimensional microsphere-structured micro / nanofiber composite wet film. The spinning parameters were as follows: needle inner diameter 500 μm, spinning solution injection rate 1.5 ml / h, microsphere spraying suspension injection rate 3 mL / h, spinning air pressure 0.08 MPa, spraying air pressure 0.08 MPa, spinning distance 35 cm, collector winding speed 700 r / h, ambient temperature 25℃, and humidity 35%.

[0066] (3) After spinning for 9 hours, the three-dimensional microsphere structure micro-nanofiber composite wet film was dried in an oven at 60°C for 3 minutes to obtain the final three-dimensional microsphere structure micro-nanofiber composite air filter material.

[0067] In this composite air filter material, the fiber diameter is 648.27 nm and the material thickness is 185.49 μm. The nano-sized microspheres have a particle size of 150 nm, and the micron-sized microspheres have a particle size of 9 μm. The nano-sized microspheres account for 60% of the total microsphere mass, and the micron-sized microspheres account for 40%. The total mass ratio of micro- and nano-spheres in the composite air filter material is 25%, the porosity is 90.10%, and the air permeability is 262.21 L / (m³). 2 *s), air resistance is 104 Pa, filtration efficiency is 99.97%.

[0068] Comparative Example 2

[0069] The fiber composite membrane described in this comparative example differs from that in Example 2 only in that it does not contain micro / nanospheres. Its preparation method includes the following steps:

[0070] (1) Nylon 6 and polyethylene are dissolved in an 88% formic acid aqueous solution to obtain a spinning solution, wherein the mass percentage of nylon 6 in the spinning solution is 8% and the mass percentage of polyethylene is 0.3%.

[0071] (2) The spinning solution is subjected to air-jet spinning and air-jet spraying through an air-jet spinning machine. The spinning parameters are as follows: the inner diameter of the needle is 500 μm, the polymer solution injection rate is 1.5 ml / h, the spinning air pressure is 0.08 MPa, the spinning distance is 35 cm, the collector winding speed is 700 r / h, the ambient temperature is 25 ℃, and the humidity is 35%.

[0072] (3) After spinning for 9 hours, the wet fiber film was dried in an oven at 60°C for 3 minutes to obtain the composite fiber air filter material.

[0073] Example 3

[0074] The preparation method of the three-dimensional microsphere structure micro / nanofiber composite air filter material in this embodiment includes the following steps:

[0075] (1) Nylon 6 and polyethylene oxide were dissolved in an 88% formic acid aqueous solution and magnetically stirred for 12-24 hours at room temperature until completely dissolved to obtain a spinning solution. PVA powder and polystyrene microspheres were mixed into an ethanol solution and stirred thoroughly at 40°C for 4 hours. Then, the mixture was ultrasonically treated at 25°C for 1-2 hours to ensure complete dissolution of PVA and thorough dispersion of microspheres and nanospheres. The resulting microspheres were ultrasonically dispersed to obtain a microsphere spraying suspension with a PVA concentration of 5 wt%.

[0076] The spinning solution contains 8% nylon 6 and 0.2% polyethylene by mass.

[0077] Microsphere spraying suspension: Polystyrene nanospheres account for 2.5% by mass, and polystyrene microspheres account for 2.5% by mass.

[0078] (2) The spinning solution was simultaneously air-jet spun and sprayed onto the microspheres using an air-jet spinning machine to obtain a three-dimensional microsphere-structured micro / nanofiber composite wet film. The spinning parameters were as follows: needle inner diameter 500 μm, spinning solution injection rate 1 ml / h, microsphere spraying suspension injection rate 1 mL / h, spinning air pressure 0.12 MPa, spraying air pressure 0.12 MPa, spinning distance 35 cm, collector winding speed 700 r / h, ambient temperature 30℃, and humidity 60%.

[0079] (3) After spinning for 9 hours, the three-dimensional microsphere structure micro-nanofiber composite wet film was dried in an oven at 60°C for 3 minutes to obtain the final three-dimensional microsphere structure micro-nanofiber composite air filter material.

[0080] In this composite air filter material, the fiber diameter is 574.01 nm and the material thickness is 164.83 μm. The nano-sized microspheres have a particle size of 300 nm, and the micron-sized microspheres have a particle size of 15 μm. The nano-sized microspheres account for 40% of the total microsphere mass, and the micron-sized microspheres account for 60%. The micro / nanospheres constitute 40% of the composite air filter material by mass, with a porosity of 89.94% and an air permeability of 245.36 L / (m³). 2 *s), air resistance is 108 Pa, filtration efficiency is 99.94%.

[0081] Comparative Example 3

[0082] The fiber composite membrane described in this comparative example differs from that in Example 3 only in that it does not contain micro / nanospheres. Its preparation method includes the following steps:

[0083] (1) Nylon 6 and polyethylene are dissolved in an 88% formic acid aqueous solution to obtain a spinning solution, wherein the mass percentage of nylon 6 in the spinning solution is 8% and the mass percentage of polyethylene is 0.2%.

[0084] (2) The spinning solution is subjected to air-jet spinning and air-jet spraying through an air-jet spinning machine. The spinning parameters are as follows: the inner diameter of the needle is 500 μm, the polymer solution feed rate is 1 ml / h, the spinning air pressure is 0.12 MPa, the spinning distance is 35 cm, the collector winding speed is 700 r / h, the ambient temperature is 30℃, and the humidity is 60%.

[0085] (3) After spinning for 9 hours, the fiber wet film is dried in an oven at 60°C for 3 minutes to obtain composite fiber air filter material.

[0086] The performance testing methods and results of the high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filter materials prepared in Examples 1-3 of this invention, and comparative examples 1-3 are as follows:

[0087] I. Testing Method:

[0088] The fiber composite membranes of Examples 1-3 of this invention were subjected to performance tests:

[0089] ① The German Topas filter media filtration tester (TOPAS AFC-131) was used at an airflow rate of 3.3m³. 2 The filtration efficiency and air resistance were measured at a rate of / h, with a test area of ​​176 cm². 2 ;

[0090] ② The surface morphology and structure of the fiber composite membrane were characterized using a Phenom scanning electron microscope.

[0091] ③ The diameter of 200 fibers was measured using an image analyzer (Nano Measure).

[0092] ④ The membrane thickness was measured using a Sodium micrometer.

[0093] ⑤ The porosity of the nylon-6 membrane was determined by gravimetric method and calculated by Equation 1.

[0094] ⑥

[0095] In the formula, W1 is the dry film mass (g), W2 is the mass of the n-butanol-wetted film (g), d is the film thickness (cm), and ρ is the density of n-butanol (ρ0).

[0096] =0.811 g / ml), A is the membrane test area (cm²). 2 ).

[0097] ⑦ The air permeability of the fiber composite membrane was tested using a YG461E automatic air permeability tester; refer to GB / T5453-1997 "Textiles - Determination of Air Permeability of Fabrics", where the test area is 20 cm². 2 The pressure drop used was 200 Pa, and each sample was tested 10 times, with the average value taken.

[0098] ⑧ The moisture permeability of the fiber composite membrane was tested using a YG601H computer-controlled fabric moisture permeability meter;

[0099] The moisture permeability was determined according to the fabric moisture permeability evaporation method - positive cup method in GB / T 12704-91;

[0100] Referring to GB / T 12704.1-2009 "Textiles - Test Methods for Moisture Permeability of Fabrics - Part 2: Evaporation Method", the moisture permeability of the fabric was determined. The sample diameter was 70 mm, the temperature was (38±2)℃, and the relative humidity was 90%±2%. Each sample was tested 3 times and the average value was taken.

[0101] The change in the mass of the moisture-permeable cup of the sample with a test area of ​​S over 24 hours was used to calculate the moisture permeability of the mask sample, resulting in M ​​= (M1 - M2) / S, where M is the moisture permeability over 24 hours, in g / m². 2 M1 is the mass of the first weighing, in grams; M2 is the mass of the second weighing, in grams; S is the area of ​​the sample being measured, in square meters. 2 Each sample was tested three times, and the average value was taken.

[0102] II. Test Results:

[0103] 1. Regarding pore size and porosity.

[0104] The fiber diameter and thickness of the above embodiments and comparative examples were tested, and the results are shown in Table 1.

[0105] Table 1:

[0106] Fiber diameter (nm) Thickness (μm) Example 1 465.34 159.63 Comparative Example 1 434.86 104.24 Example 2 648.27 185.49 Comparative Example 2 615.74 125.76 Example 3 574.01 164.83 Comparative Example 3 551.99 117.78

[0107] As shown in Table 1, under otherwise unchanged conditions, the fiber composite membrane with added nano-microspheres has a slightly larger fiber diameter, which may be due to the interference of the dual-nozzle airflow. The fiber membrane doped with microspheres is also thicker because the micron-sized microspheres dispersed between the fibers provide three-dimensional support for the structure of the fiber membrane, which macroscopically manifests as an increase in the thickness of the fiber membrane.

[0108] The porosity of the above embodiments and comparative examples was tested, and the results are shown in Table 2.

[0109] Table 2:

[0110] Porosity (%) Example 1 91.34％ Comparative Example 1 78.83％ Example 2 90.10％ Comparative Example 2 75.16％ Example 3 89.94％ Comparative Example 3 77.28％

[0111] Porosity is a key factor affecting filtration pressure drop. Higher porosity results in lower nanofiber packing density, which is more conducive to efficient, low-resistance air filtration. Table 2 shows the porosity of nanofiber membranes in different embodiments and comparative examples. The porosity of the nanofiber membrane can be controlled by changing the proportion of microspheres; higher concentrations of micron-sized microspheres result in higher porosity. Combining the data in Table 2 with… Figure 3 It can be seen that, under the condition that other conditions remain unchanged, the fiber composite membrane with added nano-microspheres has a larger porosity. This is because the micro-sized microspheres dispersed between the fibers provide three-dimensional support for the structure of the fiber membrane. The dispersion of micro-sized microspheres between the fibers greatly increases the porosity of the fiber membrane, making it easier for airflow to penetrate and helping to reduce air resistance.

[0112] 2. Regarding air permeability and moisture permeability.

[0113] The air permeability and moisture permeability of the above embodiments and comparative examples were tested, and the results are shown in Table 3.

[0114] Table 3:

[0115] <![CDATA[Air permeability (L / (m 2 *s))]]> <![CDATA[Water vapor transmission rate (g / (m 2 ·h))]]> Example 1 276.43 228.76 Comparative Example 1 223.1 187.89 Example 2 262.21 209.90 Comparative Example 2 214.73 179.48 Example 3 245.36 205.89 Comparative Example 3 219.81 186.81

[0116] Air permeability is defined as "the velocity of airflow perpendicularly through a given area under a specific air pressure difference." Both air permeability and moisture permeability are important for filter materials. As shown in Table 3, the air permeability and moisture permeability of different embodiments and comparative examples were measured, combined with... Figure 3 , Figure 4 As can be seen from (a)-(c), under the condition that other conditions remain unchanged, the fiber composite membrane with added nano-microspheres has an obvious three-dimensional support pore structure of microspheres, and the micro-nano microsphere fiber composite membrane has better air permeability and moisture permeability.

[0117] 3. Regarding air resistance and filtration efficiency.

[0118] The air resistance and filtration efficiency of the above embodiments and comparative examples were tested, and the results are shown in Table 4.

[0119] Table 4:

[0120] Air resistance (Pa) Filtration efficiency (%) Example 1 98 99.93％ Comparative Example 1 138 96.78％ Example 2 104 99.97％ Comparative Example 2 145 95.29％ Example 3 108 99.94％ Comparative Example 3 143 95.91％

[0121] As shown in Table 4, under otherwise unchanged conditions, the filtration efficiency of the fiber composite membrane with added nano- and micro-spheres is improved, while the air resistance is further reduced. This is because the micron-sized microspheres dispersed between the fibers greatly increase the porosity of the fiber membrane, making it easier for airflow to penetrate and thus reducing air resistance. The nano-sized microspheres not only increase the specific surface area and nanoscale roughness of the composite filter material, but also further increase the capture efficiency of PM particles, which is beneficial for the rapid and effective interception of fine particles. The fiber membrane with a higher proportion of micron-spheres exhibits a better air resistance reduction effect, while the fiber membrane with a higher proportion of nanospheres has a higher filtration efficiency.

[0122] In summary, this invention achieves the controllable fabrication of a low-filtration-resistance three-dimensional nanofiber composite membrane by embedding microspheres into a nanofiber framework through a one-step multi-jet free-surface air-jet spinning process, thereby attaching the nanospheres to the fiber surface. This allows for the preparation of large-area microsphere nanofiber membranes with a simple and rapid production process. Compared to electrospinning and electrostatic spraying, this invention requires no high voltage, consumes less energy, and offers faster production rates, higher output, and safer and simpler equipment operation. The high-efficiency, low-resistance microsphere-fiber composite membrane prepared by this invention exhibits high porosity, high air and moisture permeability, and excellent filtration performance.

[0123] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filtration material, comprising a micro / nanofiber membrane body, characterized in that: The micro / nanofiber membrane consists of a two-dimensional, compact, three-dimensional, loose framework structure formed by spun polymer micro / nanofibers and several micro / nanospheres embedded within the framework structure. The micro / nanofibers have a diameter of 465.34-648.27 nm, the micro / nanospheres have a particle size of 0.05-15 μm, the micro / nanospheres account for 10-40% of the composite air filter material by mass, the porosity is 89.94%-91.34%, and the air permeability is 245.36-276.43 L / (m³). 2 *s), air resistance is 98-108 Pa; The micro-nanospheres are composed of micron-sized microspheres and nano-sized microspheres, wherein the particle size of the nano-sized microspheres is 50-300 nm and the particle size of the micron-sized microspheres is 3 μm-15 μm; the mass of the nano-sized microspheres accounts for 40-60% of the total mass of the microspheres, and the mass of the micron-sized microspheres accounts for 60-40% of the total mass of the microspheres.

2. The high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filter material according to claim 1, characterized in that: The micro-nanospheres are hydrophilic polydisperse microspheres, and the micro-nanospheres are one or more of silica, polystyrene, polymethyl methacrylate, and titanium dioxide.

3. A method for preparing a three-dimensional microsphere structured micro / nanofiber composite air filter material as described in any one of claims 1-2, characterized in that, Includes the following steps: I. Preparation of spinning solution: (1) Dissolve the spinning raw material in a solvent with a mass fraction of 88%, and stir magnetically for 12-24 hours at room temperature until completely dissolved to obtain the spinning solution for later use; II. Preparation of microsphere spraying suspension: (2) PVA powder and micro / nanosphere particles were mixed into an ethanol solution and stirred thoroughly at 40°C for 4 hours. The PVA concentration in the microsphere spraying suspension was 5 wt%. (3) The solution obtained in step (2) is ultrasonically treated at 25°C for 1-2 hours to ensure that the PVA is completely dissolved and the micro-nanospheres are fully dispersed, so as to obtain a microsphere spraying suspension with a total microsphere mass percentage of 1-5% and a total microsphere mass percentage of 2.5% in the microsphere spraying suspension; III. Air-jet spinning and spraying: (4) The spinning solution obtained in step (1) and the microsphere spraying suspension obtained in step (2) are simultaneously air-jet spun and air-jet coated by a parallel dual-nozzle air-jet spinning machine. The inner diameter of the needle of the parallel dual-nozzle air-jet spinning machine is 500μm, the injection rate of the spinning solution is 1-2ml / h, the injection speed of the microsphere spraying suspension is 1-4mL / h, the spinning air pressure is 0.08-0.12MPa, the spraying air pressure is 0.08-0.12MPa, the distance from the spinneret to the receiving curtain is 35cm, the winding speed of the collector is 700r / h, the ambient temperature is 20-30℃, and the ambient humidity is 35%-60%, to obtain a three-dimensional microsphere structure micro-nanofiber composite wet film. (5) The three-dimensional microsphere structure micro-nanofiber composite wet membrane is dried at a temperature of 60°C for 3 minutes to obtain the three-dimensional microsphere structure micro-nanofiber composite air filter material.

4. The method for preparing the high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filter material according to claim 3, characterized in that: In step (1), the spinning raw material is one or more of polyamide 6, polyamide 66, polyurethane, polyacrylonitrile, polyimide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride or polyoxyethylene.

5. The method for preparing the high-efficiency, low-resistance three-dimensional microsphere structure micro / nanofiber composite air filter material according to claim 3, characterized in that: In step (1), the molecular weight of the spinning raw material is 50,000 to 200,000, the mass percentage of the spinning raw material in the spinning solution is 8.2% to 10%, and the solvent is one or more of formic acid, ethanol, or N,N-dimethylformamide.

Images