Gradient-electrostatic composite high-efficiency low-resistance air filtration material and preparation method thereof

Abstract

The application discloses gradient-electrostatic composite high-efficiency low-resistance air filtration material, and further discloses a preparation method of the air filtration material, which comprises the following steps: adding alcohol-soluble polyamide EPA and silica SiO2 aerogel powder into anhydrous ethanol, stirring to uniformly disperse the EPA and the SiO2, and forming an EPA / SiO2 composite spinning solution; performing electrostatic spinning by using the spinning solution, and using non-woven fabric to undertake, so as to obtain an EPA / SiO2 micro-nano fiber composite film; placing PS balls between two layers of the EPA / SiO2 micro-nano fiber composite film, sealing the edge area of the two layers of the composite film, so as to encapsulate the balls in the inside, and obtaining the air filtration material. The air filtration material realizes fine filtration and high-efficiency low-resistance by means of pore size gradient design and spontaneous electrostatic effect.

Description

Technical Field

[0001] This invention belongs to the field of air filtration material technology, and relates to a gradient-electrostatic composite high-efficiency low-resistance air filtration material. This invention also relates to a method for preparing the material. Background Technology

[0002] Currently, mainstream air filtration technologies still have many limitations. First, ordinary filter materials, such as meltblown nonwoven fabrics, typically have fiber diameters in the micrometer range and a simple pore structure, limiting their ability to trap PM2.5 and even finer particles (such as PM0.3), making it difficult to improve filtration accuracy. Second, while traditional methods such as bag filters have simple structures, increasing material density or thickness to improve accuracy often leads to significantly increased operating resistance (pressure drop), resulting in excessive energy consumption and high application costs.

[0003] In addition, another widely used electrostatic dust removal technology relies on an externally applied high voltage to charge particulate matter, which is then captured. This method has several inherent drawbacks: first, it requires a complex and expensive high-voltage power supply and control system, resulting in high equipment costs; second, its electrostatic effect is easily affected by ambient humidity, leading to unstable performance; third, the high-voltage corona discharge process generates secondary pollutants such as ozone, posing a potential threat to human health; and fourth, it has minimal effect on removing uncharged gaseous pollutants.

[0004] In summary, existing technologies generally face a bottleneck that is difficult to balance: physical filtration methods, in pursuit of high filtration efficiency, inevitably come with high resistance and high energy consumption; while electrostatic assisted methods, while improving efficiency, introduce new problems such as ozone pollution, equipment complexity, and performance instability. Therefore, the industry urgently needs an innovative filtration material and technology solution that can simultaneously achieve "high-efficiency filtration" and "low operating resistance" without relying on external high-voltage electricity or generating ozone. Summary of the Invention

[0005] The purpose of this invention is to provide a gradient-electrostatic composite high-efficiency low-resistance air filter material, which has the characteristics of low filtration resistance, fine filtration, and high filtration efficiency.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned high-efficiency, low-resistance air filter material.

[0007] The technical solution adopted in this invention is: The preparation method of gradient-electrostatic composite high-efficiency low-resistance air filter material is carried out according to the following steps: Step 1: Add alcohol-soluble polyamide (EPA) and SiO2 aerogel powder to anhydrous ethanol, stir to uniformly disperse EPA and SiO2, and form EPA / SiO2 composite spinning solution; Step 2: Electrospinning is performed using the spinning solution obtained in Step 1, and the nonwoven fabric is used as a support to obtain an EPA / SiO2 micro / nanofiber composite membrane. Step 3: Place the PS ball between two layers of EPA / SiO2 micro / nanofiber composite membrane, and seal the edge area of ​​the two composite membranes to encapsulate the ball inside, thus obtaining the air filter material.

[0008] The invention is further characterized by: In the composite spinning solution of step 1, the mass concentration of EPA is 16wt%~24wt%, and the doping amount of SiO2 aerogel is 1wt%~7wt%.

[0009] In step 2, the electrospinning process parameters are: voltage 8kV~12kV, spinning distance 8cm~12cm, pouring speed 0.5mL / h~2mL / h, relative humidity 35%~45%, and temperature 25℃~28℃.

[0010] In step 2, a dotted adhesive layer is coated onto the nonwoven fabric.

[0011] In step 3, the diameter of the PS balls is 50μm~500μm, and the placement density of the PS balls is 10 balls / cm²-50 balls / cm².

[0012] In step 3, the PS ball comes into contact with the nanofiber membrane of the two-layer micro-nanofiber composite membrane.

[0013] In step 3, the edge areas of the two micro / nanofiber composite films are sealed and bonded together by hot pressing or ultrasonic welding.

[0014] Another technical solution adopted in this invention is: The gradient-electrostatic composite high-efficiency low-resistance air filter material includes a micro / nanofiber composite membrane and PS balls, wherein the PS balls are sealed in the micro / nanofiber composite membrane and can move freely; the micro / nanofiber composite membrane is obtained by electrospinning EPA spinning solution doped with SiO2 aerogel on a nonwoven fabric; the PS balls are in contact with the nanofiber membrane formed by electrospinning.

[0015] The beneficial effects of this invention are: (1) The method of the present invention uses electrospinning technology to prepare nanofiber membranes containing silica (SiO2) aerogel, which are combined with a nonwoven fabric support layer to form a gradient filtration structure, thereby achieving efficient gradation from coarse filtration to fine filtration and significantly improving the filtration efficiency for particles of different sizes. The SiO2 aerogel also endows the material with superhydrophobic properties, effectively preventing bacterial growth and secondary pollution in humid environments; (2) The innovative method of this invention sets micron-sized polystyrene (PS) beads between two layers of nanofiber membranes. The beads are driven by airflow to generate static electricity through friction with the membrane layers, thereby reducing filtration resistance and improving efficiency through the spontaneous electrostatic effect. This design does not require an external electric field, fundamentally avoiding the secondary pollution problem of ozone generated by high-voltage discharge in traditional electrostatic dust removal. (3) The preparation process of this invention is green and environmentally friendly. The substrate material used is alcohol-soluble polyamide (EPA), which is an environmentally friendly polymer that can use ethanol as a solvent. This material can efficiently filter particulate pollutants of PM0.3 and above, with a filtration efficiency of over 98%. In terms of maintenance, it is stable in operation, has strong environmental adaptability, and the filter components do not need to be replaced frequently, effectively reducing maintenance costs and operating difficulties. Attached Figure Description

[0016] Figure 1 The spinning process of the electrospun nanofiber membrane in the filter material of this invention is described below. Figure 2 This is a schematic diagram of the self-generated static electricity of the filter material of the present invention; Figure 3 This is an optical display of the filter material of the present invention and an electron microscope image after filtration. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] This invention relates to a gradient-electrostatic composite high-efficiency low-resistance air filter material, comprising a micro / nanofiber composite membrane obtained by electrospinning an EPA spinning solution doped with SiO2 aerogel on a nonwoven fabric, and PS beads located between the two composite membranes. The nanofiber membrane and the nonwoven fabric form a gradient filtration structure with pores decreasing in size, while the PS beads can achieve triboelectric charging. Under the synergistic effect of the gradient structure and electrostatics, fine, efficient, and low-resistance filtration is achieved, ultimately resulting in filtered clean air.

[0019] The preparation method of the gradient-electrostatic composite high-efficiency low-resistance air filter material of the present invention is carried out according to the following steps: Step 1: Place EPA and SiO2 aerogel powder in a container, add anhydrous ethanol as a solvent, and stir thoroughly with a magnetic stirrer to uniformly disperse the EPA and SiO2 aerogel powder in the ethanol to form a stable EPA / SiO2 composite spinning solution, wherein the concentration of EPA is 16wt%~24wt% and the doping amount of SiO2 aerogel is 1wt%~7wt%.

[0020] Step 2: Load the spinning solution obtained in Step 1 into the electrospinning device, perform electrospinning, and use a nonwoven fabric with an adhesive layer dotted by a scraper roller to receive the spinning solution. The process parameters for electrospinning are: voltage 8kV~12kV, spinning distance 8cm~12cm, injection speed 0.5mL / h~2mL / h, relative humidity 35%~45%, and temperature 25℃~28℃.

[0021] Under the influence of a high-voltage electric field, the solution is sprayed to form nanofibers, which then rapidly solidify and deposit onto the nonwoven fabric of the receiving device, thus obtaining an EPA / SiO2 micro / nanofiber composite membrane. The specific spinning process is as follows: Figure 1 As shown.

[0022] Step 3: Distribute PS beads (50μm~500μm in diameter) evenly between two layers of EPA / SiO2 micro / nanofiber composite membrane at a density of 10 beads / cm²-50 beads / cm², with the nanofiber membrane located inside and the nonwoven fabric located outside, i.e., the PS beads are in contact with the nanofiber membrane in the composite membrane; seal the three layers of materials at the edge area by hot pressing or ultrasonic welding, thereby encapsulating the beads inside.

[0023] like Figure 2 As shown, PS balls have triboelectric properties. By adding PS balls between two layers of micro-nanofiber composite membrane, the membrane spontaneously generates static electricity through airflow, achieving efficient and low-resistance air filtration with a gradient structure that does not require an external electric field.

[0024] The working principle of the high-efficiency, low-resistance air filter material of this invention is as follows: EPA / SiO2 nanofiber membranes prepared using electrospinning technology possess uniform fiber diameter and a smooth surface, exhibiting high filtration precision and efficiency, and are easily recyclable and separable. The nonwoven fabric provides mechanical support for the nanofiber membrane, enhancing the overall strength and toughness of the material. Simultaneously, the nanoscale pores of the nanofiber membrane work in conjunction with the larger pores of the nonwoven fabric to form a gradient filtration structure, achieving graded filtration from coarse to fine, significantly improving the filtration efficiency for particles of different sizes. Combined with the porous structure of the hydrophobic SiO2 aerogel, the nanofiber membrane not only possesses a high specific surface area and porosity, improving air filtration efficiency, but also exhibits superhydrophobic properties, effectively preventing secondary contamination of the air filtration material in humid environments.

[0025] Furthermore, the two-layer micro / nanofiber composite membrane is filled with micron-sized PS beads with triboelectric properties. The nanofiber membrane loaded with PS beads can construct a suitable gradient pore structure, which improves the adsorption capacity. It also allows the fiber membrane to spontaneously generate static electricity without an external electric field under the catalysis of airflow, resulting in very low resistance. The additional electrostatic adsorption force applied to charged particles greatly improves the capture capacity of fine particles, while avoiding the secondary pollution problem caused by the external high pressure applied by ordinary filtration devices.

[0026] Example 1: Using nonwoven fabric as a substrate, an adhesive layer is dot-coated using a coating roller. Then, an EPA / SiO2 nanofiber membrane is fabricated on the adhesive layer using electrospinning technology, forming a micro / nanofiber composite membrane. PS beads with a diameter of 100μm are uniformly distributed between two layers of the EPA / SiO2 micro / nanofiber composite membrane at a density of 30-40 beads / cm². The three layers are then sealed together at the edges using hot pressing, encapsulating the beads inside. Driven by airflow, the beads move, and the fiber membrane spontaneously generates static electricity, enabling efficient adsorption and filtration of air.

[0027] The concentration of EPA was 20 wt%, and the doping amount of SiO2 aerogel was 5 wt%. The electrospinning process parameters were: voltage 10 kV, spinning distance 10 cm, pouring speed 1 mL / h, relative humidity 40%, and temperature 25 ℃.

[0028] like Figure 3 The image shown is an optical display of the filter material prepared in this embodiment and an electron microscope image after filtration. It can be seen that the material can effectively capture small particles of different sizes in the air.

[0029] The filter material of this embodiment was used to simulate the passage of air in a low-concentration environment (containing PM0.3 micron particles), and the ball bearings were driven to generate static electricity through friction with an airflow of 10 L / min. The results showed that the initial filtration efficiency reached 99.5% with a resistance of 12 Pa. After continuous operation, the efficiency dropped to 96.5% and the resistance increased to 40 Pa.

[0030] Example 2: Using nonwoven fabric as a substrate, an adhesive layer is dot-coated using a coating roller. Then, an EPA / SiO2 nanofiber membrane is fabricated on the adhesive layer using electrospinning technology, forming a micro / nanofiber composite membrane. PS beads with a diameter of 500μm are uniformly distributed between two layers of the EPA / SiO2 micro / nanofiber composite membrane at a density of 10-20 beads / cm². The three layers are then sealed together at the edges using ultrasonic welding, encapsulating the beads inside. Driven by airflow, the beads move, and the fiber membrane spontaneously generates static electricity, enabling efficient adsorption and filtration of air.

[0031] The concentration of EPA was 16 wt%, and the doping amount of SiO2 aerogel was 7 wt%. The electrospinning process parameters were: voltage 12 kV, spinning distance 12 cm, pouring speed 1 mL / h, relative humidity 45%, and temperature 28 °C.

[0032] The filter material of this embodiment was used to simulate the passage of air in a low-concentration environment (containing PM0.3 micron particles), and the ball bearings were driven to generate static electricity through friction with an airflow of 10 L / min. The results showed that the initial filtration efficiency reached 97.5% and the resistance was 16 Pa. After continuous operation, the efficiency dropped to 96.5% and the resistance increased to 50 Pa.

[0033] Example 3: Using nonwoven fabric as a substrate, an adhesive layer is dot-coated using a coating roller. Then, an EPA / SiO2 nanofiber membrane is fabricated on the adhesive layer using electrospinning technology, forming a micro / nanofiber composite membrane. PS beads with a diameter of 300μm are uniformly distributed between two layers of the EPA / SiO2 micro / nanofiber composite membrane at a density of 40-50 beads / cm². The three layers are then sealed together at the edges using ultrasonic welding, encapsulating the beads inside. Driven by airflow, the beads move, and the fiber membrane spontaneously generates static electricity, enabling efficient adsorption and filtration of air.

[0034] The concentration of EPA was 24 wt%, and the doping amount of SiO2 aerogel was 4 wt%. The electrospinning process parameters were: voltage 8 kV, spinning distance 8 cm, infusion rate 2 mL / h, relative humidity 35%, and temperature 25℃.

[0035] The filter material of this embodiment was used to simulate the passage of air in a low-concentration environment (containing PM0.3 micron particles), and the ball bearings were driven to generate static electricity through friction with an airflow of 10 L / min. The results showed that the initial filtration efficiency reached 99.7% with a resistance of 10 Pa. After continuous operation, the efficiency dropped to 99% and the resistance increased to 35 Pa.

Claims

1. A method for preparing a gradient-electrostatic composite high-efficiency low-resistance air filter material, characterized in that, The specific steps are as follows: Step 1: Add alcohol-soluble polyamide (EPA) and SiO2 aerogel powder to anhydrous ethanol, stir to uniformly disperse EPA and SiO2, and form EPA / SiO2 composite spinning solution; Step 2: Electrospinning is performed using the spinning solution obtained in Step 1, and the nonwoven fabric is used as a support to obtain an EPA / SiO2 micro / nanofiber composite membrane. Step 3: Place the PS ball between two layers of EPA / SiO2 micro / nanofiber composite membrane, seal the edge area of ​​the two composite membranes, thereby encapsulating the ball inside and allowing it to move freely, thus obtaining the air filter material.

2. The preparation method of the gradient-electrostatic composite high-efficiency low-resistance air filter material according to claim 1, characterized in that, In the composite spinning solution of step 1, the mass concentration of EPA is 16wt%~24wt%, and the doping amount of SiO2 aerogel is 1wt%~7wt%.

3. The preparation method of the gradient-electrostatic composite high-efficiency low-resistance air filter material according to claim 1, characterized in that, In step 2, the electrospinning process parameters are: voltage 8kV~12kV, spinning distance 8cm~12cm, pouring speed 0.5mL / h~2mL / h, relative humidity 35%~45%, and temperature 25℃~28℃.

4. The method for preparing the gradient-electrostatic composite high-efficiency low-resistance air filter material according to claim 1, characterized in that, In step 2, a dotted adhesive layer is coated onto the nonwoven fabric.

5. The method for preparing the gradient-electrostatic composite high-efficiency low-resistance air filter material according to claim 1, characterized in that, In step 3, the diameter of the PS balls is 50μm~500μm, and the placement density of the PS balls is 10 balls / cm²-50 balls / cm².

6. The method for preparing the gradient-electrostatic composite high-efficiency low-resistance air filter material according to claim 1, characterized in that, In step 3, the PS ball is in contact with the nanofiber membrane of the two-layer micro-nanofiber composite membrane.

7. The method for preparing the gradient-electrostatic composite high-efficiency low-resistance air filter material according to claim 1, characterized in that, In step 3, the edge areas of the two micro / nanofiber composite films are sealed and bonded together by hot pressing or ultrasonic welding.

8. A gradient-electrostatic composite high-efficiency low-resistance air filter material, characterized in that: The air filtration material includes a micro / nanofiber composite membrane and PS beads, wherein the PS beads are sealed within two layers of the micro / nanofiber composite membrane and can move freely; the micro / nanofiber composite membrane is obtained by electrospinning an EPA spinning solution doped with SiO2 aerogel on a nonwoven fabric; the PS beads are in contact with the nanofiber membrane formed by electrospinning.

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