Electrostatic spinning high-efficiency comfortable air filtration protective material and preparation method thereof

Abstract

The present application relates to a kind of electrostatic spinning high efficiency comfortable air filtration protective material and its preparation method, the material is sandwich structure, from top to bottom respectively is the windward face of bimodal fiber membrane, the middle layer of string bead fiber membrane, the leeward face of bimodal fiber membrane.Nanofiber in bimodal fiber average diameter is 10~90 nm, submicron fiber diameter is in 100~200 nm.String bead fiber is obtained by manipulating the Rayleigh instability of dilute jet.The extremely fine nanofiber and submicron fiber in bimodal fiber layer and string bead fiber layer are used to high efficiency capture PM 0.3 , the introduction of string bead fiber membrane can effectively reduce the close packing of fiber, thereby promoting the efficient transmission of airflow, moisture and heat.SSM can simultaneously consider PM 0.3 High protection performance and wearing comfort, in the field of personal protection air filtration shows great application prospect.

Description

Technical Field

[0001] This invention belongs to the field of air filtration materials and their preparation, and specifically relates to an electrospun high-efficiency and comfortable air filtration and protection material and its preparation method. Background Technology

[0002] Air particulate matter pollution poses a significant threat to the global economy, the ecological environment, and human health. PM2.5 is a complex mixture, containing PM2.5... 0.3 Particularly notorious is its high penetrability (approximately 300 nm), allowing it to travel long distances in the air and carry various bacteria and viruses. To reduce the harm caused by air pollution, especially during periods of emerging infectious disease outbreaks, the importance of air filtration materials is paramount. Publicly available patents such as "A Healthy Anti-epidemic Mask and its Preparation Method" (CN202311672183.7) and "A Meltblown Fabric Production Process and High-Efficiency Low-Resistance Mask" (CN202110956677.2) address PM2.5 pollution. 10 or PM 2.5 It has good filtration efficiency, but due to its inherent structural characteristics of large diameter and large pore size, it is less effective at filtering particulate matter (PM) with the largest penetrating particle size. 0.3 Its filtration efficiency is relatively low. Furthermore, the heavy stacking method used to improve efficiency results in poor air permeability. Additionally, a published patent, "A Method for Preparing Low-Resistance, High-Efficiency, High-Dust-Capacity Air Filter Material" (CN202210795938.1), reports a method for obtaining filter materials using a melt-blown electret method. However, the electret charge in the material prepared by this method is easily dissipated, and filtration stability cannot be guaranteed.

[0003] Electrospun nanofiber filter materials possess advantages such as high filtration efficiency, thinness, and light weight due to their structural characteristics of fine diameter, small pore size, and high porosity. Published patents related to electrospun fiber air filter materials include "A High-Efficiency Air Filter Composite Nanofiber Membrane and Its Preparation Method" (CN202110537187.9), "An Air Filter Membrane Based on Nano-Hybrid Modified Polylactic Acid Fiber and Its Preparation Method" (CN202211594526.8), "An Air Filter Membrane and Its Preparation Method and Application" (CN202210695095.8), and "A High-Efficiency, Low-Resistance Multi-Component Three-Dimensional Cavity Structure Air Filter Material and Its Preparation Method" (CN202010041701.5). However, due to their pseudo-nanoscale diameter (>100 nm), the filtration performance of these filter materials is difficult to further improve. Recently, some researchers have prepared filter materials composed of true nanofibers, such as "A PVDF dendritic nanofiber air filter material and its preparation method" (CN202010031082.1) and "A method for preparing a dendritic multi-level structured air filter nanofiber membrane" (CN202110793035.5). While these filter materials can effectively intercept PM2.5... 0.3 However, due to its tightly stacked structure, the filtration resistance remains unsatisfactory, and it lacks a certain level of comfort. Therefore, it is necessary to develop a high-efficiency PM2.5 system that simultaneously offers low pressure drop and thermal and humidity comfort. 0.3 Filters are especially important. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a sandwich structure membrane composed of a bimodal fiber layer with small pores and a beaded fiber layer with large pores, which can simultaneously address PM2.5 contamination issues. 0.3 Protective performance and wearing comfort of the air filter.

[0005] To achieve the above objectives, the present invention provides an electrospun high-efficiency and comfortable air filtration and protection material and its preparation method.

[0006] This invention utilizes electrospinning and doping with a third component possessing specific structures and properties to improve solution conductivity and weaken intermolecular forces, thereby promoting jet splitting and controllably preparing bimodal fibers. Furthermore, beaded fibers were prepared by manipulating the Rayleigh instability of the dilute jet. By further combining bimodal fiber membranes with beaded fiber membranes, a unique SSM (Self-Spun Surface Mixture) was designed.

[0007] Preferably, the preparation method of the electrospun high-efficiency comfort air filtration and protective material includes the following steps:

[0008] (1) Preparation of bimodal fibers: The spinning solution consists of polymer, solvent and third component; draw an appropriate amount of solution with a syringe, connect the needle to the positive terminal of the power supply, set appropriate voltage, receiving distance and injection rate parameters, and the receiving substrate is polypropylene nonwoven fabric;

[0009] (2) Preparation of beaded fibers: The spinning solution consists of polymer and solvent; draw an appropriate amount of solution with a syringe, connect the needle to the positive terminal of the power supply, and set appropriate voltage, receiving distance and injection rate parameters;

[0010] (3) SSM was obtained by layer-by-layer electrospinning.

[0011] Preferably, the third component of the polymer solution for preparing bimodal fibers is an amphiphilic substance composed of hydrophilic ionic groups and lipophilic alkane chains. This type of substance can improve the solution conductivity and weaken intermolecular forces through ion-dipole interactions, making it easier for some molecular chains to detach from the jet matrix, thereby promoting the splitting of the charged jet and forming bimodal fibers. Furthermore, its hydrophilicity allows water molecules from the external environment to better displace the solvent in the solution system, thus accelerating the curing of the bimodal fibers. Specifically, the third component includes 2,3-epoxypropyltrimethylammonium chloride.

[0012] Preferably, the method for preparing the polymer solution for bimodal fiber preparation is as follows: First, add the third component to the solvent and stir with a magnetic stirrer at room temperature for 60-180 min until the solution becomes clear and transparent. Then, add the polymer and stir continuously with a magnetic stirrer at room temperature or under heating for 8-24 h.

[0013] Preferably, the polymer solution used to prepare the bimodal fiber has a polymer mass fraction of 2-10 wt%, a third component of 2-10 wt%, a viscosity range of 50-1500 mPa·s, and an electrical conductivity range of 1-1000 µS·cm. -1 .

[0014] Preferably, the polymer solution used to prepare the beaded fibers is a dilute solution with a polymer mass fraction of 1-8 wt%, a viscosity range of 1-100 mPa·s, and an electrical conductivity range of 1-500 µS·cm. -1 .

[0015] Preferably, the polymer is PA6, and the solvent includes hexafluoroisopropanol and trifluoroethanol.

[0016] Preferably, the voltage during electrospinning is 10-25 kV, and the spinning flow rate is set to 0.1-2.0 mL·h. -1The receiving distance is 10-20 cm, the metal needle of the syringe is 18-22#, the ambient temperature is maintained at 20-35 ℃, and the relative humidity is 30-90%.

[0017] Preferably, the SSM, from top to bottom, consists of the windward side of the bimodal fiber membrane, the intermediate layer of the beaded fiber membrane, and the leeward side of the bimodal fiber membrane. The bimodal fibers are composed of true nanofibers (10-90 nm) and submicron fibers (100-200 nm); the beaded fibers are composed of 2-3 μm beads and submicron fibers; and the average pore size of the SSM is 1.27 µm.

[0018] The ultrafine nanofibers and submicron fibers in the bimodal fiber layer and beaded fiber layer are used for efficient PM capture. 0.3 The introduction of beaded fiber membranes can effectively reduce the dense packing of fibers, thereby promoting the efficient transfer of airflow, moisture and heat.

[0019] More preferably, the SSM is for PM 0.3 Its filtration efficiency is 99.8%, pressure drop is as low as 65 Pa, and QF is as high as 0.097 Pa. -1 The water vapor transmission rate of the SSM is as high as 7.6 kg·m. -2 ·d -1 Breathability is 164 mm·s -1 Furthermore, during exhalation, the surface temperature of the SSM is 3.9 °C higher than that of commercial masks. The SSM can simultaneously reduce PM2.5 levels. 0.3 High protective performance and comfortable wearing of air filters.

[0020] Beneficial effects

[0021] (1) This invention creates a special solution system with high conductivity and weak intermolecular interactions by doping a third component into the polymer solution to form ion-dipole interactions. Electrospinning technology is then used to promote the detachment of some molecular chains from the spinning jet, resulting in splitting and solidification. This allows for the preparation of a bimodal fiber layer composed of ultrafine nanofibers and submicron fibers. By controlling the Rayleigh instability of the electrospinning solution jet, a beaded fiber layer composed of micron-sized beads and submicron fibers can be prepared. Further composite of the bimodal fiber membrane and the beaded fiber membrane results in a unique SSM.

[0022] (2) The SSM prepared by this invention has structural features such as small pore size and fine diameter. The presence of the composite structure gives the air filter material a three-dimensional structure, which can filter particles of different sizes step by step, thus improving the filtration accuracy. In addition, SSM has good thermal and humidity comfort, which can provide inspiration for the design of efficient and comfortable personal protective materials. Attached Figure Description

[0023] Figure 1 This is a SEM image of the PA6 / GTA bimodal fiber membrane prepared in Example 1 of the present invention.

[0024] Figure 2 This is a SEM image of the PA6 beaded fiber membrane prepared in Example 1 of the present invention.

[0025] Figure 3 This is a SEM image of the SSM prepared in Example 1 of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0027] Test conditions for sample filtration performance: The filtration performance of the prepared electrospun composite membrane was tested using an LZC-K1 automatic filter media analyzer. NaCl aerosol particles were used during the test, with an air velocity of 32 L / min and a test area of ​​100 cm². 2 Each sample was tested three times, and the average pressure drop and filtration efficiency were calculated. The formula for calculating the quality factor (QF), which reflects the overall filtration performance, is as follows:

[0028]

[0029] Air permeability testing of samples: The air permeability was tested using a YG461E-III fabric air permeability tester, with a test area of ​​100 cm². 2 The differential pressure was set to 200 Pa, the test mode was set to automatic mode, and the test was performed 10 times, with the average value taken.

[0030] Moisture permeability test of samples: The test was conducted using an FX3180-CM15 moisture permeability tester. Each sample was tested three times, and the average value was taken.

[0031] Example 1

[0032] This embodiment provides an electrospun high-efficiency and comfortable air filtration and protective material. This filter material has a "sandwich" structure, consisting from top to bottom of a bimodal fiber membrane windward side, a beaded fiber membrane middle layer, and a bimodal fiber membrane leeward side. The bimodal fibers are composed of true nanofibers (46±11 nm) and submicron fibers (155±28 nm). The beaded fibers are composed of approximately 120 nm submicron fibers and approximately 3.37 µm microspheres. The ultrafine nanofibers and submicron fibers in the bimodal fibers can jointly form pores, preventing the nanofibers from densely packing together, thereby effectively intercepting and capturing PM2.5. 0.3This reduces filtration resistance. A loosely beaded fiber membrane with large pores serves as the intermediate layer to support the two bimodal fiber membranes, potentially allowing for simultaneous PM2.5 filtration. 0.3 It intercepts airflow and facilitates the transfer of air, moisture, and heat. The sandwich-structured membrane has a pore size of 1.27 µm, a thickness of approximately 3.6 µm, and a basis weight of approximately 0.6 g·m³. -2 .

[0033] The specific steps for the mass production method of the above-mentioned filter material are as follows:

[0034] Step 1: Dissolve PA6 in hexafluoroisopropanol and stir at room temperature until the solution becomes clear and transparent. The solution has a viscosity of 247 mPa·s and a conductivity of 4 µS·cm at a concentration of 6 wt%. -1 .

[0035] Step 2: Dissolve 2,3-epoxypropyltrimethylammonium chloride (GTA) in the solution prepared in Step 1, and stir at room temperature until the solution becomes clear and transparent. The fraction used in this step is 5 wt% of the PA6 added in Step 1. The viscosity of this solution is 179 mPa·s, and the conductivity is 287 µS·cm. -1 .

[0036] Step 3: Dissolve PA6 in hexafluoroisopropanol and stir at room temperature until the solution becomes clear and transparent. The prepared solution has a viscosity of 76 mPa·s and a conductivity of 2 µS·cm at a fraction of 6 wt%. -1 .

[0037] Step 4: The solution prepared in Step 2 is loaded into a syringe equipped with a 20# metal spinneret for high-voltage electrospinning, and fibers are deposited at 20 g·m⁻². -2 On the nonwoven fabric, the receiving distance was fixed at 12 cm, the voltage was set to 20 kV, and the spinning flow rate was set to 0.6 mL·h. -1 The ambient temperature was maintained at 25 ± 3℃, and the relative humidity at 50% ± 5%.

[0038] Step 5: The solution prepared in step 3 is loaded into a syringe equipped with a 20# metal spinneret for high-voltage electrospinning. The distance between the collector and the needle tip is fixed at 12 cm, the voltage is set to 11 kV, and the spinning flow rate is set to 1.0 mL·h. -1 The ambient temperature was maintained at 25 ± 3℃, and the relative humidity at 50% ± 5%. The fibers were finally deposited on the fiber membrane prepared in the fourth step.

[0039] Step 6: Load the solution prepared in Step 2 into a syringe equipped with a 20# metal spinneret for high-voltage electrospinning. The receiving distance is fixed at 12 cm, the voltage is set to 20 kV, and the spinning flow rate is set to 0.6 mL·h.-1 The ambient temperature was maintained at 25 ± 3℃, and the relative humidity at 50% ± 5%. Fibers were deposited on the fiber membrane prepared in step five.

[0040] The SSM prepared in this embodiment has ultrafine fiber diameter, small pore size, and low bulk density for PM. 0.3 The removal rate is as high as 99.8%, the pressure drop is as low as 65 Pa, and the QF is as high as 0.097 Pa. -1 After 180 minutes of continuous filtration, the SSM was still able to intercept over 99.7% of PM. 0.3 This demonstrates excellent long-term filtration stability. Furthermore, the SSM exhibits a water vapor permeability of up to 7.6 kg·m³. -2 ·d -1 The breathability of SSM is 164 mm·s. -1 Furthermore, during exhalation, the surface temperature of the SSM is 3.9 °C higher than that of commercial masks, demonstrating superior heat dissipation.

[0041] Comparative Example 1

[0042] The filter material is a gradient structure membrane consisting of a bimodal fiber membrane on the windward side and a beaded fiber membrane on the leeward side. It has a pore size of 1.34 µm, a thickness of approximately 3.6 µm, and a basis weight of approximately 0.6 g·m³. -2 The specific steps are as follows:

[0043] Step 1: Dissolve PA6 in hexafluoroisopropanol and stir at room temperature until the solution becomes clear and transparent. The concentration is 6 wt%.

[0044] Step 2: Dissolve GTA in the solution prepared in Step 1, and stir at room temperature until the solution becomes clear and transparent. The concentration should be 5 wt% of the PA6 added in Step 1.

[0045] Step 3: Dissolve PA6 in hexafluoroisopropanol and stir at room temperature until the solution becomes clear and transparent. The concentration is 6 wt%.

[0046] Step 4: The solution prepared in step 3 is loaded into a syringe equipped with a 20# metal spinneret for high-voltage electrospinning, and the fibers are deposited at 20 g·m⁻². -2 On the nonwoven fabric, the distance between the collector and the needle tip was fixed at 12 cm, the voltage was set to 11 kV, and the spinning flow rate was set to 1.0 mL·h. -1 The ambient temperature was maintained at 25 ± 3℃, and the relative humidity was 50% ± 5%.

[0047] Step 5: The solution prepared in Step 2 is loaded into a syringe equipped with a 20# metal spinneret for high-voltage electrospinning. The receiving distance is fixed at 12 cm, the voltage is set to 20 kV, and the spinning flow rate is set to 0.6 mL·h. -1 The ambient temperature was maintained at 25 ± 3℃, and the relative humidity at 50% ± 5%. Fibers were deposited on the fiber membrane prepared in step four.

[0048] The prepared gradient structure membrane for PM 0.3 The filtration efficiency is 99.31%, the pressure drop is 66 Pa, and the quality factor is 0.076 Pa. -1 .

[0049] Comparative Example 2

[0050] The filter material consists of a gradient structure membrane, with a beaded fiber membrane on the windward side and a bimodal fiber membrane on the leeward side. It has a pore size of 1.35 µm, a thickness of approximately 3.6 µm, and a basis weight of approximately 0.6 g·m³. -2 The specific steps are as follows:

[0051] Step 1: Dissolve PA6 in hexafluoroisopropanol and stir at room temperature until the solution becomes clear and transparent. The concentration is 6 wt%.

[0052] Step 2: Dissolve GTA in the solution prepared in Step 1, and stir at room temperature until the solution becomes clear and transparent. The concentration should be 5 wt% of the PA6 added in Step 1.

[0053] Step 3: Dissolve PA6 in hexafluoroisopropanol and stir at room temperature until the solution becomes clear and transparent. The concentration is 6 wt%.

[0054] Step 4: The solution prepared in Step 2 is loaded into a syringe equipped with a 20# metal spinneret for high-voltage electrospinning, and fibers are deposited at 20 g·m⁻². -2 On the nonwoven fabric, the receiving distance was fixed at 12 cm, the voltage was set to 20 kV, and the spinning flow rate was set to 0.6 mL·h. -1 The ambient temperature was maintained at 25 ± 3℃, and the relative humidity at 50% ± 5%.

[0055] Step 5: The solution prepared in step 3 is loaded into a syringe equipped with a 20# metal spinneret for high-voltage electrospinning. The distance between the collector and the needle tip is fixed at 12 cm, the voltage is set to 11 kV, and the spinning flow rate is set to 1.0 mL·h. -1 The ambient temperature was maintained at 25 ± 3℃, and the relative humidity at 50% ± 5%. The fibers were finally deposited on the fiber membrane prepared in the fourth step.

[0056] The prepared gradient structure membrane for PM 0.3The filtration efficiency is 99.20%, the pressure drop is 65 Pa, and the quality factor is 0.075 Pa. -1 .

[0057] The superior filtration performance of the SSM filter in Example 1 is attributed to its unique sandwich structure, which consists of bimodal fibers, beaded fibers, and another bimodal fiber in sequence. This three-layer structure not only enables efficient and stable step-by-step filtration of particulate matter but also ensures airflow. Furthermore, compared to gradient structure membranes, SSM has a smaller pore size, which plays a crucial role in improving filtration efficiency.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-efficiency, comfortable air filtration and protective material spun by electrospinning, characterized in that: The membrane filter media is composed of a fluffy sandwich structure consisting of a bimodal fiber layer and a beaded fiber layer; from top to bottom, the sandwich structure membrane filter media consists of the windward side of the bimodal fiber membrane, the middle layer of the beaded fiber membrane, and the leeward side of the bimodal fiber membrane. By doping a third component into a polymer solution to form ion-dipole interactions, a solution system with high conductivity and weak intermolecular interactions was customized. Electrospinning technology was then used to promote the detachment of some molecular chains from the spinning jet, resulting in splitting and solidification, thus preparing a bimodal fiber layer composed of ultrafine nanofibers and submicron fibers. Furthermore, by controlling the Rayleigh instability of the electrospinning dilute solution jet, a beaded fiber layer composed of micron-sized beads and submicron fibers was prepared. The third component is an amphiphilic substance composed of hydrophilic ionic groups and lipophilic alkane chains. This type of substance improves the conductivity of the solution and weakens the binding force between polymer molecular chains through ion-dipole interactions. The hydrophilic third component absorbs water molecules from the external environment, thereby better displacing the solvent in the solution system and promoting the solidification of the spinning jet into fibers. The third component is 2,3-epoxypropyltrimethylammonium chloride.

2. The method for preparing the electrospun high-efficiency comfortable air filtration and protective material according to claim 1, characterized in that, Includes the following steps: (1) Preparation of bimodal fibers: The spinning solution consists of polymer, solvent and third component; draw an appropriate amount of solution with a syringe, connect the needle to the positive terminal of the power supply, set appropriate voltage, receiving distance and injection rate parameters, and the receiving substrate is polypropylene nonwoven fabric; (2) Preparation of beaded fibers: The spinning solution consists of polymer and solvent; draw an appropriate amount of solution with a syringe, connect the needle to the positive terminal of the power supply, and set appropriate voltage, receiving distance and injection rate parameters; (3) The sandwich structure membrane filter material is obtained by layer-by-layer stacking electrospinning method.

3. The method according to claim 2, characterized in that, The preparation method of the polymer solution in step (1) includes: first, adding the third component to the solvent, stirring with a magnetic stirrer at room temperature for 60~180 min until the solution becomes clear and transparent, then adding the polymer, and stirring continuously with a magnetic stirrer at room temperature or under heating for 8~24 h.

4. The method according to claim 2, characterized in that, In step (1), the polymer solution contains a polymer mass fraction of 2–10 wt%, the third component accounts for 2–10% of the polymer mass, the viscosity of the polymer solution ranges from 50 to 1500 mPa·s, and the conductivity ranges from 1 to 1000 µS·cm. -1 .

5. The method according to claim 2, characterized in that, In step (2), the polymer solution used to prepare the beaded fiber is a dilute solution with a polymer mass fraction of 1 to 8 wt% and a viscosity range of 1 to 100 mPa·s.

6. The method according to claim 2, characterized in that, The polymer used in steps (1) and (2) is PA6, and the solvents include hexafluoroisopropanol and trifluoroethanol.

7. The method according to claim 2, characterized in that, In steps (1) and (2), the voltage during electrospinning is 10-25 kV, and the spinning flow rate is set to 0.1-2.0 mL·h. -1 The receiving distance is 10-20 cm, the metal needle of the syringe is 18-22#, the ambient temperature is maintained at 20-35 ℃, and the relative humidity is 30-90%.

8. The method according to claim 2, characterized in that, The diameter of the nanofibers in the bimodal fiber is 10~90 nm, and the diameter of the submicron fiber is 100~200 nm; the beaded fiber is composed of 2~3 μm beads and submicron fibers, and the average pore size of the sandwich structure membrane filter material is ≤2 μm.

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