Wet film, method for producing the same, humidifier, and air processing device

Abstract

The application provides a wet film, a preparation method thereof, a humidifier and an air treatment device. The wet film comprises a non-woven fabric, a PAN nanofiber layer and a SiO2 nanoparticle layer, the PAN nanofiber layer is arranged on one side surface of the non-woven fabric, the SiO2 nanoparticle layer is arranged on a surface of the PAN nanofiber layer, and the PAN nanofiber layer is located between the non-woven fabric and the SiO2 nanoparticle layer. According to the technical scheme, the non-woven fabric material is used as a base material of the humidifying film material and is compounded with the PAN nanofiber layer. The PAN nanofiber has good hydrophilic performance, the PAN nanofiber is deposited on the surface of the base material, and then the hydrophilic nano SiO2 particles are loaded on the surface of the PAN nanofiber film, so that different roughness gradients are constructed and the hydrophilic performance of the material itself is further improved. Therefore, the composite wet film has high water absorption performance and humidification capacity.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a wet film and its preparation method, a humidifier, and an air treatment device. Background Technology

[0002] Currently, the most common humidifying membrane material on the market is spunlace nonwoven fabric made of PET / viscose fiber blend, which is used in downdraft wet membrane humidifiers to distribute water by utilizing the material's water absorption properties. Viscose fiber serves as the water-absorbing component, while PET fiber serves as the supporting component.

[0003] However, the current wet film has uneven moisture distribution, and the upper part of the wet film cannot absorb moisture. The humidification performance depends heavily on the water absorption performance of the humidification film material. The water absorption height is low and the water absorption speed is slow, resulting in poor humidification performance. Summary of the Invention

[0004] This invention proposes a wet membrane designed to address the problem of poor humidification performance of existing wet membranes.

[0005] To address the above problems, the present invention proposes a wet film comprising:

[0006] Nonwoven fabric;

[0007] A PAN nanofiber layer is disposed on one side surface of the nonwoven fabric;

[0008] A SiO2 nanoparticle layer is disposed on the surface of the PAN nanofiber layer;

[0009] The PAN nanofiber layer is located between the nonwoven fabric and the SiO2 nanoparticle layer.

[0010] In one embodiment, the nonwoven fabric is prepared by blending PET fibers and viscose fibers.

[0011] In one embodiment, the PAN nanofiber layer is formed on the surface of the nonwoven fabric by an electrospinning process.

[0012] In one embodiment, the SiO2 nanoparticle layer is formed on the surface of the PAN nanofiber layer by an electrostatic spraying process.

[0013] In one embodiment, the loading ratio of PAN nanofibers in step b to SiO2 nanoparticles in step d is: 1 / 3.5 ≤ PAN / SiO2 ≤ 1 / 1.

[0014] In one embodiment, the diameter of the PAN nanofibers ranges from 0.1 μm to 0.7 μm.

[0015] In one embodiment, the particle size of the SiO2 microspheres ranges from 1.0 to 30 μm.

[0016] In one embodiment, the thickness of the wet film is 0.02 mm to 0.12 mm.

[0017] In one embodiment, the wet film is arranged in a serrated shape.

[0018] In one embodiment, the tooth height of the wet film is 20 mm to 40 mm.

[0019] In one embodiment, the interdental spacing of the wet film is 3 mm to 8 mm.

[0020] The present invention also provides a method for preparing a wet film, comprising the following steps:

[0021] a. Prepare PAN / DMF electrospinning solution;

[0022] b. The PAN / DMF electrospinning solution is deposited on the surface of a nonwoven fabric through an electrospinning process, and the composite film is obtained after drying.

[0023] c. Prepare PAN / SiO2 / DMF spinning solution;

[0024] d. The PAN / SiO2 / DMF spinning solution is electrosprayed onto the surface of the PAN nanofiber layer of the composite membrane using an electrostatic spraying process, and then dried.

[0025] In one embodiment, in step a, the concentration of the PAN / DMF electrospinning solution is 5wt% to 12wt%.

[0026] In one embodiment, in step b, the PAN loading of the composite membrane is greater than 0 and not greater than 1.0 mL / cm.

[0027] In one embodiment, in step c, the concentration of the PAN / SiO2 / DMF spinning solution is 1wt% to 5wt%, wherein the proportion of SiO2 in the PAN / SiO2 / DMF spinning solution is 4wt% to 8wt%.

[0028] In one embodiment, in step d, the SiO2 loading is greater than 0 and not greater than 1.0 mL / cm.

[0029] This application also provides a humidifier, including a support and a wet membrane. The wet membrane includes a nonwoven fabric, a PAN nanofiber layer, and a SiO2 nanoparticle layer. The PAN nanofiber layer is disposed on one side surface of the nonwoven fabric. The SiO2 nanoparticle layer is disposed on the surface of the PAN nanofiber layer. The PAN nanofiber layer is located between the nonwoven fabric and the SiO2 nanoparticle layer. The wet membrane is mounted on the support.

[0030] This application also provides an air treatment device, including a humidifier. The humidifier includes a support and a wet film. The wet film includes a nonwoven fabric, a PAN nanofiber layer, and a SiO2 nanoparticle layer. The PAN nanofiber layer is disposed on one side surface of the nonwoven fabric. The SiO2 nanoparticle layer is disposed on the surface of the PAN nanofiber layer. The PAN nanofiber layer is located between the nonwoven fabric and the SiO2 nanoparticle layer. The wet film is mounted on the support.

[0031] The technical solution of this invention involves compositely using a nonwoven fabric as the substrate for the humidifying membrane material with a PAN nanofiber layer. Based on the good hydrophilic properties of PAN nanofibers, PAN nanofibers are deposited on the substrate surface, and then hydrophilic nano-SiO2 particles are loaded onto the PAN nanofiber membrane surface to construct different roughness gradients, further improving the hydrophilicity of the material itself. This results in a composite humidifying membrane with high water absorption and humidification capacity. Attached Figure Description

[0032] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the composite wet membrane of the present invention;

[0034] Figure 2 This is a schematic diagram of humidification using a humidifying filter.

[0035] Figure 3 for Figure 2 A top view of the medium-humidity membrane, where the wet membrane is a serrated humidification filter element;

[0036] Figure 4 The image shows a SEM image of CA nanofibers, in which CA forms uniformly sized fibers with diameters ranging from 0.5 to 0.6 μm on a polyester / viscose blended spunlace nonwoven substrate.

[0037] Explanation of icon numbers:

[0038]

[0039]

[0040] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0041] 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 only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0043] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, if the word "and / or" appears throughout the text, it means including three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0044] Conventional wet humidifier films are typically made of spunlace nonwoven fabric blended with PET / viscose fibers. This type of nonwoven fabric has uneven moisture distribution. When used in humidifiers (with the film placed vertically and its lower end immersed in a water tank), the upper part of the film absorbs less moisture, or the absorption time is extremely long, resulting in a slow absorption rate and affecting the humidification effect. When the air handling unit is in humidification mode, because the film absorbs less moisture, the amount of moisture carried away by the air is also limited. Furthermore, after the moisture on the film is carried away by the air, the film itself takes a long time to absorb more moisture, and the carried-away moisture cannot be quickly absorbed from the water tank, thus severely hindering the humidification effect.

[0045] Please see Figure 1 This application relates to a composite wet membrane 100, comprising a nonwoven fabric 101, a PAN nanofiber layer 102 (PAN: polyacrylonitrile containing silver nanoparticles), and a SiO2 nanoparticle layer 103. The PAN nanofiber layer 102 is disposed on one side surface of the nonwoven fabric 101; the SiO2 nanoparticle layer 103 is disposed on the surface of the PAN nanofiber layer 102. The PAN nanofiber layer 102 is located between the nonwoven fabric 101 and the SiO2 nanoparticle layer 103.

[0046] Here, nonwoven fabric 101 refers to a fabric formed without spinning or weaving. It is created by orienting or randomly arranging short or long textile fibers to form a web structure, which is then reinforced using mechanical, thermal, or chemical methods. It is a novel fiber product with a soft, breathable, and planar structure, formed directly from polymer chips, short fibers, or filaments through various web-forming methods and bonding techniques. Simply put, nonwoven fabric 101 is not made by interlacing or knitting individual yarns, but by directly bonding fibers together using physical methods.

[0047] The aforementioned composite wet membrane 100 uses three layers of materials (non-woven fabric 101, PAN nanofiber layer 102, and SiO2 nanoparticle layer 103). The connection relationship between the three layers is unrestricted. For example, the non-woven fabric 101 and the PAN nanofiber layer 102 can be bonded together with an adhesive, or sewn together, or hot-pressed together; the PAN nanofiber layer 102 and the SiO2 nanoparticle layer 103 can also be bonded together with an adhesive, or sewn together, or hot-pressed together.

[0048] The main materials of the composite wet membrane 100 are nonwoven fabric, PAN nanofibers and SiO2 nanoparticles, all of which are mature raw material systems and do not involve high costs or high equipment requirements.

[0049] The composite wet membrane 100 uses PAN nanofibers and SiO2 nanoparticles to form a microsphere / nanofiber membrane with superhydrophilic properties, significantly improving the water absorption rate. Furthermore, the water absorption capacity of the superhydrophilic microsphere / nanofiber membrane effectively improves the water absorption performance of the PET / viscose nonwoven fabric 101.

[0050] The technical solution of this invention uses a nonwoven fabric 101 as the substrate material for the humidifying membrane 100 and composites it with a PAN nanofiber layer 102. Based on the good hydrophilic properties of PAN nanofibers, PAN nanofibers are deposited on the surface of the substrate, and then hydrophilic nano-SiO2 particles are loaded onto the surface of the PAN nanofiber membrane to construct different roughness gradients, further improving the hydrophilic properties of the material itself. This results in the composite humidifying membrane 100 of this invention having high water absorption and humidification capacity.

[0051] There are many types of nonwoven fabric 101, such as spunlace nonwoven fabric, needle-punched nonwoven fabric, heat-sealed nonwoven fabric, imitation adhesive meltblown nonwoven fabric, stitch-bonded nonwoven fabric, etc. Considering water absorption and air permeability, spunlace nonwoven fabric is used in this embodiment, specifically prepared by blending PET fiber and viscose fiber.

[0052] The above embodiments mention various connection relationships between the PAN nanofiber layer 102 and the nonwoven fabric 101. In this embodiment, in order to make the connection between the PAN nanofiber layer 102 and the nonwoven fabric 101 more reliable and not affect the performance of the two, the PAN nanofiber layer 102 is formed on the surface of the nonwoven fabric 101 by electrospinning.

[0053] It should be noted that electrospinning, or electrospinning, mainly utilizes a high-voltage electrostatic field to charge the polymer solution or melt, causing it to deform and form a suspended cone-shaped droplet at the nozzle tip. When the repulsive force of the charge on the droplet surface exceeds its surface tension, the droplet surface will eject a stream of tiny polymer droplets at high speed, referred to as a "jet." These jets undergo high-speed stretching, solvent evaporation, and solidification within a short distance under the influence of the electric field, ultimately depositing on the receiver.

[0054] In the electrospinning process, the jetting device is filled with a charged polymer solution or molten liquid. Under the action of an applied electric field, the polymer droplets, held at the nozzle by surface tension, accumulate surface charges under the induction of the electric field, and are subjected to an electric force opposite to the direction of surface tension. As the electric field gradually increases, the droplets at the nozzle are elongated from a spherical shape to a cone shape, forming a so-called Taylor cone. When the electric field strength increases to a critical value, the electric force overcomes the surface tension of the liquid, and the droplets are ejected from the Taylor cone. The jet oscillates and becomes unstable under the action of a high electric field, generating irregular spiral motions with extremely high frequencies. In the high-speed oscillation, the jet is rapidly thinned, and the solvent evaporates rapidly, eventually forming fibers with diameters on the nanometer scale, which are randomly scattered on the nonwoven fabric 101 to form polymer fibers.

[0055] After the PAN nanofiber layer 102 is formed on the surface of the nonwoven fabric 101 by electrospinning, the SiO2 nanoparticle layer 103 is formed on the surface of the PAN nanofiber layer 102 by electrostatic spraying.

[0056] Here, the addition of SiO2 causes a significant change in the surface morphology of PAN / SiO2 composite nanofibers. SiO2 particles appear on the surface of the nanofibers, and the SiO2 particles can form a microsphere layer / nanofiber membrane with superhydrophilic properties, thereby significantly improving the water absorption rate.

[0057] The specific manufacturing process for composite wet film 100 is as follows:

[0058] a. Prepare PAN / DMF electrospinning solution.

[0059] b. The PAN / DMF electrospinning solution is deposited on the surface of the nonwoven fabric 101 by electrospinning process, and the composite film is obtained after drying.

[0060] c. Prepare PAN / SiO2 / DMF spinning solution.

[0061] d. The PAN / SiO2 / DMF spinning solution is electrosprayed onto the surface of the PAN nanofiber layer 102 of the composite membrane using an electrostatic spraying process, and then dried.

[0062] In step a, the concentration of the electrospinning solution is 5 to 12 wt% (e.g., 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%), and then the prepared electrospinning solution is injected into the syringe of the electrospinning equipment.

[0063] In step b, adjust parameters such as infusion speed, working voltage, receiving distance, roller speed, slide table, temperature, and humidity. After electrospinning for different times, remove the composite film from the roller and place it in a vacuum oven to dry.

[0064] The specific parameters of the spinning equipment in the experiment were as follows: injection speed 0.5–2 mL / h, voltage 15–50 kV, receiving distance 18–36 cm, roller speed 38–63 rpm, slide table 7–10 cm / 80; temperature 25±2℃, humidity 45±5%. After electrospinning for different times, composite films with PAN loading of 0–1.0 mL / cm were obtained and dried in a vacuum oven at 80℃ for 3 hours. Here, the PAN loading should not be too high, because an excessively high PAN loading will lead to an increase in the fiber diameter in the PAN fiber layer 102. Although the water absorption rate can increase, the air resistance also increases at the same time. Therefore, the PAN loading was set between 0 and 1.0 mL / cm.

[0065] In step c, a PAN / SiO2 / DMF spinning solution with a concentration of 1–5 wt% (e.g., 2 wt%, 3 wt%, 4 wt%) is prepared and injected into the syringe of an electrospinning device. The composite film obtained in the previous step is used as the base fabric. The proportion of SiO2 in the PAN / SiO2 / DMF spinning solution is 4 wt%–8 wt%. As the SiO2 loading increases, the aggregation of SiO2 particles becomes more severe, and the SiO2 particle size increases accordingly. This blocks some of the capillary wicking channels, which in turn gradually reduces the water absorption rate of the wet film.

[0066] The reason for limiting the proportion of SiO2 in the PAN / SiO2 / DMF spinning solution is that if the proportion of SiO2 is too small, the subsequent electro-spraying efficiency will be low and the SiO2 adhesion effect will be poor; if the proportion of SiO2 is too high, the SiO2 loading rate will increase rapidly in the subsequent electro-spraying process, making it difficult to control.

[0067] In step d, the parameters of the electrospinning equipment were as follows: injection rate 0.5–2 mL / h, voltage 15–50 kV, receiving distance 18–36 cm, roller speed 38–63 rpm, slide table 7–10 cm / 80; temperature 25 ± 2℃, humidity 45 ± 5%. After electrospinning for different times, composite membranes with PAN loading of 0–1.0 mL / cm were obtained and dried in a vacuum oven at 80℃ for 3 hours. Here, the SiO2 loading of the composite membrane was limited to the range of 0–1.0 mL / cm to account for the aggregation of SiO2 particles.

[0068] In one embodiment, the loading ratio of PAN nanofibers in step b to SiO2 nanoparticles in step d is: 1 / 3.5≤PAN / SiO2≤1 / 1. The specific reasons will be explained in the subsequent experimental data.

[0069] The addition of SiO2 significantly altered the surface morphology of the PAN / SiO2 composite nanofibers. Agglomerated SiO2 particles appeared on the nanofiber surface, and the agglomeration became increasingly severe with increasing SiO2 loading, leading to an increase in SiO2 particle size. This blocked some of the capillary pores, resulting in an initial increase followed by a decrease in water absorption rate. Furthermore, as the SiO2 loading increased, the fiber diameter also increased, thereby increasing the thickness of the composite fiber layer. This, in turn, increased the water absorption rate and air resistance, resulting in a trend of initial increase followed by a decrease in humidification capacity.

[0070] To test the correlation between the manufacturing process of the composite wet film 100 and its overall performance, the following experiment was conducted:

[0071] Based on different PAN / SiO2 loading ratios, embodiments of the present invention provide nonwoven fabric 101 / electrospun PAN-SiO2 fiber membrane composite humidifying membrane 100 materials of different thicknesses. For example... Figure 2 As shown, the composite humidifying membrane 100 material is folded to form a sawtooth-shaped humidifying filter element. The sawtooth height H1 is 30mm, and the tooth spacing 21 is 5mm. The sawtooth-shaped humidifying filter element is placed vertically on the water tank 300 (placement method as shown). Figure 3 As shown), the humidifying filter element draws water from the water tank 300, and air enters from the air inlet 210 and passes vertically through the humidifying filter element. The composite membrane of the humidifying filter element is on the windward side, and the substrate is on the leeward side. After the water vapor passes through the composite membrane and the substrate, it is blown out from the air outlet 220.

[0072] Performance testing:

[0073] The water absorption rate, water absorption ratio, air resistance, and humidification capacity of Examples 1-6 were tested using the following methods:

[0074]

[0075] Water absorption rate test: Refer to GB / T 21655.1-2008.

[0076] Water absorption test: Refer to GB / T 21655.1-2008.

[0077] Wind resistance: Refer to GB / T 14295-2008.

[0078] Humidification capacity test: Refer to GB / T 23332-2009.

[0079] Test results:

[0080] Combination Figure 4 (a) is an electron microscope image of PET / viscose nonwoven fabric 101, which shows that the material is made by blending cylindrical PET fibers and grooved viscose fibers.

[0081] (b) is an SEM image of PAN nanofibers deposited on nonwoven fabric 101 substrate by electrospinning technology. It can be seen that the PAN nanofibers are fine in diameter and uniformly distributed, with good fiber morphology and a diameter of 0.4-0.5 μm.

[0082] (c) Hydrophilic SiO2 nanoparticles are electrosprayed onto PAN nanofiber membranes using electrostatic spraying technology to construct a multi-level nano-SiO2 particle microsphere layer with a particle size of 16-20 μm.

[0083] (d) is a cross-sectional electron microscope image of the composite humidification membrane 100. We can clearly see the three-layer structure of the composite membrane: the top layer is SiO2 nanoparticles, the middle layer is PAN nanofiber layer 102, and the bottom layer is spunlace nonwoven fabric 101; the thickness of the PAN / SiO2 composite membrane is about 0.08 mm.

[0084] As can be seen from Examples 1 to 6, its water absorption rate is obviously higher than that of the comparative example, and its water absorption rate is also higher than that of the comparative example. The addition of appropriate amount of water also significantly exceeds that of the comparative example. However, its wind resistance is also higher than that of the comparative example (especially Examples 5 and 6).

[0085] However, the situation changed in Example 7. When the negative PAN / SiO2 loading ratio was 1 / 4, the PAN fiber diameter reached 0.7 to 0.8, the SiO2 particle diameter reached 31 to 35 μm, and the composite film thickness reached 0.15 mm, although the water absorption rate increased, the water absorption rate actually decreased for the first time, and the humidification amount decreased significantly (compared to Example 6).

[0086] Cause Analysis: Among the four factors—PAN / SiO2 loading ratio, PAN fiber diameter, SiO2 particle diameter, and composite film thickness—the parameters with the largest variations are the PAN / SiO2 loading ratio, SiO2 particle diameter, and composite film thickness (of course, the PAN fiber diameter also has an impact, but its variation is small and its influence is relatively minor). Therefore, it can be preliminarily determined that the PAN / SiO2 loading ratio should not be lower than 1 / 4, the PAN fiber diameter should not be higher than 0.7 μm, the SiO2 particle diameter should not be higher than 30 μm, and the composite film thickness should not be higher than 0.15 mm. In Examples 1 to 6, the PAN nanofiber diameter ranged from 0.1 μm to 0.7 μm; the SiO2 microsphere particle size ranged from 1.0 μm to 30 μm; and the thickness of the wet film 100 was 0.02 mm to 0.12 mm; all of these are preferred embodiments.

[0087] Furthermore, setting the wet film 100 in a serrated shape can increase its contact area with air, thereby improving the water absorption rate and humidification capacity. The tooth height of the wet film 100 should not be too large or too small. If it is too large, the wet film 100 will occupy too much thickness space, and if it is too small, it will affect the humidification effect of the wet film 100. In this embodiment, the tooth height of the wet film 100 is 20mm to 40mm.

[0088] The tooth spacing 21 of the wet membrane 100 also needs to be appropriately limited. If the spacing is too large, it will reduce the contact area between the wet membrane 100 and the air. If the spacing is too small, it will increase the wind resistance of the wet membrane 100. Therefore, in this embodiment, the tooth spacing 21 of the wet membrane 100 is 3mm to 8mm.

[0089] In addition, the present invention also provides a humidifier 20, which includes a support and a wet film 100 mounted on the support. The wet film 100 itself can be constructed in a flat, cylindrical, or arc shape, and the support can be adapted to the specific shape of the wet film 100.

[0090] The present invention also provides an air handling device, please refer to [link / reference]. Figure 3 The air handling unit is equipped with the aforementioned humidifier 20. Here, the air handling unit can be an air conditioner, a humidifier, or a fan.

[0091] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A wet membrane used in a humidifying device, the wet membrane being placed vertically with its lower end immersed in a water tank, characterized in that, include: A nonwoven fabric, wherein the nonwoven fabric is prepared by blending PET fibers and viscose fibers; A PAN nanofiber layer is disposed on one side surface of the nonwoven fabric; A SiO2 nanoparticle layer is disposed on the surface of the PAN nanofiber layer; The PAN nanofiber layer is located between the nonwoven fabric and the SiO2 nanoparticle layer to construct different roughness gradients. The method for preparing the wet film includes the following steps: a. Prepare PAN / DMF electrospinning solution; b. The PAN / DMF electrospinning solution is deposited on the surface of a nonwoven fabric through an electrospinning process, and the composite film is obtained after drying. c. Prepare PAN / SiO2 / DMF spinning solution; d. The PAN / SiO2 / DMF spinning solution is electrosprayed onto the surface of the PAN nanofiber layer of the composite membrane using an electrostatic spraying process, and then dried. The loading ratio of PAN nanofibers in step b to SiO2 nanoparticles in step d is: 1 / 3.5≤PAN / SiO2≤1 / 1; The PAN nanofiber layer has a fiber diameter range of 0.1μm to 0.7μm; the SiO2 nanoparticle layer has a SiO2 microsphere size range of 1.0μm to 30μm; and the wet film has a thickness of 0.02mm to 0.12mm.

2. The wet film as described in claim 1, characterized in that, The PAN nanofiber layer is formed on the surface of the nonwoven fabric by electrospinning.

3. The wet film as described in claim 1, characterized in that, The SiO2 nanoparticle layer is formed on the surface of the PAN nanofiber layer by electrostatic spraying.

4. The wet film according to any one of claims 1 to 3, characterized in that, The wet film is arranged in a serrated shape.

5. The wet film as described in claim 4, characterized in that, The tooth height of the wet film is 20mm~40mm; and / or The inter-tooth spacing of the wet film is 3mm to 8mm.

6. The method for preparing the wet film according to any one of claims 1 to 5, characterized in that, Includes the following steps: a. Prepare PAN / DMF electrospinning solution; b. The PAN / DMF electrospinning solution is deposited on the surface of a nonwoven fabric through an electrospinning process, and the composite film is obtained after drying. c. Prepare PAN / SiO2 / DMF spinning solution; d. The PAN / SiO2 / DMF spinning solution is electrosprayed onto the surface of the PAN nanofiber layer of the composite membrane using an electrostatic spraying process, and then dried. The loading ratio of PAN nanofibers in step b to SiO2 nanoparticles in step d is: 1 / 3.5 ≤ PAN / SiO2 ≤ 1 / 1.

7. The method for preparing a wet film as described in claim 6, characterized in that, In step a, the concentration of the PAN / DMF electrospinning solution is 5wt%~12wt%.

8. The method for preparing a wet film as described in claim 7, characterized in that, In step b, the PAN loading of the composite membrane is greater than 0 and not greater than 1.0 mL / cm.

9. The method for preparing a wet film as described in claim 8, characterized in that, In step c, the concentration of the PAN / SiO2 / DMF spinning solution is 1wt%~5wt%, wherein the proportion of SiO2 in the PAN / SiO2 / DMF spinning solution is 4wt%~8wt%.

10. The method for preparing a wet film as described in claim 9, characterized in that, In step d, the SiO2 loading is greater than 0 and not greater than 1.0 mL / cm.

11. A humidifier, characterized in that, It includes a support and a wet membrane as described in any one of claims 1 to 5, wherein the wet membrane is mounted on the support.

12. An air handling device, characterized in that, Including the humidifier as described in claim 11.

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