A high humidity resistant filter medium and its preparation method

Abstract

The present invention belongs to the technical field of protective materials, and relates to a high-humidity-resistant filter material and a preparation method thereof. The method includes: the filter material main body is sequentially stacked with a first hydrophilic fiber layer, a second hydrophilic fiber layer, and a core filter layer from outside to inside; the thickness of the second hydrophilic fiber layer increases in a gradient from top to bottom. The beneficial effects are that after water is fully diffused in the first hydrophilic fiber layer, it is transmitted to the second hydrophilic fiber layer. The second hydrophilic fiber layer has a wedge-shaped structure with a small thickness at the upper end and a large thickness at the lower end, ensuring that the absorbed water finally converges to the bottom, so that the resistance of the filter material increases slowly during long-term use. The filter material provided by the present invention can enable water to diffuse in a gradient in a short time, greatly alleviate the problem of rapid increase in the resistance of the filter material in a high-humidity environment, and at the same time protect the static electricity of the core filter layer from being affected by humidity, achieving high efficiency and low resistance within the service life of the filter material.

Description

Technical Field

[0001] The present invention relates to the technical field of protective materials, and in particular to a high-humidity-resistant filter material and a preparation method thereof. Background Art

[0002] Fiber filter materials are widely used in the field of air filtration, and their most important filtration performances include filtration efficiency and resistance. With the emergence of high-efficiency filter materials such as nanofiber filter materials, high-density surface layer filter materials, and electrostatic filter materials, high filtration efficiency is no longer the main problem. The filter material resistance is too high, especially in a high-humidity environment, the resistance of the filter material increases rapidly in a short time, which has become a key problem that needs to be solved urgently for the existing filter materials.

[0003] To address the problem of the too-fast increase in the resistance of the filter material in a high-humidity environment, the main technical measures currently taken are to perform super-hydrophobic treatment on the filter material, so that water vapor can pass through the filter material without clogging the pores of the filter material. However, in the case where water vapor and liquid droplets coexist, the liquid droplets will accumulate on the surface of the hydrophobic filter material and clog the pores of the filter material, causing the resistance of the filter material to increase rapidly. For example, in a tunnel mining working face, a combination of spray dust suppression and filter material dust removal is often used, and the liquid droplets generated by spraying will cause the resistance of the filter material to rise rapidly, greatly affecting the normal use of the filter material.

[0004] Therefore, the super-hydrophobic filter material cannot solve the problem of the rapid increase in resistance in the case of the coexistence of water vapor and liquid droplets. Summary of the Invention

[0005] Technical problems to be solved:

[0006] In view of the above-mentioned disadvantages and deficiencies of the prior art, the present invention provides a high-humidity-resistant filter material and a preparation method thereof, which solve the technical problem of how to alleviate the too-fast increase in the resistance of the filter material in a high-humidity environment.

[0007] Technical solutions:

[0008] To achieve the above object, the main technical solutions adopted by the present invention include:

[0009] In the first aspect, the present invention provides a high-humidity-resistant filter material, and the filter material main body is sequentially stacked with a first hydrophilic fiber layer, a second hydrophilic fiber layer, and a core filter layer from outside to inside;

[0010] The thickness of the second hydrophilic fiber layer increases in a gradient from top to bottom.

[0011] Optionally, the material of the first hydrophilic fiber layer is hydrophilic polyester, hydrophilic polyurethane with a water absorption speed greater than 0.2 cm / s, or hollow fiber with capillary action.

[0012] Optionally, the thickness of the first hydrophilic fiber layer is 3 mm to 5 mm.

[0013] Optionally, the second hydrophilic fiber layer is a hydrophilic fiber web wrapping superabsorbent resin particles or powder, and the superabsorbent resin particles or powder are evenly distributed between two hydrophilic fiber webs.

[0014] Optionally, the superabsorbent resin in the second hydrophilic fiber layer is polyacrylate, starch acrylate polymer, starch-acrylonitrile graft copolymer or acrylamide-acrylonitrile-acrylic acid terpolymer with a water absorption capacity of more than 30 g / g.

[0015] Optionally, the upper part of the second hydrophilic fiber layer has a thickness of 2 mm to 4 mm, and the lower part has a thickness of 4 mm to 10 mm.

[0016] Optionally, the core filter layer is one of electret filter materials with electrostatic action, specifically melt-blown polypropylene or electrospun nanofiber membrane.

[0017] Optionally, the core filter layer has a thickness of 5 mm to 15 mm.

[0018] In a second aspect, the present invention provides a method for preparing a high-humidity resistant filter material, including:

[0019] S1. Prepare the core filter layer by melt-blown, electrospinning or corona electret;

[0020] S2. Prepare a second hydrophilic fiber layer with an increasing thickness gradient from top to bottom from hydrophilic fibers or particles with a large water holding capacity;

[0021] S3. Stack the first hydrophilic fiber layer, the second hydrophilic fiber layer and the core filter layer in sequence from outside to inside;

[0022] S4. Tightly bond the first hydrophilic fiber layer, the second hydrophilic fiber layer and the core filter layer by hot pressing and / or gluing to form a high-humidity resistant filter material.

[0023] Beneficial effects:

[0024] The beneficial effects of the present invention are as follows: A high-humidity resistant filter material of the present invention has a multi-layer structure with a gradually changing hydrophilic property from the outside to the inside. The outermost layer is a hydrophilic fiber layer with a fast water absorption rate, the second layer is a hydrophilic fiber layer with a large water capacity, and the third layer is a core filter layer with an electrostatic adsorption effect. In a high-humidity environment, when water vapor or droplets come into contact with the filter material, they quickly diffuse in the hydrophilic fiber layer and do not form a liquid film to block the pores of the fiber mesh, ensuring that the resistance of the filter material does not increase rapidly in the initial stage of use. After the water fully diffuses in the hydrophilic fiber layer, it is transmitted to the hydrophilic fiber layer. The hydrophilic fiber layer has a wedge-shaped structure with a small thickness at the upper end and a large thickness at the lower end, ensuring that the absorbed water finally converges to the bottom, making the resistance of the filter material increase slowly during long-term use. The filter material provided by the present invention can enable the water to diffuse in a gradient within a short time, greatly alleviating the problem of rapid increase in the resistance of the filter material in a high-humidity environment. At the same time, it protects the static electricity of the core filter layer from being affected by humidity, achieving high efficiency and low resistance within the service life of the filter material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. is a schematic diagram of the overall structure of a high-humidity resistant filter material provided by an embodiment of the present invention;

[0026] Figure 2 FIG. is a test chart of the water absorption rate of the first hydrophilic fiber layer material (polyurethane) used in a high-humidity resistant filter material provided by an embodiment of the present invention;

[0027] Figure 3 FIG. is a test chart of the water absorption rate of the second hydrophilic fiber layer material (sodium polyacrylate) used in a high-humidity resistant filter material provided by an embodiment of the present invention;

[0028] Figure 4 FIG. is a graph showing the resistance growth trend of a high-humidity resistant filter material provided by an embodiment of the present invention under the condition of coexistence of water droplets and water vapor;

[0029] Figure 5 FIG. is a test chart of the water absorption rate of the first hydrophilic fiber layer material (polyester) used in a high-humidity resistant filter material provided by an embodiment of the present invention;

[0030] Figure 6 FIG. is an example diagram of a high-humidity resistant filter material provided by an embodiment of the present invention for use in an individual respiratory protection device;

[0031] Figure 7 FIG. is a graph showing the resistance growth of a high-humidity resistant filter material provided by an embodiment of the present invention for use in an individual respiratory protection device under high humidity.

[0032] DESCRIPTION OF REFERENCE NUMERALS:

[0033] 1: First hydrophilic fiber layer;

[0034] 2: Second hydrophilic fiber layer;

[0035] 3: Core filtration layer. Detailed implementation mode

[0036] To better explain the present invention for easier understanding, the present invention will be described in detail below in conjunction with the drawings through specific implementation modes. To better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0037] Embodiment 1

[0038] In the first aspect, referring to Figure 1 , this embodiment provides a high-humidity-resistant filter material. The filter material main body is sequentially stacked with a first hydrophilic fiber layer 1, a second hydrophilic fiber layer 2, and a core filtration layer 3 from outside to inside;

[0039] The thickness of the second hydrophilic fiber layer 2 increases in a gradient from top to bottom.

[0040] The first hydrophilic fiber layer 1 is a hydrophilic fiber material with a fast water absorption speed and a small volume expansion after water absorption; the second hydrophilic fiber layer 2 is a hydrophilic fiber material with a large water capacity; the core filtration layer 3 is a polypropylene meltblown cloth material with an electrostatic adsorption effect.

[0041] The high-humidity-resistant filter material is applied in a high-humidity environment, and the humidity of the high-humidity environment ≥ 100% (a mixed environment of water vapor and liquid droplets).

[0042] The mechanism by which the high-humidity-resistant filter material functions is as follows: After water vapor or liquid droplets come into contact with the filter material, they quickly diffuse in the first hydrophilic fiber layer 1 and do not form a liquid film to block the pores of the fiber mesh, ensuring that the resistance of the filter material does not increase rapidly at the initial stage of use. After the water fully diffuses in the first hydrophilic fiber layer 1, it is transmitted to the second hydrophilic fiber layer 2. The second hydrophilic fiber layer 2 has a wedge-shaped structure with a small thickness at the upper end and a large thickness at the lower end, ensuring that the absorbed water finally converges to the bottom, making the resistance of the filter material grow slowly during long-term use and protecting the core filtration layer from charge decay under the action of humidity.

[0043] Optionally, the material of the first hydrophilic fiber layer 1 is one of hydrophilic materials such as hydrophilic polyester, hydrophilic polyurethane, and hollow fibers with capillary action whose water absorption speed is greater than 0.2 cm / s.

[0044] Optionally, the thickness of the first hydrophilic fiber layer 1 is 3 mm to 5 mm.

[0045] Optionally, the second hydrophilic fiber layer 2 is a hydrophilic fiber web wrapping superabsorbent resin particles or powder, and the superabsorbent resin particles or powder are evenly distributed between two hydrophilic fiber webs.

[0046] Optionally, the superabsorbent resin in the second hydrophilic fiber layer 2 is one of superabsorbent resins such as polyacrylate, starch acrylate polymer, starch-acrylonitrile graft copolymer, or acrylamide-acrylonitrile-acrylic acid terpolymer with a water absorption capacity greater than 30 g / g (30 g of water can be absorbed per g of superabsorbent resin).

[0047] Optionally, the upper part of the second hydrophilic fiber layer 2 has a thickness of 2 mm to 4 mm, and the lower part has a thickness of 4 mm to 10 mm.

[0048] Optionally, the core filtration layer is one of electret filters with electrostatic action, specifically melt-blown polypropylene or electrospun nanofiber membranes.

[0049] Optionally, the core filtration layer has a thickness of 5 mm to 15 mm.

[0050] Second, this embodiment provides a method for preparing a high-humidity-resistant filter medium, including:

[0051] S1. Prepare the core filtration layer by melt-blown, electrospinning, or corona electretization;

[0052] S2. Prepare the second hydrophilic fiber layer 2 with an increasing thickness gradient from top to bottom from hydrophilic fibers or particles with a large water holding capacity;

[0053] S3. Stack the first hydrophilic fiber layer 1, the second hydrophilic fiber layer 2, and the core filtration layer 3 in sequence from outside to inside;

[0054] S4. Tightly bond the first hydrophilic fiber layer 1, the second hydrophilic fiber layer 2, and the core filtration layer 3 by hot pressing and / or gluing to form a high-humidity-resistant filter medium.

[0055] According to the method for preparing a high-humidity-resistant filter medium provided in this embodiment, since it is used to prepare the high-humidity-resistant filter medium provided in the first aspect embodiment of the present invention, this method for preparing a high-humidity-resistant filter medium has all the technical effects of this high-humidity-resistant filter medium, which will not be elaborated here.

[0056] Embodiment 2

[0057] Refer to the appendix Figure 1 Prepare a high-humidity-resistant filter medium with a sandwich structure. First, select a polyurethane fiber layer with a water absorption speed of 150 ms (time to absorb 1 ml of water) as the first hydrophilic fiber layer 1, as Figure 2 shown, and cut it to the required size. Weigh an appropriate amount of sodium polyacrylate (the appropriate standard is 5 g / cm 2 -10 g / cm2 ), particles, the water absorption rate of sodium polyacrylate particles is 6 s, as Figure 3 shown, the water holding capacity is 73 g / g (1 g of sodium polyacrylate can absorb 73 g of water). The particles are laid flat on the hot melt adhesive film according to the principle of thinner on top and thicker on the bottom as the second hydrophilic fiber layer 2. A polypropylene electret filter medium is prepared by the meltblowing process as the core filter layer.

[0058] The polyurethane first hydrophilic fiber layer 1, the sodium polyacrylate second hydrophilic fiber layer 2, the hot melt adhesive film, and the polypropylene core filter layer are laminated together by hot pressing to form a high humidity resistant filter medium. Compared with ordinary filter media, the high humidity resistant filter medium has a significantly slower increase in resistance in a high humidity environment. The resistance increase is less than 500 Pa within 4 hours, while the resistance of ordinary filter media increases by 1500 Pa, as Figure 4 . After testing in a high humidity environment, the efficiency of the high humidity resistant filter medium remains above 90%. For ordinary filter media, because the charge of the polypropylene core filter layer is neutralized by water vapor, the efficiency drops to 75%.

[0059] Example 3

[0060] Refer to the appendix Figure 1 Prepare a high humidity resistant filter medium with a sandwich structure. First, select a polyester fiber layer with a water absorption rate of 4 cm / min as the first hydrophilic fiber layer 1, as Figure 5 . Cut it to the required size. Weigh an appropriate amount of sodium polyacrylate (the appropriate standard is 5 g / cm 2 - 10 g / cm 2 ), the water absorption rate of sodium polyacrylate particles is 6 s, as Figure 3 shown, the water holding capacity is 73 g / g (1 g of sodium polyacrylate can absorb 73 g of water). The particles are laid flat on the hot melt adhesive film according to the principle of thinner on top and thicker on the bottom as the second hydrophilic fiber layer 2. In this example, the second hydrophilic fiber layer 2 is in a trapezoidal structure. Laminating and compounding in the order of polyester fiber layer, sodium polyacrylate hydrophilic layer, polyester fiber layer, hot melt adhesive film, and polypropylene meltblown fabric to prepare a high humidity resistant filter medium.

[0061] Use the prepared high humidity resistant filter medium as the core filter of respiratory protection equipment, as Figure 6 shown. The respiratory protection equipment prepared with the high humidity resistant filter medium is tested in a mine 800 meters underground. The temperature in the mine is 40 °C, the relative humidity is 100%, and there is fine water mist. Compared with ordinary respiratory protection equipment, the respiratory protection equipment prepared with the high humidity resistant filter medium has a significantly slower increase in resistance in a high humidity environment. After 5 hours of use, the resistance increases to 450 Pa, while the resistance of ordinary respiratory protection equipment increases to 700 Pa, as Figure 7 , and the high humidity resistant filter medium significantly alleviates the respiratory discomfort caused by the increase in resistance.

[0062] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention should also cover these modifications and variations.

[0063] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A high humidity resistant filter medium, characterized in that, The filter media main body is sequentially stacked with a first hydrophilic fiber layer (1), a second hydrophilic fiber layer (2), and a core filter layer (3) from outside to inside; The first hydrophilic fiber layer (1) is a hydrophilic fiber material with a fast water absorption speed and a small volume expansion after water absorption; the thickness of the second hydrophilic fiber layer (2) increases in a gradient from top to bottom, and the second hydrophilic fiber layer (2) is high water absorption resin particles or powder with a large water holding capacity.

2. The high humidity resistant filter medium according to claim 1, characterized in that, The material of the first hydrophilic fiber layer (1) is hydrophilic polyester, hydrophilic polyurethane, or hollow fiber with capillary action.

3. The high humidity resistant filter medium according to claim 2, wherein, The thickness of the first hydrophilic fiber layer (1) is 3mm to 5mm.

4. The high-humidity resistant filter material according to claim 1, characterized in that, The high water absorption resin in the second hydrophilic fiber layer (2) is polyacrylate, starch acrylate polymer, starch-acrylonitrile graft copolymer, or acrylamide-acrylonitrile-acrylic acid terpolymer with a water absorption capacity greater than 30g / g.

5. The high-humidity resistant filter material according to claim 4, characterized in that, The upper part of the second hydrophilic fiber layer (2) has a thickness of 2mm to 4mm, and the lower part has a thickness of 4mm to 10mm.

6. The high humidity resistant filter medium according to claim 1, characterized in that The core filter layer is one of electret filter media with electrostatic action.

7. The high humidity resistant filter medium according to claim 6, characterized in that, The thickness of the core filter layer is 5mm to 15mm.

8. A method for preparing a high-humidity resistant filter medium as described in claim 1, characterized in that, Including: S1. Prepare the core filter layer by melt blowing, electrospinning, or corona electret; S2. Prepare the second hydrophilic fiber layer (2) with a thickness gradient increasing from top to bottom from high water absorption resin particles or powder with a large water holding capacity; S3. Stack the first hydrophilic fiber layer (1), the second hydrophilic fiber layer (2), and the core filter layer (3) sequentially from outside to inside; S4. Tightly bond the first hydrophilic fiber layer (1), the second hydrophilic fiber layer (2), and the core filter layer (3) by hot pressing and / or gluing to form a high humidity resistant filter media.

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