Single-layer filtering material as well as preparation method and application thereof

Abstract

The invention discloses a single-layer filtering material and a preparation method and application thereof, the preparation method comprises the following steps: a fiber felt prepared by a flash evaporation process has a surface A and a surface B opposite to each other in the thickness direction, the surface A is heated to reduce the average pore size of the surface A, and the single-layer filtering material is obtained; the temperature of the heating treatment is 120 to 200 DEG C, and the time of the heating treatment is 0.1 to 15 seconds. By controlling the temperature and time of the heating treatment, the average pore size of the A surface of the fiber felt is effectively reduced, so that the average pore size and the large average pore size of the B surface form a gradient, the three-dimensional network structure of the fiber felt is favorably kept, the collapse of the fiber felt is avoided, and the single-layer filtering material with the gradient average pore size is integrally prepared. In addition, dirt, dust, particles, suspended solids or other substances in the liquid flow can be blocked, and the dirt holding capacity of the single-layer filtering material is improved.

Description

Technical Field

[0001] This invention relates to the field of purification technology, and more specifically, to a single-layer filter material, its preparation method, and its application. Background Technology

[0002] With the technological upgrading in fields such as new energy, oil and gas chemicals, automotive coating, semiconductors, and life sciences, the demand for filtration and purification is increasing. Filter media are the core filter elements in the purification process, removing dirt, dust, particles, suspended solids, or other substances from liquid flows. As the usage time increases, the amount of dirt / dust on the filter media continues to accumulate. In particular, under high filtration precision, fluid resistance increases, shortening the replacement or rinsing cycle of the filter media, reducing the filtration efficiency and lifespan of the filter media, and increasing system energy consumption and material costs.

[0003] Currently, existing technologies attempt to improve filtration efficiency and lifespan by adjusting the structure of materials. One approach is to use pre-filters with coarser fiber diameters, typically exceeding 10-15 μm, to protect the final filter. However, this incurs costs and increases the filtration system's footprint, sacrificing compactness. A more conventional method utilizes gradient composite multilayer filter materials, with a coarse fiber surface layer and finer fibers (such as polymer nanofibers with diameters less than 1 μm) in the lower layers. This type of filter material, due to its gradient average pore size, offers higher filtration efficiency and lifespan than typical single-layer filter materials. However, this method often requires adhesives to bond and maintain the gradient average pore size composite multilayer structure. The use of adhesives not only introduces harmful substances and unpleasant odors, but the adhesive's bonding effect weakens over time, eventually failing to maintain the gradient average pore size composite multilayer structure, thus reducing the filter material's lifespan. Using single-layer filter materials with gradient average pore sizes can effectively solve these problems, improving filtration efficiency and lifespan without introducing additional harmful substances and unpleasant odors.

[0004] Therefore, developing a method for preparing single-layer filter materials to integrate the preparation of single-layer filter materials with gradient average pore size is of great significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a single-layer filter material, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing a single-layer filter material, comprising the following steps: The fiber felt has opposing A and B surfaces in the thickness direction. The A surface is heated to reduce the average pore size of the A surface, thus obtaining a single-layer filter material. The heat treatment is performed at a temperature of 120-200℃ for a duration of 0.1-15 seconds.

[0007] This invention effectively reduces the average pore size of the fiber felt on side A by controlling the temperature and time of the heat treatment, creating a gradient with the larger average pore size on side B. This helps maintain the three-dimensional network structure of the fiber felt and prevents it from collapsing, thus achieving the integrated fabrication of a single-layer filter material with a gradient average pore size. Furthermore, it helps to block dirt, dust, particles, suspended solids, or other substances in the liquid flow, increasing the dirt-holding capacity of the single-layer filter material.

[0008] Preferably, the temperature of the heat treatment is a range of one or any two of the following: 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, and 200°C.

[0009] More preferably, the temperature of the heat treatment is 130-200℃, specifically 135-200℃.

[0010] Preferably, the heating treatment time is 0.1s, 0.2s, 0.3s, 0.5s, 0.8s, 1s, 1.2s, 1.5s, 1.8s, 2s, 2.2s, 2.5s, 2.8s, 3s, 3.2s, 3.5s, 3.8s, 4s, 4.2s, 4.5s, 4.8s, 5s, 5.2s, 5.5s, 5.8s, 6s, 6.2s, 6.5s, 6.8s, 7s, 7.2s, 7.5s, or 7.8s. The range of values ​​for one or any two of the following: 8s, 8.2s, 8.5s, 8.8s, 9s, 9.2s, 9.5s, 9.8s, 10s, 10.2s, 10.5s, 10.8s, 11s, 11.2s, 11.5s, 11.8s, 12s, 12.2s, 12.5s, 12.8s, 13s, 13.2s, 13.5s, 13.8s, 14s, 14.2s, 14.5s, 14.8s, and 15s.

[0011] More preferably, the heating treatment time is 0.5-15s, specifically 5-15s.

[0012] Preferably, the heat treatment is performed by heating surface A with a metal plate.

[0013] Preferably, the average fiber diameter of the fiber felt on side A and / or side B is a value within the range of one or any two of the following: 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, and 20μm.

[0014] More preferably, the average fiber diameter of the fiber felt on side A and / or side B is 0.5-20 μm.

[0015] More preferably, the average fiber diameter of the fiber felt on side A and / or side B is 0.8-5 μm.

[0016] Preferably, the average pore size of the fiber felt A side and / or B side is a value within the range of one or any two of the following: 1μm, 3μm, 5μm, 8μm, 10μm, 13μm, 15μm, 18μm, 20μm, 23μm, 25μm, 28μm, 30μm, 33μm, 35μm, 38μm, and 40μm.

[0017] More preferably, the average pore size of the fiber felt A side and / or B side is 1-40 μm.

[0018] More preferably, the average pore size of the fiber felt A side and / or B side is 10-30 μm.

[0019] In this invention, when the fiber felt uses a specific average fiber diameter and average pore size and undergoes a specific heat treatment, the average pore size of the A-side of the fiber felt can be reduced more effectively, thereby better blocking dirt, dust, particles, suspended solids or other substances in the liquid flow and increasing the dirt holding capacity of the single-layer filter material; at the same time, it can also enhance and stabilize the three-dimensional network structure of the fiber felt, which can better improve the burst strength of the single-layer filter material.

[0020] In this invention, the fiber felt can be purchased commercially or prepared using conventional flash spinning methods in the art. The raw materials for preparing the fiber felt include, but are not limited to, at least one of polyethylene (PE), polyethylene glycol (PEG), polylactic acid-glycolic acid copolymer (PLGA), polylactic acid (PLA), polycaprolactone (PCL), polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), etc. When preparing the fiber felt using flash spinning, fiber felts with different average diameters can be obtained by controlling the concentration of the spinning solution (i.e., the concentration of the raw materials for preparing the fiber felt), temperature, pressure, and spinning aperture diameter. Fiber felts with different average pore sizes can be obtained by controlling the fiber stacking pattern and the number of stacked layers.

[0021] Preferably, the thickness of the fiber felt is one or any two of the following: 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, and 10mm.

[0022] More preferably, the thickness of the fiber felt is 0.1-10 mm.

[0023] More preferably, the thickness of the fiber felt is 0.1-0.8 mm, specifically 0.1-0.6 mm.

[0024] In this invention, the method for measuring the average diameter of fibers on the A-side and / or A'-side and / or B-side and / or B'-side in the fiber felt and / or single-layer filter material is as follows: Observe using a scanning electron microscope, randomly select 100 fibers with good morphology to measure their diameter using mapping software, calculate the average value, and obtain the average diameter of the fibers.

[0025] In this invention, the method for measuring the average pore size of the A-side and / or B-side of the fiber felt is as follows: a transverse cut is made at the midpoint along the thickness direction of the fiber felt to obtain two test samples containing the A-side and the B-side respectively. The test samples containing the A-side or the B-side are measured according to the standard method of GB / T32361-2015, using ethanol impregnation and N2 displacement, to obtain the average pore size of the A-side or the B-side of the fiber felt.

[0026] In this invention, the method for measuring the average pore size of the A' and B' surfaces in the single-layer filter material is as follows: a transverse cut is made along the midpoint of the thickness direction of the single-layer filter material to obtain two test samples containing the A' and B' surfaces respectively. The test samples containing the A' or B' surface are measured according to the GB / T 32361-2015 standard method, using ethanol impregnation and N2 displacement, to obtain the average pore size of the A' or B' surface of the single-layer filter material.

[0027] In this invention, the thickness of the fiber felt and / or single-layer filter material is measured using a Thwing Albert 89-100 thickness tester according to TAPPI standard T 411 om-2015.

[0028] Preferably, when heat-treating surface A, surface B of the fiber felt is opened to increase the average pore size of surface B.

[0029] In this invention, the opening process can be achieved using a brush or brush roller. The opening process can increase the average pore size of surface B, thereby further increasing the gradient of the average pore size of the single-layer filter material.

[0030] Compared to the opening process, the gradient average pore size structure obtained by heat treatment is more stable and robust, and is more conducive to maintaining the three-dimensional network structure of the fiber felt.

[0031] Preferably, before heating surface A, both surface A and surface B of the fiber felt are subjected to a first corona treatment simultaneously.

[0032] Preferably, after the heat treatment of surface A, a second corona treatment is performed on both surface A and surface B of the fiber felt.

[0033] In this invention, before and / or after heat treatment of surface A, both surfaces A and B of the fiber felt are simultaneously subjected to corona treatment (which can be achieved using a corona treatment machine). This oxidizes the fiber molecules, producing highly polar groups such as carbonyl groups and peroxides, which is beneficial for better capturing dirt, dust, particles, suspended solids, or other substances in the liquid flow, thereby further increasing the dirt-holding capacity of the single-layer filter material. At the same time, it helps to enhance the interaction forces between fibers, improve the stability of the three-dimensional network structure of the fiber felt, and thus further improve the burst strength of the single-layer filter material.

[0034] More preferably, the voltage of the first and / or second corona treatment is a value within the range of one or any two of the following: 5kV, 6kV, 7kV, 8kV, 9kV, 10kV, 11kV, 12kV, 13kV, 14kV, 15kV, 16kV, 17kV, 18kV, 19kV, 20kV, 21kV, 22kV, 23kV, 24kV, and 25kV.

[0035] More preferably, the voltage of the first and / or second corona treatment is 5-25kV, specifically 15-25kV.

[0036] More preferably, the duration of the first and / or second corona treatment is within the range of one or any two of the following: 0.1s, 0.2s, 0.3s, 0.4s, 0.5s, 0.6s, 0.7s, 0.8s, 0.9s, 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, and 10s.

[0037] More preferably, the time for the first and / or second corona treatment is 0.1-10s, specifically 0.5-5s.

[0038] In a second aspect, the present invention provides a single-layer filter material prepared by the preparation method described in the first aspect, wherein the single-layer filter material has opposing A' and B' surfaces in terms of thickness, wherein the A' surface is obtained by heat treatment of the A surface of a fiber felt.

[0039] Preferably, the average fiber diameter on side A' of the single-layer filter material is 0.5μm, 0.55μm, 0.6μm, 0.65μm, 0.7μm, 0.75μm, 0.8μm, 0.85μm, 0.9μm, 0.95μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 1 The range of values ​​for one or any two of the following: 3.5μm, 14μm, 14.5μm, 15μm, 15.5μm, 16μm, 16.5μm, 17μm, 17.5μm, 18μm, 18.5μm, 19μm, 19.5μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, and 45μm.

[0040] More preferably, the average fiber diameter of the single-layer filter material on the A' side is 0.5-45μm, specifically 0.6-40μm.

[0041] Preferably, the average aperture of surface A' is smaller than that of surface B', and the average aperture gradually increases from surface A' to surface B'.

[0042] In this invention, when surface A is heated to reduce its average aperture, the heat is transferred from surface A to surface B, and the amount of heat decreases, resulting in a gradual increase in the average aperture from surface A' to surface B'.

[0043] Preferably, the average pore size of the single-layer filter material on surface A' is 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 13.5μm, 14 ... The range of values ​​is one or any two of the following: μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, and 39μm.

[0044] More preferably, the average pore size of the single-layer filter material on surface A' is 0.1-39 μm, specifically 0.3-25 μm.

[0045] Preferably, the average fiber diameter on the B' side of the single-layer filter material is one or any two of the following values: 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.55μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, and 20μm.

[0046] More preferably, the average fiber diameter on the B' side of the single-layer filter material is 0.1-20 μm, specifically 0.3-20 μm.

[0047] Preferably, the average pore size of the single-layer filter material on surface B' is 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm. The range of values ​​is one or any two of the following: m, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, and 40μm.

[0048] More preferably, the average pore size of the single-layer filter material on the B' side is 0.1-40 μm, specifically 0.5-40 μm.

[0049] Preferably, the thickness of the single-layer filter material is one or any two of the following: 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, and 10mm.

[0050] More preferably, the thickness of the single-layer filter material is 0.1-10 mm.

[0051] The third invention provides an application of a single-layer filter material in filtration and purification.

[0052] The single-layer filter material of this invention can be used for filtration and purification in liquid environments.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention effectively reduces the average pore size of the fiber felt on side A by controlling the temperature and time of the heat treatment, creating a gradient with the larger average pore size on side B. This helps maintain the three-dimensional network structure of the fiber felt and prevents it from collapsing, thus achieving the integrated fabrication of a single-layer filter material with a gradient average pore size. Furthermore, it helps to block dirt, dust, particles, suspended solids, or other substances in the liquid flow, increasing the dirt-holding capacity of the single-layer filter material.

[0054] In this invention, when the fiber felt uses a specific average fiber diameter and average pore size and undergoes a specific heat treatment, the average pore size of the A-side of the fiber felt can be reduced more effectively, thereby better blocking dirt, dust, particles, suspended solids or other substances in the liquid flow and increasing the dirt holding capacity of the single-layer filter material; at the same time, it can also enhance and stabilize the three-dimensional network structure of the fiber felt, which can better improve the burst strength of the single-layer filter material.

[0055] In this invention, before and / or after heat treatment of surface A, both surfaces A and B of the fiber felt are simultaneously subjected to corona treatment (which can be achieved using a corona treatment machine). This oxidizes the fiber molecules, producing highly polar groups such as carbonyl groups and peroxides, which is beneficial for better capturing dirt, dust, particles, suspended solids, or other substances in the liquid flow, thereby further increasing the dirt-holding capacity of the single-layer filter material. At the same time, it helps to enhance the interaction forces between fibers, improve the stability of the three-dimensional network structure of the fiber felt, and thus further improve the burst strength of the single-layer filter material. Detailed Implementation

[0056] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0057] Examples 1-19 and Comparative Examples 1-3 Examples 1-16 and Comparative Examples 1-3 provide different single-layer filter materials and their preparation methods. The differences between them are the temperature and time of the heat treatment, the average fiber diameter and average pore size of the fiber felt, whether there is an opening treatment and a corona treatment, and the voltage and time of the corona treatment, as shown in Table 1. The preparation methods of the single-layer filter materials in Examples 1-16 and Comparative Examples 1-3 include the following steps: The fiber felt has opposing A and B sides in the thickness direction. The A and B sides are subjected to a first corona treatment simultaneously using a corona treatment machine. Then, the A side is placed on a heated metal plate and heated to reduce the average pore size of the A side. Next, the A and B sides are subjected to a second corona treatment simultaneously using a corona treatment machine, thus obtaining a single-layer filter material with a gradient average pore size. Example 17: A method for preparing a single-layer filter material, comprising the following steps: The fiber felt has opposing A and B sides in the thickness direction. The A and B sides are subjected to a first corona treatment using a corona treatment machine. Then, the A side is placed on a heated metal plate and heated to reduce the average pore size of the A side. At the same time, the B side of the fiber felt is loosened using a brush roller to increase the average pore size of the B side. Then, the A and B sides are subjected to a second corona treatment using a corona treatment machine, thus obtaining a single-layer filter material with a gradient average pore size. Example 18: A method for preparing a single-layer filter material, comprising the following steps: The fiber felt has opposing A and B sides in the thickness direction. The A and B sides are simultaneously subjected to the first corona treatment using a corona treatment machine. Then, the A side is placed on a heated metal plate and heated to reduce the average pore size of the A side, thus obtaining a single-layer filter material with a gradient average pore size. Example 19: A method for preparing a single-layer filter material, comprising the following steps: The fiber felt has opposing A and B sides in the thickness direction. Then, the A side is placed on a heated metal plate and the A side is heated to reduce the average pore size of the A side, thus obtaining a single-layer filter material with a gradient average pore size. Table 1. Experimental parameters for each embodiment and comparative example. Note: In the table above, the fiber felt is prepared using a conventional flash spinning method in the art. The raw material for preparing the fiber felt is polyethylene (PE). When preparing fiber felt using the flash spinning method, fiber felts with different average diameters can be obtained by adjusting the diameter of the spinning holes, and fiber felts with different average pore sizes can be obtained by adjusting the fiber stacking pattern and the number of stacked layers.

[0058] The method for measuring the average diameter of fibers on side A and / or side B in the fiber felt is as follows: observe with a scanning electron microscope, randomly select 100 fibers with good morphology to measure their diameter using mapping software, calculate the average value, and obtain the average diameter of the fibers.

[0059] The method for measuring the average pore size of the A-side and / or B-side in the fiber felt is as follows: a transverse cut is made at the midpoint along the thickness direction of the fiber felt to obtain two test samples containing the A-side and the B-side respectively. The test samples containing the A-side or the B-side are measured according to the standard method of GB / T 32361-2015, using ethanol impregnation and N2 displacement, to obtain the average pore size of the A-side or the B-side of the fiber felt.

[0060] The thickness of the fiber felt is measured using a Thwing Albert 89-100 thickness tester according to TAPPI standard T 411 om-2015.

[0061] Performance testing The single-layer filter materials prepared in the various embodiments and comparative examples of the present invention have opposing A' and B' surfaces in terms of thickness, wherein the A' surface is obtained by heat treatment of the A surface of the fiber felt; the single-layer filter materials of the various embodiments and comparative examples were subjected to the following performance tests: 1. Test of average fiber diameter of single-layer filter material In a single-layer filter material, the average diameter of fibers on the A' and B' sides is measured as follows: Observation is performed using a scanning electron microscope, 100 fibers with good morphology are randomly selected, and their diameters are measured using mapping software. The average value is calculated to obtain the average diameter of the fibers. 2. Average pore size test of single-layer filter material fibers The method for measuring the average pore size of the A' and B' surfaces in a single-layer filter material is as follows: a transverse cut is made at the midpoint along the thickness direction of the single-layer filter material to obtain two test samples containing the A' and B' surfaces respectively. The average pore size of the A' or B' surface of the single-layer filter material is obtained by measuring the test sample containing the A' or B' surface according to the standard method of GB / T 32361-2015, which is impregnated with ethanol and displaced by N2. When N(%) = (average pore size of B' surface - average pore size of A' surface) / average pore size of B' surface × 100%, the single-layer filter material is considered to have a gradient average pore size if N(%) = (average pore size of B' surface - average pore size of A' surface) / average pore size of B' surface × 100% ≥ 15%, the single-layer filter material is considered to have a gradient average pore size. 3. Thickness test of single-layer filter material In single-layer filter materials, the thickness is measured using a Thwing Albert 89-100 thickness tester according to TAPPI standard T 411 om-2015. Since the thickness of the fiber felt used to prepare the single-layer filter material in each embodiment and comparative example is 0.4 mm, when the thickness of the single-layer filter material is less than 15% of the thickness of the fiber felt, that is, when the thickness of the single-layer filter material is ≤0.1 mm, it is considered that the three-dimensional structure of the single-layer filter material has collapsed. 4. Dirt holding capacity test of single-layer filter material The method for measuring the dirt-holding capacity of a single-layer filter material is as follows: It is determined according to GB / T 18853-2015 standard, with a final pressure drop of 300 kPa; the test dust is prepared according to the mass ratio of ISO12103-1 A3 dust: 5μm particle size iron powder = 80:20; flow rate: 3 L / min; filter area: 100 cm². 2 ; 5. Bursting strength test of single-layer filter material Dry bursting strength is measured according to TAPPI standard T 403 om-22 (“Burning strength of paper”), unit: kPa; The experimental results are shown in the table below: Table 2 Performance test results of single-layer filter materials in each embodiment and comparative example Note: In the table above, comparative examples 1 and 3 no longer measure the average fiber diameter and average pore size parameters because their three-dimensional structures collapsed.

[0062] As can be seen from Table 2: By comparing Examples 1-3 and Comparative Examples 1-2, it can be seen that when the heat treatment time is constant, the average pore size of surface A' decreases continuously and N% increases continuously as the temperature rises; however, when the temperature is too high (e.g., 250°C), the fiber felt melts to a greater extent, the three-dimensional structure of the single-layer filter material collapses, and it does not have a gradient average pore size.

[0063] By comparing Examples 1, 4-6 and Comparative Example 3, it can be seen that when the heat treatment temperature is constant, the average pore size of surface A' decreases continuously and N% increases continuously with the increase of time; however, when the time is too long (e.g., 50s), the fiber felt melts to a greater extent, the three-dimensional structure of the single-layer filter material collapses, and it does not have a gradient average pore size.

[0064] By comparing Examples 1 and 7-12, it can be seen that when the fiber felt uses a specific fiber average diameter and average pore size and undergoes a specific heat treatment, the average pore size of the A side of the fiber felt can be reduced better, so as to better construct the gradient average pore size of the single-layer filter material.

[0065] Comparing Examples 1, 13-16, and 18-19, it can be seen that adjusting the voltage and time of the first and / or second corona treatment has virtually no impact on the three-dimensional structure and gradient average pore size of the single-layer filter material.

[0066] By comparing Examples 1 and 17, it can be seen that opening the B side of the fiber felt can increase the average pore size of the B side, thereby further increasing the gradient of the average pore size of the single-layer filter material.

[0067] Table 3 Performance test results of single-layer filter materials in each embodiment and comparative example As shown in Table 2-3, the preparation method of the present invention realizes the integrated preparation of a single-layer filter material with a gradient average pore size. The single-layer filter material has high dirt holding capacity and burst strength, wherein the dirt holding capacity is ≥300g and the burst strength is ≥650kPa.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a single-layer filter material, characterized in that, Includes the following steps: The fiber felt has opposing A and B surfaces in the thickness direction. The A surface is heated to reduce the average pore size of the A surface, thus obtaining a single-layer filter material. The heat treatment is performed at a temperature of 120-200℃ for a duration of 0.1-15 seconds.

2. The method for preparing the single-layer filter material as described in claim 1, characterized in that, Includes at least one of the following (1)-(5): (1) The temperature of the heat treatment is 130-200℃; (2) The heat treatment time is 0.5-15s; (3) The average fiber diameter of the fiber felt on side A and / or side B is 0.5-20 μm; (4) The average pore size of the fiber felt A side and / or B side is 1-40 μm; (5) The heating treatment method is to heat surface A with a metal plate.

3. The method for preparing the single-layer filter material as described in claim 1, characterized in that, Includes at least one of the following (1)-(2): (1) The average fiber diameter of the fiber felt on side A and / or side B is 0.8-5 μm; (2) The average pore size of the fiber felt A and / or B is 10-30 μm.

4. The method for preparing the single-layer filter material as described in claim 1, characterized in that, The thickness of the fiber felt is 0.1-10 mm.

5. The method for preparing the single-layer filter material as described in claim 1, characterized in that, Includes at least one of the following (1)-(3): (1) When heat treatment is performed on surface A, surface B of the fiber felt is opened to increase the average pore size of surface B. (2) Before the heat treatment of surface A, the first corona treatment is performed on both surface A and surface B of the fiber felt. (3) After the A-side is heated, the A-side and B-side of the fiber felt are subjected to a second corona treatment at the same time.

6. The method for preparing the single-layer filter material as described in claim 5, characterized in that, Includes at least one of the following (1)-(2): (1) The voltage of the first and / or second corona treatment is 5-25kV; (2) The time for the first and / or second corona treatment is 0.1-10s.

7. The method for preparing the single-layer filter material as described in claim 5, characterized in that, Includes at least one of the following (1)-(2): (1) The voltage of the first and / or second corona treatment is 15-25kV; (2) The time for the first and / or second corona treatment is 0.5-5s.

8. A single-layer filter material, characterized in that, Prepared by any one of the preparation methods described in claims 1-7, the single-layer filter material has opposing A' and B' surfaces in terms of thickness, wherein the A' surface is obtained by heat treatment of the A surface of the fiber felt.

9. The single-layer filter material as described in claim 8, characterized in that, Includes at least one of the following (1)-(5): (1) The average aperture of surface A' is smaller than that of surface B', and the average aperture gradually increases from surface A' to surface B'; (2) The average fiber diameter of the single-layer filter material on surface A' is 0.5-45 μm; (3) The average pore size of the single-layer filter material on surface A' is 0.1-39 μm; (4) The average fiber diameter of the single-layer filter material on the B' side is 0.1-20 μm; (5) The average pore size of the single-layer filter material on the B' side is 0.1-40 μm.

10. The application of the single-layer filter material according to any one of claims 8-9 in filtration and purification.

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