Antibacterial air filtering material as well as preparation method and application thereof

Abstract

The invention discloses an antibacterial air filtering material as well as a preparation method and application thereof. The preparation method comprises the following steps: opening and carding low-melting-point fibers and 2D fibers, and then conveying the fibers and the 2D fibers into a lapping machine to lay a fiber net; conveying the fiber net to a hot pressing roller for heating, pressing and shaping to obtain filter base cloth; the filtering base cloth is introduced into a melt-blown line spraying shaft; polypropylene particles and a silver ion antibacterial agent are mixed and then put into a heating bin for melt-blowing, melt-blown polypropylene fibers adhere to the outer surface of the filter base cloth, and a PP melt-blown layer is formed; the air filter cloth is obtained; spraying an antibacterial viscose solution on the PP melt-blown layer of the air filter cloth at high pressure; the air filter cloth is conveyed to drying equipment to be dried and shaped, and edge cutting and rolling are conducted. The air filtering material has a double-layer structure with a fluffy upper layer and a dense lower layer, and has antibacterial and antiviral functions, and the filter cloth can still keep high-efficiency filtering and antibacterial effects after being washed repeatedly.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application No. 18919863, filed October 18, 2024, entitled "Preparation Method for Antimicrobial Air Filtration Material", the entire contents of which, including amendments herein, are incorporated herein by reference. Technical Field

[0003] This invention belongs to the field of air filtration material technology, specifically relating to an antibacterial air filtration material, its preparation method, and its application. Background Technology

[0004] With the progress of the times and rapid economic development, environmental pollution has intensified. Dust, chemicals, and harmful microorganisms in the air have adversely affected people's health. However, people have increasingly higher demands for environmental quality, especially for densely populated areas where air purification is required. To achieve a high level of environmental cleanliness, filtration is currently a commonly used method. Air filter materials can effectively intercept particulate matter, bacteria, viruses, and other microorganisms in the air.

[0005] Air filter materials are widely used in air conditioning and ventilation systems, air purifiers, and automotive air conditioning filters. Currently, air filter materials primarily remove particulate matter and gaseous pollutants from the air. Meltblown fiber air filters trap particulate matter or aerosol pollutants, while activated carbon or other materials adsorb other airborne pollutants. However, after a period of time, a large amount of dust accumulates on the surface and inside the filter screen, easily leading to the growth of bacteria, viruses, mold, and other microorganisms. If not treated promptly, this can cause serious secondary pollution.

[0006] Many researchers are trying to develop more efficient air filtration materials.

[0007] Patent document CN114130123A discloses an antibacterial and antifungal air purification material, comprising a filter layer, a transition layer, and a functional layer. The filter layer is composed of a mixture of supporting fibers, strength fibers, and ultrafine fibers. The supporting fibers are polyester fibers, with a content of 10-20%, containing 10-20% organic antibacterial agent. The strength fibers are ABS plastic fibers, with a diameter of 0.5-1 mm and a content of 30-40%, containing 5-10% molecular sieve, 3-10% zinc oxide, and 4-12% copper oxide. The ultrafine fibers are polypropylene fibers, with a diameter of 0.1-2 μm and a content of 40-60%. The functional layer is a honeycomb mesh, filled with functional particles. The functional particles are composed of alumina molecular sieves loaded with manganese oxide and zinc oxide, with a manganese oxide content of 1-3% and a zinc oxide content of 2-5%. However, the preparation process of this document involves the mixing and lamination of multiple materials, resulting in high process complexity. The compatibility between different materials may affect the overall performance, and the long-term effects and durability need to be verified.

[0008] Patent document CN113430662A discloses an antibacterial, antifungal, and antiviral meltblown filter material and its preparation method, including the following steps: S1. Preparing a meltblown polypropylene masterbatch containing copper, silver, and zinc ion antibacterial agents; S2. During the meltblown spinning process of the polypropylene masterbatch, mixing stearic acid and zinc oxide particles, under the action of meltblown jets, spraying them onto the fiber surface of the resulting meltblown polypropylene nonwoven fabric to obtain the meltblown polypropylene nonwoven fabric; the molar ratio of zinc oxide to stearic acid is (0.2~1):1; S3. Performing a water electret treatment on the meltblown polypropylene nonwoven fabric to obtain the antibacterial, antifungal, and antiviral meltblown filter material. However, the zinc oxide particles in this document do not adhere firmly to the surface of the nonwoven fabric and are easily detached after high-pressure water washing, resulting in a significant decline in antibacterial performance and a short service life; moreover, the water electret treatment used is very expensive, resulting in a high cost of the filter material. Summary of the Invention

[0009] The purpose of this invention is to provide a method for preparing antibacterial air filter materials to solve the technical problems of existing technologies, such as limited material properties, performance degradation after cleaning, and short service life.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing an antibacterial air filter material, comprising the following steps:

[0012] S1, low melting point fibers are fed into the first cotton blending opener for opening, 2D fibers are added into the second cotton blending opener for opening, and then they are respectively conveyed to the pneumatic cotton blending box for uniform mixing to obtain mixed fiber raw materials; then the mixed fibers are conveyed to the carding machine for carding.

[0013] S2, the combed mixed fiber web is conveyed to the reciprocating web laying machine to lay out a certain number of fiber web layers; the fiber web has 4 to 6 folded layers and a basis weight of 0.03 to 0.06 kg / m²;

[0014] S3, the fiber web is conveyed to a hot press molding machine for heating, pressing and shaping into a filter base fabric, the axial surface temperature of the hot press molding machine is 200-300℃;

[0015] S4, the filter base cloth is introduced onto the spraying shaft of the meltblown line, entering in an inverted C-shaped structure;

[0016] S5. Polypropylene granules and silver ion antibacterial agent are mixed at a mass ratio of 100:(1-5) and then added to a heating chamber. The mixture is heated to 180-230°C and melt-blown. The melted polypropylene granules are in a liquid state, and the silver ion antibacterial agent is incorporated into the polypropylene material. The melt-blown polypropylene fibers containing the silver ion antibacterial agent adhere to the outer surface of the filter base cloth, forming a PP melt-blown layer with antibacterial capabilities. After stretching, web forming, reinforcement or self-adhesion, an air filter cloth with a double-layer structure of a fluffy upper layer and a dense lower layer is obtained.

[0017] S6, an antibacterial adhesive solution is sprayed onto the PP meltblown layer of the air filter cloth under high pressure, wherein the spraying amount of the antibacterial adhesive solution is 1% to 2% of the basis weight of the air filter cloth;

[0018] S7, the air filter cloth is conveyed to the drying equipment for drying and shaping, and the edges are trimmed and rolled up to obtain the antibacterial air filter material.

[0019] Preferably, the low-melting-point fiber is polyethylene terephthalate (PET, polyester) with a melting point of 110-150°C, such as LMF fiber produced by Sichuan Huiweishi Chemical Fiber Co., Ltd.; low-melting-point polyester fiber has a lower melting shrinkage temperature than general low-melting-point fibers, and can melt and bond with other fibers at a lower temperature.

[0020] The 2D fiber is a synthetic fiber made from polyester materials through a specific process, with a melting point of 240-260°C. For example, the 2De*64mm fiber produced by Sichuan Huiweishi Chemical Fiber Co., Ltd. or Jiangsu Yizheng Chemical Fiber Co., Ltd.

[0021] The original fiber length of the low melting point fiber and 2D fiber is 65±5mm, and the fiber length is 10~30mm after being heated and shaped by a hot pressing and shaping machine.

[0022] Preferably, the PP meltblown layer has a fiber length of 5-15 mm, a diameter of 0.5-10 μm, and a basis weight of 0.02-0.06 kg / m².

[0023] Preferably, the antibacterial adhesive solution is prepared by uniformly mixing an inorganic silver ion antibacterial agent (e.g., LD904 from Nanjing Tianshilandun Biotechnology Co., Ltd.), water, and carboxylated styrene-butadiene latex in a mass ratio of (1.0-2.5):(6-10):1, with a preferred mass ratio of 1:8:1.

[0024] Preferably, the drying and shaping temperature is 100-150°C.

[0025] Secondly, the present invention proposes an antibacterial air filter material prepared using the preparation method of the antibacterial air filter material described in the present invention.

[0026] Thirdly, this invention proposes the application of the antibacterial air filter material provided by this invention, especially in air filtration equipment such as air conditioning ventilation and purification systems, air purifiers, and vehicle air conditioning filters.

[0027] Compared with existing technologies, the present invention has the following advantages:

[0028] The antibacterial air filter material of this invention is a double-layer fiber web formed by the cross-lamination of ultra-fine fibers. One layer is a rigid support structure layer, which provides excellent support for the filter material itself, reduces filter cloth resistance, and improves filtration efficiency. The other layer is a melt-blown filter layer with antibacterial agent. The PP melt-blown filter layer has many pores, a loose structure, small fiber diameter, and a large specific surface area. It has a unique capillary structure, which can increase the number of fibers and surface area per unit area, effectively preventing the invasion of harmful particles, while maintaining high air permeability and oil absorption, and making it easier to integrate antibacterial components. At the same time, the air filter material of this invention has antibacterial and antiviral functions, as well as excellent durability and washability. The filter cloth can withstand repeated washing and still maintain a high efficiency of filtration and antibacterial effect. Even after 12 washes, it can still maintain a 90.1% antibacterial rate and the filtration efficiency only decreases by 6%. Attached Figure Description

[0029] Figure 1 Microscopic image of long fibers formed after heat setting of fiber web.

[0030] Figure 2 Microscopic image of short fibers in PP meltblown layer.

[0031] Figure 3 Microscopic image of an air filter cloth with a double-layer structure of a fluffy upper layer and a dense lower layer. Detailed Implementation

[0032] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Those skilled in the art should recognize that these embodiments are merely illustrative of the present invention and are not intended to limit the invention. Any modifications or variations to the embodiments within the scope of the present invention are within the scope of the claims of the present invention.

[0033] The raw materials used in Examples 1-4 and Comparative Examples 1-2 below are all commercially available products:

[0034] Low melting point fiber: LMF 4de*64mm fiber produced by Sichuan Huiweishi Chemical Fiber Co., Ltd.

[0035] 2D fiber: 2De*64mm fiber produced by Sichuan Huiweishi Chemical Fiber Co., Ltd. or Jiangsu Yizheng Chemical Fiber Co., Ltd.

[0036] Inorganic silver ion antibacterial agent: Nanjing Tianshilandun Biotechnology Co., Ltd. LD904;

[0037] Carboxylated styrene-butadiene latex: Carboxylated styrene-butadiene latex produced by Mingzhou Chemical Co., Ltd., grade MZ-01852.

[0038] Example 1

[0039] A method for preparing an antibacterial air filter material includes the following steps:

[0040] S1, the low melting point fiber is fed into the first cotton blending opener for opening, and then conveyed to the pneumatic blending box for uniform mixing; then the mixed fiber is conveyed to the carding machine for carding; the original length of the low melting point fiber is 65mm;

[0041] S2, the carded low melting point fiber web is conveyed to the reciprocating web laying machine to lay out a certain number of layers of fiber web; the fiber web is folded into 6 layers and has a basis weight of 0.06 kg / m²;

[0042] S3, the fiber web is conveyed to a hot press setting machine for heating, pressing, and setting into a filter base fabric with interwoven and bonded fiber filaments. The axial surface temperature of the hot press setting machine is 280℃. After heating and setting in the hot press setting machine, the fiber length is 10-30mm (as shown in the attached image). Figure 1 );

[0043] S4, the filter base cloth is introduced into the spraying shaft of the meltblown line in an inverted C-shaped structure;

[0044] S5, polypropylene granules and silver ion antibacterial agent are mixed at a mass ratio of 100:5 and then added to a heating chamber. The mixture is heated to 225°C for melt-blowing. The melted polypropylene granules are in a liquid state, incorporating the silver ion antibacterial agent into the polypropylene material. This causes the melt-blown polypropylene fibers containing the silver ion antibacterial agent to adhere to the outer surface of the filter base fabric, forming a short-fiber molten structure PP melt-blown layer with antibacterial capabilities (as shown in the attached image). Figure 2 The polypropylene fiber diameter is 0.5–10 μm, the fiber length is 5–15 mm, and the basis weight of the PP meltblown layer is 0.04 kg / m². After stretching, web formation, and self-adhesion, an air filter cloth with a double-layer structure of a fluffy upper layer and a dense lower layer is obtained (see attached). Figure 3 );

[0045] S6, apply antibacterial adhesive solution to the PP meltblown layer of the air filter cloth under high pressure; the amount of antibacterial adhesive solution applied is 2% of the weight of the air filter cloth; the antibacterial adhesive solution is made by uniformly mixing inorganic silver ion antibacterial agent, water and carboxylated styrene-butadiene latex in a mass ratio of 1:8:1.

[0046] S7. The air filter cloth is conveyed to the drying equipment and dried and shaped at 100-150℃. After trimming and rolling, the antibacterial air filter material can be obtained.

[0047] Example 2 has the same production process as Example 1, except that in step S5 of Example 2, the mass ratio of polypropylene particles to silver ion antibacterial agent is 100:3.

[0048] Example 3 has the same production process as Example 1, except that in step S5 of Example 3, the mass ratio of polypropylene particles to silver ion antibacterial agent is 100:1.

[0049] Example 4

[0050] A method for preparing an antibacterial air filter material includes the following steps:

[0051] S1, low melting point fibers are fed into the first cotton blending opener for opening, 2D fibers are added into the second cotton blending opener for opening, and then conveyed to the pneumatic blending box for uniform mixing to obtain blended fibers; then the blended fibers are conveyed to the carding machine for carding; the filament length of low melting point fibers and 2D fibers is 65mm;

[0052] S2, the combed mixed fibers are conveyed to the web laying machine to lay out the fiber web; the fiber web has 4 folds and a basis weight of 0.04 kg / m²;

[0053] S3, the fiber web is conveyed to the hot press setting machine for heating, pressing and setting into filter base fabric. The axial surface temperature of the hot press setting machine is 220℃. After being heated and set by the hot press setting machine, the fiber length is 18-30mm.

[0054] S4, the filter base cloth is introduced into the spraying shaft of the meltblown line in an inverted C-shaped structure;

[0055] S5. Polypropylene granules and silver ion antibacterial agent are mixed at a mass ratio of 100:4 and then added to a heating chamber. After being heated to 185°C, the mixture is melt-blown. The melted polypropylene granules are in a liquid state, and the silver ion antibacterial agent is incorporated into the polypropylene material. The melt-blown polypropylene fibers containing the silver ion antibacterial agent adhere to the outer surface of the filter base cloth, forming a PP melt-blown layer with a short fiber filament melt structure and antibacterial ability. The diameter of the polypropylene fibers is 0.5-10 μm, the fiber length is 5-15 mm, and the basis weight of the PP melt-blown layer is 0.05 kg / m². After stretching, web forming, and self-adhesion, an air filter cloth with a double-layer structure of a fluffy upper layer and a dense lower layer is obtained.

[0056] S6, apply antibacterial adhesive solution to the PP meltblown layer of the air filter cloth under high pressure; the amount of antibacterial adhesive solution applied is 1.5% of the weight of the air filter cloth; the antibacterial adhesive solution is made by uniformly mixing inorganic silver ion antibacterial agent, water and carboxylated styrene-butadiene latex in a mass ratio of 2:10:1.

[0057] S7. The air filter cloth is conveyed to the drying equipment and dried and shaped at 100-150℃. After trimming and rolling, the antibacterial air filter material can be obtained.

[0058] The production process of Example 5 is the same as that of Example 2. The difference is that in step S6 of Example 5, the spraying amount of antibacterial adhesive solution is 1% of the weight of the air filter cloth; the antibacterial adhesive solution is made by uniformly mixing inorganic silver ion antibacterial agent, water and carboxylated styrene-butadiene latex in a mass ratio of 2:7:1.

[0059] Comparative Example 1 is a comparative example of Example 4. The difference is that in step S1 of Comparative Example 1, all low melting point fibers are used, and in step S3, the roller surface temperature of the hot press setting machine is 155°C. After being heated and set by the hot press setting machine, the fiber length is 35-50 mm.

[0060] Comparative Example 2 is Example 4 of Patent Document CN113430662A.

[0061] The aforementioned hot pressing and shaping equipment can use hot pressing rollers or hot rolling rollers as the core heating and shaping components. It should be specifically noted that the cotton blending process in step S1 is not limited to a pneumatic cotton blending box structure; similarly, the web laying process in step S2 is not limited to a reciprocating web laying machine structure. Any equivalent equipment with corresponding cotton blending and web laying functions is an optional implementation of the technical solution of this invention and should be included within the patent protection scope of this invention.

[0062] Test Experiment Example

[0063] The antibacterial air filter materials obtained in Examples 1-5 and Comparative Examples 1-2 were tested. PM2.5 filtration efficiency (%) and resistance were tested according to GB / T6165-2005 "Performance Test Methods for High-Efficiency Air Filters - Efficiency and Resistance". The PM2.5 filtration efficiency test wind speed was 2.2 m / s, and the PM2.5 dust source was sodium chloride aerosol. The antibacterial rate was tested according to GB / T20944.3-2008 "Evaluation of Antibacterial Properties of Textiles - Part 3: Vibration Method", using Escherichia coli (ATCC25922) as the test bacteria. The filters were cleaned using an 8 kg pressurized water source from the metal mesh side for at least 3 minutes, followed by drying in a forced-air drying oven at 40°C.

[0064] Table 1. Test results of Examples 1-4 and Comparative Documents 1-2

[0065]

[0066]

[0067] As shown in Table 1, the antibacterial air filter material of this invention is produced in a single process with a double-layer structure. It utilizes a composite processing of low-melting-point fiber and 2D fiber to form a dense and sturdy filter interception layer. Combined with a melt-blown layer of polypropylene fiber sprayed on the surface, it forms a filter structure that is tight on one side and loose on the other. This structure facilitates the subsequent processing and molding of the air filter element, and the polyester fiber layer will not experience filter fiber shedding or breakage. In addition to having excellent filtration effect and significant antibacterial effect on fine particulate matter (such as PM2.5) in the air, it also has excellent durability and washability. It can withstand repeated washing while maintaining a high efficiency of filtration and antibacterial effect. Even after 12 washes, it can still maintain a 90.1% antibacterial rate and the filtration efficiency only decreases by 6%.

[0068] In Comparative Example 1, because only low-melting-point fibers were used, the rigid support structure layer was not strong enough to withstand the scouring of water during multiple washes. It was easy for the fibers to collapse and block the pores, resulting in a sharp increase in resistance and ultimately a significant decrease in PM2.5 filtration efficiency.

[0069] The polypropylene meltblown process in reference document 2 (i.e., patent document CN113430662A) is a basic processing technology in this industry. However, the zinc oxide particles in the process do not adhere firmly to the surface of the nonwoven fabric and are easy to fall off after high-pressure water washing, resulting in a significant decline in antibacterial performance and a short service life.

Claims

1. A method for preparing an antibacterial air filter material, characterized in that, Includes the following steps: S1, low melting point fibers are fed into the first cotton blending opener for opening, 2D fibers are added into the second cotton blending opener for opening, and then conveyed to the pneumatic cotton blending box for uniform mixing to obtain mixed fibers; then the mixed fibers are conveyed to the carding machine for carding. S2, the mixed fiber layer after being combed into a web is conveyed to a reciprocating web laying machine to lay out the fiber web; the fiber web has 4 to 6 folded layers and a basis weight of 0.03 to 0.06 kg / m²; S3, the fiber web is conveyed to a hot press molding machine for heating, pressing and shaping into a filter base fabric, the axial surface temperature of the hot press molding machine is 200-300℃; S4, the filter base cloth is introduced onto the spraying shaft of the meltblown line, entering in an inverted C-shaped structure; S5. Polypropylene granules and silver ion antibacterial agent are mixed at a mass ratio of 100:(1-5) and then added to a heating chamber. The mixture is heated to 180-230°C and melt-blown. The melted polypropylene granules are in a liquid state, and the silver ion antibacterial agent is incorporated into the polypropylene material. The melt-blown polypropylene fibers containing the silver ion antibacterial agent adhere to the outer surface of the filter base cloth, forming a PP melt-blown layer with antibacterial capabilities. After stretching, web forming, reinforcement or self-adhesion, an air filter cloth with a double-layer structure of a fluffy upper layer and a dense lower layer is obtained. S6, an antibacterial adhesive solution is sprayed onto the PP meltblown layer of the air filter cloth under high pressure, wherein the spraying amount of the antibacterial adhesive solution is 1% to 2% of the basis weight of the air filter cloth; S7, the air filter cloth is conveyed to the drying equipment for drying and shaping, and the edges are trimmed and rolled up to obtain the antibacterial air filter material.

2. The method for preparing the antibacterial air filter material according to claim 1, characterized in that, The low-melting-point fiber is polyethylene terephthalate with a melting point of 110-150°C; the 2D fiber is a synthetic fiber made from polyester materials through a specific process, with a melting point of 240-260°C.

3. The method for preparing the antibacterial air filter material according to claim 1, characterized in that, The original fiber length of the low melting point fiber and 2D fiber is 65±5mm, and the fiber length is 10~30mm after being heated and shaped by a hot pressing and shaping machine.

4. The method for preparing the antibacterial air filter material according to claim 1, characterized in that, The PP meltblown layer has a fiber length of 5-15 mm, a diameter of 0.5-10 μm, and a basis weight of 0.02-0.06 kg / m².

5. The method for preparing the antibacterial air filter material according to claim 1, characterized in that, The antibacterial adhesive solution is prepared by uniformly mixing inorganic silver ion antibacterial agent, water and carboxylated styrene-butadiene latex in a mass ratio of (1.0-2.5):(6-10):

1.

6. The method for preparing the antibacterial air filter material according to claim 5, characterized in that, The antibacterial adhesive solution is prepared by uniformly mixing inorganic silver ion antibacterial agent, water and carboxylated styrene-butadiene latex in a mass ratio of 1:8:

1.

7. The method for preparing the antibacterial air filter material according to claim 1, characterized in that, The drying and shaping temperature is 100-150℃.

8. An antibacterial air filter material obtained by the preparation method according to any one of claims 1 to 7.

9. An application of the antibacterial air filter material according to claim 8, characterized in that, Used in air filtration equipment such as air conditioning ventilation and purification systems, air purifiers, and vehicle air conditioning filters.

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