Double-layered wool bio-composite air filtration material and method of producing the same

Abstract

The objective of this invention is to provide a double-layer wool biocomposite air filter material and its production method, which is completely biodegradable and can be processed and enriched from animal hair. The double-layer wool biocomposite air filter material consists of the following: (a) a micro-cotton blend layer containing PPK microfibers produced from biocomposite particles of washed and combed coarse wool, with a maximum diameter of 22±10 micrometers, spun together with washed and combed wool; and (b) a PPK nanofiber layer with a diameter of 0.2-1 micrometer, produced from biocomposite particles of washed and combed coarse wool.

Description

Technical Field

[0001] This invention relates to light industry, and more particularly to a double-layer wool biocomposite air filter material for air purification and filtration, and its production method. Background Technology

[0002] It is estimated that indoor air pollution is 2 to 5 times higher than outdoor air pollution [Non-Patent Literature 1]. Currently, the world's most commonly used High Efficiency Particulate Air (HEPA) filters are discarded and landfilled annually, amounting to 6,000 tons per year [Non-Patent Literature 2].

[0003] Therefore, polyethylene (PET) and polypropylene (PP), as the main raw materials for synthesizing HEPA filters, are sources of microplastics that pollute soil and water [Non-Patent Literature 3, 4]. In particular, HEPA and other air filter materials containing synthetic fibers are difficult to recycle once contaminated, and produce more toxic volatile compounds when burned [Non-Patent Literature 5].

[0004] Therefore, given its impact on the environment and human health, it is crucial to find organic sources for filtering small particles from the air.

[0005] The most commonly used air filtration material in Mongolia and around the world is made of polyethylene and polypropylene, which filters air pollutants in the following ways ( Figure 5 [Non-patent literature 6] like Figure 5 As shown, the microfiber air filter 50 consists of multiple layers of fibers 51, typically in the range of tens of micrometers in diameter. The airflow entering the filter 50 is illustrated by the right-pointing arrow 52.

[0006] Nanofiber air filter material is a commonly used filter material made of fibers with a diameter of less than 1 micrometer and an average diameter of 500 nanometers [Non-Patent Literature 7].

[0007] like Figure 5 As shown, when air pollution particles 54 to 57 enter through these microfilaments 51, they are filtered by colliding with the microfilaments and slowly reducing their speed (particle 54), being trapped between the microfilaments 51 (particle 55), being attracted to the microfilaments 51a by electrostatic attraction (particle 57), and diffusing between the microfilaments 51 (particle 56).

[0008] Compared to such synthetic materials, there are filters that use organic materials. For example, filtration schemes using animal hair have been widely used. Such wool filters are placed in the exhaust path of all types of chimneys and are used to filter harmful compounds in the smoke emitted from the chimney. This is a filter constructed by placing two layers of wool and / or felt filters, each 5 to 30 mm thick, in a cylindrical body prepared according to the dimensions of the chimney used for exhaust. Sheep wool filters for smoke filtration are known [Patent Document 1].

[0009] An air wool filter is also known that can effectively filter fine particles based on the diameter and density of the fibers by means of weaving or non-weaving methods of sheep wool [Patent Document 2].

[0010] Also known are sheep wool filters from the brand LANACO (trademark) (New Zealand). The main application of this filter is in the filtration of face masks [Non-Patent Literature 8]. Australian Merino wool is the finest and most widely used sheep wool in the world, with an average diameter of ultrafine fibers of 12.5 to 17.5 micrometers [Non-Patent Literature 9].

[0011] The extent to which the aforementioned wool filters used for smoke filtration can filter both sizes of airborne particles is unknown, and there is no information regarding the relative effectiveness of the wool fibers used against contaminants. The efficiency of air wool filters is determined by comparing the properties of the filter substrate material with its structure and content, but there is currently no information on how to make it useful in woven and non-woven ways.

[0012] LANACO brand sheep wool filters are enriched with non-biodegradable polymers, so they will not be fully biodegradable when disposed of as waste in landfills [Non-Patent Literature 10].

[0013] One of the indicators used to measure air quality (especially pollution) is the amount of particles present in or suspended in the air. Here, PM (particulate matter) 10 is measured, which consists of particles with a diameter of 10 micrometers, and PM2.5, which consists of particles with a diameter of 2.5 micrometers. Fine particles polluting indoor air in buildings are typically PM 10 or smaller.

[0014] Commercial air filters (filters) typically use synthetic fibers with uniform diameter and are capable of filtering fine particles up to PM2.5. However, because these filters are made of a single layer of material used for air filtration, all particles in the air, from PM2.5 to PM10 and larger, are collected on the filter surface. This results in a reduction in the total surface area of ​​the filter material, lowering the efficiency rating.

[0015] The mechanisms for absorbing airborne particles are classified into depth filtration and surface (membrane) filtration based on filtration requirements. Figure 6 [Non-patent literature 11]. For example... Figure 6 As schematically illustrated in (a), depth filtration is a method of trapping particles 62 in an airflow within a filter 60 composed of fibrous fibers 61. Figure 6 As schematically illustrated in (b), membrane filtration 63 is a method of capturing airborne particles 62 on the surface or outer surface of a filter and preventing further passage.

[0016] There are two main technologies for producing high-performance air filter materials designed to filter fine particles smaller than PM 0.3: structure-based and interaction-based [Non-Patent Literature 12].

[0017] Interaction-based approach

[0018] Interaction-based methods are often used as additives in synthetic polymers. When the fibers that make up the filter are electrically filled, they attract charged particles in the air and operate based on the principle that charged particles are attracted to the filter body through electrical interactions.

[0019] Structure-based approach 1

[0020] Structure-based filters can be created by blending fibers with different structures and using multiple layers of fibers with different structures. This is a technique that can be used not only for wool, but also for any organic animal hair or fiber as the main structure and to enrich other fibers.

[0021] Structure-based approach 2

[0022] Another structural approach is based on layering a filter material enriched with biocomposite microfibers with a diameter of 1 ± 0.3 micrometers with a single layer of finer biocomposite nanofibers (called PPK nanofibers) with a diameter of 0.2-1 micrometers and a thickness of 0.2-5 mm.

[0023] References

[0024] Patent References

[0025] Patent Reference 1: 20-2016-0003373 20-0002604 2016.10.20 "A Wool Filter for Smoke"

[0026] Patent Reference 2: 20-2021-0004559 20-0003409 2021.12.01 "A Wool Filter for Smoke Detection"

[0027] Non-patent literature

[0028] Non-patent literature source 1: Environmental Returns (ROE) report from the U.S. Environmental Protection Agency

[0029] Environmental Protection Agency (EPA): https: / / www.epa.gov / reportenvironment / indoor-air-quality

[0030] Non-Patent Document 2: BriivAir Air Purifier (the world's most sustainable air filter made from natural materials) https: / / www.fivecreate.co.uk / project-l

[0031] Non-patent literature reference 3: Guo Jingjie et al., “Sources, migration and toxicology of microplastics in soil”, International Environment, Vol. 137, April 2020, pp. 105263.

[0032] Non-patent literature 4: Merlin N. Isaac and Balasubramania Kandasubramania, “The impact of microplastics on water and aquatic systems”, Environmental Science and Pollution Research, Vol. 28, pp. 19544-19562 (2021).

[0033] Non-patent literature 5: Paul M. Lemieux et al., “Emissions of organic air toxins in open combustion: a comprehensive review”, Advances in Energy and Combustion Science, Vol. 30 (2004), pp. 1-32.

[0034] Non-patent literature 6: S. Han, J. Kim, SH. Guo, “Advances in air filtration technology: structure-based and interaction-based approaches”, Progress in Materials Today, Vol. 9, 2021, 100134, ISSN 2590-0498.

[0035] Non-patent literature 7: Wang, C., Wu, S., Jiang, M. et al., “Silk nanofibers as efficient and lightweight air filters”, Nano Res., Vol. 9, pp. 2590-2597 (2016).

[0036] Non-patent literature resource 8: https: / / lanaco.co.nz / filters /

[0037] Non-patent literature source 9: https: / / merinos.com.au / australian-merino /

[0038] Non-patent literature reference 10: https: / / shop.lanaco.co.nz / pages / faq

[0039] Non-patent literature 11: Process hygiene | Risks and control of air pollution, GJ Curiel and HLM Leliveld, included in Encyclopedia of Food Microbiology (Second Edition), 2014.

[0040] Non-patent literature 12: S. Han, J. Kim, SH. Guo, “Advances in air filtration technology: structure-based and interaction-based approaches”, Progress in Materials Today, Vol. 9, 2021, 100134, ISSN 2590-0498.

[0041] Non-patent literature 13: Bian Ye, Wang Shijie, Zhang Li, Chen Chun, “Influence of fiber diameter, filter thickness and packing density on PM2.5 removal efficiency of electrospun nanofiber air filters for indoor applications”, Building and Environment, Vol. 170, 2020, 106628, ISSN 0360-1323.

[0042] Non-patent literature 14: Bengi, S., Visaka, K., Das, S. et al., “Oxidative stress, DNA and film targets as modes of antimicrobial and antibiofilm activity of easily synthesized biocompatible keratin-copper nanoparticles against multidrug-resistant urinary tract pathogens”, World Journal of Microbial Biotechnology 38, 20 (2022).

[0043] Non-patent literature 15: Schiff Shankar and Lin Zhonghuan, “Environmentally friendly antibacterial nanoparticles of keratin-metal ion complex”, Materials Science and Engineering: C, Vol. 105, 2019, 110068, ISSN 0928-4931.

[0044] Non-patent literature 16: Dan Mogosanu, George, Mihai Grumezescu, Alexandru, Carmen Chiferuk, Marianna, “Keratin-based biomaterials for biomedical applications”, Current Drug Targets, Vol. 15, No. 5, 2014, pp. 518-530 (13 pages in total).

[0045] Non-patent literature 17: Richard S. Karan, Aaron Ghosh, and Joron M. Dale, “Surface properties of wool fabrics modified with Linde A-type nanozeolite”, Journal of Applied Polymer Science, Vol. 132, No. 32, 2015.

[0046] Non-patent literature 18: Shavandi A, Ali MA, “Keratin-based thermoplastic biocomposites: a review”, Environmental Science & Biotechnology Review, June 1, 2019; 18: 299-316. Summary of the Invention

[0047] Solution to the problem

[0048] The objective of this invention is to provide a method for developing a double-layer wool biocomposite air filter material and a method for producing it, which is fully biodegradable and can be processed and enriched from animal hair.

[0049] Another objective of the present invention is to provide a method for processing coarse wool fibers to manufacture a double-layer wool biocomposite air filter material and a method thereof.

[0050] Another objective of the present invention is to provide a method for developing a double-layer wool biocomposite air filter material and a method for producing the same, which uses coarse wool to process it, providing a biocomposite fiber mixed with a biopolymer compound, and supplemented with fine wool.

[0051] Advantages of the invention

[0052] This invention provides and enriches wool to produce 100% biodegradable biocomposite air filter material.

[0053] This invention addresses the shortcomings of known solutions, namely that they are non-biodegradable and a source of soil pollution.

[0054] This invention utilizes the positively charged electromagnetic properties of the cuticle membrane of wool fibers, which can trap and filter some negatively charged volatile organic compounds in the air, to manufacture a bio-composite air filter material that filters small particles in the air.

[0055] This invention is an environmentally friendly solution that does not pollute the environment.

[0056] This invention relates to a double-layer bio-composite air filter material and its production method.

[0057] The double-layer wool bio-composite air filter material of the present invention is composed of the following: The first layer is produced from microfibers processed from biocomposite particles of washed and combed coarse wool with a diameter of up to 22 ± 10 micrometers, and The second layer consists of nanofibers with a diameter of 0.2-1 micrometer, which are processed from biocomposite particles made from washed and combed coarse wool.

[0058] The production method of the double-layer wool biocomposite air filter material of the present invention includes: The dehydration step involves preparing the washed and combed coarse wool to a size of less than 3 mm, washing it in an aqueous solution of 0.1% surfactant, and rinsing it with distilled water. The mixture production step involves cleaning the mixing device with a 30% sodium hydroxide solution, mixing the dehydrated wool, and adding sodium percarbonate to form a mixture. The keratin extraction step involves using a dehydration device to extract keratin as a solid phase from the wool of the mixture obtained using a mixing device. The drying mixture preparation step involves mixing the extracted keratin with a polylactic acid / PBAT (80:20) polymer mixture at a ratio of 90:10; The 10% solution preparation step involves dissolving the dried mixture in a solvent of ethyl acetate (EA) / dimethylformamide (N,N-DMF) in a 7:3 ratio; In the biocomposite material extraction step, the solution was heated at 75°C for 24 hours; The biocomposite particle extraction step involves using a twin-screw extruder at a speed of 200 rpm and a temperature of 175°C to extract the biocomposite particles and uniformly harden the extracted biocomposite material. The microfiber and nanofiber extraction step extracts microfibers and nanofibers from the biocomposite particles; and The production steps of the double-layer wool air filter material include ironing the microfibers and nanofibers at different temperatures according to the thickness of the material.

[0059] Preferably, the aqueous solution of the surfactant is 0.1% TWEEN 80.

[0060] Preferably, the main raw material is washed and combed coarse wool that meets the requirements of MNS 6398:2020 standard.

[0061] Preferably, the washed and dehydrated wool is mixed with a 30% sodium hydroxide solution at 3% of its dry weight in a mixing machine, and then 4.5% of the dry weight of wool is added and mixed for 4 hours.

[0062] The biocomposite particles are polylactic acid / PBAT / keratin particles made of sheep wool biocomposite materials, with PPK microfibers and PPK nanofibers.

[0063] The present invention comprises the steps of producing microfibers with a diameter of 1 to 5 micrometers by spinning the biocomposite particles at a speed of 4500 rpm and a temperature of 175°C using a temperature-controlled rotary spinning machine; and the steps of producing a pre-filter by combining the microfibers with fine Mongolian wool or washed and combed wool with a diameter of up to 22 ± 10 micrometers using an opening device.

[0064] The present invention comprises the steps of dissolving the biocomposite particles in a solvent and spinning them using a high-voltage electrospinning apparatus that introduces the solution to produce nanofibers with a diameter of 0.2 to 1 micrometer.

[0065] This invention is based on the principle of air wool filtration in patent reference 2, namely the phenomenon of classifying particles according to size from largest to smallest, and the depth filtration mechanism for capturing particles based on surface or thin-film filtration mechanisms. It utilizes three structural and interaction methods to filter a large number of finer particles. It is a method for producing biodegradable double-layer wool biocomposite air filter materials.

[0066] In this invention, fine (12 to 22 micrometers) sheep wool is combined with coarse (>160 micrometers) sheep wool, enriched with biocomposite fibers mixed with biopolymer compounds, and then a layer of biocomposite fibers with a finer diameter is superimposed on top to produce a 100% biodegradable air filter biocomposite material.

[0067] The majority (approximately 80%) of Mongolian wool's composition is keratin, with the remainder consisting of non-protein compounds, fats, and mineral salts. Of the protein compounds that make up the keratin in Mongolian wool, about 40% are hydrophobic and about 60% are hydrophilic, enabling it to filter many polar and non-polar aromatic organic compounds from the air, such as volatile organic compounds like benzene, toluene, and xylene. However, structurally, Mongolian wool is unsuitable for other uses because it contains a large number of coarse fibers exceeding 160 micrometers, making it suitable for physicochemical decomposition and filtering fine solid particles within its pores.

[0068] The technology uses natural absorbent sheep wool, which is processed and enriched with biodegradable polymer compounds such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) to refine the internal pore structure, thereby creating a biodegradable filter material that can compete with existing high-efficiency particulate air (HEPA) filters on the market.

[0069] The solution is a wool air filter using two layers of materials with different filtration capabilities. The first layer is a micro-cotton blend that meets the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Minimum Efficiency Reporting Value (MERV) 13 standard (Table 1), and the second layer is a PPK nanofiber air filter that meets the MERV 17 standard for this category.

[0070] Table 1. Properties of Air Filter Materials according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) MERV Standard

[0071] The air wool filter of the present invention has been tested in utility model patent application number MN20-2021-0004559 filed by the applicant of the present invention. The ability of the C2+C3 filter and the B filter to filter fine particulate matter (PM0.3) was determined by a Korean standard compliance laboratory, with the C2+C3 filter achieving 57.8% and the B filter achieving 12.5%.

[0072] The ability to filter fine particles is directly related to the fine diameter and high density of the air filter material [Non-Patent Literature 13], therefore two types of filter materials have been developed, and in accordance with... Figure 4 The chart shown illustrates the development of production techniques to enrich materials with higher filtration efficiency.

[0073] In this invention, coarse Mongolian wool is treated with alkali during industrial processing to obtain semi-degradable keratin. This allows copper nanoparticles, zeolite, and activated carbon to attach to the degradable structure to improve its functional properties, such as deodorization, providing antibacterial properties, and absorbing more toxic compounds [Non-Patent Literature 14 to 18].

[0074] This solution can be used to purify and filter air in buildings, industrial facilities, automobiles, heavy machinery, and household appliances. Attached Figure Description

[0075] Figure 1 This is a schematic diagram illustrating an example of a production method for the double-layer wool biocomposite air filter material of the present invention.

[0076] Figure 2 This is a schematic diagram illustrating an example of the manufacturing process of the air filter material according to the present invention.

[0077] Figure 3This is a schematic diagram of the structure of the double-layer wool biocomposite air filter of the present invention.

[0078] Figure 4 A graph is used to illustrate the experimental test results of determining the manufacturing method of air filter materials based on their ability to filter PM 0.3 air pollutants.

[0079] Figure 5 A schematic diagram illustrating the mechanism of filtering particles from the air.

[0080] Figure 6 To illustrate depth ( Figure 6 (a) and surface ( Figure 6 A schematic diagram of the working principle of (b) (membrane) filtration. Detailed Implementation

[0081] This invention relates to a double-layer wool biocomposite air filter material and its production method, which provides wool and has a double-layer structure.

[0082] The double-layer wool biocomposite air filter material of the present invention combines two methods for producing air filter materials: a structure-based method and an interaction-based method.

[0083] This solution uses pure wool in its double-layer wool biocomposite air filter material, and the waste generated after using the final product is completely biodegradable, making it an environmentally friendly solution.

[0084] In this scheme, coarse wool is defined as wool with a diameter of 160 micrometers or more. Fine wool is defined as wool with a diameter of at most 22 ± 10 micrometers.

[0085] In this process, coarse wool waste undergoes physical and chemical processing to produce semi-degraded keratin, which is then blended with biodegradable polymer compounds such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) to produce biocomposite particles (PLA / PBAT / keratin-PPK). The biocomposite particles are then produced using two types of fiber production technologies: PPK microfibers with a diameter of 1–5 micrometers and PPK nanofibers with a diameter of 0.2–1 micrometer. The PPK microfibers are enriched with fine sheep fibers or washed and combed wool with a diameter of up to 22 ± 10 micrometers and are used in an opening device to produce a pre-filter called a micro-cotton blend. The thickness of the material can be adjusted according to the application. The PPK nanofibers are used in multiple layers with a thickness of 0.2–5 mm and can be used alone or in combination with multiple layers of the micro-cotton blend, depending on the application.

[0086] Figure 3 The structure of the double-layer wool biocomposite air filter 20 of the present invention is schematically illustrated. Here, the filter 20 consists of a first layer 21 of micro-cotton blend (PPK fibers 23 mixed with cotton) and a second layer 22 of PPK nano-wool fibers 24. The first layer 21 has a looser fiber structure on the outer side (i.e., the side where air enters from the outside) (see section 21a), while it has a denser fiber structure on the inner side (see section 21b).

[0087] Airflow from the outside is illustrated by arrow 25, and airflow from the outside is illustrated by arrow 27. Airflow between multiple layers is also illustrated by arrow 26. As air flows through the first layer 21 and the second layer 22, particles 28, 28a, 28b, and 28c contained therein are trapped by the fibrous fibers, and the purified air flows out of the filter.

[0088] Air entering from the outside enters the first layer 21 from the outside. Because the fibers are sparse at the inlet, coarse particles (dirt) are trapped here (e.g., particles 28a). As the air flows inward, the fibers become denser, so the trapped particles become smaller (e.g., particles 28b).

[0089] The second layer 22 is made of PPK nanofibers 24, which are finer and denser and designed to filter small particles. Here, it is able to filter particles up to PM 0.3.

[0090] Sheep wool itself possesses neutral filling properties. Therefore, it is a condition that traps some small charged molecules. Furthermore, coarse Mongolian sheep wool (also known as mink wool, goat wool, etc.) with a size greater than 160 micrometers undergoes physicochemical processing and is mixed with biopolymer compounds (polylactic acid - PLA, polybutylene adipate / terephthalate).

[0091] Adipate terephthalate (PBAT) is used to produce biocomposite microfibers (called PPK microfibers) with diameters up to 1 ± 0.2 micrometers. This method has the advantage of allowing the formation of keratin complexes to incorporate some metals (such as copper and silver), thereby allowing them to exhibit antibacterial activity and other functional properties.

[0092] Mammal hair is a fine-grained material whose internal structure is composed of proteins. It is used to manufacture dense air-filtering materials. In addition, the outer keratin membrane (which is one of the hair fibers) has positive electromagnetic properties, thus enabling it to trap and filter some negatively charged volatile organic compounds in the air.

[0093] Therefore, using sheep wool as a material to filter small particles in the air is not only beneficial for air filtration due to the structural properties of wool, but it is also an environmentally friendly solution that does not pollute the environment.

[0094] This solution combines two methods: depth filtration and membrane filtration. Depth filtration uses filter materials with a structure that is more efficient than membrane filtration and can absorb or collect more particles.

[0095] The general technical solution of the production method of the double-layer wool biocomposite air filter material of the present invention is shown in the figure. Figure 1 In the diagram.

[0096] To produce double-layer wool biocomposite air filter material, the raw material wool is first prepared (step 1).

[0097] In this invention, coarse sheep wool is used as an example of wool. Other animal hairs, such as cashmere wool, may be used if they perform the same function as the coarse sheep wool used in this invention. For example, coarse sheep wool may be used.

[0098] The raw material is coarse wool that has been washed and combed to meet the requirements of MNS 6398:2020 standard, cut to a size of less than 3 mm, washed in a 0.1% Tween 80 solution, rinsed with distilled water and dehydrated (step 2). Tween 80 solution is an aqueous solution of surfactants. Different types meet the requirements here.

[0099] The wool is then bleached with alkali (step 3). Here, the washed and dehydrated wool is placed in a mixing device, and 3% (dry weight) of a 30% sodium hydroxide solution is added and mixed thoroughly. Afterward, 4.5% (dry weight) of wool is added and mixed for 4 hours. The mixture in the mixing device is then placed in a dehydrator to extract the solid phase, namely the keratin from the sheep wool.

[0100] A 10% solution was prepared by adding polylactic acid (PLA) and polybutylene adipate-terephthalate (PBAT) (steps 4 and 5).

[0101] Here, the keratin obtained in the above steps is mixed with a polylactic acid (PLA) / PBAT (80:20) polymer mixture at a ratio of 90:10 to prepare a dry mixture (steps 4 and 5).

[0102] This dry mixture was dissolved in ethyl acetate (EA) / dimethylformamide (N,N-DMF) in a 7:3 solvent (hereinafter referred to as "(E7:D3) solvent") to prepare a 10% solution. The solution was stirred at 75°C for 24 hours to obtain the biocomposite material.

[0103] To ensure uniform solidification of the extracted biocomposite material, it was placed in a twin-screw extruder and polylactic acid / PBAT / keratin particles of the sheep wool biocomposite material were produced at a speed of 200 rpm and a temperature of 175°C (step 6). Otherwise, granulation was performed.

[0104] Subsequently, the wool particle biocomposite material was spun into filaments using two methods: centrifugal spinning and electrospinning (steps 7 and 11). These two methods produced two different types of byproducts from the biocomposite particles: PPK microfilaments and PPK nanofilaments (steps 7a and 11a).

[0105] PPK microfibers

[0106] First, we will describe the centrifugal spinning of PPK microfilaments (steps 7 to 10). Granulated sheep biocomposites are spun into filaments at an appropriate speed using a thermo-controlled rotary spinneret. For example, the processed sheep biocomposites are spun into PPK microfilaments or biocomposite filaments with a diameter of 1 to 5 micrometers using a thermo-controlled rotary spinneret at a speed of 4500 rpm and a temperature of 175°C (step 7a).

[0107] The obtained biocomposite yarn is combined with fine Mongolian wool or washed and combed wool with a maximum diameter of 22 ± 10 micrometers and spun (steps 8 and 9). Here, the biocomposite yarn is combined with fine wool and mixed in a spinning device to produce a micro-cotton mixture or pre-filter (step 10). The thickness of the micro-cotton mixture is produced in appropriate quantities, from thick to thin, depending on the application.

[0108] PPK nanofibers

[0109] Let us briefly describe the production of PPK nanofibers. Processed sheep wool biocomposite material is dissolved in a solvent (e.g., ethyl acetate (EA) / dimethylformamide (N,N-DMF) in a 7:3 ratio), and the solution is fed into an electrospinning apparatus to spin and produce PPK nanofibers (steps 11, 11a). The electrospinning apparatus is operated at a high voltage (e.g., 90 kW) to spin and produce biocomposite nanofibers with a diameter of 0.2 to 1 micrometer. The biocomposite nanofibers are formed into filters with a certain thickness and shape.

[0110] There is also a process of ironing and shaping the aforementioned micro-cotton blend pre-filter and biocomposite nanofiber filter (step 12). Here, since the product will be used as a filter, the micro-cotton blend pre-filter and biocomposite nanofiber filter are ironed with a hot iron, which can be done under pressure, and ironed to obtain air filter material (step 12). During ironing, the temperature varies depending on the thickness of the material, and the wool air filter material is thus completed.

[0111] The extracted air filter material has a thickness of 0.2 to 5 mm and is comparable in efficiency to MERV 17 HEPA filters.

[0112] Here, the air filter material is a planar material with a certain thickness, which is cut according to the application, inserted into the filter mold, and the final product is produced (step 13).

[0113] Production steps

[0114] An example of the processing flow of the factory 1 producing the air filter material of the present invention is schematically illustrated in [the diagram]. Figure 2 middle.

[0115] The raw wool is washed and cleaned in washing unit 2. The capacity of washing unit 2 will vary depending on the amount of raw material used. For example, washing unit 2 can wash 15 kg of dry wool in one wash. Before putting the wool into washing unit 2, check for mechanical impurities and separate them from the wool. Put the wool into the washing unit and add 0.1% of TWEEN 80 solution. TWEEN 80 is a solution of polyoxyethylene (20) sorbitan monooleate or polysorbate 80, which is an aqueous solution of surfactant.

[0116] Washing unit 2 can be a manual washing tub or an automatic washing machine. Washing unit 2 is responsible for washing and cleaning the wool, and sterilizing it. The washing and sterilization process depends on the size of the wool, and takes approximately 30 minutes for the aforementioned sizes.

[0117] The wet wool quilt, after being washed and disinfected by the washing device 2, is placed in the dewatering device 3, and the water is drained. The dewatering device 3 is a device with rotating cylindrical (vertical or horizontal) pulleys that separates water (liquid) by centrifugal force. It can also be a device that squeezes the wool to remove moisture.

[0118] The dehydration device can be a large or small roller device depending on the size of the wool. For example, up to 25 kg of wet wool can be dehydrated in 10 minutes in a single operation.

[0119] To ensure that the wet wool exiting the dehydration unit 3 is completely dry, it is sent to the drying unit 4 for further drying. The drying unit 4 may be a device that operates based on the condensation principle or an electric dryer equipped with a heat pump.

[0120] The drying device 4 can, for example, dry up to 15 kg of damp wool in 30 minutes in a single operation.

[0121] After washing and drying, the wool is then shredded for further chemical processing. Here, cutting device 5 is used to cut and shred the wool to a particle size of less than 3.0 mm. Cutting device 5 is suitable if it has a capacity to cut up to 50 kg of wool per hour.

[0122] As mentioned above, the wool remains slightly damp even after drying. To chemically treat this damp wool, it is placed in tank 6, a 30% sodium hydroxide solution (3.0% of the dry wool) is added, and the mixture is thoroughly mixed. Then, it is placed in tank 7, 4.5% of the dry wool's weight in industrial soda ash is added, and the mixture is chemically treated for 4 hours, stirring and mixing to form a paste.

[0123] This mixture is pumped from tank 7 to dehydration unit 8, where the keratin is separated. Dehydration unit 8 may be a device that operates based on the principle of centrifugal force or the principle of pressure.

[0124] Then, the raw material (keratin) from the dehydration unit 8 is introduced into the drying unit 9 and completely dried. The drying unit 8 can be a device that operates based on the condensation principle or an electric drying machine with a heat pump.

[0125] Take 10% of the dried keratin and 90% of the polylactic acid / PBAT polymer mixture and place it in a dry mixer 10. Add 10 times the amount of the E7:D3 solution mixture and mix at 75°C for 24 hours to obtain a biocomposite material. Then place it in a granulator 11 to obtain biocomposite granules.

[0126] The pellet mill 11 is a device that operates according to the principle of a twin-screw extruder.

[0127] The extracted PPK mixture is placed in spinning device 12 and spun under centrifugal force to produce artificial cotton.

[0128] In this part of the technology, the produced polymer cotton and fine wool blend is fed into felting line 13 (a fully automated production line) for carding, carding, felting and cutting.

[0129] The felting line 13 is a fully automated line that uses belt conveyors between each function. Belt conveyors of any width can be used here; for example, a widely used 1300mm wide belt conveyor is used in this example.

[0130] In felting line 13, fine wool and PPK polymer wool are mixed in an 80:20 ratio, and the mixed wool is evenly distributed on the conveyor platform of the line. The belt conveyor is preferably equipped with a magnetic surface to prevent metal parts from entering the equipment, and such a belt conveyor is used in this example. The mixed wool is conveyed by the belt conveyor and enters the felting unit. The mixed wool from the felting machine is pumped in and enters the feed section of the carding machine. The wool from the carding unit passes through the belt conveyor and enters the felting unit. Here, the width and thickness of the felting material are preset. The felted loose material passes through the belt conveyor and enters a compactor with rollers heated to 200°C, where it is compressed and compacted by rollers from both sides.

[0131] The material from the compactor is cut into predetermined sizes by a cutting device via a belt conveyor. The cutting device winds the cut material onto a rotating shaft and removes the air filter material (step 14).

[0132] The resulting core-coating material will be used as an air filter material and will be cut (shredded and crushed) to the appropriate size for use in the manufacture of air filters.

[0133] experiment

[0134] The experiment established a method for producing air filter materials based on their ability to filter PM 0.3 air pollutants.

[0135] The results of this experiment are presented graphically. Figure 4 middle.

[0136] Figure 4 The horizontal axis of the chart shows the materials used in the experiment, labeled B here. A3, C2+C3 XI X2 X3 and X4 The thickness of each material is indicated on the chart.

[0137] The vertical axis on the left of the chart shows the density of the materials used in the test, and the vertical axis on the right shows the ability to filter PM3.0 particles.

[0138] Here, based on the results confirmed by experiments and analysis, the new development options are labeled XI to X4.

[0139] Y=4.11.82x-8.0911...(Formula 1)

[0140] R 2 =l ... (Formula 2)

[0141] Here: Y - PM0.3 Judicial capacity, % x - Material density, g / cm³ 3 R 2 - Correlation coefficient y = -22.148x + 196.49 ... (Formula 3) R 2 =0.0007...(Formula 4) Here: Y - PM0.3 Judicial capacity, % x - Material thickness, mm R 2 - Correlation coefficient Here, based on the experimental results, Equations 1 to 4 show how filtration capacity depends on the density and thickness of the material.

[0142] result

[0143] In this invention, domestically sourced raw materials are used to produce fully biodegradable filter materials.

[0144] This filter material can be mass-produced in many different types with varying filtration capabilities.

[0145] In this invention, there is a process for processing coarse sheep wool and mixing it with a biopolymer compound to produce biocomposite fibers, enriching fine sheep wool with it, and layering it with biocomposite fibers of even finer diameter, thereby obtaining a 100% biodegradable air-purifying biocomposite material.

[0146] The filter material of this invention combines both filter structure and interaction method to produce an effective end product that filters airborne particles through both deep and surface (film) mechanisms.

[0147] This move has resulted in a biodegradable filter material that can compete with existing high-efficiency particulate air (HEPA) filter materials on the market.

Claims

1. A double-layer wool bio-composite air filter material, comprising: The first layer is produced by processing microfibers, which are obtained from biocomposite particles made from washed and combed coarse wool, the diameter of which is at most 22 ± 10 micrometers. The second layer is made of nanofibers with a diameter of 0.2-1 micrometers, which are obtained by processing biocomposite particles made from washed and combed coarse wool.

2. A method for producing a double-layer wool bio-composite air filter material, comprising: In the dehydration step, the washed and combed coarse wool is prepared to a size of less than 3 mm, washed in an aqueous solution of 0.1% surfactant, and rinsed with distilled water. The mixture production step involves cleaning the mixing device with a 30% sodium hydroxide solution, mixing the dehydrated wool, and adding sodium percarbonate to form a mixture. The keratin extraction step involves using a dehydration device to extract keratin as a solid phase from the wool of the mixture obtained from the mixing device; The preparation step of the dried mixture involves mixing the extracted keratin with a polylactic acid / PBAT (80:20) polymer mixture at a ratio of 90:10; The 10% solution preparation step involves dissolving the dried mixture in a solvent of ethyl acetate (EA) / dimethylformamide (N,N-DMF) in a 7:3 ratio; In the biocomposite material extraction step, the solution was heated at 75°C for 24 hours; The biocomposite particle extraction step involves using a twin-screw extruder at a speed of 200 rpm and a temperature of 175°C to extract the biocomposite particles and uniformly harden the extracted biocomposite material. The microfiber and nanofiber extraction step extracts microfibers and nanofibers from the biocomposite particles; and The production steps of the double-layer wool air filter material include ironing the microfibers and nanofibers at different temperatures according to the thickness of the material.

3. The method for producing the double-layer wool bio-composite air filter material according to claim 2, wherein... The microfiber production step involves spinning the biocomposite particles using a temperature-controlled rotary spinning machine at a speed of 4500 rpm and a temperature of 175°C to produce microfibers with a diameter of 1-5 micrometers; and The pre-filter production step involves combining the microfibers with fine Mongolian wool or washed and combed wool with a diameter of up to 22±10 micrometers using an opening device to produce a pre-filter.

4. The method for producing the double-layer wool bio-composite air filter material according to claim 2, wherein... The nanofiber production step involves dissolving the biocomposite particles in a solvent and spinning them using a high-voltage electrospinning device that introduces the solution, in order to produce nanofibers with a diameter of 0.2-1 micrometers.

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