4-ply face mask

Abstract

The present invention relates to the design of a face mask incorporating a waste-derived warp knit polyethylene terephthalate permeable spacer layer for daily use in the current pandemic conditions. The central layer of the face mask is a selectively hydrophobic layer, recycled from waste RO membrane modules, intended for use as a non-medical multi-layer face mask for the general public. The mechanical strength and shape retention ability allow for the creation of a unique 3D shaped face mask that stretches from the bridge of the nose to the chin, leaving an air gap between the mouth and the inner layer of the face mask. The introduction of the PET layer provides the design advantage of smoothing facial movements and not impeding conversation. The 3D fold of the mask is seam-free and conforms closely to the user's face, suppressing fogging of glasses and possible infection.

Description

[Technical field]

[0001] The present invention relates to a face mask design incorporating a waste-derived warp knit polyethylene terephthalate (PET) permeable spacer layer for daily use during pandemic conditions. The central layer of the face mask is a selectively hydrophobic layer recycled from waste RO membrane modules, intended for use as a non-medical multi-layer face mask for the general public. More specifically, the face mask has a four-layer structure, including two tightly woven cotton layers as the first and fourth layers, a waste-derived recycled hydrophobic PET layer and a polypropylene nonwoven layer as the second and third layers, respectively. The mechanical strength and shape retention ability allow the creation of a unique 3D shaped face mask that stretches from the bridge of the nose to the chin, leaving an air gap between the mouth and the inner layer of the face mask. The incorporation of the PET layer provides design benefits that allow smooth facial movements and unhindered conversation. The 3D fold of the mask is seamless and fits snugly to the user's face, preventing fogging of glasses and infection. [Background technology]

[0002] Due to the sudden outbreak of the COVID-19 pandemic, various health control measures and public safety guidelines have been formulated and implemented, among which wearing a face mask is the first and foremost imperative. Countries such as Italy, the United States, Canada, Brazil, and Spain have been confirmed to be significantly affected compared to Japan, Taiwan, India, and other countries that use face masks. The main route of infection is through liquid droplets and aerosols that carry infectious pathogens, so using a face mask is the primary means of fighting the virus. Research has shown that more than 90% of person-to-person infections occur through contact with and inhalation of aerosols that carry infectious diseases, so the first choice to prevent and protect against the spread of the virus is the use of a face mask, which is recommended by most medical experts as well as the World Health Organization (WHO). However, because the outbreak of the pandemic was so rapid and critical, the market supply of surgical masks and N95 face masks was not enough to meet the demand. To meet the surge in demand and to make up for the shortage of commercially available face masks, alternative low-cost face masks were designed and developed. The COVID-19 pandemic has not only collapsed the medical infrastructure, but also seriously affected the economy and transportation, making it very difficult to obtain raw materials for preparing face masks. To prevent the cumulative impact of COVID-19 on the general public, a low-cost, durable, high-quality face mask derived from waste and capable of protecting against viruses and other pathogens has been developed. In this context, the present disclosure describes the composition of a mask designed and developed for large-scale production to protect the general public against airborne viruses and pollutants.

[0003] See U.S. Patent No. 4,856,509, in which a face mask structure is provided with a chemical coating on a porous film to prevent the spread of disease, such as that contained in dust particles or aerosol particles of bodily fluids.

[0004] See U.S. Patent Application Publication No. 2009 / 0211581, in which a microporous membrane layer and an absorbent fabric layer are used to create a respirator to protect the wearer from airborne particulates, chemical vapors, and droplets.

[0005] See US Patent No. 7,802,572, which relates to a face mask design with an air impermeable central transparent portion and an outer filter portion that is made of antimicrobial, deodorant and masking agents.

[0006] See U.S. Patent No. 6,412,486, which details the manufacture and use of a disposable filtering (membrane) mask to protect persons moving through the air from airborne contaminants. The mask has two layers, an outer layer that traps larger contaminants like dust and a small percentage of bacteria and other germs, and a second layer that traps fine particles that get through the first layer.

[0007] See U.S. Patent Application Publication No. 2011 / 0209711, published Sep. 1, 2011, in which a disposable protective respirator is made from a multi-layered spunbonded nonwoven fabric, the first middle layer being a felt-type tribocharged nanofabric and the second layer being a nonwoven ply of meltblown microfiber.

[0008] See US Patent Application Publication No. 2010 / 0101584, in which a reusable mask is constructed from a flexible porous shell that can be secured to the wearer's face and a removable semi-rigid respiratory filter that fits within the shell to which one or more exhalation valves are attached.

[0009] See European Patent No. 0051616 which relates to a method for producing a disposable surgical mask having high bacterial filtration efficiency, conforming to the face, being flexible, and having minimal weight and resistance to ventilation.

[0010] See U.S. Patent No. 4,790,307, in which a disposable surgical mask is self-coated in the center with an antibacterial fluid to reduce the transmission of ectopic and nosocomial infections in operating rooms used by doctors and nurses.

[0011] See US Patent No. 6,681,765, which discloses an antiviral and antibacterial mask for general public use that helps prevent bacteria, viruses, spores, algae, fungi, protozoa, and harmful and toxic gases from entering the nasal passages. The mask is lightweight and disposable, and protects against organic and inorganic harmful substances in the air.

[0012] See U.S. Patent No. 7,845,351, issued Dec. 7, 2010, in which a face mask is described that has germicidal properties that reduce microbial activity. The layers used in the mask are nonwoven fabrics such as spunbond, meltblown, or coform. The masks can be used for medical, industrial, and household purposes, and protect the user from dust and other harmful airborne contaminants.

[0013] See US Patent Application Publication No. 2009 / 0320849, in which a face mask is made of a filter material specially made from nonwoven polypropylene and has a Carbopol-type acidic polymer deposited on the fibers, the mask having antiviral properties that prevent the inhalation of harmful viruses and other biological contaminants.

[0014] See U.S. Patent Application Publication No. 2019 / 0215421, in which textile waste consists primarily of cotton and wool for the production of fibers that are then combined with a thermoplastic binder to create a nonwoven mat.

[0015] Objective of the invention The primary objective of this invention is to design and develop a reusable, washable, cost-effective and environmentally friendly multi-layer face mask incorporating waste membrane-derived polyethylene terephthalate (PET) permeable spacer from waste RO membrane modules for protection of the public under various conditions.

[0016] Another objective of the present invention is to reduce the use of raw materials and energy in making the new PET layers used in designing 4-ply non-medical face masks for general commuters, working people, corporate employees, street vendors, sanitation zone workers, support staff working in crowded places like hospitals, schools, shopping malls, markets etc.

[0017] Yet another object of the present invention is to reduce the generation of plastic waste and continuously reuse the polyethylene terephthalate (PET) membrane permeable spacer of four-ply non-medical face masks.

[0018] Yet another object of the present invention is to develop a simple and reproducible method for manufacturing a non-medical polyethylene terephthalate (PET) membrane permeable spacer integrated face mask having cotton fabric as first and fourth layers and polypropylene as the third layer.

[0019] Yet another object of the present invention is to scientifically verify the performance of a polyethylene terephthalate (PET) membrane permeable spacer built-in face mask through permeability, durability, washability, liquid retention, anti-inflammatory properties, breathability, bacterial filtration efficiency, and particle filtration efficiency tests. Summary of the Invention

[0020] In the context of the COVID-19 pandemic, the use of protective masks as a preventive measure has been recommended by the World Health Organization for healthcare workers as well as the general public. Since the outbreak of the pandemic, the market demand for face masks has increased exponentially, creating a severe shortage of available commercial face masks. The present invention provides an alternative method for the affordable production of multi-layered reusable face masks. The first aspect of the present invention is to design a non-medical 4-ply face mask combining a polyethylene terephthalate (PET) layer derived from waste / used membranes with two cotton layers and one polypropylene layer. The incorporation of permeable spacers obtained from waste membrane modules is a "waste-to-health" conversion step integrated into the mask manufacturing. The polyethylene terephthalate (PET) layer obtained from waste membrane modules offers two advantages: resource recovery and economy. PET is one of the key layers that impart structural integrity, mechanical strength, tortuosity, and durability to face masks due to its hydrophobicity and warp knit structure.

[0021] The 4-ply face mask (4-ply or 4-ply face mask) is equipped with a recycled microporous hydrophobic warp-knitted PET (polyethylene terephthalate) permeable spacer from a spiral wound waste RO / UF membrane module, thereby reducing plastic pollution by recycling the PET spacer material of the spiral wound waste membrane module. The manufacturing process is composed of the following layers from the outside:

[0022] a) The outer layer [1] consists of a tightly woven cotton fabric layer with a 100 x 100 count specification, which acts as a per-filter to prevent the ingress of particulate matter larger than 5-10 μm (Figure 1a, Figure 1b) and also improves the appearance of the face mask.

[0023] b) The second layer [2] consists of a microporous hydrophobic polyethylene terephthalate (PET) membrane spacer fabric (Figure 1a) derived from used wound reverse osmosis or ultrafiltration membrane modules, which repels respiratory droplets that come into contact with the mask by electrostatic repulsion and a high contact angle.

[0024] c) The third layer [3] is made of a hydrophobic polypropylene (PP) nonwoven fabric layer and is arranged adjacent to the PET layer from the front end side.

[0025] d) The inner layer [4] in contact with the face is made of closely woven cotton fabric layers to provide comfort to the wearer and enable long-term use, and the four layers (Figures 1a and 1b) are closely sewn together to provide a dense void space of less than 0.3 μm and water repellency.

[0026] A four-ply multi-layer PET permeable spacer face mask with a woven cotton outer layer [1] that prevents inhalation of airborne contaminants, especially larger particle sizes, and gives the mask a soft finish and proper structure for user comfort.

[0027] A four-ply multi-layer PET permeable spacer face mask, with a microporous hydrophobic PET second layer [2] as a permeable spacer derived from used wound reverse osmosis or ultrafiltration membrane modules, warp knitted to help prevent inhalation of airborne contaminants such as large particles, pollen, dust, bacteria, and other pathogens, and to help reduce solid waste generation.

[0028] A four-ply multi-layer PET permeable spacer face mask in which a third layer of porous polypropylene nonwoven fabric [3] adjacent to the PET layer acts as a filter to restrict contaminants or germs not captured by the other layers.

[0029] A four-layered PET permeable spacer face mask in which a hydrophobic polypropylene (PP) nonwoven layer [3] is placed next to the PET layer [2] to limit the ingress of contaminants past layers 1 and 2.

[0030] A four-ply multi-layer PET permeable spacer face mask with each layer of the mask measuring 9.5 inches by 6.5 inches (Figure 3c) and 6.65 inches by 4.55 inches (Figure 3d), trimmed for universal and junior sizes, respectively.

[0031] This is a four-layered, multi-layered PET permeable spacer face mask that is designed with a unique 3D pattern (Figure 3) that effectively covers the face without restricting facial movement and does not interfere with speech or breathing, and can be reused for up to three months or 30 washes.

[0032] The reuse and repurposing of polyethylene terephthalate (PET) permeable spacers obtained from waste membrane modules provides a low-cost and economically viable alternative, while at the same time resulting in sustainable waste reuse and repurposing. The four-layer configuration, incorporating two cotton fabrics as the first and fourth layers, and PET and polypropylene fabrics as the second and third layers into a face mask, creates a vigorous and tortuous path that can restrict particulate matter with sizes of 0.3 μm to 10 μm from causing infectious diseases. Furthermore, the mask can filter out 95-98% of respiratory droplets as small as 0.3 μm. In the four-layer face mask configuration, the layers of the mask are non-toxic, non-allergenic, non-hazardous, and biocompatible. The front and back cotton layers provide good appearance and comfort to the wearer, respectively. The second layer is a hydrophobic PET fabric obtained from waste membrane modules, which is flexible, hydrophobic, stain-resistant, breathable, waterproof, and easy to sew the layers. The third layer is a microporous hydrophobic polypropylene nonwoven layer, whose tiny pores help keep out harmful bacteria and viruses.

[0033] Another aspect of the present invention involves a simple preparation method that can be adopted and reproduced by a layperson following easy procedures.

[0034] The manufacturing method of the 4-ply face mask includes: a) making the outer layer [1] using a 100 x 100 count densely woven cotton fabric layer, which acts as a per-filter to prevent the intrusion of particulate matter larger than 5 to 10 μm and improve the appearance of the face mask; b) making the second layer [2] using a microporous hydrophobic polyethylene terephthalate (PET) membrane spacer fabric obtained from used rolled reverse osmosis membrane modules or ultrafiltration membrane modules to repel respiratory droplets that contact the face mask by electrostatic repulsion and a high contact angle; c) making the third layer [3] using a hydrophobic polypropylene (PP) nonwoven fabric layer, which is placed next to the PET layer from the front end side; d) making the inner layer [4] that directly contacts the face using a densely woven cotton fabric layer to make the wearer comfortable and enable long-term use; and e) sewing all layers closely together so that the dense air gaps are water repellent at 0.3 μm or less.

[0035] Moreover, after 2-3 months of use, the masks are disposed of by incinerating the cotton layer, recycling the polypropylene layer at solid waste treatment facilities to produce other value-added products, and reusing the PET layer after recycling. Thus, this non-medical 4-ply face mask brings an immediate solution for the general public, frontline sanitation workers, etc. to protect themselves from COVID-19 virus infection. The masks have been tested for bacterial filtration efficiency, particulate filtration efficiency, breathability, flammability, drip resistance, washability, liquid retention capacity, and durability at the Membrane Separation Laboratory of CSIR-IICT, Hyderabad, Telangana, India. The results obtained have been certified and verified by South Indian Textile Research Association (SITRA)-Center of Excellence for Medical Textiles, Coimbatore, India. A cost comparison of the designed mask was also conducted with similar commercially available masks. [Brief description of the drawings]

[0036] [Figure 1a] A schematic diagram of a four-ply face mask incorporating a waste-derived PET layer. [Figure 1b]FIG. 1 is a schematic diagram of the process for sourcing waste-derived PET layers from spent RO / UF filtration membranes for incorporation into face masks. [Figure 2a] Schematic arrangement of beads on the ear straps of a face mask. [Figure 2b] This is a photo of the mask with the ear straps fixed. [Figure 3a] FIG. 1 is a front view of a sewn mask having portions with and without folds along the elastic ear straps. [Figure 3b] FIG. 2 is a rear view of a sewn mask with elastic ear straps. [Figure 3c] Layout and dimensions of a universal fit face mask. [Figure 3d] Layout and dimensions of a junior fitted face mask. [Figure 3e] Photographs of fitted face masks for adults and children. [Figure 4] FIG. 1 shows bacterial filtration efficiency test by open plate method. [Diagram 5] FIG. 1 is a diagram of particle filtration efficiency testing. [Figure 6a] This is an experimental setup for an air test cell using a circular mask inside the cell. [Figure 6b] This is an experimental device for permeability testing. [Figure 7a] SEM image of waste-derived PET layers at 50x magnification and 1mm scale. [Figure 7b] SEM image of waste-derived PET layer at 150x magnification and 300μm scale. [Figure 7c] 1 is a SEM image of a polypropylene nonwoven layer at 100x magnification and 500 μm scale. [Figure 7d] This is an SEM image of a cotton fabric layer at 50x magnification and 1mm scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Due to the sudden outbreak of the COVID-19 pandemic, various medical countermeasures and public safety guidelines have been formulated and implemented, among which wearing a face mask is the first and foremost necessity. Understanding the necessity and usefulness of face masks, a low-cost multi-layer face mask was designed and developed to prevent the spread of the COVID-19 virus. After extensive research and development on the materials used in the mask, a design was made that perfectly combines high protection performance and aesthetic beauty at an affordable cost. Then, the development of a four-layer 3D design mask including waste-derived PET was considered. A hydrophobic polypropylene layer is sandwiched between the woven layers, and the first barrier is the waste-derived hydrophobic PET layer, which not only provides mechanical support to the mask but also blocks airborne particulate pollutants including dust, smoke, animal dander, and pollen. The polypropylene layer is non-wetting, so it does not absorb respiratory droplets and is also capable of electrostatic repulsion. The microporous polypropylene nonwoven layer provides additional safety due to its dense voids. The cotton woven layers located on the front and back of the mask provide aesthetic beauty and provide comfort to the wearer by controlling humidity and temperature.

[0038] The biggest advantage of these multi-layered face masks is that they create a highly tortuous path and prevent the passage of aerosols between 0.3μm and 10μm, thus restricting bacteria and some viruses from entering the respiratory tract and providing effective protection. It should be noted that micro- or ultra-porous membranes were found to cause breathing difficulties, so antibacterial polypropylene fabric was used instead. The masks are expected to be usable for at least 2-3 months if they are regularly disinfected and gently hand-washed with mild soap under running water and then dried. The face masks developed at CSIR-IICT will be sent for testing and certification at SITRA, a standard government testing laboratory in Coimbatore. The disclosed masks will be manufactured as reusable personal protective equipment for the general public living in villages and towns, and new designs for medical workers and paramedical personnel will be developed based on the test results and feedback from real-time usage.

[0039] Face masks are designed for long-term use, lasting more than 8 hours, and require comfort without restricting facial movement during conversation or breathing. Reusing the PET layer from waste membrane modules can reduce more than one ton of plastic for every 200,000 masks produced. The components and arrangement of the four layers of the face mask are shown in Figure 1a. Figure 1b shows the route to obtain the waste-derived PET layer from the used membrane module. After the filtration efficiency of the RO / UF membrane in water purification decreases, the inner rolled membrane is removed from the housing and cut open to extract the PET permeable spacer. The waste-derived PET membrane spacer is then cleaned and disinfected and incorporated as the central layer of the multi-layer face mask. Each layer of the face mask is sewn at the ends to physically bond with each other, and flexible elastic straps are attached to both ends for fastening. Each elastic ear strap has an adjustment bead to allow the wearer to change the tightness and fit to the face. The face masks are available in two sizes: Universal for adults with dimensions of 9.5 inches by 6.5 inches, and Junior for children with dimensions of 6.65 inches by 4.55 inches (Figure 2). The design purposefully does not have a backflow valve to avoid air pollution and disease transmission due to breathing by infected individuals. The fabrication mode of the four-layer non-medical polyethylene terephthalate membrane permeable spacer built-in face mask is shown in Figure 1. The non-medical mask has 75 GSM tightly woven cotton fabric as the first and fourth layers, 90 GSM microporous hydrophobic polyester (PET) and 25 GSM polypropylene (PP) fabric as the second and third layers, respectively. This four-layer mask has excellent breathability and is used by the general public, working people, and organization staff. The microporous hydrophobic polyester (PET) fabric provides mechanical support to the mask and is the first barrier to block airborne particulate contaminants, especially dust, smoke, animal dander, and pollen. The PP layer is non-wetting, which helps repel respiratory droplets. In addition, the PP layer also has electrostatic repelling properties. The tightly woven cotton fabric absorbs moisture during conversation and controls temperature, making the user comfortable. In addition to this, the most effective 4-ply non-medical masks can prevent the entry of airborne microorganisms.Therefore, the designed four-ply mask is suitable for general commuters, working people, organization staff, street vendors, etc. The sample masks made with this pattern were found to be very convenient for users and comfortable to breathe through, based on feedback from volunteers. EXAMPLES

[0040] The following examples are presented to illustrate the scope of the invention and should not be construed as limiting the invention.

[0041] Example 1: Testing of CSIR-IICT masks and commercial masks in Membrane Lab Experiments were conducted to evaluate the performance of the designed mask. An external agency, SITRA, conducted the tests to evaluate bacterial filtration efficiency, particulate filtration efficiency, breathability, flammability, and splash resistance according to ASTM test methods. Breathability and water permeability tests were conducted with our own testing equipment. The test reports for all the mentioned physical parameters are enclosed in Annexures A and B. A cost comparison analysis between our designed mask and commercially available masks was also conducted. The details of the tests conducted with the developed face mask and comparison with commercially available face masks are shown in Table 1. Table 1: Testing of CSIR-IICT masks and commercial masks in the membrane lab TIFF0007665097000001.tif80170

[0042] Example 2: Washing durability test The prepared masks were washed 5 to 30 times. The prepared masks were washed and dried, and the changes were observed after washing 5, 10, 20, and 30 times. The performance of the designed masks was compared with a commercially available cotton mask. The prepared 4-ply masks were extensively tested for durability, breathability, appearance, and fit, and the results are summarized in Table 2. Table 2: Physical parameters observed during wash durability testing TIFF0007665097000002.tif40131

[0043] Example 3: Bacterial filtration efficiency test Bacterial filtration efficiency test was carried out at membrane separation laboratory CSIR-IICT to measure the number of bacteria passing through the mask. The mask was sterilized by UV irradiation on both sides for 15 minutes to prevent microbial contamination. At the same time, 30 mL of nutrient medium was poured into each petri dish to prepare medium plates. After the nutrient medium solidified, the sterilized mask was placed on one plate and the other plate had only nutrient medium. These plates were exposed to 100 L of air for 4 hours and incubated at 37°C for 24 hours. Finally, colonies were counted using a colony counter to measure the bacterial filtration efficiency. The results are shown in Table 3 and Figure 4 (a and b). Table 3: Bacterial filtration efficiency of different layers TIFF0007665097000003.tif34131

[0044] Example 4: Particle Filtration Efficiency Particulate matter with an average particle size of 0.3 μm was sprayed onto the mask using air and water as a medium. From the experimental results in Table 4, the PFE of this mask was 83.57%. Table 4: Experiments to evaluate particle filtration efficiency TIFF0007665097000004.tif22131

[0045] Example 5: Air and water permeability tests The air and water permeability tests were carried out in a stainless steel (SS) test cell, as shown in Figures 6a and 6b. The mask had an effective surface area of ​​0.0072 m 2The mask was placed in a SS cell, which was reinforced and fixed with flanges on both sides. Three polyurethane (PU) pipelines were connected to the cell: supply, permeate, and exhaust. Air or water was delivered to the mask through the supply line. Three pressure gauges and three control valves were fixed to the supply line, permeate line, and exhaust line, respectively. First, air was supplied to the test cell at a controlled pressure of 0.5 bar. The exhaust line was normally closed. At this pressure, the permeate air started to flow slowly downstream after passing through the mask. Then, when a steady state was reached, the permeate volumetric flow rate was measured using a bubble flowmeter. Meanwhile, the water test was carried out by passing water through the supply flow path, which was connected to the test cell followed by the pressure gauge and control valve. Sufficient pressure (0.5 bar) was applied to the cell to pass water through the mask. The filtered water was collected from the permeate side to know the permeability and efficiency of the mask. The detailed experimental results are shown in Table 5. Table 5: Air permeability and water permeability tests TIFF0007665097000005.tif29131

[0046] A comparison of the overall properties of the CSIR-IICT designed warp knit 4-ply face mask and commercially available N95 masks is given in Table 6. Table 6: Comparison of IICT and N95 Efficiency Masks TIFF0007665097000006.tif85131 *Tested at a pressure of 7.25 psi (g) and a temperature of 28±2°C. -IICT masks are 2.2 times more breathable than N95 masks. -IICT masks are water repellent, with only 37% of the water permeability of N95 masks. The IICT mask has a breathability to water permeability ratio of 712. The N95 mask has a breathability to water permeability ratio of 122.

[0047] The price of this mask was estimated and compared with commercially available masks, as shown in Table 5. Physical properties such as reusability, hydrophobicity, breathability, water permeability, flexibility, and price were also compared (Table 5). It was confirmed that the newly developed mask is significantly superior to commercially available masks in terms of cost and performance (Table 7). Table 7: Cost comparison of modern masks TIFF0007665097000007.tif90170

[0048] Example 6: Cost Estimation Following the design of the multi-layer mask, a cost estimation analysis was performed as part of the present invention. The materials used in the design of the multi-layer mask and their unit cost were calculated and are shown in Table 8. According to this analysis, the materials shown in the table are available in the market and are cost-effective. Table 8: Cost estimates for single-unit multi-layer masks TIFF0007665097000008.tif58131

[0049] Example 7: Contact angle test using a goniometer Contact angle measurements were performed for each layer of the designed mask by the sessile drop method using a software controlled system. Measurements were performed by dispensing a water drop from a Hamilton syringe onto the mask layer fixed on a glass plate. The sample was held within the focal distance of a magnifying camera and a backlight, and the intensity of the incident light was adjusted using computer-aided software. A proprietary algorithm provided with the instrument was used to infer the contact angle formed by the drop photographed at a programmed speed by a frame grabber.

[0050] Example 8: Scanning electron microscopy analysis All four layers of the mask were analyzed at different magnifications to determine the surface morphology and microstructure of the material. The results are shown in Table 9. The analysis was carried out using a JSM 5410 Scanning Electron Microscope (SEM) (JEOL Ltd., Tokyo, Japan). The samples were fractured in liquid nitrogen prior to fitting and were thin-coated with gold according to standard methods. Table 9: Microscopic images of the internal structure of the mask TIFF0007665097000009.tif71165

[0051] Advantages of the Invention The polyethylene terephthalate membrane permeable spacer-embedded face mask has a waste membrane spacer derived from used reverse osmosis (RO) membranes as a layer that gives mechanical strength and washable texture to the entire mask and filters airborne pollutants.

[0052] The unique 3D pattern of the polyethylene terephthalate membrane permeable spacer face mask allows unrestricted facial movement, prevents glasses from fogging, and allows the user to breathe and talk comfortably. The flexible finish of the mask makes it comfortable for the user.

[0053] The polyethylene terephthalate membrane permeable spacer built-in face mask can be washed and reused for 3-4 months without losing its shape or properties.

[0054] The unique feature of the developed polyethylene terephthalate membrane permeable spacer built-in face mask is that it uses waste RO membrane spacers, which reduces plastic pollution and allows for zero waste recycling, making it a green technology.

Claims

1. A four-ply face mask having a microporous, hydrophobic, warp-knitted polyethylene terephthalate permeable spacer from a wound used reverse osmosis (RO) membrane module or ultrafiltration (UF) membrane module, the four-ply face mask reducing plastic pollution by recycling the microporous, hydrophobic, warp-knitted polyethylene terephthalate permeable spacer, a) an outer layer (1) having a tightly woven cotton fabric layer that acts as a filter to prevent the ingress of particulate matter larger than 5-10 μm (FIGS. 1a and 1b) and improves the appearance of the face mask; b) a second layer (2) made of a microporous hydrophobic warp knit polyethylene terephthalate permeable spacer from wound used reverse osmosis (RO) or ultrafiltration (UF) membrane modules, which repels respiratory droplets that contact the face mask by electrostatic repulsion and a large contact angle; c) a third layer (3) having a hydrophobic polypropylene nonwoven fabric layer arranged adjacent to the second layer (2) from the front end side; and d) an inner layer (4) that contacts the face and is made of a tightly woven cotton fabric layer, providing comfort to the user and allowing for extended wear; from the outside, The four layers (FIGS. 1a and 1b) are closely sewn together to provide air gaps of 0.3 μm or less and water repellency to the face mask.

2. 2. The face mask according to claim 1, A face mask in which the outer layer (1) prevents inhalation of particulate airborne pollutants and has a soft finish for comfort to the user.

3. 2. The face mask according to claim 1, The second layer (2) of the face mask is made of warp knit to provide protection against inhalation of airborne contaminants such as large particles, pollen, dust, bacteria, and other pathogens.

4. 2. The face mask according to claim 1, A face mask in which a third layer (3) adjacent to the second layer (2) acts as a filter to restrict contaminants or germs not captured by the other layers.

5. 2. The face mask according to claim 1, A hydrophobic polypropylene nonwoven layer (3) is disposed adjacent to the second layer (2) to limit further ingress of contaminants through the first and second layers.

6. 2. The face mask according to claim 1, A face mask in which the dimensions of each layer of the face mask are either a universal size of 9.5 inches by 6.5 inches (Figure 3c) or a junior size of 6.65 inches by 4.55 inches (Figure 3d).

7. 2. The face mask according to claim 1, The face mask is designed with a unique 3D pattern (Figure 3) that extends from the bridge of the nose to the chin, leaving a gap between the mouth and the inner layer of the face mask (4), effectively covering the face without restricting facial movement, does not interfere with conversation or breathing, and can be reused for up to three months or 30 washes.

8. 2. The face mask according to claim 1, The bacterial filtration efficiency of the designed face mask is 95.7% against Staphylococcus aureus ATCC 6538 when tested according to ASTM F2101 test method, the overall filtration efficiency against all fungi, gram-positive and gram-negative bacteria present in the air is 90% using the open plate method, and the particulate filtration efficiency against 0.3 μm particles of the developed mask is 83.57% according to ASTM F2299 test method, the face mask.

9. 2. The face mask according to claim 1, The breathability of the developed mask was 211.01 Pa / cm when tested using the differential pressure EN 14683 test method. ２ and The flammability of the developed mask, when inclined at 45° in an automatic flame chamber and tested according to the 16CFR Part-1610 test method, was 38.8 seconds, and the average burn time of the Class I category face mask is 3.5 seconds or more.

10. A method for manufacturing a four-ply face mask, comprising: a) making the outer layer (1) using a tightly woven cotton fabric layer that acts as a filter to prevent the ingress of particulate matter larger than 5-10 μm and improves the appearance of the face mask; b) using microporous hydrophobic warp knit polyethylene terephthalate permeable spacers from wound spent reverse osmosis (RO) or ultrafiltration (UF) membrane modules to create a second layer (2) that repels respiratory droplets that contact the face mask due to electrostatic repulsion and large contact angles; c) preparing a third layer (3) using a hydrophobic polypropylene nonwoven fabric layer, the third layer (3) being disposed adjacent to the second layer (2) from the front end side; d) using a tightly woven cotton layer to create an inner layer (4) that comes into direct contact with the face and provides comfort to the user for extended use; and e) Stitching all layers closely together to provide small voids of 0.3 μm or less and water repellency. The manufacturing method of the present invention.

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