Respirators, respirator materials and methods of manufacturing the same

Abstract

A disposable, flat-fold respirator is presented that includes a mask body that includes a plurality of panels which may fold in towards each other and may unfold into an open configuration. The mask body includes a single layer of charged filter material. The plurality of panels includes an upper panel, a lower panel, and a central panel. The central panel is connected to the upper panel and lower panel. The respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 µm. A harness is secured to the mask body.

Description

[0001] RESPIRATORS, RESPIRATOR MATERIALS AND METHODS OF MANUFACTURING THE SAME

[0002] Background

[0003] Maintenance-free respirators (sometimes referred to as "filtering face masks" or "filtering face pieces") are commonly worn over the breathing passages of a person to prevent impurities or contaminants from being inhaled by the wearer. Maintenance-free respirators typically comprise a mask body and a harness and have the filter material incorporated into the mask body itself — as opposed to having attachable filter cartridges or insert molded filter elements (see e.g., U.S. Patent 4,790,306 to Braun) — to remove the contaminants from the ambient air.

[0004] To ensure that contaminants do not inadvertently enter the mask interior without passing through the filter media, maintenance-free respirators have been designed to fit snugly upon the wearer's face. Conventional maintenance-free respirators can, for the most part, match the contour of a person's face over the cheeks and chin. In the nose region, however, there is a complex contour change, which makes a snug fit more challenging to achieve. Failure to achieve a snug fit can allow air to enter or exit the respirator interior without passing through the filter media. In this situation, contaminants may enter the wearer's breathing track, and other persons or things may be exposed to contaminants exhaled by the wearer. Further, the wearer's eyewear can become fogged, which, of course, makes visibility more troublesome to the wearer and creates further unsafe conditions for the user and others.

[0005] Summary

[0006] A disposable, flat-fold respirator is presented that includes a mask body that includes a plurality of panels which may fold in towards each other and may unfold into an open configuration. The mask body includes a single layer of charged filter material. The plurality of panels includes an upper panel, a lower panel, and a central panel. The central panel is connected to the upper panel and lower panel. The respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. A harness is secured to the mask body.

[0007] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. It is to be understood, therefore, that the following description should not be read in a manner that would unduly limit the scope of this disclosure.

[0008] Brief Description of the Drawings

[0009] FIGS. 1A-1D illustrate views of a respirator in accordance with embodiments herein.

[0010] FIG. 2 illustrates a conventional respirator construction.

[0011] FIG. 3 illustrates a method of constructing a respirator in accordance with embodiments herein. Detailed Description

[0012] As used in this document, the following terms are defined as set below:

[0013] The term "about" is used to indicate that the numerical values specified are approximate and may include variations within a range of at least ±10% of the stated value. This term allows for minor deviations from the exact numerical values, acknowledging that such variations do not significantly affect the overall function or performance of the product. For example, "about 60 gsm" may encompass values from 54 gsm to 66 gsm, providing flexibility while ensuring that the product remains within acceptable performance parameters.

[0014] "central panel" means a panel that is located between upper and lower panels;

[0015] "clean air" means a volume of atmospheric ambient air that has been filtered to remove contaminants;

[0016] "contaminants" means particles (including dusts, mists, and fumes) and / or other substances that generally may not be considered to be particles (e.g., organic vapors, et cetera) but which may be suspended in air, including air in an exhale flow stream;

[0017] "exterior gas space" means the ambient atmospheric gas space into which exhaled gas enters after passing through and beyond the mask body and / or exhalation valve;

[0018] "filter " or "filtration layer" means one or more layers of material adapted for the primary purpose of removing contaminants (such as particles) from an air stream that passes through it;

[0019] "filter media" means an air-permeable structure that is designed to remove contaminants from air that passes through it;

[0020] "flat-fold" means the respirator has at least one line of demarcation about which the respirator generally folds or bends in response to simple manual pressure;

[0021] "integral" means that it is part of the whole panel or mask body and is not a separate piece that is attached thereto;

[0022] "harness" means a structure or combination of parts that assists in supporting a mask body on a wearer's face;

[0023] "interior gas space" means the space between a mask body and a person's face;

[0024] "line of demarcation" means a fold, seam, weld line, bond line, stitch line, hinge line, and / or any combination thereof;

[0025] "lower panel" means a panel that extends under or makes contact with a wearer's chin when the respirator is being worn by a person;

[0026] "mask body" means an air-permeable structure that can fit at least over the nose and mouth of a person and that helps define an interior gas space separated from an exterior gas space;

[0027] "molded" means causing the element being molded (for example, the shaping layer) to take on a predefined form after being exposed to heat and / or pressure;

[0028] "nose clip" means a mechanical device — other than a nose foam — which device is adapted for use on a mask body to improve the seal at least around a wearer's nose; "nose foam" means a foam-type material that is adapted for placement on the interior of a mask body to improve fit and / or wearer comfort over the nose when the respirator is being worn by a person;

[0029] "nose region" means the portion that resides over a person's nose when the respirator is worn;

[0030] "panel" means a three-dimensional part or portion that is substantially larger in first and second dimensions than in a third;

[0031] “perimeter" means the outer edge of the mask body, which outer edge would be disposed proximate to a wearer's face when the respirator is being donned by a person;

[0032] "polymer" means a material that contains repeating chemical units, regularly or irregularly arranged;

[0033] "polymeric" and "plastic" each mean a material that mainly includes one or more polymers and may contain other ingredients as well “polymer" means a material that contains repeating chemical units, regularly or irregularly arranged;

[0034] "respirator" means a device that is worn by a person to filter air before the air enters the wearer's respiratory system; specifically, respirators described herein have a filtering efficiency that meets one or more international standards for filtering efficiency, such as N95, N99, P95, P99, KN95 or other applicable standards from United States agencies or other jurisdictions;

[0035] "upper panel" means the panel that extends over the nose region and under the wearer's eyes when the respirator is worn; and

[0036] "upper segment" means the part of the perimeter that extends over the nose region and under the wearer's eyes when the respirator is being worn.

[0037] FIGS. 1A-1D illustrate views of respirators in accordance with embodiments herein. FIGS. 1A- 1D illustrate embodiments where a respirator is a flat-fold respirator. Flat-fold respirators are not fully formed into their desired cup-shaped configuration for being worn by a person over the nose and mouth. Rather, the mask body is opened into the cup-shaped or open configuration from a folded condition. However, it is expressly contemplated that embodiments herein may be applicable to other respirator designs. For example, filter media herein may be used in the formation of horizontal flat fold respirators, vertical fold respirators, cup-shaped respirators, duck-bill shaped respirators and / or pleated media respirators.

[0038] The illustrated flat-fold respirator 10 can provide the wearer with a source of clean air to breath. The respirator 10 includes a mask body 12 and a harness 14 where the mask body 12 has a plurality of panels, including an upper panel 16, a central panel 18, and a lower panel 20. The mask body 12 has a periphery that includes a perimeter 22, particularly a face -contacting perimeter, that would be located next to the wearer's face when the mask is being worn. A graspable tab extends from the regular periphery, particularly the regular perimeter. In the illustrated embodiment, the tab extends centrally from the lower panel 20. To open the mask body into the ready-to-use configuration shown in FIGS. 1C-1D, the user pulls on the tab 21 in a direction away from an adjoining or opposing panel.

[0039] FIGS. 1C-1D show the mask body in an open configuration, ready for placement on a person's face. When a person is not wearing the respirator 10, it may be folded flat for storage as shown in FIGS. 1A-1B. As illustrated in FIGS. 1A-1D, the central panel 18 is separated from the upper panel 16 and the lower panel 20 by first and second lines of demarcation 24 and 26. The upper and lower panels 16 and 20 may each be folded inward towards the backside or inner surface 28 of the central panel 18 when the mask is being folded flat for storage (FIGS. 1A-1B) and may be opened outward for placement on a wearer's face (FIGS. 1C-1D). When the mask body 12 is taken from its open configuration to its closed configuration or vice versa, the upper and lower panels 16 and 20, respectively, rotate about the first and second lines of demarcation 24 and 26. In this sense, the first and second lines of demarcation 24 and 26 act as first and second hinges or axis, respectively, for the upper and lower panels 16 and 20. The tab thus assists the user in pulling the panel 20 from its folded condition to open the mask body into an open, ready-to-use (or in- use) configuration.

[0040] The respirator 10 also may be provided with first and second side tabs or flanges 30 and 32 that provide a region for securement of the harness 14 that may include straps or elastic bands 34. The straps or bands 34 are stapled 35 to the mask body 12 at each opposing side to hold the mask body 12 against the face of the wearer when the mask is being worn. U.S. Patent D449,377 to Henderson et al. shows an example of tabs or flanges that can be used as strap securement regions. The harness also could be secured to the mask body by adhering, gluing, welding, etc. An example of a compression element that could be used to fasten a harness to a mask body using ultrasonic welding is described in U.S. Patents 6,729,332 and 6,705,317 to Castiglione. The band also could be welded directly to the mask body without using a separate attachment element — see U.S. Patent 6,332,465 to Xue et al. Examples of harnesses that could possibly be used in conjunction with the present invention are described in U.S. Patents 5,394,568 to Brostrom et al. and 5,237,986 to Seppala et al. and in EP 608684A to Brostrom et al. The upper panel 16 can have its structure altered to increase resistance to air flow to help prevent the fogging of protective eyewear, for example as taught in U.S. Patent No. 9770611 titled “Maintenance-Free Anti-Fog Respirator,” which is hereby incorporated by reference.

[0041] The upper panel 16 of mask body 12 also may include a nose clip 36 that is made from a malleable strip of metal such as aluminum, which can be conformed by mere finger pressure to adapt the respirator to the configuration of the wearer's face in the nose region. An example of a suitable nose clip is shown and described in U.S. Patents 5,558,089 and Des. 412,573 to Castiglione. Other examples are shown in US Patent 8,171,933 and US Patent Publication 2007 / 0068529.

[0042] FIG. ID particularly shows that the respirator 10 also may include a nose foam 38 that is disposed inwardly along the inside perimeter of the upper panel 16. The foam also could extend around the whole perimeter of the mask body and could include a thermochromic fit-indicating material that contacts the wearer's face when the mask is worn. Heat from the facial contact causes the thermochromic material to change color to allow the wearer to determine if a proper fit has been established — see U.S. Patent 5,617,749 to Springett et al. Examples of suitable nose foams are shown in US Patent Application Publication Nos. US2008 / 0099022 and US2008 / 0023006. The perimeter of the mask body can be sculpted along the upper panel 16 to improve compatibility of fit with protective eyewear, for example as taught in U.S. Patent No. 10,827,787 titled “Maintenance-Free Respirator That Has Concave Portions on Opposing Sides Of Mask Top Section,” which is hereby incorporated by reference.

[0043] FIG. 2 illustrates a conventional respirator construction. Conventional respirators are often formed of multiple layers of the same or different materials. For example, a respirator may be formed of a smooth inner layer 110 to avoid irritation of a user’s face, one or more filter layers 120 designed to filter out particulates, aerosols and / or gaseous contaminants, a stiffening layer 130 selected to maintain a 3D shape of a respirator (e.g. as illustrated in FIGS. 1C and ID) while in use, and a cover layer 140 to entrap loose fibers or for aesthetic reasons. In some cases, some of these layers include melt-blown nonwoven media. In some cases, some layers are spunbond layers. In many cases, the composition of the different layers differ - being made in different ways from different starting materials. The different layers must also be joined together, for example using adhesive bonding and / or ultrasonic welding.

[0044] Combining a number of layers together to form a disposable respirator requires additional mechanical steps, takes more material, and increases cost of a resulting product. However, each of the different types of layers 110-140 provides a different functional or aesthetic purpose. Inner layer 110 is often a smooth melt-blown web. The filtration layer(s) 120 may be electret melt-blown webs that provide the filtration properties. A stiffening layer may be a stiff spun-bond web that provides rigidity, and the outer cover layer may be a light weight spun-bond web that provides strength and protection.

[0045] A single layer of respirator material is desired that can provide the different functionality of layers 110-140. The single layer of respirator material may have a consistent composition throughout its volume. The single layer of respirator material may be made using melt-blown techniques, spunbond techniques, or a hybrid of the two methods.

[0046] A single layer of respirator material should meet a number of requirements that are normally provided through multiple different sheets of media. The single layer of respirator material must have sufficient tear strength. The single layer of respirator material must be sufficiently stiff such that, as a user breathes through the respirator, the general shape illustrated in FIG. ID is maintained, e.g. the respirator does not experience significant collapse. Traditionally, a respirator has required a stiffening material layer in addition to a filter media. For example, U.S. Pat. 6,123,077 describes a multilayer construction that incorporates a stiffener web in addition to a filter layer.

[0047] The single layer of respirator material must also have a satisfactory filtration efficiency. For example, the single layer of respiratory material may satisfy one or more NIOSH Particulate Filtering Respirator Classifications such as the N95, N99, N100, R95, R99, R100, P95, P99 and / or P100. The single layer of respirator media may also satisfy respirator requirements for FFP1, FFP2 and / or FFP3 EN 149 standard. The single layer of respiratory media may also satisfy the Chinese KN95 standard. Respirators made using media described herein may also satisfy other filtration efficiency tests from other regulatory bodies or jurisdictions.

[0048] The same media that satisfies the filtration efficiency should also have a smooth surface for contact against the face of a user, in order to reduce irritation. The media should also be a non-fuzzing material. Fuzzing may be measured using Taber abrasion testing, for example. Respirators in accordance with embodiments herein are formed of a single sheet of fdter media that has a high fdtration efficiency, a high stiffness, a high tear strength, while also having a low or non-fuzzing surface.

[0049] Some respirators have been formed having a single layer of material, such as that described in U.S. Pat. 9,770,058 to Angadijivand. However, respirators in accordance with embodiments herein are formed of a significantly lighter nonwoven web having a basis weight of around 100 gsm. Using melt-blown techniques, it has been difficult to achieve a light-weight web with a sufficient tear strength. Spun-bond techniques can produce a nonwoven web with a high tear strength, but there is difficulty in obtaining fibers with low effective diameters needed for good filtration efficiency at low basis weights.

[0050] Respirator filter media described in embodiments herein meet the filtration, stiffness and tear strength requirements using a single layer of a relatively low basis weight nonwoven web.

[0051] Some advantages of a single layer construction over a multilayer construction may include, but are not limited to, reduced cost due to simpler construction and fewer material needs. A single layer construction may also be lighter weight, allowing for a respirator construction to have a reduced pressure drop compared to multilayer constructions, allowing for easier breathability and greater comfort while worn.

[0052] A single layer construction may also be a more sustainable option, requiring less material, due to the reduced basis weight, and a reduced amount of resin in its construction. In some embodiments herein, a flat-fold respirator is formed from less than 8 grams of material, or even less than 7 grams of material, or even less than 6 grams of material. A conventional 5-layer five-fold respirator may have a corresponding weight of about 9-10 grams.

[0053] Additionally, when compared to a conventional multi-layer media respirator, a single layer media respirator may provide lower thermal resistance and enable better moisture transmission rate so the wear feels more comfortable.

[0054] Respirators in accordance with embodiments herein are formed of a single layer of filter media. The filter media is a unitary structure having a homogenous composition throughout its volume. The filter media, in accordance with embodiments herein, has a substantially flat surface. The filter media in embodiments herein is formed of fibers having a monomodal distribution. Some previous respirator designs, such as those described in U.S. Pat. 9,770,058 issued September 26, 2017, and U.S. Pat. 10,575,571, issued March 3, 2020, describe a construction that uses a bimodal fiber distribution.

[0055] FIG. 3 illustrates a method of forming a respirator in accordance with embodiments herein. FIGS. 1A-D illustrate one style of respirator which may be formed using respirator media described herein. However, it is expressly contemplated that other respirator designs may also benefit from media described herein.

[0056] At block 310, material is obtained for forming a nonwoven web. The material may, in some embodiments, include polypropylene.

[0057] At block 320, a nonwoven web is formed. The formed nonwoven web may have a basis weight of at least about 60 gsm. In some embodiments, the formed nonwoven web has a basis weight of less than about 150 gsm. In some embodiments, the formed nonwoven web has a basis weight between about 80 gsm and about 120 gsm, or between about 90 gsm and about 110 gsm.

[0058] The formed nonwoven web may have a thickness between about 25 mils and about 50 mils. The formed nonwoven web may have a solidity of at least about 9%. The formed nonwoven web may have a solidity of less than about 15%. The formed nonwoven web may include fibers having an effective fiber diameter of at least about 8 pm. The formed nonwoven web may include fibers having an effective fiber diameter of less than about 15 pm. The formed nonwoven web may have a Gurley stiffness of at least about 350 mg. The formed nonwoven web may have a Gurley stiffness of less than about 500 mg.

[0059] The nonwoven webs of the present disclosure can be made by wet laid, carded, air laid, spunlaced, spunbonding, spunmelt, or melt-blowing techniques or combinations thereof.

[0060] Melt-blown microfibers useful in the present disclosure can be prepared as described in Van A. Wente, “Superfine Thermoplastic Fibers,” Industrial Engineering Chemistry, vol. 48, pp. 1342-1346 and in Report No. 4364 of the Naval Research Laboratories, published May 25, 1954, entitled “Manufacture of Super Fine Organic Fibers” by Van A. Wente et al.

[0061] Spunbond microfibers may be formed using a spunbond process in which one or more continuous polymeric free-fibers are extruded onto a collector, as described, for example, in U.S. Pat. Nos. 4,340,563 and 8,162,153 and US Patent Publication No. 2008 / 0038976.

[0062] In some embodiments herein, the web is formed using a hybrid process that combines one or more of wet laid, carded, air laid, spunlaced, spunbonding, spunmelt, or melt-blowing techniques.

[0063] Forming a web may also include a calendaring step. Calendaring may include application of heat and / or high pressure to weld fibers within the single layer of respirator media.

[0064] In accordance with embodiments herein, a disposable respirator is formed from a single layer of filter media that at least meets the N95 standard of filtration efficacy. The respirator is formed of one or more panels. Each panel is formed of media that has a uniform composition across the surface of the one or more panels.

[0065] In some embodiments herein, the single layer respirator is a flat fold respirator having two or more panels, each panel being formed of a single layer of nonwoven material that at least meets the N95 standard set by NIOSH.

[0066] In some embodiments herein, the single layer of filter media is formed of a material having a basis weight of at least about 60 gsm. In some embodiments herein, the single layer of filter media has a basis weight of less than about 150 gsm. In some embodiments herein, the single layer of filter media has a basis weight between about 100 gsm and about 120 gsm.

[0067] In some embodiments herein, the respirator, when completely assembled with a harness, has a weight of less than 8 grams. The total weight of the assembled respirator may be less than 7 grams. The total weight of the assembled respirator may even be less than 6.5 grams. The total weight of the assembled respirator may even be less than 6 grams. In some embodiments herein the single layer of nonwoven filter media has a thickness of at least about 25 mils (0.64 mm). In some embodiments, herein the single layer of nonwoven filter media has a thickness of less than about 50 mils (1.3 mm).

[0068] In some embodiments herein the single layer of nonwoven filter media has a solidity of at least about 9 %. In some embodiments herein the single layer of nonwoven filter media has a solidity of less than about 15 %. In some embodiments herein the single layer of nonwoven filter media has a solidity of less than about 12 %. In some embodiments herein the single layer of nonwoven filter media has a solidity of about 10 %. In some embodiments herein the single layer of nonwoven filter media has a solidity of about 11 %. In some embodiments herein the single single layer of nonwoven filter media has a solidity of about 12%.

[0069] In some embodiments herein the single layer of nonwoven filter media has an effective fiber diameter of at least about 8 pm. In some embodiments the single layer of nonwoven filter media has an effective fiber diameter of less than about 15 pm. In some embodiments the single layer of nonwoven filter media has an effective fiber diameter of less than about 12 pm. In some embodiments the single layer of nonwoven filter media has an effective fiber diameter of less than about 10 pm.

[0070] In some embodiments herein the single layer of nonwoven filter media has a Gurley stiffness of at least about 350 mg. In some embodiments herein the layer of nonwoven filter media has a Gurley stiffness of less than about 550 mg.

[0071] In some embodiments herein the flat-fold disposable respirator experiences a pressure drop of at least about 7 mm H2O. In some embodiments herein the flat-fold disposable respirator experiences a pressure drop of less than about 12.5 mm H2O. In some embodiments herein the flat-fold disposable respirator experiences a pressure drop of less than about 10 mm H2O.

[0072] In some embodiments herein the single layer of nonwoven filter media has a tensile strength of at least 750 g when measured in a cross-web direction. In some embodiments herein the single layer of nonwoven filter media has a tensile strength of at least 750 g when measured in a machine direction.

[0073] In some embodiments herein the single layer of nonwoven filter media is composed of a nonfuzzing, or substantially non-fuzzing material.

[0074] Respirators made in accordance with embodiments herein may be capable of filtering, at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. Respirators made in accordance with embodiments herein may be capable of filtering, at least 99% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. Respirators made in accordance with embodiments herein may be capable of filtering, at least 99.9% of airborne particles with a mass median aerodynamic diameter of 0.3 pm.

[0075] Respirators made in accordance with embodiments herein may be more comfortable for a wearer than a corresponding multilayer respirator construction. For example, a single layer of filter media will have a lower thermal resistance than a corresponding multi-layer web construction. Similarly, a single layer web construction will have a higher moisture vapor transfer rate than a corresponding multi-layer web construction. This may allow for a breathing space of a wearer (between the respirator interior and the user’s face) to retain less heat and moisture. Respirator material in embodiments herein may be suitable for particle capture or gas and vapor type and / or may be a barrier layer that prevents the transfer of liquid from one side of the filter layer to another to prevent, for instance, liquid aerosols or liquid splashes from penetrating the filter layer. Respirator media described in embodiments herein generally has a low pressure drop (for example, less than about 20 to 30 mm H2O at a face velocity of 13.8 centimeters per second) to minimize the breathing work of the mask wearer. Respirator media in embodiments herein are both flexible and have sufficient shear strength so that they generally maintain their structure under expected use conditions. The formed nonwoven web may include one or more webs of fine inorganic fibers (such as fiberglass) or polymeric synthetic fibers. Synthetic fiber webs may include electret charged polymeric microfibers that are produced from processes such as melt blowing. Polyolefin microfibers formed from polypropylene that are electret charged may provide particular utility for particulate capture applications.

[0076] The respirator media may come in a variety of shapes and forms. It typically has a thickness of about 0.2 millimeters (mm) to 1 centimeter (cm), more typically about 0.3 millimeters to 0.5 cm, and it could be a planar web, or it could be a corrugated web that has an expanded surface area relative to the shaping layer — see, for example, U.S. Patents 5,804,295 and 5,656,368 to Braun et al.

[0077] Respirator media herein include charged media. Webs of melt-blown fibers, such as taught in Wente, Van A., Superfine Thermoplastic Fibers, 48 Indus. Engn. Chem., 1342 et seq. (1956), especially when in a persistent electrically charged (electret) form are especially useful (see, for example, U.S. Pat. No. 4,215,682 to Kubik et al.). These melt-blown fibers may be microfibers that have an effective fiber diameter less than about 20 micrometers (pm), typically about 1 to 12 pm. Particularly preferred are melt- blown webs that contain fibers formed from polypropylene, poly(4-methyl-l -pentene), and combinations thereof. Electrically charged fibrillated-film fibers as taught in van Turnhout, U.S. Patent Re. 31,285, may also be suitable, as well as rosin-wool fibrous webs and webs of glass fibers or solution-blown, or electrostatically sprayed fibers, especially in microfilm form. Electric charge can be imparted to the fibers by contacting the fibers with water as disclosed in U.S. Patents 6,824,718 to Eitzman et al., 6,783,574 to Angadjivand et al., 6,743,464 to Insley et al., 6,454,986 and 6,406,657 to Eitzman et al., and 6,375,886 and 5,496,507 to Angadjivand et al. Electric charge also may be impacted to the fibers by corona charging as disclosed in U.S. Patent 4,588,537 to Klasse et al. or by turbocharging as disclosed in U.S. Patent 4,798,850 to Brown. Also, additives can be included in the fibers to enhance the filtration performance of webs produced through the hydro-charging process (see U.S. Patent 5,908,598 to Rousseau et al.). Fluorine atoms, in particular, can be disposed at the surface of the fibers in the filter layer to improve filtration performance in an oily mist environment — see U.S. Patents 6,398,847 Bl, 6,397,458 Bl, and 6,409,806 Bl to Jones et al. Typical basis weights for melt-blown, electret filtration layers are about 15 to 100 grams per square meter. When electrically charged according to techniques described in, for example, the '507 patent the basis weight may be about 20 to 40 g / m2and about 10 to 30 g / m2, respectively.

[0078] At block 330, a respirator is formed from the media. Forming a respirator may include forming and coupling multiple panels together - e.g. a top, center, and bottom panel of a respirator illustrated in FIGS. 1A-1D. Where different panels need to be coupled, the coupling may be done using welding, adhesive, stapling or another coupling mechanism that substantially forms and maintains a seal between the panels such that air is forced through the filter media during use.

[0079] Forming a respirator may also include a shaping step, for example to form a cup-shaped respirator. However, it is expressly contemplated that media described herein may be used to form a number of respirator styles including vertical flat fold styles 334, horizontal flat fold styles 332, or other styles 336.

[0080] Media described herein may be suitable for forming a pleated style respirator (for example, available from 3M Company under the trade name VFLEX®), for example such as that illustrated in US Pat. No. 8,640,704, FIGS. 1-4 and column 4, line 25 - column 5, line 29, incorporated herein by reference. Pleated style respirators are foldable along a centerline, having a mask body that has a transversely extending line of demarcation with a longitudinal axis. One or more weld patterns may be disposed above and not traversing the line of demarcation. The one or more weld patterns may be disposed on each side of the longitudinal axis. In some embodiments, an additional one or more weld patterns are disposed below, and not crossing, the line of demarcation on each side of the longitudinal axis. Any, all, or a subset of welds are a two-dimensional enclosed pattern. Weld patterns for a pleated respirator may have a truss-type geometry, one or more triangles, with either sharp or rounded comers. Weld patterns may have other shapes as well. Weld pattern shapes may be present in multiple size, multiple orientations, or both. Shapes may overlap, share edges or comers, or be nested within each other, in some embodiments.

[0081] Respirator media described herein may be suitable for a “duck-billed” style respirator, such as that described in U.S. Pat 5,322,061 to Bmnson. Such as respirator can be characterized as having a generally trapezoidal portion forming an upper half of the respirator, which contacts the wearer’s nose, as well as a generally trapezoidal portion forming a lower half of the respirator, which contact the wearer’s chin.

[0082] It is expressly contemplated that respiratory designs herein may also benefit from including wrinkled media, for example as described in US Provisional Applications 63 / 496002, filed April 13, 2023, and 63 / 607197, filed December 7, 2023, both of which are incorporated by reference herein. For example, wrinkled media may be used for a face seal and / or headband. Additionally, wrinkled media may be used for one or more of the panels in a multi-panel constmction. For example, for the respirator design of FIGS. 1A-1D, wrinkled media may be used for a lower panel.

[0083] Forming a respirator may also include adding peripherals such as straps, nose foams, nose clips and / or a harness to the body of the respirator.

[0084] In some embodiments, respirators herein include anti-fog properties in their upper and lower panels. Examples of such anti-fog layers are taught in U.S. Patent No. 9,770,611 titled, “Maintenance-Free Respirator,” which is hereby incorporated by reference.

[0085] The respirator also may include an optional exhalation valve that allows for the easy exhalation of air by the user. Exhalation valves that exhibit an extraordinarily low pressure drop during an exhalation are described in U.S. Patents 7,188,622, 7,028,689, and 7,013,895 to Martin et al.; 7,117,868, 6,854,463, 6,843,248, and 5,325,892 to Japuntich et al.; and 6,883,518 to Mittelstadt et al. The exhalation valve may be secured to the central panel, preferably near the middle of the central panel, by a variety of means including sonic welds, adhesion bonding, mechanical clamping, and the like — see, for example, U.S. Patents 7,069,931, 7,007,695, 6,959,709, and 6,604,524 to Curran et al and EPl, 030, 721 to Williams et al.

[0086] Flat-fold, maintenance-free respirators of the present invention can be manufactured according to the process described in U.S. Patents 6,123,077, 6,484,722, 6,536,434, 6,568,392, 6,715,489, 6,722,366, 6,886,563, 7,069,930, and US Patent Publication No. US2006 / 0180152A1 and EP0814871B1 to Bostock et al. The respirator manufacturing process would include a supply of precut material for the stiffening layers which would be incorporated between the other webs of material forming the respirator. The stiffening layers could be held in place between the layers and between certain weld lines.

[0087] At block 340, additional processing may be done. For example, the respirator may be packaged and / or text may be printed onto a surface of the respirator.

[0088] A disposable, flat-fold respirator is presented that includes a mask body that includes a plurality of panels which may fold in towards each other and may unfold into an open configuration. The mask body includes a single layer of charged filter material. The plurality of panels includes an upper panel, a lower panel, and a central panel. The central panel is connected to the upper panel and lower panel. The respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. A harness is secured to the mask body.

[0089] The respirator may be implemented such that the charged filter material includes a uniform composition across a material surface.

[0090] The respirator may be implemented such that the charged filter material includes a uniform composition throughout a material depth.

[0091] The respirator may be implemented such that the respirator, in the open configuration, is configured to maintain a mask body shape during use.

[0092] The respirator may be implemented such that the charged filter material includes a basis weight of at least about 60 gsm. The respirator may be implemented such that the charged filter media includes a basis weight of less than about 150 gsm. The respirator may be implemented such that the charged filter media includes a basis weight between about 80 gsm and about 120 gsm.

[0093] The respirator may be implemented such that the charged filter media includes a web thickness of between 25-50 mils.

[0094] The respirator may be implemented such that the charged filter media has a stiffness of at least about 350 mg. The respirator may be implemented such that the charged filter media has a stiffness of less than about 450 mg. The respirator may be implemented such that the charged filter media has a stiffness of less than about 500 mg.

[0095] The respirator may be implemented such that the charged filter media has a solidity of at least about 9%. The respirator may be implemented such that the charged filter media has a solidity of at least about 11%. The respirator may be implemented such that the charged filter media has a solidity of less than about 12%. The respirator may be implemented such that the charged filter media has a solidity of less than about 15%. The respirator may be implemented such that the charged filter media has an average flow resistance at 85 liters per minute of at least about 7 mm H2O. The respirator may be implemented such that the charged filter media has an average flow resistance at 85 liters per minute of less than about 12.5 mm H2O.

[0096] The respirator may be implemented such that the charged filter media includes calendared charged filter media.

[0097] The respirator may be implemented such that the charged filter media includes polypropylene.

[0098] The respirator may be implemented such that the respirator includes a harness, and wherein the has a total weight of less than 8 grams. The respirator may be implemented such that the respirator includes a harness, and wherein the has a total weight of less than 7 grams. The respirator may be implemented such that the respirator includes a harness, and wherein the has a total weight of less than 6.5 grams. The respirator may be implemented such that the respirator includes a harness, and wherein the has a total weight of less than 6 grams.

[0099] The respirator may be implemented such that the single layer of charged filter media includes fibers having an effective fiber diameter of at least about 8 pm. The respirator may be implemented such that the single layer of charged filter media includes fibers having an effective fiber diameter of less than about 15 pm. The respirator may be implemented such that the single layer of charged filter media includes fibers having an effective fiber diameter of less than about 12 pm. The respirator may be implemented such that the single layer of charged filter media includes fibers having an effective fiber diameter of less than about 10 pm.

[0100] The respirator may be implemented such that a tensile strength of the single layer of charged filter media is at least 750 g in a cross-web direction. The respirator may be implemented such that a tensile strength of the single layer of charged filter media is at least 750 g in a machine direction.

[0101] The respirator may be implemented such that the respirator includes a non-fuzzing surface.

[0102] The respirator may be implemented such that the upper panel and lower panel are configured to fold in towards the central panel to put the respirator into a closed configuration, and wherein the upper panel and lower panel are configured to unfold away from the central panel to put the respirator into an open configuration.

[0103] The respirator may also including a valve, a nose clip, or a nose foam.

[0104] The respirator may be implemented such that the respirator filters at least 99% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. The respirator may be implemented such that the respirator filters at least 99.9% of airborne particles with a mass median aerodynamic diameter of 0.3 pm.

[0105] A disposable respirator is presented that includes a mask body having an interior surface and an exterior surface. The mask body is configured such that the interior surface receives an exhaled breath of a user, and wherein the exterior surface is exposed to ambient air. The mask body includes a single layer of filter media, wherein the single layer of filter media includes the interior surface separated from the exterior surface by a thickness. The respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. The disposable respirator may be implemented such that the single layer of fdter media has a uniform composition across the exterior surface.

[0106] The disposable respirator may be implemented such that the single layer of fdter media has a uniform composition through the thickness.

[0107] The disposable respirator may be implemented such that the charged fdter material includes a basis weight of at least about 60 gsm. The disposable respirator may be implemented such that the charged fdter media includes a basis weight of less than about 150 gsm. The disposable respirator may be implemented such that the charged fdter media includes a basis weight between about 80 gsm and about 120 gsm.

[0108] The disposable respirator may be implemented such that the charged fdter media includes a web thickness of between 25-50 mils.

[0109] The disposable respirator may be implemented such that the charged fdter media has a stiffness of at least about 350 mg. The disposable respirator may be implemented such that the charged fdter media has a stiffness of less than about 450 mg. The disposable respirator may be implemented such that the charged fdter media has a stiffness of less than about 500 mg.

[0110] The disposable respirator may be implemented such that the charged fdter media has a solidity of at least about 9%. The disposable respirator may be implemented such that the charged fdter media has a solidity of at least about 11%. The disposable respirator may be implemented such that the charged fdter media has a solidity of less than about 12%. The disposable respirator may be implemented such that the charged fdter media has a solidity of less than about 15%.

[0111] The disposable respirator may be implemented such that the charged fdter media has an average flow resistance at 85 liters per minute of at least about 7 mm H2O. The disposable respirator may be implemented such that the charged fdter media has an average flow resistance at 85 liters per minute of less than about 12.5 mm H2O. The disposable respirator may be implemented such that the charged fdter media includes calendared charged fdter media.

[0112] The disposable respirator may be implemented such that the charged fdter media includes polypropylene.

[0113] The disposable respirator may be implemented such that the disposable respirator includes a harness, and wherein the has a total weight of less than 8 grams. The disposable respirator may be implemented such that the disposable respirator includes a harness, and wherein the has a total weight of less than 7 grams. The disposable respirator may be implemented such that the disposable respirator includes a harness, and wherein the has a total weight of less than 6.5 grams. The disposable respirator may be implemented such that the disposable respirator includes a harness, and wherein the has a total weight of less than 6 grams.

[0114] The disposable respirator may be implemented such that the single layer of charged fdter media includes fibers having an effective fiber diameter of at least about 8 pm. The disposable respirator may be implemented such that the single layer of charged fdter media includes fibers having an effective fiber diameter of less than about 15 pm. The disposable respirator may be implemented such that the single layer of charged fdter media includes fibers having an effective fiber diameter of less than about 12 pm. The disposable respirator may be implemented such that the single layer of charged fdter media includes fibers having an effective fiber diameter of less than about 10 pm.

[0115] The disposable respirator may be implemented such that a tensile strength of the single layer of charged filter media is at least 750 g in a cross-web direction.

[0116] The disposable respirator may be implemented such that a tensile strength of the single layer of charged filter media is at least 750 g in a machine direction.

[0117] The disposable respirator may be implemented such that the disposable respirator includes a nonfuzzing surface.

[0118] The disposable respirator may be implemented such that the mask body that includes a plurality of panels which may fold in towards each other and may unfold into an open configuration, wherein the mask body, wherein each of the plurality of panels includes the single layer of charged filter media.

[0119] The disposable respirator may be implemented such that the plurality of panels includes an upper panel, a lower panel, and a central panel, wherein the central panel is connected to the upper panel and lower panel.

[0120] The disposable respirator of claim 1 and further including a valve, a nose clip, or a nose foam.

[0121] The disposable respirator may be implemented such that the disposable respirator filters at least 99% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. The disposable respirator may be implemented such that the disposable respirator filters at least 99.9% of airborne particles with a mass median aerodynamic diameter of 0.3 pm.

[0122] The disposable respirator may be implemented such that the disposable respirator is a horizontal flat-fold style respirator.

[0123] The disposable respirator may be implemented such that the disposable respirator is a cup-shape style respirator, and wherein the cup-shape respirator includes a shell.

[0124] The disposable respirator may be implemented such that the disposable respirator is a vertical-fold style respirator.

[0125] The disposable respirator may be implemented such that the disposable respirator is a pleated style respirator.

[0126] The disposable respirator may be implemented such that the disposable respirator is a duck bill style respirator.

[0127] A method of forming a disposable respirator is presented that includes forming a nonwoven web and forming a mask body for the disposable respirator from the nonwoven web. The nonwoven web has a uniform composition, the uniform composition at least partially defined as having a basis weight of at least about 60 gsm and less than about 150 gsm, a Gurley stiffness of at least about 350 mg, and a solidity of at least about 9%. The mask body is formed of a single layer of the nonwoven web such that the single layer of the nonwoven web includes both an exterior surface and an interior surface of the disposable respirator. The disposable respirator has an airflow resistance of less than 12.5 mmfTO. and wherein the disposable respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. The method may be implemented such that forming the mask body includes welding the nonwoven web.

[0128] The method may be implemented such that forming the mask body includes applying staples to the nonwoven web.

[0129] The method may be implemented such that forming the bask body includes applying a valve to the mask body.

[0130] The method may be implemented such that forming the mask body includes applying a harness to the mask body.

[0131] The method may be implemented such that forming the nonwoven web includes calendaring the nonwoven web.

[0132] The method may be implemented such that forming the mask body includes forming a plurality of panels, each panel including the single layer of the nonwoven web.

[0133] The method may be implemented such that forming the mask body includes coupling the plurality of panels together to form a shape of the mask body.

[0134] The method may be implemented such that the nonwoven web has a basis weight of at least about 80 gsm.and less than about 120 gsm.

[0135] The method may be implemented such that the nonwoven web has a thickness of at least about 25 mils. The method may be implemented such that the nonwoven web has a thickness of less than about 50 mils.

[0136] The method may be implemented such that the nonwoven web is formed of fibers having an effective fiber diameter of less than about 15 pm . The method may be implemented such that the nonwoven web is formed of fibers having an effective fiber diameter of at least about 8 pm. The method may be implemented such that the nonwoven web is formed of fibers having an effective fiber diameter of less than about 12 pm. The method may be implemented such that the nonwoven web is formed of fibers having an effective fiber diameter of less than about 10 pm. The method may be implemented such that the disposable respirator exhibits an airflow resistance of less than about 12.5 mm H2O. The method may be implemented such that the disposable respirator exhibits an airflow resistance of at least about 7 mm H2O.

[0137] The method may be implemented such that the disposable respirator has a total weight of less than about 8 grams. The method may be implemented such that the disposable respirator has a total weight of less than about 7 grams. The method may be implemented such that the disposable respirator has a total weight of less than about 6.5 grams.

[0138] The method may be implemented such that the nonwoven web has a crossweb tensile strength of at least 750 g.

[0139] The method may be implemented such that the nonwoven web has a machine direction tensile strength of at least 750 g.

[0140] The method may be implemented such that the nonwoven web has a Gurley stiffness of less than about 500 mg.

[0141] The method may be implemented such that the nonwoven web is a non-fuzzing nonwoven web. The method may be implemented such that the disposable respirator filters at least 99% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. The method may be implemented such that the disposable respirator fdters at least 99.5% of airborne particles with a mass median aerodynamic diameter of 0.3 pm.

[0142] The method may be implemented such that forming the nonwoven web includes a spun bond technique, a melt blown technique and / or a combination thereof.

[0143] A nonwoven respirator fdter media is presented that includes a basis weight of between about 60 gsm and about 150 gsm, a solidity of between about 9% and about 15%, a plurality of fibers having an effective fiber diameter of between about 8 pm and about 15 pm, a Gurley stiffness of between about 350 mg and about 500 mg, and a tensile strength of at least 750 g in a crossweb direction or a machine direction.

[0144] The nonwoven respirator filter media may be implemented such that the respirator filter media is sufficiently stiff such that, when a single layer is formed into a mask body shape, it maintains the mask body shape during use without collapsing.

[0145] The nonwoven respirator filter media may be implemented such that the basis weight is between about 80 gsm and about 120 gsm.

[0146] The nonwoven respirator filter media may be implemented such that the solidity is between about 9% and about 12%.

[0147] The nonwoven respirator filter media may be implemented such that the effective fiber diameter is between about 8 pm and about 10 pm.

[0148] The nonwoven respirator filter media may be implemented such that a tensile strength of the single layer of charged filter media is at least 750 g in a cross-web direction.

[0149] The nonwoven respirator filter media may be implemented such that a tensile strength of the single layer of charged filter media is at least 750 g in a machine direction.

[0150] The nonwoven respirator filter media may be implemented such that the respirator includes a nonfuzzing surface.

[0151] The nonwoven respirator filter media may be implemented such that the plurality of fibers include polypropylene.

[0152] The nonwoven respirator filter media may be implemented such that the plurality of fibers exhibit a quasi-permanent charge.

[0153] The nonwoven respirator filter media may be implemented such that the plurality of fibers include electret fibers.

[0154] The nonwoven respirator filter media may be implemented such that the nonwoven respirator filter media is a calendared nonwoven respirator filter media.

[0155] The nonwoven respirator filter media may be implemented such that the nonwoven respirator filter media includes a uniform composition.

[0156] Test Methods The following test methods were used to evaluate media and respirator examples. Unless otherwise noted, all initial DOP penetration and pressure drop tests of Example (EX) and Comparative Example (CE) webs were run at a face velocity of 13.8 cm / sec. The listed media web performance in Tables ## are actual measurements per Test Methods listed.

[0157] Effective Fiber Diameter (EFD)

[0158] Effective fiber diameter may be determined according to Davies, C. N., The Separation Of Airborne Dust Particles, Institution Of Mechanical Engineers, London, Proceedings IB, 1952.

[0159] Solidity

[0160] Solidity is a nonwoven web property inversely related to density and characteristic of web permeability and porosity (low Solidity corresponds to high permeability and high porosity), and is defined by Equation 1 below.

[0161] Equation 1

[0162] Pressure Drop

[0163] Pressure drop and percent penetration of media webs may be determined using a challenge containing NaCl or DOP (Dioctyl Phthalate) particles, delivered at a flow rate of 85 liters / min or LPM, and evaluated using a TSI™ Model 8130 high-speed automated filter tester (available from TSI Inc., Shoreview, Minnesota). An MKS pressure transducer (available from MKS Instruments, Andover, Massachusetts) may be employed to measure pressure drop (dP, mm H2O) through the filter media or filter samples.

[0164] DOP Penetration

[0165] For DOP testing, the aerosol may contain particles with a nominal diameter of about 0.185 pm at a target concentration of about 100 mg / m3, and the Automated Filter Tester may be operated with both the heater and particle neutralizer off. The initial DOP penetration and pressure drop tests last about 21 seconds.

[0166] The NaCl or DOP particles are forced through a media sample that has 11.4 cm in diameter or 102 cm2opening at a rate of 85 LPM.

[0167] The DOP or NaCl percent penetration is defined by Equation 2:

[0168] %Pen = (Concentration downstream / Concentration upstream) xlOO Equation 2

[0169] Tensile Strength

[0170] The webs can be tested for tensile strength. The methodology outlined in ASTM D5034 may be used. Examples of suitable testing conditions include web samples of 30 mm xl50 mm or 1 inch x 4 inch in size, mounted with 100 mm distance between the clamps, and under 300 mm / min or 500 mm / min pulling speed.

[0171] N95 respirators, intended to be worn by healthcare personnel in a healthcare setting to protect them from the transfer of large droplets, splashes, or sprays of bodily or other hazardous fluids, must meet the Class II devices regulation per FDA 21 CFR 878.4040 and must meet fluid resistance testing as per methodology outlined in ASTM F1862 standard, which simulates a high-velocity stream of synthetic blood corresponding to 80, 120 and 160 mmHg pressure in testing. A higher level rating is given to a higher pressure. For example, Level 1 indicates 80 mmHg resistance and Level 3 indicated 160 mmHg resistance. In some embodiments, respirators herein have level 1 or 2 or 3 fluid resistance ratings.

[0172] The measured values are presented in the Examples section.

[0173] Examples

[0174] In this example, the web properties of a single layer of the filter media used in this example to filter media commonly used for certified respirators were compared. Comparative Examples 1 - 5 represent a single filtering layers taken from different commercially available media that are suitable for use in a respirator with an N95, FFP2, or higher certification. It is noted that the respirators of Examples 1-5 are all commercially sold as a multi-layer respirator construction. The properties measured were EFD (effective fiber diameter), %solidity, basis weight in grams / square meter, and pressure drop in mmlLO.

[0175] Examples EX-1 through EX-4 were formed into flat-fold respirators and the %penetration for a DOP aerosol was tested, the results are also shown in Table 1.

[0176] The %penetration for a DOP aerosol at 85 1pm is also provide. The penetration data is an average of 5 replicates. x It is shown that the initial performance requirements for a certified respirator of type horizontal flat-fold can be achieved with a single layer of the filter media described herein.

[0177] Table 1 Example 2.

[0178] In this example, we have converted Ex-2 of the previous example into a flat-fold style respirator. This was done by first calendaring the web with a 17% calendar against a smooth roll. The resulting pressure drop was 9.7 mmH20 vs. 7.8 mmH20 in the previous example. The calendared web was charged and converted into a style that mimics a flat fold respirator. Using a test fixture designed for flat fold respirators, the single layer respirators were tested for salt loading using a TSI 8130 and compared to a flat fold respirator with construction similar to a 3M Aura™ 9205+ The relevant test data is provide in Table 2 and is an average of 5 replicates.

[0179] Table 2

[0180] Example 3.

[0181] Four commercially available respirators obtained from 3M Company, available under the trade designation Aura™ 9205+. The commercially available respirators were also weighed in sets of two, each with a standard PIP headband, and the results were averaged, resulting in an average weight of 9.03 g.

[0182] Four of the respirators of Examples 1 -6 were weighed in sets of two, each with a headband having an identical weight to the headband associated with the Aura™ 9205+, and the results were averaged, resulting in an average weight of 6.016 g.

[0183] Example 4.

[0184] In this example, the face fit performance of respirators made for Example 2, Ex-1 and CE-4 was assessed.

[0185] A face fit test was employed to determine the amount of leakage between a respirator user's face and the seal structure(s) of a tight-fitting respirator. The amount of face seal leakage between a respirator and a user's face was quantified by measuring the concentration of a test aerosol (e.g. NaCl particles suspended in air) on the inside and outside of a respirator. A useful face fit test has been developed, which selectively detects particles of 60 nanometers (nm) or smaller. See U.S. Pat. No. 6,125,845 to Halvorson et al. A commercially available instrument was used for the face fit testing - the TSI PortaCount® Pro+ (TSI Inc., Shoreview, Minnesota).

[0186] Thirteen samples each of Ex-1 and CE-4 were prepared for face fit testing on human subjects. A sample probe fixture (TSI Inc.) was attached to each sample so that the aerosol concentration inside the sample could be determined during the face fit test. Face fit tests were conducted in a large room. A NaCl aerosol was generated using a model 8026 Particle Generator (TSI Inc.). The atomizer was adjusted so that enough particles were available to obtain fit factors of at least 200.

[0187] For each fit test, the subjects donned the respirator and attached the respirator to the fit test system via a sample probe and a hose. The subject was then asked to perform eight exercises that are defined in US Code of Federal Regulations 29 CFR 1910. 134, Appendix A, Part I.A.14. During these exercises, particle concentration data was collected from the fit test system using a microcomputer. The data can be obtained without a microcomputer by running the fit test system in "Count mode" and recording the data manually from the fit test system readout. The specific exercises, their duration, and the data collection scheme are shown below in Table 3. The start and end times are measured in seconds (s) after the exercise begins.

[0188] Table 3

[0189] A fit factor was calculated for each exercise except Grimace. Fit Factor is equal to the chamber aerosol concentration divided by the internal respirator aerosol concentration. For each exercise, the chamber aerosol concentration used was the mean of the chamber concentrations measured immediately before and after the concentration inside the respirator. An average fit factor for each subject with each sample respirator was obtained by calculating the harmonic mean of the seven fit factors for the 1stNormal Breathing, Deep Breathing, Up and Down Head Movements, Side to Side Head Movement, Rainbow Message Reading, Bending at Waist, and 2ndNormal Breathing exercises. The harmonic mean can be obtained by computing the reciprocal of the arithmetic mean of the reciprocals of the individual exercise fit factors. The results of the face fit tests conducted using samples of CE-4 and EX-1 are shown below in

[0190] Table 4:

[0191] Table 4

[0192] The fit factor for eight of the thirteen subjects was significantly higher for inventive Ex-1 when compared to CE-4, showing a significant reduction in face seal leakage. In one subject (Subject 2), the fit factors were found to be essentially equivalent between CE-4 and Ex-1. Four of the thirteen tested (Subjects 4, 7, 10, and 12) had a lower fit factor with Ex-1 than with CE-4.

[0193] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document mentioned or incorporated by reference herein, this specification as written will prevail.

[0194] In some embodiments, a disposable flat-fold respirator includes a mask body with a plurality of panels that may fold in towards each other and unfold into an open configuration. The mask body includes a single layer of charged filter material. The plurality of panels includes an upper panel, a lower panel, and a central panel, with the central panel connected to the upper panel and lower panel. The respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. A harness is secured to the mask body. The charged filter material may have a uniform composition across a material surface and throughout a material depth. The respirator, in the open configuration, may be configured to maintain a mask body shape during use. The charged filter material may have a basis weight of at least about 60 gsm, less than about 150 gsm, or between about 80 gsm and about 120 gsm. The charged filter media may have a web thickness of between 25-50 mils, a stiffness of at least about 350 mg, less than about 450 mg, or less than about 500 mg, and a solidity of at least about 9%, at least about 11%, less than about 12%, or less than about 15%. The charged filter media may have an average flow resistance at 85 liters per minute of at least about 7 mm H20 or less than about 12.5 mm H20. The charged filter media may include calendared charged filter media and polypropylene. The respirator may include a harness and may have a total weight of less than 8 grams, less than 7 grams, less than 6.5 grams, or less than 6 grams. The single layer of charged filter media may include fibers having an effective fiber diameter of at least about 8 pm, less than about 15 pm, less than about 12 pm, or less than about 10 pm. A tensile strength of the single layer of charged filter media may be at least 750 g in a cross-web direction or in a machine direction. The respirator may include a non-fuzzing surface. The upper panel and lower panel may be configured to fold in towards the central panel to put the respirator into a closed configuration and unfold away from the central panel to put the respirator into an open configuration. The respirator may further include a valve, a nose clip, or a nose foam. The respirator may filter at least 99% or at least 99.9% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. A disposable respirator includes a mask body having an interior surface and an exterior surface, with the interior surface receiving an exhaled breath of a user and the exterior surface exposed to ambient air. The mask body includes a single layer of filter media, with the interior surface separated from the exterior surface by a thickness. The respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. The single layer of filter media may have a uniform composition across the exterior surface and through the thickness. The charged filter material may have a basis weight of at least about 60 gsm, less than about 150 gsm, or between about 80 gsm and about 120 gsm. The charged filter media may have a web thickness of between 25-50 mils, a stiffness of at least about 350 mg, less than about 450 mg, or less than about 500 mg, and a solidity of at least about 9%, at least about 11%, less than about 12%, or less than about 15%. The charged filter media may have an average flow resistance at 85 liters per minute of at least about 7 mm H2O or less than about 12.5 mm H2O. The charged filter media may include calendared charged filter media and polypropylene. The disposable respirator may include a harness and may have a total weight of less than 8 grams, less than 7 grams, less than 6.5 grams, or less than 6 grams. The single layer of charged filter media may include fibers having an effective fiber diameter of at least about 8 pm, less than about 15 pm, less than about 12 pm, or less than about 10 pm. A tensile strength of the single layer of charged filter media may be at least 750 g in a cross-web direction or in a machine direction. The disposable respirator may include a nonfuzzing surface. The mask body may include a plurality of panels that may fold in towards each other and unfold into an open configuration, with each of the plurality of panels including the single layer of charged filter media. The plurality of panels may include an upper panel, a lower panel, and a central panel, with the central panel connected to the upper panel and lower panel. The disposable respirator may further include a valve, a nose clip, or a nose foam. The disposable respirator may filter at least 99% or at least 99.9% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. The disposable respirator may be a horizontal flat-fold style respirator, a cup-shape style respirator with a shell, a vertical-fold style respirator, a pleated style respirator, or a duck bill style respirator. A method of forming a disposable respirator includes forming a nonwoven web with a uniform composition, defined as having a basis weight of at least about 60 gsm and less than about 150 gsm, a Gurley stiffness of at least about 350 mg, and a solidity of at least about 9%. The method includes forming a mask body from the nonwoven web, with the mask body formed of a single layer of the nonwoven web such that the single layer includes both an exterior surface and an interior surface of the disposable respirator. The disposable respirator has an airflow resistance of less than 12.5 mmH20 and fdters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. Forming the mask body may include welding the nonwoven web, applying staples, applying a valve, applying a harness, calendaring the nonwoven web, forming a plurality of panels, and coupling the panels together to form the mask body shape. The nonwoven web may have a basis weight of at least about 80 gsm and less than about 120 gsm, a thickness of at least about 25 mils and less than about 50 mils, and fibers with an effective fiber diameter of less than about 15 pm, at least about 8 pm, less than about 12 pm, or less than about 10 pm. The disposable respirator may exhibit an airflow resistance of less than about 12.5 mm H2O or at least about 7 mm H2O and may have a total weight of less than about 8 grams, less than about 7 grams, or less than about 6.5 grams. The nonwoven web may have a crossweb tensile strength of at least 750 g, a machine direction tensile strength of at least 750 g, and a Gurley stiffness of less than about 500 mg. The nonwoven web may be non-fuzzing. The disposable respirator may filter at least 99% or at least 99.5% of airborne particles with a mass median aerodynamic diameter of 0.3 pm. Forming the nonwoven web may include a spun bond technique, a melt blown technique, or a combination thereof. A nonwoven respirator filter media includes a basis weight of between about 60 gsm and about 150 gsm, a solidity of between about 9% and about 15%, fibers with an effective fiber diameter of between about 8 pm and about 15 pm, a Gurley stiffness of between about 350 mg and about 500 mg, and a tensile strength of at least 750 g in a crossweb direction or a machine direction. The respirator filter media may be sufficiently stiff to maintain a mask body shape during use without collapsing. The basis weight may be between about 80 gsm and about 120 gsm. The solidity may be between about 9% and about 12%. The effective fiber diameter may be between about 8 pm and about 10 pm. A tensile strength of the single layer of charged filter media may be at least 750 g in a cross-web direction or in a machine direction. The respirator may include a non-fuzzing surface. The fibers may include polypropylene and exhibit a quasi-permanent charge. The fibers may include electret fibers. The nonwoven respirator filter media may be calendared and include a uniform composition.

Claims

What is claimed is:

1. A nonwoven respirator filter media comprising: a basis weight of between about 60 gsm and about 150 gsm; a solidity of between about 9% and about 15%; a plurality of fibers having an effective fiber diameter of between about 8 pm and about 15 pm; a Gurley stiffness of between about 350 mg and about 500 mg; and a tensile strength of at least 750 g in a crossweb direction or a machine direction.

2. The nonwoven respirator filter media of claim 1, wherein the respirator filter media is sufficiently stiff such that, when a single layer is formed into a mask body shape, it maintains the mask body shape during use without collapsing.

3. The nonwoven respirator filter media of claim 1 or 2, wherein the basis weight is between about 80 gsm and about 120 gsm.

4. The nonwoven respirator filter media of any of claims 1-3, wherein the solidity is between about 9% and about 12%.

5. The nonwoven respirator filter media of any of claims 1-4, wherein the effective fiber diameter is between about 8 pm and about 10 pm.

6. The nonwoven respirator filter media of any of claims 1-5, wherein a tensile strength of the single layer of charged filter media is at least 750 g in a cross-web direction.

7. The nonwoven respirator filter media of any of claims 1-6, wherein the respirator comprises a non-fuzzing surface.

8. A disposable flat-fold respirator comprising: a mask body that comprises a plurality of panels which may fold in towards each other and may unfold into an open configuration, wherein the mask body comprises a single layer of charged filter material; wherein the plurality of panels includes an upper panel, a lower panel, and a central panel, wherein the central panel is connected to the upper panel and lower panel; wherein the respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm; and a harness secured to the mask body.

9. The respirator of claim 8, wherein the charged filter material comprises a uniform composition across a material surface.

10. The respirator of claim 8 or 9, wherein the charged filter material comprises a uniform composition throughout a material depth.

11. The respirator of any of claims 8-10, wherein the respirator, in the open configuration, is configured to maintain a mask body shape during use.

12. The respirator of any of claims 8-11, wherein the charged filter material comprises a basis weight of at least about 60 gsm.

13. The respirator of any of claims 8-12, wherein the charged filter media comprises a basis weight of less than about 150 gsm.

14. The respirator of any of claims 8-13, wherein the charged filter media comprises a basis weight between about 80 gsm and about 120 gsm.

15. The respirator of any of claims 8-14, wherein the charged filter media comprises a web thickness of between 25-50 mils.

16. The respirator of any of claims 8-15, wherein the charged filter media has a stiffness of at least about 350 mg.

17. The respirator of any of claims 8-16, wherein the charged filter media has a stiffness of less than about 450 mg.

18. A method of forming a disposable respirator, the method comprising: forming a nonwoven web, wherein the nonwoven web has a uniform composition, the uniform composition at least partially defined as having a basis weight of at least about 60 gsm and less than about 150 gsm, a Gurley stiffness of at least about 350 mg, and a solidity of at least about 9%; forming a mask body for the disposable respirator from the nonwoven web, wherein the mask body is formed of a single layer of the nonwoven web such that the single layer of the nonwoven web comprises both an exterior surface and an interior surface of the disposable respirator; and wherein the disposable respirator has an airflow resistance of less than 12.5 mmH20, and wherein the disposable respirator filters at least 95% of airborne particles with a mass median aerodynamic diameter of 0.3 pm.

19. The method of claim 18, wherein forming the nonwoven web comprises calendaring the nonwoven web to impart a smooth, non-fuzzing surface.

20. The method of claim 18, wherein the nonwoven web has a basis weight of at least about 80 gsm and less than about 120 gsm, and a thickness of between 25-50 mils.

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