CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims the priority of United States Patent Application No. 63/144,527, filed on February 2, 2021 , and of United States Patent Application No. 63/278,686, filed on November 12, 2021 , the contents of both of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] This disclosure generally relates to the field of protective filtering masks for protecting a wearer’s airways against undesired pathogens and airborne particles.

BACKGROUND OF THE ART

[0003] Filtering masks, such as N95, N99, and N100 masks, are designed for filtering particles of a given threshold size. For example, N95 masks have been widely used in health care environments to protect wearers against viruses such as influenza or other infectious particles. Recently, the World Health Organization advised that N95 masks could be included in personal protection equipment for people treating patients against COVID-19 to decrease transmission of the disease.

[0004] The Canadian particulate filter efficiency (PFE) norm requires 95% of particles of 0.3 microns to be block from passing through the filter. However, such high filtering efficiency may be correlated with a high breathing resistance for the wearer. Some masks include a valve via which air exhaled by the wearer passes through the mask. The use of masks equipped with such valve is not recommended since pathogens contained within the air exhaled by the wearer may flow unfiltered outside and contaminate another person.

[0005] Improvements are therefore sought.

SUMMARY

[0006] In one aspect, there is provided a filtering mask comprising: a filtering portion having an outer layer oriented away from a wearer, an inner layer oriented toward the wearer, and a filtering core between the outer layer and the inner layer; wherein the inner layer and the outer layer are made of a non-woven fabric, and wherein the filtering core is made of non-woven electrostatically charged fibers. [0007] Further in accordance with the aspect, for instance, the filtering core includes two layers of the non-woven electrostatically charged fibers.

[0008] Still further in accordance with the aspect, for instance, an outer core layer of the two layers is made of polypropylene having a density of from 23 to 33 gram by square meter.

[0009] Still further in accordance with the aspect, for instance, an inner core layer of the two layers is made of polypropylene having a density of from 23 to 33 gram by square meter.

[0010] Still further in accordance with the aspect, for instance, the outer layer is made of polyester having a density of from 200 to 250 gram by square meter.

[0011] Still further in accordance with the aspect, for instance, the inner layer is made of polyester having a native density of from 200 to 250 gram by square meter.

[0012] Still further in accordance with the aspect, for instance, the filtering portion includes a face-engaging section, a breathing section, and an intermediate section between the faceengaging section and the breathing section.

[0013] Still further in accordance with the aspect, for instance, a thickness of the breathing section is greater than a thickness of the intermediate section, and wherein the thickness of the intermediate section is greaterthan a thickness of the face-engaging section.

[0014] Still further in accordance with the aspect, for instance, a stiffness of the breathing section is less than a stiffness of the intermediate section, and wherein the stiffness of the intermediate section is less than a thickness of the face-engaging section.

[0015] Still further in accordance with the aspect, for instance, the filtering core is free to move relative to the inner layer and relative to the outer layer in the breathing section, and wherein the filtering core is laminated to the inner layer and to the outer layer in the face-engaging section.

[0016] Still further in accordance with the aspect, for instance, the face-engaging section defines a flange at a periphery of the filtering portion.

[0017] Still further in accordance with the aspect, for instance, the filtering portion is a monolamination. [0018] Still further in accordance with the aspect, for instance, the inner layer, the outer layer, and the filtering core have uniform native thicknesses.

[0019] Still further in accordance with the aspect, for instance, the inner layer, the outer layer, and the filtering core include low-melt fibers.

[0020] Still further in accordance with the aspect, for instance, the low-melt fibers are present as 20% ± 10% per weight.

[0021] Still further in accordance with the aspect, for instance, the filtering mask further includes a sealing portion

[0022] Still further in accordance with the aspect, for instance, the sealing portion is a gasket of closed-cell polyvinyl chloride foam.

[0023] Still further in accordance with the aspect, for instance, the foam has 7.0 lb/ft ³ ± 1.0 lb/ft ³ .

[0024] Still further in accordance with the aspect, for instance, an attachment portion may be provided.

[0025] In accordance with another aspect, there is provided a method of manufacturing a filtering mask, comprising: sandwiching a filtering core between an outer layer and an inner layer, the outer layer and the inner layer made of non-woven fibers, the filtering core made of non-woven electrostatically charged fibers; and compressing and heating the outer layer, the filtering core, and the inner layer between complementary mold members to create a body of the filtering mask having a concave shape.

[0026] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.

DESCRIPTION OF THE DRAWINGS

[0027] Fig. 1 is a three dimensional view of a face of a wearer equipped with a mask shown schematically;

[0028] Fig. 2 is a three dimensional view of a mask in accordance with one embodiment; [0029] Fig. 3A is a three dimensional view showing an inner side of the mask of Fig. 2, with a first type of sealing portion;

[0030] Fig. 3B is a rear view showing an inner side of the mask of Fig. 2, with a second type of sealing portion;

[0031] Fig. 4 is another three dimensional view of the inner side with a sealing portion removed therefrom for illustration purposes;

[0032] Fig. 5 is a face view of the mask of Fig. 2;

[0033] Fig. 6 is a cutaway view of the mask taken along line C-C of Fig. 5;

[0034] Fig. 7 is a cutaway view of the mask taken along line D-D of Fig. 5;

[0035] Fig. 8 is an enlarged cross-sectional view of the mask of Fig. 2 illustrating a layered construction of said mask.

DETAILED DESCRIPTION

[0036] Referring to Figs. 1 -3B, a mask in accordance with various embodiments of the present disclosure is shown at 10. The mask 10 includes a face-covering portion 20, also referred to as a filtering portion or a shell, a sealing portion 30, and an attachment portion 40, optionally. Each of those parts or portions are described herein below.

[0037] The filtering portion 20 is configured to be in abutment against a face F of a wearer along a perimeter P. The perimeter P extends around a portion of a nose N, a mouth M, and around a portion of a chin C of a wearer. The filtering portion 20 therefore covers the mouth M and nose N of the wearer via which air may be inhaled and exhaled by the wearer, i.e., the two main airways of human anatomy. As will be discussed below, the mask 10 is configured to sealingly engage the face F of the user at the perimeter P to force substantially all air exhaled and inhaled by the wearer to go through the filtering portion 20 to avoid unwanted pathogens from being inhaled by the wearer or from being exhaled by the wearer toward other persons that may be contaminated by said pathogens. Stated differently, if worn properly, the mask 10 aims to limit air flow between the perimeter P of the mask 10 and a face of the wearer.

[0038] Referring more particularly to Figs. 4-7, the filtering portion 20 of the mask 10 includes a body 21 having a wearer-facing side 21 a and an opposed outside-facing side 21 b. The filtering portion 20 has a thickness T* (i.e., T1 , T2, T3, etc) extending from the wearer-facing side 21 a to the outside-facing side 21 b. Though it may have an integral or monolithic molded construction, the body 21 may include three sections, namely, a face-engaging section 22, a breathing section 23, and an intermediary section 24 extending from the face-engaging section 22 to the breathing section 23. Sections 22, 23 and 24 may be inseparable from one another (e.g., monolithic or monolaminate) but are described as separate sections 22, 23, 24 to facilitate an understanding of the filtering portion 20. More or fewer sections may be present. Each of these sections has a respective thickness, or thicknesses. Namely, the face-engaging section 22 has a first thickness T1 that may be less than a second thickness T2 of the intermediary section 24. The breathingsection 23 has a third thickness T3 that may be greater than both of the first and second thicknesses T1 , T2. Other arrangements are considered as well. The face-engaging, intermediary, and breathing sections 22, 24, 23 may be referred to as consolidated, semiconsolidated, and non-consolidated sections, respectively. This latter nomenclature is used below. While the expression “thickness” is used, for example as thickness T1 , thickness T2, thickness T3, the thickness of any of these sections may not be constantly at a single value. For example, any one of thicknesses T1 , T2, and T3 may be a range of values. In a variant, it may be said that a numerical value for any one of thicknesses T1 , T2 and T3 is an average value, a median value, a middle value, etc.

[0039] The consolidated section 22 may define a flange 25 extending all around an opening O of the mask 10, via which the face F (Fig. 1) of the wearer is partially received within a cavity S of the filtering portion 20 of the mask 10. The flange 25 may also extend around part of the opening O, for instance with disruptions in the flange 25 (e.g., at the dorsum nasi). As another possibility, the flange 25 may taper to a small width at given locations, such as at the dorsum nasi. As discussed below, the flange 25 is used to interface the filtering portion 20 to the face F of the wearer. Moreover, the consolidated section 22 may serve as a bonding surface for the sealing portion 30, as described below.

[0040] In the embodiment shown, the body 21 of the filtering portion 20 of the mask 10 has a converging shape from the opening O toward the breathing section 23. In the present case, this converging shape is achieved by having the semi-consolidated section 24 made of three stepped segments secured to one another. The breathing section 23 and the face-engaging section 22 are connected to one another via the three stepped segments of the intermediary section 24. Having three interconnected stepped segments or like configuration may provide some clearance between the mouth of the user and the filtering portion 20 of the mask 10. This may increase comfort and may limit the humidity level between the mouth and the filtering portion 20. Moreover, the ovoid-shaped breathing section 23 (or like elongated shape) may be sized to optionally accommodate a valve in other embodiments. However, steps are only optionally present and/or steps may be part of the face-engaging section 22 and/or the breathing section 23. There may be more or fewer steps than the three shown and the steps may not be limited to defining closed figures. Moreover, steps may be viewed as ribs on the sides of the mask 10, and may blend into continuous surfaces that are at the chin and nose portions of the mask 10.

[0041] Referring now to Fig. 8, the body 21 of the filtering portion 20 of the mask 10 has a layered structure 100 including an outer layer 101 , a filtering core 102, and an inner layer 103. The outer layer 101 is exposed on the outer-facing side 21 b of the body 21 of the filtering portion 20. The inner liner 103 is exposed on the wearer-facing side 21 a of the body 21 of the filtering portion 20. In an embodiment, each of the face-engaging section 22, the breathing section 23, and the intermediary section 24 of the body 21 of the mask 10 includes the layered structure 100.

[0042] In the embodiment shown, the outer layer 101 is made of a non-woven fabric. The outer layer 101 may be made of non-woven polyester fibers (e.g., polyethylene terephthalate (PET) fibers) having a native density of about 200 to about 280 gram by square meter and a thickness t1 ranging from 1 to 10 mm, and in an embodiment, t1 is from 5.0 to 6.0 mm, inclusively, native density meaning herein before molding (a.k.a., laminating, thermoforming). The inner layer 103 may be made of a non-woven fabric. The inner layer 103 may be made of non-woven polyester fibers having a native density of about 200 to about 250 gram by square meter and a thickness t2 ranging from 1 to 10 mm, and in an embodiment from 5.0 to 6.0 mm, before molding. Thicknesses t1 and t2 of the outer layer 101 and of the inner layer 103 correspond to “before molding” thicknesses of the non-woven fabric before being formed into the body 21 of the mask 10, or native thicknesses. Stated differently, the “before molding” thicknesses are those when the sheets or panels of the non-woven fabric are in a non-compressed ambient relaxed condition. The native density is expressed as mass by surface area because those materials are typically sold as rolls. Hence, a square meter of the fabric having a density of 200 grams by square meter weighs 200 grams. In a particular embodiment, the outer layer 101 and/or the inner layer 103 are made of non-woven spunbound polypropylene or non-woven spunbound polyester. The outer layer 101 and the inner layer 103 may be made of or may include filaments of any suitable stretchable woven fabric, such as, Lycra™, Spandex™, and so on. The materials of the different layers of the layered structure 100 may include a percentage (e.g., 20% ± 10% perweight) of low- melt fibers acting as a binder when heated and compressed at the perimeter of the filtering portion 20 of the mask 10. As shown in Fig. 8, the inner layer 103, the outer layer 101 , and the layer(s) 104, 105 of the filtering core 102 have uniform native thicknesses, as t1 , t2, t3 and t4 are shown by parallel lines, but this is optional.

[0043] The filtering core 102 includes at least one layer of a filtering medium. In the embodiment shown, the filtering core 102 includes outer and inner core layers 104, 105 of a filtering medium. The outer core layer 104 is disposed adjacent to the outer layer 101 and between the outer layer 101 and the inner core layer 105. The outer core layer 104 may be made of nonwoven electrostatically charged polypropylene fibers having a native density of from 23 to 33 gram by square meter, such as 28 grams by square meter. The inner core layer 105 is disposed adjacent to the inner layer 103 and is disposed between the inner layer 103 and the outer core layer 104. The inner core layer 105 may be made of non-woven electrostatically charged polypropylene fibers having a native density of from 23 to 33 gram by square meter, such as 30 gram by square meter. A thickness t3 of the outer core layer 104 of the filtering core 102 may be from 0.15 mm to 0.20 mm, before molding. A thickness t4 of the inner core layer 105 of the filtering core 102 may be from 0.15 mm to 0.20 mm before molding. The thicknesses t3 and t4 of the outer core layer 104 and of the inner core layer 105 are “before molding” thicknesses that correspond to thicknesses of the non-woven fabric before being formed into the body 21 of the mask 10. A pair of core layers are shown, but a single one may suffice, for instance a single one that may have the same properties.

[0044] For manufacturing the body 21 of the mask 10, the layered structure 100 described herein above with reference to Fig. 8 is inserted between male and female mold counterparts, heated, compressed to form the shape of the body 21 of the mask 10, and cooled down. This may be known as lamination, as thermoforming. The layered structure 100 is made by superposing the different layers on top of one another as shown in Fig. 8. The four layers 101 , 102, 104, 105 are not secured to one another at their contact surfaces. Stated differently, the four layers 101 , 102, 104, 105 are simply in contact with one another without being held and may slide one relative to the other during the molding process, i.e., in plane movement is possible.

[0045] During the molding process, the outer layer 101 and the inner layer 103 may allow the shaping of the body 21 into the concave shape shown in Figs. 2-3B. The material of the outer and inner layers 101 , 103, non-woven polyester fibers in the embodiment shown, may play a damping function during molding. This may allow the molding of the body 21 of the mask 10 in a single molding step. The outer and inner layers 101 , 103 of non-woven polyester fibers may allow the shaping of the outer and inner core layers 104, 105 without tearing them. In otherwords, the outer and inner layers 101 , 103 may prevent the tearing of the outer and inner core layers 104, 105 of the filtering core 102 during the molding process.

[0046] The molding process including the outer and inner layers 101 , 103 may reduce tearing risks of the outer and inner filtering core 104, 105. The outer and inner layers 101 , 103 act has a protective shell for the filtering core 102 since materials of the filtering core 102 may be more fragile and more susceptible to tearing while being manipulated. Tearing of the layers 104, 105 of the filtering core 102 may reduce resistance to breathing and impair the filtering efficiency. The disclosed layered structure 100 with its outer and inner layers 101 , 103 may result in a mask having a greater filtering efficiency compared to a mask made without the outer and inner layers 101 , 103. Moreover, the one-step molding process described above may provide a more efficient mask from a filtering efficiency perspective.

[0047] Referring to Figs. 6-8, before molding the layered structure 100, the thickness of the layered structure 100 is uniform and corresponds to the sum of the thicknesses t1 , t2, t3, t4 of the uncompressed different layers 101 , 103, 104, 105. The use of thick (5-6 mm) outer and inner layers 101 , 103 may allow to manufacture the body 21 of the mask 10 with different zones of varying stiffness. These zones are briefly described below and corresponds to the consolidated section generally defined by the face-engaging section 22, the semi-consolidated section generally defined by the breathing section 23, and the non-consolidated section generally defined by the intermediary section 24. In the embodiment shown, the molded thickness T1 of the consolidated section 22 is from 1 to 1.5 mm. The consolidated section 22 is therefore stiffer than the semi- and non- consolidated sections 24, 23 because the layered structure 100 has been compressed to a thinner thickness, and has an increased density. A greater stiffness may be desired for the consolidated section 22 since it defines the perimeter of the body 21 and the flange 25 via which the attachment system 40 is secured to the body 21 of the filtering portion 20 of the mask 10 and via which the sealing portion 30 is secured to the body 21 at the flange 25. The semi-consolidated section, encompassing the intermediary section 24, occupies about 75% of the surface of the body 21 . The molded thickness T2 of the semi-consolidated section 24 is from 3 to 5 mm. This semi-consolidated section 24 may uniformly spread filtration capabilities of the mask while keeping a moderated stiffness. The non-consolidated section 23 is at a front portion of the body 21 and may have an ovoid shape, or other appropriate shapes, including a teardrop shape. The non-consolidated section 23 may occupy about 12% of the surface of the body 21 . The thickness T3 of the non-consolidated section 23 is from 8 to 12 mm. The non-consolidated section 23 may reduce breathing resistance for the wearer. Namely, the greater thickness T3 in this section compared to the other two sections may improve by more than 18% the breathing comfort for the wearer, i.e., as the layers have a lesser degree of compression therein, the nonconsolidated section 23 may offer greater breathability than the other sections. This percentage may vary in function of the density of the material of the outer and inner layers 101 , 103.

[0048] Having the different layers 101 , 103, 104, 105 of the layered structure 101 of the body 21 of the mask 10 free to move one relative to the other at least at the non-consolidated section 23, i.e., after molding, may promote air displacement through the body 21 toward the outside without compromising the filtering of said air. This may promote a stable breathing for the wearer and may improve how sounds travel through the mask 10 when the wearer is talking. It may therefore be easier for another person to hear the wearer of the mask 10 speaks thanks to the non-consolidated section 23. The lower density of the non-consolidated section 23, compared to that of the semi- and consolidated sections 24, 22 may promote evacuation of hot and humid warm air exhaled from the wearer when breathing. This may avoid accumulation of heat into the cavity S of the body 21 and may improve comfort for the wearer. Moreover, the freedom of movement between the layers may remove tear points, and reduce the risk of rupture of the membranes 104 and 105.

[0049] Typical molding processes require a pre-shaping step. This pre-shaping step is used to avoid stretching and/or deforming filtering medium by up to from 15 to 18% during molding to avoid loss in filtering efficiency. The disclosed layered structure 100 may not require the preshaping step hence may decrease manufacturing costs and reduce manufacturing time.

[0050] Referring to Fig. 3A, a variant ofthe sealing portion 30 may be made of a thermoplastic elastomer, may be flexible and may be secured to the flange 25 of the body 21 of the mask 10. The sealing portion 30 may be welded to the body 21 using an ultrasound welding technique, glues, stitching, etc. The sealing portion 30 may be able to conform to the face F (Fig. 1) of the wearer and may cater to a plurality of shapes of faces as required by some regulations (e.g., PFE95). For example, the sealing portion 30 is molded, and may come in different sizes based on age groups, gender, race, etc, as may also be the case for the filtering portion 20.

[0051] Referring to Fig. 3B, another variant of the sealing portion 30 is a strip of material acting as a gasket, extending peripherally along the mask 10 in the wearing-facing side 21 a, inside the cavity S. The sealing portion 30 in Fig, 3B is in close proximity to the flange 25. In an embodiment, the sealing portion 30 of Fig. 3B could be applied to the flange 25. The sealing portion 30 of Fig. 3B may be made of any appropriate material. One such materials is a light density closed-cell polyvinyl chloride foam. Such foam may come in the form of a tape that is adhered to the surface of the mask 10, against the material of the inner layer 103. Due to the level of compression in the consolidated section 22, adherence of the foam tape is suitable to ensure that the sealing portion 30 of Fig. 3B is airtight against the inner layer 103. The foam tape may also have a surface skin applied against the inner layer 103 and/or facing away from the inner layer 103. In the latter case, the skin may contribute to the comfort of the wearer. In an embodiment, a thickness of the sealing portion 30 of Fig. 3B is from 0.079” (2.0 mm) to 1.0” (25.4 mm), though other thicknesses are contemplated. An exemplary density of the foam tape is 7.0 lb/ft ³ ± 1.0 lb/ft ³ .

[0052] Referring to Fig. 2, the attachment portion 40 may include an elastic 41 , which may be composed of about 87% polyester and 13% spandex. The elastic 41 may have a width of about 6 mm and may be a band inserted into apertures defined through the flange 25 of the body 21 of the mask 10, as a possibility among others. The band 41 may for instance be a strip glued to the body 21 of the mask 10 or to the sealing portion 30. The elastic 41 may be stretched by about 125% of its at-rest length. An optional tie ring 42, which may be made of PVC, fabric, etc, may allow the tightening of the elastic 41 to bias the body 21 of the mask and the sealing portion 30 in a sealing engagement against the face F of the wearer and for deforming the body 21 until it conforms to the shape of the face F of the wearer. The mask 10 may be without the attachment portion 40, or may be sold separately. In a variant, the attachment portion 40 features a Velcro® system at the end of non-elastic strips, or may be used with an adhesive between a user’s skin the filtering portion 20 or sealing portion 30. The filtering portion 20 may also be sold as a separated unit, or may be used without the sealing portion 30.

[0053] In an embodiment, the filtering portion 20 may be described as being made of the same layers of material, though with different characteristics and properties depending on the various sections, or zones, of the filtering portion 20. The different characteristics may result in a molding process that gives the filtering portion 20 its shape along with the characteristics and properties described above.

[0054] Test carried on the mask 10 of the present disclosure revealed that the mask 10 may filtrate 97% or more of particles having a size of 0.3 microns and may have an average breathing resistance of about 130 Pa. However, these values are merely given as an example, as they were obtained in specific test settings, that may not be replicated without the precise parameters of testing.

[0055] In the present disclosure, the expression “about” implies a variation of plus or minus 10% of a value. For instance, about 10 implies from 9 to 11 .

[0056] The mask 10 may be generally described a filtering mask that may include a filtering portion having an outer layer oriented away from a wearer, an inner layer oriented toward the wearer, and a filtering core between the outer layer and the inner layer. The inner layer and the outer layer are made of a non-woven fabric. The filtering core is made of non-woven electrostatically charged fibers. The mask 10 may be fabricated in different ways. One such method consists of a method of manufacturing a filtering mask, that may include: sandwiching a filtering core between an outer layer and an inner layer, the outer layer and the inner layer made of non-woven fibers, the filtering core made of non-woven electrostatically charged fibers; andcompressing and heating the outer layer, the filtering core, and the inner layer between complementary mold members to create a body of the filtering mask having a concave shape.

[0057] The filtering portion 20 may be said to be monolithic, monoblock, ora monolamination, even though it may have version sections. These expressions are present to express that the filtering portion 20, once manufactured to the shape shown in the figures (Fig. 4), starting for example from flat sheets as in Fig. 8, has its layers form an integral unseparable component, in that an attempt to separate the layers may require specific manipulations and/or forces and/or tools to succeed, with the risk of tearing some of the layers. Stated differently, the filtering portion 20 is a single piece of different layers that may not separate from one another.

[0058] As can be seen therefore, the examples described above and illustrated are intended to be exemplary only. The scope is indicated by the appended claims.