BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of a foam block 10 that illustrates how multiple nose foams 12 can be cut therefrom into predefined arcuate shapes;
FIG. 2
a is a front view of predefined arcuate nose foam 12;
FIG. 2
b is a top view of an arcuate nose foam 12 taken in the direction of arrow A noted in FIG. 2a;
FIGS. 3
a-3c are perspective views of three different nose foam embodiments 12, 12′, and 12″;
FIG. 4 is a rear view of a respirator 24 that has a nose foam 12 located on an interior surface 18 of the mask body 20; and
FIG. 5 is a cross-section of mask body 20.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In describing preferred embodiments of the invention, specific terminology is used for clarity sake. The invention, however, is not intended to be limited to the specific terms so selected, and each term so selected includes all technical equivalents that operate similarly.
In practicing the present invention, a new respirator is provided that has a nose foam with a predefined downward concave curvature on the first major surface. The nose foam may also be configured on its first major surface to have a curvature that generally matches the interior concave downward curvature of the respirator mask body. When the nose foam is cut or otherwise fashioned into such a predefined shape, the foam is less likely to exhibit a pinching or compaction in one or more locations along the length of the nose foam when it is placed on the interior of the mask body. Before the present invention, conventional nose sealing foams had often been cut in a generally linear configuration that bore no relation to the curvature of the mask body interior. As such, the nose foams were susceptible to becoming compressed when they were bent to accommodate the shape of the mask body interior. The present invention, thus, may reserve nose foam compaction for accommodating the shape of the wearer's nose when the mask is worn.
FIG. 1 shows a nose foam block 10 from which a plurality of predefined, arcuate nose foams 12 may be cut. In previous techniques for manufacturing nose foams, the nose foams 12 were cut as linear strips that extended across the nose foam block 10. As shown in FIG. 1, the nose foams 12 are cut such that the inner cut of one nose foam also defines the outer cut of an adjacent nose foam. When the nose foams are cut in this manner, no waste is produced between adjacent nose foams. Waste may be created on the sides 13 of the block 10 but not between each adjacent nose foam 12. Although FIG. 1 shows multiple nose foams being cut from a single block of foam, the nose foams may be fashioned in other ways such as by individually molding each nose foam into the appropriate shape.
FIG. 2
a further illustrates the nose foam 12 and its first and second opposing major surfaces 14 and 16, respectively. The opposing major surfaces 14 and 16 are separated from each other by the thickness T of the nose foam. The first major surface 14 would be secured to the interior surface 18 of mask body 20 in its nose region 22 (FIG. 4). The second major surface 16 of the nose foam 12 is available for making substantial contact with the wearer's nose when the respirator 24 (FIG. 4) is donned. As shown in FIG. 2a, the nose foam 12 has a predefined downward concave curvature. The curvature is particularly pronounced in the center region 23 and may be defined by radius r1 and r2. The first radius r1 defines the radius of the inner curvature of the nose foam 12, and the second radius r2 defines the curvature of the outer surface of the nose foam 12 when viewed from the side elevation. The second major surface 16 may have an arc length A-L. In a preferred embodiment, the dimensions of r1 generally range from about 1.5 to 75 millimeters (mm), more typically about 2 to 50 mm. The dimensions of r2 generally range are about r1 plus the thickness of the nose foam. The path length of the nose foam A-L on its interior surface typically is about 4 to 10 centimeters (cm), more typically about 7 to 9 cm. The thickness of the nose foam T generally is greater than about 3 mm and may be up to about 15 mm, more typically greater than about 4 or 5 mm up to about 10 mm.
As shown in FIG. 2b, the nose foam 12 has the total projected lengthwise dimension P-L and a width W. The projected lengthwise dimension P-L is generally about 3 to 9 cm, more commonly about 5 to 8 cm. The width W generally is about 0.5 to 3 cm, more typically about 0.8 to 2 cm. The width W is the distance between the first and second side surfaces 19 and 21, respectively, of the nose foam 12.
The nose foam can be made from a variety of materials such a polyurethane, polyvinylchloride, polyolefin such as polypropylene and polyethylene, polyethylene vinyl acetate, rubber (natural or synthetic) such as polyisoprene, or combinations thereof. The nose foam could be made from an open cell or closed cell foam. Microcellular foams may also be used. The nose foam could use essentially any compressible material (now known or later developed) that adapts to the shape of a person's nose.
FIGS. 3
a-3c show three different embodiments of a nose foam element 12, 12′, and 12″. Each nose foam has a first major surface 14, 14′, and 14″, and a second major surface 16, 16′, and 16″. The embodiment shown in FIG. 5a has a generally constant curvature over the first and second major surfaces and has first and second tapered ends 15 and 17. These tapered ends are also present in the embodiments shown in FIGS. 3b and 3c as 15′, 15″, and 17′, 17″, respectively. In the embodiments shown in FIG. 3b, the nose foam has first and second straight portions 25′ and 27′ and has a tightly curved central portion 23′. In FIG. 3c, the central portion 23″ does not have as tight a radius as the central portion 23′ shown in FIG. 3b. The particular arc that is used on the first major surface 14, 14′, and 14″ may vary as shown in FIGS. 3a-3c. The configuration of the arc may vary depending on the interior shape of the mask body. As indicated above, it is preferred, but not necessary, that the first major surface more closely follows the interior of the mask body in the nose region. When the first major surface 14, 14′, and 14″ more closely matches the interior surface of the mask body in the nose region, there may be less opportunity for the nose foam to become pinched or unnecessarily compacted, particularly in the center of the nose foam 23, 23′, or 23″.
FIG. 4 shows a respirator mask 24 that includes a mask body 20 and the nose foam 12. The nose foam 12 exhibits a concave downward curvature when viewing the mask in an upright position as shown in FIG. 4. The nose foam 12 can be secured to the mask body 20 by applying an adhesive to the first major surface 14 of the nose foam 12 or to the interior of the mask body 20 or both. The adhesive could be, for example, a pressure-sensitive or hot-melt adhesive and could be applied as a coating or by spraying. Essentially any adhesive or other suitable means of securement, ultrasonic welding, for example, could be used to fasten the foam 12 to the mask body 20 interior 18. Mask body 20 is adapted to fit over the nose and mouth of a person in a spaced relation to a wearer's face to create an interior gas space or void between the wearer's face and the interior surface 18 of the mask body 20. The mask body 20 may be of a curved, hemispherical, cup-shape such as shown in FIG. 3—see also U.S. Pat. No. 4,536,440 to Berg, U.S. Pat. No. 4,807,619 to Dyrud et al., and U.S. Pat. No. 5,307,796 to Kronzer et al. The respirator body also may take on other shapes as so desired. For example, the mask body can be a cup-shaped mask having a construction as shown in U.S. Pat. No. 4,827,924 to Japuntich. The mask body also may be a flat-folded product like the bi-fold and tri-fold mask products disclosed in U.S. Pat. Nos. 6,722,366 and 6,715,489 to Bostock, U.S. Pat. Nos. D459,471 and D458,364 to Curran et al., and U.S. Pat. Nos. D448,472 and D443,927 to Chen. See also U.S. Pat. Nos. 4,419,993, 4,419,994, 4,300,549, 4,802,473, and Re. 28,102. The respiratory 24 may include a malleable nose clip that can be conformed to the shape of the wearer's nose. The nose clip may be made from a metal or plastic material that retains its deformed shape after being manually conformed. Examples of nose clips are shown in U.S. Pat. Nos. 5,558,089 and D412,573 to Castiglione, and in U.S. Ser. No. 11/236,283 to Kalatoor et al. Because the mask body shape at the nose region tends to be dictated by the shape of the nose clip, the nose foam curvature may be provided to generally match the curvature of the nose clip. The mask body may include one or more layers of filter media. Commonly, a nonwoven web of electrically-charged microfibers—i.e., fibers having an effective diameter of about 25 micrometers (μm) or less (typically about 1 to 15 μm)—is used as a layer of filter media. Filter media can be charged according to U.S. Pat. No. 6,119,691 to Angadjivand et al. Essentially any presently known (or later developed) mask body that is air permeable and that includes a layer of filter media could be used in connection with this invention.
As shown in FIG. 4, the respirator 24 also includes a harness such as straps 26 that are sized to pass behind the wearer's head to assist in providing a snug fit to the wearer's face. The straps 26 preferably are made of an elastic material that causes the mask body 24 to exert a slight pressure on the wearer's face. A number of different materials may be suitable for use as straps 26, for example, the straps may be formed from a thermoplastic elastomer that is ultrasonically welded to the respirator body 20. Ultrasonic welding may be beneficial over the use of staples to fasten the harness to the mask body since metal is not used. The 3M 8210™ particulate respirator is an example of a filtering face mask that employs ultrasonically welded straps. Woven cotton elastic bands, rubber cords (e.g. polyisoprene rubber) and/or strands also may be used, as well as non-elastic adjustable straps—see U.S. Pat. No. 6,705,317 to Castiglione and U.S. Pat. No. 6,332,465 to Xue et al. Other examples of mask harnesses that may be used in connection with the present invention are shown in U.S. Pat. Nos. 6,457,473B1, 6,062,221, and 5,394,568, to Brostrom et al., U.S. Pat. Nos. 6,591,837, 6,119,692 and 5,464,010 to Byram, and U.S. Pat. Nos. 6,095,143 and 5,819,731 to Dyrud et al. Essentially any strap system (presently known or later-developed) that is fashioned for use in supporting a respiratory face piece on a wearer's head could be used as a harness in connection with the present invention. The harness also could include a head cradle in conjunction with one or more straps for supporting the mask. The respirator also can have an exhalation valve located thereon such as the unidirectional fluid valve disclosed in U.S. Pat. No. 6,854,463 to Japuntich et al. An exhalation valve allows exhaled air to escape from the interior gas space without having to pass through the filter media in the mask body 20. The exhalation valve can be secured to the mask body through use of an adhesive—see U.S. Pat. No. 6,125,849 to Williams et al.—or by mechanical clamping—see U.S. Pat. No. 6,604,524 to Curran et al. The illustrated mask body 20 is air permeable and may be provided with an opening (not shown) that is located where an exhalation valve would be attached to the mask body 20 so that exhaled air can rapidly exit the interior gas space through the exhalation valve. The preferred location of the opening on the mask body 20 is directly in front of where the wearer's mouth would be when the mask is being worn. The placement of the opening, and hence the exhalation valve, at this location allows the valve to open more easily in response to the force or momentum from the exhale flow stream. For a mask body 20 of the type shown in FIG. 1, essentially the entire exposed surface of mask body 20 is air permeable to inhaled air.
The mask body may be spaced from the wearer's face, or it may reside flush or in close proximity to it. In either instance, the mask body helps define an interior gas space into which exhaled air passes before leaving the mask interior through the exhalation valve. The mask body also could have a thermochromic fit-indicating seal at its periphery to allow the wearer to easily ascertain if a proper fit has been established—see U.S. Pat. No. 5,617,849 to Springett et al.
FIG. 5 shows that the mask body 20 may comprise multiple layers, including an inner stiffening or shaping layer 28, a filtration layer 30, and an outer cover web 32. The inner stiffening or shaping layer 28 provides structure to the respirator body 20 and support for the filtration layer 30. The shaping layer 28 can be located on the inside and/or outside of the filtration layer 30 and can be made, for example, from a non-woven web of thermally-bondable fibers that have been molded into, for example, a cup-shaped configuration by, for example, the method taught in U.S. Pat. No. 5,307,796 to Kronzer et al. A shaping layer 28 also could be made from a molded plastic net—see U.S. Pat. No. 4,850,347 to Skov. Although the shaping layer is designed with the primary purpose of providing structure to the mask and providing support for a filtration layer, the shaping layer also may act as a filter, typically for capturing larger particles suspended in the exterior gas space, if disposed outside of the filter layer. Together the shaping and filtration layers may operate as an inhale filter element. When a wearer inhales, air is drawn through the mask body, and airborne particles become trapped in the interstices between the fibers, particularly the fibers in the filter layer. In the embodiment shown in FIGS. 4, the filter layer 30 is “integral” with the mask body 20—that is, it forms part of the mask body and is not an item that subsequently becomes attached to (or removed from) the mask body like a filter cartridge.
Filtering materials that are commonplace on negative pressure half mask respirators—like the filtering face mask 24 shown in FIG. 4—often contain an entangled web of electrically charged microfibers, particularly meltblown microfibers (BMF). Microfibers typically have an average effective fiber diameter of about 20 to 25 micrometers (μm) or less, but commonly are about 1 to about 15 μm, and still more commonly be about 3 to 10 μm in diameter. Effective fiber diameter may be calculated as described in Davies, C. N., The Separation of Airborne Dust and Particles, Institution of Mechanical Engineers, London, Proceedings 1B. 1952. BMF webs can be formed as described in Wente, Van A., Superfine Thermoplastic Fibers in Industrial Engineering Chemistry, vol. 48, pages 1342 et seq. (1956) or in Report No. 4364 of the Naval Research Laboratories, published May 25, 1954, entitled Manufacture of Superfine Organic Fibers by Wente, Van A., Boone, C. D., and Fluharty, E. L. Meltblown fibrous webs can be uniformly prepared and may contain multiple layers, like the webs described in U.S. Pat. Nos. 6,492,286B1 and 6,139,308 to Berrigan et al. When in the form of a randomly entangled web, BMF webs can have sufficient integrity to be handled as a mat. Electric charge can be imparted to fibrous webs using techniques described in, for example, U.S. Pat. Nos. 6,454,986B1 and 6,406,657B1 to Eitzman et al.; U.S. Pat. Nos. 6,375,886B1, 6,119,691 and 5,496,507 to Angadjivand et al., U.S. Pat. No. 4,215,682 to Kubik et al., and U.S. Pat. No. 4,592,815 to Nakao.
Examples of fibrous materials that may be used as filters in a mask body are disclosed in U.S. Pat. No. 5,706,804 to Baumann et al., U.S. Pat. No. 4,419,993 to Peterson, U.S. Reissue Pat. No. Re 28,102 to Mayhew, U.S. Pat. Nos. 5,472,481 and 5,411,576 to Jones et al., and U.S. Pat. No. 5,908,598 to Rousseau et al. The fibers may contain polymers such as polypropylene and/or poly-4-methyl-1-pentene (see U.S. Pat. No. 4,874,399 to Jones et al. and U.S. Pat. No. 6,057,256 to Dyrud et al.) and may also contain fluorine atoms and/or other additives to enhance filtration performance—see, U.S. Pat. Nos. 6,432,175B1, 6,409,806B1, 6,398,847B1, 6,397,458B1 to Jones et al. and U.S. Pat. Nos. 5,025,052 and 5,099,026 to Crater et al., and may also have low levels of extractable hydrocarbons to improve performance—see U.S. Pat. No. 6,213,122 to Rousseau et al. Fibrous webs also may be fabricated to have increased oily mist resistance as described in U.S. Pat. No. 4,874,399 to Reed et al., and in U.S. Pat. Nos. 6,238,466 and 6,068,799, both to Rousseau et al. The filtration layer optionally could be corrugated as described in U.S. Pat. Nos. 5,804,295 and 5,763,078 to Braun. The mask body also can include an outer cover web to protect the filtration layer. The cover web may be made from nonwoven webs of BMF as well, or alternatively from webs of spunbond fibers. An inner cover web also could be used to provide the mask with a soft comfortable fit to the wearer's face—see U.S. Pat. No. 6,041,782 to Angadjivand et al. The cover webs also may have filtering abilities, although typically not nearly as good as the filtering layer.
The following Example has been selected merely to further illustrate features, advantages, and other details of the invention. It is to be expressly understood, however, that while the Examples serve this purpose, the particular ingredients and amounts used as well as other conditions and details are not to be construed in a manner that would unduly limit the scope of this invention.
EXAMPLE
A nose foam of the invention was constructed and attached to a mask body. The nose foam included a reticulated flexible polyester polyurethane foam manufactured by Foamex International Inc., Linwood, Pa. under the brand SIF™. The foam had a nominal density of 26 kilograms per cubic meter (kg/m3), tensile strength of 173 Kilo Pascals (kPa), tear strength of 525 Newtons per meter (N/m) as determined in accordance with ASTM D 3574. The pore texture of the foam was nominally 195 cells per 10 lineal centimeters. The nose foam was formed from a 7.9 mm thick foam sheet that had a pressure sensitive adhesive applied to one face. The adhesive was acrylic based, was manufactured by the 3M Company, and was manually applied to one face of the cut nose foam. The foam sheet was then placed onto a cutting surface and was cut using a steel rule die cutting tool. The cut nose foam was then removed from the cutting tool, resulting in an arced, annulus-section, part that mirrored the contour of the cutting tool. The shape of the cut nose foam is generally depicted in FIGS. 2 and 3a. The inner arc of the annulus section had a radius of curvature, r1 as depicted in FIG. 2 of 43.2 mm, with a corresponding outer arc radius of curvature, r2, of 48.2 mm. The path length A-L at radius of curvature r1 along the inner arc from point 33 to point 35 was 90 mm long. The projected length P-L was 57.3 mm. Each end of the nose seal foam had a rounded end having a radius of 10 mm.
The above-described nose foam was affixed to a commercially available 8511™ particulate respirator manufactured by the 3M Company, St. Paul, Minn. The sole modification to the respirator was that the original nose foam and nose clip were removed, and the inventive nose foam replaced the original nose foam. The inventive nose foam was attached to the inner surface of the respirator cup using an adhesive that was applied to the first major surface of the nose foam. The nose foam was positioned in the same general location on the respirator cup as the original nose foam. The inner arc of the nose foam, as defined by curvature of radius r1, was oriented to face the interior surface of the respirator cup. The arcuate shape of the first major surface of the nose foam allowed it to follow the arc of the inner surface of the respirator cup without visually noticeable deformation or pinching of the nose foam.
This invention may take on various modifications and alterations without departing from its spirit and scope. Accordingly, this invention is not to be limited to the above-described but is to be controlled by the limitations set forth in the following claims and any equivalents thereof.
This invention may be suitably practiced in the absence of any element not specifically disclosed herein.
All patents and patent applications cited above, including those in the Background section, are incorporated by reference into this document in total. To the extent there is a conflict or discrepancy between the disclosure in such incorporated document and the above specification, the above specification will control.
Patent Application
20080023006
