[0001] The present invention pertains to a respirator that has a grasping feature located
on the mask body. The grasping feature includes an indicia that provides an indication
of where the user should grasp the mask body for donning, or doffing, or adjusting.
BACKGROUND
[0002] Respirators are commonly worn over the breathing passages of a person for at least
one of two common purposes: (1) to prevent impurities or contaminants from entering
the wearer's breathing track; and (2) to protect other persons or things from being
exposed to pathogens and other contaminants exhaled by the wearer. In the first situation,
the respirator is worn in an environment where the air contains particles that are
harmful to the wearer, for example, in an auto body shop. In the second situation,
the respirator is worn in an environment where there is risk of contamination to other
persons or things, for example, in an operating room or a clean room.
[0003] A variety of respirators have been designed to meet either (or both) of these purposes.
Some respirators have been categorized as being "filtering face-pieces" because the
mask body itself functions as the filtering mechanism. Unlike respirators that use
rubber or elastomeric masks in conjunction with attachable filter cartridges (see,
e.g.,
U.S. Patent RE39,493 to Yuschak et al. and
U.S. Patent 4,098,270 to Dolby) or insert-molded filter elements (see, e.g.,
U.S. Patent 4,790,306 to Braun), filtering face-piece respirators are designed to have the filter media cover much
of the whole mask body so that there is no need for installing or replacing a filter
cartridge. Filtering face-piece respirators commonly come in one of two configurations:
molded respirators and flat-fold respirators.
[0004] Molded filtering face piece respirators have regularly comprised non-woven webs of
thermally-bonded fibers or open-work plastic meshes to furnish the mask body with
its cup-shaped configuration. Molded respirators tend to maintain the same shape during
both use and storage. Examples of patents that disclose molded, filtering, face-piece
respirators include
U.S. Patents 7,131,442 to Kronzer et al,
6,923,182,
6,041,782 to Angadjivand et al.,
4,850,347 to Skov,
4,807,619 to Dyrud et al.,
4,536,440 to Berg, and Des.
285,374 to Huber et al.
[0006] Before donning a respirator, it is critically important that the respirator wearer
read and understand use instructions. A user's unfamiliarity with, for example, flat-fold
respirators may cause incorrect handling and donning and doffing mistakes. Such misguided
use may result in an improper and uncomfortable fit, which may lead to lack of protection
and also may tarnish a user's perception of respirators.
[0007] Some filtering face-piece respirators have been provided with grasping features to
assist the user in donning and doffing.
U.S. Patents 6,948,499 and
6,945,249 to Griesbach, III et al. disclose an example of such a filtering face-piece respirator. While this respirator
is provided with a grasping feature in the form of a "tab", the grasping feature does
not include any type of indicia that would intuitively inform the user of where to
grasp the mask during donning, doffing, and adjusting operations. Therefore, the grasping
feature may not be readily apparent and accordingly may not be used by the wearer.
As discussed below, the present invention, however, provides a user friendly way to
quickly identify where to grasp the mask for fitment purposes.
SUMMARY OF THE INVENTION
[0008] The present invention provides a new filtering, face-piece respirator that comprises
(a) a harness; and (b) a mask body that has a grasping feature located thereon, the
grasping feature having an indicia for providing an indication for where to grasp
the mask body for fitment.
[0009] The inventors discovered that the use of indicia on a grasping feature is beneficial
for both achieving and maintaining a snug fit to the wearer's face. The grasping feature
provides a solid surface onto which the wearer's fingers can easily grasp the mask
body to properly position it during donning and subsequent adjustments and doffing.
The indicia provides an indication to the wearer of where the grasping feature is
located and how to grasp that feature during these fitment operations and accordingly
facilitates wearer training.
[0010] Imagery, rather than text, has become an increasingly popular means for conveying
information to users concerning the operation of various products. Many images have
taken on universal recognition. The intention of the indicia in the present invention
is to create an association in the mind of the user of the correct place on the respirator
to hold the mask body when repositioning and doffing. The indicia may take the form
of, for example, a fingerprint pattern. A fingerprint pattern can be integrated into
an area of ultrasonically bonded material to be seen as a contrast, or image, between
the welded and un-welded areas and also may be felt at the wearer's fingertips by
varying mask thickness at those areas. An image, however, also could be printed onto
the grasping feature to allow for a greater visual contrast from the rest of the mask.
When the indicia is generally circular in shape, the effect could be achieved by cutting
a crescent shape, or even a small hole, into the grasping feature, which hole or opening
would have the additional function of allowing the mask to be hung on a nail or hook
for easy storage away from contaminated surfaces, or even as a method for dispensing.
GLOSSARY
[0011] The terms set forth below will have the meanings as defined:
[0012] "bisect(s)" means to divide into two generally equal parts;
[0013] "comprises (or comprising)" means its definition as is standard in patent terminology,
being an open-ended term that is generally synonymous with "includes", "having", or
"containing". Although "comprises", "includes", "having", and "containing" and variations
thereof are commonly-used, open-ended terms, this invention also may be suitably described
using narrower terms such as "consists essentially of', which is a semi open-ended
term in that it excludes only those things or elements that would have a deleterious
effect on the performance of the inventive respirator in serving its intended function;
[0014] "clean air" means a volume of atmospheric ambient air that has been filtered to remove
contaminants;
[0015] "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;
[0016] "crosswise dimension" is the dimension that extends laterally across the respirator
from side-to-side when the respirator is viewed from the front;
[0017] "cup-shaped configuration" means any vessel-type shape that is capable of adequately
covering the nose and mouth of a person;
[0018] "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;
[0019] "filtering face-piece" means that the mask body itself is designed to filter air
that passes through it; there are no separately identifiable filter cartridges or
insert-molded filter elements attached to or molded into the mask body to achieve
this purpose;
[0020] "filter" or "filtration layer" means one or more layers of air-permeable material,
which layer(s) is adapted for the primary purpose of removing contaminants (such as
particles) from an air stream that passes through it;
[0021] "filter media" means an air-permeable structure that is designed to remove contaminants
from air that passes through it;
[0022] "filtering structure" means a construction that includes a filter media or a filtration
layer and optionally other layers;
[0023] "first side" means an area of the mask body that is located on one side of a plane
that bisects the mask body normal to the cross-wise dimension;
[0024] "fitment" means any one or combination of donning, doffing, or the adjusting mask
body position;
[0025] "flange" means a protruding part that has sufficient surface area to be grasped by
a person;
[0026] "frontally" means extending away from the mask body perimeter when the mask body
is in a folded condition;
[0027] "harness" means a structure or combination of parts that assists in supporting the
mask body on a wearer's face;
[0028] "indicia" means an identifying mark(s), pattern(s), image(s), opening(s), texture(s)
or combination thereof;
[0029] "integral" means being manufactured together at the same time; that is, being made
together as one part and not two separately manufactured parts that are subsequently
joined together;
[0030] "interior gas space" means the space between a mask body and a person's face;
[0031] "laterally" means extending away from a plane that bisects the mask body normal to
the cross-wise dimension when the mask body is in a folded condition;
[0032] "line of demarcation" means a fold, seam, weld line, bond line, stitch line, hinge
line, and/or any combination thereof;
[0033] "mask body" means an air-permeable structure that is designed to fit over the nose
and mouth of a person and that helps define an interior gas space separated from an
exterior gas space (including the seams and bonds that join layers and parts thereof
together);
[0034] "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;
[0035] "perimeter" means the outer edge of the mask body, which outer edge would be disposed
generally proximate to a wearer's face when the respirator is being donned by a person;
[0036] "pleat" means a portion that is designed to be or is folded back upon itself;
[0037] "polymeric" and "plastic" each mean a material that mainly includes one or more polymers
and that may contain other ingredients as well;
[0038] "plurality" means two or more;
[0039] "respirator" means an air filtration device that is worn by a person to provide the
wearer with clean air to breathe;
[0040] "second side" means an area of the mask body that is located on one side of a plane
that bisects the mask body normal to the cross-wise dimension (the second side being
opposite the first side);
[0041] "snug fit" or "fit snugly" means that an essentially air-tight (or substantially
leak-free) fit is provided (between the mask body and the wearer's face);
[0042] "tab" means a part that exhibits sufficient surface area for attachment of another
component; and
[0043] "transversely extending" means extending generally in the crosswise dimension.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1 is a front perspective view of a filtering face-piece respirator
10, in accordance with the present invention, being worn on a person's face;
[0045] FIG. 2 is a top view of the respirator
10 shown in FIG. 1;
[0046] FIG. 3 is an enlarged top view;
[0047] FIG. 4 is a cross-sectional view of the mask body
12 taken along lines 4-4 of FIG. 2; and
[0048] FIG. 5 is a cross-sectional view of the filtering structure
16 taken along lines 5-5 of FIG. 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0049] In practicing the present invention, a filtering face-piece respirator is provided
that has a grasping feature disposed on the mask body. An indicia is placed on the
grasping feature so that the user can readily learn that that feature is designed
for being grasped by the user during fitment. The grasping feature may comprise first
and second flanges that extend both laterally and frontally from the mask body when
in an open configuration. The first and second flanges provide "handles" on each side
of the mask body to allow the wearer to appropriately position the mask body during
use. The wearer does not need to pinch the mask body to move the mask into a desired
face-fitting position. The flanges thus provide a very handy means for accomplishing
mask adjustment. The indicia acts to inform the user that the flanges are where the
mask body should be grasped during donning, doffing, and adjusting.
[0050] FIG. 1 shows an example of a flat-fold filtering face-piece respirator
10 that may be used in accordance with the present invention to provide clean air for
the wearer to breathe. As illustrated, the filtering face-piece respirator
10 includes a mask body
12 and a harness
14. The mask body
12 has a filtering structure
16 through which inhaled air passes before entering the wearer's respiratory system.
The filtering structure
16 removes contaminants from the ambient environment so that the wearer breathes clean
air. The mask body
12 includes a top portion
18 and a bottom portion
20. The top portion
18 and the bottom portion
20 are separated by a line of demarcation
22. In this particular embodiment, the demarcation line
22 is a pleat that extends transversely across the central portion of the mask body.
The mask body
12 also includes a perimeter that includes an upper segment
24a and a lower segment
24b. The harness
14 has a strap
26 that is stapled to a tab
28a. As illustrated, the tab
28a is an integral part of the flange
30a.
[0051] FIG. 2 shows that the respirator
10 can have first and second flanges
30a and
30b located on opposing sides of the mask body
12. The strap
26 is attached to each tab
28a, 28b using, for example, a staple. The flanges
30a and
30b project both laterally and frontally from the mask body and as such provide a grasping
feature for the user. Each flange projects laterally from the mask body in that it
extends away from a plane
P that bisects the mask body in the x directions. The flanges
30a and
30b also extend frontally from the mask body
12 in that they extend away from the perimeter
24a towards the front edge
22 of the mask body
12 in the direction as noted by arrow y. Each flange typically occupies a surface area
of about 1 to 15 square centimeters (cm
2), more typically about 2 to 12 cm
2, still more typically about 5 to 10 cm
2. Each flange also typically extends away from the mask body at least 2 millimeters
(mm), more typically at least 5 mm, and still more typically at least 1 to 2 centimeters
(cm). The flanges
30a, 30b may be integrally or non-integrally disposed on the mask body and may comprise one
or more or all of the various layers that comprise the mask body. That is, the flanges
may be an extension of the material used to make the mask body, or they may be made
from a separate material such as a rigid or semi-rigid plastic. The flanges
30a, 30b each have an indicia
32a, 32b located on one or more sides of the flanges. As shown, the indicia
32, 32 may be in the form of a fingerprint to inform the user of where the mask body can
be grasped between by user's opposable digits, for example, the thumb and the index
finger. The indicia could take on other shapes and forms, for example concentric circles,
ovals, or rectangles. Alternatively, the indicia could include a hole in the flange
so that the wearer can feel the contact between their opposable digits.
[0052] FIG. 3 shows an example of a hole
33 that may be provided within the indicia 32b. The indicia can be created from a weld
pattern, a printed image, one or more openings, cut slit(s), perforations, tackiness,
or a combination of such things. The indicia typically will occupy a surface area
of about 1 to 6 square centimeters (cm
2), more typically about 2 to 4 cm
2. Although another item such as ink may be added to the surface of the mask body to
create the indicia, the indicia typically is formed integrally and exclusively from
the materials of the mask body itself, for example, as a weld pattern. The indicia
may be a welded pattern that is noticeable on the opposing major surfaces of each
flange - that is, the weld extends through the flange thickness. The layers that comprise
the mask body accordingly may be welded together such that the weld pattern is noticeable
from the top or bottom surface of the grasping feature. An integral flange can have
additional welds or bonds
34 provided thereon to increase flange stiffness. Alternatively, an adhesive layer may
be used between the layers to increase flange stiffness. Using a
Stiffness in Flexure Test set forth below, the flanges may have a flexural modulus of at least 10 Mega Pascals
(MPa), more typically at least 20 MPa when bent along a major surface of the flange.
At the upper end, the flexural modulus is typically less than 100 MPa, more typically
less than 60 MPa. These numbers (i.e., at both the low and high ends) are approximately
twice as large when the test is performed along the edges of the sample. Flange stiffness
may be measured using a modified ASTM D790 method "Flexural Properties of Unreinforced
and Reinforced Plastics and Electrical Insulating Materials," Method I "Three Point
Bend Testing". Flexural Modulus can be calculated according to ASTM D790 in the linear
region of the stress-strain plot. Although the tabs
28a and
28b are illustrated in FIG. 2 as having a shared edge that is part of perimeter segment
24a, the tabs, however may extend beyond the face-contacting periphery part of the mask
body perimeter when the mask is placed upon a wearer's face as shown in FIG. 1. The
face-contacting periphery generally resides within the bracketed area
35 and thus is not part of the tab perimeter. The mask body perimeter may have a series
of bonds or welds
34' to join the various layer of the mask body
12 together. Bond lines
36 also may be provided where the flanges
30a, 30b meet the filtering structure
16. The upper portion
18 may include at least one pleat line
38 that extends from the first side of the mark body to the second side of the mask
body. Examples of other grasping features besides integral flanges may include the
addition of other components attached to the mask body such as flaps, loops, and posts,
and may include: plastic injection molded parts; die cut parts made of plastic, metal,
and/or cellulosic materials; mechanical clip-on devices; adhesively attached devices
made of plastic, metal, and/or cellulosic materials; and mechanically attached devices
such as rivets that are deformed during the attachment process.
U.S. Patent Application 12/338,084 entitled
Flat Fold Respirator Having Flanges Disposed On The Mask Body, discloses an example of a filtering face-piece respirator that uses flanges as grasping
features, suitable for use in the present invention.
[0053] FIG. 4 illustrates an example of a pleated configuration of a mask body
12 that may be used in connection with the present invention. As shown, the mask body
12 includes pleats
22 and
38, already mentioned with reference to FIGs. 1 and 2. The upper portion or panel
18 of the mask body
12 also includes a pleat
40. The lower portion or panel
20 of the mask body
12 includes pleats
42, 44, 46, 48, 50, and
52. The lower portion
20 of the mask body
12 may include more filter media surface area than the upper portion
18. The mask body
12 also includes a perimeter web
54 that is secured to the mask body along its perimeter. A nose clip
56 may be disposed on the upper portion
18 of the mask body centrally, adjacent to the perimeter between the filtering structure
16 and the perimeter web
54. The nose clip
56 may be made from a pliable metal or plastic that is capable of being manually adjusted
by the wearer to fit the contour of the wearer's nose. The perimeter web
54 may be folded over the mask body at the perimeter
24a, 24b. The perimeter web
54 also may be an extension of an inner cover web
58, folded and secured around the edge of
24a and
24b. Alternatively, the perimeter web could be an extension of the outer cover web
60. As shown, the upper portion
18 appears as a pleated panel when the mask body
12 is in a folded condition; similarly the lower portion
20 (FIG. 1) appears as a pleated panel when the mask is in its folded storage condition.
More or less pleats than illustrated may be used in providing a flat-fold filtering
face-piece respirator in accordance with the present invention.
[0054] FIG. 5 illustrates that the filtering structure
16 may include one or more layers such as the inner cover web
58, the outer cover web
60, and a filtration layer
62. The inner and outer cover webs
58 and
60 may be provided to protect the filtration layer
62 and to preclude fibers from the filtration layer
62 from coming loose and entering the mask interior. During respirator use, air passes
sequentially through layers
60, 62, and
58 before entering the mask interior. The air that is disposed within the interior gas
space of the mask may then be inhaled by the wearer. When a wearer exhales, the air
passes in the opposite direction sequentially through layers
58, 62, and
60. Alternatively, an exhalation valve (not shown) may be provided on the mask body to
allow exhaled air to be rapidly purged from the interior gas space to enter the exterior
gas space, minimizing air passage through filtering structure
16. Typically, the cover webs
58 and
60 are made from a selection of nonwoven materials that provide a comfortable feel,
particularly on the side of the filtering structure that makes contact with the wearer's
face. The construction of various filter layers and cover webs that may be used in
conjunction with the support structure of the present invention are described below
in more detail. To improve wearer fit and comfort, an elastomeric face seal can be
secured to the perimeter of the filtering structure
16. Such a face seal may extend radially inward from the perimeter to contact the wearer's
face when the respirator is being donned. Examples of face seals are described in
U.S. Patents 6,568,392 to Bostock et al.,
5,617,849 to Springett et al., and
4,600,002 to Maryyanek et al., and in Canadian Patent
1,296,487 to Yard. The filtering structure also may have a structural netting or mesh juxtaposed against
at least one or more of the layers
58, 60, or
62, typically against the outer surface of the outer cover web
60. The use of such a mesh is described in
U.S. Patent Application Serial No. 12/338,091 filed December 18, 2008, entitled
Expandable Face Mask with Reinforcing Netting.
[0055] A filtering structure that is used in connection with the present invention may take
on a variety of different shapes and configurations. Generally the shape and configuration
of the filtering structure corresponds to the general shape of the mask body. Although
a filtering structure has been illustrated with multiple layers that include a filtration
layer and two cover webs, the filtering structure may simply comprise a filtration
layer or a combination of filtration layers. For example, a pre-filter may be disposed
upstream to a more refined and selective downstream filtration layer. Additionally,
sorptive materials such as activated carbon may be disposed between the fibers and/or
various layers that comprise the filtering structure. Further, separate particulate
filtration layers may be used in conjunction with sorptive layers to provide filtration
for both particulates and vapors. The filtering structure may include one or more
stiffening layers that assist in providing a cup-shaped configuration. The filtering
structure also could have one or more horizontal and/or vertical lines of demarcation
that contribute to its structural integrity.
[0056] The filtering structure that is used in a mask body of the invention can be of a
particle capture or gas and vapor type filter. The filtering structure also 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 (e.g. blood)
from penetrating the filter layer. Multiple layers of similar or dissimilar filter
media may be used to construct the filtering structure of the invention as the application
requires. Filters that may be beneficially employed in a layered mask body of the
invention are generally low in pressure drop (for example, less than about 195 to
295 Pascals at a face velocity of 13.8 centimeters per second) to minimize the breathing
work of the mask wearer. Filtration layers additionally can be flexible and can have
sufficient shear strength so that they generally retain their structure under the
expected use conditions. Examples of particle capture filters 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 meltblowing. Polyolefin microfibers formed from polypropylene
that has been electrically charged are particularly useful for particulate capture
applications. An alternate filter layer may comprise a sorbent component for removing
hazardous or odorous gases from the breathing air. Sorbents may include powders or
granules that are bound in a filter layer by adhesives, binders, or fibrous structures
- see
U.S. Patents 6,334,671 to Springett et al. and
3,971,373 to Braun. A sorbent layer can be formed by coating a substrate, such as fibrous or reticulated
foam, to form a thin coherent layer. Sorbent materials may include activated carbons
that are chemically treated or not, porous alumna-silica catalyst substrates, and
alumna particles. An example of a sorptive filtration structure that may be conformed
into various configurations is described in
U.S. Patent 6,391,429 to Senkus et al.
[0057] The filtration layer is typically chosen to achieve a desired filtering effect. The
filtration layer generally will remove a high percentage of particles and/or or other
contaminants from the gaseous stream that passes through it. For fibrous filter layers,
the fibers selected depend upon the kind of substance to be filtered and, typically,
are chosen so that they do not become bonded together during the molding operation.
As indicated, the filtration layer may come in a variety of shapes and forms; it typically
has a thickness of about 0.2 millimeters (mm) to 10 mm, more typically about 0.3 mm
to 5 mm, and it could be a generally planar web or it could be corrugated to provide
an expanded surface area - see, for example,
U.S. Patents 5,804,295 and
5,656,368 to Braun et al. The filtration layer also may include multiple filtration layers joined together
by an adhesive or any other means. Essentially any suitable material that is known
(or later developed) for forming a filtering layer may be used as the filtering material.
Webs of melt-blown fibers, such as those 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 (µm) (referred to as BMF for "blown microfiber"), typically
about 1 to 12 µm. Effective fiber diameter may be determined according to Davies,
C. N.,
The Separation OfAirborne Dust Particles, Institution Of Mechanical Engineers, London, Proceedings 1B, 1952. Particularly preferred
are BMF webs that contain fibers formed from polypropylene, poly(4-methyl-1-pentene),
and combinations thereof. Electrically charged fibrillated-film fibers as taught in
van Turnhout,
U.S. Patent Re. 31,285, also may 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 imparted to the fibers by corona charging as disclosed
in
U.S. Patent 4,588,537 to Klasse et al. or by tribocharging 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 fiber surfaces in the filter
layer to improve filtration performance in an oily mist environment - see
U.S. Patents 6,398,847 B1,
6,397,458 B1, and
6,409,806 B1 to Jones et al. Typical basis weights for electret BMF filtration layers are about 10 to 100 grams
per square meter. When electrically charged according to techniques described in,
for example, the '507 Angadjivand et al. patent, and when including fluorine atoms
as mentioned in the Jones et al. patents, the basis weight may be about 20 to 40 g/m
2 and about 10 to 30 g/m
2, respectively.
[0058] An inner cover web can be used to provide a smooth surface for contacting the wearer's
face, and an outer cover web can be used to entrap loose fibers in the mask body or
for aesthetic reasons. The cover web typically does not provide any substantial filtering
benefits to the filtering structure, although it can act as a pre-filter when disposed
on the exterior (or upstream to) the filtration layer. To obtain a suitable degree
of comfort, an inner cover web typically has a comparatively low basis weight and
is formed from comparatively fine fibers. More particularly, the cover web may be
fashioned to have a basis weight of about 5 to 50g/m
2 (typically 10 to 30g/m
2), and the fibers used often have an average fiber diameter of about 5 to 24 micrometers,
typically of about 7 to 18 micrometers, and more typically of about 8 to 12 micrometers.
Suitable materials for the cover web may be blown microfiber (BMF) materials, particularly
polyolefin BMF materials, for example polypropylene BMF materials (including polypropylene
blends and also blends of polypropylene and polyethylene) and spun-bond fibers. Cover
webs that are used in the invention preferably have very few fibers protruding from
the web surface after processing and therefore have a smooth outer surface. Examples
of cover webs that may be used in the present invention are disclosed, for example,
in
U.S. Patent 6,041,782 to Angadjivand,
U.S. Patent 6,123,077 to Bostock et al., and
WO 96/28216A to Bostock et al.
[0059] The strap(s) that are used in the harness may be made from a variety of materials,
such as thermoset rubbers, thermoplastic elastomers, braided or knitted yarn/rubber
combinations, inelastic braided components, and the like. The strap(s) may be made
from an elastic material such as an elastic braided material. The strap preferably
can be expanded to greater than twice its total length and be returned to its relaxed
state. The strap also could possibly be increased to three or four times its relaxed
state length and can be returned to its original condition without any damage thereto
when the tensile forces are removed. The elastic limit thus is preferably not less
than two, three, or four times the length of the strap when in its relaxed state.
Typically, the strap(s) are about 20 to 30 cm long, about 3 to 10 mm wide, and about
0.9 to 1.5 mm thick. The strap(s) may extend from the first tab to the second tab
as a continuous strap or the strap may have a plurality of parts, which can be joined
together by further fasteners or buckles. For example, the strap may have first and
second parts that are joined together by a fastener that can be quickly uncoupled
by the wearer when removing the mask body from the face. An example of a strap that
may be used in connection with the present invention is shown in
U.S. Patent 6,332,465 to Xue et al. Examples of fastening or clasping mechanisms that may be used to joint one or more
parts of the strap together are shown, for example, in the following
U.S. Patents: 6,062,221 to Brostrom et al.;
5,237,986 to Seppala; and
EP1,495,785A1 to Chien.
[0060] An exhalation valve also may be attached to the mask body to facilitate purging exhaled
air from the interior gas space. The use of an exhalation valve may improve wearer
comfort by rapidly removing the warm moist exhaled air from the mask interior. See,
for example,
U.S. Patents 7,188,622,
7,028,689, and
7,013,895 to Martin et al.;
7,428,903,
7,311,104,
7,117,868,
6,854,463,
6,843,248, and
5,325,892 to Japuntich et al.;
6,883,518 to Mittelstadt et al.; and
RE37,974 to Bowers. Essentially any exhalation valve that provides a suitable pressure drop and that
can be properly secured to the mask body may be used in connection with the present
invention to rapidly deliver exhaled air from the interior gas space to the exterior
gas space.
[0061] A nose clip that is used in conjunction with the present invention may be essentially
any additional part that assists in improving the fit over the wearer's nose. Because
there are substantial changes in contour to the wearer's face in this region, a nose
clip can better assist the mask body in achieving the appropriate fit in this location.
The nose clip may comprise, for example, a pliable dead soft band of metal such as
aluminum, which can be shaped to hold the mask in a desired fitting relationship over
the nose of the wearer and where the nose meets the cheek. An example of a suitable
nose clip is shown in
U.S. Patent 5,558,089 and Des.
412,573 to Castiglione. Other nose clips are described in
U.S. Patent Application 12/238,737 (filed September 26, 2008);
U.S. Publications 2007-0044803A1 (filed August 25, 2005); and
2007-0068529A1 (filed September 27, 2005).
[0062] Although the present invention has been described with reference to a particular
flat-fold mask, the invention may be used in conjunction with flat-fold masks that
have other configurations - such as those shown in
U.S. Patents 7,069,930 to Bostock et al. and
6,394,090 to Chen, or it may be used in conjunction with molded masks - see for example
U.S. Patents 7,131,442 to Kronzer et al.,
6,923,182 to Angadjivand et al, and
6,827,764 to Springett et al. The invention also may be used in connection with the molded masks cited above.
EXAMPLE
[0063] A respirator filtering structure was formed from three layers of nonwoven material
and other respirator components. The mask was assembled in two main operations - preform
making and mask finishing. The preform making stage included the steps of lamination
and fixing of nonwoven fibrous webs, formation of pleat crease lines, and attachment
of the nose clip. The mask finishing operation included folding of pleats along embossed
crease lines, fusing the lateral mask edges with the claimed indicia feature, cutting
the tab into its final form, and attaching the headband.
[0064] The body of the respirator was formed from three layers of nonwoven material: outer
cover web (205 mm x 300 mm); a filter material (205 mm x 300 mm); and an inner cover
web (238 mm x 300 mm). The outer and inner cover webs were a 34 grams per square meter
(gsm) polypropylene spun-bonded nonwoven. The filter material used in the mask body
was an electret-charged blown microfiber polypropylene web that had a basis weight
of 59 gsm, a solidity of 6%, and an effective fiber diameter of 7.5 micrometers.
[0065] The respirator body was made by plying each of the layers, which was then ultrasonically
welded together using a point-bonded pattern. Ultrasonic welding was accomplished
using an ultrasonic welding unit, Model 2000, from Branson, Danbury, Connecticut,
operated at a ram pressure of 483 kilo pascals (kPa) with a horn amplitude, frequency,
and dwell time of 100%, 20 kilohertz (kHz) and 0.6 sec respectively. Operating against
an anvil with flat-top square pegs, having individual face areas of 1.6 square millimeters
arranged in a grid pattern with spacing of approximately one centimeter on center
of the pegs, the flat-faced horn of the welder acted against the anvil at a contact
pressure of approximately 6 MPa. With the layers of nonwoven fixed, crease lines that
define pleat location were embossed on the fixed layers of nonwoven. Embossing of
the crease lines was done using a die cutting machine, Hytronic Cutting Machine Model
B, from USM Corporation, Haverhill, Massachusetts, at 15 tons of force and with a
crease rule die. The die had nine bars with radius edges that traversed the length
of the preform and when pressed into the preform created lines into the nonwoven layers.
The embossed lines compressed the webs together at the point of contact but did not
penetrate or significantly fuse the material.
[0066] As a final step in the preform making operation, the extending edges of the inner
coverweb were wrapped around the edges of the preform and ultrasonically welded into
place. Ultrasonic welding was carried out using an ultrasonic welding unit Model 2000X
from Branson, Danbury, Connecticut, operated at a ram pressure of 448 kPa with a horn
amplitude, frequency, and dwell time of 100%, 20 kHz, and 0.5 sec, respectively. Operating
against an anvil with a contact surface area of 4.1 square centimeters, using the
specified ram pressure and horn conditions, resulted in contact pressures of 8.5 MPa
to bond the materials of the preform. The area of the anvil used to bond the perimeter
edge of the preform was configured in flat-top square pegs, having individual face
areas of 1.6 square millimeters that were arranged in a pattern 34' as shown in FIG.
2. The flat-faced horn of the welder acted against an anvil, fixing the perimeter
web to the preform. Using this process, a nose clip was attached to the top of the
preform and was encapsulated between the outer coverweb and the folded over edge of
the inner coverweb. The nose clip was a malleable, plastically-deformable aluminum
strip that had the shape shown in FIG. 2 and was 9 cm long by 0.5 cm wide by 1 mm
thick.
[0067] In the mask finishing operation, pleats were folded along crease lines as shown in
FIG. 4. Pleats located above the central fold of the mask, were folded such that the
exterior folds faced downwards with the mask open; this was done to help prevent accumulation
of gross matter in the mask folds when worn. With the preform properly pleated and
folded around the center fold, the preform was ultrasonically welded to fuse the lateral
edges of the mask
(28a and
28b in FIG. 2) and to create the bonded layers of the stiffening flange which includes
the grasping indicia
(32a and
32b in FIG. 2). Ultrasonic welding was done using an ultrasonic welding unit Model 2000x
also from Branson, operated at a ram pressure of 483 kPa with a horn amplitude, frequency,
and dwell time of 100%, 20kHz, and .8 sec, respectively. The contact area of the anvil
for bonding the flange material was configured with flat-top square pegs, having individual
face areas of 1.04 square millimeters that were spaced 2.88 millimeters apart from
their flat sides, and included the shape of the claimed indicia. The resultant bond
pattern is indicated as 30a in FIG. 2. The anvil bars that formed the lateral edge
bonds of the mask were 95.25 millimeters long and 9.525 millimeters wide, with the
resulting bond pattern indicated as 36 in FIG. 2. The flat-faced horn of the welder
acted against the anvil resulting in the formation of an indicia weld pattern shown
in FIGS. 2 and 3) and created the bonded layers of the flanges. Angled bar elements
of the anvil sealed the lateral edges of the mask and pin welding surfaces fused and
stiffened the flange material. As a final step in the mask finishing operation, the
stiffening flanges were cut to a desired shape, and a headband was stapled to the
tabs. Flanges were 1.0 cm wide by 5.0 cm long with a 0.5 cm radius head located at
the tab point of attachment of the headband. The headband was attached to the tabs
radius head using a hand stapler from Stanley Bostitch, East Greenwich, Rhode Island,
Model P6C-8 and staples No. STH5019 1/4 inch galvanized. Sections of the flange were
cut from the mask and tested according to the method outlined in
Stiffness in Flexure Test. The flange sections were tested in two orientations: along the flat plane of the
sample and along the edge of the sample as it would be oriented along the length of
the flange. When bent along the flat plane of the sample, the flexural modulus was
27 MPa. When tested along the edge of the sample, it was 66 MPa. The headband was
7.9 mm wide by 0.8 mm thick, Sample No. 125-1 from Providence Braid Co., Pawtucket,
Rhode Island. The flanges were able to rotate on an axis parallel to the line of attachment
to the mask body and provided a more rigid mask body when opened and donned. The indicia
disposed on the flanges was readily visible as an indication of where to grasp the
mask body.
[0068] This invention may take on various modifications and alterations without departing
from its spirit and scope. Accordingly, this invention is not limited to the above-described
but is to be controlled by the limitations set forth in the following claims and any
equivalents thereof.
[0069] This invention also may be suitably practiced in the absence of any element not specifically
disclosed herein.
[0070] 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.