U.S. patent application number 13/727983 was filed with the patent office on 2014-07-03 for filtering face-piece respirator having welded indicia hidden in pleat.
This patent application is currently assigned to 3M INNOVATIVE PROPERTIES COMPANY. The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Dean R. Duffy.
Application Number | 20140182600 13/727983 |
Document ID | / |
Family ID | 51015732 |
Filed Date | 2014-07-03 |
United States Patent
Application |
20140182600 |
Kind Code |
A1 |
Duffy; Dean R. |
July 3, 2014 |
FILTERING FACE-PIECE RESPIRATOR HAVING WELDED INDICIA HIDDEN IN
PLEAT
Abstract
A filtering face-piece respirator 10 that comprises a harness 14
and a mask body 12 that has a pleats 21. The mask body 12 has an
indicia 19 located within the pleat 21 in at least a partially
non-visible location when the pleat 21 is folded. The indicia 19 is
made from a weld pattern and is fully visible when the pleat 21 is
unfolded. The fully visible indicia 19 provides an indication to
the wearer that the mask body is in its proper unfolded condition.
The indicia 19 also includes welded lines that extend normally
across the pleat to improve collapse resistance.
Inventors: |
Duffy; Dean R.; (Woodbury,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Assignee: |
3M INNOVATIVE PROPERTIES
COMPANY
St. Paul
MN
|
Family ID: |
51015732 |
Appl. No.: |
13/727983 |
Filed: |
December 27, 2012 |
Current U.S.
Class: |
128/863 |
Current CPC
Class: |
A41D 13/1115
20130101 |
Class at
Publication: |
128/863 |
International
Class: |
A41D 13/11 20060101
A41D013/11 |
Claims
1. A filtering face-piece respirator that comprises: (a) a harness;
and (b) a mask body that has a filtering structure that contains
one or more pleats, a welded indicia is located within the pleat(s)
in at least a partially non-visible location when the pleat is
folded, the indicia being fully visible when the pleat is
unfolded.
2. The filtering face-piece respirator of claim 1, wherein the
indicia includes at least one line that extends across the fold
line of the pleat.
3. The filtering face-piece respirator of claim 2, wherein the at
least one line that extends across the fold line of the pleat is
normal to the fold line.
4. The filtering face-piece respirator of claim 3, wherein the at
least one line that extends normally across the fold line of the
pleat is at least one centimeter long.
5. The filtering face-piece respirator of claim 4, wherein the at
least one line that extends normally across the fold line of the
pleat is at least two cm long.
6. The filtering face-piece respirator of claim 5, wherein the at
least one line that extends normally across the fold line of the
pleat includes at least two closely-spaced parallel weld lines.
7. The filtering face-piece respirator of claim 6, wherein the
indicia comprises a trademark of the respirator manufacturer.
8. The filtering face-piece respirator of claim 5, wherein the
indicia includes a numeral, a letter, or a combination thereof
9. The filtering face-piece respirator of claim 2, wherein the
filtering structure comprises a plurality of layers which includes
a filtering layer and first and second cover webs, and wherein the
indicia is a weld pattern that is made by welding the plurality of
layers that comprise the filtering structure together.
10. The filtering face-piece respirator of claim 2, wherein the
indicia comprises closely-spaced parallel lines that are spaced
apart by a distance of about 0.5 to 5 millimeters (mm), the spaced
parallel weld lines are at least 1 cm in length, and wherein the
indicia is 0.5 to 2 centimeters (cm) high by up to about 0.5 to 4
centimeters (cm) wide.
11. The filtering face-piece respirator of claim 2, wherein the
total width of single or a parallel set of weld lines is 1.5 mm to
7.0 mm.
12. The filtering face-piece respirator of claim 5, wherein the
indicia is ultrasonically welded into the filtering structure, and
wherein the indicia is 1 to 2 cm high by 2 to 3 cm wide.
13. The filtering face-piece respirator of claim 6, wherein the
region between each of the weld lines may be densified such that
the thickness of the plurality of layers of the nonwoven material
between the parallel weld lines is less than the thickness of those
layers outside the weld lines.
14. The filtering face-piece respirator of claim 2, wherein the
mask body comprises a plurality of transversely extending pleats,
and wherein there is a indicia in the plurality of pleats.
15. The filtering face-piece respirator of claim 2, wherein the
indicia is located in a pleat that extends transversely across the
mask body from a first side to a second side.
16. A filtering face-piece respirator that comprises: (a) a
harness; and (b) a mask body that has a filtering structure that
comprises a plurality of layers, which plurality of layers includes
a filtering layer and first and second cover webs, the filtering
structure also containing one or more transversely-extending
pleats, a welded indicia is located within the pleat(s) in at least
a partially non-visible location when the pleat is folded, the
indicia being fully visible when the pleat is unfolded, wherein the
welded indicia is made by welding the plurality of layers that
comprise the filtering structure together, and wherein the indicia
comprises at least line that is at least one centimeter long and
extends across the pleat normally thereto.
Description
[0001] The present invention pertains to a filtering face-piece
respirator that has a welded indicia hidden in a pleat of the
filtering structure. The welded indicia becomes visible when the
pleat is opened into its in use configuration.
BACKGROUND
[0002] Respirators are commonly worn over a person's breathing
passages for at least one of two common purposes: (1) to prevent
impurities or contaminants from entering the wearer's respiratory
system; 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 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 mask bodies in conjunction with attachable
filter cartridges (see, e.g., U.S. Pat. No. RE39,493 to Yuschak et
al.) or insert-molded filter elements (see, e.g., U.S. Pat. No.
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.
These 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-bonding 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. These respirators therefore cannot be
folded flat for storage and shipping. Examples of patents that
disclose molded, filtering, face-piece respirators include U.S.
Pat. No. 7,131,442 to Kronzer et al, U.S. Pat. Nos. 6,923,182,
6,041,782 to Angadjivand et al., U.S. Pat. No. 4,807,619 to Dyrud
et al., and U.S. Pat. No. 4,536,440 to Berg.
[0005] Flat-fold respirators--as their name implies--can be folded
flat for shipping and storage. They also can be opened into a
cup-shaped configuration for use. Examples of flat-fold respirators
are shown in U.S. Pat. Nos. 6,568,392 and 6,484,722 to Bostock et
al., and U.S. Pat. No. 6,394,090 to Chen.
[0006] Although flat-fold respirators are convenient in that they
can be folded flat for shipping and storage, persons using these
respirators must take care to ensure that the mask body is properly
opened into its in-use configuration. If the mask is so opened
properly, for example, if some of the pleats remain closed, the
respirator may not make full use of its available surface area for
filtering. Such a situation could cause an increase in pressure
drop or a decrease in product service life. The mask body also may
not be fully spaced from the wearer's face, making the respirator
touch the wearer's face, causing comfort issues.
SUMMARY OF THE INVENTION
[0007] The present invention provides a filtering face-piece
respirator that comprises a harness and a mask body that has a
filtering structure that contains one or more pleats. The mask body
has an indicia located within the pleat(s) in at least a partially
non-visible location when the pleat is folded. The indicia is made
from a weld pattern and is fully visible when the pleat is
unfolded.
[0008] The present invention is beneficial in that the fully
visible indicia provides an indication to the wearer that the mask
body is in its properly unfolded condition. When the indicia is
hidden or non-visible, the wearer is, in effect, notified that the
mask body is not in its proper open configuration for use. The
wearer can then make adjustments to the mask body to cause the
pleat to become fully opened so that the full surface area of the
mask body can be available for filtration. The indicia, because it
is welded into the pleated filtering structure also assists in
keeping the pleat in its open configuration once expanded. The weld
pattern can provide a beam-type affect across the pleat which
assists in keeping it open.
Glossary
[0009] The terms set forth below will have the meanings as
defined:
[0010] "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 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;
[0011] "clean air" means a volume of atmospheric ambient air that
has been filtered to remove contaminants;
[0012] "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;
[0013] "crosswise dimension" is the dimension that extends
laterally across the respirator, from side-to-side when the
respirator is viewed from the front;
[0014] "cup-shaped configuration" means any vessel-type shape that
is capable of adequately covering the nose and mouth of a
person;
[0015] "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;
[0016] "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;
[0017] "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;
[0018] "filter media" means an air-permeable structure that is
designed to remove contaminants from air that passes through
it;
[0019] "filtering structure" means a generally air-permeable
construction that filters air;
[0020] "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;
[0021] "flange" means a protruding part that imparts structural
integrity or strength to the body from which it protrudes;
[0022] "folded inwardly" means being bent back towards the part
from which extends;
[0023] "frontally" means extending away from the mask body
perimeter;
[0024] "harness" means a structure or combination of parts that
assists in supporting the mask body on a wearer's face;
[0025] "hidden" means not visible or only partially visible;
[0026] "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;
[0027] "interior gas space" means the space between a mask body and
a person's face;
[0028] "leading edge" an unattached edge;
[0029] "line of demarcation" means a fold, seam, weld line, bond
line, stitch line, hinge line, and/or any combination thereof;
[0030] "major portion" means the cup-shaped portion of the mask
body;
[0031] "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);
[0032] "match" means to substantially follow a similar path as;
[0033] "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;
[0034] "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;
[0035] "pleat" means a portion that is designed to be or is folded
back upon itself;
[0036] "polymeric" and "plastic" each mean a material that mainly
includes one or more polymers and that may contain other
ingredients as well;
[0037] "plurality" means two or more;
[0038] "respirator" means an air filtration device that is worn by
a person to provide the wearer with clean air to breathe;
[0039] "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);
[0040] "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);
[0041] "tab" means a part that exhibits sufficient surface area for
attachment of another component; and
[0042] "transversely extending" means extending generally in the
crosswise dimension.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1 is a front perspective view of a flat-fold filtering
face-piece respirator 10, in accordance with the present invention,
being worn on a person's face;
[0044] FIG. 2a is a top view of the respirator 10 of FIG. 1,
showing the upper pleat 19 in a folded condition ;
[0045] FIG. 2b is a top view of the respirator 10 shown in FIG. 1,
showing the upper pleat 19 in a opened configuration;
[0046] FIG. 3 is a cross-sectional view of the mask body 12 taken
along lines 3-3 of FIG. 2a;
[0047] FIG. 4 is a cross-sectional view of the filtering structure
16 taken along lines 4-4 of FIG. 3; and
[0048] FIG. 5 is a front view of the mask body 12, which may be
used in connection with the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0049] In practicing the present invention, a filtering face-piece
respirator is provided where an indicia made from a weld pattern
and becomes fully visible when the pleat is unfolded. The fully
visible pleat provides an indication to the wearer that the mask
body is in its proper unfolded condition for use over a wearer's
nose and mouth. The welded indicia is further beneficial in that it
helps keep the pleated mask body in its expanded shape during
use.
[0050] FIG. 1 shows an example of a filtering face-piece respirator
10 that may be used in connection with the present invention to
provide clean air for the wearer to breathe. 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 must pass 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. A welded indicia
pattern 19 (in this instance it includes the capital letter "A") is
seen on the top portion 18 when the mask body is opened in an
in-use configuration. The indicia 19 becomes visible when the pleat
21 (FIGS. 2a and 2b) is unfolded. The top portion 18 and the bottom
portion 20 are separated by a line of demarcation 22. In this
particular embodiment, the line of demarcation 22 is a fold or
pleat that extends transversely across the central portion of the
mask body from side-to-side. The mask body 12 also includes a
perimeter 24 that includes an upper segment 24a and a lower segment
24b. The harness 14 also has a first and second straps 26 and 27
that are secured to a first flange 30a. The harness straps 26, 27
each have first and second ends 29a, 29b that are secured to the
first flange 30a in a spaced apart relationship so that the first
strap 26 has a first segment that follows a path above the wearer's
ear and the second strap 27 has a second segment that follows a
path below the wearer's ear when the respirator is being donned.
The straps 26, 27 are each placed in tension when the respirator is
donned, and such tension, particularly the tension on strap 27,
causes the flaps 30a to be folded downwardly into contact with the
major portion 28 of mask body 12 during respirator use.
[0051] FIG. 2a shows the mask body 12 in a condition where the
pleat 21 is folded thereby hiding the indicia 19 (FIGS. 1, 2b) from
view. A second flange 30b is shown on an opposing side 31b of the
mask body 12 from side 31a. A plane 32 bisects the mask body 12 to
define the first and second sides 31a, 31b. The flanges 30a, 30b
can have welds or bonds 35 provided thereon to increase flange
stiffness. The flanges 30a, 30b may be integrally or non-integrally
connected to the major portion of the mask body 12 and may comprise
one or more or all of the various layers that comprise the mask
body filtering structure 16. The mask body perimeter 24a also may
have a series of bonds or welds 35 to join the various layers of
the mask body 12 together. The perimeter therefore may not be very
fluid permeable. The remainder of the filtering structure
16--inwardly from the perimeter--may be fully fluid permeable over
much of its extended surface, with the possible exception of areas
where there are bonds, welds, or fold lines. The mask body 12 also
includes first and second lines of demarcation 36a, 36b located on
first and second sides of the mask body 12. The first and second
flanges 30a, 30b are joined to the mask body 12 at the first and
second lines of demarcation 36a, 36b and may be rotated or folded
about an axis generally parallel to these demarcation lines,
respectively. The top portion 18 of the mask body 12 may include
one or more pleat lines that extend from the first line of
demarcation 36a to the second line of demarcation 36b
transversely.
[0052] FIG. 2b shows the pleat 21 being opened so that the indicia
19 "Al" located therein can be seen. When the mask is in a non-use
condition, the indicia 19 is located within the folded pleat 31 not
visible from the exterior. Once the pleat 21 is opened, however,
the indicia 19 is visible from the front of the mask body 12.
Having seen the indicia 19, the wearer can be assured that the
upper portion 18 of the mask body 12 is adequately opened and ready
for use. Similar or other indicia may be used in the other pleats
of the upper and lower portions 18 and 20 to provide indications
that those pleats are in a full open position as well.
[0053] FIG. 3 illustrates an example of a pleated configuration of
a mask body 12 in accordance with the present invention. As shown,
the upper portion or panel 18 of the mask body 12 may include the
inner pleat 21 in which the indicia 19 is hidden when the pleat 21
is folded. The upper panel 18 also has an outer pleat 38 and half
of the outer fold 22, which separates the upper portion 18 from the
lower portion 20. The lower portion or panel 20 of the mask body 12
may include pleats 42 and 44 and half of pleat 22. Pleat 22
separates the upper and lower portions 18 and 20 of mask body 12.
The lower portion 20 of the mask body 12 may include less, more, or
the same amount of filter media surface area as the upper portion
18. The mask body 12 also may include a perimeter web that is
secured to the mask body along its perimeter. The perimeter web may
be folded over the mask body at the perimeter 24a, 24b. The
perimeter web also may be an extension of an inner cover web folded
and secured around the edge of 24a and 24b. A nose clip 56 (FIG. 5)
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. The nose clip 56 may be made from a pliable
metal or plastic that is capable of being manually adapted by the
wearer to fit the contour of the wearer's nose.
[0054] FIG. 4 shows that the filtering structure 16 may include one
or more layers such as an inner cover web 58, an 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 body 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 without passing 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 mask body perimeter to
contact the wearer's face when the respirator is being donned.
Examples of face seals are described in U.S. Pat. No. 6,568,392 to
Bostock et al., U.S. Pat. No. 5,617,849 to Springett et al., and
U.S. Pat. No. 4,600,002 to Maryyanek et al., and in Canadian Patent
1,296,487 to Yard. The mask body perimeter 24 also may be folded
upon itself in the nose region to achieve a snug fit--see U.S.
Patent Application Publication 2011/0315144A1. FIG. 5 shows the
mask body 12 in an in-use configuration. During use, the pleat 19
on the major portion 28 of mask body 12 is opened so that the
indicia "A1" is fully visible from a front view of the mask body
12. The indicia 19 may include a combination of numerals and/or
letters or any other characters suitable to be visible to a person
when the pleat 19 is opened. The indicia 19 also may be a trademark
such as the brand identifier of the respirator manufacturer. The
indicia 19 therefore may be, for example, the trademark "3M",
representing the company who makes the inventive respirator. The
indicia 19 is made from a weld pattern that is disposed on the
major portion 28 of the mask body 12. The weld pattern can be made
by welding the various layers that comprise the filtering structure
16. The welding can be achieved using, for example, an ultrasonic
welder, which causes the polymeric materials in the filtering
layers and cover webs to melt and bond to each other. Weld lines
may be created using ultrasonic welding in either a "plunge" or
"rotary" welding process. In general, a vibrating horn on the
ultrasonic welder causes the filtering structure 16 to compress,
melt, and then solidify in a region that is against an anvil that
contains the weld line pattern. This process can take a filtering
structure 16 with an original thickness A and bond it together to a
thickness C (thickness C being less than thickness A) in the
regions of contact between the horn and anvil. In plunge welding,
the horn and anvil typically come into contact in an up and down
motion with the filtering structure 16 in-between these parts;
while in rotary welding, the filtering structure 16 is continuously
fed between the horn and anvil in a rotary fashion. Other means are
possible to bond the filtering structure 16 into weld lines, such
as using heat and pressure with appropriate tooling. Ultrasonic
welders suitable for making the indicia, perimeter welds, and other
weld lines include the ultrasonic welders sold by Emerson
Industrial Automation under the Branson.TM. brand. The indicia
includes at least one line 64 that extends across the fold line 66
of the pleat. The at least one line 64 that extends across the fold
line 66 of the pleat 21 may be normal (or at least generally
normal) to the fold line to improve the collapse resistance of the
mask body 12. The at least one line that extends normally across
the fold line of the pleat is at least one centimeter long, more
typically at least two cm long. The characters that comprise the
indicia may be a of the single solid line type or that may be of a
parallel line configuration like the lines disclosed in U.S. Patent
application 2011/0094515 A1 to Duffy. The parallel lines may be
spaced apart by a distance of about 0.5 to 5 millimeters (mm) More
preferably, the parallel weld lines are spaced apart about 1 to
4mm, and still more preferably are spaced apart at about 1.5 to 3
mm. Typically, the spaced parallel weld lines are at least 0.5 cm
long, and more typically greater than 1 cm long. The indicia may be
about 0.5 to 2 centimeters (cm) high by up to about 0.5 to 4
centimeters (cm) wide. More typically, the indicia 19 is about 1 to
2 cm high by 2 to 3 cm wide. The weld lines may be created such
that the various layers of the filtering structure are fused
together to stiffen those layers in the weld line. Three or more
parallel weld lines also may be used in a spaced apart relationship
to create two or more substantially continuous regions between the
weld lines. The weld lines that comprise the indicia also may
assist in keeping the pleat in its unfolded condition for use to
increase collapse resistance of the respirator mask body. Increased
densification in the weld lines and in regions disposed between
closed welded areas may improve the beam stiffness and hence the
collapse resistance of the major portion 28 of mask body 12. The
region between each of the weld lines may be densified such that
the thickness of the plurality of layers of the nonwoven material
between the weld lines is less than the thickness of those layers
outside the weld lines. The thickness of the layer(s) of nonwoven
fibrous media that comprise the filtering structure 16 typically
has a thickness of about 0.3 mm to 5 mm, more typically about 0.5
mm to 2.0 mm, and still more typically about 0.75 mm to 1.5 mm. If
parallel weld lines are used, each individual weld line in the
parallel set may have a width dimension that may be about 0.5 to 2
mm wide, more commonly about 0.75 to 1.5 mm wide. The total width
of single or parallel weld lines (taken in combination) typically
is about 1.5 mm to 7.0 mm, more typically is about 2.0 mm to 5 mm,
and still more typically is about 2.5 mm to 4.0 mm.
The Filtering Structure
[0055] The filtering structure that is used in connection with the
present invention may take on a variety of different shapes and
configurations. The filtering structure typically is adapted so
that it properly fits against or within the support structure.
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.
The first and second flanges when used in accordance with the
present invention, however, may make unnecessary the need for such
stiffening layers and lines of demarcation.
[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 may be
flexible and may 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 provide particular utility 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. Pat. No. 6,334,671 to Springett et al.
and U.S. Pat. No. 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. Pat. No. 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 and
typically has a thickness of about 0.2 millimeters (mm) to 1
centimeter (cm), more typically about 0.3 mm to 0.5 cm, and it
could be a generally planar web or it could be corrugated to
provide an expanded surface area--see, for example, U.S. Pat. Nos.
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 (.mu.m) (referred to
as BMF for "blown microfiber"), typically about 1 to 12 .mu.m.
Effective fiber diameter may be determined according to Davies, C.
N., The Separation Of Airborne Dust Particles, Institution Of
Mechanical Engineers, London, Proceedings 1B, 1952. Particularly
preferred are BMF 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. Pat. No. 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. Pat. No.
6,824,718 to Eitzman et al., U.S. Pat. No. 6,783,574 to Angadjivand
et al., U.S. Pat. No. 6,743,464 to Insley et al., U.S. Pat. Nos.
6,454,986 and 6,406,657 to Eitzman et al., and U.S. Pat. Nos.
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. Pat. No. 4,588,537 to Klasse et al. or by tribocharging as
disclosed in U.S. Pat. No. 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. Pat. No.
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. Pat. Nos. 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.sup.2 and about 10 to 30
g/m.sup.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 preferably 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 50
g/m.sup.2 (typically 10 to 30 g/m.sup.2), and the fibers may be
less than 3.5 denier (typically less than 2 denier, and more
typically less than 1 denier but greater than 0.1). Fibers used in
the cover web 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. The cover web material may
have a degree of elasticity (typically, but not necessarily, 100 to
200% at break) and may be plastically deformable.
[0059] 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). A suitable process
for producing BMF materials for a cover web is described in U.S.
Pat. No. 4,013,816 to Sabee et al. The web may be formed by
collecting the fibers on a smooth surface, typically a
smooth-surfaced drum or a rotating collector--see U.S. Pat. No.
6,492,286 to Berrigan et al. Spun-bond fibers also may be used.
[0060] A typical cover web may be made from polypropylene or a
polypropylene/polyolefin blend that contains 50 weight percent or
more polypropylene. These materials have been found to offer high
degrees of softness and comfort to the wearer and also, when the
filter material is a polypropylene BMF material, to remain secured
to the filter material without requiring an adhesive between the
layers. Polyolefin materials that are suitable for use in a cover
web may include, for example, a single polypropylene, blends of two
polypropylenes, and blends of polypropylene and polyethylene,
blends of polypropylene and poly(4-methyl-1-pentene), and/or blends
of polypropylene and polybutylene. One example of a fiber for the
cover web is a polypropylene BMF made from the polypropylene resin
"Escorene 3505G" from Exxon Corporation, providing a basis weight
of about 25 g/m.sup.2 and having a fiber denier in the range 0.2 to
3.1 (with an average, measured over 100 fibers of about 0.8).
Another suitable fiber is a polypropylene/polyethylene BMF
(produced from a mixture comprising 85 percent of the resin
"Escorene 3505G" and 15 percent of the ethylene/alpha-olefin
copolymer "Exact 4023" also from Exxon Corporation) providing a
basis weight of about 25 g/m.sup.2 and having an average fiber
denier of about 0.8. Suitable spunbond materials are available,
under the trade designations "Corosoft Plus 20", "Corosoft Classic
20" and "Corovin PP-S-14", from Corovin GmbH of Peine, Germany, and
a carded polypropylene/viscose material available, under the trade
designation "3 70/15", from J. W. Suominen OY of Nakila,
Finland.
[0061] 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. Pat. No. 6,041,782 to Angadjivand, U.S. Pat. No.
6,123,077 to Bostock et al., and WO 96/28216A to Bostock et al.
Respirator Components
[0062] 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, 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. Pat. No. 6,332,465 to Xue et al. Examples of fastening or
clasping mechanism that may be used to joint one or more parts of
the strap together is shown, for example, in the following U.S.
Pat. No. 6,062,221 to Brostrom et al., U.S. Pat. No. 5,237,986 to
Seppala, and EP1,495,785A1 to Chien. The harness also may be in the
form of a reusable carriage or an adhesive layer that is provided
on the internal surface of the perimeter.
[0063] As indicated, an exhalation valve 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. Pa. Nos. 7,188,622, 7,028,689, and 7,013,895
to Martin et al.; U.S. Pat. Nos. 7,428,903, 7,311,104, 7,117,868,
6,854,463, 6,843,248, and 5,325,892 to Japuntich et al.; U.S. Pat.
No. 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.
[0064] A nose clip that is used in the present invention may be
essentially any additional part that assists in improving the fit
over the wearer's nose. Because the wearer's face exhibits in the
nose region, a nose clip may be used to better assist 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. Pat.
No. 5,558,089 and Des. 412,573 to Castiglione. Other nose clips are
described in U.S. patent application Ser. No. 12/238,737 (filed
Sep. 26, 2008); U.S. Publications 2007-0044803A1 (filed Aug. 25,
2005); and 2007-0068529A1 (filed Sep. 27, 2005).
[0065] 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
[0066] This invention also may be suitably practiced in the absence
of any element not specifically disclosed herein.
[0067] 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.
* * * * *