U.S. patent application number 14/775420 was filed with the patent office on 2016-01-21 for a facemask having one or more nanofiber layers.
The applicant listed for this patent is Matthew CONLON, CROSSTEX INTERNATIONAL, INC.. Invention is credited to Matthew CONLON.
Application Number | 20160015098 14/775420 |
Document ID | / |
Family ID | 51537383 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160015098 |
Kind Code |
A1 |
CONLON; Matthew |
January 21, 2016 |
A FACEMASK HAVING ONE OR MORE NANOFIBER LAYERS
Abstract
Facemasks and methods utilizing nanofibers are provided. The
facemask and methods provided reduce pressure drop and enhance
filtration of airborne particles. In one embodiment there is a
facemask, comprising: an inner layer comprising non-woven fiber
material configured to contact a wearer's nose and mouth; a middle
layer disposed on the inner layer and comprising a nanofiber
material; an outer layer disposed on the middle layer and
comprising nonwoven fiber material, the facemask having upper and
lower edges and at least one pleat configured to fit over a chin of
the wearer when unfolded, the at least one pleat configured for
folding and unfolding the facemask such that when folded the
facemask is configured to assume a generally flat storage
configuration and when unfolded the facemask is configured to cover
at least the nose and mouth of the wearer.
Inventors: |
CONLON; Matthew; (Caldwell,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CONLON; Matthew
CROSSTEX INTERNATIONAL, INC. |
Hauppauge |
NY |
US
US |
|
|
Family ID: |
51537383 |
Appl. No.: |
14/775420 |
Filed: |
March 15, 2013 |
PCT Filed: |
March 15, 2013 |
PCT NO: |
PCT/US13/32518 |
371 Date: |
September 11, 2015 |
Current U.S.
Class: |
128/863 ;
29/428 |
Current CPC
Class: |
A41D 13/1192 20130101;
A41D 13/1115 20130101; A62B 23/025 20130101 |
International
Class: |
A41D 13/11 20060101
A41D013/11 |
Claims
1. A facemask, comprising: an inner layer comprising nonwoven fiber
material configured to contact a wearer's nose and mouth; a middle
layer disposed on the inner side of the outer layer and comprising
a nanofiber material; an outer layer disposed on the middle layer
and comprising nonwoven fiber material, the outer layer configured
to contact an external environment, the facemask having upper and
lower edges and at least one pleat disposed between at least the
upper and lower edges and configured to fit over a chin of the
wearer when unfolded, the at least one pleat configured for folding
and unfolding the facemask such that when folded the facemask is
configured to assume a generally flat storage configuration and
when unfolded the facemask is configured to cover at least the nose
and mouth of the wearer.
2. A facemask according to claim 1, wherein the nanofiber material
of the middle layer is coated on the inner layer and/or outer layer
in one or more discrete coatings.
3. A facemask according to claim 1, wherein the nanofiber material
is disposed on a nonwoven, spunbond fiber layer of the middle
layer.
4. A facemask according to claim 1, wherein each nanofiber of the
nanofiber material has a diameter comprising at least about 150
times smaller than the diameter of each fiber of nonwoven fiber
material.
5. A facemask according to claim 1, wherein the nanofibers layer
comprises a metal organic framework disposed on the nanofiber
layer.
6. A facemask according to claim 1, wherein the nanofiber material
is hydrophilic or hydrophobic and draws moisture away from the
inner and/or outer layer.
7. A facemask according to claim 1, wherein the outer, middle,
and/or inner layer comprises an antimicrobial agent.
8. A facemask according to claim 1, wherein the nanofiber material
increases in hydrophilicity or hydrophobicity in a direction from
the inner layer to the middle layer such that a moisture
concentration gradient is formed between the inner layer and middle
layer with the inner layer having the least moisture and the middle
layer having the most moisture when the mask is worn.
9. A facemask according to claim 1, further comprising a malleable
stiffening member attached to or within the facemask proximate to
the upper edge, the malleable stiffening member configured to
conform the inner layer to at least a nose portion and a cheek
portion of the face of the wearer.
10. A facemask according to claim 9, wherein the malleable
stiffening member comprises a bend portion indicating at least the
inner layer and the nose portion of the facemask by having a
portion of the facemask elevated when the facemask is in the folded
storage configuration and the facemask comprises a means for
securing the facemask to the wearer's face.
11. A facemask according to claim 9, further comprising a second
malleable stiffening member attached to or within a lower edge of
the facemask, the second malleable stiffening member configured to
conform the facemask to at least a chin portion and a jaw portion
of the face of the wearer, the second malleable stiffening member
being smaller in length than the malleable stiffening member.
12. A facemask according to claim 11, wherein the second malleable
member comprises a bend portion indicating at least the inner layer
and the chin and/or jaw portion of the facemask by having a portion
of the facemask elevated when the facemask is in the folded storage
configuration.
13. A facemask according to claim 12, wherein the malleable
stiffening member is pre-crimped to conform to the nose and cheek
portion of the wearer, and the second malleable stiffening member
is pre-crimped to conform to the chin and jaw portion of the face
of the wearer.
14. A facemask according to claim 1, wherein the facemask comprises
a temperature, moisture, and/or pathogen collector disposed on the
outer, inner, or middle layer.
15. A facemask according to claim 5, wherein the facemask comprises
an antimicrobial disposed in or on one or more layers.
16. A facemask according to claim 14, wherein the collector
comprises a removable nanofiber strip.
17. A method of reducing pressure differential in a facemask, the
method comprising: providing an inner layer comprising nonwoven
fiber material configured to contact a wearer's nose and mouth; a
middle layer disposed on the inner layer or inner side of outer
layer and comprising a nanofiber material; an outer layer disposed
on the middle layer and comprising nonwoven fiber material, the
outer layer configured to contact an external environment, the
facemask having upper and lower edges and at least one pleat
disposed between at least the upper and lower edges and configured
to fit over a chin of the wearer when unfolded, the at least one
pleat configured for folding and unfolding the facemask such that
when folded the facemask is configured to assume a generally flat
storage configuration and when unfolded the facemask is configured
to cover at least the nose and mouth of the wearer.
18. A method according to claim 17, wherein each nanofiber of the
nanofiber material has a diameter comprising at least about 150
times smaller than the diameter of each fiber of nonwoven fiber
material.
19. A method according to claim 17, further comprising a malleable
stiffening member attached to or within the facemask proximate to
the upper edge, the malleable stiffening member configured to
conform the inner layer to at least a nose portion and a cheek
portion of the face of the wearer.
20. A method according to claim 19, further comprising a second
malleable stiffening member attached to or within a lower edge of
the facemask, the second malleable stiffening member configured to
conform the facemask to at least a chin portion and a jaw portion
of the face of the wearer, the second malleable stiffening member
being smaller in length than the malleable stiffening member.
21. A method of enhancing filtration efficiency of airborne
particles in a facemask, the method comprising: providing an inner
layer comprising nonwoven fiber material configured to contact a
wearer's nose and mouth; a middle layer disposed on the inner layer
and comprising a nanofiber material; an outer layer disposed on the
middle layer and comprising nonwoven fiber material, the outer
layer configured to contact an external environment, the facemask
having upper and lower edges and at least one pleat disposed
between at least the upper and lower edges and configured to fit
over a chin of the wearer when unfolded, the at least one pleat
configured for folding and unfolding the facemask such that when
folded the facemask is configured to assume a generally flat
storage configuration and when unfolded the facemask is configured
to cover at least the nose and mouth of the wearer.
22. A method according to claim 21, wherein each nanofiber of the
nanofiber material has a diameter comprising at least about 150
times smaller than the diameter of each fiber of nonwoven fiber
material.
23. A method according to claim 21, further comprising a malleable
stiffening member attached to or within the facemask proximate to
the upper edge, the malleable stiffening member configured to
conform the inner layer to at least a nose portion and a cheek
portion of the face of the wearer.
24. A method according to claim 23, further comprising a second
malleable stiffening member attached to or within a lower edge of
the facemask, the second malleable stiffening member configured to
conform the facemask to at least a chin portion and a jaw portion
of the face of the wearer, the second malleable stiffening member
being smaller in length than the malleable stiffening member.
25. A method of making a facemask, the method comprising providing
an inner layer comprising nonwoven fiber material configured to
contact a wearer's nose and mouth; disposing a middle layer on the
inner layer, the middle layer comprising a nanofiber material;
disposing an outer layer on the middle layer, the outer layer
comprising nonwoven fiber material, the outer layer configured to
contact an external environment; and forming at least one pleat
disposed between upper and lower edges of the facemask, the at
least one pleat configured to fit over a chin of the wearer when
unfolded, the at least one pleat configured for folding and
unfolding the facemask such that when folded the facemask is
configured to assume a generally flat storage configuration and
when unfolded the facemask is configured to cover at least the nose
and mouth of the wearer.
26. A method according to claim 25, further comprising attaching a
malleable stiffening member to or within the facemask proximate to
the upper edge, and conforming the malleable stiffening member to
at least a nose portion and a cheek portion of the face of the
wearer.
27. A method according to claim 26, further comprising attaching a
second malleable stiffening member to or within the lower edge of
the facemask; conforming the second malleable stiffening member to
at least a chin portion and a jaw portion of the face of the
wearer, the second malleable stiffening member being smaller in
length than the malleable stiffening member; and packing the
facemask.
28. A stack of facemasks, each face mask comprising: an inner layer
comprising nonwoven fiber material configured to contact a wearer's
nose and mouth; a middle layer disposed on the inner layer and
comprising a nanofiber material; an outer layer disposed on the
middle layer and comprising nonwoven fiber material, the outer
layer configured to contact an external environment, the facemask
having upper and lower edges and at least one pleat disposed
between at least the upper and lower edges and configured to fit
over a chin of the wearer when unfolded, the at least one pleat
configured for folding and unfolding the facemask such that when
folded the facemask is configured to assume a generally flat
storage configuration and when unfolded the facemask is configured
to cover at least the nose and mouth of the wearer.
29. A stack of facemasks according to claim 28, wherein each face
mask further comprises a malleable stiffening member attached to or
within the facemask proximate to the upper edge, the malleable
stiffening member configured to conform the inner layer to at least
a nose portion and a cheek portion of the face of the wearer and
each facemask is stacked so that each malleable stiffening member
is stacked substantially parallel to each other so that the inner
layer of the facemasks all face in the same direction.
30. A stack of facemasks according to claim 29, wherein each face
mask further comprises a second malleable stiffening member
attached to or within the facemask proximate to the lower edge, the
second malleable stiffening member configured to conform the inner
layer to at least a chin portion and a jaw portion of the face of
the wearer; and each facemask is stacked so that each second
malleable stiffening member is stacked substantially parallel to
each other so that the inner layer of the facemasks all face in the
same direction.
31. A stack of facemasks according to claim 29, wherein each
malleable stiffening member comprises a concave portion that is
stacked on top of one another so that the inner layer of the
facemasks all face in the same direction.
32. A stack of facemasks according to claim 30, wherein each second
malleable stiffening member comprises a concave portion that is
stacked on top of one another so that the inner layer of the
facemasks all face in the same direction.
Description
BACKGROUND
[0001] Recently, there has been great interest in different ways to
reduce the risk of infection not only in nursing homes, hospitals
and hospices throughout the nation, but also in the doctor's and
dentist's office, as well as in non-healthcare settings such as
businesses, offices, schools and other places where people
congregate. The healthcare and non-healthcare environments contain
a diverse population of microorganisms, which can cause infection.
Microorganisms (e.g., bacteria, fungi, yeast, molds and viruses) in
air and water, on surfaces, on skin, in bodily fluid (e.g., blood,
saliva, secretions, wound exudate, etc.), and other sources tend to
be the biggest players in the spread of infection. Not only are
patients at risk of developing infection, but also are the
visitors, nurses, doctors, or other healthcare and non-healthcare
workers that come into contact with these infectious sources.
[0002] Medical knowledge and public awareness of ways in which
infections are transmitted is helping to reduce spread of
infections. Infection prevention and control procedures involving
universal precautions such as hand washing, wearing gloves, gowns,
facemasks and other protective equipment and covering open wounds
has also helped reduce the spread of infections.
[0003] Unfortunately, when it comes to medical facemasks,
healthcare and non-healthcare workers often do not wear the mask
properly on the nose, cheek, lower jaw and chin areas. Sometimes
the healthcare and non-healthcare workers will even wear the mask
inside out or upside down, which results in a poor fit and gaps in
the facemask leading to potential risk of exposure for themselves
and others to microorganisms that cause infections.
[0004] Many healthcare and non-health care workers alike at times
complain that conventional facemasks are uncomfortable and often do
not remain in position during use. This may lead to a poor fit and
further discomfort to the wearer.
[0005] Further, present medical facemasks have a high pressure drop
between the interior and exterior of the mask because the filter
material prohibits the passage of air. This high pressure drop is
uncomfortable for the wearer because the interior of the mask
increases in temperature. Also, a large portion of the exhaled air
of the wearer is forced to deflect above and below the wearers face
without passing through the facemask. The more exhaled air that
deflects out of the facemask instead of passing through the
facemask results in a surrounding environment having more
pathogens, which originate from the wearer's exhaled breath.
[0006] Formal government guidelines encourage the use of face masks
on sick patients, when/if tolerated, as a means to decrease spread
of respiratory-generated infection. Evidence shows intolerance of
sick patients to wear standard surgical masks in order to limit,
through filtration, the potential spread of their illness to the
environment and others. Intolerance is related to discomfort and
perception of limited breathing ability.
[0007] Therefore, there is a need for a medical face mask which
overcomes the problems of conventional medical face mask and
provides for a comfortable and better fit over a wider range of
facial sizes and shapes. Medical face masks that help the user
properly wear the mask and to reduce potential risk of
contamination to the wearer and others are still needed.
SUMMARY
[0008] By including one or more discrete nanofiber layers on or in
place of the middle layer, the facemask provided allows for reduced
deflection of inhaled or exhaled air, which enhances filtration
efficiency for air that passes through the mask. In some
embodiments, the facemask provided allows consistent pressure and
comfortable and consistent temperatures within the mask for the
user when the mask is worn.
[0009] In some embodiments, the facemask comprises a bend portion
(e.g., crimp, concave portion, etc.) in a malleable stiffening
member (e.g., metal strip) of the facemasks, so that the user can
properly identify the front, back, nose and cheek area of the mask,
and properly wear the mask to reduce potential risk of
contamination and effectively filter either inhaled or exhaled air
from the nostrils or the mouth of the wearer.
[0010] In some embodiments, by including a malleable stiffening
member (e.g., metal strip) in the nose portion and the chin portion
of the facemask, the user can pinch the malleable stiffening
members to obtain a secure and comfortable fit to the mask and,
therefore, have the mask custom fit to his/her face.
[0011] In some embodiments, there is a facemask, comprising: an
inner layer comprising nonwoven fiber material configured to
contact a wearer's nose and mouth; a middle layer disposed on or
attached to the inside of the outer layer or on the inner layer and
comprising a nanofiber material; an outer layer disposed on the
middle layer and comprising nonwoven fiber material, the outer
layer configured to contact an external environment, the facemask
having upper and lower edges and at least one pleat disposed
between at least the upper and lower edges and configured to fit
over a chin of the wearer when unfolded, the at least one pleat
configured for folding and unfolding the facemask such that when
folded the facemask is configured to assume a generally flat
storage configuration and when unfolded the facemask is configured
to cover at least the nose and mouth of the wearer.
[0012] In some embodiments, there is a method of reducing pressure
differential between inside and outside (ambient) spaces in a
facemask, the method comprising: providing an inner layer
comprising nonwoven fiber material configured to contact a wearer's
nose and mouth; a middle layer disposed on the inner layer and
comprising a nanofiber material; an outer layer disposed on the
middle layer and comprising nonwoven fiber material, the outer
layer configured to contact an external environment, the facemask
having upper and lower edges and at least one pleat disposed
between at least the upper and lower edges and configured to fit
over a chin of the wearer when unfolded, the at least one pleat
configured for folding and unfolding the facemask such that when
folded the facemask is configured to assume a generally flat
storage configuration and when unfolded the facemask is configured
to cover at least the nose and mouth of the wearer. In some
embodiments, the nanofibers are integrally adhered to or applied to
the inside of the outer layer.
[0013] In some embodiments, there is a method of enhancing
filtration of airborne particles in a facemask by reducing
deflection and differential pressure gradients within and external
to the face mask, the method comprising: providing an inner layer
comprising nonwoven fiber material configured to contact a wearer's
nose and mouth; a middle layer disposed on the inner side of the
outer layer and comprising a nanofiber material; an outer layer
disposed on the middle layer and comprising nonwoven fiber
material, the outer layer configured to contact an external
environment, the facemask having upper and lower edges and at least
one pleat disposed between at least the upper and lower edges and
configured to fit over a chin of the wearer when unfolded, the at
least one pleat configured for folding and unfolding the facemask
such that when folded the facemask is configured to assume a
generally flat storage configuration and when unfolded the facemask
is configured to cover at least the nose and mouth of the
wearer.
[0014] In some embodiments, there is a method of making a facemask,
the method comprising providing an inner layer comprising nonwoven
fiber material configured to contact a wearer's nose and mouth;
disposing a middle layer on the inner side of an outer layer, the
middle layer comprising a nanofiber material; disposing an outer
layer on the middle layer, the outer layer comprising nonwoven
fiber material, the outer layer configured to contact an external
environment; and forming at least one pleat disposed between upper
and lower edges of the facemask, the at least one pleat configured
to fit over a chin of the wearer when unfolded, the at least one
pleat configured for folding and unfolding the facemask such that
when folded the facemask is configured to assume a generally flat
storage configuration and when unfolded the facemask is configured
to cover at least the nose and mouth of the wearer.
[0015] In some embodiments, there is a stack of facemasks, each
face mask comprising: an inner layer comprising nonwoven fiber
material configured to contact a wearer's nose and mouth; a middle
layer disposed on the inner side of an outer layer and comprising a
nanofiber material; an outer layer disposed on the middle layer and
comprising nonwoven fiber material, the outer layer configured to
contact an external environment, the facemask having upper and
lower edges and at least one pleat disposed between at least the
upper and lower edges and configured to fit over a chin of the
wearer when unfolded, the at least one pleat configured for folding
and unfolding the facemask such that when folded the facemask is
configured to assume a generally flat storage configuration and
when unfolded the facemask is configured to cover at least the nose
and mouth of the wearer. The mask allows bidirectional air
flow.
[0016] In some embodiments, there is a facemask, comprising: an
inner layer comprising nonwoven fiber material configured to
contact a wearer's nose and mouth; a middle layer disposed on the
inner layer and comprising a nanofiber material; an outer layer
disposed on the middle layer and comprising nonwoven fiber
material, the outer layer configured to contact an external
environment, the facemask having upper and lower edges and at least
one pleat disposed between at least the upper and lower edges and
configured to fit over a chin of the wearer when unfolded, the at
least one pleat configured for folding and unfolding the facemask
such that when folded the facemask is configured to assume a
generally flat storage configuration and when unfolded the facemask
is configured to cover at least the nose and mouth of the
wearer.
[0017] Additional features and advantages of various embodiments
will be set forth in part in the description that follows, and in
part will be apparent from the description, or may be learned by
practice of various embodiments. The objectives and other
advantages of various embodiments will be realized and attained by
means of the elements and combinations particularly pointed out in
the description and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 illustrates an embodiment of an outside sectional
view of the facemask in a folded configuration prior to the
facemask being installed upon a wearer's face. The bend portion or
crimp causes a projection, convex projection, or peak visible from
the outside of the mask and a recesses or trough visible from the
inside of the mask that the wearer places against the face. In this
embodiment, the rest of the facemask is flat.
[0019] FIG. 2A illustrates an embodiment of a top view of the
malleable stiffening member (e.g., metal strip) having a bend
portion shown as a crimp, concave recess, or crease that causes a
recess or trough or cavity visible from the inside of the mask in
the nose section.
[0020] FIG. 2B illustrates an embodiment of a top view of the
malleable stiffening member (e.g., metal strip) having a bend
portion shown as it would bend further around the nose if the
facemask was unfolded and the user pinched the malleable stiffening
member.
[0021] FIG. 3 illustrates a cross-sectional exploded view of an
embodiment of a facemask installed upon a wearer's face.
[0022] FIG. 4 illustrates a perspective view of an embodiment of a
facemask installed upon a wearer's face.
[0023] FIG. 5 illustrates an embodiment of the inner surface of a
facemask.
[0024] FIG. 6 illustrates an embodiment of the outer surface of the
facemask as the mask is installed upon a wearer's face and having a
visual indicator of temperature, moisture, and/or if a pathogen
contacts the mask.
[0025] FIG. 7 illustrates an embodiment of the indicator as a
strip.
[0026] FIG. 8 is a graphic illustration showing different mask
filtration. The nanofiber masks had greater filtration than other
masks.
[0027] FIG. 9 is a graphic illustration showing different pressure
differentials with various masks. The pressure differentials were
lower with the nanofiber masks indicating reduced deflection and
better filtration.
[0028] It is to be understood that the figures are not drawn to
scale. Further, the relation between objects in a figure may not be
to scale, and may in fact have a reverse relationship as to size.
The figures are intended to bring understanding and clarity to the
structure of each object shown, and thus, some features may be
exaggerated in order to illustrate a specific feature of a
structure.
DETAILED DESCRIPTION
[0029] For the purposes of this specification and appended claims,
unless otherwise indicated, all numbers expressing quantities of
ingredients, percentages or proportions of materials, reaction
conditions, and other numerical values used in the specification
and claims, are to be understood as being modified in all instances
by the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques.
[0030] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard deviation found in their respective testing measurements.
Moreover, all ranges disclosed herein are to be understood to
encompass any and all subranges subsumed therein. For example, a
range of "1 to 10" includes any and all subranges between (and
including) the minimum value of 1 and the maximum value of 10, that
is, any and all subranges having a minimum value of equal to or
greater than 1 and a maximum value of equal to or less than 10,
e.g., 5.5 to 10.
[0031] It is noted that, as used in this specification and the
appended claims, the singular forms "a," "an," and "the," include
plural referents unless expressly and unequivocally limited to one
referent. Thus, for example, reference to "a layer" includes one,
two or more layer(s).
[0032] Reference will now be made in detail to certain embodiments
of the invention, examples of which are illustrated in the
accompanying drawings. While the invention will be described in
conjunction with the illustrated embodiments, it will be understood
that they are not intended to limit the invention to those
embodiments. On the contrary, the invention is intended to cover
all alternatives, modifications, and equivalents, which may be
included within the invention as defined by the appended
claims.
[0033] The headings below are not meant to limit the disclosure in
any way; embodiments under any one heading may be used in
conjunction with embodiments under any other heading.
Face Mask
[0034] The present disclosure includes a face mask containing
nanofiber material. By including one or more discrete nanofiber
layers on or in place of the standard polypropylene filtration
layer, the facemask provided allows for reduced airflow resistance
and thereby reduced deflection of inhaled or exhaled air and
associated particles, which enhances filtration efficiency for
airborne particles that pass through the mask. In some embodiments,
the face mask provided allows consistent pressure and comfortable
and consistent temperatures within the mask for the user when the
mask is worn. In some embodiments, the materials to make the mask
comprise hydrophobic materials, e.g., hydrophobic polymers,
hydrophobic fluoropolymers, or polymers having a hydrophobic
surfactants, or the like. Suitable hydrophobic materials include
polyolefins (polyethylene, polypropylene and combinations thereof)
or polyesters that are free of hydrophilic materials. In some
embodiments, the hydrophobic polymer can comprise fluoro
surfactants. Examples of fluoro surfactants are the perfluoroalkyl
acrylic copolymers sold under the tradename Zonyl 8300 or Zonyl
7040, supplied by Ciba Geigy.
[0035] In some embodiments, the face mask provided allows for
reduced pressure differential (internal to ambient air) and
enhanced filtration of airborne particles. The face mask provided
improves filtration and/or reduces breathing resistance (e.g.,
provides wearer comfort) while protecting the wearer from airborne
particles as small as 0.05 microns (e.g., including viruses,
bacteria, spores, mold, dust and diffuse airborne chemical
pollutants, etc.). In some embodiments, the face mask can be
comfortably worn by the source of the airborne contaminants (e.g.,
patient).
[0036] Nanofiber filtration media will enable high filtration and
limit differential pressure within the mask allowing for greater
comfort and perceived breathability. This discomfort level may also
be measured by temperature readings within the worn mask. Nanofiber
masks show low temperature reading within the space between the
mask and the wearer; an indication of greater comfort. Likewise,
healthcare personnel are required to wear masks in clinical
settings to either protect themselves from large airborne droplets
or to protect other patients from their potentially infectious
respiratory emissions. Nanofiber masks will contribute to higher
mask-wearing compliance as well as the wearing of masks with more
proper fit. In association with MOF (Metal Organic Frameworks)
chemistries, nanofiber masks may also serve to protect the wearer
from specific airborne gaseous chemical threats.
[0037] Discrete integrated or detachable nanofiber strips placed
within the nanofiber masks may enable the capture of exhaled
particles for subsequent analysis and detection of wearer
illness/infection. Including a discrete nanofiber layer between two
discrete nonwoven fiber layers provides for enhanced filtration of
airborne particles, such as, for example, pathogens, and reduced
pressure drop.
[0038] FIG. 1 illustrates an embodiment of an outside sectional
view of the face mask 10 in a folded configuration 11 prior to the
facemask being installed upon a wearer's face. In the view shown,
this side of the facemask 10 would face the outside environment and
not touch the wearer's nose, cheeks, jaw and/or chin. The facemask
10 may have application in healthcare, industrial, domestic,
public, or other settings. The embodiment shown is an N95
respirator, which is a lightweight, nose-and-mouth respirator that
provides protection for the wearer from microorganisms (e.g.,
bacteria, fungi, yeast, molds and viruses).
[0039] The facemask 10 is generally configured so as to provide a
secure fit which reduces or prevents gaps and passage of material
between the nostrils and mouth and the surrounding environment
except through the filter material 13. The makeup of the filter
material 13, and the pleating 20 used in connection with the
facemask 10 will be explained in detail shortly. The facemask 10
has the particular advantage of allowing a secure fit to be created
and to be maintained upon installation of the facemask 10 on the
face with the use of two ear loops 28 and 30.
[0040] The facemask 10 may be constructed of a wide variety of
materials and is preferably disposable. The inner, outer, and
filtration materials 13 used to fabricate the facemask 10 may vary
according to the particular application of the facemask 10. For
example, when the facemask 10 is to be used in a medical
application, such as on members of a surgical team, it is common to
use a three layer filter material that will provide blood (or
other) fluid resistance to prevent penetration of fluids to the
inner lining of the mask. However, appropriate inner, outer, and
filtration materials may be of a single or multiple layer design.
Multi-layer material may be readily purchased in a precollated
form, that is with the three layers already arranged, or the
materials may be obtained separately and the filter material 13
formed in part of the process for forming the facemask 10.
[0041] Generally, a three or four layer filter medium might include
an outer layer of a relatively porous paper-like or spunbond
polypropylene material which provides durability and resistance
against abrasion and/or fluid penetration. The outer layer may also
be generally stiffer than the other layers. By using a stiffer
outer layer, the effectiveness of the various pleating arrangements
is increased. The pleats 20 are disposed between the upper edge 12
and lower edge 25 and side edges 21 and 29 and may be incorporated
in the body of the filter material 13 to hold the facemask 10 in a
cup-like shape when installed. The inner layer or layers of the
filter material generally contain polyethylene or polypropylene, or
other material, which exhibits the proper filtration
characteristics. In the embodiment shown, the middle layer
comprises nanofiber material that is coated onto either the outer
side of the inner layer or the inner side of the outer layer. Glass
fiber based materials may also have applications as the middle
filtration layer. The innermost layer of the filter material is to
be worn next to or against the face and generally comprises a soft
material for providing a soft, non-irritating surface against which
the facial skin will make contact.
[0042] In medical, dental and/or surgical applications, it is
generally important that the combined mask materials 13 also
provide bacterial filtration efficiency (BFE) in accord. The BFE of
a filter material is generally determined by the percentage of
bacteria, such as Staphylococcus aureus or Bacillus
stearothermophilus, that is able to migrate through the filter
material under normal conditions. The fewer bacteria which are able
to pass through the filter material 13, the higher the BFE. Of
course, a BFE of 100% is desirable; however, efficiencies of as low
as 25% are not uncommon among some types of prior art disposable
facemasks. However, materials are available which provide BFE's of
between 90 and 99%. Thus, in a medical, dental and/or surgical
environment it is generally desirable to utilize a filter material
having as high a BFE as possible so as to prevent release of
nasopharyngeal organisms into the environment. In general, the
considerations that provide for a high BFE are the same
considerations which provide that a filter material would be
desirable in applications in industry and domestic use. For
example, a filter material which inhibits the migration of nearly
all bacteria would generally also prevent inhalation of dust and
dirt particles in industrial applications. Furthermore, it has
generally been found that those materials providing a high BFE are
often also those materials which provide the least resistance to
passage of gases through the filter material.
[0043] The easy passage of gases through the filter material is
important in maintaining the comfort of the wearer and reduce or
inhibit deflection of air and the particles it carries out of any
openings created by imperfect sealing of the face mask to the face,
thereby by-passing the particle filtration process intended. It
should be realized by one of ordinary skill in the art, however,
that many applications might require greater or lesser standards of
filtration than is commonly required in the medical environment.
Therefore, while filter materials having an efficiency suitable for
use with the present application available in the art, the best
filter material is of little use if the air inhaled and exhaled by
the wearer is allowed or facilitated to escape the face mask 10
without passing through the filter material 13. Indeed, the lack of
a secure fit across a wide variety of facial sizes and shapes in
the face masks available in the prior art is important to the
design and fabrication of face masks. Therefore, the present
application provides a unique secure fit which reduces or prevents
inhaled and exhaled air from leaking around the edges 12, 25, 21,
and 29 of the facemask 10 by finding the combination of air flow
patterns caused by pressure differentials, and an route of escape,
all while providing a superior fit on a wider range of facial sizes
and shapes. The maintenance of such a secure fit greatly improves
the overall efficiency of the face mask 10.
[0044] The structure of the face mask 10 is generally prepared as a
rectangular piece of flat filter material 13. However, it will be
understood by those of ordinary skill in the art that other shapes
of the face mask can be made in order to cover additionally both
the eyes, hair, and throat of the user. As such, the present
application includes face masks 10 that cover areas above and
beyond simply the nose and mouth of the user. The facemask may also
incorporate any combination of known face mask 10 features, such as
visors or shields, sealing films, beard covers, etc. In some
embodiments, the face mask 10 may be from about 5.5 inches to 7
inches across in length to cover the user's nose and mouth. In FIG.
1, the mask is shown as it would be packaged in its folded and flat
configuration, except for the convex outside by the malleable
stiffening member 14, where the outside surface is viewed.
[0045] The facemask 10 comprises a malleable stiffening member 14
attached to or imbedded in the mask material 13 at the masks upper
edge 12. The malleable stiffening member 14 is configured to
conform the filter material 13 to at least a nose portion and a
cheek portion of the face of the wearer. It will cause a portion of
the mask to be convex and have, in some embodiments a curved
projection on the outer layer to indicate the nose and cheek
area.
[0046] A second malleable stiffening member 24 is attached to or
within lower edge 25 of the filter material 13, as illustrated in
FIG. 1. The second malleable stiffening member is configured to
conform the mask material to at least a chin portion and a jaw
portion of the face of the wearer. In some embodiments, the second
malleable member does not include a bend portion. In other
embodiments, it can include a bend portion that is different from
the bend portion 15 in the nose and cheek portion of the mask
provided that they can be distinguished (e.g., the bend portion 15
at the nose section can be creased at a larger angle than the
optional bend portion in the chin piece). The portion of the mask
that has the second malleable stiffening member will also have, in
some embodiments, a convex projection on the outer layer.
[0047] It should be understood that the use of the term "malleable
stiffener" or "malleable stiffening member" herein is meant to
include the use of both malleable and flexible stiffeners. It is
preferred that the malleable stiffeners 14 and 24 be placed
adjacent to the upper 12 and lower edges 25 of the mask material
13, respectively. Alternatively, the malleable stiffeners 14, and
24 may be placed somewhere along the upper 12 and lower edges 25 of
the mask material 13. The important property of the malleable
stiffeners 14 and 24 is that the material be pliant enough to be
bent to a shape that conforms to the face of the wearer, and then
retain that shape. In this regard, it is important that the
malleable stiffeners 14 and 24 not be too stiff so as to make it
difficult for the wearer to conform the face mask 10 upon
installation. The face mask 10 also has ear loop 30 attached to
edges of the mask at attachment points 16 and 22 and ear loop 28 to
edges of the mask at attachment points 18 and 26 used in donning
the mask. In the embodiment shown in FIG. 1, the ear loops are
attached to the outside surface of the mask. However, it will be
understood by those of ordinary skill in the art that the loops can
be attached to the inside surface of the mask.
[0048] In some embodiments, the mask can be a mask that is not
folded, e.g., a cone shaped mask that has the nanofiber disposed on
the inner layer or the inside of the outer layer.
[0049] In some embodiments, the mask of the current application is
not an N95 mask, but other mask type like a cone-shaped mask.
[0050] Generally, as used herein, the upper portion of the facemask
10 will refer to that portion which contacts the nose and cheek
areas of the wearer while the lower portion of the facemask 10 will
be that portion which is in proximity to the lower jaw and chin of
the wearer. The malleable stiffeners 14 and 24 can comprise any
pliant material, such as a malleable metal or alloy, plastic, or
the like. In some embodiments, the malleable stiffeners comprise
aluminum or other binding material which exhibits stiffening
characteristics.
[0051] The malleable stiffeners 14 and 24 can be attached to or
imbedded within the inside or outside surface of the filter
material. In some embodiments, the malleable stiffening members can
be attached to the facemask and then covered with the same or
different material used to make the mask. For example, the
malleable stiffening members can be attached to the mask by
covering it with spunbonded polypropylene and ultrasonically
sealing it to the outer surface of the mask. In some embodiments,
the malleable stiffening members can be attached to the mask by
adhesive or other means for holding the malleable stiffening
members to the mask.
[0052] In some embodiments, first malleable stiffener 14 used for
the nose portion of the mask may be from about 3 to 6 inches in
length and from about 0.025 or 0.125 or 0.25 or 0.5 inches in
height and from about 0.01 or 0.02 or 0.05 or 0.125 or 0.25 inches
thick.
[0053] In some embodiments, second malleable stiffener 24 used for
the chin portion of the mask may be from about 1.5 to 5 inches in
length and from about 0.025 or 0.125 or 0.25 or 0.5 inches in
height and from about 0.01 or 0.02 or 0.05 or 0.125 or 0.25 inches
thick. In some embodiments, the first malleable stiffener 14 used
in the nose portion is a length that is larger or the same size as
the length of second malleable stiffener 24 that is used in the
chin portion of the facemask. In some embodiments, the second
malleable stiffener 24 is smaller than the first malleable
stiffener 14.
Bend Portion
[0054] The malleable stiffening member 14 has a bend portion 15
indicating at least the inner surface, outer surface, center and/or
the nose portion of the facemask. The bend portion or crimp
includes an angular or rounded shape made by pinching, folding,
punching or bending the malleable stiffening member 14 to cause a
cavity, indentation, recess, crease, concave recess, or trough on
the inside surface of the mask (not shown) and a projection, convex
projection, peak, protrusion, elevation or ridge on the outside
surface of the mask (shown). At these portions of the facemask, it
will not be flat on storage. In some embodiments, the bend portion
15 includes making a ridge or fold by pinching the malleable
stiffening member 14 by hand or machine. Although the bend portion
15 is shown generally in the center of the malleable stiffening
member 14, it will be understood that the bend portion 15 can be
disposed to the left, or right of center.
[0055] The bend portion 15 or crimp may be located by the nose
portion of the mask on the outer or inner surface and be angled or
crimped in the direction away from the nose so that the user can
bend it further for a custom fit around the nose and check area. In
this way, the bend portion can be "pre-bent" or "pre-crimped" by
the manufacturer. Accordingly, the bend portion will cause the
inner surface of the mask that is to be placed against the user's
nose to have a cavity, indentation, recess, crease, or trough on
the inside surface of the mask and as the malleable stiffening
member 14 is further pinched, bent or folded (as shown by the
arrows in FIG. 2A), a cavity, indentation, recess, crease, or
trough becomes larger to accommodate the nose. In this way, the
user will have a visual indication of where the top of the mask is,
where the nose section of the mask is and/or where the center of
the mask is for those embodiments where the bend portion is
disposed within the center or generally within the center of the
malleable stiffening member 14. In some embodiments, the bend
portion 15 allows the user to identify the outside of the mask, the
inside of the mask, top of the mask, and/or center of the mask. In
some embodiments, the bend portion 15 is packaged (not shown) at
least partially bent so that the cavity, indentation, recess,
crease, or trough is visible on the interior of the mask.
[0056] The bend portion 15 or crimp is typically formed from the
same material as the malleable stiffening member. However, the same
or different material may be used as long as the bend portion will
cause a crease or fold in the filter material and allow the user to
identify the top, center, inside and/or outside of the mask. The
bend portion may be formed from any suitable material, such as an
elastic material (e.g., a polymer), inelastic material, a nonwoven,
knit, ribbon, cloth, wire, metal or the like.
[0057] In some embodiments, the bend portion may be bent before use
by the manufacturer by about 1 to about 5 degrees, by about 1 to
about 10 degrees, or by about 5 to about 20 degrees. In some
embodiments, the bend portion may be bent before use by the
manufacturer so that the bend portion projects out of the inner or
outer surface of the mask by about 0.25 mm to about 0.5 mm, or by
about 1 mm to about 5 mm or by about 1 mm to about 10 mm or by
about 5 mm to about 20 mm, or by about 10 mm to about 30 mm or by
about 35 mm to about 60 mm. Therefore, the facemask will not be
flat when stored or in the package as a stack before it is worn. In
some embodiments, the bend portion is designed for easy bending
around the ridge of the nose. In some embodiments, the bend
portion, like the malleable stiffening member, may be substantially
deformable so that a wearer is able to bend, pinch or fold the bend
portion and/or the malleable stiffening member between two or more
fingers when gripping it as it is put around the ridge of the
nose.
[0058] The bend portion 15, since it provides space between
adjacent masks, allows the facemask 10 to be stacked for easy
packaging and dispensing of a plurality of masks. In one
embodiment, there is a stack of facemasks, each face mask
comprising: an inner layer comprising nonwoven fiber material
configured to contact a wearer's nose and mouth; a middle layer
disposed on the inner layer and comprising a nanofiber material; an
outer layer disposed on the middle layer and comprising nonwoven
fiber material, the outer layer configured to contact an external
environment, the facemask having upper and lower edges and at least
one pleat disposed between at least the upper and lower edges and
configured to fit over a chin of the wearer when unfolded, the at
least one pleat configured for folding and unfolding the facemask
such that when folded the facemask is configured to assume a
generally flat storage configuration and when unfolded the facemask
is configured to cover at least the nose and mouth of the wearer.
The facemasks are positioned in a nestled relation to one another
(e.g., masks that are close or one on top of the other in the
package), the inner surface of at least one mask being apposed to
the outside surface of an adjacent mask, thereby forming a stack.
Likewise, when the facemask comprises bent malleable stiffening
members, the concave portions can be stacked one on top of the
other and parallel to each other for ease of packaging.
[0059] FIG. 2A illustrates a top side view of the malleable
stiffening member 31 (e.g., metal strip) having a bend portion
shown as a crimp or crease. The bend portion has a projection,
peak, protrusion, elevation, convex surface or ridge 32A that
extends out and is visible on the outside surface of the mask (not
shown). The bend portion has a cavity, concave surface,
indentation, recess, crease, or trough 32B on the inside of the
mask that is visible on the inside surface of the mask. The
stiffening member 31 would have this configuration when attached to
the mask. The mask would be in a flat and/or folded configuration,
except for the bend portion(s). In the embodiment shown, the bend
portion, like the malleable stiffening member 31, may be
substantially deformable so that a wearer is able to bend or fold
the bend portion and/or the malleable stiffening member in the
direction of the arrows shown using two or more fingers when
gripping it as it is put around the ridge of the nose.
[0060] By employing a bend portion in the malleable stiffening
member 31, which is placed in the center of the facemask, the
wearer will see a projection, peak, protrusion, elevation, convex
surface, or ridge or other marker visible on the outside surface of
the mask, or a cavity, concave surface, indentation, recess,
crease, or trough or other marker visible on the inside surface of
the mask and know where the top inside or outside, and/or center of
the mask is and where the nose portion of the mask is to be placed
on the face. It will be understood by those of ordinary skill in
the art that the bend portion can be any shape (e.g., circular,
square, rectangular, regular, irregular, symmetrical or
asymmetrical shape).
[0061] In some embodiments, the bend portion causes a projection,
peak, protrusion, elevation, or ridge or other marker on the top
front, outside and/or center portion of the mask so that the wearer
will know these portions of the mask and know the right side of the
mask should be facing the outside environment and not the wearer's
nose or face. In this way, the facemask of the present application
reduces the risk that the wearer will wear the mask
incorrectly.
[0062] FIG. 2B illustrates a top view of the malleable stiffening
member 31 having a bend portion shown as it would start to bend
around the nose if the facemask (not shown) was unfolded. The bend
portion has a projection, peak, protrusion, elevation or ridge 32A
that extends out and is visible on the outside surface of the mask
(not shown). The projection increases as the malleable stiffening
member 31 is further bent or pinched. The bend portion has a
cavity, indentation, recess, crease, or trough 32B on the inside of
the mask that is visible on the inside surface of the mask and gets
bigger as the malleable stiffening member is further bent, pinched
or folded. The stiffening member 31 would have this configuration
when attached to or in the unfolded mask. In the embodiment shown,
the bend portion, like the malleable stiffening member 31 may be
substantially deformable so that a wearer is able to bend or fold
the bend portion and/or the malleable stiffening member using two
or more fingers when gripping it as it is put around the ridge of
the nose. It will be understood that the one or more malleable
members once bent will cause the mask to be elevated where the bend
is, while the other portions of the mask that do not have a bend
portion will remain flat.
[0063] In some embodiments, the bend is in a vertical direction
relative to the one or more pleats. In some embodiments, the bend
portion 32 is crimped, bent, creased, folded, or angled toward the
inner surface or outer surface of the facemask by about 1 to 10
degrees or by 0.5 mm to about 50 mm. For example, the crimp can be
from 1 mm, 10 mm, 15 mm, 20 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm,
55 mm, 60 mm, or 65 mm.
Securing Means
[0064] The facemask may be attached to the user by a securing means
that can attach the mask to the user. For example, the securing
means may be a pair of manual tie straps that are wrapped around
the head of the user and are connected to one another, or the
securing means may be ear loops (28 and 30 in FIG. 1), elastic
bands wrapped around the head of the user, a hook and loop type
fastener arrangement (e.g. VELCRO.RTM. fasteners), or a connection
directly attaching the face mask to a hair cap.
[0065] In some embodiments, the ear loops (28 and 30 in FIG. 1) can
be attached to the inner or outer surface of the mask at upper
edges 16 and 18 and lower edges 22 and 26. The attachment points
may be in from the edge by, for example, from about 1/8.sup.th of
an inch to 1 inch. The closer together the ear loops are, the
tighter the fit and the mask will reduce gaps and leakage of
inhaled and exhaled air. In some embodiments, the loop is
positioned so as to be balanced in the wearer's hand, thereby
stabilizing the mask for donning.
[0066] The loop may be formed from any suitable material, such as
an elastic material (e.g. a polymer), inelastic material, a
nonwoven, knit, ribbon, cloth, wire, and so forth. As used herein,
the term "elastic" refers to the ability of a material to recover
its size and shape after deformation. As used herein, the term
"inelastic" refers to the inability of a material to recover its
size and shape after deformation. In some embodiments, the loop is
formed from the same material selected to form the outside surface
of the mask. The loop may be bonded or otherwise affixed to the
outside surface or inside surface of the mask. Examples of suitable
techniques include adhesive bonding, thermal bonding, stitching,
and so forth. As used herein, the term "adhesive" refers to the
property of any material that allows the material to bond together
substrates by surface attachment.
[0067] The loop is generally sized and positioned to facilitate
gripping by a wearer, both prior to, during, and after donning. The
loop 30 may be more or less than about 80 mm (0.08 m) in length as
measured from the first end 16 to the second end 22 along the
length of the loop. In other embodiments, the loop 30 may be less
than about 60 mm (0.06 m) in length. In yet other embodiments, the
loop 30 may be less than about 40 mm (0.04 m) in length. Where, in
some embodiments, the loop is formed from an elastic material, the
loop may have a fully extended length of 200 mm (0.200 m) or more.
In some embodiments, the loop is from about 4 to 10 inches in
length.
[0068] In some embodiments, the loop generally extends inwardly
from the outside surface or inside surface a sufficient distance so
that the wearer of the mask may grip the loop between two or more
fingers of a single hand. In some embodiments, the loop may extend
outwardly from the inside or outside surface at least 5 mm (0.005
m). In other embodiments, the loop may extend outwardly from the
outside or inside surface at least about 8 mm (0.008 m). In yet
other embodiments, the loop may extend outwardly from the outside
or inside surface at least about 10 mm (0.01 m) from the outside
surface.
Nanofibers
[0069] Current medical masks incorporate filter materials that are
made of non-woven cellulose and/or polypropylene materials. Fiber
diameter and density is the main variable responsible for
maintaining a balance between filtration efficiency and pressure
differentials (inside the mask on the face in relation to ambient
pressures outside the mask). Greater diameter and density of fibers
provide for less fiber surface area and thereby less space between
fibers through which gaseous particles may pass. When such a
dense-fiber mask is sealed to the face through a tight fit, upon
wearer exhalation pressure within the mask is elevated creating a
pressure differential between the inside of the mask and the
ambient air. The pressurized gas will seek equivalence to ambient
(lower) air pressures through the pathway of least resistance,
namely any opening or unintended leak around the mask, rather than
through the dense filtration material. This creates a condition
whereby airflows are deflected off of the mask material (inner, and
filter layers) rather than passing through it. Likewise, upon
inhalation of a mask with high(er) density filtration material and
a tight seal, inhalation will produce a negative pressure within
the mask chamber. This pressure differential will resolve itself in
the same fashion, namely, with higher ambient (external) air flows
seeking entry into the mask via the path of least resistance;
through any mask leaks, rather than through the filter material. In
both exhalation and inhalation, greater effort is required to move
air through the mask. For example, the use of N95 respirators,
which generally contain higher density filtration materials,
require medical clearance to ensure that the extra burden on the
diaphragmatic muscles used for breathing don't cause adverse health
consequences to the wearer. The lower the resistance, or pressure
differential, created by the mask filtration material, therefore,
the lower the likelihood for air escape and filter by-pass in
seeking pressure equilibrium within and external to the mask, and
the lower "work" required for the wearer to move the air, through
his/her breathing cycle, through the filter material. Mask fit,
therefore, becomes less critical in achieving optimal filtration.
Replacement of conventional filtration materials by nanofiber
material with .about.150.times. smaller diameter and far greater
surface area will result in significant improvements in filtration
efficiency, lower pressure differentials, and less mask leakage and
filter bypass. Efficiency increases are attributed to the enormous
specific surface of the nanofiber filter media. Less inward to
outward leakage, higher filtration efficiency, and lower pressure
differential will enhance the respiratory source control (inward to
outward filtration/capture of potentially infectious particles)
efficacy of the mask. Additionally, the nanofiber layer, while
chemically inert, can be modified to incorporate specific
functional characteristics. In some embodiments, the nanofiber can
be modified with silver, copper, or gold nanoparticles for
antimicrobial functionality or application of Metal Organic
Frameworks (MOFs) that can be functionalized for capture of
specific gaseous airborne threats. Additionally, these fibers can
be tailored to be hydrophobic or hydrophilic.
[0070] The nanofibers can be any suitable type of nanofiber,
including electrospun fibers, protein nanofibers, cellulose
nanofibers, hollow nanofibers, bacterial nanofibers, inorganic
nanofibers, hybrid nanofibers, splittable nanofibers or
combinations thereof. In some embodiments, the nanofibers can be
coated on or adhered to the inside of the outer layer, middle layer
inside or outside of it, or on or adhered to the inside or outside
of the inner layer of the mask.
[0071] As used herein, the term "nanofibers" refers to very small
diameter fibers having an average diameter not greater than about
1500 nanometers (nm). Nanofibers are generally understood to have a
fiber diameter range of about 10 to about 1500 nm, more
specifically from about 10 to about 1000 nm, more specifically
still from about 20 to about 500 nm, and most specifically from
about 20 to about 400 nm. Other exemplary ranges include from about
50 to about 500 nm, from about 100 to 500 nm, or about 40 to about
200 nm. In instances where particulates are present and
heterogeneously distributed on nanofibers, the average diameter of
a nanofiber can be measured using known techniques (e.g., image
analysis tools coupled with electro microscopy), but excluding the
portions of a fiber that are substantially enlarged by the presence
of added particles relative to the particle free portions of the
fiber.
[0072] Nanofibers ranging from 10 nm to 1000 nm can be used in
filtration medium to capture submicron particles below 1000 nm. The
ability of nanofibers to capture particles is believed to be due to
a combination of interception of submicron particles by the fibers
as well as the Brownian motion or "random walk" of submicron
particles, both of which facilitate the particles to be captured by
the large surface/mass ratio of the nanofibers. Further increase of
capture capability may be obtained by increasing the nanofiber
surface area such as by reducing the fiber diameter and/or by
increasing the packing density of the nanofibers, as measured in
terms of grams of nanofibers per square meter.
[0073] In some embodiments, the facemask configuration of the
present application may offer many advantages: the nanofibers may
maintain a low solid volume fraction (or equivalently a higher
porosity) in each nanofiber layer, the total thickness of the
nanofiber layers in the filter may well exceed the single nanofiber
layer having the same total polymer packing density (i.e. same
grams per square meter or "gsm"), a high particle capture
efficiency may be attained with submicron particles, a lower
pressure drop may be achieved when compared to the single layer
with the same packing density (i.e. same gsm), the substrate layer
may act as a support providing mechanical stress (tensile) for the
filtration medium, and the substrate layer may serve as a filter
medium.
[0074] In some embodiments, the nanofibers can be in a discrete
layer(s) sandwiched between the outer and inner layer. In some
embodiments, the nanofibers can make up the middle layer or can be
disposed on the middle layer of the facemask. In some embodiments,
the nanofiber can be disposed on the inner, middle and/or outer
layer by electrospinning.
[0075] As used herein, the term "electrospinning" refers to a
technology which produces nano-sized fibers referred to as
electrospun fibers from a solution using interactions between fluid
dynamics and charged surfaces. In general, formation of the
electrospun fiber involves providing a solution to an orifice in a
body in electric communication with a voltage source, wherein
electric forces assist in forming fine fibers that are deposited on
a surface that may be grounded or otherwise at a lower voltage than
the body. In electrospinning, a polymer solution or melt provided
from one or more needles, slots or other orifices is charged to a
high voltage relative to a collection grid. Electrical forces
overcome surface tension and cause a fine jet of the polymer
solution or melt to move towards the grounded or oppositely charged
collection grid. The jet can splay into even finer fiber streams
before reaching the target and is collected as an interconnected
web of small fibers. The dried or solidified fibers can have
diameters of about 40 nm, or from about 10 to about 100 nm,
although 100 to 500 nm fibers are commonly observed. Various forms
of electrospun nanofibers include branched nanofibers, tubes,
ribbons and split nanofibers, nanofiber yarns, surface-coated
nanofibers (e.g., with carbon, metals, etc.), nanofibers produced
in a vacuum, and so forth. The production of electrospun fibers is
illustrated in many publication and patents, including, for
example, P. W. Gibson et al, "Electrospun Fiber Mats: Transport
Properties," AIChE Journal, 45(1): 190-195 (January 1999), which is
hereby incorporated by reference.
[0076] The nanofibers can be in the mask to create a gradient in
the mask. The gradient can be a multi-component material in which
nano-sized fibers of at least two different "types" which have been
produced by electrospinning are present and non-uniformly
distributed to create one or more gradients or heterogeneity in one
or more directions. The gradient in a "gradient electrospun
material" provides discrete areas having measurable differences in
surface chemistry (e.g., wicking, contact angle, etc.) or other
material properties, including, but not limited to, density, pore
size, surface charge, zeta potential, and so forth, resulting from
the presence of fibers of different types, i.e., of substantially
different material composition.
[0077] In some embodiments, the nanofibers can be coated on the
mask in the inner, middle and/or outer layer. In some embodiments,
the inner layer is the most porous, the middle layer is less porous
than the middle layer and the outer layer is the least porous. In
some embodiments, the porosity of the inner and middle layer is the
same and the outer layer is the least porous.
[0078] With reference to FIG. 3, which shows an exploded
cross-sectional view of the medical facemask of the present
disclosure, the medical facemask has a first discrete nonwoven
fiber layer 33 (inner layer) disposed adjacent a wearer's face.
First layer 33 has an inner surface 34, which is at least partially
contacting the wearer's face. First layer also has an outer surface
35. A second discrete nonwoven fiber layer 36 (middle layer) is
disposed adjacent to outer surface 35 of first layer 33. Second
layer 36 can be spaced apart from first layer 33 or can be disposed
in contact with first layer 33. Second layer 36 has an inner
surface 37 facing direction A as shown in FIG. 3. Second layer 36
includes an outer surface 38 facing direction B as shown in FIG. 3
opposite inner surface 34. In one embodiment, a third discrete
nonwoven fiber layer 39 is disposed adjacent second layer 36 such
that second layer 36 is disposed between first and second layers
33, 36. Third layer 39 (outer layer) has an inner surface 40 facing
direction A as shown in FIG. 3 disposed adjacent outer surface 38
of second layer 36. Third layer 39 (outer layer) also includes an
outer surface 41 exposed to the surrounding environment opposite
inner surface 40 of third layer 39.
[0079] Nanofiber material is layered or coated onto surfaces of
first, second and/or third fiber layers 33 (inner layer), 36
(middle layer), 39 (outer layer). Alternatively, the nanofiber
layer can replace the outer, middle, or inner layer. The nanofiber
layers are discrete layers, separate from and coated on first,
second and third fiber layers 33, 36, 39. The discrete nanofiber
layers are not interwoven into the nonwoven fiber layers nor are
they composites of the nonwoven fiber layers. Discrete nanofiber
layers can be coated on one or a plurality of the surfaces of the
first, second and third fiber layers 33, 36, 39. In one embodiment,
second layer 36 is replaced with a first discrete nanofiber layer
42 coated on outer surface 35 of first layer 33 and a second
nanofiber layer 43 coated onto inner surface 40 of third layer 39.
In one embodiment, discrete nanofiber layers are coated onto outer
surface 35 of first layer 33, inner and outer surfaces 37, 38 of
second layer 36, and inner surface 40 of third layer 39 forming a
facemask having four discrete nanofiber layers for enhanced
filtration of airborne pathogens. In one embodiment, a discrete
nanofiber layer is coated on inner surface 34 of first layer 33
and/or inner surface 40 of third layer 39.
[0080] The nanofiber layer density and the combination of
non-woven/nanofiber layers will vary according to specific
performance objectives for each mask version. For example, one mask
version may incorporate a more dense nanofiber layer as a
replacement for the non-woven filtration layer in order to achieve
similar filtration efficacy while reducing pressure differentials
(increasing breathability). Another version may incorporate a less
dense nanofiber layer onto an existing layer to achieve greater
filtration efficiency. Additionally, the hydrophilic or hydrophilic
nature of the incorporated nanofibers may vary. For example, a
highly hydrophobic outer layer would be used to improve the fluid
bather properties of the mask. Conversely, a highly hydrophilic
nanofiber layer may be used to draw moisture in (wick) towards a
subsequent layer in order to draw moisture away from the wearer's
face and/or to draw potentially infectious moisture droplets toward
an anti-microbial layer where the pathogen would be neutralized. It
is envisioned that the nanofiber layers may incorporate
antimicrobial nanoparticles, metal organic frameworks, moisture
sensors and/or an integrated flu diagnostic nano-strip. In some
embodiments, the materials to make the mask comprise hydrophobic
materials, e.g., hydrophobic polymers, hydrophobic fluoropolymers,
or polymers having a hydrophobic surfactants, or the like.
[0081] It is further contemplated that the facemask is a continuous
loop of fabric that is stretched over the wearer's head covering
the neck. Approximately half of the fabric will comprise
nano-filter material and the other half will comprise fabric having
elastic properties. The front filter portion will be pulled over
the bridge of the nose. It is contemplated that the facemask has a
tear-away perforation for removal and safety purposes, and will not
require any metal pieces or ties in order to secure the facemask to
the wearer.
[0082] In one embodiment, discrete nanofiber layer 42 is
hydrophilic to draw moisture away from first layer 33. In a further
embodiment, the discrete nanofiber layers increase in
hydrophilicity from inner surface 34 of first layer 33 to inner
surface 40 of third layer 39 such that a moisture concentration
gradient is formed between first and third layers 33, 39. First
layer 33 has the lowest moisture content and third layer 39 has the
highest moisture content given that moisture will be constantly
drawn away from the wearer's face in direction B as shown in FIG.
3. Once moisture originating from the wearer's breath passes from
inner surface 34 of first layer 33 to outer surface 41 of third
layer 39, the moisture will evaporate into the surrounding
environment. The moisture concentration gradient reduces the amount
of moisture in an interior cavity 27 of facemask 10, thus enhancing
comfort for the wearer. In one embodiment, first, second and third
layers 33, 36, 39 comprise material increasing in hydrophilicity,
respectively.
[0083] FIG. 4 illustrates a perspective view of an embodiment of a
facemask 44 installed upon a wearer's face. The outer surface 58 of
the facemask 44 is shown facing the outside or external environment
that the wearer 64 is exposed to. The facemask 44 is shown in its
unfolded position and secured to the wearer's face to provide the
secure and comfortable fit by securing the ear loops (one shown as
62) around the wearer's ears. The ear loops are preferably formed
of elastic such that they will secure the facemask 44 in the proper
position on the wearer's face. Use of elastic ear loops allows the
facemask 44 to be easily installed by the wearer and avoids the
difficulty of tying a string tie behind the head. Furthermore,
since the ear loops are elastic, there is not the risk of the ear
loops becoming untied at an inopportune moment which accompanies
the use of ordinary tie strings. Furthermore, the elasticity of the
ear loops may be chosen so as to allow the facemask 44 to be easily
repositioned on the face while only using one hand.
[0084] The facemask 44 comprises one or more pleats (shown in the
unfolded position are three pleats that have been unfolded 48, 50
and 52). The one or more pleats are disposed between at least the
upper, lower, and/or side edges of the mask. As used herein, the
term "pleat" refers to a relatively flat double-fold formed in the
facemask 44 when the facemask 20 is in the flat storage
configuration (as illustrated in FIG. 1). The pleats in the filter
material can be any known in the art and include, for example, Z
shaped pleats, standard pleats, omega pleats, secondary pleats,
reverse pleats or the like.
[0085] The one or more pleats are disposed between the upper, lower
and side edges (60) of the mask. It will be understood by those of
ordinary skill in the art that the mask may have one, two, three,
four, five, six, seven, eight or more pleats, each of which can be
the same or different sizes and/or shapes.
[0086] The facemask 44 comprises in its upper section, an upper
malleable stiffener 46, which when pinched, folded or twisted pulls
the filter material including its top and side edges against the
nose and cheeks. The facemask also comprises lower malleable
stiffener 54 in the lower section of the facemask, which when
pinched, folded or twisted pulls the side and lower edges into the
side of the face and lower jaw area to provide a secure facial fit.
Furthermore, it can also be seen that the pleats 48, 50, and 52
allow the creation of a pocket-like shape by which the inner
surface of the filter material is held tightly against the lower
jaw area of the wearer. The upper and lower malleable stiffeners
(46 and 54) are attached to or imbedded in the mask material,
typically on or in the inside or outside of the mask. These
malleable stiffeners increase the secure fit formed around the nose
and cheek area and the chin and jaw portion of the face of the
wearer.
[0087] By properly positioning the ear loops, the one or more
pleats, and pinching, bending, folding or twisting the malleable
stiffeners against the nose, cheek, chin and/or jaw areas upon
installation of the facemask, a secure fit is provided not only
along the upper and lower malleable stiffeners 46 and 54, but also
along the side edges of the facemask 44 which contact the cheeks.
This is due to the effect of the tension exerted because of the
cooperation of the pleats, malleable stiffener(s) and the ear
loops. Furthermore, the facemask 44 still allows for normal speech
without significant difficulty while maintaining a secure fit.
[0088] FIG. 5 illustrates an embodiment of the inner surface 68 of
a facemask that the wearer would place against his/her face. The
mask is shown in the unfolded or partially unfolded position. The
upper malleable stiffener 67 imbedded or attached to the mask has
been folded, crimped, pinched, bent, creased, and/or angled around
the wearer's nose and/or cheek area and causes a cavity 66 in the
filter material that conforms and pulls it closer to a portion of
the nose and/or cheek. The lower malleable stiffener 70 imbedded or
attached to the mask has been crimped, bent, creased, folded,
pinched, and/or angled around or under the wearer's chin and/or jaw
area and causes a cavity 69 in the filter material that conforms
and pulls it closer to a portion of the wearer's chin and/or jaw
area. In some embodiments, the cavity 69 will be located under the
chin so that the user can rest it on it. The mask provides a secure
and comfortable fit for the user by simply pinching the malleable
stiffeners. It will be understood by those of ordinary skill in the
art that the cavities in the inside of the mask 66 and 69 can be
aligned vertically with each other or be substantially parallel to
each other so that projection 66 and 69 line up.
[0089] FIG. 6 illustrates an embodiment of the outer surface 73 of
the facemask installed upon a wearer's face. The mask is shown in
the unfolded or partially unfolded position. The upper malleable
stiffener 71 imbedded or attached to the mask has been folded,
crimped, pinched, bent, creased, and/or angled around the wearer's
nose and/or cheek area and causes a projection 72 in the filter
material that conforms it to a portion of the nose and/or cheek.
The lower malleable stiffener 74 imbedded or attached to the mask
has been crimped, bent, creased, folded, pinched, and/or angled
around or under the wearer's chin and/or jaw area and causes a
projection 75 in the filter material that conforms to a portion of
the wearer's chin and/or jaw area. In some embodiments, the
projection 75 will be located under the chin so that the user can
rest it on it. The mask provides a secure and comfortable fit for
the user by simply pinching the malleable stiffeners. In this way,
the mask reduces leakage of material around the top, bottom and
edges of the masks. It will be understood by those of ordinary
skill in the art that the projections in the outside of the mask 72
and 75 can be aligned vertically with each other or be
substantially parallel to each other so that projection 72 and 75
line up and the masks can be stacked one on top of the other.
[0090] In some embodiments, individuals who wear eyeglasses also
are plagued by the problem of fogging of their glasses due to
condensation of warm, vapor laden exhaled air on the colder surface
of their eyeglasses. Ensuring a secure fit along the upper edge of
the facemask helps to reduce fogging of eyeglasses due to the
condensation of vapor laden air. The nanofibers can be combined
with FogFree.RTM. face masks, some with fog free strips, available
from CrossTex (Hauppauge, N.Y.).
[0091] In some embodiments, for easy grasping, the facemask may be
thermally molded or heat set to increase stiffness. In other
embodiments, binder chemicals may be added to the materials prior
to formation of the mask. The facemask can be disposable and/or for
single use.
Indicator
[0092] In FIG. 6, the outer surface 73 of the facemask comprises a
temperature, moisture, and/or pathogen indicator. Although shown on
the outer surface, it will be understood by those of ordinary skill
in the art that this indicator can be disposed on or in the outer,
inner, and/or middle layer.
[0093] The indicator provides a visual indication when a certain
temperature, and/or moisture is reached and/or when a pathogen is
detected.
[0094] The indicator can have for example, a thermochromic dye,
such as for example, that disclosed in U.S. Pat. No. 4,826,550, the
entire disclosure is herein incorporated by reference, to provide
the indication of a temperature change in the mask. When the
temperature threshold is reached, it results in a visual
indication. For example, at temperatures above 60.degree. F., above
70.degree. F., above 85.degree. F., above 87.degree. F., or above
97.degree. F., the indicator will change color. Desirably, the
visual indication of a change in temperature threshold is a change
in color. This can signal the user to change the mask.
[0095] In some embodiments, the indicator can be a label, strip,
film, and/or tape that can change between two colors, or between a
colored condition and colorless condition. A thermochromic material
can have an activation temperature, which is the temperature at
which the material has reached its final color (or clear) state.
For example, a thermochromic material can be provided in the form
of microcapsules which contain crystal violet lactone, a weak acid,
and a dissociable salt dissolved in a non-polar or slightly polar
solvent liquid crystal solvent such as dodecanol or another
suitable liquid crystal solvent. When the temperature is room
temperature, the dye exists in its lactone leuco form. However,
when the temperature increases, the liquid crystal solvent melts,
the salt dissociates, the pH inside the microcapsule lowers (making
protons readily available), the dye becomes protonated, and the
lactone ring opens causing its absorption spectrum to shift,
absorbing in the visible spectrum, such as a deeply violet color
for crystal violet lactone. Suitable thermochromic dyes can be
based on mixtures of leucodyes with suitable other chemicals, which
display a color change (usually between a colorless leuco form and
the colored form of the dye) dependent on the temperature.
[0096] Thermochromic materials which can be used in the current
application also include, but are not limited to, spirolactones,
fluorans, spiropyrans, or fulgides. Weak acids that can be used as
proton donors include bisphenol A, parabens, 1,2,3-triazole
derivatives, and 4-hydroxycoumarin. These weak acids can function
as a proton donor to cause a dye molecule to change between its
leuco form and its protonated colored form. Stronger Bronsted acids
(better proton donors) can also be used but they tend to make the
color change irreversible. Other thermosensitive dyes that can be
used include an oxazine-based leuco thermosensitive dye (such as
that sold under the trade mark CSB-12 by Hodogaya Chemicals Co), a
spiropyran-based leuco thermosensitive dye (such as that sold under
the trade mark CSR-13 by Hodogaya Chemicals Co), a quinoline-based
thermosensitive dye (such as that sold under the trade mark CSY-13
by Hodogaya Chemicals Co) or the like.
[0097] Specific thermosensitive dyes that can be used in the
thermochromic material are non-toxic and are known to activate at
temperatures in the range of 21 to 51.degree. C. and which are
available from SICPA Securink Corporation of Springfield, Va. These
dyes include 744020TC (thermochromic blue), 744010TC (thermochromic
turquoise), 744027TC (thermochromic yellow), 734010TC
(thermochromic rose), 724010TC (thermochromic orange), 754027TC
(thermochromic green). There are also thermochromic dyes which lose
color when heated, so that they change from a color towards clear.
These dyes include 178002TC (black/clear) which is active at 80 to
97 degrees C. and 128001TC (orange/clear), 1384175TC (rose/clear),
150015TC (green/clear), 148003TC (blue/clear), 17800TC
(black/clear), 14001TCBR (blue/red), or 128001TCY (orange/yellow),
or combinations thereof.
[0098] In some embodiments, for moisture detection, the indicator
can comprise an agent that changes colors based on pH such as, for
example, bromophenol blue. For example, as moisture from
respiration or sweat occurs in the mask, the pH will decrease and
the color will be indicated so the user can change the mask.
[0099] FIG. 7 illustrates an embodiment of the indicator shown as a
strip 77. The strip at one end has a section 81 that can be held
and used to pull the strip from the mask. This embodiment is useful
for example when the strip is going to be used to test a pathogen.
The strip can be pulled from the mask and the strip can be cultured
to see what pathogen can grow (bacteria, virus, mold, etc.). The
strip can be attached to the mask by velcro, adhesive, glue, or
other attachment means. In some embodiments, the strip comprises an
indicator region 83 disposed on the strip that gives a visual
indication (certain color, color change, or turn colorless, etc.)
when a certain threshold temperature, moisture, and/or pathogen is
present so that the mask can be changed or used only for a certain
period of time. The strip can comprise a region 85 that does not
contain any visual indication. In some embodiments, the strip can
comprise the same material as the mask, for example, nanofibers and
non-nanofibers.
[0100] In some embodiments, the indicator comprises a collector
that can capture microbes and they can be sent to the laboratory
for identification or in some embodiments, the collector can
capture the microbe and have an indicator to identify the microbe
(e.g., gram positive or gram negative bacteria, etc.). The
collector allows immobilization of the microbes that can be sent to
the lab.
[0101] In some embodiments, the mask can have certain colors for
the malleable member (e.g., strip) so the user can know how to wear
the mask. For example, the nose piece can be a certain color of the
malleable member and the malleable member of the chin piece can be
a different color than the nose piece. Alternatively, the outside
of the mask can be marked with a different color to indicate the
part of the mask to be worn on the nose and that part of the mask
to be worn on the mouth.
Methods of Making
[0102] The facemask may be formed from a variety of materials and
fabrics, such as woven reusable fabrics and nonwoven disposable
fabrics or webs. As used herein, the term "nonwoven fabric" or
"nonwoven web" or "nonwoven material" means a web having a
structure of individual fibers or threads that are randomly
interlaid, but not in an identifiable manner or pattern as in a
knitted fabric. Nonwoven fabrics or webs have been formed from many
processes, for example, meltblowing processes, spunbonding
processes, and bonded carded web processes.
[0103] As used herein, the term "spunbond" or "spunbond fibers" or
"spunbonded fibers" refers to small diameter fibers that are formed
by extruding molten thermoplastic material as filaments from a
plurality of fine, usually circular capillaries of a spinneret with
the diameter of the extruded filaments then being rapidly reduced,
for example, as in U.S. Pat. No. 4,340,563 to Appel et al., and
U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No.
3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394
to Kinney, U.S. Pat. No. 3,502,763 to Hartman, and U.S. Pat. No.
3,542,615 to Dobo et al.
[0104] As used herein, the term "meltblown" or "meltblown fibers"
means fibers formed by extruding a molten thermoplastic material
through a plurality of fine, usually circular, die capillaries as
molten threads or filaments into converging high velocity, usually
hot, gas (e.g. air) streams that attenuate the filaments of molten
thermoplastic material to reduce their diameter, which may be to
microfiber diameter. Thereafter, the meltblown fibers are carried
by the high velocity gas stream and are deposited on a collecting
surface to form a web of randomly disbursed meltblown fibers. Such
a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to
Butin et al.
[0105] The facemask may be formed from a single layer or multiple
layers of material or a composite of multiple layers. In the case
of multiple layers, the layers are generally positioned in a
juxtaposed or surface-to-surface relationship and all or a portion
of the layers may be bound to adjacent layers. The multiple layers
of a composite may be joined to form a multilayer laminate by
various methods, including but not limited to adhesive bonding,
thermal bonding, or ultrasonic bonding.
[0106] One composite material suitable for use with the present
application is a spunbond/meltblown/spunbond (SMS) laminate. An SMS
laminate may be made by sequentially depositing onto a moving
forming belt first a spunbond fabric layer, then a meltblown fabric
layer and last another spunbond layer and then bonding the laminate
in a manner described below. Alternatively, the fabric layers may
be made individually, collected in rolls, and combined in a
separate bonding step. Multilayer laminates may have multiple
meltblown layers or multiple spunbond layers in many different
configurations and may include materials other than nonwovens.
Examples of such other materials include wovens, films, foam/film
laminates and combinations thereof, for example, a
spunbond/film/spunbond (SFS) laminate. Examples of other composite
materials suitable for use in the present invention include, but
are not limited to, those described in U.S. Pat. No. 4,041,203 to
Brock et al., U.S. Pat. No. 5,169,706 to Collier, et al., U.S. Pat.
No. 5,145,727 to Potts et al., U.S. Pat. No. 5,178,931 to Perkins
et al., U.S. Pat. No. 4,374,888 to Bornslaeqer, and U.S. Pat. No.
5,188,885 to Timmons et al., which are all incorporated herein by
reference.
[0107] The facemask of the present application may include a layer
of material, for example, a nonwoven material, suitable for
filtration. The filtration material may be made from a meltblown
nonwoven web and, in some embodiments, may be subject to electret
treating. As used herein, the term "electret" or "electret
treating" refers to a treatment that imparts a charge to a
dielectric material, such as a polyolefin. The charge includes
layers of positive or negative charges trapped at or near the
surface of the polymer, or charge clouds stored in the bulk of the
polymer. The charge also includes polarization charges that are
frozen in alignment of the dipoles of the molecules. Methods of
subjecting a material to electret treating are well known by those
skilled in the art. These methods include, for example, thermal,
liquid-contact, electron beam, and corona discharge methods. One
particular technique of subjecting a material to electret treating
is disclosed in U.S. Pat. No. 5,401,466, the contents of which are
herein incorporated in its entirety by reference. This technique
involves subjecting a material to a pair of electrical fields
wherein the electrical fields have opposite polarities. Electret
treatment results in a charge being applied to the filtration
medium that further increases filtration efficiency by drawing
particles to be filtered toward the filter by virtue of their
electrical charge. Electret treatment can be carried out by a
number of different techniques. One technique is described in U.S.
Pat. No. 5,401,446 to Tsai and incorporated herein by reference in
its entirety. Other methods of electret treatment are known in the
art, such as that described in U.S. Pat. No. 4,215,682 to Kubik et
al., U.S. Pat. No. 4,375,718 to Wadsworth, U.S. Pat. No. 4,592,815
to Nakao and U.S. Pat. No. 4,874,659 to Ando, incorporated herein
by reference in their entirety.
[0108] Alternatively, the mask may include a layer of expanded
polytetrafluoroethylene (PTFE) membrane for filtration, such as
those manufactured by W. L. Gore & Associates. A more complete
description of the construction and operation of such materials can
be found in U.S. Pat. No. 3,953,566 to Gore and U.S. Pat. No.
4,187,390 to Gore, incorporated herein by reference in their
entirety.
[0109] In some embodiments, the facemask comprises one or more
layers individually or combined made of medical grade tissue, spun
bound polypropylene, cellulose material, meltblown polypropylene,
spun bound high density polyethylene, and/or low density
polyethylene.
[0110] In some embodiments, one or more layers of the mask may be
impervious or substantially impervious to liquid (e.g., spun bound
polypropylene, and/or meltblown polypropylene layer(s)), which may
cause liquid to bead on one or more surfaces or layers of the
mask.
[0111] In some embodiments, the facemask can be made by providing
the filter material and inserting or attaching the malleable
stiffening members to the mask, where at least one malleable
stiffening member is partially bent, crimped, creased, folded,
and/or angled and attached to or in the nose portion of the mask,
either on the inside of the mask or outside of it and then
attaching a second malleable stiffening member to the lower portion
of the mask for the chin and/or jaw area; and attaching securing
members to the mask, either on the inside of the mask or outside of
it.
[0112] In some embodiments, the bend portion is pinched, crimped,
bent, creased, folded, or angled toward the inner surface or outer
surface of the facemask by about 1 to 10 degrees or by 1 mm to
about 20 mm by hand or machine, before, during or after it is
attached or imbedded in the mask. These include crimping machines
having stops, posts, or the like that allow the bend portion to be
formed.
[0113] Having now generally described the invention, the same may
be more readily understood through the following reference to the
following examples, which are provided by way of illustration and
are not intended to limit the present invention unless
specified.
Examples
[0114] Tables 1-3 below display the differential pressure or
pressure drop between the interior of the facemask and the
surrounding environment using a facemask of the present disclosure
having nanofiber layers. Tables 1-3 also display the differential
pressures measured using a facemask without a discrete nanofiber
layer and a three layer melt-blown nonwoven fiber facemask without
a discrete nanofiber layer. Three separate trials runs were
performed for each facemask as represented by Tables 1, 2 and 3,
respectively. Air was directed through an inner surface of the mask
representing the flow of a wearer's breath during exhalation.
Differential pressure drop was measured for air flows of 25, 125,
250 and 500 liters per minute. The results are displayed below.
TABLE-US-00001 TABLE 1 Mask 1 Differential Pressure Air flow Face 3
layer 3 layer melt-blown liters/min (l/m) mask nanofiber (nf)
nonwoven fiber (mb) 25 8.47 0.46 8.14 125 42.1 3.03 38.7 250 78.3
4.31 75.3 500 141 15.8 127
TABLE-US-00002 TABLE 2 Mask 2 Air Flow Differential Pressure (l/m)
Face mask 3 layer nf 3 layer mb 25 10 0.416 8.48 125 55.3 2.79 49.4
250 97.1 4.17 90.6 500 187 9.82 158
TABLE-US-00003 TABLE 3 Mask 3 Airflow Differential Pressure (l/m)
Face mask 3 layer nf 3 layer mb 25 11.2 0.548 12.3 Cfm 125 57.9
2.82 62 Cfm 250 116 5.81 116 Cfm 500 221 11.8 222 cfm
[0115] As shown in Tables 1-3, the differential pressures measured
for the facemask of the present disclosure is as much as
approximately 18 times lower than the differential pressures
measured for facemasks without discrete nanofiber layers. The
differential pressure is directly related to the amount of air that
gets deflected above and below the facemask. Therefore, a lower
differential drop associated with the use of the facemask of the
present disclosure results in a reduced amount of air deflection
and an increased amount of air that passes through the facemask
rather than around the facemask. Facemasks without discrete
nanofiber layer(s) demonstrated higher air deflection and therefore
less airflow through the facemask.
[0116] The nanofiber coating can have a thickness from between 0.03
grams per square meter (gsm) to about 1.0 gsm, or 1-60 gsm.
Further, each surface of the filter material can have multiple
coatings of nanofiber layers to increase the thickness of the
nanofiber coating. The length of each nanofiber can be below
approximately 0.01 deniers.
[0117] FIG. 8 is a graphic illustration showing different mask
filtration. Those marked with "T" were taped to the face; those not
marked with a T were not taped. The nanofiber masks had greater
filtration than other masks.
[0118] FIG. 9 is a graphic illustration showing different pressure
differentials with various masks. The pressure differentials were
lower with the nanofiber masks indicating reduced deflection and
better filtration.
[0119] By having the nanofibers on the inside surface of the outer
layer or on the middle layer or inner layer or in place of the
middle layer, there is low pressure differential between layers and
there is enhanced filtration efficiency. There is also enhanced
bidirectional flow of air. In some embodiments, the nanofibers can
be integrally adhered (e.g., applied) to the inside of the outer
layer material.
[0120] It will be apparent to those skilled in the art that various
modifications and variations can be made to various embodiments
described herein without departing from the spirit or scope of the
teachings herein. Thus, it is intended that various embodiments
cover other modifications and variations of various embodiments
within the scope of the present teachings.
* * * * *