U.S. patent application number 11/169636 was filed with the patent office on 2006-06-08 for microbicidal air filter.
Invention is credited to Normand Bolduc.
Application Number | 20060117729 11/169636 |
Document ID | / |
Family ID | 37561739 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060117729 |
Kind Code |
A1 |
Bolduc; Normand |
June 8, 2006 |
MICROBICIDAL AIR FILTER
Abstract
Microbicidal air filter for use with an air passageway, which
includes an immobilization network including a plurality of fibers
having an amount of at least one antimicrobial agent incorporated
and molecularly bonded into a structure thereof sufficient to
substantially immobilize, retain and at least inhibit the growth
of, or typically kill, microbes suspended in a volume of air moving
through the air passageway. The immobilization network is
substantially permeable to air. A microbicidal facemask and a
microbicidal air filter used in an air circulation system using the
immobilization network are disclosed.
Inventors: |
Bolduc; Normand; (Laval,
CA) |
Correspondence
Address: |
Franz Bonsang;c/o PROTECTIONS EQUINOX INT'L INC.
Suite 224
4480, Cote-de-Liesse
Montreal
QC
H4N 2R1
CA
|
Family ID: |
37561739 |
Appl. No.: |
11/169636 |
Filed: |
June 30, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10455337 |
Jun 6, 2003 |
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11169636 |
Jun 30, 2005 |
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09982804 |
Oct 22, 2001 |
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10455337 |
Jun 6, 2003 |
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Current U.S.
Class: |
55/524 |
Current CPC
Class: |
Y10S 55/05 20130101;
B01D 2239/065 20130101; B01D 2239/0442 20130101; A62B 23/025
20130101; B01D 39/086 20130101; A62B 18/025 20130101; B01D 46/10
20130101; B01D 2239/0618 20130101; B01D 39/1623 20130101; B01D
2239/1208 20130101; B01D 39/083 20130101; B01D 2239/0654 20130101;
B01D 46/0028 20130101; B01D 2239/0636 20130101; B01D 46/30
20130101 |
Class at
Publication: |
055/524 |
International
Class: |
B01D 46/00 20060101
B01D046/00 |
Claims
1. Microbicidal air filter for use with an air passageway, said air
filter comprising: an immobilization network including a plurality
of fibers having an amount of at least one antimicrobial agent
incorporated and molecularly bonded into a structure thereof
sufficient to substantially immobilize, retain and at least
substantially inhibit the growth of microbes suspended in a volume
of air moving through said air passageway, said immobilization
network being substantially permeable to said air.
2. The filter, according to claim 1, in which said at least one
antimicrobial agent kills microbes suspended in the volume of
air.
3. The filter, according to claim 1, in which said plurality of
fibers arranged in a mesh, said mesh defining a plurality of air
spaces between said fibers.
4. The filter, according to claim 3, in which said fibers are
tightly woven or loosely woven.
5. The filter, according to claim 4, in which said fibers are
treated PVC based organic fibers.
6. The filter, according to claim 1, in which said antimicrobial
agent is selected from the group consisting of: an antibacterial
agent an anti-vital agent, an anti-dust mite agent, an anti-mold
agent and an anti-yeast agent.
7. The filter, according to claim 6, in which said antimicrobial
agent is TRICLOSAN.TM..
8. The filter, according to claim 6, in which said antimicrobial
agent is benzyl benzoate.
9. The filter, according to claim 1, in which said immobilization
network is an after-filter so that the air is pre-filtered prior
reaching the air passageway.
10. The filter, according to claim 1, in which said air filter is a
facemask configured and sized to fit over the nose and mouth of a
user and to be secured therearound.
11. The filter, according to claim 1, in which said air filter is
an air duct filter configured and sized to fit in an air duct
system forming the air passageway.
12. The filter, according to claim 11, in which said air filter
further includes: first and second air permeable screen elements
securable together along respective peripheral edges, said screen
elements being configured and sized to fit In the air duct system
and to be secured therein; said air permeable immobilization
network being located substantially between said first and second
screen elements.
13. The filter, according to claim 12, in which a fastening member
connects said first and second air permeable screen elements
together to sandwich said immobilization network therebetween.
14. The filter, according to claim 13, in which said fastening
member includes a frame for connecting said first and second screen
elements together.
15. The filter, according to claim 14, in which said fastening
member further includes a plurality of stitches located through
said immobilization network to divide said immobilization network
into subdivisions.
16. Microbicidal facemask comprising: first and second air
permeable screen elements secured together along respective
peripheral edges, said screen elements defining a gap therebetween,
said screen elements being configured and sized to fit over the
mouth and nose of a user and to be secured thereto; an air
permeable immobilization network located in and substantially
filling said gap, said immobilization network including a plurality
of fibers having an amount of at least one antimicrobial agent
incorporated and molecularly bonded into a structure thereof
sufficient to substantially immobilize, retain and at least
substantially inhibit the growth of microbes suspended in a volume
of air moving through said network.
17. The facemask, according to claim 16, in which said at least one
antimicrobial agent kills microbes suspended in the volume of
air.
18. The facemask, according to claim 16, in which said
immobilization network includes a plurality of fibers arranged in a
mesh, said mesh defining a plurality of air spaces between said
fibers.
19. The facemask, according to claim 18, in which said fibers are
tightly woven or loosely woven.
20. The facemask, according to claim 19, in which said fibers are
treated PVC based organic fibers.
21. The facemask, according to claim 16, in which said
antimicrobial agent is selected from the group consisting of an
antibacterial agent, an anti-viral agent, an anti-dust mite agent,
an anti-mold agent and an anti-yeast agent.
22. The facemask, according to claim 16, in which said
antimicrobial agent is TRICLOSAN.TM..
23. The facemask, according to claim 16, In which said
antimicrobial agent is benzyl benzoate.
24. The facemask, according to claim 16, in which said
immobilization network is an after-filter so that the air is
pre-filtered prior reaching the air passageway.
25. The facemask, according to claim 16, in which said first air
permeable screen element includes a slit located therein of
sufficient size to allow said immobilization network to be
positioned in said gap.
26. The facemask, according to claim 16, in which said
Immobilization network includes RHOVYL'AS.TM. fibers.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part (C.I.P.) of
application Ser. No. 10/455,337, filed on Jun. 6, 2003, now
abandoned, that is a continuation-in-part (C.I.P.) of application
Ser. No. 09/982,804, filed on Oct. 22, 2001, now abandoned.
FIELD OF THE INVENTION
[0002] The present invention concerns air filters, more
particularly microbicidal air filters.
BACKGROUND OF THE INVENTION
[0003] Removing airborne pathogens and environmental allergens is
very important in environments that require high levels of air
purity, such as in hospitals and in houses of people suffering from
severe allergic responses to the aforesaid allergens. Typically,
devices in the form of masks or in-air duct filters filter out
particulate material during either air circulation or, in the case
of facemasks, during inhalation and exhalation. The facemasks and
air duct filters temporarily capture the pathogens and allergens,
and particulate matter such as dust, on a surface of a filtering
material. Once the filters reach a threshold limit or after a
single use, they are typically discarded or in some cases, cleaned
and reused. Many designs of filtering devices exist, examples of
which are as follows: [0004] U.S. Pat. No. 1,319,763, issued Oct.
28, 1919, to Drew for "Air filter for wall registers"; [0005] U.S.
Pat. No. 3,710,948, issued Jan. 16, 1973, to Sexton for
"Self-sustaining pocket type filter"; [0006] U.S. Pat. No.
3,779,244, issued Dec. 18, 1973, to Weeks for "Disposable face
respirator"; [0007] U.S. Pat. No. 3,802,429, issued Apr. 9, 1974,
to Bird for "Surgical face mask"; [0008] U.S. Pat. No. 4,197,100,
issued Apr. 8, 1980, to Hausheer for "Filtering member for
filters"; [0009] U.S. Pat. No. 4,798,676, issued Jan. 17, 1989, to
Matkovich for "Low pressure drop bacterial filter and method";
[0010] U.S. Pat. No. 5,525,136, issued Jun. 11, 1996, to Rosen for
"Gasketed multi-media air cleaner"; [0011] U.S. Pat. No. 5,747,053
issued May 5, 1998, to Nashimoto for "Antiviral filter air cleaner
impregnated with tea extract"; [0012] U.S. Pat. No. 5,906,677,
issued May 25, 1999, to Dudley for "Electrostatic supercharger
screen"; [0013] U.S. Pat. No. 6,036,738 issued Mar. 14, 2000, to
Shanbrom for "Disinfecting gas filters"; [0014] U.S. Pat. No.
6,514,306 issued Feb. 4, 2003, to Rohrbach et al. for
"Anti-microbial fibrous media".
[0015] The aforesaid designs suffer from a number of important
drawbacks. Disadvantageously, in the above-mentioned designs
removal of the dirty filter or the facemask after use may cause
non-immobilized pathogens or particulates to be dispersed into the
air immediately around the user, which, if inhaled may be hazardous
to the user. In addition, the designs may not immobilize the air
borne pathogens and kill them in situ. Some of the designs
incorporate viscous material into the filter material to capture
particulate material. Some designs incorporate complex arrangements
of filters inside cartridges, which may be impractical for use in
air ducts or in facemasks. In some cases, fiberglass is used as
part of the filter medium, which may be harmful to humans if
located near the nose and mouth. In one design, disinfectant soaked
cotton wool appears to be located in an air duct for aerosolizing
into a room to maintain moisture content. Use of such a wet
disinfectant may be harmful to humans in close proximity to the
disinfectant and may not be appropriate for use in a facemask.
Another filter media uses fibers having cavities filled with
antibacterial agent for slow release there from. Another design
discloses the fiber manufactured with antibacterial agent therein
that freely detaches there from upon blooming of the fibers. These
fiber designs have the problem of a rapid lost of their
antibacterial activity upon cleaning or washing thereof.
[0016] Accordingly, there is a need for an improved microbicidal
air filter.
SUMMARY OF THE INVENTION
[0017] The present invention reduces the difficulties and
disadvantages of the prior art by providing a microbicidal air
filter, which captures and kills pathogenic microbes on a novel
immobilization network of fibers. To achieve this, the fibers
include an antimicrobial agent incorporated into their structure,
during manufacturing of the fibers, for the latter to substantially
kills the microbes getting in proximity thereto. The antimicrobial
agent is internally and externally secured to the structure of the
fibers with strong molecular bonds. This significantly reduces or
essentially eliminates the problems associated with further release
of the microbes from the filter after use and during disposal.
Advantageously, the filter can be used as a facemask or in
air-circulation ducts, typically as an after-filter or downstream
of a filter, and can capture and kill a wide variety of microbes.
The fibers can be made of a material, such as but not limited to
polyvinyl chloride (PVC) based materials, which enables the filter
to be washed and reused, almost indefinitely, without significant
loss of antimicrobial activity because of the molecular bonds
between the antimicrobial agent and the structure of the
fibers.
[0018] In accordance with an aspect of the present invention, there
is provided a microbicidal air filter for use with an air
passageway, said air filter comprising: an immobilization network
including a plurality of fibers having an amount of at least one
antimicrobial agent incorporated and molecularly bonded into a
structure thereof sufficient to substantially immobilize, retain
and at least inhibit the growth of, or typically kill, microbes
suspended in a volume of air moving through said air passageway,
said immobilization network being substantially permeable to said
air.
[0019] In one embodiment, the immobilization network is an
after-filter so that the air is pre-filtered prior reaching the air
passageway.
[0020] In one embodiment, the air filter is a facemask configured
and sized to fit over the nose and mouth of a user and to be
secured therearound.
[0021] In one embodiment, the air filter is an air duct filter
configured and sized to fit in an air duct system forming the air
passageway.
[0022] Typically, the air filter further includes: first and second
air permeable screen elements securable together along respective
peripheral edges, said screen elements being configured and sized
to fit in the air duct system and to be secured therein; said air
permeable immobilization network being located substantially
between said first and second screen elements.
[0023] Conveniently, a fastening member connects said first and
second air permeable screen elements together to sandwich said
immobilization network therebetween.
[0024] Typically, the fastening member includes a frame for
connecting said first and second screen elements together.
[0025] Conveniently, the fastening member further includes a
plurality of stitches located through said immobilization network
to divide said immobilization network into subdivisions.
[0026] In accordance with another aspect of the present invention,
there is provided a microbicidal face mask comprising: first and
second air permeable screen elements secured together along
respective peripheral edges, said screen elements defining a gap
therebetween, said screen elements being configured and sized to
fit over the mouth and nose of a user and to be secured thereto; an
air permeable immobilization network located in and substantially
filling said gap, said immobilization network including a plurality
of fibers having an amount of at least one antimicrobial agent
incorporated and molecularly bonded into a structure thereof
sufficient to substantially immobilize, retain and at least inhibit
the growth of, or typically kill, microbes suspended in a volume of
air moving through said network.
[0027] In one embodiment, the first air permeable screen element
includes a slit located therein of sufficient size to allow said
immobilization network to be positioned in said gap.
[0028] Further advantages and objects of the invention will be in
part obvious from an inspection of the accompanying drawings and a
careful consideration of the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In the annexed drawings, like reference characters indicate
like elements throughout.
[0030] FIG. 1 is a simplified exploded view of an embodiment of a
filter;
[0031] FIG. 2 is a simplified partial cutaway view of a facemask
with the filter;
[0032] FIG. 2a is a simplified partial cutaway view of an
alternative embodiment of a facemask;
[0033] FIG. 3 is a simplified exploded view of an embodiment of a
filter in a frame;
[0034] FIG. 4 is a simplified exploded view of the filter with a
primary filter;
[0035] FIG. 5 is a simplified exploded view of an air circulation
system with a filter;
[0036] FIG. 6 is simplified front view of an alternative filter for
use in the system of FIG. 5;
[0037] FIG. 7 is a simplified front view of an alternative filter
for use with the system of FIG. 5, showing stitches as a fastening
member;
[0038] FIG. 8 is a simplified front view of an alternative filter
for use with the system of FIG. 5, showing rivets as a fastening
member; and
[0039] FIG. 9 is a cross sectional view taken along lines 9-9 of
FIG. 7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] With reference to the annexed drawings the preferred
embodiments of the present invention will be herein described for
indicative purposes and by no means as of limitation.
Definitions
[0041] As used herein, the term "microbe" or "microbial" is
intended to mean microorganisms including, but not limited to,
bacteria, protozoa, viruses, molds and the like. Also included in
this definition are dust mites.
[0042] As used herein, the term "antimicrobial agent" is intended
to mean a compound that inhibits, prevents, or destroys the growth
or proliferation of microbes such as bacteria, protozoa, viruses,
molds and the like. Examples of antimicrobial agents as used herein
include anti-bacterial agents, anti-viral agents, anti-mold agents,
anti-yeast agents and anti-dust mite agents, or any combination
thereof.
[0043] As used herein, the terms "anti-bacterial agent",
"bacteriocidal agent" and "bacteriostatic agent" are intended to
mean compounds that inhibit, prevent the growth of, and/or kill
bacteria.
[0044] As used herein, the term "anti-viral agent" is intended to
mean a compound that inhibits, prevents the growth of, or kills
viruses.
[0045] As used herein, the term "anti-mold agent" is intended to
mean a compound that inhibits, prevents the growth of, or kills
molds.
[0046] As used herein, the term "anti-yeast agent" is intended to
mean a compound that inhibits, prevents the growth of, or kills
yeasts.
[0047] As used herein, the term "anti-dust mite agent" is intended
to mean a compound that inhibits, prevents the growth of, or kills
dust mites.
[0048] As used herein, the terms "microbicidal", "biocidal" and
"aseptic" are intended to refer to the inhibition, growth
prevention or killing properties of any of the aforesaid "agents",
used either alone or in combination with each other.
Preferred Embodiments
[0049] Referring now to FIG. 1, a first embodiment of a
microbicidal air filter shown generally at 10. Broadly speaking,
the filter 10 includes an air permeable immobilization network 12,
an air permeable first screen 14 and an air permeable second screen
16. The first screen 14 and the second screen 16 are merely acting
to support the network 12 and to define a work area 18. One skilled
in the art will recognize that the immobilization network 12 may be
used independently of the screens 14 and 16.
[0050] The network 12 includes a mesh of fibers 20, which can be
non-woven or woven depending on whether a soft or hard (rigid)
network is desired. The network 12 may also include yarn such as
cotton in which the fibers 20 are interwoven. Each fiber 20
includes a quantity of at least one antimicrobial agent that is
fully incorporated and secured to the structure of the fiber 20 via
substantially strong molecular bonds thereby providing a large
permanent concentration of the antimicrobial agent over a large
surface area, throughout the entire life of the fibers 20. In other
words, the antimicrobial agent is within the heart of the fiber 20
and bondly mixed and spread there along, there over and therein.
The fibers 20 are arranged such that they are permeable to air over
the entire mesh, typically as a fine layer of so-called angel's
hair, of flaky mesh or the like.
[0051] Preferably, the network is a fibrous material. More
preferably, the fibrous material is commercially available
RHOVYL'AS+.TM., RHOVYL'AS.TM. (with "AS" for reference to
"aseptic"), THERMOVYL-L9B.TM., THERMOVYL-ZCB.TM., THERMOVYL-MXB.TM.
(with "B" for reference to "biocidal") or triclosan treated
polyvinyl chloride (PVC) or the like based organic fiber.
[0052] Both RHOVYL'AS+.TM., RHOVYL'AS.TM., THERMOVYL-L9B.TM.,
THERMOVYL-MXB.TM. and THERMOVYL-ZCB.TM. are fibrous materials,
manufactured by RHOVYL.TM., SA, that have instrinsic antimicrobial
and/or biocidal activity. In particular, the RHOVYL'AS.TM. fiber,
the THERMOVYL-L9B.TM. fiber and the THERMOVYL-ZCB.TM. fiber
incorporate an antibacterial agent, which is molecularly bonded to
the structure of the fiber, whereas the RHOVYL'AS.TM. fiber
antibacterial agent, the RHOVYL'AS+.TM. fiber and the
THERMOVYL-MXB.TM. fiber also contain acaricide, an anti-dust mite
agent. triclosan is a well known antimicrobial agent, which at
least reduces the growth, and typically even kills microbes such as
bacteria, yeast and molds.
[0053] The fibrous material is either used pure (100%) or in
blends, with a percentage of at least 30% volume, along with other
types of fibers within woven or non-woven type fabrics, and which
meet the requirements of an individual protective equipment (IPE).
The fibrous material may also have other properties including, but
not limited to, non-flammability, resistance to chemical products,
ignition suppression, thermal insulation, and moisture
management.
[0054] Preferably, the antimicrobial agents include an
antibacterial agent, an anti-viral agent, an anti-dust mite agent,
an anti-mold agent and an anti-yeast agent.
[0055] Preferably, the anti-bacterial agent is triclosan.
[0056] Preferably, the anti-dust mite agent is benzyl benzoate.
[0057] Typically, the fibrous material has porosity in the range of
about 0.1 .mu.m to about 3 .mu.m, although this depends upon the
size of microbe to be retained.
[0058] Typically, the fibrous material has a density of between two
grams per square foot (2 gr/ft.sup.2) to thirty grams per square
foot (30 gr/ft.sup.2). More preferably, the density is around ten
grams per square foot (10 gr/ft.sup.2).
[0059] As best illustrated in FIG. 2, the filter 10 may be part of
a facemask 24 of the type normally used by hospital workers and the
like and which could be expandable (soft mask) or not (rigid mask),
that are sometimes used in areas with pre-filtered air. The screens
14 and 16 are typically connected around a peripheral edge 22 and
define a gap 23 therebetween. The network 12 can be attached to one
of the aforesaid screens to provide both a physical barrier against
particulate material and more importantly, to pathogenic microbes.
The network 12 can be attached to the screens 14 or 16 using a
VELCRO.TM. type fastener, stitches, bonding and the like, or inside
an individual portable mask 24 that are worn in front of the
nose/mouth area of the individual. A front mask screen 25 of the
mask 24 acts as a primary filter located upstream of the network 12
to pre-filter the air by removing particulate material and microbes
from the air passing therethrough along an air passageway, as shown
by the arrows.
[0060] Alternatively, as best illustrated in FIG. 2a, the network
12 may be located between the front screen 25 and a rear screen 27,
such as commercially available filter masks, in the gap 23 of the
facemask 24 to create a two-way system of filtration, as shown by
the arrows. The front screen 25 may include a slit 29 to allow the
network 12 to be inserted into the gap 23. This type of facemask 24
may be useful for people who are suffering from a respiratory
infection and who still wish to work yet, don't wish to infect
others by exhaling breath contaminated with pathogenic
microbes.
[0061] The screen elements 14, 16 can have different sizes and
shapes and can be simple typical flexible or semi-flexible type
screens as illustrated in FIG. 1, made from aluminum, nylon,
thermoplastic material, fiberglass type materials (usually not
approved for mask applications), woven type fabrics or the like. As
shown in FIG. 3, the screen elements 14, 16 and the network 12 can
be supported by a rigid frame 26, such as a standard aluminum
screen frame, that is divided into two parts 28, 30 and integral
with the screen elements 14, 16 respectively, to ensure rigidity
and ease of installation. A fastening member 32 may be used to
releasably connect the two screen elements 14, 16 together with the
network 12 sandwiched therebetween and compressed to prevent it
from being displaced by the air flowing therethrough. The fastening
member 32 may be a pivoting retainer pivoting on one of the parts
28, 30 to retain the other part against the same. Alternatively, as
best illustrated in FIG. 4, a rigid screen 34 of any existing air
filter 36 may also be used.
[0062] Referring now to FIGS. 5 and 6, the filter 10 is illustrated
installed inside an air duct 38 downstream of the air filter 36 and
upstream of an air heating system 40 (the arrows in FIG. 5 show the
air passageway) such that the air passing through the network 12
could be pre-filtered such that the network 12 acts as an
after-filter, thereby being more efficient since most of the
particulate material or dirt contained in the air is removed there
from before reaching the network. The frame 26 generally encloses
the screen elements 14, 16 but also includes intermediate
reinforcing rods 42 used to subdivide the screen elements 14, 16
into a plurality of smaller sub-elements 44 to constrain the
network 12 to remain in place between the two elements 14, 16.
Alternatively, as best seen in FIG. 6, the frame 26 is a thin
metallic rod onto which the screens 14, 16 are attached, with
reinforcing rods 42 providing additional support to the screen
elements 14, 16 and to the network 12 and to provide the aforesaid
sub-elements 44.
[0063] Referring now to FIGS. 5, 7, 8 and 9, other types of
fastening members 32 are illustrated. One preferable type of
fastening member 32 includes a plurality of stitches 46 which may
be arranged in a variety of patterns, for example wavy lines or
straight lines. The stitches 46 pass through the network 12 and
divide the network into subdivisions 44, as previously described.
Alternatively, as best illustrated in FIG. 8, the fastening members
32 may also include rivets 48, which pass through the network
12.
EXAMPLES
[0064] The present invention is illustrated in further detail by
the following non-limiting examples.
Example 1
Evaluation of Microbicidal and Filtering Capacity of Rigid and Soft
Facemasks
[0065] As shown in Table 1, two facemasks of the present invention
were compared to a commercially available facemask.sup.1,2,3 for
their antimicrobial and retaining capabilities against a panel of
bacteria and molds of various sizes.sup.4,5,6,7. The NB rigid and
soft masks used in Examples 1 and 2 were both equipped with a
network 12 of PVC based organic fiber containing molecularly bonded
triclosan. The NB soft mask was composed of a double covering of
woven type fabric containing 76% w/w THERMOVYL-ZCB.TM. fibers and
24% w/w polyester (although any other woven type fabric such as
cotton or the like could have been used) stitched to each other at
their periphery, within which the network 12 was located (see FIG.
2a above). The NB rigid mask was made of two conventional
commercially available anti-dust masks, which were inserted one
inside the other, between which the network of PVC based organic
fiber containing triclosan was located.
[0066] An air contamination chamber.sup.5,8,9 was used to measure
the filtering capacity of a mask containing the network. The
chamber includes a perforated bottle containing a predetermined
quantity of lyophilized microorganisms. The chamber is installed on
a microbiologic air-sampler. The test mask was installed at the
interface between the contaminated air chamber and the air sampler.
A negative pressure was generated in the air chamber, which caused
the lyophilized microorganisms to move towards the mask. A
culturing medium was located downstream of the mask to detect any
breakthrough of the mask. TABLE-US-00001 TABLE 1 Filtration
efficiency (%) Microorganisms Size (.mu.m) NBRM NBSM 3M* Bacteria
Mycobacteria tuberculosis 0.2-0.7 .times. 1.0-10 100 100 95 Proteus
spp. 0.4-0.8 .times. 1-3 100 100 Pseudomonas aureginosa 0.5-1.0
.times. 1.5-5 100 100 Staphylococcus aureus 0.5 .times. 1.5 100 100
Streptococcus 0.5-1.5 100 100 pneumoniae Haemophilius influenze 1
100 100 Anthrax 1-1.5 .times. 3-5 100 100 Moulds Acremonium
strictum 3.3-5.5 (7) .times. 100 100 96 0.9 .times. 1.8 Aspergillus
versicolor 2-3.5 100 100 Penicillium griseofulvum 2.5-3.5 .times.
2.2-2.5 100 100 Neosartorya fischeri 2 .times. 2.5 100 100 NBRM =
Rigid mask NBSM = Soft mask *Data from technical
specification.sup.2
Example 2
Evaluation of Filtering of Small Particles
[0067] The filtering capacity of the three masks of Example 1 was
tested against two particulate materials of 0.3 .mu.m particle size
using essentially the same apparatus as in Example 1. A cartridge
capturing membrane located downstream from an air pump, in this
case, captured breakthrough particulates. The air pump creates a
negative pressure downstream of the mask. The two particulate
materials chosen were sodium chloride and dioctyl phthalate.
TABLE-US-00002 TABLE 2 Filtration efficiency (%) Particulate
material Size (.mu.m) NBRM NBSM 3M* Sodium chloride (NaCl) 0.3 100
100 95 Dioctylphthalate (DOP) 0.3 100 100 NBRM = Rigid mask NBSM =
Soft mask *Data from technical specification.sup.2
Example 3
Evaluation of Microbicidal and Filtering Capacity of a Ventilation
System Filter
[0068] The antimicrobial capacity of a filter of the embodiment of
FIG. 3 with RHOVYL'AS+.TM. fibers was evaluated after 0, 7, 14, and
21 days installation in a ventilation system in a house. The
results are illustrated in Tables 3 to 6 below.
[0069] The filters were removed after the aforesaid times and
analysed using the Samson method.sup.10. The fibrous material (1 g)
of each filter was diluted with demineralised, sterilized water (9
mL) and then serially diluted.
[0070] The calculation of total amount of bacteria, yeast and molds
were done using hemacytometry. The calculation of the total amount
of viable bacteria, yeasts and molds were determined following a
culture of the serial dilutions on appropriate media. The aerobic
viable bacteria were cultured on soya agar-agar (TSA, Quelab),
whereas the yeasts and molds were cultured on HEA supplemented with
gentamycin (0.005% p/v) and oxytetracycline (0.01% p/v) to limit
bacterial growth. HEA's pH of 4.8+/-0.2 allows the germination of
spores and development of mycelens. After the incubation period,
the calculation of microbial colonies was carried out using a
colony meter (Accu-Lite.TM., Fisher). The morphotype of the
bacterial colonies was identified by Gram staining (see Table
5).
[0071] Concerning the yeasts and molds calculation, each
macroscopically distinct mold colony was identified by gender
and/or species using microscopy.
[0072] Mold slides were prepared using the adhesive tape
method.sup.11. This technique maintains the integrity of the mold
structures by fixing them on the sticky side of the tape. Once
collected, the molds were stained with lactophenol and observed at
a magnification of 10.times. and 40.times.. Using identification
keys.sup.12,13,14,15, the molds were identified. In this experiment
only colonies that produced spores were identified. TABLE-US-00003
TABLE 3 Bacterial filtering After filter Calculated bacteria
(UFC/g) Time (days) Viable Non-viable Total 0 6000 169000 175000
(3.43%) (96.57%) (100%) 7 9000 318000 327000 (2.75%) (97.25%)
(100%) 14 27000 1193000 1220000 (2.21%) (97.79%) (100%) 21 70000
3650000 3720000 (1.88%) (98.12%) (100%)
[0073] TABLE-US-00004 TABLE 4 Fungal filtering After filter
Calculated fungi (UFC/g) Time (days) Viable Non-viable Total 0
29000 218000 247000 (11.74%) (88.26%) (100%) 7 110000 970000
1080000 (10.19%) (89.81%) (100%) 14 230000 2400000 2630000 (8.75%)
(91.25%) (100%) 21 1640000 21000000 22640000 (7.24%) (92.76%)
(100%)
[0074] TABLE-US-00005 TABLE 5 Identification of bacterial
morphotypes After filter (days) Bacterial morphotypes 0 78.4% Cocci
Gram positive 21.6% Rod Gram negative 7 84.3% Cocci Gram positive
15.7% Rod Gram negative 14 86.7% Cocci Gram positive 13.3% Rod Gram
negative 21 88.9% Cocci Gram positive 11.1% Rod Gram negative
[0075] TABLE-US-00006 TABLE 6 Identification of mold species After
filter (days) Mold species 0 Aspergillus niger, Cladosporium
cladosporioides, Cladosporium herbarum, Penicillium sp., yeasts 7
Aspergillus niger, Cladosporium cladosporioides, Cladosporium
herbarum, Penicillium sp., yeasts 14 Alternaria alternata,
Arthrinium sp., Aspergillus niger, Cladosporium sp., Geotrichum
sp., Penicillium sp., yeasts 21 Aspergillus niger, Cladosporium
cladosporioides, Cladosporium herbarum, Penicillium sp., yeasts
Example 4
Evaluation of Antimicrobial Activity after Extensive Washing
Antibacterial of Woven Fiber Samples
[0076] In order to ensure the antimicrobial fibers of the present
invention retain their antimicrobial activity after multiple
cleaning and washing, respective samples of woven THERMOVYL-L9B.TM.
and THERMOVYL-ZCB.TM. fibers with molecularly bonded triclosan
agent were tested. Three (3) samples of each fiber types were
submitted to multiple successive cleanings and tested for
antibacterial activity against growth of two bacteria, namely
Staphylococcus aureus and Escherichia coli, after five (5), ten
(10) and one hundred (100) washes, respectively. One (1) witness
reference sample of each fiber type without any antimicrobial agent
was also similarly tested after five (5) washes. The results are
summarized in Table 7 below. TABLE-US-00007 TABLE 7 Bacteria
Bacteria Inhibition Growth/ Number of Zone Size Antimicrobial
Bacteria Fiber Washes (mm) Efficiency S. aureus Thermovyl-L9B 5
12.5 None/High 10 13 None/High 100 14.75 None/High Thermovyl-ZCB 5
12.125 None/High 10 12.625 None/High 100 16.75 None/High
Thermovyl-L9* 5 0 Medium/Poor Thermovyl-ZC* 5 0 Medium/Poor E. coli
Thermovyl-L9B 5 5.125 None/High 10 6.125 None/High 100 8.125
None/High Thermovyl-ZCB 5 5 None/High 10 5.375 None/High 100 9.375
None/High Thermovyl-L9* 5 0 Medium/Poor Thermovyl-ZC* 5 0
Medium/Poor *Without microbicidal agent
Discussion
[0077] To date, commercially available masks have been hampered by
their inability to capture and kill in excess of 95% of
microorganisms. A study of a microbicidal network of the present
invention, in the form of the facemasks and filters in a
ventilation system, has demonstrated a significant improvement in
capturing and killing efficiency (Tables 1 to 6).
[0078] Tables 1 and 2 illustrated the effectiveness of PVC based
organic fiber containing triclosan as particulate filters,
anti-bacterial and anti-mold filters. For both the soft facemask
and the rigid facemask, the anti-microbial and particulate
filtering capacities were 100% compared to the corresponding
capacities for a commercially available mask (95 to 96%).
[0079] Tables 3 to 7 illustrate highly efficient levels of
antimicrobial and filtering capacity of the filter of the present
invention. Specifically, the inventor has demonstrated, in Tables 3
and 4, that the combined anti-bacterial, anti-fungal, and retaining
capacities are each 100%.
[0080] In addition, the inventor has demonstrated that different
bacterial morphotypes, as is illustrated in Table 5, were captured
on the filter after zero (0) days 96.6% (78.8% and 21.6% of cocci
Gram-positive and rod Gram-negative type bacteria respectively) of
the whole bacteria population present on the fibers of the filter.
After twenty-one days (21) 98.1% (88.9% and 11.1% of cocci
Gram-positive and rod Gram-negative type bacteria respectively)
were present on the fibers of the filter. This demonstrates that
the efficiency of the filer remains after an extended period. As
illustrated in Table 6, a variety of pathogenic molds were
identified on the filter of the present invention up to twenty-one
days.
[0081] If desired, the filter can be cleaned, washed, as well as
resist other treatments and be reused without a significant loss of
the aforesaid capacities, or even with an increase of the aforesaid
capacities with increasing number of washes, as illustrated in
Table 7.
[0082] A key feature of the filter 10, whether it be in the
aforesaid facemasks or the circulation system duct filter, is its
ability to immobilize, retain and kill or inhibit the growth of a
wide variety of microbes, which come into contact with the network
12 of fibers 20. Air that is either pre-filtered, in the case of
the circulation system, or inhaled/exhaled through the facemask by
the user, often includes residual microbes that have either passed
through the primary filter or the filter has failed to immobilize
them. In the case where a person who uses the facemask of the
present invention and who has an upper respiratory infection, such
as influenza, tuberculosis, anthrax, severe acute respiratory
syndrome (SARS) and the like, can significantly reduce or
essentially eliminate further infection to other people. Similarly,
air that is contaminated with pathogenic microbes can be filtered
before entering into the nose and mouth area of the user. The flow
of air is shown by the arrows in FIGS. 2, 2a, and 5, in which air
contaminated with microbes is shown as hatched lines and
non-hatched arrows show clean, filtered air.
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* * * * *
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