U.S. patent application number 12/670556 was filed with the patent office on 2010-09-02 for unitary respirator with molded thermoset elastomeric elements.
This patent application is currently assigned to 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Paul J. Flannigan, Jahannes Hoogenraad, David P. Knivsland.
Application Number | 20100218761 12/670556 |
Document ID | / |
Family ID | 39809369 |
Filed Date | 2010-09-02 |
United States Patent
Application |
20100218761 |
Kind Code |
A1 |
Flannigan; Paul J. ; et
al. |
September 2, 2010 |
UNITARY RESPIRATOR WITH MOLDED THERMOSET ELASTOMERIC ELEMENTS
Abstract
A respiratory protection composite facepiece is disclosed and
includes a polymeric rigid facepiece body portion having a first
surface and a second surface and a silicone sealing facepiece
element chemically bonded at least one of the first surface or the
second surface. The first and second surfaces can be opposing major
surfaces. A second silicone element is chemically bonded to at
least one of the first surface or the second surface. Methods of
making the same are also disclosed.
Inventors: |
Flannigan; Paul J.;
(Roseville, MN) ; Hoogenraad; Jahannes; (Plymouth,
MN) ; Knivsland; David P.; (North St. Paul,
MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M INNOVATIVE PROPERTIES
COMPANY
Saint Paul
MN
|
Family ID: |
39809369 |
Appl. No.: |
12/670556 |
Filed: |
July 15, 2008 |
PCT Filed: |
July 15, 2008 |
PCT NO: |
PCT/US08/70043 |
371 Date: |
January 25, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60999743 |
Aug 31, 2007 |
|
|
|
Current U.S.
Class: |
128/201.19 ;
128/206.24; 264/279; 29/527.1 |
Current CPC
Class: |
B29D 99/0053 20130101;
Y10T 29/4998 20150115; A62B 18/025 20130101; A62B 18/10 20130101;
B29K 2083/005 20130101; B29K 2081/00 20130101; B29C 65/483
20130101; B29C 2045/14327 20130101; A62B 23/025 20130101; A62B
18/08 20130101; B29C 45/14311 20130101; B29L 2031/4835 20130101;
A62B 18/084 20130101; B29C 45/1657 20130101 |
Class at
Publication: |
128/201.19 ;
264/279; 128/206.24; 29/527.1 |
International
Class: |
A62B 18/08 20060101
A62B018/08; B29C 63/22 20060101 B29C063/22; A62B 18/10 20060101
A62B018/10; B23P 17/00 20060101 B23P017/00 |
Claims
1. A respiratory protection composite facepiece comprising: a
polymeric rigid facepiece body portion having a first surface and a
second surface; a silicone sealing facepiece element chemically
bonded to at least one of the first surface or the second surface;
and a second silicone element chemically bonded to at least one of
the first surface or the second surface.
2. A respiratory protection composite facepiece according to claim
1, wherein the polymeric rigid facepiece body portion further
comprises an inhalation valve or an exhalation valve and the second
silicone element forms a diaphragm for the inhalation valve or the
exhalation valve.
3. (canceled)
4. A respiratory protection composite facepiece according to claim
1, wherein the polymeric rigid facepiece body portion further
comprises a speaking port and the second silicone element forms a
diaphragm for the speaking port.
5. A respiratory protection composite facepiece according to claim
1, wherein the silicone sealing facepiece element is chemically
bonded to the first surface and the second surface.
6. A respiratory protection composite facepiece according to claim
1, wherein the polymeric rigid facepiece body portion comprises a
plurality of apertures extending through the polymeric rigid
facepiece body portion and the silicone sealing facepiece element
interpenetrates at least a portion of the apertures.
7. A respiratory protection composite facepiece according to claim
1, wherein the polymeric rigid facepiece body portion comprises a
thermoplastic polymer and the silicone sealing facepiece element
and the second silicone element is a thermoset polymer and the
thermoset polymer chemically bonds directly onto the thermoplastic
polymer.
8. A respiratory protection composite facepiece according to claim
1, wherein the polymeric rigid facepiece body portion further
comprises an inhalation valve and the second silicone element forms
a gasket surrounding the inhalation valve.
9. A respiratory protection composite facepiece according to claim
1, wherein the second silicone element forms at least a portion of
one or more straps configured to secure the respiratory protection
composite facepiece to a user's head.
10. A respiratory protection composite facepiece comprising: a
polymeric rigid facepiece body portion having a first surface and a
second surface and a inhalation port; a silicone sealing facepiece
element chemically bonded to at least one of the first surface or
the second surface and forming a gasket about the inhalation
port.
11. A respiratory protection composite facepiece according to claim
10, wherein the silicone sealing facepiece element is chemically
bonded to the first surface and the second surface.
12. A respiratory protection composite facepiece according to claim
10, wherein the polymeric rigid facepiece body portion comprises a
plurality of apertures extending through the polymeric rigid
facepiece body portion and the silicone sealing facepiece element
interpenetrates at least a portion of the apertures.
13. A method of forming a respiratory protection composite
facepiece comprising: overmolding liquid silicone onto a polymeric
rigid facepiece body portion having a first surface and a second
surface, the liquid silicone in contact with at least one of the
first surface or the second surface; and solidifying the liquid
silicone to form a silicone sealing facepiece element that
chemically bonds to one of the first surface or the second surface,
and a second silicone element chemically bonded to at least one of
the first surface or the second surface, forming a respiratory
protection composite facepiece.
14. A method according to claim 13, wherein the polymeric rigid
facepiece body portion further comprises an inhalation valve or an
exhalation valve and the solidifying step forms a second silicone
element diaphragm for the inhalation valve or the exhalation
valve.
15. A method according to claim 13, wherein the solidifying step
solidifies the liquid silicone to form a silicone sealing facepiece
element that chemically bonds to the first surface and the second
surface.
16. A method according to claim 13, wherein the polymeric rigid
facepiece body portion comprises a plurality of apertures extending
through the polymeric rigid facepiece body portion and the
overmolding step interpenetrates liquid silicone into at least a
portion of the apertures to form the silicone sealing facepiece
element.
17. (canceled)
18. A method according to claim 13, wherein the solidifying step
second silicone element forms at least a portion of one or more
straps configured to secure the respiratory protection composite
facepiece to a user's head.
19. A method according to claim 14, further comprising attaching a
chemical or particulate filtration cartridge to the inhalation
valve.
20. A method of forming a respiratory protection composite
facepiece comprising: overmolding liquid silicone onto a polymeric
rigid facepiece body portion having a first surface and a second
surface, the liquid silicone in contact with at least one of the
first surface or the second surface; and solidifying the liquid
silicone to form a silicone sealing facepiece element that
chemically bonds to one of the first surface or the second surface,
and forming a gasket about the inhalation port.
21. A method according to claim 20, wherein the solidifying step
solidifies the liquid silicone to form a silicone sealing facepiece
element that chemically bonds to the first surface and the second
surface.
22. A method according to claim 20, wherein the polymeric rigid
facepiece body portion comprises a plurality of apertures extending
through the polymeric rigid facepiece body portion and the
overmolding step interpenetrates liquid silicone into at least a
portion of the apertures to form the silicone sealing facepiece
element.
Description
FIELD
[0001] The present disclosure relates to a unitary respirator with
molded thermoset elastomeric elements and particularly to a
respirator facepiece with a thermoset elastomeric face seal and
another thermoset elastomeric element.
BACKGROUND
[0002] Half-mask respirators provide respiratory protection from
airborne substances with filtering processes and/or otherwise
facilitating access to clean air. One characteristic of these
devices is the seal that is formed between the user and other
functional components of the respirator. Respirators often utilize
an elastomeric material to form the seal which is often referred to
as the "faceseal."
[0003] One design consideration with these respirators is the
air-tight fastening of the elastomeric faceseal with the solid
structural components of the respirator. This air-tight seal often
requires a mechanical seal that adds complexity and cost to the
respirator design. Another design consideration is the formation
and attachment of other elastomeric elements of the respirator.
These other elastomeric elements also add complexity and cost to
the respirator design.
BRIEF SUMMARY
[0004] The present disclosure relates to a unitary respirator with
molded thermoset elastomeric elements and particularly to a
respirator facepiece with a thermoset elastomeric face seal and
another thermoset elastomeric element. This disclosure further
relates to a respirator facepiece having a polymeric rigid
facepiece body portion and a silicone sealing facepiece element and
a second silicone element that is chemically bonded to at least one
major surface of the polymeric rigid facepiece body portion. In
many embodiments, the silicone sealing facepiece element and a
second silicone element is chemically bonded to at least two major
surfaces of the polymeric rigid facepiece body portion. In some
embodiments, the silicone sealing facepiece element and the second
silicone element penetrates through at least one aperture in the
polymeric rigid facepiece body portion.
[0005] In a first embodiment, a respiratory protection composite
facepiece includes a polymeric rigid facepiece body portion having
a first surface and a second surface and a silicone sealing
facepiece element chemically bonded to at least one of the first
surface or the second surface. The first and second surfaces can be
opposing major surfaces. A second silicone element is chemically
bonded to at least one of the first surface or the second surface.
In some embodiments, the silicone sealing facepiece element and/or
second silicone element may be chemically bonded to at least two
opposing major surfaces of the polymeric rigid facepiece body
portion. The silicone sealing facepiece element and/or second
silicone element may in some cases also interpenetrate apertures
that extend through the polymeric rigid facepiece body portion. The
second silicone element may form a diaphragm for the inhalation
valve, the exhalation valve, or speaking diaphragm, or form a
sealing gasket about an inhalation port, or form at least a portion
of headstraps.
[0006] In another embodiment, a respiratory protection composite
facepiece includes a polymeric rigid facepiece body portion having
a first surface and a second surface and an inhalation port. A
silicone sealing facepiece element is chemically bonded to at least
one of the first surface or the second surface and forming a gasket
about the inhalation port. The first and second surfaces can be
opposing major surfaces. The gasket is chemically bonded to at
least one of the first surface or the second surface. In some
embodiments, the silicone sealing facepiece element and/or gasket
may be chemically bonded to at least two opposing major surfaces of
the polymeric rigid facepiece body portion. The silicone sealing
facepiece element and/or gasket may in some cases also
interpenetrate apertures that extend through the polymeric rigid
facepiece body portion.
[0007] In a further embodiment, a method of forming a respiratory
protection composite facepiece includes overmolding liquid silicone
onto a polymeric rigid facepiece body portion having a first
surface and a second surface, where the liquid silicone is in
contact with at least one of the first surface or the second
surface, and solidifying the liquid silicone to form a silicone
sealing facepiece element that chemically bonds to one of the first
surface or the second surface. A second silicone element is
chemically bonded to at least one of the first surface or the
second surface, forming a respiratory protection composite
facepiece. The second silicone element may form a diaphragm for the
inhalation valve, the exhalation valve, or speaking diaphragm, or
form a sealing gasket about an inhalation port, or form at least a
portion of headstraps
[0008] In a still further embodiment, a method of forming a
respiratory protection composite facepiece includes overmolding
liquid silicone onto a polymeric rigid facepiece body portion
having a first surface and a second surface, where the liquid
silicone is in contact with at least one of the first surface or
the second surface, and solidifying the liquid silicone to form a
silicone sealing facepiece element that chemically bonds to one of
the first surface or the second surface, and forming a gasket about
the inhalation port.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention may be more completely understood in
consideration of the following detailed description of various
embodiments of the invention in connection with the accompanying
drawings, in which:
[0010] FIG. 1 is a perspective view of an illustrative respiratory
protection mask;
[0011] FIG. 2 and FIG. 3 are schematic cross-section views of an
illustrative inhalation or exhalation diaphragm valve;
[0012] FIG. 4 is a schematic cross-section view of an illustrative
speaking diaphragm;
[0013] FIG. 5 is a perspective view of an illustrative rigid
facepiece body for a respirator protection mask;
[0014] FIG. 6 is a perspective front view of the rigid facepiece
body shown in FIG. 5 illustrating a silicone sealing facepiece
element overmolded onto half of the rigid facepiece body;
[0015] FIG. 7 is a perspective rear view of the rigid facepiece
body shown in FIG. 5 illustrating a silicone sealing facepiece
element overmolded onto half of the rigid facepiece body;
[0016] FIG. 8 is a schematic cross-sectional view of portion of a
respiratory protection composite facepiece illustrating a
mechanical interlock created when the liquid silicone
interpenetrates an aperture through the rigid facepiece body;
and
[0017] FIG. 9 is a perspective partial exploded view of an
illustrative respiratory protection mask.
[0018] The figures are not necessarily to scale. Like numbers used
in the figures refer to like components. However, it will be
understood that the use of a number to refer to a component in a
given figure is not intended to limit the component in another
figure labeled with the same number.
DETAILED DESCRIPTION
[0019] In the following description, reference is made to the
accompanying drawings that form a part hereof, and in which are
shown by way of illustration several specific embodiments. It is to
be understood that other embodiments are contemplated and may be
made without departing from the scope or spirit of the present
invention. The following detailed description, therefore, is not to
be taken in a limiting sense.
[0020] All scientific and technical terms used herein have meanings
commonly used in the art unless otherwise specified. The
definitions provided herein are to facilitate understanding of
certain terms used frequently herein and are not meant to limit the
scope of the present disclosure.
[0021] Unless otherwise indicated, all numbers expressing feature
sizes, amounts, and physical properties 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 foregoing specification
and attached claims are approximations that can vary depending upon
the desired properties sought to be obtained by those skilled in
the art utilizing the teachings disclosed herein.
[0022] The recitation of numerical ranges by endpoints includes all
numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2,
2.75, 3, 3.80, 4, and 5) and any range within that range.
[0023] As used in this specification and the appended claims, the
singular forms "a", "an", and "the" encompass embodiments having
plural referents, unless the content clearly dictates otherwise. As
used in this specification and the appended claims, the term "or"
is generally employed in its sense including "and/or" unless the
content clearly dictates otherwise.
[0024] The term "respirator" means a personal respiratory
protection device that is worn by a person to filter air before the
air enters the person's respiratory system. This term includes full
face respirators, half mask respirators, supplied air hoods,
powered air purifying respirators, and self contained breathing
apparatus.
[0025] The present disclosure relates to a unitary respirator with
molded thermoset elastomeric elements and particularly to a
respirator facepiece with a thermoset elastomeric face seal and
another thermoset elastomeric element. The present disclosure also
relates to a respirator facepiece having an inhalation port and a
thermoset elastomeric face seal that also surrounds the inhalation
port forming an inhalation port gasket. This disclosure further
relates to a respirator facepiece having a polymeric rigid
facepiece body portion and a silicone sealing facepiece element and
a second silicone element that is chemically bonded to one or two
major surfaces of the polymeric rigid facepiece body portion. In
some embodiments, the silicone sealing facepiece element and the
second silicone element also penetrates through the polymeric rigid
facepiece body portion. This respirator facepiece can be formed by
molding a thermoset silicone sealing facepiece element and a second
silicone element onto the polymeric thermoplastic rigid facepiece
body portion sequentially or at the same time. These respirator
facepieces have a robust bond between the silicone elements and the
rigid facepiece body portion. While the present invention is not so
limited, an appreciation of various aspects of the invention will
be gained through a discussion of the examples provided below.
[0026] The unitary respirator having an overmolded thermoset
elastomeric seal and another overmolded element provides a face
sealing element and other elastomeric element that is integrally or
chemically bonded with the polymeric rigid facepiece body portion.
This construction has been found to enhance the durability of the
elastomeric elements and prevent debris from being interposed
between the polymeric rigid facepiece body portion and the
thermoset elastomeric elements. This integral construction also
reduces the number of assembly parts and part size variability. The
overmolded thermoset elastomeric materials described herein also do
not require that the polymeric rigid facepiece body portion be
primed in order for the thermoset elastomeric elements to be
chemically attached or bonded to the polymeric rigid facepiece body
portion.
[0027] FIG. 1 is a perspective view of an illustrative respiratory
protection mask 10. The respiratory protection mask 10 includes a
respiratory protection composite facepiece 11 attached to number of
respiratory protection elements including, for example, one or more
inhalation valves with an optional chemical or particulate
filtration cartridge 28 connected to one or more of the inhalation
valves, one or more exhalation valves 32, one or more speaking
diaphragms and/or one or more headstraps or straps 34 configured to
secure the respiratory protection composite facepiece 11 to a
user's head.
[0028] The respiratory protection composite facepiece 11 includes a
silicone sealing facepiece element 12 overmolded onto a polymeric
rigid facepiece body 20 (as described in more detail below). The
chemical or particulate filtration cartridge 28 to can be either
fixedly attached or removably attached to the one or more of the
inhalation valves. In some embodiments, the silicone sealing
facepiece element 12 also forms a seal or gasket (as described in
more detail below) between the chemical or particulate filtration
cartridge 28 and the polymeric rigid facepiece body 20 or
inhalation valve (as described in more detail below). The chemical
or particulate filtration cartridge 28 can have any useful shape,
other than the shape illustrated in FIG. 1.
[0029] While FIG. 1 illustrates a respiratory protection mask 10
having two cheek inhalation valves attached to a chemical or
particulate filtration cartridge 28 and one nose exhalation valve
32, any useful respiratory protection configuration is possible.
For example, the respiratory protection mask 10 can have a single
inhalation valve attached to a chemical or particulate filtration
cartridge 28 or clean air supply and one or two exhalation valves
or one or more speaking diaphragms, as desired.
[0030] FIG. 2 and FIG. 3 are schematic cross-section views of an
illustrative inhalation or exhalation valve. FIG. 4 is a schematic
cross-section view of an illustrative speaking diaphragm. These
inhalation or exhalation valves or speaking diaphragm are located
within or adjacent to the plurality of openings of the rigid
facepiece body 20, described below.
[0031] FIG. 2 illustrates a partial schematic diagram of a
diaphragm valve disposed between an exterior area 1 or 2 and an
interior area 2 or 1 of the illustrative respiratory protection
mask 10. The valve 25 is an inhalation valve when the diaphragm 26
is disposed between the rigid facepiece body 20 and the user's face
or the interior area 2 of the illustrative respiratory protection
mask 10. The valve 25 is an exhalation valve when the diaphragm 26
is disposed between the rigid facepiece body 20 and the exterior
area 1 of the illustrative respiratory protection mask 10. FIG. 3
illustrates the valve allowing either inhalation air 5 or
exhalation air 5 to pass between the diaphragm 26 and the valve
body or rigid facepiece body 20. The exemplary diaphragm 26 is
attached to a valve support element 19 that anchors the diaphragm
26 to the valve body or rigid facepiece body 20. One or more struts
17 (see FIG. 5) can connect the support element 19 that anchors the
diaphragm to the valve body or rigid facepiece body 20.
[0032] FIG. 4 illustrates a partial schematic diagram of a speaking
diaphragm. The illustrative speaking diaphragm includes a diaphragm
27 fixed to the rigid facepiece body 20. While the diaphragm 27 is
illustrated being sandwiched between two rigid facepiece body 20
body portions, the diaphragm 27 may be simply chemically bonded to
one or both of the first surface and a second surface (described
below) and may penetrate through at least one aperture in the
polymeric rigid facepiece body portion (described generally below).
The diaphragm 27 is disposed between the exterior area 1 or 2 and
an interior area 2 or 1 of the illustrative respiratory protection
mask 10. The speaking diaphragm 27 assists in the transmission of
speech from the respiratory protection mask 10 user.
[0033] FIG. 5 is a perspective front view of an illustrative rigid
facepiece body 20 for a respirator protection mask 10. The rigid
facepiece body 20 includes a first surface 21 and a second surface
22. In the illustrated embodiment, the first surface 21 and a
second surface 22 are opposing major surfaces of the rigid
facepiece body 20, separated by a body thickness T. In the
illustrated embodiment, the first surface 21 is an outer surface
(directed toward the environment) and the second surface 22 is an
inner surface (directed toward a user's face). The illustrated
rigid facepiece body 20 includes a plurality of openings or ports
such as, for example, a nose opening 16 and two cheek openings 18.
At least one inhalation valve including a diaphragm (not shown) and
one exhalation valve including a diaphragm (not shown) are disposed
within the plurality of ports or openings and forms the illustrated
rigid facepiece body 20. In some embodiments, a speaking diaphragm
is disposed within one or more of the plurality of ports or
openings.
[0034] In many embodiments, one or more apertures 23 extend through
the body thickness T. During the overmolding manufacture of the
respiratory protection composite facepiece 11 liquid silicone (that
forms the silicone sealing facepiece element 12) flows through the
one or more apertures 23 and forms a mechanical interlock between
the silicone sealing facepiece element 12 and the rigid facepiece
body 20. In some embodiments, the inhalation valve includes a
chemical or particulate filtration cartridge attachment element 29.
In many embodiments, the attachment element 29 is a bayonet
attachment element that mates with a complementary element on the
chemical or particulate filtration cartridge attachment element 29.
A bayonet attachment system is configured for attaching two
portions together, where the two portions include elements other
than mainly threads such that the two portions are attached by
inserting one portion at least partially within the other portion
and rotating one portion relative to the other portion so that the
two portions can be joined without multiple turns.
[0035] FIG. 6 is a perspective front view of the rigid facepiece
body 20 shown in FIG. 5 with a silicone sealing facepiece element
12 overmolded onto half of the rigid facepiece body 20. FIG. 7 is a
perspective rear view of the rigid facepiece body shown in FIG. 5
with a silicone sealing facepiece element overmolded onto half of
the rigid facepiece body. It is understood that the exemplary
respiratory protection composite facepiece 11 includes the silicone
sealing facepiece element 12 overmolded onto both halves of the
rigid facepiece body 20, but is shown as a cross-section of the
silicone sealing facepiece element 12 to more easily illustrate the
contour of the silicone sealing facepiece element 12.
[0036] The rigid facepiece body 20 is described above. The silicone
sealing facepiece element 12 is chemically bonded to at least one
of a first surface and a second surface of the rigid facepiece body
20, such the first surface 21 and/or the second surface 22. In many
embodiments, the silicone sealing facepiece element 12 is
chemically bonded to at least one of the first surface 21 and the
second surface 22, where the first surface 21 and a second surface
22 are major surfaces of the rigid facepiece body 20, separated by
a body thickness T, as described above.
[0037] A second silicone element is chemically bonded to at least
the first surface 21 and/or the second surface 22. The second
silicone element can be any silicone element or component useful in
a respiratory protection mask. The second silicone element can be,
for example, a diaphragm for the inhalation valve, exhalation
valve, or speaking diaphragm, or form a sealing gasket about an
inhalation port, or form at least a portion of headstraps, for
example. The second silicone element can be formed (e.g.,
overmolded) at the same time or sequentially as the silicone
sealing facepiece element 12 is formed (e.g., overmolded).
[0038] During the overmolding manufacture of the respiratory
protection composite facepiece 11 liquid silicone (that forms the
silicone sealing facepiece element 12 or second silicone element)
flows through the one or more apertures 23 and forms a mechanical
interlock between the silicone sealing facepiece element 12 and the
rigid facepiece body 20 once the liquid silicone is cured to its
solid state. During this overmolding process, or in a sequential
overmolding process, the second silicone element is formed by
liquid silicone that flows onto at least the first surface 21
and/or the second surface 22 and optionally through one or more
apertures in the mask body and forms a mechanical interlock between
the mask body and the second silicone element, once the liquid
silicone is cured to its solid state.
[0039] FIG. 8 illustrates a schematic cross-sectional view of
portion of a respiratory protection composite facepiece 11
illustrating a mechanical interlock created when the liquid
silicone interpenetrates an aperture 23 through the rigid facepiece
body 20. The silicone sealing facepiece element 12 and/or second
silicone element can be disposed on and chemically bonded to the
first surface 21 and/or the second surface 22, where the first
surface 21 and a second surface 22 are major surfaces of the rigid
facepiece body 20, separated by a body thickness T, as described
above.
[0040] Referring back to FIG. 6 and FIG. 7, the silicone sealing
facepiece element 12 is configured to form an air-tight seal
between a user's head or face and the rigid facepiece body 20. The
term "air-tight seal" refers to a connection of the silicone
sealing facepiece element 12 to the user's face or head that
substantially prevents unfiltered or ambient air from entering an
interior portion of the respiratory protection composite facepiece
11 at the connection interface. The illustrated silicone sealing
facepiece element 12 includes an in-turned feathered cuff 14 that
contacts a user's face.
[0041] Air-tightness is measured with a vacuum leak test. The test
fixture consists of a sealed chamber with three ports. The volume
of the chamber is approximately 750 cm.sup.3. A respirator
attachment component is affixed to one of the three ports by means
of its bayonet attachment element. A vacuum gauge capable of
measuring the pressure differential between the inside of the
chamber and the ambient air (to at least 25 cm water) is attached
to a second port on the fixture. A vacuum source is attached to the
third port through a shut off valve. To conduct the test, the
shut-off valve is opened and the vacuum source is turned on to
evacuate the chamber to a pressure of 25 cm water below atmospheric
pressure (as indicated by the vacuum gauge). The shut-off valve is
then closed and the vacuum source is turned off. The vacuum level
inside the chamber is monitored for 60 seconds. Inward leakage of
air causes the pressure inside the chamber to increase, thereby
reducing the vacuum level. For the current invention, the pressure
differential between the chamber and the ambient air is greater
than 15 cm of water after 60 seconds. More preferably, the pressure
differential remains above 24 cm of water after 60 seconds.
[0042] The respiratory protection composite facepiece 11 can be
formed by overmolding a thermosetting silicone material onto a
thermoplastic rigid facepiece body 20. The thermosetting silicone
material chemically bonds (i.e., adhesive bonding or covalent
bonding) to the thermoplastic rigid facepiece body 20.
[0043] The terms "chemical bonding or chemically bonded" refer to
physical processes responsible for the attractive interactions
between atoms and molecules and includes covalent and ionic bonds,
as well as hydrogen and van der Waal's bonds and can often depend
on available functional groups on the rigid facepiece body 20
surface and their reactivity with the thermosetting silicone
material. In many embodiments, the thermosetting silicone material
is selected so that pretreatment of the thermoplastic rigid
facepiece body 20 is not necessary. In other words, the
thermosetting silicone material is self-adhesive with the
thermoplastic rigid facepiece body 20. The thermosetting silicone
material is often heated to cure the thermosetting silicone
material during the overmolding process to a temperature sufficient
to cure the thermosetting silicone material but less than a glass
transition temperature of the thermoplastic rigid facepiece body
20.
[0044] As shown in the Examples below, the level of chemical
bonding can be determined by the average force to failure test
method. In many embodiments, the average force to failure is 25 N
or greater, 50 N or greater, or 100 N or greater, or 150 N or
greater, or 200 N or greater, or 300 N or greater.
[0045] The thermoplastic rigid facepiece body 20 can be formed of
any useful thermoplastic material. In many embodiments, the
thermoplastic rigid facepiece body 20 is formed of a polyamide
(e.g., nylon), a polycarbonate, polybutylene-terephthalate,
polyphenyl oxide, polyphthalamide, or mixtures thereof.
[0046] Any useful thermosetting liquid silicone rubber or material
can be utilized to form the silicone sealing facepiece element 12
and second silicone element. Liquid silicone rubber is a high
purity platinum cured silicone with low compression set, great
stability and ability to resist extreme temperatures of heat and
cold. Due to the thermosetting nature of the material, liquid
silicone injection molding often requires special treatment, such
as intensive distributive mixing, while maintaining the material
cool before it is pushed into the heated cavity and vulcanized.
Silicone rubber is a family of thermoset elastomerics that have a
backbone of alternating silicone and oxygen atoms and methyl or
vinyl side groups. Silicone rubbers constitute about 30% of the
silicone family, making them the largest group of that family.
Silicone rubbers maintain their mechanical properties over a wide
range of temperatures and the presence of methyl-groups in silicone
rubbers makes these materials hydrophobic.
[0047] Illustrative thermosetting silicone material includes
self-adhesive liquid silicone rubbers available under the trade
designation: ELASTOSIL LR 3070 from Wacker-Silicones, Munich,
Germany; the KE2095 or KE2009 series (such as, for example,
KE2095-60, KE2095-50, KE2095-40) or X-34-1547A/B, X-34-1625A/B,
X-34-1625A/B all from Shin-Etsu Chemical Co., LTD., Japan. These
self-adhesive liquid silicone rubbers do not require pretreatment
of certain thermoplastic surfaces for the liquid silicone rubbers
to chemically bond to the thermoplastic surface.
[0048] FIG. 9 is a perspective partial exploded view of an
illustrative respiratory protection mask 11. The mask includes a
rigid facepiece body 20 is described above, a silicone sealing
facepiece element 12 is chemically bonded to the rigid facepiece
body 20, a nose opening 16 and two cheek openings 18. At least one
inhalation port 18 or valve including a diaphragm (i.e., second
silicone element) and one exhalation port 16 or valve including a
diaphragm 26 (i.e., second silicone element) is disposed within the
plurality of ports or openings. A silicone gasket 31 (i.e., second
silicone element) is disposed about the chemical or particulate
filtration cartridge attachment element 29 and inhalation port 18
or valve. The silicone gasket 31 forms an air-tight seal with the
chemical or particulate filtration cartridge 28 and the rigid
facepiece body 20.
[0049] The silicone gasket 31 and silicone exhalation diaphragm 26
(and inhalation diaphragms) can be formed simultaneous or
sequentially and chemically bonded to the to the rigid facepiece
body 20. In some embodiments, silicone gasket 31 and silicone
exhalation diaphragm 26 (and inhalation diaphragms) penetrate
through the rigid facepiece body 20 as illustrated in FIGS. 2, 3,
and 8.
[0050] The chemical or particulate filtration cartridge 28 to can
be either fixedly attached or removably attached to the chemical or
particulate filtration cartridge attachment element 29. The
chemical or particulate filtration cartridge 28 can have any useful
shape, other than the shape illustrated in FIG. 9.
EXAMPLES
[0051] Several tests were used to identify suitable combinations of
silicone rubbers and thermoplastic materials. Of particular
interest is the strength of the bond between the silicone rubber
and thermoplastic material, which affects the durability of the
air-tight seal.
[0052] The test strip is prepared by molding a rigid, flat
substrate piece 51 mm long, 25 mm wide, and 2 mm thick with
thermoplastic material. The substrate is then clamped into a second
mold such that 6 mm of one end of the substrate protrudes into the
cavity of the second mold. The cavity of the second mold is 27 mm
wide and 49 mm long. The depth of the mold is 2 mm, expanding to 4
mm in the immediate vicinity of the protruding substrate end, such
that when silicone is injected into the mold cavity it forms a
layer 1 mm thick on all sides of the protruding substrate end. The
resulting test strip is thus 94 mm long, with a rigid thermoplastic
substrate piece on one end and silicone rubber on the other
end.
[0053] The strength of the bond between the substrate material and
silicone is measured by gripping the two ends of the test strip in
the jaws of a mechanical tester such as an MTS Model 858 Material
Test System (MTS Systems Corporation, Eden Prairie, Minn.),
stretching it until the test strip breaks apart, and recording the
force at which failure occurs. Examples of the force to failure are
shown in Table 1. Examples 1 through 4 show that bond strengths
greater than 300 N can be achieved with the appropriate combination
of materials. For Comparative Examples C1 and C2, the silicone did
not bond to the thermoplastic material.
TABLE-US-00001 Thermoplastic Average Force Example Silicone
Substrate to Failure (N) 1 Shin-Etsu KE2095 60 RTP Nylon 6/6 136 2
Wacker 3070-60 RTP Nylon 6/6 303 3 Dow LC-70-2004 Zytel PA 174 4
Wacker 3070-60 Zytel PA 166 C1 Dow LC-70-2004 RTP Nylon 6/6 No
bonding C2 Shin-Etsu KE2095 60 Zytel PA No bonding Dow LC-70-2004
silicone is produced by Dow Corning Corporation, Midland MI; RTP
Nylon 6/6 is a polyamide produced by RTP Company, Winona, MN; Zytel
PA is a polyamide produced by E.I. du Pont de Nemours, Wilmington,
DE.
[0054] Thus, embodiments of the UNITARY RESPIRATOR WITH MOLDED
THERMOSET ELASTOMERIC ELEMENTS are disclosed. One skilled in the
art will appreciate that the present invention can be practiced
with embodiments other than those disclosed. The disclosed
embodiments are presented for purposes of illustration and not
limitation, and the present invention is limited only by the claims
that follow.
* * * * *