U.S. patent application number 10/426933 was filed with the patent office on 2004-01-08 for doors and methods of producing same.
Invention is credited to Kepler, Steven P., Minke, Ronald C., Nemazi, John E., Redding, David R., Templeton, G. Daniel.
Application Number | 20040003559 10/426933 |
Document ID | / |
Family ID | 33415944 |
Filed Date | 2004-01-08 |
United States Patent
Application |
20040003559 |
Kind Code |
A1 |
Minke, Ronald C. ; et
al. |
January 8, 2004 |
Doors and methods of producing same
Abstract
One aspect of the present invention is directed to a door, and
more specifically, to a door that includes a web and a rigid foamed
core. In one embodiment, a door is disclosed which comprises a door
shell having a generally planar construction with marginal edges
and first and second door skins helping to define an interior door
cavity, a web disposed within the interior door cavity, and a rigid
foamed cementitious core disposed within the interior door cavity
and cooperating with the web.
Inventors: |
Minke, Ronald C.;
(Leo-Cedarville, IN) ; Templeton, G. Daniel; (Fort
Wayne, IN) ; Redding, David R.; (Fort Wayne, IN)
; Kepler, Steven P.; (Leo-Cedarville, IN) ;
Nemazi, John E.; (Bloomfield Hills, MI) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Family ID: |
33415944 |
Appl. No.: |
10/426933 |
Filed: |
April 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10426933 |
Apr 29, 2003 |
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10131056 |
Apr 24, 2002 |
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Current U.S.
Class: |
52/309.9 ;
52/784.1 |
Current CPC
Class: |
B28B 7/243 20130101;
E06B 5/10 20130101; E06B 2003/7028 20130101; B28B 1/50 20130101;
B28B 1/14 20130101; E06B 2003/703 20130101; E06B 5/16 20130101;
E06B 2003/7063 20130101; E06B 3/825 20130101; B28B 7/42 20130101;
E06B 2003/7067 20130101; B28B 19/00 20130101 |
Class at
Publication: |
52/309.9 ;
52/784.1 |
International
Class: |
E04C 001/00; E04C
002/54 |
Claims
What is claimed is:
1. A door comprising: a door shell having a generally planar
construction with marginal edges and first and second door skins
helping to define an interior door cavity; a mat within the
interior door cavity; and a rigid foamed cementitious core within
the interior door cavity.
2. The door of claim 1 wherein the mat includes openings.
3. The door of claim 2 wherein the mat is comprised of a web.
4. The door of claim 1 wherein the mat is comprised of a
substantially rectangular plastic bladder filled with gas.
5. The door of claim 1 wherein the mat is comprised of a ballastic
resistant material.
6. The door of claim 1 wherein the door shell is comprised of a
blow-molding material.
7. The door of claim 6 wherein the blow-molding material is
comprised of a pre-pigmented plastic.
8. The door of claim 6 wherein the blow-molding material is
comprised of a thermoformed material.
9. The door of claim 8 wherein the thermoformed material is
comprised of a twin-sheet thermoformed material.
10. The door of claim 1 further comprising an adhesive layer
partially coating the internal surface of at least one door skin
for at least partially adhering the rigid foamed cementitious core
to the at least one door skin.
11. The door of claim 10 wherein the adhesive is selected from the
group consisting of latex acrylic, hot melt urethane, epoxy,
pressure sensitive adhesives, and radiation cured adhesives.
12. The door of claim 1 wherein the rigid foamed cementitious core
cooperates with the mat.
13. The door of claim 1 wherein the rigid foamed cementitious core
is comprised of a foamed cement core.
14. The door of claim 1 wherein the door skins are comprised of
fiberglass.
15. The door of claim 1 wherein the door skins are comprised of a
thermoplastic material.
16. The door of claim 3 wherein the rigid foamed cementitious core
is disposed between the first and second door skins and on at least
one side of the web.
17. The door of claim 3 wherein the rigid foamed cementitious core
is disposed between the first and second door skins and on both
sides of the web.
18. The door of claim 3 wherein the web is offset towards one of
the door skins.
19. The door of claim 3 wherein the web is substantially centered
in the interior door cavity.
20. The door of claim 3 wherein the web is closer to one of the
door skins than to the other door skin.
21. The door of claim 3 wherein the web is comprised of a metal
screen.
22. The door of claim 3 wherein the web is comprised of a polymer
woven sheet.
23. The door of claim 1 wherein the rigid foamed cementitious core
prevents the passage of fire for at least about 20 minutes using
test method ASTM E 2074-00 or at least about 30 minutes using test
method BSI 476/22.
24. The door of claim 23 wherein the rigid foamed cementitious core
prevents the passage of fire for at least about 45 minutes using
test method ASTM E2074-00 or at least about 60 minutes using test
method BSI 476/22.
25. The door of claim 1 wherein the foamed cementitious core
provides a sound transmission coefficient rating of at least about
27 using test method ASTM E-413.
26. The door of claim 1 wherein the foamed cementitious core has a
compressive strength of at least about 210 kPa.
27. The door of claim 3 wherein at least two webs are disposed
within the interior door cavity.
28. The door of claim 3 wherein the web is comprised of an expanded
metal mesh.
29. The door of claim 28 wherein the door shell includes a door
frame having first and second rails and first and second
stiles.
30. The door of claim 29 wherein the expanded metal mesh includes
apertures having a first dimension longer than a second dimension
and the first dimension being substantially parallel to the first
and second stiles.
31. A door comprising: a door frame and at least one door skin
being connected and helping to define an interior door cavity; a
mat within the interior door cavity; and a rigid foamed
cementitious core within the interior door cavity.
32. A method of constructing a door comprising: providing a door
shell having a generally planar construction with marginal edges
and first and second door skins helping to define an interior door
cavity; disposing a mat within the interior door cavity; and
disposing a rigid foamed cementitious core within the interior door
cavity, the rigid foamed cementitious core cooperating with the
web.
33. The method of claim 32 wherein the mat includes openings.
34. The method of claim 33 wherein the mat is comprised of a
web.
35. The method of claim 34 wherein the web is disposed within the
interior door cavity prior to disposing the rigid foamed
cementitious core within the interior door cavity.
36. The method of claim 34 wherein the web is disposed offset
towards one of the door skins.
37. The method of claim 34 wherein the web is disposed
substantially centered in the interior door cavity.
38. The method of claim 34 further comprising securing the web to
at least one of the door skins.
39. The method of claim 34 further comprising securing the web to
the marginal edges of the door shell.
40. The method of claim 34 further comprising forming a shelf into
the marginal edges of the door shell.
41. The method of claim 40 wherein the forming step is comprised of
removing a portion of the marginal edges such that a first and
second shelf surface is formed into the marginal edges.
42. The method of claim 41 wherein the first shelf surface is
substantially parallel to the first and second doors skins and the
second shelf surface is substantially perpendicular to the first
and second door skins.
43. The method of claim 42 further comprising securing at least a
portion of the web to at least a portion of the first shelf
surface.
44. The method of claim 43 wherein the second shelf surface is
offset towards one of the door skins.
45. The method of claim 44 wherein the second shelf surface is
substantially centered between the first and second door skins.
46. A door comprising: a door shell having a generally planar
construction with marginal edges and first and second door skins
helping to define an interior door cavity; a polymeric shell
disposed on the interior surface of at least one of the door skins;
and a rigid foam core disposed within the interior door cavity.
47. The door of claim 46 wherein the polymeric shell is the cured
product of a curable mixture.
48. The door of claim 47 wherein the curable mixture includes a
curable resin and a co-curable monomer.
49. The door of claim 48 wherein the curable mixture further
includes a filler material.
50. The door of claim 49 wherein the curable mixture further
includes a fibrous reinforcement material.
51. The door of claim 46 wherein the rigid foam core is comprised
of a rigid foamed cementitious core.
52. The door of claim 51 wherein the rigid foamed cementitious core
is comprised of a foamed cement core.
53. The door of claim 46 wherein the rigid foam core is comprised
of a rigid foamed polyurethane core.
54. A door comprising: a door shell having a generally planar
construction with marginal edges and first and second door skins
helping to define an interior door cavity; a mat disposed within
the interior door cavity and offset towards one of the door skins;
and a rigid foamed polyurethane core disposed within the interior
door cavity and cooperating with the mat.
55. The door of claim 54 wherein the mat includes openings.
56. The door of claim 55 wherein the mat is comprised of a web.
57. The door of claim 56 wherein the web is comprised of expanded
metal mesh.
58. The door of claim 57 wherein the door shell includes a door
frame having first and second rails and first and second
stiles.
59. The door of claim 58 wherein the expanded metal mesh includes
apertures having a first dimension longer than a second dimension
and the first dimension being substantially parallel to the first
and second stiles.
60. The door of claim 56 wherein the rigid foamed polyurethane core
is comprised of the cured product of a polyurethane foam.
61. The door of claim 60 wherein the polyurethane foam has a
density of at least about 2.0 lb/ft.sup.3.
62. A door comprising: a door shell having a generally planar
construction with marginal edges and interior and exterior door
skins helping to define an interior door cavity; a web means for
preventing access to the interior door skin from the exterior door
skin, the web means being within the interior door cavity; and a
rigid foamed cementitious core extending between and connecting at
least portions of the interior and exterior door skins.
63. The door of claim 62 wherein the rigid foamed cementitious core
extends between and connects substantial portions of the skins.
64. The door of claim 62 wherein the rigid foamed cementitious core
is comprised of a rigid foamed cement core.
65. The door of claim 62 wherein the rigid foamed cementitious core
prevents the passage of fire for at least about 20 minutes using
test method ASTM E 2074-00 or at least about 30 minutes using test
method BSI 476/22.
66. The door of claim 65 wherein the rigid foamed cementitious core
prevents the passage of fire fore at least 45 minutes using test
method ASTM E2074-00 or at least about 60 minutes using test method
BSI 476/22.
67. The door of claim 62 wherein the foamed cementitious core
provides a sound transmission coefficient rating of at least about
27 using test method ASTM E-413.
68. The door of claim 62 wherein the foamed cementitious core has a
compressive strength of at least about 210 kPa.
Description
CROSS-REFERENCE TO A RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/131,056, filed Apr. 24, 2002, entitled
"High Performance Door", which is hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] One aspect of the present invention is directed to a door,
and more specifically, to a door that includes a web and a rigid
foamed core.
[0004] 2. Background Art
[0005] Door systems have been designed to pass security tests, such
as British standard PAS 23 (PAS 23), British standard PAS 24 (PAS
24), and Florida Building Code Test TAS/PA 201 (TAS/PA 201). These
door systems are customarily designed to prevent forcible entry by
tools as defined by PAS 23 and PAS 24 and to pass an impact test
simulating large missile debris impact during high velocity wind
storms, such as hurricanes or typhoons, as defined by TAS/PA
201.
[0006] Many steel doors pass some security tests. However, these
doors are less desirable as entry way doors since they lack
aesthetic detail, rust and dent readily. For example, entry way
doors to common areas in apartment complexes and hotels experience
significant use and receive substantial physical abuse, lending to
significant rusting and denting. By way of another example, entry
way doors along salt water coasts receive substantial physical
abuse and are susceptible to corrosive chemical attack.
[0007] Other doors are particularly successful in resisting rust
and denting. For example, fiberglass reinforced plastic (FRP)
doors, glass reinforced plastic (GRP) doors, simple fiberglass
doors, thermoplastic doors (such as PVC doors,
poly-carbonate-skinned doors), and acrylic-capped acrylonitrile
butadiene styrene (ABS) skinned doors commonly have this positive
attribute. This success can be partially attributed to minimizing
the effects of rusting and denting while offering an aesthetically
pleasing appearance at a reasonable price.
[0008] However, these doors have had difficulty meeting the
requirements of PAS 23 and PAS 24. For example, the plastic on
these doors can be cut with tools, such as utility knives and
wrecking bars. These doors have difficulty absorbing the impact of
a nine pound 2".times.4" piece of wood traveling at approximately
35 miles per hour, as required by TAS/PA 201. These results are
unacceptable to certain customers, particularly public housing
officials who control specifications for apartments in the United
Kingdom and to building code officials in high velocity wind zone
areas, such as Florida in the United States.
[0009] In light of the disadvantages inherent in the doors
available in the market place, it would be desirable to provide a
door that successfully passes PAS 23, PAS 24 and/or TAS/PA 201
tests. Moreover, it would be desirable to provide a door that
resists denting and rusting and is reasonably priced through
reduced material costs. Additionally, it would be desirable to
provide a door that is a positive pressure fire rated door and/or
retards sound transmission.
SUMMARY OF THE INVENTION
[0010] According to one aspect of the present invention, doors are
provided that can be used as security doors that can pass PAS 23,
PAS 24, and/or TAS/PA 201 tests.
[0011] An aspect of the present invention provides doors that
resist denting and are reasonably priced.
[0012] Another aspect of the present invention provides doors that
are positive pressure rated doors.
[0013] Yet another aspect of the present invention provides doors
that retard sound transmission.
[0014] In certain embodiments of the present invention, a door
comprising a door shell having a generally planar construction with
marginal edges and first and second door skins helping to define an
interior door cavity, a mat within the interior door cavity, and a
rigid foamed cementitious core within the interior door cavity is
disclosed. In certain embodiments, the mat includes openings, for
example, a web. Examples of materials suitable for the mat,
include, but are not limited to a substantially rectangular plastic
bladder filled with gas, or a ballastic resistant material. The
door shell can be comprised of a blow-molded material, for example,
a pre-pigmented plastic, a thermoformed material or a twin-sheet
thermoformed material. The door skins can be comprised of, for
example, fiberglass or a thermoplastic material.
[0015] The rigid foamed cementitious core can cooperate with the
mat. In one embodiment, the rigid foamed cementitious core is
comprised of a foamed cement slurry. The rigid foamed cementitious
core can be disposed between the first and second door skins and on
at least one side of the web. Alternatively, the core can be
disposed on both sides of the web. The web can be offset towards
one of the door skins or substantially centered in the interior
door cavity. The web can be comprised of many different materials,
for example, metal screen, polymer woven sheet, or expanded metal
mesh.
[0016] In certain embodiments, the door can further comprise an
adhesive layer partially coating the internal surface of at least
one door skin for at least partially adhering the rigid foamed
cementitious core to the at least one door skin. Examples of
suitable adhesives include, but are not limited to, latex acrylic,
hot melt urethane, epoxy, pressure sensitive adhesives, and
radiation cured adhesives.
[0017] In certain embodiments, the rigid foamed cementitious core
prevents the passage of fire for at least about 20 minutes using
test method ASTM E2074-00 or at least about 30 minutes using test
method BSI 476/22. In other embodiments, the rigid foamed
cementitious core prevents the passage of fire for at least 45
minutes using test method ASTM E2074-00 or at least about 60
minutes using test method BSI 476/22. In yet other embodiments, the
foamed cementitious can provide a sound transmission coefficient
rating of at least about 27 using test method ASTM E-413. The
foamed cementitious core can also have a compressive strength of at
least about 210 kPa.
[0018] Another aspect of the above-mentioned door includes a door
shell having a door frame having first and second rails and first
and second stiles. In those embodiments with an expanded metal mesh
web, the mesh can include apertures having a first dimension longer
than a second dimension. In certain embodiments, the first
dimension can be substantially parallel to the first and second
stiles. It should be understood that more than one web can be
disposed within the interior door cavity.
[0019] In another embodiment of the present invention, a door
comprising a door frame and at least one door skin being connected
in helping to define an interior door cavity, a mat within the
interior door cavity, and a rigid foamed cementitious core within
the interior door cavity is disclosed.
[0020] Another embodiment of the present invention is a method of
constructing a door. The method comprises providing a door shell
having a generally planar construction with marginal edges and
first and second door skins helping to define an interior door
cavity, disposing a mat within the interior door cavity, and
disposing a rigid foamed cementitious core within the interior door
cavity. In certain embodiments, the mat can include opening, for
example, a web. In some embodiments, the rigid foamed cementitious
core cooperates with the web. In certain embodiments, the web is
disposed within the interior door cavity prior to disposing the
rigid foamed cementitious core within the interior door cavity. The
web can be disposed offset toward one of the door skins or
substantially centered in the interior door cavity. The web can be
secured to at least one of the door skins or alternatively to the
marginal edges of the door shell.
[0021] In another embodiment, the method further comprises forming
a shelf into the marginal edges of the door shell. The forming step
can be comprised of removing a portion of the marginal edges such
that a first and second shelf surface is formed into the marginal
edges. In certain embodiments, the first shelf surface is
substantially parallel to the first and second door skins and the
second shelf surface is substantially perpendicular to the first
and second door skins. In certain embodiments, at least a portion
of the web can be secured to at least a portion of the first shelf
surface. The first shelf surface can be offset toward one of the
door skins or substantially centered between the first and second
door skins.
[0022] In yet another embodiment of the present invention, a door
is provided that comprises a door shell having generally planar
construction with marginal edges and first and second door skins
helping to define an interior door cavity, a polymeric shell
disposed on the interior surface of at least one of the door skins,
and a rigid foam core disposed within the interior door cavity. In
certain embodiments, the polymeric shell is the cured product of a
curable mixture. The curable mixture can include the following
components: a curable resin, a co-curable monomer and a fibrous
reinforcement material. The rigid foam core can be a rigid foamed
cementitious core and more particularly a foamed cement core.
Alternatively, the rigid foam core can be comprised of a rigid
foamed polyurethane core.
[0023] Yet another embodiment of the present invention includes a
door comprising a door shell having a generally planar construction
with marginal edges and first and second door skins helping to
define an interior door cavity, a web disposed within the interior
door cavity and offset towards one of the door skins, and a rigid
foamed polyurethane core disposed within the interior door cavity
and cooperating with the web. In certain embodiments, the mat can
include openings, for example, a web. The door shell can include a
door frame having first and second rails and first and second
stiles. The web can be comprised of expanded metal mesh that
includes apertures having a first dimension longer than a second
dimension. In one embodiment, the first dimension is substantially
parallel to the first and second stiles. The rigid foamed
polyurethane core can be comprised of the cured polyurethane foam
and in some cases, can have a density of at least about 2.0
lbs/ft.sup.3.
[0024] Another embodiment of the present invention includes a door
comprised of a door shell having a generally planar construction
with marginal edges and interior and exterior door skins helping to
define an interior door cavity, a web means for preventing access
to the interior door skin from the exterior door skin, and a rigid
foamed cementitious core extending between and connecting portions
of the interior and exterior door skins. The web means can be
disposed within the interior door cavity. In certain embodiments,
the rigid foamed cementitious core extends between and connects
substantial portions of the skins. The rigid foamed cementitious
core can be comprised of a rigid foamed cement core. The rigid
foamed cementitious core means can provide the following
attributes: the prevention of the passage of fire for at least
about 20 minutes using test method ASTM E2074-00 or at least about
30 minutes using test method BSI 476/22, sound transmission
coefficient rating of at least about 27 using test method ASTM
E-413, and/or a compressive strength of at least about 210 kPa. In
other embodiments, the rigid foamed cementitious core prevents the
passage of fire for at least 45 minutes using test method ASTM
E2074-00 or at least about 60 minutes using test method BSI
476/22.
[0025] These and other aspects and embodiments of the present
invention will become more apparent, clearly understood and
appreciated from a reading of the specification in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The features of the present invention which are believed to
be novel are set forth with particularity in the appended claims.
The present invention, both as to its organization and manner of
operation, together with further objects and advantages thereof,
may best be understood with reference to the following description,
taken in connection with the accompanying drawings:
[0027] FIG. 1A is a front elevational view of a security door
according to an embodiment of the present invention;
[0028] FIG. 1B depicts an exploded view of a portion of expanded
metal mesh in accordance with an embodiment of the present
invention;
[0029] FIG. 2 depicts an exploded perspective view of a web
connected to the interior stile surfaces of a security door
according to an embodiment of the present invention;
[0030] FIG. 3 depicts an exploded perspective view of a shelf
machined into the frame edge of a security door according to
another embodiment of the present invention;
[0031] FIG. 4 depicts an exploded perspective view of frame edges
suitable for the machining of a shelf;
[0032] FIG. 5 depicts a flowchart of a preferred method for mixing
ingredients to obtain a foamed cement slurry in accordance with an
embodiment of the present invention;
[0033] FIG. 6 illustrates an apparatus in accordance with an
embodiment of the present invention for filling interior door
cavities with foamed cement slurry and curing the foamed cement
slurry to produce a gas-entrained cementitious core;
[0034] FIG. 7 depicts a cross-section of a platen which includes a
tube for conveying a heat exchanging liquid in accordance with an
embodiment of the present invention; and
[0035] FIG. 8 depicts an overhead view of a schematic plant layout
to be used in a system for producing doors in accordance with an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] As required, detailed embodiments of the present invention
are disclosed herein. However, it is to be understood that the
disclosed embodiments are merely exemplary of the invention that
may be embodied in various and alternative forms. The figures are
not necessarily to scale, and some features may be exaggerated or
minimized to show details of particular components. Therefore,
specific structural and functional details disclosed herein are not
to be interpreted as limiting, but merely as a representative basis
for the claims and/or as a representative basis for teaching one
skilled in the art to variously employ the present invention.
[0037] Aspects of the present invention will now be described in
detail with reference being made to the accompanying drawings.
According to the embodiment illustrated in FIG. 1A, door 10 is a
hinged entry way door. It is understood that door 10 refers to, but
is not limited to, hinged patio doors, sliding patio doors, hinged
interior doors, impact-resistant doors suitable for meeting high
wind velocity building codes, and general commercial grade doors.
Door 10 can also be fitted with a translucent panel, i.e. a
doorlite assembly or side light assembly. For example, an opening
can be cut in door 10 to accept an inserted doorlite assembly.
Alternatively, door 10 can be fitted with a frame assembly for
accepting the translucent panel 12.
[0038] Door 10 can have many different sizes, shapes, and uses. In
certain embodiments, door 10 can have a thickness of between about
0.5 inches and about 3 inches. In other embodiments, door 10 can
have a thickness of between about 1.25 inches and about 1.85
inches. In certain embodiments, door 10 can have a height of
between about 48 inches and about 96 inches. In other embodiments,
door 10 can have a height of between about 74 inches and about 96
inches. In certain embodiments, door 10 can have a width of between
about 8 inches and about 48 inches. In other embodiments, door 10
can have a width of between about 10 inches and about 44 inches. In
yet other embodiments, door 10 can have a width of between about 30
inches and about 42 inches.
[0039] As shown in FIG. 1A, door shell 14 includes first door skin
16, second door skin 18 and door frame 20. It should be understood
that one door skin can be an exterior door skin and the other door
skin can be an interior door skin based on how the door is hinged
to the entry way. In the illustrated embodiment, the exterior door
skin typically faces an outside environment and the interior door
skin faces an inside environment (i.e. the inside of a house
containing the entry way for hinging the door). Door shell 14 helps
to define interior door cavity 22. Door shell 14 can be comprised
of a blow-molded material, for example, a pre-pigmented plastic, a
thermoformed material or a twin-sheet thermoformed material. The
door skins include an exterior side and an interior side. The
interior sides face interior door cavity 22 and the exterior sides
face away from interior door cavity 22. Suitable materials for the
door skins include reinforced or unreinforced matrix materials of
thermoset (i.e. thermoset materials), steel, aluminum,
thermoplastic, ceramic, wood or combinations thereof, preferably
thermoset materials, and most preferably fiberglass reinforced
thermoset materials. In certain embodiments, the door frame is
constructed with materials that are machinable with common building
tools.
[0040] Door frame 20 includes a first stile 24 and a second stile
26. Stiles 24 and 26 are parallel to one another. Stiles 24 and 26
are positioned in a perpendicular relationship to first rail 28 and
second rail 30. Second rail 30 is parallel to and spaced apart from
first rail 28. First rail 28 and second rail 30 extend between and
connect to stiles 24 and 26. Stiles 24 and 26 and rails 28 and 30
can be constructed of laminated or unlaminated wood. Stiles 24 and
26 can also be a hollow channel of pultruded or extruded reinforced
plastic, a metal hollow channel, a partially or totally metal
reinforced channel made of a material other than metal, or a
compressed mineral stile. According to FIG. 1A, door frame 20 has a
rectangular geometric configuration. However, it is understood that
door frame 20 can be arranged in a variety of geometric
configurations depending upon the desired application. For example,
door frame can have a radiused or arched top typical of "mission
style" architecture.
[0041] First hinge insert 32, second hinge insert 34 and lock
insert 36 can be inserted into the door shell 14. Hinge inserts 32
and 34 can be fastened to second stile 26, adhered to either or
both first door skin 16 or second door skin 20, or inserted into
pre-defined spaces in either or both first door skin 16 or second
door skin 18. Lock insert 36 can be fastened to first stile 24,
adhered to either or both first door skin 16 or second door skin
18, or inserted into pre-defined spaces in both or either door
skins 16 and/or 18. First hinge plate 38 and second hinge plate 40
can be secured to first hinge insert 32 and second hinge insert 34
by using a screw, nail, or similar fastener. Lock apparatus 42 can
be secured to lock insert 38 by using a screw, nail or similar
fastener.
[0042] Referring to FIG. 1A, web 44 can be disposed within interior
door cavity 22. In certain embodiments, the material used for web
44 provides impact resistance and can prevent access to the
interior door skin from the exterior side of the door skin by
using, for example, sharp cutting tools. Portions of web 44 can be
removed so that web 44 does not interfere with hinge inserts 32 and
34 and lock insert 36. Also, it should be understood that a
plurality of layers of webs can be used for impact and intrusion
resistance requirements.
[0043] Examples of web materials that provide impact resistance
include, but are not limited to, plastic web materials, such as
rubber-based plastics, soft durometer plastics, and polyolefin web
materials. An example of a suitable soft durometer plastic can be a
vinyl rubber mat. In certain embodiments, vinyl rubber mat sheets
with a thickness of about 0.25 inches can be used. Suitable
polyolefin web materials include those typically used as snow
fences and/or construction barriers. In certain embodiments, these
types of webs with a thickness of about 0.1 inches are used. It
should be understood that web materials suitable for impact
resistance need not be primarily planar sheets and can have
significant thickness (in the range of about 0.01 inches to about
0.75 inches), for example dimensional monofilament materials such
as COLORBOND available from BHP Steel of Australia.
[0044] Examples of web materials that are suitable for use and that
also provide impact resistance and prevention of access to the
interior door skin from the exterior door skin using, for example,
sharp cutting tools include, but are not limited to, metal screen,
polymer woven screen, expanded metal mesh, and wire form.
[0045] In other embodiments, a mat can be disposed within interior
door cavity 22 and is generally rectangular in shape. It should be
understood that a mat may or may not have openings. Examples of
materials for mats, can include, but are not limited to, a plastic
chamber with inflating gas, a ballistic resistant material, gypsum
core, a solid metal mat, and a solid polymeric sheet. In certain
embodiments, the mat can allow the foamed cement slurry to be
poured on both sides of the mat.
[0046] FIG. 1B illustrates an exploded portion of expanded metal
mesh in accordance with an embodiment of the present invention. The
expanded metal mesh is preferably comprised of a network of
apertures 46, i.e. openings, having a first dimension 48 and a
second dimension 50. In certain embodiments, the ratio of the first
dimension to the second dimension, otherwise referred to as the
aspect ratio, can be greater than about 1.1. In other embodiments,
the first dimension can be about 0.2 inches to about 1.5 inches and
the second dimension can be about 0.18 inches to about 1.35 inches.
However, it should be understood that the first and second
dimensions can be greater than about 1.5 inches and about 1.35
inches, respectively, provided that the apertures are small enough
to not allow penetration by a hand of an intruder and/or an
impacting object through the expanded metal mesh. It should also be
understood that the first and second dimensions can be less than
about 0.2 inches and about 0.18 inches, respectively, provided that
the apertures are large enough to allow a rigid foam to pass
through the expanded metal mesh during pouring (this step is
described in greater detail below).
[0047] In certain embodiments, the thickness of the expanded metal
mesh can be about 0.3 inches to about 2.0 inches. In other
embodiments, the thickness can be 0.04 inches. Suitable thicknesses
can provide a relatively inexpensive web material while providing
the advantages of impact resistance and entry prevention. In
certain embodiments, web 44 is comprised of expanded metal mesh
which can be disposed within interior door cavity 22 for maximum
tensile strength by orienting the expanded metal mesh so that the
first dimension is parallel to rails 28 and 30.
[0048] FIG. 2 depicts an embodiment for disposing web 44 within
interior door cavity 22. The lengthwise edges of web 44 can be bent
to form first bent portion 52 and second bent portion 54. Bent
portions 52 and 54 can have a uniform width of about 0.5 inches and
about 1.0 inches. In certain embodiments, bent portions 52 and 54
can be substantially perpendicular to the adjoining flat portion 56
of web 44 and bent in the same direction so that they face each
other. Bent portions 52 and 54 can be secured to at least a portion
of first stile surface 58 and second stile In certain embodiments,
flat portion 56 is closer to the exterior door skin than the
interior door skin so that the added layer of protection (i.e. web
44) is closer to the exterior door skin which is vulnerable to
attack.
[0049] FIGS. 3 and 4 depict another embodiment for disposing web 44
within interior door cavity 22. In the depicted embodiment, shelf
62 is machined, or otherwise formed, into all four sides of the
frame edge. However, it should also be understood that shelf 62 may
be machined into a portion the frame edge contained on stiles 24 or
26 or contained on rails 28 and 30. According to FIGS. 3 and 4,
shelf 62 is machined into first frame edge 64 which is adjacent to
first door skin 16 upon assembly of door 10. It should be
understood that shelf 62 can also be machined into second frame
edge 66 which is adjacent to second door skin 18 upon assembly of
door 10.
[0050] Shelf 62 is comprised of first shelf surface 68 and second
shelf surface 70. In certain embodiments, first shelf surface 68 is
substantially parallel to door skins 16 and 18 and second shelf
surface 70 is substantially perpendicular to door skins 16 and 18.
In certain embodiments, the width of first shelf surface 68 can be
at most about half the width of stiles 24 and 26. In certain
embodiments, the width of second shelf surface 70 can be in the
range of about the thickness of web 44 and about half the thickness
of door 10.
[0051] In certain embodiments, the width of second shelf surface 70
is about the thickness of web 44 and shelf 62 is machined into the
frame edge which is adjacent to the exterior door skin upon
assembly. In certain embodiments, the door assembly provides the
added layer of protection, i.e. web 44, adjacent to the exterior
door skin which is vulnerable to attack.
[0052] In certain embodiments, the length and width of web 44 is
greater than the length and width of interior door cavity such that
the edges of web 44 lay flat upon first shelf surface 64 and can be
secured to first shelf surface 68 with staples, brads, nails,
screws or other fasteners.
[0053] According to another method of disposing web 44 within the
interior door cavity 22, web 44 can be placed within interior door
cavity 22 without being secured to door frame 20. According to this
embodiment, web 44 is secured within interior door cavity 22
through the foaming process, described in more detail below.
[0054] In certain embodiments, door skins 16 and 18 are secured to
door frame 20 after web 44 is secured to door frame 20. In these
embodiments as well as others, door skins 16 and 18 are secured to
door frame 20 with an adhesive. Suitable adhesives include, but are
not limited to, latex acrylic, hot melt urethane, epoxy, pressure
sensitive adhesives, and radiation cured adhesives. It is
understood that door skins 16 and 18 can include interlocking edges
that function to secure door skins 16 and 18 to door frame 20.
Alternatively, an interlocking skin can be used instead of first
door skin 16 and second door skin 18. The interlocking door skin
fits over the door frame 18 and the edges of the interlocking door
skin mate together, for example, with snap-fits.
[0055] In certain embodiments of the present invention, a rigid
foam core disposed within the interior door cavity is then
provided, as described in greater detail below. In certain
embodiments, the rigid foam core prevents the passage of fire for
at least about 20 minutes using test method ASTM or at least about
30 minutes using test method BSI 476/22. In other embodiments, the
rigid foamed cementitious core prevents the passage of fire for at
least 45 minutes using test method ASTM E2074-00 or at least about
60 minutes using test method BSI 476/22. In certain embodiments,
the rigid foam core provides a sound transmission coefficient
rating of at least about 27 using test method ASTM E-413. In
certain embodiments, the rigid foam core can have a compressive
strength of at least about 210 kPa (about 30 lbf/in.sup.2).
Examples of foams that provide rigid foam cores with the fire and
sound ratings disclosed above include polyurethane foams having a
minimum density of at least about 2.0 lb/ft.sup.3 and those formed
from gas-entrained cementitious materials. In certain embodiments,
the gas-entrained cementitious material can be a controlled low
strength cementitious material, or more specifically an
air-modified controlled low strength cementitious material, or most
specifically a foamed cement slurry.
[0056] Gas-entrained cementitious materials refer to inorganic
materials or mixtures of inorganic materials which sets and
develops strength by a chemical reaction with water by formation of
hydrates, and which entrains more than about 5 volume % gas,
preferably between about 10 and about 80 volume %, more preferably
between about 30 and about 60 volume %, and most preferably between
about 40 and about 55 volume %. It is understood that the gas can
come from a variety of sources including, but not limited to direct
gas injection, microspheres containing gases, porous particles
containing gases, and in-situ chemical reactions or changes in the
state of matter. It is further understood that materials entrained
may not always be in the gaseous phase, particularly when
environmental temperatures to which the article is exposed change
significantly. It is further understood that the gases may migrate
through time and be replaced by other gases or liquids.
[0057] Controlled low strength cementitious material (CLSM), a
subset of gas-entrained cementitious materials, refers to a generic
term for flowable cementitious materials having a self-compacting
property and a compressive strength of less than about 1,200
lbf/in.sup.2 (8.27 Mpa) and an unconfined ultimate compressive
strength of between about 30 lbf/in.sup.2 and about 500
lbf/in.sup.2. In other embodiments, an unconfined compressive
strength of between about 50 lbf/in.sup.2 and about 250
lbf/in.sup.2. CLSMs are also commonly referred to as flowable fill,
flow fill, or controlled density fill.
[0058] Air-modified controlled low strength cementitious materials
can be referred to as a CLSM which has entrained in it more than 5
volume % air. In certain embodiments, the entrainment can be
between about 10 to about 80 volume % air. In other embodiments,
the entrainment can be between about 30 to about 60 volume % air.
In yet other embodiments, the entrainment can be about 40 to about
55 volume % air.
[0059] Foamed cement slurries can refer to a type of air-modified
controlled low strength cementitious material in which the
cementitious material is any type of hydraulic cement, and in some
embodiments Portland cement, in which air or other gases are
entrained at more than about 5 volume % air or other gas. In
certain embodiments, the entrainment can be between about 10 to
about 80 volume % air or other gas. In other embodiments, the
entrainment can be between about 30 to about 60 volume % air or
other gas. In yet other embodiments, the entrainment can be between
about 40 to about 55 volume % air or other gas. Portland cement can
be defined in ASTM C-150 and is a variety of blended hydraulic
cement as defined in ASTM C-595.
[0060] In certain embodiments, foamed cement slurries can be
utilized to produce gas-entrained cementitious cores by
transferring the foamed cement slurry into the interior door cavity
22 and curing the slurries. It should be understood that the curing
occurs through a hydration, otherwise referred to as a water-based
reaction. The foamed cement slurry can be prepared by mixing a
combination of ingredients. FIG. 5 depicts a flowchart of a method
for mixing ingredients to obtain a foamed cement slurry in
accordance with the present invention. According to FIG. 5, cement
72 and water 74 are mixed in a high speed mixer 76 to produce
cement slurry 78. As depicted in block 80, a brewing step is
utilized to produce foaming solution 82. Typically, the brewing
step includes mixing air and water with a foaming agent to produce
a foaming solution with entrained air. In one embodiment, cement
slurry 78, foaming solution 82, and expanded polystyrene (EPS)
beads 84 are introduced into gentle mixer 86 and mixed to produce
foamed cement slurry 88. Optionally, fiber spools 90 can be fed
into chopper 92 to produce reinforcement fibers 96, which can be
introduced into gentle mixer 86 along with the other ingredients.
Once mixed, the foamed cement slurry can be transferred into
interior door cavity 22.
[0061] In certain embodiments, the water to cement ratio in the
foamed cement slurry is greater than about 38 parts water to about
100 parts cement by weight in order to provide strength to the
resulting door member. Optional additives, such as water reducers,
setting accelerators, superplasticizers, reinforcement fibers, and
expanded polystyrene beads, can be added to the foamed cement
slurry to enhance properties, such as flow rate, curing rate,
weight, or rigidity. It should be understood that reinforcing
fibers refer to a fiber or a bundle of fibers having an aspect
ratio greater than about 4, which results in one or more increased
mechanical properties when present.
[0062] Water reducers, in general, improve the workability of
cement slurries and reduce the amount of mixing water for a given
workability. Typically this is about 5-15% reduction in water
usage. Water reducers can be frequently drawn from the groups
consisting of condensed naphthalene sulfonic acids, salts of
lignosulfonic acids, salts of hydroxycarboxylic acids,
carbohydrates and blends thereof. Superplasticizers, also known as
superfluidizers, super water reducers, and high range water
reducers, are a class of water reducers capable of reducing the
water usage by at least about 30%. While not being bound to any one
theory, it is believed that superplasticizers break down the large
irregular agglomerates of cement particles by virtue of
deflocculation due to adsorption and electrostatic repulsion, as
well as some steric effects. Superplasticizers are typically drawn
from a group consisting of sulfonated melamine-formaldehyde
condensates, sulfonated naphthalene-formaldehyde condensates,
modified lignosulfonates, sulfonic acid esters, polyacrylates,
polystyrene sulfonates, and blends thereof.
[0063] Many cements that are suitable for use in the present
invention contain additives. These additives can include
cementitious and pozzolanic additives. Cementitious additives refer
to an inorganic material or mixture of inorganic materials which
forms or assists to form cementitious materials which develops
strength by chemical reaction with water by formation of hydrates.
Cementitious additives are generally rich in silica and alumina.
According to ASTM C-539-94, pozzolanic additives refer to siliceous
or alumino-siliceous material which in itself possesses little or
no cementitious value, but which when in finely divided form and in
the presence of moisture will chemically react with alkali and
alkaline earth hydroxides at ordinary temperatures to form or
assist in forming compounds possessing cementitious properties.
Examples of pozzolanic additives can include Class C fly ash from
burning lignite coal, Class F fly ash from burning bituminous coal,
pulverized-fuel fly ash, condensed silica fume, metakaolin, rubber
ash, and glass cullet. Additives found in cement are particularly
useful in increasing the mass of the resulting door member.
[0064] Insulating gases can replace entrained air to provide
greater insulation. These gases include molecules that generally
have a higher atomic mass than air. Possible examples include
halocarbons and hydrohalocarbons, such as HCFC-22, HFC-134a,
HFC-245fa, HFC-365mfc; noble gases, such as argon, xenon, and
krypton; sulfur hexafluoride; hydrocarbons, such as pentane; and
mixtures thereof.
[0065] FIG. 6 depicts an apparatus in accordance with an embodiment
of the present invention for filling interior door cavities with
foamed cement slurry and curing the foamed cement slurry to produce
a gas-entrained cementitious core. In the depicted embodiment, the
filling structure is comprised of door shell bank 98, filling
station 100, and heat exchanger system 102.
[0066] Door shell bank 98 is comprised of sled 104 having first and
second sled panels 106 and 108. In certain embodiments, sled panels
106 and 108 can be generally rectangular in shape and constructed
from plywood. The longer edges of generally rectangular sled panels
106 and 108 can be fitted with a first and second plurality of
castors 110 and 112, respectively, for facilitating movement of
sled 104 around an assembly floor.
[0067] In the depicted embodiment, door shell bank 98 is also
comprised of first and second reinforcement shell ends 114 and 116,
first and second platen shell 118 and 120, a plurality of door
shells 122, and at least one platen center shell 124, which are
loaded onto sled 104 in preparation for filling the plurality of
door shells 122 with the foamed cement slurry. In alternative
embodiments, reinforcement can be provided by a plurality of metal
reinforcement sheets of substantial thickness (between about 0.5
inches to about 2.0 inches) placed between the door shell or by the
door frame itself if made out of fabricated metal, for example, in
the case of metal fire doors. In yet other embodiments, the
reinforcement can be provided by a plurality of spaced apart and
reinforced open mouth cavities such that each reinforced cavity is
suitable for housing at least one article shell. In certain
embodiments, the loading process is comprised of orienting sled 104
such that second sled panel 108 is substantially parallel to the
assembly floor, sliding items 114 through 124 onto second sled
panel 108 in an order, and then tipping sled 104 about ninety
degrees so that first sled panel 106 is substantially parallel to
the assembly floor. In certain embodiments, the order from one end
to the other end of sled 104 can be the following: first
reinforcement shell end 114, first platen shell 118, door shell
120, platen center shell 124, door shell 120, second platen shell
122, and second reinforcement shell end 116. It is fully
contemplated that greater than two door shells can be loaded onto
sled 104 as long as additional platen center shells 124 are loaded
in between the door shells. In certain embodiments, 10-15 door
shells with 11-16 platen center shells 124 are loaded onto sled
104. However, it should be understood that this is merely exemplary
of the amount doors that can be paired in tandem with platen center
shells. Other amounts can be used based on the amount of time
necessary to set the foamed cement slurry. First rail of each door
shell 120 faces upward from an assembly floor and second rail of
each door shell 120 preferably sits flush against first sled panel
106 after sled 104 can be tipped about ninety degrees.
[0068] In certain embodiments, reinforcement shell ends 114 and 116
are generally rectangular in shape with a height and length similar
to door shell 122 and can be comprised of a metal alloy sheet of
substantially uniform thickness which is fabricated into a
one-piece, hollow rectangular box with strength sufficient to
resist buckling under vacuum conditions. Suitable pure metal or
metal alloys for this purpose, include, but are not limited to,
aluminum, stainless steel, carbon steel, cast iron, and alloys
thereof. In certain embodiments, the width of reinforcement shell
ends 114 and 116 can be in the range of about 0.05 inches to about
4.0 inches. In other embodiments, the width can be in the range of
about 0.625 inches to about 1.0 inches. In certain embodiments, the
width can be in the range of about 0.625 inches to about 0.75
inches.
[0069] In certain embodiments, platen shells 118, 120, and 124 can
be generally rectangular, with a height and length similar to door
shell 122. Such platens can be comprised of a metal sheet of
substantially uniform thickness which is fabricated into a
one-piece, hollow rectangular box with strength sufficient to
resist bucking under vacuum conditions. Suitable pure metal or
metal alloys for this purpose, include, but are not limited to,
aluminum, stainless steel, carbon steel, cast iron, and alloys
thereof. In certain embodiments, the width of reinforcement shell
ends 114 and 116 can be in the range of about 0.05 inches to about
4.0 inches. In other embodiments, the width can be in the range of
about 0.625 inches to about 1.0 inches. In certain embodiments, the
width can be in the range of about 0.625 inches to about 0.75
inches.
[0070] In certain embodiments, platen shells 118, 120, and 124 can
provide heat to the foamed cement slurry encased in the surrounding
door shells in order to decrease the green-strength curing time, as
described in greater detail below. The heat decreases the time
necessary for the cement in the foamed cement slurry to form a
structurally stable cell wall around entrained gas and/or air
bubbles. In certain embodiments, the interior cavity of platens
118, 120, and 124 house a tube generally following a serpentine
path for conveying a heat exchanging liquid. It is fully understood
that the other path configurations can be used as long as they can
be used to deliver heat to a substantial portion of the platen
surface.
[0071] For example, FIG. 7 depicts a cross-section of platen 118
about plane 7-7 which includes tube 126 for conveying a heat
exchanging liquid. In the depicted embodiment, tube 126 enters the
interior shell cavity of platen shell 118 through opening 128,
extends through a generally serpentine path and exits through
opening 130. In certain embodiments, the heat exchanging liquid can
be introduced into a heater for heating the liquid to a temperature
in the range of about 1.degree. C. to about 70.degree. C. above
ambient, more particularly about 10.degree. C. to about 40.degree.
C., and most particularly about 20.degree. C. to about 35.degree.
C. In certain embodiments, the heat exchanging liquid can enter the
interior cavity of the platen in tube 126 through opening 128. As
the heat exchanging liquid flows through tube 126 towards opening
130, it loses heat to the relatively cooler adjacent liquid cement
slurry. This heat exchange aids in decreasing the green strength
curing time. The cooled heat exchanging liquid exits the interior
door cavity in tube 126 through opening 130 which feeds into a
return line. Preferably, the heat exchanging liquid is circulated
for further use. Examples of suitable heat exchanging liquids
include, but are not limited to, water, oil, or THERMOL. In certain
embodiments, the return line is connected to the heater through a
recirculating line for recycling the heat exchanging liquid to
provide energy savings.
[0072] According to the embodiment as shown in FIG. 6, filling
station 132 is comprised of filling nozzle 134, vacuum lines 136,
and platform 138. Nozzle 134 can deliver foamed cement slurry into
interior door cavity 22. The foamed cement slurry can be
transferred into interior door cavity incrementally, using between
one and five increments. In certain embodiments, one to three
increments can be used. In other embodiments, one increment can be
used. In certain embodiments, nozzle 134 can be part of a gravity
feed system for transferring foamed cement slurry from gentle mixer
86 into interior door cavity 22. In these embodiments, the contents
of gentle mixer 86 can be poured under the force of gravity into a
hopper. The hopper can be mechanically positioned over interior
door cavity 22 and foamed cement slurry flow via a pump from the
hopper through nozzle 134 into interior door cavity 22. This system
can reduce costs by limiting the destruction of bubbles passing
through the compressive phase of the pump. In certain embodiments,
platform 138 is positioned over loaded door steel bank 98 and is in
the vicinity of filling nozzle 134 such that an operator can move
the filling nozzle between door shells. In certain embodiments, at
least one vacuum line 136 can be attached to a shell edge of at
least one platen shell 118 for providing suction between the door
skin and a reinforcement shell surface so that the door shell
retains its pre-curing shape during curing.
[0073] FIG. 8 depicts an overhead view of a schematic plant layout
to be used in a system for producing doors in accordance with an
embodiment of the present invention. In the depicted embodiment,
the system can include a plurality of door shell banks 140 which
are positioned below at least one platform 142 having a vacuum and
slurry source for supplying a vacuum to reinforcement shells of
door shell banks 140 and delivering the gas-cementitious material
to the interior cavity of door shells, respectively. In certain
embodiments, the filled doors can be moved on door shell banks 140
to a curing area 144, which can be a curing room, in order to
green-strength cure the filled door shells. After curing, the doors
can proceed to trim line 146 and pallets 148.
[0074] In certain embodiments, an adhesive can be applied to the
interior surface of each door skin of each door before being loaded
onto sled 104. The adhesive helps to adhere the foamed cement
slurry to the interior surfaces during the curing process. Examples
of suitable adhesives include, but are not limited to, latex
adhesive, epoxy, hot melt urethane, radiation cured adhesives, and
mixtures thereof. The adhesive can reduce the time necessary to
achieve green-strength, i.e. when the door can be removed from the
fixture without damage, for example, inducing cracking, and
increases the strength of the door upon final setting. It should be
understood that in certain embodiments the foamed cement slurry can
reach this green-strength after at least partially curing the
foamed cement slurry and without the use of an adhesive.
[0075] According to another embodiment of the present invention, a
curable mixture is applied to the interior surface of at least one
door skin and the interior surface of the door frame. The curable
mixture cures to form a polymeric shell which can increase the
security rating and/or the strength of the door. In certain
embodiments, the curable mixture can be a viscous liquid when
applied and dries upon curing to form a curable shell. The curable
mixture can be applied to form the polymeric shell in a range of at
least about 0.5 inches when dry to the full width of the interior
door frame and within about 2.0 inches of the interior door frame
corners to the full length of the interior door frame.
[0076] In certain embodiments, the curable mixture can be comprised
of a curable resin, a co-curable monomer, a filler material, and a
fibrous reinforcement material. Sufficient filler material can be
added to prevent shrinkage of the curable shell. The amount of
filler material necessary varies according to the amount of curable
resin used in the curable mixture. In certain embodiments, the
filler material can comprise between about 30% to about 80% by
weight of the curable mixture. Unless otherwise stated, all
percentages disclosed are by weight based on the total weight of
the curable mixture. In other embodiments, about 50% to about 75%
filler material can be used. In yet other embodiments, about 60% to
about 74% filler material can be used. The fibrous reinforcement
material can be selected from chopped fiberglass, woven fiberglass
mat, nonwoven fiberglass mat, needled fiberglass mat, aramid fiber
mat, carbon fiber mat, nylon screen, rubber-coated textiles,
plastic laminated fibers, and combinations thereof. In certain
embodiments, the fibrous reinforcement material can comprise about
10% to about 40% of the curable mixture. In other embodiments, the
fibrous reinforcement material can comprise about 15% to about 35%
of the curable mixture. In yet other embodiments, the fibrous
reinforcement material can comprise about 17% to about 30% of the
curable mixture.
[0077] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *