U.S. patent application number 10/972657 was filed with the patent office on 2006-05-11 for fire door core assembly.
This patent application is currently assigned to Industries 3F, Inc.. Invention is credited to Andre Fortin.
Application Number | 20060096240 10/972657 |
Document ID | / |
Family ID | 36314897 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060096240 |
Kind Code |
A1 |
Fortin; Andre |
May 11, 2006 |
Fire door core assembly
Abstract
A laminated fire door including a core, containing panels or
boards made from an organic material including flax, and a fibrous
binder constituting a sodium silicate adhesive, is used to make a
door exhibits at least a 45 minute fire rating. In accordance with
a preferred form of the invention, the fire door core is formed by
using a silicate adhesive, preferably sodium silicate, in the order
of 25 mils (0.6 mm) to laminate together two flax boards, each
having a thickness in the range of 0.625-0.875 inches
(approximately 16-22 mm), with each of the laminated flax boards
having a density of between 20 and 45 pounds per cubic foot
(320-700 kgs/m.sup.3).
Inventors: |
Fortin; Andre; (Lennoxville,
CA) |
Correspondence
Address: |
DIEDERIKS & WHITELAW, PLC
12471 Dillingham Square, #301
Woodbridge
VA
22192
US
|
Assignee: |
Industries 3F, Inc.
|
Family ID: |
36314897 |
Appl. No.: |
10/972657 |
Filed: |
October 26, 2004 |
Current U.S.
Class: |
52/784.11 |
Current CPC
Class: |
B32B 2260/023 20130101;
B32B 2262/065 20130101; B32B 2607/00 20130101; B32B 9/02 20130101;
B32B 37/12 20130101; E06B 5/16 20130101; B32B 7/12 20130101; B32B
2419/00 20130101; B32B 2307/3065 20130101; B32B 2260/046 20130101;
B32B 5/26 20130101 |
Class at
Publication: |
052/784.11 |
International
Class: |
E04C 2/54 20060101
E04C002/54 |
Claims
1. A fire door comprising: an outer peripheral frame; and a two
panel laminate core including: a first panel formed from an organic
material including first and second opposing planar surfaces, said
organic material including flax; a second panel formed from an
organic material including first and second opposing planar
surfaces, said organic material including flax; and a fibrous
binder layer arranged between the first planar surface of the first
panel and the first planar surface of the second panel, said binder
layer including a silicate adhesive, wherein the first and second
panels are pressed together with the binder layer sandwiched
therebetween to form the two panel laminate core, said two panel
laminate core being arranged within the outer peripheral frame to
form a door having a fire rating of at least 45 minutes.
2. The fire door according to claim 1, wherein each of the first
and second panels has a thickness in the order of 0.625-0.875
inches (approximately 16-22 mm).
3. The fire door according to claim 1, wherein the flax in the
first and second panels has a density between 20 and 45 pounds per
cubic foot (320-700 kgs/m.sup.3).
4. The fire door according to claim 1, wherein the fibrous binder
layer is approximately 25 mils (approximately 0.6 mm) thick.
5. The fire door according to claim 1, wherein the silicate
adhesive constitutes sodium silicate.
6. The fire door according to claim 5, wherein the sodium silicate
further contains components selected from the group consisting of:
talc, aluminum silicate of potash and soda, magnesium silicate,
cellulose and/or inert fillers, kaolin clay, mica, perlite and/or
cristaline silica.
7. A two panel laminate core for a fire resistant door having a
fire rating of at least 45 minutes including: a first panel formed
from an organic material including first and second opposing planar
surfaces, said organic material including flax; a second panel
formed from an organic material including first and second opposing
planar surfaces, said organic material including flax; and a
fibrous binder layer arranged between the first planar surface of
the first panel and the first planar surface of the second panel,
said binder layer including a silicate adhesive, wherein the first
and second panels are pressed together with the binder layer
sandwiched therebetween to form the two panel laminate core, said
two panel laminate core being arranged within the outer peripheral
frame to form a door having a fire rating of at least 45
minutes.
8. The core according to claim 7, wherein each of the first and
second panels has a thickness in the order of 0.625-0.875 inches
(approximately 16-22 mm).
9. The core according to claim 7, wherein the flax in the first and
second panels has a density between 20 and 45 pounds per cubic foot
(320-700 kgs/m.sup.3).
10. The core according to claim 7, wherein the fibrous binder layer
is approximately 25 mils (approximately 0.6 mm) thick.
11. The core according to claim 7, wherein the silicate adhesive
constitutes sodium silicate.
12. The core according to claim 11, wherein the sodium silicate
further contains components selected from the group consisting of:
talc, aluminum silicate of potash and soda, magnesium silicate,
cellulose and/or inert fillers, kaolin clay, mica, perlite and/or
cristaline silica.
13. A method of forming a two panel fire resistant door core rated
for at least 45 minutes comprising: forming a first panel formed
from an organic material containing flax; forming a second panel
formed from an organic material containing flax; coating one side
of at least one of the first and second panels with a silicate
adhesive to form a binder layer; and joining the first and second
panels with the binder layer being sandwiched between the first and
second panels.
14. The method of claim 13, wherein joining the first and second
panels constitutes cold pressing the first and second panels
together to a desired thickness for the laminate core.
15. The method of claim 13, further comprising: mounting the core
in an outer peripheral frame; and applying outer sheathing panels
to opposite sides of the core to form a door having a fire rating
of at least 45 minutes.
16. The method of claim 13, wherein the binder layer is rolled onto
each of the first and second panels.
17. The method of claim 13, wherein each of the first and second
panels is provided with a thickness in the order of 0.625-0.875
inches (approximately 16-22 mm).
18. The method of claim 13, wherein the binder layer is formed
approximately 25 mils (approximately 0.6 mm) thick.
19. The method of claim 13, wherein the silicate adhesive
constitutes sodium silicate.
20. The method of claim 19, further comprising: employing sodium
silicate which contains components selected from the group
consisting of: talc, aluminum silicate of potash and soda,
magnesium silicate, cellulose and/or inert fillers, kaolin clay,
mica, perlite and/or cristaline silica.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention pertains to the art of doors and, more
particularly, to the construction of a door having a fire resistant
core.
[0003] 2. Discussion of the Prior Art
[0004] Doors for commercial, and even domestic, applications are
often rated for fire resistance. More specifically, fire doors are
rated based on their ability to resist burning in the case of a
fire, with standard ratings being defined as 20, 45, 60 and 90
minutes depending on the length of time a door can withstand a
rating temperature, typically in the range of 1700+.degree. F. The
higher the minute rating, the better the fire rating. For instance,
low rated fire doors are typically made from an organic material,
while high rated fire doors are generally made from mineral or
metal materials. More specifically, a 20 minute door typically
includes a particle or stave board core. For 45, 60 and 90 minute
ratings, a wood door generally has a mineral core.
[0005] In general, the higher rated fire doors have more costly
constructions. It is known in the door industry that a particle
board or wood fiber board can achieved a 20 minutes fire rating,
but cannot withstand the hose stream test in a 45 minutes fire
test. It is also more difficult or impossible when two layers of
fiberboard are laminated together with PVA adhesive. In a typical
45 minutes fire test, the first layer will fall in the furnace
after 15 to 20 minutes and the burning will progress fast
thereafter leaving little structure to hold the brutal effect of
the hose stream test.
[0006] Fire rated door cores for 45-60-90 minute ratings are
generally made of inorganic materials such as gypsum, perlite,
vermiculite and calcium silicate. The process manufacturing is
usually by casting. These panels have disadvantages of not being
able to provide good mechanical strength specially for screws or
nails and they are very dusty for any cutting or boring. They are
also very fragile and do not provide always good lamination for the
door skins. Of course, these materials are more expensive than wood
or wood-based products.
[0007] As indicated above, a fire rating of at least 45 minutes is
usually achieved with inorganic door cores, rather than with a core
made of solid wood, wood particle board or wood fiber board. It has
also been more difficult to obtain such results with lamination of
two layers of particle board or wood fiber board because of
delamination of one layer during the fire test. Also, a high level
of distortion or cupping is occurring on a large door, specially
when the density of the core is exceeding 40 lbs.
[0008] Based on the above, it would be a substantial advantage to
provide a cost efficient 45 minutes fire door that would offer good
screw holding power on the entire core for hardware or other
fastening devices and an effective surface for high strength
lamination of door skins, while also being light, stable, sound
reducing and ecological.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to producing a laminated
fire door including a core containing panels or boards made from an
organic material and a fibrous binder or adhesive, wherein the door
exhibits at least a 45 minute fire rating. More specifically, a
fire door constructed in accordance with the invention includes a
core having multiple panels made from an organic material
containing flax, having sandwiched therebetween a relatively thick
layer of a fibrous binder, preferably a sodium silicate adhesive.
In accordance with a preferred form of the invention, the fire door
core is formed by using a silicate adhesive, preferably sodium
silicate, in the order of 25 mils (0.6 mm) to laminate together two
flax boards, each having a thickness in the range of 0.625-0.875
inches (approximately 16-22 mm). In accordance with the most
preferred form of the invention, each of the laminated flax boards
has a density of between 20 and 45 pounds per cubic foot (320-700
kgs/m.sup.3). The laminated flax board panels can then be trimmed
to be used as a core in making a specified sized door. With the
exposed organic surfaces, outer door skins can be readily and
effectively laminated to the core.
[0010] With this construction, a fire door can be readily
manufactured with a fire rating level of at least 45 minutes out of
laminated organic panels containing flax which establish
advantageous adhesion qualities for door skins. Additional objects,
features and advantages of the present invention will become more
readily apparent from the following detailed description of a
preferred embodiment when taken in conjunction with the drawings
wherein like reference numerals refer to corresponding parts in the
several views.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a partial sectional view of a portion of a fire
door constructed in accordance with the present invention; and
[0012] FIG. 2 is a perspective view of a system for producing a
fire door core shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] With initial reference to FIG. 1, a fire door constructed in
accordance with the present invention is generally indicated at 2.
As shown, door 2 includes an outer peripheral frame 5, constituted
by interconnected rails, an upper one of which is shown at 7, and
stiles, one of which is shown at 8; a core 11; an inner door skin
14; and an outer door skin 15. In general, the above construction
of door 2, with the exception of the particulars of core 11, is
known in the art. Therefore, these aspects of door 2 will not be
discussed further here in detail.
[0014] The present invention is particularly directed to the
construction and method of forming core 11. In general, core 11
constitutes a laminate including a first panel 20, a second panel
21 and an intermediate fibrous binder layer 23. In accordance with
the most preferred form of the invention, each of first and second
panels 20 and 21 is formed from an organic material, specifically
flax. On the other hand, intermediate binder layer 23 is preferably
constituted by a sodium silicate adhesive.
[0015] In the most preferred form of the invention, each of first
and second panels 20, 21 has a thickness in the order of
0.625-0.875 inches (approximately 16-22 mm) and are spaced by
intermediate binder layer 23 in the order of 25 mils (0.6 mm). Of
course, these distances and dimensions are merely presented in
connection with a preferred embodiment of the invention such that
they can be readily altered in connection with forming other
standard door thicknesses and/or custom designs.
[0016] It has been found that, by using flax board, instead of
wood, and by using a sodium silicate fibrous adhesive, core 11
remains together during a standard 45 minute burn test. Also
advantageous is the fact that the flax board offers a very high
insulation coefficient versus particle board or inorganic products
because it contains air pockets in its structure, with the air
pockets also reducing the burning rate. The sodium silicate
adhesive provides a rating of 2000.degree. F. and can contain talc,
aluminum silicate of potash and soda, magnesium silicate, cellulose
and/or inert fillers, kaolin clay, mica, perlite and/or cristaline
silica. It should be noted that the sandwich construction of flax
board would not achieve the 45 minutes rating if laminated with
PVA, poly-urethane, epoxy or any other organic adhesives.
Therefore, it is the combination of flax board and sodium silicate
that makes this core so resistant to fire by creating a heat
barrier in center of the core. For instance, using only flax board
of even 1.5 inches (3.8 cm) thick as the core would not achieve the
same results and would fail the fire test. By constructing door
cores in accordance with the invention, doors can be assembled
easily with standard production lines that are handling the high
volume of 20 minutes particle board constructions. The door faces
or skins can be readily laminated to the door core without special
adhesives because two organic surfaces are being bonded
together.
[0017] FIG. 2 illustrates a preferred manner of forming core 11 in
accordance with the invention. In general, each of first and second
panels 20 and 21 are originally received from a stack 33 of
corresponding panels arranged on an in-feed scissor lift 35. Each
panel 20, 21 is systematically pushed directly through a coating
apparatus 48, at which both the first and second panels 20 and 21
are coated with a respective portion of binder layer 23, and then
placed upon a conveyor 42. In general, this step can be performed
in various ways, including spraying, pouring, painting and the
like. In the most preferred embodiment, a binder layer coating 23
of sodium silicate adhesive having a thickness of about 12 mils
(0.3 mm) is applied with a roller spreader on exposed surface of
each panel 20, 21. Thereafter, each panel 20, 21 is transferred to
another scissor table 50 as illustrated in FIG. 2 with respect to a
previously coated panel 20 being arranged on top of a stack 55 of
cores 11. As illustrated, top panel 20 on stack 55 has an exposed
coating of the binder layer 23. Thereafter, after panel 21 is fully
coated, panel 21 is flipped from upon conveyor 42 to a position
atop panel 20 in stack 55 thereby combining the binder layers 23 to
establish an adhesive thickness of approximately 25 mils (0.6 mm).
In this manner, each set of panels 20 and 21 are laminated together
to form the various cores 11 arranged in stack 55.
[0018] In accordance with the most preferred form of the invention,
after stack 55 has achieved a desired number of cores 11, e.g.,
20-25 cores, stack 55 is shifted upon a conveyor 60 to within a
cold press indicated at 65 for a prior stack 70 of cores 11. Each
stack 70 remains in cold press 65 until the various binder layers
23 are fully dried or cured, generally in the order of one hour.
Thereafter, the stack 70 is removed from cold press 65 upon
conveyor 75 such that cores 11 can be used in making a requisite
number of doors 2.
[0019] With the above arrangement, it has been found that a portion
of the sodium silicate adhesive penetrates the air pockets in the
flax board, becomes tacky and sticky, and dries in a cold press to
form a hard and glassy bond to weld the two panels together in
order to avoid separation or delamination during a 45 minute fire
test. Core 11 can then be trimmed on any or all of its four sides
for use in making a specified sized door 2, such as with the
addition of frame 5 and inner and outer door skins 14 and 15.
[0020] With this arrangement, it has been found that the flax-based
core 11 achieves at least a fire rating level of 45 minutes.
Therefore, a relatively inexpensive door 2 can be formed in
accordance with the present invention which exhibits low weight,
high mechanical strength, exceptional bonding for outer door skins,
good screw holding power, the ability to be readily cut to various
sizes, easy machining characteristics, and low dust generation
during machining as compared to more expensive mineral cores.
[0021] Although described with reference to a preferred embodiment
of the invention, it should be readily understood that various
changes and/or modifications can be made to the invention without
departing from the spirit thereof.
* * * * *