Note: Descriptions are shown in the official language in which they were submitted.
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CONSTRUCTION BOARD
FIELD
[0001] The present disclosure relates to construction boards, in particular
fiberboards.
BACKGROUND
[0002] Fiberboard (cellulosic fiber) ¨ structural and decorative ¨ is a
fibrous-felted,
homogeneous panel made from ligno-cellulosic fibers ¨ usually wood ¨ which has
a
density of less than 31 lb/ft3 (497 kg/m3), but more than 10 lb/ft3 (160
kg/m3). Fiberboard
is characterized by an integral bond which is produced by interfelting the
fibers, but which
has not been consolidated under heat and pressure as a separate stage in
manufacture.
Other materials may be added to fiberboard during manufacture to improve
certain
properties of the produced panel such as well known waxes to provide moisture
resistance
and well known plant derived starches for fiber bonding to impart degrees of
strength. It is
also well known in the long history of the manufacture of wood produced
fiberboards that
many sectors of building related projects are well suited for wood fiber
boards that impart
added thermal insulation qualities, sound suppression benefits, as well as
providing for an
economical construction cover board. For example, fiberboards are easy and
light to install
and may be used as interior wallboards or as exterior sheathing. Although
there have been
numerous advances in the history of fiberboard production in these areas there
are some
serious shortcomings that are inherent in the present state of the art. For
example, the
following are issues of concern with current construction boards and
fiberboards:
1) Wood fiberboards are flammable in nature and must not be left exposed under
existing
building code requirements; 2) Wood Fiberboards are susceptible to moisture
degradation
due to mold and organic decay and must be treated to meet existing building
code
requirements;
3) Wood fiberboards are generally weak in strength as compared to other
construction
cover boards where structural stability is required; and
4) Wood fiberboards are not smooth in composition and readily release fibers
when
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handled or lightly abraded during standard installation procedures and are not
considered
as acceptable candidates for architectural finishes such as paint.
[0003] Over the past several years, alternative materials to commodity grade
fiberboards
have become available, including gypsum boards, oriented strand boards (OSB),
expanded
polystyrene (EPS) and polyisocyanurate boards (Polyiso). Due to these
alternative
materials, demand for fiberboard has decreased. For example, production
capacity of
fiberboard in North America has been reduced by 37.5% over the last 5 years.
However,
these alternative materials have their own challenges and are less eco-
friendly than
fiberboard.
SUMMARY
[0004] The present invention relates to a wood fiberboard comprising wood
fibers bound
together with a binder polymer resin that imparts additional strength,
moisture resistance
and incorporating a thermal fire suppressing expandable flake inorganic
graphite and
sodium silicate component to render the fiberboard to be non-combustible.
[0005] The invention here described discloses a method of substantially
improving the fire
resistance properties of a Fiberboard (Cellulosic fiber) homogenous panel by
the admixture
during the manufacturing process of certain known intumescent and binding
materials in
such a way that a significant and unexpected improvement in the properties
ofthe
fiberboard composition may be achieved. In fact the unexpected improvements
rival
thermal resistance and fire protection properties that are only generally
achieved by well
known inorganic construction boards such as Dens glass, gypsum and concrete
wallboards
(Drywall)
[0006] In order to address the shortcomings addressed in the current state of
art mentioned
above, research was carried out to develop a process where the admixing of
preferred
components could be carried out in the standard manufacturing methods
currently
considered as the state of the art in the manufacture of said fiberboards. The
research
investigated:
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(a) A water borne polymer binder that can be added to the present
manufacturing process
so as to impart additional strength as well as impart water resistance. This
polymer binder
would be implemented in a similar manner and in a similar position as the
existing current
art of using the aforementioned waxes and starches.
(b) A known intumescent and/or fire retardant that would also be compatible to
the
existing current art of fiberboard production.
(c) A preferred method of surface treatment to the face of the fiberboard so
as provide for a
smooth and acceptable finish that incorporated the use of an inorganic sodium
silicate to
increase strength and fire resistance.
[0007] In the present application, the terms "fiberboard" and "construction
board" may be
used interchangeably.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Embodiments of the invention are described below with reference to the
following
drawings:
[0009] Figure 1 is a block diagram illustrating a manufacturing system for
producing a
construction board product according to one embodiment of the present
application;
[0010] Figure 2 is a block diagram illustrating a continuation of the
manufacturing system
for producing the construction board product according to the one embodiment
of the
present application;
[0011] Figure 3 is a graph illustrating the mean furnace temperature during a
full wall burn
test of a sample construction board having 30% of graphite by weight according
to an
embodiment of the present application;
[0012] Figure 4 is a graph illustrating the mean furnace temperature during a
full wall burn
test of a sample construction board having 15% of graphite by weight according
to an
embodiment of the present application;
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[0013] Figure 5 is a graph illustrating the unexposed face maximum temperature
during a
full wall burn test of a sample of construction board of the present
application;
[0014]Figure 6 is a graph illustrating the unexposed face average temperature
during a full
wall burn test of a sample of construction board of the present application;
[0015]Figure 7 is a graph illustrating the furnace pressure during a full wall
burn test of a
sample of construction board of the present application;
[0016]Figure 8 is a graph illustrating the surface temperature of a
conventional fiberboard
subjected to a heat test;
[0017]Figure 9 is a graph illustrating the surface temperature of a fiberboard
having a
silicate coating subjected to a heat test;
[0018] Figure 10 is a graph illustrating the surface temperature of a
fiberboard comprising
graphite according an embodiment of the present application subjected to a
heat test; and
[0019]Figure 11 is a graph illustrating the surface temperature of a
fiberboard comprising
graphite according an embodiment of the present application subjected to a
heat test.
DETAILED DESCRIPTION
[0020] In a first aspect of the present disclosure, a fiberboard composition
is provided
comprising a plurality of ligno-cellulosic fibers and an inorganic expandable
graphite in an
amount suitable for providing fire resistance. The ligno-cellulosic fibers may
be wood-
based, cardboard, or any other organic ligno-cellulosic fiber known to one
skilled in the
art. The inorganic expandable graphite forming part of the fiberboard
composition
provides fire-resistance properties. The inorganic expandable graphite may not
expand at
temperatures less than about 240 C. In some embodiments, the inorganice
expandable
graphite may not expand at temperatures less than about 220 C. A suitable
inorganic
expandable graphite is produced by Asbury Carbons and sold under the product
ID
Expandable Graphic Grade 1722HT (previously product number RD18702 HT). In one
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embodiment, the fiberboard comprises between 15% to 30% of graphite by weight.
In
other embodiments, the content of graphite in the fiberboard may be larger,
for example up
to 60% of graphite by weight. The graphite in the fiberboard improves the fire
resistance
properties of the fiberboard. For example, the fiberboards of the present
application meet
and exceed fire-resistance ratings according to Canadian and International
standards. Due
to the fire-resistance properties of the fiberboard, it may be used in various
industries and
applications, for example in interior home and building construction as well
as for exterior
sheathing of structures.
[0021] The fiberboard composition may further comprise a waterborne polymer
binder
resin in an amount suitable for providing water resistance. Various types of
waterborne
polymer binder resins may be used. For example, this waterborne polymer binder
resin
may be selected from the group consisting of: latex, natural rubber, gutta-
percha, styrene-
butadiene rubber, styrene-isoprene rubber, polyisoprene, polybutadiene,
polychloroprenes,
organic polysulphides, butyl rubber, halogenated butyl rubber, chlorinated
polyethelene,
chlorosulfanated polyethylene, ethylene-propoylene rubber, butadiene
acrylonitrile
copolymers, polyvinyl acetate, vinyl-acrylic, styrene- acrylic, and all
acrylic polymers, or
other waterborne polymer binder resins known to one skilled in the art. The
use of the
polymer binder resin instead of a starch binder provides a fiberboard with
increased
strength properties. Due to the increased strength of the fiberboard product
of the present
application, the fiberboard products may be used in various industries for
multiple
applications, including roofing systems, exterior siding, and sound proofing.
[0022] The fiberboard composition may further comprise a silicate for
enhancing fire
resistance. This silicate may be around 10% water-based and may be selected
from the
group consisting of sodium silicate and potassium silicate.
[0023] It is here disclosed a novel process that allows the admixing of
certain known
polymer binder formulations as well as the inclusion of known inorganic
intumescent
graphite particles in the present state of the art in the manufacturing of
Fiberboard
(Cellulosic).
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[0024] While various types of polymeric binders were found to be effective in
providing
the required strength and water resistance that included a wide range of
latexes well known
to the art that include dispersions of natural rubber, gutta-percha, styrene-
butadiene rubber,
styrene-isoprene rubber, polyisoprene, polybutadiene, polychloroprenes,
organic
polysulphides, butyl rubber, halogenated butyl rubber, chlorinated
polyethelene,
chlorosulfanated polyethylene, ethylene-propoylene rubber, butadiene
acrylonitrile
copolymers, polyvinyl acetate, vinyl-acrylic, styrene- acrylic, all acrylic
polymers and the
like. For properties needed to achieve the desired requirements, the preferred
binder was
found to be included in the class of elastomeric styrenated acrylic in which
the proportion
of styrene to methyl acrylic acid between 10/90 and 20/80 and the glass
transition
temperature of +5 C or higher as produced by Ona Polymers of Garland Texas
USA. The
ability to increase strength and water resistance was achieved by direct in
line addition of
approx: 2-3 gals per minute into the pulp slurry during the manufacture of the
fiberboard
as it was being formed just ahead of the forming line presses.
[0025] While various types of known fire retardants and inorganic intumescents
were
trialed including APP, diammonium salts, monoamonium salts, borates, and boric
acid, the
preferred inorganic intumescents was discovered to be expandable graphite as
produced by
Asbury Carbons and Sodium Silicate as produced by PQ Corporation which could
be
readily dispersed through the existing and current art of fiberboard
production.
[0026] The wood fiber used in the present method is acquired through
conventional
methods of processing recycled wood. For example, recycled wood products may
be cut
up into wood chips and processed using conventional processes to remove any
foreign
materials and other impurities. Such a conventional process may include use of
a belt and
magnet conveyor to remove any metallic foreign materials from the wood chips.
Next, the
wood chips may be treated using conventional processes for cleaning and
treating the
wood chips.
[0027] As shown in Figure 1, there is provided one embodiment of a
manufacturing system
100 for producing the construction board of the present application. In this
embodiment,
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the system 100 includes a machine chest 102, a constant level box 104 and a
head box 108.
The machine chest 102 contains a mixture of the processed and/or treated wood
fiber and
water (for example, also referred to herein as wood pulp slurry). During
manufacturing
graphite is added into the machine chest 102 at a substantially constant rate.
This allows
the graphite to evenly mix with the wood fiber pulp and water mixture prior to
the graphite
wood fiber mixture entering the head box 108. For example, the graphite may be
introduced into the machine chest 102 at a constant rate of ten (10) pounds of
graphite per
minute. The graphite may be added into the machine chest 102 manually or by
some
automated system or component (not shown). In alternative embodiments, the
graphite
may be introduced at a different location during the manufacturing process,
such as at the
head box 108 or prior to the machine chest 102.
[0028] The graphite wood fiber mixture previously combined in the machine
chest 102 is
moved via the constant level box 104 using a pump 106 into the head box 108.
The
constant level box 104 recirculates any overflow back to the machine chest
102. In some
embodiments, a coloring agent is added to the graphite wood fiber mixture
using a
coloration device 103 such that the finished product will have a particular
color. As well,
water is circulated into the head box 108 by a dilution device 105 to provide
a high water
content mixture.
[0029] The graphite wood fiber mixture is then evenly distributed onto the
formation table
110, which has a flat wire mesh surface. At the entry point of the formation
table 110 (and
after mixing with water in the head box 108), the graphite wood fiber mixture
is
approximately comprised of 99% water and 1% of combined wood fiber and
graphite. The
graphite wood fiber mixture is moved along the formation table 110 towards a
plurality of
rollers 118. Prior to reaching the plurality of rollers 118, water in the
graphite wood fiber
mixture is filtered out of the mixture through the wire mesh on the formation
table 110 and
into the water canal 116. As well, water may be further removed from the
graphite wood
fiber mixture using a low vacuum 112 and a high vacuum 114 along the formation
table
110. After the removal of the water using the low and high vacuums 112, 114,
the graphite
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wood fiber mixture is approximately comprised of 70% water and 30% of combined
wood
fiber and graphite. The graphite wood fiber mixture is then passed through a
plurality of
rollers 118 which flatten the mixture to a predetermined thickness. An
overhead vacuum
system 111 removes moisture and water from the graphite wood fiber mixture
while it is
being passed along the formation table and while it is being flattened. As
well, during the
flattening step, further water is removed from the graphite wood fiber
mixture, the water
falling into the water canal 116. After flattening, the mixture is now formed
into a semi-
rigid board on the formation table 110. An optional coating may be applied to
the semi-
rigid board at this stage from coating shower system 126. The semi-rigid pre-
fiberboard is
cut into predetermined sized pieces by the cross-cutter 120 and then is sent
to a dryer
system 200 for drying and hardening. At this stage, the semi-rigid pre-
fiberboard is
approximately comprised of 48% water and 52% of combined wood fiber and
graphite.
Any excess graphite wood fiber mixture falls into a pulper 122 and is stored
in a reserve
chest 123.
[0030] Figure 2 illustrates the dryer system 200 as part of the overall
manufacturing system
of the fiberboard shown in Figure 1, according to the one embodiment of the
invention.
The semi-rigid board continues onto one or more conveyors 202 into one or more
dryers
204. The dryers 204 operate to remove the majority of the remaining water that
is in the
semi-rigid fiberboard. The dryers 204 remove a significant amount of water
such that the
dried fiberboard leaving the dryers 204 is approximately comprised of 5% water
and 95%
of combined wood fiber and graphite. The dried fiberboard exits the dryers 204
onto one or
more conveyors 205 and may be cut into predetermined sized pieces by one or
more saws
206. The fiberboard may be cut in any size of board. After the dried
fiberboard has been
cut, the fiberboard proceeds onto a conveyor 208 to receive final treatments.
For example,
the surface of the fiberboard may be smoothed by a calender 210, the surface
of the
fiberboard may receive a polymer coating applied by a coating device 212 and
the surface
of the fiberboard may be laminated by a lamination device 214. After receiving
the one or
more final treatments, the finished fiberboard product may be stored. The
finished
fiberboard may be cut into boards having generally the dimensions 4 feet x 8
feet x 1/2 feet.
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The fiberboard may be cut into any size and the thickness of the finished
fiberboard may
vary depending on the intended end use application.
[00311 During the trials there were a number of obstacles that needed to be
overcome.
[0032] 1. Polymer Binder
(a) Although a waterborne polymer emulsion was compatible with existing
manufacturing
methods during the process it was found that the surfactants in the polymers
had to be re-
worked and cross linked as they were impacting water resistance due to their
very nature
of being hydrophilic. A new proprietary surfactant had to be added to the
polymer binder
with a cross linking agent WB31B(metal complex) as produced by Federal Process
Corp
that reacts only after the formulation soaks into the wood fiber and the water
evaporates.
Cross linking the surfactant destroys its ability to attract water and
preserves depth of
penetration better than solvent-based systems.
(b)The polymer binder had to be adjusted to a cationic ph of 6 or less so as
bind to the
cellulosic fiber as the fiber carried an anionic charge to enhance attraction.
(c) The polymer binder may be added to the machine chest 102 or may be added
to the
head box 108, for mixing with the wood fiber slurry. As well, the polymer
binder may be
added at another point during the manufacturing process. The use of the
polymer binder
rather than conventional binders (e.g. starch) results in a stronger
fiberboard product. Due
to the increased strength properties of the fiberboard of the present
application, it may be
used in various industries and for various applications that conventional
fiberboard could
not be used, for example for roofing applications which require a certain
level of structural
strength, for example, to permit walking on top of fiberboard.
(d) The percentage of the polymer binder in the fiberboard was trialed
approximately
between 0% to 15%.
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TC12-xxxx
(ID #) 173G 1741 17411 170A 174J
Binder Starch Starch Starch polymer
polymer
% solids of Binder N/A N/A N/A 55% 55%
Weight of Binder 2.07% 2.12% 2.02% 1.91%
1.93%
Wood Fiber 28.05% 27.80% 27.25% 28.08%
27.92%
Water 69.88% 68.98% 67.02% 69.83%
68.73%
Crosslink-WB31B 0.00% 0.00% 0.00% 0.18%
0.18%
Wax 0.00% 1.09% 3.70% 0.00%
1.24%
Total 100.00% 100.00% 100.00% 100.00% 100.00%
Wt.Before
water(g) 8.5640 (g) 7.9883(g) 8.4619(g) 8.4225(g)%
8.0680(g)
Wt.After 2Hr (g) 14.5257(g) 12.6892(g) 12.3866(g) 11.3183(g)
10.2342(g)
Absorption 2Hr
(%) 69.61% 58.55% 46.38% 34.38%
26.85%
Wt.Before
water(g) 8.3347(g) 8.3696(g) 8.5919(g) 8.8394(g) 8.1127(g)
Wt.After 4Hr (g) 34.9321(g) 14.8635(g) 14.7384(g) 11.9293(g)
10.8069(g)
Absorption 4Hr
(%) 319.10% 77.59% 71.54% 34.96% 33.21%
Table 1.1
[0033] Table 1.1 illustrates a comparison between conventional fiberboards
having starch
as a binder and fiberboards of the present application which utilize polymer
as a binder.
The example fiberboards 173G, 1741 and 17411 each utilized starch as a binder.
Starch is a
highly combustible material. Fiberboards 173G, 1741 and 17411 have generally
the same
percentages of wood fiber, water and weight of the starch binder. The
characteristics of
fiberboards 173G, 1741 and 174H differ in the percentage of wax used, with
173G having
0%, 1741 has 1.09% and 17411 having 3.70%. The use of wax in the fiberboards
decreases
the water absorption percentage after 2 hours and after 4 hours, with the
highest amount of
wax 3.70% in fiberboard 17411 providing the lowest water absorption rates.
[0034] As shown in Table 1.1, Fiberboards 170A and 174J of the present
application utilize
the above-described polymer as a binder. The fiberboards 170A and 174J have
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the same percentages of solids of the polymer binder, wood fiber, crosslink-
WB31B and
water, and generally the same weight of the polymer binder. The
characteristics of the
fiberboards 170A and 174J differ in the percentage of wax used, with 170A
having 0% and
174J having 1.24%.
[0035] When comparing conventional fiberboard 173G with the fiberboard 170A
according to the present application, where both have no wax component, it is
shown that
the water absorption percentage (2hours and 4 hours) is reduced significantly
when the
binder of the fiberboard is the polymer binder having the new proprietary
crosslinking
agent WB31B of the present application. For example, the 4 hour water
absorption
percentage of the fiberboard 170A of the present application is 34.96% in
contrast to the
conventional fiberboard 173G which has a 4 hour water absorption percentage of
319.10%.
[0036] Fiberboard 174J of the present application differs from fiberboard 170A
in that it
contains 1.24% of wax. The introduction of the wax does not provide a
significant
decrease in water absorption percentages, as the 4 hour water absorption
percentage of the
fiberboard 174JA of the present application is 33.21% and the 4 hour water
absorption
percentage of the fiberboard 170A (without wax) of the present application is
34.96%.
[0037] Conventional fiberboards 173G, 1741 and 174H are made with a starch
binder and
include a wax component in order to reduce percentages of water absorption.
However,
one problem with using starch and wax in fiberboards is that these materials
are highly
flammable. In the present application, the fiberboards are manufactured
without starch and
without wax, making them less flammable than conventional fiberboards. Instead
of a
starch binder, the fiberboards of the present application manufactured with a
polymer
binding, which results in decreased water absorption percentages than the
conventional
starch binder based fiberboards.
[0038] 2. Expandable Graphite
(a) Expandable graphite is known as an intercalation compound, the expansion
factor and
ability to expand is determined by temperature gradients. It is thus desirable
that the
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expansion occur rapidly once the material reaches a certain critical value.
Most commonly
the temperature at which such expansion commences is within the range of 150 C
to
220 C. The production of Fiberboard requires travel through ovens 204 (Figure
2) in the
drying process where temperatures exceed 240 C. It was imperative that we have
the
manufacturer of the graphite produce graphite with higher temperature limits.
Asbury
Carbons a world leader in carbon mining was able to formulate a new high
temperature
reactive graphite that met our requirements and it has been commercially
branded as
Expandable Graphic Grade 1722HT (previously identified as RD 18702
HT).Accordingly,
with the use of the expandable graphic having higher temperature limits,
particularly
Grade 1722HT, this obstacle was overcome. Table 1.2 shows the typical
properties of
expandable graphite at different grade levels as indicated and sold by Asbury
Carbons. As
previously discussed, for the present application, the preferred grade of
expandable
graphite is 1722HT as the onset temperature is very high (220-230 C); and will
work with
furnace temperatures in the 240 C range.
3772 >300 ?98 0.9 3.1 300:1 5-10 180 -
200
1721 >300 >98 0,9 3,5 300:1 1 - 6 180 -
200
3721 >300 > 95 0.9 3.5 290:1 5-10 180 -
200
1722 >300 > 95 0.9 3.5 290:1 1 - 6 180 -
200
3335 >300 ?85 0.9 3,2 270:1 5-10 180 -
200
3577 > 300 > 85 0.9 3.4 270:1 1 -6
180 - 200
3570 > 180 > 80 0.8 3.1 230:1 5-10
150 170
1395 >180 280 0.8 3.5 230:1 1 - 6 150
170
3558 -= 180 > 99 0,8 3,1 210:1 5-10
180 - 200
3626 >75 2,80 0.6 3.0 160:1 5 - 10 150-
170
3494 >75 ?80 0.9 2.9 90:1 1 - 6 160 -
180
3538 -. 75 ?80 1.4 2,6 60:1 5-10
200 - 225
1722111 >300 > 95 1,6 5,0 220:1 1 -6 220 -
230
_
Table 1.2 ¨ Asbury Carbons - Typical Properties Expandable Graphite
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(b) As the expandable graphite is a solid and not a liquid, this posed a
problem as to how
and where to insert the required flow so as to have correct particle
distribution throughout
the mass of the fiberboard panel. This obstacle was overcome after trialing
numerous entry
areas. The preferred entry point was identified at the existing head box 108
that in
fiberboard production provides the distribution of wood fiber slurry by high
volume
agitation evenly throughout the main forming line. By adding the graphite at
the rate of 10
lbs per minute at this location very uniform particle distribution was
recorded. In some
embodiments, the graphite is added to the machine chest 102 at a constant
rate, prior to the
head box 108. The introduction of graphite during the fiberboard manufacturing
process as
described herein results in a fiberboard product having improved fire
resistance properties.
[0039]3. Surface Treatment
[0040] The surface treatment of the face of the boards is realized by
subjecting the finished
board as it came out of the dryers 204 to a surface coat of sodium silicates
(case trials were
done with both sodium and potassium silicates and sodium due to its relatively
inexpensive
cost was chosen as the preferred method.) The surface treatment was optimized
using a
spray coat of a 10% water based solution(higher and lower concentrations in
the range of
5% to 100% were trialed but the optimum was 10%) of inorganic sodium silicate
which
quickly penetrated the surface of the fiberboard and then was sent into a
calender press
roller 210 to provide a suitable smooth profile for paint application. In some
embodiments,
the surface treatment is performed by a coating device 212 after the
fiberboard is sent into
the calender press roller 210, as shown in Figure 2. The application of the
sodium silicate
was enhanced by the addition of a high heat (450E-500F) pressure compression
roller that
not only provided for a smooth surface but in doing so set the sodium silicate
due to the
high temperature flash drying of the water carrier that resulted in a smooth
glass like
appearance that provided an additional fire resistance quality that is well
known in this
particular chemistry of silicates otherwise known as waterglass.
[0041] To exemplify the fire resistant characteristics of the fiberboard of
the present
application, full wall burn tests were performed. For these tests, fiberboard
made with
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natural pulp and comprising the graphite, polymer resin binder and the
silicate coating was
used. A first batch of the fiberboard was produced with a graphite content of
15% by
weight (for example, during manufacturing the graphite may be added at a rate
of 5 lbs of
graphite per minute) and a second batch of fiberboard was produced with a
graphite
content of 30% by weight (for example, during manufacturing the graphite may
be added a
rate of 10 lbs of graphite per minute).
[0042]Figure 3 is a graph of the mean furnace temperature during the CAN ULC
S101-14
full wall test of fiberboard from the second batch having a graphite content
of 30% by
weight. The x-axis of Figure 3 represents the temperature of the furnace in
Fahrenheit and
the y-axis represents the length of time in minutes the fiberboard burns until
it reaches a
failure state. For the purposes of the full wall burn test, a failure state of
the fiberboard is
when the fiberboard reaches a thermal loss value that exceeds ASTM
fireproofing
standards. As shown in Figure 3, two thermal losses occur after 35 minutes and
after 40
minutes. Conventional fiberboards subjected to a similar full wall burn test
would reach a
thermal loss within 5 minutes. Accordingly, the fiberboard of the present
application
provides superior fireproofing qualities compared to conventional fiberboard.
This
improved fireproofing characteristic of the fiberboard of the present
application is in part a
result of the graphite added to the fiberboard during manufacturing.
[0043] Figure 4 is a graph of the CAN ULC S101-14 mean furnace temperature
during the
full wall test of fiberboard from the first batch having a graphite content of
15% by weight.
As shown, a thermal loss occurs on the graph between 25 and 30 minutes.
Accordingly,
when comparing the full wall burn test results of the first batch of
fiberboard having 15%
graphite by weight with the second batch of fiberboard having 30% graphite by
weight, it
is shown that the increased amount of graphite in the fiberboard resulted in
an increase in
time before a thermal loss event occurs, thereby improving the fireproofing
characteristics
of the fiberboard.
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[0044] Figure 5 is a graph illustrating the unexposed face maximum temperature
during a
CAN ULC S101-14 full wall burn test of a sample of construction board of the
present
application;
[0045] Figure 6 is a graph illustrating the unexposed face average temperature
during a
CAN ULC S101-14 full wall burn test of a sample of construction board of the
present
application;
[0046] Figure 7 is a graph illustrating the furnace pressure during a CAN ULC
S101-14
full wall burn test of a sample of construction board of the present
application.
[0047] The fiberboard (Cellulosic fiber) of the present application is
rendered non-
combustible due to the inclusion in its composition of a new high temperature
activated
expandable graphite.
[0048] As well, the fiberboard (Cellulosic fiber) of the present application
has improved
strength characteristics and water resistance properties due to the inclusion
of polymer
binders in its composition.
[0049] Also, the fiberboard (Cellulosic fiber) of the present application has
a sodium
silicate (waterglass) surface treatment and compressed profile that results in
a smooth and
paint ready surface with inherent fire resistant properties.
[0050] Thermal testing was conducted on sample fiberboards to illustrate the
effects that
the silicate and graphite, alone and in combination, have on the thermal
resistant properties
of the fiberboard of the present application. As a baseline, a thermal test
was conducted on
a standard conventional fiberboard. For each of the thermal tests, the furnace
temperature
was maintained at an approximate temperature of 1500 F. On the graphs in
Figures 8 to
11, where the unexposed surface temperature of the board is shown to surpass
the furnace
temperature is an indication of a thermal loss event, which may considered as
a failure
point of the fiberboard that is being subjected to heat.
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[00511 Figure 8 illustrates the results of such the thermal test on a
conventional fiberboard.
As shown, the unexposed surface temperature of a conventional fiberboard
rapidly rises to
just over 1400 F and reaches a failure state in less than approximately 2
minutes.
[0052]Figure 9 illustrates the results of the thermal test on a fiberboard
having a silicate
coating. As previously discussed, a silicate coating provides fire-resistant
properties to a
fiberboard. In Figure 9, the unexposed surface temperature rises to
approximately only
400 F after 30 minutes of exposure, despite the furnace temperature being
approximately
1500 F. The fiberboard having the silicate coating reaches a failure state at
approximately
between 35 and 40 minutes. Accordingly, the silicate coating on the fiberboard
provides
improved thermal resistance when compared with the heat test results of the
conventional
fiberboard of Figure 8 which reached a failure state within 2 minutes under
the same
furnace temperature conditions.
[0053]Figure 10 illustrates the results of the thermal test on a fiberboard
comprising a
predetermined percentage of graphite, according to the present application. As
previously
discussed, the introduction of graphite during the fiberboard manufacturing
process, as
provided in the present application, improves the fire resistant properties of
the fiberboard.
In Figure 10, the unexposed surface temperature rises to approximately only
400 F after
about 35 minutes of exposure, despite the furnace temperature being
approximately
1500 F. The fiberboard comprising the graphite reaches a failure state at
approximately
between 40 and 50 minutes. Accordingly, the fiberboard comprising graphite
provides
improved thermal resistance when compared with the heat test results of the
conventional
fiberboard of Figure 8 which reached a failure state within 2 minutes under
the same
furnace temperature conditions.
[0054]Figure 11 illustrates the results of the thermal test on a fiberboard
comprising a
predetermined percentage of graphite and having a silicate coating, according
to the
present application. In Figure 11, the unexposed surface temperature rises to
approximately only 400 F after about 45 minutes of exposure, despite the
furnace
temperature being approximately 1500 F. The fiberboard comprising the graphite
and
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having the silicate coating reaches a failure state at approximately 50 to 55
minutes.
Accordingly, the combination of the fiberboard comprising graphite and having
a silicate
coating provides the greatest level of thermal resistance relative to the
examples provided
in Figures 9 (fiberboard having silicate coating only) and 10 (e.g. fiberboard
comprised of
graphite only). As well, the combination of the fiberboard comprising graphite
and having
a silicate coating provides significant improvement of thermal resistance
(e.g. failure after
50 minutes of heat exposure) when compared with the heat test results of the
conventional
fiberboard of Figure 8 which reached a failure state within 2 minutes under
the same
furnace temperature conditions.
to [0055]Furthermore, various tests (for example, to identify thermal
conductivity, water
absorptiveness) were performed to compare the standard specifications of
gypsum board
(for example, according to ASTM 1.1.1 standard) to samples of the fiberboard
of the
present application. For these tests, the fiberboard samples of the present
application has a
thickness of approximately 5/8 inches. As well, the tests were performed on
samples of
5/8" gypsum boards having water-repellent surfaces.
[00561 Tables 2.1 and 2.2 show results of thermal conductivity tests performed
in
accordance with the ASTM C518 standard. In Tables 2.1, the thermal
conductivity of the
gypsum boards is shown. The RSI value for thermal resistance is 0.08 Cm2/W for
the
gypsum board, the heat flow rate in the measured area is 12.45W, and the
thermal
conductivity rating is R=0.48.
Haat flow*
Thervial Thermal
Sample AX r.km WI In the mettrtd AT K
RSI Ofy visight DensItY
resistance t V" imitate
iros {0}
= in (") in W BR* I Tp124)
'Foehl BTU *pet/ BTU 'C fit W 9 bs pe
518' gypsJrn 0625 0620 12.45 2.04 1.305 0.766 0,48
008 1036.08 4428
Table 2.1 ¨ Thermal conductivity on 5/8" gypsum boards with water-repellent
surfaces
(According to Standard ASTM C518)
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[0057] In Table 2.2, the thermal conductivity properties of sample fiberboards
of the
present application are shown (for example, the fiberboard has the proprietary
name
"Starboard"). For the fiberboard #7 having the characteristics and properties
of the present
application, the RSI value for thermal resistance is 0.29 Cm2/W and the heat
flow rate in
the measured area is 5.53W. The other tested fiberboard #8 of the present
application as
tested had a similar RSI and heat flow rate as fiberboard #7. The thermal
conductivity
rating of fiberboard #7 is R=1.63 and of fiberboard #8 is R=1.59.
Heat flow rale
Thema! Themii
Ample AX dameld AK in the metered Al KRS
NY weight Dia*
mislays al 11 restebnce
(Q)
C.911.h RV V=Vit I BM =C .m2 W
gbetpil
Starboard #7 1625 0.610 5.53 2.97 0.375 2.667 1.63
0.29 484.36 21.04
Starboard #8 0.625 0.590 5.63 2.94 0.372 2.688 1.59
0.28 473.42 21.26
Table 2.2 ¨ Thermal conductivity on 5/8" MSL fireproof and calendered
fiberboard of the
lo present application (According to Standard ASTM C518)
[0058] Accordingly, from the testing it is shown that the fiberboard produced
according to
the present application has improved heat resistance properties (e.g. RSI,
heat flow rate)
over gypsum boards.
[0059] Tables 3.1. 3.2 and 3.3 show results of water absorptiveness tests
performed on the
gypsum board samples (Table 3.1) and the fiberboard samples of the present
application
(Table 3.2 and 3.3), in accordance with the ASTM D3285 Standard Test Method
for Water
Absorptiveness of Nonbibulous Paper and Paperboard (also known as the "Cobb
Test"). In
table 3.1, the results of the Cobb Test for the gypsum board samples is shown,
where the
average absorption of the gypsum board over a 4 hour period was 773.64 g/m2
and the
average surface absorption was 3.24%.
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Sample Initial weight Final weight Absorption
Sudace absorption
4 hours 9 0 011112 %
C-1 251 57 258.05 651.91
2.51
C-2 213.40 221.81 846.08
3.79
C-3 211 93 220.52 864.19
3.90
C-4 254 97 262.25 732.40
2.78
Average 23217 24016 773.64
314
Table 3.1 - Cobb Test on 5/" gypsum boards with water-repellent surfaces
(white side)
(test duration: 4 hours)
[0060]In Table 3.2, the results of the Cobb Test for the fiberboard samples of
the present
application is shown, where the average absorption of the fiberboard over a 2
hour period
was 244.22 g/m2 and the average surface absorption was 2.06%.
SallTt!. '
2 hour& , - 9 ,.:' ' = , :-, ___ ----, -.9:.,
,,.._..:40744,WF,-.:::.-.
-
cl 112.25 11451 221.37 117
C-2 114.79 117 03 225 35
1.91
C-3 116.41 119.06 266.80
2.23
C4 117.76 120.32 257.55
2.13
Average 115,30 117.73 244.22
2.06
Table 3.2 - Cobb Test on 5/8" MSL fireproof and calendered fiberboard of the
present
application (test duration: 2 hours)
[0061] In Table 3.3, the results of the Cobb Test for the fiberboard samples
of the present
application is shown, where the average absorption of the fiberboard over a 4
hour period
was 303.57 g/m2 and the average surface absorption was 2.72%.
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Sample klit0Wattti Fine weight
4*Itikbsot*in
- = -
4 bows
C.1 1C,60 Y1.79 320.93
2.85
C.2 105,59 108 68 310.87
2.84
C,3 110.94 113.59 266.60
2.33
C4 107.50 110.64 315.90
2.84
Average 108.16 111.18 303.57
2.72
Table 3.3 - Cobb Test on 5/8" MSL fireproof and calendered fiberboard of the
present
application (test duration: 4 hours)
[0062] Accordingly, from the testing it is shown that the fiberboard produced
according to
the present application has reduced absorption properties and characteristics
(absorption
and surface absorption percentage) over gypsum boards.
[0063] Table 4 shows results of an absorption by water immersion test
performed on the
fiberboard samples of the present application, according to the ASTM C209
Standard
(Standard Test Methods for Cellulosic Fiber Insulating Board - Section 14). As
shown in
Table 4, after a 2 hour test duration, the average absorption percentage is
6.81%.
Sample Initial weight Final weight Absorption
Absorption
2 hours
A-1 112.40 130.68 18.28
4.96
A-2 109.71 128.57 18.86
5.12
A-3 113.92 134.95 21.03
5.70
A4 116.16 158.48 42.32
11.48
Average 6.81
Table 4 - Absorption by water immersion on 5/8" MSL fireproof and calendered
fiberboard of the present application
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[0064] Strength tests were also performed on the fiberboard of the present
application.
Table 5 shows the measured results of a tensile strength test performed
according to the
ASTM C208 Standard (Section 13). As shown in Table 5, the tensile strength
perpendicular to the surface of the fiberboard was measured, with an average
net strength
of: 620.67psf, 281.53kg and 29.72Kpa.
Sanvie TEST TARE
Net strength Average Net strength Avsrage Net strength Average Side
Psf Psf Psf Psf kg kg KPa Psf kg Kin, -
S-1 785 18 767 34791 3E72
Bottom
S-2 496 18 478 620.67 216 82 281.53
22,89 29,72 120 - 55 6 Top
635 18 617 279 87 29,54 Bottom
Table 5 ¨ Tensile strength perpendicular to surface on 5/8" MSL fireproof and
calendered
fiberboard of the present application
[0065] Tables 6.1 and 6.2 show the measured results of transverse strength
tests performed
on the fiberboard of the present application, according to the ASTM C209
standard
(Section 10). In table 6.1, the average transverse strength perpendicular to
the board panel
length of the "M" samples was 28.501bf and the average transverse strength
perpendicular
to the board panel length of the "T" samples was similar with 27.83 lbf After
a two week
curing period, the transverse strength was measured again, and as shown in
table 6.2, the
average transverse strength of the "M" samples was 25.17 lbf and the average
transverse
strength of the "T" samples was similar with 24.70 lbf. In contrast, a gypsum
board has a
standard specification (according to ASTM 1.1.1) of transverse strength
perpendicular to
the board panel length of 23.5 lbf. Accordingly, the fiberboard of the present
application
has an increased transverse strength compared to gypsum board.
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Sample Transverse strength Average
5/8" Starboard lb( 1b1
1-M
2-M 28/
3-M 234 28.50
4-M 29.8
5-M 27.5
1-T 28.0
2-T 27.8
3-T 284 27.83
4-T 27.7
5-T 27.4
Table 6.1 ¨ Transverse strength test on 5/8" MSL fireproof and calendered
fiberboard of
the present application
Sample Transverse strength Average
5/8" Starboard
1-M 25.9
2-M 29.5
3-M 234 25.17
4-M 24_2
5-M 25.4
1-T 23.7
2-T 21.2
3-T 25_6 24.70
4-T 24.8
5-T 25.0
Table 6.2 ¨ Transverse strength test on 5/8" MSL fireproof and calendered
fiberboard of
the present application after a two week curing time
[0066] Calculations were performed to determine the average density of the
fiberboard of
the present application. As shown in Table 7, for a fiberboard having a
generally uniform
5/8" thickness, the average dry weight was 460.94g and the average density is
19.91
lbs/ft3.
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Sample Production Average thicknass 1:¶Y wei9ht
Density
Natural so Code In 9 11,
I Pe
1 MSL Starboard-CA 0.6155 463.10
19.94
2 MSL Starboard-CA 0.6150 461.03
19.87
3 MSL Starboard-CA 0.5980 444.31
19.69
4 MSL Starboard-CA 0.6265 473.71
20.04
MSL Starboard-CA 0.6141 462.70 19.97
6 MSL Starboard-CA 0.6158 463.10
19.93
7 MSL Starboard-CA 0.6164 466.12
20.04
8 MSL Starboard-CA 0.6159 464.17
19.97
9 MSL Starboard-CA 0.6036 452.60
1987.
MSL Starboard-CA 0.6148 458.54 19/7
Average _ 0.6135 460.94
1991.
Table 7 - Average density calculation of the 5/8" MSL fireproof and calendered
fiberboard
of the present application
5 [0067] One or more currently preferred embodiments have been described
by way of
example. It will be apparent to persons skilled in the art that a number of
variations and
modifications can be made without departing from the scope of the invention as
defined in
the claims.
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