Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BAC~GROUND OF THE INVENTION
Fire retardant compositions are generally applied
to fire unstable materials as a surface coating. The -
composition, in a liquid form, is applied to the surface by
brush painting, or spray painting or by some form of
printing equipment, such as the use of a doctor roll. If
the liquid is a viscous relatively thick material, its
effectiveness will depend on its ability to adhere to and
remain on the surface of the fire unstable material during
production, handling, installing and use of the resultant
fire retardant structure. Upon exposure to flame and heat,
it may separate from the surface or the action of the flame
and heat may cause ablation, thus allowing exposure of the
flame and heat to the fire unstable material and defeating
the purpose of applying the fire retardant material.
When the fire retardant material is relatively
inert, or has an inert surface finish as in the case of
polymeric materials or a particle board bonded with a
resinous type material, such as, a phenol-formaldehyde
resin, it is difficult to get good adherence of the fire
retardant composition.
The use of additional substances in an attempt
to increase adherence may be self-defeating. Adhesives~
- solvents, etc. may offset or detract from the effectiveness
of the fire retardant material. These substances may be
flammable themselves or may react with the fire retardant
composition in some fashion to lessen its usefulness.
The present invention has as a principal object
the incorporation of fire retardant compositions into the
surface of fire unstable materials so that they will
tenaciously adhere and remain as a part of the fire un-
stable material during production, handling and use of
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1~146~a3
the resulting fire retardant structure. It has also been
discovered that by the present invention the resistance to
flame and heat exposure of the resultant structure are
significantly enhanced.
SUMMARY OF THE INVENTION
A method for treating fire unstable materials with
a fire retardant composition and the resulting fire and flame-
proof structure are provided. The method involves insinuating
or pressure injecting a fire retardant composition into the
surface of a fire unstable material to an appreciable depth
and thus tenaciously adhering the composition thereto so that
the resultant structure will not be subject to damage by
abrasion or impact during handling and usage. The structure
also provides resistance to the detrimental affects of the
flame and heat during exposure thereto and a fire and
flameproof structure is created.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a treatment of
fire unstable materials so that the fire retardant composi-
tion is pressure injected or insinuated into the surface of
the fire unstable material to an appreciable depth. It is
accordingly tenaciously adhered to the fire unstable materi-
al, and in fact incorporated into the material so that the
resulting structure is rendered more protective against
exposure, even for prolonged times, to fire and heat.
The fire unstable materials may be in the form of
stratas or layers having large surface areas. The fire un-
stable material may be made of paper, cardboard, wood, other
cellulosic materials, synthetic plastic materials of a poly-
meric type, or the like. They may also be made of glass or
metal fibers which may be subject to severe deterioration in
1~ i4Çi~3
;
the presence-tof~prol~ng~ih~ab ~n~mf~am~ Su~h,~a~erials
may be in the form of boards, stratas, or even laminates,
depending upon the use to which they are to be put and
the structural requirements desired. Since the present
invention in general relates to a surface treatment of the
fire unstable material it will in general be discussed with
respect to boardlike structures such as wood, polymeric
materials, especially polystyrene, polyurethane and the
like in a foamed cellular configuration, but it will be
appreciated that the invention is applicable to the surface
treatment of any fire unstable material. Thin metal alloys,
particularly those of aluminum and magnesium used in air- ;
craft or mobile homes may be subject to severe damage and r
~ even burning when exposed to flame and heat.
!j In accordance with the present invention, suitable
fire or flame retardant compositions may encompass a wide
variety o~ chemical compositions having the characteristics
of imparting to the surface of a fire unstable material a
desired resistance to flame and heat. Fire retardant
compositions are available which when applied to the surface
of a synthetic polymeric material have the effect of
rendering the material incapable of supporting combustion
;~ when t~ei source of ignition or flame is removed from the
vicinity of the fire unstable material. Many of these
chemicals depend on a halogen content to provide fire and
flame retardant characteristics. Metallic oxides are
another well-known ingredient for fire retardant composi-
tions. ~arious combinations of halogenating materials and
metallic oxides may be useful.
3Q It is believed that to obtain more nearly fire
and flameproof structures, fire retardant compositions
having intumescent properties are the most desirable.
45~`~
Such compositions under exposure to heat and/or flame appear
first to soften and then yield a voluminous foam which serves
as an insulating barrier to protect the fire unstable mate-
rial. Upon prolonged exposure to flame and heat, the insula-
ting intumescent foam carbonizes and forms a stable insulat-
ing char which continues to protect the fire unstable`mate-
rials with remarkable efficiency.
A particularly preferred fire and flameproof compo- ~ ~
sition is that obtained due to the reaction of phosphorous ,
acid and a reducing sugar with the possible addition of at
least one supplemental foam producing additive. Compositions
of this type can provide intumescence at significantly lower
temperatures such as below 100C., and thus provide earlier
and longer lasting protection. Fire and flameprobf composi-
tions for use in the present invention have been derived from
the teachings of the patents of Dr. Ralph Matalon in U.S.
patents 3,551,365, 3,808,159, and 3,824,200.
- While a number of fire retardant compositions may be
used to illustrate the present invention, a particularly
suitable composition is being selected because of its highly
effective properties. This composition involves the resin-
ous reaction product of a resin forming substance (designated
as RF71) and a hardener substance (designated as 175F). The
resin forming substance comprises the following approximate
weights of ingredients: 3% water, 41% phosphoric acid (85%
strength, it being understood that the strength of the acid
used is dependent upon the water that may exist elsewhere
in the formulation and the strength or amount of acid may be
adjusted to compensate),
6~3
dextrose 56%.
It is generally desirable to increase the intumescent
properties of the resin former for its intended fire resistant
use by the addition of at least one substance having the
property of evolving gas, especially under the influence of
heat. Examples of such substances are monoammonium phosphate,
oxalic acid, urea, monoethanolamine, and the like. Illustra-
tive of a resin former substance having such additives is
that identified as RF77, comprising the following proportions ,r
_ lO by weight: about 3% water, about 31% phosphoric acid (85~
strength), about 43% dextrose, about 8% monoammonium phosphate,
about 4~ oxalic acid, about 10% urea, and about 1% monoethanol-
amine.
The resin former substances may be prepared by ;
charging the water and phosphoric acid to a kettle and heating
, the same to about 70-90C. The reducing sugar is added andthe mixture agitated for about lO to 15 minutes. Any
~, additional desired additives to provide increased intumescence
in the final product are added and also thoroughly agitated.
The kettle is closed, heated to about 120C for about 10
minut0s, allowed to cool, and the contents discharged.
A suitable hardener or curing agen~ may comprise
the following ingredients by weight: water about 4~, dextrose
about 35~, urea about 28%, sodium hydroxide (3~ strength)
about 3%, furfuryl alcohol about 5~, and paraformaldehyde
about 25%. The following procedure is illustrative of the
method of making the hardening agent. The sodium hydroxide,
water, furfuryl alcohol, and paraformaldehyde are charged
to a reactor and mixed until dissolved at a temperature of
approximately 90~C. The dextrose is added and mixed until
a homogenous solution is formed. The mixture is cooled or
allowed to cool to about 400C, followed by addition of the
--6--
;
1~46~
urea and monoethanolamine. This results in an exothermic
reaction and it is desired that the mixture be allowed to
heat, but not to rise above the temperature of 110C, with
the reactor closed. The mixture is held for about 25
minutes, allowed to react and then discharged. Alterna-
tively, water and dextrose may be charged to the kettle,
; heated and mixed until they are dissolved at about 90C.
The urea is charged and stirred until dissolved. The
kettle is allowed to cool or is cooled by heat transfer
to about 60C, at which time the sodium hydroxide, furfuryl
alcohol, and the paraformaldehyde are added. The kettle
is closed, heated to about 110C and stirred while maintain-
; ing the temperature for about 25 minutes. As the tempera-
ture cools, the monoethanolamine may be added and stirred.
When the mixture is cooled, it is then ready for use.
The fire and flame retardant composition is then
prepared by mixing the resin former and the hardener. They
may be mixed in a preferred ratio of about 1 to 1, however,
this ratlo may be varied with the approximate range of
resin former to hardener being about 3 to 1 to about 1 to
4 depending upon the physical properties or function desired
in the resultant composition. The end product is a thick,
viscouz liquid having a density of about 12 grams per cubic
centimeter.
To accomplish the surface treatment of a fire
unstable material, the fire and flame retardant composition
has been made into the form of a powder. This may be
accomplished by heating the liquid fire retardant composi-
tion in a vessel having a large surface area compared to
volume and then comminuting or grinding the dried cake to
~14~
a powdered or pulverized form. A particularly desirable
flame retardant powder is produced by mixing the previously
` described resin former and hardener in a ratio of 1 part
- former to 1 part hardener. The mixture is heated to a
temper~ture of approximately 70 to 80C and held until it
becomes a dried cake in about 72 to 90 hours. The cake is
relatively friable. In its powdered ~orm it has a higher
bulk density than in liquid form, and is considerably less
soluble in water than the liquid form, due to the reaction
; 10 occurring during the drying stage
For applying the pulverized ~ire retardant
composition to a fire unstable material it has been found
particularly effective to use sandblasting equipment, such
as a small portable sandblaster available in hardware stores.
The piece of equipment used in the testing to be described
developed a pressure of 100 pounds per square inch. The
powdered material is held in a reservoir and aspirated into
the high pressure air stream for application to the desired
surface. In operation the sandblaster was held at a
distance of approximately 3 to 4 inches away from the
surface of a foamed polystyrene or foamed polyurethane
board and the surface was sandblasted for the length of
time desired to apply the predetermined quantity of fire
retardant composition. In carrying out the present inven-
tion~ lt was found that the foamed polystyrene and foamed
polyurethane surfaces were penetrated as much as about
1/32 of an inch or greater depending on the manner of use
of the sandblaster.
The sandblasting with a fire retardant composi-
tion of a surface of a fire unstable material as described
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....
above was performed on the surface of foamed polystyrene.
A foamed cellular polystyrene surface made from cutting a
molded billet, having a density of about 1 pound per cubic
~ foot, exposes both open and closed cells, and has a cell ~-
- size generally averaging from about 3 to 8 mils in diameter.
Foam polystyrene is a generally closed cell structure,
with the exception of those cells that have been laid open
by the cutting operation. In appearance the board surface
has not materially changed due to the sandblasting treat-
ment. There is no significant rupture or crushing of the
polystyrene cellular structure due to the sandblasting. At
the same time the fire retardant composition has been
pressure in~ected into and through the polystyrene foam
cellular structure, possibly through the interstices
between the cell boundaries.
It has also been found that the sandblast treat-
ment seems to be more effective when the surface to which
it is to be applied is moistened prior to treatment. When
higher amounts of fire retardant powdered composition are
to ~e used, wetting the surface to be treated with water
facilitates the heavier sandblasting treatment, and assists
in retention of the increased amount of composition.
The advantages and utility o~ structures treated
as deecribed in accordance with the present invention are
dramatic and surprisingly remarkable. To establish this,
untreated and treated samples were given a rather severe
test, designated as a Modified Bureau of Mines Burn Through
Test. In this test, samples one foot square and of a
thickness as described are supported in a horizontal posi-
tion on a tripod. Each sample is supported two inches
above the top of a Fisher burner. The horizontal placement
of the sample and the substitution of a ~isher burner for ~,
a propane torch are the modifications adopted for this test
that differ from the Bu~eau of Mines ~urn Through Test.
The flame of the Fisher burner is ad~usted to a 41" height
with a 121l inner cone. A cellulosic tissue is placed on the
,,
top of the sample and the sample is supported horizontally ~-
on the tripod above the flame. Burn through time is
indicated by ignition of the tissue. Results of this
testing are illustrated in the following examples.
EXAMPLE I
A piece of foamed polystyrene board 12" by 12"
by 1" thick made from expandable polystyrene, sold under
the trademark DYLITE M-57, was subjected to the Modified
Bureau of Mines Burn Through Test and experienced a burn
through time of seven seconds with a weight loss of 50
of the sample.
A plurality of identical samples were treated by
the sandblasting method with a dry powder made from a resi-
nous ~lre retardant composition as previously described.
The samples were treated with the sandblast material on
top and bottom faces, some samples being given a treatment
amounting to 12~ grams per square foot of fire retardant
powdered composition, others at 25 grams per square foot
and still others at 50 grams per square foot. All of the
samples were faced on the two ma~or surfaces with 2 mil
alumlnum foil. No burn through of any of the samples was
experienced over a period of 30 minutes exposure. The
weight losses of the various samples ranged from about
3 14.8 to about 20.3~.
10.
$~
., ':
Another sample, untreated by the fire retardant
composition, and having a facing of .3 mil aluminum foil
on the surface facing downward, i.e., the flame side,
experienced a burn through of 15 seconds.
Thus, the sandblasting treatment with the fire
- retardant composition resulted in foam polystyrene samples
that were exposed to the test without burn through for a
greatly increased exposure of the relatively flammable
- material, polystyrene, from 7 or 5 seconds to over 1800
seconds.
EXAMPLE II
A sample of polystyrene foam board si~ilar to
those used in Example I but having a thickness of 2" was
sub~ected to the Burn Through Test and burn through was
e~perienced in 10 seconds.
An identical sample having a coating of the liquid
fire retardant composition formed by the admixture of resin
former and hardener in a ratio of 1 part resin former to
2 parts hardener applied to the top and bottom surface of
the polystyrene foam in the amount of 25 grams per square
foot, with a facing of .3 mils aluminum foil experienced
a burn through of 2 minutes and 13 seconds.
Samples of 2" thick polystyrene foam board exposed
to the sandblast treatment and faced with a 2 mil aluminum
foil coating on both surfaces did not experience any burn
through in 30 minutes. The weight loss of the samples
averaged from 12.9% to 23.5~.
In this Example II, it will be noted that the
sandblasted samples showed an increase in exposure time
from 133 seconds to over 1800 seconds, showing the marked
11 .
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~,. .
- advantages of sandblasting with a pul~erulent fire retardant
composition over the use of the same composition coated in
a liquid form.
EXAMPLE III
In this case samples of modified rigid polyurethane
board 12" by 12" by 2" thick were tested by the Burn Through
Test to compare the burn through exposure time of a control
sample having no sandblasting or other fire retardant treat-
ment in contrast with samples treated by sandblasting with
fire retardant composition in the amount of l22 grams per
s~uare foot and 25 grams per square foot, with and without
facings of aluminum foil 2 mils thick on both the top and
bottom surfaces. Table l shows the results of this testing
with comments regarding the amount of burning of the sample.
It will be noted that the untreated control sample exhibited ~
extreme burning of its outer surfaces whereas the samples ~ ;
treated by the ~andblast method showed no surface burning
whether or not they were faced with the aluminum foil.
TABLE 1
Surface Burn Through
Treatment Time 30
gm~/8q .ft. Facin~Minutes Test Comments
Control 0 12 minutes Extreme
o burning
of outer
surfaces
-
12.5 0 0 No
surface
burning
12.5 2 mil 0 No
Al foil surface
burning
25.0 0 0 No
surface
burning
25.0 2 mil 0 No
Al foil surface
burning
~ L4G~
:~ .
EXAMPLE IV
A sample 12" x 12" x 3/8" of p-i'ne board was
subjected to the Burn Through Test as a control, and after
four minutes exposure there was complete envelopment of the
sample by the flame. In other words, the sample became
completely on fire and was consumed. A similar sample
treated by sandblasting with a powdered fire retardant
composition at the rate of 25 grams per square foot on
both of its major surfaces was subjected to the Burn
~hrough Test. After exposure for 60 minutes there was no
burn through and no apparent effect on the samp~e.
EXAMPLE V
A piece of plywood of a size 12" x 12" x 1/4"
thick was submitted to the Burn Through Test as a control
and after exposure for about 2 min~tes there was complete
envelopment of the sample by fire.
A similar sample which had been sandblasted with
pulverulent fire retardant composition at a rate of 25 grams
per square foot on both of the ma~or surfaces was exposed
to the Burn Through Test and after 90 minutes there was no
bu~n through and no apparent effect on the sample.
A number of samples of structures sandblast
treated in accordance with the present invention were
sub~ected to a more severe test, known as the Underwriters'
Laboratories Tunnel Test. It is entitled "Test Method for
Fire Hazard Classification of Building Materials UL73".
The text was approved as ANSI A2.5-1970, April 14, 1970 by
Underwriters~ Laboratories, Inc. In this test, a sample is
supported and enclosed within a horizontally extending
duct or tunnel which is equipped with gas burners at one
13.
:
end and provided with controlled draft conditions all along
the length of the tunnel. Each test sample is 20" wide and
25' long. As an oversimplified summary, the test compares
the fire hazard classification of a given sample to
asbestos cement board (non-combustible) and having a
rating of 0 with select red oak flooring (combustible)
having a rating of lO0. Ratings are obtained for flame
spread, fuel contributed, and smoke density developed.
The sample is installed when the closed duct informs the
roof of the duct. The duct itself is 171" by 12" by 25'
long. The test is begun by lighting the gas burners and
allowing the sample to be exposed to the gas flame under
the specified test conditions for a period of 10 minutes.
Data is recorded at constant intervals throughout the test
procedure. Readings are obtained for the flame spread and
the smoke density. In the case of polymeric materials as
well as some other materials, the fuel contributed data is
considered not meaningful, and although recorded by
Underwriters' Laboratories in the test is omitted from
the data results presented in this description.
EXAMPLE VI
In this examp]e, the samples undergoing the
Tunnel Test are individually described and the test
results are tabulated in Table 2.
Sample l, a control sample, was a foam poly-
styrene board 2" thick, 20" wide and 25' long. It had a
denslty of about l.0 pounds per square foot and was made
from slabs cut from a molded billet of expandable poly-
styrene, sold under the trademark DYLITE M-57. This
sample was completely consumed during the test.
14.
~ ` ~
\
6~
Sample 2 was also a foam polystyrene board 2~
thick. It was coated with a resinous liquid mixture of
resin former and hardener in the ratio of 1 part resin
former to 2 parts hardener. The coating was deposited at
the rate of 25 grams per square foot. The sample was
faced on both sides with aluminum foil of .3 mils. In
this case, under the severe test conditions and even
though coated on both sides with a fire retardant composi-
tion, the board was 100~ consumed.
Sample 3 was a similar foam polystyrene board
1 3/4" thick. It had been sandblasted in accordance with
the present invention depositing a coating of 25 grams per
square foot on each side of the sample and the sample was
faced with 2 mil foil on both sides. The sample suffered -
a weight loss of only 13.1% after the normal 10 minute
length of test.
It will be noted that the present invention
provides a fire and flameproof structure capable of
prolonged resistance to flame and heat.
~ TABLE 2
Flame Weight
Sample Spread Smoke ~Loss
Number Ratin~ Developed ~ Dama~e
1 10 350 to over 100 Consumed
(Control) 500 Sample
melted
onto
tunnel
floor
-
2 _ 90.7 423 100) Consumed
3 12.8 21.1 13.1 Minimum
Dama~e
~0
15-
