Note: Descriptions are shown in the official language in which they were submitted.
83
BACKGROUND OF THE IN~ENTION
Fire unstable structures that are covered or coated
with fire-retardant and/or flameproof' coa-tings are subject to
deterioration due to ablation, disi.ntegration of the fire un-
stahle structure, and the like under continued and extreme
exposure to flame and heat. This detracts from the efflciency
and utility of the coating compositions and the final product
obtained. In order to achieve the desired ability to with-
stand exposure to heat and flame it is usually necessary to
provide a coating of the fire-retardant and/or flameproof
composition that has more than adequate or desired thickness
over the fire unstable structure. Obviously, this results in
increased cost of materials, which may render the use of such
structures uneconomical, and therefor not commercially
competitive or feasible.
When laminates of fire unstable materials have their
abutting faces coated with a fire-retardant or flameproof
coating, the prolonged exposure of heat and flame can,
especially if localized, create damage to portions of the
total structure, such as, warping or separation of the lami-
nates, and destroy or greatly reduce the e:Efectiveness of the
coat:l.ng. To solve this, lar~er amounts of the f':Lre-retardant
o:r :~'lamep:rooI' coatlng may be used. However, i..ncreasing the
amount of the coatin~ compos.ition will not always provide an
acleyuate so:Lut:l.orl. :c:r the f:ire unstab:Le ~structure or por-
tions of it are exposed to the direct action of the heat and
f:Lame, this may cause a separation of the coating composition
from the fire unstable structure and prevent it from providing
l.ts norma:L protective action. The exposure of the structure
to direct flame, as occurs in a fi.re~ may cause ablation of
the coating so that the fire unstable structure is directly
exposed to the destructive action of the heat and flame.
83
For these reasons, it is common practice in the
case of fire unstable structures which have been treated to
render them fire retardant or flameproof to provide
additional reinforcement for supplemental protection such
as fireproof layers of` glass fibers, metal, plaster, gypsum
board, cement, or other protec-tive materials so that the
structure as a whole can withstand the prolonged effects of
exposure to heat and/or open flame. r~his defeats the
purpose of using fire-retardant compositions as the major
protection for fire unstable structures.
It is an object of the present invention to
eliminate or at least reduce the amount of such supplemental
protection, depending on the structure to be protected and
the intensity of the exposure that it must withstand.
SUMMARY OF THE INVENTION
-
To improve the adequacy of resistance of a struc-
ture to prolonged exposure to fire and open flame, it has
been found that the best results may be obtained by the
provision of quantities of fire and flameproof composition
in interior portions of the fire unstable structure, in
addition to coating the surface of the fire unstable
s-tructure. The flre-retarclant or flameproo~ co~lposition may
be cl:L~posed :Ln hol]ows, cavitl.es or grooves in the f'lre
unsta'ble structu:re. This is in contrast to merely coating
the suYf'a(e of the fire unsta'ble structure. The resu:Lts
obtained are 'beneficially disp:roportionate to the increase
in the amount of f'iYe or flameproof composition employed.
Thls may be due to the f'act that the composition in the
cavities or grooves acts as a reservoir of material. In
addition, it provides increased adherence or interloc~ing
of the composition to the fire unsta'ble structure and
produces the desired end object. Thus the location and
3.
2483
disposition of the fire-retardant or ~lameproof compositions
will produce comrnercially acceptable flameproo~ structures
whether the fire unstable structure is in the form of a
coated single strata or is in a laminated form in
association with fire-retardant or flameproof compositions.
In-tumescent coating compositions are pre~erable, particu-
larly when the protected structure is a synthetic plastic
having a relati.vely high degree of flammability
D~TAILED DES~RIPTION 0~1 ~IE I~rVENTION
For the purposes of the present invention, the
fire-retardant or flameproof structures which are produced
comprise fire unstable material in a variety o~ forms and
arrangements and composed of a wide variety of materials
having associated therewith or coated thereon suitable fire-
retardant or flameproof compositions.
Fire unstable structures are materials unsuitable
for use where resistance and ability to withstand e~posure
to heat and flame are required. ~lassic types of fire
unstable materials are paper, wood, or other cellulosic
materials. Synthet-lc plastic materials, generally of
polymeric type, such as polyethylene, polyst-yrene, poly-
vinylchloride, pol~urethane, and the like, ~ther in solid
form OI' in the foYm o~ a ~oamed cellular product are a form
of fire unstable materlals that present problems in the
productiorl o~ ~lamepYoof structures since most of these
materials are of a materially greater degree o~ flammability
than the previously mentioned cellulosic fire unstable
materials. Glass or metal ~lbers comprising a large number
of filaments are also considered as fire unstable materials
since they are subject to severe deterioration in the
presence of prolonged heat and flame. Often the fibers
~L~Z29L~33
are coated with fire unstable substances to cause them to be
flufE'y and to inhibit compacting of the fibers when they are
used for insulation purposes. In this coated form such
materials are c~uite flammable and require treatment to pro-
vide a fire and flame-retardant structure.
Fire unstable structures~ as used herein3 include
structures in almost any physical arrangement in which they
may be disposed. They rnay be individual layers or may be in
the form of laminated stratas o~ fire unstable materials, or
may have the form of honeycomb structures produced from fire
unstable structures, as a strata, or in laminated form.
According to the invention, fire or flame-retardant
compositions may encompass a wide variety of chemical composi-
tions having the characteristics of imparting to a fire unstable
material the desired characteristics of resistance to heat and
flame. ~ large number of such compositions are known. For
example, fire-retardant compositions are available which when
applied to a synthetic polymeric material may ~Lave the effect
of rendering the material incapable of supporting combustion in
the absence of a flame being applied to the material. Many
such materials depend on a halogen content to provide these
E':I.re and flarne-retardant character:l.stics. Meta:Llic oxides are
arLother wel:L known f:lYe-retaYclant ingred:Lent. ~arious combLna-
tlons ol su.ch materlals are oE'ten conLblned E'or use.
.IE':Lt :Ls clesLYed to produce structures which woulcd
rnore neaYly clua:LiE'y as f':LameprooE' or E':lreproor, :it appears
highly desirable that the composition be an lntumescent
cornposltion. Such compositions under exposure to heat and/
or flame appea:r E'irst to soften and then to yield a volume
of' foarn which serves as an insulating barrier to protect the
fire unstable material. Upon prolonged exposure to flame and
heat, the foam carbonizes arld forms a stable insulating
33
char which continues to pro-tec-t the fire unstable ~aterials with remar]~-
able efficiency. A particularly preferred fire and flameproof composi-
tion is that obtained due to the reaction of phosphoric acid and a re-
ducing sugar, with the possible addition of a-t least one additional 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 flameproof compositions 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 3,82~,200. Also of interest
are the compositions taught in the Matalon U.S. patent No. 4,265,963.
For illustration of the present invention a particularly pre-
ferred fire and flameproof composition has been selected. Such a com-
position is that obtained from the reaction of a phosphoric acid and
a reducing sugar, such as, dextrose or commercial glucose, with the
possible addition of at least one supplemental foam producing agent.
m is type of composition can provide intumescence at significantly
lower temperatures such as below 100C. and thus provide earlier and
longer lasting protection.
In one specific embodiment, this composition comprises a mix-
ture of a resin forming substance (designated as RF71) and a hardener
substance (desic~nated as 175F).
The resin forming substance comprises the followiny approxi-
nk~te weights oE inyredients: 3% water, ~1% phosphoric acid ~85~
strength, it beiny understood that the strength of -the acid used is
dependent upon the water that r~y exist elsewhere in the formulation
and the s-trength of -the acid may thus be adiusted for compensation),
and dextrose 56%.
~ - 6 -
~2Z4~3
It is desirab:Le 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 li~e. Illustrative of a
resi.n former substance having such additives is that
identi.fied as RF77, compri.sing the following proportions by
weight: about 3~0 water, about 31.~ phosphoric acid (850~
strength), about L~3~o dextrose, about 8~o monoammonium phos-
phate, about 4~ oxalic acid, about lO~ urea, and about l~o
monoethanolamine.
The resin former substances may be prepared by
charging the water and phosphoric acid to a kettle and heating
the same to about 70 to 90C. The reducing sugar is added
and the 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 ke-ttle i.s closed, heated to about 120C for about lO
minutes, allowed to cool, and the contents discharged.
A suitable hardener or curing agent may comprise
the following ingredients by weight: water about L~, dex~
t:rose about 35/, urea abou.t 28/~ sodil1m hydrox1.de ( 3/o
st:ren~;th) about 3(~ :E'u.:r:f''ury:l. a.lcoho:L r~bol;Lt 5%~ and para~
:f;lo:rma:Ldehyde a'bout 25%. The :f'o:L:Low:ing procedure is~
L:l.lust:ra-tl.ve of' the method of' maki.rlg the harderl:ing agent.
The socLium hydroxide~ wate:r, :E'ur:f'ury:l. a:l.coho]., and para-
~o:rmal.dehyde are cha:rged to a reactor and rnlxed until
disso:l.ved at a ternperature of' approximate:Ly 90C. The
3 dextrose i.s acLded and mixed until a homogenous solution is
formed. The mixture is cooled or allowed to cool to about
L~oC, followed by addition of the urea and monoethanolamine.
Z483
This resu]ts in an exotherrnic 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. Alternatively, water and dextrose may be
charged to the kettle, heated and mixed until they are dis-
solved at about 90~. The urea is charged and stirred until
dissolved. The kettle is allowed to cool or is cooled by
heat trans~er to about 600C, at which time the sodium hydroxide,
furfuryl alcohol, and the paraformaldehyde are added. The
kettle is closed, heated to about 110C and stirred while
maintaining the temperature for about 25 minutes. As the
temperature 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 ratio may be varied with the approximate range of resin
former to hardener being about 3 to 1 to about 1 to ~,
depending upon the physical properties or'function desired
in the resultant composition. The end product is a thick,
v:Lscous :Llqu~ having~ a density oE' about 1-2 grams per cublc
cent:Lmeter. The composition has goocl adhes:ive properties
when used as a coat:l.ng or will securely adhere together
strata oL' E'ire unstabLe material
Th:Ls cornpos:ition may 'be used as a coat;:ing for a
fire unstable material. For example, it may 'be used to coat
the ma~or surf'aces of a foam polystyrene board made from
expanda'ble polystyrene~ comrnercially available as DYLITE
M57. The resin cornposition may be applied in any of
several well known ways, such as by spraying, painting,
8.
24~3
applying by a doctor roll or the like. The coating may be
appliecl at any desired level or thlckness, but the amount of
25 grams per square f'oot was selected as being adequate for
normal protection and within a range that would be economical
for commercial production.
In accordance with the present invention the foam
polystyrene board is provided with hollows or grooves in one
or more of its surfaces arranged to hold additional resin
composition. These hollows or grooves may be of any desired
con-figuration suitable for the purpose of interlocking or
securely adhering the composition, which does have good
adhesive qualities, to the board, and providing reservoirs
of the composition to assist in increasing the fire and heat
retardant characteristics of the coated board. The board may
have parallel rows of rectangular of u shaped slots, or the
cross section of the slots may be triangular, trapezoidal,
or the like. Random spaced hollowed out portions may also be
useful.
Samples of various structures made in accordance ~I
with the present invention were prepared for testing and com-
parison~ purposes.
One of the tests adopted to illustrate the fire
reslstance provided by the present invention is entitled a
Modif:l.ed Bureau oE' MLnes Burn Through Test. In thls test,
sa~p.Les one f'oot square and of a thlc~ness as clescribed are
supported :ln a horizontal posit:ion on a tripod. The sample is
su~ported ~ above the top oE' a ~isher bu:rner. The
horiYontal placement o:E' the sample and -the sub~,titution o:E' a
~lsher burner for a propane torch are the modifications
adopted for this test that dif'E'er from the Bureau of Mines
Burn Through Test. The flame of the ~isher burner is
adjusted to a 42" height and a 12" inner cone. ~ tissue is
~ ZZ~83
placed on top of the samp]e and the sample supported horizon-
tally on the tripod above the flame. Burn through time is
indicated by ignition of the tissue.
EX~MPLE I
A number of samples of f'oam polystyrene board were
prepared and subjected to -the Burn Through Test to illustrate
points of comparison and the efficac~ of the present invention~
as follows
Sample l, a control sample, comprised a piece of
polystyrene board 12~' x 12" x 2~ thick with no fire retardant
treating or and with no facing. It was made by wire cutting
from a molded billet of expandable polystyrene, sold under
the -trademark DYLITE ~57, and had a density of about 1.0
pounds per square -foot. The burn through time for this
sample was 8 seconds.
Sample 2 was a similar piece of foam polystyrene
boari 2~ thic~, untreated, but had a facing of aluminum foil
.3 mils thickness on the f'lame side only. This sample had
a burn through time of l5 seconds.
Sample 3 was a similar piece of foam polystyrene
board, except that it was coated with a fire retardant
composition compr:ising resin :~ormer and hardener i.n a ratio
of':l. to 2. The resin coating was appl:Led w:Lth a thlckness
of' 25 grarns per s~uare f'oot and the exposed f'ace ~bottom)
of' the~ samp:le was covered with an aluminum ~oil of .3 mils
th:Lckness. On exposure I;his ~larnp:Le had a burn through ti.me
of' 2 minutes and 1.3 seconcls. Th:Ls sample was heavil~ damaged
and a sizable hole was burned through the sample.
Sample 4 was a similar piece of' foam polystyrene
3 boarrl 2~ thick but provided with a series of rectangular
slots in parallel rows. The rows were l" on centers and the
slots were 21' deep and l/L~" wide. The slots were provided
10 .
~ 12~4~33
on both major surf'aces o:f' the sample and were coated with
the fire retardan-t composi-tion descr~ibed in connection with
Sample 3, the coating being app~Lied at a thickness of 25
grams per square :f'oot. The surfaces of the slots were
coated but the s:Lots were not full of fire retardant
composi-tion. An aluminum :f'oil facing of .3 mils thick was
applied to bokh faces of the sample. Upon test there was
no burn through during the test time o:E` 5 minutes. Only
rnoderate damage with shrinkage or melting occurred. In
additionaL samples no burn through cccurred with 60 minutes
exposure.
Sample 5 was a sample similar to Sample ~ except
that in addition to the surface coating the slots -were
filled with the fire retardant resinous composition. There
was no burn through after testing for 30 minutes. Only
limited damage had occurred to the sarnple.
Sample 6 was similar to Sample 5 except that the
slots were filled with the same fire retardant composition
which had been made into a powdered form. The powdered
forrn was made by drying the liquid resinous composition
at elevated temperatures (approximately 800~) for an extended
time period such as 72 to 90 hours and the resultant
cake was puLverized and used to E'i.l.L the s:l.otf a:f'ter the
s~r~ace coatlng O:r the :L:i.qu:Ld f'ire retardant composltlon
hacl been ~pp:Liecl. ~t the end of 30 minutes exposure
to the :E'lame there ha(l been no burn throug~h in th:is
sarrlp:Le.
To f'urther illustrate the present invention a
more severe test oE` EIoam polystyrene board coated with
the same fire ancl flame :retardant composition wa,s conducted.
~12Z~33
m is test is described as the Tunnel Test and is performed
by the Underwri-ters I.aboratories, Inc. It is entitled
~Test Method ~or Fire Hazard Classi~ication of Building
~aterials UL73." The test was approved as ANSl A2.5-1970,
April 1~, 1970. In this test a sample is supported and
enclosed within a horizontally extending duct or tunnel
which is equipped with gas burners at one end and provided
w-L-th controlled dra~t conditions all along the length o~
the tunnel. The test sample is 20" wide and 25 ~eet long.
As an o~ersimplified summary, the test compares the ~ire
hazard classi~ication of a gi~en sample to asbestos cement
board (non-combustible) and having a rating o~ 0 and with
select grade red oak flooring (combustible) having a rating
of 100. Ratings are obtained ~or ~lame spread, fuel
contributed, ana smoke density de~eloped. me sample is
installed in the closed duct and ~orms the roof of the
duct. The duct itsel~ is 17z'' x 12" x 25'. The test is
begun by lighting the gas burners and allowing -the sample
to be exposed to the gas ~lame under the speci~ied test
conditions ~or a period of 10 minutes. Data is recorded
at constant intervals throughout the test procedure.
~ead:Lngs are obtained ~or the ~lame spread and the smoke
denslty. In the case o~ polymeric materials as well as
some other materials, the ~uel contributed data is
considered not meanlng~ul, and although recorded by
Underwriters Laboratorles in the tests, is omitted ~rom
the data results presented in -this description
EXAMP~3 II
~ series o~ 5 Samples were prepared and exposed
to the Tur~el Test, with the results shown in the following
Table 1. The per~ormance o~ Sample 5 is illustrative
Z~3
s'~- ~1~ ~ ~D
O 1~ ~d o 5~ rd . ~ c~
O d ~ ~3
~, ~> ', ~ ~o ~d ~,
~ O,Q ~ ~,,Q ~ ~ ~1 ~3
5 1 ~ rd5~ 5 ~ ~ 1::~1 ~ ~ O
~Q O O ~, O O ~ ~.~ ~
I~ C) ~13 c ) 113 ~ ~ ~ ~H
S ~ ~ rd I--I ~1 ~ ~1 1)
C~ ~1 (1~ ~ I ~1 a) rC~I ~rl ~5 rC~I
O ~ ~ O ;> .~' O ~ 'd
~1 0 -~ ~1 0t~ O ,C_~
o o a) ~ o a~ ~1 ~ O
c~E~ ~ ~t~ ~ H ~ ~i ~1 ~ C~i a)
-1~ - -- _,,. rd
C'' ~ ~ ~ ~ ~ ~ O
~0 $ $ C~ ~ ~ O ~
~ t--1 r~ r I _ :: -1~ ~
~3 ~d
rd rl rl
tD ~, g F 1 ~H
~0 rl L~ ~ O r O r~ ~O ~ t!)
n O r~ ~ ~ Lr~ c ;~:
r~ r' tQ
FLI I _ _ _ _ _ C r
tl3 O LO I-- tr3
td tD r-l CU O O 1~
F~ tQ, r O , . rl (U
tQ h \ (U rd
l)ra rd CU rd ~ ~,
o ~~1 ~ s~ ~ rd
r-l rl~ID rd rn rd td O
V~ (U ~ ~ O rH tU
.t) S~ Ll~ ~, O t~ Q r )
O (\.1 0 rl ~ td
. ,~, ,_ ~, rn s: ~ rl ~H
~d rd rd rd rl ~d rl O rn h
~1 c I e I . ~1 ~U ~ r~ ~ rn -~ Q)
(d ~ td ~ td u td ~ra rl Pl (U -1~ C~l rn
O tL) O tD O raO O td tU O ~U h O
FCI 1~ F4 -~ FLI \ ~L) t ~t lt) ,0 ~H ~.¦
td rd rard c) rd ~, rd
s lt~d ,rr'td ~r i td ~b ~ H rl tL) (U rd! ~d
Fr-l ~1-'~ dl F'l O FO \ ~rl ~ ! C) '\ (U t~ ~, tt3
~, (U (U ~U tU ~ tU O O ~ O
r-l~ ¦ r~ o C¦ '~ r~ O rl ~11 -l~ rl C)
~1(U ~zi ~U ~-i ~U rt~ tl) ~r-l ~ rd ~1 F:l
C~~1 ~1 $-1 tU ~1,. t~ 1 ~¦ ,C~ c~ r~
~a h ~, ~,~fll~ ~n t~ ~d -1~ 0 ~a rl O
~U1~ ~1~ 1~ tt3 1~ (U rd O ta rl td ta
(Uta rd~a rd r~l tn rd t~) rl ,o ~ rl ~ tV ',~
rlO ~3O ~ O Ar~ O O ~d ~t-l O (U ~t-l ta C' ta ta
F~F4 0P-l O p~ rlP-l t~ Cl ,4 -~ tD r-l tU r-l td 0
~1 ~ ta -~ 3 ~ ~ ~I ri r I C) -1~ ;~
V~ _ ~ _ ~ ~ ~ -- Cj O O ~ O tr3 rl ~ ~d O L~
tU
r~ r~ r~
_ ., __ _ _ ,..... __ _ ra ~ ~a
tl) tr3 tD
* F~; ~n
. * * *
O r~ C~J t.~) ~ 1~ * *
~i I . .. _~ _ . , ..... .. _~_
33
that the present invention provides a structure that has
excellent fire res;stance.
EXAMPLE III
~Cn this case, samples o~ wood 12 inches~square and
3/8 inches thick were su'bjected to the Burn Through Test.
Sample 1 was an untreated control samp]e. While
there was no burn through, the complete sample was enveloped
by flame with lateral ~lame propagation.
Sample 2 was painted with a commercially available
intumescent paint, sold as Ball Chemical G-3232. The coating
was applied at a rate o~ 25 grams per square ~oot coverage.
After 34.5 minute,s, the sample was enveloped with :~lame, with
lateral ~lame propagations.
Sample 3 was slotted with slots 1/16 inch wide,
spaced on 1 inch centers, and 1/8 inch deep on both of its
major sur~aces. The sample was then coated with the same
intumescent paint as Sample 2. The coating was applied at
the rate o~ 25 grams per square foot to the slot sur~aces as
well as the board sur~ace, so that due -to the increased
sur~ace area created by the slots the overall coating was
thinner. After 90 minutes exposure, there was no burn
through, no lateral ~lame propagation ~nd no ~nvelopment by
the ~]ame.
FXAMPI,I~ :C'V
Samples oi' po:Lyuretharle i''oam board 12 inches ~square
ancl 1 inch th:ic'k were subjectecL to the'Burn Through Test.
TLle po:l.yurethane ~oam is commerc:la:l:l.y avaiLa'ble i~rom Dacar
Chemica:L ProcLucts Co. under the grade name o~` 22G.
Sample 1 was an untreated control sampLe and burn
throllgh occurred in about 6 minutes.
Sample 2 had 'both major sur~aces painted with a
commercially available intumescent pain~ (Ball Chemical
1~.
~L3L2Z~33
Cornpany, G3232) at a level of 25 grarns per square foot.
Burn through was experienced after 19 minutes.
Sample 3 was slotted on both its major surfaces
with slots :L/8 inch wide, 1~4 inch deep, with the slots
spaced on 1 inch centers The sample was coated with the
same intumescent paint as Sample 2 at a level of 25 grams
per square foot with the slot surfaces coated as well as
the board surfaces. Burn through did not occur until
exposure fox 4r7 minutes.
3o
