Note: Descriptions are shown in the official language in which they were submitted.
F.N. 913,804
3Z91
INTUMESCABLE FIRE-RETARDANT PRODUCTS
Despite many efforts over the years, there has
never been a fire-retardant asphalt roofing material having
the same widespread acceptance as standard, non-fire-
retardant versions.
The prior efforts have taken several directions:
use of mineral fibers as a filler in the asphalt layers or
as a replacement fiber in the roofing felt for the purposes
of reducing combustible material and limiting flow and ex-
posure of asphalt during a fire (see Fasold et al, U.S. Pat.
10 2,555,401; Tomlinson et al, U.S. Pat. 3,332,830; and
Schuetz, U.S. Pat. 3,369,956); inclusion of chemical fire-
retardant agents in the roofing (see Tomlinson and Bierly,
U.S. Pat. 2,667,425); and/or use of extra or heavier layers
of roofing granules. Some of these approaches have pro-
duced commercial roofing sufficiently fire-retardant to
be rated Class A by Underwriter's Laboratory (in contrast
to the Class C rating of standard asphalt roofing); but
even those approaches are not the answer the art is seeking,
since they either greatly increase the cost of roofing,
require special manufacturing equipment or processes, or
provide only marginal fire protection. As an example of
the latter deficiency, some commercial roofing materials
with glass fiber felts pass Underwriter's Laboratory's
"burning brand" test on 3/4-inch-thick (2-centimeters-
thick) roof decks, but they will not pass the test on 3/8-
inch-thick (l-centimeter-thick) roof decks, which are now
approved for use in construction.
A different approach tried by several prior
111~29~1
-- 2
workers is to introduce a layer of intumescable particles
into the roofing, which, as stated in Donegan, U.S. Pat.
2,782,129, is intended to expand in the presence of a fire
to form "a fire resistant support or rigid sponge which
absorbs the asphalt, preventing flow and providing an ef-
fective fire barrier to the underlying roof." Donegan
suggests use of unexpanded vermiculite as the intumescable
material, disposed as a particulate layer between two layers
of asbestos-filled asphalt. Bick et al, U.S. Pat.
3,216,883, also suggests the use of vermiculite, either
unexpanded or partially expanded, in "built-up" roofing
(formed in place on a roof). Hinds, U.S. Pat. 3,365,322
(1968), cites disadvantages of vermiculite (it is expensive
and, because of its low weight, is difficult to incorporate
into roofing in uniform amounts), and suggests replacing
the vermiculite with mineral granules that carry an intu-
mescable coa~ing of sodium silicate and borax.
None of these efforts with intumescable roofing
have been as effective as some of the other described ap-
proaches. Roofing material as taught in Hinds was com-
merically sold for awhile, but without apparent success.
Very little intumescence was provided by the coated
granules, and fire-resistance appeared to depend on
presence of asbestos fibers as a filler in the asphalt;
such a filled asphalt is difficult to apply by standard
coating equipment, is costly, and has toxicity and other
disad-~antages. In addition, the coated mineral granules
were flood-coated into the roofing material at weights of
100 to 125 kilograms per 10-by-10-meter section of applied
*We use the word "intumescable" herein to describe material which
is capable of intumescing.
l~o{)t`illg. addillg to cc)st a~ eigllt of thc roofing. /~l-;o. the coatirlg on tllc
grailUleS W.IS SO~ ` ill W.ltel`, alld ill -the ne,lrly ~onti.nuou-; -llood-coated lay-
er ~-as esl~eci.ll~y suscel)til)le to lc;lcl~ing and conse(luent loss of intumesc-
abillty.
Vermiculi.tc as suggcsted by ~)onegan and Bick also offers only low-
volume intumescence, and vermiculite will not intumesce Imtil a fire has pro-
gressed sufficiently to create high tempcrature.
In brief, nothing in the known prior work with intumescable roofing
suggests that intumescence could be the basis :Eor an effective and economical
fire-retardant asphalt roofing.
The present inventiorl provides fire-retardant, intumescable roofing
material comprising in parallel layers, a roofing :Eelt; at least one asphalt
coating disposed above the felt; a layer of roofing granules partially em-
bedded in the top asphalt coating in the roofing material; and a layer of
inturnescable particles disposed within the roofing material; said particles
having hydrated soluble silicate glass at least at the core of the particles,
and said core being at least 25 micrometers in diameter.
In another aspect the invention provides moisture-resistant parti-
cles that intumesce in ].arge volume when exposed to heat comprising a core
particle that comprises a hydrated solublc si.l.icate glass, and a protective
moisture-resistant coating surrounding the core particle; the protective
coating including an ingredi.ent that is ioni~ed in the presence of water to
provide metal cation capable of reacting with the silicate ion of the core
partic~e to form a reaction product that is less water-soluble than the sili-
cate glass of the particle, thereby l:i.miting action of water on the core
particle.
The present invention provides a new roofing material, which is of
the intumescable type, but whic}l offers an economic and effective fire-retard-
ancy that promises widespread utility for the roofing material. ln basic
construction, the new roofing material can be like previous intumescable roof-
ing materials, i.e. it generally comprises a roofing felt; at least one
asphalt coating above the felt; a layer of roofing granules partially embedded
in tllc tol- asl)lnllt COatillg 011 the roofing fclt; and a layer of intumescable
-artieles d:isl)osed withill thc roof`ing material so as to intumesce when the
roofing matericll is exposcd to f:ire. Also, the intumescable material in the
new roofing material i.s hydr.lted soluble silicate, which, as indicated above,
has previously been uscd in fire-retardant roofing as a coating on mineral
granules.
Notwithstanding such similarities, roofing ma-
:~ - 3a -
~ 4 --
terial of the invention is effective where prior-art intu-
mescable roofing has not been. A first difEerenee over
prior-art int~ne~cable roofing is that the intumescable
particles in roofing material of the invention comprise
hydrated soluble silicate at thei.r core, rather than in a
peripheral coating as in the prior-art coated mineral
granules. Despite previous work in the art with hydrated
soluble silicate, there has never, so far as known, been a
commercially available hydrated soluble silicate in par-
tieulate form such as used in roofing material of theinvention, nc)r }l;lS SllCh partl.culate hydratecl solubl.e sili-
cate been !;ug(leste(~ s an :intumesc.-lble fire-retardant
additive. We have succeeded in providing a commercially
practicable method of manufacture of such particles (as
will be subsequently described), and have found that when
the particles are included as a layer in roofing material,
they provide a fire-retardancy far superior to that pro-
vided in any previous intumescable roofing.
Anothe:r rcas()n E(3r the .;uper;.or .i.ntumescellce of
roo:E.in~;J materic~ r the illvf~ ior~ i.s tll~ [~)rutocl:ion c3i.ven
the hydrated sc)lublc sil:icate g:lclss part.icles agai.nst
attack by mc)isture. Moisture wi.:Ll leach away alkali metal
oxide from solubl.e s-i.l:icate particles and take away their
ability tc) intumesce. Sorne protecti.(.)n against such attack
can be providecl with extra-heclvy layers of asphalt, extra-
hiyh coneentratiolls of i.ntumescable particles, or construc-
tions in which the particles are sandwiched between imper-
meable films. The e.Efectiveness of these procedures is
assisted by the concentrated nature of the intumescable
~articles u~ed in the present invention; sinte each in(li-
vidual intumescable pclrtic1e in roofing material, of the
invention in~ume~,ces in large volurne, fewer particies need
he used and the par-ticles can be better surrounded and
isolated by moisture-resistant structure.
~ owever, the present invention achieves even
more effective moisture-protection with a novel hydr~ted
soluble silicate particle that carries a unique protective
coating. This protective coating includes an ingredient
that is ionized in the presence of water to provide metal
cation capable of reacting with the silicate ion of the
core particle. The reaction between the metal and silicate
ions forms a reaction product that is less water-soll1ble
than the core particle, whereby a protective layer is
formed around the particle. The protective coating i_
regarded as having a self~healing function, in that any
openings which develop in the protective layer tend to be
sealed, thereby limiting action of water on the core par-
ticles and maintaining the intumescent character of the
particles.
The protective coating is also a key to conven-
ient manufacture of the intumescable particles. Prior to
the present invention, he art might have considered two
general kinds of method for manuacturing hydrated soluble
silicate particles: drying of commercially available
solutions of soluble silicates to a solid of the needed
water content; and hydration of commercially available
anhydrous soluble silicate material. Both methods present
diff~culties: the drying operation of the first method
fo~ms (~ fil~ r.~t~ s ev~ )r.l~.Lon :-in(l ~3~ tly l~n~lt~ L,
t}~e pr~ L~ t~ r lti~ t~ ) in tlle si~c~,nfl m~.~th~"l
tends t~ for.n acJ~Jlolllerat~(3 c~ ss-l:i.ke material tha~ is
di.fficult to co~minute to needed si~es. Such difficulties
have now been overcc)me with the discovery that anhydrous
soluble silicate material r crushed ~o a desired particle
size, can be coated with the described. protective coating
and then hydrated to the desired moisture content under the
heat and pressure of an autoclave, producing ready-to-use
non-agglomerated particles.
In a different manufacturing method, anhydrous
soluble silicate fines can be agglomerated to desired
particle sizes with liquid soluble silicate, coated with
the described protective coating, and heated to form in-
tumescable hydrated soluble silicate particles (the heatingoperation is understood as distributing water present in
the liquid soluble silicate throughout the particle to
make the particle intumescable~. Particles formed from
agglomerated fines have the advantage that during intu-
mescence they tend to form a multicellular product, whichhas greater crush strength.
A less desirable alternative for manufacturing
particles useful in the invention is to hydrate uncoated
anhydrous soluble silicate particles in a bed of inert
particles such as clay~ A protective coating of the in-
vention can be applied to particles that have already been
hydrated, as well as to anhydrous particles.
Because of the moisture-resistant nature of
coated particles of the invention, together with their
il~8291
- 7 -
small si2e and high degree of intumescence, they can be
conveniently and economically included in asphalt roofing
materials without significant change of standard manufac-
turing procedures. A rather low amount of the particles
can be applied per unit area of the roofing material, and
the particles can be cascaded directly onto and partially
embedded in asphalt coatings already incorporated into
standard asphalt roofing materials.
The amount of intumescence exhibited by roofing
- 10 material of the invention can be controlled through se-
!, lection of the amount of intumescable particles. A rather
low amount of particles gives the roofing material a large
volume of intumescence and a high degree of fire-retardancy.
Roofing material of the invention passes Underwriter's
Laboratory's "burning brand" test on either 2-centimeter
or l-centimeter-thick decks, and in fact, will pass a more
stringent laboratory test in which a Bunsen burner is
trained continuously for 30 minutes on a 15-by-15-centimeter
sample of applied roofing material (i.e. overlapped in the
manner that roofing shingles are applied to a roof deck),
but laid over a piece of unsaturated organic felt paper
rather than a roof deck. In neither test does fire pene-
trate through the test sample.
Further, extended tests of roofing material of
the invention at restricted test sites as well as acceler-
ated aging tests indicate that the described fire-
retardancy is retained over a useful lifetime for roofing.
- The total combination of properties is a significant
advance in the roofing material art, and appears to offer
~S~:~
-- 8
~r the ~ir~t: ;ime t~lle ~()tential F(~r as~)h.llt--satl1x-atfd,
felt~base-l r~ Lin(7 ll~ateriaL to be offer~?d in a form that
is both highly fire-retarc~ant and economical.
Besldes use in roofing material, coated particles
of the invention can be included in a wide range of ma-
terials -- ranging from solid foams to liquid coating
compositionc. The moisture-resistanc2 and highly intu
mescent character of the particles make their use conven-
ient and effective, all at moderate cost.
Some additional prior art background for the
present invention can be summarized as follows:
According to Vail~ J. G., Solub_e Silicates
~1952, Reinhold Publishing Company), Volume 2, page 481,
the United States patent literature on intumescence of
soluble silicates begins in 1883 with Kelly, U.S. Pat.
283,7890 which teaches a cellular mass of expanded silicate
as a thermal insulation for fireproo' saEes. Arthur, U.S.
Pat. 1,041,565, issued in 1912, teaches a particulate
soluble silicate such as sodium or potassium silicate which
may be intumesced to form expanded or cellular particulate
material useful as thermal insulation.
The patent literature very early discusses ways
to insolubilize the soluble silicate glasses. Gesner, U.S.
Pat. 419,657, issued in 1890, teaches the treatment of
cellular silicate glasses with chemical agents such as
calcium chloride; acids such as sulfuric or hydrochloric
acid; and soluble oxides and salts of metals other than
alkaline metals, including such oxides as barium or
strontium hydroxide and such salts as calcium or barium
111~3Z91
g
nitrite. Gesner also teaches that the cellular material
may be made impervious to water by coating it with paraffin,
drying oils, asphalt, rubber and fused or dissolYed insol-
uble metallic soaps or oleates or stearates, and solutions
of resins or gums.
The ~inds patent mentioned above suggests that
the intumescable coated granules may be coated with asphalt
~` emulsions, oils, silicones, or latex emulsions to prevent
water-absorption by the granules.
10Another example of prior teachings as to use of
- intumescable silicate materials for fire retardancy is
Vail's report (page 483) that wooden beams have been coated
with heavy silicate solutions to reduce the hazard of fire.
In a different kind of teaching, Cohen, U.S. Pat.
15917,543 suggests the use of sodium silicate in roofing
material as an adhesive to bond a sheet of asbestos to a
sheet of organic fibers and form a fire and waterproof
material. However, there is no suggestion that the sodium
silicate be particulate or intumescable as in the case in
our new roofing material.
Insofar as known, nothing in the prior art
teaches asphalt-saturated, felt-based roofing material
containing a layer of hydrated soluble silicate particles
for fire-retardancy. Nor does the kno~n prior art teach
particulate silicate glasses, not yet expanded but still
intumescable, and coated with a coating that protects and
increases the expansibility of the particles during intu-
mescence and makes possible their convenient manufacture.
Figure 1 is a sectional view through an illus-
~ 10 --
txlti~!c lo(-~Li~ tt~Li~l 10 c-f the in~ r!tio~. Th~ roofir
ma~erial 10 cal~ L~ nade as follows. A roofing felt paper
11 is satulated, and coated on its top surface -to form a
la~er 12, with an asphaltic composition. Int~mescable
soluble silicate par-ticles 13 are cascaded onto the coated
felt where they become partially er~edded in the layer 12.
A layer 14 of asphaltic compositlon is then applied over
the particles of the invention; and roofing granules 15 are
cascaded onto the layer 14, where they become partially
em'oedded. A back coating 16 of asphaltic composition is
applied to the bottom of the felt paper 11, and a dust
coating 17 of mica or the like is applied to make the back
side of the material tack-free.
Figure 2 is a sectional view through a repre-
sentative intumescent particle 19 of the invention, whichcomprises a core particle 20 and a protective coating 21
surrounding the particle.
Figure 3 is a graph showing the amount of intu-
mescence versus water content for coated particles of the
~0 invention a,nd particles that are the same except for being
uncoatedO
Sodium silicates are preferred as the soluble
silicate glass in int~mescable particles of the invention
because of their lower costs, but silicates formed from
other alkali metals may also be used, including, for
example, those formed from potassium and lithium. The
silicates used may also have different ratios of silica
to alkali-metal oxide, but silicates having a ratio above
about 2 to 1 are preferred because they are less water-
so1uble Lha~l t:hos.? ~)~ lesser ratios.
The ln~llm~scabl.e p~rticles can range widel~ insize, though as shown in Tab:Le I, volume of intumescence
varies with the si7.e of the particles. P~s the particle size
Table I
Vol~e Intumescence of Sodium Silicate Particles
~SiO2; Na2O ratio of 3.22, and hydrated with 13
percent water)
Particle Si~e Volume to which
two-milliliter
10 ~ A~ r:j~ d.a-~= Y sample expands
(mlcrometers)~mlcrometers) (mllliliters)
2~00 - 2380 2~00 200
840 - 200~ 1400 200
590 - 840 710 175
15~20 - 59~ 50~ 175
2.97 - 420 350 160
176 - 297 230 125
1~5 - 176 150 110
~8 - ~27 105 ~0
2070 ~ 88 80 80
62 - 74 67 7~
44 - 62 53 50
2~ 25
~ 20 14 3
25~ 10 6 3
reported in the ta~le rises above m~nimal values, the volume
of intumescence increases significantly; the reported par-
ticles that average approximately 25 micrometers in si~e
intumesce over ten-fold t and the reported particles that
average approximately 100 micrometers, intumesce over forty-
~118Z91
- 12 -
fold. Particles of the invention should intumesce at least
four-fold and preferably at least forty-fold for most uses
as a fire-retardant additive. For the highest volume-
percent of intumescence, particles above about 300 micro-
meters in diameter are preferably used (in giving valuesfor maximum and minimum diameter, the values stated apply
for only 90 volume-percent of the particles, since after a
screening operation some of the remaining particles are
outside the screen sizes). For the most satisfactory use
in roofing material the particles should average less than
2 millimeters, and preferably less than 1 millimeter in
diameter. However, particles up to several centimeters in
diameter can also be used for special purposes.
The particles will intumesce in different amounts
depending on the amount of water present. Curve 1 in
Figure 3 is a graph of the intumescence at a typical
actuating temperature range ti.e., about 200 to 300C) for
coated sodium silicate particles generally of the type
described in Example 1 below, but with varying water can-
tent, and Curve 2 is a similar curve for uncoated particles.(The curves show the vollIme in milliliters to which a 2-
milliliter sample expands.)
To obtain a useful amount of intumescence the
soluble silicate should generally include at least 3 per-
cent, and preferably at least 10 percent, water. Peakintumescence for the illustrated sodium silicate occurs
at around 15 percent water. With greater amounts of water
beyond 15 percent, intumescence declines, though it will
occur for contents of water up to, and in fact beyond, the
- l3
~ t (~b~ t ~0 ~ ct~-l! at ~I?~ t~ s~ blf s~ t~
d:Ls~o~ves in w~lte-r~ Irypically~ no slgnificant benefit~ are
obtained by includi~ ore than ~0 percen~ wa~er.
Whereas the co~e particle in coated particles of
-the invention can be quite soluble in water, the protective
coating comprises ingredients that have a low solubility,
preferably a room-temperature solubility in water of less
than 0.2 gram/cubic centimeter. However, even with this
low solubility, there is sufficient dissociation to provide
metal cations for self-healing reaction with silicate ion
of the core particle.
The preferred protective coating, providing the
longPst-lasting and most thorough moisture protection, com-
prises a metal salt of a long-chain fatty acid. Stearic
acid is the pr~ferred long-chain fatty acid but others,
such as oleic or palmitic acid, can also be used. Also,
although calcium is a preferred metal, other metals, such
as the alkaline-earth metals barium and magnesium, and
aluminum and zinc, can be used.
In preferred coatings as just described, the best
water-stability has been obtained when the coating includes
metal, in an ionizable compound, in excess of that needed
for stoichiometric association with the anion of the long-
chain fatty acid. The excess metal of such metal-cation-
rich coatings can be provided, for example, as the hydrox-
ide, carbonate r chloride, or fluoride of the metal. Typi-
cally the excess-meta1~providing ionizable compound, which
is desirably present in an amount accounting for at least
one-half volume-percent of the protective coating, is more
~olubl~ lhall t'le metai salt ~i- th~ k~n-J~chaln fatt~ a~
~ the~ wat~}-inso1uble ~)mponellts can be inc1uderl
in pxotecti~re coatings of the invention, either as a sup-
plement or as a substltute for the metal salt of a long-
chain fatty acid. Eor example, organic polymeric films suchas polyethylene, polypropylene, wax, epoxy resins, Gr
urethane resins may be used. Arl ionizable ingredient pro-
viding metal catlon for reaction with silicate ion of the
core particle should be included in such coatings to obtain
the best water-stability.
A further ingredient preferably included in pro-
tective coatings on particles of the invention is silicone
water-repellent agents. A large list of such agents are
known to repel moisture from a surface on which they are
applied. Use of such a repellent coating has been found
to add significantly to the moisture-resistance provided by
the protective coating.
The long-term stability of coated particles of
the invention has been demonstrated both in extended aging
tests on test decks, and by accelerated laboratory tests in
which the particles are totally immersed in water and their
intumescability measured at various intervals. In the
latter kind of testing, for example, sodium silicate par-
ticles as described in Example 1 below, after having been
immersed in water for 40 days, still exhibit useful intu-
mescence upon heating. ~en sodium silicate particles the
s~me as those of Example 1, but without any protective
coating, are subjected to the same test, they will not
intumesce at all after 1 - 3 days of exposure. Also, when
L
- 15 -
~odiuln si.llc~lt.~ L~ ; t~he s~:lme as t}lose of },xaln~1e l
~ce~t coated wit}-l c.lLci.um ~tea~ate in which the calcium
~nd steaL~ate are i.ll stoic~lic)metI-:ic proporti.ons are su~jected
to the same testing, intumescence of the particles declines
af~er 6 to ~ days to the level exhibited by par-ticl.es of
Example 1 after 4Q days of exposure,
The protective coating on coated particles can
be appli.ed by known coating procedures. For example, the
core particles can be mixed with the coating material while
the latter is in a liquid fo.rm, e.g. by melting or dis
solving. The coating is then allowed to harden to a sub-
stantially continuous film, as by cooling, drying or re-
acting, In one useful coating operation, the core par-
ticles are first coated with a liquefiable portion of the
coating -- e.g. melted stearic acid; oleic acid, which is
liquid at room temperature; molten polymer such as poly-
ethylene; or a liquid uncured epoxy resin-hardener compo~
sition. Then, before the coating has cooled or hardened,
other ingredients such as the metal-cation-supplying ingre-
dient are added, as by mixing a powdered form of that in-
gredient and the coated core particles. For example,
powdered ca:Lcium hydroxide is conveniently mixed with par-
ticles that have been first coated with molten stearic
acid. After such mixing, the calcium hydroxide becomes
partially embedded in the stearic acid coating; the calcium
reacts with the stearic acid to form nearly insoluble cal-
cium stearate; and any unreacted calcium hydroxide remains
present in the layer to provide excess calcium cation for
a self-healing function.
~118Z9~
- 16 -
Alternatively to the above procedure, metal-
cation-supplying ingredient such as calcium hydroxide can
be incorporated into other ingredients of the protective
coating, such as stearic acid, prior to coating of the core
particles. In the case of calcium hydroxide and stearic
acid, calcium steaxate is produced during such a premixing
operation and must be melted before the core particles can
be coated.
As shown in Figure 1, the intumescable particles
in roofing material of the invention need not be closely
packed, since upon expansion they occupy a much larger
volume. Coated particles of the invention can generally be
included in an amount of no more than about 50, and more
commonly are included in an amount of no more than about
25, kilograms per 10-by-10-meter section of applied roofing
material. At least 5, and preferably at least 10, kilograms
of particles are generally used per 10-by-10-meter section~
Though generally embedded in an asphalt coating on the roof-
ing felt, the layer of particles may be disposed elsewhere
in the roofing material, e.g., in the felt itself.
Besides utility in roofing material, coated par-
ticles of the invention are also useful as fire-retardant
additives in a variety of polymeric articles, including
risid or flexible foams, molded or sheet articles, extruded
or cast films, elastomeric articles, etc. Such articles
- may be made from polyurethanes, epoxy resins, polyesters,
etc. Also, the particles can be introduced into various
coating materials to form fire-retardant coatings; such
coating materials generally comprise a liquid vehicle that
17 -
hardens to a solid coating upon exposure as a thin coating
in predetermined environments. Also, the particles can be
added in a loose mixture with other powdered materials for
fire-retardant purposes. In addition to protecting a sub-
strate against fire, particles of the invention can performa heat insulating function; for example, a coating con-
taining a layer of particles of the invention can be used
to protect steel beams from reaching temperatures during a
fire that would damage the beams and cause them to sag.
Also, particles of the invention can be intumesced and
used for a variety of purposes; for example, particles can
be intumesced at a building site and introduced into the
walls or other structure of the building as thermal insu-
lation.
The invention will be further illustrated by the
following examples.
Example 1
- One-hundred parts of anhydrous sodium silicate
glass particles having a SiO2:Na2O ratio of 3.22 and a
20 range in size from about 300 to 840 micrometers were heated
in an oven to 250F (120C). After reaching that tempera-
ture, the particles were dumped into a cement mixer and 2
parts of powdered stearic acid added, whereupon the stearic
acid melted and became coated on the particles. After the
mixing had continued for about 10 minutes, 2 parts of
calcium hydroxide was added and the mixing continued for
B an additional 10 minutes. Next, 1 part of a silicone water
- repellent ~DC-772 sodium siliconate from Dow Corning~ was
added and mixed in for 10 minutes.
1~8Z9l
- 18 -
The coated particles were discharged into trays
to a bed depth of about 5 centimeters. The tray~ were
loosely fitted with aluminum foil lids and placed in an
autoclave where they were hydrated at a steam temperature
of 285F (140C) fo. 2 hours. After removal from the auto-
clave the particles were free-flowing, had a water content
; of 10 weight-percent, and expanded upon heating about 65
fold. Intumescence was measured by gradually pouring 2-
milliliter-size samples into an aluminum pan heated by a
hot plate to a temperature above 400F (205C), whereupon
the particles immediately intumesced. The intumescent
particles were then gathered and their volume measured in
a graduated cylinder.
Particles of the example were incorporated into
a standard roofing material in the manner shown in Figure
1. The weight amount of the various layers was as follows:
layer 12, 100 kilograms; layer 13, 15 kilograms; and layer
14, 300 kilograms per 10-by-10-meter section of applied
roofing. When the resulting roofing material was tested by
the Hburning brand" and more stringent laboratory tests
noted above, the fire did not burn through the test
samples.
Samples of the described roofing material were
placed on roof decks in restricted test sites for five
years, and when removed from the deck showed no visible
change and again passed the noted "burning brand" and more
stringent laboratory tests.
` Example 2
i- Example 1 was repeated in a larger batch size
:
P~
with a rotary .~lt(~ ve. I~lstead of 2 parts of caL(ium
hydro~ide, '0 ~ t~i were used. 'rhe laryer amount f~rmed
a thicker coatin~ on the particles and made them more free-
flowing without reducing intumescence.
E mple 3
Example l was repeated except the silicone
water-repellent agent was omi~ted. When the resulting
particles were tes~ed in the described accelerated aging
test, they exhibited useful in~mescence after a 20-day
exposure.
Examples 4 and 5
Example 3 was repeated except that the stearic
acid was replaced with either oleic acid (Example 3) or
palmitic acid (Example 4). In the accelerated aging test
the calcium-oleate-treated particles had a useful life of
6 days in water, and the calcium-palminate-treated particles
of 7 days.
Examples 6 - 8
Example 3 was repeated with sodium silicate par-
ticles e~cept that the calcium hydroxide was replaced witheither aluminum hydroxide (Example 6), magnesium hydroxide
~Example 7), or barium hydroxide (Example 8). In the ac-
celerated aging test, the aluminum-stearate-treated par-
ticles had a life of 6 days, and the barium-stearate-
treated particles of 9 days.
Examples 9 and 10
Example 3 was repeated except that the sodiumsilicate particles were replaced in Example 9 with lithium
silicate ~SiO2:K2O ratio of 2.50~ and in Example lO with
111~29i
- 20 -
potassium silicate (SiO2:K2O ratio of 2.50). Upon heating
to about 200C, the particles intumesced many-fold~
Example 11
Example 3 was repeated except that 2 parts of
polyethylene low-density polyethylene powder replaced the
stearic acid, and 2 parts of calcium hydroxide were used.
In the accelerated aging test the coated particles had a
life of 6 days.
Example 12
Sixty parts of particles of Example 3 were mixed
; into 100 parts of a mixture of Parts A and B of precursors
(available from Freeman Chemical Corporation, Port
Washington, Wisconsin) that form a pour-in-place, rigid
urethane foam having a density of about 0.032 gram per
cubic centimeter. The mixture was poured into trays and
allowed to cure. After removal from the trays, the cured
samples were conditioned according to the specifications
outlined in Underwriter's Laboratory's tests for flam-
mability of plastic materials, and then subjected to the
horizontal burning test for classifying materials (Test No.
94 HBF) and the vertical burning test for classifying
materials (Tes~ No. 94 VE-O). In each test the samples
- passed the test.
Example 13
- 25 Ten parts o~ particles of Example 3 were mixed
into a mixture of 100 parts polyol (TP740 commercially
available from Wyandotte Chemical Corporation) and 5S parts
of polyisocyanate (Mondur MRS commercially available from
- Mobay). The mixture was then catalyzed by adding 0.3 part
,~
~ ~ 7~ 7~
11182~?~
- 21 -
lead octoate. Samples were cured and conditioned according
to the specifications outlined in Underwriter's Laboratory's
tests for flammability of plastic materials, and then sub-
jected to the horizontal burning test for classifying ma-
terials (Test No. 94 HBF) and the vertical test for clas-
sifying materials tTest No. 94 VE-O). In each test the
samples passed the test.
Example 14
Uncoated sodium silicate particles (SiO2:Na20
ratio of 3.22~ ranging between 300 and 840 micrometers in
diameter and hydrated with a water content of about 14
percent were incorporated into roofing material as shown
in Figure 1. Weights were as listed for the roofing mater-
ial described in Example 1, except that the layer of intu-
mescent particles 13 weighed 100 kilograms per 10-by-10-
~ meter section of applied roofing. After exposure on a test
; deck for 3 years, the roofing material still exhibited
useful intumescence when exposed to ~ fire.
Example 15
:
One-hundred-sixty parts of anhydrous sodium
silicate fines having a SiO2:Na2O ratio of 3.22 and a
particle size smaller than about 300 micrometers were
mixed in a Hobart mixer with 40 parts of liquid sodium
silicate having a silica-to-soda ratio of 3.22 and a water
content of about 62 percent~ Agglomerated particles were
formed and screened to leave particles in a size range of
300 to 840 micrometers. The particles were coated in the
manner described in Example 1 with 2 parts stearic acid
and 5 parts calcium hydroxide, and then heated in an oven
,, ~
1118291
for about 4 llours. The resulting particles intumesced about 50-fold when
heated to 300C.
Alternatively, the particles can be prepared by coating the core
particles only with calcium hydroxide and no stearic acid, although the
particles are not as free-flowing during the hydrating operation.
- 22 -
