Note: Descriptions are shown in the official language in which they were submitted.
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THERMAL BARRIER MINERAL FOAM COMPOSITE AND SO FORTH
FIELD AND PURVIEW OF THE INVENTION
This concerns a polymer intrinsically including a number of mineral additives
for thermal
barrier, fire retardant, and smoke reducing properties. The polymer generally
is formed with an
isocyanate and an organic active hydrogen compound such as a polyol,
polythiol, polyamine,
polyimine or isocyanate itself, say, the polyol, and thus be a polymer such as
a polyurethane,
polyurethaneurea, polyurea, polyisocyanurate, or analog thereof, including
halogenated
compositions, and may be foamed, for instance, it may be the polyurethane,
especially a rigid
polyurethane foam. The mineral additives generally are a particulate such as a
basic, hydrated
particulate filler, which can provide for release of water at different,
predetermined, elevated
temperatures, say, a temperature below 200 C and a temperature above 200 C,
for example, a
mixture of calcium sulfate dihydrate (CSD) and aluminum trihydrate (ATH),
which can begin to
evolve water at temperatures of about 140 C from CSD and about 240 C from ATH.
The
mineral additive is made an intrinsic inclusion by providing it during
formation of the polymer,
which may be assisted by a reactive diluent such as a suitable organic
phosphorus compound, for
example, (tris(2-chloroethyl)) phosphate. Thus, the polymer may be considered
to be filled with
the mineral additive.
BACKGROUND TO THE INVENTION
Because of the natural flammability of organic polymer resins, it is common
practice to
incorporate a flame retardant into the formulation of a resin based
composition or system in
order to improve the fire safety of the final product. A common approach is to
incorporate into
the resin certain flame inhibiting compounds such as a phosphate, which may be
in powder form,
for example, monammonium phosphate, diammoniun phosphate, ammonium
polyphosphate, or
liquid form, for instance, a triaryl phosphate. Other approaches employ
melamine, other amines,
bromides, chlorides and/or oxides. Generally when compounded into resins at
sufficient levels,
these compounds impart flame retardant capability by interrupting the
chemistry of combustion,
evolving non-combustible gases and/or promoting char formation to limit flame
spread.
Although these additives have met with some success as flame-retardants,
certain
problems exist, especially when levels of visible and/or toxic smoke are taken
into consideration.
Many North American building codes specify limits on the amount of visible
smoke that would
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permitted during combustion, and these limits can effectively prohibit the use
of many non-
foamed and foamed plastics for interior finishes.
In addition, in particular, high levels of powdexed phosphates can affect the
physical
properties of the final product, for example, engendering friability in a
foamed polyurethane. An
excessive amount liquid phosphate can retard polymerization or lead to
extended reaction times,
and soft or inconsistent compressive strength, for example, in a polyurethane
matrix.
Countless plastic and composite formulations exist. Many of these include in
varying
amounts compounds that can release water when heated to a point where
combustion would be
sustained. It is known to employ dihydrate to decahydrate compounds - or other
complexes that
carry even greater quantities of water of crystallization - for such a purpose
in plastics, including
extruded plastics, electrical cable jackets, films, solids and foams. It is
often said that such these
additives reduce flame spread and combustion byproducts - primarily because
they lower the
flame spread ratings and smoke index when tested by the Steiner Tunnel Test
protocol (ASTM-
E84 in the U.S. or Can4-102 in Canada), which measures the distance that a
flame travels along
an exposed surface of the product in ten minutes (measures the "Flame Spread
Rating") and the
opacity of smoke developed over the duration of the test with a photoelectric
cell (to determine
the "Smoke Developed Rating").
Although there is considerable advantage to reducing flame spread and smoke
developed
ratings for products tested under ASTM-E84 and Can4-S 102, such products are
subject to
considerable constraint in the market. For example, for polyurethane products,
typical flame
spread ratings may be 150-450 and smoke developed ratings 450-600 plus; which
limits the use
of the polyurethane products under most building codes in both countries due
to the rapid flame
progression and high smoke levels. Furthermore, while flame spread and smoke
developed
ratings can be suitable for products for interior use, many of such products
are classified as
"foamed plastic," therefore subject to rules requiring that they be covered by
a thermal barrier -
a covering which must meet the requirements of ASTM-E 119 or corresponding
Can4-S 127 test
protocol. This thermal barrier test protocol requires that the covering be
exposed to elevated
temperatures and be of sufficient thermal resistance to protect the foamed
plastic from
temperatures in excess of 140 C to 180 C for period of ten to fifteen minutes.
Protection of this
magnitude is commonly provided simply by the application of a single sheet
of'/2-inch gypsum
board (drywall) covering the exposed face of the foamed plastic substrate.
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While many times the installation of a sheet of drywall is not an undue
hardship, there are
situations where the installation of the drywall cover may completely negate
the advantage of
installing the foamed plastic substrate. One manifest disadvantage of
installing drywall as a
thermal barrier board would be in situations where the foamed plastic had been
installed for its
decorative features such as the case wherein a foamed urethane plastic formed
a decorative,
ornamental feature such as the manufacture of decorative stone-like veneers
and the like.
Another disadvantage would be in that of an outdoor application.
Returning to the hydrated compounds known to be employed as mentioned above,
among
such compounds include flame inhibiting hydrated minerals such as ATH,
magnesium hydroxide
(Mg(OH)2), and others. When these hydrated minerals are incorporated as
powders into resins at
sufficient levels, they impart both flame and smoke retardant capability when
at elevated
temperatures they evolve non-toxic gases such as water vapor to dilute the
combustion products
and promote char formation. Although these hydrated minerals have met with
some success as
flame-retardants, certain problems exist. For example, with respect to
polyurethanes, high
loadings of ATH or the other hydrates can affect the viscosity of liquid
polyol side of the
formulation where they are typically employed and make blending and casting of
urethane
shapes difficult due to the extremely high viscosities of the liquid-powder
blends. Also, friability
of polyurethane foams can be a problem with the high loadings of ATH required
to impart the
desired flame and smoke retardant capability to the foam.
Various U.S. patent art is illustrative:
No. 4,547,526 to Al-Tabaqchali et al. This discloses a flame protecting
composition
comprising aluminum trihydrate, organic binder, and a sulfur compound
and a polyurethane foam provided with such flame-protection composition.
No. 4,876,291 to Dallavia, Jr., et al. This discloses a mineral filler fire
retardant
composition and method.
No. 5,444,115 to Hu et al. This discloses a fire resistant
poly(methylmethacrylate)
composition.
No. 5,508, 315 to Mushovic. This discloses cured unsaturated polyester-
polyurethane
hybrid highly filled resins.
No. 6,790,906 to Chaignon et al. This discloses fire-retardant polyurethane
systems.
Pub. No. 2006/0089444 of Goodman et al. This discloses flame retardant polymer
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compositions comprising a particulate clay mineral.
It would be desirable to ameliorate or overcome problems in - or provide
alternatives to -
the art. It would be desirable moreover to provide thermal barrier and fire
retardant properties,
plus smoke reduction, in a synthetic polymer, especially a foam, for instance,
a foamed
polyurethane.
A FULL DISCLOSURE OF THE INVENTION
In general, provided is a synthetic polymer intrinsically including a mineral
additive for
thermal barrier, fire retarding and smoke reducing properties. The polymer can
be formed with
an isocyanate and an organic active hydrogen compound such as a polyol,
polythiol, polyamine,
polyimine, and so forth, or isocyanate itself, for instance, the polyol, and
thus be a polymer such
as a polyurethane, polyurethaneurea, polyurea, polyisocyanurate, or analog
thereof, including
halogenated compositions. The polymer may be foamed. It may be, for instance,
the
polyurethane, especially a polyurethane foam, especially a rigid polyurethane
foam. The mineral
additive can be a particulate such as a basic, hydrated particulate filler,
which can provide for
release of water at different, predetermined, elevated temperatures, for
instance, being a mixture
of different mineral additives. The mineral additive is made an intrinsic
inclusion by providing it
during polymer formation, which may be assisted by a reactive diluent. The
polymer may be
considered as filled with the mineral additive.
The invention is useful as a thermal barrier, fire and/or smoke retarding
synthetic plastic.
Significantly, by the invention, the art is advanced in kind. Not only is a
plastic product
that can serve as a thermal barrier and fire retardant provided, but also the
plastic product can
have smoke retardant capability. This can extend over a generous range of
temperatures. For
example, a foamed polyurethane may be filled with mineral additives that
release water at
a temperature below 200 C and a temperature above 200 C, say, with a mixture
of CSD and
ATH, which can begin to evolve water at temperatures about 140 C and 240 C,
respectively, to
afford such capabilities. Moreover, the smoke reduction can be provided to a
level that is
acceptable under existing U.S. and Canadian building codes. Embodiments of the
present
mineral foam composite can be light weight, and provide superior thermal
barrier physical
properties, say, a Class A rating, when compared to conventional two-component
urethane foams
common in the prior art, for example, when tested according to the ASTM-E 119
or
corresponding Can4-S 127 test protocol and/or provide superior results, i.e.,
a marked decrease,
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in flame spread and smoke developed ratings when compared to a conventional
two-component
urethane foam, for example, under the ASTM-E84 or corresponding Can4-S 102
test protocol.
Furthermore, thermal barrier protection without covering decorative features
of a synthetic
plastic veneer can be provided in decorative products. Thus, a synthetic
composite product can
provide the advantages and appeal of the decorative product without the need
for a separate
thermal barrier cover. What is more, the product can be highly uniform
throughout with respect
to the mineral additive. For example, a combination of ATH and CSD blended
with the polyol
side for a polyurethane foam before being reacted with the isocyanate side for
the polyurethane
foam permits the desired effects but at a low overall cost and with little if
any settling of the
mineral additives when thus blended and reacted. A so-called "reactive
diluent," for example, a
liquid triaryl phosphate or (tris(2-chloroethyl)) phosphate, can assist in
this. The invention is
highly effective, economical and efficient.
Numerous further advantages attend the invention.
The invention can be further understood by the detail set forth below. As with
the
foregoing, such is to be taken in an illustrative and not necessarily limiting
sense.
At the outset, exemplary of the invention is a filled polyurethane foam. A
polyurethane
generally refers to the reaction product of a polyfunctional isocyanate with a
polyol, the reaction
products of isocyanates with themselves, or the reaction of a polyfunctional
isocyanate with any
hydrogen donor to produce a polymerized compound.
Generally, the present composition evolves water at elevated temperatures. The
temperatures may be about 120 C and above, about 140 C and above, or about and
above any
other suitable temperature(s). For instance, a multi-tiered release of water
may occur, say, with a
first release about 140 C and a second release about 240 C.
A thermal barrier, fire and/or smoke retardant polyurethane composite mineral
foam can
be made by providing a liquid isocyanate side (A-side), which contains a
polyfunctional
isocyanate. A polyfunctional isocyanate is an isocyanate or mixture of
isocyanates having an
average functionality greater than one. Polyfunctional isocyanates can include
di-, tri- or tetra-
isocyanates, or a mono-functional isocyanate employed in a mixture with an
isocyanate of higher
functionality. Common aromatic polyfunctional isocyanates that may be employed
include pure
or mixed isomers of toluene diisocyanate (TDI), diphenylmethane diisocyanate
(MDI) and
polymeric MDI. Common aliphatic or cyclo-aliphatic polyfunctional isocyanates
that may be
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employed include hexamethylene diisocyanate (HDI) and isophorone diisocyanate
(IPDI). The
polyfunctional isocyanate may be commercially obtained; for example, it may be
HAD-M7000-
32 (Carpenter Co., Richmond, Va.). Separate from the A-side, a polyol side (B-
side) mixture
can be prepared, which can contain the polyol and other ingredients such a
blowing agent, for
example, water, and a catalyst, for example, potassium 2-ethylhexanoic acid,
potassium acetate
or (tri(dimethylaminomethyl))phenol, plus the mineral additive, say, in
particulate form, for
instance, by admixing the mineral additive with a polyol and other ingredients
without mineral
additive to form the B-side mixture with mineral additive. A polyol generally
is a polyhydroxy
organic compound, and it may be formed by a polymeric reaction product of an
organic oxide
and a compound containing two or more active hydrogens. For example, polyether
polyols are
based on propylene oxide terminated with a secondary hydroxyl. Typical of
polyols that are
used in commercial urethane foam production and that may be employed herein
include 1, 4-
butanediol; hydroxy terminated polyethylene oxide, and polypropylene oxide.
The polyol can be
commercially obtained; for example, it may be EB-HDB-900 polyether polyol
(Carpenter Co.,
Richmond, Va.). A "reactive diluent" may be provided for the B-side. The
reactive diluent acts
to reduce the viscosity of the polyol and permit blending of the mineral
additive with the
remaining polyol side ingredients without increasing the viscosity to the
extent that handling and
mixing would be adversely affected and may enhance homogeneity of the mixture;
for instance,
the reactive diluent may be a suitable organic phosphorus compound such as a
liquid triaryl
phosphate or trialkyl phosphate or mixed trialkyl-triaryl phosphate, to
include halogenated
version(s) thereof, for example, (tris(2-chloroethyl))phosphate, which is
commercially available
as Fyrol CEF (Supresta LLC, Ardsley, N.Y.). A polyol blend can be diluted with
the reactive
diluent, and then particulate mineral additive hydrates, for example, ATH and
CSD, can be
blended to form a homogeneous mix to form the B-side. A suitable ratio of the
A-side and B-
side mixture then can be contacted to produce a polyurethane-based composite
mineral foam
having suspended therein the particulate mineral additive. This polyfunctional
isocyanate and
polyol/filler blend can be mixed for a period of time at temperatures
sufficient to initiate
polymerization to form the polyurethane. The A-side and B-side mixture may be
discharged into
a mold, covered and left to rise and fill the cavity.
The mineral additive may be provided by a combination of two or more hydrated
mineral
fillers which function to increase the thermal barrier properties of the
polyurethane composite
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mineral foam. A first mineral additive can be a basic, hydrated, particulate
mineral filler capable
of evolving water at a temperature above 200 C, for example, A1203.H2O, which
is also known
as ATH, or Mg(OH)2, or other suitable compound that releases water vapor when
heated above
200 C. Typically, for example, ATH will release most of its water at about 240
C. Amounts of
the first mineral additive can vary; for instance, they may be 1.5 to 19.5 or
3.1 to 6.2 percent by
weight of the liquid B-side mixture including any reactive diluent or second
or more mineral
additive or additional material; for example, ATH may be added at about 3.5
percent by weight
of such a liquid B-side, and Mg(OH)2, at about 2.0 percent by weight of such a
liquid B-side. A
second mineral filler can be a basic, hydrated, particulate mineral filler
capable of evolving
water, but has a bulk density that is considerably lower than the first
mineral additive, especially
ATH, and a lower decomposition temperature, for instance, below 200 C, for
example, CSD or
other suitable compound that releases water vapor when heated below 200 C.
Typically, for
example, CSD will release most of its water at about 140 C, and it assists in
reducing both the
smoke developed rating and also contributes to the much improved thermal
barrier rating by
interrupting the chemistry of combustion during the early stages of the fire
and affording marked
improvement in delays in temperature rise through the mineral foam core which
translates into
the improve `thermal barrier' properties. Amounts of the second mineral
additive can vary; for
instance, they may be 1.5 to 20.5 or 14.5 to 20 percent by weight of the
liquid B-side mixture
excluding any reactive diluent or first or other than second mineral additive
or additional
material; for example, CSD may be added at about 15 percent by weight of such
a liquid B-side.
The mineral additive may have any suitable particle size, for instance, from
about 1, 3, 5 or 10 to
some 10, 25, 50, 75 or 100 microns, more or less. For example, ATH can be
provided in varying
particle sizes about from 5 to 50 microns, and CSD can be provided in varying
particle sized
about from 5 to 75 microns. Other hydrated mineral filler compositions fillers
may include di-,
tr-i, tetra-, penta-, sexta-, septa-, octa- nona- and deca- hydrates, which
may be finely divided
sufficiently to produce a slurry when nixed with the polyol and any reactive
diluent.
Materials for making the polyurethane can be those materials and/or compounds,
which,
when mixed at the appropriate ratios, produce a rigid polyurethane foam. For
instance, such
materials can have ingredients similar to or made or sold by Urethane
Technologies Corporation
of Newburgh, N.Y., under the designation "UTC-6022-7.5FR." As with most if not
all
polyurethane systems, such ingredients are provided in two parts or sides, the
A-side and B-side.
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It is believed that that B-side contains polyols, blowing agents, and
catalytic agents, and has a
viscosity of 150-350 cP and a specific gravity of 1.22-1.24 at 77 F (25 C).
The A-side is a
polyisocyanate component containing polymethylene-polyphenyl-isocyanate, and
has a viscosity
of 1000-1200 cP and a specific gravity of 1.10 at 77 F (25 C). When
appropriately mixed, and
dispensed, for instance, by casting, spraying, and so forth, these two main
ingredients produce a
cured polyurethane material having a density of 5-25 pounds per cubic feet.
The mixing ratio of
the A-side (UTC-6022-7.5 FRA) to the B-side (UTC-6022-7.5 FRB) can be any
suitable ratio,
for instance, about 1:1.55 by weight. The two sides can be dispensed, for
instance, by hand, by
mixing gun, and so forth, and reacted, say, at temperatures of 60-250 F (16-
121 C). Other
materials can be employed. To such ingredients, say, with the B-side, is added
any reactive
diluent and the mineral additive.
Additional materials may be added. For instance, a chopped aramid fiber and/or
a
chopped carbon fiber may be added. Each or both may be have independently an
about 0.5-rrim
or an about 1-mm to an about 6-mm or an about 20-mm length. The chopped aramid
fiber, for
example, may be poly(p-phenylene terephthalamide) and/or poly(m-phenylene
isophthalamide).
A pigment such as iron oxide, titanium dioxide, and so forth may be employed.
The additional
material(s) may be provided in any suitable amount. For instance, the chopped
aramid and/or
carbon fiber(s) may be present from about 0.1 to about ten percent by weight
of total composite,
and/or the iron oxide pigment may be present from about 0.01 to about five
percent by weight of
the total composite.
The present composite may embrace from about 35 to about 45 percent by weight
of a
polyol, from about 35 to about 45 percent by weight an isocyanate and from
about 6 to 8 percent
of reactive diluent (such as Fyrol CEF), and from about 3.5 to about to 4.5
percent by weight of a
metal hydrate such as alumina trihydrate, and from about 10.1 to about 12
percent by weight of
calcium sulfate dihydrate. It may also embrace colored pigments and chopped
fiber, and other
functional and/or complimentary fillers.
The present composite may be considered to embrace a thermal barrier, flame
and/or
smoke retardant mineral foam composite including a particulate ATH filler and
a particulate
CSD filler, generally as a polymeric material formed from a polyfunctional
isocyanate, with the
polymeric material being present in an amount sufficient to coat without
substantially
agglomerating the particulate fillers, the particulate fillers associated with
an initiator in an
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amount sufficient to effect reaction polymerization of the polyfunctional
isocyanate. The
composite may have the polyfunctional isocyanate present in an amount about
from 30% to 50%
to include substantially between 30% to 50% by weight of the total mix. The
polymeric material
may be formed from the polyfunctional diisocyanate and a polyol in combination
with a reactive
diluent and the particulate fillers. The polymeric reaction product may be
present in an amount
about from 30% to 50% to include substantially between 30% to 50% by weight of
the final mix.
The present composite may be considered to embrace a thermal barrier, flame
and/or
smoke retardant mineral foam composite of a polyurethane foam material formed
from the
reaction of a suitable isocyanate and a polyol, with the material containing
suspended therein an
amount of a particulate mineral additive effective to reduce the flammability
of the polyurethane
foam composite material. An initiator of a catalyst may be employed to
initiate polymerization
of the isocyanate. The polymeric material may be formed from
autopolymerization of one or
more polyfunctional isocyanates in the presence of the mineral additive.
The present composite may be considered to embrace a thermal barrier, flame
and/or
smoke retardant mineral foam composition including a particulate ATH in
combination with a
CSD. A reactive diluent may be employed.
Either side of the polyurethane forming ingredients may contain the mineral
additive and
be provided in such form. For instance, a liquid B-side with the mineral
additive, optionally with
the reactive diluent, may be provided for sale, accompanied or not by a
corresponding separate
A-side for reaction with the B-side to make a polyurethane.
The polyurethane may be substituted by or augmented with an analog thereof
and/or
another type polymer. For instance, the other type of polymer may be
polymethylmethacrylate.
The following examples further illustrate the invention. Therein, parts and
percentages
are by weight unless otherwise specified.
EXAMPLE 1
Two storage tanks are provided to hold reagents. In one tank is an isocyanate -
in this
case HAD-M700-32. In the other tank is a mixture of polyol, in this case EB-
HDB-900; reactive
diluent, in this case Fyrol CEF; and the ATH and CSD mineral filler fire
retardant blended
together in a premix. In addition, a small quantity of an iron oxide pigment
was added to help
differentiate this product from other - typically yellow colored - urethane
products of this type.
When the contents of the two storage tanks are properly blended together at
appropriate ratios, as
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outlined herein below, a reaction occurs and a polyurethane-based thermal
barrier mineral foam,
fire and/or smoke retardant composite is produced.
Two liquid parts referenced as Part A and Part B were formulated as follows:
Part A: Isocyanate 7701b. 41.10%
Part B: Polyol 7561b. 40.25%
Reactive diluent 1081b. 05.75%
Brown oxide pigment 22.51b. 01.20%
ATH 60.0 lb. 03.20%
CSD 162. lb. 08.60%.
When these two liquids were blended, at room temperature, say, between 60 F
and 70 F,
using a high shear mixer, at a ratio of 1.3 parts of A to 2.0 parts of B (w/w)
and cast in a six
sided rectangular mold, the result was a rigid composite mineral foam slab
with a density about
from 12 to 181b./cu.ft. depending on the quantity of the mixed materials to
the size of the mold
and the pressure or constraints exerted on the mold during the iso/polyol
foaming reaction.
When 2.321bs. of the above mentioned blend of materials was cast in a 12" x
24" x 1"
mold, the result was a solid mineral foam composite having a density of 18.1
lb./cu.ft. The lid of
the mold was constrained in a press at 20 psi to prevent the rising foam from
escaping the gap
(by lifting the lid) between the mold and the lid.
EXAMPLE 2
The composite of Example 1, when cast in a rigid shape at 3' x 3' x 1-1/2
inches was
subject to testing under the Can4-S 127 - 15 minute "Thermal Barrier Test."
The product offered
a Class A Thermal Barrier Rating at a nominal thickness of 1.5 inches.
When this same mix was cast as one-inch thick panels by 12" x 24" and placed
edge to
edge over a 24-foot Steiner Tunnel and tested under Can4-S 102 - the 10-minute
Steiner Tunnel
Test - the results after three such tests consistently demonstrated an average
Flame Spread of 15
and a Smoke Developed Rating of less than 350. The combination of these
performance
characteristics based on these approved test methods makes the composite
suitable for use as a
thermal barrier mineral foam composite, and it may be used on interior
surfaces in most
occupancies under the North American Model Building Codes.
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