CA2631594A1 - Thermal barrier mineral foam composite - Google Patents

Abstract

Thermal barrier synthetic polymer composite embraces a synthetic polymer matrix made from reaction of a mixture of at least an isocyanate and an active hydrogen-containing compound, in intimate admixture and combination with at least one water-releasing mineral additive. Thermal barrier, fire resistance, fire retardant, and smoke reducing properties are provided by the composite.

Description

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 MinFoam-768 1 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.

MinFoam-768 2 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 MinFoam-768 3 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, MinFoam-768 4 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 MinFoam-768 5 employed include hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). The polyfunctional isocyanate may be commercially obtained; for example, it may be 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 MinFoam-768 6 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.
MinFoam-768 7 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 MinFoam-768 8 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.

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 MinFoam-768 9 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.

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.

MinFoam-768 10

Claims

CONCLUSION
The present invention is thus provided. Various feature(s), part(s), step(s), subcombination(s) and/or combination(s) may be employed with or without reference to other feature(s), part(s), step(s), subcombination(s) and/or combination(s) in the practice of the invention, and numerous adaptations and modifications can be effected within its spirit, the literal claim scope of which is particularly pointed out as follows:
What is claimed is:
The invention disclosed hereby in all its new and useful aspects and embodiments.
The invention described hereby in reference to all exemplary subject matter.