2019 APR 19 (NewsRx) -- By a
No assignee for this patent application has been made.
News editors obtained the following quote from the background information supplied by the inventors: “Field of the Invention
“The Inventions Disclosed And taught herein relate generally to polyurethanes and their manufacture, and more specifically, are related to methods for the manufacture and installation of isocyanate and polyurethane based foams with improved flame retardation and charring properties.
“Spray foam insulation is an alternative to traditional building insulation such as fiberglass. A two-component mixture composed of isocyanate and polyol resin comes together at the tip of a gun, and forms an expanding foam that is sprayed onto roof tiles, concrete slabs, into wall cavities, or through holes drilled in into a cavity of a finished wall.
“Various systems are used to apply the spray foam. The two component high pressure system is generally used in new home construction. It is a quick expanding type of spray foam. The two component low pressure spray foam is another system that is used primarily for remodel jobs where there are existing walls with drywall already in place. This is also known as a slow rise formula and often referred to as injection foam
“Spray foam insulation can be categorized into two different types: open cell and closed cell.
“Open Cell Foam Insulation
“Open cell is a type of foam where the tiny cells are not completely closed. Open cell is less expensive because it uses fewer chemicals. It is a very good air barrier but does not provide any type of water vapor barrier. It is much more sponge-like in appearance. It is often used for interior walls because it provides sound reduction. It is not recommended for outdoor applications.
“Closed Cell Foam Insulation
“Closed cell foam insulation is much denser than open cell. It has a smaller, more compact cell structure. It is a very good air barrier as well as a water vapor barrier. It is often used in roofing projects or other outdoor applications, but can be used anywhere in the home.
“US Patent Publication 20130030067 to Mooney et al provides a thorough background on polyurethane foam, and much of that background is provided herein.
“Polyurethane foams articles are used extensively in a wide array of commercial and industrial applications. The popularity of polyurethane foam articles is due in part to the fact that the physical properties of a polyurethane foam article may be selectively altered based on the formulation of reactants which form the polyurethane foam article. The formulation may be developed to provide a polyurethane foam article that is soft, flexible and open-celled which can be used in applications such as seat cushions. On the other hand, the formulation may be developed to provide a polyurethane foam article that is rigid, structural, thermally resistant and closed-celled and which therefore can be used as a thermal insulation panel.
“The most common method of forming polyurethane foam articles is the mixing and, subsequent reaction, of a polyol (e.g. a resin composition) with an isocyanate in the presence of a blowing agent. Generally, when the resin composition is mixed with the isocyanate to form a reaction mixture in the presence of the blowing agent, a urethane polymerization reaction occurs. As the urethane polymerization reaction occurs, the reaction mixture cross-links to form the polyurethane and gas is simultaneously formed and released. Through the process of nucleation, the gas foams the reaction mixture thereby forming voids or cells in the polyurethane foam article.
“The resin composition typically comprises one or more polyols, a cell opening agent, a cross linking agent, a catalyst, an adhesion promoting agent and various additives. The blowing agent creates the cells in the polyurethane foam article as described above. The cell opening agent helps open the cells so that the cells form an interconnected network and improves the stability of the polyurethane foam article. The cross-linking agent promotes cross-linking of the reaction mixture which results in the polyurethane foam article. The catalyst controls reaction kinetics to improve the timing of the polymerization reaction by balancing a gel reaction and the blowing agent to create the polyurethane foam article, which is stable. Other additives, such as adhesion promoting agents (e.g. a protic solvent), may be added to the formulation in order to facilitate wet out of the reaction mixture and promotes adhesion of the polyurethane foam article to substrates upon which the polyurethane foam article is disposed. For example, the substrate may be a thermoplastic shell or thermoplastic liner of a picnic cooler. The density and rigidity of the polyurethane foam article may be controlled by varying the chemistry of the isocyanate, therein composition and/or the blowing agent, and amounts thereof. Other additives that are often included within the polyurethane foam product are fire retardants, typically halogenated--(e.g., brominated and chlorinated materials) and phosphorus-containing retardant materials.
“Plastic foams have been utilized as thermal insulating materials, light weight construction materials, and flotation materials and for a wide variety of other uses because of their excellent properties. Until recently, their use has been somewhat limited in environments where there is danger of fire because of their substantial fuel contribution, their contribution to rapid flame spread and the fact that they generate large quantities of noxious smoke on thermal decomposition when burned or heated to an elevated temperature. This has limited the commercial development of plastic foams, and large amounts of money and much research time have been expended in attempts to alleviate these problems.
“With the present interest in conserving heating fuel, many existing buildings are installing additional insulation, and newly constructed buildings are including more insulation than was formerly used.
“A previously common type of foam insulation for existing structures are urea formaldehyde foams, which are foamed in place between the outside wall and the inside wall of the structure, with or without additional, fiberglass insulation. Fiberglass insulation alone can be considered to be porous in nature since it is generally a mat of fine glass fibers, which can contribute to lower insulation values by allowing air circulation within the walls. Foam insulations, however, form an air barrier between the interior and exterior walls of a structure, and thus form a generally impervious barrier to air circulation, thereby making them better insulation materials. Unfortunately, the urea formaldehyde foam that has been used spontaneously decomposes, releasing formaldehyde fumes in quantities which may be toxic. The use of urea formaldehyde foams in construction is prohibited in many building codes for this reason.
“Polyurethane Foam Insulation
“Another type of material often used for insulation is polyurethane foam. However, polyurethane foam provides a substantial fuel contribution, spreads flame rapidly, and releases toxic gases including carbon dioxide, carbon monoxide and hydrogen cyanide when burned.
“Rigid Polyurethane Foam
“Rigid polyurethane foams are generally prepared by reacting an organic polyisocyanate with a polyol. For most commercial purposes, the reaction is conducted in the presence of a foaming agent, surfactant, catalyst and possibly other ingredients.
“Ignition Barrier or Thermal Barrier Requirements
“Examples of improved foams can meet ignition barrier or thermal barrier requirements without the use of a secondary system. On the construction side, this will greatly reduce install time and cost related to constructibility, worker exposure, inspection, and reliability of the system. On the residential or commercial occupant side, this has the potential to increase the time of fire rated assemblies that are already using standard isocyanate and polyurethane based foams, thus improving safety and increasing potential survivability of the occupants.
“Non-prescriptive thermal barriers (termed ‘equivalent thermal barriers’) must undergo a temperature transmission fire test wherein the temperature rise of the underlying polyurethane foam is limited to not more than 121.degree. C. (250.degree. F.) after 15 minutes of fire exposure complying with the standard time temperature curve of ASTM E 119 (Test Methods for Fire Tests of
“In effect, equivalent thermal barriers (i.e., other than the prescriptive 1/2-inch thick gypsum wallboard) must undergo two fire tests: (1) A temperature transmission test (such as a modified ASTM E 119, the actual thermal barrier test apparatus being smaller than the typical large-scale wall or roof/ceiling test assemblies); and (2) A fire integrity test (a large-scale fire test such as NFPA 286 [with a specific acceptance criteria defined within the IBC or IRC], UL 1040, UL1715 or FM 4880).
“One approach to improving fire resistance is to provide a flame retardant agent in the foam composition. One type of flame retardant agent is an endothermic decomposition agent, such as magnesium hydroxide, Mg(OH).sub.2,
“This class of flame retardants is primarily condensed phase in its activity, but there is also some vapor phase action. When this flame retardant is heated, it decomposes endothermically to cool the condensed phase (thus preventing further heat-induced decomposition and pyrolysis) and typically releases a nonflammable gas. This nonflammable gas dilutes the total amount of fuel in the vapor phase which either prevents/delays ignition or keeps heat release low, allowing for self-extinguishment once the external flame is removed from the polymer.
“The types of additives that fall into this class are typically mineral fillers, including hydroxides such as aluminum hydroxide (also known as alumina trihydrate) and magnesium hydroxide, as well as carbonates such as hydromagnesite. Organic carbonates can also be used as flame retardants, but they are not as effective as mineral filler systems. This is because the mineral filler flame retardants bring one additional benefit to the condensed phase: they dilute the total amount of fuel in the condensed phase, since after they release their nonflammable gas and cool the condensed phase, they are typically inorganic oxides, which cannot be burned further. Those oxides have not only replaced flammable polymer fuel, but sometimes will fuse together and form protective ceramic barriers as well.
“Methods for Creating
“Another approach to improving fire resistance is to provide a charring agent that creates a char layer when the foam is subjected to flame or heat .
“Modesti [Ref 1] discusses three types of charring agents-ammonium polyphosphate, melamine cyanurate and expandable graphite. All those compounds lead to the formation of a superficial char layer that prevents further decomposition, but they act in three different ways: Ammonium polyphosphate (APP) leads to the formation of a char layer through the linking of phosphates to the ester group; the latter are readily eliminated forming conjugated double bonds, which finally cyclize to give char; Melamine cyanurate (MC) acts through endothermic decomposition that leads to evolution of ammonia and formation of condensation polymers; and Expandable graphite (EG) leads to the formation of a char layer characterized by the presence of ‘worms’, deriving from its expansion.
“Several example compositions appear to quickly provide an effective char layer in a manner that is different from the mechanisms described by Modesti. Without being limited by theory, Applicants propose that ground mineral wool is an example novel type of char-promotion agent and suggest a possible mechanism for its effectiveness. One theory is that ground mineral wool is an effective sintering agent, whereby the ground mineral wool particles are readily sintered together at a temperature below the particle melting temperatures.
“Prior Art Use of Mineral Wools
“Mineral wool is provided as batts for wall or ceiling insulation.
“European Patent Application 1893404 (WO2006134236) to Fellman at al describes a fire protection element comprising at least two mineral wool layers sandwiching an inorganic layer which literate water or carbon dioxide in the presence of heat. Feldman notes that it is previously known to use mineral wool in fire protection slabs. The reason for this are the good fire protection properties of the mineral wool itself. It is also known to e.g. between two layers of mineral wool such as stone wool arrange an inorganic material layer, consisting of a dehydrating hydroxide as a fire retardant in combination with a binder, which is to bind the mineral wool slabs together. Such solutions are described for example in prior art in publications EP 1239093 A2, EP 0741003 B1, EP 0485867 B1 and EP 0353540 B2.”
As a supplement to the background information on this patent application, NewsRx correspondents also obtained the inventors’ summary information for this patent application: “Despite the cost differential between drawn, or textile, glass fiber and blown glass or mineral wools, it does not appear that prior art has heretofore successfully added quantities of blown glass or mineral wool into an isocyanate based foam product because of clumping, non refinement, and dispensability of these fibers.
“Applicants suggest a representative method for incorporating mineral wool and a secondary flame retardant into an isocyanate foam which does not introduce extraneous or deleterious constituents or require expensive capital investment for auxiliary equipment. Ground mineral wool, or similar materials such as ground blown glass, may be blended with appropriate amounts of secondary fire retardant, such as an inorganic metal based flame retardant, in such a fashion that the individual mineral wool fiber segments or particles are dispersed evenly and suspended in solution. In this form, the mineral wool is readily and accurately meterable into isocyanate foam formulas using conventional equipment and readily disperses throughout the aqueous mixture.
“In a first embodiment of the present disclosure, ground mineral wool is added to conventional polyurethane composition A or B. In accordance with a first embodiment of the present disclosure, a flame-retardant polyurethane foam made by reacting together a first and second reaction mixture is described; the first and second reaction mixtures comprising a polyol wherein substantially all of the hydroxyl groups on the polyol are free; an isocyanate; a surfactant; an aqueous blowing agent; a polyurethane producing catalyst; a ground mineral wool charring agent; and a magnesium hydroxide flame retardant. A method of making a flame-retardant polyurethane foam is described, the method comprising (a) mixing an untreated polyol in which substantially all of the hydroxyl groups are free, a surfactant, a polyurethane forming catalyst, and water to form a first aqueous solution; (b) adding to the first aqueous solution mixture a second solution containing a polyisocyanate; and © allowing the mixture to foam.
“In a second embodiment, a larger percentage of ground mineral wool is used in combination with a higher water concentration in order to substantially reduce the hydrocarbon content of the resulting foam.
“In a third embodiment, a foam composition is substantially re-formulated to reduce polyol concentration. Preliminary testing has suggested that it is possible to create an effective foam-like insulation without requiring the ‘foam’ components to have a high poll concentration.
“In one example, a method for preparing a water blown, low density, polyurethane foam, is described, the method which comprises contacting at least one polyisocyanate with at least one natural polyol in an amount from about 20 wt. % to about 70 wt. %, at an Isocyanate Index of 10 to 120, more preferably at an Index between 20 to 50, in the presence of a blowing agent composition comprising at least 2 wt. % water, preferably at least about 5 wt. % water, and an effective amount of a catalyst composition comprising a gelling catalyst which and a blowing catalyst, the foam having a density of 0.3 lb/ft.sup.3 to 5 lb/ft.sup.3 (6 Kg/m.sup.3 to 80 Kg/m.sup.3). In further accordance with aspects of this embodiment, the natural polyol is sucrose, invert, molasses, or a combination thereof, and provides an open-cell foam with a low compressive strength, and good tensile strength.
“In accordance with further aspects of the present disclosure, a composition for preparing polyurethane foam is described, the composition comprising an A-side component comprising one or more isocyanates, and a B-side component comprising between 20 to about 70 wt. % of natural polyol, between about 0.5 wt. % and 10 wt. % water, a surfactant in an amount between about 1.0 wt. % and about 5 wt. %, between about 0.05 to about 10 wt. % of a blowing catalyst, from about 0.5 wt. % to about 5 wt. % of a chain extender, an amine catalyst in an amount from about 0.01 wt. % to about 10 wt. %, a plasticizer in an amount ranging from about 0.01 wt. % to about 15 wt. %, and a fire retardant in an amount ranging from about 5 wt. % to about 40 wt. %, and wherein the volume ratio of A-side component to B-side component is about 1:1.
“Flame Retardant and Charring Additives
“In some embodiments, a ground mineral wool charring agent and a metal hydroxide flame retardant agent, such as Mg(OH).sub.2 are added to the foam component(s).
“Metal hydroxides function in both the condensed and gas phases of a fire by absorbing heat and decomposing to release their water of hydration. This process cools both the polymer and the flame and dilutes the flammable gas mixture.
“There are several ways in which the combustion process can be retarded by physical action (Troitzsch, 1990).
“(a) By cooling. Endothermic processes such as triggered by additives such as cool the substrate to a temperature below that required to sustain the combustion process.
“(b) By formation of a protective layer (coating). The condensed combustible layer can be shielded from the gaseous phase with a solid or gaseous protective layer. In some embodiments, the formation of this ‘char layer’ is facilitated by a ‘charring agent’ agent such as ground mineral wool. The condensed phase is thus cooled, smaller quantities of pyrolysis gases are evolved, the oxygen necessary for the combustion process is excluded and heat transfer is impeded.
“The most significant chemical reactions interfering with the combustion process take place in the solid and gas phases (Troitzsch, 1990).
“(a) Reaction in the gas phase. The free radical mechanism of the combustion process which takes place in the gas phase is interrupted by a flame retardant such as Mg(OH).sub.2. The exothermic processes are thus stopped, the system cools down, and the supply of flammable gases is reduced and eventually completely suppressed.
“(b) Reaction in the solid phase. Here two types of reaction can take place. Firstly, breakdown of the polymer can be accelerated by the flame retardant, causing pronounced flow of the polymer and, hence, its withdrawal from the sphere of influence of the flame, which breaks away. Secondly, the flame retardant can cause a layer of carbon to form on the polymer surface. This can occur, for example, through the dehydrating action of the flame retardant generating double bonds in the polymer. These form the carbonaceous layer by cyclizing and cross-linking.”
The claims supplied by the inventors are:
“1. An additive composition for improving flame or fire retardant properties of polyurethane foam, the additive composition comprising a char-promoting component comprising a first ceramic, glass, mineral, or slag material having a particle size in the range of 1 to 6730 microns.
“2. The additive composition of claim 1 wherein the char-promoting component comprises a first ceramic, glass, mineral, or slag material having a particle size in the range of 1 to 1680 microns.
“3. The additive composition of claim 1 wherein the char-promoting component comprises a first ceramic, glass, mineral, or slag material having a particle size in the range of 1 to 595 microns.
“4. The additive composition of claim 1 wherein the char-promoting component comprises a ground mineral wool having a particle size in the range of 1 to 595 microns.
“5. The additive composition of claim 4 wherein the char-promoting component is a ground rockwool.
“6. The additive composition of claim 1 further comprising a flame retardant component in the range of 2 to 45 percent by weight; and
“7. The additive composition of claim 6 wherein the flame retardant agent is an endothermic decomposition agent.The additive composition of claim 10 wherein
“8. The additive composition of claim 7 wherein the flame retardant agent is magnesium hydroxide.
“9. An open cell polyurethane spray foam insulation composition comprising a Part A, isocyanate, foam insulation composition; a Part B, polyol, foam insulation composition; and ground mineral wool.
“10. The open cell polyurethane spray foam insulation composition of claim 9 further comprising a flame retardant agent in the range of 2 to 45 weight percent.
“11. The open cell polyurethane spray foam insulation composition of claim 9 further comprising a ground mineral wool is provided in the Part A, polyol, foam insulation composition in the range of 2 to 45 weight percent.
“12. The open cell polyurethane spray foam insulation composition of claim 9 further comprising a Part A, isocyanate, foam insulation composition comprising a Part B, polyol, foam insulation composition comprising ground mineral wool in the range of 10 to 45 weight percent, and water in the range of 2 to 35 weight percent.
“13. The open cell polyurethane spray foam insulation composition of claim 9 further comprising a flame retardant agent.
“14. The open cell polyurethane spray foam insulation composition of claim 13 wherein the flame retardant agent is an endothermic decomposition agent.
“15. The open cell polyurethane spray foam insulation composition of claim 14 wherein the flame retardant agent is magnesium hydroxide.
“16. The open cell polyurethane spray foam insulation composition of claim 15 wherein the flame retardant agent is magnesium hydroxide in the range of 2 to 40 weight percent.
“17. The open cell polyurethane spray foam insulation composition of claim 12 wherein the mineral wool char-promotion agent is a ground rock wool having a particle size of 1 to 595 microns.
“18. A method of using a ground mineral wool material to improve char-creation properties of a flammable material, the method comprising producing a powder by grinding a ceramic, glass, mineral, or slag mineral wool to a particle size of 1 to 595 microns; adding the powder to Part A or Part B of a isocyanate/polyol foam composition in a concentration range of 2 to 40 weight percent.
“19. The method of claim 6 further comprising creating a polyurethane foam from the Part A or Part B of a polyol/isocyanate foam composition.”
For additional information on this patent application, see: Stogner,
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