Pakan, Dwight (2231 Blue Bell Lane, Charlotte, NC, 28270, US)
Erdner, Seth (3118 Huntington Ridge Ct, Matthews, NC, 28105, US)
Pakan, Dwight (2231 Blue Bell Lane, Charlotte, NC, 28270, US)
| 1. | A method of controlling a fire consuming a combustible object comprising a step of applying a sufficient amount of a firefighting composition to the combustible object to retard, suppress, or extinguish the fire, said firefighting composition comprising : (a) about 0.01 % to about 20%, by weight, of a superabsorbent polymer ; (b) about 0.005% to about 10%, by weight, of a colorant ; (c) about 0.005% to about 10%, by weight, of an opacifying agent selected from the group consisting of a sparingly watersoluble inorganic com pound, a synthetic homopolymer or copolymer, and mixtures thereof; and (d) water. |
| 2. | A method of preventing a fire from consuming a combustible object comprising a step of applying a sufficient amount of a firefighting composition to the combus tible object to inhibit initiation of the fire, said fire fighting composition comprising: (a) about 0.01 % to about 20%, by weight, of a superabsorbent polymer ; (b) about 0.005% to about 10%, by weight, of a colorant ; (c) about 0.005% to about 10%, by weight, of an opacifying agent selected from the group consisting of a sparingly watersoluble inorganic com pound, a synthetic homopolymer or copolymer, and mixtures thereof; and (d) water. |
| 3. | The method of claim 1 or 2 wherein the colorant and the opacifying agent are present in a weight ratio of 1 part colorant to about 0.25 to about 5 parts opacify ing agent. |
| 4. | The method of one of the claims 1 to 3 wherein the opacifying agent and su perabsorbent polymer are present in a weight ratio of 1 part opacifying agent to about 1.5 to about 10 parts superabsorbent polymer. |
| 5. | The method of one of the claims 1 to 4 wherein the fire is a forest fire, a grass fire, a brush fire, or a wildfire. |
| 6. | The method of one of the claims 1 to 5 wherein the combustible objects com prises a manmade structure. |
| 7. | The method of one of the claims 1 to 6 wherein the superabsorbent polymer is present in an amount of about 0.05% to about 10%, by weight of the composi tion. |
| 8. | The method of one of the claims 1 to 7 wherein the superabsorbent polymer comprises a polymerized a, punsaturated carboxylic acid, or a salt or an anhy dride thereof. |
| 9. | The method of one of the claims 1 to 8 wherein the superabsorbent polymer is selected from the group consisting of poly (acrylic acid), a hydrolyzed starch acrylonitrile graft copolymer, a starchacrylic acid graft copolymer, a saponified vinyl acetateacrylic ester copolymer, a hydrolyzed acrylonitrile copolymer, a hydrolyzed acrylamide copolymer, an ethylenemaleic anhydride copolymer, an isobutylenemaleic anhydride copolymer, a poly (vinylsulfonic acid), a poly (vinylphosphonic acid), a poly (vinylphosphoric acid), a poly (vinylsulfuric acid), a sulfonate polystyrene, and salts and mixtures thereof. |
| 10. | The method of the claims 1 to 9 wherein the superabsorbent polymer is selected from the group consisting of a poly (vinylamine), a poly (dialkylaminoalkyl (meth) acrylamide), a polyethylenimine, a poly (allylamine), a poly (allylguanidine), a poly (dimethyidiallylammonium hydroxide), a quaternized polystyrene deriva tive, a guanidinemodified polystyrene, a quaternized poly ((meth) acrylamide) or ester analog, a poly (vinylguanidine), salts thereof, and mixtures thereof. |
| 11. | The method of one of the claims 1 to 10 wherein the superabsorbent polymer comprises polyacrylic acid neutralized about 50% to 100%. |
| 12. | The method of one of the claims 9 to 11 wherein the polyacrylic acid is neutral ized with sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, or a mixture thereof. |
| 13. | The method of one of the claims 1 to 12 wherein the colorant is present in an amount of about 0. 01 % to about 5%, by weight of the composition. |
| 14. | The method of one of the claims 1 to 13 wherein the colorant is a dye, a pigment, or a mixture thereof. |
| 15. | The method of one of the claims 1 to 14 wherein the colorant imparts a yellow, red, orange, violet, or blue color to the composition. |
| 16. | The method of one of the claims 1 to 15 wherein the colorant is selected from the group consisting of a direct dye, a basic dye, an acid dye, a reactive dye, a sol vent dye, a disperse dye, a leather dye, a natural dye, a sulfur dye, a vat dye, a synthetic pigment, a naturally occurring pigment, a security dye, and mixtures thereof. |
| 17. | The method of claim 16 wherein the colorant comprises a direct dye. |
| 18. | The method of claim 17 wherein the direct dye is selected from the group consist ing of Direct Red 81, Direct Red 239, Direct Red 254, Direct Yellow 11, Direct Yellow 6, Direct Yellow 127, Direct Orange 102, Direct Orange 102: 1, Direct Or ange 116, Direct Yellow 5, and mixtures thereof. |
| 19. | The method of the claims 17 or 18 wherein the colorant comprises Red 51 L, Orange 80LN, or Yellow 76LN. |
| 20. | The method of one of the claims 1 to 19 wherein the opacifying agent is present in an amount of about 0. 01% to about 5%, by weight of the compositions. |
| 21. | The method of one of the claims 1 to 20 wherein the opacifying agent is selected from the group consisting of calcium carbonate, a styrenebutadiene copolymer, a styrenevinylpyrrolidone copolymer, a styrenebutadieneacrylonitrile copoly mer, an acrylic polymer, a polyvinyl acetate, a polyvinyl acrylate, a starch, a polyethylenimine, a polystyrene, a polyethylene, a polyvinyl alcohol, and mixtures thereof. |
| 22. | The method of one of the claims 1 to 21 wherein the opacifying agent comprises calcium carbonate. |
| 23. | The method of one of the claims 1 to 22 wherein the opacifying agent comprises an emulsion or a latex of the synthetic homopolymer or copolymer. |
| 24. | The method of claim 23 wherein the opacifying agent comprises a polyethylen imine. |
| 25. | The method of one of the claims 1 to 24 wherein the composition further com prises up to about 10%, by weight, of a water soluble organic solvent. |
| 26. | The method of one of the claims 1 to 25 wherein the composition further com prises one or more optional ingredient selected from the group consisting of a viscosity modifier, a dispersant, a pH modifier, a surfactant, and mixtures thereof. |
| 27. | The method of one of the claims 1 to 26 wherein the composition imparts a color to the combustible object. |
| 28. | The method of claim 27 wherein the color imparted to the combustible object substantially fades within 30 days after application of the composition. |
| 29. | The method of claim 27 or 28 wherein the color imparted to the combustible ob ject is of sufficient intensity such that a combustible object having the composi tion applied thereto is differentiated from the combustible object that lacks on ap plication of the composition by a naked eye. |
| 30. | The method of one of the claims 1 to 29 wherein the composition is applied by ground equipment or by aerial equipment. |
| 31. | A composition comprising (a) about 0.1 % to about 5%, by weight, of a superabsorbent polymer ; (b) about 0. 015% to about 2%, by weight, of a colorant ; (c) 0.015% to about 2%, by weight, of an opacifying agent selected from the group consisting of a sparingly watersoluble inorganic compound, a syn thetic homopolymer or copolymer, and mixtures thereof; and (d) water. |
| 32. | The composition of claim 31 further comprising up to about 10%, by weight, of a watersoluble organic solvent. |
| 33. | The composition of claim 31 or claim 32 further comprising one or more optional ingredient selected from the group consisting of a viscosity modifier, a dispers ant, a pH modifier, a surfactant, and mixtures thereof. |
| 34. | The composition of one of the claims 31 to 33 wherein the colorant and the opacifying agent are present in a weight ratio of 1 part colorant to about 0.5 to about 3 parts opacifying agent. |
| 35. | The composition of one of the claims 31 to 34 wherein the opacifying agent and the superabsorbent polymer are present in a weight ratio of 1 part opacifying agent to about 2 to 4 parts superabsorbent polymer. |
The fire-fighting composition comprises a superabsorbent polymer (SAP), a colorant, an opacifying agent, and water. The method comprises applying a sufficient amount of the aqueous fire-fighting composition to natural or man-made combustible objects, ei- ther before or after initiation of combustion, to prevent, retard, suppress, or extinguish a fire.
BACKGROUND OF THE INVENTION Water is the material of choice to extinguish most fires or to prevent combustible ob- jects from burning. Water predominantly is supplied from a network of pipes or, in the case of a forest fire, for example, from natural waters. In fire fighting, water contacts burning objects which results in sufficient cooling such that the burning objects fall be- low their combustion or ignition temperature, and new ignition is precluded. In addition, when water contacts hot objects, the water vaporizes to produce steam, which expands and expels the air necessary for combustion.
When a fire is extinguished by spraying water on the fire, less than 10% of the sprayed water is effective because of water loss, such as by run-off or evaporation. This is par- ticularly disadvantageous in the case of forest fires and wildfires because a consider- able portion of the water often is transported a long distance at a great expense, and then is wasted. To date, it has not been possible to make optimum use of water in for- est fires and wildfires because such fires are frequently preceded by a period of drought and, accordingly, the ground has a particularly high water absorptive capacity.
The waste of water is a very important aspect of forest fire fighting because a forest fire typically consumes the dry undergrowth (e. g. , grass, foliage, and heather) and leads to individual crown fires which then unite.
The problem of ineffective water usage also is encountered in other types of fires, for example, when a roof of a building is on fire. In this case, the water often reaches the lower stories of the building through floors, openings, and staircases, for example, and is thereby lost for fire fighting purposes. This creates a potential lack of water, such that the fire spreads from the burning roof downwards. In addition, the water running off to lower stories frequently results in considerable water damage.
Forest fires and brush fires annually cause the loss of millions of dollars worth of timber and other property. Extensive damage often occurs because by the time the fire is de-
tected, and before control measures can be applied, the fire is out of control in a condi- tion known as a"wildfire The direct property loss due to such fires is catastrophic, and the associated soil erosion and watershed problems also are significant. It is important, therefore, to minimize and control the spread of forest fires whenever possible.
Another problem encountered in fighting a forest fire is an inability to precisely deter- mine which objects, or areas, have been sprayed and which have not. This is an espe- cially difficult problem encountered in the aerial firefighting of forest fires. Effective fire fighting requires that all objects or areas of interest are sprayed, while minimizing dou- ble spraying of some objects or areas.
In order to improve the action of water when fighting a forest fire, thickened water or water containing a chemical fire retardant has been applied to timber and other foliage in the path of a fire to retard advancement of the flame front. Various methods of dis- tributing the water, including direct spraying and aerial dropping, have been employed.
Aerial dropping is advantageous because areas that are not easily accessible can be sprayed.
There are two types of fire retardants commonly employed in fighting forest, range, grass, and brushland wildfires. These fire retardants are classified as"short-term"or "long-term"retardants. Short-term retardants rely primarily upon water to retard com- bustion. Long-term retardants contain, in addition to water, a water-soluble chemical that effectively retards combustion for brief periods even after the water has evapo- rated.
The present invention is directed to compositions and methods of preventing, retarding, suppressing, and extinguishing fires by applying a sufficient amount of an aqueous composition containing an SAP, a colorant, and an opacifying agent to combustible objects, either before or after initiation of combustion.
Prior patents have disclosed the use of an SAP in the control of fires, for example, U. S.
Patent Nos. 5,190, 110 and 5,849, 210. U. S. Patent No. 3,354, 084 discloses a composi- tion containing (a) an SAP, (b) a nonionic, water-insoluble solid, and (c) an optional nonionic or anionic water-soluble dye. The water-insoluble solid increases the viscosity of an SAP hydrogel for improved firefighting. It is essential that an aqueous dispersion of the insoluble solid has a resistivity of at least about 50,000 ohms, or the gel capacity of the SAP is diminished. The insoluble solids disclosed in U. S. Patent No. 3,354, 084 are essentially totally water insoluble and include titanium dioxide, silica gel, powdered aluminum, and calcium silicate, for example. The sole optional dye disclosed in U. S.
Patent No. 3,354, 084 is rhodamine B.
European Patent Application 0 649 669 A1 discloses a fire extinguishing medium con- taining (a) an SAP, (b) a substance having a large surface structure, a capillary struc- ture, or a fibrous structure, and (c) an optional biodegradable dye. The substances of component (b) are water-insoluble materials, like sawdust, cellulose, kieselguhr, ground plastics, ground foamed plastics, and hydrophobic silicon dioxide. This Euro- pean application fails to disclose any specific dyes.
SUMMARY OF THE INVENTION The present invention is directed to compositions and methods of preventing a com- bustible object from burning, and of controlling combustion of a burning combustible object, by contacting the combustible object, before or during combustion, with an aqueous fire-fighting composition comprising a water-insoluble SAP, a colorant, and an opacifying agent. The present method is especially useful in preventing, retarding, sup- pressing, and/or extinguishing a forest fire or wildfire.
Accordingly, one aspect of the present invention is to provide an aqueous composition that can be applied to grass, foliage, brush, trees, and similar vegetation, either before or after a fire has started. Another aspect of the present invention is to provide a fire- fighting composition that can be effectively applied using ground spray equipment, a helicopter or airplane, or other means known to firefighters.
Another aspect of the present invention is to provide a composition and method of con- trolling wildfires, wherein previously treated fire zone areas are readily distinguished from untreated fire zone areas, from both aerial and land application equipment.
Still another aspect of the present invention is to provide a fire-fighting composition comprising: (a) about 0. 01% to about 20%, by weight, of an SAP; (b) about 0.005% to about 10%, by weight, of a colorant ; (c) about 0.005% to about 10%, by weight, of an opacifying agent; (d) water; and (e) optional ingredients. Typically, the colorant and opacifying agent are present in the composition in a weight ratio of 1 part colorant to about 0.25 to about 5 parts opacifying agent, and preferably 1 part colorant to about 0.5 to about 3 parts opacifying agent. The colorant and SAP generally are present in a weight ratio of 1 part colorant to about 1.5 to about 10 parts SAP. The opacifying agent and SAP generally are present in a weight ratio of 1 part opacifying agent to about 1.5 to about 10 parts SAP, and preferably 1 part opacifying agent to about 2 to about 4 parts SAP.
Yet another aspect of the present invention is to provide a fire-fighting composition and method wherein combustible objects treated with the composition are readily visible to the naked eye, thereby effectively precluding a second application of the composition
to previously treated combustible objects and effectively insuring that all combustible objects of interest have been treated.
Another aspect of the present invention is to provide a fire-fighting composition and method wherein visible indicia of treatment of a combustible object are substantially reduced to the naked eye about thirty days or less after treatment.
Further aspects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments, taken in conjunction with the examples and the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As used herein, the terms"fire-fighting"and"controlling a fire"are defined as extin- guishing, suppressing, and/or retarding combustion of objects on fire, and/or preventing combustible objects from igniting. The combustible objects can be naturally occurring, e. g. , brush, grass, trees, and the like, or can be man-made, e. g., buildings, platforms, and the like.
In one embodiment, the present invention is directed to a method of controlling com- bustion of a combustible object, particularly a forest fire or a wildfire, comprising apply- ing a sufficient amount of a fire-fighting composition, either before or after fire initiation, to the combustible object to prevent, suppress, retard, and/or extinguish the fire, wherein the composition comprises an SAP, a colorant, an opacifying agent, and wa- ter.
In another embodiment, the present invention is directed to a fire-fighting composition useful in preventing, suppressing, extinguishing, and/or retarding the progression of a fire comprising (a) an SAP, (b) a colorant, (c) an opacifying agent, (d) water, and (e) optional ingredients known to persons skilled in the art. The present invention also is directed to a concentrated fire-extinguishing composition wherein two or more of ingre- dients (a), (b), (c), and (e) are premixed prior to solution or dispersion in water. Alterna- tively, ingredients (a), (b), (c), and (e) can be added to water individually to provide a composition of the present invention.
Various embodiments of the present invention, and a nonlimiting description of the components of the present fire-fighting composition, follow.
SUPERABSORBENT POLYMER (SAP) In general, a present fire-fighting composition contains an SAP in an amount such that sufficient free water is present to provide an excellent fire extinguishing effect with mi-
minimum damage caused by water, and to allow its application while ensuring a very good wetting capacity, analogous to that of pure water.
More particularly, an SAP is present in the fire-fighting composition in an amount of about 0. 01 % to about 20%, and preferably about 0.05% to about 10%, by weight of the composition. To achieve the full advantage of the present invention, the composition contains about 0. 1 % to about 5% SAP, by weight of the composition. The weight per- cent SAP in a present composition is the amount of unhydrated SAP particles used to provide the final composition.
An SAP is a water-absorbing resin. SAPs are widely used in sanitary and hygienic goods, wiping cloths, water-retaining agents, dehydrating agents, sludge coagulants, disposable towels and bath mats, disposable door mats, thickening agents, disposable litter mats for pets, condensation-preventing agents, and release control agents for various chemicals. SAPs are available in a variety of chemical forms, including substi- tuted and unsubstituted natural and synthetic polymers, such as hydrolysis products of starch acrylonitrile graft polymers, carboxymethylcellulose, crosslinked polyacrylates, crosslinked and partially neutralized copolymers of isobutylene and maleic anhydride, saponification products of vinyl acetate-acrylic acid copolymer, sulfonate polysty- renes, hydrolyzed polyacrylamides, polyvinyl alcohols, polyethylene oxides, polyvi- nylpyrrolidones, and polyacrylonitriles.
These polymers, and others, are known in the art by various names, such as superab- sorbent polymers, hydrogels, hydrocolloids, and water-absorbent hydrophilic polymers, for example. As used herein, the term"SAP"refers to a superabsorbent polymer, and collectively refers to such water-absorbing materials. The term"SAP particles"refers to superabsorbent polymer particles in the dry state, more specifically, particles contain- ing from no water up to an amount of water less than the weight of the particles, and typically less than about 5%, by weight, water. The terms"SAP gel,""SAP hydrogel,"or "hydrogel"refer to a superabsorbent polymer in the hydrated state, more specifically, particles that have absorbed at least their weight in water, and typically several times their weight in water.
SAPs are lightly crosslinked hydrophilic polymers, and are discussed generally in U. S.
Patent Nos. 5,669, 894 and 5,559, 335, each incorporated herein by reference. SAPs can differ in their chemical identity, but all SAPs are capable of absorbing and retaining amounts of aqueous fluids equivalent to many times their own weight, even under mo- derate pressure. For example, SAPs can absorb one hundred times their own weight, or more, of distilled water.
An SAP typically is neutralized at least about 25 mole percent, preferably at least about 50 mole percent, and usually about 70 to 80 mole percent, to achieve optimum absor-
bency. Neutralization can be achieved by neutralizing the acrylic acid monomer before polymerization of the monomer, or the polymer can be neutralized after the polymeriza- tion reaction is substantially complete. After polymerization and internal crosslinking of the monomer, followed by partial neutralization, e. g. , 50-100 mole percent neutraliza- tion, preferably 70 to 80 mole percent neutralization, the polymer is subdivided, e. g., shredded or chopped, for more efficient drying, then dried and milled to a desired parti- cle size. The polymer preferably then is surface crosslinked and again dried to form the final product.
An SAP used in the composition and method of the present invention is limited only in that the SAP is capable of absorbing several times its weight of an aqueous fluid and swells to form a hydrogel. The SAP can be an acidic water-absorbing resin or a basic water-absorbing resin. Monomers useful in the preparation of an SAP are disclosed in U. S. Patent No. 5,149, 750 and WO 01/68156, each incorporated herein by reference.
The SAP component of the present fire-extinguishing composition comprises an acidic or a basic water-absorbing resin neutralized about 25% to about 100%, i. e. , has a de- gree of neutralization (DN) of about 25 to about 100.
The SAP can be anionic (an acidic water-absorbing resin) or cationic (a basic water- absorbing rein) in nature. The anionic SAPs are based on an acidic water-absorbing resin. The anionic SAPs, either strongly acidic or weakly acidic, can be any resin that acts as an SAP in its neutralized form. The acidic resins typically contain a plurality of carboxylic acid, sulfonic acid, phosphonic acid, phosphoric acid, and/or sulfuric acid moieties.
A preferred SAP is an acidic water-absorbing resin neutralized 25% to 100%. The aci- dic water-absorbing resin can be a single resin or a mixture of resins. The acidic resin can be a homopolymer or a copolymer. The identity of the acidic water-absorbing resin is not limited as long as the resin is capable of swelling and absorbing at least ten ti- mes its weight in water, when in a neutralized form.
The acidic water-absorbing resin typically is a lightly crosslinked acrylic resin, such as lightly crosslinked poly (acrylic acid). The lightly crosslinked acidic resin typically is pre- pared by polymerizing an acidic monomer containing an acyl moiety, e. g., acrylic acid, or a moiety capable of providing an acid group, i. e., acrylonitrile, in the presence of an internal crosslinking monomer, i. e. , a polyfunctional organic compound. The acidic resin can contain other copolymerizable units, i. e. , other monoethylenically unsaturated comonomers, well known in the art, as long as the polymer is substantially, i. e. , at least 10%, and preferably at least 25%, acidic monomer units. To achieve the full advantage of the present invention, the acidic resin contains at least 50%, and more preferably, at least 75%, and up to 100%, acidic monomer units.
Ethylenically unsaturated carboxylic acid and carboxylic acid anhydride monomers use- ful in the acidic water-absorbing resin include acrylic acid, methacrylic acid, ethacrylic acid, a-chloroacrylic acid, a-cyanoacrylic acid, ß-methylacrylic acid (crotonic acid), a- phenylacrylic acid, ß-acryloxy-propionic acid, sorbic acid, a-chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamic acid, ß-stearylacrylic acid, itaconic acid, citra- conic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, furmaric acid, tricarboxyethylene, and maleic anhydride. Acrylic acid is the most preferred ethylen- cally unsaturated carboxylic acid for preparing the SAP.
Ethylenically unsaturated sulfonic acid monomers include aliphatic and aromatic vinyl sulfonic acids, such as vinyl sulfonic acid, allyl sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, acrylic and methacrylic sulfonic acids, such as sulfoethyl acrylate, sulfoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3- methacryloxypropyl sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid.
Phosphate-containing acidic resins are prepared by homopolymerizing or copolymeriz- ing ethylenically unsaturated monomers containing a phosphoric acid moiety, such as methacryloxy ethyl phosphate. An extensive list of suitable SAP-forming monomers can be found in U. S. Patent No. 4,076, 663, incorporated herein by reference.
The anionic SAPs can be, for example, a poly (acrylic acid), a hydrolyzed starch- acrylonitrile graft copolymer, a starch-acrylic acid graft copolymer, a saponified vinyl acetate-acrylic ester copolymer, a hydrolyzed acrylonitrile copolymer, a hydrolyzed acrylamide copolymer, an ethylene-maleic anhydride copolymer, an isobutylene-maleic anhydride copolymer, a poly (vinylsulfonic acid), a poly (vinyl-phosphonic acid), a poly (vinylphosphoric acid), a poly (vinylsulfuric acid), a sulfonated polystyrene, and mix- tures thereof. The preferred anionic SAP is a poly (acrylic acid).
The polymerization of acidic monomers, and copolymerizable monomers, if present, most commonly is performed by free radical processes in the presence of a polyfunc- tional internal crosslinking monomer. The acidic resins are crosslinked to a sufficient extent such that the polymer is water insoluble. Crosslinking renders the acidic resins substantially water insoluble, and, in part, serves to determine the absorption capacity of the resins. For use in absorption applications, an acidic resin is lightly crosslinked, i. e. , has a crosslinking density of less than about 20%, preferably less than about 10%, and most preferably about 0. 01 % to about 7%. An internal crosslinking monomer most preferably is used in an amount of less than about 7 wt%, and typically about 0.1 wt% to about 5 wt%, based on the total weight of monomers.
Examples of internal crosslinking monomers include, but are not limited to, polyacrylic (or polymethacrylic) acid esters represented by the following formula (I), wherein x is ethylene, propylene, trimethylene, cyclohexyl, hexamethylene, 2- hydroxypropylene,- (CH2CH20) nCH2CH2- or wherein n and m, independently, are an integer 5 to 40, and k is 1 or 2; and bisacryla- mides, represented by the following formula (II), CH2=CH-C (=O)-NH (CH2CH2NH), C (=O)-CH=CH2 (ici) wherein I is 2 or 3.
The compounds of formula (I) are prepared by reacting polyols, such as ethylene gly- col, propylene glycol, trimethylolpropane, 1, 6-hexanediol, glycerin, pentaerythritol, po- lyethylene glycol, or polypropylene glycol, with acrylic acid or meth-acrylic acid. The compounds of formula (II) are obtained by reacting polyalkylene polyamines, such as diethylenetriamine and triethylenetetramine, with acrylic acid. Specific crosslinking monomers are disclosed in U. S. Patent No. 6,222, 091, incorporated herein by refer- ence. Especially preferred crosslinking agents are pentaerythritol triallyl ether, pentae- rythritol triacrylate, N, N'-methylenebisacrylamide, N, N'-methylenebismethacrylamide, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate.
Analogous to the acidic resin, a basic water-absorbing resin, i. e. , cationic SAP, useful in the present SAP-clay particles can be a strong or weak basic water-absorbing resin.
The basic water-absorbing resin can be a single resin or a mixture of resins. The basic resin can be a homopolymer or a copolymer. The identity of the basic resin is not lim- ited as long as the basic resin is capable of swelling and absorbing at least 10 times its weight in water, when in a charged form. The weak basic resin preferably is present in its cationic form, i. e. , about 25% to 100% of the basic moieties, e. g. , amino groups, are present in a charged form. The strong basic resins typically are present in the hydrox- ide (OH) or bicarbonate (HCO3) form.
The basic water-absorbing resin typically is a lightly crosslinked resin, such as a poly (vinylamine) or a poly (dialkylaminoalkyl (meth) acrylamide). The basic resin also can be, for example, a lightly crosslinked polyethylenimine, a poly (allylamine), a poly (allylguanidine), a poly (dimethyldiallylammonium hydroxide), a quaternized polysty- rene derivative, a guanidine-modified polystyrene, a quaternized poly ( (meth) acryl- amide) or ester analog. See U. S. Patent No. 6,235, 965, incorporated herein by refer- ence. The lightly crosslinked basic water-absorbing resin can contain other copoly- merizable units and is crosslinked using an internal crosslinking monomer, as set forth above with respect to the acidic water-absorbing resin. Preferred basic resins include a poly (vinylamine), polyethylenimine, poly (vinylguanidine), poly (dimethylaminoethyl acryl- amide) (poly (DAEA) ), and poly (dimethylaminopropyl methacrylamide) (poly- (DMAPMA) ).
A basic water-absorbing resin used in the present SAP particles typically contains an amino or a guanidino group. Accordingly, a water-soluble basic resin also can be crosslinked in solution by suspending or dissolving an uncrosslinked basic resin in an aqueous or alcoholic medium, then adding a di-or polyfunctional compound capable of crosslinking the basic resin by reaction with the amino groups of the basic resin. Such crosslinking agents are disclosed in U. S. Patent No. 6,235, 965, incorporated herein by reference. Crosslinking agents also are disclosed in U. S. Patent No. 5,085, 787, incor- porated herein by reference, and in EP 450 923. Preferred crosslinking agents are eth- ylene glycol diglycidyl ether (EGDGE), a water-soluble diglycidyl ether, and a dibro- moalkane, an alcohol-soluble compound.
Copolymerizable monomers for introduction into the acidic resin or the basic resin, in- clude, but are not limited to, ethylene, propylene, isobutylene, C, 1alkyl acrylates and methacrylates, vinyl acetate, methyl vinyl ether, and styrenic compounds having the formula : wherein R represents hydrogen or a C16alkyl group, and wherein the phenyl ring op- tionally is substituted with one to four C11alkyl or hydroxy groups.
Suitable C, 4alkyl acrylates include, but are not limited to, methyl acrylate, ethyl acry- late, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, and the like, and mixtures thereof. Suitable C, 4alkyl methacrylates include, but are not limited to, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-
butyl methacrylate, and the like, and mixtures thereof or with C, 4alkyl acrylates. Suit- able styrenic compounds include, but are not limited to, styrene, a-methylstyrene, p- methylstyrene, t-butyl styrene, and the like, and mixtures thereof or with C, 4alkyl acry- lates and/or methacrylates.
Any polymerization initiator known for use in preparing SAPs can be used. Examples of useful initiators are redox and thermal initiators, such as those disclosed in U. S. Patent No. 6,359, 049, incorporated herein by reference. The redox and thermal initiators can be used singly or in suitable combination. Of these, especially preferred initiators are a redox initiator comprising ammonium persulfate and sodium hydrogen sulfite, and azo initiators, such as azobisisobutyronitrile and 2,2'-azobis (2-amidinopropane) dihydro- chloride, commercially available under the tradename V-50 from Wako Chemicals U. S. A., Inc., Richmond, Virginia. The initiator typically is used in an amount, calculated as solids, of about 0. 1 % to about 10%, based on the weight of the acrylic acid mono- mer, preferably about 0.5% to about 5%, based on the weight of the monomer. De- pending on the amount and kind of the initiator, the initiator optionally can be used to- gether with isopropyl alcohol, an alkyl mercaptan, or other chain transfer agent to con- trol the molecular weight of the poly (acrylic acid).
Ultraviolet (UV) light also can be used to effect polymerization of acrylic acid. UV light can be used in conjunction with a redox initiator and/or a free radical initiator. When UV light is utilized in the polymerization step, a photoinitiator also is added to the reaction mixture in an amount well known to persons skilled in the art. Suitable photoinitiators include, but are not limited to, 2-hydroxy-1- [4- (hydroxyethyoxy) phenyl]-2-methyl-1- propanone, which is commercially available from Ciba Additives of Hawthorne, New York, as IRGACURE 2959, and 2-hydroxy-2-methyl-1-phenyl-1-propanone, which also is commercially available from Ciba Additives as DAROCUR 1173.
Industrial processes useful for preparing the SAP component include all processes customarily used to synthesize SAPs, as described, for example, in Chapter 3 of"Mo- dern Superabsorbent Polymer Technology, "F. L. Buchholz and A. T. Graham, Wiley- VCH (1998). A suitable process for polymerizing the acrylic acid is aqueous solution polymerization, wherein an aqueous solution containing acrylic acid and polymerization initiator is subjected to a polymerization reaction and a crosslinking reaction by the addition of an internal crosslinking monomer, such as methylenebisacrylamide.
A preferred SAP in a fire-fighting composition of the present invention is neutralized poly (acrylic acid). The poly (acrylic acid) typically is neutralized to DN about 65 to a- bout 80. Preferably, the neutralizing agent is sodium hydroxide, sodium carbonate, potassium hydroxide, or potassium carbonate. Most preferably, the neutralizing agent is potassium hydroxide or potassium carbonate, i. e. , the SAP component of the fire- fighting composition is a partially neutralized, lightly crosslinked potassium polyacry- late.
COLORANT In addition to the SAP, the present method and composition utilize a colorant. The col- orant is present in the composition to visibly identify combustible objects treated by the present method and composition. The visual effect of the colorant essentially precludes a double application of the composition to some combustible objects, while helping ensure that all combustible objects of interest are treated.
Therefore, incorporation of a colorant in a present fire-fighting composition is an impor- tant feature of the present invention. The colorant can be a dye or a pigment. The amount of colorant used in the method and composition of the present invention is suf- ficient to render various combustible objects (e. g. , trees, grass, brush, or man-made objects, such as buildings or cars) treated by the fire-fighting composition visible to the naked eye.
The colorant component of the present compositions and methods allows the fire fight- ers to visually determine treated areas and application coverage rates of the combusti- ble objects. For example, from the shade, tone, and intensity of the color of the treated combustible objects, fire fighters can determine whether a sufficient amount of the fire- fighting composition has been applied to the combustible objects.
A colorant incorporated in a present fire-fighting composition is limited only in that its color is in contrast to the color of the combustible objects being treated, and that the dye is soluble or dispersible in the fire-fighting composition. It is important that the col- orant is distributed throughout the composition to ensure a relatively even distribution of the colorant on the treated combustible objects.
Typically, the color intensity of the colorant is essentially unchanged for several days after application until the fire-fighting composition dries on the combustible material.
Drying typically occurs about five to seven days after application of the fire-fighting composition. After drying, the color intensity of the colorant begins to fade.
In a preferred embodiment, the colorant also is degradable or otherwise removable (e. g., rinsable) from treated combustible objects within about 30 days after application of the fire-fighting composition. In this embodiment, combustible objects that are un- burned or merely partially burned substantially return to their natural color within about one month after application of the fire-fighting composition. Alternatively stated, the color imparted to the combustible object substantially fades, i. e., loses at least 50% of its color intensity, within 30 days after application of the composition. In embodiments, wherein the fire-fighting compound is applied to vegetation, it is preferred that the col- orant is nonherbicidal and otherwise nonharmful to the environment.
The amount of colorant present in a composition of the present invention is such that a desired color and shade are imparted to treated combustible objects after application of the fire-fighting composition. Preferably, the colorant is present in a composition of the present invention in an amount of about 0.005% to about 10%, by weight of the com- position. More preferably, the colorant is present in an amount of about 0. 01 % to about 5%, by weight of the composition. To achieve the full advantage of the present inven- tion, the colorant is present in an amount of about 0.015% to about 2%, by weight of the composition.
Colorants that can be used in the method and composition of the present invention include, but are not limited to, a direct dye, a basic dye, an acid dye, a reactive dye, a solvent dye, a disperse dye, a leather dye, a natural dye, a sulfur dye, a vat dye, a syn- thetic pigment, a naturally occurring pigment, a security dye, or mixtures thereof. Pref- erably, the colorant is a direct dye.
Specific classes of colorants useful in the present invention include the ANTHOSIN@, BASACID@, BASANTOL@, BASAZOL@, BASOVIT@, and FASTUSOL# classes of color- ants, all of which are available from BASF AG, Ludwigshafen, Germany.
Typically, colorants useful in the present invention impart a red, yellow, orange, violet, or blue color to combustible objects treated by the method and composition of present invention. Accordingly, specific colorants useful in the present invention include, but not limited to, (a) acid dyes, e. g., ANTHOSINe Orange 35L ANTHOSINs Red 49L ANTHOSINO Yellow 47L ANTHOSINs Yellow 57L; (b) basic dyes, e. g., BASAZOL"Red 71 L BASAZOL Violet 45L BASAZOL# Violet 47L BASAZOL# Violet 49L BASAZOLO Violet 57L BASAZOL# Violet 94L BASAZOLs Yellow 40L BASAZOLO Yellow 46L
(c) direct dyes, e. g., FASTUSOL# Blue 31 L FASTUSOL# Yellow 70L FASTUSOL# Blue 47L FASTUSOL# Yellow 76LN FASTUSOL# Blue 79L FASTUSOL# C Blue 49LS FASTUSOL# Orange 49L FASTUSOL# C Blue 76L FASTUSOL# Orange 80LN NB 70% FASTUSOL# Orange PR268L FASTUSOL# C Blue 77LS FASTUSOL# Red 43LN FASTUSOL# C Blue FASTUSOL# Red 45L PR929L 200% FASTUSOL# Red 50L FASTUSOL# Red 32L FASTUSOL# Red 50L 150% FASTUSOL# C Red 61 L FASTUSOL# Red 51 L FASTUSOLs C Violet 04 FASTUSOL# Red 53L 25% FASTUSOL# Violet 08L FASTUSOL# C Violet 92 FASTUSOL# Yellow 14L FASTUSOL# Yellow 36LV FASTUSOL# Yellow 30L FASTUSOL# C Yellow FASTUSOLe Yellow 49L 97L FASTUSOLs Yellow 66L (d) additional colorants, e. g., BASANTOL# Orange 273 <BR> <BR> BASANTOLs Red 311 <BR> <BR> <BR> <BR> BASANTOLs Yellow 099 BASANTOL# Yellow 215 BASONYLe Yellow 105 BASONYL# Orange 204 BASONYL# Red 482 BASONYL# Red 482 Low-Dust BASONYL# Red 483 BASONYL Red 485 BASONYL# Red 540 BASONYL# Red 545 Liquid BASONYL# Red 555 Liquid BASONYL# Red 560 BASONYLe Violet 600 BASONYL# Violet 602 Liquid BASONYL# Violet 609 Liquid BASONYL# Violet 610 BASONYL# Blue 636
BASONYLs Blue 640 BASONYLO Blue 644 Liquid BASACIDs Yellow 094 BASACIDO Yellow NB 132 Liquid BASACIDs Yellow NB 216 Liquid BASACID@ Yellow 226 BASACIDO Orange NB 282 Liquid BASAC) Red 316 BASACID"Red NB 384 Liquid BASACIDO Red NB 391 Liquid BASACID"Red NB 432 Liquid 150% BASACID"Red 495 Liquid BASACIDs Red NB 510 Liquid BASACIIDP Blue 762 Liquid For use in forest fires and wildfires, the preferred colorants impart a yellow, red, or or- ange color to treated foliage. Various useful colorants include, but are not limited to, Direct Red 81, Direct Red 239, Direct Red 254, Direct Yellow 11, Direct Yellow 6, Di- rect Yellow 127, Direct Orange 102, Direct Orange 102: 1, Direct Orange 116, and Di- rect Yellow 5, available from BASF Corporation, Mount Olive, NJ.
PACIFYING AGENTS In addition to the SAP and colorant, a present fire-fighting composition contains an opacifying agent. The opacifying agent is included to improve the visual effect of the colorant. For some colorants, and in some applications, combustible objects treated with a composition lacking an opacifying agent are somewhat difficult to observe, es- pecially from the air. The presence of an opacifying agent improves the visibility of the applied fire-fighting composition. The amount of opacifying agent included in a present fire-fighting composition is sufficient to provide an opaque composition, which improves the visibility of the fire-fighting composition after application to combustible objects.
The opacifying agent can be organic or inorganic in chemical composition. In particular, the opacifying agent comprises an inorganic compound an organic polymeric material, or a mixture thereof. The opacifying agent typically is white or off-white in color. The opacifying agent renders an SAP hydrogel opaque, and thereby increases the visibility of an SAP hydrogel after application to combustible objects.
An inorganic opacifying agent used in the present composition is a sparingly water- soluble compound. As used herein, the term"sparingly water soluble"is defined as an inorganic material having a water solubility, in its anhydrous form, of about 0.0005 to
about 0.005 grams per 100 ml of water at 25°C. An organic polymeric opacifying agent is a synthetic homopolymer or copolymer, preferably dispersed in water to form an emulsion or a latex.
The opacifying agent, therefore, can be, but is not limited to, calcium carbonate (CaCO3), a styrene-butadiene copolymer, a styrene-vinylpyrrolidone copolymer, a sty- rene-butadiene-acrylonitrile copolymer, an acrylic polymer, a polyvinyl acetate, a poly- vinyl acrylate, a starch, a polystyrene, a polyethylenimine, a polyethylene, a polyvinyl alcohol, or a mixture thereof. Preferably, the opacifying agent is a synthetic organic homopolymer or copolymer, more preferably dispersed in water as an emulsion or a latex for ease of incorporation into a present fire-fighting composition.
The amount of opacifying agent present in a fire-fighting composition is 0.005% to about 10%, by weight, of the composition. Preferably, the opacifying agent is present in the composition at about 0. 01 % to about 5%, by weight of the composition. To achieve the full advantage of the present invention, the opacifying agent is present in an amount of about 0.015% to about 2%, by weight of the composition. Typically, the a- mount of opacifying agent is present in the composition in a sufficient amount such that a desired opacity level and color intensity are provided after application of the composition to combustible objects.
WATER The carrier of the present fire-fighting composition is water. However, small amounts of an organic solvent, i. e. , up to about 10%, for example, about 0. 01% to about 10%, by weight of the composition, optionally can be included in the composition to facilitate manufacture of the composition, or provide other beneficial properties, such as ease of application of the composition. The organic solvent is water soluble, and can be for example, an alcohol, a diol, a polyol, a glycol ether, or a mixture thereof.
OPTIONAL INGREDIENTS A fire-fighting composition of the present invention also can include optional ingredients known to persons skilled in the art. Each optional ingredient, if present at all, is in- cluded in the composition in a sufficient amount to perform its intended function without adversely effecting the composition or its use as a fire prevention, suppressing, retard- ing, or extinguishing agent. Typically, each optional ingredient is present in an amount of up to about 10%, by weight, of the composition, and, in total, the optional ingredients are present up to about 30%, by weight, of the composition. For example, the composi- tion can include one or more of a viscosity modifier, a dispersant, a pH modifier, and a surfactant.
Viscosity modifiers optionally are included in the composition of the present invention to stabilize the composition, as well as improve the application properties of the composi- tion. Viscosity modifiers include, but are not limited to, associative thickeners, alkali swellable thickeners, alkali soluble thickeners, polymeric thickeners, and mixtures thereof. Specific examples of viscosity modifiers include, but are not limited to, polyvi- nyl alcohol, a water-soluble or water-dispersible cellulose derivative, such as hy- droxyethyl cellulose, hydroxypropyl cellulose and sodium carboxymethylcellulose, a polyether, a urethane-modified polyether, a polycarboxylic acid, a polyvinylpyrrolidone, a polyoxyethylene derivative, such as a polyethylene glycol ether or a polyethylene glycol distearate, sodium alginate, and mixtures thereof.
If needed or desired, a dispersant can be added to stabilize the composition and im- prove application properties. Useful dispersants include, but are not limited to, inor- ganic dispersing agents, such as a sodium salt of a polycarboxylic acid, a sodium or ammonium salt of a fused naphthalene sulfonate, a polyoxyalkylene alkyl ether of phe- nol ether, a sorbitan fatty acid ester, a polyoxyalkylene fatty acid ester, a glycerin fatty acid ester, a polyoxyethylene styrene phenol, sodium tripolyphosphate, sodium hexa- metaphosphate, an organosilanol derivative of tung oil or linseed oil, high erucic acid rapeseed oil, and mixtures thereof.
The composition, optionally, can further include a pH adjusting agent to provide a de- sired pH value. Corrosion of fire-fighting apparatus and objects sprayed for fire protec- tion can be minimized or avoided by adjusting the pH of the fire-fighting composition to about 6 to about 8. The pH adjusting agent can be any pH adjusting agent that pro- vides the desired pH. The pH adjusting agent typically is a base. Examples of pH ad- justing agents include, but are not limited to, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, ammonium hy- droxide, ammonia, an amine, triethanolamine, 3-dimethylaminoethanol, and mixtures thereof.
A surfactant also can be included in the composition to improve the application proper- ties of the composition. The surfactant can be an anionic, a nonionic, or an ampholytic surfactant.
To manufacture a fire-fighting composition, an SAP, a colorant, an opacifying agent, and any other optional ingredients are admixed with water and an optional organic sol- vent. The ingredients can be individually added to the water. One or more ingredient also can be predissolved or predispersed in an organic solvent prior to addition to wa- ter. In addition, the colorant can be admixed with the opacifying agent and/or SAP to form a premix that then can be added to the water. Alternatively, the colorant and opacifying agent can be admixed, then added to the water or a preformed SAP hy- drogel.
Also envisioned is a concentrated premix that can be added to water to provide a fire- fighting composition of the present invention. The concentrated premix comprises at least two of the SAP, colorant, and opacifying agent, in predetermined desired amounts, for addition to a proper amount of water to provide a present fire-fighting composition. The concentrated premix also can include one or more of the optional ingredients. The water can include an organic solvent as disclosed above.
A present fire-fighting composition is effective because it immobilizes water where the water is needed, i. e. , on a combustible object, and excludes oxygen from the surface of the combustible object. The composition functions by forming a relatively gas- impermeable barrier on the surface of combustible objects, which prevents, or substan- tially reduces, oxygen from reaching the surface to support combustion of the combus- tible objects. This effect often prevents combustion from initiating or continuing, and substantially increases the time required for combustion. In addition, a present aque- ous composition forms a thermal barrier that slows the transfer of heat from a fire to a combustible object. Importantly, the dye and opacifying agent provide an excellent vis- ual indicator to mark where the fire-fighting composition has been applied, thereby pro- viding a more effective appliction of the composition. By evenly applying a sufficient amount of the composition to combustible objects, fire control and prevention are en- hanced because fire fighters can visualize when all desired combustible objects are treated.
An aqueous fire-fighting composition of the present invention is used by applying the composition to objects that are already burning, or by applying the composition to ob- jects that are not burning, but are in danger of igniting, such as foliage, trees, a build- ing, or other structures near a burning building. In this way, the aqueous fire-fighting composition can be used both to extinguish and suppress fires and to retard and pre- vent fires from spreading.
A present fire-fighting composition can be applied by spraying from the land or by aerial application, for example. The colorant and opacifier provide an indicator for the fire- fighters to visually identify which combustible objects have been treated. The opacify- ing agent enhances the visibility of the composition on the combustible objects. The SAP facilitates the action of the water in extinguishing the fire, and helps prevent com- bustion of unignited combustible objects. In preferred embodiments, treated combusti- ble objects substantially regain their natural color within about 30 days. In particular, the composition typically is rinsed from, or the colorant is degraded, within about 30 days, such that unburned objects substantially return to their natural color.
As noted above, the aqueous fire-fighting composition can be used to prevent fires from spreading, as well to extinguish fires. The composition also can be used to form a
firebreak or firewall that prevents a fire from spreading. In attempting to contain large fires, such as forest fires, firefighters often attempt to prevent the fire from spreading by removing combustible materials. In fighting forest fires, for example, firefighters may clear a band of trees along a continuous path spaced from the fire to form a firebreak, which prevents the fire from spreading to other trees and combustible objects on a nonburning side of the cleared path. The composition and method of the present inven- tion can be used to prevent a forest fire from spreading without clearing unburned trees from the area.
A present composition therefore can be applied to a band of trees rather than removing the trees to form a fire barrier. The contrasting color provided by the present composi- tion allows firefighters to more accurately apply the composition where needed, espe- cially for compositions applied from the air. The treated foliage substantially returns to its natural color within about 30 days after treatment.
The invention is further described in the following examples, which are merely illustra- tive and do not in any way limit the scope of the invention as described and claimed.
EXAMPLE 1 (COMPARATIVE) A fire-fighting composition was prepared by admixing 1000 g water, 5 g SAP (potas- sium polyacrylate) from BASF, and 2 g of FASTUSOL Red 51 L colorant from BASF.
After admixing, the pH of the composition was adjusted to 7 with sodium hydroxide.
The resulting hydrogel composition was spread on cardboard targets approximately 12"x12"square, then the targets were observed by the naked eye from various dis- tances, and under indoor and natural outdoor light conditions. The amount of colorant was adjusted to various levels, and the resulting compositions were applied to addi- tional cardboard targets to optimize the color visibility of the clear hydrogel. In this con- trolled experiment, color visibility was sufficient at relatively close distances. However, it was determined that at greater distances (e. g. , from aerial application), or when the composition is applied to nonplanar surfaces, this fire-fighting composition would be hard to detect, thus making it difficult to ensure an even and complete application of the composition to combustible objects.
EXAMPLE 2 A fire-fighting hydrogel composition was prepared by admixing 1000 g of water, 5 g of SAP from BASF, 2 g of FASTUSOL Red 51 L colorant from BASF, and 3 g of calcium carbonate (CaCO3) as an opacifying agent. After admixing, the pH of the hydrogel was adjusted to 7 with sodium hydroxide. The resulting hydrogel composition was spread on cardboard targets approximately 12"x12"square, then the targets were observed by the naked eye from various distances and under indoor and natural outdoor light condi-
tions. Other colorants also were evaluated for visibility. The amounts of colorant and CaCO3 were adjusted to various levels, and the resulting compositions were applied to additional cardboard and colored paper targets in order to optimize the color visibility and opacity of the opaque hydrogel. The visibility of the composition of Example 2 was improved over the visibility of the composition of Example 1, especially at greater dis- tances from the targets.
EXAMPLE 3 A fire-fighting composition is prepared as described in Example 2, and the composition is spread on various target materials, including dark green colored paper, vinyl siding, cedar shakes, and stucco. The treated target materials then are observed from various distances and under indoor and natural outdoor light conditions. The target materials then are exposed to natural weathering and direct sunlight conditions for a period of 7 days. The hydrogel composition applied to the target materials is observed for amount of drying and degree of color fade. All exposed areas fade significantly during this pe- riod to a light orange to clear residue. The above targets then are partially cleaned us- ing fresh tap water and mild abrasion (i. e. , sponge or soft scrub material). All residue of the hydrogel composition is easily removed from the target materials.
EXAMPLE 4 A fire-fighting composition is prepared by adding 1.8 mi of a colorant and 1.8 ml of a high molecular weight polyethylenimine (BASONAL White FO 1, available from BASF Corporation) to 990 ml of water, then stirring until homogeneous. To the resulting mix- ture was added about 5.75 gm of a sodium polyacrylate SAP, followed by stirring to provide a homogeneous composition. The three colorants added to separate composi- tions were FASTUSOL Red 51 L, FASTUSOLO Orange 80LN, and FASTUSOL Yel- low 76LN. A comparative example free of a high molecular weight polyethylenimine and colorant also was prepared.
A sample of each opacified composition was applied to a 2'x4'sheet of Astroturf. A sample of uncolored and unopacified SAP hydrogel also was applied to a sheet Astro- turf. The uncolored and unopacified SAP hydrogel was not visible on the Astroturf. The color of the Astroturf treated with a composition of the present invention was clearly visible. In an additional sample wherein the weight ratio of opacifier to colorant was increased to 2: 1, the color visibility of the applied fire-fighting composition was further enhanced.
After application to the Astroturf, a present fire-fighting composition dried after about 5 days, at which time the colorant applied to the Astroturf began to fade and the white opacifying agent became clear to light amber in color.
It will be understood that the specification and examples are illustrative only, are not limitative of the present invention, and other embodiments within the spirit and scope of the invention will suggest themselves to those skilled in the art.