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Publication numberUS3220858 A
Publication typeGrant
Publication dateNov 30, 1965
Filing dateNov 6, 1961
Priority dateNov 6, 1961
Publication numberUS 3220858 A, US 3220858A, US-A-3220858, US3220858 A, US3220858A
InventorsEldon A Behr, Hill Robert Ennis, Henry M Tobey
Original AssigneeChapman Chem Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Fire retardant
US 3220858 A
Abstract  available in
Images(12)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent 3,220,858 FIRE RETARDANT Eldon A. Behr, East Lansing, Mich., and Henry M. Tobey and Robert Ennis Hill, Memphis, Tenn., assignors to Chapman Chemical Company, Memphis, Tenn., a corporation of Tennessee No Drawing. Filed Nov. 6, 1961, Ser. No. 150,213 6 Claims. (Cl. 106-15) This invention relates to a method and composition for the protection of structural fibrous materials, and more particularly, to a method and composition for the treatment of wood, particle board, hard board, and related structural cellulosic fibrous materials for the purpose of protecting the same against fire and preserving the same, which method and compositions are designed to simplify the application to the wood and improve the overall re sults obtained.

There is a great need for the protection of wood used in exterior construction from fire. Particularly, such items as electric and communication poles located in city alleys may be severely damaged by the burning of rubbish too near the pole. Some pole lines are located in areas of tall grass which is easily set on fire. Railroad trestles composed of wood pressure treated with creosote and other oil borne preservatives also present a good case for the use of a medium for the protection from fire. In

flammable material are often set on fire by sparks, pieces of hot metal from brake shoes, or the like sources of fire, including fusees which may fall directly on wood structures to start fires. In order to avoid this potential source of fires, considerable sums are spent by railroads for labor and/ or chemicals to keep embankments under trestles free of Weeds that present the fire hazard.

There are a number of other situations which require protection from fire for wooden type structures and these include wharves, docks, platforms, fence posts and ferry slips. The instant invention is adapted for the use in protection against all of these devices.

In addition, the method and compositions of the instant invention are uniquely adapted for the inclusion of a wood preservative ingredient in the fire retardant composition.

Fire retardant treatments for wood or the like are available, but few if any are suited for use on wood in place that is impregnated with creosote, creosote-coal tar, creosote-petroleum, pentachlorophenol-petroleum or cop- 'per naphthenate-petroleum. Even less are intended for exterior use. Generally, fire retardant treatments involve the use of inorganic salts such as boric acid-borax mixtures and/or phosphates injected into the wood in aqueous solution. In addition, US. Patent No. 2,725,311 discloses the use of certain organic materials, namely, chlorinated parafiins, which are used in combination with creosote in a volatile solvent for the pretreatment of wood before it is used. This procedure as well as other procedures involving impregnation of wood with aqueous solutions are adapted for use in the treatment of wood or similar structural materials prior to the incorporation of such materials in structures in place, such as trestles and the like.

Another approach, allegedly for the protection of wood structures already in place, is described in U.S. Patent No. 2,734,827 which describes the use of a coating comprising an asphaltic vehicle, a fire retardant chemical (such as ammonium sulfate or ammonium bicarbonate, or a chlorinated parafiin), a silica aerogel, and for some purposes asbestos fibers. Such a coating for the most part relies on insulating properties or the formation of an intumescent coating and has a disadvantage that the coatings in use may tend to become embrittled and fall from the wood, or it may be necessary to employ a layer of glass fabric over the wood surface to cause proper adherence. Other coatings become embrittled and fall from the wood while others are not resistant to Weathermg.

Some coatings are especially diflicult to apply to a horizontal overhead surface such as the underside of a deck of a bridge. Many coatings are useable only in an interior exposure. The most important disadvantage of such insulating coatings is that these coatings must retain their integrity and adherence to the coated wood from the time the coating has set through an exposure to fire. This period of time between application and exposure to fire may range from a few months to several years. Thus, the coating for use in external applications must be resistant to deterioration by various climatic conditions such as rain, hail, Wind, high temperature and the like so that it will not erode or crack or lose its adherence.

On heavily treated wood, in addition, a high temperature fire will sometimes cause the oil borne preservative to bleed from the wood at the surface of contact between the coating and the wood causing loss of adherence. When the coating pulls away or falls from the wood, the preservative treated wood not containing fire retardant chemicals is exposed to the hazard of the fire. In some instances, a closely woven wire net may be nailed to the wood and a coating applied to the net which reinforces the coating. This procedure, however, is expensive and does not guarantee continuity of the coating.

By employment of our invention, we substantially overcome the problems and difiiculties of the prior art and effective means are provided for reducing the loss of Wood from burning, primarily that which may be preservatively treated with oil or oil-soluble materials including coal tar creosote, creosote-coal tar mixtures, creosote-petroleum mixtures, pentachlorophenol-petroleum oil, pentachlorophenol-creosote or copper naphthenatepetroleum oil. It will be appreciated that the compositions of the instant invention are not intended to prevent burning of the wood, but rather to retard spreading of the fire and to prevent total consumption of the wood, thereby retaining enough structural strength to permit subsequent and continued use of the structure of which the Wood is a part. Furthermore, compositions prepared in accordance with this invention promote formation of char which, in turn, protects the wood, and, in addition, the formation of volatile, flammable heat-treated products of wood is also reduced.

Some of the fire retardant ingredients of the compositions of the present invention have heretofore been employed in treatments for protecting fence posts from brush and grass fires and for protecting railroad trestles. However, all these treatments involved dissolving the fire retardant ingredient in a carrier solvent and introducing the ingredient into the wood by pressure or soaking. When the destined use of previously untreated wood is known, such treatments are probably the most economical way of introducing a fire retardant chemical into the organic phosphorus Compound, or the halogenated compound may contain phosphorous in the same molecule with either or both of the halogens, chlorine and bromine. In addition, the phosphorus and halogen containing compounds may be mixed further with separate compounds containing either bromine or chlorine. It is preferable that the halogens be held in combination in the molecule in all these compounds by a halogen to carbon bond.

It has been found that a thickening compound of bentonite and an organic-nitrogen base is capable of imparting the desired consistency to the fire inhibiting greaselike compositions, while permitting sufficient penetration of the fire retardant ingredient into the wood to which the grease is applied. In addition to its compatibilty with the fire retardant ingredients employed in our invention, this particular thickening compound produces a distinctly superior grease in that bleeding is substantially minimized. Also the material is easily compounded and applied.

It is, therefore, an important object of the present invention to provide an improved composition and method for wood preservation and flame protection.

It is a further object of the instant invention to provide an improved grease-like wood-preservative composition that does not tend to bleed heavily.

It is another object of the instant invention to provide an improved grease-like composition that is easily applied to wood for the preservation thereof.

It is still another object of the present invention to provide an improved grease-like composition having flame retardant properties including an oil-soluble, halogenated and/or phosphorous-containing compound and a thickening compound of bentonite and an organic-nitrogen base.

A further object of the present invention is to provide an improved grease-like composition having flame retardant properties that is easily applied to wood for the preservation thereof including an oil-soluble, phosphoruscontaining organic compound admixed with bromine or chlorine containing compounds and mixtures thereof and a thickening compound of bentonite and an organic-nitrogen base.

A still further object of the present invention is to provide improved grease-like compositions having flame and burning inhibiting properties that are easily applied to wood for the preservation thereof including an oilsoluble, halogenated organic compound containing phosphorous or admixed with an organic phosphorus compound, and a thickening compound of bentonite and an organic-nitrogen base in an amount sufficient to impart a grease-like consistency to the composition.

Yet another object of the present invention is to provide an improved method of inhibiting the burning of wood that comprises milling or subjecting to shear a composition comprising an oil-soluble halogenated compound containing phosphorous or admixed with organic phosphorous compounds and a thickening compound (with one of the many standard mixers and homogenizers), and applying the final grease-like composition to Wood.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof.

The present invention consists in a grease-like wood fire retardant composition comprising an oil-soluble, halogenated organic compound containing bromine or chlorine or mixtures thereof which contains phosphorus or which is admixed with organic phosphorous compounds, and a thickening agent of a compound of bentonite and an organic-nitrogen base in an amount sufficient to impart a grease-like consistency to said composition. The fire retardant composition preferably includes organic com pounds containing bromine or chlorine or mixtures of the two halogen compounds. Chlorine and bromine may also be present in the same molecule.

A feature of the present invention is the addition to the wood of a suificient amount of the fire retardant ingredient to reduce loss of wood substance by fire. This feature might conceivably be accomplished by brushing or spraying a solution of the fire retardant ingredent to the wood surface. In those cases where the wood has weathered and still retains only a small amount of the original preservative, brushing or spraying a solution of the fire retardant additive might be possible. In these cases the wood would absorb the fire retardant ingredient. However, in other circumstances, there remains a large amount of the original preservative in the wood and a spray or brush application of a solution of the fire retardant ingredient would run off to a large extent. These difficulties are overcome by the present invention. The fire retardant compositions of the present invention are applied to the treated wood in a gel or grease form. With the present invention, a reserve or reservoir of the fire retardant ingredient, as much as a quarter inch thick, may be applied to the wood. Thus, even on wood containing a high amount of preservative, substantial quantities of the fire retardant ingredient may be introduced into the wood. In additon, by employment of a gel or grease, various solid additives may be included in the grease and held on the wood surface which would not be possible with the prior art fiuid solution applications.

The fire retardant gel compositions of the present invention include the advantages of easy application by suit able pressurized spraying equipment; do not require continuity of an insulating fire resistant coating for their self-estinguishing properties or their effect in retarding flame spread. Of course, the degree of adherence Will depend upon the extent to which the wood has been previously treated and the extent to which the previously applied preservative is bleeding from the wood. Additionally, when using an insulating coating, the continuity of the coating must be broken for periodic inspection of certain structures to detect defective members, and the exposed wood then recoated. However, with the present invention, the fire retardant chemicals of the gel or grease diffuse to a certain extent into the wood and the residual gel or grease may be removed Without impairing the fire retardants of the structure significantly and need not be replaced. Furthermore, structural materials which have been previously treated with oil borne preservatives to high retention levels may be rendered fire retardant by the diffusion of the fire retardant ingredients of the gel compositions into the treated wood from the gel.

The fire retardant ingredients of the present invention are highly concentrated in the outer layers of the portion of the wood structures exposed to the hazard of fire where they are the most effective rather than being distributed throughout the treated portion of the wood, as in the case of wood which has been pressure treated with fire retardant chemicals dissolved in oil borne preservative solutions.

The fire retardant ingredients in the gel or grease compositions of the present invention are relatively water insoluble and may be used to effectively impart fire resistance to exterior structures exposed to various climatic conditions. The gel or grease compositions are also resistant to weathering conditions and the action of water does not dissolve or destroy their gelling properties.

The thickening agent employed in the practice of the instant invention for obtaining a grease-like consistency in the final grease composition is preferably a compound of bentonite and an organic-nitrogen base as described in US. Patent No. 2,904,467. In addition, the class of organic amonium montmorillonites including benzyl stearyl dimethyl ammonium bentonite may be employed satisfactorily in the practice of the present invention.

Bentonite compounds are composed of montmorillonite mineral in which at least a part of the cation content of the mineral has been replaced by an organic-nitrogen base. Clays that swell at least to some extent on being contacted with water and contain as a primary constituent a mineral of the group known as montmorillonites are generally referred to as bentonite. Such clays, which contain exchangeable alkali metal atoms either naturally or after treatment, constitute the raw materials employed in making the bentonite-organic base compounds used in the practice of the instant invention.

The bentonite-organic-nitrogen base compounds are preferably prepared as described in US. Patent No. 2,033,856, issued March 10, 1936, as compounds of bentonite with organic bases of sufiicient alkalinity to be titratable with mineral acids, which compounds are made by bringing together the bentonite and the organic-nitrogen base in the presence of aqueous mineral acid to effect base exchange. The organic-nitrogen bases include cyclic, aliphatic and heterocyclic amines, such as decyl amine, dodecyl amine, tetradecyl amine, hexadecyl amine, octadecyl amine, hexadecyl ammonium acetate, octadecyl ammonium acetate, dimethyl diOctyl ammonium acetate, dimethyl didodecyl ammonium acetate, dimethyl dodecyl hexadecyl ammonium acetate, dimethyl hexadecyl octadecyl ammonium acetate, dimethyl dioctadecyl ammonium acetate, and the corresponding chlorides and quaternary ammonium chlorides. The preferred bentonite compounds are prepared from quaternary ammonium compounds in which the N-substituents are aliphatic groups containing at least one alkyl group with a total of at least to 12 carobn atoms. When aliphatic amines are used, they preferably contain at least one alkyl group containing at least 10 to 12 carbon atoms.

Although the bentonite compounds are particularly useful in the practice of the instant invention as thickeners for the final grease composition, it will be noted that some of the bentonite compound may be replaced by inert inorganic fillers such as finely divided silica, diatomaceous earth, finely divided calcium silicate, and the like.

In general, when employed, the total amount of bentonite compound and inorganic filler (if any is used) should be such as to efiect the desired thickening of the composition and this amount may range, as aforesaid, from about 2% to about 16% of the final composition. The weight ratio of the bentonite compound to the inorganic filler, if used, may range from about 1:10 to 10:1.

The compositions of the present invention being rendered greases or grease-like materials by the addition of the bentonite ingredient may be applied to wood by handspreading, by a mechanical grease gun, or on a paper or plastic film or bandage. By this means, a reserve or reservoir of the fire retardant additive as much as a quarter inch or more thick may be applied to wood. Then, even on wood containing a high amount of preservative, substantial quantities of the fire retardant additive may be introduced in the wood.

Thus application of the grease compositions of the instant invention is adaptable for treatment of wood structures already in place, and, because of the chemical, mechanical and physical compatibility of the grease compositions with a variety of other ingredients, the properties of the grease compositions may be enhanced to meet the requirements of any particular application.

As may be observed from a study of the enclosed tabulation of fire retardant grease compositions, the percent organic ammonium montmorillonite employed in the gel compositions varies from about 3.76 to about 15.75%. These gels were made in the ASTM cone penetration (worked 60 strokes at 77 F.) range of from about 280 400.

Among the bentonite compounds found useful in the practice of the present invention are benzyl stearyl dimethyl ammonium bentonite, dicetyl dimethyl ammonium bentonite, dimethyl dioctadecyl ammonium bentonite, stearyl ammonium bentonite and the like organic ammonium montmorillonites.

A dispersing agent is preferably employed with the bentonite compound such as those agents disclosed in US. Patent No. 2,904,467, and propylene carbonate may also be employed as such an agent. The amount of dispersing agent employed may range from about 0.5% to about 7% of the final grease composition while we prefer to employ and excellent results are obtained employing from about 1.0% to about 5.0% of the dispersing agent. The dispersing agent is an organic polar solvent such as methanol, acetone or the like (preferably a low molecular weight alcohol, ketone or ester containing not more than about 4 carbon atoms, such as methanol, ethanol, isopropanol, butanol, acetone, diethyl ketone, methyl acetate, ethyl acetate and the like). In the practice of the present invention the dispersing agent is preferably added to the composition after the bentonite compound, but before inert filler materials, if any, are added (as used herein, the terms parts and percent means parts and percent by weight, unless otherwise designated).

As aforesaid, the fire retardant ingredients of the present invention include organic phosphorous containing compounds and organic bromine and chlorine containing compounds or compounds containing mixtures of both or mixtures of compounds containing both.

The preferred phosphorous and halogen containing compounds are those of low water-solubility, low volatility or low vapor pressure at ambient temperatures, and which have slow rates of decomposition at ambient temperatures and under outside weathering conditions.

These properties are considered essential where permanence in the wood is desired since the fire retardant efiect of the fire retardant ingredients may have to be maintained over a period of years. It is also desirable that mixtures of the fire retardant chemicals or ingredients or a single fire retardant ingredient containing both phosphorous and the preferred halogens be liquids of a fairly low pour point or be highly soluble in a solvent and also be soluble in the oil borne preservatives which may be present in the wood to be treated with the gel compositions of the present invention. Partial solubility of one of these components, does not, necessarily, rule out its use in a gel composition for application to wood containing a high concentration of oil borne preservative, provided the partially soluble component is a solid preferably finely divided, which is fairly soluble in the oil born preservative already present in the wood.

Phosphorous containing compounds which have been employed successfully in the practice of the present invention, depending upon the length of retardation desired, include:

. Boiling Point 245 C. at 11 mm. insoluble in water and stable to hydrolysis.

Boiling point varies with isomers.

10.7 7; by w 36.7% by wt. calculated.

Boiling Point;

6. Tris(dichloropropyl) a phosphate.

7. Tris(dibromopropyl) phosphate.

8. Tris(2,3dibrornopropy1) phosphate.

Greater than 200 C. at 4mm.

Also having utility are the following:

of fire retardant gel compositions on wood containing high concentrations of oil borne preservatives. Addi- Boiling Point Most of the liquid triesters of phosphoric acid prepared from alkylated phenols, mixtures of alkylated phenols and mixtures of alkylated phenols with phenol could be used, especially the triesters formed from various mixtures of cresols and phenol. It will be appreciated that since the addition of alkyl substituents lowers the phosphorous content of the compound, only the lower molecular weight alkyl groups are preferred.

It will be observed that most of the liquid triesters of phosphoric acid prepared from alkylated phenols are preferred for use in the practice of the present invention.

In general it may be said that the phosphorous containing compounds found useful in the present invention are the neutral tertiary esters of phosphoric acid with ester linkages to aryl, alkyl substituted aryl and saturated chlorinated and brominated alkyl groups. Bromine containing phosphonates are also considered useful in the present invention.

When employing the phosphorous organic compound admixed with organic bromine compounds not containing phosphorous, it has been found that the monocyclic aromatic bromine compounds containing bromine substituted on the ring have special utility in the present invention. These compounds contain high bromine percentages. Three such compounds used in formulating gel compositions of the present invention are:

If the end objective of the application of the fire retardant grease composition of the present invention is to coat previously untreated Wood or Wood containing lower retentions or concentrations of an oil borne wood preservative in the outer surface layers thereof, it is desirable then that the organic fire retardant ingredients remain in the form of a solution at the mean ambient temperatures of the wood to be treated. A stable solution of the ingredients should, in this case, be gelled with the organic ammonium montmorillonite.

If, however, the end objective of the application of the fire retardant grease-like composition is to coat previously treated wood containing high concentrations of an oil borne preservative in the outer surface layers thereof, it is not necessary that all the fire retardant ingredients present as undissolved solids be in solution but that these ingredients be soluble in the oil borne preservative already present in the wood.

Thus, while the most soluble of the above listed bromine compounds in organic phosphates and hydrocarbon solvents is tribromophenol, it is also one of the lowest boiling. The preferred bromine compound is Ar-tetrabromodiethylbenzene which is soluble in hydrocarbons and oil borne preservatives but not to the same extent as tribromophenol. Tribromoaniline is the least soluble of the three but is satisfactory for use in the application F. Approx. Dist. Pour Percent Range, Pt. C1 by wt. C.

1. Aroclor 1262 (chlorinated biphcnyl) 99 62 400430 2. Aroclor 1260 (chlorinated biphenyl) 88 60 385-420 3. Aroclor 1248 (chlorinated biphenyl) 48 340-375 4. Pentachlorophenol (MP. 190 C.) 60. 6 309-310 Other organic chlorine containing compounds which may be employed in this invention are the remaining known Aroclors (particularly the higher boiling point compounds which are polychlorinated polyphenyls), the isomeric tetrachlorophenols and trichlorophenols.

The compositions of the present invention may include a solvent, which preferably is a low boiling, non-flammable chlorinated or brominated solvent. The solvent is employed to lower the pour point and viscosity of the fire retardant chemicals, depending upon the application desired, which may have been in the form of a solution before the solvent is added. The solvent may also be added to dilute and solubilize insoluble ingredients of the fire retardant composition.

In most grease compositions only a small amount of solvent is added, for example, from about 5 to about 10% of the final gel composition. Because some solvents such as the hydrocarbon solvents, Eastman B solvent and creosote are flammable, the addition thereof should be held to a minimum and should not be higher than about 35% based on the final Weight of the gel or grease-like composition.

In most compositions, a highly aromatic petroleum will suffice. Examples of such solvents are:

9 Another solvent, Eastman B, has been successfully employed in the practice of the present invention and has the following characteristics:

Specific gravity, 20/-2() C 8.48 gal. Hydroxyl as OH 0.8%.

Ester as COOC 8.6%.

Boiling range 136 C.254 C.

The Eastman B solvent is a by-product containing mixtures of higher boiling alcohols, ketones, aldehydes and esters.

In some circumstances, a small amount of coal tar creosote may be added to the fire retardant composition not only as a solvent but also as a preservative for the Wood. In this instance, the solvent is preferably in a lesser amount than the solute. Coal tar creosote has a ditsillation range of not more than distilled over up to 210 C. and not more than 85% or less than 60% distilled over at 355 C.

An additional additive which may be included in the fire retardant composition is a wood preservative particularly for use in forming gel compositions for coating untreated wood or wood containing low concentrations of oil borne preservatives. The wood preservative may be pentachlorophenol which also may function as a source of chlorine in the composition. The wood preservative may also be coal tar creosote which may also function as a solvent for the fire retardant ingredients, and copper naphthenate has utility also in the present invention.

A corrosion inhibitor for preventing corrosion of the exposed metal hardware or steel rails in trestle construction and the like by the fire retardant gel may be employed and, examples thereof are, finely dispersed borax, boric acid or zinc borate. Zinc borates are less watersoluble than borax or boric acid and corrosion tests on mild steel indicate that the three inhibitors are effective in reducing corrosion of the fire retardant gel compositions, particularly those containing tribromophenol.

In general, the formulation of the fire retardant greaselike compositions of the present invention is usually accomplished by mixing of the organic ammonium montmorillonite with a solution of the fire retardant ingre' dients and stirring of the mixture until the thickening agent is disseminated or dispersed throughout the liquid. The fire retardant compounds, if they are a solution at room temperature, normally need not be heated much above room temperature during the stirring period. With other compositions, the solution may only be stable at high temperatures so that the thickening agent is disseminated or dispersed at the high temperature of solution and, after the composition has thickened, one of the ingredients may partially crystallize out after cooling to room temperature. A suitable polar agent or dispersing agent is added, when required, to disperse the organic ammonium montmorillonite. With stable fire retardant solutions, methanol and acetone may be employed. The solutions which are stable at higher temperatures than the boiling points of acetone or methanol may require higher boiling polar agents or propylene carbonate. After the polar agents have been added to the mixture, the mixture may be homogenized or milled at high shear rates to form a gel or grease. A Manton-Gaulin homogenizer or a colloid mill may be employed for this purpose. With some compositions employing thickening agents, such as benzyl stearyl dimethyl ammonium bentonite, a grease-like consistency may be obtained by prolonged stirring in a bakery type dough mixer as made by the Hobart Manufacturing Company, and the resulting gel composition does not necessarily require homogenizing or milling in a separate device such as the Manton-Gaulin machine or a colloid mill.

With some compositions, a solution including fire retardant ingredients which are stable at room temperature or lower may be gelled employing the organic montmorillonite and the remaining insoluble fire retardant ingredients mechanically mixed into the composition in finely powdered form. In other compositions, the ingredients may be of sufl'icient chemical polarity to disperse the organic montmorillonite without the addition of a separate polar agent to form the grease-like final composition.

The final gel or grease-like composition made in accordance with any of the above procedures may contain from about 2% to about 10% phosphorous (based on the original weight of the ingredients) in the form of the high boiling phosphates or phosphonates.

Preferably the halogens, bromine and/ or chlorine should be present in the final grease-like composition in the following ratios:

(1) If chlorine alone is present it should be in a weight ratio of not less than three parts chlorine to one part phosphorous or more than sixteen parts chlorine to one part phosphorous. Obviously the higher ratios of chlorine to phosphorous will be in formulations of low phosphorous content.

(2) If bromine alone is present it should be in a Weight ratio of not less than 1.5 parts bromine to one part phosphorous or no more than eight parts bromine to one part phosphorous.

(3) If mixtures of bromine and chlorine are present, the parts by weight of bromine should be multiplied by two and added to the parts of chlorine, the total should be no less than three parts of this calculated mixture to one part phosphorous or no more than sixteen parts of the calculated mixture to one part phosphorous.

The fire retardant grease-like composition, as aforesaid, should contain no more than about 35% of a solvent and may contain a wood preservative or wood preservatives in various amounts. An inorganic corrosion inhibitor may be mechanically dispersed in the gel, preferably after milling, and should be in a small amount, for example, no more than about 2% by weight of the final grease-like composition.

The fire retardant grease-like composition may be applied, as aforesaid, by spraying on the surfaces of the wood to be coated by means of Alemite equipment of conventional construction. In addition the equipment used for spraying asphalt undercoatings on automobiles may also be employed. The gel, of course, may be applied manually.

The thickness of the applied fire retardant gel or grease depends upon the composition of the grease, the type of wood being treated as Well as the desired amount of fire protection. It will be appreciated that gels low in fire retardant chemicals may be applied in thicker coatings than the more highly concentrated gels. The thickness of the gel may vary, for example, from about A1. to of an inch; however, excellent results are obtained where the thickness of the grease is about of an inch. In general, the actual amount of grease to be employed is preferably calculated on a weight per unit area basis to provide a predetermined weight of phosphorous and bromine per square foot of surface covered.

After the grease-like composition has aged and the fire retardant ingredients have partially diffused into the wood, it will be appreciated that the residual gel layer will decrease in thickness to some extent in proportion to the loss of the fire retardant ingredients from the grease-like composition into the treated wood. The residual gel layer over time will, of course, harden to some extent.

In testing the effectiveness of the fire retardant greaselike compositions of the present invention, three general methods were employed including, an overhead panel test, a full scale bridge replica test and a fire cabinet test.

The materials employed in the panel, bridge, and fire cabinet tests were Douglas fir and/ or southern yellow pine which had been treated with either coal tar creosote or coal tar creosote-petroleum mixture-s to various solution retentions before application of the grease-like composition to the surface of the material.

The overhead panel test was designed to evaluate fire control agents in field burning tests and to simulate the portion of a ballasted deck trestle exposed to the hazard of weed fires.

12 in addition to the 0.6 part of chlorine whereas Gel C contained one part phosphorous to 7.3 parts chlorine including the pentachlorophenol and the term D71A is a trade name known to the art prior to this application The panels were weighed before and after exposure to and designating a commercially available composition fire to determine weight loss data during the burning of that consists essentially of a low boiling hydrocarbon tumbleweed -in contact therewith. Also, the time repetroleum solvent. quired for the panels to become self-extinguishing is After two and one-half months of exposure (summer), recorded in the accompanying tables and, in addition, the the panels were weighed and installed in an open end depth of charring is so recorded. section replica representative of closed deck bridge con- I performing th panel t ts, th panels w r built struction. The permanent portion of the structure was three feet wide and fourteen feet long from Douglas fir protected from the fire with asbestos. Tumbleweeds were and southern pine lumber of 2-inch thickness which had pi ed tWO to three feet high under the panel with the gel been treated one to four years previously with a 50/50 coated side down, and the weeds were ignited. mixtur of o l t creosote-petroleum, The results of these overhead panel burning tests along Three fire retardant grease-like compositions were pre with control panels are ShOWll in Table II. Table II ll'ldlpared d usgd i these t cates that the panels continued to burn after the tumble- Each grease-like composition was sprayed by means of Weed Which y range from a temperature of 1400 Alemite equipment on one of the two wide surfaces (50 i0 1600 had burned f However, h P2111615 square feet) of two southern pine panels and two Douglas treated With the COITIPOSHIOHS of the Pfesflnt Invention fi 13311515 for t t 1 f12 1 were self-extinguishing, and the flames died out after a The compositions of these greases are set forth in fairly Short Perifld of time, especially the Panels treated Table I: with Gel B and Gel C.

TABLE I As will be observed from a study of Table II the fire retardant effect was especially evident in the tests employ- GGHM GGHL G914) ing southern yellow pine panels when the results employpercent percent percent ing these treated panels are compared with the control panels. Even though the amount of available phos- Monophenyl-dieresyl phosphate conphorous per square foot of area was less in Gel B and T53535331 335.tlti figitttr 8138 21 Gel the l t r two were more effective in their fire 2,4,6tribro1nophcnc1 27. 50 retarding effects. Gel A contained only one part phos- 11:: is: phorous to 0.6 part by weight of chlorine whereas Gel B Stearylammomum bentomte 10-50 11-00 contained one part phosphorous to 4.6 parts bromine istiilimlli ifiifi fiii fliTRY??? 7,25 y g t in addition to 0.9 part of chlorine. Gel c Methanol contained one part phosphorous to 7,3 part hlorin including the pentachlorophenol.

TABLE II Calculated Pounds of Elements Fire Re- Original Weight of Applied Per Square Foot of Area Total Phosphorous, tardant Gel Applied to Chlorine and Bro- Species of Treated Gel Sq. Ft. of Area in mine Applied For Wood Pounds Phosphor- Chlorine Bromine Square Foot OHS 0. 024 0. 016 0. 040 Douglas fir,

Southern pine. 0. 01s 0. 018 0.080 0. 116 Do. 0. 014 0.102 0.11s 3 1 The weight of gel applied to each panel corresponded to a Mo inch layer over the 50 sq. ft. of surface area of the panels.

Gel A contained only about one part phosphorous to 0.6 part by weight of chlorine while Gel B contained one part phosphorous to 4.6 parts bromine by weight In Table III are set forth the data relating to burning of the wood treated in accordance with the procedure outlined above.

TABLE III Time After Ignition Time After Ignition for Weeds to Burn Out for Panels to be Self- Weight Depth of Gol Extinguishing Loss Dur- Char in ing Fire Inches in Pounds 1 Minutes Seconds Minutes Seconds 1 30 l6 00 24 Slight. Gel A Remo vcd4atcr 20 min. 2 27 Slight. 00 13 Slight; G913 l i t; 5 00 2o glight 13 0O 25 light Gel C i 2 00 7 13 22 Slight. None 2 00 h 23 00 22 Lil; inch. 1 30 Extlnguished after 1 hr. 50 mm 27 min. 3

l The weight loss of the gel coated panels included the residual gel which was burned away during the fire. This caused the weight losses to be high when compared to the untreated controls.

tlnguished.

13 Other panels similarly prepared for the burning tests were not burned; however, increment borings from two of the unburned panels treated with Gel B were analyzed for phosphorous and bromine content with the following results:

*Calculated in pounds of monophenyl dieresyl phosphate containing 8.6% elemental phosphorous. I

built of southern yellow pine piling and Douglas fir lumber which has been treated with a 50/50 creosote-petroleum mixture 2 to years prior to construction. This bridge replica was spray coated with Gel C-2 of the same fire retardant composition as Gel C in a layer of 0.7 inch thick or about pounds per square feet. It will be observed that the amount applied is 5 pounds more than employed in the previous overhead panel tests. Two months later, the bridge replicas were bored for analysis along with some test piling coated at the same time the bridge replicas were coated. After borings were taken, tumbleweed was placed under the bridge replicas and ignited. The results of these burning tests are shown in Table V along with the results obtained in burning of pressure treated replicas in which an alkylated triaryl TABLE V Description of Treatment of Full Scale Bridge Replica Species of Wood Peak Fire Temp., F.

Decking Piling 1. Newly treated replica-Pressure treated fresh stock with a 50/50 creosote-petroleum mixture.

D. fir 1,500 at 2.5 min.

D. fir 1,630 at 6.2 min.

D. fir 1,600 at 3 min.

D. fir So. pine.-. 1,710 at 2.0 min.

D. fir So. pine... 1,690 at 3 min.

1 Containing 13.5% mixed (ethyl phenyl) (isopropyl phenyl) phosphate. 2 Containing 20% mixed (ethyl phcnyl) (isopropyl phenyl) phosphate.

These results indicate that penetration into the previously treated Wood was accompanied by the fire retardant chemical from Gel B in the 2 /2 month period after application thereof on both types of wood indicated in Table IV. In addition, on 50/50 creosote-petroleum treated southern pine and Douglas fir timbers coated With Gel C five months previously contained both phosphorous and chlorine in the outer, second, and in some cases, in the third quarter inch zones.

The second test procedure conducted was that of burning a full scale bridge replica. A bridge replica was constructed of Douglas fir piling and lumber previously treated with 50/50 creosote-petroleum mixture from 2 to 10 years prior to construction of the replica.

A fire retardant gel composition Gel B2, similar to the above Gel B formulation, was applied to approximately 500 square feet of surface area of the replica in a A inch thickness by spraying. The Gel B2 differs from Gel B only in that about 5% of D7 1A petroleum solvent was substituted for pentachlorophenol. The amount of gel applied was about 23.5 lbs. per 50 square feet and is almost identical in the application rate to that rate of application of Gel B used in the aforementioned overhead panel tests. A second bridge replica was TABLE VI [TIME IN MINUTES AFTER IGNITION] Time of Temp. Time Time Time Max. Dpth Duration Above Until Fire Until Fire Until Fire of Char.

1,000 F. subsided Substan- Totally in Inches tially Out Out Table VI indicates the burning time data of the tests on the materials set forth in Table V.

Tables VII and VIII indicate the results of the phosphorous analysis on wood removed by boring from parts of the various replicas.

The results in Table V indicate the effectiveness of the fire retardant ingredients of the gel compositions of the present invention and indicate that the gel compositions and treatments of the present invention excel when compared to the treatments in which the fire retardant is dissolved in the pressure treating solution. It will be observed that the results in Tables V-VIII also indicate that it is more advantageous to employ gels prepared in accordance with this invention on the heavily treated 15 structures than it is to disassemble the structures, repressure treat the members of the structure after solvent cleaning and then reassemble the structure.

TABLE VII Treatment Zone D. fir Pile Douglas fir Analyzed Cap 1 Piling 2 1. Newly treated Replica 0.21 0. 32 Pressure treated fresh stock 0. 18 0. 6,; with a 50/50 creosote-petro- 0.11 0. 01 leum mixture.* 0.00 0. 35 2. Gel treated Replica Gel 0.16 0.370.39-0. 11 B2Previously creosote- 0.03 013-0. 10

petroleum treated stock 0.03 0.11-0. 10-0.

which had been covered with M6 coating of Gel 13-2 for two months.

3. Retreated ReplicaPrevi- 1st. y 0.11

ously creosote-petroleum 2d. y- 0. 04 treated stock which had 2d. 0.03 been solvent cleaned and 2d. 1" 0.01 retreated with a creosote mixture. 13 4. Gel treated Replica Gel 1st. 1 0.07 0. 02 *2 Previously creosote 2d. V. O. 02 0. o3 petroleum treated stock 3d. 0.02 0.

which had been covered with up to 0.07" coating 01' Gel 0-2 for 2 months.

The Douglas fir pile cap was treated to 8.0 lbs/cu. ft. retention of preservative.*

The Douglas fir piling was treated to 12.7 lbs/cu. it. retention of preservative.

*Containing 13.5% mixed (ethyl phenyl) sopropyl phenyl) phosphate Containing 20% mixed (ethyl phenyl) (isopropyl phenyl) phosphate The third test method employed in evaluating the effectiveness of the fire retardant gels prepared in accordance with the present invention was the fire cabinet test. This method, as described in the American Wood Preservers Association publication entitled Some Effects of creosote-Solutions on the Flammability of Southern Yellow Pine, by S. K. Coburn and K. J. Morris, Jr., was employed with the following modifications: Thermocouples were inserted in the cabinet to measure the flame temperature only and rectangular 3.5" X 3.5" x 18" test specimens were used.

The specimens were suspended in the cabinet so that the flames from each of the four vertical flame tubes impinged down the length of one of the four 3.5 x 18" faces of the specimen. This was accomplished by suspending the specimen with its longitudinal axis in a vertical position so that the four corners thereof were held half way between each of the vertical flame tubes. The specimens employed in this test were from two southern yellow pine sections 3.5 x 3.5" by 14' long containing a small amount of boxed heartwood. The two sections were pressure treated with coal tar creosote to retentions of 21 and 20 pounds of creosote per cubic foot of wood.

The sections were then sawn into 18" lengths and left for one month, after which time they were weighed, and identical weights of individual test greases were applied to duplicate specimens, one from each of the two original sections. Twelve specimens were coated and two were left uncoated for control purposes.

pared to the control specimens.

After four months of outside exposure, small amounts of the gel compositions prepared in accordance with the present invention were removed from small areas in a sector of the specimen and near the middle of each sector the specimens were bored. The small samples of wood obtained from boring were analyzed for phosphorus, and, in some instances, bromine content. The boring holes were plugged with untreated wooden dowels and the gel composition that had been removed was replaced. The specimens were then burned in a test cabinet as described in the above identified publication by ignition in a flame, such as propane gas flame, for a period of five minutes. After turning off the gas flame, the interval of time required for the specimens to be self-extinguishing was recorded.

The specimens were removed, and, then weighed after removal of the char.

The results of the analysis for phosphorous and bromine are disclosed in Table IX. The results of the burning tests are shown in Table X.

The results of the burning tests also indicate excellent fire rectardancy of the gel compositions when com- From Tables IX and X it may be seen that very high retentions of phosphorous and bromine were found in the outer zones of the grease coated wood after four months of outdoor exposure during the summer months. The residual gel was still intact to the time the borings were taken, and climatic conditions had not visibly affected the gel compositions so that the fire retardant chemicals could diffuse into the treated wood.

The grease coated wood was self-extinguished shortly after the source of ignition was removed. Also, the weight losses which were all based on the weight of the specimens when originally coated with the gels were significantly lower. This procedure was followed since, if the residual grease lost during the fire is included as weight loss of the specimen, the weight will be too high and would not be representative of the weight loss due to fire. This high weight loss was shown in Table I in which the weight of the residual grease was included in the loss data.

An important feature of the present invention resides in the realization that the application of the gels is not only to impart a fire retardant effect to wood (cellulosic materials) but also to impart this effect to the oilborne preservative which may be present in the wood in high concentrations. The fire cabinet test above described is an excellent example. In the tests, and in using the 3.5 X 3.5 x 18" specimens, it was quite difficult to get untreated Douglas fir or southern pine (not containing an oil-borne preservative or fire retardant grease) to support combustion after the propane flame was extinguished, although these specimens are charred by the flame. They were self-extinguishing and tended to glow for a period after the propane flame subsided.

Controls, however, that were treated with high retentions of coal tar creosote or creosote-petroleum continued to support combustion after the propane flame was extinguished, so that a measuable fire burning time was observed. The fire retardant gel compositions of the present invention suppressed this type burning and extinguished the flame quite readily. From these observations it is readily apparent that a suppression of the combustion of both the wood and oil-borne preservation has taken place.

The Gel E contained one part by weight of phosphorous to 5.3 parts of bromine in a mixture of compounds, one of which contains all the phosphorous and the other which contains all the bromine. The solution from which the gel composition of the present invention may be prepared is not completely stable at room temperature as some of the tetrabromo-diethyl benzene will eventually crystallize out. However, a g l may be prepared at temperatures 10 to 20' C. below the boiling point of the polar agent, i.e., methanol, with little ditficulty. The ratio of phosphorous to bromine in the wood does not appear to indicate that this slight insolubility hinders penetration of the tetrabromo-diethyl benzene into wood containing creosote. The gel will contain crystals when stored, however, for long periods at C. This gel in addition contained zinc borate.

The compositions and percentages of these gels are set forth in a later table (Table XII).

Gel F contains the same fire retardant ingredients used in Gel E with, however, 1 part phosphorous by weight to only 2.1 parts by weight of bromine. This fire retardant ingredient forms a stable solution at room temperatures before gelling.

Gel G was prepared employing Celluflex CEF, tris(flchloroethyl)phosphate, in combination with tribromophenol. This is an example of a fire retardant ingredient containing phosphorous and chlorine in the same molecule of the compound which was mixed with another chemical compound containing bromine to form the final solution. This solution is stable at room temperature.

The Gel B-2 contains tribromophenol and monophenyl discresyl phosphate. This fire retardant solution is stable at about 0 C. and the gel may'be stored for long periods at 0 F. without formation of crystals. A five gallon pail of this gel composition which had an initial ASTM TABLE IX Ratio in gel phate after homogenizing.

18 position containing the phosphorous and chlorine in the same chemical compound as heretofore mentioned.

Gels described in Table IX were homogenized with the exception of Gel G which was only stirred in a Hobart type dough mixer.

In Tables XI and XI-A are set forth examples of grease-like compositions prepared in accordance with the present invention. The examples disclosed therein include mixtures of cresyl phenyl phosphates in which sep- 10 arate bromine and chlorine containing compounds are used both alone and in mixtures.

Gel O of Table XI was formulated by the addition of tribromo aniline to a gel including benzyl stearyl dimethyl ammonium bentonite and cresyl diphenyl phos- The tribromo-aniline, in powdered form, was physically mixed with the gel or grease formulation which was employed in a fire cabinet test. This grease composition was applied to southern yellow pine specimens treated with a 50/50 mixture of 20 coal tar creosote-petroleum to a retention of 22 pounds per cubic foot and left for a period of months. The application rate was 21.9 pounds of gel per 50 square of treated wood. When tested in the fire cabinet test, the coated specimen was found to give a free burning time 25 of one and minutes and a weight loss of 11%. This was compared to an uncoated control specimen which burned for 8 minutes with a 24% weight loss.

Lbs. of Material Found/cu. ft. of Wood After 4 Months Calculated Phospho- Phospho- Gel Designation lbs. of Gel rous to rous to Phosphoper sq. ft. Bromine Chlorine Zones Phosphorous to Analyzed rous Bromine Bromine ratio in Zones Untreated Controls.

*Contaiued 1% Zinc Borate.

cone penetration at 77 F. (worked strokes) of 335 mm./ 10 was found to have a penetration of 339 mm./ 10 within months after storage in an unheated warehouse. There was only a trace of bleeding and the gel composition contained no lumps or crystals.

1 Average free burning time after five minute ignition in fire cabinet o duplicate specimens.

2 Approximate average percent weight loss after burning based on weight when coated with gel of duplicate specimens.

Gels J and K are identical and were prepared employing Cellufiex (CEF), tris(B-chloroethyDphosphate, as the only fire retardant. This example represents a gel com- TABLE XI Gelling Agent Technical Phosphate Gel Com- Penta- Methanol position chloro- X 1 Y 2 phenol A 3 B 4 Footnotes at end of table.

TABLE XICnt1nued TABLE XICont1nued Chlorine Oom- Bromine Compound Solvents Percent By Weight Parts By Weight pound Aroclor Tribromo Gel D-71A Composition East- C.T. Phos- Bro- Chlo- 1262 1248 Phenol Aniline man Creophomine rine PzBr P:Cl

B sote rous A 6. 0 10. 00 B 4. 3 5. 02 C 4. 0 10.00 13-2 4.1 15.35 0-2 4.0 25. 68 L 4. 1 20. 96 M 4. 1 N 3.1 O 5. 0 P- 2.7 15 Q 8. 38 R 3. 5 S 2. 7 T 4. 2 U V- T Z..- 10. 00 Z X 10.00 Y W X V 4.14 W U 4. 14 8. 28 V 8.28 '1" 4.60 U. S 4. 60 9.18 T 9.18 R 39. 80 S 3. 9 21. 4 1-5. 4 R 12. 2 3. 4 24. 7 1-7. 2

All the above formulations were homogenized in a Manton-Gaulin NOTES: figgggggg ga at 1153- with exception of Y which was not 30 N was formulated by mixing in powdered tribromoaniline after a 1 Stearyl Amine Bentonite.

Z Benzyl Stearyl Ammonium Bentom'te. 3 Monocresyl Diphenyl Phosphate.

4 Monophenyl Dicresyl Phosphate.

gel had been formed containing part of the tribromoaniline solution.

0 was formulated by mixing in powdered tribromoaniline after a gel had been formed with the remaining constituents.

TABLE XI-A Gelling Agent Celluflex Ar Gel Com- Phosphate Aroclor Tetra- Tribromo position Methanol A 3 P 6 1260 bromo phenol D-71A X 1 Y 2 CEF 4 FR-2 5 diethylbenzene 5. 25 III 5. 25 2. 25 42. 65

Triphenyl Phosphate Tricresyl Acetone Phosphate Solvents Percent By Weight Parts By Weight Homoge- Gel Compo- D-71A nizing sition Pressure,

Eastman-B AN-3 Phospho- Bromine Chlorine IzBr PzCl p.s.i.

rous

Norm-C contains 1% zinc borate. 1 Stearyl amine bentonite.

Z Benzyl stearyl ammonium bentonite.

3 Monoeresyl diphenyl phosphate.

7 Not homogenize dams-5s Analysis of both Douglas fir heartwood and southern pin sapwood treated with from 16 to 28 pounds per cubic foot of wood with creosote-petroleum mixtures and coated with Gel showed adequate bromine contents in the outer and second zones of both species after 4 months.

22 The Gel O' exemplifies a gel or grease-like composition in which no polar solvent, such as methanol, is employed to disperse the grease. The Eastman B solvent was added as a last ingredient after mixing and heating of the gel composition to 140 F. This mixture was This test indicated that the tribromoaniline had good pene- 5 homogenized at 6000 pounds p.s.i. in a single stage Mantration although its solubility in some phosphates, cresyl ton-Gaulin homogenizer to form the gel. diphenyl phosphates, is limited. Gel M (Table XIII) was prepared from the constitu- Gel W was also employed to coat southern yellow pine ents of Gel 0' with the addition of melted tetrabromopressure treated with 50/50 mixture of coal tar c'reosotediethyl benzene to form a solution at 180 F. The mixpetroleum wood preservative to an average retention of ture, at 180 F. was homogenized at 6000 pounds p.s.i. pounds per cubic foot of wood; The gel composition to make the gel. The tetrabromodiethyl benzene crys- W was applied at a rate of 22.7 pounds per 50 square tallized out as the gel was cooled to room temperature. feet and anaylses of borings made from 20 specimens However, the gel could be applied by pressure spray showed phosphorus and chlorine to be present in. the equipment and the gel upon storage at 0 C. was still outer 0.25 inch and second 0.25" zones of the treated workable or spreadable.

TABLE XIII Gelling Agents, Percent Ar tetra- Homoge- ASTM Gel Methanol, Phosphate bromo D-71A nizing Cone Composition Percent A* diethyl Pressure, Pene- X Z2 W Y4 V Benzene p.s.i. tration N OTES:

X Stearyl Amine Bentonite.

Phosphate A*Cresyl Diphenyl Phosphate.

wood. This gel composition was tested in burning crib tests wherein stacks of wood treated with the gel are piled and the Wood crib burned.

Gel W indicates the importance of the time element in difiusion of the fire retardant ingredients into wood. This Gel W was employed to cover southern yellow pine and Douglas fir piling sections treated years previously with creosote-petroleum. Samples of wood were taken by boring over intervals of time in order to determine the rate of diffusion of the monophenyl dicresyl phosphate made from mixtures of phenol and cresols calculated from the phosphorus content of the outer and second A" zones.

Table XII indicates the rate of diffusion of the phos# phate ingredient from the gel composition into the wood.

tains from 2 to 10% elemental phosphorous, preferably as a neutral phosphate ester with ester linkages to aryl, alkylated aryl, and/ or partially halogenated aryl, all-containing 6 to 12 carbon atoms, and/or two alkyl groups TABLE XII Thickness Estimated Phosphate Retention, lbs/cu. it. of

of Gel Zones 50/50 Creowood after Species of Piling Coating Analyzed sote-Petro- (in) leum, lbs/cu.

ft. of wood I 2 Wks. 1 Mo. 2 Mo. 4 Mo.

Douglas fir 26 0.67 1. 49 3, 85 31 0.11 0.10 0.06 M 26 0.39 1.05 2. 70 31 0.07 0.04 0.04 Southern Pine 33 2. 34 3. 86 8. 58 25 0.20 0. 27 0.62 Mg 33 1. 68 2. 95 5. 10 25 0.11 0.30 1.07

In both species of wood, the zones analyzed were all containlng fr0m'4 to 8 carbon atoms, and/or two haloin the sapwood layer.

From Table XII it will be observed that the gel composition was continuously releasing the fire retardant ingredient to the heavily treated wood over the fourmonth period. This data indicates that an increase in fire retardant effectiveness occurs with aging.

Table XIII includes other grease-like compositions prepared in accordance with the present invention in which other phosphates are employed as well as the mixed cresyl diphenyl phosphates.

genated alkyl groups containing from 2 to 8 carbon atoms. The phosphorous is present in combination with from about 1 6 to about 3 parts chlorine to about 1 part part phosphorous by weight or with about 8 parts to about 1.5 parts bromine to 1 part phosphorous by weight, or in combination with a mixture of bromine and chlorine in which the parts by Weight of bromine ,multiplied by 2 and .the total sum added to the parts by weight of chlorine is between about 16 parts to about 1 part phosphorous and about 3 parts to about 1 part phosphorous by weight, the halogens being combined in the phosphorous containing molecule or in separate halogenated aromatic compounds, or in mixtures of both, the separate halogenated compounds being represented by the chlorinated biphenyls, terphenyls, and polychlorinated polyphenyls and the brominated phenols, tribromoaniline, tetrabromo-o-cresol and the brominated alkylated benZenes containing 3 .to 4 bromine atoms and pentachlorophenol. The pentachlorophenol may be added as a wood preservative as well as a source of chlorine. In addition coal tar creosote may be added as a wood preservative as well as a solvent, or, copper naphthenate. The final gel or grease-like composition may contain not over about 2% of an inorganic corrosion inhibitor, such as zinc borate, so that after application to untreated or wood treated with oil-borne wood preservative, the fire retardant ingredients migrate into the wood structure in an amount sutficient to impart self fire extinguishing properties to the wood and any oilborne preservative present after the source of fire has been removed, and which also prevents flame spread along the surface of the wood.

The preferred fire retardant ingredients are those containing high boiling, stable, low pour point phosphates, such as the mixed cresyl phenyl phosphates and tricresyl phosphates and the high boiling bromine containing compounds. If triorthocresyl phosphate is employed, it will be remembered that this composition is fairly toxic so that it is preferable to employ those phosphates of this type containing low percentages of ortho-isomer.

For example, Cellufiex 179-A is described as containing less than 1% by weight of the ortho-isomer. However, Celluflex GA is described as containing 10.0% maximum by weight of ortho-isomer, and both are described as tricresyl phosphates. A cresylic acid for the manufacture of tricresyl phosphate which is available from the Koppers Company is described as follows:

E.G. grade cresylic acid, percent Meta cresol Min 45 Para cresol Ca 26 Low boiling xylenols Ca 23 Other tar acids Ca 4 Other materials from Koppers designated for use in commercial tricresyl phosphate are:

2 Meta Paraeresol 3 Meta Paracresol Meta CrcsoL- Min. 55%. Ca. 33%.

Ca. 87 Max. 6%.

The preferred bromine compound is the high boiling, water insoluble, technical tetrabromo diethyl benzene formed from the bromination of diethyl benzene. This compound has a melting point of about 55 to 59 C. and a boiling point over 320 C. Three isomers of tetrabromodiethyl benzene are reported as follows:

M.P., C. 3,4,5,6-tetrabromo-1,2-diethyl benzene 64.5 2,4,5,6-tetrabromo-1,3-diethyl benzene 74.0

2,3,5,6-tetrabromo-1,4-diethyl benzene 112.0

The order of addition of the ingredients in the compositions of the present invention is not important in most cases. The liquid components may be added to the organic montmorillonite or the organic montmorillonite may be added to the solution, all at once or stepwise. The addition of the dispersing agent is rarely to the montmorillonite alone, but may be added before all the solution is added to the organic montmorillonite or, as usually is the case, added last.

The grease-like compositions prepared in accordance with the present invention exhibit good storage stability and consistency of a period of months has been maintained to the point where the compositions were found usable at room temperature.

A compound in which both chlorine and bromine are chemically combined in the molecule and which has utility in the present invention is 2,6-dichloro-3,4,5-tribrornophenol. In all formulations containing pentachlorophenol, the pentachlorophenol is dissolved in the monophenyl dicresyl phosphate or monocresyl diphenyl phosphate at concentrations below saturation at room temperature.

It will be appreciated that the above examples are representative only and that modifications and variations thereof may be effected without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. A fire retardant grease-like composition of low volatility and low water solubility comprising (a) fire retardant material consisting essentially of (a an organic phosphate selected from the group consisting of monophenyldicresyl phosphates, diphenyl monocresyl phosphates, tris(chloroethy1) phosphate, tris(dichloropropyl)phosphate, and tricresyl phosphate combined with (a an organic halogen compound selected from the group consisting of tribromoaniline, tribromophenol, and tetrabromodiethyl benzene; in which material (a) the PzBr plus Cl Weight ratio is substantially 1:1.5 to 1:16; and (b) a thickening agent in an amount by Weight of the composition ranging from 5% to 20%, said thickening agent being a compound of bentonite and an organic-nitrogen base, present in an amount sufiicient to impart a grease-like consistency to said composition.

2. A composition as claimed in claim 1, wherein compound (a is 2,4,6-tribromopheno1.

3. A composition as claimed in claim 2, wherein said retardant (a) also comprises pentachlorophenol.

4. A composition as claimed in claim 1, wherein compound (a is 2,4,6-tribromoaniline.

5. A composition as claimed in claim 1, wherein compound (a is tetrabromodiethyl benzene.

6. A fire retardant grease-like composition of low volatility and low Water solubility comprising (a) fire retardant material consisting essentially of tris(ch1oroethyl)phosphate; and (b) a thickening agent in an amount by weight of the composition ranging from 5% to 20%, said thickening agent being a compound of bentonite and an organic-nitrogen base, present in an amount sutficient to impart a grease-like consistency to said composition.

References Cited by the Examiner UNITED STATES PATENTS 2,743,188 4/1956 Hunter 10615 2,803,562 8/1957 Erbel et a1 10615 2,861,002 11/1958 Britton 106177 2,904,467 9/1959 Behr 10615 ALEXANDER H. BRODMERKEL, Primary Examiner.

JOHN H. MACK, MORRIS LIEBMAN, Examiners.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2743188 *Apr 11, 1952Apr 24, 1956Hunter Metallic Products CorpPutty
US2803562 *May 26, 1955Aug 20, 1957Dow Chemical CoTreatment of cellulosic materials to impart flame resistance thereto
US2861002 *Feb 9, 1956Nov 18, 1958Borden CoHot melt resinous adhesive composition
US2904467 *Jul 30, 1957Sep 15, 1959Chapman Chem CoWood preservative grease
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3899466 *May 25, 1973Aug 12, 1975Ethyl CorpBrominated xylene diols
US3974260 *Oct 4, 1973Aug 10, 1976Hoechst AktiengesellschaftDesensitized free-flowing red phosphorus
USRE30193 *Feb 11, 1976Jan 15, 1980 Fire retardant agent
Classifications
U.S. Classification106/18.11, 252/607, 106/18.23, 106/18.18, 106/18.17, 106/18.19
International ClassificationB27K5/00, B27K3/50
Cooperative ClassificationC09K21/12, B27K3/50
European ClassificationC09K21/12