US3498925A - Smoke generating compositions - Google Patents

Description

US. Cl. 252-305 8 Claims ABSTRACT OF THE DISCLOSURE A smoke agent consisting essentially of (a) a mixture of organometallic and organometallic hydride compounds such as triethylaluminum and diethylaluminum hydride, (b) an aromatic substance having up to three carbocyclic aromatic, six-membered rings and from six to 20 carbon atoms, said aromatic substance being composed solely of carbon and hydrogen, e.g., a-methylnaphthalene, and (c) a component selected from petroleum oil and mixtures of petroleum oil and fluorocarbons. Smoke is produced by exposing the smoke agent to the atmosphere.

This application is a continuation-in-part of applicants prior copending application Ser. No. 473,224, filed July 19, 1965, now US. Patent No. 3,400,082.

This invention relates to agents which produce smoke. More specifically, it relates to smoke-producing agents containing a mixture of organometallic and organometallic hydride compounds. In a highly preferred embodiment, this invention relates to smoke-producing formulations which contain a mixture of organoaluminum and organoaluminum hydride compounds.

Many of the smoke-producing formulations proposed in the past have serious deficiencies. For example, they may be too expensive. Similarly, many smokes produced by prior art smoke agents are toxic, corrosive or irritating to the skin and eyes. Thus, in many instances, personnel anticipating contact with smoke must wear protective clothing and use a breathing apparatus to obviate untoward effects produced by the smokes. Such protective measures are costly, reduce personnel efficiency and present logistic problems.

For certain operations by the armed forces, law enforcement agencies and the like, non-irritant, non-toxic and non-flammable obscuring smokes are desired. To avoid or minimize the deleterious consequences arising from the use of hazardous smokes, prior workers have proposed that smokes be generated from petroleum oils using heat sources such as specially designed heaters,

. turbine or diesel engines, or from oils or water in combination with certain chemical agents. In all of these instances, bulky, complex equipment is required which presents logistic problems and renders these methods impractical in certain instances; for example, in aerial and jungle operations.

United States Patent Smoke-producing agents commonly employed today,

e.g., FS (sulfur trioxide-chlorosulfonic acid) and FM (titanium tetrachloride), which depend upon the reaction of x the moisture in the atmosphere, vary markedly in effithis invention do not depend solely upon a reaction with atmospheric moisture but rather, to a large extent, upon the presence of atmospheric oxygen. Hence, the agents.

of this invention do not vary so widely in efliciency and quantity of smoke produced as do the above named and 3,498,925 Patented Mar. 3, 1970 designated prior art formulations. However, the smokeproducing formulations of this invention can produce smoke by reacting with water or oxygen. This is an important feature of this invention.

In our copending parent application Ser. No. 473,224, filed Aug. 19, 1965, now US. Patent No. 3,400,082, we have disclosed a new type of smoke agents having properties superior to the conventional smoke agents. The smoke agents covered by our copending application consist essentially of aluminum trialkyl, and aromatic hydrocarbon and a petroleum lubricating oil. The smoke agents of the present invention, while possessing all superior properties of the agents of our copending application, also contain additional beneficial properties. For example, the smoke agents of the present invention produce smoke, as the formulations in the copending application, merely by coming in contact with oxygen and/ or moisture. However, the agents of this invention are more stable than the agents in our copending application and, therefore, in some instances may beof even greater value than the compositions disclosed in our copending application.

Thus, an object of this invention is to provide improved smoke-producing agents which do not have many of the deficiencies of the prior art smoke-producing agents and/or methods. A further object is to provide nonirritant, non-toxic, and non-flammable obscuring smokes. Additional objects will be apparent from the following detailed description and appended claims.

The objects of this invention are accomplished by providing smoke-producing formulations containing a mixture of organometallic compounds.

Essentially, the smoke formulations of this invention comprise a mixture of an organometallic and organometallic hydride compounds, and one or more diluents and/or flame suppressants to control the rate of oxidation and/ or hydrolysis of the organometallic compounds. In a preferred embodiment, the smoke formulations of this invention comprise an organometallic compound, an aromatic substance, petroleum oil, and/ or a fluorocarbon. In a very highly preferred embodiment, this invention provides a smoke agent consisting essentially of (a) A mixture of an alkyl aluminum having the formula R Al and an alkyl aluminum hydride having the formula R AlH wherein R is an alkyl radical solely composed of carbon and hydrogen and having up to six carbon atoms, and x and y are one or two;

(b) An aromatic compound having up to three carbw cyclic aromatic six-membered rings and from 6 to 20 carbon atoms, said aromatic compound being solely composed of carbon and hydrogen, and

(c) A petroleum oil.

As stated above, the smoke-producing formulations of this invention contain a mixture of organometallic compounds. Compounds of aluminum, boron and zinc are preferred. Applicable organoaluminum compounds include those having the formula wherein R is an organic radical having up to six carbon atoms, said radical being selected from alkyl or aryl groups. Most preferably, R is an alkyl group having up to six carbon atoms which is solely composed of carbon and hydrogen.

Applicable organoaluminum hydrides include those having the empirical formula:

wherein R is anorganic radical having up to six carbon atoms, said radical being selected from alkyl and aryl groups, and x and y are one or two. Preferably, R is an alkyl group having up to six carbon atoms which is solely composed of carbon and hydrogen. 1

In addition to the aluminum compounds formulated above, boron compounds having the formulae:

R3B and R BH wherein R is an alkyl or aryl group having up to six carbon atoms and x and y are one or two, can also be employed. Similarly, zinc compounds having the formulae:

wherein R has the same significance as defined above can also be used.

Highly preferred organoaluminum compounds employedin this invention include tri-n-propylaluminum, trin-butylaluminum, triisobutylaluminum, tri-n-amylaluminum, tri-sec-amylaluminum, tri-n-hexylaluminum, triphenylaluminum, ethyldiphenylaluminum, and the like, and mixtures thereof. A most highly preferred aluminum alkyl is triethylaluminum.

Highly preferred organoaluminum hydrides employed in this invention are diethylaluminum hydride, dimethylaluminum hydride, di-n-propyla-luminum hydride, diisopropylaluminum hydride, diisobutylaluminum hydride, ethylmethylaluminum hydride, ethyl-n-propylaluminum hydride, isopropylisobutylaluminum hydride, and the like, and mixtures thereof.

All the organic radicals bonded to the metal atom or atoms (in the organometallic compounds employed in this invention) need not be identical. For example, two or three different radicals can be bonded to aluminum. Compounds of this type are illustrated by dimethyl ethyl aluminum, diethyl methyl aluminum, methyl diisopropyl aluminum, methyl hexyl butyl aluminum, and the like. Thus, the triorgano aluminum compounds applicable in this invention include compounds having the formula RRRA-l wherein R, R and R" are alike or different alkyl radicals of one to six carbon atoms. Diorganoaluminum hydrides include compounds having the formula wherein R and R are alike or different alkyl radicals of one to six carbon atoms as exemplified above.

Whenever a triorganoaluminum compound is mixed with a diorganoaluminum hydride, the resulting composition does not remain merely as a physical mixture of two specific compounds. Under such conditions, molecular rearrangement or disproportionation takes place. Thus, the organic and the hydrogen radicals exchange until an equilibrium is obtained. The end result is that the composition is not merely a mixture of tWo compounds, but a mixture of many compounds containing compositions intermediate between the two original compounds.

The operation of disproportionation may be illustrated by the following example. If originally triethylaluminum, triisobutylaluminum and diethylaluminum hydride are mixed, the resulting disproportionation product will contain the following intermediate compounds: diethylisobutylaluminum, ethylisobutylaluminum hydride, ethyldiisobutylaluminum, and diisobutylaluminum hydride. Similar disproportionation takes place when mixture of triorganoboron and diorganoboron hydride are employed.

In addition to the metallic compounds noted above, preferred formulations of this invention also contain an aromatic compound. Applicable aromatic materials are those which have one carbocyclic aromatic six-membered ring or from two to three fused carbocyclic aromatic sixmembered rings. Preferably these compounds are solely composed of carbon and hydrogen and most preferably, they also contain from 6 to about carbon atoms. Preferred substances of this type have up to 20 carbon atoms and are selected from the class consisting of alkyl-substituted benzene such as xylenes, naphthalene, alkyl-substituted naphthalenes, acenaphthene, alkyl-substituted acenapthenes, fluorene, alkyl-substituted fluorenes, phenanthrene, alkyl-substituted phenanthrenes, anthracene, and alkyl-substituted anthracenes. Of these compounds, naphthalene and the alkyl-substituted naphthalenes are preferred. Highly preferred alkyl naphthalenes are ot-methylnaphthalene, a-ethylnaphthalene, and fl-methylnaphthalene. A very highly preferred aromatic substance is amethylnaphthalene.

The third major ingredient in the preferred formulations of this invention is a petroleum oil. In general, any petroleum oil can be employed. A preferred oil is mineral oil such as USP white mineral oil. A very highly preferred oil is Neutral No. 75 oil which is a distilled solventrefined, dewaxed petroleum oil having a viscosity in Saybolt Universal Seconds at 100 F. within the range of from about 70 to 80. Usually oils of this type have a viscosity in Saybolt Universal Seconds within the range from 72 to 78.

Another preferred oil is Circo XXX Light Oil which is a naphthenic oil having a viscositly in Saybolt Universal Seconds at 100 F. within the range of from about 55-60. Still another preferred oil is Circosol 410 oil which is also a naphthenic oil having a viscosity in Saybolt Universal Seconds of about 100. Generally, petroleum base oils having a viscosity in Sabolt Universal Seconds in the range of from about 40 to about 200 may be employed.

In addition to the petroleum oils described above, other petroleum fractions can also be employed. For example, ordinary heating oils, diesel oil, and kerosene may be used. Similarly, crude petroleum can be employed. One or more of the above diluents can be used. For example, crude petroleum-kerosene mixtures are applicable as well as mixtures of home heating oils and kerosene In general, the smoke formulations of this invention contain from about 10 to about parts by weight of the organo-metallic compounds, from about 5 to about 50 parts of an aromatic substance of the type described above and from about 10 to about parts of petroleum or petroleumderived products (all parts are by weight). The organometallic component contains from about 10 to about 60 weight percent of organometallic hydride, and preferably from about 20 to about 40 weight percent. The preferred alkylaluminum formulations of this invention contain from about 10 to about 60 parts by weight of the organoaluminum compounds, from about 5 to about 20 parts by weight of one or more aromatic substances of the type described above, and from about 40 to about 70 parts of a petroleum lubricating oil.

In addition to the above-named ingredients, the formulations of this invention may optionally contain minor amounts, say up to about 10 percent by weight, of additives to prevent freezing, reduce flame hazards, improve solubilities or compatibilities, etc. Thus, the formulations of this invention may contain fluorocarbons such as Freons, silicones, dispersants, detergents, as Well as oxidizing salts such as ammonium nitrate, permanganates, chlorates, perchlorates, etc. In addition, the compositions of this invention may optionally contain metal alcoholates such as tetraisopropyl titanate (titanium tetraisopropylate), tetran-butyl titanate, and the like.

Ethers are a preferred type of additional ingredient which may optionally be included in the smoke-producing formulations of this invention. In general, from about 5 to about 90 parts by weight of an ether may be included in the formulations. Like the aromatic substances discussed above, the ethers seem to have a flame suppressant effect.

The preferred ethers are polyethers; in other words, they contain two or more ether oxygen atoms. Preferred polyethers are the diethers and triethers (ethers containing 2 and 3 ether oxygen atoms, respectively) having up to about 20 carbon atoms.

The diethers which are applicable herein are represented by the formula In this formula, R is a bridging group, that is, an alkylene radical of a branched or (preferably) a straight chain containing from one to about six carbon atoms. In addition, the bridging R group may be a cycloalkyl group, that is, it may be a-saturated ring containing from 4 to' 6 carbon atoms. In the above formula, R is a terminal group which may be a saturated, straight or branched chain alkyl group containing from 1 to carbon atoms. In addition, R can also be a saturated alicyclic group, that is, it may be an alicyclic ring radical containing from 4 .to '6 carbon atoms. R", like R, is a terminal group. Hence, it is selected from the same type of radicals as R. Preferably R and R" are identical radicals. Most preferably, they are alkyl radicals having from 1 to 4 carbon atoms. Illustrative but non-limiting examples of diethers which are applicable in this invention include dimethoxyethane, diethoxyethane, dibutoxyethane, and the like. 1 i

The most preferably polyethers are the triethers represented by the following formula:

In this formula, R, R and R have the same significance as that in the above formula which illustrates the diethers. Illustrative but non-limiting examples of triethers which are applicable in this invention include diethyleneglycol diethylether, dipropyleneglycol diethylether, dibutyleneglycol dimethylether, dipropyleneglycol dibutylether, dihexyleneglycol diisopropylether, dihexyleneglycol dibutylether, and the like. Very highly preferred triethers are diethyleneglycol dimethylether and diethylene'glycol dibutylether. Other polyethers such as triethyleneglycol dialkylethers can also be used.

The formulations of this invention can be prepared in any convenient manner. -It is only necessary to mix the desired ingredients in the desired amounts. In many instances, it is preferable to mix the ingredients under a blanket of an inert atmosphere. Many inert gases can be employed to supply the inert atmosphere, e.g., nitrogen, neon, argon, and the like. Because of its low cost and availability, nitrogen is the preferred inert gas.

The smoke formulations of this invention produce smoke upon exposure to oxygen or moisture. Exposure to these materials is conveniently carried out by rupturing a vessel containing the formulations or byflowing the formulation through a valve and nozzle.

The following examples illustrate the smoke-producing formulations of this invention and are non-limiting. All parts are by weight unless otherwise noted.

EXAMPLE 1 A smoke-producing formulation was prepared by mixing the following ingredients in the amounts stated under nitrogen:

Y Parts Triethylaluminum-diethylaluminum hydride (containing 28i2% of the hydride) a-Methylnaphthalene 10 Circosol 410 oil 65 This formulation is activated by oxygen and/or moisture in the air to produce a dense white smoke. The formulation is a clear mobile. liquid at temperatures above 20 F. The above formulation is. chemically stable under storage conditions of F. to 120? E, The

density of the material is about 0.85 gram per ml.

EXAMPLE 2 A smoke-producing formulation was prepared by mixing the following ingredients in the amounts stated under nitrogen:

6 The properties and smoke producing ability of this formulation is substantially the' same as described in Example 1.

EXAMPLE 3 A smoke-producing formulation was prepared by mixing the following ingredients in the amounts stated under nitrogen:

Parts Triethylaluminum-diethylaluminum hydride 30 Dibromotetrafluoroethane (Freonll4 B2) 15 Neutral No. oil 55 EXAMPLE 4 A smoke-producing formulation was prepared by mixing the following ingredients in the amounts stated under nitrogen:

Parts Triethylaluminum-diethylaluminum hydride 30 a-Methylnaphthalene 12.4 Dibromotetrafluoroethane (Freon-114 B2) 5 Neutral No. 75 oil 52.6

EXAMPLE 5 A smoke-producing formulation was prepared by mixing the following ingredients in the amounts stated under nitrogen:

Parts Triethylaluminum-diethylaluminum hydride 30 a-Methylnaphthalene 12.4 Dibromotetrafiuoroethane (Freonl14 B2) 10 Neutral No. 75 oil 47.6

EXAMPLE 6 A smoke-producing formulation was prepared by mixing the following ingredients in the amounts stated:

Parts Triethylaluminum-diethylaluminum hydride 30 OL-MCl'hYlIlElPhlhfllCllG 5 Dibromotetrafluoroethane (Freon-1l4 B2) 12.5 Neutral No. 75 oil 52.5

Similar formulations are prepared by substitution of triethylaluminum-diethylaluminum hydride in Examples 1 to 6 with the following mixtures of aluminum compounds: triisopropylaluminum diisopropylaluminum hydride, triethylaluminum diisopropylaluminum hydride, triisopropylaluminum-diethylaluminum hydride.

EXAMPLE 7 A smoke-producing formulation was prepared by mixing the following ingredients in the amounts stated under nitrogen:

Parts Triethylaluluminum-diethylaluminurn hydride 30 a-Methylnaphthalene 10 Dibromotetrafluoroethane (Freon-114 B2) 12.5 Neutral No. 75 oil 47.5

EXAMPLE 8 A A smoke-producing formulation was prepared by mix- EXAMPLE 9 A smoke-producing formulation was produced by mixing the following ingredients under nitrogen in the amounts stated:

Similar results are obtained when in the above example, diethyleneglycol dimethylether is substituted by Parts dipropoxybutane, dicyclohexyloxyethane, diethyleneglycol Triethylaluminum-diethylaluminum hydride 30 dibutylether, diethyleneglycol dipropylether, diethylenea-Methylnaphthalene 5 glycol dihexylether, or dibutyleneglycol dihexylether. Dibromotetrafluoroethane (Freon-114 B2) 12.5 The smoke formulations of this invention produce a Neutral No. 75 oil 2 relatively innocuous smoke. The solid and liquid parti- Circo oil 26.5 cles within the smoke are probably'the oxides of the EXAMPLE metals within the organometallic compounds, or hydrated 10 metal oxides, as well as the components within the dilu- A 9 formulatlon. 1S P R by mlxlng ents and flame suppressants, e.g., Neutral No. 75 oil and the following ingredients under nitrogen in the amounts ethylnaphthalene, respectively. Gaseous products stated: which are likely to be included in the smokes produced Parts by this invention are ethylene, butylene, butane, hydro- Trlethylallmlnum-dlethylalumlnum hydflde 30 gen, ethane, carbon dioxide. It is anticipated that the hywMelhYlnaPhthalfine 5 drocarbon diluents should be innocuous in the exposure gibromlotfiiafluloroethane (Freon-114 B2) time and concentration range time likely to be encounlrcoso O1 tered. The metal oxides within the smokes, e.g., alumi- In Examples 3 to 10, the content of the organoaluminum oxide, are generally considered to be relatively nonnum hydride is about 283:2 weight percent of the organotoxic. aluminum mixture. It was stated earlier that the smoke compositions of EXAMPLE 11 this invention contain certain improved properties over A smoke-producing formulation is prepared by mixing F P compositions disclosed in our Copending the following ingredients under nitrogen in the amounts plKfatlon 1 some of the Pf p d; which improvement is realized are flash point and fire P t point. The flash and fire points were determined by a Trimethylaluminum-isobutylaluminum hydride (cons andard method known as the Cleveland Open Cup taining 10% of the hydride) 15 Method, ASTM D92, described in ASTM Standards on Diethyleneglycol dimethylether 50 Petroleum Products and Lubricants published by the Phenanthrene American Society for Testing Materials, 1916 Race St., EXAMPLE 12 Philadelphia, Pa. Comparative results between the smoke formulation of this invention containing a mixture of A 9 formulatlon. 1S Prepfdred by mlxmg triethylaluminum and diethylaluminum hydride and the the following ingredients under nitrogen 1n the amounts 35 Smoke formulation in our copending application, Stated P t tioned above, containing triethylaluminum are given in M S the table below. Also reported in the table is the rela- Diethylisobutylaluminum hexylpropylaluminum hytive obscuring power of each smoke formulation. This dride (containing 20% of the hydride) 80 d Methylnaphthalcne 10 0 test is conducted in the following manner: A standard u 4 amount of a smoke agent was atomized into an air stream White mineral oil 10 in a smoke tunnel with the air flow rate kept as a con- Slmllar results are Obtamed when anthracaine stant .'Smoke densities were measured with an Autotron tylphenamhren? ii ifg naphtha Model P8L3/E8BC photocell-light source combination. are employed m p ace 0 y nap t a The output from the photocell was amplified and recorded EXAMPLE 13 by a Mosley Autograph Model 680 strip chart recorder. A Smoke producing formulation is prepared by mixing This gave a time-transmission record. By plotting the timethe following ingredients under nitrogen in the amounts 2 1 1? f l 1 the l'elatlve obscuring Power Of each d; smo e is o tame Parts In the table, the abbreviations have the following mean- Trihexylaluminum diethylaluminum hydride (conings:

taining 45% of the hydride) a-Methylnaphthalene 5 TEATriethylalu minum I Dibromotetrafluoroethane (Freon-114 B2) '15 TEA-DEAH-Triethylaluminum-diethylaluminiim Circosol 410 oil 10 55 hydride mixture. 1 Diethyleneglycol dimethylether 10 Freon-114 B2Dibromotetrafluoroethane TABLE Weight Percent gselative O Clll'lll a-Methyl- Freon- Neutral Circo Circosol power Flash point, Fire point, TEA TEA-DEAH naphthalene 114 B2 Qil XXX oil 410 oil percent F. F. 30 0 0 15.0 55.0 0 0 Inconelusive 174 17s 0 30 0 15. 0 55. 0 0 0 97 288 291 30 0 12. 4 5. 0 52. 5 0 0 100 111 111 0 30 12. 4 5. 0 52. 5 0 0 77 111 119 0 n 22 a 3 5 52 15 3 8 513 i215 5215 0 0 Not tested 187 100 0 30 5. 0 12. 5 52. 5 0 0 277 291 30 0 10.0 12.5 47.5 0 0 Not tested 180 183 0 30 10.0 12.5 47.5 0 0 288 29s 30 0 5.0 12.5 0 52.5 0 115 190 100 0 30 5. 0 i2. 5 0 52. 5 0 105 298 302 30 0 5.0 12.5 25.5 25.0 0 Not tested 199 208 o 30 5.0 12.5 25.5 25.0 0 273 295 30 0 5. 0 i2. 5 0 0 52. 5 Not tested 0 30 5. 0 12. 5 0 0 52. 5 277 277 From the above table it is seen that even though the relative obscuring power of the agents of this invention is generally similar to the obscuring power of the agents containing only triethylaluminum as the aluminum-containing component, the flash and fire points are very substantially improved. These properties are of great importance when dealing with smoke agents because the higher the flash and fire point, the more stable the agent is.

This invention is extended to cover smoke-producing formulations which contain hydrides such as boron hydrides. Furthermore, colored smokes may be attained by incorporating organometallic compounds, particularly of the pi-bonded type, whose metals form colored oxides.

Having fully described the novel compositions .of this invention, their method of preparation, and their use, it is desired that this invention be limited only within the lawful scope of the appended claims.

We claim:

1. A smoke agent consisting essentially of:

(a) from about 10 to about 80 parts by weight of a mixture of an alkylaluminum and an alkylaluminum hydride having the following formulae respectively:

wherein R, R' and R" are radicals solely composed of carbon and hydrogen and having up to six carbon atoms, said alkylaluminum hydride being in the amount of from 10 to about 60 weight percent of said mixture;

(b) from about to about 50 parts by weight of an aromatic substance having up to 3 carbocyclic, aromatic, six-membered rings, and from 6 to 20 carbon atoms, said aromatic substance being solely composed of carbon and hydrogen; and

(c) from about 10 to about 90 parts by weight of a component selected from the class consisting of petroleum oils and a mixture of petroleum oils and fluorocarbons, said fluorocarbon being in the amount of up to 10 weight percent of said smoke agent.

2. The smoke agent of claim 1 wherein:

(a) said alkylaluminum and alkylaluminum hydride mixture is in the amount of from about 10 to about 60 parts by weight, and R, R and R" are alkyl radicals having up to 6 carbon atoms;

(b) said aromatic substance is in the amount of from about 5 to about 20 parts by weight, and

(c) said component is a petroleum oil in the amount of from about 40 to about 70 parts by weight.

3. The smoke agent of claim 2 wherein R, R and R" are ethyl.

4. The smoke agent of claim 2 wherein said aromatic substance is selected from the group consisting of xylene, naphthalene, acenaphthene, alkyl-substituted naphthalenes and acenaphthenes, fluorene, alkyl-substituted fluorenes, phenanthrene, aikyl-substituted phenanthrenes, anthracene, and alkyl-substituted anthracenes.

5. The smoke agent of claim 2 wherein said aromatic substance is u-methylnaphthalene.

6. The smoke agent of claim 2 wherein:

(a) said mixture of alkylaluminum and alkylaluminum hydride is triethylaluminum-diethylaluminum hydride comprising about 25 parts by weight of the total composition, said mixture containing about 28 percent by weight of diethylaluminum hydride;

(.b) said aromatic substance being an a-methylnaphthalene comprising about 10 parts by weight of the total composition, and

(c) said petroleum oil being distilled, solvent refined, dewaxed petroleum oil having a viscosity in Saybolt Universal Seconds at 100 F. Within the range of from about 40 to 200, and comprising about parts by weight of the total composition.

7. The smoke agent of claim 2 wherein:

(a) said mixture of alkylaluminum and alkylaluminum hydride is triethylaluminum-diethylaluminurn hydride comprising about 20 parts by weight of the total composition, said mixture containing about 28 percent by weight of diethylaluminum hydride;

(b) said aromatic substance being an a-methylnaphthalene comprising about 10 parts by weight of the total composition, and

(c) said petroleum oil being distilled, solvent refined,

. dewaxed petroleum oil having a viscosity in Saybolt Universal Seconds at 100 F. within the range of from about 40 to 200 and comprising about parts by weight of the total composition.

8. The smoke agent of claim 1 wherein:

(a) said mixture of an alkylaluminum and an alkylaluminum hydride is in the amount of from about 20 to about 60 parts by weight and R, R and R" are alkyl radicals having up to about six carbon atoms;

(b) said aromaticsubstance is in the amount of from about 5 to about 20 parts by weight; and

(c) said component is a mixture of petroleum oils and fluorocarbons in the amount of from about 40 to about 70 parts by weight of petroleum .oil and in the amount of about 10 parts by weight of fluorocarbon, wherein said fluorocarbon is dibromotetrafluoroethane.

References Cited UNITED STATES PATENTS RICHARD D. LOVERING, Primary Examiner mg Wren smrre m'rrwr omen QEREKFEQA'LFEQ CF CCRfiECHCN mam Non 3, r9 ,925 Dated March 5, 1970 Invantgf(g) Martin E. Gluckstein, Ellis B. Rifkin, Harold A. Beatty It in certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

w Column 2, line 6, for "Aug," read July -3 Column 6,

line 57, for "prepared" read produced --3 Line 38, after "ingredients insert under nitrogen --3 Column 10, line 2,

for "aikyl" read alkyl linear:

Edward E m-3951A .Axmesfixmg @ffieer 33% Comisaiomer of Patents mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 9 9 5 Dated March 3, Q7

Inventor) Martin E. Gluckstein, Ellis B. Rifkin, Harold A. Beatt It in certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

II I! q Column 2, line 6, for Aug. read July ---3 Column 6, line 37, for "prepared" read produced --5 Line 38, after "ingredients" insert under nitrogen --3 Column 10, line 2,

for "aikyl" read alkyl smash mam) Edward 1!. TIME