US 2443378 A
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Patented June 15, 1948' 2,443,378 QHEMICAL PROCESS AND PRODUCT Harry R. Dittmar and Daniel E. Strain, Wilmington, DeL, assignors to E. & Company, Wilmington,
Delaware 1. du Pont de Nemours Del., a corporation of No Drawing. Application July 8, 1944, Serial No. 544,146
This invention relates to improved processes for preparing hydrocarbon gels. It also relates to new incendiary compositions containing hydrocarbons in gelatinized form,
In the manufacture of certain incendiary munitions, particularly incendiary bombs containing hydrocarbon fuels, it is important that the hydrocarbon in the incendiary charge be gelatinized so that it may be expelled from the munition without disintegration into small particles. For satisfactory accomplishment of this result, it is necessary that the hydrocarbon gel have a maximum of strength without being friable, and without sacrifice of incendiary qualities.
An object of this invention is to provide a process for the manufacture of readily ignitable gelatinous fuel. Another object is to provide a gelatinous fuel which can be expelled from a munition with great force without being broken into small particles. Still another object is to provide a 13 Claims. (01.44-7) carbon mixtures. For example, lowboiling oreven gaseous hydrocarbons may be admixed with high-boiling hydrocarbons to obtain fuels which have relatively low ignition temperatures and at the same time high heat of combustion per unit volume of fuel. Moreover, it is sometimes desirable to add low-boiling olefin hydrocarbons to higher-boiling saturated hydrocarbons to obtain blends which, after gelatinization in accordance with this invention, can be readily ignited. In general, the weight of hydrocarbon fuel employed is at least 50%,.and preferably about 70% to 96%, of the total Weight of the gel.
' The aqueous alkaline materials which may be employed in the preparation of hydrocarbon gels according to this invention include the aqueous alkali metal hydroxides, the alkaline earth metal readily ignitable, gelatinous, hydrocarbon-containing mixture which has good stability when stored at either high or low temperatures. A further object is to provide a gasoline gel which, when ignited, does not flash, but burns smoothly at a controllable rate.
These and other objects are accomplished in accordance with this invention by admixing a hydrocarbon fuel with a viscolizing agent comprising a hydrocarbon-soluble acrylic resin, prefer ably a salt-forming hydrocarbon-soluble acrylic resin, and with an aqueous alkaline material. Other suitable ingredients, which may be, but need not necessarily be, present in the mixtures, include hydrocarbon-soluble soap-forming acids or salts thereof, plasticizers, rosin, and, in certain instances, various readily combustible materials.
The hydrocarbon fuels which are useful in the compositions of the present invention include the readily 'ignitable liquid hydrocarbons, such as gasoline, benzene, toluene, xylene, kerosene and higher-boiling liquid hydrocarbons. In one specific embodiment of the invention the hydrocarbon component is a mixture of hydrocarbons, namely a mixture of aromatic hydrocarbons (particularly benzene, toluene or xylene) and gasoline, containing about 5% to 30% by weight of the aromatic hydrocarbon to increase solubility of the viscolizing agent. This mixture, in accordance with this invention, results in gels having outstandingly good resistances tosyneresis on long storage. In some instances. hydrocarbon blends may be employed in this invention to increase the ease of ignition of the hydrowhat inferior.
' as free carboxyl groups.
oxides and hydroxides, and the water-soluble alkaline materials in general. The preferred aqueous alkaline materials are sodium or potassium hydroxides in 20% to aqueous solution, and calcium hydroxide slurries containing about 20% to of calcium hydroxide. In some instances, ammonia or water-soluble organic bases may be used, but the resultant gels generally are some- The amount of alkaline material employed usually is from about 0.5 to 10%, preferably 2% to 5%, of the total weight of the gel ingredients.
The acrylic resins which serve as viscolizing agents in the present invention include the polymers of alkyl acrylates and alkyl alkacrylates. For best results these acrylic resins should contain small amounts of salt-forming groups, such The carboxyl groups in any convenient manner, a carboxyl-containing monomer, by hydrolysis of ester groups during or after polymerization, or by mild pyrolysis of the polymer after it'hasbeen formed. The latter method is quite effective with isobutyl methacrylate polymers, which may be heated for several hours at about F., whereby some of the ester groups are converted to carboxyl groups. In general, polymerization of an acrylic or alkacrylic ester with an acrylic or alkacrylic acid give polymers containing salt-forming groups. Satisfactory interpolymers are obtained by emulsion polymerization of acrylic or alkacrylic ester and acrylic or alkacrylic acid in the presence of an emulsifying agent and a peroxy compound catalyst. tends to make the'interpolymers hydrocarboninsoluble, it is necessary that the acrylic or alkacrylic acid content of the interpolymers be quite may be introduced such as by the use of Since free carboxyl groups in such resins,
low, generally about 0.01 to 6.0%. Hydrocarbon solubility increases with increasing of size of the alkyl groups in the monomeric esters, hence it. is preferred to use interpolymer derived from methacrylic acid and alkyl metha-crylates having at least carbon atoms, in the ----CO0 alkyl groups. Among the preferred viscolizing agents are methacrylic acidbutyl methacrylate interpolymers, containing 0.02 to 3.0% methacrylic acid, and methacrylic acid-lauryl methacrylate interpolymers, containing 0.02 to 3.0% methacrylic acid. The butyl methacrylate so employed may be n-butyl, isobutyl or secondary butyl methacrylate. The amount of saltformin hydrocarbon-soluble acrylic resin employed is preferably about 1% to of the total weight of the gel. ant that the resin have a very high molecular weight, 1. e. a molecular weight sufilciently high to provide a gel structure in the hydrocarbon medium after theaddition Of alkali.
The soaps which may be present in the compositions described herein include alkali metal stearates, palmitates and oleates and alkali metal salts of the fatty acids derived from dimerized soybean oil. The plasticizers include hydrocarbon-soluble salts of, relatively high molecular weight acids such as the naphthenic acids. If desired the fatty acid component may be introduced in the form of an ester of the fatty acid. These soaps and plasticizers are preferably prepared by dissolving the appropriate acid in the hydrocarbon fuel along with the viscolizingagent, and forming the soaps in situ during the subsequent gelation with aqueous alkali. In general these hydrocarbon-soluble soaps lend vis- It is importcosity to the incendiary compositions, while the viscolizing agent provides the gel structure. The various gel ingredients, such as rosin, may be added prior to gelation with alkali if desired.
The compositions of the present invention may be prepared conveniently by dissolving the viscolizing agent and the organic acid, (1. e. stearic, palmitic, oleic, naphthenic, or the acids derived from dimerized soybean oil) in the hydrocarbon fuel and thereafter mixing the hydrocarbon solution with the aqueous alkaline material. It is sometimes desired to heat the hydrocarbon at a temperature in the range of from 25 to 100 C. to facilitate the solution of viscolizing agent. The gel is produced by thoroughly mixing the hydrocarbon solution with the alkaline material, preferably at a temperature of about 20 to 50 C'. After the treatment with the alkaline material, the resultant gel is stored, suitably for a period of about 24 hours, before it is ready for use. If desired, a plasticizer, and/or various readily ignitable fuels may be added in any stage during the preparation of the incendiary composition, such as during the solution of the viscolizing agent in the hydrocarbon.
In a preferred embodiment of this invention a solution of.isobuty1 methacrylate-methacrylic acid interpolymer in gasoline is mixed with stearic acid and then passed continuously through a tube wherein it comes in contact with an injected stream of 40% solution of sodium hydroxide in The resultant composition is thoroughly mixed, suitably in a centrifugal pump, and the incendiary gel is removed from the outlet tube and stored in a suitable container.
In the following examples reference is made to certain tests whereby several of the compositions of this invention were evaluated. Such tests include the determination of impact The impact strength was measured by the following method. A Schopper Dynstat plastics impact tester was modified to handle gels. A blade one quarter inch wide was mounted on a pendulum with a total length of 15 inches. A trough to retain the gel sample was placed horizontally at the bottom of the swing of the pendulum. By determining the vertical height of the upward swing of the pendulum under various loads the work requiredto force the blade through the gel on an arc whose chord was 26 cm. long was measured and labeled the impact strength. The units are empirical but approximate kilogram centimeters.
The viscosity of the gel was determined by means of the parallel plate test, which is a modification of the test used for determiningthe consistency of putty (H. A. Gardener, Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors, 8th edition, Jan. 1, 1937, pp. 599-601)., It consists of measuring the diameter in cm. of the circle to which 5 c. c. of gel spreads in one minute between parallel plates of glass under a 2 kilogram load.
The stability of the gel, 1. e. the per cent syneresis under predetermined conditions, was measured by storing the gel samples in sealed bottles under the following test conditions: (1) one month at 40 F., (2) 6 months at room temperature, and (3) one month at 125 F. In carrying out the test, a weighed sample of the gel to be tested was placed in a. screw cap bottle and the bottle sealed. After exposure to one of the above test conditions the bottle and gel sample were inverted and the amount of free hydrocarbon which could be poured off was noted in terms of percent of the total sample.
The test for comparative burning time was made as follows: grams of gel was spread out on a metal tray which was '7 inches in diameter. The gel and tray were placed in a draft-free area. The gel was ignited and the duration of combustion determined.
The invention is further illustrated by the following examples in which parts are by weight.
Example 1.A solution containing 87 parts of gasoline, 5 parts of isobutyl methacrylate-methacrylic acid interpolymer (.028% methyl methacrylic acid), 2.5 parts stearic acid and 2.5 parts naphthenic acid was thoroughly mixed with 3 parts of 40% aqueous sodium hydroxide solution at room temperature. A strong, easily ignitable hydrocarbon gel was thus obtained.
Example 2.A solution containing 86.5 parts gasoline, 3 parts of isobutyl methacrylate-methacrylic acid interpolymer (.028% methacrylic acid) and 4 parts of stearic acid was mixed thoroughly with 4 parts of ground calcium oxide, and 2.5 parts of water was added with continued agitation. A firm, stable gel was thus obtained.
Example 3.A dispersion containing 87.8 parts of gasoline, 0.75 part of alpha-cellulose, 2 parts of isobutyl methacrylate-methacrylic acid interpolymer (containing 0.3% methacrylic acid), 2 parts of stearic acid, 2 parts of naphthenic acid and'2 parts of rosin was thoroughly mixed with 3.7 parts of 40% aqueous sodium hydroxide solution. A strong stable gel with good adhesive properties was thus obtained.
Example 4.-A mixture containing 87.5 parts of gasoline, 2 parts of isobutyl methacrylatemethacrylic acid interpolymer (028% methacrylic acid), 3 parts of stearic acid and 3.parts of naphthenic acid was metered to a centrifugal pump along with a metered stream of 4.5 parts of 40% aqueous sodium hydroxide solution. The desired agitation was achieved by feeding the reaction mixture to the centrifugal pump .at a rate lower than the rated capacity of the pump. In this manner a satisfactory gel of controllable composition was produced'continuously by feeding the reaction mixture at the rate of pounds per minute to a centrifugal pump having a capacity of pounds per minute.
Example 5.Several hydrocarbon gels were prepared, and their properties were determined. as shown in the following table.
Preparation and properties of gasoline gels Composition (wt. per cent) A "B C D V lsobutylmethacrylate-methacrylic acid mterpolymcr containing 0.028% methacrylic acid 3 Isobutyl methacrylate-methacrylic acid lnterpolymer containing 0.3% methacrylic acid 4 4 6 Siearic Acid 4 Na hthenic Acid 1 40 Na H... l 1.5 1 C80 (40 mesh) 4 Hz0. 2- Gasoline 75 73. 5 73 86. 5 Toluene 20 20 Physical Properties Impact. Strength 15. 2+ l5. 2+ 17. 2+ 14.8 Parallel Plate Test, cm. at-
Stability Per Cent Summer:-
1 mo. at F 0 0.8 0 10.2 1 mo. at 125 F ll 0. 4 0 0. 5
Incendiary Characteriafics Comparative Burning Time, minutes 2. 7 2. 8 3. 0 0. 5
0.6 (as 40% NaOH). 1 0.9 (as 40% NaOH). 3 0.6 (as 40% NaOH).
From the foregoing it is clear that the compositions of the present invention are incendiary gels which contain a liquid hydrocarbon, as
.contain salts of fatty acids (about 0.5 to 5.0%),
about 2 parts of a salt of rosin, and certain other materials such as solid fuels, oxidizing agents and I the like.
The compositions disclosed herein may be used in many difierent ways, such as in combination with any suitable means for igniting combustible materials. If desired, the gel may be reinforced with fibrous materials, or by enclosure in a suitable sack, which may encase the gel prior to and during its expulsion from the munition. The incendiary gels/of the present invention may be used for various fuel purposes, as in canned heat compositions. More broadly considered, the invention provides gels made from hydrocarbons generally, and so includes gelatinous compositions which are useful as lubricants, sealing mixtures, leather softening agents, and the like.
Since many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof it will be understood that we do not limit ourselves except as has been set forth in the following claims.
1. A process for preparing a hydrocarbon gel having a readily ignitable liquid hydrocarbon terpoiymer containing at least 5 carbon atoms in the CO0 alkyl groups, said interpolymer having from 0.01 to 6.0% by weight of the methacrylic acid component. and admixing the resultant solution with an aqueous alkaline material of the class consisting of alkali metal hydroxides, alkaline earth oxides and alkaline earth hydroxides, whereby a' hydrocarbon-containing gel is obtained, the relative quantities of gel ingredients being such that the amount of hydrocarbonsoluble alkyl methacrylate-methacrylic acid interpolymer is from 1% to 10% of the weight of the gel, and the amount of water is suflicient to effect gelatinization of the mixture, said amount of water being not less than 0.6% nor more than 3.0% of the weight of the gel, the amount of the said alkaline material being from about 0.5 to 10% of the total .weight of the ingredients of the mixture.
2. The process set forth in claim 1, wherein the said aqueous alkaline material is aqueous sodium hydroxide solution containing about 20% to 60% by weight of sodium hydroxide.
3. The process set forth in claiml, wherein the said aqueous alkaline material is a calcium hydroxide slurry containing about 20% to 70% by weight of calcium hydroxide.
4. A process for preparing a. hydrocarbon gel having a readily ignitable liquid hydrocarbon fuel as the chief ingredient which comprises dissolving in a liquid hydrocarbon a butyl methacrylatemethacrylic acid interpolymer containing from 0.01 to 6.0% by weight of the methacrylic acid component, and admixing the resultant solution with an aqueous alkaline material of the class consisting of alkali metal hydroxides, alkaline earth oxides and alkaline earth hydroxides, whereby a hydrocarbon-containing gel is obtained, the amount of the said alkaline material being from about 0.5 to 10% of the total weight of the gel ingredients, the relative quantities of the said ingredients being such that the amount of hydrocarbon soluble butyl methacrylatemethacrylic acid interpolymer is from 1% to 10% by weight of the gel, and the amount of water is from 0.6 to 3.0% of the weight of the mixture.
5. The process set forth in claim 4, wherein the said liquid hydrocarbon is a hydrocarbon mixture containing about 5% to 30% by weight of an aromatic hydrocarbon of the class consisting of benzene, toluene and xylene.
6. A process for preparing a hydrocarbon gel having a readily ignitable liquid hydrocarbon fuel as the chief ingredient which comprises dissolving in a liquid hydrocarbon a butyl methacrylate-methacrylic acid interpolymer containing from 0.01 to 6.0% by weight of the methacrylic acid component and a. soap-forming fatty acid, and admixing the resultant solution with an aqueous alkaline'material of the class consisting of alkali metal hydroxides, alkaline earth oxides and alkaline earth hydroxides, whereby a hydrocarbon-containing gel is obtained, the amount of the said alkaline material being from about 0.5 to 10% of the weight of the gel ingredients, the relative quantities of the gel ingredients being such that the amount of butyl methacrylatemethacrylic acid in'terpolymer is from 1% to 10% of the weight of the gel, and the amounts of the resulting salt of fatty acid, and water, are .about 0.5 to 5.0% and 0.6 to 3.0% respectively of the total weight of the gel ingredients.
7. The process set forth in claim 6, wherein the said liquid hydrocarbon is gasoline.
8. The process set forth in claim 6 wherein the said fatty acid is stearic acid.
.9. The process set forth in claim 6 wherein the said fatty acid is palmitic acid.
10. The process set forth in claim 6 wherein the said fatty acid is oleic acid.
11. A process for preparing a hydrocarbon gel having a readily ignitable liquid hydrocarbon as the chief ingredient which comprises dissolving in a liquid hydrocarbon an isobutyl methacrylatemethacrylic acid interpolymer containing from 0.01 to 6.0% by weight of the methacrylic acid component and a soap-forming fatty acid, and admixing the resultant solution with an aqueous alkaline material of the class consisting of alkali metal hydroxides, alkaline earth oxides and alkaline earth hydroxides, whereby a hydrocarboncontaining gel is obtained, the amount of the said alkaline material being from about 0.5 to 10% of the weight of the gel ingredients, the relative quantities of the gel ingredients being such that the amount of isobutyl methacrylatemethacrylic acid interpolymer salt is from 1% to 10% of the weight of the gel, and the amounts of the resulting salt of fatty acid, and water, are,
of the component of the class consisting of acrylic acid and methacrylic acid, and admixing the resulting solution with an aqueous reagent containing about 2% to 5% by weight, based on 5 the total weight of the gel ingredients. of alkaline material of the class consisting of alkali metal hydroxides. alkaline earth oxides and alkaline earth hydroxides, whereby an incendiary hydrocarbon-containinggel i obtained, the weight of the said hydrocarbon fuel employed being from 50% to 96% of the total weight of the gel, the relative quantities of gel ingredients being such that the amount of the said interpolymer is from 1% to 10% of the weight of the gel and the amount of water is about 0.6 to 3.0% of the total weight of the mixture.
13. An incendiary gel composed of gasoline as the chief ingredient, 0.6 to 3.0% by weight of water, 1 to 10% of a salt selected from the group of alkali metal and alkaline earth metal salts of isobutyl methacrylate-methacrylic acid interpolymers containing from 0.01% to 6.0% methacrylic acid, and about 0.5 to 5.0% of a, salt selected from the group of alkali metal and alkaline earth metal salts of stearic. palmitic, and oleic The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,984,417 Mark et a1. Dec. 18, 1934 2,274,673 I Earle Mar. 3. 1942 Certificate of Correction Patent No. 2,443,378.
HARRY R. DITTMAR ET AL.
June 15, 1948.
It is hereby certified that error appears in the printed specification of the above numbered patent'requiring correction as follows: Column 2, line 32, after the syllable mers insert and interpol'ymers; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.
Signed and sealed this 31st day of August, A. D. 1948.
THOMAS F. MURPHY,
Assistant Uommissz'oner of Patents.