Patented Dec. 14, 1937 2,102,187 UNITED STATES PATENT OFFICE 2,102,187 METHOD OF ACCE LERATION OF GE LATN ZATION OF CELLULOSE INTRATE AND LIQUED NITRC ESTERS AND THE PROD UCT THEREOF James T. Power, Wilmington, Del, and Kenneth R. Brown, Tamaqua, Pa., assignors to Atlas Powder Company, Wilmington, Del, a corpo ration of Delaware No Drawing. Original application January, 6, 1934, Serial No. 705,622. Divided and this ap plication October 30, 1934, serial No. 750,736 4. Claims. (Ch. 52-22) This invention relates to the acceleration of the and ungelatinized cellulose nitrate. The Sensi gelatinization of cellulose nitric esters and liquid tiveness to detonation, the velocity of detonation, nitric esters, particularly glycerine trinitrate and and the length of time the product may be stored mixtures of glycerine trinitrate with its freezing before it becomes unsatisfactory to use, are ad point depressants, such as the glycol nitric es versely affected. s ters, polymerized glycerine nitric esters, nitric Increasing the time of gelatinization or ele esters of chlorhydrins, etc., and to the products vation of the temperature of the reacting ma resulting therefrom. terials, while of some benefit, does not overcome The present application is a division of our co the trouble and either prolongation of the time O pending application, Serial Number 705,622, of mixing or elevation of the temperature in 10 fled January 6, 1934. troduces additional hazards. Acetone, alcohol The object of our invention is to gelatinize ether mixtures and similar solvents of relatively cellulose nitric esters by means of liquid nitric low boiling point have been tried but are not de esters with the aid of more efficient gelatiniza sirable due to their unfavorable effect. On Sensi 5 tion accelerators than any heretofore known or tivity and keeping properties of the explosives in 5 used; thus making a more satisfactory product storage. and obtaining greater speed, economy, and flex We are aware that, U. S. Patent No. 1,640.72, ibility in the production of compositions which issued to Moran, claims glycols as accelerators in involve this process, as for example, smokeless the gelatinization of cellulose nitrate with nitro 2 powder, blasting gelatins, gelatin dynamites and glycerine mixtures. However, we have found 20 plastics. W that fully substituted glycols, such as ethoxy In the manufacture of explosives such as blast ethyl acetate (cellosolve acetate) are much ing gelatin, gelatin dynamites, semi-gelatins, more efficient than the glycols thern Scycs. The Smokeless powders, etc., which contain cellulose most effective substituents are the monovalent 25 nitrate and liquid nitric esters such as nitro hydrocarbon residues, acyl groups (and mono glycerine, glycol nitrates, dinitrochlorhydrin, etc., valent inorganic acid radicals). Compounds of 25 it is the usual practice to gelatinize the cellulose this type may be represented, as derived by the nitrate by adding it in the fibrous form, to the etherification or etherification and estcrification liquid nitric ester or mixture of two or more of all of the hydroxys of a polyhydric alcohol. 30 nitric esters, contained in a mixer provided with The derivation of these products may be norc 30 an agitator. The mixer may or may not be pro clearly illustrated by considering a polyhydric vided with means for satisfactorily applying heat. alcohol, such as glycol, or glycerine, to have at The choice of liquid nitrates, cellulose nitrate and least one of its hydroxyl groups replaced by an degree of gelatinization have heretofore deter alkoxy group, and all of any of the remaining mined whether or not heat was necessary. While hydroxyls replaced by a monobasic organic acid 35 nitroglycerine and ethylene glycol dinitrates are radical or an inorganic acid radical. By alkoxy Solvents of cellulose nitrates of the class used in grOlip We nean a Saturated a cyclic monohydric the manufacture of gelatinized explosives as alcohol from which the hydroxylic hydrogen above described, the solvent action of nitro atom has been removed, and having the formula 40 glycerine is very slow and that of ethylene glycol (CnH2n-1)-O. For example, in our preferred 40 dinitrate, although faster, is still relatively slow. accelerator, namely, ethylene glycol ethyl ether To hasten the solution of the cellulose nitrate acetate, or (3-ethoxyethyl acetate, the polyhy heat is usually provided. v. Complete gelatiniza dric alcohol, ethylene glycol, has one hydroxyl tion of all the cellulose nitrate fibres is very group replaced by the ethoxy group, and the One 45 difficult to obtain. The fibres tend to form ag remaining hydroxyl group replaced by the mono 45 gregates of more or less incompletely gelatinized basic organic acetate radical. cellulose nitrate. The surfaces of these ag These compounds are by definition fully sub gregates are covered with a film of gelatinized stituted and contain no free hydroxyl groups. material which prevents the penetration of liquid Our improved process of gelatinization may be 50 nitric ester to the interior of the aggregate in carried out in different ways. We may add the 50 sufficient amount to effect complete gelatiniza accelerator to the liquid nitric esters or a mix tion Even with excessive periods of mixing it. ture of liquid nitric esters and cellulose nitrate in is difficult to break down all of these aggregates. the mixing bowl; we may choose to mix. the cel The re.ult is a distribution throughout the fin lulose nitrate and the accelerator to form a solu ished explosive of gelatinized, partly gelatinized tion before admixing the liquid nitric esters; 1. 1 2 2,102,187 or we may elect to mix the accelerator and liquid of an accelerator comprising g-ethoxyethyl face nitric ester and then add the cellulose nitrate. tate (celloSolve acetate). We prefer to stir the mixture during and subse 3. The process of gelatinizing cellulose nitric quent to the addition of the cellulose nitrate. esters with liquid nitric esters which comprises We may elevate or reduce the temperature by bringing about the gelatinization in the presence 5 adding or subtracting heat during the mixing, of an accelerator comprising ethoxyethyl nitrate depending on the selection of materials, the de (celloSolve nitrate). m gree of gelatinization desired, and the time avail 4. An explosive composition comprising nitro able for carrying out the process. cellulose gelatinized with a liquid nitric ester in O The quantity of accelerator required for this the presence of 0.1% to 5.0% of an accelerator 0. gelatinization is Small, usually ranging from 0. comprising 6-ethoxyethyl acetate (celloSolve ace to 5% of the explosive composition. tate). As an illustration of the efficacy of accelerators 5. The process of gelatinizing cellulose nitric of the type herein disclosed we give the following esters with liquid explosive nitric esters Which 5 example: comprises bringing about the gelatinization in 5 Eacample I the presence of an accelerator comprising at least To a mixture of 1.5 parts cellulose nitrate and one of the group of compounds derivable from a 100 parts low-freezing nitroglycerine, part of polyhydric alcohol having not more than 3 hy B-ethoxyethyl acetate (cellosolve acetate) was droxyl groups by replacing at least one of the added, and the mixture stirred until gelatinized. hydroxyl groups by an alkoxy group containing 20 This required 10 minutes. To reach the same not more than 4 carbon atoms, and replacing all degree of gelatinization without the accelerator of any remaining hydroxyls by a monobasic acid 85 minutes were required. radical taken from the group consisting of the As cited above the esterification may be carried radicals of paraffin acids containing not more 25 Out with inorganic acids as well as organic. Thus, than 4 carbon atoms, and nitric acid radical. 25 in the case of etherified nitrates, Such as cello 6. A process as in claim 5, wherein all the hy Solve, or ethoxyethyl nitrate, we may choose to droxyls of the polyhydric alcohol are replaced by add the celloSolve to the glycerine or glycol mix alkoxy groups. ture and carry out the nitration of the ether 7. A process as in claim 5, wherein the acid 30 simultaneously with the nitration of the glycerine radicals are those of paraffin acids containing 30 Or glycol mixture. not more than 4 carbon atoms, 8. A process as in claim 5, wherein the acid Eacample radical is the nitrate radical. A mixture of 89 parts by weight of glycerine, 9. A composition of matter Comprising a cellul 10 parts ethylene glycol, and 1 part celloSolve lose nitric ester gelatinized with a liquid explosive 35 Was nitrated at 5.0-5.5 C. employing 511 parts of nitric ester in the presence of a minor proportion of an accelerator comprising at least one of the mixed acid having the composition group of compounds derivable from a polyhydric Percent alcohol having not more than 3 hydroxyl groups 40 Sulfuric acid---------------------------- 54.30 by replacing at least one of the hydroxyl groups 40 Nitric acid----------------------------- 45.33 by an alkoxy group containing not more than 4 The nitrated mixture was washed and neutralized carbon atoms, and replacing all of any remain in the cutonary manner. 91.5 parts of this oil ing hydroxyls by a monobasic acid radical taken were used for gelatinizing 8.5 parts of nitrocellu from the group consisting of the radicals of paraf lose. The gelatinization test was carried out at fin acids containing not more than 4 Carbon 45 30 C. Gelatinization took place in 442 minutes, atoms, and nitric acid radical. whereas a similar gelatin, made without any ac 10. A composition of matter containing an ac celerator, required 17 minutes to gelatinize. celerator as in claim 9, wherein all the hydroxyl Among the accelerators of the ge de groups of the polyhydric alcohol are replaced by scribed we may specifically mention as contem alkoxy groupS.