Patented Sept. 11, 1945 2,384,730 UNITED STATES PATENT OFFICE 2,884,736 . RETO OF PREPARNG CAST EPLOSY CAES Clyde o. Davis and watam E. Kirst, woodbury, s N.Company, S., assignors Wilynington, to E. I. duDel, Pont a corporationde Nernors of& - Delaware No Drawing. Application August 7, 1943, Seria No. 49,853 5 Clains. (C. 52-22) This invention relates to cast explosive tol tetranitrate is time-consuming and is ac charges and more particularly to a more advan complished with considerable hazard. The dis tageous method for the preparation of blends of covery therefore that wet pentaerythritol tetra trinitrotoluene and pentaerythiritol tetranitrate. nitrate can be satisfactory introduced into the In the preparation of these blends, it has been melt is a very important advance. the practice of the art to employ carefully dried In preparing cast blends of TNT and PEN, pentaerythritol tetranitrate. There have been the mixture of the two is prepared and the TNT attendant difficulties it that lumps are formed maintained in molten condition, at a tempera on addition to note NT. ture between its melting point and 100° C. The This application is a continuation in part of 0. PETN is desirably in relatively finely divided our copending application, Serial No. 415,635, condition and thoroughly mixed with the TNT filed October 18, 1941. by agitation. A water layer forms almost in An object of the present invention is a high mediately on top of the melt and this Water car density cast explosive charge of outstanding be drawn off readily, leaving normally less than properties. A further object is an improved 5 5% ot-water in the molten blend. The melt can method for preparing explosive charges contain be formed and handled satisfactorily in steanna ing trinitrotoluene and pentaerythritol tetrar jacketed metal containers. Under such cond nitrate. A still further object is such a method toils, the greater part of the residuai Water in in which increased efficiency in handling the the neit will be removed by evaporatio in a ingredients results, and in which safety in opa relatively short time. We find it desirable, how eration is promoted. Additional objects will be ever, to hasten the removal of the water by pas disclosed as the invention is described Ore in sage of air through the net, it is desirable to detail hereinafter. dry the material to a moisture content not greater We have found that the foregoing objects are that a 0.1%. accomplished when we utilize pentaerythrito s Various compositions of such blends of tri tetranitrate wet with water and bring it into nitrotoluene with pentaerythritol tetranitrate mixture, with trinitrotoluene. The latter in can be prepared having desirable explosive prop molten condition is contacted with the penta erties. We find a 50-50 composition to give erythritol tetranitrate, and the water present in satisfactory results and, generally speaking, pre this latter material will rise to the surface. It 30 fer to maintain the composition within the range can then be decanted, drawn or skinned off, or of 35-7.5% pentaerythritol tetranitrate and 65 removed in any desired manner. - 25% trinitrotoluene. It will be understood that Two procedures may be followed in obtaining in such blends the trinitrotoluene is the con the mixture of PEN with molten N. For tinuous phase, with pentaerythritol tetranitrate example, we may bring the TNT into molten form 35 dissolved in the molten compound to an amount and introduce the Wet PEN thereito. We equal to approximately a tenth of the trinitro may, on the other hand, blend the solid TNT toluene by weight, with the remainder dispersed with the wet PETN and then raise the tempera therein. ture above the fusion point of the lower melting The following specific embodiments will serve compound. If desired, both explosive materials 40 as examples of methods employed to prepare . may be introduced into water and the temperan blends in accordance with the foregoing descrip ture of said water be raised above the fusion tion. point of the TNT, for example, by the passage Sacassisple of steam. Whatever the procedure, when the Two 5000-gram batches (about 1 lbs. each) wet PETN becomes blended with molten TNT, 45 were prepared by adding to molten trinitro the water present rises to the surface and may toluene heated to 98 C. pentaerythritol tetra be removed therefrom nitrate having a water content of 40%, the two The pentaerythritol tetranitrate available for compounds being used in a 50-50 relationship. commercial use is ordinarily in wet form. The The melts were made in a jacketed sheet-iron regulations require that this explosive for ship 50 pot, 9' in diameter by 6%' in depth, heated ping shall have a water content of at least 40% with steam at 0-lbs. pressure. All the trinitro and material in storage in large amounts should toluene was first brought into molten form and have no less water content. Consequently, the ... unheated pentaerythritol tetranitrate was added material available for use will ordinarily be in in 200-300 gram lots at such a rate that the very wet form. The drying of wet pentaerythri 55 nelt temperature remained batween 75-80 C.

2 2,884,730 As soon as all the pentaerythritol tetranitrate tion of melts, since it does not form lumps on . had been added, removal of supernatant water addition to molten trinitrotoluene. Such lumps was begun by means of a dipper. The molten are formed with dry pentaerythritol tetranitrate, blend was stirred at intervals and was allowed which becomes encased in layers of crystallized to stand with continued heating from the steam trinitrotoluene when the former cools the trini jacket. The Water content in each case trotoluene below its freezing point. The use of amounted to less than 0.1% after the elapse of material containing 40% of water, as a matter about 87 minutes. The removal of water was of fact, is gy advantageous Over that con evidenced by the change of color from whitish taining 18%, for example, and allows more rapid opacity to clear amber. 0 addition of the material to molten trinitrotoluene. Our invention has been described fully in the a . Eacample II foregoing. It will be understood, however, that Two 4000-gram batches (8.8 lbs. each) were many details in compositions and methods of pro prepared of 50-50 biends in a manner similar to cedure can be introduced without departure from that of Example I, except that in this case, the the scope of the invention. We intend to be pentaerythritol tetranitrate added had a water limited therefore only by the following patent content of 18%. After the water had been re claims, moved from the top of the melt, the material We claim: contained 4-5% water, as was found to be the 1. The method of preparing cast explosive case regardless of the original water content. 2) charges, which comprises blending trinitrotoluene The removal of the residual water was hastened and wet pentaerythritol tetranitrate, raising the by bubbling air through the melt. In this case, temperature of the mixture to a point where the the moisture content amounted to less than 0.1% trinitrotoluene becomes molten, removing the after about 54 minutes of operation. separated water from the surface of the blended Eacample III 25 charge and further reducing the water content by evaporation at an elevated temperature. A 5000-gram lot was prepared by mixing 2500 2. The method of preparing cast explosive grams of TNT with 3500 grams of wet PETN, charges, which comprises preparing a blend of having a water content of approximately 40%. 35-73%. pentaerythritol tetranitrate and 65-25% The mixture was in a jacketed kettle and was trinitrotoluene by mixing trinitrotoluene and heated to a temperature above the melting point pentaerythritol tetranitrate having a water con of TNT. After fusion was complete and thorough tent greater than 10%, heating to form a melt, mixture had been obtained, the water was rea removing the separated water from the surface moved from the surface by dipping. The mix of the blended charge, and bringing about further ture was then allowed to stand at a temperature drying by passage of air through the melt. above the fusion point until the clearness of the 3. The method of preparing cast explosive melt showed the elimination of substantially all charges, which comprises adding to molten tri the water. nitrotoluene pentaerythritol tetranitrate wet with Eacaniple IV more than 10% of water, removing the separated Similar amounts of TNT and wet PETN were water from the surface of the blended charge and brought into a jacketed sheet-iron pot containing further reducing the water content by evapora water. Steam was run into the mixture to tion at an elevated temperature, agitate the same and to raise the temperature 4. The method of preparing cast explosive above the melting point of the TNT. After charges, which comprises preparing a blend of thorough mixture, the supernatant water was re 45 35-7.5% pentaerythritol tetranitrate and 65-25% moved from the surface. Air was caused to pass trinitrotoluene by adding to the trinitrotoluene in through the fused mixture while it was main molten condition pentaerythritol tetranitrate tained at an elevated temperature, and a dry having a water content in excess of 10%, remov-, mixture was thereby obtained. ing the separated water from the surface of the The advantages of the process according to our 50 blended charge and bringing about further drying invention can be readily appreciated. As has al by passage of air through the melt. ready been stated, the use of wet pentaerythritol 5. The method of preparing cast explosive tetranitrate avoids the loss of time consumed in . . charges; which comprises adding to molten tri drying the material. At the same time, it reduces nitrotoluene pentaerythritol tetranitrate wet the hazards of the operations by elimination of SS with more than 10% of water, removing the sepal. the drying process as well as by making it possible rated water from the surface of the blended to handle wet pentaerythritol tetranitrate, rather charge and further reducing the water content than the sensitive dry material. There is the fur by evaporation. ther advantage that the wet materia) is consider CLYDE. O. DAVIs. ably more suitable than the dry for the prepara 60 WLLAM E. KRST.