US2482091A - Method of making a high-density explosive - Google Patents

Description

Patented Sept. 20, 1949 METHOD OF'MAKING A HIGH-DENSITY EXPLOSIV'E Ludwig F. Audrieth and Dewitt D. Sager, Dower,

N. J., assignors to the United States of America as represented by the Secretary of War N Drawing. Application March 20, 1944, Serial No. 527,326

(Granted under the act of March .3, 1883, as amended April 30, 192:8; 370 0.. G. 7:57)

1 Claim.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

The present invention relates to new high ex- .plosive compositions consisting of trinitrotoluene, pentaerythritol tetranitrate, and ethylene dinitramine.

Specifically this invention relates to compositions of matter possessing high brisance and high explosive power based upon the use of a mixture consisting of pentaerythritol tetranitrate and trinitrotol-uene or a mixture of ethylene dinitramine and trinitrotoluene as carriers for ethylene din-itramine and for pentaerythritol tetranitrate, respectively, either singly or in combination to produce a ternary composition in all cases consisting of pentaerythritol tetranitrate, trinitrotoluene and ethylene dinitramine. The resulting three component explosives thus broadly specified are characterized by their superior properties as high explosive charges for use in loading and filling, preferably by cast loading, of shells, bombs, mines, bursters, grenades, various demolition charges and other ammunition.

In order to make the basis of our discoveries clear, it would be well to review briefly the status of Various useful high explosives which are now commonly employed in particular for military purposes. Binary combinationssuc'h as a mixture .of pentaerythritol tetranitrate plus trinitrotoluone, and. a mixture of ethylene dinitramine plus trinitrotoluene, are widely used as military explosives, not only because they possess satisfactory thermal stability and high brisance but also because they can be loaded into shells, bombs, mines, etc. by a process known as cast .or melt loading. Such binary combinations are commonly prepared by adding to molten trinitrotoluone either pentae'rythritol tetranitrate or ethylene dinitramine, both of which are more powerful explosives than the trinitrotoluene which serves as the carrier. In the case of the mixture comprising pentaerythritol tetranitrate and trinitrotoluene, appreciable solubility of the pentaerythg ritol .tetranitrate in the liquid is involved. Thus, for instance, a liquid melt can be prepared very easily at temperatures between 90 and 100 0, containing 30 parts by weight of pentaerythritol tetranitrate and 7.0 parts by Weight of trinitrotoluene. Melts containing higher percentages of pentaerythritol tetranitrate may also be prepared but are more viscous in view of the fact that the limit of solubility of pentaerythritol tetranitrate in trinitrotoluene is exceeded. In case of the mixture com-prising ethylene dinitramine and tri nit-rotoluene, the solubility of the ethylene dinitramine in trinitrotoluene at temperatures ordinarily employed in melt loading operations is rather limited. Ethylene dinitramine under these conditions is soluble to the extent of only 2% in molten trinitrotoluene. It is possible, however, to prepare mixtures of ethylene dinitramine and trinitrotoluene which can be cast in the form of a slurry or suspension and which possess sufliciently high fluidity to make pouring of such melts possible. Thus, a mixture consisting of 54% ethylene dinitramine and 46% trinitrotoluone is readily pourable at temperatures between and C. so that the cast loading processes can be carried out without diificulty. It should be pointed out here that the temperatures 90- l-05 C. are specified, the upper limit being the highest permissible consistent with safe operation and handling of such materials.

Such binary mixtures being capable of cast loading may, therefore, be employed to give relatively high density explosive charges of higher 'brisance and power than are obtainable with cast trinitrotoluene by itself. In all these cases, the

- resulting binary mixtures, while more sensitive to shock and impact than trinitrotoluene, are nevertheless considerably less sensitive than the added component by itself, thus reducing the hazards which attend the loading operations. It is, of course, possible to press load such materials as pure ethylene .dinitramine and pure pentaerythritol tetranitrate but high pressures are necessary to achieve high density charges with the result that operations of this sort are carried out only in special and limited cases and would not be suitable for large caliber shells, bombs or mines.

The present invention is based upon the discovery that it is possible to make use of binary mixtures such as a mixture of pentaerythritol tetranitrate plus trinitrotoluene or .a mixture of ethylene dinitramine plus trinitrotoluene for the production of ternary mixtures of high explosives which not only possess satisfactory thermal stability but are characterized by higher power and greater brisance than the binary mixtures by themselves. Thus, it is possible to make use of a mixture of pentaerythritol tetranitrate and trinitrotoluene and add to it appreciable quantities of ethylene dinitramine :to give a ternary mixture consisting of pentaerythritol tetranitrate and trinitrotoluene and ethylene din-itramine, the resulting ternary explosive composition being superior to the binary earrier from which it was prepared. Likewise, it is possible to take a mixture consisting of ethylene dinitramine and trinitrotoluene and add to such binary carrier, appreciable quantities of pentaerythritol tetranitrate, such addition resulting in the production of a high explosive composition of higher explosive power than the binary mixture which served as the carrier. It is possible in both of these instances broadly outlined hereinabove to obtain high density explosive charges which possess greater power, brisance and have more pronounced fragmentation effects than any binary compositions heretofore known in the patent literature or recorded in the pertinent art. While it is possible to prepare the desired high explosive consisting of trinitrotoluene, pentaerythritol tetranitrate and ethylene dinitramine over a wide range of combination of the three ingredients, we prefer to use those which at temperatures commonly employed in melt loading operations possess suificient fluidity so that they may be poured readily and thereby loaded by conventional loading procedures. Ternary mixtures which are not readily pourable may, however, be extruded, stemmed or lob-loaded over this same temperature range. Certain other combinations which can neither be cast nor hot-loaded, as specified can be press loaded in particular cases and for particular purposes.

Another advantage possessed by the pentaerythritol tetranitrate, trinitrotoluene, and ethylene dinitramine ternary composition is the fact that the ternary eutectic temperature is relatively high. The pentaerythritol tetranitrate, trinitrotoluene, ethylene dinitramine ternary system has an eutectic melting point at 75.8 C. It will, therefore, not tend to undergo exudation from loaded components under the ordinary conditions of storage and use.

The new explosive compositions described broadly in the above discussion can best be visualized in the exemplifications of typical ternary mixtures. In presenting such examples, it is to be understood, however, that these are not to be considered as limiting cases but are merely presented in order to make clear the significance of our discoveries as new and valuable contributions to the number of military explosives now employed.

Example I As typical of the ternary compositions wherein a mixture of pentaerythritol tetranitrate and. trinitrotoluene is used as the carrier, there has been prepared the desired high explosive composition by adding 43 part-s by weight of ethylene dinitramine to 57 parts of a liquid melt of a mixture containing pentaerythritol tetranitrate and 70% trinitrotoluene. At temperatures between 90 and 100 C. this high explosive possesses satisfactory fluidity so that it can be poured and cast readily even though it is in the form of a suspension. On cooling, this explosive gives a charge with a density of approximately 1.65 grams per cc. Its brisance, as judged by the sand test is greater than that of the mixture which acts as the liquid carrier.

Example II We have found that it is possible to use a mixture consisting of ethylene dinitramine and 50% trinitrotoluene, as a carrier for relatively large quantities of pentaerythritol tetranitrate. Thus, for instance, a readily pourable and castable ternary composition of pentaerythritol tetranitrate, trinitrotoluene and ethylene dinitramine can be prepared by adding 40 parts by weight of pentaerythritol tetranitrate to 60 parts by weight of the mixture indicated above at a temperature above to 1 0 C. Such a composition, when cast, solidifies to a density of 1.66 grams per cc. and possesses a high brisance.

There are, of course, many variations in the procedure which may be employed to prepare ternary compositions. While we base our invention upon the fact that binary mixtures of pentaerythritol tetranitrate plus trinitrotoluene and ethylene dinitramine plus trinitrotoluene may serve as carriers, this doesnot mean that we intend to be limited in the preparation of these ternary mixtures to the use of these binary systems as starting materials. It is entirely possible to prepare mixtures of the three ingredients and. then to combine these to produce a pourable ternary composition. We have also found that it is possible to dissolve the three components in acetone and to coprecipitate them either by dilution with water or by adding the acetone solution to a large excess of water. Actual process studies indicate, however, the desirability of using either the binary compositions consisting of pentaerythrito1 tetranitrate plus trinitrotoluene and ethylene dinitramine plus trinitrotoluene, both of which are standard explosive compositions, and then subsequently adding the respective third ingredient as, for instance, ethylene dinitramine to the mixture of pentaerythritol tetranitrate and trinitrotoluene, and pentaerythritol tetranitrate to the mixture of ethylene dinitramine and trinitrotoluene. It should further be mentioned that ternary compositions consisting of pentaerythritol tetranitrate, trinitrotoluene, and ethylene dinitramine can be made by suitable admixture of combinations comprising pentaerythrito1 tetranitrate plus trinitrotoluene and ethylene dinitramine plus trinitrotoluene.

We also envisage the fact that certain addends to increase pourability and to inhibit the settling of the solid phase in the molten mixture will not adversely affect ternary mixtures prepared from them. We believe that the addition of certain surface active agents, such as long chain alkyl, aralkyl and cycloalkyl sulfonated alcohol derivatives, monoand di-substituted amides, ketones, and the like, that is compounds containing a polar atom or group attached to a high molecular weight organic radical will make it possible to produce mixtures comprising ethylene dinitramine and trinitrotoluene containing a higher percentage of ethylene dinitramine than is possible without their use. Consequently, We do not wish to limit our invention to those castable and pourable ternary compositions described in the examples given above for we believe that addition of surface active agents Will make it possible to produce mixtures with still higher per centages of the third ingredient, thereby producing explosives of still higher brisance and power.

It is, of course, well known that many common explosives are much too sensitive to be used as A. P. shot fillers. In such instances, the addition of desensitizing wax in percentages varying from 1-10% of the weight of the explosive has been found to make their use feasible for armour piercing shell. The sensitivity to impact of such ternary compositions can be considerably reduced by appropriate additions of a wide variety of waxes such as carnauba, montan, paraflin waxes, etc. The use of an inert nose pad in the shell cavity also makes possible the use of certain more sensitive ternary compositions for armour piercing shell.

Where it is desired to increase the incendiary effect of an explosive filler, the addition of powdered aluminum, of magnesium, of boron, or of alloys of these elements has been found advantageous. In the case of the ternary compositions described by us, addition of percentages of such finely divided metals or alloys up to 20% will cause in like manner an increased incendiary action. Addition of these materials has the added advantage in producing greater blast effects.

It should be pointed out that all the properties of the ternary compositions broadly claimed by us indicated their superiority over the corresponding binary mixtures. They are non-hygroscopic and, therefore, will not attack or corrode metal components because of inadvertent presence of traces of moisture. The sand test values indicate the superiority of these materials as highly brisant explosives. The rates of detonation indicate, furthermore, that such mixtures should have high fragmentation action and, therefore, be particularly useful in such military devices as shells, hand grenades and anti-personnel mines. The ternary explosives, in particular those which can be cast loaded, produce fillers of high density, a factor which is of importance with respect to the power developedon a volume basis by the explosive. All the ternary mixtures are readily initiated by mercuric fulminate. Aside from these advantages, such mixtures can be cast loaded by the usual operations which are now employed for loading of other H. E. fillers.

We have now described our inventions in broad and general terms. We have indicated certain V 6 modifications and extensions which those skilled in the art will be able to recognize as coming within the scope of our disclosures. In order to more adequately summarize the general scope as well as to emphasize preferred compositions and applications, we claim:

The method of preparing a high density bursting charge including trinitrotoluene, pentaerythritol tetranitrate, and ethylenedinitramine, the said method comprising forming a suspension of ethylenedinitramine in a liquid melt of trinitrotoluene in which pentaerythritol tetranitrate is dissolved, introducing the said suspension into a cavity intended to carry the bursting charge, and solidifying the said suspension in said cavity.

LUDWIG F. AUDRETH. DEWITT D. SAGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- Number Name Date 1,996,146 Crater Apr. 2, 1935 2,011,578 Hale Aug. 20, 1935 2,346,116 Snelling Apr. 4, 1944 2,353,147 Cook July 11, 1944 FOREIGN PATENTS Number Country Date 370,600 Great Britain Apr. 14, 1935 OTHER REFERENCES Stettbacker, Nitrocellulose, vol. 11, pages 63- 67 (1940) appearing in 1941 Chem. Abs., page 4953.